[{"slug":"a-frame-roof","title":"A-Frame Roof","category":"roof-forms","type":"article","summary":"An A-frame is a building whose steep roof planes start near the ground and meet at the ridge, so the roof also forms most of the walls.","body":"An A-frame is an extreme form of steep gable roof in which the two roof planes begin at or near the foundation and rise to meet at a ridge, so that the building's cross-section resembles a capital letter A. The roof is effectively the walls as well, and interiors are often open to the rafters.\n\n## History\n\nTriangular, roof-only shelters have existed for centuries across Europe, China and the South Pacific, often as simple utilitarian structures. The modern A-frame house is usually traced to the architect R. M. Schindler, who in 1934 designed a cabin for Gisela Bennati at Lake Arrowhead, California. In 1955 Andrew Geller built the Elizabeth Reese House on Long Island; after it was featured in the New York Times in 1957, thousands of A-frames followed.\n\nFrom the mid-1950s through the 1970s A-frames became hugely popular in North America and elsewhere as vacation homes and ski chalets. Their appeal was attributed to post-war prosperity, demand for second homes, low building costs and design flexibility. Prefabricated kits, including some sold through department stores, made them even cheaper.\n\n## Characteristics\n\n- Very steep pitch, which sheds snow and rain efficiently, making the form well suited to snowy and mountain sites.\n- Simple structure of paired rafters or frames on a floor platform.\n- Tall glazed gable ends that provide views and daylight.\n- Lofts within the upper triangle.\n\n## Limitations\n\n- Much of the floor area near the side walls has low headroom, so usable space is smaller than the footprint suggests.\n- Placing windows and doors in the sloping sides requires dormers or special framing.\n- The large roof area relative to floor area affects the cost of roofing and insulation.\n\n## Contemporary use\n\nA-frames have seen renewed interest in the 21st century as cabins, glamping units and small houses, often with metal or shingle roofs.","key_facts":[{"label":"First modern A-frame house","value":"Bennati cabin, R. M. Schindler, 1934"},{"label":"Peak popularity","value":"Mid-1950s to 1970s"},{"label":"Strength","value":"Sheds snow well"}],"regions":["North America","Europe","Global"],"aliases":["A-frame house","A-frame cabin","A-frame chalet"],"related":["gable-roof","rafter","roof-pitch"],"company":null,"sources":[{"title":"A-frame house","url":"https://en.wikipedia.org/wiki/A-frame_house","publisher":"Wikipedia"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"}],"country":null},{"slug":"acrylic-roof-coating","title":"Acrylic Roof Coating","category":"low-slope-systems","type":"term","summary":"A water-based elastomeric coating, usually white, applied to low-slope roofs for reflectivity and weather protection; generally not suited to ponding water.","body":"Acrylic roof coatings are water-based elastomeric coatings made from acrylic polymer emulsions with pigments, typically titanium dioxide for white products, and fillers. They dry by evaporation into a flexible film that stretches and recovers with roof movement.\n\n## Uses\n\n- reflective cool-roof coatings over existing membranes, metal roofs and modified bitumen\n- protective top coat on spray polyurethane foam roofs\n- restoration of weathered single-ply and bituminous roofs, often with polyester fabric at seams and details\n\nAcrylics are among the most widely used restoration coatings. The NYC CoolRoofs programme, for example, applied acrylic elastomeric coatings to roof membranes across New York City.\n\n## Advantages\n\n- high initial solar reflectance in white\n- easy application by spray or roller and water clean-up\n- low odour and low solvent content\n- relatively low cost\n\n## Limitations\n\n- **Ponding water:** acrylic coatings soften and can lose adhesion under standing water, and acrylic manufacturers typically do not warrant ponding areas. Drainage must be corrected first, or a different coating used in low spots.\n- **Weather during application:** rain, dew or freezing before the film dries can wash out or damage it, so acrylics need warm, dry conditions.\n- **Film build:** each coat is relatively thin, so several coats are often needed to reach the specified dry film thickness.\n\n## Maintenance\n\nReflectance falls as dirt accumulates; cleaning and periodic recoating restore performance.\n\n## Standards and ratings\n\nCool-roof coatings are rated for solar reflectance and thermal emittance by the Cool Roof Rating Council, whose directory lists more than 500 coatings. ENERGY STAR criteria for low-slope roof products set minimum solar reflectance of 0.65 initially and 0.50 after weathering.","key_facts":[{"label":"Base","value":"Water-borne acrylic emulsion"},{"label":"Cure","value":"Dries by evaporation"},{"label":"Ponding","value":"Typically not warranted"},{"label":"Main use","value":"Cool-roof restoration, SPF top coat"},{"label":"ENERGY STAR low-slope reflectance","value":"0.65 initial; 0.50 aged"}],"regions":["Global","North America"],"aliases":["acrylic elastomeric coating","white roof coating"],"related":["roof-coating","silicone-roof-coating","spray-polyurethane-foam-roofing","cool-roof","ponding-water"],"company":null,"sources":[{"title":"Roof coating","url":"https://en.wikipedia.org/wiki/Roof_coating","publisher":"Wikipedia"},{"title":"Cool roof","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"},{"title":"RICOWI Roof Guide: Spray Foam","url":"https://ibhs.org/guidance/ricowi-roof-guide-spray-foam/","publisher":"IBHS / RICOWI"},{"title":"Cool Roofs","url":"https://www.energy.gov/energysaver/cool-roofs","publisher":"U.S. Department of Energy"}],"country":null},{"slug":"alaskan-yellow-cedar","title":"Alaskan Yellow Cedar","type":"term","summary":"A slow-growing Pacific Northwest cypress whose hard, durable wood is used for premium shingles, shakes and heritage roof repairs.","body":"Alaskan yellow cedar, also called yellow cedar, Alaska cedar, Nootka cypress or yellow cypress, is a conifer of the Pacific Northwest coast. Its scientific name has changed several times (*Callitropsis*, *Cupressus* or *Chamaecyparis nootkatensis*). Despite the common name it is a cypress, not a true cedar.\n\n## Range\n\nThe tree grows in coastal mountains from the Kenai Peninsula in Alaska to the Klamath Mountains of northern California, including the Cascades, usually at higher elevations than western red cedar, and near the tree line it can grow as low, stunted krummholz.\n\n## Wood properties\n\nSlow growth makes the wood relatively hard. It has a uniform colour, straight grain and good dimensional stability, and resists weather, insects and ground contact. It works easily with tools, holds nails well, resists splintering and wears smoothly. Anti-fungal compounds help the living tree reach a great age, although it is still susceptible to heart rot. Freshly cut wood has a bitter smell that fades once seasoned.\n\n## Roofing uses\n\nYellow cedar is used for shingles, shakes and siding, especially where a long-lived, uniform-coloured product is wanted. In historic preservation it is used as a substitute for western red cedar and bald cypress when suitable old-growth stock of those species is hard to find. Its high cost generally limits it to premium and finish work.\n\n## Supply concerns\n\nLarge-scale die-offs of yellow cedar linked to climate change have affected more than 7% of the species' range. The US Fish and Wildlife Service has been reviewing whether to list it as threatened or endangered, which could affect future availability.\n","key_facts":[{"label":"Botanical name","value":"Callitropsis (Cupressus) nootkatensis"},{"label":"Range","value":"Kenai Peninsula, Alaska, to northern California"},{"label":"Notable trait","value":"Hard, stable, uniform colour"},{"label":"Supply issue","value":"Die-off over more than 7% of range"}],"regions":["North America"],"aliases":["yellow cedar","Alaska cedar","Nootka cypress","yellow cypress"],"related":["western-red-cedar","wood-shingle","wood-shake"],"sources":[{"title":"Cupressus nootkatensis","url":"https://en.wikipedia.org/wiki/Cupressus_nootkatensis","publisher":"Wikipedia"},{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"algae-resistant-shingle","title":"Algae-Resistant Shingle","type":"term","summary":"An asphalt shingle containing copper- or zinc-coated granules that release ions to inhibit the dark streaks caused by roof algae.","body":"An algae-resistant shingle is an asphalt shingle that includes a proportion of granules coated with copper or, less commonly, zinc compounds. When rain and dew wet the roof, these granules slowly release metal ions that inhibit the growth of blue-green algae, the cause of the black or dark-brown streaks seen on many shingle roofs in humid climates.\n\n## The streaking problem\n\nThe streaks are usually caused by the cyanobacterium *Gloeocapsa magma*. It thrives where dew, humidity and shade keep the roof damp, and it often appears first on north-facing slopes. In very humid regions, one manufacturer reports that streaks can appear within about three years of installation and spread over time. The algae are generally regarded as a cosmetic problem rather than a cause of structural damage, although dark streaks can raise surface temperature slightly.\n\n## How the protection works\n\nCopper-coated granules are blended in with the normal colour granules so they are not visible. One manufacturer states that its algae-resistant products use at least a 10% blend of copper granules. The protection is preventive: it aims to stop algae from establishing rather than to remove existing growth. Over decades the copper is gradually depleted.\n\nAlgae warranties are usually separate from the main shingle warranty and much shorter, often 5-10 years in older products and longer in some current lines. They typically cover only *Gloeocapsa magma*, not moss, lichen, mould or other growths.\n\n## Alternatives and maintenance\n\n- Strips of bare zinc or copper installed near the ridge release ions when rain runs over them and can reduce growth on the slope below.\n- Existing streaks can be removed with dilute bleach-based cleaners applied at low pressure.\n- High-pressure washing is discouraged because it strips granules and shortens shingle life.\n","key_facts":[{"label":"Main organism","value":"Gloeocapsa magma (cyanobacterium)"},{"label":"Active ingredient","value":"Copper (sometimes zinc) coated granules"},{"label":"Typical copper blend","value":"At least 10% of granules (one manufacturer)"}],"regions":["North America","Global"],"aliases":["AR shingle","algae-resistant roofing","copper granule shingle"],"related":["roofing-granules","asphalt-shingle","roof-algae"],"sources":[{"title":"Algae resistant granules","url":"https://www.malarkeyroofing.com/features/algae-resistant-granules/","publisher":"Malarkey Roofing Products"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Asphalt Shingle Types (3-Tab vs. Laminated Architectural), ASTM Classifications & Thermal Behavior","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-types-astm-thermal","publisher":"Open Exam Prep"}],"category":"materials","company":null,"country":null},{"slug":"alligatoring","title":"Alligatoring","category":"problems-maintenance","type":"term","summary":"A pattern of shrinkage cracks resembling alligator skin on aged asphalt, coal-tar or coated roof surfaces exposed to sun and heat.","body":"Alligatoring is the cracking of a bituminous roof surface into a network of roughly rectangular or polygonal segments, so the surface looks like reptile skin. It is most associated with smooth-surfaced or inadequately protected built-up roofs, asphalt coatings, and flood coats that have been exposed to sunlight and heat for years. Related terms include crazing (fine surface cracks) and checking.\n\n## Causes\n\nAsphalt and coal tar are kept flexible by lighter oils. Ultraviolet radiation, heat and oxygen gradually drive off and oxidise these oils, so the surface becomes hard and brittle. At the same time, daily heating and cooling makes the surface expand and contract. Once it can no longer stretch, it cracks into a pattern. Surfaces without enough gravel or reflective coating, or with too thick a layer of bitumen applied at once, are more vulnerable. Some coatings applied over incompatible substrates can also alligator as they cure.\n\n## Why it matters\n\nEarly alligatoring may be limited to the top surface. As the cracks deepen, they expose the underlying felts or reinforcement to weather and allow water to enter. Water in the cracks can then freeze, widening them further. Left alone, alligatoring is a step toward splits, leaks and wet insulation.\n\n## Identification\n\nThe pattern is visible to the eye, typically over large open areas rather than at isolated spots. Inspectors check crack depth: shallow surface crazing differs from cracking that reaches the plies. They also look for loss of surfacing aggregate, which often goes hand in hand with alligatoring on gravel-surfaced built-up roofs.\n\n## Treatment\n\nWhere the cracks are shallow and the membrane beneath is sound, cleaning and recoating, or restoring the gravel surfacing, can extend service life. Coatings and primers must be compatible with the existing bitumen. Deep cracking with wet insulation underneath usually means recover or replacement. Routine inspection, at least twice a year on low-slope roofs, helps catch the condition early.","key_facts":[{"label":"Typical roofs","value":"Built-up roofing, asphalt coatings, flood coats"},{"label":"Main driver","value":"UV and heat oxidising bitumen oils"},{"label":"Early treatment","value":"Clean and recoat or restore surfacing"}],"regions":["Global"],"aliases":["alligator cracking","crazing","checking"],"related":["built-up-roofing","roof-coating","ponding-water","roof-maintenance-checklist","roof-moisture-survey"],"company":null,"sources":[{"title":"Common Problems With Built-Up Roof Systems","url":"https://facilitiesnet.com/roofing/article.aspx?id=15980","publisher":"Facilitiesnet"},{"title":"See you later, alligator-ing","url":"https://www.rooferscoffeeshop.com/post/see-you-later-alligator-ing","publisher":"RoofersCoffeeShop"},{"title":"Technical Details: Why All Roofs Need Maintenance","url":"https://roofingcontractor.com/articles/85285-technical-details-why-all-roofs-need-maintenance","publisher":"Roofing Contractor"}],"country":null},{"slug":"altdeutsche-deckung","title":"Altdeutsche Deckung","category":"installation","type":"term","summary":"The 'Old German' slating method, using hand-dressed slates of graded sizes laid in rising courses; regarded as the most demanding German slate technique.","body":"The **Altdeutsche Deckung** (\"Old German covering\", also *Altdeutsche Schieferdeckung*) is a traditional German method of slating in which slates of varying height and width are laid in courses that rise at an angle across the roof. It is the classic slate roof of the Rhineland and the German uplands, and German roofers call it the \"queen of laying methods\" (*Königin der Deckarten*) because it is difficult and demanding to execute.\n\n## How it works\n\n- **Shaped slates.** Each slate is dressed to a set outline. The shape of the cut, the *Hieb*, comes in standard variants: normal, sharp (*scharfer Hieb*) and blunt (*stumpfer Hieb*).\n- **Rising courses.** The courses (*Gebinde*) are not parallel to the eaves but climb diagonally across the roof. This rise (*Gebindesteigung*) lets water run off sideways along the lap. The steeper the roof, the smaller the rise needed.\n- **Graded sizes.** Course heights reduce from the eaves to the ridge, with the largest slates at the eaves, where most water flows, and the smallest at the ridge. Depending on rafter length, the difference between the largest and smallest course is about 40-80 mm (1.6-3.1 in). Grading also makes the roof look taller.\n\nBecause slates can be sized and shaped to suit, the method adapts well to complex roofs with towers, dormers, valleys and curves.\n\n## Related methods\n\n- **Wilde Deckung** (\"wild covering\") follows the same principles but uses undressed stones that the roofer shapes on site.\n- A **template variant** uses the same slate geometry in uniform sizes, giving a flatter, more regular appearance.\n- The **French method** (*Französische Deckung*) uses rhombic or hexagonal slates laid in courses parallel to the eaves.\n\n## Background\n\nSlate roofing on the Rhine and Mosel goes back to the Romans, who laid slate in bonded patterns to fixed rules, and the craft reached a high point in the Middle Ages. Reference sources describe the Altdeutsche method, with irregular rhombic slates laid diagonally to the eaves, as the most common form in the Rhineland.\n\n## German slating compared\n\nGerman slating uses roughly 250 slate formats, generally 4-6 mm (about 0.16-0.24 in) thick, about 5 mm (0.2 in) on average, and a wide range of laying methods. French practice concentrates on about 10-15 rectangular formats, 2.5-4 mm thick, while British slating uses only rectangular slates, often large. Slate roofers in Germany are trained at the federal training centre (BBZ) in Mayen.\n\n## Sources and gaps\n\nMinimum pitches for the method under the ZVDH technical rules: published information is limited.","key_facts":[{"label":"Meaning","value":"Old German (slate) covering"},{"label":"Course layout","value":"Rising (diagonal) courses"},{"label":"Slate sizes","value":"Graded, largest at eaves"},{"label":"Course height range","value":"About 40-80 mm (1.6-3.1 in) difference"},{"label":"Cut variants","value":"Normal, sharp and blunt Hieb"}],"regions":["Europe"],"aliases":["Old German slating","Altdeutsche Schieferdeckung","Old German method"],"related":["natural-slate","german-roofing-slate","slate-roof-installation","roofing-in-germany","zvdh-fachregeln","slaters-hammer"],"company":null,"sources":[{"title":"Altdeutsche Deckung","url":"https://de.wikipedia.org/wiki/Altdeutsche_Deckung","publisher":"Wikipedia (German)"},{"title":"Historische Dachdeckungen","url":"https://www.baunetzwissen.de/altbau/fachwissen/dach-deckungen/historische-dachdeckungen-2949105","publisher":"Baunetz Wissen"}],"country":null},{"slug":"aluminum-roofing","title":"Aluminium Roofing","category":"materials","type":"article","summary":"Aluminium roofing uses light, rust-free aluminium alloy sheet, usually factory-painted, and is favoured near salt water where coated steel corrodes faster.","body":"Aluminium roofing is made from rolled aluminium alloy sheet formed into standing seam panels, corrugated or ribbed sheets, shingles and press-formed tiles. Aluminium does not rust in the way steel does. Aluminium contains no iron, and its surface forms a thin, hard oxide layer that seals the metal and re-forms if scratched, which is why aluminium is widely used on coastal buildings.\n\n## Alloys and thickness\n\nRoofing sheet is often a 3000-series alloy such as 3105 or 3003, in a work-hardened temper such as H24. Aluminium is lighter than steel at the same thickness and is usually specified in thousandths of an inch or in millimetres rather than by gauge. Residential roofing typically ranges from about 0.019 in (0.48 mm), used for flashing and some stamped shingles, to about 0.040 in (1.02 mm); standing seam pans are often 0.032 in (0.81 mm) or heavier. Temper and profile geometry (ribs, striations, stamped texture) affect stiffness as much as thickness.\n\n## Strengths\n\n- Good corrosion resistance in marine air, where the sacrificial coatings on steel are consumed faster.\n- Light weight.\n- Recyclable at end of life.\n\n## Limitations\n\n- **Thermal movement**: aluminium expands about 23 x 10^-6 per degree C (about 12.8 x 10^-6 per degree F), roughly twice as much as steel. Panels must be allowed to move, typically with sliding clips; pinning them rigidly pushes the movement into stressed fasteners, noise or waviness.\n- **Denting**: aluminium is less stiff than steel of the same thickness, so thin, flat aluminium dents more easily; thicker sheet and textured or ribbed profiles resist denting.\n- **Appearance**: roofing aluminium is normally factory-painted, usually with a PVDF finish, for colour and UV resistance rather than for corrosion protection.\n- **Compatibility**: aluminium is anodic to copper, stainless steel and carbon steel. It should not be in contact with copper or receive run-off from copper, and fasteners should be compatible (typically stainless or aluminium).\n\nAluminium systems typically cost more upfront than coated steel and much less than copper.","key_facts":[{"label":"Typical alloy","value":"3000 series (e.g. 3105, 3003)"},{"label":"Typical residential thickness","value":"About 0.019-0.040 in (0.48-1.02 mm); standing seam often 0.032 in (0.81 mm)"},{"label":"Thermal expansion","value":"About 23 x 10^-6/K (12.8 x 10^-6/F)"},{"label":"Main advantage","value":"Corrosion resistance in coastal environments"}],"regions":["Global"],"aliases":["aluminum roofing","aluminium roof","aluminum metal roof"],"related":["galvanic-corrosion","thermal-movement-in-metal-roofs","pvdf-coating","standing-seam-metal-roof","sheet-metal-gauge"],"company":null,"sources":[{"title":"Busting 5 Metal Roofing Myths","url":"https://www.rooferscoffeeshop.com/post/busting-5-metal-roofing-myths-2","publisher":"RoofersCoffeeShop"},{"title":"Coefficients of Linear Thermal Expansion","url":"https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html","publisher":"The Engineering ToolBox"},{"title":"Galvanic corrosion","url":"https://en.wikipedia.org/wiki/Galvanic_corrosion","publisher":"Wikipedia"},{"title":"Sheet metal","url":"https://en.wikipedia.org/wiki/Sheet_metal","publisher":"Wikipedia"},{"title":"Aluminum Roofing Gauge & Thickness Explained (2026)","url":"https://www.interlockroofing.com/kb/aluminum-roofing-gauge-thickness/","publisher":"Interlock Roofing"},{"title":"Thermal Expansion & Oil Canning in Aluminum Roofs Explained","url":"https://www.interlockroofing.com/kb/aluminum-roof-thermal-expansion-oil-canning/","publisher":"Interlock Roofing"},{"title":"Aluminum vs. Steel Roofing: Which Is Better?","url":"https://www.interlockroofing.com/kb/aluminum-vs-steel-roofing/","publisher":"Interlock Roofing"}],"country":null},{"slug":"ambohimanga-royal-houses","title":"Ambohimanga Royal Houses","category":"world-roofing","type":"place","summary":"Royal timber houses on the hill of Ambohimanga, Madagascar, including Andrianampoinimerina's rosewood house with a peaked roof on a 10 m pillar; UNESCO 2001.","body":"Ambohimanga is a fortified royal hill near Antananarivo, associated with the Merina kingdom of the central highlands. Inscribed on the World Heritage List in 2001, it preserves a royal city of two palaces, a pavilion, sacred basins, tombs and fourteen stone gateways. Following highland custom, the houses of the living were built of wood and plant materials, and the tombs of the dead of stone.\n\n## Andrianampoinimerina's house\n\nThe Mahandrihono compound was established by Andriambelomasina between 1710 and 1730. King Andrianampoinimerina later replaced its twin houses with a larger residence, which survives:\n\n- **Walls**: solid rosewood.\n- **Roof**: steep and peaked, supported by a central rosewood pillar 10 m (33 ft) tall.\n- **Covering**: originally thatched; the thatch was later replaced with wooden shingles, but the house is otherwise preserved in its original state.\n- **Ornament**: silver-plated roof horns (*tandrotrano*) where the gable beams cross, a silver eagle once at the ridge, and silver ornaments in the interior roof corners.\n\nIn February 2012 Cyclone Giovanna tore off the wooden shingles, exposing the interior, and badly damaged the compound's timber fence.\n\n## Other buildings\n\n- **Fandriampahalemana**: a rosewood palace built in 1871.\n- **Tranofitaratra** (\"house of glass\"): dated to 1862.\n- **Bevato**: the earliest compound, established before 1710; its buildings were destroyed under French rule and a school built on the site.\n\n## Tomb houses\n\nThe compound held twelve royal tombs, each a stone crypt topped by a small windowless wooden house (*tranomasina*). In March 1897 the French colonial authorities destroyed the tomb houses and removed the royal remains to Antananarivo. The Malagasy state rebuilt the sacred wooden houses in 2008, following traditional rites, building rules and choices of timber. Restoration since 1996 has used traditional Malagasy techniques and materials, and since 2006 the site has been managed by the Office of the Cultural Site of Ambohimanga (OSCAR).","key_facts":[{"label":"Location","value":"Ambohimanga, near Antananarivo, Madagascar"},{"label":"Roof","value":"Steep peaked roof, thatch later replaced by wooden shingles"},{"label":"Central pillar","value":"Rosewood, 10 m (33 ft)"},{"label":"UNESCO inscription","value":"2001"},{"label":"Tomb houses rebuilt","value":"2008"}],"regions":["Africa"],"aliases":["Royal Hill of Ambohimanga","Mahandrihono"],"related":["roofing-in-madagascar","tandrotrano","wood-shingle","thatch"],"company":null,"sources":[{"title":"Ambohimanga","url":"https://en.wikipedia.org/wiki/Ambohimanga","publisher":"Wikipedia"},{"title":"Royal Hill of Ambohimanga","url":"https://whc.unesco.org/en/list/950/","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"amrize","title":"Amrize","category":"manufacturers","type":"company","summary":"Amrize is the North American building-materials company spun off from Holcim in June 2025; its roofing brands include Elevate and Malarkey.","body":"Amrize is a building-materials company formed from the North American business of the Swiss group Holcim. The separation was completed on 23 June 2025, when Amrize began trading as an independent, publicly listed company. Its activities include cement and aggregates as well as building envelope products, among them several of the largest commercial and residential roofing brands in North America.\n\n## Origins\n\nHolcim built up a North American roofing business in the early 2020s. It completed the purchase of Firestone Building Products from Bridgestone on 1 April 2021 and renamed it Elevate in June 2022. In 2022 it also bought Malarkey Roofing Products, a residential shingle maker based in Portland, Oregon. These businesses were part of the North American operations that Holcim decided to separate from its global group, with a full capital-market split.\n\n## Roofing brands\n\n- **Elevate**: commercial low-slope roofing, including EPDM, TPO and PVC single-ply membranes, polyiso insulation and accessories, with a head office in Nashville, Tennessee.\n- **Malarkey**: residential asphalt shingles and underlayments.\n\n## Significance\n\nWith the separation, the former Firestone and Malarkey roofing businesses passed from a Swiss-headquartered parent to a stand-alone company focused on North America. Holcim itself remains listed on the SIX Swiss Exchange and retains its operations outside North America.\n\n## Commercial roofing context\n\nLow-slope commercial roofs in North America are commonly covered with single-ply membranes such as EPDM, TPO or PVC laid over rigid insulation. Because these roofs are replaced on a cycle of decades, demand comes largely from re-roofing existing buildings rather than from new construction, which gives roofing businesses a steadier revenue profile than cement and aggregates.","key_facts":[{"label":"Formed","value":"23 June 2025 (spin-off from Holcim)"},{"label":"Roofing brands","value":"Elevate, Malarkey"},{"label":"Region","value":"North America"}],"regions":["North America"],"aliases":["Amrize Ltd"],"related":["holcim-elevate","malarkey-roofing-products","epdm-roofing","tpo-roofing","pvc-roofing"],"company":{"founded":"2025","known_for":["Elevate commercial roofing","Malarkey shingles","Cement and aggregates"]},"sources":[{"title":"Holcim","url":"https://en.wikipedia.org/wiki/Holcim","publisher":"Wikipedia"},{"title":"Elevate","url":"https://www.elevatecommercialbp.com/us-en","publisher":"Elevate"},{"title":"Amrize Ltd Form 10-K FY2025","url":"https://www.sec.gov/Archives/edgar/data/2035989/000203598926000017/holcim-20251231.htm","publisher":"US SEC"}],"country":null},{"slug":"ancient-greek-roof-tiles","title":"Ancient Greek Roof Tiles","category":"history","type":"article","summary":"How the Greeks developed interfitting terracotta and marble roof tiles, beginning with the 7th-century BCE Protocorinthian system at Corinth.","body":"Greek temples are remembered for their stone columns, but their roofs were just as important technically. Greek builders developed sophisticated systems of moulded terracotta tiles, and later marble tiles, that set the pattern for Roman and much later European roofing.\n\n## Earlier flat tiles\n\nFlat, rectangular ceramic tiles without interfitting parts were already used on corridor houses of the Greek mainland in the Early Bronze Age, around 2650-2200 BCE. These were simple coverings rather than a coordinated system.\n\n## The Protocorinthian system\n\nThe earliest interfitting tiled roof yet identified in the archaeological record belongs to the Old Temple at Corinth, a 7th-century BCE building that preceded the later Temple of Apollo there. Archaeologists call its tiling the **Protocorinthian system**. Research by the American School of Classical Studies at Athens has compared how tiles were made for buildings at Corinth, Isthmia, Perachora and Delphi. Some scholars also discuss early tiled roofs at Argos; the precise sequence of first use in the Peloponnese is still being studied.\n\n## Making the tiles\n\nGreek tile makers pressed wet clay into four-sided moulds, trimmed it, often with a wire, and fired it in a kiln. Moulds grew more sophisticated over time. Flat pan tiles (later called *tegulae* in Latin) were overlapped by curved or angled cover tiles (*imbrices*).\n\n## Marble and metal\n\nFrom around 620 BCE marble tiles were used on the most prestigious buildings. Marble could be cut much larger than clay, and marble roofs covered the Temple of Zeus at Olympia and the Parthenon in Athens. Bronze and gilded tiles were rarer still.\n\n## Ornament and drainage\n\nRows of decorated **antefixes** closed the open ends of the cover tiles along the eaves. Gutters along the sides of formal buildings often had spouts in the shape of lions' heads. Much of the painted terracotta ornament from Corinth survives and helps archaeologists date buildings.\n\n## Legacy\n\nThe Greek split between pan and cover tile passed to Rome, and from Rome to Mediterranean and Latin American tile traditions. The word *imbrication*, meaning overlapping layers, comes from the same root as *imbrex*.","key_facts":[{"label":"Earliest interfitting system found","value":"Old Temple, Corinth, 7th century BCE"},{"label":"Marble tiles first used","value":"About 620 BCE"},{"label":"Notable marble roofs","value":"Parthenon; Temple of Zeus, Olympia"}],"regions":["Europe"],"aliases":["Protocorinthian roof","Greek terracotta roof tiles"],"related":["earliest-fired-clay-roof-tiles","imbrex-and-tegula","antefix","clay-roof-tile"],"company":null,"sources":[{"title":"Research Spotlight: Roof Tile Manufacturing Techniques","url":"https://www.ascsa.edu.gr/news/newsDetails/sapirstein-dissertation","publisher":"American School of Classical Studies at Athens"},{"title":"Imbrex and tegula","url":"https://en.wikipedia.org/wiki/Imbrex_and_tegula","publisher":"Wikipedia"},{"title":"Reconstructing the earliest known composite-tiled roofs from the Chinese Loess Plateau","url":"https://www.nature.com/articles/s41598-023-35299-x","publisher":"Scientific Reports (Nature Portfolio)"}],"country":null},{"slug":"andean-ichu-thatch","title":"Andean Ichu Thatch","category":"world-roofing","type":"article","summary":"Grass thatch of the high Andes, made from ichu bunchgrass and used on Inca buildings, tied to stone gables with pegs and rope.","body":"Andean ichu thatch is the traditional grass roofing of the high Andes of Peru, Bolivia and neighbouring countries. It is made from coarse bunchgrasses of the altiplano, chiefly *ichu* (*Jarava ichu*, formerly *Stipa ichu*), a name that comes from the Quechua word for straw. The grass is also known as Peruvian feathergrass, *paja brava* and *paja ichu*, and grows from Mexico and Central America through the Andes to Chile and Argentina.\n\n## Inca roofs\n\nThe Inca state, which flourished from about 1425 until 1532, built its famous fitted-stone walls but roofed most buildings with thatch. According to the World History Encyclopedia, Inca roofs were made of grass or reed thatch laid on poles of wood or cane tied together with rope. The poles were secured to the stone walls by projecting stone pegs, either set into the masonry or carved from the same block, and some gable tops carried a stone ring for tying down the roof. In wetter areas the pitch was steep, often about 60 degrees, to shed rain quickly.\n\nInca stonework of this kind survives at many sites, including Machu Picchu, founded around 1450 and inscribed by UNESCO in 1983, although the original thatch has long since perished. Large public halls (*kallanka*), with several doorways onto a plaza, were also roofed in this way.\n\n## Grass rope and communal work\n\nThe same grass is twisted into rope. The best-known example is the Q'eswachaka suspension bridge in Peru, which Quechua communities rebuild every year over three days. Families twist straw into thin cords about 70 m (230 ft) long, which are combined into thicker ropes and finally braided into six main cables tied to ancient stone abutments. UNESCO added the knowledge, skills and rituals of the renewal to its Representative List of the Intangible Cultural Heritage of Humanity in 2013. The tradition shows the skill in harvesting, twisting and tying grass that Andean thatching also depends on.\n\n## Thatch today\n\nGrass thatch has largely given way to metal and fibre-cement sheet. In Peru's 2017 census, 2.9% of occupied dwellings had roofs of straw, palm leaves or similar materials, against 39.2% with metal (*calamina*) or fibre-cement sheets. Bolivia's 2015 household survey estimated 6.4% of households with roofs of straw, cane, palm or mud.","key_facts":[{"label":"Main grass","value":"Ichu (Jarava ichu, syn. Stipa ichu)"},{"label":"Meaning","value":"Quechua for 'straw'"},{"label":"Inca fixing","value":"Poles tied to stone pegs and gable rings"},{"label":"Typical pitch","value":"About 60 degrees in wetter areas"},{"label":"Related tradition","value":"Q'eswachaka bridge renewal (UNESCO ICH 2013)"}],"regions":["Latin America"],"aliases":["Inca thatch","ichu thatch","paja ichu roof","Inca roof"],"related":["thatch","roofing-in-peru","roofing-in-bolivia","roofing-in-argentina-and-chile","uros-totora-houses","prehistoric-shelters-and-early-thatch"],"company":null,"sources":[{"title":"Inca Architecture","url":"https://www.worldhistory.org/Inca_Architecture/","publisher":"World History Encyclopedia"},{"title":"Jarava ichu","url":"https://en.wikipedia.org/wiki/Jarava_ichu","publisher":"Wikipedia"},{"title":"Knowledge, skills and rituals related to the annual renewal of the Q'eswachaka bridge","url":"https://ich.unesco.org/en/RL/knowledge-skills-and-rituals-related-to-the-annual-renewal-of-the-qeswachaka-bridge-00594","publisher":"UNESCO Intangible Cultural Heritage"},{"title":"En el país existen más de diez millones de viviendas particulares censadas","url":"https://m.inei.gob.pe/prensa/noticias/en-el-pais-existen-mas-de-diez-millones-de-viviendas-particulares-censadas-10893/","publisher":"INEI Perú"},{"title":"Encuesta de Hogares 2015: material más utilizado en los techos (s1a_09)","url":"https://anda4.ine.gob.bo/ANDA4_3/index.php/catalog/497/variable/V1618?pdf=1","publisher":"Instituto Nacional de Estadística de Bolivia"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"}],"country":null},{"slug":"animal-damage","title":"Animal and Bird Damage to Roofs","category":"problems-maintenance","type":"article","summary":"Damage by squirrels, raccoons, rats, birds, possums and insects that chew, tear or nest in roofs, vents, soffits and attics.","body":"Animals and birds damage roofs by tearing into them to reach shelter in the attic, by nesting in vents and gutters, and by leaving debris and droppings that block drainage and corrode materials. The species vary by region: squirrels, raccoons, rats and mice, bats and birds in North America and Europe; possums in Australia and New Zealand; monkeys in parts of South and Southeast Asia; and insects such as termites and wood-boring beetles in many climates.\n\n## Typical damage\n\n- **Chewed or torn openings** at roof vents, plumbing boots, soffits, fascia corners, gable vents and the junction where a lower roof meets a wall. Squirrels and rats can gnaw through plastic vents and thin wood; raccoons can pull up shingles and rip open soffit panels.\n- **Nesting** in gutters, valleys, chimneys and vents, causing blockages and moisture problems.\n- **Lifted tiles and ridge pieces** where birds or animals get underneath.\n- **Contaminated insulation** with droppings and urine in the attic.\n- **Pecking** by woodpeckers on wood siding and trim, and by some birds at sealant and membranes.\n- **Gravel or ballast displacement** by birds on low-slope roofs.\n\n## Signs\n\nNoises in the attic at dawn and dusk, debris on the ground below the eaves, gnaw marks, displaced insulation, droppings, and unexplained leaks near vents.\n\n## Exclusion and repair\n\nWildlife professionals generally recommend removing animals humanely before sealing entry points, often using one-way exits, and avoiding sealing during breeding seasons when young may be trapped inside. Local wildlife laws can restrict trapping or relocation of certain species, and bats and many birds are legally protected in many countries. Repairs then use durable materials: metal vent guards, heavy-gauge mesh over gable and soffit vents, chimney caps, and reinforced soffit corners. Trimming branches that overhang the roof removes an easy access route. Damaged insulation and roofing are replaced once the animals are out.","key_facts":[{"label":"Common entry points","value":"Roof vents, soffits, fascia corners, roof-wall junctions"},{"label":"Key rule","value":"Remove animals before sealing openings"},{"label":"Legal note","value":"Bats and many birds are protected in many countries"}],"regions":["Global"],"aliases":["wildlife damage","pest damage","bird damage","squirrel damage"],"related":["soffit","fascia","gutter-problems","thatch-maintenance","wood-rot"],"company":null,"sources":[{"title":"When animals invade your attic","url":"https://www.canr.msu.edu/news/when_animals_invade_your_attic","publisher":"Michigan State University Extension"},{"title":"How squirrels enter your attic through a roof vent","url":"https://www.skedaddlewildlife.com/blog/squirrels-enter-attic-roof-vent/","publisher":"Skedaddle Humane Wildlife Control"},{"title":"Raccoon Damage to Roofs, Soffits, and Attics","url":"https://www.hamiltonwildlife.ca/?p=5386","publisher":"Hamilton Wildlife Control"}],"country":null},{"slug":"fm-4473","title":"ANSI/FM 4473","summary":"ANSI/FM 4473 rates the hail resistance of rigid roofing such as tile, slate and metal by firing ice balls at it, from Class 1 to Class 4.","body":"ANSI/FM 4473, *Specification Test Standard for Impact Resistance Testing of Rigid Roofing Materials by Impacting with Freezer Ice Balls*, was developed by FM Approvals and is an American National Standard. It is the main alternative to [UL 2218](/ul-2218) for rating hail resistance, and it is used mostly for rigid products such as clay and concrete tile, slate, and some metal and composite products.\n\n## How the test works\n\nIce balls are made by freezing water in controlled moulds and then fired from an air cannon at a 3 by 3 ft (0.9 by 0.9 m) specimen of new material. The test is run at a temperature between 60 and 90 °F (16–32 °C). Each target location receives two coincident impacts, and at least two locations are tested.\n\nThe four classes correspond to nominal ice ball diameters:\n\n- **Class 1** – 1.25 in (32 mm)\n- **Class 2** – 1.5 in (38 mm)\n- **Class 3** – 1.75 in (44 mm)\n- **Class 4** – 2.0 in (51 mm)\n\nA 2 in ice ball weighing about 0.135 lb (61 g) travels at roughly 117 ft/s (about 80 mph, 129 km/h) and carries around 29.5 ft-lb (40 J) of energy, according to one technical summary. To pass a class, the sample must show no visible cracking, breakage or perforation.\n\n## Why ice rather than steel\n\nReal hail can shatter or flatten when it strikes. Ice balls spread their energy differently than solid steel balls, which deliver a sharp point load. Supporters of FM 4473 argue that steel-ball tests unfairly penalize brittle materials like tile and slate. Because the methods differ, a product can pass one and fail the other, so ratings are not interchangeable.\n\n## Where it is required\n\nThe IBHS [FORTIFIED Roof](/ibhs-fortified-roof) program's hail supplement accepts tile rated Class 4 under FM 4473, while metal and low-slope systems are expected to meet UL 2218 Class 4. FM Approvals also uses impact testing within its roofing approval standards, and FM Approvals publishes a separate standard, 4475, for roof components in hail-prone regions.\n\n## Limitations\n\nLike any lab test, FM 4473 uses new material at mild temperatures. Ageing, cold brittleness, and wind-driven hail at an angle can all make real damage worse than test results suggest.","key_facts":[{"label":"Developer","value":"FM Approvals (American National Standard)"},{"label":"Projectile","value":"Freezer ice balls fired by air cannon"},{"label":"Specimen","value":"3 x 3 ft (0.9 x 0.9 m)"},{"label":"Classes","value":"1–4 (1.25–2.0 in / 32–51 mm ice balls)"},{"label":"Typical use","value":"Tile, slate and other rigid roofing"}],"regions":["North America","Global"],"aliases":["FM 4473","ANSI FM 4473","ice ball impact test"],"related":["ul-2218","fm-approved","clay-roof-tile","concrete-roof-tile","hail-damage"],"sources":[{"title":"Approval Standard 4473 (ANSI) PDF","url":"https://www.fmapprovals.com/-/media/Feature/Approval-Standards/4473ansi-pdf.pdf","publisher":"FM Approvals"},{"title":"Tech Today: impact resistance testing","url":"https://professionalroofing.net/articles/article/1363","publisher":"Professional Roofing (NRCA)"},{"title":"Roof hail impact resistance","url":"https://roofobservations.com/roof-hail-impact-resistance/","publisher":"Roof Observations"},{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/?p=2512","publisher":"IBHS FORTIFIED"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"fm-4474","title":"ANSI/FM 4474","summary":"ANSI/FM 4474 is a US national standard for testing the simulated wind uplift resistance of roof assemblies with static pressure or pull tests.","body":"ANSI/FM 4474, *American National Standard for Evaluating the Simulated Wind Uplift Resistance of Roof Assemblies Using Static Positive and/or Negative Differential Pressures*, was developed by FM Approvals (the certification arm of insurer FM, formerly FM Global) and approved as an American National Standard. The 2004 edition was reaffirmed in 2010.\n\n## Scope\n\nThe standard measures how well a complete roof assembly resists uplift by applying a static pressure difference across it. It applies to:\n\n- standing seam metal roofing\n- lap seam (through-fastened) metal roofing\n- hot-mopped and built-up roofing\n- single-ply membranes\n\nLoose-laid and ballasted systems are outside its scope because they rely on weight rather than attachment.\n\n## Test types\n\nANSI/FM 4474 describes several procedures, including:\n\n- **Pull test** – a 2 by 2 ft (0.6 by 0.6 m) simulated uplift test, often used for components such as insulation adhesion.\n- **Pressure uplift tests** – on samples of 5 by 9 ft (1.5 by 2.7 m) or 12 by 24 ft (3.7 by 7.3 m), depending on the assembly.\n\nPressure is increased in 15 psf (0.72 kPa) increments, each held for 60 seconds, until failure.\n\n## Relationship to FM Approvals ratings\n\nFM Approvals uses the 12 by 24 ft uplift table in its own approval standards, such as [FM 4470](/fm-4470) for membrane roofs. Approved assemblies are given ratings such as Class 1-60, Class 1-90 and higher, where the number is the uplift pressure in psf that the assembly withstood (with FM's own safety margin applied in design). These ratings appear in the RoofNav database used by specifiers and insurers.\n\n## Code recognition\n\nThe International Building Code accepts FM 4474 alongside [UL 580](/ul-580) and [UL 1897](/ul-1897) as a wind uplift test for membrane roof systems. Florida Product Approval and Miami-Dade product control files frequently cite FM 4474 test results.\n\n## Practical notes\n\nThe test is static, so it does not capture the fluttering and cyclic loading that mechanically attached membranes see in real wind. Designers working in Canada often also look for dynamic test data under CSA A123.21.","key_facts":[{"label":"Developer","value":"FM Approvals"},{"label":"Status","value":"American National Standard (2004, reaffirmed 2010)"},{"label":"Increments","value":"15 psf (0.72 kPa), 60 seconds each"},{"label":"Sample sizes","value":"2 x 2 ft pull; 5 x 9 ft or 12 x 24 ft pressure"},{"label":"Excludes","value":"Loose-laid and ballasted systems"}],"regions":["North America","Global"],"aliases":["FM 4474","ANSI FM 4474","FM wind uplift test"],"related":["fm-4470","fm-approved","ul-580","ul-1897","wind-uplift"],"sources":[{"title":"ANSI FM 4474-2004 (R2010)","url":"https://intertek.com/building/standards/ansi-fm-4474-2004","publisher":"Intertek"},{"title":"ANSI/FM 4474 standard (PDF)","url":"https://fmapprovals.com/-/media/Feature/Approval-Standards/4474ansi-pdf.pdf","publisher":"FM Approvals"},{"title":"An uplifting experience","url":"https://code-authorities.ul.com/about/blog/certifying-roof-deck-constructions-for-wind-resistance/","publisher":"UL Solutions"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"antefix","title":"Antefix","category":"history","type":"term","summary":"A vertical ornamental block, usually terracotta, that closed the open end of each cover tile along the eaves of Greek, Etruscan and Roman roofs.","body":"An **antefix** (plural *antefixes* or *antefixa*) is an upright ornament fixed at the lower end of a row of cover tiles (imbrices) along the eaves of a tiled roof. It sealed the hollow end of the half-round tile, keeping out birds, wind-driven rain and debris, and gave the roof edge a decorative finish.\n\n## Form and decoration\n\nAntefixes were usually moulded in terracotta at the same workshops that made the roof tiles. Each was attached to, or made in one piece with, the end of an imbrex. Designs varied by region and period:\n\n- **Greek** examples commonly carried palmette (anthemion) designs and were often painted.\n- **Roman** antefixes were made in provincial tile works as well as in Italy, and examples have been excavated as far north as York in England and at Saint-Denis near Paris.\n- Figured designs such as masks and heads also occur; the motifs varied with workshop, region and period.\n\nBecause they were mass-produced from moulds, antefixes from the same mould can link buildings, workshops and dates, which makes them useful to archaeologists. Rare finds, such as an antefix recovered in York, help show how far classical roofing practice travelled.\n\n## Function in the roof system\n\nIn the imbrex and tegula system, rain runs down the flat tegulae and drops off the eaves. The rounded imbrices sit over the joints. Without an antefix, each imbrex leaves an open hole at the eaves. The antefix closes it, much as a modern eaves closure or bird stop closes the profile of a Spanish tile or corrugated sheet.\n\n## Later echoes\n\nClassical revival architecture of the 18th and 19th centuries reused antefix-like cresting along cornices. East Asian roofs developed a parallel feature: decorated round roof-end tiles that cap the eave tiles on Chinese, Korean and Japanese buildings, though these arose independently within those traditions.","key_facts":[{"label":"Material","value":"Usually moulded terracotta"},{"label":"Position","value":"Lower end of each cover tile at the eaves"},{"label":"Traditions","value":"Greek, Etruscan, Roman"}],"regions":["Europe"],"aliases":["antefixa","antefixes"],"related":["imbrex-and-tegula","ancient-greek-roof-tiles","korean-giwa-history","ember-resistant-roofing"],"company":null,"sources":[{"title":"Imbrex and tegula","url":"https://en.wikipedia.org/wiki/Imbrex_and_tegula","publisher":"Wikipedia"},{"title":"Les antéfixes","url":"https://archeologie.culture.gouv.fr/saint-denis/en/les-antefixes","publisher":"French Ministry of Culture"},{"title":"Rare antefix found in York","url":"https://yorkarchaeology.co.uk/rare-antefix-found-in-york/","publisher":"York Archaeology"}],"country":null},{"slug":"app-modified-bitumen","title":"APP Modified Bitumen","category":"low-slope-systems","type":"term","summary":"Modified bitumen membrane made with atactic polypropylene, giving a stiff, heat-resistant sheet that is normally torch-applied.","body":"APP modified bitumen is roofing membrane made from asphalt blended with atactic polypropylene, a plastic polymer. The blend is often called \"plastomeric\" bitumen, as opposed to the elastomeric SBS type. APP modification was first reported in Italy by Romolo Gorgato in 1967 and was available in the Netherlands and Great Britain by the mid-1970s.\n\n## Composition\n\nAPP compounds use a relatively high polymer content, roughly 25-30% polypropylene blended into asphalt over several hours. The result is a stiffer compound with good resistance to high temperatures and ultraviolet light. APP sheets are most often reinforced with heavy spunbonded polyester.\n\n## Installation\n\nAPP sheets are designed to be torch-applied: the installer heats the underside until the compound flows, then rolls the sheet into place so it bonds to the substrate and seals the laps. APP needs higher torching temperatures than SBS. Some products have special backings for cold adhesive, but APP sheets are generally not compatible with hot-mopped asphalt.\n\nTorching is a fire risk, and insurers have placed increasing scrutiny on torch-applied systems. Safe practice includes fire watches, keeping flames away from combustible substrates and edges, and using flame-free details at vulnerable locations.\n\n## Uses\n\nAPP membranes are used as cap sheets, base sheets, flashing membranes and below-grade waterproofing. Many APP cap sheets are mineral-surfaced; some smooth sheets are coated after installation.\n\n## Comparison with SBS\n\nAPP is more heat- and UV-tolerant but less flexible in cold weather than SBS, and offers fewer installation choices.\n\n## Standards\n\nIn North America APP sheets are covered by ASTM product specifications for atactic polypropylene modified bituminous sheet materials, and repair guidance for both APP and SBS membranes appears in the ARMA/NRCA/SPRI repair manual for low-slope membrane roof systems.","key_facts":[{"label":"First reported","value":"Italy, 1967 (R. Gorgato)"},{"label":"Polymer content","value":"About 25-30% APP"},{"label":"Usual reinforcement","value":"Spunbonded polyester"},{"label":"Install method","value":"Primarily torch-applied"}],"regions":["Global","Europe","North America"],"aliases":["APP mod-bit","plastomeric bitumen","APP membrane"],"related":["modified-bitumen-roofing","sbs-modified-bitumen","torch-applied-roofing"],"company":null,"sources":[{"title":"Who Put the Modified in Modified Bitumens?","url":"https://buildings.com/feature/article/10187932/who-put-the-modified-in-modified-bitumens","publisher":"Buildings"},{"title":"Low-slope roofing systems: built-up roofs and modified bitumen","url":"https://buildingenclosureonline.com/articles/82366-low-slope-roofing-systems-built-up-roofs-and-modified-bitumen","publisher":"Building Enclosure"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"}],"country":null},{"slug":"apron-flashing","title":"Apron and Headwall Flashing","category":"components","type":"term","summary":"Apron flashing is a continuous flashing where the top of a roof slope butts against a wall, or across the downhill face of a chimney.","body":"An apron flashing is a single continuous flashing installed where a roof slope meets a vertical surface running horizontally across it. The two most common locations are a headwall, where a lower roof's upper edge abuts a taller wall (for example, a porch roof against the house wall), and the downhill face of a chimney. In North American usage the term headwall flashing is common; in the UK, \"apron\" is the standard term and the flashing is traditionally made of lead.\n\n## Shape and installation\n\nAn apron flashing has one leg lying over the top course of the roof covering and another leg turned up the wall. Because water runs straight down the slope onto it, it is installed over the roof covering, not under it. Its upper leg is then covered by the wall's water-resistive barrier and cladding, or by a counter-flashing let into masonry.\n\nOn a chimney, the apron is the first piece installed: it wraps across the front and around the lower corners, after which step flashing (or soakers) runs up the sides and a back gutter or cricket deals with the uphill face.\n\n## Details that matter\n\n- The roof leg must be long enough to carry water well out onto the covering.\n- Where the apron meets sidewall step flashing at an outside corner, the corner needs to be folded or soldered so it does not open.\n- At the end of a headwall where the wall continues down past the roof, a kickout or diverter may be needed.\n- On tile roofs in the UK, the lead apron is dressed down over the profile of the tiles below.\n\n## Materials\n\nLead, copper, aluminium, galvanised and coated steel are all used. Historically, the apron below a chimney was typically a strip of lead.","key_facts":[{"label":"Location","value":"Headwall or front of chimney"},{"label":"Laid","value":"Over the roof covering"},{"label":"Traditional UK material","value":"Lead"}],"regions":["Global"],"aliases":["headwall flashing","apron flashing","front apron"],"related":["chimney-flashing","step-flashing","counter-flashing","roof-flashing"],"company":null,"sources":[{"title":"Flashing (weatherproofing)","url":"https://en.wikipedia.org/wiki/Flashing_(weatherproofing)","publisher":"Wikipedia"},{"title":"How to get it right: Too much abutment flashing?","url":"https://www.labc.co.uk/news/how-get-it-right-too-much-abutment-flashing","publisher":"LABC"},{"title":"All About Roof Flashing","url":"https://www.greenbuildingadvisor.com/article/all-about-roof-flashing","publisher":"Green Building Advisor"}],"country":null},{"slug":"aqal","title":"Aqal","category":"world-roofing","type":"term","summary":"Portable Somali dome hut of bent saplings tied to central poles and covered with woven mats, built by women and carried by camel.","body":"The aqal (Somali: *aqal Soomaali*) is the traditional portable house of Somali pastoral nomads in the Horn of Africa. It is a low dome of bent saplings covered with woven mats, designed to be taken apart, loaded onto camels and rebuilt at a new grazing site. Roof and walls are one continuous woven skin.\n\n## Roles\n\nMen traditionally chose the site for a new camp; women built the aqal and wove its mats.\n\n## Frame\n\nThe frame has named parts:\n\n- **udub**: central poles that hold the structure upright, erected first;\n- **kabaal**: two posts that frame the doorway;\n- **heego**: bundles of saplings set in a circle in the ground and bent over to the udub to form the dome;\n- **siid**: short branches tied across the udub, kabaal and heego to brace the whole frame.\n\n## Covering\n\nMats are woven from acacia branches, palm fronds and grass and bound with rope and fibre. The decorated, colourful side faces inward, and the plain side forms the outside. The mat nearest the ground can be removed in hot weather to let air through. Once finished, the aqal is tied down so that strong winds cannot blow it away. Its curved, low profile also reduces wind resistance. Woven grass mats of this kind are recognised as endangered cultural knowledge among Somali pastoralists.\n\n## Layout\n\nInside, the sleeping area is placed near the back wall and the living area near the door.\n\n## Related forms\n\nThe Afar of Djibouti and Ethiopia build a similar round hut, the *danas*, of bent acacia branches covered with palm-leaf or grass mats. Both belong to a wider family of portable mat-covered dome dwellings in the Horn of Africa.","key_facts":[{"label":"People","value":"Somali pastoral nomads"},{"label":"Form","value":"Low dome"},{"label":"Frame","value":"Udub poles, heego sapling ring, siid bracing"},{"label":"Covering","value":"Woven mats of acacia, palm frond and grass"},{"label":"Builders","value":"Women"}],"regions":["Africa"],"aliases":["aqal Soomaali","Somali hut","Somali nomadic dome"],"related":["roofing-in-somalia","roofing-in-djibouti","roofing-in-ethiopia","dome","ger-roof"],"company":null,"sources":[{"title":"The Somali aqal","url":"https://www.paukwa.or.ke/?p=14652","publisher":"Paukwa"},{"title":"The Traditional Architecture of Djibouti","url":"https://www.arabamerica.com/the-traditional-architecture-of-djibouti","publisher":"Arab America"},{"title":"Harar, the traditional woven grass mats of the Somali pastoral nomads","url":"https://www.emkp.org/harar-woven-grass-mats/","publisher":"Endangered Material Knowledge Programme (British Museum)"}],"country":null},{"slug":"architectural-shingle","title":"Architectural Shingle","type":"term","summary":"A laminated asphalt shingle made of two or more bonded layers, giving a thicker, textured, multi-dimensional appearance.","body":"An architectural shingle, also called a laminated or dimensional shingle, is an asphalt shingle built from two or more layers bonded together. The upper layer is cut into tabs or shapes of varying width, and the lower layer shows through the gaps. The result is a roof with irregular shadow lines that loosely imitates wood shakes or slate, rather than the flat grid of a three-tab roof.\n\n## Construction and size\n\nLaminated shingles have no regular cutouts. Most are made in metric sizes of about 13 by 39 in (333 by 1000 mm). The extra layer makes them heavier: inspection references give about 240-320 lb per square (roughly 12-16 kg/m²), and high-end versions with up to five layers can approach 500 lb per square (about 24 kg/m²).\n\n## Performance\n\nThe double thickness generally gives better resistance to wind and more tolerance of minor deck irregularities. Typical wind ratings quoted for standard installation are around 70-110 mph (113-177 km/h), and about 110-130 mph (177-209 km/h) when the manufacturer's enhanced six-nail pattern is used. Manufacturer warranties commonly run from 30 years to \"lifetime\" terms, usually prorated and often limited to material. Typical service lives are commonly given as about 24-30 years, but heat, ventilation and installation quality strongly affect real performance.\n\n## Market position\n\nIn North America, architectural shingles have largely replaced three-tab shingles as the standard choice for new homes and re-roofing. Their irregular pattern also hides slight colour variation and deck unevenness better than flat strip shingles.\n\n## Installation notes\n\nArchitectural shingles need to be nailed in the manufacturer's specified nail zone, which is often a narrow band where the two layers overlap; nails placed too high may miss the lower layer and reduce wind resistance. Matching hip and ridge caps are usually sold separately because the laminated shingle cannot be folded over a ridge without cracking.\n","key_facts":[{"label":"Typical size","value":"About 13 x 39 in (333 x 1000 mm)"},{"label":"Weight","value":"About 240-320 lb per square (12-16 kg/m²)"},{"label":"Wind rating (typical)","value":"About 110-130 mph with six-nail pattern"},{"label":"Typical life","value":"About 24-30 years (climate dependent)"}],"regions":["North America"],"aliases":["laminated shingle","dimensional shingle","architectural asphalt shingle"],"related":["asphalt-shingle","three-tab-shingle","designer-shingle","impact-resistant-shingle"],"sources":[{"title":"Mastering Roof Inspections: Asphalt Composition Shingles, Part 6","url":"https://nachi.org/asphalt-comp-shingles-part6-60.htm","publisher":"InterNACHI"},{"title":"Asphalt Shingle Types (3-Tab vs. Laminated Architectural), ASTM Classifications & Thermal Behavior","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-types-astm-thermal","publisher":"Open Exam Prep"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"ardennes-slate","title":"Ardennes Slate","category":"materials","type":"term","summary":"Roofing slate from the Ardennes uplands of Belgium, France and Luxembourg, quarried from the Middle Ages until the late 20th century.","body":"**Ardennes slate** is natural roofing slate from the Ardennes, the upland region shared by southern Belgium, the French département of Ardennes and northern Luxembourg. Quarried from at least the Middle Ages, it roofed houses, churches and abbeys across the Low Countries and northern France. Production in Belgium and Luxembourg ended in the 1970s and 1980s, but the slate-roofed villages and old workings remain an important part of the region's heritage.\n\n## Geology\n\nThe Ardennes slate belt consists of schists and phyllites. Around Vielsalm in Belgium the beds dip steeply, at about 55-60 degrees, and include phyllites containing the mineral ottrelite. The same area yields **coticule**, a fine whetstone used for sharpening razors.\n\n## Early use\n\nSchist plaques engraved during the Magdalenian period (roughly 17,000-10,000 years ago) have been found at sites including Monthermé in France and the Trou de Chaleux cave in Belgium. In Roman and Gallo-Roman times slate was used mainly for floors and for tombs, such as the slate-walled graves of a cemetery at Bihain. Roofing slate appears in documents from the 12th century: in 1156 the abbey of Saint-Trond is said to have been roofed with slate from Fumay in the French Meuse valley. The monks of Orval held a quarry at Herbeumont, confirmed in 1269 and again in 1306, and slate working at Vielsalm is recorded from 1481.\n\n## Industrial peak\n\nIn the Belgian province of Luxembourg, 480 workers produced about 17 million slates in 1840. Output reached about 41 million slates in 1873 and 1876, when 1,108 people worked in the industry, and in 1877 there were 51 open-air and 116 underground workings. The main Belgian basins were around Herbeumont, Bertrix, Cugnon and Martelange, and around Vielsalm. Across the border, the Haut-Martelange mines in the Grand Duchy of Luxembourg produced about 6 million slates a year by the end of the 19th century.\n\n## Decline\n\nCompetition from tiles, other roofing materials and cheaper imported slate reduced demand through the 20th century. Major Vielsalm quarries closed in 1884-1886, others in 1930, 1944 and 1968, and Vielsalm's production ended in 1972. The last Luxembourg mine, at Haut-Martelange, closed in 1986, and Martelange, the last Belgian slate site, closed at the end of the 1980s. In the French Ardennes, former slate centres such as Rimogne are now part of a tourist \"slate route\".\n\n## Uses\n\nRoofing was the main use, valued for fire resistance and durability. Slate was also made into floor slabs, school writing slates, billiard tables, sinks, laboratory crucibles and sawn slabs.\n\n## Sources and gaps\n\nTechnical test data for Ardennes slate under EN 12326: published information is limited.","key_facts":[{"label":"Region","value":"Ardennes (Belgium, France, Luxembourg)"},{"label":"Early roofing record","value":"1156 (Fumay slate for Saint-Trond abbey)"},{"label":"Belgian peak","value":"About 41 million slates (1873, 1876)"},{"label":"Last Belgian site","value":"Martelange, closed end of the 1980s"},{"label":"Last Luxembourg mine","value":"Haut-Martelange, closed 1986"}],"regions":["Europe"],"aliases":["Belgian slate","ardoise d'Ardenne","Ardennes ardoise","Martelange slate"],"related":["natural-slate","roofing-in-belgium","roofing-in-luxembourg","roofing-in-france","welsh-slate","en-12326"],"company":null,"sources":[{"title":"L'extraction des ardoises en suivant le fil historique","url":"https://gsb.naturalsciences.be/wp-content/uploads/2026/03/2-1-Lextraction-des-ardoises-en-suivant-le-fil-historique.pdf","publisher":"Geological Survey of Belgium"},{"title":"History","url":"https://www.ardoise.lu/historie?lang=en","publisher":"Musée de l'Ardoise, Haut-Martelange"},{"title":"Ardennes slate route","url":"https://www.visitardenne.com/en/adventures-ardennes/historical-adventures/ardennes-slate-route","publisher":"Visit Ardenne"}],"country":null},{"slug":"asante-traditional-buildings","title":"Asante Traditional Buildings","type":"place","summary":"Earth-and-timber shrine houses near Kumasi, Ghana, once steeply thatched with palm fronds and now mostly roofed in corrugated iron.","body":"The Asante Traditional Buildings are a group of shrine (\"fetish\") houses in the countryside around Kumasi, Ghana, mostly to the north-east of the city. They are the last substantial survivors of the architecture of the Asante kingdom, which was at its height in the 18th and 19th centuries, and were inscribed on the UNESCO World Heritage List in 1980.\n\n## Construction\n\nThe buildings are made of timber, bamboo and earth. Walls are built with wattle-and-daub and earth techniques and finished with mud plaster. Rooms are arranged around courtyards, typically four rooms facing a central court, and stand on a raised plinth. The walls carry bold bas-relief decoration of spirals and arabesques, together with animals, birds and plants associated with Adinkra symbols.\n\n## The roof\n\nUNESCO records that the buildings were originally covered with steeply pitched roofs thatched with palm fronds. The steep pitch suited the hot, wet forest climate, shedding heavy rain quickly and keeping water off the earthen walls.\n\nIn 12 of the 13 buildings recorded by UNESCO, the thatch has since been replaced with corrugated iron. The metal roofs are lighter and set at a shallower pitch than the originals. This is one of the clearest documented examples in West Africa of a heritage building type changing its roof covering from organic thatch to sheet metal, a change that alters the silhouette and the way the building handles heat and rain.\n\n## Early records\n\nDrawings made by the English visitor Thomas Bowdich in 1817 are an important record of the architecture of Kumasi before the British conquest. The royal mausoleum at Kumasi was destroyed by British forces during the 1895-96 expedition to Kumasi, and the surviving rural shrines are now the main physical evidence of the tradition.\n\n## Conservation issues\n\nThe buildings face a demanding environment:\n\n- The hot, humid climate damages earth and wattle-and-daub walls and encourages mould.\n- Termites and other insects attack timber and organic materials.\n- Agricultural expansion makes thatch, bamboo and some timber species harder to obtain.\n- Many structures are incomplete, with parts of the original buildings missing.\n\nUNESCO notes that the survival of the shrines depends on regular maintenance and a sustainable supply of the organic materials needed for repairs. Restoring thatch would require reliable sources of palm fronds and skilled thatchers.\n\n## Significance for roofing\n\nThe Asante shrines show the forest-zone counterpart to the flat earth roofs of the Sahel: a pitched, thatched roof over earth walls, relying on overhang and steepness rather than mass to protect the building.","key_facts":[{"label":"Location","value":"Around Kumasi, Ghana"},{"label":"Original roof","value":"Steep palm-frond thatch"},{"label":"Current roof","value":"Corrugated iron on 12 of 13 buildings"},{"label":"Walls","value":"Timber, bamboo, wattle-and-daub, mud plaster"},{"label":"UNESCO inscription","value":"1980"}],"regions":["Africa"],"aliases":["Asante shrine houses","Ashanti traditional buildings","Asante fetish houses"],"related":["roofing-in-ghana","palm-thatch","thatch","corrugated-iron","roofing-in-west-africa"],"sources":[{"title":"Asante Traditional Buildings","url":"https://whc.unesco.org/en/list/35/","publisher":"UNESCO World Heritage Centre"},{"title":"Asante Traditional Buildings","url":"https://en.wikipedia.org/wiki/Asante_Traditional_Buildings","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"asbestos-cement-roofing","title":"Asbestos-Cement Roofing","type":"article","summary":"Roof sheets and slates made of cement reinforced with asbestos fibres, widely used in the 20th century and now banned in many countries as a health hazard.","body":"Asbestos-cement roofing is roofing made from a composite of Portland cement reinforced with asbestos fibres, pressed into corrugated sheets, flat sheets, slates and moulded fittings. It was used worldwide through much of the 20th century on houses, garages, farm buildings and factories. Today it is recognised as a health hazard, its manufacture and use are banned in many countries, and its removal is tightly regulated. In Australia and New Zealand it is widely known as **fibro**; other names include AC sheet and, after an early brand, Eternit.\n\n## History\n\nAustrian Ludwig Hatschek patented his asbestos-cement process in 1900 (some sources give 1901) and gave the product the trade name Eternit in 1903. His process mixed about 90% Portland cement with 10% asbestos fibre and water and formed thin sheets on a machine adapted from cardboard-making. The material was marketed as a cheap, fireproof alternative to asphalt and other roofing, and corrugated profiles such as \"Super Six\" became standard on industrial and agricultural buildings. Products were also made to imitate slate, and Europe produced a wider variety of shapes than the United States.\n\n## Health hazard\n\nIntact, well-bonded asbestos cement releases few fibres, but weathering, breakage, drilling, cutting, abrasion and pressure-washing can release them into the air. As the material ages it becomes brittle and more friable. Inhaled asbestos fibres cause or increase the risk of asbestosis and of pleural and peritoneal mesothelioma. Queensland, Australia, for example, prohibits cleaning fibro roofs with pressure washers.\n\n## Bans by country (selected)\n\n- **United Kingdom**: blue and brown asbestos banned in 1985; white (chrysotile) asbestos banned in Great Britain in 1999 and Northern Ireland in 2000.\n- **Australia**: nationwide ban on import and use of all asbestos from 31 December 2003 (materials already installed were not covered).\n- **New Zealand**: raw amphibole asbestos imports banned 1984; chrysotile imports banned 2002.\n- **Japan**: full ban 2004.\n- **South Korea**: full ban from January 2009.\n- **Brazil**: nationwide prohibition by the Supreme Federal Court in November 2017.\n- **Canada**: import, sale and use of most asbestos products prohibited from 30 December 2018.\n- **United States**: in March 2024 the Environmental Protection Agency finalised a rule banning the ongoing uses of chrysotile asbestos, the only form still imported or used in the country, with phase-out periods for remaining industrial uses. The rule covers ongoing uses; asbestos already in buildings is addressed separately.\n- **European Union** member states have also banned asbestos.\n- In parts of **South America and Asia** asbestos-cement sheets remain common on existing buildings, and India has continued to use asbestos widely.\n\n## Removal regulations\n\nRules vary widely, so owners should check local law before disturbing any suspect roof. In Great Britain the Control of Asbestos Regulations 2012 require duty holders of non-domestic buildings to manage asbestos, and set notification, record-keeping and health-surveillance requirements for certain work; higher-risk materials must be removed by licensed contractors. Australia's national codes set out management and removal practices, with state regulators enforcing them.\n\n## Replacement\n\nAsbestos-free fibre cement, reinforced with cellulose fibres, replaced asbestos cement from the 1980s and is still widely made for slates and corrugated sheets.\n","key_facts":[{"label":"Invented","value":"1900, Ludwig Hatschek (Eternit name 1903)"},{"label":"Typical mix","value":"About 90% cement, 10% asbestos fibre"},{"label":"Health risks","value":"Asbestosis, mesothelioma"},{"label":"Example bans","value":"UK 1999, Australia 2003, Japan 2004, Canada 2018, US (chrysotile) 2024"}],"regions":["Global","Europe","Oceania","North America","Latin America","South Asia","East Asia"],"aliases":["AC sheet","fibro","asbestos cement sheet","transite","asbestos slate"],"related":["fibre-cement-slate","corrugated-fibre-cement-sheet","organic-mat-shingle"],"sources":[{"title":"Asbestos cement","url":"https://en.wikipedia.org/wiki/Asbestos_cement","publisher":"Wikipedia"},{"title":"Asbestos and the law","url":"https://en.wikipedia.org/wiki/Asbestos_and_the_law","publisher":"Wikipedia"},{"title":"Eternit","url":"https://en.wikipedia.org/wiki/Eternit","publisher":"Wikipedia"},{"title":"Fiber cement siding","url":"https://en.wikipedia.org/wiki/Fiber_cement_siding","publisher":"Wikipedia"},{"title":"Roof","url":"https://en.wikipedia.org/wiki/Roof","publisher":"Wikipedia"},{"title":"Biden-Harris Administration Finalizes Ban on Ongoing Uses of Asbestos to Protect People from Cancer","url":"https://www.epa.gov/newsreleases/biden-harris-administration-finalizes-ban-ongoing-uses-asbestos-protect-people-cancer","publisher":"U.S. Environmental Protection Agency"},{"title":"Ludwig Hatschek","url":"https://en.wikipedia.org/wiki/Ludwig_Hatschek","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"ashrae-90-1","title":"ASHRAE 90.1","summary":"ASHRAE 90.1 is the US-based energy standard for buildings other than low-rise residential, setting minimum roof insulation and reflectance requirements.","body":"ANSI/ASHRAE/IES Standard 90.1, *Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings*, is published by ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning Engineers) with the Illuminating Engineering Society. It sets minimum energy-efficiency requirements for the design of commercial and multifamily buildings and is one of the most influential energy standards in the world. The current edition is **90.1-2025**. Its predecessor, 90.1-2022, incorporated more than 80 addenda to the 2019 edition and broadened the scope from buildings to \"sites and buildings.\"\n\n## History\n\nThe standard grew out of the 1970s energy crisis. The first version was issued as ASHRAE 90-1975. It was later reissued as Standard 90.1 (the 1989 edition was 90.1-1989) and placed on continuous maintenance in 1999. Since 2001, new editions have appeared every three years (2001, 2004, 2007, 2010, 2013, 2016, 2019, 2022, 2025).\n\nIn the United States, the Department of Energy reviews each edition and issues a determination on whether it improves efficiency. A positive determination requires states to update their commercial energy codes to meet or exceed that edition.\n\n## Roof provisions\n\nSection 5 (Building Envelope) sets requirements for roofs, including:\n\n- **Minimum insulation** – maximum U-factors or minimum R-values for roof assemblies, varying by climate zone and roof type (insulation entirely above deck, metal building roofs, attic and other).\n- **Roof reflectance** – the 2010 edition added minimum solar reflectance and thermal emittance requirements for low-slope roofs in warmer climate zones, with exceptions and trade-offs.\n- **Air leakage** – continuous air barrier requirements that affect roof-to-wall transitions and penetrations.\n\nThe 2016 edition updated requirements for metal building roofs.\n\n## Relationship to other codes\n\nMany US states adopt the International Energy Conservation Code (IECC), which allows ASHRAE 90.1 as an alternative compliance path for commercial buildings. California's Energy Code ([Title 24](/title-24-cool-roof)) has a similar structure. Outside the US, 90.1 has been a model for national codes, including India's Energy Conservation Building Code.\n\n## Why it matters for roofs\n\nReroofing projects on commercial buildings frequently trigger energy code requirements to add insulation to current levels. Designers use 90.1 tables to determine how much insulation a new roof needs and whether a reflective surface is required.","key_facts":[{"label":"Publisher","value":"ASHRAE (with IES)"},{"label":"Current edition","value":"90.1-2025"},{"label":"First version","value":"ASHRAE 90-1975"},{"label":"Scope","value":"Sites and buildings except low-rise residential"},{"label":"Roof requirements","value":"Section 5: insulation, reflectance, air barrier"}],"regions":["North America","Global"],"aliases":["ASHRAE 90.1","Standard 90.1","ASHRAE/IES 90.1"],"related":["title-24-cool-roof","cool-roof-rating-council","roof-insulation","international-building-code"],"sources":[{"title":"Standard 90.1","url":"https://www.ashrae.org/technical-resources/bookstore/standard-90-1","publisher":"ASHRAE"},{"title":"ASHRAE 90.1","url":"https://en.wikipedia.org/wiki/ASHRAE_90.1","publisher":"Wikipedia"},{"title":"Interpretations for Standard 90.1-2025","url":"https://www.ashrae.org/technical-resources/standards-and-guidelines/standards-interpretations/interpretations-for-standard-90-1-2025","publisher":"ASHRAE"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"aspen-ploughshare-shingles","title":"Aspen Ploughshare Shingles (Lemekh)","category":"world-roofing","type":"article","summary":"Carved aspen shingles, called lemekh or 'ploughshares', that clad the domes, barrels and tent roofs of wooden churches in the Russian North, as at Kizhi.","body":"*Lemekh* (Russian, literally \"ploughshare\") is the name given to the small carved wooden shingles that cover the curved roofs of traditional wooden churches in northern Russia. They are usually made of aspen and are shaped with a stepped or pointed lower end, so that a dome covered with them looks scaled. Laid over curved surfaces, they allow onion domes, barrel roofs and tent roofs to be clad entirely in timber. As aspen weathers it takes on a silvery-grey tone that can shimmer in changing light.\n\n## Where they are used\n\nRussian wooden church builders favoured expressive roof forms: tall tent roofs that could reach about 18 m (60 ft), barrel (*bochka*) and cube-shaped roofs, and clusters of onion domes. Curved forms appeared mainly on churches and wealthy houses and were often decorated with carvings and ploughshare shingles. Archival records show, for example, that the tent roof of the Church of the Nativity at Bolkachevskaya (1769) in the Povazhye area was covered with lemekh, and other 17th- and 18th-century tent roofs in the region were covered with wooden shingles. At Kizhi, flatter roof surfaces were covered with spruce planks instead.\n\n## Kizhi Pogost\n\nThe best-known example is the Church of the Transfiguration at Kizhi Pogost on Lake Onega in Karelia, a UNESCO World Heritage Site inscribed in 1990. Dendrochronology places its construction after 1713-1714. The church rises to 37 m (121 ft) and carries 22 domes clad in aspen. Published counts of the shingles differ: about 60,000 shingles fixed with about 180,000 nails according to one account, and about 30,000 carved shingles according to another. The nearby Church of the Intercession (1764) has nine domes, and the octagonal bell tower (1862, rebuilt 1874) has a shingled onion dome.\n\nThe shingles are made by hand. Craftsmen carve a stepped profile into each one using a curved-blade axe. Beneath them, the domes are covered with birch bark as an additional waterproof layer. Aspen is valued because it is flexible and strong, and resists warping and rot.\n\n## Restoration history\n\nIn the 19th century the Kizhi domes were covered with metal sheets and the walls with boards; a restoration in 1949-1959 returned the churches to their original appearance. In 1980-1983 a steel frame was installed inside the Transfiguration Church to stabilise it. A long restoration, carried out in full from 2011 and lasting about a decade, replaced only 36% of the structure's timber; about 40,000 roof shingles were restored individually, with some replaced by new ones made by traditional methods. The church reopened to visitors in 2021.\n\n## Maintenance\n\nWooden shingles on domes are exposed to rain, snow and sun on every side and must be repaired and replaced periodically. At Kizhi, replacement shingles have been made using traditional techniques.","key_facts":[{"label":"Material","value":"Aspen wood"},{"label":"Russian name","value":"Lemekh (\"ploughshare\")"},{"label":"Used on","value":"Onion domes, barrel and tent roofs"},{"label":"Landmark example","value":"Kizhi Transfiguration Church, 22 domes"},{"label":"Weathered colour","value":"Silvery grey"}],"regions":["Europe","Arctic"],"aliases":["lemekh","lemeh","ploughshare shingles","plowshare shingles","aspen shingles"],"related":["onion-dome","roofing-in-russia","wood-shingle","birch-bark-roofing","pyramid-roof","wooden-tserkva-roofs","maramures-church-roofs"],"company":null,"sources":[{"title":"Kizhi Pogost","url":"https://whc.unesco.org/en/list/544","publisher":"UNESCO World Heritage Centre"},{"title":"Kizhi Pogost","url":"https://en.wikipedia.org/wiki/Kizhi_Pogost","publisher":"Wikipedia"},{"title":"The Church of the Transfiguration, Kizhi Island, Russia","url":"https://naturalhomes.org/kizhi-island.htm","publisher":"Natural Homes"},{"title":"Nailed it: Kizhi Pogost church is finally restored","url":"https://www.theartnewspaper.com/2021/07/16/nailed-it-kizhi-pogost-church-is-finally-restored-on-russian-island-of-remarkable-wooden-buildings","publisher":"The Art Newspaper"},{"title":"18th Century Wooden Churches of Povazhye: Traditions and Local Peculiarities (O. Zinina)","url":"https://www.atlantis-press.com/article/125964353.pdf","publisher":"Atlantis Press"},{"title":"Russian wooden architecture","url":"https://en.wikipedia.org/wiki/Russian_wooden_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"asphalt-roofing-manufacturers-association","title":"Asphalt Roofing Manufacturers Association (ARMA)","summary":"ARMA is the North American trade association of asphalt shingle and asphalt membrane manufacturers, founded in 1915.","body":"The Asphalt Roofing Manufacturers Association (ARMA) is a trade association for North American manufacturers of asphalt roofing products and their raw material suppliers. Its members make most of the asphalt shingles and asphalt-based low-slope membranes sold in North America. ARMA began in 1915 in New York City as the Asphalt Roofing Industry Bureau and marked its centennial in 2015. Its offices later moved to Garland, Texas, and then to the Washington, D.C., area; its current address is in Forest Hill, Maryland.\n\n## Background\n\nAsphalt roofing in North America dates to 1893, when roll roofing first appeared on the market. Early asphalt shingles used an organic felt mat, with granules of materials such as mica, dolomite or crushed oyster shell on the surface. Modern shingles mostly use a fibreglass mat. Asphalt shingles are now the most common roof covering on houses in the United States and Canada.\n\n## Activities\n\n- **Technical information.** ARMA publishes technical bulletins, guides and white papers on installation, ventilation, wind and hail resistance, and maintenance of asphalt roof systems, for both steep-slope and low-slope work.\n- **Codes and standards.** It works with building code bodies and standards organisations, and seeks to influence laws, codes and regulations that affect asphalt roofing.\n- **Market data.** It issues a quarterly report on product shipments.\n- **Recycling.** It hosts a forum on recycling asphalt shingles, for example into asphalt pavement.\n- **Awards.** It runs the Excellence in Asphalt Roofing Awards for completed projects.\n\n## Context\n\nARMA's publications are widely cited by contractors and inspectors, but they reflect the view of the manufacturers. Installation must also follow the specific maker's instructions and local building code, which can differ by climate zone. For example, ice barrier underlayment at the eaves is required in cold regions under North American codes.","key_facts":[{"label":"Founded","value":"1915 (as Asphalt Roofing Industry Bureau)"},{"label":"Address","value":"Forest Hill, Maryland, USA"},{"label":"Members","value":"Asphalt shingle and membrane manufacturers, raw material suppliers"},{"label":"Website","value":"asphaltroofing.org"}],"regions":["North America"],"aliases":["ARMA","Asphalt Roofing Industry Bureau"],"related":["asphalt-shingle","modified-bitumen-roofing","built-up-roofing","roof-ventilation"],"company":{"founded":"1915","headquarters":"Forest Hill, Maryland, USA","website":"https://www.asphaltroofing.org","known_for":["Asphalt roofing technical bulletins","Excellence in Asphalt Roofing Awards"]},"sources":[{"title":"About us","url":"https://asphaltroofing.org/about-arma/about-us","publisher":"ARMA"},{"title":"Association unveils new logo to mark 100 years of industry leadership","url":"https://www.asphaltroofing.org/asphalt-roofing-manufacturers-association-celebrates-a-century-of-success-in-building-construction/","publisher":"ARMA"},{"title":"ARMA celebrates a century of success in building construction","url":"https://www.roofingcontractor.com/articles/90773-arma-celebrates-a-century-of-success-in-building-construction","publisher":"Roofing Contractor"}],"category":"organizations","type":"organization","country":null},{"slug":"asphalt-shingle","title":"Asphalt Shingle","type":"article","summary":"A flexible roofing unit made of a mat coated in asphalt and surfaced with mineral granules, laid in overlapping courses on pitched roofs.","body":"An asphalt shingle is a thin, flexible roofing unit made from a reinforcing mat that is soaked or coated with asphalt (bitumen) and topped with crushed mineral granules. Shingles are nailed to a solid deck in overlapping rows so that each course sheds water onto the one below. They are among the most widely used roof coverings on houses in North America, and similar products are sold in Europe under the name bitumen shingles.\n\nThe product grew out of \"asphalt prepared roofing\", a rolled material that appeared in the United States in the 1890s. Slate granules were added in 1897, the material was first cut into strips in 1901, and individual shingles were in use by 1903.\n\n## Construction\n\nA modern shingle has four parts:\n\n- **Mat**: originally organic felt (rag, paper or wood fibre); since the 1980s mostly a glass-fibre mat.\n- **Asphalt coating**: often filled with powdered minerals; some products use polymer-modified (SBS) asphalt for flexibility.\n- **Granules**: ceramic-coated stone that blocks ultraviolet light, adds colour and improves fire resistance.\n- **Back surfacing and sealant**: sand, talc or mica on the underside, plus a heat-activated adhesive strip that bonds each course to the next.\n\n## Main types\n\n- **Three-tab (strip) shingles**: single-layer, flat, with two cutouts forming three tabs.\n- **Architectural (laminated or dimensional) shingles**: two or more layers bonded together for a thicker, textured look.\n- **Designer or luxury shingles**: heavier multi-layer products that imitate slate or wood shake.\n\nWeights range from roughly 190 lb per square (about 9 kg/m²) for basic strip shingles to more than 450 lb per square (about 22 kg/m²) for heavy designer products. A \"square\" is 100 sq ft (9.29 m²) of roof.\n\n## Performance and standards\n\nIn the United States, the International Building Code requires glass-mat shingles to meet ASTM D3462 and sets a minimum slope of 2:12 (about 9.5°) on a solid deck. Wind resistance is classified under ASTM D3161 and ASTM D7158 (classes D, G and H, up to 90, 120 and 150 mph respectively). Fire performance is tested to ASTM E108 / UL 790, and hail resistance to UL 2218, where Class 4 is the highest rating.\n\n## Ageing and lifespan\n\nHeat is the main cause of ageing. Sun and temperature swings drive volatile oils out of the asphalt, the shingle becomes brittle, granules wash off and the mat is eventually exposed. Good attic ventilation and lighter colours slow this process. Typical service lives are commonly given as about 15-18 years for three-tab shingles and 24-30 years for architectural shingles, depending heavily on climate.\n\n## End of life\n\nOld shingles are a large waste stream: a 2007 study linked to the US EPA estimated about 11 million short tons of shingle waste per year in the United States. Some is recycled as reclaimed asphalt shingles (RAS) in road paving, although many US states restrict that use.\n","key_facts":[{"label":"Main components","value":"Glass-fibre or organic mat, asphalt, mineral granules"},{"label":"Minimum slope (IBC)","value":"2:12 (about 9.5°)"},{"label":"Typical weight","value":"190-450+ lb per square (about 9-22 kg/m²)"},{"label":"Key US standards","value":"ASTM D3462, D3161, D7158, UL 2218, UL 790"},{"label":"First shingles","value":"c. 1903, United States"}],"regions":["North America","Europe","Global"],"aliases":["composition shingle","comp shingle","bitumen shingle","asphalt roofing shingle"],"related":["three-tab-shingle","architectural-shingle","designer-shingle","fiberglass-shingle","organic-mat-shingle","roofing-granules","impact-resistant-shingle","bitumen-shingle","roll-roofing"],"sources":[{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Mastering Roof Inspections: Asphalt Composition Shingles, Part 6","url":"https://nachi.org/asphalt-comp-shingles-part6-60.htm","publisher":"InterNACHI"},{"title":"Asphalt Shingle Types (3-Tab vs. Laminated Architectural), ASTM Classifications & Thermal Behavior","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-types-astm-thermal","publisher":"Open Exam Prep"}],"category":"materials","company":null,"country":null},{"slug":"shingle-nailing-pattern","title":"Asphalt Shingle Nailing Pattern","category":"installation","type":"article","summary":"The nailing pattern sets how many nails each asphalt shingle receives and where: typically four, or six for high-wind and steep-slope work.","body":"The **nailing pattern** is the number and position of fasteners in each asphalt shingle. It is one of the most important factors in wind resistance, and incorrect nailing is a common reason manufacturers decline warranty claims. Manufacturers print a nailing line or zone on the shingle and publish the pattern in their installation instructions.\n\n## Number of nails\n\n- **Standard:** four nails per strip shingle is the usual code and manufacturer minimum.\n- **High wind:** six nails, as manufacturers specify for high-wind installations; local codes in high-wind regions may also require them.\n- **Steep slopes and mansards:** one manufacturer defines steep slope as 21 in per foot (about 60 degrees) or more and requires six nails plus hand-sealing with spots of asphalt cement.\n\n## Placement\n\nNails go in the manufacturer's nailing zone, which on laminated shingles is placed so the nail passes through both the upper and lower layers where they overlap. One manufacturer's four-nail layout places nails about 1 in from each end and about 13 in from each end, on a line 7 3/8 in below the top edge. Nails should be at least 2 in from joints or cutouts in the shingle below.\n\n\"High nailing\", where nails are driven above the zone, is a frequent defect: the nail may miss the underlying course and the shingle can pull free.\n\n## Nail specification\n\n| Item | Typical requirement |\n|---|---|\n| Material | Galvanized steel, stainless steel or aluminium roofing nails |\n| Shank | 12 gauge minimum (some manufacturers allow 11 gauge) |\n| Head | 3/8 in (9.5 mm) minimum |\n| Penetration | 3/4 in (19 mm) into the deck, or through thinner sheathing |\n\nThe IRC specifies roofing nails for asphalt shingles, so staples are not a permitted substitute. Near salt water, guidance recommends hot-dip galvanized or stainless fasteners.\n\n## Driving nails\n\nNails should be driven straight with the head flush with the shingle surface. Overdriven nails cut into the mat and lose holding power; underdriven nails hold the next course up and can break through it. Pneumatic nailers are commonly run at about 90 to 110 psi and adjusted for the deck.","key_facts":[{"label":"Standard nails per shingle","value":"4"},{"label":"High-wind nails per shingle","value":"6"},{"label":"Minimum head diameter","value":"3/8 in (9.5 mm)"},{"label":"Minimum penetration","value":"3/4 in (19 mm) or through deck"}],"regions":["North America","Global"],"aliases":["shingle nailing","six-nail pattern","four-nail pattern","high-wind nailing"],"related":["starter-course","shingle-exposure-and-offset","asphalt-shingle","roofing-fasteners","wind-uplift"],"company":null,"sources":[{"title":"TBR64 Proper Nailing for Laminated Shingles","url":"https://www.iko.com/na/document/tbr64-proper-nailing-for-laminated-shingles-product-bulletin","publisher":"IKO"},{"title":"Asphalt shingle installation requirements, IRC 2024","url":"https://www.jaspector.com/codes/irc-2024/ch09-roof-assemblies/asphalt-shingle-installation-irc-2024/","publisher":"Jaspector"},{"title":"Shingle Application Mechanics: Starter Courses, Offsets, Fastener Placement and Wind Sealant Activation","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-application-mechanics","publisher":"Open Exam Prep"},{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"},{"title":"Canadian Roofing Reference Manual: 9.1.2 Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-1-asphalt-shingles/9-1-2-installation/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"asphalt-shingle-recycling","title":"Asphalt Shingle Recycling","type":"article","summary":"Reprocessing old and scrap asphalt shingles, mainly by grinding them for use in asphalt road paving.","body":"Asphalt shingle recycling is the recovery of waste asphalt shingles, mostly by grinding them into small particles for use in asphalt pavement. Asphalt shingles are among the most widely used roof coverings in North America, so they generate a large waste stream when roofs are replaced.\n\n## Size of the waste stream\n\nA study commissioned by the US Environmental Protection Agency in 2007 estimated that the United States generated about 11 million short tons (roughly 10 million tonnes) of asphalt shingle waste each year, most of it sent to landfill. The waste comes from two sources:\n\n- **Tear-off shingles** removed during reroofing, which make up most of the volume.\n- **Manufacturing scrap**, such as trimmings and rejected shingles, which is cleaner and easier to recycle.\n\n## Use in pavement\n\nShingles contain asphalt binder, mineral granules and a fibreglass or organic mat. Ground shingles, known as reclaimed or recycled asphalt shingles (RAS), can replace part of the virgin asphalt binder and fine aggregate in hot-mix asphalt for roads and parking areas. In 2019, US asphalt plants accepted an estimated 1.1 million tons of reclaimed shingles.\n\n## Processing\n\n1. Collection at transfer stations or directly from roofing contractors.\n2. Sorting to remove nails, wood, underlayment, flashing and trash.\n3. Grinding to a specified particle size.\n4. Testing, especially of tear-off shingles, for contaminants; some older roofing products may contain asbestos, so screening is an important step.\n\n## Barriers\n\nRecycling depends on nearby processing facilities, asphalt plant demand, specifications from road agencies, and landfill tipping fees. Where landfill is cheap or processors are distant, shingles are still commonly landfilled.\n\n## Context\n\nConstruction and demolition debris is a large waste stream; the US EPA estimated about 600 million tons were generated in the United States in 2018, with just under 145 million tons sent to landfill. Asphalt shingles are one of the materials the EPA tracks in that stream.","key_facts":[{"label":"US shingle waste (2007 EPA-commissioned estimate)","value":"About 11 million short tons per year"},{"label":"Reclaimed shingles accepted by US asphalt plants (2019)","value":"About 1.1 million tons"},{"label":"Main end use","value":"Hot-mix asphalt pavement"},{"label":"Key screening concern","value":"Asbestos in some older roofing"}],"regions":["North America"],"aliases":["RAS","recycled asphalt shingles","shingle recycling"],"related":["asphalt-shingle","roofing-waste","embodied-carbon-roofing","metal-roof-recycling"],"sources":[{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Sustainable Management of Construction and Demolition Materials","url":"https://www.epa.gov/smm/sustainable-management-construction-and-demolition-materials","publisher":"US Environmental Protection Agency"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"astm-a653","title":"ASTM A653","summary":"ASTM A653 is the North American specification for hot-dip galvanized (zinc-coated) and galvannealed steel sheet used in roofing and construction.","body":"ASTM A653/A653M, *Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process*, is the main North American standard for galvanized steel sheet. It covers sheet in coils and cut lengths and can be ordered in inch-pound units (A653) or SI units (A653M). ASTM lists A653/A653M-25a as the active version.\n\n## What it covers\n\nThe specification defines:\n\n- coating types: **galvanized** (pure zinc) and **galvannealed** (zinc-iron alloy produced by heat-treating the coating)\n- coating mass designations, set out in tables in the standard. In inch-pound units, galvanized coatings are designated with a \"G\" followed by the total coating mass in hundredths of an ounce per square foot (for example G90). Metric designations use \"Z\" with grams per square metre.\n- steel designations such as commercial, forming, drawing and structural steel grades\n- testing, tolerances and ordering rules\n\nGalvanized sheet is produced on continuous lines in which steel strip is cleaned and passed through molten zinc.\n\n## Use in roofing\n\nGalvanized steel has long been used for corrugated and ribbed roofing, flashings, gutters and roof decks. Today most residential and commercial steel roofing in North America uses either A653 galvanized or [ASTM A792](/astm-a792) aluminum-zinc coated steel as the base, with a factory paint system on top. Heavier zinc coatings are chosen for harsher environments, such as coastal or agricultural exposures.\n\n## How zinc protects steel\n\nZinc corrodes in preference to steel (sacrificial or galvanic protection), so small scratches and cut edges are protected by the surrounding coating. The life of the coating is roughly proportional to its thickness and depends strongly on the environment.\n\n## Related standards\n\n- In Europe, zinc-coated steel sheet is covered by [EN 10346](/en-10346), with coatings designated Z (zinc), ZF (zinc-iron), ZA, ZM (zinc-magnesium), AZ and AS.\n- Hot-dip galvanizing of fabricated steel (as opposed to sheet) is covered by other standards, such as ISO 1461.","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Active version","value":"A653/A653M-25a"},{"label":"Coatings","value":"Galvanized (zinc) and galvannealed (zinc-iron)"},{"label":"Units","value":"Inch-pound (A653) or SI (A653M)"},{"label":"European counterpart","value":"EN 10346"}],"regions":["North America","Global"],"aliases":["A653","G90","galvanized steel standard","ASTM A 653"],"related":["astm-a792","en-10346","metal-roofing","corrugated-iron","galvanized-steel-roofing"],"sources":[{"title":"ASTM A653/A653M-23 Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed)","url":"https://store.astm.org/a0653_a0653m-23.html","publisher":"ASTM International"},{"title":"Hot-dip galvanization","url":"https://en.wikipedia.org/wiki/Hot-dip_galvanization","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-a792","title":"ASTM A792","summary":"ASTM A792 is the North American specification for steel sheet hot-dip coated with 55% aluminum-zinc alloy, widely used for metal roofing.","body":"ASTM A792/A792M, *Standard Specification for Steel Sheet, 55 % Aluminum-Zinc Alloy-Coated by the Hot-Dip Process*, covers steel sheet in coils and cut lengths coated with a 55% aluminium-zinc alloy. This coating is sold under trade names such as Galvalume and Zincalume and is one of the most common substrates for metal roofing and wall panels worldwide. The 2023 edition is A792/A792M-23.\n\n## What it covers\n\nThe standard defines:\n\n- the coating alloy and how it is applied (continuous hot-dip process)\n- coating mass designations, which state how much coating is on the sheet\n- steel designations, including commercial, forming, drawing, high-temperature and structural steel grades\n- tolerances, testing and ordering information\n\nThe product is intended where corrosion resistance, heat resistance or both are needed.\n\n## Why aluminum-zinc\n\nThe aluminium in the coating forms a stable oxide barrier that slows general corrosion, while the zinc provides some sacrificial protection at cut edges and scratches. In many atmospheres this gives longer life than plain zinc (galvanized) coatings of similar thickness. Aluminum-zinc coatings are less suited to direct contact with wet concrete, mortar or some treated timbers, and their cut-edge protection is lower than zinc's.\n\n## Use in roofing\n\nMost painted steel roofing in North America is either A792 aluminum-zinc or [ASTM A653](/astm-a653) galvanized steel with a paint system on top. Bare (unpainted) A792 sheet is also used on agricultural and industrial buildings. Paint and finish warranties from coil coaters and panel makers usually specify the coating designation required.\n\n## International equivalents\n\n- In Europe, aluminum-zinc coated steel is designated **AZ** under [EN 10346](/en-10346), with coating masses such as AZ150 or AZ185 (grams per square metre, both sides).","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Edition","value":"A792/A792M-23"},{"label":"Coating","value":"55% aluminum-zinc alloy, hot-dip"},{"label":"Product form","value":"Steel sheet in coils and cut lengths"},{"label":"European equivalent","value":"EN 10346 (AZ coatings)"}],"regions":["North America","Global"],"aliases":["A792","Galvalume standard","AZ50","AZ55","aluminum-zinc coated steel"],"related":["astm-a653","en-10346","metal-roofing","galvalume","standing-seam-metal-roof"],"sources":[{"title":"ASTM A792/A792M-23 Steel Sheet, 55% Aluminum-Zinc Alloy-Coated by the Hot-Dip Process","url":"https://store.astm.org/a0792_a0792m-23.html","publisher":"ASTM International"},{"title":"EN 10346:2015","url":"https://genorma.com/en/standards/en-10346-2015","publisher":"Genorma (CEN catalogue data)"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-b370","title":"ASTM B370","summary":"ASTM B370 is the US specification for copper sheet and strip used in building construction, including roofing, flashing and gutters.","body":"ASTM B370, *Standard Specification for Copper Sheet and Strip for Building Construction*, covers rolled copper sheet and strip in flat lengths or coils for roofing, cladding, flashings, gutters, downspouts and general sheet metal work. The active edition is ASTM B370-22. The standard notes that products made to it are not intended for electrical uses.\n\n## Tempers\n\nCopper's hardness (temper) affects how easily it can be formed and how well it holds its shape. B370 lists tempers including:\n\n- **O60** – soft\n- **H00** – cold-rolled (often called eighth-hard)\n- **H01** – cold-rolled, high-yield (quarter-hard)\n- **H02** – half-hard\n- **H03** – three-quarter hard\n- **H04** – hard\n\nCold-rolled copper is the most common temper in US building construction because it is much stronger than soft copper while still workable. Eighth-hard cold-rolled copper is often recommended for roofing and flashing, and quarter-hard high-yield copper is used mainly for flashing where strength and some formability are both needed. Soft copper is used for intricate forming and where it must conform to irregular shapes.\n\n## Thickness by weight\n\nIn the United States, architectural copper thickness is usually stated as weight in ounces per square foot. Common construction weights range from about 12 oz to 48 oz per square foot; gutters and downspouts often use 16 oz or 20 oz copper. In Europe, roofing copper is usually specified by thickness, typically 0.6 to 0.7 mm (about 0.024 to 0.028 in).\n\n## Durability\n\nCopper forms a protective patina that progresses from oxides to darker sulfides and eventually to the green basic sulfate familiar on old roofs. Full green patina may take around 7 to 9 years in marine air and 15 to 25 years in industrial settings, and longer in clean rural air. Once formed, corrosion is very slow, so properly detailed copper roofs can last for centuries.\n\n## Related standards\n\nIn Europe, copper sheet for building is covered by a separate European Standard. Copper roofing systems such as standing seam, batten seam and flat-lock soldered roofs are installed following trade guidance rather than B370 itself.","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Active edition","value":"B370-22"},{"label":"Tempers","value":"O60, H00, H01, H02, H03, H04"},{"label":"Typical roofing weight","value":"16–20 oz/ft² (about 0.55–0.69 mm)"},{"label":"Not for","value":"Electrical applications"}],"regions":["North America"],"aliases":["B370","copper sheet standard","16 oz copper"],"related":["copper-roofing","standing-seam-metal-roof","roof-flashing","copper-patina","en-988"],"sources":[{"title":"Standard Specification for Copper Sheet and Strip for Building Construction","url":"https://store.astm.org/standards/b370","publisher":"ASTM International"},{"title":"Copper in architecture","url":"https://en.wikipedia.org/wiki/Copper_in_architecture","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-c406","title":"ASTM C406","summary":"ASTM C406 is the North American specification for natural roofing slate, grading it S1, S2 or S3 by strength, absorption and weathering tests.","body":"ASTM C406, *Standard Specification for Roofing Slate*, sets material and physical requirements for natural slate used as roof shingles in North America. The active version listed by ASTM is C406/C406M-22.\n\n## What it covers\n\nThe specification deals with the characteristics, physical requirements and sampling procedures for selecting slate for roofing. It excludes slates containing soft carbonaceous \"ribbons\" (bands of different composition), because their properties vary widely and their service life is uncertain.\n\n## Grades\n\nRoofing slate is classified into three grades:\n\n- **Grade S1** – the highest grade, intended for the longest service.\n- **Grade S2** – intermediate.\n- **Grade S3** – the lowest grade.\n\nEach grade must meet requirements for:\n\n- **Breaking load (modulus of rupture)** – how much force the slate can carry before snapping.\n- **Absorption** – how much water the slate takes up. Lower absorption generally means better resistance to freeze-thaw damage.\n- **Depth of softening** – a weathering test in which slate is exposed to acid to see how deeply its surface softens, simulating attack by polluted rain.\n\nThe specific numerical limits are in the standard itself. ASTM C406 itself does not state a service life for each grade.\n\n## Use\n\nArchitects specify a grade in project documents, and quarries test their product and state the grade on data sheets. Slate from the same quarry can vary between beds, so testing is done on representative samples.\n\n## Comparison with Europe\n\nThe European equivalent is [EN 12326](/en-12326), which uses a different set of tests and declared codes rather than three grades. Imported European slate sold in North America is sometimes tested to both standards. The two systems do not convert directly.\n\n## Installation\n\nASTM C406 covers only the material. Slate roof installation in North America follows manufacturer and trade guidance, such as that of national roofing contractor and slate associations.","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Active version","value":"C406/C406M-22"},{"label":"Grades","value":"S1 (highest), S2, S3"},{"label":"Tests","value":"Breaking load, absorption, depth of softening"},{"label":"Excludes","value":"Ribbon slates with soft carbonaceous bands"}],"regions":["North America"],"aliases":["C406","ASTM C 406","S1 slate","roofing slate grades"],"related":["natural-slate","en-12326","slate-roof-installation"],"sources":[{"title":"Standard Specification for Roofing Slate","url":"https://store.astm.org/standards/c406","publisher":"ASTM International"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-d225","title":"ASTM D225","summary":"ASTM D225 was the US specification for organic-felt asphalt shingles; it was withdrawn in 2012 after organic shingles left the North American market.","body":"ASTM D225, *Standard Specification for Asphalt Shingles (Organic Felt) Surfaced With Mineral Granules*, was the ASTM International product standard for asphalt shingles made with an organic felt mat. The last edition was D225-07. ASTM withdrew the standard in 2012 without a replacement.\n\n## What it covered\n\nOrganic shingles were made from a felt of cellulose fibres (paper, rag or wood fibre) saturated and coated with asphalt and surfaced with mineral granules on the weather side. D225 set requirements for these products as manufactured and called for a headlap of at least 51 mm (2 in).\n\nOrganic shingles were heavier and more flexible in cold weather than early fiberglass shingles, and for decades they were common in the northern United States and Canada. They absorbed more asphalt, however, and were more prone to curling, blistering and moisture absorption over time. They also generally had lower fire ratings than fiberglass shingles.\n\n## Why it was withdrawn\n\nFiberglass-mat shingles, specified under [ASTM D3462](/astm-d3462), steadily replaced organic shingles. Most large manufacturers stopped making organic shingles in the mid-to-late 2000s, and Building Products of Canada, the last North American producer, ended production in 2011. With no products left to specify, ASTM withdrew D225 in 2012.\n\n## Why it still matters\n\nMany roofs installed before about 2010 still have organic shingles. Inspectors, insurers and roofers may see D225 on older product documentation, warranty paperwork and building plans. Older codes and specifications also refer to it. When an existing organic roof is repaired, exact matching products are no longer made, so repairs usually use fiberglass shingles of a similar appearance.","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Last edition","value":"D225-07"},{"label":"Status","value":"Withdrawn 2012, no replacement"},{"label":"Reinforcement","value":"Organic felt"},{"label":"Successor technology","value":"Fiberglass shingles (ASTM D3462)"}],"regions":["North America"],"aliases":["D225","organic shingle standard","ASTM D 225"],"related":["astm-d3462","asphalt-shingle","roofing-felt"],"sources":[{"title":"Standard Specification for Asphalt Shingles (Organic Felt) Surfaced With Mineral Granules (Withdrawn 2012)","url":"https://store.astm.org/standards/d225","publisher":"ASTM International"},{"title":"Understanding asphalt shingle standards","url":"https://www.professionalroofing.net/articles/article/4817","publisher":"Professional Roofing (NRCA)"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-d3161","title":"ASTM D3161","summary":"ASTM D3161 is a US laboratory test that rates the wind resistance of asphalt shingles by blowing air across a test deck with a fan.","body":"ASTM D3161, *Standard Test Method for Wind-Resistance of Asphalt Shingles (Fan-Induced Method)*, is published by ASTM International. It is one of the two test methods North American building codes accept for showing that asphalt shingles can stay on a roof in high winds. The other is [ASTM D7158](/astm-d7158).\n\nIn the test, shingles are installed on a small sloped deck, allowed to self-seal under heat, and then exposed to a steady stream of air from a large fan for two hours. Inspectors look for any damage, including a sealed tab that has come loose. Any lifted or torn tab counts as a failure.\n\n## Classes\n\nShingles that pass are assigned a class according to the fan speed used:\n\n- **Class A** – 60 mph (about 97 km/h)\n- **Class D** – 90 mph (about 145 km/h)\n- **Class F** – 110 mph (about 177 km/h)\n\nClass F is the rating most often seen on shingle packaging and in high-wind specifications. The IBHS FORTIFIED Roof program, for example, accepts ASTM D3161 Class F or ASTM D7158 Class H shingles.\n\n## Limits of the test\n\nThe fan speed is a laboratory condition, not a forecast of how a roof will behave in a storm. NRCA's *Professional Roofing* magazine has pointed out that D3161 results do not correlate directly with in-service wind speeds, and the method takes no account of building height, terrain exposure, importance factor or risk category. For that reason designers in high-wind areas often prefer ASTM D7158, which ties its classes to the design wind speed method used in ASCE 7.\n\n## Use in codes\n\nThe International Building Code and International Residential Code require asphalt shingles to be classified for wind resistance. According to NRCA, the codes call for shingles with factory-applied self-sealing strips to be classified under ASTM D7158, while shingles without self-sealing strips may use D3161 classes; the required class depends on the design wind speed at the site. The product standard [ASTM D3462](/astm-d3462) itself requires at least Class A (60 mph) wind resistance. In Canada, asphalt shingle product standards in the [CSA A123](/csa-a123-series) series and the National Building Code also reference wind testing. Outside North America, bitumen shingles in Europe are assessed under [EN 544](/en-544) and related CEN methods rather than D3161.\n\n## Reading a rating\n\nA label reading \"ASTM D3161 Class F\" means a sample of that shingle passed the 110 mph fan test when installed to the manufacturer's standard instructions, which may include a specific nail count. Installing with fewer nails, on a damaged deck, or in cold weather that delays sealing can reduce real-world wind performance. Manufacturers often require a high-wind nailing pattern for their highest wind warranty levels.","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Full title","value":"Standard Test Method for Wind-Resistance of Asphalt Shingles (Fan-Induced Method)"},{"label":"Test duration","value":"2 hours"},{"label":"Classes","value":"A (60 mph / 97 km/h), D (90 mph / 145 km/h), F (110 mph / 177 km/h)"},{"label":"Applies to","value":"Asphalt shingles"}],"regions":["North America"],"aliases":["D3161","ASTM D 3161","fan-induced wind test","Class F shingle rating"],"related":["astm-d7158","asphalt-shingle","ibhs-fortified-roof","international-building-code","wind-uplift"],"sources":[{"title":"Standard Test Method for Wind-Resistance of Asphalt Shingles (Fan-Induced Method)","url":"https://store.astm.org/standards/d3161","publisher":"ASTM International"},{"title":"Understanding asphalt shingle standards","url":"https://www.professionalroofing.net/articles/article/4817","publisher":"Professional Roofing (NRCA)"},{"title":"The wind resistance of shingles","url":"https://professionalroofing.net/articles/article/4302","publisher":"Professional Roofing (NRCA)"},{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/?p=2512","publisher":"IBHS FORTIFIED"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-d3462","title":"ASTM D3462","summary":"ASTM D3462 is the US product specification for fiberglass-mat asphalt shingles surfaced with mineral granules, referenced by US building codes.","body":"ASTM D3462, *Standard Specification for Asphalt Shingles Made from Glass Felt and Surfaced with Mineral Granules*, is the main product standard for asphalt shingles in the United States. Almost all asphalt shingles sold in North America today use a glass-fibre (fiberglass) mat, so D3462 covers the bulk of the market. The active version listed by ASTM is D3462/D3462M-25.\n\n## What it covers\n\nThe standard covers shingles made from glass felt that is coated on both sides with asphalt and surfaced on the weather side with mineral granules. It sets requirements for the product as manufactured, before installation, including:\n\n- minimum masses (such as the mass of asphalt and of the overall shingle)\n- physical properties such as tear strength, fastener pull-through resistance and pliability\n- dimensions and tolerances\n\nShingles meeting D3462 are designed for a headlap of at least 51 mm (2 in) and must either have a factory-applied self-sealing adhesive or be designed to lock together during installation. According to NRCA, the standard also requires at least Class A fire resistance and Class A (60 mph) wind resistance under [ASTM D3161](/astm-d3161).\n\n## What it does not cover\n\nD3462 does not set requirements for performance after installation or in service. Long-term weathering, hail resistance and higher wind ratings are covered by separate standards such as [UL 2218](/ul-2218) and [ASTM D7158](/astm-d7158).\n\n## Code use\n\nThe International Building Code and International Residential Code reference ASTM D3462 as a minimum requirement for asphalt shingles. Product packaging and data sheets normally state compliance with it.\n\n## Related standards\n\n- **[ASTM D225](/astm-d225)** covered organic-felt shingles and was withdrawn in 2012 because organic shingles are no longer made in North America.\n- **ASTM D3018** is a less common product standard that covers Class A fire-resistant shingles in self-sealing and non-self-sealing types.\n- In Canada, asphalt shingle product requirements are in the [CSA A123](/csa-a123-series) series.\n- In Europe, bitumen shingles are specified under [EN 544](/en-544).","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Active version","value":"D3462/D3462M-25"},{"label":"Reinforcement","value":"Glass felt (fiberglass mat)"},{"label":"Minimum headlap","value":"51 mm (2 in)"},{"label":"Code reference","value":"IBC and IRC"}],"regions":["North America"],"aliases":["D3462","ASTM D 3462","fiberglass shingle standard"],"related":["asphalt-shingle","astm-d225","astm-d3161","astm-d7158","en-544"],"sources":[{"title":"Standard Specification for Asphalt Shingles Made from Glass Felt and Surfaced with Mineral Granules","url":"https://store.astm.org/standards/d3462","publisher":"ASTM International"},{"title":"Understanding asphalt shingle standards","url":"https://www.professionalroofing.net/articles/article/4817","publisher":"Professional Roofing (NRCA)"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-d4434","title":"ASTM D4434","summary":"ASTM D4434 is the North American material specification for reinforced poly(vinyl chloride) (PVC) sheet used as single-ply roofing membrane.","body":"ASTM D4434/D4434M, *Standard Specification for Poly(Vinyl Chloride) Sheet Roofing*, sets minimum requirements for PVC single-ply roofing membranes. The active version is D4434/D4434M-21.\n\n## What it covers\n\nThe specification covers flexible sheet made from poly(vinyl chloride) resin for use as single-ply roofing exposed to the weather. Under the current edition the sheet must contain reinforcing fibres or fabric. Properties addressed include thickness, breaking strength, elongation, seam strength of factory seams, tearing strength, low-temperature bending, dimensional stability, water absorption, and resistance to heat ageing and weathering.\n\nThe specification does not cover in-place roof design matters such as fire resistance and wind uplift, which are demonstrated by system testing and code compliance.\n\n## About PVC membranes\n\nPVC is a rigid plastic, so roofing membranes contain plasticizers to make them flexible. Over many years plasticizer can migrate out of the sheet, especially in contact with incompatible materials such as asphalt or polystyrene insulation, leaving the membrane brittle. Formulation, thickness and separation layers are used to manage this. PVC membranes are heat-welded at seams and are known for good resistance to many chemicals, oils and fats, which makes them common on restaurant roofs and some industrial buildings.\n\nPVC is one of the thermoplastic membranes (along with TPO and KEE blends) that together hold a large share of the US commercial roofing market.\n\n## Related standards\n\n- [ASTM D6878](/astm-d6878) covers TPO membranes.\n- [ASTM D4637](/astm-d4637) covers EPDM membranes.\n- In Europe, PVC roofing membranes are specified under a harmonised European standard for plastic and rubber roof waterproofing sheets.","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Active version","value":"D4434/D4434M-21"},{"label":"Material","value":"Poly(vinyl chloride) sheet with reinforcement"},{"label":"Seaming","value":"Heat-welded"},{"label":"Scope limit","value":"Excludes fire resistance and wind uplift"}],"regions":["North America"],"aliases":["D4434","PVC roofing standard","ASTM D 4434"],"related":["pvc-roofing","astm-d6878","astm-d4637","single-ply-roofing"],"sources":[{"title":"Standard Specification for Poly(Vinyl Chloride) Sheet Roofing","url":"https://store.astm.org/standards/d4434","publisher":"ASTM International"},{"title":"Membrane roofing","url":"https://en.wikipedia.org/wiki/Membrane_roofing","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-d4637","title":"ASTM D4637","summary":"ASTM D4637 is the North American material specification for EPDM rubber sheet used as a single-ply roofing membrane, in three types.","body":"ASTM D4637/D4637M, *Standard Specification for EPDM Sheet Used In Single-Ply Roof Membrane*, sets minimum quality requirements for ethylene propylene diene terpolymer (EPDM) roofing membranes. EPDM is a synthetic rubber and one of the oldest single-ply roofing materials in North America. The active version is D4637/D4637M-15 (reapproved 2021, with an editorial change).\n\n## Types\n\nThe specification recognizes three types of sheet:\n\n- **Type I** – non-reinforced rubber sheet, the most common form, usually black.\n- **Type II** – sheet with internal fabric or scrim reinforcement, often used for mechanically attached systems.\n- **Type III** – fabric-backed sheet, where a fleece or fabric is bonded to the underside, often for adhered systems.\n\n## What it covers\n\nThe standard covers flexible EPDM sheet for single-ply roofing exposed to the weather. Tests and property limits set minimum quality levels for properties such as thickness, tensile strength, elongation, tear resistance, brittleness at low temperature, ozone resistance, heat ageing and weathering.\n\nIt excludes in-place roof design factors including fire resistance, field seam strength, material compatibility and uplift resistance. Those depend on the whole roof system and are addressed through system tests and codes.\n\n## About EPDM roofing\n\nEPDM is a thermoset: it is cured during manufacture and cannot be heat-welded. Seams are made with adhesives or factory-applied seam tapes. EPDM is flexible over a wide temperature range and resists ultraviolet light and ozone well. Black EPDM absorbs heat; white-surfaced versions exist for cooler roofs.\n\nBecause it does not leach plasticizers, EPDM is also used for pond liners and rainwater harvesting roofs.\n\n## Related standards\n\n- [ASTM D6878](/astm-d6878) (TPO) and [ASTM D4434](/astm-d4434) (PVC) cover thermoplastic membranes.\n- In Europe, EPDM roofing sheet is specified under a harmonised European standard for plastic and rubber roof waterproofing sheets.","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Active version","value":"D4637/D4637M-15 (R2021)"},{"label":"Types","value":"I non-reinforced, II scrim-reinforced, III fabric-backed"},{"label":"Seaming","value":"Adhesive or seam tape (not weldable)"}],"regions":["North America"],"aliases":["D4637","EPDM standard","rubber roof standard"],"related":["epdm-roofing","astm-d6878","astm-d4434","single-ply-roofing"],"sources":[{"title":"Standard Specification for EPDM Sheet Used In Single-Ply Roof Membrane","url":"https://store.astm.org/standards/d4637","publisher":"ASTM International"},{"title":"Membrane roofing","url":"https://en.wikipedia.org/wiki/Membrane_roofing","publisher":"Wikipedia"},{"title":"EPDM rubber","url":"https://en.wikipedia.org/wiki/EPDM_rubber","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-d6162-d6163-d6164","title":"ASTM D6162, D6163 and D6164 (SBS Modified Bitumen)","summary":"ASTM D6162, D6163 and D6164 are US specifications for SBS-modified bitumen roofing sheets, differing by their reinforcement type.","body":"ASTM D6162, D6163 and D6164 are a family of ASTM International specifications for **SBS-modified bituminous sheet materials**, the rubber-modified asphalt membranes widely used in multi-ply low-slope roofing and waterproofing. SBS (styrene-butadiene-styrene) is a thermoplastic elastomer that makes asphalt more flexible, especially in cold weather.\n\nThe three standards differ mainly in the reinforcement inside the sheet:\n\n- **ASTM D6162** – reinforced with a **combination of polyester fabric and glass fibre**. Active version: D6162/D6162M-21.\n- **ASTM D6163** – reinforced with **glass fibre**.\n- **ASTM D6164** – reinforced with **polyester**.\n\nEach covers prefabricated sheets, with or without mineral granule surfacing, intended for multiple-ply roofing and waterproofing membranes.\n\n## Why reinforcement matters\n\n- **Polyester** reinforcement gives high elongation and puncture resistance, so the membrane can stretch with building movement.\n- **Glass fibre** gives dimensional stability and resists shrinkage but stretches less.\n- **Combination** reinforcement aims to balance the two.\n\nDesigners choose base sheets and cap sheets with different reinforcements to suit deck movement, traffic and climate.\n\n## Typical properties\n\nThe specifications set limits for properties such as thickness, mass, tensile strength, elongation, tear strength, low-temperature flexibility, dimensional stability, compound stability (resistance to flow at high temperature) and granule adhesion.\n\n## Installation methods\n\nSBS sheets can be applied in hot asphalt, with cold adhesives, as self-adhered sheets, or by torch application (for torchable products). Field performance and fire and wind ratings are system properties tested separately (for example under [FM 4470](/fm-4470), [UL 1897](/ul-1897) and [ASTM E108](/astm-e108-ul-790)).\n\n## History and related standards\n\nPolymer-modified bitumen membranes were developed in Europe in the mid-1960s and have been in common use in the United States since about 1975. APP (atactic polypropylene) modified sheets, which are usually torch-applied, are covered by companion ASTM specifications. In Europe, reinforced bitumen sheets for roof waterproofing are specified under a harmonised European standard.","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Modifier","value":"SBS (styrene-butadiene-styrene)"},{"label":"D6162","value":"Polyester + glass fibre combination"},{"label":"D6163","value":"Glass fibre reinforcement"},{"label":"D6164","value":"Polyester reinforcement"}],"regions":["North America"],"aliases":["D6162","D6163","D6164","SBS mod bit standard","modified bitumen ASTM"],"related":["modified-bitumen-roofing","built-up-roofing","fm-4470"],"sources":[{"title":"Standard Specification for SBS Modified Bituminous Sheet Materials Using a Combination of Polyester and Glass Fiber Reinforcements","url":"https://store.astm.org/standards/d6162","publisher":"ASTM International"},{"title":"Membrane roofing","url":"https://en.wikipedia.org/wiki/Membrane_roofing","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-d6878","title":"ASTM D6878","summary":"ASTM D6878 is the North American material specification for thermoplastic polyolefin (TPO) sheet used as single-ply roofing membrane.","body":"ASTM D6878/D6878M, *Standard Specification for Thermoplastic Polyolefin Based Sheet Roofing*, sets minimum material requirements for TPO roofing membranes. TPO is a heat-weldable single-ply membrane widely used on low-slope commercial roofs in North America and increasingly elsewhere. ASTM lists D6878/D6878M-26 as the active version.\n\n## What it covers\n\nThe specification applies to flexible sheet made with thermoplastic polyolefin as the principal polymer, intended for use as single-ply roofing exposed to the weather. Requirements include properties such as:\n\n- overall sheet thickness and thickness of the coating over the reinforcing scrim\n- breaking strength and elongation\n- tearing strength\n- low-temperature brittleness\n- dimensional stability\n- heat ageing and resistance to ultraviolet light and weathering\n\nLike other ASTM membrane specifications, D6878 deals with the sheet as manufactured. In-place roof performance, such as fire rating, wind uplift and seam strength in the field, is covered by system tests and code requirements, for example [UL 1897](/ul-1897), [FM 4470](/fm-4470) and [ASTM E108](/astm-e108-ul-790).\n\n## About TPO\n\nTPO compounds blend a thermoplastic such as polypropylene or polyethylene with an elastomer such as EPDM, plus fillers and stabilizers. TPO resists ultraviolet degradation and is usually white or light-coloured, which makes it common where reflective \"cool roof\" performance is wanted. Seams are joined by hot-air welding.\n\nThe specification has been revised several times as the industry gained field experience with the material.\n\n## Market context\n\nThermoplastic membranes (TPO and PVC, plus KEE) together account for a large share of the US commercial roofing market. Competing single-ply membranes are PVC under [ASTM D4434](/astm-d4434) and EPDM under [ASTM D4637](/astm-d4637).\n\n## Outside North America\n\nIn Europe, flexible thermoplastic membranes are specified under a harmonised European standard for plastic and rubber roof waterproofing sheets, which covers several polymer types rather than TPO alone; polyolefin membranes there are often called FPO (flexible polyolefin).","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Active version","value":"D6878/D6878M-26"},{"label":"Material","value":"Thermoplastic polyolefin (TPO) sheet"},{"label":"Seaming","value":"Heat-welded"},{"label":"Scope limit","value":"Material only; not in-place roof design"}],"regions":["North America"],"aliases":["D6878","TPO standard","ASTM D 6878"],"related":["tpo-roofing","astm-d4434","astm-d4637","single-ply-roofing","cool-roof"],"sources":[{"title":"Standard Specification for Thermoplastic Polyolefin Based Sheet Roofing","url":"https://store.astm.org/standards/d6878","publisher":"ASTM International"},{"title":"Membrane roofing","url":"https://en.wikipedia.org/wiki/Membrane_roofing","publisher":"Wikipedia"},{"title":"Thermoplastic polyolefin","url":"https://en.wikipedia.org/wiki/Thermoplastic_polyolefin","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-d7158","title":"ASTM D7158","summary":"ASTM D7158 rates asphalt shingle wind resistance by comparing measured uplift resistance with calculated wind uplift force, giving Classes D, G and H.","body":"ASTM D7158, *Standard Test Method for Wind Resistance of Asphalt Shingles (Uplift Force/Uplift Resistance Method)*, is an ASTM International test that classifies how well sealed asphalt shingles resist wind. Unlike the fan test in [ASTM D3161](/astm-d3161), it uses an engineering approach: the uplift force that wind would place on a shingle is compared with the shingle's measured mechanical resistance, which depends on its stiffness and the strength of its self-seal adhesive bond.\n\nBecause the classes are linked to the wind design methods of ASCE 7 (the US standard for minimum design loads), many engineers consider D7158 a closer reflection of real building conditions than D3161.\n\n## Classes\n\nThe class thresholds have changed as ASCE 7 changed. According to NRCA's *Professional Roofing*:\n\n- **2005 edition** (based on ASCE 7-02 nominal wind speeds): Class D up to 90 mph (145 km/h), Class G up to 120 mph (193 km/h), Class H up to 150 mph (241 km/h).\n- **2016 edition** (based on ASCE 7-10 ultimate design wind speeds, Vult): Class D up to 115 mph (185 km/h), Class G up to 150 mph (241 km/h), Class H up to 190 mph (306 km/h).\n\nThe 2016 classes apply to buildings in risk categories I to IV, in exposure B or C, with a mean roof height of 60 ft (18 m) or less. Outside those limits additional engineering calculation is needed. The Asphalt Roofing Manufacturers Association (ARMA) has published guidance on using D7158 when standard conditions do not apply.\n\n## Ongoing revision\n\nLater ASCE 7 editions (ASCE 7-16 onward) raised pressure coefficients for steep-slope roofs. NRCA has advised designers to apply D7158 classes with caution where ASCE 7-16 or newer codes govern, since the published class limits were derived from older pressure coefficients.\n\n## Use in codes and programs\n\nThe International Building Code and International Residential Code require self-sealing asphalt shingles to be classified under D7158 (shingles without self-seal strips may instead use [ASTM D3161](/astm-d3161) classes), with the required class set by the site's design wind speed. The IBHS [FORTIFIED Roof](/ibhs-fortified-roof) program accepts D7158 Class H or D3161 Class F shingles.\n\n## What a rating means\n\nA Class H label indicates that, under the assumptions of the standard, the sealed shingle's bond and stiffness provide enough resistance for the stated wind speed range. The rating assumes the shingles have fully sealed. Shingles installed in cold weather may not seal for weeks, and in that period they are more vulnerable than the rating suggests.","key_facts":[{"label":"Publisher","value":"ASTM International"},{"label":"Method","value":"Measured uplift resistance vs calculated uplift force"},{"label":"Classes (2016 edition)","value":"D: 115 mph, G: 150 mph, H: 190 mph (Vult)"},{"label":"Height limit for classes","value":"60 ft (18 m) mean roof height"},{"label":"Applies to","value":"Sealed asphalt shingles"}],"regions":["North America"],"aliases":["D7158","ASTM D 7158","uplift force/uplift resistance method","Class H shingle rating"],"related":["astm-d3161","asphalt-shingle","ibhs-fortified-roof","wind-uplift"],"sources":[{"title":"The wind resistance of shingles","url":"https://professionalroofing.net/articles/article/4302","publisher":"Professional Roofing (NRCA)"},{"title":"Using ASTM D7158 Where Standard Conditions Do Not Apply","url":"https://www.asphaltroofing.org/using-astm-d7158-where-standard-conditions-do-not-apply/","publisher":"Asphalt Roofing Manufacturers Association"},{"title":"Understanding asphalt shingle standards","url":"https://www.professionalroofing.net/articles/article/4817","publisher":"Professional Roofing (NRCA)"},{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/?p=2512","publisher":"IBHS FORTIFIED"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"astm-e108-ul-790","title":"ASTM E108 / UL 790 (Roof Fire Ratings)","summary":"ASTM E108 and UL 790 are the North American fire tests that rate roof coverings Class A, B or C for resistance to fire from outside the building.","body":"ASTM E108, *Standard Test Methods for Fire Tests of Roof Coverings*, and UL 790, *Standard Test Methods for Fire Tests of Roof Coverings*, are the two closely aligned North American standards used to give roofs their familiar **Class A, B or C** fire ratings. ASTM E108 is maintained by ASTM Committee E05 on fire standards; UL 790 is maintained by UL Standards & Engagement. US building codes generally accept either standard.\n\nThe tests measure how a roof covering behaves when fire comes from **outside** the building: wind-blown embers, burning debris landing on the roof, or flames spreading across the surface. They do not measure fire resistance from inside the building, which is covered by separate assembly fire-resistance tests.\n\n## Test procedures\n\nThe standards include several exposures, run on decks of wood or noncombustible material as specified by the manufacturer:\n\n- **Intermittent flame test** – a gas flame is applied to the roof surface in cycles while air blows across it, checking whether fire penetrates to the deck.\n- **Spread of flame test** – a flame and wind are applied at the eave to see how far flame travels up the roof.\n- **Burning brand test** – a burning block of wood (a \"brand\") is placed on the roof, and the deck underside is watched for flaming or penetration. UL 790 descriptions note brand exposure periods of up to 90 minutes.\n- **Flying brand test** – checks whether the covering itself breaks off and sends burning pieces into the air.\n- **Rain test** – used for treated materials such as fire-retardant wood shakes, to check that treatment does not wash out.\n\n## Classes\n\n- **Class A** – effective against severe fire exposure, giving a high degree of protection to the deck.\n- **Class B** – effective against moderate fire exposure.\n- **Class C** – effective against light fire exposure.\n\nIn all three classes the covering must stay in place and not produce flying brands.\n\n## Stand-alone and assembly ratings\n\nSome materials, such as clay and concrete tile, slate and many metal roofs, can achieve Class A on their own. Others reach Class A only as part of a tested assembly that includes a specific underlayment, cap sheet or fire barrier board. Product literature usually states whether a rating is \"stand-alone\" or \"by assembly.\"\n\n## Code use\n\nUS codes require Class A or B roofs in many situations, and wildland-urban interface codes in fire-prone areas such as California often call for Class A. In Canada, the equivalent test is CAN/ULC-S107. In Europe, external fire performance is classified under [EN 13501-5](/en-13501-5) using the [CEN/TS 1187](/cen-ts-1187) test methods.","key_facts":[{"label":"Standards","value":"ASTM E108 and UL 790"},{"label":"Classes","value":"A (severe), B (moderate), C (light exposure)"},{"label":"Tests","value":"Intermittent flame, spread of flame, burning brand, flying brand, rain"},{"label":"Fire source","value":"External (outside the building)"}],"regions":["North America"],"aliases":["E108","UL790","Class A roof","Class A fire rating","roof fire rating"],"related":["en-13501-5","cen-ts-1187","clay-roof-tile","wood-shake"],"sources":[{"title":"ASTM E108-20a Standard Test Methods for Fire Tests of Roof Coverings","url":"https://store.astm.org/e0108-20a.html","publisher":"ASTM International"},{"title":"UL 790 fire tests of roof coverings","url":"https://www.intertek.com/building/standards/ul-790/","publisher":"Intertek"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"asuka-dera","title":"Asuka-dera","category":"history","type":"place","summary":"Japan's first full Buddhist temple complex, begun in 588 with Baekje craftsmen; the first building in Japan known to have used fired roof tiles.","body":"**Asuka-dera** (also Hōkō-ji) is a Buddhist temple in Asuka, Nara Prefecture, Japan. Founded by the powerful Soga clan in the late 6th century, it is regarded as the first fully fledged Buddhist temple complex in Japan and the first building in the country roofed with fired clay tiles (kawara).\n\n## Founding\n\nThe main source is the *Nihon Shoki*, an 8th-century chronicle. It says Soga no Umako vowed to build a temple if he defeated the rival Mononobe clan, and dates the decision to 587. Construction is dated to 588 or 592, depending on the passage, with completion in 596. Historians treat these dates as approximate because the chronicle was compiled more than a century later.\n\n## Baekje craftsmen and the first tiles\n\nThe chronicle records that in 588 the Korean kingdom of Baekje sent a team to Japan: two temple builders, one specialist probably responsible for metal fittings such as the pagoda spire, **four roof-tile experts** and a painter. The tile makers brought the moulding and kiln methods used on Baekje temples, so Asuka-dera's roofs mark the start of Japanese tile making.\n\n## Move to Nara\n\nWhen the capital moved to Heijō-kyō (Nara) in the early 8th century, the temple was re-established there as **Gangō-ji**. Sources give the move as 716 or 718; which is correct is uncertain. Gangō-ji's Gokuraku-bo hall and Zenshitsu still carry what are described as the oldest surviving kawara in Japan, a direct physical link to the Asuka period tile work.\n\n## Significance for roofing\n\nBefore Asuka-dera, Japanese buildings were roofed with plant materials such as thatch and bark. Tiles remained largely a temple material for the next century, then spread to palaces and government buildings. The temple therefore stands at the head of a tradition that, over about a thousand years, made tiled roofs common on Japanese houses.","key_facts":[{"label":"Founded","value":"Begun 588 (Nihon Shoki); completed 596"},{"label":"Founder","value":"Soga no Umako"},{"label":"Baekje tile experts","value":"Four, sent in 588"},{"label":"Successor temple","value":"Gangō-ji, Nara (moved 716 or 718)"}],"regions":["East Asia"],"aliases":["Hoko-ji","Asukadera","Asuka Temple"],"related":["history-of-japanese-kawara","korean-giwa-history","earliest-fired-clay-roof-tiles"],"company":null,"sources":[{"title":"Asuka-dera","url":"https://en.wikipedia.org/wiki/Asuka-dera","publisher":"Wikipedia"},{"title":"Kawara (tile)","url":"https://www.japanesewiki.com/culture/Kawara%20(tile).html","publisher":"Japanese Wiki Corpus"}],"country":null},{"slug":"atlas-roofing","title":"Atlas Roofing Corporation","category":"manufacturers","type":"company","summary":"Atlas Roofing Corporation is a US maker of asphalt shingles, underlayment and polyiso insulation, founded in 1982 in Meridian, Mississippi.","body":"Atlas Roofing Corporation is a North American manufacturer of roofing and insulation products. It began with a single plant in Meridian, Mississippi in 1982 and has its corporate offices in Atlanta, Georgia. By its 40th anniversary in 2022 the company reported 36 facilities in North America.\n\n## Divisions\n\nAtlas is organised into several divisions:\n\n- **Shingles and underlayment**: asphalt shingles for steep-slope roofs and synthetic and felt underlayments.\n- **Roof and wall insulation**: rigid foam insulation boards for commercial roofs and building walls, including polyisocyanurate (polyiso) products.\n- **Molded products**: expanded polystyrene (EPS) and other molded foam items.\n- **WebTech**: a division providing coated and laminated facer materials.\n\n## History and brand\n\nThe company has used three logos in its history. In January 2022, to mark 40 years in business, it introduced a new brand identity and corporate tagline and moved to the website atlas-arc.com, with the updated logo retaining the globe from its original 1982 mark. Atlas has stated that its shingles have been installed on more than 1.5 million roofs.\n\n## Products in context\n\nAtlas shingles are sold mainly in the United States through roofing distributors. Like other North American shingle producers, it markets shingles together with underlayment, starter, ridge and ventilation components as a complete system eligible for extended manufacturer warranties. Its insulation business supplies the commercial low-slope roofing market, where polyiso boards are commonly installed beneath single-ply or bituminous membranes.Polyiso and EPS serve different roles: polyiso offers higher insulating value per unit thickness and is common under commercial membranes, while EPS is lighter and often used in tapered insulation and molded goods.","key_facts":[{"label":"Founded","value":"1982, Meridian, Mississippi"},{"label":"Corporate office","value":"Atlanta, Georgia"},{"label":"Facilities","value":"36 in North America (2022)"},{"label":"Products","value":"Asphalt shingles, underlayment, foam insulation"}],"regions":["North America"],"aliases":["Atlas Roofing","Atlas"],"related":["asphalt-shingle","polyiso-insulation","roofing-underlayment","eps-insulation"],"company":{"founded":"1982","headquarters":"Atlanta, Georgia, United States","website":"https://www.atlasroofing.com","known_for":["Asphalt shingles","Polyiso insulation","EPS molded products"]},"sources":[{"title":"Atlas Roofing Corporation unveils new brand as company celebrates 40th anniversary","url":"https://www.roofingcontractor.com/articles/96571-atlas-roofing-corporation-unveils-new-brand-as-company-celebrates-40th-anniversary","publisher":"Roofing Contractor"},{"title":"Atlas Roofing celebrates 40 years by giving back","url":"https://meridianstar.com/?p=25278","publisher":"The Meridian Star"}],"country":null},{"slug":"attap-roof","title":"Attap Roof","category":"materials","type":"term","summary":"Attap is the nipa-palm leaf thatch of the Malay world, once standard on kampong houses in Malaysia, Singapore, Brunei and Indonesia.","body":"Attap (Malay *atap*, literally \"roof\") is the traditional palm-leaf thatch of the Malay world, used on houses in Malaysia, Singapore, Brunei and Indonesia. The leaves come mainly from the nipa palm (*Nypa fruticans*), a mangrove palm of tidal rivers and estuaries, which also supplied material for walls. In English the word also describes a whole building type, the attap house or attap dwelling.\n\n## Use\n\nAttap covered the steep, gabled roofs of kampong (village) houses raised on posts, from simple huts to substantial houses. Until the 19th century even significant public buildings such as temples were roofed this way. In Brunei's Kampong Ayer, roofs were made of palm leaves, timber or nipa leaves (*apong*), chosen for their ability to shed rainwater.\n\n## Performance\n\n- **Heat:** attap is a good insulator, keeping interiors cooler than metal sheet.\n- **Ventilation:** the light, open construction of attap houses allowed natural cross-ventilation, a principle reused in modern Singapore buildings such as WOHA's Newton Suites.\n- **Fire:** in heat waves and droughts attap becomes dry and brittle and ignites easily. In densely packed settlements this made fire a constant danger.\n\n## Decline in Singapore\n\nSingapore's experience shows how quickly attap disappeared from cities. From the 1950s many attap roofs were replaced with zinc sheet. A series of kampong fires, culminating in the Bukit Ho Swee fire of 25 May 1961, which left more than 16,000 people homeless, became a key argument for moving residents into public flats. Attap- or zinc-roofed houses fell from 34% of Singapore homes in 1970 to 10.8% in 1980.\n\n## Today\n\nAttap now survives mainly on heritage and rural buildings. Related palm-leaf thatches include *nipa* in the Philippines and *dhani* in Myanmar, both from the same palm.\n## Sources and gaps\n\nFigures on the current use of attap: published information is limited.","key_facts":[{"label":"Meaning","value":"Malay atap, \"roof\""},{"label":"Main plant","value":"Nipa palm (Nypa fruticans)"},{"label":"Regions","value":"Malaysia, Singapore, Brunei, Indonesia"},{"label":"Singapore decline","value":"Attap/zinc homes 34% (1970) to 10.8% (1980)"}],"regions":["Southeast Asia"],"aliases":["atap","attap","nipah thatch","attap dwelling"],"related":["palm-thatch","thatch","bahay-kubo","roofing-in-malaysia","roofing-in-singapore","roofing-in-brunei","roofing-in-indonesia"],"company":null,"sources":[{"title":"Attap dwelling","url":"https://en.wikipedia.org/wiki/Attap_dwelling","publisher":"Wikipedia"},{"title":"Post-WWII fire hazards in Singapore's kampongs","url":"https://www.nus.edu.sg/nuslibraries/dsprojects/heatinurbanasia/03-cities/post-wwii-fire-hazards-in-singapores-kampongs/","publisher":"NUS Libraries and Asia Research Institute"},{"title":"'Kampong' house","url":"https://www.roots.gov.sg/Collection-Landing/listing/1077823","publisher":"National Heritage Board, Singapore (Roots.sg)"},{"title":"Kampong Ayer","url":"https://en.wikipedia.org/wiki/Kampong_Ayer","publisher":"Wikipedia"}],"country":null},{"slug":"attic-condensation","title":"Attic Condensation","type":"term","summary":"Moisture that condenses on the underside of a roof deck or framing, usually from warm indoor air leaking into a cold attic.","body":"Attic condensation is water that forms on the cold underside of a roof deck, nails, framing or underlayment when moist air contacts surfaces below its dew point. Over time it can cause frost build-up, dripping, stained ceilings, mould, rotting sheathing and rusted fasteners. It is one of the most common moisture problems in pitched roofs in cold and mixed climates.\n\n## Where the moisture comes from\n\nBuilding science research identifies air movement, not vapour diffusion, as the main way moisture reaches attics. Warm, humid indoor air leaks through gaps in the ceiling: around light fixtures, attic hatches, plumbing and wiring penetrations, and leaky ductwork. Bathroom and kitchen fans that vent into the attic rather than outdoors add large amounts of moisture.\n\n## Night sky radiation\n\nRoof surfaces radiate heat to the clear night sky and can cool below the outdoor air temperature, especially metal, membrane and shingle roofs in dry or high-altitude locations. The underside of the deck can then fall below the dew point of the attic air, causing condensation even when indoor moisture levels are moderate.\n\n## Ventilated attics\n\nIn cold climates, attic ventilation mainly keeps the roof deck cold (which also helps prevent ice dams) and removes moisture that enters from the house. Building codes in North America specify net free vent area as a ratio of the insulated ceiling area, ranging from 1:150 to 1:600; 1:300 is the most common and is typically allowed where there is an air barrier at the ceiling. Ventilation does not cure air leakage; sealing the ceiling is the primary control.\n\n## Unvented roof assemblies\n\nUnvented (conditioned) attics are increasingly used, especially where ducts or equipment are in the attic. To avoid condensation, they keep the roof deck warm, for example with rigid insulation above the deck or air-impermeable spray foam against its underside.\n\n## Signs and remedies\n\nSigns include frost on nail tips in winter, damp or blackened sheathing, and water stains after cold snaps. Remedies typically involve:\n\n1. Air sealing ceiling penetrations and duct leaks.\n2. Venting exhaust fans and dryers outdoors.\n3. Reducing indoor humidity where it is high.\n4. Correcting blocked or unbalanced attic ventilation.\n5. Adding insulation above the deck in unvented designs.","key_facts":[{"label":"Main moisture route","value":"Air leakage from the living space"},{"label":"Common code vent ratio","value":"1:300 (range 1:150 to 1:600)"},{"label":"Other cause","value":"Night sky radiation cooling of the roof"}],"regions":["North America","Europe","Global","Arctic"],"aliases":["attic moisture","roof deck condensation","attic frost","sheathing condensation","frost in attic"],"related":["ice-dam","roof-ventilation","vapor-retarder","roofing-underlayment","attic-mold","roof-leak-detection","nail-pops"],"sources":[{"title":"BSD-102: Understanding Attic Ventilation","url":"https://buildingscience.com/documents/digests/bsd-102-understanding-attic-ventilation","publisher":"Building Science Corporation"},{"title":"Ice dam (roof)","url":"https://en.wikipedia.org/wiki/Ice_dam_(roof)","publisher":"Wikipedia"},{"title":"Why Is There Frost in the Attic?","url":"https://greenbuildingadvisor.com/article/why-is-there-frost-in-the-attic","publisher":"GreenBuildingAdvisor"},{"title":"Attic frost","url":"https://structuretech.com/attic-frost/","publisher":"Structure Tech"},{"title":"Condensation control in attics and roofs in cold weather","url":"https://basc.pnnl.gov/resource-guides/condensation-control-attics-and-roofs-cold-weather","publisher":"Building America Solution Center (PNNL)"},{"title":"Attics handout","url":"https://buildingscience.com/sites/default/files/presentation-docs/2020-10_fhb_ueno_attics_handout.pdf","publisher":"Building Science Corporation"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"attic-mold","title":"Attic Mould","category":"problems-maintenance","type":"article","summary":"Mould growth on attic sheathing and framing, almost always driven by moisture from indoor air leaks, exhaust ducts or roof leaks.","body":"Attic mould is fungal growth on the underside of roof sheathing, rafters and trusses. It usually appears as black, grey or white spotting or staining, often heaviest on north-facing slopes, near the eaves, or around a bathroom fan or other moisture source. Mould needs moisture, a food source (wood and paper facings) and suitable temperatures; in attics the controllable factor is moisture.\n\n## Sources of moisture\n\n- **Indoor air leakage.** Warm, humid air rising from the house through gaps in the ceiling, light fittings, attic hatches, plumbing and wiring holes and top plates. In cold weather it condenses on the cold sheathing.\n- **Exhaust fans and dryer vents** that discharge into the attic, are disconnected, or have leaking ducts.\n- **Roof leaks** at flashings, penetrations and damaged roofing.\n- **Blocked ventilation**, for example insulation pushed against soffit vents.\n- **Damp construction materials** or high humidity from crawlspaces and basements.\n\n## Ventilation alone is not the cure\n\nBuilding-science writers and home inspectors repeatedly note that adding ventilation does not reliably stop attic mould if humid indoor air keeps leaking in. In some climates, extra ventilation brings in humid outdoor air that can make conditions worse on cold nights. The recommended order is to stop the moisture source first: air seal the ceiling plane, route all exhaust ducts outdoors, fix leaks, and then make sure intake and exhaust vents work as designed.\n\n## Assessment and remediation\n\nLight, old staining on dry wood may be inactive; a moisture meter helps check whether the wood is currently wet. Active growth, odours or extensive coverage usually call for professional assessment. Remediation methods include cleaning, abrasive or dry-ice blasting and treatment with appropriate products, followed by fixing the moisture cause. Badly damaged sheathing is replaced, often during reroofing. People with health concerns should seek guidance from local health authorities before disturbing mould.","key_facts":[{"label":"Main cause","value":"Moisture from indoor air leaks and exhaust ducts"},{"label":"Often worst on","value":"North slopes, eaves, around fans"},{"label":"Fix order","value":"Stop moisture, air seal, duct exhaust outside, then ventilate"}],"regions":["Global","North America","Europe"],"aliases":["attic mold","mouldy roof sheathing","black sheathing"],"related":["attic-condensation","roof-ventilation","roof-leak-detection","wood-rot","moisture-meter"],"company":null,"sources":[{"title":"Moldy Roof Sheathing in the Pacific Northwest","url":"https://www.greenbuildingadvisor.com/article/moldy-roof-sheathing-in-the-pacific-northwest","publisher":"GreenBuildingAdvisor"},{"title":"Ventilation Won't Prevent Attic Mold Growth","url":"https://www.homeinspector.org/?p=13005","publisher":"ASHI Reporter"},{"title":"Look for exhaust fans venting outside","url":"https://basc.pnnl.gov/diy-guides/look-exhaust-fans-venting-outside","publisher":"Building America Solution Center (PNNL)"}],"country":null},{"slug":"australian-whs-roof-work","title":"Australian WHS Roof Work Requirements","category":"installation","type":"standard","summary":"Australian work health and safety codes require roof work fall risks to be controlled through a hierarchy, with edge protection and rules based on roof pitch.","body":"In Australia, falls during roof work are controlled under the harmonised **Work Health and Safety (WHS)** laws and supporting codes of practice published by Safe Work Australia and adopted by states and territories. The **Preventing Falls in Housing Construction Code of Practice** gives detailed, practical rules for residential roofing. Some states and territories publish their own versions, so the local regulator's code should be checked.\n\n## Hierarchy of control\n\nThe code sets five levels of control for fall risks:\n\n1. **Eliminate** the risk by doing work on the ground or a solid construction.\n2. **Fall prevention devices**, such as guardrails and catch platforms. Guardrails are the main form of edge protection for roofing.\n3. **Work positioning (travel restraint)**, which stops a worker reaching an edge.\n4. **Fall arrest systems**, used only where higher controls are not reasonably practicable.\n5. **Administrative controls and ladders**, used only for remaining risk; ladders are mainly for access and short, light work.\n\n## Edge protection details\n\n- Physical edge protection should be provided for all roofing work so far as reasonably practicable.\n- Guardrails should have top and mid rails and toeboards or mesh, with the top rail at least 900 mm above the roof surface and gaps between rails no more than 450 mm.\n- Guardrails outside the roof line should leave no more than 100 mm between the roof edge (including gutter) and the rail.\n\n## Roof pitch thresholds\n\n- Workers may walk and work on roofs below the **critical angle**, which should never exceed 26 degrees, or 10 degrees on slippery surfaces.\n- Catch platforms are set no more than 1 m below the edge on roofs of 26 degrees or less, and no more than 500 mm below on steeper or slippery roofs, with infill panels above 26 degrees.\n- Roofs steeper than **35 degrees** are treated as unsuitable to stand on even with edge protection; workers need at least two of a work positioning system, a roof ladder or a scaffold platform at the edge.\n\n## Harness systems\n\nTravel restraint anchors on metal or tiled roofs may be used for short tasks. The code notes that fall arrest has limited use in housing construction, being generally suited to work above about 6.5 m, and that achieving a 15 kN anchorage on a timber roof is often difficult; any fall arrest use needs a rescue procedure.","key_facts":[{"label":"Guardrail top rail height","value":"At least 900 mm"},{"label":"Critical angle","value":"No more than 26 degrees (10 degrees if slippery)"},{"label":"Too steep to stand on","value":"Over 35 degrees"},{"label":"Fall arrest anchorage","value":"15 kN"}],"regions":["Oceania"],"aliases":["Australian roof safety code","Safe Work Australia roof work","WHS falls code"],"related":["roofing-fall-protection","work-at-height-regulations-2005","personal-fall-arrest-system"],"company":null,"sources":[{"title":"Work Health and Safety (Preventing Falls in Housing Construction) Code of Practice 2015","url":"https://legislation.gov.au/F2016L00411/asmade/2016-03-30/text/original/epub/OEBPS/document_1/document_1.html","publisher":"Federal Register of Legislation (Australia)"},{"title":"Model Code of Practice: Managing the risk of falls in housing construction","url":"https://safeworkaustralia.gov.au/system/files/documents/1810/model-cop-preventing-falls-in-housing-construction.docx","publisher":"Safe Work Australia"},{"title":"Model Code of Practice: Managing the risk of falls at workplaces","url":"https://www.safeworkaustralia.gov.au/sites/default/files/2022-10/model-cop-managing-the-risk-of-falls-at-workplaces%2021102022.docx","publisher":"Safe Work Australia"}],"country":null},{"slug":"aviation-snips","title":"Aviation Snips","category":"tools-equipment","type":"term","summary":"Compound-lever hand shears for cutting sheet metal, colour-coded by cut direction: red for left, green for right, yellow for straight.","body":"Aviation snips, also called compound snips or tin snips, are hand shears with a compound-lever mechanism that multiplies hand force, allowing clean cuts in sheet metal. They take their name from their early use in aircraft sheet metal work and are now standard tools for metal roofers, gutter installers, sheet metal and HVAC workers.\n\n## Colour code\n\nA widely used convention colours the handles by cutting direction:\n\n- **Red**: left-cutting snips, which cut curves counter-clockwise and make straight cuts where the waste falls to the left.\n- **Green**: right-cutting snips, for clockwise curves.\n- **Yellow**: straight-cutting snips, which can also cut wide curves.\n\nThe colour refers to the cut direction, not to whether the user is left- or right-handed. Some manufacturers use other colours for specialty tools such as seamers and crimpers.\n\n## Variants\n\n- **Offset snips** keep the hand above the work so long cuts can be made without the cut metal fouling the hand.\n- **Long-cut snips** for straighter, longer cuts.\n- **Bulldog or heavy snips** for thicker material.\n- **Power shears and nibblers**, electric tools used for long cuts in panels, which avoid the heat and burred edges caused by abrasive discs.\n\n## Capacity\n\nTool reviews indicate typical aviation snips cut up to about 18 gauge cold-rolled steel or 22 gauge stainless steel, though capacity varies by model. Aluminium, copper and zinc cut more easily than steel of the same thickness.\n\n## Roofing practice\n\nRoofers use snips to notch panels at eaves and ridges, trim flashing, cut around penetrations and finish trims. Metal roofing manufacturers generally discourage abrasive cut-off wheels on coated steel because hot filings embed in the finish and rust, and because heat can damage coatings at the cut edge. Snips and shears produce cleaner, cooler cuts. After cutting, filings should be swept off the roof promptly.\n\n## Safety\n\nCut sheet metal edges are very sharp. Gloves rated for cut resistance and eye protection are standard, and cut-offs should be collected rather than left on the roof.","key_facts":[{"label":"Red","value":"Left-cutting"},{"label":"Green","value":"Right-cutting"},{"label":"Yellow","value":"Straight-cutting"},{"label":"Typical capacity","value":"Up to about 18 ga cold-rolled steel"}],"regions":["Global"],"aliases":["tin snips","compound snips","metal snips"],"related":["hand-seamer","sheet-metal-brake","hemming-tool","red-rust","metal-roofing"],"company":null,"sources":[{"title":"Understanding the Aviation Tin Snips Color Code","url":"https://www.protoolreviews.com/aviation-tin-snips-color-code/","publisher":"Pro Tool Reviews"},{"title":"Tin snips and aviation snips guide","url":"https://aimsindustrial.com.au/en-nz/blogs/product-guides/tin-snips-aviation-snips-guide","publisher":"AIMS Industrial"},{"title":"How to get the most out of your aviation snips","url":"https://allfasteners.com/news/post/how-to-get-the-most-out-of-your-aviation-snips","publisher":"All Fasteners"}],"country":null},{"slug":"badgir","title":"Badgir (Windcatcher)","type":"article","summary":"A rooftop tower that catches wind and vents hot air to cool buildings, typical of Iran and the Persian Gulf, where it is called barjeel.","body":"A badgir, from Persian *bâd* (wind) and *gir* (catcher), is a tower that rises above a roof to bring moving air into a building and let warm air out. Windcatchers are a defining roof feature of hot, dry parts of Iran, and related towers are found around the Persian Gulf, where the Arabic name *barjeel* is used, and in Egypt, where the traditional form is the *malqaf*.\n\n## How it works\n\nA windcatcher works in two ways:\n\n- **Wind pressure.** Openings facing the prevailing wind push air down the shaft into the rooms below, while suction on the sheltered side draws stale air out.\n- **Stack effect.** On still days, warm indoor air rises and escapes through the tower, pulling cooler air in from courtyards or basements.\n\nAir can be cooled further as it passes over water, wet surfaces or cool masonry and soil. Towers can also flush a building with cool night air. Reported indoor temperature reductions compared with outside air are in the range of 8-12 °C (14-22 °F), though actual performance depends on design and weather.\n\n## Design variations\n\nWindcatchers may have one, four or eight openings. Square shafts are generally more efficient than round ones, and taller towers reach stronger, cooler air. In Yazd the towers are typically four- or eight-sided, while in nearby Meybod they are short and single-sided. The tallest Iranian examples reach about 34 m (112 ft); one of the tallest surviving stands in the Dowlatabad Garden in Yazd. Traditional materials are adobe, fired brick, stone and plaster.\n\n## Roofs and the city\n\nIn the Historic City of Yazd, a UNESCO World Heritage site, buildings are made of earth, roofs are formed as vaults and domes, and windcatchers punctuate the skyline alongside minarets. UNESCO describes how windcatchers, courtyards and thick earth walls together create a comfortable microclimate. Water reaches the city through *qanat* tunnels, and many traditional water reservoirs (*ab anbar*) are also ventilated by windcatchers.\n\n## Modern revival\n\nWindcatchers declined in the 20th century as mechanical air conditioning spread, but they have attracted renewed interest in the 21st century as a low-energy cooling method. Contemporary versions use lightweight metal or fabric and sometimes combine with mechanical ventilation.","key_facts":[{"label":"Meaning","value":"Wind catcher (Persian)"},{"label":"Other names","value":"Barjeel (Gulf Arabic), malqaf (Egypt)"},{"label":"Tallest examples","value":"About 34 m (112 ft)"},{"label":"Typical materials","value":"Adobe, brick, stone, plaster"},{"label":"Notable city","value":"Yazd, Iran (UNESCO)"}],"regions":["Middle East"],"aliases":["Windcatcher","Wind tower","Barjeel","Malqaf","Bâdgir"],"related":["roofing-in-iran","roofing-in-the-middle-east-and-gulf","middle-eastern-domes","roof-ventilation"],"sources":[{"title":"Windcatcher","url":"https://en.wikipedia.org/wiki/Windcatcher","publisher":"Wikipedia"},{"title":"Historic City of Yazd","url":"https://whc.unesco.org/en/list/1544","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing","country":null},{"slug":"bahay-kubo","title":"Bahay Kubo (Nipa Hut)","type":"article","summary":"Traditional Philippine stilt house with a tall, steep roof thatched in nipa, cogon or anahaw leaves, built for heavy rain and heat.","body":"The *bahay kubo*, also called the nipa hut, is the traditional rural house of the lowland Philippines. It is a light timber and bamboo house raised on posts, with a tall, steep thatched roof. It is widely regarded as an icon of Philippine culture and was the basis for the later colonial-era *bahay na bato*.\n\n## The roof\n\nThe roof (*bubong*) rests on a frame of bamboo or timber called the *balangkas*. Its main features are:\n\n- **Thatch.** Coverings are typically nipa palm leaves, cogon grass or anahaw leaves. Nipa was the most common, and palm leaves were often smoked to improve water resistance.\n- **Steep pitch.** A tall roof with a peak (*angkub*) sheds monsoon rain quickly.\n- **Long eaves** (*sibi*), sometimes extended further (*pasibi*) to shade a porch.\n- **Bamboo \"tiles\".** Some roofs used *kalaka*, halved bamboo culms laid alternately face up and face down like clay tiles, each running the full length of the slope.\n\n## Climate performance\n\nThe tall roof space lets hot air rise away from the living floor, and some houses have no ceiling so heat escapes through vents beneath the ridge. The raised floor helps with floods and pests and lets air move under the house. The light frame flexes in strong winds and can be rebuilt quickly after storms or earthquakes. The steep pitch is often cited as one reason many bahay kubo survived the ashfall from the 1991 Mount Pinatubo eruption, when heavier flat-roofed houses collapsed under the load.\n\n## Evolution\n\nIn the 19th century, wealthier families often replaced nipa thatch with Spanish-style curved clay tiles (*teja de curva*). The *bahay na bato* kept the bahay kubo's basic form but used a stone or brick lower storey; its roofs were high-pitched gables or hips (*cuatro aguas*), the latter valued for better wind resistance. Galvanised iron sheet appeared on these houses in the later 19th century.","key_facts":[{"label":"Region","value":"Philippines (lowlands)"},{"label":"Thatch","value":"Nipa palm, cogon grass, anahaw leaves"},{"label":"Roof form","value":"Tall, steep gable or hip with long eaves"},{"label":"Structure","value":"Bamboo or timber frame on posts"},{"label":"Successor","value":"Bahay na bato"}],"regions":["Southeast Asia"],"aliases":["Nipa hut","Bahay kubo","Kubo"],"related":["roofing-in-southeast-asia","thatch","hip-roof"],"sources":[{"title":"Nipa hut","url":"https://en.wikipedia.org/wiki/Nipa_hut","publisher":"Wikipedia"},{"title":"Bahay na bato","url":"https://en.wikipedia.org/wiki/Bahay_na_bato","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"bahay-na-bato","title":"Bahay na Bato","category":"world-roofing","type":"article","summary":"Spanish colonial Philippine house of stone and timber with a steep hipped or gabled roof of clay tile, thatch or, from the late 1800s, galvanised iron.","body":"The *bahay na bato* (\"house of stone\") is the urban house type that developed in the Philippines during the Spanish colonial period (1565-1898). It combines a masonry ground storey with a lighter timber upper storey, and it keeps the steep, overhanging roof of the native *bahay kubo* while changing the covering from thatch to tile and, later, metal.\n\n## Origins\n\nThe form grew out of practical failures. Spanish colonists first planned stone mansions on European lines, but a major earthquake in Manila in 1645 showed that heavy masonry upper floors were dangerous. Fire was the other recurring threat in thatched towns. Builders therefore kept a timber upper floor, which flexes in earthquakes, over a fire-resistant stone or brick base.\n\n## Roof forms\n\nRoofs are high-pitched and take three main forms:\n\n- **Hip roof** (*cuatro aguas*, \"four waters\"), sloping on all four sides. It is regarded as stronger than a gable roof because it resists wind better, and its overhang on every side shades the walls and keeps rain off.\n- **Gable roof** (*dos aguas*, \"two waters\").\n- **Combinations** of hip and gable, similar to the hip-and-gable roofs of East Asia.\n\nOver the upper-floor windows, small shed roofs called *media agua* protect window openings from sun and rain. Some houses carry carved stone spouts (gargoyles) to throw roof water clear of the walls, and later examples add decorative timber trim along the eaves.\n\n## Roof coverings\n\n- **Curved clay tiles** (*teja de curva*), the Spanish pan-and-cover tile sometimes called \"monk and nun\" tile.\n- **Thatch** of nipa, sago palm or cogon grass, carried over from the native house.\n- **Galvanised iron sheet**, introduced in later 19th-century houses; it was lighter than tile, which mattered in earthquakes, and less of a fire risk than thatch.\n\nSurviving houses show all of these, sometimes on the same street.\n\n## Legacy\n\nThe bahay na bato is a key part of Philippine architectural heritage and the model for many later revival designs. Its hipped, deep-eaved metal roofs set the pattern for much of the 20th-century Philippine house.\n\n## Local terms\n\n- *cuatro aguas* - hip roof\n- *dos aguas* - gable roof\n- *media agua* - shed roof over a window\n- *teja de curva* - curved clay tile\n- *kalaka* - halved bamboo laid like tiles","key_facts":[{"label":"Period","value":"Spanish colonial era, 1565-1898"},{"label":"Roof forms","value":"Hip (cuatro aguas), gable (dos aguas), combinations"},{"label":"Coverings","value":"Teja de curva clay tile, nipa/sago/cogon thatch, galvanised iron (later 19th century)"},{"label":"Formative event","value":"Manila earthquake of 1645"}],"regions":["Southeast Asia"],"aliases":["bahay na bato","stone house","casa de piedra"],"related":["roofing-in-the-philippines","bahay-kubo","spanish-tile","hip-roof","gable-roof","corrugated-iron","palm-thatch","bamboo-roofing"],"company":null,"sources":[{"title":"Bahay na bato","url":"https://en.wikipedia.org/wiki/Bahay_na_bato","publisher":"Wikipedia"},{"title":"Housing units in PH reach 28.5 million in 2020 (PSA census results)","url":"https://realestatenews.ph/national/housing-units-in-ph-reach-285-million-in-2020","publisher":"Real Estate News PH"}],"country":null},{"slug":"ballasted-roof-system","title":"Ballasted Roof System","category":"low-slope-systems","type":"term","summary":"A low-slope roof in which the membrane and insulation are loose-laid and held down by the weight of stone or concrete pavers.","body":"In a ballasted roof system, the waterproofing membrane is not fastened or glued across its surface. Instead, the membrane and usually the insulation beneath it are laid loose, attached only at perimeters, penetrations and flashings, and held in place against wind by a layer of heavy material on top.\n\n## Ballast materials\n\n- rounded river stone or crushed stone of specified sizes\n- concrete pavers or linked paver systems\n- in green and inverted roofs, growing medium, paving or gravel serving the same function\n\nBallast also shields the membrane from UV, hail and foot traffic.\n\n## Where it is used\n\nBallasted systems are common with EPDM and other single-ply membranes, and are the usual method for protected membrane (inverted) roofs, where the ballast also keeps the insulation boards from floating. They suit large, simple roofs on structures able to carry the extra dead load.\n\n## Design\n\nWind design is critical. In North America the wind design of ballasted single-ply systems is covered by the ANSI/SPRI RP-4 standard, and corners and perimeters, where suction is highest, typically need heavier ballast or pavers. In the UK, zero-fall inverted roof guidance requires ballast heavy enough to prevent insulation flotation so water can reach the outlets.\n\n## Advantages\n\n- fast installation with few fasteners or adhesives\n- membrane protected from weathering\n- membrane and stone can be reused at reroofing\n\n## Limitations\n\n- heavy, so the structure must be designed for it\n- stone can be scoured or blown off at corners in high winds\n- leaks are harder to locate because the membrane is covered\n- dark stone cancels the benefit of a white membrane; light ballast is needed for cool-roof performance","key_facts":[{"label":"Hold-down method","value":"Weight of stone or pavers"},{"label":"US design standard","value":"ANSI/SPRI RP-4"},{"label":"Common membranes","value":"EPDM, single-ply, inverted roof systems"},{"label":"Main limitation","value":"Dead load and wind scour"}],"regions":["Global","North America","Europe"],"aliases":["ballasted roof","loose-laid ballasted system","stone ballast roof"],"related":["epdm-roofing","protected-membrane-roof","mechanically-attached-roof-system","fully-adhered-roof-system","gravel-surfaced-roof"],"company":null,"sources":[{"title":"Technical Details: Thermoset Membranes - EPDM Technology and Repair","url":"https://roofingcontractor.com/articles/85516-technical-details-thermoset-membranes-epdm-technology-and-repairp","publisher":"Roofing Contractor"},{"title":"Cool Roofs","url":"https://www.energy.gov/energysaver/cool-roofs","publisher":"U.S. Department of Energy"},{"title":"ANSI/SPRI Standards","url":"https://www.spri.org/standards/","publisher":"SPRI"},{"title":"Major Projects: Zero falls flat roof policy","url":"https://labcwarranty.co.uk/blog/major-projects-zero-falls-flat-roof-policy/?hsLang=en","publisher":"LABC Warranty"},{"title":"Inverted roof","url":"https://www.designingbuildings.co.uk/wiki/Inverted_roof","publisher":"Designing Buildings Wiki"}],"country":null},{"slug":"bamboo-roofing","title":"Bamboo Roofing","type":"term","summary":"Roofs built with bamboo, either as split culms laid like interlocking half-pipes or as a frame for thatch and other coverings, common in tropical Asia and Latin America.","body":"Bamboo roofing uses the hollow, fast-growing stems (culms) of bamboo either as the roof covering itself or as the structural frame for another covering such as thatch, tiles or sheets. It is traditional in many parts of South and South-east Asia, East Asia and Latin America.\n\n## As a covering\n\nThe simplest bamboo covering uses culms split lengthways into half-round channels. One row is laid concave side up, running from ridge to eaves, and a second row is laid convex side up over the joints, in the same pan-and-cover principle as Roman or mission clay tiles. In the Philippines, halved bamboo sections used this way on the traditional *bahay kubo* house are called *kalaka*. The natural flexibility of bamboo can also give rooflines a gentle curve, a feature associated with some East and South-east Asian architecture.\n\n## As a structure\n\nBamboo poles are widely used as rafters, purlins and battens under palm, grass or metal coverings. Colombia is noted for advances in engineered structural bamboo, and bamboo frames are also common in Indonesia, Vietnam and Ecuador.\n\n## Durability\n\nDurability is the main limitation. Untreated bamboo is attacked by beetles, termites and fungal rot, and its internal life is commonly given as only about 2-6 years, and less than a year when it is exposed to water. Because the culm walls are thin, even small amounts of decay greatly reduce strength.\n\n## Treatment and design\n\n- **Boron treatment**, usually a mix of borax and boric acid, is the most common protection against insects. It does not protect against rot and leaches out when wet, so it must be combined with design that keeps the bamboo dry.\n- **Copper azole** is an alternative, though less tested on bamboo and more hazardous to handle.\n- **Design measures** include generous roof overhangs, drip details, raising the structure off the ground and protective coatings.\n- Traditional soaking and smoking give only limited protection.\n\n## Harvesting\n\nCulms mature over about 5-7 years. Practitioners generally prefer to harvest a few months before the wet season; harvest timing also depends on species.\n","key_facts":[{"label":"Covering method","value":"Split culms laid pan-and-cover"},{"label":"Untreated life (internal)","value":"About 2-6 years"},{"label":"Common treatment","value":"Borax and boric acid"},{"label":"Culm maturity","value":"About 5-7 years"}],"regions":["Southeast Asia","South Asia","East Asia","Latin America"],"aliases":["bamboo roof","split bamboo roof","kalaka"],"related":["palm-thatch","thatch","mission-tile","imbrex-and-tegula"],"sources":[{"title":"Bamboo construction","url":"https://en.wikipedia.org/wiki/Bamboo_construction","publisher":"Wikipedia"},{"title":"Roof","url":"https://en.wikipedia.org/wiki/Roof","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"bamileke-conical-roof","title":"Bamileke Conical Roof","category":"world-roofing","type":"term","summary":"Bamileke buildings of Cameroon's West Region pair square bamboo-panel walls with tall conical roofs; chiefdom great huts reach about 17 m.","body":"In the Bamileke chiefdoms of Cameroon's Western Highlands (the Grassfields of the West Region), the characteristic building is a square or rectangular structure topped by a high conical roof. Walls are made of prefabricated panels assembled on site, using craft techniques of binding, braiding and carving. The largest examples are the great huts of chiefdoms such as Bandjoun, whose tall conical roofs dominate the royal compound.\n\n## Form and meaning\n\nA 2026 study of Bamileke architecture describes the conical roof as a deliberate expression of social structure: a single leader at the apex and the community below, with each member on an equal footing with the others. Buildings were planned with symbolic as well as practical purposes. In chiefdoms, the roofs of notables' huts are peaked, and the number of points on a roof reflects the owner's rank.\n\n## The Bandjoun great hut\n\nThe great hut of the Bandjoun chiefdom, once the residence of the chief and containing a meeting room, is about 17 m (56 ft) high. Tradition credits its construction to King Notouom I about four centuries ago; it has been restored regularly since and has survived three fires, and its central pillars are the oldest part of the building.\n\n- **Structure**: carved wooden pillars and colonnades carry the building and surround it.\n- **Walls**: facades of bamboo interwoven with plant fibres, some worked in geometric patterns. Doors with carved panels are raised about 50 cm (20 in) above the ground to keep out runoff and animals.\n- **Interior**: three rooms and a meeting room hung with lion and panther skins, symbols of the chief and senior nobles; bamboo furniture and a central hearth.\n- **Roof**: a heavy, thick conical roof, described as dense enough that rain does not penetrate. The attic beneath it serves as a granary for firewood, groundnuts and maize. The original thatch has been replaced by corrugated iron, while the interior is unchanged.\n\nThe chief who acceded in 2004 has rebuilt heritage lost to a fire early in his reign, and a modern museum at Bandjoun holds the chiefdom's regalia and art.\n\n## Sources and gaps\n\nThe grass species and thatching method used on traditional Bamileke conical roofs, and roof pitches and spans: published information is limited.","key_facts":[{"label":"Region","value":"West Region (Grassfields), Cameroon"},{"label":"Plan","value":"Square or rectangular"},{"label":"Roof","value":"High conical roof; originally thatch"},{"label":"Landmark","value":"Bandjoun great hut, about 17 m (56 ft) high"},{"label":"Walls","value":"Bamboo panels woven with plant fibre"}],"regions":["Africa"],"aliases":["Bamileke great hut","Bandjoun chefferie","Bamileke chieftaincy house","Grassfields conical roof"],"related":["roofing-in-cameroon","thatch","conical-roof","corrugated-iron","rondavel"],"sources":[{"title":"Bandjoun","url":"https://en.wikipedia.org/wiki/Bandjoun","publisher":"Wikipedia"},{"title":"Traditional Bamileke Architecture in Western Cameroon: The Building as an Expression of Intention","url":"https://macrothink.org/journal/index.php/ijch/article/view/24045","publisher":"International Journal of Culture and History"},{"title":"Chefferie (Bandjoun)","url":"https://www.lonelyplanet.com/points-of-interest/chefferie/1300217","publisher":"Lonely Planet"}],"company":null,"country":null},{"slug":"bangla-roof","title":"Bangla Roof","category":"world-roofing","type":"term","summary":"The bangla roof is a curved, drooping-eave roof form from Bengal, copied from thatched village huts into brick temples and later Mughal and Rajput buildings.","body":"The **bangla roof** (also called the Bengal roof or *chala* roof) is a roof with a curved ridge and eaves that droop down at the corners. It began as the everyday roof of village houses in the wet Bengal delta, now divided between Bangladesh and the Indian state of West Bengal, where roofs of straw, reed or grass thatch were bent into a curve over a light frame. From about the 16th century the shape was copied in brick and stone, first in Bengal and then in the palaces, mosques and pavilions of the Mughals and Rajputs across northern India.\n\n## From thatch to masonry\n\nOn a thatched hut, the curve helps rain run off quickly and away from the mud walls. Banglapedia's survey of Bengal temple architecture says the hut-style temples were modelled directly on thatched earthen huts, and that the curve, which works on a thatched roof, was kept in brick and terracotta purely for decoration. The Gangetic delta had little building stone, so temple builders worked in burnt brick and carved terracotta, imitating the bamboo frame and thatch in fired clay.\n\n## Types\n\nBengali builders named the forms by the number of roof slopes, *chala* meaning a roof surface:\n\n- **Do-chala** (\"two roofs\"): two curved slopes meeting at a curved ridge, like a single village hut. Two do-chala units joined side by side make the **jor-bangla** (\"twin bangla\").\n- **Char-chala** (\"four roofs\"): four curved triangular slopes meeting at a point, like a curved hip roof.\n- **At-chala** (\"eight roofs\"): a char-chala with a smaller char-chala set on top to add height, giving eight roof surfaces in two tiers. Banglapedia says it became popular in the 18th and 19th centuries, especially in Hugli and Howrah.\n\nA separate family of Bengal temples, the *ratna* type, adds towers (pinnacles) on top: five in a *pancharatna*, nine in a *navaratna*.\n\n## Dated examples\n\n- **Gunjanth Siva Temple, Jessore** (Bangladesh): an at-chala temple of 1740.\n- **Kantanagar Temple, Dinajpur** (Bangladesh): a navaratna temple begun in 1704 and completed in 1752. Its nine towers were lost in the earthquake of 1897.\n- **Rasmancha, Bishnupur** (West Bengal): dated around 1600.\n\n## Spread beyond Bengal\n\nThe curved roof left Bengal in the 16th and 17th centuries. In the Agra Fort, the Khas Mahal, built about 1635 for Shah Jahan's daughters, has pavilions with Bengal-style roofs. The form also appears on the Moti Masjid in Delhi's Red Fort (1659), and later in Rajasthan, on havelis in Jaisalmer and Mandawa, on Jaisalmer *chhatris* of the 18th and 19th centuries and on the Hawa Mahal in Jaipur (1799). Nineteenth-century Sikh buildings, including the Harmandir Sahib in Amritsar, also use it.\n\n## Today\n\nVillage houses in Bangladesh and West Bengal are now more often roofed with corrugated metal sheets than with thatch, so the curved roof survives mainly in temples, mosques, and heritage buildings, and in new buildings that deliberately borrow it.","key_facts":[{"label":"Origin","value":"Thatched village huts of Bengal"},{"label":"Main types","value":"Do-chala, char-chala, at-chala"},{"label":"Masonry versions","value":"Burnt brick and terracotta temples"},{"label":"Mughal example","value":"Khas Mahal, Agra Fort (c. 1635)"}],"regions":["South Asia"],"aliases":["Bengal roof","chala roof","do-chala","char-chala","at-chala","jor-bangla"],"related":["roofing-in-bangladesh","roofing-in-india","thatch","chhatri","barrel-vault-roof","hip-roof"],"company":null,"sources":[{"title":"Temple Architecture","url":"https://en.banglapedia.org/index.php/Temple_Architecture","publisher":"Banglapedia, Asiatic Society of Bangladesh"},{"title":"Bengal roofs","url":"https://en.wikipedia.org/wiki/Bengal_roofs","publisher":"Wikipedia"}],"country":null},{"slug":"banpo-houses","title":"Banpo Houses","category":"history","type":"place","summary":"Semi-subterranean round houses with steep, overhanging thatched roofs at Banpo, a Yangshao culture village near Xi'an, China, about 4700-3600 BCE.","body":"Banpo is a Neolithic village of the Yangshao culture in the Yellow River valley, east of present-day Xi'an in Shaanxi province, China. It was occupied from about 4700 to 3600 BCE. The site was discovered in 1953 and excavated from 1954 to 1957, and the Xi'an Banpo Museum was built over it in 1957. It is one of the best-known examples of a pit-house village in East Asia.\n\n## The settlement\n\nThe site covers about 50,000 m² (12 acres). Visitors today can see the remains of 45 houses, two animal pens, more than 200 storage cellars, six pottery kilns and about 250 graves. Estimates of the population range from about 100 to 500 people. A large building near the centre is interpreted as a meeting hall, alongside a central storage area.\n\n## House construction\n\n- **Floor:** many houses were semi-subterranean, with the floor sunk about 1 m (3 ft) below the ground surface.\n- **Walls:** mud and wood on low foundations; some accounts describe wattle-and-daub walls.\n- **Frame:** timber poles and beams carried the roof.\n- **Roof:** thatch over the timber frame, steeply pitched and overhanging the walls.\n- **Heating:** a fire in the middle of each house.\n\nMost houses were round. Sinking the floor gave headroom with only a short wall above ground, and the steep pitch helped the thatch shed rain.\n\n## Significance for roofing history\n\nBanpo is among the earliest well-documented villages in China with a recognisable roof form: a steep thatched cone or pyramid on posts, overhanging a low wall. Pit-house construction continued for millennia in northern China, and dugout dwellings were still being built there in the 20th century. The site is also a reference point for comparing East Asian pit houses with those of Jomon Japan and Neolithic Korea.","key_facts":[{"label":"Culture","value":"Yangshao"},{"label":"Date","value":"About 4700-3600 BCE"},{"label":"Location","value":"Near Xi'an, Shaanxi, China"},{"label":"Floor depth","value":"About 1 m (3 ft) below ground"},{"label":"Roof","value":"Steep, overhanging thatch on timber poles"}],"regions":["East Asia"],"aliases":["Banpo village","Banpo Neolithic village","Pan-p'o"],"related":["pit-house","jomon-pit-dwellings","hemudu-stilt-houses","prehistory-of-roofing","roofing-in-china"],"company":null,"sources":[{"title":"Banpo","url":"https://en.wikipedia.org/wiki/Banpo","publisher":"Wikipedia"},{"title":"Exploring Chinese History: Banpo","url":"https://ibiblio.org/chinesehistory/contents/02cul/c03s05.html","publisher":"ibiblio"},{"title":"Roundhouse (dwelling)","url":"https://en.wikipedia.org/wiki/Roundhouse_(dwelling)","publisher":"Wikipedia"}],"country":null},{"slug":"barasti","title":"Barasti","category":"world-roofing","type":"term","regions":["Middle East"],"company":null,"summary":"Gulf houses and shelters built of date-palm fronds (arish), once common along the coasts of the UAE and its neighbours.","aliases":["arish","areesh","barasti hut","palm-frond house","palm-leaf architecture"],"body":"Barasti, also known as *arish*, is the palm-leaf building tradition of the Arabian Gulf. Walls and roofs were made from the fronds of the date palm, tied over a light frame, producing shaded, ventilated shelters suited to the hot, humid summers of the coast. In the United Arab Emirates, the Bedouin used arish shelters in the summer months.\n\n## Construction\n\nThe date palm supplied almost the whole building: trunks for posts, and dried fronds tied into panels and bundles for walls and roof. Frames were often made from mangrove poles imported from East Africa (the same imported timber used in coral-stone houses; see chandal-roof). In Qatar the word *barasti* refers to palm or reed shading. Building an arish house was a community effort carried out by families and tribes.\n\n## Scale\n\nArish was not marginal. In the 1950s Dubai had as many as 4,000 arish houses sheltering about 12,000 people, and Liwa about 800. The tradition goes back a very long way in the region: a house roughly 7,000 years old on Delma Island was built from palm trunks.\n\n## Decline\n\nAfter oil was discovered in the late 1950s, concrete, glass and steel rapidly replaced palm-leaf building. The material had not been developed technically and is less durable than concrete. Most of the craftspeople who mastered arish have since died.\n\n## Revival\n\nThe architect and researcher Sandra Piesik, who has studied arish since 2008 and wrote *Arish: Palm-Leaf Architecture*, argues for laboratory testing and new hybrid uses. She notes that the UAE has about 42 million date palms, each producing dried leaves now largely treated as agricultural waste, and that palm leaves reflect sunlight much better than concrete and glass. Reconstructions can be seen at heritage sites such as Sharjah's Al Hisn Fort and Hatta.\n\n## Related\n\nBarasti belongs to the same family as palm-thatch roofs elsewhere in the tropics. It differs from the permanent coral-stone and mud houses of Gulf towns, which used heavy flat roofs on imported poles.","key_facts":[{"label":"Material","value":"Date-palm fronds and trunks"},{"label":"Frame","value":"Often mangrove poles from East Africa"},{"label":"Dubai, 1950s","value":"Up to 4,000 arish houses"},{"label":"Decline","value":"After oil discovery, late 1950s"}],"related":["palm-thatch","chandal-roof","roofing-in-the-united-arab-emirates","roofing-in-qatar","roofing-in-bahrain","roofing-in-oman","thatch"],"sources":[{"title":"Architecture of the United Arab Emirates","url":"https://en.wikipedia.org/wiki/Architecture_of_the_United_Arab_Emirates","publisher":"Wikipedia"},{"title":"Arish: the palm leaf's role in the past and future of sustainable architecture in the UAE","url":"https://www.thenationalnews.com/arts-culture/art/arish-the-palm-leaf-s-role-in-the-past-and-future-of-sustainable-architecture-in-the-uae-1.1051472","publisher":"The National"},{"title":"Architecture of Qatar","url":"https://en.wikipedia.org/wiki/Architecture_of_Qatar","publisher":"Wikipedia"}],"country":null},{"slug":"bargeboard","title":"Bargeboard","category":"components","type":"term","summary":"A bargeboard is a board fixed along the sloping edge of a gable roof, covering the ends of the roof structure, often decoratively carved.","body":"A bargeboard (also barge board or vergeboard) is a board fixed to the projecting edge of a roof at a gable end, running along the rake or verge from the eaves to the ridge. It conceals and protects the ends of the battens, purlins or roof sheathing that overhang the gable wall, and gives the gable a finished edge. Where a gable overhang is created by projecting purlins or lookouts, it is usually capped with bargeboards.\n\n## Decorative use\n\nBargeboards became a vehicle for ornament in several traditions:\n\n- **Medieval and Tudor England:** carved oak bargeboards on timber-framed houses.\n- **Gothic Revival and Victorian:** elaborate pierced and scrolled bargeboards on cottages, lodges and villas in the UK and North America; the American Carpenter Gothic style is characterised by fretsawn \"gingerbread\" bargeboards.\n- **Scandinavian and Alpine vernacular:** carved verge boards on timber houses.\n\n## Relationship to other parts\n\nAt the eaves, the bargeboard typically meets the fascia; the junction may be finished with a small projecting piece (a sprocketed or kicked detail) or a box end. Above the bargeboard, a verge detail seals the top of the roof covering.\n\n## Materials and maintenance\n\nHistorically bargeboards were timber and needed painting. Modern versions are made in uPVC, composite and aluminium-clad timber. Because bargeboards sit at an exposed edge, they suffer from rot and wind damage, and the ends of the roof timbers behind them should be checked when replacing them.\n\n## Terminology\n\nNorth American builders often call the plain version a rake board or rake fascia, reserving \"bargeboard\" for decorative examples, while in the UK \"bargeboard\" is used for both.","key_facts":[{"label":"Location","value":"Sloping edge of a gable"},{"label":"Also called","value":"Vergeboard, rake board"},{"label":"Decorative traditions","value":"Tudor, Gothic Revival, Carpenter Gothic"}],"regions":["Europe","North America","Global"],"aliases":["barge board","vergeboard","rake board","gable board"],"related":["roof-rake","fascia","gable-roof","eaves"],"company":null,"sources":[{"title":"Eaves","url":"https://en.wikipedia.org/wiki/Eaves","publisher":"Wikipedia"},{"title":"Gable","url":"https://en.wikipedia.org/wiki/Gable","publisher":"Wikipedia"}],"country":null},{"slug":"barrel-vault-roof","title":"Barrel Roof (Barrel Vault)","category":"roof-forms","type":"article","summary":"A barrel roof is a continuously curved roof shaped like half a cylinder, the roof form of a barrel (tunnel or wagon) vault.","body":"A barrel roof has a semicircular or segmental cross-section extended along the length of the building, like a barrel or tunnel cut lengthwise. In masonry, the structure is called a barrel vault, also known as a tunnel vault or wagon vault; effectively it is a series of arches placed side by side. In modern buildings the same curved profile is produced in steel, timber, glue-laminated arches, curved metal sheeting or polycarbonate, and is often simply called a curved or arched roof.\n\n## History\n\n- The earliest known example is a tunnel vault beneath a Sumerian ziggurat at Nippur, dated to around 4000 BC.\n- Egyptian builders used tunnel vaults from about 3500 BC, mostly for underground passages, and the Ramesseum mortuary temple was vaulted in this way.\n- The Romans used barrel vaults widely but increasingly favoured groin vaults, which need thinner supporting walls and allow more openings.\n- Barrel vaults returned in medieval Romanesque churches such as Cluny Abbey, gave way to ribbed vaults in Gothic cathedrals, and were revived in the Renaissance and Baroque, including at St Peter's Basilica.\n- In the 20th century, Louis Kahn's Kimbell Art Museum in Texas used a series of vaults.\n\n## Structural behaviour\n\nA barrel vault pushes outward along its full length, so the supporting walls must be thick, buttressed or tied, or the thrust must be balanced by adjacent vaults. Intersecting two barrel vaults at right angles creates a groin vault.\n\n## Modern curved roofs\n\nCurved metal roofs, either crimp-curved profiled sheets or curved standing-seam panels, are used on houses, Dutch barn conversions, sports halls and industrial buildings. Curved roofs pair well with metals such as zinc. Lightweight arched steel buildings, including military huts, use a similar profile. Drainage is straightforward because water flows down both sides, but the flatter crown can require a covering suited to low slopes.","key_facts":[{"label":"Other names","value":"Tunnel vault, wagon vault, curved roof"},{"label":"Earliest known","value":"Nippur, c. 4000 BC"},{"label":"Structural note","value":"Continuous outward thrust"}],"regions":["Global"],"aliases":["barrel vault","tunnel vault","wagon vault","curved roof","arched roof"],"related":["dome","hyperbolic-paraboloid-roof","gambrel-roof"],"company":null,"sources":[{"title":"Barrel vault","url":"https://en.wikipedia.org/wiki/Barrel_vault","publisher":"Wikipedia"},{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"}],"country":null},{"slug":"basel-green-roof-policy","title":"Basel Green Roof Policy","type":"standard","summary":"Basel, Switzerland, has required green roofs on new and renovated flat roofs since a 2002 law change, with rules aimed at biodiversity.","body":"Basel, in northern Switzerland, is known for one of the world's most extensive green roof programs. It combined early subsidies with a legal requirement and is notable for its focus on biodiversity rather than stormwater alone.\n\n## Incentive programs\n\nBasel ran two two-year subsidy programs, funded by an Energy Saving Fund that takes 5 percent of customers' energy bills:\n\n- **1996-1997:** subsidies of 20 Swiss francs per m² for new and retrofitted green roofs;\n- **2005-2007:** subsidies of 30-40 Swiss francs per m² for retrofits only.\n\n## Legal requirement\n\nA 2002 amendment to the canton's Building and Construction Law required all new and renovated flat roofs to be greened according to design guidelines. A 2010 regulation extended this to all flat roofs in building retrofits and all new buildings with flat roofs.\n\n## Biodiversity rules\n\nBasel's guidelines aim to recreate local habitats:\n\n- substrate of native regional soil, at least 10 cm (4 in) deep, raised to 12 cm (about 5 in) in a 2015 amendment;\n- a native plant mix characteristic of the Basel region;\n- mounds about 30 cm (12 in) high and 3 m (10 ft) wide to create varied habitat for invertebrates;\n- consultation with the city's green roof expert for flat roofs over 1,000 m² (about 10,800 sq ft).\n\n## Results\n\nBy 2006, about 23 percent of Basel's flat roof area was green, and around 100 roofs (80,000 m²) have been added each year since. By 2019, Basel had about 5.7 m² of green roof per inhabitant, described by the European Environment Agency's Climate-ADAPT platform as the largest in the world. The city estimates coverage of roughly 40 percent of flat roofs, though no official figure is available. Studies of insects and snails on the roofs were ongoing at the time of the Climate-ADAPT case study.\n\n## Influence\n\nBasel's approach of pairing subsidies with mandates, and specifying native soils and plants, is frequently cited as a model for cities seeking both climate adaptation and habitat benefits from roofs.","key_facts":[{"label":"Legal requirement","value":"2002 building law amendment; extended 2010"},{"label":"Minimum substrate","value":"10 cm, raised to 12 cm in 2015"},{"label":"Flat roof area green (2006)","value":"About 23%"},{"label":"Green roof per inhabitant (2019)","value":"About 5.7 m²"}],"regions":["Europe"],"aliases":["Basel green roofs","Basel-Stadt green roof regulation"],"related":["green-roof","green-roofs-in-germany","toronto-green-roof-bylaw","copenhagen-green-roof-policy"],"sources":[{"title":"Green roofs in Basel, Switzerland: combining mitigation and adaptation measures","url":"https://climate-adapt.eea.europa.eu/en/metadata/case-studies/green-roofs-in-basel-switzerland-combining-mitigation-and-adaptation-measures-1","publisher":"Climate-ADAPT (European Environment Agency)"},{"title":"How Basel started a green-roof revolution in Europe","url":"https://livingarchitecturemonitor.com/news/how-basel-started-a-green-roof-revolution-in-europe","publisher":"Living Architecture Monitor"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"batak-toba-house","title":"Batak House (Jabu)","category":"world-roofing","type":"article","summary":"Traditional houses of the Batak of North Sumatra: the Toba jabu with a huge saddleback roof and projecting gables, and tiered Karo houses with hip roofs of ijuk.","body":"The Batak are a group of peoples of North Sumatra, Indonesia, whose traditional houses are among the most dramatic in Southeast Asia. The Toba Batak house (*jabu*, also called *rumah bolon*) is dominated by a huge, steeply pitched saddleback roof with projecting gables, while Karo Batak houses rise in tiers under great hipped roofs.\n\n## Toba Batak roofs\n\n- **Form:** a large, steeply pitched saddleback roof. Rafters angle outward from the wall plate to produce the curve, and sharply projecting triangular gables overhang the house on all sides. The front gable reaches further than the rear.\n- **Structure:** there are no internal roof trusses. Large longitudinal beams called *labe-labe*, at head height, carry the roof, and diagonal ties run from them to the gable ends instead of horizontal battens.\n- **Space:** the open roof creates most of the interior volume. A flat timber ceiling over the front third of the living area forms an attic for heirlooms and sometimes shrines.\n- **Decoration:** the front gable is carved and painted in red, white and black with suns, stars, cockerels and geometric motifs; the rear gable is plain.\n- **Covering:** roofs were traditionally thatched.\n\nThe rice barn (*sopo*) follows the same form, with grain stored inside the roof, carried on six large pillars over an open working and sleeping platform.\n\n## Karo Batak roofs\n\nKaro houses (*siwaluh jabu*) have hip roofs rather than saddle roofs, sometimes up to 15 m (about 49 ft) high. Variants include:\n\n- *rumah beru-beru* - a basic hip-and-saddle roof;\n- *si empat ayo* - four gables, made by crossing two saddle roofs at right angles;\n- *rumah tersek* - a double-storeyed roof, with a saddle roof over the lower hipped part, improving ventilation and letting cooking smoke escape;\n- *anjong-anjong* - a miniature house set on top of the roof as decoration.\n\nThe roof is thatched and bound with *ijuk*, fibre from the sugar palm (*Arenga pinnata*), without nails or screws. Painted interlaced triangles called *ajo* decorate the gable, and buffalo horns are mounted at the roof ends.\n\n## Comparison\n\nUnlike the Minangkabau *rumah gadang*, whose curved roof sits on conventional walls, the Toba roof itself forms most of the living space. Both belong to the Austronesian tradition of raised houses with steep, heavy-gabled roofs.","key_facts":[{"label":"Toba roof","value":"Saddleback with projecting gables; no internal trusses"},{"label":"Karo roof height","value":"Up to about 15 m (49 ft)"},{"label":"Traditional covering","value":"Thatch bound with ijuk (sugar-palm fibre)"},{"label":"Key beam","value":"Labe-labe (longitudinal head-height beams)"}],"regions":["Southeast Asia"],"aliases":["jabu","rumah bolon","Batak Toba house","Karo house","siwaluh jabu"],"related":["roofing-in-indonesia","rumah-gadang","gonjong-roof","tongkonan","ijuk-thatch","gable-roof","thatch"],"company":null,"sources":[{"title":"Batak architecture","url":"https://en.wikipedia.org/wiki/Batak_architecture","publisher":"Wikipedia"},{"title":"Indonesian architecture","url":"https://en.wikipedia.org/wiki/Indonesian_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"batammariba-takienta","title":"Batammariba Takienta (Tower-House)","type":"article","summary":"Earthen tower-house of the Batammariba of northern Togo and Benin, with livestock below and granaries standing on the roof terrace.","body":"The *takienta* (plural *sikien*) is the earthen tower-house of the Batammariba people, whose homeland, Koutammakou, straddles the Kara Region of northern Togo and the Atakora Department of Benin. In the Ditammari language the people's name is usually explained as \"those who shape the earth\", and the house is the clearest expression of that skill. The landscape was inscribed by UNESCO as a World Heritage site in 2004 and extended into Benin in 2023.\n\n## Form and use\n\nA takienta is built on a circular or elliptical plan and reads from outside as a cluster of linked earth towers. UNESCO describes it as a family dwelling that is at once technical, practical and religious: it also serves as a shrine for the ancestors. The ground level is given over to animals, while the family's granaries stand on the roof terrace above. Many of the houses have two levels, and some have flat roofs.\n\n## Materials\n\nThe houses are made almost entirely from what the surrounding land provides: earth for the walls and terrace, timber for the structure, and straw. Because every element is organic or unfired, the buildings depend on continual upkeep and on a living tradition of builders who know how to shape and repair them. Skills in takienta construction are among the practices targeted by a UNESCO safeguarding programme for Batammariba intangible heritage launched in 2008.\n\n## The roof terrace\n\nThe terrace is the working heart of the house. It closes the top of the ground-floor rooms, provides a raised, dry platform for storing grain away from animals and damp, and links the separate granary towers. Like the earthen flat roofs of the wider Sahel, it relies on a well-maintained earth surface to shed the rains.\n\n## Numbers and condition\n\nAccording to UNESCO, about 1,716 sikien are still lived in on the Togo side and about 1,400 on the Benin side. Heavy rains in August 2018 damaged houses in Koutammakou, and UNESCO's Heritage Emergency Fund supported a damage-assessment mission that October.\n\n## Pressures\n\nUNESCO lists several threats to the houses:\n\n- Over-use of the local environment, which makes suitable wood and straw harder to find near villages.\n- Declining interest among younger people in building and maintaining the houses.\n- Semi-urban growth and new detached houses roofed with metal sheet (\"tin roofs\").\n- Changing ways of life and climate change.\n\nThe shift to metal-sheet houses is the same one seen across West Africa: quicker to build and lower in maintenance, but a break with the earth-and-straw building culture that the takienta embodies.\n\n## Names\n\nThe area is also known as Tamberma country, and the houses are sometimes called Tamberma houses. Spellings vary between sources, including *takyenta* and *sikien* or *siken*.","key_facts":[{"label":"Location","value":"Koutammakou, northern Togo and Benin"},{"label":"Plan","value":"Circular or elliptical earth towers"},{"label":"Roof","value":"Earth terrace carrying granaries"},{"label":"Materials","value":"Earth, wood, straw"},{"label":"Inhabited houses","value":"About 1,716 (Togo), 1,400 (Benin)"},{"label":"UNESCO","value":"Inscribed 2004, extended 2023"}],"regions":["Africa"],"aliases":["takienta","sikien","takyenta","Tamberma house","tata somba","Batammariba tower-house"],"related":["roofing-in-togo","roofing-in-benin","sahelian-earthen-roofs","roofing-in-west-africa","flat-roof","mud-roof"],"sources":[{"title":"Koutammakou, the Land of the Batammariba","url":"https://whc.unesco.org/en/list/1140/","publisher":"UNESCO World Heritage Centre"},{"title":"Koutammakou","url":"https://en.wikipedia.org/wiki/Koutammakou","publisher":"Wikipedia"},{"title":"UNESCO's Heritage Emergency Fund supports Koutammakou (Togo) damage assessment","url":"https://whc.unesco.org/en/news/1932","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing","country":null},{"slug":"batten-seam-roofing","title":"Batten Seam Roofing","category":"installation","type":"article","summary":"Batten seam roofing lays metal pans between raised wooden or metal battens running down the slope, with a metal cap locked over each batten.","body":"Batten seam (or batten roll) roofing is a traditional seamed-metal method in which pans run parallel to the slope and are separated by battens fixed to the deck. The pan edges turn up against the battens, and a metal cap is folded over each batten and loose-locked into the adjacent pans. The result is a roof with bold, evenly spaced ribs. It is used in copper, zinc, lead (as wood-cored rolls), terne-coated stainless and other metals.\n\n## Construction (copper example)\n\nCopper Development Association details describe:\n\n- Battens nominally 2 x 2 in (about 50 x 50 mm), assuming caps about 1.5 in (38 mm) high.\n- Pans up to about 20 in (510 mm) wide in 16 oz copper; wider pans, over about 24 in (610 mm), in 20 oz copper.\n- Caps of the same weight as the pans, joined end to end with 1/2 in (13 mm) locks or lapped at least 3 in (75 mm).\n- A gap of about 1/16 in (1.6 mm) between pan leg and batten so the metal can move. Tapered battens, slightly narrower at the base, are the preferred way to give this clearance.\n- Cleats at transverse seams on shorter pans; one type is set as battens are installed, another is nailed to the battens.\n\n## Slopes\n\nSteep-slope transverse seam details apply from about 6 in per foot (1:2); low-slope details cover 3 to 6 in per foot (1:4 to 1:2). Roofs below 4 in per foot, or in snowy and wet climates, need special design attention.\n\n## Regional variants\n\nIn Europe, zinc and copper batten roll roofs follow similar principles with metal caps over timber rolls. In UK lead roofing, wood-cored rolls play the same role, accommodating movement between bays.","key_facts":[{"label":"Typical batten","value":"2 x 2 in (about 50 x 50 mm)"},{"label":"Movement clearance","value":"About 1/16 in (1.6 mm) each side"},{"label":"Copper weight","value":"16 oz up to ~20 in pans; 20 oz for wider"}],"regions":["Global"],"aliases":["batten roll roofing","batten seam","batten cap roof"],"related":["standing-seam-metal-roof","copper-roofing","lead-roofing","zinc-roofing","flat-seam-roofing"],"company":null,"sources":[{"title":"Batten Seam Roofing","url":"https://copper.org/applications/architecture/arch_dhb/arch-details/roofing/batten_seam_roofing.php","publisher":"Copper Development Association"},{"title":"14.3. Copper Roofing (architectural specifications)","url":"https://archive.copper.org/applications/architecture/arch_dhb/specifications/arch_specs/sheet_roofing.php","publisher":"Copper Development Association"},{"title":"The top ten dos and don'ts of rolled lead sheet","url":"https://ribaj.com/products/the-top-ten-dos-and-don-ts-of-rolled-lead-sheet","publisher":"RIBA Journal"}],"country":null},{"slug":"bau-munich","title":"BAU (Munich)","type":"event","summary":"BAU is a large biennial trade fair in Munich, Germany, for architecture, building materials and systems, organised by Messe München.","body":"BAU is an international trade fair for architecture, materials and systems held every two years in Munich, Germany. It is organised by Messe München GmbH and is marketed as the world's leading trade fair in its field. It brings together architects and planners, investors, manufacturers, distributors and the building trades. Its website is bau-muenchen.com.\n\n## Schedule\n\nBAU takes place in January in odd-numbered years. The next edition is scheduled for 11-15 January 2027 at the Munich exhibition centre (Messe München).\n\n## Relevance to roofing\n\nBAU covers the whole building, but roofing is a significant part of the exhibition. Exhibitors typically include producers of:\n\n- roof tiles, slate and fibre cement products;\n- metal roofing and cladding;\n- flat roof waterproofing membranes, insulation and roof drainage;\n- roof windows, skylights and daylighting systems;\n- building-integrated photovoltaics and solar roof systems;\n- green roof systems.\n\nBecause the audience includes many architects and engineers, BAU is often used by large manufacturers to launch new products and systems aimed at specifiers, rather than at roofing contractors alone.\n\n## Programme\n\nAlongside the exhibition halls, BAU runs forums and talks on topics such as sustainability, circular construction, digital design and building in existing stock. These themes affect roofing through requirements for energy efficiency, recycled content, product declarations and solar integration.\n\n## Related events\n\nFor the roofing and timber trades specifically, the German fair DACH+HOLZ International is more focused on contractors. In France, Batimat serves the wider construction market, and in North America the International Roofing Expo focuses on roofing.","key_facts":[{"label":"Frequency","value":"Every two years (odd years, January)"},{"label":"Organiser","value":"Messe München GmbH"},{"label":"Location","value":"Munich, Germany"},{"label":"Next edition","value":"11-15 January 2027"}],"regions":["Europe","Global"],"aliases":["BAU München","BAU Munich"],"related":["dach-holz-international","international-roofing-expo","building-integrated-photovoltaics"],"company":{"website":"https://bau-muenchen.com","parent":"Messe München GmbH","known_for":["Trade fair for architecture, materials and systems"]},"sources":[{"title":"BAU Munich","url":"https://bau-muenchen.com/en/","publisher":"Messe München"},{"title":"DACH+HOLZ International","url":"https://www.dach-holz.com/en/","publisher":"GHM"}],"category":"organizations","country":null},{"slug":"bba-agrement","title":"BBA Agrément Certificate","type":"term","summary":"A BBA Agrément Certificate is a UK document from the British Board of Agrément assessing a construction product's fitness for purpose and building regulations compliance.","body":"The **British Board of Agrément (BBA)** is a UK body that assesses and certifies construction products. It was set up by the government in 1966, initially to provide product and installer approval, and is based near Watford, where it has offices and test facilities. It describes itself as having served the construction supply chain for more than 50 years.\n\nIts best-known output is the **BBA Agrément Certificate**, which assesses a product's fitness for its intended purpose and states whether it complies with, or helps achieve compliance with, UK building regulations.\n\n## Why Agrément exists\n\nTraditional products, such as clay tiles or natural slate, are covered by long-established British and European Standards. Newer or innovative products, such as breathable membranes, liquid-applied roof coatings, insulation systems, synthetic slates and some single-ply membranes, may not be fully covered by a product standard or a code of practice. An Agrément Certificate fills that gap by evaluating the product as used in a building, often including durability, installation and how it interacts with the rest of the construction.\n\n## Roofing relevance\n\nRoofing is one of the two largest sectors covered by BBA certificates, alongside insulation, among roughly 200 product sectors. Certificates are commonly held for:\n\n- roof underlays and breathable membranes\n- single-ply and reinforced bitumen membranes\n- liquid-applied waterproofing\n- green roof systems\n- dry-fix ridge, hip and verge systems\n- insulation used in roofs\n\nSpecifiers, warranty providers and building control bodies often ask for a BBA certificate when a product is not covered by a standard such as [BS 5534](/bs-5534).\n\n## What a certificate contains\n\nA typical certificate describes the product, its intended uses, how it supports compliance with the relevant regulations (in England, Wales, Scotland and Northern Ireland), design and installation considerations, durability estimates and the basis of assessment. The BBA monitors production to check that it continues to match the certified product.\n\n## Accreditation status\n\nThe BBA's website stated in 2026 that its UKAS accreditations were suspended and that it was working with UKAS to resolve the matter. Users relying on certificates for regulatory or warranty purposes may wish to check current status.\n\n## Related systems\n\nSimilar national approval or technical assessment schemes exist elsewhere, such as Avis Techniques in France and General Building Authority Approvals in Germany. In the EU, European Technical Assessments under the [CPR](/ce-marking-construction-products) serve a harmonised role.","key_facts":[{"label":"Issuer","value":"British Board of Agrément (BBA)"},{"label":"Founded","value":"1966"},{"label":"Location","value":"Near Watford, England"},{"label":"Largest sectors","value":"Roofing and insulation"},{"label":"UKAS status (2026)","value":"Accreditations suspended per BBA website"}],"regions":["Europe"],"aliases":["BBA certificate","Agrément certificate","British Board of Agrément"],"related":["bs-5534","ce-marking-construction-products","uk-building-regulations","vapour-permeable-underlay"],"sources":[{"title":"British Board of Agrément","url":"https://en.wikipedia.org/wiki/British_Board_of_Agr%C3%A9ment","publisher":"Wikipedia"},{"title":"BBA","url":"https://www.bbacerts.co.uk/","publisher":"British Board of Agrément"}],"category":"standards-codes","company":null,"country":null},{"slug":"beaver-tail-tile","title":"Beaver-Tail Tile","type":"term","summary":"A flat clay roof tile with a rounded or shaped tail, known in German as Biberschwanz; traditional in southern and eastern Germany and central Europe.","body":"A beaver-tail tile (German *Biberschwanz*, literally \"beaver's tail\") is a flat fired-clay roof tile, usually with a rounded lower end, hung from battens by a nib. It is the classic roof tile of southern and eastern Germany and neighbouring regions of central Europe, and gives old town roofs in places such as Nuremberg and Bamberg their fine, scale-like texture.\n\n## Size\n\nThe standard German format is 36.5 by 15.5 cm (about 14.4 by 6.1 in) and about 1 cm (0.4 in) thick. The traditional southern German format is 38 by 18 cm (about 15 by 7 in), with variable thickness.\n\n## Shapes of tail\n\nMany cut shapes are made, including:\n\n- round cut (*Rundschnitt*), the most familiar form;\n- segmental cut (*Segmentschnitt*);\n- straight cut (*Geradschnitt*), with square or rounded corners;\n- hexagonal, Gothic, ogee and diamond-pointed versions;\n- narrower and shorter \"tower\" tiles for spires and turrets.\n\n## Laying methods\n\n- **Crown lay (*Kronendeckung*)**: two layers of tiles hang on the same batten, the upper layer covering the joints of the lower.\n- **Double lay (*Doppeldeckung*)**: each course has its own batten, and each tile covers a little more than half of the one below, similar to English plain tiling.\n- **Single lay (*Einfachdeckung* or *Spließdeckung*)**: only half as many tiles are used, with thin strips (*Spließe*) of wood or other material placed under the vertical joints to catch water.\n\nRidge and eaves rows are normally laid with the crown method even on double-lap roofs.\n\n## History\n\nThe tile probably originated in the 14th century around the clay pits near Nuremberg, where medieval examples survive on the city wall and castle. Beaver-tail tiles gradually replaced the two-piece curved *Mönch und Nonne* (monk and nun) tiles inherited from Roman practice. In the 18th century they were sometimes called *Ochsenzungen* (\"ox tongues\").\n\n## Distribution\n\nThe type is most widespread in southern and eastern Germany and the countries to the south and east. It is rare in western Germany and very common in Mecklenburg. Beaver-tail tiles hold well even on very steep roofs, which suits the tall roofs of central European towns.\n","key_facts":[{"label":"Standard German size","value":"36.5 x 15.5 cm (14.4 x 6.1 in)"},{"label":"Traditional size","value":"38 x 18 cm (15 x 7 in)"},{"label":"Laying methods","value":"Crown, double, single (with splints)"},{"label":"Origin","value":"Probably 14th century, Nuremberg area"}],"regions":["Europe"],"aliases":["Biberschwanz","Biberschwanzziegel","beaver tail","flat tile (German)"],"related":["plain-tile","clay-roof-tile","mission-tile"],"sources":[{"title":"Biberschwanzziegel","url":"https://de.wikipedia.org/wiki/Biberschwanzziegel","publisher":"Wikipedia (German)"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"beijing-national-stadium","title":"Beijing National Stadium","category":"history","type":"place","summary":"The 'Bird's Nest' stadium for the 2008 Beijing Olympics, whose roof and facade form a single lattice of about 121,000 tons of steel.","body":"The **Beijing National Stadium**, known as the **Bird's Nest**, was built as the main stadium of the 2008 Summer Olympics in Beijing. Its tangled lattice of steel members, which forms both the facade and the roof structure, made it one of the most recognisable stadiums in the world.\n\n## Design team\n\nThe stadium was designed by the Swiss architects **Herzog & de Meuron** (Jacques Herzog and Pierre de Meuron, with project architect Stefan Marbach) jointly with the **China Architecture Design and Research Group**, led by Li Xinggang. The artist **Ai Weiwei** acted as artistic consultant, although he later distanced himself from the project. **Arup** were the structural engineers. The nickname \"Bird's Nest\" was first used by the architects themselves.\n\n## Structure\n\nThe stadium consists of two independent structures about 15 m (50 ft) apart: a concrete seating bowl and the outer steel frame that wraps around it and spans over the stands. The frame uses about **121,000 tons of steel**, all made in China. Twenty-four trussed columns, each weighing about 1,000 tons, encase the inner bowl and carry the roof. The site covers about 204,000 m² (about 50 acres).\n\n## The roof redesign\n\nThe original design included a **retractable roof**. It was removed after a roof collapse at Paris Charles de Gaulle Airport led to a review of major projects with complex roofs. The upper roof section was altered so that it still shelters spectators from the weather.\n\n## Construction\n\n- Groundbreaking: 24 December 2003.\n- Official start of construction: March 2004.\n- Completion: June 2008.\n- Opening: 28 June 2008.\n\nDuring the Games it seated about 91,000 people, the largest capacity of any Olympic venue, and hosted the opening and closing ceremonies, athletics and the football final.\n\n## Significance\n\nThe Bird's Nest shows how roof and facade can merge into one structural system, and how a roof design can be changed late in a project because of safety concerns arising elsewhere.","key_facts":[{"label":"Architects","value":"Herzog & de Meuron with CADG"},{"label":"Structural engineer","value":"Arup"},{"label":"Steel","value":"About 121,000 tons"},{"label":"Opened","value":"28 June 2008"},{"label":"Retractable roof","value":"Dropped from the design"}],"regions":["East Asia"],"aliases":["Bird's Nest","National Stadium Beijing"],"related":["millennium-dome","munich-olympic-stadium-roof"],"company":null,"sources":[{"title":"Beijing National Stadium","url":"https://en.wikipedia.org/wiki/Beijing_National_Stadium","publisher":"Wikipedia"},{"title":"Venues of the 2008 Summer Olympics","url":"https://en.wikipedia.org/wiki/Venues_of_the_2008_Summer_Olympics","publisher":"Wikipedia"}],"country":null},{"slug":"bhutanese-shingle-roof","title":"Bhutanese Shingle Roof","category":"world-roofing","type":"term","summary":"The traditional Bhutanese roof is a gently pitched roof of loose pine shingles held down by stones on laths, raised above an open, ventilated loft.","body":"The traditional roof of Bhutan is a broad, gently sloping roof of **loose wooden shingles held down by stones**. It sits on a timber frame lifted clear of the top of the walls, leaving a tall, open loft beneath that air can blow straight through. Seen from a distance, the roof seems to float above the house, which is why it is sometimes described as a \"flying roof\". The same type of roof traditionally covered farmhouses as well as the great fortress-monasteries (*dzongs*).\n\n## Construction\n\nThe roof frame is built of hardwood and bamboo and, like other traditional Bhutanese carpentry, is assembled without nails. The covering is made of pine shingles laid loose on the frame. Rather than being nailed, they are held down by laths laid across them at regular intervals, with stones placed on the laths. The Folk Heritage Museum in Thimphu, housed in a mid-18th-century farmhouse, notes that such roofs were designed to withstand severe winter winds.\n\nUnder the roof, the space between the top of the walls and the shingles is left open at the eaves. This ventilated loft is used for storage and for drying chillies and animal skins, and is insulated in places with bamboo mats and hay. Traditional roofs have decorated timber cornices but no rain gutters.\n\n## Dzong and temple roofs\n\nDzong roofs follow the same principle on a larger scale, with flared roofs over the inner temples and heavily decorated eaves. Buddhist temples (*lhakhang*) are often crowned by gilded copper roofs or roof ornaments. Timber shingles weighted with stones were the original covering of dzong roofs; Trongsa (Tongsa) Dzong keeps one of the few surviving shingle roofs, which was being restored in 2006-07.\n\n## Change\n\nAlmost all dzong roofs, and most houses, are now covered with corrugated galvanised iron instead of shingles, and metal shingles are increasingly chosen for their durability. The heavy use of timber leaves traditional buildings vulnerable to fire and decay.\n\nThe form of the roof is protected even where the material has changed. A royal decree of 1998 requires all buildings in Bhutan to have sloping roofs, along with traditional painted timber fronts and small arched windows, and the code of etiquette known as *Driglam Namzha* sets out traditional rules for dzongs and ordinary buildings.","key_facts":[{"label":"Covering","value":"Loose pine shingles weighted with stones"},{"label":"Fixing","value":"No nails; stones on laths across the shingles"},{"label":"Under the roof","value":"Open, ventilated loft for drying and storage"},{"label":"Replaced by","value":"Corrugated galvanised iron; some metal shingles"},{"label":"Regulation","value":"Sloping roofs required by 1998 royal decree"}],"regions":["South Asia"],"aliases":["Bhutanese flying roof","Bhutan wooden shingle roof","dzong roof"],"related":["wood-shingle","roofing-in-bhutan","corrugated-iron","roof-ventilation","pagoda-roof","roofing-in-nepal"],"company":null,"sources":[{"title":"Dzong architecture","url":"https://en.wikipedia.org/wiki/Dzong_architecture","publisher":"Wikipedia"},{"title":"The Pride of Bhutanese Architecture","url":"https://folkheritagemuseum.org.bt/?p=129","publisher":"Folk Heritage Museum, Thimphu"},{"title":"Wood Work - Shingzo","url":"https://globalinch.org/craft/wood-work-shingzo/","publisher":"Global InCH"},{"title":"Architecture of Bhutan","url":"https://en.wikipedia.org/wiki/Architecture_of_Bhutan","publisher":"Wikipedia"}],"country":null},{"slug":"birch-bark-roofing","title":"Birch-Bark Roofing","category":"world-roofing","type":"article","summary":"Layers of birch bark used as a waterproof roof membrane under turf, poles or wooden shingles in Scandinavia, Finland, Russia and the Baltic region.","body":"Birch bark was the original waterproofing membrane of the northern forest. Across Norway, Sweden, Finland, Russia and neighbouring regions, builders stripped sheets of bark from birch trees and laid them in overlapping layers on roof boards. The bark is naturally rich in water-repellent compounds and very slow to rot, so it could keep a roof dry for generations, provided it was shielded from sun, wind and mechanical damage by turf, poles or shingles laid on top.\n\n## Use under turf\n\nIn the Scandinavian sod roof (*torvtak*), birch bark is the real waterproof layer and the turf mainly holds it down and protects it. Bark was laid on gently sloping roof boards; six layers were considered adequate, and up to 16 have been recorded on high-quality roofs. The lowest layers project about 8 cm (3 in) beyond the eaves to form a drip. Birch bark could last for generations, though about 30 years was a normal life for a sod roof before it was relaid. See torvtak and Scandinavian sod roofs.\n\n## The Finnish pole roof\n\nUntil the early 19th century the traditional Finnish roof was the *malkakatto*: a base of wooden slats covered with several layers of birch bark, held down by long timber poles weighted with boulders, and left unpainted. Wooden shingles replaced it during the 19th century.\n\n## Under shingles and domes\n\nIn Russia, birch bark has been used as a waterproofing material since ancient times. On the Church of the Transfiguration at Kizhi in Karelia, birch bark covers the domes beneath the carved aspen shingles. See aspen ploughshare shingles.\n\n## Iceland\n\nIceland had little usable timber, but dwarf birch was sometimes packed beneath the turf, as at Þverá in Laxárdalur, one of the sites on the country's UNESCO Tentative List.\n\n## Decline and replacement\n\nDuring the 19th and 20th centuries, clay tile, corrugated iron and other industrial coverings displaced bark-and-turf roofs in most places. When turf roofs are built today, birch bark is normally replaced by bitumen roofing felt nailed to the sarking, with a dimpled drainage membrane above it. Bark is still used in heritage conservation, where open-air museums and preservation bodies maintain traditional roofs.\n\n## Why it worked\n\n- Birch bark is flexible, light and water-resistant, and can be peeled in large sheets.\n- Layering and overlapping, like shingles, sheds water down the slope.\n- Turf or poles on top protect the bark from ultraviolet light and wind and hold it down.","key_facts":[{"label":"Function","value":"Waterproof layer under turf, poles or shingles"},{"label":"Typical layers","value":"Six; up to 16 recorded"},{"label":"Region","value":"Scandinavia, Finland, Russia"},{"label":"Modern substitute","value":"Bitumen roofing felt"}],"regions":["Europe","Arctic"],"aliases":["birch bark roof","malkakatto","bark roofing"],"related":["torvtak","scandinavian-sod-roofs","sod-roof","roofing-in-finland","roofing-in-norway","roofing-in-russia","aspen-ploughshare-shingles","roofing-in-sweden"],"company":null,"sources":[{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"},{"title":"Architecture of Finland","url":"https://en.wikipedia.org/wiki/Architecture_of_Finland","publisher":"Wikipedia"},{"title":"Russian wooden architecture","url":"https://en.wikipedia.org/wiki/Russian_wooden_architecture","publisher":"Wikipedia"},{"title":"The Church of the Transfiguration, Kizhi Island, Russia","url":"https://naturalhomes.org/kizhi-island.htm","publisher":"Natural Homes"},{"title":"The Turf House Tradition (Tentative List)","url":"https://whc.unesco.org/en/tentativelists/5589","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"bitumen-shingle","title":"Bitumen Shingle","type":"term","summary":"The usual European name for an asphalt shingle: a glass-fibre mat coated with bitumen and granules, nailed to a continuous deck.","body":"A bitumen shingle is a roofing shingle made from a reinforcing mat, usually glass fibre, coated with bitumen and surfaced with mineral granules. It is essentially the same product that is called an **asphalt shingle** or composition shingle in North America; \"bitumen\" is the term generally used in Europe for the petroleum binder that Americans call asphalt.\n\n## Construction\n\nEuropean bitumen shingles are typically built on a glass-fibre mat saturated and coated with oxidised or polymer-modified bitumen. They are nailed to a continuous supporting deck. Example product data for a common European shingle give:\n\n- **Size**: about 1,000 by 337 mm (39 by 13 in);\n- **Thickness**: about 2.9 mm (0.11 in);\n- **Weight**: about 8-9.4 kg/m² (1.6-1.9 lb/ft²);\n- **Pitch range**: from about 15-20° up to 85°, with an underlay recommended on lower pitches.\n\n## Shapes\n\nCommon cut patterns include rectangular (similar to North American three-tab shingles), beaver-tail or round, hexagonal and triangular.\n\n## Use in Europe\n\nBitumen shingles are widely sold in Europe for houses as well as garden buildings and cabins. Asphalt shingles are reported to be gaining popularity in Europe because installation costs are lower than for many traditional materials.\n\n## Standards\n\nIn Europe, bitumen shingles are CE-marked against a harmonised product standard and supplied with a Declaration of Performance. In North America, glass-mat shingles are specified to ASTM D3462.\n\n## Warranty and fixing\n\nManufacturer warranties on European bitumen shingles are typically limited to weatherproofing and depend on installation to the maker's instructions; one common product carries a 10-year weatherproof warranty. Each shingle is fixed with nails into a continuous deck.\n","key_facts":[{"label":"North American term","value":"Asphalt shingle"},{"label":"Typical European size","value":"About 1,000 x 337 mm (39 x 13 in)"},{"label":"Typical weight","value":"About 8-9.4 kg/m²"},{"label":"Shapes","value":"Rectangular, beaver-tail, hexagonal, triangular"}],"regions":["Europe","Global"],"aliases":["bituminous shingle","asphalt shingle (Europe)"],"related":["asphalt-shingle","fiberglass-shingle","three-tab-shingle","corrugated-bitumen-sheet","roll-roofing"],"sources":[{"title":"Bardoline Classic Roof Shingle","url":"https://uk.onduline.com/en/diy/products/shingles/bardoline-classic-roof-shingle","publisher":"Onduline UK"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Roof","url":"https://en.wikipedia.org/wiki/Roof","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"blue-roof","title":"Blue Roof","type":"term","summary":"A flat or low-slope roof designed to store rainwater temporarily and release it slowly, reducing peak flows to storm sewers.","body":"A blue roof is a roof designed to hold rainwater for a period and then release it slowly, rather than draining it away immediately. Blue roofs are usually flat or low-sloped and are used mainly in cities, where large areas of paving and roofs send stormwater quickly into sewers. By delaying runoff, they reduce peak flows, which helps prevent flooding and combined sewer overflows.\n\n## Types\n\n**Passive systems** have no moving parts. Water is held on the roof and released through restricted outlets:\n\n- **Roof-integrated systems** retain water on the membrane, often within a gravel layer, using weirs or flow-control devices on drains.\n- **Modular trays** placed on existing roofs that hold water and release it through controlled openings.\n- **Roof dams or checks** that hold water behind low barriers with weep holes.\n\n**Active systems** use valves (manual, timer-controlled, pneumatic or hydraulic) to control drainage. Forecast-based systems that empty the roof ahead of expected storms were proposed in 2008.\n\n## Blue-green roofs\n\nA blue-green roof combines water storage beneath a vegetated green roof. The stored water can irrigate plants, increase evapotranspiration and cooling, and still provide detention during storms.\n\n## Case example\n\nFrom 2010 to 2012, the New York City Department of Environmental Protection tested blue roofs to reduce combined sewer overflows. The pilot used passive trays with filter fabric to control drainage, and monitoring showed lower peak flows and delayed timing in the sewer system.\n\n## Design considerations\n\n- **Structural capacity** for the weight of stored water, including if outlets block. Water weighs about 10 kg per square metre per centimetre of depth (about 5.2 lb per square foot per inch).\n- **Waterproofing** suited to prolonged contact with water.\n- **Overflow drainage** so water cannot rise beyond the design depth.\n- **Drain-down time** so roofs empty before the next storm and do not become mosquito habitat.\n\n## Limits\n\nBlue roofs detain water but do not treat it; they do not remove pollutants by themselves. In drier climates, stored water can be harvested for reuse, such as irrigation or cooling.","key_facts":[{"label":"Function","value":"Temporary detention of rainwater"},{"label":"Types","value":"Passive (trays, weirs, dams) and active (valves)"},{"label":"Water load","value":"About 10 kg/m² per cm depth (5.2 lb/ft² per inch)"},{"label":"Pilot example","value":"New York City, 2010-2012"}],"regions":["Global","North America","Europe"],"aliases":["blue-green roof","stormwater detention roof","attenuation roof","stormwater roof"],"related":["green-roof","ponding-water","roof-drainage-design","rainwater-harvesting-roofs","copenhagen-green-roof-policy","overflow-drainage","protected-membrane-roof","positive-drainage"],"sources":[{"title":"Blue roof","url":"https://en.wikipedia.org/wiki/Blue_roof","publisher":"Wikipedia"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"},{"title":"Blue roof","url":"https://www.designingbuildings.co.uk/wiki/Blue_roof","publisher":"Designing Buildings Wiki"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"},{"title":"BS 6229:2018 and flat roofing systems","url":"https://ikogroup.co.uk/?p=820","publisher":"IKO"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"bluescope","title":"BlueScope","category":"manufacturers","type":"company","summary":"BlueScope is a Melbourne-based steel company, demerged from BHP in 2002, whose brands include COLORBOND, ZINCALUME and LYSAGHT roofing steel.","body":"BlueScope Steel is an Australian steel producer headquartered in Melbourne, Victoria. It was created when BHP Billiton spun off its steel business as BHP Steel on 15 July 2002, and it took the name BlueScope on 17 November 2003. It makes metallic-coated and pre-painted steel widely used for roofing in Australia and New Zealand, and operates in 14 countries with more than 15,800 employees across over 160 locations.\n\n## Roofing brands\n\n- **COLORBOND steel**: pre-painted steel for roofing, walling and rainwater goods.\n- **ZINCALUME steel**: steel with an aluminium-zinc alloy coating, used unpainted for roofing and as the substrate for painted products.\n- **TRUECORE steel**.\n- **LYSAGHT**: roll-formed roofing, walling, rainwater and structural products.\n- **BUTLER**, from the US company Butler Manufacturing.\n\n## Operations\n\nBlueScope's Australian steelmaking is centred on the Port Kembla steelworks in New South Wales, the country's largest integrated steel plant, with coating and painting at Western Port in Hastings, Victoria. It owns New Zealand Steel at Glenbrook. In the United States it merged with Butler Manufacturing in 2004 and acquired four US businesses in 2007; in 2019 it announced a USD 1 billion expansion of its US investment. In India it built a coated steel plant at Jamshedpur, opened in March 2012 through its joint venture with Tata Steel, Tata BlueScope Steel, which it sold to Tata Steel in 2025.\n\n## Regulatory history\n\nIn 2022 the Federal Court of Australia ordered BlueScope to pay a record AUD 57.5 million penalty in a cartel case brought by the Australian Competition and Consumer Commission in 2019.\n\n## Context\n\nIn Australia, steel producers such as BlueScope supply coated coil to roll-formers, who shape it into corrugated and other profiles; roofing sheet is therefore often described by both the coating brand and the profile name.","key_facts":[{"label":"Formed","value":"15 July 2002 (demerger from BHP)"},{"label":"Headquarters","value":"Melbourne, Australia"},{"label":"Roofing brands","value":"COLORBOND, ZINCALUME, LYSAGHT"},{"label":"Countries","value":"14"}],"regions":["Oceania","North America","Southeast Asia","East Asia"],"aliases":["BlueScope Steel","BHP Steel"],"related":["colorbond-steel","galvalume","corrugated-iron","metal-roofing","tata-steel-colors","stramit"],"company":{"founded":"2002","headquarters":"Melbourne, Australia","website":"https://www.bluescope.com","known_for":["COLORBOND pre-painted steel","ZINCALUME aluminium-zinc coated steel","LYSAGHT roofing profiles"]},"sources":[{"title":"BlueScope","url":"https://en.wikipedia.org/wiki/BlueScope","publisher":"Wikipedia"},{"title":"About us","url":"https://www.bluescope.com/about-us/","publisher":"BlueScope"}],"country":null},{"slug":"bmi-group","title":"BMI Group","category":"manufacturers","type":"company","summary":"BMI Group is Standard Industries' European-based roofing and waterproofing group, formed in 2017 from Braas Monier and Icopal.","body":"BMI Group is a manufacturer of pitched-roof tiles and flat-roof waterproofing, owned by the US-based Standard Industries. It was created after Standard bought the Danish flat-roofing company Icopal in January 2016 (for about EUR 1 billion) and the German-listed pitched-roof group Braas Monier Building Group in April 2017 (for about EUR 1.1 billion), combining the two businesses. BMI operates mainly in Europe, with businesses in South Africa and Asia, and cites a history of more than 180 years through its oldest constituent businesses.\n\n## Brands\n\nBMI sells under many national and product brands, including:\n\n- **Braas** (concrete and clay tiles, Germany and central Europe).\n- **Redland** (tiles, UK and Ireland).\n- **Monier** (tiles in several European and Asian markets).\n- **Bramac** (south-eastern Europe), **Wierer** (Italy), **Cobert** (Spain and Portugal) and **Coverland** (South Africa).\n- **Icopal**, **Vedag**, **Villas**, **Sealoflex** and **Wolfin** (bituminous, synthetic and liquid waterproofing).\n- **Siplast** and **EverGuard** (low-slope membranes).\n\n## Products\n\n- Pitched-roof systems built around concrete and clay roof tiles, with ridge, verge and ventilation components and underlays.\n- Flat-roof systems using bitumen membranes, synthetic membranes and liquid-applied waterproofing.\n- Green roofs and blue roofs (roofs designed to store rainwater temporarily).\n- Waterproofing for civil engineering.\n\n## Scale\n\nAt the end of 2016, just before the Standard acquisition, Braas Monier alone operated in 36 countries with 121 production sites, about 7,900 employees and revenue of about EUR 1.24 billion. BMI's country websites cover roughly 30 markets. Its businesses cover both pitched and flat roof markets. Many national brands date from long before the group's formation.","key_facts":[{"label":"Formed","value":"2017 (Braas Monier + Icopal)"},{"label":"Owner","value":"Standard Industries"},{"label":"Main markets","value":"Europe, South Africa, Asia"},{"label":"Products","value":"Roof tiles, bitumen and synthetic membranes"}],"regions":["Europe","Africa","Southeast Asia","South Asia"],"aliases":["BMI","Braas Monier Icopal"],"related":["standard-industries","braas","redland","icopal","concrete-roof-tile","gaf"],"company":{"founded":"2017","website":"https://www.bmigroup.com","parent":"Standard Industries","known_for":["Concrete and clay roof tiles","Bituminous waterproofing","Synthetic membranes"]},"sources":[{"title":"Braas Monier","url":"https://en.wikipedia.org/wiki/Braas_Monier","publisher":"Wikipedia"},{"title":"Standard Industries","url":"https://en.wikipedia.org/wiki/Standard_Industries","publisher":"Wikipedia"},{"title":"BMI Group","url":"https://www.bmigroup.com/","publisher":"BMI Group"}],"country":null},{"category":"world-roofing","type":"article","company":null,"slug":"bohio","title":"Bohío","summary":"Palm-thatched house of the Taíno of the Greater Antilles, still built in rural Cuba and recorded in Dominican census roof categories.","body":"A bohío is a house of wooden posts with walls and roof of palm materials, originating with the Taíno, the Indigenous people of the Greater Antilles and the Bahamas at the time of European contact. The word, Taíno in origin, remained in use in Spanish for rural thatched houses in Cuba, Hispaniola and Puerto Rico.\n\n## Taíno houses\n\nTaíno villages (*yucayeques*) were largest in Puerto Rico and Hispaniola and smallest in the Bahamas. Their houses stood around a central plaza used for ceremonies and games. Ordinary dwellings are described as large circular buildings, each home to roughly 10-15 families, built of wooden poles, woven straw and palm leaves. The chief (*cacique*) and his family lived in a rectangular house of similar construction with a wooden porch, usually called the *caney*. Inside hung cotton hammocks (*hamaca*).\n\nCuban accounts describe the frame as strong log posts and beams to resist Caribbean winds, walls of reeds and palm leaves tied with vines, and a roof of woven royal palm fronds. Early bohíos had a rounded plan and conical roof; later ones were rectangular under a gabled roof. Sources differ on which shape the names *bohío* and *caney* refer to.\n\n## Colonial and later use\n\nThe rectangular bohío shaped rural colonial building and persisted in parts of Cuba into the late 19th century. The Cuban Ministry of Construction records about 200,000 bohíos and huts before 1959, and 115,000 fewer since. Bohíos remain most common in eastern Cuba, particularly around Baracoa, where they have been revived as cheap to build and suited to a humid, cyclone-prone island.\n\nIn the Dominican Republic, the 2022 census still recorded 1,970 dwellings roofed with *cana* and 1,656 with *yagua*, two traditional palm materials, out of 3.69 million.\n\n## Roof performance\n\nA thick palm roof sheds tropical rain, stays cool and ventilates well, which is why bohíos had no windows yet remained airy. Its drawbacks are flammability, vulnerability to hurricane winds and the need for periodic re-thatching.\n\n## Related forms\n\nThe palm-thatched *palapa* of Mexico and Central America and the Seminole *chickee* of Florida are related palm-roofed structures (see palapa).","key_facts":[{"label":"Origin","value":"Taíno, Greater Antilles"},{"label":"Roof","value":"Woven palm fronds (royal palm in Cuba)"},{"label":"Forms","value":"Round with conical roof; later rectangular with gable"},{"label":"Still built","value":"Eastern Cuba (Baracoa)"}],"regions":["Latin America","North America"],"aliases":["Bohio","Caney","Taíno house"],"related":["palm-thatch","thatch","palapa","roofing-in-cuba","roofing-in-the-dominican-republic","roofing-in-puerto-rico","roofing-in-haiti","roofing-in-the-caribbean"],"sources":[{"title":"Taíno","url":"https://en.wikipedia.org/wiki/Ta%C3%ADno","publisher":"Wikipedia"},{"title":"The Taíno dwelling (la vivienda taína)","url":"https://en.absolutviajes.com/cuba/la-vivienda-taina/","publisher":"Absolut Viajes"},{"title":"Política de la Vivienda en Cuba","url":"https://oncubanews.com/wp-content/uploads/2023/03/Micons_-Politica-de-la-Vivienda-1.pdf","publisher":"Ministerio de la Construcción de Cuba (MICONS), via OnCuba News"},{"title":"¿De qué material se construyen los techos en República Dominicana?","url":"https://inmobiliario.do/de-que-material-se-construyen-los-techos-en-republica-dominicana/","publisher":"El Inmobiliario"}],"country":null},{"slug":"bonnet-roof","title":"Bonnet Roof","category":"roof-forms","type":"term","summary":"A bonnet roof is a double-pitched roof whose lower slope is shallower than the upper slope, the reverse of a mansard or gambrel, often forming porch eaves.","body":"A bonnet roof (sometimes called a kicked-eave roof) has two pitches on each side, like a mansard or gambrel, but reversed: the upper slope is steep and the lower slope, near the eaves, is shallower and projects outward. The lower slope often extends over a porch or veranda, giving the building a wide, sheltering brim that resembles a bonnet.\n\n## Where it is found\n\nBonnet roofs appear on traditional barns in the western United States, for example in Grand Teton National Park in Wyoming, where the shallow lower slope shelters the walls and stored equipment. Related \"kicked\" or flared eaves, in which the bottom of the roof flattens out over the wall, occur in many traditions worldwide. Terminology varies, and many of these are described simply as flared or bell-cast eaves.\n\n## Construction\n\nThe change of slope is usually created in one of two ways:\n\n- **Sprockets:** short tapered timbers fixed to the lower ends of the rafters to lift and flatten the eaves (the British term sprocketed eaves).\n- **Separate rafters:** a lower set of rafters at a shallower pitch, often running from the wall to porch posts.\n\n## Advantages and drawbacks\n\n- Sheds water well clear of the walls and provides shade and shelter.\n- The shallower lower slope reduces the speed of water at the eaves, but it must still meet the minimum pitch of the chosen covering; very shallow kicks may need extra underlayment or a covering rated for low slopes.\n- The break in slope needs careful flashing, and snow can accumulate at the transition.","key_facts":[{"label":"Profile","value":"Steep upper slope, shallow lower slope"},{"label":"Reverse of","value":"Mansard / gambrel"},{"label":"Example region","value":"Western US barns (e.g. Grand Teton)"}],"regions":["North America","Global"],"aliases":["kicked-eave roof","bell-cast roof","flared eave roof","sprocketed eaves"],"related":["gambrel-roof","mansard-roof","eaves","rafter"],"company":null,"sources":[{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"},{"title":"Rafter","url":"https://en.wikipedia.org/wiki/Rafter","publisher":"Wikipedia"}],"country":null},{"slug":"border-cave","title":"Border Cave","category":"history","type":"place","summary":"Rock shelter in South Africa's Lebombo Mountains with grass bedding about 200,000 years old, among the earliest evidence of prepared resting places.","body":"Border Cave is a rock shelter high on the western scarp of the Lebombo Mountains in KwaZulu-Natal, South Africa, close to the border with Eswatini. Its deposits span the Middle Stone Age to the Iron Age, and they include the oldest known evidence of deliberately laid grass bedding. For a history of roofing, the site illustrates the earliest stage of shelter: a natural rock overhang used as a roof, furnished with plant material on the floor.\n\n## Setting\n\nThe west-facing shelter lies at about 600 m (2,000 ft) above sea level, roughly 100 m (330 ft) below the crest of the range and about 12 km (7.5 mi) north of Ingwavuma. Its oldest deposits are about 250,000 years old by luminescence dating, with ESR and radiocarbon results of 227,000 ± 11,000 years; the youngest layers date from about 41,000 to 24,000 years ago.\n\n## Grass bedding\n\nA 2020 study in *Science* led by Lyn Wadley described grass beds in layers dated between about 227,000 and 179,000 years ago. The beds are made mostly of grasses of the subfamily Panicoideae, with occasional sedges and leaves of broad-leaved plants, and were laid near the back of the shelter. In all, 48 bedding layers were identified. Charcoal in the bedding and alternating bands of brown sand and white ash record repeated burning; burn marks occur mostly at the edges of the beds. Regular burning appears in the plant-microfossil record by about 170,000 years ago. Rhizomes of *Hypoxis* found in hearths suggest that plant foods were cooked.\n\n## Significance\n\nPlant shelters and roofs rarely survive, so evidence for early building is indirect. Border Cave shows that by about 200,000 years ago people in southern Africa were returning repeatedly to the same shelter, managing fire and preparing the floor with grass, the same material that later formed the thatched roofs of the region.","key_facts":[{"label":"Location","value":"Lebombo Mountains, KwaZulu-Natal, South Africa"},{"label":"Type","value":"Rock shelter"},{"label":"Grass bedding","value":"C. 227,000-179,000 years ago"},{"label":"Bedding layers","value":"48"},{"label":"Key study","value":"Wadley et al., Science, 2020"}],"regions":["Africa"],"aliases":["Border Cave rock shelter"],"related":["prehistoric-shelters-and-early-thatch","roofing-in-south-africa","roofing-in-eswatini","thatch"],"company":null,"sources":[{"title":"Border Cave","url":"https://en.wikipedia.org/wiki/Border_Cave","publisher":"Wikipedia"},{"title":"Fire and grass-bedding construction 200 thousand years ago at Border Cave, South Africa (Science 369:863-866, 2020)","url":"https://doi.org/10.1126/science.abc7239","publisher":"Science / AAAS"}],"country":null},{"slug":"braas","title":"Braas","category":"manufacturers","type":"company","summary":"Braas is a German concrete and clay roof tile brand founded by Rudolf Braas, part of BMI Group, known for the Frankfurter Pfanne tile.","body":"Braas is a German roofing brand, best known for concrete roof tiles, now part of BMI Group, the European roofing arm of Standard Industries. The business was founded by Rudolf Braas. In the early 1950s the British tile maker Redland took a stake in Braas, later becoming the majority owner, and the two companies' histories have been intertwined since.\n\n## The Frankfurter Pfanne\n\nIn 1954 Braas introduced the Frankfurter Pfanne, an single-lap concrete roof tile that became the most widely laid concrete tile in Germany. Concrete tiles of this type are made from sand, cement and pigment, extruded and cut to shape, and laid over battens with locked side and head joints, allowing relatively shallow pitches compared with traditional plain tiles.\n\n## Corporate history\n\n- **Early 1950s**: Redland acquires a stake in Braas; a 1954 minority holding later becomes a majority.\n- **1996**: Redland and Braas combine their roof tile operations as Redland Braas Building Group.\n- **1997**: The French cement group Lafarge takes over Redland and forms Lafarge Roofing.\n- **2007-2008**: PAI Partners acquires the majority of Lafarge Roofing, which is renamed Monier.\n- **2010**: Lenders including Apollo Global Management and TowerBrook Capital Partners take control through a debt-for-equity restructuring.\n- **2013**: The group is renamed Braas Monier Building Group; it lists on the Frankfurt Stock Exchange in June 2014, with headquarters in Luxembourg.\n- **3 April 2017**: Standard Industries acquires Braas Monier and combines it with Icopal to form BMI Group.\n\n## Markets\n\nWithin BMI, the Braas name is used in Germany, Poland, Switzerland, Turkey and other markets, for concrete and clay tiles, roof accessories and pitched-roof systems.","key_facts":[{"label":"Founder","value":"Rudolf Braas"},{"label":"Country","value":"Germany"},{"label":"Known product","value":"Frankfurter Pfanne concrete tile (1954)"},{"label":"Parent","value":"BMI Group / Standard Industries"}],"regions":["Europe"],"aliases":["Braas Monier","Braas Monier Building Group"],"related":["bmi-group","redland","concrete-roof-tile","standard-industries"],"company":{"headquarters":"Germany","website":"https://www.bmigroup.com/de/","parent":"BMI Group","known_for":["Frankfurter Pfanne concrete tile","Concrete and clay roof tiles"]},"sources":[{"title":"Braas Monier","url":"https://en.wikipedia.org/wiki/Braas_Monier","publisher":"Wikipedia"},{"title":"Redland plc","url":"https://en.wikipedia.org/wiki/Redland_plc","publisher":"Wikipedia"},{"title":"BMI Group","url":"https://www.bmigroup.com/","publisher":"BMI Group"}],"country":null},{"slug":"branz","title":"BRANZ (Building Research Association of New Zealand)","summary":"BRANZ is New Zealand's independent building research organisation, established in 1970 and funded by a levy on building consents.","body":"BRANZ, the Building Research Association of New Zealand, is an independent research, testing and information organisation for the building industry in New Zealand. It was established in 1970; its predecessor, the Building Research Bureau, was an industry-funded research library from the 1950s. BRANZ is based at Judgeford in Porirua, near Wellington, where it has research and testing facilities. Its website is branz.co.nz.\n\n## Funding\n\nBRANZ is funded mainly through the Building Research Levy, created by legislation in the late 1960s. The levy is charged at 0.1% on building consents for work valued over NZ$20,000, which BRANZ describes as $1 for every $1,000 above that threshold. BRANZ has publicly responded to a government Cabinet proposal to remove the Building Research Levy Act.\n\n## Activities\n\n- **Research** on affordability, resilience, sustainability and quality of buildings, including weathertightness, durability, fire and energy performance.\n- **Testing** of building products and systems.\n- **Appraisals** of building products, which assess them against the New Zealand Building Code.\n- **Publications** for builders and designers, including the bimonthly magazine *Build* and technical guides.\n\n## Roofing relevance\n\nBRANZ research and guidance is widely used for roofing in New Zealand, especially on:\n\n- weathertightness, following the country's \"leaky homes\" problems of the 1990s and 2000s;\n- corrosion of metal roofing in coastal and geothermal environments;\n- wind loads, fixings and roof bracing;\n- roof underlays, ventilation and condensation in roof spaces;\n- durability of membranes and other low-slope roof systems.\n\n## Related bodies\n\nIn New Zealand, BRANZ works alongside the Roofing Association of New Zealand (RANZ), the New Zealand Metal Roofing Manufacturers (NZMRM) and government regulators. Comparable building research bodies elsewhere include national laboratories in the United States, the Fraunhofer Institute for Building Physics in Germany and the National Research Council Canada.","key_facts":[{"label":"Established","value":"1970"},{"label":"Location","value":"Judgeford, Porirua, New Zealand"},{"label":"Funding","value":"Building Research Levy (0.1% on consents over NZ$20,000)"},{"label":"Magazine","value":"Build (bimonthly)"}],"regions":["Oceania"],"aliases":["BRANZ","Building Research Association of New Zealand"],"related":["roofing-association-of-new-zealand","new-zealand-metal-roofing-manufacturers","oak-ridge-national-laboratory-building-envelope-research"],"company":{"founded":"1970","headquarters":"Judgeford, Porirua, New Zealand","website":"https://www.branz.co.nz","known_for":["Building research and appraisals","Build magazine"]},"sources":[{"title":"BRANZ","url":"https://en.wikipedia.org/wiki/BRANZ","publisher":"Wikipedia"},{"title":"About BRANZ","url":"https://www.branz.co.nz/about/","publisher":"BRANZ"},{"title":"BRANZ home page","url":"https://www.branz.co.nz/","publisher":"BRANZ"}],"category":"organizations","type":"organization","country":null},{"slug":"brazilian-slate","title":"Brazilian Slate","type":"term","summary":"Slate from Minas Gerais, Brazil; widely used for flooring and cladding but generally considered less suited to roofing in freezing climates.","body":"Brazilian slate is stone quarried mainly in the state of Minas Gerais, which accounts for about 95% of Brazil's slate extraction, particularly around Papagaios. Brazil is the world's second-largest slate producer after Spain.\n\n## Geology\n\nBrazilian slate differs from most European and North American roofing slates. It is generally described as a sedimentary-derived rock that splits along its original bedding planes rather than along a metamorphic cleavage. This affects how thinly and evenly it can be split and how it behaves when wet and frozen.\n\n## Performance as roofing\n\nA Spanish-led comparative study found that Brazilian slate had higher water absorption than Galician roofing slate and lost significant strength under freeze-thaw cycling, making it less suitable for roofing in cold climates. Some Brazilian products sold in the United Kingdom have been reported as not entitled to the CE mark for roofing use. European producers have also questioned the suitability of some imported slates for roofing.\n\n## Uses\n\nFreeze-thaw weakness matters most in cold, wet climates; in frost-free regions the same limitation is less significant, and slate from Brazil is also used for non-roofing purposes such as paving and cladding.\n\n## Specification advice\n\nAnyone considering imported slate for a roof in a frost-prone region should ask for test results to the relevant national standard, such as EN 12326 in Europe or ASTM C406 in North America, rather than relying on origin or appearance.\n\n## Other imported slates\n\nChina also has vast slate deposits, and its exports of finished and unfinished slate have grown in recent years. As with Brazilian material, the suitability of any imported slate for roofing depends on its test results rather than its country of origin.\n","key_facts":[{"label":"Main region","value":"Minas Gerais (about 95% of Brazilian output)"},{"label":"World ranking","value":"Second-largest producer after Spain"},{"label":"Roofing caution","value":"Higher absorption; strength loss under freeze-thaw (study)"}],"regions":["Latin America"],"aliases":["Minas Gerais slate"],"related":["natural-slate","spanish-slate","en-12326"],"sources":[{"title":"Slate industry","url":"https://en.wikipedia.org/wiki/Slate_industry","publisher":"Wikipedia"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"},{"title":"Roofing: Quality shows","url":"https://www.stonespecialist.com/news/roofing-quality-shows","publisher":"Natural Stone Specialist"}],"category":"materials","company":null,"country":null},{"slug":"breeam","title":"BREEAM","category":"standards-codes","type":"standard","summary":"BREEAM is a sustainability assessment and certification method for buildings, first published by the UK's Building Research Establishment in 1990.","body":"BREEAM (Building Research Establishment Environmental Assessment Method) is a sustainability assessment and certification method for buildings and infrastructure. It was first published in 1990 by the Building Research Establishment (BRE) in the UK, after development began in 1988, making it one of the oldest green building rating systems. It is used in more than 100 countries, with national scheme operators in countries including Germany, Austria, Switzerland, the Netherlands, Norway, Spain and Sweden. Around 600,000 buildings have been certified and some 2.3 million registered.\n\n## How it works\n\nAssessments are carried out by licensed assessors. Credits are awarded across categories such as management, energy, health and wellbeing, water, materials, waste, pollution, transport, land use and ecology, and resilience, and are weighted to give an overall score. Ratings are:\n\n- Pass\n- Good\n- Very Good\n- Excellent\n- Outstanding\n\nSchemes exist for new construction, in-use buildings, refurbishment and fit-out, communities and infrastructure.\n\n## Relevance to roofing\n\nRoofs affect several BREEAM categories:\n\n- **Energy** – roof insulation and airtightness contribute to operational energy performance, and roofs host photovoltaic and solar thermal systems.\n- **Materials** – roofing products can earn credits through life-cycle assessment data, such as Environmental Product Declarations, and responsible sourcing certification.\n- **Land use and ecology** – green and biodiverse roofs can contribute to ecological value.\n- **Pollution and water** – green and blue roofs can reduce surface water run-off.\n- **Resilience** – durability and protection of the building fabric.\n\n## Influence\n\nBREEAM influenced later rating systems, and several European countries operate adapted national versions through national scheme operators. In the UK, some planning authorities set BREEAM targets for non-domestic buildings. Comparable systems elsewhere include [LEED](/leed-heat-island-reduction) in North America.","key_facts":[{"label":"Developer","value":"Building Research Establishment (BRE), UK"},{"label":"First published","value":"1990"},{"label":"Ratings","value":"Pass, Good, Very Good, Excellent, Outstanding"},{"label":"Reach","value":"More than 100 countries"},{"label":"Certified buildings","value":"About 600,000"}],"regions":["Europe","Global"],"aliases":["Building Research Establishment Environmental Assessment Method"],"related":["leed-heat-island-reduction","green-roof","environmental-product-declaration","uk-building-regulations"],"sources":[{"title":"BREEAM","url":"https://breeam.com/","publisher":"BRE"},{"title":"BREEAM","url":"https://en.wikipedia.org/wiki/BREEAM","publisher":"Wikipedia"}],"company":null,"country":null},{"slug":"bronze-age-roundhouse","title":"Bronze Age and Iron Age Roundhouse","category":"history","type":"article","summary":"The circular house with a conical thatched roof that was standard in Britain and Ireland from the Bronze Age to the Iron Age.","body":"The roundhouse was the standard dwelling of Britain and Ireland from the Bronze Age through the Iron Age, and in some areas into the post-Roman period. Its defining feature is a conical roof over a circular wall of timber posts with wattle-and-daub panels, or of stone. Diameters ranged from under 5 m (16 ft) to over 15 m (49 ft). Circular houses with conical roofs also appear elsewhere in Europe, from the Villanovan huts of Italy to the palloza of northwest Spain, which has a conical rye-straw roof and no chimney.\n\n## Evidence\n\nFor most of the 20th century roundhouses were known almost entirely from rings of post holes, with only a few timbers preserved in bogs. Reconstruction depended on engineering judgement and experiment. The discovery at Must Farm in Cambridgeshire of Bronze Age roundhouses that had collapsed and charred with posts, walls and roofs in place confirmed much of what had been supposed.\n\n## Experimental archaeology\n\nAt Butser Ancient Farm in Hampshire, England, Peter Reynolds and his successors have built and monitored full-size roundhouses since the 1970s. Its Pimperne house, based on an excavated ground plan, was begun in 1976 and dismantled in 1990, and is one of the most fully recorded experiments:\n\n- **Plan:** an outer ring of posts 12.8 m (42 ft) across and an inner ring about 9.75 m (32 ft) across.\n- **Walls:** outer wall 1.52 m (5 ft) high; inner ring 3.04 m (10 ft).\n- **Roof frame:** six principal rafters about 11.2 m (37 ft) long, arranged as a double tripod, each weighing 740-985 kg (1,630-2,170 lb); ring beams on the inner posts and about one-third of the way down from the apex; hazel purlins.\n- **Pitch:** 45 degrees, which kept the house watertight.\n- **Thatch:** about 7 tonnes of modern wheat straw. Laid at about one-third of the depth professional thatchers recommend, it lasted about ten years.\n\nExperiments found that a pitch of around 45 degrees gave the strongest and most efficient design. The loads on the posts were essentially vertical, so the structure was stable once the post bases were packed.\n\n## Smoke and fire\n\nReynolds argued that roundhouses probably had no smoke hole at the apex, because the updraught would ignite the thatch. Instead smoke filled the roof space and seeped slowly out through the thatch. Modern reconstructions rest on such assumptions and may differ from the originals.\n\n## Reconstructions\n\nReconstructed roundhouses can be seen at Butser Ancient Farm, Castell Henllys in Pembrokeshire, Bostadh on Great Bernera (built 1999), Beeston Castle in Cheshire (a 2019 reconstruction of a house of about 2000 BCE), the Stonehenge Visitor Centre (Neolithic houses) and the Scottish Crannog Centre on Loch Tay.\n\n## Regional forms\n\nIn Atlantic Scotland the roundhouse developed into massive stone forms, including brochs and wheelhouses. In Ireland and Scotland roundhouses were also built on crannogs, artificial islands in lakes.","key_facts":[{"label":"Period","value":"Bronze Age to Iron Age (Britain and Ireland)"},{"label":"Diameter","value":"Under 5 m (16 ft) to over 15 m (49 ft)"},{"label":"Tested roof pitch","value":"About 45 degrees"},{"label":"Pimperne house thatch","value":"About 7 tonnes of wheat straw"},{"label":"Key experiment","value":"Butser Ancient Farm, from the 1970s"}],"regions":["Europe"],"aliases":["roundhouse","Iron Age roundhouse","prehistoric roundhouse","Butser roundhouse"],"related":["must-farm","crannog","thatch","english-thatch","prehistory-of-roofing","conical-roof"],"company":null,"sources":[{"title":"Roundhouse (dwelling)","url":"https://en.wikipedia.org/wiki/Roundhouse_(dwelling)","publisher":"Wikipedia"},{"title":"Pimperne House","url":"https://butser.org.uk/pimperne.html","publisher":"Butser Ancient Farm"}],"country":null},{"slug":"bs-5534","title":"BS 5534","summary":"BS 5534 is the British code of practice for slating and tiling pitched roofs and vertical cladding, including wind loading and mechanical fixing rules.","body":"BS 5534, *Slating and tiling for pitched roofs and vertical cladding – Code of practice*, is published by BSI and is the main UK standard for the design and installation of slate and tile roofs. It covers materials, underlays, battens, fixings, weathertightness and resistance to wind. The current version is BS 5534:2014+A2:2018.\n\n## The 2014 revision and later changes\n\nThe 2014 edition, which came fully into effect in 2015, made several significant changes:\n\n- **No mortar-only fixing.** Mortar can no longer be relied on as the only means of securing roof tiles. Ridge and hip tiles, and single-lap tiles, must be mechanically fixed even where mortar is used for bedding.\n- **Perimeter tiles.** Tiles at the edges of the roof (eaves, verges, ridge, hips) are to be fixed twice, because wind suction is highest there.\n- **Higher wind loads.** Revised wind calculation, aligned with Eurocode wind loading, generally means more fixings than older practice.\n- **Underlays.** Underlays must be classified for wind uplift resistance using prescribed tests, with a maximum drape between rafters of 15 mm (0.6 in). Definitions of low-resistance (LR) and air-permeable underlays changed.\n- **Scope.** Re-roofing and repairs were brought within scope, with a note that heritage roofs may need a different approach agreed with planning authorities.\n\nThe 2018 amendment (A2) refers to **BS 8612**, which sets requirements for dry-fixed ridge, hip and verge systems, including their fixing and ventilation.\n\n## How fixing is decided\n\nBS 5534 uses wind loads from [EN 1991-1-4](/en-1991-1-4) and its UK National Annex, combined with uplift resistance data for the tile and fixing (often from [EN 14437](/en-14437) tests), to determine fixing requirements for each part of the roof. Manufacturers publish fixing specifications based on site location, altitude, roof pitch and building height.\n\n## Workmanship\n\nOn-site workmanship is covered by the companion standard BS 8000-6. Warranty providers in the UK new-homes market, such as LABC Warranty, refer to BS 5534 compliance in their technical standards.\n\n## Influence\n\nAlthough written for the UK, BS 5534 is used as a reference in Ireland and in other countries that follow British roofing practice.","key_facts":[{"label":"Publisher","value":"BSI"},{"label":"Current version","value":"BS 5534:2014+A2:2018"},{"label":"Key change","value":"Mortar alone no longer acceptable for fixing"},{"label":"Max underlay drape","value":"15 mm (0.6 in)"},{"label":"Related","value":"BS 8612 dry-fix systems; BS 8000-6 workmanship"}],"regions":["Europe"],"aliases":["BS5534","British Standard 5534","slating and tiling code of practice"],"related":["en-14437","en-1991-1-4","clay-roof-tile","natural-slate","roofing-underlayment","uk-building-regulations"],"sources":[{"title":"What are the fixing requirements of BS 5534?","url":"https://www.marley.co.uk/blog/what-are-the-fixing-requirements-of-bs-5534","publisher":"Marley"},{"title":"Tech update: roof tiling and underlays","url":"https://www.labcwarranty.co.uk/blog/tech-update-roof-tiling-and-underlays/?hsLang=en","publisher":"LABC Warranty"},{"title":"Slating and tiling for pitched roofs and vertical cladding. Code of practice","url":"https://knowledge.bsigroup.com/products/slating-and-tiling-for-pitched-roofs-and-vertical-cladding-code-of-practice?version=standard","publisher":"BSI"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"bs-5534-fixing-specification","title":"BS 5534 Fixing Specification","category":"installation","type":"standard","summary":"BS 5534 is the British code of practice for slating and tiling; its fixing specification sets how every tile, ridge and verge is mechanically secured.","body":"**BS 5534** is the British Standard code of practice for slating and tiling, including shingles. It covers design aspects such as wind loading, fixing, underlays and battens. The **fixing specification** is the set of instructions, derived from the standard, that defines how many and which fixings each part of a particular roof needs. Site workmanship is covered by the companion standard BS 8000-6.\n\n## Key fixing principles\n\nFollowing revisions that took effect in 2015, the standard no longer allows mortar to be relied on as the only means of securing a roof covering. Its requirements include the following:\n\n- single-lap tiles must be mechanically fixed, whether or not mortar is also used;\n- ridge and hip tiles must also be mechanically fixed;\n- tiles at the perimeter of the roof are fixed twice; and\n- higher wind loads are assumed than in earlier editions, which generally means more fixings.\n\n## How a fixing specification is produced\n\nThe standard contains methods to calculate wind uplift on the roof and to compare that load with the tested resistance of tiles, nails and clips. Tile manufacturers typically provide a site-specific fixing specification based on location, building height, roof pitch and exposure, listing the nails, clips and edge fixings for each zone of the roof.\n\n## Amendments\n\n- **2014 edition with 2015 changes.** Introduced the mechanical fixing requirements and aligned the standard with Eurocodes.\n- **Amendment A2, February 2018.** Improved the interpretation of tile clip uplift tests, set a maximum underlay drape of 15 mm, revised underlay definitions and added guidance on temporary weather protection.\n\n## Related standards\n\n**BS 8612:2018** specifies dry-fix ridge, hip and verge systems, written in response to products that gave insufficient mechanical restraint. Underlays must be classified for wind uplift resistance using prescribed test methods.\n\nThe fixing specification concept is specific to UK practice, but similar wind-based fixing tables appear in other national codes, such as Australian and New Zealand standards and North American tile installation manuals.","key_facts":[{"label":"Scope","value":"Code of practice for slating and tiling"},{"label":"Current form","value":"BS 5534:2014+A2:2018"},{"label":"Mortar","value":"Not relied on as sole fixing"},{"label":"Related standards","value":"BS 8000-6, BS 8612"}],"regions":["Europe"],"aliases":["BS5534","British Standard 5534","tile fixing specification"],"related":["clay-and-concrete-tile-installation","dry-fix-ridge-system","tile-clips","tile-battens","underlayment-installation"],"company":null,"sources":[{"title":"What are the fixing requirements of BS 5534?","url":"https://www.marley.co.uk/blog/what-are-the-fixing-requirements-of-bs-5534","publisher":"Marley"},{"title":"What is BS 5534?","url":"https://www.marley.co.uk/Blog/What-is-BS-5534","publisher":"Marley"}],"country":null},{"slug":"buckminster-fuller","title":"Buckminster Fuller","category":"history","type":"person","summary":"American designer and inventor (1895-1983) who popularised the geodesic dome, patented in 1954, and designed the US Pavilion at Expo 67.","body":"**Richard Buckminster Fuller** (12 July 1895 - 1 July 1983) was an American architect, designer, inventor and writer. In roofing and structural history he is best known for popularising the **geodesic dome**, a lightweight spherical structure built from a network of triangles.\n\n## Dymaxion\n\nFuller's early work aimed at efficient, mass-produced shelter. His concept house of around 1929 was marketed under the name **Dymaxion**, a word coined by publicists from \"dynamic\", \"maximum\" and \"tension\". He also designed the Dymaxion car, shown at the 1933-1934 Century of Progress fair.\n\n## The geodesic dome\n\nDuring the summers of **1948 and 1949**, while teaching at **Black Mountain College**, Fuller experimented with dome structures together with students, including the artist Kenneth Snelson, and coined the term \"geodesic\". He received **US patent 2,682,235** for the geodesic dome on **29 June 1954**.\n\nA geodesic dome divides a sphere into triangles. Triangles are inherently rigid, so loads are shared throughout the frame, and the dome encloses a large volume with very little material and no internal supports.\n\n## Who invented it?\n\nFuller is often credited with inventing the geodesic dome, but the first such dome was designed by **Walther Bauersfeld**, chief engineer of Carl Zeiss Jena, for a planetarium in the 1920s. Bauersfeld received a German patent in 1925, and the Zeiss planetarium dome in Jena opened in 1926. Fuller independently developed, named, patented and popularised the form.\n\n## Major domes\n\n- The oldest surviving Fuller-built dome is at Woods Hole, Massachusetts, built by students in three weeks in 1953.\n- With **Shoji Sadao**, Fuller designed the dome of the **United States Pavilion at Expo 67** in Montreal, now the **Montreal Biosphère**.\n\nWithin a few years, thousands of geodesic domes had been built around the world.\n\n## Legacy\n\nFuller's emphasis on doing more with less material anticipated later interest in lightweight and resource-efficient structures.","key_facts":[{"label":"Born","value":"12 July 1895"},{"label":"Died","value":"1 July 1983"},{"label":"Geodesic dome patent","value":"US 2,682,235, 29 June 1954"},{"label":"Expo 67 dome","value":"US Pavilion, Montreal (with Shoji Sadao)"}],"regions":["North America"],"aliases":["R. Buckminster Fuller","Bucky Fuller"],"related":["geodesic-dome-history","frei-otto","dome"],"company":null,"sources":[{"title":"Buckminster Fuller","url":"https://en.wikipedia.org/wiki/Buckminster_Fuller","publisher":"Wikipedia"},{"title":"Geodesic dome","url":"https://en.wikipedia.org/wiki/Geodesic_dome","publisher":"Wikipedia"}],"country":null},{"slug":"budj-bim-stone-houses","title":"Budj Bim Stone Houses","category":"history","type":"place","summary":"Remains of Gunditjmara domed houses with basalt walls in the Budj Bim World Heritage landscape of south-west Victoria, Australia.","body":"The Budj Bim Cultural Landscape in south-west Victoria, Australia, is the country of the Gunditjmara people, who built an eel aquaculture system in the lava flows of the Budj Bim volcano and lived in settled communities of stone-walled houses. The landscape, including the Lake Condah and Tyrendarra fish traps, was added to the UNESCO World Heritage List in July 2019.\n\n## The houses\n\nEuropean observers in 1840 recorded beehive-shaped, domed dwellings with walls of basalt, often grouped in communities of 20 to 30; about 70 houses were recorded at one site, facing north-east. Remnants of at least 146 stone houses are known at Budj Bim. The circular stone walls stood more than 1 m (3 ft) high.\n\nSources differ on how the houses were roofed. Australian Geographic, drawing on Gunditjmara guides, describes reed roofs, while another account describes domes clad with earth or sod over the stone walls. Both are consistent with a light frame covered with locally available material, and only the stone bases survive.\n\n## Setting\n\nThe Gunditjmara cut channels into the basalt lava flows to divert water and trap eels, reportedly by heating the rock with fire and breaking it. Lake Condah has about 13 trap systems, and archaeologists date the traps to at least 6,500 years ago; UNESCO describes the system as the economic and social base of Gunditjmara society for six millennia. Women wove fishnets and eel traps from reeds. The reliable eel harvest is linked to the settled way of life that the stone houses reflect.\n\n## Fire and rediscovery\n\nThe Black Summer bushfires of December 2019 burned about 7,000 ha (17,000 acres) of the landscape and exposed channels previously hidden by undergrowth.\n\n## Significance for roofing history\n\nThe Budj Bim houses are among the clearest evidence that Aboriginal Australians built permanent, insulated dwellings, not only temporary shelters. They belong to a wider pattern of domed Aboriginal houses documented across the continent (see [gunyah](/gunyah)), and to the worldwide story of early roofs over stone footings (see [prehistoric shelters and early thatch](/prehistoric-shelters-and-early-thatch)).","key_facts":[{"label":"Location","value":"Budj Bim, south-west Victoria, Australia"},{"label":"People","value":"Gunditjmara"},{"label":"Walls","value":"Basalt, circular, over 1 m high"},{"label":"Roof (reported)","value":"Reeds, or earth/sod domes"},{"label":"Known remains","value":"At least 146 stone houses"},{"label":"World Heritage","value":"Inscribed July 2019"}],"regions":["Oceania"],"aliases":["Gunditjmara stone houses","Lake Condah stone huts","Budj Bim stone huts"],"related":["roofing-in-australia","gunyah","prehistoric-shelters-and-early-thatch","sod-roof","thatch"],"company":null,"sources":[{"title":"Revealed by fire","url":"https://inside.australiangeographic.com.au/articles/revealed-by-fire","publisher":"Australian Geographic"},{"title":"Aboriginal houses","url":"https://www.creativespirits.info/aboriginalculture/land/aboriginal-houses","publisher":"Creative Spirits"},{"title":"Vic site added to World Heritage list","url":"https://www.canberratimes.com.au/story/6260524/vic-site-added-to-world-heritage-list/?cs=14231","publisher":"The Canberra Times"}],"country":null},{"slug":"building-integrated-photovoltaics","title":"Building-Integrated Photovoltaics","type":"article","category":"climate-sustainability","summary":"Photovoltaic products that replace conventional building materials in the roof or facade, generating electricity while forming part of the building envelope.","body":"Building-integrated photovoltaics (BIPV) are photovoltaic materials that replace conventional building materials in part of the building envelope, such as the roof covering, skylights or facades. Unlike ordinary solar panels mounted on racks above a finished roof, BIPV products act as the roof or wall itself, so part of their cost is offset by the materials and labour they replace.\n\n## Roof applications\n\nRoofing holds a larger share of the BIPV market than facades and is generally more productive because of its orientation to the sun. Main roof products are:\n\n- **Solar shingles**: units shaped and laid like conventional shingles.\n- **Solar roof tiles**: tile-shaped modules, including ceramic tiles with integrated cells; a Dutch company patented a ceramic solar roof tile in 2013.\n- **Flexible thin-film laminates**: adhered to low-slope membranes; copper indium gallium selenide (CIGS) cells have been fused into TPO single-ply membranes.\n\nRoof-integrated PV can also protect the membranes beneath it from UV and water and help keep the dew point above the membrane, reducing condensation.\n\n## History\n\n- **1970s**: aluminium-framed PV modules were attached to buildings, mostly in remote areas without grid power.\n- **1980s**: roof add-on systems were demonstrated on grid-connected buildings.\n- **1990s**: purpose-designed BIPV construction products became commercially available.\n- **2005 onward**: solar shingles entered the market, followed by products from large roofing and energy companies.\n\n## BIPV versus BAPV\n\nBuilding-applied photovoltaics (BAPV) are PV systems added to a building after construction, such as rack-mounted panels. Many installations described as building-integrated are in fact BAPV.\n\n## Challenges\n\n- **Heat**: integrated modules lose heat less effectively than ventilated rack-mounted panels, so they run hotter, which reduces output and can degrade cells.\n- **Cost and complexity**: higher upfront cost, more complex design and construction, and the need to meet both roofing and electrical codes.\n- **Awareness**: limited familiarity among designers, installers and the public.\n\n## Incentives\n\nSome governments have offered extra support for integrated PV. France, for example, paid an extra €0.25/kWh for roof-, wall- or window-integrated systems, and China's Golden Sun programme subsidised up to 50% of investment in eligible projects, including BIPV.\n","key_facts":[{"label":"Definition","value":"PV that replaces part of the building envelope"},{"label":"Main roof forms","value":"Solar shingles, solar tiles, thin-film laminates"},{"label":"Commercial BIPV products","value":"From the 1990s"},{"label":"Key drawback","value":"Higher operating temperature than rack-mounted PV"}],"regions":["Global"],"aliases":["BIPV","solar shingles","solar tiles","solar roof tiles","integrated PV","integrated solar roof","in-roof solar","Building-Integrated Photovoltaics (BIPV)"],"related":["rooftop-solar-pv","solar-roof-mounting","class-a-fire-rating","shingle-wind-rating","solar-shingle","green-roof","cool-roof"],"sources":[{"title":"Building-integrated photovoltaics","url":"https://en.wikipedia.org/wiki/Building-integrated_photovoltaics","publisher":"Wikipedia"},{"title":"Photovoltaic mounting system","url":"https://en.wikipedia.org/wiki/Photovoltaic_mounting_system","publisher":"Wikipedia"},{"title":"Solar shingle","url":"https://en.wikipedia.org/wiki/Solar_shingle","publisher":"Wikipedia"}],"company":null,"country":null},{"slug":"buildwise","title":"Buildwise","category":"organizations","type":"organization","summary":"Buildwise, formerly the Belgian Building Research Institute, is the research and technical-advice centre of the Belgian construction industry.","body":"**Buildwise** is Belgium's innovation and research centre for construction. Formerly known in English as the Belgian Building Research Institute (BBRI), it was founded in 1959 as a private research institute at the initiative of the National Federation of Belgian Building Contractors, under the so-called \"De Groote\" decree-law of 1947 that provided for collective research centres serving whole industries.\n\n## Role\n\nBuildwise has three statutory tasks:\n\n- scientific and technical research for the benefit of its members;\n- technical information, guidance and advice to members;\n- contract research and services for industry and public authorities.\n\nIts statutory members are Belgium's construction companies, more than 120,000 firms, most of them small and medium-sized businesses. It employs more than 300 staff.\n\n## Relevance to roofing\n\nBelgium has no single national building code; building rules are set largely by the regions, and European EN standards govern products. Buildwise's statutory role of providing technical information and advice to construction companies therefore spans all building trades, roofing included. Buildwise publishes a magazine, annual reports and other publications, most of them also available in English.\n\n## Comparable bodies\n\nNeighbouring countries have their own technical reference bodies for building trades. In France, the Centre Scientifique et Technique du Bâtiment (CSTB) holds the secretariat for the NF DTU technical rules and issues technical assessments for new products, while in Germany the roofers' federation ZVDH publishes the technical rules of the roofing trade. Buildwise differs from both in being a collective research centre whose statutory members are the contractors themselves.\n\n## Sources and gaps\n\nFounding details of its roofing committees and the titles of its current roofing guidance documents: published information is limited.","key_facts":[{"label":"Former name","value":"Belgian Building Research Institute (BBRI)"},{"label":"Founded","value":"1959"},{"label":"Legal basis","value":"1947 'De Groote' decree-law"},{"label":"Members","value":"Over 120,000 Belgian construction companies"},{"label":"Staff","value":"Over 300"}],"regions":["Europe"],"aliases":["BBRI","Belgian Building Research Institute","CSTC"],"related":["roofing-in-belgium","zvdh","dtu-40-series"],"company":{"founded":"1959","headquarters":"Belgium","website":"https://www.buildwise.be","known_for":["Construction research","Technical guidance for Belgian contractors"]},"sources":[{"title":"Buildwise is there for you","url":"https://www.buildwise.be/en/","publisher":"Buildwise"},{"title":"CSTC Centre Scientifique et Technique de la Construction > Buildwise","url":"https://www.polemecatech.be/en/members/cstc-centre-scientifique-et-technique-de-la-construction-buildwise","publisher":"Pôle MecaTech"}],"country":null},{"slug":"built-up-roofing","title":"Built-Up Roofing (BUR)","category":"low-slope-systems","type":"article","summary":"A low-slope roof membrane made of several plies of reinforcing felt laminated with hot or cold bitumen, usually finished with gravel or a cap sheet.","body":"Built-up roofing, abbreviated BUR and known colloquially as \"tar and gravel\", is one of the oldest membrane roofing methods. It builds a waterproof layer on site by alternating layers of bitumen (asphalt or coal-tar pitch) with reinforcing felts, called plies. The bitumen provides the waterproofing; the felts stabilise and reinforce it. A typical system uses three to five plies.\n\n## History\n\nBUR has been used in the United States since the mid-to-late nineteenth century and dominated North American commercial low-slope roofing for roughly a century until about 1980. Its share then fell as modified bitumen and single-ply membranes arrived and oil prices rose. NRCA market surveys around 2000 still showed BUR at 20% or more of US low-slope sales, and an estimated 50 billion square feet was in service; later estimates put its share of new US installations far lower. Many old BUR roofs remain in place, often covered by newer systems.\n\n## Components\n\n- **Deck:** steel, concrete, poured gypsum or wood.\n- **Vapour retarder and insulation** where required.\n- **Base sheet:** a heavier felt, often mechanically fastened, that anchors the membrane.\n- **Plies:** organic, glass-fibre or polyester felts set in bitumen. Asphalt-impregnated glass-fibre felts are the most common today.\n- **Flashings:** frequently made from modified bitumen.\n- **Surfacing:** a flood coat of bitumen with embedded gravel or slag, a mineral-surfaced cap sheet, or a coating.\n\nThe membrane alone is roughly 13 mm (1/2 in) thick and weighs about 12 kg/m2 (2.5 lb/sq ft); gravel adds about 15 to 20 kg/m2 (3 to 4 lb/sq ft).\n\n## Hot and cold application\n\nIn hot-applied BUR, asphalt is heated in a kettle or tanker and applied by mop or mechanical spreader, typically about 25 lb per 100 sq ft per ply (about 1.2 kg/m2). Correct temperature is critical; the industry uses the equiviscous temperature (EVT) to target the right viscosity. Cold-process BUR uses solvent- or water-based adhesives applied by spray, brush or squeegee, avoiding kettles but needing longer cure times.\n\n## Performance and problems\n\nMultiple plies give redundancy, and well-built systems have served for decades. Typical problems are blisters, splits (often from unanchored insulation), ridging over insulation joints, fishmouths, slippage, alligatoring of exposed bitumen and gravel scour at corners. Most leaks start at flashings and penetrations rather than in the field of the roof.\n\n## Health considerations\n\nUS NIOSH has identified roofing asphalt fumes as a potential occupational carcinogen, and IARC classified occupational exposure to oxidised bitumen during roofing as probably carcinogenic in 2011. Low-fuming asphalts and kettle controls were developed in response.","key_facts":[{"label":"Typical plies","value":"3 to 5"},{"label":"Membrane weight","value":"About 12 kg/m2 (2.5 lb/sq ft) without gravel"},{"label":"Gravel surfacing","value":"About 15-20 kg/m2 (3-4 lb/sq ft)"},{"label":"In US use since","value":"1850s-1880s (sources vary)"},{"label":"Main bitumens","value":"Asphalt (ASTM D312) and coal-tar pitch"}],"regions":["North America","Global"],"aliases":["BUR","tar and gravel roof","hot-mopped roof","built-up felt roof"],"related":["roofing-asphalt","coal-tar-pitch-roofing","gravel-surfaced-roof","modified-bitumen-roofing","cold-applied-roofing"],"company":null,"sources":[{"title":"Built-Up Roofing (BUR): What It Is, Types, Issues & More","url":"https://roofonline.com/built-up-roofing-introduction/","publisher":"RoofOnline"},{"title":"Low-slope roofing systems: built-up roofs and modified bitumen","url":"https://buildingenclosureonline.com/articles/82366-low-slope-roofing-systems-built-up-roofs-and-modified-bitumen","publisher":"Building Enclosure"},{"title":"The evolution of built-up roofing asphalt","url":"https://www.asphaltmagazine.com/buraevolution/","publisher":"Asphalt Magazine"},{"title":"Rules for long-lasting BUR systems (H. H. Pierce, Interface, Oct 2006)","url":"https://iibec.org/wp-content/uploads/2006-10-Pierce.pdf","publisher":"IIBEC"},{"title":"BUR performance (Janicki and Trumbore, Interface, Aug 2003)","url":"https://iibec.org/wp-content/uploads/2003-08-Janicki-Trumbore.pdf","publisher":"IIBEC"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"}],"country":null},{"slug":"burza-pash-roof","title":"Burza Pash Roof (Kashmiri Birch-Bark Roof)","category":"world-roofing","type":"term","summary":"Burza pash was the traditional Kashmiri roof of timber boards, birch bark and a layer of earth, which in spring flowered with tulips and irises.","body":"**Burza pash** (also written *burz-push* or *burze pash*) is the traditional earth-covered roof of the Kashmir Valley. *Burza* is the Kashmiri name for birch bark, taken from the white birch (*burza kul*), which today grows mainly between about 3,100 and 3,600 m (10,200-11,800 ft) in places such as Gulmarg and Sonamarg. For centuries many roofs in Srinagar were built with birch bark and earth, and in spring they turned into strips of flowering meadow. Shingles and then corrugated metal sheets have largely replaced it.\n\n## Construction\n\nThe roof was a close relative of the Scandinavian sod roof. Builders laid wooden planks over a frame of deodar (Himalayan cedar) poles, covered the boards with overlapping sheets of birch bark, and spread earth over the bark. The earth layer was about 3-4 inches (75-100 mm) thick. The thick layers of bark formed the waterproof surface, and the soil on top held them in place and insulated the house.\n\nHeavy Kashmiri snowfalls were a real danger to a soil roof. Householders reached the roof through an opening called *woabb* to clear it, and paid snow-clearers, *sheen mohniev*, went round after each fall.\n\n## Flowering roofs\n\nSeeds blown or dropped by birds, and bulbs planted deliberately, grew in the soil. Travellers and officials who wrote about the valley, among them François Bernier in the 17th century and Walter Lawrence in *The Valley of Kashmir*, described roofs covered with flowers. Local accounts list red tulips (*gul-e-lala*), irises in purple, white and yellow, crown imperial lilies and narcissus (*yemberzal*); around Baramulla flax (*alish*) was common. Some owners grew herbs or vegetables on the roof.\n\nBirch-and-earth roofs were used on the houses of middle-class and wealthier families, and on shrines and mosques, including the Jamia Masjid, the old Hazratbal shrine and the Khanqah-e-Maula in Srinagar. Poorer households used simpler thatched roofs of grass and reeds.\n\n## Decline\n\nMost houses and shrines built in Srinagar in the 18th and 19th centuries had burza pash roofs, and many homes kept them until about the late 19th century. Some owners then changed to wooden shingles, and shingles in turn gave way to cheap imported corrugated galvanised iron (CGI) sheets, a change that began in the British period and accelerated with modernisation. Critics point out that metal roofs make houses hotter in summer, whereas the earth roofs insulated well. The best-known surviving burza pash roof is on the Madin Saheb shrine at Hawal in Srinagar, perhaps the only public building in Kashmir whose birch-bark roof still flowers; it is in need of repair.","key_facts":[{"label":"Region","value":"Kashmir Valley, especially Srinagar"},{"label":"Layers","value":"Deodar poles, planks, birch bark, 3-4 in (75-100 mm) of earth"},{"label":"Waterproofing layer","value":"Birch bark (burza)"},{"label":"Replaced by","value":"Wooden shingles, then corrugated iron (CGI) sheets"},{"label":"Surviving example","value":"Madin Saheb shrine, Srinagar"}],"regions":["South Asia"],"aliases":["burz-push","burze pash","burzaposh","Kashmiri sod roof","birch-bark roof"],"related":["sod-roof","green-roof","scandinavian-sod-roofs","corrugated-iron","roofing-in-india","roofing-in-pakistan","history-of-green-roofs"],"company":null,"sources":[{"title":"Burza Pash: The rooftops that exploded with colours","url":"https://www.greaterkashmir.com/todays-paper/burza-pash-the-rooftops-that-exploded-with-colours","publisher":"Greater Kashmir"},{"title":"Kashmir's Forgotten Burza","url":"https://kashmirlife.net/kashmirs-forgotten-burza-vol-17-issue-39-417633/","publisher":"Kashmir Life"}],"country":null},{"slug":"bushfire-attack-level","title":"Bushfire Attack Level (BAL)","type":"standard","summary":"Australia's rating of a building site's bushfire exposure, from BAL-LOW to BAL-FZ, which sets construction requirements including roofing.","body":"A Bushfire Attack Level (BAL) is a rating used in Australia to measure how severely a building site could be exposed to ember attack, radiant heat and direct flame during a bushfire. The BAL determines which construction requirements of the Australian Standard AS 3959, Construction of buildings in bushfire-prone areas, apply to the building, including its roof.\n\n## The levels\n\nRatings run from BAL-LOW to BAL-FZ (Flame Zone):\n\n- **BAL-LOW:** very low risk; no specific bushfire construction requirements.\n- **BAL-12.5, BAL-19, BAL-29 and BAL-40:** increasing exposure; the number refers to the expected radiant heat flux in kilowatts per square metre.\n- **BAL-FZ:** the site is likely to be exposed to direct contact with the fire front, very high heat flux and ember attack.\n\n## How a BAL is assessed\n\nThe assessment considers the regional fire danger index, the type of surrounding vegetation, the distance from the building to that vegetation, and the slope of the land beneath it. After the February 2009 Victorian bushfires, which destroyed more than 2,000 houses, Standards Australia fast-tracked revisions and bushfire attack assessments became central to building approvals in bushfire-prone areas. The Australian Building Codes Board adopted a design flame temperature of 1,090 K (about 820 °C) for the standard.\n\n## Roofing implications\n\nAs the BAL rises, AS 3959 requires progressively stricter roof details. Typical concerns include:\n\n- **Non-combustible roof coverings** such as metal sheeting or tile at higher levels;\n- **Sarking (underlay)** with a low flammability index beneath tiles;\n- **Sealing gaps** at eaves, ridges and between the covering and fascia, often with mineral wool or non-combustible closures;\n- **Ember guards** on vents, gutters and evaporative cooler openings;\n- **Restrictions on combustible fascias, eaves linings and skylights.**\n\nIn New South Wales, the Rural Fire Service's Planning for Bush Fire Protection 2019 document sets out additional statutory requirements for building on bushfire-prone land.\n\n## Comparison with other systems\n\nBAL is a site exposure rating, not a product rating. It differs from North American systems, which rate roof coverings (for example Class A under ASTM E108) and apply wildland-urban interface code zones.","key_facts":[{"label":"Country","value":"Australia"},{"label":"Standard","value":"AS 3959"},{"label":"Levels","value":"BAL-LOW, 12.5, 19, 29, 40, FZ"},{"label":"Number meaning","value":"Radiant heat flux in kW/m²"},{"label":"Design flame temperature","value":"1,090 K (about 820 °C)"}],"regions":["Oceania"],"aliases":["BAL","BAL rating","AS 3959","bushfire attack level"],"related":["wildfire-roofing","ember-resistant-roofing","class-a-fire-rating"],"sources":[{"title":"2009 Victorian bushfires","url":"https://en.wikipedia.org/wiki/2009_Victorian_bushfires","publisher":"Wikipedia"},{"title":"Building in a bush fire area","url":"https://www.rfs.nsw.gov.au/plan-and-prepare/building-in-a-bush-fire-area","publisher":"NSW Rural Fire Service"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"butterfly-roof","title":"Butterfly Roof","category":"roof-forms","type":"article","summary":"A butterfly roof is an inverted gable: two roof planes slope down from the outer walls to a central valley, like a pair of raised wings.","body":"A butterfly roof, also called a V roof, is formed by two roof surfaces that slope downward from opposite outer edges to meet in a valley near the middle of the building. The profile resembles the wings of a butterfly, or an open book. The outer walls are tall, allowing large clerestory windows and a sense of openness, while rainwater collects in the centre.\n\n## History\n\n- Le Corbusier first used the form in 1930 for the Maison Errázuriz, a holiday house in Chile.\n- Other early modernist examples include Antonin Raymond's house in Japan (1933), Oscar Niemeyer's Pampulha Yacht Club in Brazil (1943) and Marcel Breuer's Geller House project on Long Island (1945).\n- In the late 1950s the architects William Krisel and Dan Palmer popularised the form in Palm Springs, California; from 1957 their Alexander tract developments produced nearly 2,000 houses, many with butterfly roofs. It became an emblem of American mid-century modern design.\n- In British cities, a similar V-shaped roof hidden behind a front parapet is found on many Georgian and Victorian terraced houses, where it is known as a London roof.\n\n## Drainage\n\nButterfly roofs typically have no perimeter gutters. Water runs to the central valley and out at one or both ends, often through a scupper into a downspout or water feature. The valley may itself be sloped, or flat with a central cricket that sends water toward the ends. The concentration of water in one place makes the valley lining, outlets and overflow provisions critical, and debris or snow can accumulate there.\n\n## Advantages and drawbacks\n\n- Tall outer walls allow generous glazing and daylight.\n- The form suits rainwater harvesting, since water is collected at one point.\n- The planes can carry solar panels.\n- The central valley is a single point of failure for leaks, and the form is generally more complex and costly to waterproof than a gable roof.","key_facts":[{"label":"Also called","value":"V roof; London roof (UK terraces)"},{"label":"First modern use","value":"Maison Errázuriz, Chile (1930)"},{"label":"Popularised","value":"Palm Springs, late 1950s"}],"regions":["Global","North America","Europe"],"aliases":["V roof","V-shaped roof","London roof","inverted pitch roof"],"related":["m-shaped-roof","roof-valley","chimney-cricket","flat-roof","shed-roof"],"company":null,"sources":[{"title":"Butterfly roof","url":"https://en.wikipedia.org/wiki/Butterfly_roof","publisher":"Wikipedia"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"}],"country":null},{"slug":"title-24-cool-roof","title":"California Title 24 Cool Roof Requirements","summary":"California's Title 24 Part 6 Energy Code includes requirements for roof solar reflectance and thermal emittance, updated every three years.","body":"California's **Building Energy Efficiency Standards**, published as Title 24, Part 6 of the California Code of Regulations, form the state's Energy Code. They are developed and maintained by the California Energy Commission (CEC) and updated on a three-year cycle. The 2025 standards take effect on 1 January 2026. A companion part, CALGreen (Title 24, Part 11), contains green building provisions, some of them voluntary.\n\nCalifornia was one of the first jurisdictions to build \"cool roof\" provisions into a statewide energy code, and its rules have influenced other codes and local ordinances.\n\n## What the cool roof provisions do\n\nThe Energy Code sets minimum values for a roof's **aged solar reflectance** and **thermal emittance**, or a combined [Solar Reflectance Index](/solar-reflectance-index), in many situations. Requirements vary by:\n\n- **building type** (nonresidential, high-rise residential, low-rise residential)\n- **roof slope** (low-slope and steep-slope have different thresholds)\n- **climate zone** – California is divided into 16 building climate zones, and cool roof rules are strongest in the hotter inland zones\n\nThe provisions apply to new construction and, in many cases, to reroofing projects that replace a large share of an existing roof. Trade-offs are allowed: for example, extra insulation or other efficiency measures can sometimes offset a roof that does not meet the reflectance values, using the performance compliance path.\n\n## Rated products\n\nRoofing products used to comply must have their radiative properties rated by the [Cool Roof Rating Council](/cool-roof-rating-council). Contractors and inspectors check the CRRC label or directory listing for the product's aged reflectance and emittance.\n\n## Why it matters for roofers\n\nIn California, choosing a roof colour or coating can be a code issue, not only a design choice. Dark shingles or membranes that do not meet the applicable values may require compliance trade-offs on the energy documentation. Reroofing permits often require a cool roof compliance form.\n\n## Wider influence\n\nCool roof provisions now appear in other energy standards, notably [ASHRAE 90.1](/ashrae-90-1), which added solar reflectance and thermal emittance requirements in its 2010 edition, and in local ordinances in cities across the United States.","key_facts":[{"label":"Code","value":"California Code of Regulations, Title 24, Part 6"},{"label":"Administered by","value":"California Energy Commission"},{"label":"Update cycle","value":"Every 3 years"},{"label":"Current edition","value":"2025 standards, effective 1 January 2026"},{"label":"Product ratings","value":"Cool Roof Rating Council"}],"regions":["North America"],"aliases":["Title 24","Title 24 Part 6","California Energy Code","Title 24 cool roof"],"related":["cool-roof-rating-council","solar-reflectance-index","ashrae-90-1","cool-roof","roof-replacement-process"],"sources":[{"title":"Building Energy Efficiency Standards","url":"https://www.energy.ca.gov/programs-and-topics/programs/building-energy-efficiency-standards","publisher":"California Energy Commission"},{"title":"Cool roof","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"},{"title":"Using Cool Roofs to Reduce Heat Islands","url":"https://www.epa.gov/heatislands/using-cool-roofs-reduce-heat-islands","publisher":"US EPA"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"canadian-roofing-contractors-association","title":"Canadian Roofing Contractors Association (CRCA)","summary":"CRCA is Canada's national roofing contractors' association, active since 1960 and based in Ottawa, Ontario.","body":"The Canadian Roofing Contractors Association (CRCA) is the national trade association for the roofing industry in Canada. It has represented roofing contractors since 1960 and is headquartered in Ottawa, Ontario. Its website is roofingcanada.com.\n\nCRCA's members include roofing contractors, manufacturers and distributors from across the country. The association works closely with provincial and regional roofing associations, such as the Roofing Contractors Association of British Columbia, which handle many local programs and training.\n\n## Role\n\n- **Advocacy.** CRCA speaks for the roofing industry on national issues, including federal policy, workforce and immigration, trade and taxation, and the National Building Code of Canada.\n- **Technical support.** The association provides technical guidance and standards of practice for members and takes part in standards and code committees.\n- **Collaboration.** It links with partner associations in Canada and abroad, including the U.S. National Roofing Contractors Association and international roofing federations.\n- **Recognition.** CRCA runs awards, including the Roofing Canada Award, and recognises long-standing member companies.\n\n## Annual conference\n\nCRCA holds an annual conference that brings together contractors and suppliers from across Canada. By 2024 the event had reached its 64th edition.\n\n## National Roofing Week\n\nCRCA promotes a National Roofing Week to raise public awareness of roofing, roof maintenance and careers in the trade.\n\n## Context\n\nCanada's roofing industry works across a very wide range of climates, from the wet Pacific coast to prairie hail zones, heavy snow regions and the North. Roof design and installation must meet the National Building Code of Canada as adopted by each province or territory, plus local rules. Contractor licensing is a provincial or municipal matter; CRCA membership is voluntary and is not a licence.","key_facts":[{"label":"Active since","value":"1960"},{"label":"Headquarters","value":"Ottawa, Ontario, Canada"},{"label":"Scope","value":"National trade association"},{"label":"Website","value":"roofingcanada.com"}],"regions":["North America"],"aliases":["CRCA","Roofing Canada"],"related":["roofing-contractors-association-of-british-columbia","nrca","national-building-code-of-canada","how-to-find-a-licensed-roofer"],"company":{"founded":"1960","headquarters":"Ottawa, Ontario, Canada","website":"https://roofingcanada.com","known_for":["National roofing advocacy in Canada","Annual CRCA conference"]},"sources":[{"title":"About CRCA","url":"https://roofingcanada.com/?p=50","publisher":"Canadian Roofing Contractors Association"},{"title":"National Roofing Week in Canada","url":"https://roofingcanada.com/?p=12023","publisher":"Canadian Roofing Contractors Association"},{"title":"Get ready for the 64th annual CRCA conference","url":"https://www.rooferscoffeeshop.com/post/get-ready-for-the-64th-annual-crca-conference","publisher":"RoofersCoffeeShop"}],"category":"organizations","type":"organization","country":null},{"slug":"cape-dutch-thatch","title":"Cape Dutch Thatch","type":"article","summary":"Thatched roofs over whitewashed walls and ornate gables, the signature of Cape Dutch architecture in South Africa's Western Cape.","body":"Cape Dutch architecture developed in the Dutch Cape Colony, in what is now the Western Cape of South Africa, from the 17th century. Its defining image is a long, whitewashed house under a steep thatched roof, broken by an ornately shaped central gable. The style is closely tied to wine estates and farmsteads in areas such as Stellenbosch, Paarl and Constantia.\n\n## Form\n\nThe typical Cape Dutch homestead has an H-shaped plan: a central front section flanked by two wings at right angles. Each wing carries its own thatched roof, and the roofs meet in valleys. Other characteristic features include large timber sash windows, external shutters and green-painted joinery. Gables are common but not universal; some houses, such as the Uitkyk manor, have none.\n\n## Thatch\n\nThe roofs were thatched, giving a thick, steep covering suited to the winter-rainfall climate of the Cape. In common with thatch practice elsewhere, such roofs are typically pitched at about 45-55 degrees so that water runs off before it can penetrate.\n\nThatch is vulnerable to fire. The Groot Constantia manor house, one of the oldest Cape Dutch homesteads, was completely destroyed by fire in 1925 and later reconstructed in its original style.\n\n## Gables\n\nThe gable is the most decorative part of the facade. A grand, rounded \"clock\" gable over the front door is the most celebrated type. Gables are plastered masonry, rising above the thatch line.\n\n## Revival\n\nA Cape Dutch Revival began in 1893, when Cecil John Rhodes bought Groote Schuur and commissioned Herbert Baker to redesign it. The revival spread to Johannesburg after 1902 and became something of a national style after the Union of South Africa was formed in 1910. Revival buildings are known mainly for their elaborate gables.\n\n## Today\n\nThatch remains in use in South Africa, both on heritage homesteads and on new houses and lodges, and South Africa is also an exporter of thatching reed.","key_facts":[{"label":"Region","value":"Western Cape, South Africa"},{"label":"Period","value":"From the 17th century"},{"label":"Typical plan","value":"H-shaped"},{"label":"Roof","value":"Steep thatch with masonry gables"},{"label":"Revival","value":"From 1893 (Groote Schuur)"}],"regions":["Africa"],"aliases":["Cape Dutch architecture","Cape Dutch gable"],"related":["roofing-in-southern-africa","thatch","rondavel","water-reed-thatch"],"sources":[{"title":"Cape Dutch architecture","url":"https://en.wikipedia.org/wiki/Cape_Dutch_architecture","publisher":"Wikipedia"},{"title":"Groot Constantia","url":"https://en.wikipedia.org/wiki/Groot_Constantia","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"carlisle-companies","title":"Carlisle Companies","category":"manufacturers","type":"company","summary":"Carlisle Companies is a US manufacturer, based in Scottsdale, Arizona, focused on commercial roofing and building envelope products.","body":"Carlisle Companies is a publicly listed US industrial company that has narrowed its focus to building products, especially commercial roofing. It was founded in 1917 in Carlisle, Pennsylvania and is now headquartered in Scottsdale, Arizona. Its operations are organised in two segments: Carlisle Construction Materials (CCM), which produces most of the group's revenue, and Carlisle Weatherproofing Technologies (CWT).\n\n## Carlisle Construction Materials\n\nCCM makes single-ply roofing membranes (EPDM, TPO and PVC), polyiso insulation and related accessories for low-slope commercial roofs. Its single-ply roofing systems are marketed under brand names including Carlisle SynTec Systems. In 2024 Carlisle acquired MTL Holdings.\n\n## Carlisle Weatherproofing Technologies\n\nCWT covers air and vapour barriers, waterproofing, sealants, coatings and spray foam. Its largest acquisition was Henry Company, a building envelope systems company bought in 2021. Carlisle had earlier acquired Accella Performance Materials in 2017.\n\n## Market\n\nCommercial low-slope roofing in North America is largely a replacement market, and single-ply membranes such as EPDM and TPO are among the most common roof coverings on such buildings. Carlisle sells through distributors to contractors, who can obtain manufacturer system warranties.\n\n## Membranes and insulation\n\nThe three main single-ply membranes differ in chemistry and seaming. EPDM is a synthetic rubber, usually seamed with tape or adhesive. TPO and PVC are thermoplastics whose seams are fused with hot air, producing a continuous welded sheet. All three are typically laid over rigid polyiso insulation, which provides most of a low-slope roof's thermal resistance, and may be fully adhered, mechanically fastened or ballasted depending on wind exposure and building design.","key_facts":[{"label":"Founded","value":"1917, Carlisle, Pennsylvania"},{"label":"Headquarters","value":"Scottsdale, Arizona, US"},{"label":"Segments","value":"CCM and CWT"},{"label":"Notable acquisitions","value":"Henry Company (2021), MTL Holdings (2024)"}],"regions":["North America","Europe"],"aliases":["Carlisle","Carlisle Construction Materials","CCM","Carlisle SynTec"],"related":["epdm-roofing","tpo-roofing","pvc-roofing","henry-company","polyiso-insulation","single-ply-roofing"],"company":{"founded":"1917","headquarters":"Scottsdale, Arizona, United States","website":"https://www.carlisle.com","known_for":["Single-ply roofing membranes","Polyiso insulation","Building envelope systems"]},"sources":[{"title":"Carlisle Companies","url":"https://en.wikipedia.org/wiki/Carlisle_Companies","publisher":"Wikipedia"},{"title":"Carlisle Construction Materials renames coatings, adhesives, sealants and elastomers business","url":"https://www.roofingcontractor.com/articles/94557-carlisle-construction-materials-renames-coatings-adhesives-sealants-and-elastomers-business","publisher":"Roofing Contractor"},{"title":"Carlisle Companies Incorporated","url":"https://metalconstruction.org/index.php/suppliers/carlisle-companies-incorporated","publisher":"Metal Construction Association"}],"country":null},{"slug":"carlisle-syntec-systems","title":"Carlisle SynTec Systems","category":"manufacturers","type":"company","summary":"Carlisle SynTec Systems is a commercial single-ply roofing brand of Carlisle Construction Materials, based in Carlisle, Pennsylvania.","body":"Carlisle SynTec Systems is a commercial roofing manufacturer and brand operated as a division of Carlisle Construction Materials (CCM), which is a wholly owned subsidiary of the NYSE-listed Carlisle Companies. Its mailing address is in Carlisle, Pennsylvania, the town where the parent company was founded in 1917.\n\n## Products\n\nCarlisle SynTec supplies complete low-slope roofing systems for commercial, industrial and institutional buildings. Its main product groups are:\n\n- **EPDM** synthetic rubber membranes, a long-established single-ply material in North America.\n- **TPO** (thermoplastic polyolefin) membranes, which are heat-welded at the seams.\n- **PVC** membranes, also heat-welded and often specified for chemical or grease exposure.\n- **FleeceBACK** membranes, which carry a fleece backing to allow adhesion to a wider range of substrates.\n- System components such as polyiso insulation (including a thin product marketed as ThermaThin), adhesives, coatings and edge metal.\n\nThe company also promotes a seam technology branded SeamShield and offers whole-building envelope programmes under the NVELOP name.\n\n## Relationship to other Carlisle brands\n\nCarlisle sells similar membrane technologies through more than one brand. Versico, for example, is a separate division of CCM offering EPDM, TPO and PVC systems through its own contractor network. Both brands share the parent's manufacturing base.\n\n## Market role\n\nSingle-ply membranes cover a large proportion of commercial low-slope roofs in North America, and replacement of older roofs is the main source of demand. Manufacturers such as Carlisle SynTec sell through distributors to authorised contractors and offer system warranties when installations follow their published specifications. Product data, specifications and warranty terms are published on the company's website.","key_facts":[{"label":"Parent","value":"Carlisle Construction Materials / Carlisle Companies"},{"label":"Location","value":"Carlisle, Pennsylvania, US"},{"label":"Products","value":"EPDM, TPO, PVC and FleeceBACK membranes"}],"regions":["North America"],"aliases":["Carlisle SynTec","Carlisle Roofing"],"related":["carlisle-companies","versico","epdm-roofing","tpo-roofing","pvc-roofing","polyiso-insulation"],"company":{"headquarters":"Carlisle, Pennsylvania, United States","website":"https://www.carlislesyntec.com","parent":"Carlisle Companies","known_for":["EPDM membranes","TPO membranes","FleeceBACK membranes"]},"sources":[{"title":"Carlisle SynTec Systems","url":"https://www.carlislesyntec.com/","publisher":"Carlisle SynTec Systems"},{"title":"Versico Roofing Systems","url":"https://www.versico.com/","publisher":"Versico"},{"title":"Carlisle Companies","url":"https://en.wikipedia.org/wiki/Carlisle_Companies","publisher":"Wikipedia"}],"country":null},{"slug":"catalan-vault","title":"Catalan Vault","category":"history","type":"article","summary":"A shallow vault of thin flat tiles laid in layers without formwork, from Catalonia and Valencia; brought to the US by Rafael Guastavino.","body":"The Catalan vault, also called the timbrel vault or thin-tile vault (Catalan volta catalana, Spanish bóveda tabicada), is a way of building a vaulted ceiling or roof from thin bricks or tiles laid flat. The first layer is laid \"in space\" without centering or formwork, and further layers, usually three in total, are bonded over it with mortar. The curve is much flatter than in most brick vaulting. Such vaults often carry a floor or roof above them.\n\n## Origins and spread\n\nThe technique developed and flourished in Catalonia, Valencia and neighbouring regions and is found throughout the Mediterranean. The Romans built brick vaults but did not lay them in this way. The name \"Catalan vault\" was coined at an architectural congress in Madrid in 1904. The method was taken to New Spain and is still used in parts of Mexico. In Catalonia, the architects Antoni Gaudí and Josep Puig i Cadafalch helped spread it in more recent times.\n\n## Guastavino in the United States\n\nRafael Guastavino (1842-1908), a Valencian architect and builder, moved to New York in 1881 with his son Rafael Jr. In 1885 he patented his Tile Arch System, based on the Catalan vault, using thin terracotta tiles and layers of mortar. Father and son eventually held 24 patents.\n\nThe Guastavino Fireproof Construction Company, incorporated in 1889, specialised in fireproof construction. Run first by the father and then by the son, it carried out its last contract in 1962. Hundreds of major buildings contain Guastavino vaulting, among them:\n\n- Boston's Central Library (1889);\n- New York's City Hall subway station (opened 1904), Carnegie Hall and Grand Central Terminal;\n- the dome of the Cathedral of St. John the Divine, New York;\n- the Great Hall ceiling at Ellis Island, rebuilt in 1917;\n- the Basilica of St. Lawrence, Asheville, North Carolina (designed 1905).\n\nIn the US the technique is often simply called Guastavino tile. John Ochsendorf and Michael Freeman's *Guastavino Vaulting: The Art of Structural Tile* (2010) documents the company's work.\n\n## How it works\n\nBecause each tile is thin and laid flat, a Catalan vault is light for its span. It works mainly in compression, like any masonry vault, so its shape must follow the line of thrust, and the walls or ties must resist the outward push at its springing. Building without formwork saves the timber that centering would otherwise require.\n\n## Roofing relevance\n\nCatalan vaults often serve as the structure that carries a floor or roof above. The method relates to other unreinforced vaulting traditions such as the Nubian vault and the mud-brick barrel vaults of Iran, which are also built without centering.","key_facts":[{"label":"Other names","value":"Timbrel vault, thin-tile vault, boveda tabicada, Guastavino tile"},{"label":"Origin","value":"Catalonia, Valencia and the Mediterranean"},{"label":"Layers","value":"Usually three courses of flat tile"},{"label":"Formwork","value":"Not needed for the first layer"},{"label":"Guastavino patent","value":"Tile Arch System, US, 1885"}],"regions":["Europe","North America","Latin America"],"aliases":["timbrel vault","thin-tile vault","boveda tabicada","volta catalana","Guastavino tile","tile arch system"],"related":["barrel-vault-roof","nubian-vault","mud-roof","terracotta","middle-eastern-domes"],"company":null,"sources":[{"title":"Catalan vault","url":"https://en.wikipedia.org/wiki/Catalan_vault","publisher":"Wikipedia"},{"title":"Rafael Guastavino","url":"https://en.wikipedia.org/wiki/Rafael_Guastavino","publisher":"Wikipedia"}],"country":null},{"slug":"catalhoyuk-roofs","title":"Çatalhöyük Roofs","category":"history","type":"article","regions":["Middle East","Europe"],"company":null,"summary":"The flat roofs of Neolithic Çatalhöyük in Turkey, where houses had no streets between them and people entered from the roof.","aliases":["Catalhoyuk roofs","Çatal Höyük","Neolithic roof access","roof-entry houses"],"body":"Çatalhöyük, on the Konya plain of central Turkey, is one of the best-known early farming settlements in the world and one of the clearest early cases of the roof doing far more than keeping out the weather. Its mud-brick houses were packed together without streets, so the roofscape itself became the circulation space of the town.\n\nThe eastern mound was occupied in the Neolithic from roughly 7400 to 6200 BC, according to UNESCO, and a western mound continued in the Chalcolithic to about 5200 BC. Wikipedia's summary of the excavations gives a slightly different span (about 7500 to 5600 BC for the eastern mound), reflecting different dating schemes. The site was inscribed on the UNESCO World Heritage List as the Neolithic Site of Çatalhöyük.\n\n## A town without streets\n\nHouses were built of mud brick and set back to back in a dense, honeycomb-like block. With no lanes or footpaths between them, people moved across the flat roofs. Most houses were entered through an opening in the roof and down a timber ladder or steep stair into the main room. UNESCO describes the settlement as streetless with access through the roofs.\n\n## The roof as living space\n\nIn good weather much daily activity probably took place on the rooftops, which may have worked together as a kind of open plaza. In later phases, large communal ovens were built up on the roofs. Inside, the roof opening was the only ventilation, so it also had to let smoke escape from the hearth and oven, which were usually set against the south wall of the main room.\n\n## Rebuilding in layers\n\nHouses were renewed by partly demolishing the old building and building again on top of the levelled rubble. Repeated over many generations, this raised the mound by up to about 20 m (66 ft) above the plain and left as many as 18 superimposed settlement levels. That sequence is why the site is so valuable for understanding how early houses, and their roofs, developed.\n\n## Excavation and protection\n\nJames Mellaart identified the site in 1958 and excavated about two hundred buildings between 1961 and 1965. Work resumed under Ian Hodder in the 1990s and continued until about 2018. Today large shelter roofs over the two main excavation areas protect the mud-brick remains from rain and erosion, an unusual case of a modern roof being built specifically to save ancient ones.\n## Sources and gaps\n\nSpecific figures for the build-up of the roofs (timber spacing, reed or brush layers, thickness of mud): published information is limited. Flat roofs of timber, small branches or reeds and packed earth are the general pattern for the region (see flat-roof and mud-roof).","key_facts":[{"label":"Location","value":"Konya plain, central Turkey"},{"label":"Neolithic occupation","value":"C. 7400-6200 BC (UNESCO)"},{"label":"Material","value":"Mud brick"},{"label":"Access","value":"Through openings in the roof, by ladder"},{"label":"Settlement levels","value":"Up to 18"}],"related":["flat-roof","mud-roof","roofing-in-turkey","prehistoric-shelters-and-early-thatch"],"sources":[{"title":"Neolithic Site of Çatalhöyük","url":"https://whc.unesco.org/en/list/1405","publisher":"UNESCO World Heritage Centre"},{"title":"Çatalhöyük","url":"https://en.wikipedia.org/wiki/%C3%87atalh%C3%B6y%C3%BCk","publisher":"Wikipedia"}],"country":null},{"slug":"ce-marking-construction-products","title":"CE Marking and Declaration of Performance (Construction Products)","type":"term","summary":"In the EU, roofing products covered by a harmonised standard must carry CE marking and a Declaration of Performance under the Construction Products Regulation.","body":"In the European Union, **CE marking** on a construction product shows that the manufacturer has declared its performance according to the EU's harmonised rules. For roofing products such as tiles, slates, membranes, metal sheet and underlays, CE marking is governed by the **Construction Products Regulation (CPR)**.\n\n## The Construction Products Regulation\n\nRegulation (EU) No 305/2011, dated 9 March 2011, replaced the earlier Construction Products Directive 89/106/EEC. Its aim is to harmonise the rules for marketing construction products in the EU and to create a common technical language for describing their performance. The CPR was revised in 2024, and the European Commission is managing a transition from the 2011 regulation to the new one, which adds elements such as a combined Declaration of Performance and Conformity and a digital product passport.\n\n## Declaration of Performance\n\nWhen a product is covered by a **harmonised European standard (hEN)** or has a **European Technical Assessment (ETA)**, the manufacturer must draw up a **Declaration of Performance (DoP)** before applying CE marking. The DoP states:\n\n- the product type and intended use\n- the harmonised standard or assessment document used\n- the assessment system that applies\n- the essential characteristics and the declared performance for at least one of them\n\nFor roofing, essential characteristics might include external fire performance (classified under [EN 13501-5](/en-13501-5)), reaction to fire, water tightness, tensile strength, frost resistance or wind uplift resistance, depending on the product standard. Examples of harmonised product standards include [EN 1304](/en-1304) for clay tiles, [EN 490](/en-490-en-491) for concrete tiles and [EN 544](/en-544) for bitumen shingles.\n\nCE marking is placed on the product, or on its packaging or accompanying documents where that is not possible.\n\n## Assessment systems (AVCP)\n\nThe CPR defines five systems for the **assessment and verification of constancy of performance (AVCP)**: 1+, 1, 2+, 3 and 4, in decreasing order of strictness. Under the stricter systems, a **notified body** audits the factory production control and issues a certificate that allows the manufacturer to issue the DoP. Under System 4, the manufacturer carries out the assessment itself.\n\n## Products without a harmonised standard\n\nInnovative products can be CE marked through the European Assessment Document (EAD) and ETA route, coordinated by the European Organisation for Technical Assessment (EOTA).\n\n## What CE marking does not mean\n\nCE marking is not a quality or approval mark. It shows that performance has been declared using common methods. Each country's building regulations then decide what performance is required for a given use. After Brexit, Great Britain introduced the UKCA mark for products placed on its market, with transitional recognition of CE marking.","key_facts":[{"label":"Legal basis","value":"Regulation (EU) No 305/2011 (revised 2024)"},{"label":"Replaced","value":"Directive 89/106/EEC"},{"label":"Key document","value":"Declaration of Performance (DoP)"},{"label":"AVCP systems","value":"1+, 1, 2+, 3, 4"},{"label":"Alternative route","value":"EAD / European Technical Assessment"}],"regions":["Europe"],"aliases":["CE mark","Declaration of Performance","DoP","Construction Products Regulation","CPR"],"related":["en-13501-5","en-1304","en-544","bba-agrement"],"sources":[{"title":"Construction Products Regulation (CPR)","url":"https://single-market-economy.ec.europa.eu/sectors/construction/construction-products-regulation-cpr_en","publisher":"European Commission"},{"title":"Construction Products Regulation","url":"https://en.wikipedia.org/wiki/Construction_Products_Regulation","publisher":"Wikipedia"}],"category":"standards-codes","company":null,"country":null},{"slug":"cedar-shake-and-shingle-bureau","title":"Cedar Shake & Shingle Bureau (CSSB)","summary":"The Cedar Shake & Shingle Bureau is a North American trade body for cedar roofing, founded in 1915, known for its Certi-label quality marks.","body":"The Cedar Shake & Shingle Bureau (CSSB) is a non-profit trade association representing producers and installers of cedar shakes and shingles in Canada and the United States. It was established on 9 June 1915, when trustees of the West Coast Lumber Manufacturers Association agreed to set up a branch serving members who made shingles. The bureau has published installation manuals and quality standards for cedar roofing for more than a century. Its website is cedarbureau.org.\n\n## History\n\n- **1915** – formed as a shingle branch of the West Coast Lumber Manufacturers Association.\n- **1963** – merged with the Handsplit Shake Bureau to become the Red Cedar Shingle & Handsplit Shake Bureau.\n- **Late 1980s** – mill quality-control inspections were contracted out to independent third-party agencies.\n- **1988** – members renamed the organisation the Cedar Shake & Shingle Bureau.\n\nIts historical records form part of the BC Archives held by the Royal BC Museum.\n\n## Certi-label products\n\nThe bureau's member mills produce shakes and shingles under the Certi-label® mark. Products carry labels showing the grade and the standard they are made to, and mills are inspected by independent agencies. Typical grades depend on how much of each piece is clear heartwood and on whether the grain is edge grain (vertical) or flat grain.\n\n## Manuals\n\nThe CSSB publishes a *New Roof Construction Manual* and a wall manual. These cover:\n\n- the difference between **shingles** (sawn, smooth on both faces) and **shakes** (split, with at least one textured face);\n- exposure (the visible length of each course), which varies with roof pitch and product length;\n- underlayment and interlayment of felt between shake courses;\n- ventilation, fastener type (stainless steel or hot-dipped galvanised), and preservative or fire-retardant treatments.\n\n## Context\n\nWestern red cedar, mostly from British Columbia and the U.S. Pacific Northwest, is the main species. Cedar roofs are also used in Europe, Australia and Japan. Fire codes in wildfire-prone areas may require treated products or restrict wood roofs.","key_facts":[{"label":"Founded","value":"9 June 1915"},{"label":"Current name since","value":"1988"},{"label":"Quality mark","value":"Certi-label"},{"label":"Main species","value":"Western red cedar"}],"regions":["North America"],"aliases":["CSSB","Red Cedar Shingle & Handsplit Shake Bureau","Cedar Bureau"],"related":["wood-shingle","roof-ventilation","wood-shake","western-red-cedar","tapersawn-shake","handsplit-shake"],"company":{"founded":"1915","website":"https://www.cedarbureau.org","known_for":["Certi-label cedar shakes and shingles","New Roof Construction Manual"]},"sources":[{"title":"Cedar Shake and Shingle Bureau history","url":"https://www.cedarbureau.org/wp-content/uploads/2020/05/Page-028-Cedar-Shake-and-Shingle-BureauR-History.pdf","publisher":"Cedar Shake & Shingle Bureau"},{"title":"New Roof Construction Manual","url":"https://www.cedarbureau.org/wp-content/uploads/2025/05/RoofManual_DIGITAL-29.pdf","publisher":"Cedar Shake & Shingle Bureau"},{"title":"Cedar Shake and Shingle fonds","url":"https://search-bcarchives.royalbcmuseum.bc.ca/cedar-shake-and-shingle-fonds","publisher":"Royal BC Museum"},{"title":"Cedar Shake & Shingle Bureau","url":"https://www.cedarbureau.org/","publisher":"Cedar Shake & Shingle Bureau"},{"title":"Roof Installation Manual","url":"https://www.cedarbureau.org/installation/roof-installation-manual/","publisher":"Cedar Shake & Shingle Bureau"}],"category":"organizations","type":"organization","country":null},{"slug":"cellular-glass-insulation","title":"Cellular Glass Insulation","category":"low-slope-systems","type":"term","summary":"Rigid, closed-cell insulation made by foaming crushed glass, impermeable to water and vapour and able to carry heavy loads on roofs.","body":"Cellular glass, also called foam glass, is rigid insulation made by heating crushed or recycled glass with a foaming agent such as carbon or limestone. Gas released during heating forms bubbles, and the cooled product is a block of glass whose volume is mostly sealed cells. Saint-Gobain filed the first patent for foam glass made with calcium carbonate in 1932; the Foamglas product was later developed by Pittsburgh Corning.\n\n## Properties\n\n- **Closed cells:** more than 75% of the insulating product consists of closed cells, so it has no capillary action and does not absorb water.\n- **Vapour:** the glass cell walls make boards effectively vapour-tight; a fully bonded cellular glass layer can act as its own vapour control.\n- **Strength:** rigid and dimensionally stable, suited to heavy loads.\n- **Fire:** made of glass, so non-combustible; one major product is classed Euroclass A1.\n- **Durability:** resistant to rot, pests and most chemicals.\n\nThermal conductivity of cellular glass boards is higher than that of polyiso or XPS, so more thickness is needed for the same thermal value. Loose foam-glass aggregate, used as fill, has a lambda of about 0.08 W/(m.K).\n\n## Roof uses\n\nCellular glass is chosen for compact (fully bonded) warm roofs, particularly in central Europe, where boards are set in hot bitumen on concrete or steel decks so that no water can travel within the assembly. It is also used under green roofs, parking decks, plazas and roofs with heavy plant, and for tapered schemes.\n\n## Considerations\n\nBoards are brittle and must be handled carefully; surfaces exposed to traffic during construction need protection. Cost is usually higher than foam insulations.\n\n## Approvals\n\nCompact cellular glass roof assemblies have been tested as complete systems; one manufacturer offers an FM Approved compact roof system for demanding commercial roofs and separate systems for trafficked activity roofs.","key_facts":[{"label":"Composition","value":"Foamed glass with closed cells"},{"label":"First patent","value":"Saint-Gobain, 1932"},{"label":"Water absorption","value":"None by capillarity"},{"label":"Fire","value":"Non-combustible"}],"regions":["Europe","Global"],"aliases":["foam glass","Foamglas (trademark)","cellular glass board"],"related":["roof-insulation","green-roof","vapor-retarder","tapered-insulation"],"company":null,"sources":[{"title":"Foam glass","url":"https://en.wikipedia.org/wiki/Foam_glass","publisher":"Wikipedia"},{"title":"FOAMGLAS cellular glass insulation","url":"https://www.foamglas.com/","publisher":"Owens Corning FOAMGLAS"}],"country":null},{"slug":"cen-ts-1187","title":"CEN/TS 1187","summary":"CEN/TS 1187 is the European technical specification with four test methods for how roofs behave when exposed to fire from outside.","body":"CEN/TS 1187, *Test methods for external fire exposure to roofs*, is a Technical Specification published by CEN, the European Committee for Standardization, under its fire safety committee CEN/TC 127. The current edition is CEN/TS 1187:2012, which replaced the earlier pre-standard ENV 1187:2002 and its 2005 amendment. CEN lists it as due for revision.\n\nIts results are used to classify roofs under [EN 13501-5](/en-13501-5), producing classes such as BROOF(t1) or BROOF(t4).\n\n## The four tests\n\nThe four methods are independent. A result from one cannot be substituted for another.\n\n- **Test 1** – burning brands only.\n- **Test 2** – burning brands combined with wind.\n- **Test 3** – burning brands, wind and additional radiant heat.\n- **Test 4** – a two-stage test, each stage combining burning brands, wind and radiant heat.\n\nBetween them, the tests assess:\n\n- fire spread across the outer surface of the roof (all tests)\n- fire spread within the roof build-up (Tests 1 to 3)\n- fire penetration through the roof (Tests 1, 3 and 4)\n- burning droplets or debris falling from the roof (Tests 1, 3 and 4)\n\nTests 2 and 3 cannot be used for geometrically irregular roofs or roofs with mounted equipment such as ventilators or rooflights.\n\n## Why there are four methods\n\nBefore European harmonization, countries used different national roof fire tests, and the regulators of each country were reluctant to give theirs up. CEN/TS 1187 brings these approaches into a common format, and each country's regulations specify which test is required. This means a roofing product sold widely in Europe may be tested to several methods.\n\n## What is tested\n\nTests are run on a representative roof build-up, including deck, insulation, underlay and covering, because the layers below the surface strongly affect fire behaviour. A membrane might achieve BROOF on one insulation type and not on another, so classifications are tied to the build-up described in the classification report.\n\n## Comparison with North America\n\nThe closest North American equivalent is [ASTM E108 / UL 790](/astm-e108-ul-790), which also uses burning brands and flame spread but produces Class A, B or C ratings. The results do not convert directly between systems.","key_facts":[{"label":"Publisher","value":"CEN (TC 127 Fire safety in buildings)"},{"label":"Current edition","value":"CEN/TS 1187:2012"},{"label":"Replaced","value":"ENV 1187:2002 and A1:2005"},{"label":"Number of tests","value":"4 (independent)"},{"label":"Used for","value":"EN 13501-5 classification"}],"regions":["Europe"],"aliases":["TS 1187","ENV 1187","external fire exposure to roofs test"],"related":["en-13501-5","astm-e108-ul-790","ce-marking-construction-products","skylight"],"sources":[{"title":"CEN/TS 1187:2012","url":"https://genorma.com/en/standards/cen-ts-1187-2012","publisher":"Genorma (CEN catalogue data)"},{"title":"EN 13501-5:2016","url":"https://genorma.com/en/standards/en-13501-5-2016","publisher":"Genorma (CEN catalogue data)"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"certainteed","title":"CertainTeed","category":"manufacturers","type":"company","summary":"CertainTeed is a North American building-products maker founded in 1904, now a wholly owned subsidiary of France's Saint-Gobain, producing roofing, siding and insulation.","body":"CertainTeed is a North American manufacturer of roofing, siding, insulation, gypsum and ceiling products. It was founded in 1904 by George M. Brown in East St. Louis, Illinois, as the General Roofing Manufacturing Company, and is today a wholly owned subsidiary of the French materials group Saint-Gobain.\n\n## History\n\nThe company started with USD 25,000 in capital and made roofing products from the outset. In 1917 it was reorganised, incorporated and renamed Certain-teed Products Corporation; it was listed on the New York Stock Exchange the following year. Over the twentieth century the business expanded from roofing into other building materials. It phased asbestos out of its products around 1990.\n\nCertainTeed is now a wholly owned subsidiary of Saint-Gobain and forms part of that group's construction-products activities in North America. In 1989 CertainTeed bought the US clay tile maker Ludowici, whose management later passed to another Saint-Gobain company, Terreal.\n\n## Roofing products\n\nCertainTeed's residential roofing range is based on asphalt shingles, including laminated designer lines, along with underlayments, ventilation and accessories. It also produces commercial low-slope roofing products. Its fibreglass shingle lines have been sold in the US and Canada under brand names such as Landmark.\n\n## Litigation\n\nLike several older North American roofing companies, CertainTeed has faced product litigation. A class-action settlement covering certain organic-mat shingles, which the company stopped manufacturing in 2005, was approved in 2010. Asbestos liabilities associated with a predecessor business were placed into a separate entity that filed for bankruptcy protection in January 2020. Its products are sold in both the United States and Canada.","key_facts":[{"label":"Founded","value":"1904, East St. Louis, Illinois"},{"label":"Original name","value":"General Roofing Manufacturing Company"},{"label":"Parent","value":"Saint-Gobain"},{"label":"Products","value":"Roofing, siding, insulation, gypsum, ceilings"}],"regions":["North America"],"aliases":["Certain-teed Products Corporation","General Roofing Manufacturing Company"],"related":["saint-gobain","asphalt-shingle","ludowici","owens-corning","gaf"],"company":{"founded":"1904","website":"https://www.certainteed.com","parent":"Saint-Gobain","known_for":["Asphalt shingles","Vinyl siding","Insulation"]},"sources":[{"title":"CertainTeed","url":"https://en.wikipedia.org/wiki/CertainTeed","publisher":"Wikipedia"},{"title":"History","url":"https://certainteed.com/about-us/history","publisher":"CertainTeed"}],"country":null},{"slug":"chaitya-vault","title":"Chaitya Vault","category":"history","type":"term","summary":"The chaitya vault is the ribbed barrel-vaulted ceiling of ancient Indian Buddhist prayer halls, carved in rock to copy lost roofs of timber and thatch.","body":"A **chaitya vault** is the tall, round-topped ceiling of a *chaitya* hall, the Buddhist prayer hall of ancient India that holds a stupa at its far end. Almost every surviving example is cut into living rock in the hills of western India. Its main interest for roofing history is that it is a fossil of a vanished roof: carvers in stone copied, rib for rib, the bent timber and thatch roofs of free-standing halls that have not survived.\n\n## A roof copied in stone\n\nScholars agree that the form follows earlier halls built of wood and plant materials, none of which survive. The ceiling is a barrel vault, often slightly stilted so that it is taller than a true half-circle, with curved ribs running across it like the rafters of a timber roof. In the earliest halls real wooden ribs were fixed to the underside of the stone vault even though they carry no load; in later halls the ribs were carved from the rock itself. The front of the hall carries a large horseshoe-shaped window, the **chaitya arch** (also called *gavaksha* or *chandrashala*), which echoes the curved end of the roof and became one of the most repeated ornaments in Indian architecture.\n\nWriters have long noted a broad likeness between the chaitya profile and the arched wicker roofs of the huts of the Toda people of the Nilgiri hills, and with the pointed, ridged barrel roofs of 4th-century BCE Lycian tombs in Anatolia.\n\n## Key examples\n\n- **Barabar Caves, Bihar** (3rd century BCE, reign of Ashoka): the Lomas Rishi and Sudama caves are the earliest surviving spaces comparable to a chaitya hall.\n- **Bhaja, Maharashtra** (2nd century BCE): possibly the earliest surviving chaitya hall, with a barrel-vaulted ceiling into which ancient wooden ribs are set.\n- **Karla, Maharashtra** (about 50-70 CE, dated by donor inscriptions): the Great Chaitya is about 45 m (148 ft) long and up to about 14 m (46 ft) high. Its vault is lined with wooden ribs that are probably as old as the excavation, which would make them roughly 1,900 to 2,000 years old. A wooden umbrella over the stupa and a wooden frame inside the great arched window also survive.\n- **Kanheri Cave 3, near Mumbai**: much of the timber in the roof is original, with some pieces replaced in the British period.\n- **Ajanta, Maharashtra**: the later chaitya halls, such as Cave 19 (about 475-500 CE), repeat the chaitya arch many times on their facades.\n- **Ellora Cave 10, Maharashtra** (first half of the 7th century): generally regarded as the last rock-cut chaitya hall.\n\n## Why it matters\n\nBecause timber and thatch decay, the rock-cut halls are the best evidence of how large public roofs were framed in India before about the 3rd century CE. They show curved rafters, a ridge and gable-end arches already in use more than two thousand years ago.","key_facts":[{"label":"Earliest comparable spaces","value":"Barabar Caves, 3rd century BCE"},{"label":"Early chaitya hall","value":"Bhaja, 2nd century BCE, with wooden ribs"},{"label":"Largest example","value":"Karla Great Chaitya, c. 50-70 CE"},{"label":"Karla dimensions","value":"About 45 m (148 ft) long, 14 m (46 ft) high"},{"label":"Last rock-cut example","value":"Ellora Cave 10, 7th century"}],"regions":["South Asia"],"aliases":["chaitya hall roof","chaitya arch","gavaksha","chandrashala","rock-cut barrel vault"],"related":["barrel-vault-roof","roofing-in-india","thatch","history-of-timber-roof-framing","bangla-roof"],"company":null,"sources":[{"title":"Karla Caves","url":"https://en.wikipedia.org/wiki/Karla_Caves","publisher":"Wikipedia"},{"title":"Chaitya","url":"https://en.wikipedia.org/wiki/Chaitya","publisher":"Wikipedia"}],"country":null},{"slug":"chalk-line","title":"Chalk Line","category":"tools-equipment","type":"term","summary":"A reel of string coated in powdered chalk that is stretched and snapped to mark long straight lines for laying shingle courses, battens and panels.","body":"A chalk line is one of the simplest and oldest layout tools in construction. It consists of a string wound on a reel inside a case filled with powdered chalk. When the string is pulled out it picks up a coating of chalk; stretched taut between two points and plucked, it snaps against the surface and leaves a straight line. Chalk lines are mentioned in Homer's *Iliad* and were used in ancient Egypt, and East Asian carpenters use a related ink line, known in Japan as the *sumitsubo*.\n\n## Uses in roofing\n\n- **Shingle courses**: snapping horizontal lines across the deck keeps courses straight and exposure consistent, compensating for uneven eaves or decks.\n- **Vertical offset lines**: lines up the slope set the stagger (offset) pattern for shingle joints.\n- **Starter courses and eave lines**, especially where the eave is not straight.\n- **Battens and counter-battens** for tile and slate roofs, marked at the correct gauge (spacing) for the tile or slate headlap.\n- **Metal panel layout**: square reference lines for the first panel and for panel spacing.\n- **Low-slope membranes**: alignment lines for rolls, fastener rows and insulation boards.\n- **Cut lines** on panels, boards and membranes.\n\n## Chalk colours\n\nChalk is sold in several colours. Blue and white chalks are generally used where marks should weather away, while red and other strong colours are often marketed as more permanent and can stain roofing materials and paint. Manufacturers also sell weather-resistant and fluorescent formulations. Choosing a colour that will not permanently mark visible surfaces matters on finished roofs, metal panels and light-coloured membranes.\n\n## Technique\n\nMeasure and mark both ends of the line, hook or hold one end, pull the line taut, lift it straight up from the surface in the middle and release it. On long runs or windy days, a helper holds the centre and snaps each half. Lines snapped on wet surfaces may smear, and lines on very steep roofs may need to be refreshed as work progresses. A tape measure, square and pencil complete the basic layout kit.","key_facts":[{"label":"Components","value":"Reel, string, chalk-filled case"},{"label":"Main roofing uses","value":"Shingle courses, offsets, batten gauge, panel layout"},{"label":"Colour caution","value":"Some colours stain permanently"}],"regions":["Global"],"aliases":["chalk box","chalk reel","snap line"],"related":["pitch-gauge","asphalt-shingle","slaters-hammer","hook-blade-utility-knife","roofing-hatchet"],"company":null,"sources":[{"title":"Chalk line","url":"https://en.wikipedia.org/wiki/Chalk_line","publisher":"Wikipedia"},{"title":"Roofers' slate tools","url":"https://www.cupapizarras.com/uk/news/roofers-slate-tools/","publisher":"Cupa Pizarras"},{"title":"Slate roofing and repair techniques","url":"https://www.finehomebuilding.com/project-guides/roofing/slate-roofing-and-repair-techniques","publisher":"Fine Homebuilding"}],"country":null},{"slug":"chandal-roof","title":"Chandal Roof","category":"world-roofing","type":"term","regions":["Middle East"],"company":null,"summary":"Traditional Gulf flat roof of imported mangrove poles (chandal, danshil) overlaid with bamboo, palm or reed mats and clay.","aliases":["danshil roof","danchal","chandal","mangrove pole roof","Gulf traditional ceiling"],"body":"The chandal roof is the classic flat roof of the traditional coral-stone and mud houses, forts and mosques of the Gulf coast, from Kuwait and Bahrain to Qatar and the UAE. Its name comes from the mangrove poles (variously written *chandal*, *danchal* or *danshil*) that form its beams. Because timber long enough for beams did not grow locally, these poles were imported by sea, mostly from East Africa.\n\n## Layers\n\nWriting on Qatar describes the roof as built up in layers:\n\n1. **Beams:** *danshil* poles spanning between the walls. They were valued for their resistance to weather and were also used for lintels and connectors, often painted in bright colours.\n2. **Mat layer:** mangrove mats, split bamboo (*baszhil*, imported from India and East Africa) or palm mats laid across the poles. Palm fronds (*duun*) could be used interchangeably.\n3. **Earth:** a covering of clay over the matting, finished to shed rain. Clay was vulnerable to rain, so roofs needed regular maintenance.\n\nDried palm trunks were also used as beams, but they carry less load than mangrove, so they were combined with other materials. Because each room had to be spanned by a single run of poles, pole length set a practical limit on room width.\n\n## Walls beneath\n\nThe roofs sat on walls of rough stone bound with clay, later with gypsum mortar, or on coral-stone slabs; in Qatar coral slabs of about 70 x 50 x 7 cm (28 x 20 x 3 in) were used for walls, niches and lintels. Gypsum plaster protected limestone walls from moisture.\n\n## Decorated ceilings\n\nSeen from below, the poles and mats form the ceiling, and in majlis rooms they were often painted with geometric patterns. In Oman, roofs of houses, mosques and forts were built from palm logs or from local or imported wood, including teak from India and East Africa chosen for its resistance to termites. Omani ceiling logs were commonly painted dark brown or red with white patterns and sometimes carry the builder's name, the date or Qur'anic verses; Jabreen Castle near Bahla, built in the late 17th century, has notable painted ceilings.\n\n## Today\n\nRestorations in Qatar, such as the 2022 work at Ar Rakiyat Fort, have rebuilt wooden ceilings with traditional materials. Elsewhere such roofs have largely given way to reinforced concrete slabs.","key_facts":[{"label":"Beams","value":"Imported mangrove poles (chandal / danshil)"},{"label":"Mat layer","value":"Bamboo, mangrove or palm mats"},{"label":"Finish","value":"Clay"},{"label":"Timber origin","value":"Mainly East Africa; bamboo also from India"}],"related":["barasti","flat-roof","mud-roof","roofing-in-qatar","roofing-in-bahrain","roofing-in-kuwait","roofing-in-oman","roofing-in-the-united-arab-emirates"],"sources":[{"title":"Architecture of Qatar","url":"https://en.wikipedia.org/wiki/Architecture_of_Qatar","publisher":"Wikipedia"},{"title":"Historical ceilings seek support","url":"https://www.omanobserver.om/ampArticle/57928","publisher":"Oman Observer"},{"title":"Architecture of the United Arab Emirates","url":"https://en.wikipedia.org/wiki/Architecture_of_the_United_Arab_Emirates","publisher":"Wikipedia"}],"country":null},{"slug":"chattel-house","title":"Chattel House","type":"article","summary":"Small, movable timber house of Barbados with a steep roof, set on loose coral-stone blocks; a symbol of post-emancipation Caribbean housing.","body":"A chattel house is a small, portable timber house associated above all with Barbados. The name reflects its legal status as *chattel*, movable property, rather than real estate. Chattel houses are usually rectangular, often of two rooms, and are covered by a steep roof that is the building's main defence against tropical rain and wind.\n\n## Origins\n\nThe type dates from the plantation era. After emancipation, the Located Labourers Act of 1840 allowed formerly enslaved people to build on marginal plantation land for low rent, but landowners could evict tenants at short notice. Houses therefore had to be movable. They were built entirely of timber and set on loose coral-stone blocks or a ground sill rather than fixed foundations, so they could be dismantled and carried to a new site, historically by ox cart and later by truck.\n\n## Roof\n\nThe roof is steep so that it deflects wind and sheds heavy rain quickly. Roof styles evolved over time from hipped roofs and steep double-pitched gables toward flatter roofs with minimal slope. Corrugated iron became a common roof covering. As families prospered, houses were often extended by adding a second unit behind the first, each with its own roof, producing the characteristic sequence of parallel roofs seen in Barbadian villages.\n\n## Weather\n\nShutters were reinforced and layouts chosen to reduce wind damage. Barbados lies at the southern edge of the main Atlantic hurricane track and is struck less often than islands further north, but tropical storms and strong trade winds still shape building practice. The light frame was also designed to survive being moved with little damage.\n\n## Related Caribbean houses\n\nSmall timber houses with steep hip or gable roofs, raised on blocks or posts, are found throughout the Eastern Caribbean. In hurricane-prone islands, hip roofs are widely recommended because their four sloping sides perform better in high winds than tall gable ends.\n\n## Heritage\n\nChattel houses are now celebrated as part of Barbadian identity, and restored examples are used as shops and homes. Their numbers have declined as concrete-block houses have become the norm.","key_facts":[{"label":"Origin","value":"Barbados, post-emancipation (after 1840)"},{"label":"Structure","value":"Timber frame on loose coral blocks"},{"label":"Roof","value":"Steep hip or gable; often corrugated iron"},{"label":"Key feature","value":"Movable property, could be dismantled"}],"regions":["Latin America"],"aliases":["Barbados chattel house","Chattel home"],"related":["roofing-in-the-caribbean","hip-roof","corrugated-iron"],"sources":[{"title":"Chattel house","url":"https://en.wikipedia.org/wiki/Chattel_house","publisher":"Wikipedia"},{"title":"Architecture of Barbados","url":"https://en.wikipedia.org/wiki/Architecture_of_Barbados","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"chhatri","title":"Chhatri","category":"world-roofing","type":"term","summary":"A chhatri is a small domed pavilion raised on pillars, used in Rajput and Mughal architecture as a rooftop ornament and as a memorial canopy.","body":"A **chhatri** is an open pavilion in which a small dome or curved canopy is lifted on slender pillars. The word comes from Hindi *chatri*, \"umbrella\" or \"parasol\", and the shape does look like a stone umbrella. Chhatris are one of the most recognisable roof elements of northern and central India: rows of them break up the skyline of forts and palaces in Rajasthan, and larger ones stand alone as memorials over the cremation sites of rulers.\n\n## Form\n\nThe simplest chhatri is a single dome on four pillars set on a square platform. Larger examples are octagonal or round, rest on eight, twelve or more columns, and may group several domes together over a base containing rooms. Some imitate the curved Bengal (*bangla*) roof instead of a hemispherical dome; in Jaisalmer, chhatris of the 18th and 19th centuries use that drooping form. The twelve-pillar type with a corbelled ceiling, built up from overlapping stone courses rather than a true arch, borrows from the porches of Hindu temples in north-west India, used since at least the 11th century.\n\nBecause chhatris are mainly ornamental, they are built of the same stone as the building they crown: red or yellow sandstone, grey-blue stone, or white marble. Interiors may be carved or painted with frescoes.\n\n## Origins and spread\n\nChhatris began as canopies over tombs and memorials. The earliest known examples on the subcontinent are at the Shrine of Ibrahim at Bhadreswar in Gujarat, of the 12th-13th centuries. The form is most closely associated with Rajasthan and the Rajput courts, and was taken up in Mughal architecture, where chhatris surround the main domes of buildings such as Humayun's Tomb in Delhi and the Taj Mahal in Agra.\n\n## Roof ornament and memorial\n\nOn palaces and forts, chhatris are set along parapets and at the corners of roofs, giving shade to anyone on the roof terrace and making the skyline more varied. As memorials they mark the cremation places of royal families. Well-known groups include:\n\n- **Bada Bagh, Jaisalmer**: chhatris of Jai Singh II (d. 1743) and later rulers of Jaisalmer.\n- **Gaitore, Jaipur**: cenotaphs of the maharajas of Jaipur, including the carved chhatri of Jai Singh II.\n- **84 Khambhon ki Chhatri, Bundi** (1683): a memorial on 84 pillars.\n- **Malhar Rao Holkar's chhatri, Alampur** (1766), built by Ahilya Bai Holkar.\n- Memorial groups at Orchha, Shivpuri, Gwalior, Indore and Maheshwar built by local rulers, including the Scindia and Holkar families.\n\n## Roofing interest\n\nChhatris are roofs in their own right: the stone dome or canopy is both structure and weathering surface, with no separate covering of tiles, metal or thatch.","key_facts":[{"label":"Meaning","value":"Hindi chatri, umbrella or parasol"},{"label":"Form","value":"Dome or canopy on four or more pillars"},{"label":"Heartland","value":"Rajasthan and central India"},{"label":"Early examples","value":"Shrine of Ibrahim, Bhadreswar, 12th-13th century"},{"label":"Typical materials","value":"Sandstone and marble"}],"regions":["South Asia"],"aliases":["chattri","chhatris","cenotaph pavilion"],"related":["dome","bangla-roof","roofing-in-india","roofing-in-pakistan","middle-eastern-domes","pyramid-roof"],"company":null,"sources":[{"title":"Chhatri","url":"https://en.wikipedia.org/wiki/Chhatri","publisher":"Wikipedia"},{"title":"Bengal roofs","url":"https://en.wikipedia.org/wiki/Bengal_roofs","publisher":"Wikipedia"},{"title":"Eighty-four pillared cenotaph, Bundi","url":"https://incredibleindia.gov.in/en/rajasthan/bundi/eighty-four-pillared-cenotaph","publisher":"Incredible India (Ministry of Tourism, Government of India)"}],"country":null},{"slug":"chimney-cricket","title":"Chimney Cricket (Saddle)","category":"components","type":"term","summary":"A chimney cricket, or saddle, is a small ridged structure built on the uphill side of a chimney to divert water and debris around it.","body":"A cricket, also called a saddle, is a small, peaked sub-roof built on the uphill side of a chimney, skylight or other wide roof penetration. Without one, water running down the slope meets the flat back of the chimney and pools, along with leaves, snow and ice, against the most vulnerable flashing joint. The cricket splits the flow and sends it around both sides.\n\n## Code requirement\n\nUnder the US International Residential Code, section R903.2.2 (Crickets and Saddles), a cricket or saddle is required on the ridge side of any chimney or penetration more than 30 in (762 mm) wide, measured perpendicular to the slope. It may be covered with sheet metal or with the same material as the roof covering. Unit skylights installed and flashed to the manufacturer's instructions are an exception. Many builders install crickets on narrower chimneys as well.\n\n## Construction\n\nA cricket is typically framed from lumber and sheathed with plywood or OSB, forming a small gable whose ridge runs from the back of the chimney up to the main roof. Two short valleys run from the cricket ridge to the upper corners of the chimney. It is then lined with underlayment or self-adhered membrane, flashed into the chimney with counter-flashing, and either covered with metal or roofed over to match the main roof. Code guidance notes that on low slopes the cricket should be steeper than the field so it drains well.\n\n## Back gutters (UK)\n\nIn UK slating and tiling, the uphill side of a chimney is usually handled with a lead back gutter, a shallow lead tray that carries water to either side, rather than a framed cricket. Very wide chimneys may also get a timber-supported lead saddle.\n\n## Other uses\n\nThe term cricket is also used for tapered insulation or framing on low-slope roofs that diverts water toward drains and away from curbs, and for the central drainage ridge in some butterfly roofs.","key_facts":[{"label":"Required when (IRC)","value":"Penetration wider than 30 in (762 mm)"},{"label":"Code section","value":"IRC R903.2.2"},{"label":"UK counterpart","value":"Lead back gutter"}],"regions":["North America","Global"],"aliases":["saddle","chimney saddle","roof cricket"],"related":["chimney-flashing","roof-valley","counter-flashing","butterfly-roof"],"company":null,"sources":[{"title":"Chimney cricket (IRC 2024 R903.2.2)","url":"https://www.jaspector.com/codes/irc-2024/ch09-roof-assemblies/chimney-cricket-irc-2024/","publisher":"Jaspector"},{"title":"Chimneys & Crickets, Skylights, Pipes, Flues, Exhaust Vents & Solar","url":"https://open-exam-prep.com/study-guides/mi-roofing-contractor/flashings-penetrations/chimney-crickets-skylights-penetrations","publisher":"Open Exam Prep"},{"title":"Flashing","url":"https://hopkinsmn.com/616/Flashing","publisher":"City of Hopkins, Minnesota"}],"country":null},{"slug":"chimney-flashing","title":"Chimney Flashing","category":"components","type":"article","summary":"Chimney flashing is the combination of apron, step or soaker, counter and back flashings, sometimes with a cricket, that seals a chimney where it passes through a roof.","body":"A chimney that rises through a sloping roof interrupts the covering on all four sides, and each side faces water differently. Chimney flashing is therefore not a single part but a system of pieces, each suited to one face, combined so that water is lapped outward at every point.\n\n## The four faces\n\n- **Front (downhill) face:** an apron flashing laid over the roof covering and turned up the masonry.\n- **Sides:** step flashing (North America) or soakers (UK and Ireland) interleaved with each course, turned up the side of the chimney.\n- **Back (uphill) face:** a back pan or back gutter turned up the chimney and running under the covering above. On wider chimneys a cricket (saddle) is built here to divert water around the chimney.\n- **Counter-flashing:** on all sides, a cap or cover flashing let into the mortar joints and turned down over the base flashings.\n\n## Crickets\n\nThe US IRC (section R903.2.2) requires a cricket or saddle on the ridge side of any chimney or penetration more than 30 in (762 mm) wide measured perpendicular to the slope. It may be covered in sheet metal or the same material as the roof.\n\n## Masonry issues\n\nBrick and mortar absorb water, so even perfect flashings can be undermined by water soaking through the masonry above the roof. Chimney caps or crowns, and in some cases through-chimney flashing trays, address this. Mortar joints holding counter-flashings need to be maintained.\n\n## Common problems\n\n- Counter-flashings set only with sealant rather than into a reglet.\n- Missing or undersized crickets leading to debris and ponding behind the chimney.\n- Corrosion where dissimilar metals meet.\n- Old flashings reused on a new roof. Codes and good practice call for damaged or deteriorated flashings to be replaced when re-roofing.\n\n## UK practice\n\nIn Britain chimney flashings are typically formed in lead: a front apron, soakers with stepped cover flashings at the sides, and a back gutter at the top, with lead codes chosen for each piece.","key_facts":[{"label":"Components","value":"Apron, step/soakers, back gutter, counter-flashing"},{"label":"Cricket required (IRC)","value":"Chimney wider than 30 in (762 mm)"},{"label":"Code section","value":"IRC R903.2.2"}],"regions":["Global"],"aliases":["chimney flashings","chimney lead work"],"related":["chimney-cricket","apron-flashing","step-flashing","counter-flashing","lead-soakers"],"company":null,"sources":[{"title":"Chimney cricket (IRC 2024 R903.2.2)","url":"https://www.jaspector.com/codes/irc-2024/ch09-roof-assemblies/chimney-cricket-irc-2024/","publisher":"Jaspector"},{"title":"Chimneys & Crickets, Skylights, Pipes, Flues, Exhaust Vents & Solar","url":"https://open-exam-prep.com/study-guides/mi-roofing-contractor/flashings-penetrations/chimney-crickets-skylights-penetrations","publisher":"Open Exam Prep"},{"title":"Flashing (weatherproofing)","url":"https://en.wikipedia.org/wiki/Flashing_(weatherproofing)","publisher":"Wikipedia"},{"title":"Flashing","url":"https://hopkinsmn.com/616/Flashing","publisher":"City of Hopkins, Minnesota"}],"country":null},{"slug":"chimney-flashing-installation","title":"Chimney Flashing Installation","category":"installation","type":"article","summary":"Chimney flashing combines apron, step, cricket and counterflashing to seal the gap between a masonry chimney and the roof.","body":"A masonry chimney passing through a roof needs a multi-part flashing because the chimney and roof frame move independently and water arrives from several directions. The standard assembly has four parts: a front **apron**, **step** (base) flashings along the sides, a **back pan** or **cricket** at the upslope side, and **counterflashing** let into the masonry and lapping over everything else.\n\n## Components\n\n- **Apron flashing.** Laid over the shingles on the downslope face and turned up the chimney.\n- **Step flashing.** One piece per course along each side, woven into the shingles. Canadian guidance specifies pieces 75 mm (3 in) longer than the shingle exposure, with 100 mm (4 in) legs on roof and chimney.\n- **Back flashing or cricket.** On the upslope side, a pan or a small ridged structure diverts water around the chimney.\n- **Counterflashing.** Metal let at least 25 mm (1 in) into the mortar joints, extending at least 150 mm (6 in) down the masonry and lapping the base flashing by at least 50 mm (2 in).\n\n## Cricket (saddle)\n\nA **cricket** prevents water and snow from piling up behind a wide chimney. Canadian guidance recommends one where the chimney is 600 mm (24 in) or more wide. It is framed from wood sheathing fastened to the deck, built to the same pitch as the main roof and covered in sealed sheet metal, with its lower edge about 100 mm (4 in) wide to form a water trough.\n\n## Sequence\n\n1. Install underlayment, turning it up the chimney sides.\n2. Fit the apron at the front after shingling up to the chimney.\n3. Weave step flashings into each course up both sides.\n4. Build and flash the cricket or back pan at the top.\n5. Cut a reglet into the mortar joints and fit counterflashing, sealing the joint.\n\n## Common problems\n\nSealant smeared over a joint instead of a proper counterflashing, missing crickets, and step flashings nailed into the masonry are frequent causes of chimney leaks. In the UK and Europe, lead is the traditional material, using lead soakers, stepped cover flashings and a back gutter.","key_facts":[{"label":"Cricket recommended (Canada)","value":"Chimney 600 mm (24 in) wide or more"},{"label":"Counterflashing embed","value":"At least 25 mm (1 in) into masonry"},{"label":"Counterflashing lap over base","value":"At least 50 mm (2 in)"}],"regions":["Global"],"aliases":["chimney flashing","counter flashing","chimney cricket"],"related":["step-flashing-installation","counter-flashing","roof-flashing"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.4.1 Intersection of Shingle Roofing and Masonry","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-1-intersection-of-shingle-roofing-and-masonry/","publisher":"Canadian Roofing Contractors Association"},{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"}],"country":null},{"slug":"china-roofing-codes","title":"China Roofing Codes (GB 50345 and GB 55030)","summary":"China's main roofing codes are GB 50345-2012, the technical code for roof engineering, and GB 55030-2022, a mandatory general code for building waterproofing.","body":"Roofing in mainland China is governed by national standards with the prefix **GB** (guobiao, \"national standard\"). Two are central for roofs.\n\n## GB 50345-2012: Technical code for roof engineering\n\nGB 50345-2012, *Technical Code for Roof Engineering*, was approved on 28 May 2012 and implemented on 1 October 2012. It was issued by the Ministry of Housing and Urban-Rural Development (MOHURD) together with the then General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ). It applies to the design and construction of roof engineering for buildings. Appendices list standards and key performance indexes for waterproofing and thermal insulation materials.\n\nThe code covers roof types common in China, including:\n\n- flat (low-slope) roofs with membrane or coating waterproofing, often with protective layers or tiles above\n- tiled pitched roofs\n- metal panel roofs\n- planted (green) roofs\n\nIt also addresses thermal insulation layers, drainage, details at parapets and penetrations, and construction quality.\n\n## GB 55030-2022: General code for building and municipal waterproofing\n\nGB 55030-2022, *General code for waterproofing of building and municipal engineering*, was issued on 27 September 2022 by MOHURD and the State Administration for Market Regulation and took effect on **1 April 2023**. It is one of China's newer \"general codes\" (the GB 55xxx series), which contain compulsory provisions: the code states that waterproofing works must comply with it.\n\nFor roofs, it sets out:\n\n- a minimum **waterproofing design working life of 20 years** for roof projects\n- **three waterproofing grades** (I, II and III) based on the type of project and its environment\n- a requirement that planted roofs be Grade I, with at least one root-resistant waterproof layer and a protective layer\n- minimum thicknesses for single-layer exposed membranes (such as PVC, TPO or EPDM) on metal roof decks of 1.8 mm, 1.5 mm and 1.2 mm (about 0.071, 0.059 and 0.047 in) for Grades I, II and III\n- treatment of fully welded sheet metal roofing as a Grade I waterproofing method\n\nGutters and enclosed balconies must match the waterproofing grade of the main roof.\n\n## Effect on the market\n\nGB 55030 raised minimum requirements compared with earlier practice, increasing the number of waterproof layers or their thickness on many projects. Where GB 50345 and GB 55030 differ, the general code's compulsory provisions take precedence, and related technical codes are being revised to align with it.\n\n## Other relevant standards\n\nLoads on roofs, including wind and snow, are set by the national load code for building structures. Product standards for membranes, coatings, tiles and metal sheets are issued as GB or GB/T (recommended) standards and as industry standards (JC, JG).","key_facts":[{"label":"Roof engineering code","value":"GB 50345-2012 (in force 1 October 2012)"},{"label":"Waterproofing general code","value":"GB 55030-2022 (in force 1 April 2023)"},{"label":"Issuing ministry","value":"MOHURD (with AQSIQ / SAMR)"},{"label":"Roof waterproofing design life","value":"At least 20 years"},{"label":"Waterproofing grades","value":"I, II, III"}],"regions":["East Asia"],"aliases":["GB 50345","GB 50345-2012","GB 55030","GB 55030-2022","Chinese roofing standard"],"related":["green-roof","metal-roofing","single-ply-roofing"],"sources":[{"title":"GB 50345-2012 Technical code for roof engineering","url":"https://www.chinesestandard.net/PDF.aspx/GB50345-2012","publisher":"ChineseStandard.net"},{"title":"GB 55030-2022 General code for waterproofing of building and municipal engineering","url":"https://www.chinesestandard.net/PDF.aspx/GB55030-2022","publisher":"ChineseStandard.net"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"chinese-glazed-roof-tiles","title":"Chinese Glazed Roof Tiles","category":"history","type":"article","summary":"Glazed ceramic roof tiles in imperial yellow, green, blue and other colours, used on Chinese palaces and temples to signal rank.","body":"Glazed roof tiles are one of the most recognisable features of Chinese imperial architecture. They are fired clay tiles coated with a coloured glaze, giving roofs a hard, shining, water-shedding surface. In late imperial China their colour was not a matter of taste but of status.\n\n## Pan and cover tradition\n\nChinese tiled roofs use the same principle found at Qiaocun on the Loess Plateau around 2400-2200 BCE: concave pan tiles laid in rows, with convex or semi-cylindrical cover tiles over the joints. Over the following millennia this system was refined with decorated eave tiles, ridge tiles and ceramic ornaments. Glazing added colour and extra resistance to water.\n\n## Colour and hierarchy\n\nBy the Ming (1368-1644) and Qing (1644-1911) dynasties, imperial yellow glaze was reserved for the emperor. In the Forbidden City in Beijing, almost every roof carries yellow tiles. The palace itself shows how other colours carried meaning:\n\n- **Green** tiles roof the residences of the crown prince, linked with wood and growth.\n- **Black** tiles cover the imperial library, the Pavilion of Literary Profundity, because black was associated with water and therefore protection against fire.\n\nRules on colour, roof type and the number of ridge figures made a building's rank readable from a distance.\n\n## Ornament\n\nImperial roofs carry rows of glazed ceramic figures along the ridges. The number of figures shows the building's importance, with the Hall of Supreme Harmony carrying the most of any building in China. Large ridge-end ornaments and decorated round eave tiles complete the composition.\n\n## After the empire\n\nAfter the end of the empire in 1911, glazed tiles and ridge ornaments began to appear on commercial buildings and tourist structures, and they remain popular in Chinese-influenced architecture worldwide.","key_facts":[{"label":"Imperial colour","value":"Yellow, reserved for the emperor"},{"label":"Crown prince residences","value":"Green tiles"},{"label":"Imperial library","value":"Black tiles (associated with water)"}],"regions":["East Asia"],"aliases":["liuli tiles","imperial yellow tiles","Chinese glazed tiles"],"related":["forbidden-city-roofs","chinese-imperial-roof-figures","earliest-fired-clay-roof-tiles","history-of-japanese-kawara","korean-giwa-history"],"company":null,"sources":[{"title":"Forbidden City","url":"https://en.wikipedia.org/wiki/Forbidden_City","publisher":"Wikipedia"},{"title":"Imperial roof decoration","url":"https://en.wikipedia.org/wiki/Imperial_roof_decoration","publisher":"Wikipedia"},{"title":"Reconstructing the earliest known composite-tiled roofs from the Chinese Loess Plateau","url":"https://www.nature.com/articles/s41598-023-35299-x","publisher":"Scientific Reports (Nature Portfolio)"}],"country":null},{"slug":"chinese-imperial-roof-figures","title":"Chinese Imperial Roof Figures","category":"history","type":"term","summary":"Glazed ceramic statuettes marching along the ridges of Chinese imperial buildings; their number signalled the building's rank.","body":"Chinese imperial roof figures are small glazed ceramic statuettes set in a line along the hip ridges of palaces, government buildings and some temples. In Chinese they are called *zǒu shòu* or *yán shòu*, roughly \"walking beasts\" or \"eave beasts\". Only official buildings were allowed to use them.\n\n## The procession\n\nA typical line starts at the lower end of the ridge with a man riding a phoenix. Behind him walk a series of mythical animals, and the line ends with a dragon head fixed to the ridge, representing the authority of the state. Folklore explains the leading man in several ways. In one story he was an official hanged from the gable for treason, with the beasts poised to pounce if he misbehaved; in another he is an immortal riding a phoenix or *qilin*.\n\n## Rank by number\n\nThe number of figures reflected the importance of the building and the duties carried out inside. Counts are normally odd numbers, with three or five on minor buildings and nine as the usual maximum. The **Hall of Supreme Harmony** in the Forbidden City, the main throne hall, is the only building in China with ten: the nine standard beasts plus a unique figure called the *hangshi*, holding a sword.\n\n## Materials and colour\n\nThe figures are glazed fired clay in the same colours as the roof tiles. On imperial buildings they are yellow, the emperor's colour. Because they sit on the ridges of hip roofs, which are highly visible on Chinese buildings, they formed part of the building's public signal of status.\n\n## After 1911\n\nWhen the empire ended in 1911, the sumptuary rules lapsed. Roof figures have since appeared on restaurants, shops and tourist boats as decoration.\n\n## Meanings\n\nPopular accounts give fixed meanings and protective powers for each animal, but these traditions vary between sources and regions.","key_facts":[{"label":"Usual maximum","value":"Nine figures"},{"label":"Exception","value":"Hall of Supreme Harmony: ten, including the hangshi"},{"label":"Material","value":"Glazed fired clay"}],"regions":["East Asia"],"aliases":["roof beasts","zoushou","yanshou","imperial roof decoration"],"related":["forbidden-city-roofs","chinese-glazed-roof-tiles"],"company":null,"sources":[{"title":"Imperial roof decoration","url":"https://en.wikipedia.org/wiki/Imperial_roof_decoration","publisher":"Wikipedia"},{"title":"Forbidden City","url":"https://en.wikipedia.org/wiki/Forbidden_City","publisher":"Wikipedia"}],"country":null},{"slug":"chiwen","title":"Chiwen","category":"history","type":"term","summary":"Chiwen are dragon-like ornaments at the ends of Chinese roof ridges, descended from the Han-period chiwei and believed to protect buildings from fire.","body":"*Chiwen* (蚩吻 or 鸱吻) are large ornaments placed at each end of the main ridge of traditional Chinese buildings. They usually take the form of a dragon- or fish-like creature whose open mouth appears to swallow the ridge. In mythology the chiwen is one of the nine sons of the dragon. The ornaments are sometimes compared to Western gargoyles, but they do not carry water and are unrelated in origin.\n\n## From chiwei to chiwen\n\nThe ornament began as the *chiwei* (鸱尾, \"owl's tail\" or \"kite's tail\"), a wing- or tail-shaped ridge end associated with the vermilion bird. The earliest images appear in the Han dynasty, on ceramic architectural models, gate towers and tomb murals. Chiwei spread to palaces, temples and official buildings in the following centuries and to aristocratic houses under the Tang.\n\nGlazed roof tiles appeared in the Tang dynasty, and chiwei were often glazed green or blue, as seen in murals at the Mogao Grottoes. In the mid-Tang a fish-like *chiwen* became popular alongside the chiwei, and in the Song dynasty it replaced the older form completely, becoming more dragon-like while keeping some bird features such as wings. The Song building manual *Yingzao Fashi* (1103) standardised the terms, parts and sizes of the ornament. Under the Ming and Qing chiwen became more ornate, with bodies and tails curling inward and many regional variations in style and colour.\n\n## Meaning\n\nChiwen were believed to guard buildings against fire. A Tang-period text states that they were placed on Han roofs for this purpose, and later geomantic beliefs extended this protection to floods and typhoons. A Ming text describes them as swallowing evil influences at the ridge ends. In practice, the heavy ornaments also help weigh down and seal the junction of ridge and roof slope.\n\n## Surviving examples\n\nExamples range from the Liao-period chiwen of Shanhua Temple and Huayan Temple in Datong to green-glazed Song examples at Longxing Temple in Zhengding, and Ming and Qing ornaments on temples and palaces across China, including the Forbidden City.\n\n## Related ornaments elsewhere\n\nIn Japan the ridge-end tile is called *shibi* (鴟尾), and the mythical fish *shachihoko*, famously gilded on Nagoya Castle, was likewise believed to protect against fire. In Korea the equivalent owl-tail ridge-end tile is called *chimi*.","key_facts":[{"label":"Position","value":"Ends of the main roof ridge"},{"label":"Earliest form","value":"Chiwei, Han dynasty"},{"label":"Replaced chiwei","value":"Song dynasty"},{"label":"Belief","value":"Protection against fire"},{"label":"Japanese / Korean","value":"Shibi / chimi"}],"regions":["East Asia"],"aliases":["chiwei","ridge-end ornament","zhengwen","shibi","chimi"],"related":["chinese-imperial-roof-figures","chinese-glazed-roof-tiles","yingzao-fashi","roof-ridge","roofing-in-china","japanese-kawara-tile","korean-giwa-history"],"company":null,"sources":[{"title":"Chiwen","url":"https://en.wikipedia.org/wiki/Chiwen","publisher":"Wikipedia"},{"title":"Chinese glazed roof tile","url":"https://en.wikipedia.org/wiki/Chinese_glazed_roof_tile","publisher":"Wikipedia"},{"title":"Korean architecture","url":"https://en.wikipedia.org/wiki/Korean_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"choga","title":"Choga","category":"world-roofing","type":"term","summary":"Choga is the Korean thatched house and its rice-straw roof, renewed every one to three years and once the home of most Korean working people.","body":"*Choga* (초가, \"grass house\") is the traditional Korean house roofed with thatch, and by extension the thatched roof itself. It is one of the two main classes of traditional Korean housing, alongside the *giwa* house with its clay-tile roof. From prehistory until the mid-20th century choga was the typical home of farmers and working people across the peninsula.\n\n## Materials\n\nChoga houses were built of straw, timber and earth. **Rice straw** was the most common roofing material because it was cheap and abundant after the harvest; wheat straw or strong grasses could also be used. Walls were first of wattle and daub, sticks plastered with clay mixed with chopped straw, and later of rammed earth, which gave better thermal mass and earthquake resistance. The thatched roof was built much larger than the rooms beneath it, and gourds and pumpkins were sometimes grown on top.\n\n## Maintenance\n\nRice straw rots quickly in wet weather, so roofs were re-thatched every one to three years depending on the local climate, usually before the summer monsoon. Re-thatching was a community effort. At Nakan Eupseong in Suncheon, about 300 thatched houses are still re-roofed every year after the rice harvest, using thatch woven by hand by local artisans.\n\n## History\n\nChoga probably evolved from Neolithic dwellings dug into the ground and roofed with grass, which developed into earth-walled houses and then timber post-and-beam houses. Mumun-period pit houses had thatched roofs. Rice-straw thatching is associated with the spread of rice cultivation in the Three Kingdoms period, from which the earliest written mention of choga also dates.\n\n## Decline\n\nChoga began to disappear in the 1960s amid rapid industrialisation, housing shortages and standardised building methods. The **Saemaul Undong** (New Village Movement), launched in 1970, replaced thatched houses across the countryside with orange-tiled houses, and by the 1980s thatched roofs had largely been replaced by cement and slate, much of it asbestos-cement.\n\n## Regional variants\n\n- **Jeju chojip** - lower thatched houses built to withstand strong island winds, behind dry-stone walls (*chukdam*) through which the wind can pass.\n\n## Preservation\n\nThatched houses survive in Hahoe and Yangdong folk villages (UNESCO World Heritage), at Nakan Eupseong, in the Korean Folk Village replica settlement and in protected heritage houses.","key_facts":[{"label":"Meaning","value":"Grass house"},{"label":"Main material","value":"Rice straw"},{"label":"Re-thatching","value":"Every 1-3 years"},{"label":"Decline","value":"1960s-1980s, Saemaul Undong"},{"label":"Surviving examples","value":"Hahoe, Yangdong, Nakan Eupseong"}],"regions":["East Asia"],"aliases":["choga-jip","chogajip","Korean thatch","chojip"],"related":["hanok-roof","thatch","kayabuki","roofing-in-south-korea","roofing-in-north-korea","korean-asbestos-slate-roofs","korean-giwa-history"],"company":null,"sources":[{"title":"Choga (architecture)","url":"https://en.wikipedia.org/wiki/Choga_(architecture)","publisher":"Wikipedia"},{"title":"Hanok","url":"https://en.wikipedia.org/wiki/Hanok","publisher":"Wikipedia"},{"title":"Korean architecture","url":"https://en.wikipedia.org/wiki/Korean_architecture","publisher":"Wikipedia"},{"title":"Saemaul Undong","url":"https://en.wikipedia.org/wiki/Saemaul_Undong","publisher":"Wikipedia"},{"title":"Suncheon City to continue thatched roof repair at Nakan Eupseong","url":"https://www.asiae.co.kr/en/article/2025090416590339296","publisher":"Asia Economy"}],"country":null},{"slug":"church-of-the-nativity-roof","title":"Church of the Nativity Roof","category":"history","type":"place","regions":["Middle East"],"company":null,"summary":"The timber-trussed, lead-covered roof of the Church of the Nativity in Bethlehem, restored from 2013 after centuries of leaks.","aliases":["Nativity Church roof","Bethlehem basilica roof","Basilica of the Nativity roof"],"body":"The Church of the Nativity in Bethlehem, Palestine, stands over the site venerated as the birthplace of Jesus. Its basilica is roofed with timber trusses covered in lead sheet, and the condition of that roof shaped the building's recent history: rainwater was seeping into the church through the deteriorating roof.\n\n## Danger listing\n\nThe church and the Bethlehem pilgrimage route were inscribed on the World Heritage List in 2012 and placed on the List of World Heritage in Danger at the same time because of the poor state of the building. The roof had not received major repairs since 1480, in the Mamluk period.\n\n## Restoration from 2013\n\nWork began in 2013, initially with a private donation, after leaks through the deteriorating roof had become obvious. The Italian firm Piacenti carried out the work to UNESCO specifications following an international tender. Key roof measures reported by Arab News:\n\n- the whole roof was re-covered with about 1,625 m² (17,500 sq ft) of new lead sheet;\n- about 8% of the timber trusses were replaced with aged timber brought from Italy;\n- steel connectors were added to the trusses to improve resistance to earthquakes.\n\nThe programme went on to restore facades, mosaics and doors. In July 2019, at its meeting in Baku, the World Heritage Committee removed the site from the danger list, citing the quality of the work on the roof, facades, mosaics and doors.\n\n## Why it matters for roofing\n\nThe project illustrates the role of a heritage roof as the first line of defence for everything beneath it. Lead sheet on timber is a long-lived system (see lead-roofing and medieval-lead-roofs), but only if the laps, fixings and supporting timbers are maintained; once leaks start, damage spreads to structure and interior finishes. The approach taken, keeping most original trusses, replacing only failed members with matching timber and adding discreet seismic connections, reflects current conservation practice.","key_facts":[{"label":"Roof system","value":"Timber trusses with lead sheet"},{"label":"Previous major repair","value":"1480 (Mamluk period)"},{"label":"Restoration began","value":"2013"},{"label":"New lead","value":"About 1,625 m² (17,500 sq ft)"},{"label":"Removed from danger list","value":"July 2019"}],"related":["roofing-in-palestine","lead-roofing","medieval-lead-roofs","earthquake-roofing","roofing-in-israel"],"sources":[{"title":"Restoration of Bethlehem's Church of the Nativity uncovers long hidden treasures","url":"https://www.arabnews.com/node/1992436/amp","publisher":"Arab News"},{"title":"Bethlehem church removed from World Heritage in Danger list","url":"https://news.un.org/en/story/2019/07/1041742","publisher":"UN News"}],"country":null},{"slug":"churches-of-chiloe","title":"Churches of Chiloé","category":"history","type":"place","summary":"Wooden churches of Chile's Chiloé archipelago, clad in timber shingles; 16 are UNESCO World Heritage Sites inscribed in 2000.","body":"The Churches of Chiloé are timber churches built across the Chiloé archipelago of southern Chile, mainly in the 18th and 19th centuries. Sixteen of them were inscribed on the UNESCO World Heritage List in 2000 as the outstanding examples of what UNESCO calls the Chilota School of architecture. They are known for their tower façades and for exterior walls and towers clad in wooden shingles (*tejuelas*), a response to the archipelago's wet, windy oceanic climate.\n\n## History\n\nJesuit missionaries arrived in the archipelago in 1608 and ran a \"circular mission,\" travelling each year between communities. UNESCO records that about 70 churches were built under this system and that by the end of the 19th century more than 100 had been built, of which about 60 survive. Franciscans continued the tradition in the 18th and 19th centuries. The work combined Spanish religious architecture with the carpentry skills of the local Indigenous population.\n\n## Construction\n\nThe basic design has a tower rising from the main façade, a basilica plan and a vaulted timber ceiling. UNESCO notes that the forms and joinery of the towers and roof structures show the strong influence of local boat-building. Walls and towers are covered in hand-split wooden shingles (*tejuelas*), traditionally of native conifers such as alerce and cypress.\n\nCommunity labour, the *minga*, has been central to building and maintaining the churches.\n\n## Conservation\n\nThe churches are vulnerable. In March 2002 a storm brought down the tower of the church at Chonchi, showing that they were weaker than had been assumed. A national programme supported by the Inter-American Development Bank has run since 2003 and has reversed serious damage, especially to the tower façades. Suitable hardwoods are now scarce, and UNESCO notes research into alternatives with properties similar to the larch and cypress used originally, as well as treatments against weathering and wood-boring insects. The churches belong to the Diocese of Ancud and are National Monuments under Chile's Law 17.288 of 1970.\n\n## The sixteen churches\n\nAchao, Quinchao, Castro, Rilán, Nercón, Aldachildo, Ichuac, Detif, Vilupulli, Chonchi, Tenaún, Colo, San Juan, Dalcahue, Chellín and Caguach.","key_facts":[{"label":"Location","value":"Chiloé archipelago, Chile"},{"label":"Built","value":"Mainly 18th-19th centuries"},{"label":"Material","value":"Native timber, shingle cladding (tejuelas)"},{"label":"UNESCO","value":"16 churches, inscribed 2000"},{"label":"Mission start","value":"Jesuits, 1608"},{"label":"Conservation programme","value":"Since 2003"}],"regions":["Latin America"],"aliases":["Iglesias de Chiloé","Chilota School","Chiloé wooden churches"],"related":["tejuela","wood-shingle","roofing-in-chile","roofing-in-argentina-and-chile"],"company":null,"sources":[{"title":"Churches of Chiloé","url":"https://whc.unesco.org/en/list/971","publisher":"UNESCO World Heritage Centre"},{"title":"Churches of Chiloé","url":"https://en.wikipedia.org/wiki/Churches_of_Chilo%C3%A9","publisher":"Wikipedia"},{"title":"Tejuela artesanal (Conserva 20, 2015)","url":"https://www.cncr.gob.cl/sites/www.cncr.gob.cl/files/2023-01/Tejuela%20Artesanal.pdf","publisher":"Centro Nacional de Conservación y Restauración (Chile)"}],"country":null},{"slug":"class-a-fire-rating","title":"Class A Fire Rating","type":"standard","summary":"The highest fire classification for roof coverings under ASTM E108 and UL 790, for roofs effective against severe external fire exposure.","body":"A Class A fire rating is the highest of three fire classifications for roof coverings under the North American test standards ASTM E108 and UL 790 (which are technically similar). It indicates that a roof covering, as tested on a particular deck and underlayment, can withstand severe fire exposure from outside the building.\n\n## The classes\n\nASTM E108 defines three classes:\n\n- **Class A:** effective against severe fire test exposure; provides a high degree of protection to the roof deck.\n- **Class B:** effective against moderate exposure.\n- **Class C:** effective against light exposure.\n\nFor all three classes, the covering should not slip from position and is not expected to produce flying brands (burning pieces that could spread fire).\n\n## The tests\n\nASTM E108 includes several test methods, applied as required for the product type:\n\n1. **Intermittent flame exposure:** a gas flame is applied and removed repeatedly to see if the deck ignites.\n2. **Spread of flame:** measures how far flame travels across the roof surface.\n3. **Burning brand:** a burning wood block is placed on the roof to see whether it burns through to the deck.\n4. **Flying brand:** checks whether the covering produces burning debris.\n5. **Rain test:** for treated products, checks whether fire retardancy survives weathering.\n\n## Stand-alone versus by assembly\n\nSome materials, such as clay tile, concrete tile, slate and many metal roofs, are often described as Class A on their own because they are non-combustible. Others, including some asphalt shingles, treated wood shakes and some metal or composite products over a wood deck, achieve Class A only as an assembly with a specified underlayment or fire-resistant layer. The listing for each product states the conditions.\n\n## Use in codes\n\nBuilding codes in the United States require minimum roof classes in certain occupancies and in wildfire-prone areas; wildland-urban interface codes typically require Class A in the highest hazard zones. Wood shakes and shingles are restricted in many fire-prone jurisdictions unless treated and listed.\n\n## Other regions\n\nEurope has its own classification system for the external fire performance of roofs, and Australia addresses roofs in bushfire-prone areas through AS 3959. Ratings from different systems are not interchangeable.","key_facts":[{"label":"Standards","value":"ASTM E108, UL 790"},{"label":"Classes","value":"A (severe), B (moderate), C (light)"},{"label":"Key tests","value":"Intermittent flame, spread of flame, burning brand, flying brand, rain"}],"regions":["North America"],"aliases":["Class A roof","ASTM E108","UL 790","fire-rated roof"],"related":["wildfire-roofing","ember-resistant-roofing","bushfire-attack-level","wood-shake"],"sources":[{"title":"ASTM E108-20a Standard Test Methods for Fire Tests of Roof Coverings","url":"https://store.astm.org/e0108-20a.html","publisher":"ASTM International"},{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Wildland-urban interface","url":"https://en.wikipedia.org/wiki/Wildland%E2%80%93urban_interface","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"clay-and-concrete-tile-installation","title":"Clay and Concrete Tile Installation","category":"installation","type":"article","summary":"Tile installation hangs or fastens clay or concrete tiles over battens or decking, fixing them mechanically and, traditionally, bedding ridges and edges in mortar.","body":"Clay and concrete roof tiles are heavy, rigid units laid in overlapping courses. They are installed in two broad ways: **batten-hung**, where nibs on the back of each tile hook over horizontal timber battens, and **direct-to-deck**, where tiles are fastened to solid sheathing over underlayment. Batten-hung roofs are standard in the UK, Europe, Australia and much of Asia; both methods are used in North America.\n\n## Battens and counter-battens\n\nBattens set the gauge (spacing) of the courses and provide the fixing point. Counter-battens, running up the slope under the battens, raise them off the underlay so water and air can drain. Canadian guidance for one tile system specifies 25 x 100 mm (1 x 4 in) spruce battens, spaced in equal divisions of no more than 345 mm (13 3/4 in) from eave to ridge.\n\n## Fixing methods\n\n- **Mechanical fixing.** Nails, screws, wire ties or clips secure tiles to battens or deck.\n- **Mortar setting.** Traditional bedding of ridge, hip and verge tiles in sand and cement mortar, and in some regions of field tiles.\n- **Adhesive setting.** In some hurricane-prone markets, approved foam adhesives are used to set tiles to the underlayment in place of or in addition to fasteners.\n- **Clips.** Tail clips or storm clips hold the lower edge of each tile against uplift.\n\nFixing frequency depends on wind exposure and pitch. Canadian guidance for one system fastens every fourth row on slopes up to 5:12, every other row from 5:12 to 12:12 and every tile above 12:12, and calls for storm clips on buildings over 12.2 m (40 ft) high or where wind speeds exceed 130 km/h (80 mph).\n\n## UK practice\n\nIn the UK, BS 5534 requires single-lap tiles and ridge and hip tiles to be mechanically fixed, and says mortar can no longer be relied on as the only fixing. Perimeter tiles are fixed twice, and fixings are calculated from site wind loads.\n\n## Ridges and edges\n\nRidges and hips are finished with ridge tiles set on mortar or a dry-fix system. Verges can be mortar-pointed, finished with cloaked verge tiles or fitted with dry verge units. Eave closures or bird-stops fill the gap under the first course of profiled tiles.","key_facts":[{"label":"Batten spacing example (Canada)","value":"No more than 345 mm (13 3/4 in)"},{"label":"Storm clips (Canada)","value":"Over 12.2 m (40 ft) height or 130 km/h (80 mph) wind"},{"label":"UK standard","value":"BS 5534"}],"regions":["Global"],"aliases":["roof tiling","tile roof installation","concrete tile installation","clay tile installation"],"related":["tile-battens","bs-5534-fixing-specification","tile-clips","dry-fix-ridge-system","clay-roof-tile","concrete-roof-tile"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.3.3 Tile Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-3-tiles-clay-concrete-slate-metal/9-3-3-installation/","publisher":"Canadian Roofing Contractors Association"},{"title":"What are the fixing requirements of BS 5534?","url":"https://www.marley.co.uk/blog/what-are-the-fixing-requirements-of-bs-5534","publisher":"Marley"},{"title":"What is BS 5534?","url":"https://www.marley.co.uk/Blog/What-is-BS-5534","publisher":"Marley"}],"country":null},{"slug":"clay-roof-tile","title":"Clay Roof Tile","type":"article","summary":"A roofing unit moulded or extruded from clay and fired in a kiln; one of the oldest and most widespread roof coverings in the world.","body":"A clay roof tile is a unit of shaped clay that has been dried and fired in a kiln, then laid in overlapping rows on a pitched roof. Clay tiles have been made for nearly three thousand years and remain the predominant roof covering in much of southern Europe, Latin America, North Africa, the Middle East and parts of Asia. Where good clay is plentiful, tile production has often been tied to local brickworks.\n\n## History\n\nFired roof tiles appear to have developed independently in late Neolithic Greece and in China. Some of the earliest securely dated examples come from temples near Corinth, around 700-650 BC. The Greek and Roman system used flat tegulae with half-round imbrices over the joints, and Roman builders carried tile-making across their empire, including Britain after AD 43. In China the Song-dynasty building manual *Yingzao Fashi* standardised glazed tile manufacture. Mass-produced interlocking tiles appeared in France in the 1840s, and later spread worldwide, including through factories such as those at Mangalore in India.\n\n## Main families\n\n- **Flat or plain tiles**: small overlapping slabs hung or nailed at the head, laid double-lap like slates; includes the German beaver-tail (Biberschwanz).\n- **Two-piece curved tiles**: pan and cover, as in the Roman imbrex and tegula and the mission or \"monk and nun\" tile.\n- **One-piece curved tiles**: the pantile and the Spanish S-tile, which combine pan and cover.\n- **Interlocking tiles**: pressed tiles with side and head grooves, such as the French or Marseille tile.\n\n## Properties\n\n- **Durability**: high-quality clay tiles have a proven life of more than 100 years.\n- **Absorption**: depends on the clay and firing; some manufacturers achieve under 2% moisture absorption. Tiles for frost-prone regions must be fired close to vitrification.\n- **Colour**: comes from the clay itself (iron oxides give the familiar red) or from an engobe or glaze. Unlike concrete, fired colour does not fade significantly.\n- **Strength**: breaking loads for higher-grade tiles are reported in the range of about 700-1,500 lbf (3.1-6.7 kN).\n- **Weight**: clay tile is heavy compared with shingles, so roof framing must be designed for it.\n\n## Regional notes\n\nIn the United States, clay tile is most common in the South, Southwest and Florida, where it is valued for longevity and performance in hurricanes when properly fastened. Mission-style clay tile was first produced in California in 1780. On Java, about 90% of houses use clay tile. In the US and Canada, installation guidance is published by the Tile Roofing Industry Alliance, based in Seattle.\n\n## Maintenance\n\nClay tiles themselves rarely wear out; problems usually arise from broken tiles, failed underlayment, corroded fixings or deteriorated mortar at ridges and hips. Walking on tiles can crack them, so repairers use roof ladders or step only on the strongest points.\n","key_facts":[{"label":"Earliest dated examples","value":"c. 700-650 BC, near Corinth, Greece"},{"label":"Typical life","value":"Over 100 years for high-quality tiles"},{"label":"Main families","value":"Plain, two-piece curved, pantile/S-tile, interlocking"},{"label":"Colour","value":"From clay (iron oxide), engobe or glaze"}],"regions":["Global","Europe","Latin America","Middle East","East Asia","Southeast Asia","South Asia","North America"],"aliases":["terracotta tile","ceramic roof tile","clay tile"],"related":["pantile","spanish-tile","mission-tile","interlocking-clay-tile","plain-tile","beaver-tail-tile","glazed-roof-tile","imbrex-and-tegula","concrete-roof-tile","mangalore-tile","terracotta"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Roof","url":"https://en.wikipedia.org/wiki/Roof","publisher":"Wikipedia"},{"title":"Terracotta","url":"https://en.wikipedia.org/wiki/Terracotta","publisher":"Wikipedia"},{"title":"Tile Roofing Industry Alliance","url":"https://tileroofing.org/","publisher":"Tile Roofing Industry Alliance"}],"category":"materials","company":null,"country":null},{"slug":"climate-change-and-roofing","title":"Climate Change and Roofing","type":"article","summary":"How a warming climate is expected to change the hazards roofs face, from stronger storms and heavier rain to heat, wildfire and shifting snow.","body":"Roofs are designed for local climate, using historical records of wind, rain, snow and temperature. As the climate warms, some of those hazards are changing, which affects how roofs should be designed, built, maintained and insured. Roofs are also part of the response to climate change through cool roofs, green roofs, rooftop solar and lower-carbon materials.\n\n## Changing hazards\n\n- **Tropical cyclones.** NOAA's Geophysical Fluid Dynamics Laboratory summarizes projections for about 2 °C of global warming: tropical cyclone intensity rising about 1-10 percent globally, a greater proportion of storms reaching Category 4 and 5, and rainfall rates near the storm centre increasing about 14 percent. The IPCC rates these projected increases with high confidence, while the total number of storms may decrease or change little. Rising sea levels increase storm surge flooding.\n- **Heavy rain.** Higher rainfall intensity raises the demand on gutters, drains and overflows, and increases the importance of secondary drainage and detention.\n- **Heat.** Higher temperatures and longer heatwaves accelerate aging of asphalt and polymer roofing, raise cooling demand, and intensify urban heat islands, which the US EPA notes are expected to strengthen as cities grow.\n- **Wildfire.** Longer fire seasons and expanding development in the wildland-urban interface increase ember exposure for roofs. In the United States, the area burned by wildfires nearly doubled between 1985-1994 and 2005-2014.\n- **Hail and convective storms.** Hail remains a leading cause of US roof claims, with more than 5,000 major hail events recorded annually in 2024 and 2025; trends are an active research topic.\n- **Snow and ice.** Changing winters can bring heavier wet snow, rain-on-snow events and more freeze-thaw cycles in some regions, affecting snow loads and ice dams.\n\n## Design responses\n\n- Updating wind, rain and snow maps in codes to reflect current and projected climate;\n- Continuous load paths, sealed roof decks and stronger edges in high-wind regions;\n- Impact-rated and Class A fire-rated coverings where hail and wildfire risk is high;\n- Larger and redundant drainage;\n- Ember-resistant vents and details;\n- Better air sealing, insulation and ventilation in cold climates.\n\n## Mitigation roles of roofs\n\n- **Cool roofs** reduce cooling energy and urban heat.\n- **Green and blue roofs** retain stormwater and cool cities.\n- **Rooftop solar** generates renewable electricity.\n- **Lower embodied carbon** through durable, recyclable and lower-emission materials verified by Environmental Product Declarations.\n\n## Insurance and resilience\n\nRising losses from storms are reshaping insurance for roofs, with more attention to roof age, material, and mitigation programs such as FORTIFIED in the United States.","key_facts":[{"label":"Projected cyclone intensity change (~2 °C)","value":"About +1-10% globally (GFDL summary)"},{"label":"Projected cyclone rain rates","value":"About +14% near storm centre"},{"label":"US wildfire area burned","value":"Nearly doubled, 1985-1994 to 2005-2014"},{"label":"Roof roles in mitigation","value":"Cool, green and blue roofs; rooftop solar; low-carbon materials"}],"regions":["Global"],"aliases":["climate adaptation roofing","climate resilience roofs","roofs and climate change"],"related":["hurricane-roof-damage","hail-damage","wildfire-roofing","roof-drainage-design","cool-roof","green-roof","rooftop-solar-pv","embodied-carbon-roofing","urban-heat-island"],"sources":[{"title":"Global Warming and Hurricanes","url":"https://www.gfdl.noaa.gov/global-warming-and-hurricanes/","publisher":"NOAA Geophysical Fluid Dynamics Laboratory"},{"title":"Learn About Heat Islands","url":"https://www.epa.gov/heatislands/learn-about-heat-islands","publisher":"US Environmental Protection Agency"},{"title":"Wildland-urban interface","url":"https://en.wikipedia.org/wiki/Wildland%E2%80%93urban_interface","publisher":"Wikipedia"},{"title":"Facts + Statistics: Hail","url":"https://www.iii.org/fact-statistic/facts-statistics-hail","publisher":"Insurance Information Institute"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"coal-tar-pitch-roofing","title":"Coal-Tar Pitch Roofing","category":"low-slope-systems","type":"article","summary":"Built-up roofing that uses coal-tar pitch, a by-product of coking coal, as the bitumen, valued for slow ageing and limited to very low slopes.","body":"Coal-tar pitch roofing is a form of built-up roofing in which the waterproofing bitumen is coal-tar pitch rather than petroleum asphalt. Coal tar is produced by high-temperature carbonisation of bituminous coal, for example when making coke. Both materials are black and thermoplastic and both are melted in kettles, so they are often confused, but they behave differently.\n\n## Properties\n\nCompared with asphalt, coal-tar pitch has lower heat stability, a lower flash point and higher specific gravity. It stays slightly fluid at roof temperatures, which allows small cracks to \"self-heal\", and it resists water and oils well. These traits made it popular on dead-level roofs and on roofs exposed to standing water. Coal-tar BUR is normally surfaced with a flood coat and gravel to protect it from sunlight.\n\n## Slope limits\n\nBecause it flows, coal-tar pitch is limited to very flat roofs. The International Building Code permits coal-tar built-up roofs at a design slope as low as 1/8 in per 12 in (1%), half the 1/4:12 required for most other membranes. Industry guidance generally advises against using it above about 1/2 in per 12 in (4%), and many references limit it to 1/4:12 or less.\n\n## Materials\n\nCoal-tar systems traditionally use coal-tar-saturated organic felts. Glass-fibre felts are a poor match because their porosity does not suit coal tar. Type I coal-tar pitch, used since the late 1800s, is the traditional product; a lower-fuming Type III introduced in the 1980s has had reported performance problems.\n\n## Durability and decline\n\nWell-built coal-tar roofs have commonly lasted 50 to 70 years, and some over a century. Even so, asphalt largely replaced coal tar from the 1980s onward. Coal-tar pitch volatiles carry occupational health advisories, which complicate handling, and lower-fume cold-process coal-tar products have been developed. It remains in use mainly on specialised dead-level and reroofing projects.","key_facts":[{"label":"IBC minimum slope","value":"1/8:12 (1%)"},{"label":"Typical maximum slope","value":"About 1/4:12 to 1/2:12"},{"label":"Reported service life","value":"50-70 years common"},{"label":"Source","value":"By-product of coking bituminous coal"}],"regions":["North America"],"aliases":["coal tar roof","pitch and gravel roof","coal-tar BUR"],"related":["built-up-roofing","roofing-asphalt","gravel-surfaced-roof","ponding-water"],"company":null,"sources":[{"title":"Low-slope roofing systems: built-up roofs and modified bitumen","url":"https://buildingenclosureonline.com/articles/82366-low-slope-roofing-systems-built-up-roofs-and-modified-bitumen","publisher":"Building Enclosure"},{"title":"Built-Up Roofing (BUR): What It Is, Types, Issues & More","url":"https://roofonline.com/built-up-roofing-introduction/","publisher":"RoofOnline"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"Minn. R. 1305.1507 - Requirements for Roof Coverings (IBC Section 1507 amendments)","url":"https://www.law.cornell.edu/regulations/minnesota/Minn-R-1305-1507","publisher":"Cornell Law School LII"}],"country":null},{"slug":"coastal-corrosion","title":"Coastal Salt Corrosion","type":"article","summary":"Accelerated corrosion of metal roofing, fasteners and flashings caused by salt spray and humidity near the sea.","body":"Coastal salt corrosion is the faster deterioration of metal roof components near the ocean, where wind carries salt spray onshore. Salt deposits attract moisture and create a conductive film on metal surfaces, which speeds electrochemical corrosion. Corrosion is usually most severe close to the shoreline and on surfaces that are not rinsed by rain, such as the undersides of eaves and lapped joints.\n\n## Why salt matters\n\nChloride ions from sea salt can break down the thin protective (passive) oxide films that normally protect aluminium and stainless steel, leading to pitting and crevice corrosion in confined spaces such as under washers, laps and sealants. On galvanized or metallic-coated steel, the zinc or zinc-aluminium coating corrodes sacrificially to protect the steel, but the coating is consumed faster in marine air.\n\n## Galvanic corrosion\n\nWhen two different metals touch in the presence of an electrolyte such as salt water, the less noble metal corrodes faster. Corrosion guidance suggests that in harsh outdoor or salt-exposed conditions the difference in anodic index between metals in contact should be kept to about 0.15 V or less. Roofing examples include:\n\n- copper flashings or runoff onto galvanized steel or aluminium;\n- carbon-steel fasteners in aluminium or stainless sheet;\n- aluminium in contact with treated lumber or wet concrete.\n\nThe Statue of Liberty is a well-known example: its copper skin corroded the iron support frame after the insulation between them failed.\n\n## Material choices near the coast\n\n- **Aluminium** forms a self-healing oxide layer and is widely used in coastal roofing, with compatible fasteners.\n- **Copper** develops a stable patina but will corrode less noble metals it drains onto.\n- **Stainless steel** fasteners resist general corrosion, though chlorides can still cause pitting in some grades.\n- **Metallic-coated steel** (galvanized or zinc-aluminium) loses its sacrificial coating faster in marine air, so coating weight and paint systems matter; product warranties may restrict coastal use.\n- **Clay, concrete tile and slate** are not affected by salt corrosion, though their fasteners and flashings are.\n\n## Maintenance\n\nRinsing sheltered surfaces with fresh water, inspecting fasteners and cut edges, touching up damaged coatings, and avoiding dissimilar-metal contact all extend service life in coastal environments. Hurricane connectors and other structural steel near the coast also benefit from heavier galvanizing or stainless steel.","key_facts":[{"label":"Cause","value":"Chloride from sea salt plus moisture"},{"label":"Galvanic limit in harsh conditions","value":"About 0.15 V anodic index difference"},{"label":"Most affected areas","value":"Unwashed surfaces, laps, fasteners, cut edges"}],"regions":["Global"],"aliases":["marine corrosion","salt spray corrosion","coastal corrosion"],"related":["galvanic-corrosion","aluminum-roofing","copper-roofing","metal-roofing","hurricane-tie"],"sources":[{"title":"Corrosion","url":"https://en.wikipedia.org/wiki/Corrosion","publisher":"Wikipedia"},{"title":"Galvanic corrosion","url":"https://en.wikipedia.org/wiki/Galvanic_corrosion","publisher":"Wikipedia"},{"title":"Galvanization","url":"https://en.wikipedia.org/wiki/Galvanization","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"coil-coating","title":"Coil Coating","category":"installation","type":"term","summary":"Coil coating is the continuous factory process that cleans, pretreats, primes, paints and bakes metal strip before it is formed into roofing.","body":"Coil coating is how most painted metal roofing gets its colour. A coil of metallic-coated steel or aluminium strip is unrolled, run through a series of cleaning, treatment, painting and curing stations at high speed, and rewound as a prepainted coil ready for slitting and roll-forming. Because the paint is applied and cured under controlled conditions, the finish is far more uniform and durable than site painting.\n\n## Typical line sequence\n\n1. Uncoil the strip and stitch it to the end of the previous coil.\n2. Clean and brush the surface.\n3. Apply a chemical conversion pretreatment, then dry.\n4. Apply primer to one or both sides.\n5. Cure in an oven, typically for 15 to 60 seconds, then cool.\n6. Apply topcoat (and backer coat) and cure again.\n7. Cool and rewind.\n\nAccumulators at the entry and exit let the line keep running while coils are changed. Lines handle strip roughly 18 to 60 in (46 to 152 cm) wide at about 100 to 700 ft per minute (0.5 to 3.6 m/s). Steel coils can weigh around 25 tons.\n\n## Coatings applied\n\nPolyesters, PVDF, plastisols, polyurethanes and epoxies are all applied on coil lines, as are laminated plastic films. The coil stock itself usually already carries a metallic coating such as galvanizing or 55% aluminium-zinc from an upstream line.\n\n## History and industry\n\nThe process dates from the 1930s; the venetian blind industry was an early user. Output is several million tonnes a year in both North America and Europe. Industry bodies include the National Coil Coating Association (NCCA) in the United States and the European Coil Coating Association (ECCA). European prepainted steel is covered by EN 10169.\n\n## Why it matters for roofs\n\nThe quality of pretreatment and primer, and the type of topcoat, govern adhesion, edge corrosion and colour retention. Roll-forming after painting requires flexible coatings, so coil paints are formulated to survive bending without cracking.","key_facts":[{"label":"Process introduced","value":"1930s"},{"label":"Line speeds","value":"About 100-700 ft/min (0.5-3.6 m/s)"},{"label":"European standard","value":"EN 10169 (organic coated steel)"},{"label":"Industry bodies","value":"NCCA (US), ECCA (Europe)"}],"regions":["Global"],"aliases":["prepainting","coil painting","pre-painted metal","prepainted steel"],"related":["metal-roof-paint-systems","pvdf-coating","galvalume","colorbond-steel"],"company":null,"sources":[{"title":"Coil coating","url":"https://en.wikipedia.org/wiki/Coil_coating","publisher":"Wikipedia"},{"title":"National Coil Coating Association","url":"https://www.coilcoating.org/","publisher":"National Coil Coating Association"},{"title":"COLORBOND steel technology","url":"https://colorbond.com/why-colorbond-steel/technology","publisher":"BlueScope"}],"country":null},{"slug":"cold-roof","title":"Cold Roof","category":"components","type":"term","summary":"A cold roof is a pitched roof insulated at ceiling level, leaving a ventilated, unheated loft or attic space between the insulation and the roof covering.","body":"A cold roof is a roof construction in which the thermal insulation is placed at ceiling level, typically between and over the ceiling joists, so the roof space above stays at roughly outdoor temperature. The term is widely used in the UK and Europe; in North America the same arrangement is usually described simply as a vented attic.\n\n## How it handles moisture\n\nWarm, moist air from the house can leak or diffuse into the cold roof space. If it meets cold surfaces such as the underside of the roof covering, underlay or sheathing, it can condense, wetting timber and insulation. Cold roofs control this mainly by:\n\n- ventilating the loft or attic with outside air, through openings at the eaves and often at the ridge;\n- reducing air leakage from the house through the ceiling;\n- in some designs, using a vapour control layer at ceiling level.\n\nIn the UK, BS 5250 is the code of practice for managing moisture in buildings and sets out ventilation provisions for cold roofs, which depend on whether the underlay is high-resistance (HR) or low-resistance (LR). In the US, IRC section R806 sets minimum net free vent area for vented attics, generally 1/150 of the attic floor area, reducible to 1/300 under conditions such as balanced high and low ventilation.\n\n## Insulation at the eaves\n\nA clear path must be kept for air to flow from eaves vents into the roof space. Baffles or eaves trays prevent insulation from blocking the vents; the IRC requires at least 1 in (25 mm) of space between insulation and the roof sheathing at the vent.\n\n## Cold flat roofs\n\nThe term is also used for flat roofs with insulation between joists and a ventilated void above. Many authorities now discourage cold flat roofs because the void is hard to ventilate reliably, preferring warm roof designs.","key_facts":[{"label":"Insulation position","value":"Ceiling level"},{"label":"UK moisture code","value":"BS 5250"},{"label":"US attic vent ratio","value":"1/150, or 1/300 with conditions (IRC R806)"}],"regions":["Europe","North America","Oceania"],"aliases":["vented attic","ventilated roof","cold loft"],"related":["warm-roof","roof-ventilation","ridge-vent","vapour-permeable-underlay"],"company":null,"sources":[{"title":"Batten space ventilation for pitched roofs","url":"https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/LABCW%20Batten%20space%20ventilation%20for%20pitched%20roofs%20V2.pdf","publisher":"LABC Warranty"},{"title":"IRC R806 Roof Ventilation (code change proposal)","url":"https://iccsafe.org/wp-content/uploads/bcac/IRC-R806.pdf","publisher":"International Code Council"},{"title":"Attic-Ventilation Strategies","url":"https://finehomebuilding.com/project-guides/roofing/attic-ventilation-strategies","publisher":"Fine Homebuilding"}],"country":null},{"slug":"cold-weather-roofing","title":"Cold Weather Roofing","category":"installation","type":"article","summary":"Cold weather roofing covers the extra precautions needed below normal application temperatures, from warming materials to hand-sealing shingles.","body":"Roofing materials are designed to be installed within certain temperature ranges. In cold weather, asphalt shingles become stiff and brittle, factory sealant strips do not bond, adhesives cure slowly, self-adhered membranes lose tack and hot bitumen cools before it bonds. Roofing still continues through winter in many cold regions, but crews adjust materials, methods and scheduling.\n\n## Asphalt shingles\n\n- **Sealant activation.** Factory sealant strips rely on sun and warmth to bond. Shingles laid in cold weather may stay unsealed until warmer weather arrives and are vulnerable to wind in the meantime; manufacturers' instructions say when hand sealing is needed.\n- **Hand sealing.** Where shingles will not self-seal soon, dabs of asphalt plastic cement (ASTM D4586 or similar) are placed under each tab or along the lower edge of laminated shingles, in the size and number the manufacturer specifies. Too much cement causes blistering.\n- **Handling.** Store bundles in a warm place and bring them to the roof as needed. Bend ridge caps carefully; Canadian guidance suggests nailing one side first, then bending the cap over, and waiting for warmer weather or warming the caps if they still crack.\n- **Nailing.** Cold shingles crack more easily when nails are overdriven, so nailer pressure is checked.\n\n## Membranes and bitumen\n\nCanadian guidance notes that in cold weather bitumen may need heating close to its flash point to reach application temperature, but overheating degrades it; that felts must be fully bonded before the bitumen cools; and that each adhesive has temperature, humidity and wind limits that change drying and cure times. Modified bitumen rolls are stored in heated, dry space and brought up only as needed; torching is slower in cold, humid conditions.\n\n## Self-adhered products\n\nSelf-adhered underlayments and ice barriers have minimum application temperatures, and substrate temperature affects their bond. Some manufacturers require primers or heat guns in cold conditions.\n\n## Site practice\n\n- Remove frost, ice and snow from decks before roofing; decks must be dry.\n- Protect workers from cold stress and slippery surfaces.\n- Install temporary membranes or night seals at the end of every working day.\n- Schedule work around shorter daylight hours.","key_facts":[{"label":"Daily practice","value":"Night seals or temporary protection"},{"label":"Shingle sealing in cold weather","value":"May be delayed; hand sealing per manufacturer"}],"regions":["North America","Europe","East Asia","Arctic"],"aliases":["winter roofing","cold weather shingle installation"],"related":["hand-sealing-shingles","hot-weather-roofing","ice-barrier-installation","torch-applied-roofing"],"company":null,"sources":[{"title":"Shingle Application Mechanics: Starter Courses, Offsets, Fastener Placement and Wind Sealant Activation","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-application-mechanics","publisher":"Open Exam Prep"},{"title":"Canadian Roofing Reference Manual: 3.3.7 Cold Weather Material Application","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-3-roofing-preparation/3-3-cold-weather-conditions/3-3-7-material-application/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 9.4.5 Ridges","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-5-ridges/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 5.2.2 Application of Membrane","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-5-modified-bituminous-membranes/5-2-membrane-installation/5-2-2-application-of-membrane/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"cold-applied-roofing","title":"Cold-Applied Roofing","category":"low-slope-systems","type":"term","summary":"Roofing installed without heat, using adhesives, cold-process bitumen or liquid resins instead of torches or hot kettles.","body":"Cold-applied roofing covers any low-slope system installed without open flames or heated bitumen. The term is used for several different technologies:\n\n- **Cold-process built-up roofing:** felts laminated with solvent- or water-based asphalt adhesives that are sprayed, brushed or squeegeed.\n- **Cold-adhered modified bitumen:** SBS sheets set in cold adhesive, sometimes with special backings.\n- **Adhered single-ply:** membranes bonded with contact or water-based adhesives.\n- **Liquid-applied membranes:** polyurethane, PMMA, polyester, acrylic or silicone resins, often reinforced with fleece.\n\n## Advantages\n\nThe main advantage is safety: no kettles, no torches and fewer hot-work permits, which lowers fire risk and makes the work acceptable on occupied buildings such as schools, hospitals and housing. Cold adhesives also avoid asphalt fumes. In the UK, cold liquids are widely chosen for roofs, car parks, balconies and walkways where hot works are not allowed.\n\n## Limitations\n\nCold systems generally have stricter weather limits than hot systems. Solvent-based adhesives need time to flash off, water-based products need warm, dry conditions to cure, and rain on uncured material can spoil it. Coverage rates must be controlled; one simple site method is to mark the roof in grids matching the product's coverage rate so the right quantity goes on each area.\n\n## Reinforced cold liquids\n\nCold-applied reinforced liquid systems embed a polyester fleece in wet resin to form a seamless membrane. PMMA versions cure in under an hour even near freezing; polyurethane and polyester systems are also common. See liquid-applied roofing.\n\n## Health and occupancy\n\nBecause cold-applied systems avoid kettles and torches, they also avoid hot asphalt fumes, which NIOSH has identified as a potential occupational carcinogen. This makes them attractive for work on occupied buildings.","key_facts":[{"label":"Main benefit","value":"No open flame or hot bitumen"},{"label":"Typical uses","value":"Occupied buildings, balconies, walkways, refurbishment"},{"label":"Key limitation","value":"Weather-sensitive curing"}],"regions":["Global"],"aliases":["cold-process roofing","cold-applied membrane","flame-free roofing"],"related":["liquid-applied-roofing","pmma-roofing","built-up-roofing","sbs-modified-bitumen","fully-adhered-roof-system"],"company":null,"sources":[{"title":"Built-Up Roofing (BUR): What It Is, Types, Issues & More","url":"https://roofonline.com/built-up-roofing-introduction/","publisher":"RoofOnline"},{"title":"Low-slope roofing systems: built-up roofs and modified bitumen","url":"https://buildingenclosureonline.com/articles/82366-low-slope-roofing-systems-built-up-roofs-and-modified-bitumen","publisher":"Building Enclosure"},{"title":"BS 6229:2018 and flat roofing systems","url":"https://ikogroup.co.uk/?p=820","publisher":"IKO"},{"title":"Top tips to help you get the most out of your flat roof","url":"https://www.sigroofing.co.uk/?p=12082","publisher":"SIG Roofing"},{"title":"Why the need for PMMA","url":"https://rcimag.co.uk/sika-roofing-hub/why-the-need-for-pmma","publisher":"RCI Magazine / Sika"}],"country":null},{"slug":"collar-tie","title":"Collar Tie and Collar Beam","category":"components","type":"term","summary":"A collar is a horizontal member joining opposite rafters above their base; depending on position it either resists sag (collar beam) or spreading (collar tie).","body":"A collar is a horizontal timber fixed between a pair of opposing rafters somewhere above the wall plate. It is one of the oldest elements in roof carpentry, and in the language of builders it is usually called a collar tie, although historians and engineers draw a distinction between a collar acting as a beam and a collar acting as a tie.\n\n## How a collar works\n\n- **Collar beam:** when the collar sits part-way up the rafters, it is mostly pushed on (in compression) and props the rafters against sagging inward.\n- **Collar tie:** a collar is a true tie, pulled in tension and resisting the rafters spreading apart, mainly when it is positioned very high near the apex or low near the base of the rafters.\n\nIn modern codes and building practice, the member that resists the outward thrust of rafters near the bottom is often called a rafter tie or ceiling joist. Collar ties placed high in the roof are commonly used to help hold the roof together at the ridge against wind. Local codes specify the size, spacing and position of these members, so the details vary by jurisdiction.\n\n## Historic roofs\n\nIn the history of timber roofs, the simplest form is the common rafter roof: rafter pairs on a tie beam. Adding a collar produced the collar-beam roof, which carpentry historians describe as suitable for spans of up to about 4.5 m (15 ft). Crown-post roofs always include collars, which are carried by a central post rising from the tie beam. Arch-braced roofs add curved braces between the rafters and the collar.\n\n## Practical notes\n\nRemoving collars or ties during attic renovations can allow rafters to spread and the ridge to sag. Any change to these members should be checked by a qualified designer.","key_facts":[{"label":"Function","value":"Resists rafter sag or spread"},{"label":"Historic collar-beam roof span","value":"Up to about 4.5 m (15 ft)"},{"label":"Related member","value":"Rafter tie / ceiling joist"}],"regions":["Global"],"aliases":["collar beam","collar","rafter tie"],"related":["rafter","ridge-board","roof-truss","king-post-truss"],"company":null,"sources":[{"title":"Collar beam","url":"https://en.wikipedia.org/wiki/Collar_beam","publisher":"Wikipedia"},{"title":"Roof glossary","url":"https://www.mkheritage.org.uk/wdahs/Thornton/docs/roofglossary.html","publisher":"Milton Keynes Heritage Association"}],"country":null},{"slug":"collyweston-stone-slate","title":"Collyweston Stone Slate","type":"term","summary":"A frost-split limestone roofing slate from Collyweston, Northamptonshire, England, traditionally exposed to winter frosts to make it split.","body":"Collyweston stone slate is a limestone roofing slate from the area around the village of Collyweston in Northamptonshire, England, near Stamford and the borders of Lincolnshire and Rutland. Despite the name it is not true slate but a thin-bedded limestone, considerably heavier than metamorphic slate. It is the traditional roof covering of many buildings in Northamptonshire, Cambridgeshire, Lincolnshire and Rutland.\n\n## Geology\n\nThe stone forms part of the Lower Lincolnshire Limestone Member of the Lincolnshire Limestone Formation, in the Inferior Oolite Group. It dates from the Bajocian stage of the Middle Jurassic, roughly 170 million years ago, and occurs in narrow beds mined from underground.\n\n## Frosting\n\nCollyweston slate is famous for its traditional production method. Mined blocks were wetted, covered with earth and left outdoors so that winter frosts would expand the moisture in the stone and open its natural layers; traditionally the stone might be left out for up to three winters. Slaters then split the frosted blocks into thin slates and dressed them to shape.\n\nBecause natural frosting depends on cold winters, an artificial alternative was sought. In the late 1990s English Heritage (now Historic England), the Burghley Estate and Sheffield Hallam University developed an artificial frosting system that reproduces freeze-thaw cycles, and further trials to refine it were commissioned in 2012.\n\n## Revival\n\nNew Collyweston slates were produced in 2012 for re-roofing parts of Apethorpe Palace, and new slates have been used on Ufford church in Cambridgeshire and the Guildhall at High Wycombe. In 2015 planning permission was granted to reopen a Collyweston slate mine that had not been worked since the 1960s. Historic uses include Bodley's Court at King's College and Clare College, Cambridge.\n\n## Roof practice\n\nCollyweston roofs were traditionally pegged over riven oak or chestnut battens and torched on the underside with lime mortar. Many have since been re-fixed with nails during repairs; on listed buildings, like-for-like pegging is generally expected. The Collyweston Stone Slaters Trust recommends cement-free lime mortar for repairs and advises that slates from barns or animal shelters may be unsuitable for houses because they can have absorbed salts and acids.\n","key_facts":[{"label":"Rock","value":"Limestone, Middle Jurassic (Bajocian), c. 170 million years old"},{"label":"Location","value":"Collyweston, Northamptonshire, England"},{"label":"Traditional splitting","value":"Natural frost (up to three winters)"},{"label":"Mine reopening approved","value":"2015"}],"regions":["Europe"],"aliases":["Collyweston slate","Collyweston stone"],"related":["stone-slate","stonesfield-slate","cotswold-stone-slate"],"sources":[{"title":"Collyweston stone slate","url":"https://en.wikipedia.org/wiki/Collyweston_stone_slate","publisher":"Wikipedia"},{"title":"Stone Slate Roofing: Technical Advice Note","url":"https://cms.historicengland.org.uk/images-books/publications/stone-slate-roofing-technical-advice-note/stoneslate","publisher":"Historic England (English Heritage)"},{"title":"Notes on Materials","url":"https://www.collywestonstoneslaterstrust.org.uk/material-notes","publisher":"Collyweston Stone Slaters Trust"}],"category":"materials","company":null,"country":null},{"slug":"colorbond-steel","title":"Colorbond Steel","category":"materials","type":"article","summary":"Colorbond is an Australian prepainted steel product line made by BlueScope, first produced in 1966 and ubiquitous on Australian roofs.","body":"Colorbond (styled COLORBOND) is the trade name of a range of prepainted, metallic-coated steel made by BlueScope in Australia. It is used for roofing, walling, gutters, fencing and sheds, and is so widespread that \"Colorbond\" is often used in Australia as a generic word for painted steel roofing. Similar BlueScope products are sold in New Zealand, Southeast Asia and other markets.\n\n## History\n\nCorrugated iron reached Australia in the mid-nineteenth century, introduced by John Lysaght, and for nearly a century the only way to colour it was to repaint it regularly. In the 1950s, US companies developed a way to bond paint to a galvanized base, and Lysaght brought the technology to Australia. The first coil of Colorbond steel came off the painting line at Port Kembla, near Wollongong, New South Wales, in 1966.\n\n## Construction\n\nBlueScope describes five layers:\n\n1. A steel base made to Australian Standards.\n2. A metallic coating using BlueScope's \"Activate\" technology, which the company says improves corrosion resistance (not offered on some variants, such as those on a galvanized base).\n3. A pretreatment layer for adhesion.\n4. A baked corrosion-inhibiting primer.\n5. A baked exterior-grade topcoat.\n\nThe product is made to Australian Standards AS 1397 (metallic-coated steel) and AS/NZS 2728 (prefinished and prepainted products).\n\n## Variants\n\nThe range includes several product variants for different uses and exposures. BlueScope's unpainted aluminium-zinc coated steel is sold separately as Zincalume.\n\n## Context\n\nColorbond is one of several regional prepainted steel brands; equivalent products exist in North America, Europe and Asia under other names. Its long history and familiarity have made it a reference point in Australian building culture.","key_facts":[{"label":"Manufacturer","value":"BlueScope"},{"label":"First production","value":"1966, Port Kembla, NSW"},{"label":"Standards","value":"AS 1397, AS/NZS 2728"},{"label":"Unpainted sister product","value":"Zincalume steel"}],"regions":["Oceania","Southeast Asia"],"aliases":["COLORBOND","Colorbond roofing"],"related":["galvalume","coil-coating","metal-roof-paint-systems","corrugated-iron"],"company":null,"sources":[{"title":"History of COLORBOND steel","url":"https://steel.com.au/resources/articles/history-colorbond-steel","publisher":"BlueScope"},{"title":"COLORBOND steel technology","url":"https://colorbond.com/why-colorbond-steel/technology","publisher":"BlueScope"}],"country":null},{"slug":"combed-wheat-reed","title":"Combed Wheat Reed","type":"term","summary":"Wheat straw combed to remove leaf and grain and laid butt-end down, giving a neat finish; traditional in south-west England, where it is called Devon reed.","body":"Combed wheat reed is wheat straw that has been combed, not threshed, so that the grain and leaves are stripped off and the stems remain straight, undamaged and aligned. Bundles are laid with the butt ends facing out, giving a closely trimmed surface similar in appearance to water reed. Despite its name, it is straw, not reed. It is also known as **Devon reed** or **wheat reed**.\n\n## Distribution\n\nCombed wheat reed is the traditional thatch of south-west England. Historically, farmers in the south-west combed their straw, while across most of lowland England straw was flailed to produce long straw.\n\n## Appearance\n\nRoofs in the West Country often have a relatively shallow pitch and soft, rounded forms, sometimes described as a \"pudding basin\" look. The surface is neat and even, with the eaves and gables cut with a knife.\n\n## Construction\n\nUnlike water reed roofs, existing combed wheat reed does not need to be fully removed before rethatching. New material is fixed with hazel spars into the sound older layers, a practice that over centuries has built up very thick roofs. Some buildings in the region retain base layers that are hundreds of years old and are valuable records of historic crops and farming.\n\n## Supply\n\nCombed wheat reed relies on tall, traditional varieties of winter wheat harvested with a binder and processed with a reed comber. Supply varies greatly with the weather: after a wet autumn in 2019 and drought in spring 2020, growers reported reductions of roughly 20-80% in quantity. In shortages, Historic England recommends patching and thin recoating before considering a change of material.\n\n## Heritage\n\nBecause combed wheat reed is a regional tradition, conservation guidance discourages replacing it with water reed on listed buildings, as this can harm the building's historic significance.\n","key_facts":[{"label":"Material","value":"Combed (unthreshed) wheat straw"},{"label":"Also called","value":"Devon reed, wheat reed"},{"label":"Main region","value":"South-west England"}],"regions":["Europe"],"aliases":["Devon reed","wheat reed","CWR"],"related":["thatch","long-straw-thatch","water-reed-thatch"],"sources":[{"title":"Thatched Roofs - An Introduction","url":"https://www.buildingconservation.com/articles/thatchrf/thatchrf.htm","publisher":"Building Conservation"},{"title":"Traditional straw thatching in times of shortage","url":"https://historicengland.org.uk/content/docs/advice/traditional-straw-thatching-times-of-shortage-context167-mar21","publisher":"Historic England"},{"title":"About thatch","url":"https://eamta.co.uk/about-thatch/","publisher":"East Anglia Master Thatchers Association"}],"category":"materials","company":null,"country":null},{"slug":"concrete-roof-tile","title":"Concrete Roof Tile","type":"article","summary":"A roof tile moulded from sand, cement and pigment; a heavy, economical alternative to clay made in many profiles worldwide.","body":"A concrete roof tile is a tile made from a mix of sand, cement and water, coloured with pigment, formed in a mould or by extrusion and then cured. Concrete tiles are produced in profiles that imitate clay pantiles, Spanish S-tiles, flat slates and plain tiles, and are one of the most common roof coverings on new housing in several countries.\n\n## History\n\nThe earliest known concrete roof tiles were made in the 1840s by Adolph Kroher at Grassau in Bavaria, Germany. Kroher sold cement and moulds so that householders could make their own tiles, which led to inconsistent quality. Factory production with mechanical extrusion in the 20th century made concrete tiles cheap and uniform, and they became widespread in the United Kingdom, continental Europe, Australia, South Africa and the southern and western United States.\n\n## Properties\n\n- **Weight**: concrete tiles are thick and among the heaviest common roofing materials, so the roof structure must be designed for them. A typical UK concrete-tiled roof has rafters at 600 mm (about 24 in) centres with battens at about 300 mm (12 in).\n- **Absorption**: concrete is more porous than well-fired clay; moisture absorption of about 13% is commonly cited, and resealing every 3-7 years is recommended in some climates.\n- **Colour**: comes from pigment mixed through the concrete or from a coloured surface slurry. Surface colour can fade over time, and old concrete roofs are often repainted or recoated.\n- **Life**: concrete tiles are usually expected to last about 30-50 years, compared with 100 years or more for high-quality clay.\n- **Heat**: when laid with an air gap between tile and deck, tiles reduce heat transfer from the sun into the building.\n\n## Profiles\n\n- **Flat or slate-look** tiles.\n- **Low-profile** interlocking tiles with shallow rolls.\n- **High-profile** S-tiles that imitate Spanish or mission clay tiling.\n- **Concrete plain tiles**, laid double-lap in the English manner.\n\nMost concrete tiles are interlocking and single-lap, hung on battens by nibs and nailed or clipped in exposed areas.\n\n## Maintenance issues\n\nCommon problems include surface erosion that exposes the sand aggregate, moss and lichen growth on the rough surface, cracked tiles from foot traffic, and weathered mortar at ridges and hips. Many current systems use dry-fix ridges with mechanical clips instead of mortar.\n","key_facts":[{"label":"Ingredients","value":"Sand, cement, water, pigment"},{"label":"First made","value":"1840s, Grassau, Bavaria (Adolph Kroher)"},{"label":"Typical life","value":"About 30-50 years"},{"label":"Moisture absorption","value":"About 13% (commonly cited)"}],"regions":["Europe","Oceania","Africa","North America","Global"],"aliases":["concrete tile","cement tile","concrete interlocking tile"],"related":["clay-roof-tile","spanish-tile","pantile","plain-tile","interlocking-clay-tile"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Roof","url":"https://en.wikipedia.org/wiki/Roof","publisher":"Wikipedia"},{"title":"Domestic roof construction","url":"https://en.wikipedia.org/wiki/Domestic_roof_construction","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"confederation-of-roofing-contractors","title":"Confederation of Roofing Contractors (CORC)","summary":"CORC is a UK roofing trade association established in 1985 that offers members insurance-backed warranties and business support.","body":"The Confederation of Roofing Contractors (CORC) is a trade association for roofing contractors in the United Kingdom. It was established in 1985 and is based in Brightlingsea, near Colchester, Essex. Its website is corc.co.uk.\n\nCORC members are roofing firms of various sizes spread across the UK, many of them working on domestic (residential) properties. The association provides business support services rather than acting as a regulator.\n\n## Services to members\n\n- **Insurance-backed warranties.** CORC holds authorisation from the UK Financial Conduct Authority (FCA) that allows it to arrange insurance-backed warranties for roofing work done by its members. These are designed to protect the customer if the contractor stops trading before the end of the warranty period.\n- **Deposit protection insurance**, which protects customers' deposits paid in advance.\n- **Code of conduct** that members agree to follow.\n- **Directory** of members for consumers searching for roofers.\n- **Publications and competitions**, including the *Roofing Trades Journal* for members.\n\n## Context\n\nThe UK does not have a general legal licence for roofers. Instead, homeowners rely on trade association membership, government-endorsed schemes such as TrustMark, Competent Person Schemes for building regulations compliance, and references. CORC is one of several associations active in this space, alongside the National Federation of Roofing Contractors (NFRC) and specialist bodies for flat roofing systems.\n\nWhen choosing a roofer, UK consumers are commonly advised to check membership claims with the association directly, ask what warranty is offered and whether it is insurance-backed, and confirm that building regulations notification will be handled for re-roofing work.","key_facts":[{"label":"Founded","value":"1985"},{"label":"Headquarters","value":"Brightlingsea, Essex, England"},{"label":"Regulated by","value":"Financial Conduct Authority (for insurance activity)"},{"label":"Known for","value":"Insurance-backed warranties for members' work"}],"regions":["Europe"],"aliases":["CORC"],"related":["national-federation-of-roofing-contractors","trustmark","how-to-find-a-licensed-roofer"],"company":{"founded":"1985","headquarters":"Brightlingsea, Essex, England","website":"https://www.corc.co.uk","known_for":["Insurance-backed warranties","Roofing Trades Journal"]},"sources":[{"title":"Confederation of Roofing Contractors","url":"https://www.corc.co.uk/","publisher":"CORC"},{"title":"TrustMark","url":"https://www.trustmark.org.uk/about-us","publisher":"TrustMark"}],"category":"organizations","type":"organization","country":null},{"slug":"conical-roof","title":"Conical Roof (Turret Roof)","category":"roof-forms","type":"term","summary":"A conical roof is a roof shaped like a cone, rising to a point over a circular plan; it typically crowns towers, turrets and round huts.","body":"A conical roof, also called a cone roof, rises from a circular base to a single point. It is the natural roof for round buildings and towers, and appears in a remarkable range of traditions, from medieval castle turrets to vernacular dwellings.\n\n## Where it is found\n\n- **Turrets and towers:** conical roofs, often steep and clad in slate or metal, crown castle towers in France, Scotland and Germany and the corner turrets of Queen Anne and Châteauesque houses in North America.\n- **Trulli of Apulia, Italy:** small dry-stone huts with conical corbelled stone roofs.\n- **East Asia:** conical roofs appear on some Chinese pavilions, for example at the Nanhai Academy in Taipei.\n- **Round huts:** thatched conical roofs over circular walls are traditional in many parts of Africa and Asia, as well as in reconstructed prehistoric roundhouses in Europe.\n\n## Construction\n\nFramed conical roofs use rafters radiating from a central point to a circular wall plate, sometimes with a central post. Masonry versions are corbelled, with each course projecting slightly inward. Coverings must be adapted to a surface that tapers to a point: slates and shingles are cut narrower toward the top, metal is laid in tapered gores or segments, and thatch is thinned and bound at the apex. A finial or cap usually seals the tip.\n\n## Practical notes\n\n- The steep pitch sheds water and snow quickly.\n- Gutters around a curved eave must be curved or segmental.\n- The apex is the most difficult point to keep watertight and is often covered by a lead or copper cap.\n- Ventilating the small space under a conical roof requires care.","key_facts":[{"label":"Plan","value":"Circular"},{"label":"Examples","value":"Castle turrets, trulli of Apulia"},{"label":"Covering challenge","value":"Tapered courses to the apex"}],"regions":["Global"],"aliases":["cone roof","turret roof","witch's hat roof","candle-snuffer roof"],"related":["pyramid-roof","dome","onion-dome","rafter"],"company":null,"sources":[{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"},{"title":"Dome","url":"https://en.wikipedia.org/wiki/Dome","publisher":"Wikipedia"}],"country":null},{"slug":"citb","title":"Construction Industry Training Board (CITB)","summary":"CITB is the statutory, levy-funded training board for the construction industry in Great Britain, established in 1964.","body":"The Construction Industry Training Board (CITB) is the industry training board for construction in Great Britain. It was established on 21 July 1964 under the Industrial Training Act 1964 and is funded largely by a statutory levy paid by construction employers. Its head office has been in Peterborough, England, since 2019. Its website is citb.co.uk.\n\n## Role\n\nCITB describes itself as the employer-led skills and standards body for construction. Its work includes:\n\n- **Levy and grants.** Construction employers above certain thresholds pay a levy based on their payroll. In 2024 the levy raised about £228 million. CITB uses this money to fund training grants and skills programmes for employers who are registered with it.\n- **Apprenticeships.** It supports employers in finding and hiring apprentices and funds parts of apprenticeship training. Roofing apprenticeships in England, Scotland and Wales are among the many trades it supports.\n- **Standards and qualifications.** It works on training standards and occupational standards for construction trades.\n- **Commissioning training.** Since 2017 CITB has mainly commissioned outside training providers rather than delivering training itself. Specialist providers are approved as CITB Approved Training Organisations.\n\n## Roofing connections\n\nRoofing is a recognised construction occupation in Great Britain, with apprenticeships covering roof slating and tiling, built-up felt and flat roofing, and sheet metal work. For example, the Lead Sheet Training Academy is a CITB Approved Training Organisation and delivers specialist leadwork qualifications. Roofing trade associations such as the National Federation of Roofing Contractors work with CITB on skills funding and workforce planning.\n\n## Scope\n\nCITB covers Great Britain (England, Scotland and Wales). Northern Ireland has its own construction industry training board. Other countries organise construction training differently: Germany relies on a dual apprenticeship system run with craft chambers and trade guilds, while in North America apprenticeship is overseen by provinces, states and trade unions.\n\n## Note\n\nCITB funding and the training it supports are separate from any requirement to hold a licence; the UK does not license roofers in general.","key_facts":[{"label":"Established","value":"21 July 1964"},{"label":"Legal basis","value":"Industrial Training Act 1964"},{"label":"Head office","value":"Peterborough, England (since 2019)"},{"label":"Levy income (2024)","value":"About £228 million"}],"regions":["Europe"],"aliases":["CITB","Construction Industry Training Board","ConstructionSkills"],"related":["lead-sheet-training-academy","national-federation-of-roofing-contractors","roofing-apprenticeship","health-and-safety-executive"],"company":{"founded":"1964","headquarters":"Peterborough, England","website":"https://www.citb.co.uk","known_for":["Construction industry levy and grants","Apprenticeship support"]},"sources":[{"title":"About CITB","url":"https://www.citb.co.uk/about-citb/","publisher":"CITB"},{"title":"Construction Industry Training Board","url":"https://en.wikipedia.org/wiki/Construction_Industry_Training_Board","publisher":"Wikipedia"}],"category":"organizations","type":"organization","country":null},{"slug":"cool-metal-roofing","title":"Cool Metal Roofing","category":"climate-sustainability","type":"article","summary":"Cool metal roofs use reflective, highly emissive finishes that bounce sunlight and shed absorbed heat, lowering roof temperatures and cooling loads.","body":"A cool roof reflects more of the sun's energy and releases absorbed heat efficiently. Metal roofing can be made \"cool\" through bright natural metal surfaces or, more often, through factory paint finishes formulated with infrared-reflective pigments, so that even medium and dark colours reflect more heat than conventional paints.\n\n## Key measures\n\n- **Solar reflectance**: the fraction of sunlight reflected, from 0 to 1.\n- **Thermal emittance**: how readily the surface releases absorbed heat, from 0 to 1. Bare, unpainted metal has low emittance; painted finishes usually have high emittance.\n- **Solar Reflectance Index (SRI)**: combines the two into a single value, typically 0 to 100, used in green building programmes. Lawrence Berkeley National Laboratory provides an SRI calculator.\n\n## Benefits\n\n- Lower roof surface and attic temperatures.\n- Reduced cooling energy in warm climates. Oak Ridge National Laboratory research reported in 2008 found substantial summer energy savings for cool-coloured metal roofs installed with an air gap.\n- Reflective metal finishes keep much of their reflectivity over time compared with some other roofing types.\n- Contribution to reducing urban heat islands.\n\n## Considerations\n\n- Oak Ridge reported smaller savings in winter than in summer.\n- Results depend on insulation, ventilation and roof construction, not the surface alone.\n\nMany coil-coating resin manufacturers and paint makers market cool-pigment versions of their standard colour ranges.\n\n## Metal compared with other roofs\n\nReflective metal roofs are reported to keep around 95% of their reflectivity over their life, compared with roughly 60 to 80% for some other roof types, and reflective paints are reported to cut cooling bills considerably in hot climates.","key_facts":[{"label":"Key metrics","value":"Solar reflectance, thermal emittance, SRI"},{"label":"SRI scale","value":"Typically 0-100"},{"label":"Main benefit","value":"Lower cooling loads in warm climates"}],"regions":["Global"],"aliases":["cool metal roof","reflective metal roofing","cool roof coatings","SRI"],"related":["pvdf-coating","metal-roof-paint-systems","metal-roofing"],"company":null,"sources":[{"title":"Busting 5 Metal Roofing Myths","url":"https://www.rooferscoffeeshop.com/post/busting-5-metal-roofing-myths-2","publisher":"RoofersCoffeeShop"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Kynar 500 PVDF resin-based coatings","url":"https://kynar500.arkema.com/en/","publisher":"Arkema"},{"title":"What Is a Cool Roof? Reflectance, Emittance & Real Savings","url":"https://www.interlockroofing.com/glossary/cool-roof/","publisher":"Interlock Roofing"},{"title":"Solar Reflectance & Emittance: Interlock's CRRC-Rated Values","url":"https://www.interlockroofing.com/kb/energy-star-cool-roof-solar-reflectance/","publisher":"Interlock Roofing"}],"country":null},{"slug":"cool-roof","title":"Cool Roof","type":"article","summary":"A roof with high solar reflectance and high thermal emittance that stays cooler in sunlight, reducing cooling loads and urban heat.","body":"A cool roof is a roof surface designed to stay cooler in sunlight than a conventional roof. It does this by combining high solar reflectance (reflecting much of the incoming sunlight) with high thermal emittance (efficiently radiating absorbed heat away). Cool roofs can be white, light-coloured, or made with special \"cool colour\" pigments that reflect invisible near-infrared light while looking darker.\n\n## How much cooler\n\nLawrence Berkeley National Laboratory's Heat Island Group reports that on a typical summer afternoon:\n\n- a clean white roof reflecting 80 percent of sunlight stays about 31 °C (55 °F) cooler than a grey roof reflecting 20 percent;\n- a cool-coloured roof reflecting 35 percent stays about 12 °C (22 °F) cooler than a conventional roof reflecting 10 percent.\n\nA study of New York City roofs coated white through the NYC CoolRoofs program found an average surface temperature reduction of about 24 °C (43 °F) compared with black roofs.\n\n## Benefits\n\n- **Lower cooling energy and peak demand.** The US EPA reports that in air-conditioned homes, solar reflectance can cut peak cooling demand by 11-27 percent.\n- **Cooler indoor spaces.** In non-air-conditioned homes, cool roofs can lower maximum indoor temperatures by about 1.2-3.3 °C (2.2-5.9 °F).\n- **Reduced urban heat.** Dark roofs are a major contributor to urban heat islands. A UK study cited by the EPA estimated that citywide cool roofs could offset 18 percent of heat-related deaths linked to the heat island.\n- **Possible longer roof life**, because lower temperatures slow heat aging of some materials.\n\n## Trade-offs\n\nIn cold climates, cool roofs can slightly increase winter heating energy. LBNL research found this penalty is usually small compared with summer savings across most of the United States, and long-lasting snow cover reduces it further. Dirt and biological growth lower reflectance over time, so low-slope cool surfaces may need cleaning. Products with infrared-reflective pigments tend to cost more.\n\n## Products\n\nLow-slope options include white or light single-ply membranes, reflective coatings, cap sheets with reflective granules and light-coloured ballast. Steep-slope options include light or cool-coloured shingles, tile, coated metal and some polymer products.\n\n## Policy\n\nCool roof requirements appear in building codes and green building programs in several US states and cities, according to Cool Roof Rating Council data compiled by the EPA, as well as in programs elsewhere. ENERGY STAR in the United States has required low-slope products to have an initial solar reflectance of at least 0.65 and a weathered value of at least 0.50.","key_facts":[{"label":"Key properties","value":"High solar reflectance and high thermal emittance"},{"label":"White vs grey roof (LBNL)","value":"About 31 °C (55 °F) cooler"},{"label":"Peak cooling reduction (EPA)","value":"11-27% in air-conditioned homes"},{"label":"Winter penalty","value":"Usually small compared with summer savings"}],"regions":["Global","North America","Europe","South Asia","Middle East"],"aliases":["reflective roof","white roof","cool roofing"],"related":["solar-reflectance","thermal-emittance","solar-reflectance-index","urban-heat-island","heat-island-group","cool-roof-rating-council","green-roof"],"sources":[{"title":"Cool Roofs","url":"https://heatisland.lbl.gov/coolscience/cool-roofs","publisher":"Lawrence Berkeley National Laboratory, Heat Island Group"},{"title":"Using Cool Roofs to Reduce Heat Islands","url":"https://www.epa.gov/heatislands/using-cool-roofs-reduce-heat-islands","publisher":"US Environmental Protection Agency"},{"title":"Cool roof (reflective surfaces)","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"cool-roof-rating-council","title":"Cool Roof Rating Council (CRRC)","category":"standards-codes","type":"organization","summary":"The Cool Roof Rating Council is a US non-profit that rates and lists the solar reflectance and thermal emittance of roofing and wall products.","body":"The Cool Roof Rating Council (CRRC) is a non-profit organization in the United States that develops methods for evaluating and labelling the radiative properties of roofing and exterior wall products. Its ratings are the main reference for **solar reflectance** (how much sunlight a surface reflects) and **thermal emittance** (how readily it sheds absorbed heat as infrared radiation) in North American energy codes and green building programs.\n\n## What the CRRC does\n\n- **Rates products.** Manufacturers submit products to accredited laboratories for testing. Rated values are published in the CRRC's Roof Products Directory and Wall Products Directory.\n- **Tracks ageing.** Ratings report both initial values and aged values after outdoor weathering, because dirt, biological growth and weathering reduce reflectance over time.\n- **Checks ratings.** The CRRC conducts random testing of listed products to verify that published values hold.\n- **Publishes a standard.** Its rating procedures are formalized in ANSI/CRRC S100, an American National Standard for test methods for radiative properties.\n\nThe CRRC does **not** set minimum performance levels. It reports values; codes and programs decide which values qualify as a \"cool roof.\"\n\n## Why the ratings matter\n\nA white roof that reflects 80% of sunlight can stay about 31 °C (55 °F) cooler on a summer afternoon than a grey roof reflecting 20%, according to Lawrence Berkeley National Laboratory. Lower roof temperatures reduce cooling energy use in buildings and help reduce urban heat islands. Thermal emittance matters because a highly reflective surface that cannot shed heat (such as bare metal) still runs warmer than its reflectance alone suggests.\n\n## Use in codes and programs\n\nCRRC-rated values are referenced by energy codes such as [California Title 24](/title-24-cool-roof) and [ASHRAE 90.1](/ashrae-90-1), by green building programs including [LEED](/leed-heat-island-reduction), and by local cool roof ordinances. The US EPA notes that cool roof requirements appear in codes or ordinances in a number of states, cities and counties. Since the [ENERGY STAR roof label](/energy-star-roof-products) ended in 2022, the CRRC directory has become the main listing for reflective roofing in North America.\n\n## Related metrics\n\nSolar reflectance and thermal emittance can be combined into a single number, the [Solar Reflectance Index](/solar-reflectance-index) (SRI), which some programs use instead of separate values.","key_facts":[{"label":"Type","value":"Non-profit rating organization (US)"},{"label":"Rates","value":"Solar reflectance and thermal emittance, initial and aged"},{"label":"Standard","value":"ANSI/CRRC S100"},{"label":"Sets minimums?","value":"No; codes and programs set thresholds"}],"regions":["North America"],"aliases":["CRRC","Cool Roof Rating Council"],"related":["solar-reflectance-index","cool-roof","title-24-cool-roof","energy-star-roof-products","leed-heat-island-reduction","solar-reflectance","thermal-emittance","heat-island-group","urban-heat-island","oak-ridge-national-laboratory-building-envelope-research"],"company":{"website":"https://coolroofs.org/","known_for":["Roof Products Directory","ANSI/CRRC S100"]},"sources":[{"title":"Cool Roof Rating Council","url":"https://coolroofs.org/","publisher":"CRRC"},{"title":"Using Cool Roofs to Reduce Heat Islands","url":"https://www.epa.gov/heatislands/using-cool-roofs-reduce-heat-islands","publisher":"US EPA"},{"title":"Cool roof","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"},{"title":"Cool Science: Cool Roofs","url":"https://heatisland.lbl.gov/coolscience/cool-science-cool-roofs","publisher":"Lawrence Berkeley National Laboratory"},{"title":"About the CRRC","url":"https://coolroofs.org/about","publisher":"Cool Roof Rating Council"},{"title":"CRRC celebrates 10 years of growth, technical advancement and industry adoption","url":"https://coolroofs.org/news/crrc-celebrates-10-years-of-growth-technical-advancement-and-industry-adoption","publisher":"Cool Roof Rating Council"},{"title":"CRRC: Cool Roof Rating Council","url":"https://basc.pnnl.gov/library/crrc-cool-roof-rating-council","publisher":"Pacific Northwest National Laboratory"}],"country":null},{"slug":"copenhagen-green-roof-policy","title":"Copenhagen Green Roof Policy","type":"standard","summary":"Since 2010, Copenhagen has required green roofs on new buildings with roofs sloped under 30 degrees, as part of climate adaptation.","body":"Copenhagen, the capital of Denmark, adopted a green roof policy in 2010, making it one of the first European capitals to require vegetated roofs. Under the city's guidelines, new buildings with flat or low-slope roofs, defined as roofs with a slope of less than 30 degrees, must have green roofs.\n\n## Purpose\n\nCopenhagen's policy is tied to climate adaptation, particularly managing intense rainfall. Green roofs absorb rainwater and slow its flow into the sewer system, reducing the risk of overloaded drains and flooding. The city has also promoted green roofs for their cooling, biodiversity and recreational benefits.\n\n## Climate adaptation context\n\nGreen roofs form one part of the city's wider effort to adapt to heavier rainfall by retaining and delaying stormwater before it reaches sewers.\n\n## Comparison with other cities\n\n- **Toronto (2009)** sets coverage percentages by building size.\n- **Basel (2002)** requires greening of flat roofs with native soils and plants.\n- **Copenhagen (2010)** uses a roof slope threshold of 30 degrees to define which new roofs must be green.\n\n## Building considerations\n\nRoofs pitched at up to 30 degrees can be greened, but steeper green roofs need measures to stop substrate slipping, such as edge restraints and stabilising grids. The added weight must be considered in structural design, and waterproofing and root barriers must be suitable for long-term vegetation cover.\n\n## Expected stormwater benefit\n\nResearch summarized by the US EPA indicates that extensive green roofs can reduce runoff by about 60 percent, with the best performance in small and moderate storms, and that green roof surfaces stay far cooler than conventional roofs in summer. For a city managing frequent heavy rain, such reductions in roof runoff ease the load on drainage networks.","key_facts":[{"label":"Adopted","value":"2010"},{"label":"Applies to","value":"New buildings with roofs sloped under 30 degrees"},{"label":"Main goal","value":"Stormwater management and climate adaptation"}],"regions":["Europe"],"aliases":["Copenhagen green roofs","Copenhagen green roof requirement"],"related":["green-roof","toronto-green-roof-bylaw","basel-green-roof-policy","blue-roof"],"sources":[{"title":"Green roofs in Copenhagen","url":"https://stateofgreen.com/en/solutions/green-roofs-in-copenhagen/","publisher":"State of Green"},{"title":"Smart City Good Practice: Green Roofs Copenhagen","url":"https://pocacito.eu/sites/default/files/GreenRoofs_Copenhagen_POCACITO.pdf","publisher":"POCACITO (EU project)"},{"title":"Using Green Roofs to Reduce Heat Islands","url":"https://www.epa.gov/heatislands/using-green-roofs-reduce-heat-islands","publisher":"US Environmental Protection Agency"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"coping","title":"Coping","category":"low-slope-systems","type":"term","summary":"The capping on top of a parapet or wall that sheds water and protects the wall and the roof membrane termination beneath it.","body":"A coping is the capping or covering laid along the top of a wall, including the parapets of low-slope roofs. Its job is to shed water off the top of the wall and away from its faces, and on a roof it also covers and protects the top edge of the membrane where it runs up and over the parapet. The word derives from \"cope\", from Latin capa, a cloak.\n\n## Materials\n\n- natural and cast stone, precast concrete, brick and terracotta\n- sheet metal: aluminium, galvanised or coated steel, stainless steel, copper and zinc\n- tile, slate and other units on traditional walls\n\nMetal copings are the most common choice on commercial low-slope roofs because they are light, quick to install and available in long lengths with concealed splice plates at joints.\n\n## Design features\n\n- **Weathered top:** the top surface is sloped or curved so water runs off, usually toward the roof side so dirty water does not streak the façade.\n- **Drip:** in UK practice a coping projects beyond the wall face with a drip or throating so water falls clear; a flush capping without a drip is distinguished as a \"capping\".\n- **Joints:** masonry copings need sealed or flashed joints; metal copings use cleats, splice plates and allowance for thermal movement.\n- **Underlay:** a waterproofing membrane under the coping protects the wall top if joints leak.\n\n## Wind resistance\n\nEdge metal and copings are a common point of failure in high winds; once they peel off, the membrane edge can be lifted. In North America, ANSI/SPRI ES-1 is the standard used to test and rate roof edge systems, including copings, for wind resistance, and building codes reference it.","key_facts":[{"label":"Function","value":"Shed water from wall top; cover membrane edge"},{"label":"Common commercial material","value":"Sheet metal"},{"label":"North American wind standard","value":"ANSI/SPRI ES-1"},{"label":"Etymology","value":"From 'cope', Latin capa"}],"regions":["Global"],"aliases":["parapet coping","coping cap","wall capping"],"related":["parapet","flat-roof","single-ply-roofing"],"company":null,"sources":[{"title":"Coping (architecture)","url":"https://en.wikipedia.org/wiki/Coping_(architecture)","publisher":"Wikipedia"},{"title":"ANSI/SPRI Standards","url":"https://www.spri.org/standards/","publisher":"SPRI"},{"title":"Parapet","url":"https://en.wikipedia.org/wiki/Parapet","publisher":"Wikipedia"}],"country":null},{"slug":"copper-development-association","title":"Copper Development Association (CDA)","summary":"The Copper Development Association is the North American market development and technical information body of the copper industry.","body":"The Copper Development Association (CDA) is a U.S.-based industry organisation that serves as the market development, engineering and information services arm of the copper industry. It is chartered to expand markets for copper and copper alloys in North America. Its website is copper.org.\n\nMembership is open to copper producers worldwide and to brass mill, wire mill and foundry companies with production facilities in the United States.\n\n## Architecture and roofing\n\nCopper has been used on roofs for centuries, on church spires, domes, flashings, gutters and standing seam or flat-lock roof panels. It is valued for long service life and for the green patina that forms as it weathers. CDA provides architects and sheet metal contractors with technical guidance on copper in building construction, including:\n\n- design and installation details for copper roofing systems, gutters, downspouts and flashings;\n- guidance on thermal expansion, which must be allowed for in long copper panels;\n- information on compatibility with other metals and materials, since copper can cause corrosion of zinc, aluminium and galvanised steel where water runs from copper onto them.\n\nCDA also produces short instructional videos on proper use of copper in construction.\n\n## Awards\n\nWith the Canadian Copper & Brass Development Association, CDA runs the North American Copper in Architecture Awards, which recognise building projects that use copper and copper alloys.\n\n## International context\n\nCopper industry promotion outside North America is carried out by related organisations, such as the European Copper Institute and regional copper centres in Asia and Latin America. Guidance on copper roofing in Europe is also covered by national roofing rules and by standards such as EN 1172, which sets requirements for copper sheet used in building.\n\n## Note\n\nCDA is an industry body. Its material promotes the use of copper; independent design guidance can be found in building codes, sheet metal trade manuals and national roofing standards.","key_facts":[{"label":"Role","value":"Market development and technical arm of the copper industry"},{"label":"Region","value":"North America"},{"label":"Awards","value":"North American Copper in Architecture Awards"},{"label":"Website","value":"copper.org"}],"regions":["North America"],"aliases":["CDA"],"related":["copper-roofing","standing-seam-metal-roof","roof-flashing","galvanic-corrosion"],"company":{"website":"https://www.copper.org","known_for":["Copper architecture technical guidance","North American Copper in Architecture Awards"]},"sources":[{"title":"About CDA","url":"https://www.copper.org/about/","publisher":"Copper Development Association"},{"title":"Copper Development Association home page","url":"https://www.copper.org/","publisher":"Copper Development Association"}],"category":"organizations","type":"organization","country":null},{"slug":"copper-patina","title":"Copper Patina","category":"materials","type":"term","summary":"Copper patina is the stable green or blue-green film of copper salts that forms on copper roofs over years of weathering and protects the metal.","body":"When bare copper is exposed outdoors it reacts slowly with oxygen, moisture and airborne sulphur and carbon compounds. The surface first darkens to browns and then, over years, develops the familiar green or blue-green coating called patina. Once fully formed, the patina is tightly bonded and highly resistant to further atmospheric attack, which is one reason copper roofs last so long.\n\n## Colour sequence\n\nNew copper is salmon pink. In the first weeks, especially in wet weather, rainbow-like interference colours can appear before the surface settles into russet and then light and dark chocolate browns. A dark oxide stage can persist for years before green begins to show. Mill oils sometimes cause temporary dark streaks that rain washes away.\n\n## Chemistry\n\nThe early brown films are oxides and sulphides, which offer only modest protection. The mature green layer is mainly basic copper sulphate in urban and industrial air and basic copper carbonate in cleaner rural air; near the sea, chlorides also take part. These films are thin, on the order of 0.05 to 0.08 mm, and are described as self-healing: a scratch slowly repatinates.\n\n## How long it takes\n\nPublished estimates vary with climate:\n\n- Industrial and seacoast locations: about 5 to 7 years (Australian and US sources), or about 5 years in marine air and 10 years in industrial air (New Zealand guidance).\n- Rural or moderate locations: about 10 to 15 years or longer; some sources cite around 18 years, and more than 30 in very mild air.\n- Arid regions: patina may never form; copper stays dark brown or bronze.\n\nHorizontal and low-slope surfaces green first, steep slopes later and vertical walls last.\n\n## Managing appearance\n\nClear lacquers and oils slow colour change but need reapplication. Factory pre-patinated copper sheet is available for an immediate green look, though its colour can vary between batches. Handling with bare hands can leave marks, so installers often wear cotton gloves.","key_facts":[{"label":"Main patina compounds","value":"Basic copper sulphates and carbonates"},{"label":"Typical time to green (industrial/coastal)","value":"About 5-7 years"},{"label":"Typical time to green (rural)","value":"About 10-15+ years"},{"label":"Arid climates","value":"Green patina may never form"}],"regions":["Global"],"aliases":["copper verdigris (colloquial)","green copper roof","copper weathering"],"related":["copper-roofing","verdigris","copper-runoff-staining","zinc-roofing"],"company":null,"sources":[{"title":"Copper Alloys Finishes – Natural Weathering","url":"https://www.australwright.com.au/technical-data/advice/copper-brass/copper-alloys-finishes-natural-weathering/","publisher":"Austral Wright Metals"},{"title":"Copper Patina","url":"https://www.metalroofing.org.nz/node/3860","publisher":"NZ Metal Roof and Wall Cladding Code of Practice (metalroofing.org.nz)"},{"title":"Copper Availability and Attributes","url":"https://atas.com/did-you-know-series/copper-availability-and-attributes","publisher":"ATAS International"},{"title":"Copper Roof Patina: Why Copper Roofs Turn Green (2026)","url":"https://www.interlockroofing.com/kb/copper-roof-patina-green/","publisher":"Interlock Roofing"},{"title":"What Is Copper Roofing? (The Complete Guide, 2026)","url":"https://www.interlockroofing.com/kb/what-is-copper-roofing/","publisher":"Interlock Roofing"}],"country":null},{"slug":"copper-roofing","title":"Copper Roofing","category":"materials","type":"article","summary":"Copper roofing uses soft cold-rolled copper sheet, typically 16 or 20 oz per square foot, which weathers from bright salmon to brown and eventually green.","body":"Copper has been used on roofs for centuries because it is durable, easy to form and solder, and needs no coating. It is installed as standing seam, batten seam, flat seam and horizontal seam roofs, and is also common for flashings, gutters, domes, cupolas and bay roofs. Philadelphia's Christ Church (1727 to 1744) had a standing seam copper roof; until the end of the eighteenth century, sheet for American roofs was imported from England.\n\n## Material\n\nNorth American specifications call for cold-rolled copper to ASTM B370, usually in temper H00. Copper is sold by weight per area:\n\n- 16 oz/ft2: about 0.0216 in (0.55 mm), roughly 24 gauge.\n- 20 oz/ft2: about 0.0270 in (0.69 mm), roughly 22 gauge.\n\nElsewhere copper sheet is specified directly in millimetres.\n\n## Installation basics\n\n- Pans are held by concealed copper cleats, typically at about 12 in (300 mm) centres, so they can expand and contract.\n- A rosin-sized paper slip sheet is laid over the underlayment so that heat-softened asphalt does not glue the copper to the deck.\n- Nails are copper or bronze; screws and bolts are copper, bronze, brass or 300-series stainless steel.\n- Contact with incompatible metals or corrosive substrates is prevented with a bituminous coating or another permanent separator.\n- Joints on low-slope roofs are soldered; tinned edges are typically 1.5 in (38 mm) wide.\n\n## Weathering and run-off\n\nCopper changes colour over years, from salmon pink through browns to a blue-green or grey-green patina whose timing depends on climate. Run-off can stain stone, brick and concrete and will attack aluminium and zinc-coated steel downstream.\n\n## Life and cost\n\nProperly installed copper roofs are commonly cited at 100 years or more. The metal is expensive but fully recyclable, and old copper is usually salvaged.","key_facts":[{"label":"Material standard (US)","value":"ASTM B370, cold-rolled, temper H00"},{"label":"16 oz copper","value":"0.0216 in (0.55 mm)"},{"label":"20 oz copper","value":"0.0270 in (0.69 mm)"},{"label":"Cited service life","value":"100+ years"}],"regions":["Global"],"aliases":["copper roof","sheet copper roofing","architectural copper"],"related":["copper-patina","verdigris","batten-seam-roofing","flat-seam-roofing","standing-seam-metal-roof","rosin-paper-slip-sheet","copper-runoff-staining","soldering-sheet-metal-roofing"],"company":null,"sources":[{"title":"14.3. Copper Roofing (architectural specifications)","url":"https://archive.copper.org/applications/architecture/arch_dhb/specifications/arch_specs/sheet_roofing.php","publisher":"Copper Development Association"},{"title":"Copper Availability and Attributes","url":"https://atas.com/did-you-know-series/copper-availability-and-attributes","publisher":"ATAS International"},{"title":"Section 07 61 16 Sheet Metal Roofing (VA master specification)","url":"https://www.wbdg.org/FFC/VA/VANCAS/VANCA076116.pdf","publisher":"Whole Building Design Guide / U.S. Department of Veterans Affairs"},{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"},{"title":"How Long Does a Copper Roof Last? (100+ Years Explained)","url":"https://www.interlockroofing.com/kb/how-long-does-a-copper-roof-last/","publisher":"Interlock Roofing"},{"title":"Copper Roof Pros and Cons (Is It Worth It? 2026)","url":"https://www.interlockroofing.com/kb/copper-roof-pros-and-cons/","publisher":"Interlock Roofing"},{"title":"Copper Roofing Types: Panels, Sheets, Shingles & Standing Seam","url":"https://www.interlockroofing.com/kb/copper-roofing-types/","publisher":"Interlock Roofing"},{"title":"Durability: Compatibility (NZ Metal Roof and Wall Cladding Code of Practice)","url":"https://www.metalroofing.org.nz/cop/durability/compatibility","publisher":"NZ Metal Roofing Manufacturers"}],"country":null},{"slug":"copper-runoff-staining","title":"Copper Run-Off and Staining","category":"problems-maintenance","type":"term","summary":"Rainwater flowing off copper carries dissolved copper that can stain masonry green and corrode aluminium, zinc and zinc-coated steel downstream.","body":"As copper weathers, rain slowly dissolves small amounts of copper compounds from its surface. That run-off has two practical effects: it can leave blue-green stains on light-coloured materials, and it can attack less noble metals that it flows onto.\n\n## Staining\n\nCopper run-off is well known for staining marble, limestone, stucco, mortar, brick, stone and concrete beneath copper roofs, gutters, downpipes and flashings. Stains are most visible where water concentrates, such as below drip edges, scuppers and the ends of valleys. Planning water paths, using gutters and downpipes, and keeping drip edges clear of walls reduces staining. Some owners use clear coatings on copper to slow weathering, though these need periodic renewal.\n\n## Corrosion of other metals\n\nDissolved copper deposits on more active metals and sets up tiny galvanic cells. Water from copper should not drain onto:\n\n- aluminium roofing, gutters or flashings;\n- zinc or titanium-zinc;\n- galvanized steel or 55% aluminium-zinc coated steel such as Galvalume.\n\nMetal roofing codes of practice rate both copper run-off onto these metals and direct contact with copper as unsuitable. Where copper and other metals must coexist, designers route copper run-off away or separate the metals with membranes and bituminous coatings.\n\n## Compatible companions\n\nCopper alloys such as bronze and brass and 300-series stainless steel are the usual fastener and accessory metals with copper, according to copper industry specifications.\n\n## Rates of release\n\nWeathering of copper is slow. New Zealand guidance indicates corrosion rates of roughly 2 to 3 micrometres per year at first, falling over time as the patina matures. Even small amounts of dissolved copper are enough to stain light surfaces and attack zinc or aluminium over many years.","key_facts":[{"label":"Stains","value":"Masonry, stone, stucco, concrete"},{"label":"Metals harmed by run-off","value":"Aluminium, zinc, galvanized and Al-Zn coated steel"},{"label":"Usual companion metals","value":"Bronze, brass, 300-series stainless steel"}],"regions":["Global"],"aliases":["copper staining","copper wash","copper runoff corrosion"],"related":["copper-roofing","copper-patina","galvanic-corrosion","galvalume"],"company":null,"sources":[{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Copper Patina","url":"https://www.metalroofing.org.nz/node/3860","publisher":"NZ Metal Roof and Wall Cladding Code of Practice (metalroofing.org.nz)"},{"title":"Galvanic corrosion","url":"https://en.wikipedia.org/wiki/Galvanic_corrosion","publisher":"Wikipedia"},{"title":"Copper Roof Pros and Cons (Is It Worth It? 2026)","url":"https://www.interlockroofing.com/kb/copper-roof-pros-and-cons/","publisher":"Interlock Roofing"},{"title":"Copper Roof Patina: Why Copper Roofs Turn Green (2026)","url":"https://www.interlockroofing.com/kb/copper-roof-patina-green/","publisher":"Interlock Roofing"},{"title":"Durability: Compatibility (NZ Metal Roof and Wall Cladding Code of Practice)","url":"https://www.metalroofing.org.nz/cop/durability/compatibility","publisher":"NZ Metal Roofing Manufacturers"},{"title":"14.3. Copper Roofing (architectural specifications)","url":"https://archive.copper.org/applications/architecture/arch_dhb/specifications/arch_specs/sheet_roofing.php","publisher":"Copper Development Association"}],"country":null},{"regions":["Europe"],"company":null,"slug":"coppo-tile","title":"Coppo (Italian Curved Tile)","category":"world-roofing","type":"term","summary":"The coppo is the traditional Italian curved clay roof tile, laid as alternating channels and covers or over flat embrici, descended from Roman roofing.","aliases":["coppi","coppo","canale","Venetian coppi","coppo veneto"],"body":"The **coppo** (plural *coppi*) is the traditional curved clay roof tile of Italy, shaped roughly like a section of a tapering cone. It belongs to the same family as the Spanish *teja árabe* and the curved tiles of Portugal, and was widely used by the Romans and known to the Greeks and Etruscans before spreading through southern Europe and the Mediterranean.\n\n## Size and weight\n\nA typical coppo is 45-50 cm (18-20 in) long and 13-20 cm (5-8 in) wide, though sizes vary by region; recognised regional types include the *coppo veneto* (Venetian) and *coppo piemontese*. A roof needs about 28-30 coppi per square metre with overlaps of around 6 cm (2.4 in), and weighs about 60-66 kg/m² (12-14 lb/ft²). The pitch is generally at least 30%.\n\n## Laying\n\nTwo systems are used:\n\n- **Coppi on coppi:** alternating rows of tiles laid concave side up as channels (*canali*) and convex side up as covers (*coperte*). This is found in both northern and southern Italy and is sometimes called *alla diavola*.\n- **Coppi on embrici:** curved covers over flat pan tiles (*embrici*), the direct descendant of the Roman tegula and imbrex. Common mainly in central Italy, where it is called *alla romana* or *alla fiorentina*; in Tuscany it was used almost exclusively until modern tiles arrived.\n\nBoth systems tolerate generous overlaps, so they adapt well to complex roof shapes. A known weakness is that coppi slowly creep down the slope; versions with anchoring lugs are made to prevent this. In Spain, comparable laying methods range from loose tiles on battens to tiles bedded in mortar on a solid deck.\n\n## Manufacture\n\nCoppi were traditionally moulded by hand and are now mostly extruded. Colour depends on the clay or added natural oxides, and glazed and artificially \"antiqued\" versions are made to match weathered roofs.\n\n## Modern alternatives and heritage\n\nSingle-piece S-shaped tiles combining channel and cover are faster to lay and resist wind and vibration better, but they are generally not allowed in Italian historic centres. Conservation work therefore keeps coppi in use, often reclaimed from older roofs.","key_facts":[{"label":"Size","value":"45-50 cm long, 13-20 cm wide"},{"label":"Coverage","value":"About 28-30 tiles per m²"},{"label":"Roof weight","value":"About 60-66 kg/m² (12-14 lb/ft²)"},{"label":"Minimum pitch","value":"Generally 30%"}],"related":["roofing-in-italy","imbrex-and-tegula","spanish-tile","mission-tile","clay-roof-tile","pantile","spanish-mediterranean-terracotta-roof","tile-slippage"],"sources":[{"title":"Coppo","url":"https://it.wikipedia.org/wiki/Coppo","publisher":"Wikipedia (Italian)"},{"title":"Teja","url":"https://es.wikipedia.org/wiki/Teja","publisher":"Wikipedia (Spanish)"},{"title":"Imbrex and tegula","url":"https://en.wikipedia.org/wiki/Imbrex_and_tegula","publisher":"Wikipedia"}],"country":null},{"slug":"corrugated-bitumen-sheet","title":"Corrugated Bitumen Sheet","type":"term","summary":"A lightweight corrugated roofing sheet of plant fibres saturated with bitumen, used on sheds, outbuildings and agricultural roofs.","body":"A corrugated bitumen sheet is a light, wavy roofing panel made from organic fibres saturated with bitumen and coloured on the surface. It is widely used on garden sheds, carports, stables, lean-tos and farm buildings, and as an under-layer beneath tiles in some systems. The product type is often called by the best-known brand name, Onduline, which originated in France and states that it has been making such products for about 80 years.\n\n## Composition\n\nSheets are made from a mat of cellulose fibres, derived from wood, impregnated with bitumen and formed into corrugations. One manufacturer states that its sheets contain about 45-51% recycled material.\n\n## Typical properties\n\nUsing one widely sold product as an example:\n\n- **Size**: 2,000 by 950 mm (about 79 by 37 in), covering 1.9 m² (20.5 ft²) per sheet.\n- **Thickness**: 3 mm (about 1/8 in).\n- **Weight**: about 6.4 kg (14 lb) per sheet, or roughly 3.4 kg/m² (0.7 lb/ft²), far lighter than fibre cement or tile.\n- **Profile**: 10 corrugations about 38 mm (1.5 in) high at 95 mm (3.7 in) centres.\n- **Minimum pitch**: 5°, with a full supporting deck required below 10°.\n- **Fire**: reaction-to-fire Class E under the European system, meaning it is combustible.\n\nIn Europe, corrugated bitumen sheets are covered by the harmonised product standard EN 534.\n\n## Advantages\n\n- Light and easy to cut, carry and fix, so it is popular for DIY work.\n- Does not rust and is quieter in rain than thin metal sheet.\n- Low cost compared with most other roofing.\n\n## Limitations\n\n- Manufacturer waterproofing warranties are relatively short (15 years for one leading product), reflecting a shorter service life than tile or metal.\n- The sheets are combustible (Class E), which needs to be considered where building regulations control fire spread.\n\n## Related products\n\nThe same manufacturers make corrugated bitumen \"tile-effect\" sheets and small bitumen tiles that imitate clay roofing.\n","key_facts":[{"label":"Material","value":"Cellulose fibres saturated with bitumen"},{"label":"Typical sheet","value":"2,000 x 950 mm, 3 mm thick, about 6.4 kg"},{"label":"Minimum pitch (example)","value":"5° (full deck below 10°)"},{"label":"European standard","value":"EN 534"}],"regions":["Europe","Global"],"aliases":["Onduline","bitumen corrugated sheet","corrugated asphalt sheet","fibre bitumen sheet"],"related":["corrugated-fibre-cement-sheet","bitumen-shingle","polycarbonate-roofing-sheet","roll-roofing"],"sources":[{"title":"ONDULINE CLASSIC","url":"https://uk.onduline.com/en/diy/products/roofing-sheets-tiles/onduline-classic","publisher":"Onduline UK"},{"title":"Onduline DIY roofing","url":"https://uk.onduline.com/en/diy","publisher":"Onduline UK"},{"title":"Onduline Group","url":"https://www.onduline.com/","publisher":"Onduline"}],"category":"materials","company":null,"country":null},{"slug":"corrugated-fibre-cement-sheet","title":"Corrugated Fibre-Cement Sheet","type":"term","summary":"A large corrugated roofing sheet of fibre-reinforced cement, used mainly on agricultural, industrial and utility buildings.","body":"A corrugated fibre-cement sheet is a large roofing panel made from cement reinforced with fibres and formed with regular corrugations for stiffness. It is widely used on barns, livestock buildings, warehouses, factories and garages, and in some regions on houses.\n\n## History\n\nCorrugated sheets were among the main products of the asbestos-cement industry founded on Ludwig Hatschek's patent of 1900, and profiles such as \"Super Six\" became a familiar sight on farm and industrial buildings. The material was popular because it was fireproof, did not rust and was cheap. From the 1980s, asbestos fibres were replaced with cellulose and synthetic fibres, and asbestos-free corrugated fibre-cement sheets are still widely made by companies including the Eternit brand owner, Etex.\n\n## Characteristics\n\n- **Non-combustible** cement-based body.\n- **Does not rust**, unlike unprotected steel sheet.\n- **Heavy and brittle**: sheets are heavier than metal or plastic sheeting and can crack under point loads. Such roofs should be treated as fragile and never walked on without crawling boards or staging.\n\n## Identifying old asbestos sheets\n\nCorrugated cement sheets installed before the asbestos bans (for example, before 1999 in Great Britain or 2003 in Australia) may contain asbestos. Owners should have suspect sheets tested before drilling, cutting, cleaning or removing them, and follow local rules on removal and disposal. Pressure-washing old sheets can release fibres and is prohibited in some places, such as Queensland.\n\n## Today\n\nAsbestos-free corrugated fibre-cement sheets remain common on agricultural and light industrial buildings worldwide, alongside alternatives such as profiled steel, corrugated bitumen and translucent plastic sheets.\n","key_facts":[{"label":"Material","value":"Fibre-reinforced cement"},{"label":"Typical uses","value":"Farm, industrial and utility buildings"},{"label":"Safety","value":"Fragile roof; old sheets may contain asbestos"}],"regions":["Global"],"aliases":["corrugated cement sheet","fibre cement roofing sheet","Super Six sheet"],"related":["asbestos-cement-roofing","fibre-cement-slate","corrugated-bitumen-sheet","polycarbonate-roofing-sheet","fragile-roof"],"sources":[{"title":"Asbestos cement","url":"https://en.wikipedia.org/wiki/Asbestos_cement","publisher":"Wikipedia"},{"title":"Eternit","url":"https://en.wikipedia.org/wiki/Eternit","publisher":"Wikipedia"},{"title":"Fiber cement siding","url":"https://en.wikipedia.org/wiki/Fiber_cement_siding","publisher":"Wikipedia"},{"title":"Asbestos and the law","url":"https://en.wikipedia.org/wiki/Asbestos_and_the_law","publisher":"Wikipedia"},{"title":"Ludwig Hatschek","url":"https://en.wikipedia.org/wiki/Ludwig_Hatschek","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"corrugated-iron","title":"Corrugated Iron (Corrugated Galvanised Iron)","category":"materials","type":"article","summary":"Corrugated iron is sheet metal rolled into parallel waves for stiffness; patented in 1829, it became a defining roofing material of farms, colonies and industry.","body":"Corrugated iron is thin metal sheet formed into a regular series of rounded ridges and troughs. The waves give the sheet much greater stiffness across the corrugations, so it can span between widely spaced supports with little framing. The galvanised version, often abbreviated CGI, is coated with zinc against rust. Although almost all modern sheet is steel, and usually carries an aluminium-zinc coating or paint, the name \"iron\" has stuck.\n\n## History\n\nHenry Robinson Palmer, engineer to the London Dock Company, patented corrugated metal sheets in 1829 and soon roofed a shed of about 40 ft (12 m) span with it. Galvanising, developed in France in 1837, made the material far more durable. By the 1840s British firms were exporting fully prefabricated corrugated iron buildings to Australia, South Africa and other colonies, and suppliers such as William Cooper and Boulton & Paul sold kit churches and chapels, now known in Britain as \"tin tabernacles\". John Lysaght introduced it to Australia within about a decade. Mild steel replaced wrought iron from about the 1890s.\n\n## Profile\n\nNearly all modern corrugated sheet has a pitch of 3 in (76 mm) between crests. Historic roofing sheets were often about 18 SWG (1.2 mm) thick, considerably heavier than today's sheets, with profile pitches of roughly 3 to 5 in.\n\n## Global use\n\nCorrugated sheet is still a mainstream roofing material in Australia, New Zealand and Argentina, including in cities, and is ubiquitous on rural and informal buildings in Africa, Latin America and South Asia because it is light, cheap and easy to transport and fix.\n\n## Conservation\n\nHistoric corrugated buildings suffer mainly from neglect. Corrosion often starts at overlaps where moisture is held by capillary action. Regular painting greatly slows rust, and repairs should match original sheet size, gauge, profile and fixings.","key_facts":[{"label":"Patent","value":"1829, Henry Robinson Palmer (UK)"},{"label":"Standard modern pitch","value":"3 in (76 mm)"},{"label":"Typical historic thickness","value":"18 SWG (about 1.2 mm)"},{"label":"Galvanising developed","value":"1837 (France)"}],"regions":["Global","Oceania","Africa","Europe","Latin America"],"aliases":["CGI","corrugated galvanised iron","corrugated steel","corrugated metal roofing","wrinkly tin"],"related":["galvanized-steel-roofing","through-fastened-metal-panels","tin-roof","colorbond-steel","metal-roofing"],"company":null,"sources":[{"title":"Corrugated galvanised iron","url":"https://en.wikipedia.org/wiki/Corrugated_galvanised_iron","publisher":"Wikipedia"},{"title":"Corrugated Iron Architecture","url":"https://buildingconservation.com/articles/corrugated-iron-architecture/corrugated-iron-architecture.htm","publisher":"Building Conservation Directory"},{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"},{"title":"History of COLORBOND steel","url":"https://steel.com.au/resources/articles/history-colorbond-steel","publisher":"BlueScope"}],"country":null},{"slug":"cotswold-stone-slate","title":"Cotswold Stone Slate","type":"term","summary":"Limestone roofing slates from the Cotswolds of England, laid in diminishing courses on steep roofs and fixed with oak pegs.","body":"Cotswold stone slates are roofing slates made from the oolitic limestones of the Cotswold hills in south-central England. They are the traditional roof covering of the region's villages, farm buildings and churches and are closely associated with its honey-coloured stone architecture.\n\n## Sources\n\nCotswold District Council guidance describes two source beds:\n\n- **Forest Marble**: split by hand soon after extraction, while the stone still holds its natural quarry moisture. These slates, called \"presents\", represent the oldest method, possibly dating from the Roman period.\n- **Stonesfield Slate**: split by frost along its natural bedding planes, giving thinner, more regular slates. These were used on prestigious buildings, including Oxford colleges.\n\n## Sizes\n\nSlates are laid in diminishing courses. The largest, about 600 mm (24 in) and occasionally up to 750 mm (30 in) long, form the double eaves course, known locally as \"cussoms\" and \"followers\". The smallest, \"short cocks\", are about 150 mm (6 in) long and were the most numerous, used near the ridge. Slaters traditionally used a range of local names for the intermediate sizes.\n\n## Roof form\n\n- **Pitch**: straight roofs are usually 47-55°.\n- **Fixing**: each slate is hung over a batten with one, sometimes two, cleft oak pegs through a hole near the top. Holes were once made with a pointed hammer and are now drilled.\n- **Ridges**: angled dressed stone, or roll-topped on more elaborate buildings such as churches.\n- **Valleys**: traditional swept valleys use specially cut slates to curve the roof through 90° in plan; a central wedge-shaped \"bottomer\" is held by side pieces. The guidance regards close-mitred or open lead valleys as cheaper but inferior.\n\nRoofs were deliberately allowed to bow slightly, which tightened the slates and helped shed rain and snow.\n\n## Weight and maintenance\n\nA Cotswold stone roof weighs about 1,000 kg per 10 m² (about 20 lb/ft²). Regular scraping to remove moss is recommended; with maintenance a roof can last about 100 years and possibly 200-300 years.\n\n## Conservation\n\nGuidance follows English Heritage policy: use new stone slates matching the original where possible, keep reclaimed slates on the building they came from, and avoid artificial, concrete, reconstituted or sawn slates on historic buildings. Imported limestone slates from the Côte d'Or in Burgundy, France, slightly more orange-yellow in colour, have been used successfully on some Cotswold projects.\n","key_facts":[{"label":"Rock","value":"Oolitic limestone (Forest Marble, Stonesfield Slate)"},{"label":"Pitch","value":"Usually 47-55°"},{"label":"Largest/smallest slates","value":"About 600 mm / 150 mm (24 in / 6 in)"},{"label":"Weight","value":"About 1,000 kg per 10 m²"}],"regions":["Europe"],"aliases":["Cotswold stone tile","Cotswold slate","Cotswold stone roof"],"related":["stone-slate","stonesfield-slate","collyweston-stone-slate"],"sources":[{"title":"Cotswold Stone Slate Roofing: Technical Guidance","url":"https://www.cotswold.gov.uk/media/hojnam3m/cotswold-stone-slate-roofing-technical-guidance-2000.pdf","publisher":"Cotswold District Council"},{"title":"Stone Slate Roofing: Technical Advice Note","url":"https://cms.historicengland.org.uk/images-books/publications/stone-slate-roofing-technical-advice-note/stoneslate","publisher":"Historic England (English Heritage)"}],"category":"materials","company":null,"country":null},{"slug":"counter-flashing","title":"Counter-Flashing","category":"components","type":"term","summary":"Counter-flashing is a cap of metal fixed into or onto a wall or chimney that covers the top edge of the base or step flashing beneath it.","body":"Counter-flashing, also called cap flashing or (in the UK) cover flashing, is the upper half of a two-part flashing system. The base flashing, such as step flashing, an apron or a membrane upstand, is attached to the roof and turned up the wall. The counter-flashing is attached to the wall and turned down over the top of the base flashing, overlapping it so that water running down the wall is carried out over the base flashing rather than behind it.\n\n## Why two parts\n\nRoofs and walls move differently with temperature, moisture and settlement, especially where a timber roof meets a masonry chimney. Separating the base flashing (fixed to the roof) from the counter-flashing (fixed to the wall) lets each move without tearing the joint open. Neither part is normally sealed rigidly to the other.\n\n## Fixing methods\n\n- **Reglet:** a groove is cut into a mortar joint or masonry, the bent top edge of the counter-flashing is inserted, and the joint is sealed or repointed.\n- **Stepped flashing:** on a sloping junction with brickwork, the counter-flashing is cut in steps so each step is let into a horizontal mortar joint. UK practice uses lead cover flashings in this way over soakers.\n- **Surface-mounted:** a termination bar or a profiled strip is fixed to the face of the wall and sealed at the top; generally considered less durable than a reglet.\n- **Through-wall flashing:** built into the wall during construction.\n\n## Materials\n\nLead is traditional in Britain and Europe; copper, aluminium, stainless and coated steel are common elsewhere. UK guidance commonly cites Code 4 lead as a minimum for cover flashings. Metal compatibility with the base flashing and the masonry needs to be considered.\n\n## Common faults\n\nSurface-applied counter-flashing that relies only on sealant, counter-flashing that is too short to lap the base flashing, and mortar joints that have eroded out of a reglet are common causes of leaks at chimneys and parapets.","key_facts":[{"label":"Also called","value":"Cap flashing, cover flashing"},{"label":"Fixing","value":"Reglet, stepped into joints, surface-mounted"},{"label":"UK lead (common minimum)","value":"Code 4"}],"regions":["Global"],"aliases":["cap flashing","cover flashing","counterflashing"],"related":["step-flashing","chimney-flashing","apron-flashing","lead-soakers","roof-flashing"],"company":null,"sources":[{"title":"Flashing (weatherproofing)","url":"https://en.wikipedia.org/wiki/Flashing_(weatherproofing)","publisher":"Wikipedia"},{"title":"How to get it right: Too much abutment flashing?","url":"https://www.labc.co.uk/news/how-get-it-right-too-much-abutment-flashing","publisher":"LABC"},{"title":"All About Roof Flashing","url":"https://www.greenbuildingadvisor.com/article/all-about-roof-flashing","publisher":"Green Building Advisor"}],"country":null},{"slug":"couvreur-zingueur","title":"Couvreur-Zingueur","category":"world-roofing","type":"term","summary":"The Parisian roofer who works zinc and slate; the skills of Paris roofers and ornamentalists joined UNESCO's intangible heritage list in 2024.","body":"A **couvreur-zingueur** is a French roofer who specialises in sheet zinc as well as slate and other coverings. In Paris the trade is closely tied to the city's 19th-century roofscape, where zinc covers about 80% of rooftops. In 2024, \"the skills of Parisian roofers and ornamentalists\" were inscribed on UNESCO's Representative List of the Intangible Cultural Heritage of Humanity.\n\n## The work\n\nCouvreurs-zingueurs cut, fold, solder and fit zinc sheet on site: they lay and replace roof sheets, form gutters, flashings and seams, and keep the steep mansards and flatter upper slopes of Haussmann-era buildings watertight. Paris roofers also work with slate, lead, clay tiles and copper. Their companions, the **ornemanistes** (ornamentalists), work zinc in the workshop to make dormer windows and to reproduce or create roof ornaments such as stamped decoration and finials. Together the two trades restore the roofs of Haussmann buildings, and their work has included the roofs of Notre-Dame de Paris.\n\n## Origins\n\nThe trade grew with the use of rolled zinc as a building material in the early 19th century and expanded under the Second Empire (1852-1870), when Baron Haussmann's rebuilding of Paris lined the new boulevards with apartment blocks under zinc-and-slate mansard roofs. Zinc suited these roofs because it was inexpensive, easy to cut, solder and form, and light enough to allow lighter roof frames.\n\n## UNESCO inscription\n\nThe inscription was decided on 4 December 2024 by UNESCO's Intergovernmental Committee for the Safeguarding of the Intangible Cultural Heritage, meeting in Asunción, Paraguay. The application was led over about seven years by the GCCP, a Paris trade group for roofing, plumbing and heating firms, with support from local politicians and industry partners. The listing recognises a living practice handed down between generations; it is separate from the long-running proposal to inscribe the roofs of Paris themselves on the World Heritage List.\n\n## Today\n\nThe trade also contributes to improving the energy performance of old buildings through roof insulation and ventilation. Recruitment is a recurring concern: industry sources describe a shortage of several hundred young roofers in Paris and thousands of unfilled roofing jobs across France.\n\n## Related terms\n\n- *Couvreur*: roofer in general.\n- *Zingueur*: zinc worker.\n- *Ornemaniste*: maker of decorative roof metalwork.\n- *Lucarne*: dormer window.","key_facts":[{"label":"Meaning","value":"Roofer and zinc worker (French)"},{"label":"Main materials","value":"Zinc, slate, lead, tile, copper"},{"label":"UNESCO","value":"Intangible Cultural Heritage, Representative List, 2024"},{"label":"Committee decision","value":"4 December 2024, Asunción"},{"label":"Paris rooftops in zinc","value":"About 80%"}],"regions":["Europe"],"aliases":["couvreurs-zingueurs","Parisian roofers","ornemanistes","skills of Parisian roofers and ornamentalists"],"related":["zinc-roofs-of-paris","zinc-roofing","mansard-roof-history","roofing-in-france","notre-dame-de-paris-roof-fire"],"company":null,"sources":[{"title":"Verriers, forains, couvreurs : trois pratiques du patrimoine immatériel à l'honneur","url":"https://www.culture.gouv.fr/actualites/verriers-forains-couvreurs-trois-pratiques-du-patrimoine-immateriel-a-l-honneur","publisher":"Ministère de la Culture"},{"title":"Protecting the work of the Parisian roofer","url":"https://vmzinc.com/news/protecting-the-work-of-the-parisian-roofer","publisher":"VMZINC"},{"title":"Toits de Paris","url":"https://fr.wikipedia.org/wiki/Toits_de_Paris","publisher":"Wikipédia"}],"country":null},{"slug":"cover-board","title":"Cover Board","category":"low-slope-systems","type":"term","summary":"A thin, firm board laid over roof insulation, or over an old roof, to protect it and provide a solid, compatible surface for the membrane.","body":"A cover board is a rigid panel installed between the insulation and the roof membrane in a low-slope roof. It is typically 6-13 mm (1/4-1/2 in) thick. While insulation boards are chosen mainly for thermal value, a cover board is chosen for strength and surface quality.\n\n## Functions\n\n- protects softer insulation from foot traffic, equipment, hail and dropped tools\n- provides a smooth, sound substrate for adhering membranes, improving wind-uplift resistance\n- separates incompatible materials, for example polystyrene from solvent adhesives or plasticised membranes\n- improves fire performance of assemblies over foam insulation\n- serves as a recovery board over an existing roof before a new membrane is installed\n\n## Common types\n\n- **Glass-mat gypsum board:** non-combustible, moisture-resistant facers; widely used under adhered single-ply.\n- **High-density (HD) polyiso:** lightweight, moisture-tolerant cover board made by the polyiso industry.\n- **Wood fibreboard:** traditional, used especially under hot-mopped BUR and modified bitumen.\n- **Perlite board:** an older mineral board used under bituminous systems.\n- **Cement and mineral boards, dense stone wool and asphaltic core boards** in some systems.\n\n## Installation\n\nCover boards are mechanically fastened along with the insulation or adhered with foam or hot adhesive. Joints are offset from insulation joints. For adhered membranes, the bond strength of the board's facer to its core often governs the wind rating of the whole assembly, so boards must be listed in the tested system.\n\n## Recovery and fire\n\nIn reroofing, a recovery board laid over a sound existing membrane provides a clean, flat surface for the new roof. Non-combustible gypsum-based boards are also used to help foam-insulated assemblies achieve fire classifications in listed systems.","key_facts":[{"label":"Typical thickness","value":"6-13 mm (1/4-1/2 in)"},{"label":"Common types","value":"Glass-mat gypsum, HD polyiso, wood fibreboard, perlite"},{"label":"Main purpose","value":"Protection and membrane substrate"}],"regions":["North America","Global"],"aliases":["coverboard","recovery board","roof cover board","overlay board"],"related":["roof-insulation","polyiso-insulation","fully-adhered-roof-system","mineral-wool-roof-insulation"],"company":null,"sources":[{"title":"Polyiso insulation","url":"https://www.polyiso.org/","publisher":"Polyisocyanurate Insulation Manufacturers Association"},{"title":"Built-Up Roofing (BUR): What It Is, Types, Issues & More","url":"https://roofonline.com/built-up-roofing-introduction/","publisher":"RoofOnline"}],"country":null},{"slug":"crannog","title":"Crannog","category":"history","type":"article","summary":"An artificial island dwelling in a lake, bog or estuary in Scotland and Ireland, typically topped by a roundhouse with a conical roof.","body":"A crannog is a partly or entirely artificial island built in a lake, loch, bog or estuary, found mainly in Scotland and Ireland. Unlike the pile dwellings of the Alps, which were built on lake shores and later flooded, crannogs were built out in the water. Most supported one or more roundhouses, so the typical crannog roof is the conical thatched roof of the British and Irish roundhouse.\n\n## Dates and numbers\n\nCrannogs were used over more than five millennia, from the Neolithic to the 17th or early 18th century. Eilean Dòmhnuill on North Uist, with radiocarbon dates of 3650-2500 BCE, is the earliest known constructed crannog. In Ireland they appear in Middle Bronze Age layers at Ballinderry (1200-600 BCE) and were most common in the Early Historic period. In Scotland, construction peaked between about 800 BCE and 200 CE; Oakbank on Loch Tay belongs to the Late Bronze Age-Early Iron Age. Ireland has an estimated 1,200 crannogs; Scotland has 389 officially listed sites, though estimates range from about 350 to 500 depending on definition.\n\n## Construction\n\nMethods depended on local materials. Where timber was plentiful, the island was often ringed by sharpened piles, sometimes joined by mortise and tenon, and built up with clay, peat, stone, timber and brush. In treeless areas such as the Outer Hebrides, builders used stone. Causeways or logboats gave access. Surviving crannogs are typically 8-25 m (26-82 ft) across.\n\n## Roofs\n\nWaterlogging preserves timbers, piles and floor deposits far better than dry sites, but roof coverings rarely survive. At Oakbank, bracken, rushes or straw may have been used for thatch. The reconstruction built by the Scottish Crannog Centre near Kenmore on Loch Tay, following experimental work led by Nicholas Dixon and Barrie Andrian in 1994-1997, has a conical roof of water reed from the River Tay fixed with ties and hazel spars over rafters, ring beams and hazel purlins. A steep pitch was considered crucial so that snow and rain would not lie on the roof.\n\nThe Loch Tay reconstruction was seriously damaged by fire in June 2021. A replacement crannog, built with traditional skills including thatching and hazel coppicing, was unveiled on 22 May 2026.\n\n## Significance for roofing history\n\nCrannogs show roundhouse roofs adapted to an exposed, wet setting, and their waterlogged deposits are among the best sources for the timber frames beneath prehistoric thatch. The 2021 fire also illustrated a long-standing hazard of thatched roofs on open hearths.","key_facts":[{"label":"Regions","value":"Scotland and Ireland (one known in Wales)"},{"label":"Earliest","value":"Eilean Domhnuill, North Uist, 3650-2500 BCE"},{"label":"Numbers","value":"About 1,200 in Ireland; 350-500 in Scotland"},{"label":"Typical diameter","value":"8-25 m (26-82 ft)"},{"label":"Reconstruction roof","value":"Water reed thatch, Loch Tay"}],"regions":["Europe"],"aliases":["crannóg","lake dwelling","artificial island dwelling"],"related":["bronze-age-roundhouse","must-farm","water-reed-thatch","irish-thatch","prehistory-of-roofing"],"company":null,"sources":[{"title":"Crannog","url":"https://en.wikipedia.org/wiki/Crannog","publisher":"Wikipedia"},{"title":"Crannogs and Thatch","url":"https://www.thatchadvicecentre.co.uk/articles/crannogs-and-thatch","publisher":"Thatch Advice Centre"},{"title":"Scottish Crannog Centre unveils new building","url":"https://www.museumsassociation.org/museums-journal/news/2026/05/scottish-crannog-centre-unveils-new-building/","publisher":"Museums Association"}],"country":null},{"slug":"creaton","title":"Creaton","category":"manufacturers","type":"company","summary":"Creaton is a German clay roof tile manufacturer based in Wertingen, Bavaria, dating to 1884 and owned by Wienerberger since 2024.","body":"Creaton GmbH is a German manufacturer of clay roof tiles, based in Wertingen in Bavaria. It is the market leader in Germany for the traditional Biberschwanz (plain or beaver-tail) clay tile. The company's history starts in 1884, when Alois Berchtold founded a brickworks in Wertingen. Since 2024 Creaton has been part of the Austrian group Wienerberger.\n\n## History\n\n- **1884**: Alois Berchtold founds a brickworks in Wertingen.\n- **1934**: Anton Ott founds a works in Autenried.\n- **1992**: The Berchtold and Ott businesses merge as Creaton Berchtold & Ott GmbH.\n- **1995**: Conversion to a stock corporation and stock-market listing.\n- **2005**: The Belgian building-materials group Etex becomes majority shareholder.\n- **2008-2009**: The German Federal Cartel Office fines Creaton and other tile manufacturers a combined EUR 188 million for price-fixing.\n- **2017**: Delisting after a squeeze-out of minority shareholders.\n- **2018**: Conversion from an AG to a GmbH.\n- **2020-2021**: Combination with the French clay tile group Terreal.\n- **January 2023**: The Federal Cartel Office clears Wienerberger's takeover of Terreal, including Creaton.\n- **March 2024**: Wienerberger completes the takeover; Creaton's Polish and Hungarian plants are transferred to Swisspor.\n\n## Products\n\nCreaton makes plain (Biberschwanz) tiles, which are laid in overlapping double or crown courses typical of southern Germany and Austria, as well as pressed single-lap clay tiles. Its range also covers concrete roof tiles, roof accessories, mounting systems for photovoltaic panels, and facade tiles.\n\n## Context\n\nGerman pitched-roof practice relies heavily on clay and concrete tiles over battens with a secondary underlay, and the Biberschwanz tile is a defining feature of traditional Bavarian and Franconian roofscapes.","key_facts":[{"label":"Roots","value":"1884, Wertingen"},{"label":"Headquarters","value":"Wertingen, Bavaria, Germany"},{"label":"Parent","value":"Wienerberger (since March 2024)"},{"label":"Known for","value":"Biberschwanz clay plain tiles"}],"regions":["Europe"],"aliases":["Creaton GmbH","Creaton AG","Creaton Berchtold & Ott"],"related":["clay-roof-tile","plain-tile","beaver-tail-tile","wienerberger","terreal"],"company":{"founded":"1884","headquarters":"Wertingen, Germany","website":"https://www.creaton.de","parent":"Wienerberger","known_for":["Biberschwanz clay tiles","Pressed clay roof tiles"]},"sources":[{"title":"Creaton","url":"https://de.wikipedia.org/wiki/Creaton","publisher":"Wikipedia (German)"},{"title":"Terreal","url":"https://fr.wikipedia.org/wiki/Terreal","publisher":"Wikipedia (French)"},{"title":"Wienerberger","url":"https://en.wikipedia.org/wiki/Wienerberger","publisher":"Wikipedia"}],"country":null},{"slug":"creep-in-sheet-metal","title":"Creep in Lead and Zinc Roofing","category":"problems-maintenance","type":"term","summary":"Creep is the slow, permanent stretching of soft metals such as lead and zinc under their own weight and repeated thermal movement, causing thinning and tears.","body":"Creep is a gradual deformation of a material held under constant load. On roofs it affects soft, heavy metals, above all lead, and to a lesser degree zinc. Gravity pulls the sheet down the slope, and daily heating and cooling repeatedly stresses it, so over years the metal stretches, thickens at the bottom, thins at the top and can eventually crack or tear.\n\n## Lead\n\nUS preservation guidance notes that lead roofs tear because of creep, the gravitational stress that moves the metal down the slope. Lead roofing practice in the UK manages creep by:\n\n- limiting the size of each bay and piece for each lead code;\n- breaking long runs with drips and rolls;\n- fixing sheets at the top and along edges in patterns set out in the Lead Sheet Association manual;\n- avoiding over-long pieces, which raise the risk of creep and fatigue cracking.\n\n## Zinc\n\nUnalloyed zinc can also creep. Architectural titanium-zinc includes about 0.06 to 0.2% titanium specifically to improve creep resistance, alongside copper for strength. Without it, zinc panels can thicken towards the eaves and slide gradually down the roof.\n\n## Other metals\n\nCopper, steel, stainless steel and aluminium are much less prone to creep at roof temperatures; their main movement concern is thermal expansion and contraction.\n\n## Signs of creep\n\n- Sagging or bulging sheets, thickening near lower edges.\n- Fixings pulled through or elongated nail holes at the top of bays.\n- Splits at fold lines and at the head of sheets.\n\nRepairs usually involve replacing affected bays with correctly sized pieces rather than patching.","key_facts":[{"label":"Most affected metal","value":"Lead"},{"label":"Zinc countermeasure","value":"Titanium alloying (0.06-0.2%)"},{"label":"Lead countermeasure","value":"Limited bay sizes, drips, rolls, correct fixing"}],"regions":["Global"],"aliases":["metal creep","lead creep","zinc creep"],"related":["lead-roofing","zinc-roofing","lead-sheet-codes","thermal-movement-in-metal-roofs"],"company":null,"sources":[{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"},{"title":"Essential Zinc: Building for the Future","url":"https://continuingeducation.bnpmedia.com/courses/umicore-building-products-usa-inc/essential-zinc-building-for-the-future/2/","publisher":"Continuing Education Center (BNP Media) / Umicore Building Products"},{"title":"The top ten dos and don'ts of rolled lead sheet","url":"https://ribaj.com/products/the-top-ten-dos-and-don-ts-of-rolled-lead-sheet","publisher":"RIBA Journal"}],"country":null},{"slug":"cricket-roofing","title":"Cricket (Saddle)","category":"low-slope-systems","type":"term","summary":"A small raised ridge built on a roof to divert water around a chimney, curb or other obstruction, or between drains on a low-slope roof.","body":"A cricket, also called a saddle, is a ridged structure that sends water around the high side of an obstruction or between low points so it does not collect. On steep-slope roofs crickets sit behind chimneys and large skylights. On low-slope roofs they are an essential part of the drainage layout.\n\n## On low-slope roofs\n\nCrickets are placed:\n\n- between roof drains along a drain line, where the two slopes would otherwise meet at a flat valley\n- on the upslope side of HVAC curbs, rooflights and plant plinths\n- along parapets, to move water toward scuppers or corner drains\n- at the junction of two roof areas with different falls\n\nThey run against or perpendicular to the main slope. Because water travelling along the cricket's valley has only the cricket's slope to drive it, crickets are commonly built at least 50% steeper than the field of the roof to reduce ponding.\n\n## Construction\n\nOn low-slope roofs crickets are usually made from tapered insulation boards cut to shape and covered by the same membrane as the field. Timber framing or lightweight fill are alternatives. Small crickets on steep-slope roofs are often sheet metal.\n\n## Design\n\nCricket layout is part of the tapered insulation drawing. Designers check that water flowing along cricket valleys reaches outlets without creating flat spots, and UK guidance recommends crickets where falls are interrupted behind obstructions.\n\n## Common mistakes\n\nCrickets that are too small or too shallow leave water standing at curbs and between drains. Guidance on ponding lists interrupted falls behind rooflights and plant plinths among its common causes, and recommends crickets to divert water in such areas.","key_facts":[{"label":"Also called","value":"Saddle"},{"label":"Typical slope","value":"Commonly at least 1.5 times the main roof slope"},{"label":"Common material (low slope)","value":"Tapered insulation"}],"regions":["Global"],"aliases":["saddle","roof cricket","drainage cricket"],"related":["tapered-insulation","positive-drainage","roof-drain","ponding-water","scupper"],"company":null,"sources":[{"title":"Cricket (roofing)","url":"https://en.wikipedia.org/wiki/Cricket_(roofing)","publisher":"Wikipedia"},{"title":"How to avoid ponding on flat roofs","url":"https://www.specifiedby.com/soprema-uk/news/how-to-avoid-ponding-on-flat-roofs","publisher":"Soprema UK via SpecifiedBy"},{"title":"Rules for long-lasting BUR systems (H. H. Pierce, Interface, Oct 2006)","url":"https://iibec.org/wp-content/uploads/2006-10-Pierce.pdf","publisher":"IIBEC"}],"country":null},{"slug":"cross-gabled-roof","title":"Cross-Gabled Roof","category":"roof-forms","type":"term","summary":"A cross-gabled roof combines two or more gable roofs that intersect, usually at right angles, over an L-, T- or cross-shaped plan.","body":"A cross-gabled roof is formed when two or more gable roofs meet, usually at right angles, so that their ridges cross or join. It is the standard way to roof a building whose plan is L-shaped, T-shaped or cruciform, and it is extremely common in houses in North America, the UK, Australia and elsewhere. The equivalent arrangement with hipped roofs is called cross-hipped, or in UK usage, hip-and-valley.\n\n## Geometry\n\nWhere the two roofs meet, internal corners form valleys, and the main ridge may continue through or be met by the secondary ridge at a lower or equal height. Each wing ends in its own gable, so a cross-gabled house presents gables to two or more directions, which architects use to create variety in the elevations.\n\n## Construction\n\n- **Framing:** valley rafters or valley boards on the main roof carry jack rafters of the intersecting roof. With trusses, the secondary roof is often built over the sheathing of the main roof using valley sets (\"California framing\" in North America).\n- **Valleys:** the valleys need extra underlayment and an open, closed-cut or woven valley detail in shingles, or a lined valley in tile and slate.\n- **Ventilation:** each roof section needs its own path for intake and exhaust air, which can be complicated by valley framing that blocks airflow.\n\n## Advantages\n\n- Follows complex house plans and allows large attic spaces in each wing.\n- Gable walls in each wing can carry windows and vents.\n- Visual interest compared with a single gable.\n\n## Disadvantages\n\n- More valleys mean more places where water concentrates and leaks can occur.\n- Multiple gable ends share the wind vulnerability of simple gable roofs.\n- Snow can drift into valleys and against higher roof sections.","key_facts":[{"label":"Plan","value":"L, T or cruciform"},{"label":"Key junctions","value":"Valleys"},{"label":"Hipped equivalent","value":"Cross-hipped / hip-and-valley"}],"regions":["Global"],"aliases":["cross gable roof","intersecting gable roof","cross-gable"],"related":["gable-roof","roof-valley","hip-roof"],"company":null,"sources":[{"title":"Gable","url":"https://en.wikipedia.org/wiki/Gable","publisher":"Wikipedia"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"},{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"}],"country":null},{"slug":"crystal-palace","title":"Crystal Palace","category":"history","type":"place","summary":"Joseph Paxton's iron-and-glass hall for the Great Exhibition of 1851, with a ridge-and-furrow glass roof of about 293,000 panes.","body":"The **Crystal Palace** was a vast prefabricated building of cast iron and plate glass, designed by **Joseph Paxton** to house the **Great Exhibition** in Hyde Park, London, from 1 May to 15 October 1851. Its glass roof and walls made it one of the most influential buildings of the 19th century and a forerunner of modern prefabricated, modular construction.\n\n## Origins\n\nPaxton was a gardener and glasshouse designer. He developed his ideas at **Chatsworth**, where he built the Great Conservatory and a house for the giant Amazonian waterlily *Victoria regia* after it first flowered there in 1849. That lily house used flat ridge-and-furrow glazing and a cantilevered glass curtain wall; Paxton said the lily's ribbed leaves were an inspiration. His first sketch for the Crystal Palace, drawn on blotting paper at a railway board meeting in Derby, is in the Victoria and Albert Museum.\n\n## The roof\n\nPaxton's **ridge-and-furrow** roof used long rows of glass laid in triangular prisms that shed rain into the valleys between them. Rain ran into timber channels in the furrows. These channels also served as rails for glaziers' trolleys during construction, and the system later became widely known as the **\"Paxton gutter\"**.\n\n## Glass and size\n\nThe glass was made by **Chance Brothers** of Smethwick. Each pane was about 49 by 10 in (1.24 m by 0.25 m), the largest then available, and the whole building's grid was based on this size. Sources cite about **293,000 panes**. The building was about 1,848 by 456 ft (563 by 139 m), with an exhibition space of about 990,000 sq ft (92,000 m²). Sources disagree on how quickly it was built, giving both thirty-nine weeks and five months.\n\n## Later history\n\nAfter the exhibition the building was dismantled and rebuilt on Sydenham Hill in south London from 1852; Queen Victoria reopened it on 10 June 1854. It was destroyed by fire on **30 November 1936**. The cause is unknown; an electrical fault in old wiring is suspected.\n\n## Significance\n\nThe Crystal Palace showed that a huge roof could be made of standard, factory-made components and assembled quickly. It remains a key reference in the history of glazed roofs and prefabricated building.","key_facts":[{"label":"Designer","value":"Joseph Paxton"},{"label":"Great Exhibition","value":"1 May - 15 October 1851"},{"label":"Glass panes","value":"About 293,000, by Chance Brothers"},{"label":"Pane size","value":"About 49 x 10 in (1.24 x 0.25 m)"},{"label":"Destroyed","value":"30 November 1936"}],"regions":["Europe"],"aliases":["Great Exhibition building","Paxton's Crystal Palace"],"related":["joseph-paxton"],"company":null,"sources":[{"title":"The Crystal Palace","url":"https://en.wikipedia.org/wiki/The_Crystal_Palace","publisher":"Wikipedia"},{"title":"Joseph Paxton","url":"https://en.wikipedia.org/wiki/Joseph_Paxton","publisher":"Wikipedia"}],"country":null},{"slug":"csa-a123-21","title":"CSA A123.21","summary":"CSA A123.21 is a Canadian test method that measures the wind uplift resistance of membrane roofing systems under dynamic, gust-like loading.","body":"CSA A123.21, *Standard test method for the dynamic wind uplift resistance of membrane-roofing systems*, is published by CSA Group in Canada. Unlike static tests such as [UL 1897](/ul-1897) or [ANSI/FM 4474](/fm-4474), it applies a sequence of fluctuating pressures derived from records of real wind, so that the roof experiences the gusting and cycling that can fatigue fasteners and seams over time.\n\nThe method was developed from research by the National Research Council of Canada (NRC) and an industry consortium known as SIGDERS (Special Interest Group for Dynamic Evaluation of Roofing Systems). It has been revised several times: the 2004 edition (reaffirmed 2009) was replaced by a 2010 edition, then by a 2014 edition, and a 2020 edition is listed by standards databases.\n\n## What it covers\n\nThe standard has two methods:\n\n- **Method 1** – mechanically attached, reinforced membrane systems, within limits on fastener row spacing (up to 2,896 mm / 114 in) and fastener spacing within rows (up to 610 mm / 24 in).\n- **Method 2** – systems where components are adhered to resist uplift, without mechanical fasteners or ballast.\n\nThe test applies load cycles at increasing pressure levels until the system fails or completes the sequence. The highest level completed sets the system's rated resistance.\n\n## Code status\n\nThe National Building Code of Canada references CSA A123.21 for determining the wind uplift resistance of membrane roofing systems. Designers compare the rated resistance with the factored wind load calculated for the building under Part 4 of the NBC, considering roof zones (field, perimeter and corners).\n\nThe Canadian Roofing Contractors Association (CRCA) has published an application policy on how the standard should be used, reflecting debates over interpreting test results and applying them to different roof areas.\n\n## Why dynamic testing matters\n\nMechanically attached single-ply membranes billow and flutter in wind. Static pressure tests can overstate their capacity because they do not reproduce repeated loading. Dynamic tests aim to capture failure modes such as fastener pull-out after many cycles, seam peel, and membrane tearing at plates.","key_facts":[{"label":"Publisher","value":"CSA Group"},{"label":"Load type","value":"Dynamic, based on recorded wind pressure"},{"label":"Methods","value":"1: mechanically attached; 2: adhered"},{"label":"Editions","value":"2004, 2010, 2014, 2020"},{"label":"Referenced by","value":"National Building Code of Canada"}],"regions":["North America"],"aliases":["CSA A123.21","CAN/CSA-A123.21","dynamic wind uplift test"],"related":["ul-1897","fm-4474","national-building-code-of-canada","single-ply-roofing"],"sources":[{"title":"CSA A123.21-10 Standard test method for the dynamic wind uplift resistance of membrane-roofing systems","url":"https://scc-ccn.ca/standardsdb/standards/4025779","publisher":"Standards Council of Canada"},{"title":"A123.21-20","url":"https://standards.globalspec.com/std/14213197/a123-21-20","publisher":"GlobalSpec"},{"title":"Test Standard CSA A123.21 Application Policy","url":"https://roofingcanada.com/wp-content/uploads/2026/06/Test-Standard-CSA-A123.21-Application-Policy-November-2023.pdf","publisher":"Canadian Roofing Contractors Association"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"cspe-hypalon-roofing","title":"CSPE (Hypalon) Roofing","category":"low-slope-systems","type":"term","summary":"Single-ply roofing made from chlorosulfonated polyethylene, sold mainly as DuPont Hypalon; production for the Americas ended in 2010.","body":"CSPE (chlorosulfonated polyethylene), also designated CSM, is a synthetic rubber made by treating polyethylene with chlorine and sulfur dioxide. It was best known under DuPont's trademark Hypalon. For roofing it was made into single-ply membrane sheets for flat roofs.\n\n## Use in roofing\n\nCSPE and related CPE membranes were used on low-slope roofs from about 1964. The same material was widely used for geomembranes, pond liners, inflatable boats, cable jackets and automotive hoses.\n\n## Discontinuation\n\nOn 7 May 2009 DuPont announced it would close its plant in Beaumont, Texas, its only CSM plant, by 30 June 2009, as it was leaving the Hypalon business. At customers' request closure was delayed until 20 April 2010. This ended supply of DuPont Hypalon in the Americas. Most other roofing membrane makers stopped producing CSPE sheets within a few years, and CSPE roofing had almost disappeared by about 2011. CSM rubber is still produced elsewhere, notably by Tosoh in Japan and manufacturers in China, but not generally for roofing.\n\n## Alternatives\n\nIn geomembrane applications, industry advisers suggested switching to other resins such as flexible polypropylene once Hypalon left the American market. In roofing, owners and designers turned mainly to PVC, KEE, TPO and EPDM.\n\n## Existing roofs\n\nSome CSPE roofs remain in service. With new CSPE sheet no longer generally available for roofing, owners reroofing these buildings choose a different membrane system.\n\n## Material characteristics\n\nCSM rubber is cured with metal oxides, enabled by the reactive chlorosulfonyl groups introduced during manufacture. Outside roofing it has been prized for long life and resistance to salt water and sunlight, which explains its long use in professional and military inflatable boats.","key_facts":[{"label":"Material","value":"Chlorosulfonated polyethylene (CSM)"},{"label":"Trade name","value":"Hypalon (DuPont)"},{"label":"Roofing use","value":"From the 1960s"},{"label":"DuPont plant closed","value":"20 April 2010"},{"label":"Status","value":"Effectively discontinued for roofing"}],"regions":["North America","Global"],"aliases":["Hypalon","CSPE","CSM","chlorosulfonated polyethylene"],"related":["single-ply-roofing","epdm-roofing","pvc-roofing"],"company":null,"sources":[{"title":"Hypalon","url":"https://en.wikipedia.org/wiki/Hypalon","publisher":"Wikipedia"},{"title":"Availability of Hypalon","url":"https://geosyntheticsmagazine.com/2010/10/01/availability-of-hypalon/","publisher":"Geosynthetics Magazine"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"}],"country":null},{"slug":"cupa-pizarras","title":"Cupa Pizarras","category":"manufacturers","type":"company","summary":"Cupa Pizarras is a Spanish producer of natural roofing slate operating since 1892, part of Cupa Group, with quarries in Galicia and exports to over 60 countries.","body":"Cupa Pizarras is a Spanish producer of natural slate for roofing and cladding, and the slate business of Cupa Group. It has been producing since 1892 and is based in Sobradelo de Valdeorras, in the province of Ourense in Galicia, north-west Spain. Cupa Group describes Cupa Pizarras as the world leader in natural slate.\n\n## Group\n\nCupa Group comprises 79 companies, with subsidiaries in nine countries, about 30 quarries and more than 2,800 employees. It exports to more than 70 countries across five continents; Cupa Pizarras itself cites exports to more than 60 countries. The group also includes a natural stone business, Cupa Stone.\n\n## Products\n\n- **Roofing slates**: natural slates split and cut to size for pitched roofs.\n- **READYSLATE**: a pre-assembled, lightweight natural slate roofing system intended to speed up installation.\n- **CUPACLAD**: a ventilated rainscreen facade system using natural slate.\n\n## Natural slate roofing\n\nRoofing slate is a fine-grained metamorphic rock that can be split into thin, durable sheets, which are fixed with hooks or nails over battens. Quality is assessed against product standards such as EN 12326 in Europe and ASTM C406 in North America, which cover properties including water absorption, freeze-thaw resistance and the presence of oxidisable minerals.\n\n## Installation\n\nIn Spain and France slates are commonly fixed with stainless-steel hooks, while in the UK and Ireland nailing is traditional. Each slate overlaps the course two rows below it, a pattern known as double-lap roofing, so that water running off one slate is always shed onto another.","key_facts":[{"label":"Producing since","value":"1892"},{"label":"Location","value":"Sobradelo de Valdeorras, Ourense, Spain"},{"label":"Group","value":"Cupa Group (79 companies, about 30 quarries)"},{"label":"Exports","value":"60+ countries"}],"regions":["Europe","Global"],"aliases":["CUPA PIZARRAS","Cupa Group"],"related":["natural-slate","en-12326","slate-hook-fixing"],"company":{"founded":"1892","headquarters":"Sobradelo de Valdeorras, Ourense, Spain","website":"https://www.cupapizarras.com","parent":"Cupa Group","known_for":["Natural roofing slate","READYSLATE system","CUPACLAD slate cladding"]},"sources":[{"title":"Cupa Pizarras","url":"https://www.cupapizarras.com/","publisher":"Cupa Pizarras"},{"title":"Cupa Group","url":"https://www.cupagroup.com/","publisher":"Cupa Group"}],"country":null},{"slug":"cycladic-flat-roof","title":"Cycladic Flat Roof","type":"article","summary":"Whitewashed flat masonry roof of the Greek Cyclades, built for a dry, windy climate and used to collect rainwater; often paired with domed churches.","body":"The flat, whitewashed roof is one of the defining features of village architecture in the Cyclades, the Aegean island group that includes Santorini, Mykonos, Naxos and Paros. Box-like houses with flat roofs step up hillsides, with domed churches rising among them.\n\n## Why flat?\n\nSeveral conditions favoured flat roofs in the Cyclades:\n\n- **Low rainfall** - the islands are dry, so a flat roof drains adequately if it is kept in good repair.\n- **Scarce timber** - long timber for pitched roof structures was hard to obtain on small, treeless islands, so spans were kept short.\n- **Strong winds** - the summer *meltemi* winds favour compact, low-profile buildings.\n- **Water collection** - flat roofs act as catchments that feed rainwater into cisterns.\n\n## Construction\n\nTraditional flat roofs were built over short spans of timber beams or, on some islands, masonry vaults, with layers of smaller sticks or reeds, and a thick layer of earth or local volcanic and clay materials, sloped gently to spouts. The surface was finished with lime. On Santorini, many houses were built as barrel vaults or carved into the soft volcanic rock of the caldera, and the air-filled pumice in the surroundings provides insulation.\n\n## Whitewash\n\nHouses and roofs are coated with white lime wash, renewed regularly. The lime keeps surfaces cooler in strong sun, and its use is also linked to keeping roofs clean so that collected rainwater is usable. Whitewashing has an aesthetic role as well, and on islands like Santorini it is now part of planning rules.\n\n## Domes\n\nChurches are usually covered with small domes on drums. On Santorini the domes of churches in villages such as Oia are often painted blue, producing the familiar white-and-blue image of the islands.\n\n## Earthquakes and conservation\n\nThe islands are seismic. The 1956 earthquake caused major damage on Santorini and was followed by emigration and later by building restrictions. A preservation programme from 1976 converted many abandoned cave houses into guest houses and hotels. Today, most new buildings use reinforced concrete flat roofs with modern waterproofing, finished white to match the tradition.","key_facts":[{"label":"Region","value":"Cyclades, Greece"},{"label":"Roof form","value":"Flat or barrel-vaulted masonry"},{"label":"Finish","value":"Lime whitewash"},{"label":"Function","value":"Rainwater collection to cisterns"}],"regions":["Europe"],"aliases":["Cycladic architecture","Santorini roof","Greek island flat roof"],"related":["roofing-in-greece","flat-roof","rainwater-harvesting-roofs","middle-eastern-domes"],"sources":[{"title":"Oia, Greece","url":"https://en.wikipedia.org/wiki/Oia,_Greece","publisher":"Wikipedia"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"},{"title":"Architecture of Greece","url":"https://en.wikipedia.org/wiki/Architecture_of_Greece","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"dach-holz-international","title":"DACH+HOLZ International","type":"event","summary":"DACH+HOLZ International is a German trade fair for roofing, timber construction and building envelope trades, held in Cologne or Stuttgart.","body":"DACH+HOLZ International is a trade fair in Germany for the roofing and timber construction sectors. Its name combines the German words for \"roof\" (Dach) and \"wood\" (Holz). It is aimed at roofers, carpenters and timber builders, and plumbers and sheet-metal workers (Klempner), and it covers products for pitched and flat roofs, walls, timber structures, tools and machinery. Its website is dach-holz.com.\n\n## Organiser and schedule\n\nThe fair is organised by GHM Gesellschaft für Handwerksmessen mbH, a Munich-based company that runs trade fairs for skilled crafts. Editions alternate between host cities. The 2026 edition was held over four days in Cologne, and the next edition is scheduled for 7-10 March 2028 at Messe Stuttgart. Recent listings point to a two-year cycle.\n\n## Content\n\nTypical exhibitors include manufacturers of:\n\n- clay and concrete roof tiles, natural slate and fibre cement;\n- metal roofing and façade systems, including zinc, copper, aluminium and coated steel;\n- flat roof waterproofing such as bitumen, synthetic membranes and liquid systems;\n- insulation, underlays, roof windows and skylights;\n- timber products, engineered wood and timber connectors;\n- tools, scaffolding, fall protection, cranes and vehicles;\n- rooftop solar systems and green roof components.\n\nThe fair also hosts talks, live demonstrations and competitions for apprentices and young tradespeople. German trade associations for roofing, carpentry and sheet-metal work take part as partners.\n\n## Context\n\nGermany has a large and highly organised roofing trade, represented nationally by the Zentralverband des Deutschen Dachdeckerhandwerks (ZVDH). DACH+HOLZ is one of the main meeting points for this trade and for timber construction in German-speaking Europe. Other relevant European events include BAU in Munich, which covers the wider building materials market, and Batimat in Paris. In North America, the International Roofing Expo serves a similar role for roofing contractors.","key_facts":[{"label":"Sectors","value":"Roofing, timber construction, sheet-metal work"},{"label":"Organiser","value":"GHM Gesellschaft für Handwerksmessen mbH, Munich"},{"label":"Venues","value":"Cologne and Stuttgart (alternating)"},{"label":"Next edition","value":"7-10 March 2028, Stuttgart"}],"regions":["Europe"],"aliases":["DACH + HOLZ","Dach und Holz"],"related":["zvdh","bau-munich","international-roofing-expo"],"company":{"website":"https://www.dach-holz.com","parent":"GHM Gesellschaft für Handwerksmessen mbH","known_for":["Roofing and timber construction trade fair"]},"sources":[{"title":"DACH+HOLZ International","url":"https://www.dach-holz.com/","publisher":"GHM"},{"title":"DACH+HOLZ International (English)","url":"https://www.dach-holz.com/en/","publisher":"GHM"}],"category":"organizations","country":null},{"regions":["Europe"],"company":null,"slug":"dalmatian-stone-slab-roof","title":"Dalmatian Stone Slab Roof","category":"world-roofing","type":"term","summary":"Traditional roofs of thin limestone slabs (kamene ploče) on houses and dry-stone huts (bunje) of the Croatian Adriatic coast and islands.","aliases":["kamene ploče","Croatian stone roof","bunja","bunje"],"body":"Along the Croatian Adriatic coast and on its islands, traditional houses and field shelters were roofed with slabs of local limestone, in Croatian *kamene ploče* (\"stone slabs\"). These roofs used the same stone as the walls and fields around them and were once common before clay tiles replaced them.\n\n## Houses\n\nOn Dugi Otok, in the area now protected as Telašćica Nature Park, early houses were built of dry-laid stone, with one part for people and another for livestock, and roofed with natural stone slabs that needed little or no working. Later, walls were bound with a plaster of sand, lime and red soil, and ceilings were carried on timber beams. The park contains more than 200 small old houses. A typical house had a *konoba*, a cellar dug into the ground that stays cool in summer and warm in winter, with the kitchen (*kužina*) and its fireplace (*komin*) above.\n\n## Island quarries\n\nBuilders chose thin, light slabs for roofs. In Bol, on the island of Brač, houses were roofed with slabs quarried at a small site called Petrore, about a kilometre inland on the north coast of neighbouring Hvar; donkeys carried them to the shore and boats ferried them across the channel. The name may relate to the old Brač word *petrade*, \"quarries\". Small quarries with tool marks still survive on Hvar's north coast.\n\n## Dry-stone shelters\n\n- **Bunje** are small dry-built stone shelters covered with slabs, some of them round, built to shelter people in the fields from rain.\n- **Kućeri** are double-walled stone shelters on hilltops, built with the entrance facing away from the *bura* or *jugo* winds so that a shepherd could watch the flock.\n\nThese belong to the wider Mediterranean family of corbelled and slab-roofed dry-stone buildings that includes the trulli of Puglia and the giren of Malta.\n\n## Decline and revival\n\nModern roof tiles ended the use of stone slabs, and few original roofs survive outside museum-like houses and old photographs. Renewed interest in traditional architecture has brought stone slabs back in new forms.","key_facts":[{"label":"Material","value":"Thin limestone slabs"},{"label":"Region","value":"Dalmatian coast and islands"},{"label":"Related huts","value":"Bunje, kućeri"},{"label":"Status","value":"Largely replaced by clay tile; reviving"}],"related":["roofing-in-croatia","stone-slate","trulli-of-alberobello","roofing-in-malta","roofing-in-montenegro"],"sources":[{"title":"Construction","url":"https://pp-telascica.hr/construction/?lang=en","publisher":"Telašćica Nature Park"},{"title":"From which stone was Bol on the island of Brač built?","url":"https://www.croatiaweek.com/?p=113553","publisher":"Croatia Week"}],"country":null},{"slug":"darbazi","title":"Darbazi","category":"world-roofing","type":"term","regions":["Middle East","Europe"],"company":null,"summary":"Traditional Georgian house with a stepped, corbelled timber roof (gvirgvini) rising to a central smoke and light opening.","aliases":["gvirgvini","glkhatun","hazarashen","harazashen","karadam","kırlangıç kubbe","corbelled log roof","lantern roof"],"body":"The darbazi is a traditional house type of Georgia whose defining feature is its roof: a stepped, pyramid-like vault of logs called the *gvirgvini*, built up in layers that turn and narrow toward a central opening. The opening at the top serves both as a window and as the smoke outlet for the hearth below.\n\nThe name is Georgian, derived from the Persian *darvāze* (\"gate\"). Similar lantern roofs are known across Asia Minor and the South Caucasus: in Armenia they are called *glkhatun* or *hazarashen*, in Turkey *kırlangıç kubbe* or *kırlangıç örtü* (\"swallow dome\"), and in Azerbaijan *karadam*.\n\n## How the roof is built\n\nHewn logs and beams are laid in stepped courses, each projecting inward over the one below, so that the opening narrows as the roof rises until only the central hole remains. This is corbelling: no course spans the whole room, which is why the method can be built from comparatively short timbers. The vault rests on pillars, and a solid central timber upright called the *deda-bodzi* (\"mother pillar\") carries much of the weight of the corbelled roof. Houses were often set partly below ground, with finely carved beams and pillars.\n\n## History\n\nThe Roman writer Vitruvius, in the 1st century BC, described a dwelling of Colchis (western Georgia) built of stacked logs, and this is often cited as an ancient precursor of the darbazi. The type continued to be built into the 20th century, with regional variants. It is most associated with Kartli, Kakheti and Samtskhe-Javakheti. Scholars have suggested the form may have influenced early Georgian church design.\n\n## Related roofs\n\nThe darbazi is a timber relative of masonry corbelled domes found elsewhere (see khmer-corbel-vault and the stone corbelled roofs of the Hauran). It differs from the masonry domes of Iran and Turkey in using timber rather than brick or stone.","key_facts":[{"label":"Roof name","value":"Gvirgvini (stepped corbelled log vault)"},{"label":"Central support","value":"Deda-bodzi (\"mother pillar\")"},{"label":"Top opening","value":"Light and smoke outlet"},{"label":"Regions","value":"Kartli, Kakheti, Samtskhe-Javakheti (Georgia)"},{"label":"Armenian name","value":"Glkhatun / hazarashen"}],"related":["roofing-in-georgia","roofing-in-armenia","roofing-in-azerbaijan","roofing-in-turkey","khmer-corbel-vault","hauran-basalt-corbelled-roofs"],"sources":[{"title":"Darbazi","url":"https://en.wikipedia.org/wiki/Darbazi","publisher":"Wikipedia"},{"title":"Armenian architecture","url":"https://en.wikipedia.org/wiki/Armenian_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"davinci-roofscapes","title":"DaVinci Roofscapes","category":"manufacturers","type":"company","summary":"DaVinci Roofscapes is a US maker of composite (synthetic) slate and shake roofing tiles made from virgin resins, owned by Westlake.","body":"DaVinci Roofscapes is a US manufacturer of composite roofing tiles designed to look like natural slate and cedar shake. Its products are moulded from virgin polymer resins blended with ultraviolet (UV) stabilisers. The company was already part of Westlake when Westlake bought Boral's North American building products businesses in 2021, and it sits alongside Westlake's roofing tile businesses.\n\n## Products\n\n- **DaVinci Slate**: single-width and multi-width composite tiles imitating natural slate.\n- **DaVinci Shake**: tiles imitating hand-split cedar shakes.\n- **Select Shake**: a further shake-style line.\n- **Siding**: hand-split shake siding and other composite siding products.\n\n## Material\n\nComposite or synthetic roofing of this kind is made by injection-moulding polymer compounds into tiles with textured surfaces and varied widths, so that an installed roof shows the irregular appearance of natural slate or wood. Compared with natural slate, composite tiles are considerably lighter and can usually be cut and nailed with ordinary roofing tools; compared with wood shakes they do not rot or split. Their long-term weathering depends on the resin and UV stabiliser formulation, and colour blends are designed to reduce the visual effect of fading. Manufacturers typically test such products for impact resistance (for example to UL 2218) and fire performance.\n\n## Market\n\nComposite slate and shake are used on homes where owners want a slate or shake appearance without the weight or cost of natural materials, and in historic districts and homeowner associations that restrict roof appearance. DaVinci is one of several North American producers in this segment, along with companies such as EcoStar.\n\n## Ownership\n\nWestlake, a Houston-based chemicals and building-products company, also makes PVC and other polymers, and markets DaVinci alongside its Westlake Royal building products.","key_facts":[{"label":"Parent","value":"Westlake"},{"label":"Material","value":"Virgin resins with UV stabilisers"},{"label":"Products","value":"Composite slate and shake tiles, siding"}],"regions":["North America"],"aliases":["DaVinci","DaVinci Slate"],"related":["synthetic-slate","westlake-royal-roofing","ecostar","natural-slate"],"company":{"website":"https://www.davinciroofscapes.com","parent":"Westlake Corporation","known_for":["Composite slate tiles","Composite shake tiles"]},"sources":[{"title":"DaVinci Roofscapes","url":"https://www.davinciroofscapes.com/","publisher":"DaVinci Roofscapes"},{"title":"Westlake significantly expands its presence ... by acquiring Boral's North American building products businesses","url":"https://businesswire.com/news/home/20210620005247/en/Westlake-Significantly-Expands-its-Presence-in-the-Growing-North-American-Home-Construction-Materials-Markets-by-Acquiring-Boral%E2%80%99s-North-American-Building-Products-Businesses","publisher":"Business Wire"}],"country":null},{"slug":"decra-roofing-systems","title":"DECRA Roofing Systems","category":"manufacturers","type":"company","summary":"DECRA is a stone-coated steel roofing brand with roots in New Zealand in 1957, manufactured in the US at Corona, California.","body":"DECRA Roofing Systems is a manufacturer of stone-coated steel roofing, a product that combines a steel sheet with a bonded surface of stone granules so that it resembles tile, shake or shingle. The company dates its products to 1957 and operates in the United States from Corona, California. Since around 2024 its products have been marketed under the name \"DECRA by IKO\".\n\n## Origins\n\nStone-coated steel roofing emerged from post-Second World War repair work on bomb-damaged buildings in Britain, where coatings were applied to metal sheets. The New Zealand entrepreneur Louis J. Fisher combined these coating ideas with pressed metal panels to create an early version of the product. The brand developed in New Zealand and later became part of Fletcher Building, the New Zealand building-materials group.\n\n## North America\n\nDECRA products were first introduced in the US at Honolulu, Hawaii in 1968, and sales grew in California during the 1980s. By 2007 the company had a manufacturing plant of about 9,700 m2 (104,000 sq ft) in Corona, California, with warehouses in Indianapolis and Arlington, Texas. Its current corporate address remains in Corona.\n\n## Product construction\n\nA DECRA panel is formed from steel sheet with an aluminium-zinc metallic coating. Acrylic layers and ceramic-coated stone granules are applied on top. In 2007 the company described its base metal as 26-gauge steel, about 0.45 mm (0.018 in) thick. Panels are pressed into profiles that imitate traditional roofing:\n\n- **Tile** profiles, including a Mediterranean-style Villa Tile.\n- **Shake** profiles imitating split wood.\n- **Shingle** profiles.\n\n## Ownership\n\nDECRA Roofing Systems, Inc. continues to use the DECRA name, and its website and literature use the \"DECRA by IKO\" brand.\n\n## Use\n\nStone-coated steel is used on homes in hurricane-, hail- and wildfire-prone regions and is lighter than the concrete or clay tile it often replaces. The company states that its products are approved for high-velocity hurricane zones in Florida and carry Class 4 impact and Class A fire ratings.","key_facts":[{"label":"Products since","value":"1957"},{"label":"Origin","value":"New Zealand"},{"label":"US base","value":"Corona, California"},{"label":"Product","value":"Stone-coated steel roofing"}],"regions":["North America","Oceania","Global"],"aliases":["DECRA","DECRA by IKO"],"related":["stone-coated-steel","iko","metal-roofing","fletcher-building","ul-2218"],"company":{"founded":"1957","headquarters":"Corona, California, United States","website":"https://www.decra.com","known_for":["Stone-coated steel tile, shake and shingle profiles"]},"sources":[{"title":"DECRA celebrates 50 years of strength","url":"https://www.roofingcontractor.com/articles/85479-decra-celebrates-50-years-of-strength","publisher":"Roofing Contractor"},{"title":"DECRA Roofing Systems","url":"https://www.decra.com/","publisher":"DECRA Roofing Systems"},{"title":"DECRA blog","url":"https://www.decra.com/blog","publisher":"DECRA Roofing Systems"}],"country":null},{"slug":"delabole-slate","title":"Delabole Slate","category":"materials","type":"term","summary":"Roofing slate from the Delabole quarry in north Cornwall, worked continuously since the 15th century and one of England's largest slate quarries.","body":"Delabole slate is natural slate from the quarry at Delabole in north Cornwall, England. The quarry has been worked continuously since the 15th century, and it is described as the oldest working slate quarry in England, and slate was reputedly dug there as early as the reign of King Stephen in the 12th century. It is one of the largest slate quarries in England and is often described as the largest single quarry in Britain.\n\n## History\n\nCornish slate quarrying dates from the late medieval period. In the reign of Elizabeth I, five quarries near Delabole were already supplying slate to Brittany and the Netherlands. In 1841 these workings were combined as the Old Delabole Slate Quarry. The pit was at one time described as the deepest man-made hole in the world, a title since lost to large open-cast mines in America and Australia. A narrow-gauge railway, thought to date from before 1834 and worked by steam and later diesel locomotives, moved slate around the site until after 1987.\n\n## Decline and ownership\n\nAbout 500 people worked at Delabole in 1910. Competition from Welsh slate and later from manufactured tiles cut demand, and by 2007 only five skilled men worked in the pit, with a total workforce of no more than 40. The company was liquidated in 1977 and run under receivership by Rio Tinto Zinc until 1999, when a local management team bought it. In 2005 its majority shareholders bought the whole share capital, returning the quarry to single family ownership for the first time since 1842.\n\n## Use\n\nDelabole slate is the characteristic roofing and cladding stone of much of north Cornwall and is used for repairs to historic Cornish buildings, where matching the local slate is a conservation concern. Many smaller Cornish coastal quarries that once had an export trade are no longer worked because extraction costs are lower at larger British quarries.\n\n## Sources and gaps\n\nCurrent production volumes and technical test data for Delabole slate: published information is limited.","key_facts":[{"label":"Location","value":"Delabole, north Cornwall, England"},{"label":"Worked since","value":"15th century (continuously)"},{"label":"Quarries combined","value":"1841"},{"label":"Workforce","value":"About 500 (1910); no more than 40 (2007)"}],"regions":["Europe"],"aliases":["Cornish slate","Old Delabole Slate Quarry"],"related":["natural-slate","welsh-slate","scottish-slate","roofing-in-the-united-kingdom"],"company":null,"sources":[{"title":"Delabole","url":"https://en.wikipedia.org/wiki/Delabole","publisher":"Wikipedia"},{"title":"Slate industry","url":"https://en.wikipedia.org/wiki/Slate_industry","publisher":"Wikipedia"}],"country":null},{"slug":"designer-shingle","title":"Designer Shingle","type":"term","summary":"A heavy, multi-layer asphalt shingle shaped and coloured to imitate slate, wood shake or other premium roofing.","body":"A designer shingle, also marketed as a luxury or premium shingle, is a heavy laminated asphalt shingle made of three or more layers. Its tabs are cut and coloured to suggest natural slate, hand-split wood shakes or other high-end materials at a lower weight and cost than the real thing.\n\n## Characteristics\n\nDesigner shingles are the heaviest asphalt products on the market. Reference material for roofing contractors lists weights of about 350 to more than 450 lb per square (roughly 17-22 kg/m²), compared with about 190-230 lb for basic three-tab shingles. Many carry the highest available ratings: wind resistance of 130 mph (209 km/h) or more, and UL 2218 Class 4 impact resistance. Manufacturer warranties on these products are often 50 years or described as \"lifetime\", but such warranties are normally prorated and conditional on correct installation.\n\n## Appearance\n\nCommon styles include:\n\n- **Slate-look**: narrow, flat, often staggered tabs in grey, black or mixed colours.\n- **Shake-look**: deep, irregular tabs with strong shadow lines to imitate hand-split cedar.\n- **Scalloped or rounded tabs**: used to suggest historic fish-scale or beaver-tail patterns.\n\n## Considerations\n\nThe weight is still far below natural slate, which commonly weighs 700-900 lb per square (about 34-44 kg/m²), so designer shingles can usually be installed on a conventional framed roof without reinforcement. However, the extra thickness makes them stiffer to handle in cold weather, and dedicated starter, hip and ridge products are normally required to complete the look. As with all asphalt shingles, heat ageing and granule loss, rather than the mat, usually limit service life.\n","key_facts":[{"label":"Layers","value":"Three or more laminated layers"},{"label":"Weight","value":"About 350-450+ lb per square (17-22 kg/m²)"},{"label":"Typical ratings","value":"130+ mph wind; often UL 2218 Class 4"}],"regions":["North America"],"aliases":["luxury shingle","premium shingle","prestige shingle"],"related":["architectural-shingle","asphalt-shingle","synthetic-slate","impact-resistant-shingle","natural-slate"],"sources":[{"title":"Asphalt Shingle Types (3-Tab vs. Laminated Architectural), ASTM Classifications & Thermal Behavior","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-types-astm-thermal","publisher":"Open Exam Prep"},{"title":"Mastering Roof Inspections: Asphalt Composition Shingles, Part 6","url":"https://nachi.org/asphalt-comp-shingles-part6-60.htm","publisher":"InterNACHI"}],"category":"materials","company":null,"country":null},{"slug":"dinorwic-quarry","title":"Dinorwic Quarry","category":"history","type":"place","summary":"A vast former slate quarry above Llanberis, Gwynedd, which employed over 3,000 men in the late 19th century and closed in 1969.","body":"**Dinorwic Quarry** (Welsh spelling Dinorwig) lies on the mountainside between the villages of Llanberis and Dinorwig in Gwynedd, north-west Wales. Together with Penrhyn it was one of the two giants of the Welsh slate industry.\n\n## History\n\nCommercial working began in 1787 under a private partnership. In 1809 the landowner, Thomas Assheton Smith, took direct control. Slate was carried to the coast by tramway from 1824, and from 1848 by the 4 ft (1,219 mm) gauge **Padarn Railway**, which served the quarry until 1961. Output reached about 80,000 tons a year by the late 1860s.\n\n## Scale\n\nThe quarry covers about 283 ha (700 acres), with two main sections each cut into about 20 galleries, or stepped working levels. In the late 19th century it employed more than 3,000 men and produced around 100,000 tonnes of slate a year.\n\n## Closure\n\nThe quarry closed in July 1969, with the loss of about 300 jobs. Its workshops at **Gilfach Ddu** were bought by the county council and now house the **National Slate Museum**, which displays the machinery and the traditional skills of splitting and dressing slate.\n\n## Later use\n\nPart of the quarry was used for the **Dinorwig power station**, a pumped-storage hydroelectric scheme built inside the mountain.\n\n## Heritage\n\nIn its heyday Dinorwic, with Penrhyn, was among the largest producers in a region that supplied about a third of the world's roofing slate. The Dinorwig area forms part of the Slate Landscape of Northwest Wales, inscribed on the UNESCO World Heritage List in 2021, which recognises how this landscape supplied roofing slate to much of the industrial world.","key_facts":[{"label":"Location","value":"Llanberis, Gwynedd, Wales"},{"label":"Commercial working began","value":"1787"},{"label":"Area","value":"About 283 ha (700 acres)"},{"label":"Closed","value":"July 1969"}],"regions":["Europe"],"aliases":["Dinorwig Quarry","Dinorwig slate quarry"],"related":["welsh-slate-industry","penrhyn-quarry","slate-landscape-of-northwest-wales"],"company":null,"sources":[{"title":"Dinorwic Quarry","url":"https://en.wikipedia.org/wiki/Dinorwic_Quarry","publisher":"Wikipedia"},{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"}],"country":null},{"slug":"diola-impluvium-house","title":"Diola Impluvium House","type":"article","summary":"Round earth house of the Diola (Jola) of Casamance, Senegal, whose thatched roof slopes inward to collect rain in a central basin.","body":"The impluvium house (French *case à impluvium*) is a traditional dwelling of the Diola, or Jola, people of the Casamance region of southern Senegal, a humid coastal zone of forests, rice fields and mangroves. Its defining feature is a thatched roof that drains not only outward but also inward, into an open central court where rainwater collects.\n\n## Form\n\nThe house is built around a central open court. Thick walls of sun-dried mud brick with an earth plaster enclose the rooms, and a timber structure carries a thatched roof. The roof rises to a ridge and then slopes both outward, over the external walls, and inward, toward an opening over the court. In architectural terms the opening is the *compluvium* and the basin below is the *impluvium*, the same words used for the Roman atrium house.\n\n## Water collection\n\nDuring the rainy season, water running down the inner slope falls into the low-walled central basin. The architect Dennis Holloway, who has studied the form, notes that the collected water served as a drinking supply. In some surviving houses the court also works as a garden or animal pen and fills completely with water at the height of the rains.\n\n## Climate performance\n\nThe thatch shades the thick earth walls from the sun and limits heat gain, while the open centre allows air movement and evaporative cooling. The combination suits a hot, wet climate close to sea level.\n\n## Where they survive\n\nExamples are found in or near villages including Enampore, Séléki, Affiniam, Oussouye and Mlomp. A visitor survey published in 2012 found that surviving impluvium houses could be counted on the fingers of two hands, most dating from the second half of the 20th century. Several now function as village guesthouses (*campements villageois*), and the impluvium at Enampore was rebuilt around 2011. Newer buildings, such as a house at Oussouye completed in 2004, have reinterpreted the type with clay walls on concrete slabs.\n\nThe impluvium houses of the Bandial kingdom are on Senegal's tentative list for World Heritage nomination.\n\n## Related types\n\nCasamance also has multi-storey earth houses (*cases à étages*), notably at Mlomp, built of clay walls with palm-wood floors and straw roofs. Compluvium courtyard houses also occur among the Igbo, Yoruba and Edo of southern Nigeria.","key_facts":[{"label":"Region","value":"Casamance, southern Senegal"},{"label":"People","value":"Diola (Jola)"},{"label":"Roof","value":"Thatch sloping outward and inward to a central opening"},{"label":"Walls","value":"Sun-dried mud brick, earth plaster"},{"label":"Function of basin","value":"Rainwater collection"}],"regions":["Africa"],"aliases":["case à impluvium","Jola impluvium house","Casamance impluvium house"],"related":["roofing-in-senegal","roofing-in-the-gambia","roofing-in-guinea-bissau","thatch","rainwater-harvesting-roofs","palm-thatch"],"sources":[{"title":"Jola Impluvium House","url":"https://dennisrhollowayarchitect.com/JolaImpluvium.html","publisher":"Dennis R. Holloway, Architect"},{"title":"House of the impluvium, multi-storey house and architectural forms in Casamance","url":"https://www.archiweb.cz/en/n/domaci/dum-impluvium-poschodovy-dum-a-architektonicke-formy-v-nbspcasamance","publisher":"Archiweb"},{"title":"Les cases à impluvium du royaume Bandial","url":"https://www.worldheritagesite.org/tentative/id/2076","publisher":"World Heritage Site"}],"company":null,"category":"world-roofing","country":null},{"slug":"djenne-earthen-architecture","title":"Djenné Earthen Architecture","type":"place","summary":"Mud-brick houses and the Great Mosque of Djenné, Mali, with earth-covered palm-timber roofs maintained by an annual community replastering.","body":"Djenné, in central Mali, is one of the best-known centres of Sudano-Sahelian earthen architecture. Its old town, inscribed by UNESCO in 1988 together with nearby archaeological sites as the Old Towns of Djenné, retains nearly 2,000 traditional earth houses, and its Great Mosque is the largest mud-brick building in the world.\n\n## Materials\n\nWalls are built of sun-dried earth bricks (*ferey*) set in a mortar of sand and earth and coated with an earth plaster. The traditional wet-earth technique of the region is called *banco*. Roofs are made of timber, typically bundled palm sticks or beams, covered with layers of earth, producing a flat or very shallow roof.\n\n## The Great Mosque roof\n\nThe current mosque was rebuilt in 1906-1907 under the direction of Ismaila Traoré, head of the masons' guild. Its prayer hall has a mud-covered roof of *rodier* palm timber supported by nine interior walls with pointed arches. Small roof vents are capped with removable, inverted fired-clay bowls; when the caps are lifted, hot air escapes and the interior is ventilated. Ceramic half-pipes project from the roofline to throw rainwater clear of the walls.\n\nBundles of palm sticks called *toron* project about 60 cm (2 ft) from the walls. They are decorative but also act as permanent scaffolding.\n\n## Annual maintenance\n\nEarth roofs and walls erode in the rainy season. Each year the community replasters the mosque: plaster is mixed in pits over several days and applied by men working from the toron and palm-wood ladders, directed by members of the masons' guild. The event has become a well-known festival. Houses are maintained the same way on a smaller scale.\n\n## Threats\n\nUNESCO lists erosion and gullying from storms, uncontrolled urban growth and the introduction of cement, fired brick and metal doors and windows among the pressures on the town. Some decorative facade elements have disappeared as a result.\n\n## Wider significance\n\nThe Djenné roof shows the core logic of Sahelian earth building: thick earth for heat control, timber only where it is essential, waterspouts to protect walls, and a maintenance cycle carried out collectively.","key_facts":[{"label":"Location","value":"Djenné, Mali"},{"label":"Roof","value":"Earth over palm timber, flat or shallow"},{"label":"Great Mosque rebuilt","value":"1906-1907"},{"label":"Surviving houses","value":"Nearly 2,000"},{"label":"UNESCO inscription","value":"1988"}],"regions":["Africa"],"aliases":["Great Mosque of Djenné","Banco architecture","Malian adobe"],"related":["sahelian-earthen-roofs","nubian-vault","roofing-in-west-africa","flat-roof","mud-roof"],"sources":[{"title":"Great Mosque of Djenné","url":"https://en.wikipedia.org/wiki/Great_Mosque_of_Djenn%C3%A9","publisher":"Wikipedia"},{"title":"Old Towns of Djenné","url":"https://whc.unesco.org/en/list/116","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing","country":null},{"slug":"dogon-architecture","title":"Dogon Architecture","type":"article","summary":"Earthen houses, thatched granaries and low toguna shelters of the Dogon on the Bandiagara cliffs of Mali.","body":"Dogon architecture is the building tradition of the Dogon people of the Bandiagara region of central Mali, where villages cling to a sandstone escarpment and spread across the plateau above and the plains below. The Cliff of Bandiagara (Land of the Dogons) is a UNESCO World Heritage site covering about 400,000 ha (roughly 990,000 acres) and 289 villages.\n\n## Houses\n\nThe large family house, the *gin'na*, is usually two storeys high. Its earth (*banco*) facade has no windows, only niches and doors, often carved with figures representing successive generations. The earthen walls are made with the same *banco* technique used across the Sudano-Sahelian belt (see Sahelian earthen roofs).\n\n## Granaries\n\nThe most recognisable Dogon roofs are on granaries. UNESCO describes them as mostly square in plan, with a thatched roof that tapers upward to a point. The thatch caps protect the stored grain from rain and sun while the earth walls below keep out animals and pests. Rows of these pointed roofs give escarpment villages their distinctive skyline.\n\n## The toguna\n\nThe *toguna* (also written *togu-na*) is a communal shelter for the men of the village. UNESCO describes it as a long structure with a roof of branches carried on roughly shaped wooden posts, shading a raised bench platform. The roof is deliberately very low, so people must sit rather than stand. A common explanation is that this keeps heated discussions calm, since no one can rise up in anger. The toguna is where elders meet to settle community matters and where people gather in the shade during the hottest hours of the day.\n\n## Sanctuaries\n\nTotemic sanctuaries (*binu*) vary widely, from caves in the cliff to earth buildings that resemble houses.\n\n## Pressures\n\nUNESCO describes Bandiagara as \"a living site, but fragile\". Threats include:\n\n- People leaving the steep escarpment villages for the plains, driven by rural exodus, schooling and new infrastructure.\n- Drought, desertification and torrential rains linked to climate change.\n- Population pressure.\n- Logging, which reduces available plant materials.\n\nFor roofs, the effect is a slow loss of the maintenance cycle on which thatched granaries and earth roofs depend, and a gradual shift to imported materials in new building.","key_facts":[{"label":"Location","value":"Bandiagara, central Mali"},{"label":"Granary roof","value":"Thatch tapering to a point"},{"label":"Toguna roof","value":"Low roof of branches on wooden posts"},{"label":"UNESCO site extent","value":"About 400,000 ha; 289 villages"}],"regions":["Africa"],"aliases":["Bandiagara architecture","Dogon granary","toguna","togu-na","gin'na"],"related":["roofing-in-mali","sahelian-earthen-roofs","djenne-earthen-architecture","thatch","flat-roof"],"sources":[{"title":"Cliff of Bandiagara (Land of the Dogons)","url":"https://whc.unesco.org/en/list/516/","publisher":"UNESCO World Heritage Centre"},{"title":"Toguna","url":"https://en.wikipedia.org/wiki/Toguna","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"dome","title":"Dome","category":"roof-forms","type":"article","summary":"A dome is a curved roof shaped like the hollow upper part of a sphere or similar surface, spanning a circular, polygonal or square space.","body":"A dome is a roof or vault in the form of the hollow upper half of a sphere, or a related curved shape, rising from a circular, polygonal or square base. Because its curvature runs in every direction, a dome carries loads by compression along its surface and can span large spaces without internal supports. The word cupola is sometimes used as a synonym, and also for a small dome on a roof or turret.\n\n## Parts of a dome\n\n- **Drum:** a cylindrical or polygonal wall that raises the dome and often contains windows; drums are frequently much thicker than the dome itself.\n- **Pendentives and squinches:** triangular or arched transitions that allow a round dome to sit over a square space.\n- **Oculus:** an opening at the apex.\n- **Lantern:** a small structure over the oculus admitting light and often topped by a cupola.\n\n## Landmark examples\n\n- **Pantheon, Rome:** described as the most famous, best preserved and largest Roman dome, with an open oculus.\n- **Hagia Sophia, Istanbul:** Justinian's 6th-century church combined a central dome with semi-domes over a basilica plan; earthquakes caused partial collapses requiring repairs.\n- **Florence Cathedral:** Filippo Brunelleschi's octagonal Renaissance dome.\n- **Geodesic domes:** lattice shells of triangles associated with Buckminster Fuller, who patented them in the United States although he did not invent the form.\n\n## Coverings\n\nMasonry and concrete domes may be left exposed or covered. Timber and lightweight domes have traditionally been clad in sheet lead or copper, and Byzantine domes used everything from ceramic tiles to lead sheeting. Modern domes use standing-seam or flat-lock metal, membranes, or specialised shingles. The doubly curved surface means sheets must be tapered or shaped to fit, and drainage at the base must handle water running off in all directions.\n\n## Structural behaviour\n\nDomes push outward at their base, so traditional masonry domes rely on thick drums, buttresses or tension rings. Onion domes and other decorative domes are often light timber or metal frames on top of a structural vault rather than true structural domes.","key_facts":[{"label":"Shape","value":"Hollow upper part of a sphere or similar"},{"label":"Key parts","value":"Drum, oculus, lantern"},{"label":"Traditional claddings","value":"Lead, copper, tile"}],"regions":["Global"],"aliases":["cupola","domed roof","geodesic dome"],"related":["onion-dome","barrel-vault-roof","conical-roof","pagoda-roof"],"company":null,"sources":[{"title":"Dome","url":"https://en.wikipedia.org/wiki/Dome","publisher":"Wikipedia"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"}],"country":null},{"regions":["Europe"],"company":null,"slug":"st-peters-basilica-dome","title":"Dome of St Peter's Basilica","category":"history","type":"place","summary":"The double-shelled brick dome of St Peter's Basilica in Vatican City, designed by Michelangelo and completed in 1590 by della Porta and Fontana.","aliases":["St Peter's dome","Michelangelo's dome","Cupola di San Pietro"],"body":"The dome of **St Peter's Basilica** in Vatican City is one of the largest masonry domes ever built and the dominant feature of the Rome skyline. It was designed principally by Michelangelo and completed in 1590.\n\n## Design history\n\nThe new basilica, replacing a 4th-century church founded by Constantine, was begun on 18 April 1506. Donato Bramante drew the first design for the dome that year. After several changes of architect, Michelangelo took over in 1547 and redesigned the dome. He did not live to see it built: Giacomo della Porta and Domenico Fontana completed it in 1590, in the last year of the reign of Pope Sixtus V. Fontana finished the lantern under Pope Gregory XIV, with inscriptions honouring Sixtus V around its opening. The basilica was consecrated by Pope Urban VIII on 18 November 1626.\n\n## Structure\n\n- **Two shells:** like Brunelleschi's dome in Florence, St Peter's dome has an inner and an outer shell, both of brick.\n- **Ribs:** the outer shell carries 16 stone ribs.\n- **Height:** about 136.57 m (448.1 ft) from the basilica floor to the top of the external cross.\n- **Span:** an internal diameter of about 41.47 m (136.1 ft), slightly less than the Pantheon's roughly 43.3 m (142 ft).\n\n## Cracking and iron chains\n\nMasonry domes push outward at their base. Cracks appeared in St Peter's dome, and in the mid-18th century four iron chains were installed between the two shells to hold it together. As many as ten chains have been installed at various times.\n\n## Care\n\nThe *Fabbrica di San Pietro*, founded in 1506, is still responsible for maintaining the basilica. The whole of Vatican City, about 44 ha (109 acres), is a UNESCO World Heritage site, with Michelangelo's cupola named among its key works.\n\n## Significance\n\nWith the Pantheon and the dome of Florence Cathedral, St Peter's is one of the three great domes of Rome and Italy, all of similar span.","key_facts":[{"label":"Completed","value":"1590"},{"label":"Designers","value":"Bramante (1506), Michelangelo (from 1547), della Porta and Fontana"},{"label":"Height to cross","value":"136.57 m (448.1 ft)"},{"label":"Internal diameter","value":"41.47 m (136.1 ft)"},{"label":"Reinforcement","value":"Iron chains from the mid-18th century"}],"related":["roofing-in-vatican-city","pantheon-dome","florence-cathedral-dome","st-pauls-cathedral-dome","dome","roofing-in-italy"],"sources":[{"title":"St. Peter's Basilica","url":"https://en.wikipedia.org/wiki/St._Peter%27s_Basilica","publisher":"Wikipedia"},{"title":"Vatican City","url":"https://whc.unesco.org/en/list/286","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"dormer","title":"Dormer","category":"components","type":"article","summary":"A dormer is a roofed structure, usually holding a window, that projects vertically from a pitched roof to add headroom and light to the space below.","body":"A dormer is a structure that projects up and out from the plane of a sloping roof, with its own small roof and, usually, a vertical window in its face. Dormers turn awkward attic space into usable rooms by adding headroom and admit daylight and ventilation. The word derives from the Middle French dormeor, a sleeping room, because dormers often lit attic bedrooms.\n\n## Common types\n\n- **Gable (gable-fronted) dormer:** a small gable with two sloping planes; the most common type, sometimes called a doghouse dormer.\n- **Hipped dormer:** three sloping planes meeting at a short ridge.\n- **Shed dormer:** a single roof plane sloping in the same direction as the main roof but at a shallower pitch, giving maximum floor area.\n- **Flat-roof dormer:** a nearly level roof with slight fall; widely used in UK loft conversions, where large box dormers are common.\n- **Eyebrow dormer:** a low, wide dormer with a gently curved roof that flows into the main roof without vertical sides.\n- **Wall dormer:** the face of the dormer is flush with the wall below, breaking the eave line.\n- **Bonneted, Nantucket, link and blind dormers** are less common variants; a lucarne is a slender dormer on a Gothic spire.\n\n## Construction and weatherproofing\n\nDormers interrupt the roof and create several vulnerable junctions: step flashing or soakers along the dormer cheeks (sides), an apron flashing below the window, and valleys where the dormer roof meets the main roof. The roof framing around a dormer opening needs trimmers to carry loads from the cut rafters.\n\n## History\n\nEarly dormers included lucarnes ventilating English Gothic spires. Dormer windows have been used in British houses since the 16th century, and François Mansart's 17th-century mansard roofs in Paris helped popularise them. In many countries, adding a dormer can require planning permission or must follow permitted development rules.","key_facts":[{"label":"Etymology","value":"Middle French dormeor (sleeping room)"},{"label":"Common types","value":"Gable, hipped, shed, flat, eyebrow, wall"},{"label":"In British houses since","value":"16th century"}],"regions":["Global"],"aliases":["dormer window","box dormer","shed dormer","gable dormer"],"related":["mansard-roof","step-flashing","apron-flashing","roof-valley","skylight"],"company":null,"sources":[{"title":"Dormer","url":"https://en.wikipedia.org/wiki/Dormer","publisher":"Wikipedia"},{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"}],"country":null},{"slug":"dougong","title":"Dougong","category":"history","type":"term","summary":"Dougong are interlocking timber bracket sets of blocks and arms that carry the roof and deep eaves of traditional Chinese and East Asian halls.","body":"*Dougong* (斗拱, roughly \"cap and arm\") is the bracket system of traditional Chinese timber architecture. A large block (*dou*) sits on top of a column and supports bow-shaped arms (*gong*), which in turn carry further blocks, arms, beams or purlins. Built up in tiers, the sets spread the load of a heavy tiled roof onto the columns and let the eaves project far beyond the walls. The same principle spread to Korea and Japan, where bracket sets support the roofs of temples and palaces.\n\n## How it works\n\nDougong pieces are fitted by joinery alone, without glue or metal fasteners, and are held together by friction and by the downward weight of the roof. Several interlocking layers spread the load and reduce strain on the beams. Because the joints can slip, rotate and compress slightly, they also absorb energy, and this flexibility is widely credited with helping old halls survive earthquakes.\n\n## History\n\n- **Origins.** Early forms appeared under the Western Zhou dynasty, without fixed rules or ornament. Bracketing was widely used by the Spring and Autumn period (770-476 BCE).\n- **Tang and Song.** Dougong reached its greatest structural importance. Walls were often non-load-bearing, so the outer bracket sets were essential to carrying the roof. Surviving Tang halls include the Great Buddha Hall of Nanchan Temple (782), whose hip-and-gable roof rests on five-tier (*puzuo*) brackets, and the East Hall of Foguang Temple (857), where each column carries a bracket set built from seven types of bracket.\n- **Standardisation.** The Song manual *Yingzao Fashi* (1103) set out an eight-rank grading system of timber sizes, known as the *cai-fen* system, and gave specifications and drawings for bracket sets.\n- **Ming and Qing.** Brackets became smaller, more numerous and more decorative. The Bao'en Temple in Sichuan, built 1440-1446, has 48 types and some 2,200 sets.\n\n## Rank and meaning\n\nFor long periods the use of bracket sets was restricted, so they came to signal the upper and ruling classes and official or religious buildings. Ordinary houses were built without them.\n\n## Regional names\n\nIn Japan the equivalent bracket system is called *tokyō*; in Korea bracket sets are a defining feature of palace and temple halls, developing from simple Goguryeo brackets to multi-bracket systems from mid-Goryeo onward.","key_facts":[{"label":"Meaning","value":"Cap (dou) and arm (gong)"},{"label":"Earliest forms","value":"Western Zhou dynasty"},{"label":"Peak structural use","value":"Tang and Song dynasties"},{"label":"Fixing","value":"Joinery only, no glue or nails"},{"label":"Codified in","value":"Yingzao Fashi (1103)"}],"regions":["East Asia"],"aliases":["tou-kung","Chinese bracket set","bracket cluster","tokyo"],"related":["yingzao-fashi","roofing-in-china","roofing-in-japan","roofing-in-south-korea","forbidden-city-roofs","pagoda-roof","irimoya","history-of-timber-roof-framing","earthquake-roofing"],"company":null,"sources":[{"title":"Dougong","url":"https://en.wikipedia.org/wiki/Dougong","publisher":"Wikipedia"},{"title":"Nanchan Temple","url":"https://en.wikipedia.org/wiki/Nanchan_Temple","publisher":"Wikipedia"},{"title":"Foguang Temple","url":"https://en.wikipedia.org/wiki/Foguang_Temple","publisher":"Wikipedia"},{"title":"Yingzao Fashi","url":"https://en.wikipedia.org/wiki/Yingzao_Fashi","publisher":"Wikipedia"},{"title":"Korean architecture","url":"https://en.wikipedia.org/wiki/Korean_architecture","publisher":"Wikipedia"},{"title":"Japanese architecture","url":"https://en.wikipedia.org/wiki/Japanese_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"downspout","title":"Downspout (Downpipe)","category":"components","type":"term","summary":"A downspout, or downpipe, is a vertical pipe that carries rainwater from a roof gutter down to the ground, a drain or a storage tank.","body":"A downspout is the vertical pipe that drains a gutter. Water collected along the eaves enters the downspout through an outlet in the gutter bottom and travels to ground level, where it is discharged onto a splash block, into an extension that carries it away from the foundation, into an underground drain, or into a rain barrel or tank. The same component is called a downpipe in Britain, Australia and New Zealand, and a leader or conductor in parts of the United States.\n\n## Components\n\n- **Outlet (drop):** the fitting connecting gutter to pipe.\n- **Elbows and offsets (swan necks in the UK):** bends that bring the pipe from the gutter, which is set out from the wall, back to the wall face.\n- **Straps or clips:** fix the pipe to the wall.\n- **Shoe:** the angled fitting at the bottom that directs water outward.\n- **Rainwater head (hopper head):** an open box at the top of the pipe collecting from one or more gutters or roof outlets, often decorative on historic buildings.\n\n## Profiles and materials\n\nRectangular (corrugated or plain) and round pipes are both common. Materials generally match the gutter: aluminium, galvanised or coated steel, copper, zinc, cast iron, uPVC. Heritage buildings in Britain often have cast-iron downpipes and decorative hoppers.\n\n## Sizing and placement\n\nThe number and size of downspouts depends on roof area, gutter capacity and design rainfall intensity. As a residential rule of thumb, a 100 mm (4 in) gutter with one 68 mm downpipe has been suggested for about 56 m² (600 sq ft) of roof. Placing outlets near the ends of long runs and at corners reduces overflow. Discharge should be directed well away from foundations, and local regulations may control connection to storm sewers.\n\n## Alternatives\n\nRain chains are a decorative alternative to downspouts, guiding water down a chain or series of cups.","key_facts":[{"label":"UK/AU term","value":"Downpipe"},{"label":"Other US terms","value":"Leader, conductor"},{"label":"Key fittings","value":"Outlet, elbows, shoe, hopper head"}],"regions":["Global"],"aliases":["downpipe","leader","conductor pipe","rainwater pipe"],"related":["rain-gutter","rain-chain","eaves"],"company":null,"sources":[{"title":"Rain gutter","url":"https://en.wikipedia.org/wiki/Rain_gutter","publisher":"Wikipedia"},{"title":"Rain chain","url":"https://en.wikipedia.org/wiki/Rain_chain","publisher":"Wikipedia"}],"country":null},{"slug":"drip-edge","title":"Drip Edge","category":"components","type":"term","summary":"A drip edge is a formed metal flashing fixed along the eaves and rakes that carries water clear of the fascia and protects the edge of the roof deck.","body":"A drip edge is a length of bent sheet metal, usually aluminium, galvanised or coated steel, or copper, installed along the roof edges. One flange lies on the roof deck; the other turns down over the edge, often with a small outward kick, so water dripping off the roof falls clear of the fascia and into the gutter rather than wicking back onto the deck edge and fascia board. It also stiffens and protects the edges of shingles and closes the gap between deck and fascia against wind-driven rain and pests.\n\n## US code requirements\n\nThe International Residential Code (section R905.2.8.5 in recent editions) requires drip edge at eaves and rake edges of asphalt shingle roofs; trade press dates the requirement to the 2012 edition. As adopted in Connecticut's 2022 code, for example, requirements include:\n\n- adjacent pieces overlapped at least 2 in (51 mm);\n- the metal extending at least 1/4 in (6 mm) below the roof sheathing;\n- extending back onto the roof deck at least 2 in (51 mm);\n- mechanically fastened to the deck at no more than 12 in (305 mm) on centre.\n\nSome shingle manufacturers recommend closer fastening. States and cities can amend the model code: Virginia's building code, for instance, does not prescriptively require drip edge, but it must be installed where the shingle manufacturer calls for it.\n\n## Eaves versus rakes\n\nThe lapping order differs between edges:\n\n- **At the eaves,** the underlayment goes over the drip edge so that water on the underlayment drains onto the metal.\n- **At the rakes,** the drip edge goes over the underlayment.\n\nWhere an ice barrier is used at the eaves, manufacturer instructions specify whether the membrane goes under or over the drip edge.\n\n## Profiles and regional terms\n\nCommon profiles include the L-shaped, the T-shaped \"D-style\", and the gutter apron, which extends down into the gutter. In the UK, eaves trays, eaves carrier strips and verge trims perform related functions, and on tiled roofs the underlay is often carried into the gutter over a fascia board or eaves support tray.","key_facts":[{"label":"IRC section","value":"R905.2.8.5"},{"label":"Minimum lap","value":"2 in (51 mm)"},{"label":"Below sheathing","value":"At least 1/4 in (6 mm)"},{"label":"Fastener spacing","value":"Max 12 in (305 mm) o.c."}],"regions":["North America","Global"],"aliases":["drip edge flashing","eaves flashing","gutter apron","edge metal"],"related":["eaves","roof-rake","fascia","rain-gutter","roofing-underlayment","roof-flashing"],"company":null,"sources":[{"title":"Roof drip edge code (IRC 2021 R905.2.8.5)","url":"https://www.jaspector.com/codes/irc-2021/ch09-roof-assemblies/roof-drip-edge-code/","publisher":"Jaspector"},{"title":"Drip Edge and the IRC","url":"https://www.jlconline.com/how-to/framing/drip-edge-and-the-irc_o/","publisher":"JLC"},{"title":"2012 IRC drip edge requirement","url":"https://ncw.homeinspectorsites.com/blog/2012-irc-drip-edge-requirement","publisher":"Home Inspector Sites"},{"title":"Asphalt Shingle Installation (2022 Connecticut State Building Code)","url":"https://www.meridenct.gov/Customer-Content/www/CMS/files/Building/Asphalt_Shingle_Installation.pdf","publisher":"City of Meriden, Connecticut, Building Division"},{"title":"Roof Replacements","url":"https://pwcaws.pwcva.gov/assets/2021-04/roofreplacements.pdf","publisher":"Prince William County, Virginia"}],"country":null},{"slug":"drone-roof-inspection","title":"Drone Roof Inspection","category":"tools-equipment","type":"article","summary":"Use of small unmanned aircraft with cameras to photograph, measure and map roofs without climbing onto them.","body":"Drone roof inspection uses small unmanned aircraft systems (UAS) fitted with cameras to capture images and video of a roof. Roofers, inspectors, insurers and building owners use drones to assess condition, document storm damage, measure roofs for estimates and monitor large commercial roofs, often without anyone climbing onto the roof.\n\n## What drones can capture\n\n- **High-resolution photographs and video** of slopes, ridges, chimneys, valleys and flashings.\n- **Orthomosaic maps and 3D models**, produced by flying automated grid patterns and stitching the images with photogrammetry software. These support measurements of area, pitch and edge lengths.\n- **Thermal images**, with radiometric infrared cameras, to support moisture surveys on low-slope roofs under suitable conditions.\n- **Close-up inspection** of areas that are unsafe or impractical to reach, such as steep or fragile roofs.\n\n## Benefits\n\n- **Safety**: reduces the need to walk on roofs, especially damaged, steep, wet or fragile ones.\n- **Speed**: large or multiple roofs can be documented quickly.\n- **Records**: dated, geolocated images give a baseline for later comparison and for insurance or warranty records.\n\n## Limitations\n\n- Drones cannot feel bruised shingles, test for soft decking, lift laps or probe seams. Hail and wind assessments often still need hands-on checks.\n- Image quality depends on light, weather, wind and the pilot's skill.\n- Thermal imaging needs specific environmental conditions and trained interpretation, and anomalies must be verified by cores or other methods.\n- Battery life limits flight time.\n\n## Regulation\n\nDrone flights are regulated by national aviation authorities. In the United States, commercial operators fly under the FAA's Part 107 rules, which require a Remote Pilot Certificate, aircraft registration, and operation no higher than 400 ft (about 122 m) above ground level, with the aircraft in visual line of sight. An exception allows flight within a 400 ft radius of a structure up to 400 ft above the structure's highest point, which is relevant to inspections of tall buildings. Canada, the United Kingdom, the European Union, Australia and other jurisdictions have their own licensing, registration and airspace rules. Privacy and neighbour concerns, flights over people and controlled airspace near airports are common restrictions.","key_facts":[{"label":"Outputs","value":"Photos, video, orthomosaics, 3D models, thermal images"},{"label":"Main benefit","value":"Inspection without climbing on the roof"},{"label":"US commercial rules","value":"FAA Part 107"}],"regions":["Global"],"aliases":["UAV roof inspection","drone roofing survey","aerial roof inspection"],"related":["storm-damage-inspection","infrared-roof-thermography","roof-moisture-survey","roof-maintenance-checklist","pitch-gauge"],"company":null,"sources":[{"title":"How to Perform a Drone Roof Inspection","url":"https://enterprise-insights.dji.com/blog/drone-roof-inspections","publisher":"DJI Enterprise"},{"title":"Roofing drones: transforming roof inspections, FAA rules, and ROI","url":"https://jobnimbus.com/blog/roofing-drones","publisher":"JobNimbus"},{"title":"Legal aspects of drone use in roofing","url":"https://www.rooferscoffeeshop.com/legal-aspects-of-drone-use-in-roofing","publisher":"RoofersCoffeeShop"},{"title":"14 CFR § 107.51 - Operating limitations for small unmanned aircraft","url":"https://www.law.cornell.edu/cfr/text/14/107.51","publisher":"Legal Information Institute, Cornell Law School"},{"title":"Certified Remote Pilots including Commercial Operators","url":"https://www.faa.gov/uas/commercial_operators","publisher":"Federal Aviation Administration"}],"country":null},{"slug":"dry-fix-ridge-system","title":"Dry-Fix Ridge System","category":"installation","type":"term","summary":"A dry-fix system secures ridge, hip or verge tiles with mechanical fixings, seals and ventilated rolls instead of mortar.","body":"A **dry-fix system** is a set of components that mechanically secures ridge, hip or verge tiles without wet mortar. Typical kits include a ridge batten bracket, a flexible ventilated roll or seal that bridges the gap between the tiles and the ridge, clips or screws to hold each ridge tile, and end caps. Dry verges replace mortar at gable edges with clip-together plastic or metal units fixed to the batten ends.\n\n## Why dry-fix is used\n\nMortar bedding is traditional on tiled roofs in many countries, but mortar cracks and erodes over time, and loose ridge tiles are a frequent storm-damage repair. In the UK, BS 5534 no longer allows mortar to be relied on as the only fixing, and ridge and hip tiles must be mechanically fixed regardless of whether mortar is used. Dry-fix systems meet this requirement without mortar and usually also provide ridge ventilation.\n\n## Standard\n\n**BS 8612:2018** sets requirements for dry-fixed ridge, hip and verge systems for slating and tiling, including fixing and ventilation performance. It was introduced after some verge products were found to give too little mechanical restraint.\n\n## Installation outline\n\n1. Fix ridge batten brackets to the rafters or trusses and fit the ridge batten at the correct height.\n2. Cut the top course of tiles so they meet the ridge line and fix them mechanically.\n3. Lay the ridge roll along the batten, dressing its adhesive edges onto the tiles on both sides.\n4. Fix each ridge tile to the batten with the screw or clip supplied, joining tiles with the system's union pieces.\n5. Fit end caps at gables and junction pieces where hips meet the ridge.\n\n## Mortar alternatives\n\nMortar is still allowed alongside mechanical fixings in the UK and remains common practice in many other regions. Heritage roofs may keep mortar bedding for appearance, with concealed mechanical fixings added to meet current standards.","key_facts":[{"label":"UK product standard","value":"BS 8612:2018"},{"label":"Typical parts","value":"Ridge batten brackets, ventilated roll, clips, end caps"},{"label":"Advantage","value":"Mechanical fixing plus ventilation without mortar"}],"regions":["Europe","Global"],"aliases":["dry ridge","dry verge","mortarless ridge"],"related":["ridge-cap-installation","bs-5534-fixing-specification","clay-and-concrete-tile-installation","ridge-vent"],"company":null,"sources":[{"title":"What are the fixing requirements of BS 5534?","url":"https://www.marley.co.uk/blog/what-are-the-fixing-requirements-of-bs-5534","publisher":"Marley"},{"title":"What is BS 5534?","url":"https://www.marley.co.uk/Blog/What-is-BS-5534","publisher":"Marley"}],"country":null},{"slug":"dtu-40-series","title":"DTU 40 Series (France)","summary":"The French NF DTU 40 series are the technical rules for pitched roof coverings in France, covering slate, clay and concrete tiles, metal sheet and roof drainage.","body":"In France, the **DTU** (*documents techniques unifiés*, unified technical documents) are the reference rules of the art for building work. They are drawn up under the Commission Générale de Normalisation du Bâtiment/DTU, with the Centre Scientifique et Technique du Bâtiment (CSTB) providing its secretariat. Since 1990 they have been progressively brought into the official French standards system, and most are now published as French standards with the prefix **NF DTU**.\n\nThe **DTU 40 series** covers pitched roof coverings (*couvertures*).\n\n## Parts of a DTU\n\nA DTU normally consists of:\n\n- a **CCT** (*cahier des clauses techniques*) – technical clauses for choosing and installing materials\n- a **CCS** (*cahier des clauses spéciales*) – special clauses that define the limits of each trade's work and its obligations to other trades\n- sometimes **calculation rules**\n\nThese documents apply contractually: they bind the parties when a contract refers to them, which most building contracts in France do. Insurers and courts also refer to them when judging whether work follows accepted practice.\n\n## Documents in the 40 series\n\nExamples include:\n\n- **DTU 40.11** – natural slate roofing\n- **DTU 40.13** – fibre-cement slate roofing\n- **DTU 40.21** – clay tiles with locking or sliding relief profiles\n- **DTU 40.23** – flat clay tiles\n- **DTU 40.24** – concrete tiles\n- **DTU 40.35** – ribbed sheets made from coated steel\n- **DTU 40.36** – aluminium sheets, pre-painted or not\n- **DTU 40.41** – zinc sheet and long-strip roofing\n- **DTU 40.44** – stainless steel sheet and long-strip roofing\n- **DTU 40.5** – rainwater drainage works\n\nOther numbers in the series cover further tile types and roof coverings.\n\n## How they are used\n\nDTUs set minimum pitches according to climatic zone, site exposure and rafter length, along with laps, fixing methods, underlay, ventilation and flashing details. As a result, the same tile can require different minimum pitches in different parts of France.\n\nProducts and methods outside the DTUs are usually covered by a CSTB *Avis Technique* or *Document Technique d'Application*, which serve as evaluated alternatives.\n\n## Access\n\nDTUs are sold rather than distributed free, which has been criticized as a barrier for individuals and small firms. In 2017 France's Conseil d'État held that NF standards cannot be made mandatory by regulation if they cannot be consulted free of charge.","key_facts":[{"label":"Country","value":"France"},{"label":"Secretariat","value":"CSTB"},{"label":"Format","value":"NF DTU (French standards)"},{"label":"Components","value":"CCT, CCS, calculation rules"},{"label":"Examples","value":"40.11 slate, 40.21 clay tiles, 40.35 steel, 40.41 zinc"}],"regions":["Europe"],"aliases":["NF DTU 40","DTU 40.11","DTU 40.21","DTU 40.41","documents techniques unifiés"],"related":["en-12326","en-1304","en-988","zvdh-fachregeln","bs-5534"],"sources":[{"title":"Document technique unifié","url":"https://fr.wikipedia.org/wiki/Document_technique_unifi%C3%A9","publisher":"Wikipédia"},{"title":"Couverture (construction)","url":"https://fr.wikipedia.org/wiki/Couverture_(construction)","publisher":"Wikipédia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"duro-last","title":"Duro-Last","category":"manufacturers","type":"company","summary":"Duro-Last is a Saginaw, Michigan maker of custom-prefabricated PVC single-ply roofing, founded in 1978 and part of Amrize since 2025.","body":"Duro-Last is a US manufacturer of single-ply roofing systems, best known for PVC membranes that are custom-fabricated in the factory into large deck sheets sized to a specific roof. It is headquartered in Saginaw, Michigan. Holcim's building envelope business acquired Duro-Last in 2023, and since Holcim's North American spin-off in June 2025 it has been a brand within the Building Envelope division of Amrize.\n\n## History\n\nThe company's founder, John R. Burt, started the business at the age of 58. Its predecessor, Tri-City Vinyl, was incorporated in 1977 to make swimming-pool liners. The Duro-Last roofing system was developed and first installed in 1978, and Duro-Last itself was incorporated in 1981. It bought its first Saginaw facility in 1982 and added a second there in 1984.\n\nFurther plants followed in Jackson, Mississippi (1994, about 7,400 m2 / 80,000 sq ft); Sigourney, Iowa and Grants Pass, Oregon (1996); Carrollton, Texas (2013); and Ludlow, Massachusetts (2017). A Largo, Florida site opened in 2023 as its seventh manufacturing facility and a Kernersville, North Carolina plant of about 9,700 m2 (104,000 sq ft) in 2025 as its eighth. Texas operations moved to a larger facility in Dallas in 2025. The company also opened a screw manufacturing operation in Oscoda, Michigan in 1999, and acquired ANViL Paints & Coatings in 2016.\n\n## Products\n\nPrefabrication is the company's distinguishing approach: seams that would otherwise be welded on the roof are heat-welded in the factory, and flashings for pipes, curbs and corners are made to measured dimensions, reducing rooftop seaming. Duro-Last uses its own PVC extrusion. Its range also includes TPO membranes, roll goods, metal roof and wall panels, insulation and cover boards, vapour barriers, skylights and coatings.","key_facts":[{"label":"First roof","value":"1978"},{"label":"Founder","value":"John R. Burt"},{"label":"Headquarters","value":"Saginaw, Michigan, US"},{"label":"Parent","value":"Amrize (acquired by Holcim 2023)"},{"label":"Known for","value":"Custom-prefabricated PVC membranes"}],"regions":["North America"],"aliases":["Duro-Last Roofing","Duro-Last, Inc."],"related":["pvc-roofing","single-ply-roofing","amrize","holcim-elevate","tpo-roofing"],"company":{"founded":"1978","headquarters":"Saginaw, Michigan, United States","website":"https://www.duro-last.com","parent":"Amrize","known_for":["Prefabricated PVC roofing membranes","Single-ply roofing systems"]},"sources":[{"title":"Duro-Last history","url":"https://duro-last.com/history/","publisher":"Duro-Last"},{"title":"Duro-Last","url":"https://www.duro-last.com/","publisher":"Duro-Last"}],"country":null},{"slug":"dutch-and-danish-reed-thatch","title":"Dutch and Danish Reed Thatch","type":"article","summary":"Water-reed thatched roofs of the Netherlands, Denmark and northern Germany, used on farmhouses, cottages and modern architect-designed houses.","body":"In the Netherlands, Denmark and the North Sea coast of Germany, thatch is made mainly from water reed (*Phragmites australis*) rather than cereal straw. Reed thatch has a long history on farmhouses and cottages in these countries and, unlike in many places, has also found a place on contemporary architecture.\n\n## History\n\nThatch was the normal roof of the North Sea lowlands for centuries. Settlements such as Hedeby, the Viking-age trading town in what is now northern Germany near the Danish border, very likely had thatched roofs. Fire was a persistent danger in towns, and in the 16th century Holland required fireproof roof materials, which encouraged the use of clay tiles and helped create a large hand-made tile industry. Thatch therefore became mainly a rural roof.\n\nIn Denmark, thatch survives on half-timbered farmhouses and vicarages such as Kølstrup near Kerteminde, on manor houses such as Liselund on Møn from the 1790s, and on cottages in coastal dune landscapes. Danish growers have also experimented with silvergrass (*Miscanthus*) as an alternative thatching crop.\n\n## Technique\n\nReed bundles are laid in courses from the eaves upward and fixed to battens with steel wire, screws or stitching, then dressed with a wooden beater (a \"leggett\") to form a smooth surface. Thatch needs a steep roof, typically 45-55 degrees. Dutch and Danish ridges are often finished with a cap of clay ridge tiles, turf, heather or, in modern work, a metal or composite ridge.\n\n## Modern use\n\nThe Netherlands has a strong thatching industry, and reed roofs appear on new villas and public buildings as well as on restorations. The House of the Five Senses at the Efteling theme park in Kaatsheuvel, Netherlands, is often described as having the largest thatched roof in the world.\n\n## Supply and fire\n\nMuch reed used in north-western Europe is now imported, from Eastern Europe, Turkey, China and South Africa among other sources. Fire risk and insurance costs are managed through fire-retardant treatments, fire barriers beneath the thatch, and careful detailing around chimneys.","key_facts":[{"label":"Main material","value":"Water reed (Phragmites australis)"},{"label":"Typical pitch","value":"45-55°"},{"label":"Notable roof","value":"House of the Five Senses, Kaatsheuvel"},{"label":"Fire regulation","value":"Holland required fireproof roofs in the 1500s"}],"regions":["Europe"],"aliases":["Rieten dak","Stråtag","Reetdach","Reed roof"],"related":["english-thatch","thatch","roofing-in-the-netherlands-and-belgium","roofing-in-scandinavia","pantile"],"sources":[{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Architecture of Denmark","url":"https://en.wikipedia.org/wiki/Architecture_of_Denmark","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"dutch-gable-roof","title":"Dutch Gable Roof (Gablet Roof)","category":"roof-forms","type":"term","summary":"A Dutch gable roof is a hip roof topped with a small gable (gablet) at the ridge ends; in Britain the term also means a curved, shaped gable parapet.","body":"In roof-form terminology, a Dutch gable roof (also called a gablet roof) is a hybrid in which the lower part of the roof is hipped on all sides and the upper part at each end rises into a small vertical gable, the gablet. It is the reverse of a half-hipped (jerkinhead) roof, where the gable is below and the small hip is at the top.\n\n## Two meanings\n\nThe term is used in two distinct ways, and context matters:\n\n- **Roof form (common in North America and Australia):** the hip-plus-gablet roof described above.\n- **Shaped gable (British and European usage):** a gable wall whose top is formed into a parapet of curves, sometimes with a pediment, that hides the diagonal roof lines behind it. Shaped \"Dutch gables\" are associated with the Netherlands, Belgium and, through trade and immigration, eastern England (notably Norfolk and Suffolk) and the Cape Dutch architecture of South Africa. A related form is the crow-stepped gable, with a stepped parapet.\n\n## Advantages of the gablet roof\n\n- Combines the all-round eaves and wind resistance of a hip roof with extra roof-space volume and the chance to place a window or vent in the gablet.\n- The gablet is a natural location for attic ventilation.\n\n## Construction\n\nFraming requires both hip and gable details: hip rafters or hip trusses on the lower slopes, a short ridge, and small gable walls set back from the eaves line. Flashing is needed where the gablet face meets the hip slopes below.\n\n## Regional notes\n\nGablet roofs are common on suburban houses in Australia and parts of the US. The same basic form, much elaborated with curved ridges and deep eaves, underlies the East Asian hip-and-gable roof (Japanese irimoya, Chinese xieshan, Korean paljak).","key_facts":[{"label":"Form","value":"Hip below, small gable (gablet) above"},{"label":"Reverse of","value":"Jerkinhead / half-hip"},{"label":"Alt. meaning (UK)","value":"Curved shaped-gable parapet"}],"regions":["Global","Europe","Oceania"],"aliases":["gablet roof","Dutch hip roof","shaped gable"],"related":["hip-roof","jerkinhead-roof","gable-roof","irimoya"],"company":null,"sources":[{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"},{"title":"Gable","url":"https://en.wikipedia.org/wiki/Gable","publisher":"Wikipedia"}],"country":null},{"slug":"eagle-roofing-products","title":"Eagle Roofing Products","category":"manufacturers","type":"company","summary":"Eagle Roofing Products is a family-owned US maker of concrete roof tile, founded in Rialto, California in 1989.","body":"Eagle Roofing Products is a North American manufacturer of concrete roof tile. It was founded in the autumn of 1989 by Robert Burlingame in Rialto, California, and is a division of Burlingame Industries, owned by the Burlingame family. The company's corporate office remains in Rialto.\n\n## Operations\n\nEagle operates four manufacturing plants serving the United States and Canada. Its Rialto plant is described by the company as the largest concrete tile plant in North America. The business has grown from five employees at its founding to more than 500. It has also opened satellite distribution yards in recent years.\n\n## Products\n\nConcrete roof tile is made from a mix of sand, cement and water that is extruded or pressed into shape, cured, and finished with colour. Eagle produces:\n\n- Tiles in seven profiles, from flat to high-barrel (S-shaped) designs.\n- More than 150 colours and blends, with availability varying by region.\n- Conventional-weight and lightweight tiles; lightweight tiles reduce dead load on the roof structure, which can matter when replacing lighter roof coverings.\n- Specialty installation patterns such as staggered and boosted (raised-butt) layouts used to imitate hand-laid clay or shake.\n\nUnder the name Secure Roof Components it supplies related components and systems, such as underlayments and fastening products.\n\n## Regulation and testing\n\nSeveral Eagle tile products have been approved for Florida's Miami-Dade high-velocity hurricane zone, one of the most demanding wind regimes in North American building codes. Concrete tile is common on homes in California, Arizona, Nevada, Florida and other warm regions of the US.\n\n## Warranty\n\nThe company offers a lifetime transferable limited product warranty on its tile.","key_facts":[{"label":"Founded","value":"1989, Rialto, California"},{"label":"Founder","value":"Robert Burlingame"},{"label":"Ownership","value":"Burlingame Industries (family-owned)"},{"label":"Plants","value":"4"},{"label":"Product","value":"Concrete roof tile"}],"regions":["North America"],"aliases":["Eagle Roofing","Burlingame Industries"],"related":["concrete-roof-tile","clay-roof-tile","westlake-royal-roofing","miami-dade-noa"],"company":{"founded":"1989","headquarters":"Rialto, California, United States","website":"https://eagleroofing.com","parent":"Burlingame Industries","known_for":["Concrete roof tile","Lightweight concrete tile"]},"sources":[{"title":"35 facts about Eagle Roofing Products in honor of 35 years in business","url":"https://eagleroofing.com/2024/01/35-facts-about-eagle-roofing-products-in-honor-of-35-years-in-business/","publisher":"Eagle Roofing Products"},{"title":"Eagle Roofing Products celebrates 35 years in manufacturing industry","url":"https://rooferscoffeeshop.com/post/eagle-roofing-products-celebrates-35-years-in-manufacturing-industry","publisher":"RoofersCoffeeShop"}],"country":null},{"slug":"earliest-fired-clay-roof-tiles","title":"Earliest Fired Clay Roof Tiles","category":"history","type":"article","summary":"The oldest known fired clay roof tiles: Neolithic pan and cover tiles from Qiaocun, China, and early flat tiles from mainland Greece.","body":"Fired clay tiles were one of the first manufactured roofing materials. They are heavy, fireproof and durable, and because broken pieces survive in the ground for thousands of years, they are much easier to trace than thatch or timber.\n\n## Qiaocun, China (about 2400-2200 BCE)\n\nExcavations between 2018 and 2021 at Qiaocun, on the edge of the Loess Plateau in north-west China, recovered a large assemblage of fired clay tiles dated to the early Longshan period, about 2400-2200 BCE. A 2023 study in *Scientific Reports* reconstructed how they fitted together. The tiles fall into three groups:\n\n- semi-cylindrical **cover tiles** (about a third of the finds);\n- trapezoidal **pan tiles** with raised side walls (about half);\n- **flat pan tiles**, possibly laid on rammed-earth gable walls.\n\nBecause pan and cover tiles were used together, the authors describe Qiaocun as the earliest known composite-tiled roof in the world. They estimate the roofs carried around half a tonne of tile, which needed thick walls to support it.\n\n## Early Greece\n\nIn western Eurasia, earlier ceramic tiles were flat and rectangular, with no interfitting parts. They roofed so-called corridor houses on the Greek mainland around 2650-2200 BCE. According to the Qiaocun study, interfitting parts appeared in western Eurasia roughly a thousand years after the Chinese composite tiles. The first fully interfitting Greek system identified so far is the 7th-century BCE Protocorinthian roof at Corinth.\n\n## Why composite tiles matter\n\nPairing a flat or dished pan with a curved cover tile is the basic principle behind the Roman imbrex and tegula, Chinese and Japanese temple roofs, and Spanish and Mission tiles today. Water runs in the pans, and the covers seal the joints between them. The Qiaocun finds show this idea existed far earlier than once thought.\n\n## Points of uncertainty\n\nNew excavations often push dates back, so \"earliest\" claims should be read as \"earliest known\". Dating relies on radiocarbon results from associated material, and reconstructions of roof layout from broken fragments involve some interpretation.","key_facts":[{"label":"Earliest composite-tiled roof","value":"Qiaocun, China, about 2400-2200 BCE"},{"label":"Early Greek flat tiles","value":"About 2650-2200 BCE (corridor houses)"},{"label":"Excavation","value":"2018-2021"}],"regions":["East Asia","Europe"],"aliases":["first roof tiles","Qiaocun tiles","Neolithic roof tiles"],"related":["ancient-greek-roof-tiles","imbrex-and-tegula","chinese-glazed-roof-tiles","clay-roof-tile"],"company":null,"sources":[{"title":"Reconstructing the earliest known composite-tiled roofs from the Chinese Loess Plateau","url":"https://www.nature.com/articles/s41598-023-35299-x","publisher":"Scientific Reports (Nature Portfolio)"},{"title":"Research Spotlight: Roof Tile Manufacturing Techniques","url":"https://www.ascsa.edu.gr/news/newsDetails/sapirstein-dissertation","publisher":"American School of Classical Studies at Athens"}],"country":null},{"slug":"earth-lodge","title":"Earth Lodge","category":"world-roofing","type":"article","summary":"A large, dome-shaped dwelling of the Great Plains, built of a heavy timber frame covered with willow, grass and thick sod over a shallow circular pit.","body":"The earth lodge is a semi-subterranean, dome-shaped dwelling built by Indigenous peoples of the Great Plains and parts of the Eastern Woodlands of North America. It is most closely associated with the Mandan, Hidatsa and Arikara of the upper Missouri River, and with the Pawnee, Otoe, Kansa, Omaha and Ponca further south. A heavy timber frame carried thick layers of plant material and earth, producing a mound-like roof with a smoke hole at the top and a covered entrance passage.\n\n## History\n\nTrue earth lodges appear in the early 1500s in Missouri River villages of central North Dakota and northern South Dakota, built by ancestors of the Mandan and Arikara. The Pawnee were building them in central Nebraska by 1600, and the Otoe, Omaha and Ponca by 1700. The Cheyenne briefly adopted the form in the mid-18th century. Earth lodges remained in use into the reservation era of the late 19th century. Earlier rectangular and square houses of the Plains (about 1000-1400 CE) are not considered true earth lodges.\n\n## Construction\n\n1. **Floor:** a shallow circular pit, typically less than 30 cm (1 ft) deep, with floor diameters of 6-18 m (20-60 ft).\n2. **Central frame:** forked posts joined by horizontal beams. Northern Plains lodges almost always had four; Central Plains lodges used four to twelve. Cottonwood was the usual timber.\n3. **Outer frame:** a ring of shorter posts linked by stringers, with split logs leaned from the stringers to the ground to form the walls.\n4. **Rafters:** laid from the outer stringers up to the central beams, leaving an opening for smoke.\n5. **Covering:** willow branches, then dried prairie grass or thatch, then thick sod and earth.\n\nAmong the Hidatsa, men helped raise the heavy central posts, while women built the rest of the structure under the direction of an experienced older woman; women owned and maintained the lodge. A lodge took about 7 to 10 days to build.\n\n## Size and use\n\nFinished lodges at the Knife River villages in North Dakota were 9-18 m (30-60 ft) across and 3-4.5 m (10-15 ft) high, and a lodge could house up to about 60 people. The entrance passage was 1.8-4.6 m (6-15 ft) long and usually faced south or east. In heavy rain or snow, an old bull boat could be turned over the smoke hole and propped up so smoke could still escape. Because cottonwood rots, lodges were rebuilt about every 7 to 10 years.\n\n## Meaning\n\nBuilding a lodge was a sacred task. In Pawnee cosmology the circular floor represented the earth and the dome the sky, and lodges were aligned so that the first light at the spring equinox struck the altar opposite the east-facing entrance.\n\n## Reconstructions\n\nReplica earth lodges can be seen at Knife River Indian Villages National Historic Site near Stanton, North Dakota, at Fort Abraham Lincoln State Park near Mandan, North Dakota, and at New Town on the Fort Berthold Reservation, where a ceremonial lodge over 27 m (90 ft) in diameter has been built.\n\n## Roofing significance\n\nThe earth lodge shows the trade-off typical of sod and earth roofs: a thick, insulating cover that also places a very heavy load on timber posts, which eventually rot and force rebuilding.","key_facts":[{"label":"Peoples","value":"Mandan, Hidatsa, Arikara, Pawnee, Omaha, Ponca, Otoe, Kansa"},{"label":"Period","value":"Early 1500s to late 19th century"},{"label":"Diameter","value":"Up to about 18 m (60 ft)"},{"label":"Roof layers","value":"Willow, grass, sod and earth on a cottonwood frame"},{"label":"Rebuilt","value":"About every 7-10 years"}],"regions":["North America"],"aliases":["earthlodge","Mandan earth lodge","Hidatsa earthlodge","Pawnee earth lodge"],"related":["pit-house","sod-roof","mud-roof","longhouse-roof","jomon-pit-dwellings"],"company":null,"sources":[{"title":"Earth lodge","url":"https://en.wikipedia.org/wiki/Earth_lodge","publisher":"Wikipedia"},{"title":"Earthlodges","url":"https://www.nps.gov/knri/learn/historyculture/earthlodge.htm","publisher":"US National Park Service, Knife River Indian Villages NHS"}],"country":null},{"slug":"earthquake-roofing","title":"Earthquakes and Roofs","type":"article","summary":"How roof weight, attachment and bracing affect building performance in earthquakes, and why heavy tile roofs on weak frames are a known risk.","body":"Earthquakes shake buildings sideways, and the forces a structure must resist are roughly proportional to its mass. The roof is at the top of the building, so a heavy roof increases the lateral forces on the walls below and the risk of collapse if those walls are weak. Roof coverings that are not well fastened can also fall from buildings during shaking.\n\n## Heavy roofs on light frames\n\nThe January 17, 1995 Great Hanshin (Kobe) earthquake in Japan, which killed more than 5,000 people, is a widely cited example. Many traditional wooden houses had heavy tiled roofs, weighing up to about two tonnes, that were intended to stay in place during typhoons. When the light timber frames beneath them failed, the roofs crushed the walls and floors below. Post-earthquake reconstruction in Japan moved toward reinforced walls and lighter roofs, although lighter roofs are more vulnerable to typhoon winds, illustrating a trade-off between hazards.\n\n## Roof weight and design\n\nClay and concrete tiles and natural slate are among the heaviest roof coverings; cement-based tiles have long been among the heaviest products because their porosity requires thickness. Metal panels, asphalt shingles and lightweight synthetic products weigh much less. In seismic regions, engineers account for roof weight when designing walls, bracing and connections. Replacing a light roof with a much heavier one, or adding heavy rooftop equipment or solar arrays, may require a structural review.\n\n## Diaphragms and connections\n\nA roof deck acts as a horizontal diaphragm that collects seismic forces and distributes them to the walls. Good performance depends on:\n\n- adequate nailing of sheathing to framing;\n- secure connections between roof framing and walls;\n- bracing of gable ends, parapets and chimneys, which often fail in earthquakes;\n- continuous load paths to the foundation.\n\n## Tile attachment\n\nLoose or mortar-only tiles can slide off during shaking and become falling hazards. Mechanical fastening of tiles (nails, screws, clips or wires), particularly at ridges, hips and eaves, reduces the chance of tiles dislodging during shaking.\n\n## Masonry chimneys and parapets\n\nUnreinforced masonry chimneys frequently break at the roofline and can fall through roofs. Bracing, reinforcement or replacement with lightweight flues are common retrofit measures in earthquake-prone areas.","key_facts":[{"label":"Key principle","value":"Seismic forces rise with building mass"},{"label":"Case study","value":"Great Hanshin earthquake, Jan 17, 1995 (more than 5,000 deaths)"},{"label":"Common weak points","value":"Heavy roofs on weak walls, loose tiles, chimneys, parapets"}],"regions":["East Asia","North America","Latin America","Oceania","Global"],"aliases":["seismic roofing","heavy roofs and earthquakes","roof seismic design"],"related":["clay-roof-tile","concrete-roof-tile","roof-to-wall-connection","rooftop-solar-pv"],"sources":[{"title":"Great Hanshin earthquake","url":"https://en.wikipedia.org/wiki/Great_Hanshin_earthquake","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Earthquake-resistant structures","url":"https://en.wikipedia.org/wiki/Earthquake-resistant_structures","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"eave-protection","title":"Eave Protection (Canada)","category":"components","type":"term","summary":"Eave protection is the Canadian building code requirement for a waterproof membrane at the lower edge of shingle, shake and tile roofs to resist ice-dam leaks.","body":"Eave protection is the term used in the National Building Code of Canada (NBC) and provincial codes based on it, such as the Ontario Building Code, for a membrane installed along the lower edge of a sloped roof to prevent leaks from ice dams and wind-driven water. It corresponds to the \"ice barrier\" of the US International Residential Code.\n\n## Extent\n\nUnder Part 9 Article 9.26.5.1, as reproduced from the Ontario Building Code, eave protection on shingle, shake or tile roofs must extend from the roof edge at least 900 mm (about 35 in) up the slope, and to a line not less than 300 mm (about 12 in) inside the inner face of the exterior wall. The inside-the-wall measurement is what usually controls on houses with wide overhangs.\n\n## Exceptions\n\nThe same reproduced text lists situations where eave protection is not required, including:\n\n- roofs over unheated garages, carports and porches;\n- roofs where the overhang, measured along the slope from the edge to the inner face of the exterior wall, exceeds 900 mm;\n- roofs with a slope of 1 in 1.5 or steeper;\n- regions with 3,500 or fewer degree-days;\n- asphalt shingle roofs installed under the code's low-slope shingle provisions.\n\nProvinces and municipalities can amend these rules, and code editions change, so the current adopted code should be checked.\n\n## Materials\n\nEave protection is commonly made from self-adhered modified-bitumen membranes, although the code also recognises other membrane types. Products are installed over the deck at the eaves, under the drip edge arrangement specified by the shingle manufacturer.\n\n## Related concepts\n\nThe comparable US requirement is the \"ice barrier\" of the International Residential Code. The underlying principle is the same: keep the lowest, coldest part of the roof watertight even when water is ponded behind ice.","key_facts":[{"label":"Code","value":"NBC Part 9, Article 9.26.5"},{"label":"Minimum up-slope","value":"900 mm (about 35 in)"},{"label":"Inside wall line","value":"Not less than 300 mm (about 12 in)"}],"regions":["North America"],"aliases":["eaves protection","eave membrane"],"related":["ice-and-water-shield","eaves","roofing-underlayment","ice-dam"],"company":null,"sources":[{"title":"Ontario Building Code 9.26.5 Required Eave Protection (unofficial reproduction)","url":"https://www.buildingcode.online/1940.html","publisher":"buildingcode.online"},{"title":"National Building Code of Canada, Part 9 roofing (NRC codes guides)","url":"https://codes-guides.nrc.ca/IA/05NBC/nbc05ei004377.html","publisher":"National Research Council Canada"}],"country":null},{"slug":"eaves","title":"Eaves","category":"components","type":"term","summary":"The eaves are the lower, horizontal edges of a roof that overhang the walls, shedding rainwater clear of the building.","body":"The eaves are the lower edges of a sloping roof, typically projecting beyond the face of the walls. The word comes from the Old English efes, meaning edge, and is used in the same form for singular and plural, although \"eave\" is accepted in American dictionaries.\n\n## Functions\n\n- **Shedding water:** the overhang throws rain away from the walls and windows and protects the vulnerable junction between roof and wall.\n- **Protecting the base of the building:** wide eaves reduce splashing and can shelter footings and paths.\n- **Shading:** in passive solar design, eave depth is tuned to latitude and orientation so high summer sun is blocked while lower winter sun reaches windows.\n- **Ventilation:** soffits beneath the eaves often hold intake vents for the roof space.\n- **Character:** deep bracketed eaves define styles such as American Craftsman; East Asian architecture uses elaborate bracket systems (Chinese dougong) to carry deep eaves.\n\n## Parts of an eave\n\n- **Rafter tails:** the projecting ends of rafters or truss top chords.\n- **Fascia:** the vertical board capping the rafter ends, which usually carries the gutter.\n- **Soffit:** the underside lining between fascia and wall; leaving rafters exposed creates an open eave.\n- **Drip edge or eaves trim:** metal at the deck edge.\n- **Ice barrier / eave protection:** a sealed membrane over the deck at the eaves in cold climates.\n\n## Design considerations\n\nDeep overhangs increase wind loads on the roof, so they must be designed for local wind speeds. In cold climates the overhang is the coldest part of the roof, which is why ice dams form there and codes require ice barriers measured from the eave edge to a line inside the wall. In planning law the dripline below the eave edge is often used to define the building's footprint relative to property boundaries.\n\n## Regional terms\n\nThe gutter fixed along the eaves is called an eavestrough in Canada.","key_facts":[{"label":"Etymology","value":"Old English efes, edge"},{"label":"Main parts","value":"Rafter tails, fascia, soffit"},{"label":"Canadian gutter term","value":"Eavestrough"}],"regions":["Global"],"aliases":["eave","eaves overhang","roof overhang"],"related":["fascia","soffit","rain-gutter","drip-edge","ice-and-water-shield","roof-rake"],"company":null,"sources":[{"title":"Eaves","url":"https://en.wikipedia.org/wiki/Eaves","publisher":"Wikipedia"},{"title":"Ice barrier code (IRC 2021 R905.1.2)","url":"https://www.jaspector.com/codes/irc-2021/ch09-roof-assemblies/ice-barrier-code/","publisher":"Jaspector"}],"country":null},{"slug":"ecostar","title":"EcoStar","category":"manufacturers","type":"company","summary":"EcoStar is a family-run US maker of synthetic slate and shake roofing made largely from recycled rubber and plastics, based in Holland, New York.","body":"EcoStar LLC is a US manufacturer of synthetic roofing tiles that imitate slate, shake, flat concrete tile and clay tile. Its products are made from blends of recycled rubber and plastics. The company is based in Holland, New York, and describes itself as a family business associated with the Staroba family.\n\n## History\n\nEcoStar's origins lie in a recycled rubber and plastic compound called StarLoy (from \"Staroba Alloy\"), developed in the 1970s. Roofing tiles made from this compound were first produced and brought to market in 1993, which the company describes as the first synthetic roofing on the market. In 2010 the business moved to Holland, New York, under the EcoStar LLC name, consolidating manufacturing, sales and marketing there.\n\n## Products\n\n- Slate-style tiles, offered with standard, enhanced or varied shadow lines.\n- Shake-style tiles.\n- Flat tiles imitating concrete tile.\n- A clay-tile-style product (Island Groove).\n- Accessories such as hip and ridge pieces.\n\nThe company states its slate and shake tiles contain up to 80 percent recycled plastics and rubbers.\n\n## Material context\n\nRecycled-content synthetic tiles are one route to diverting waste rubber and plastic from landfill, and their flexibility allows them to be nailed and cut with standard tools. As with other synthetic roofing, buyers and code officials generally look for third-party testing for fire classification, wind uplift and hail impact before approval in a given jurisdiction.\n\n## Market\n\nEcoStar competes in the North American composite roofing segment with producers such as DaVinci Roofscapes. These products are typically used on steep-slope residential and light commercial roofs where the appearance of slate or shake is wanted with lower weight.","key_facts":[{"label":"First products","value":"1993"},{"label":"Headquarters","value":"Holland, New York, US"},{"label":"Ownership","value":"Family business"},{"label":"Recycled content","value":"Up to 80% recycled plastics and rubbers"}],"regions":["North America"],"aliases":["EcoStar LLC"],"related":["synthetic-slate","davinci-roofscapes","natural-slate"],"company":{"founded":"1993","headquarters":"Holland, New York, United States","website":"https://www.ecostarllc.com","known_for":["Synthetic slate and shake tiles","Recycled-content roofing"]},"sources":[{"title":"About EcoStar","url":"https://www.ecostarllc.com/about-us/","publisher":"EcoStar"},{"title":"EcoStar","url":"https://www.ecostarllc.com/","publisher":"EcoStar"}],"country":null},{"slug":"electronic-leak-detection","title":"Electronic Leak Detection (ELD)","category":"tools-equipment","type":"article","summary":"Methods that use low or high voltage and a conductive layer under a membrane to pinpoint breaches in roofing and waterproofing.","body":"Electronic leak detection (ELD) locates holes, splits and seam defects in roof and waterproofing membranes by detecting electrical current passing through the breach. Most roofing membranes are electrical insulators, while the deck or a conductive layer beneath is a conductor. Where the membrane is breached, current can flow through the opening, and instruments detect that path. ASTM D7877 describes electronic methods for locating leaks in waterproof membranes, and ELD is widely used to test new roofs, green roofs, plaza decks and below-grade waterproofing.\n\n## Low-voltage methods\n\nLow-voltage methods (around 48 volts or less) need a **wet** membrane surface, so that a continuous film of water carries current to any breach.\n\n- **Vector mapping (electric field vector mapping)**: a perimeter wire around the test area is energised, and a technician uses a pair of probes to follow the voltage gradient in the water to the breach.\n- **Scanning platforms**: a wheeled unit with conductive brushes is pushed across the wetted membrane and signals when it crosses a breach.\n- **Vertical surface scanning**: a moistened sensor checks walls, parapets, corners and flashings.\n\n## High-voltage method\n\nHigh-voltage testing (typically 600 volts or more) is performed on a **dry** membrane. A brush or wand electrode is swept over the surface, and a spark jumps through any breach to the grounded substrate, triggering an alarm. The test voltage is set according to membrane thickness.\n\n## Requirements\n\n- A **conductive path beneath the membrane**. Concrete decks often provide this. Over insulation, a conductive layer, such as a scrim, screen or conductive primer installed under the membrane, is needed. Many roofs are designed with ELD in mind from the start.\n- **Non-conductive membranes**. Some methods cannot be used on conductive membranes such as black EPDM or heavy carbon-black materials; high-voltage testing is limited to non-conductive membranes.\n- **Isolation of grounded items** such as drains and metal penetrations to avoid false readings.\n- **Skilled operators**: results depend heavily on technician experience.\n\n## Advantages and limits\n\nELD can find breaches as small as pinholes and can be repeated after repairs, unlike flood testing, which IIBEC material describes as often inconclusive. Overburden such as insulation, drainage mats, root barriers and soil in protected or vegetated roofs can interfere with signals or shift apparent leak locations, which is why permanent leak detection grids are sometimes installed under green roofs.","key_facts":[{"label":"Standard","value":"ASTM D7877"},{"label":"Low-voltage","value":"Wet surface; vector mapping or scanning platform"},{"label":"High-voltage","value":"Dry surface; spark through breach to ground"}],"regions":["Global"],"aliases":["ELD","vector mapping","electric field vector mapping","spark testing"],"related":["roof-leak-detection","roof-moisture-survey","seam-probing","green-roof","single-ply-roofing"],"company":null,"sources":[{"title":"Electronic leak detection methods for locating leaks in waterproofing membranes","url":"https://iibec.org/publication-post/electronic-leak-detection-methods-for-locating-leaks-in-waterproofing-membranes","publisher":"IIBEC"},{"title":"IIBEC Technical Advisory No. 018-2019: Electronic Leak Detection","url":"https://iibec.org/publication-post/iibec-technical-advisory-no-018-2019-electronic-leak-detection/","publisher":"IIBEC"},{"title":"SpecTopics: Electronic Leak Detection (ELD) Systems","url":"https://www.carlislesyntec.com/Resources/Media/Blog-Landing-Page/SpecTopics/2023/04/06/Electronic-Leak-Detection-Systems","publisher":"Carlisle SynTec"},{"title":"Electronic leak detection (ELD) systems","url":"https://www.greenroofs.com/2023/05/05/electronic-leak-detection-eld-systems/","publisher":"Greenroofs.com"}],"country":null},{"slug":"holcim-elevate","title":"Elevate (formerly Firestone Building Products)","category":"manufacturers","type":"company","summary":"Elevate is a North American commercial roofing manufacturer, formerly Firestone Building Products, owned by Holcim from 2021 and part of Amrize since 2025.","body":"Elevate is a manufacturer of commercial roofing and wall systems in North America. It was known for decades as Firestone Building Products, a unit of the tyre maker Bridgestone, before being sold to Holcim in 2021 and renamed. Since Holcim's June 2025 separation of its North American business, Elevate has been part of Amrize. Its head office is in Nashville, Tennessee.\n\n## History\n\nHolcim completed its acquisition of Firestone Building Products on 1 April 2021, and on 21 June 2022 the business was rebranded as Elevate. The company describes itself as having around 40 years of experience in the commercial roofing market, and it operates about 21 manufacturing facilities in North America plus international operations.\n\n## Products\n\n- **Single-ply membranes**: EPDM (RubberGard), TPO (UltraPly) and PVC.\n- **Asphalt-based membranes** for built-up and modified-bitumen roofs.\n- **Polyiso insulation** boards (such as ISOGARD) used beneath membranes.\n- **Metal and wall products**: exposed- and concealed-fastener wall panels, soffits and metal roofing accessories.\n- **Lining**: geomembranes and pond liners derived from its membrane technology.\n\n## Market role\n\nEPDM and TPO together cover a large share of North American low-slope commercial roofs, and Elevate is one of a handful of companies that manufacture both. It sells through distributors and a network of authorised contractors, who can obtain system warranties from the manufacturer.\n\n## Membrane types\n\nEPDM is a synthetic rubber sheet joined with tapes or adhesives, while TPO and PVC are thermoplastics whose seams are fused with hot air. Each is installed over insulation such as polyiso, and the choice depends on climate, rooftop exposure and owner requirements for reflectivity.","key_facts":[{"label":"Former name","value":"Firestone Building Products"},{"label":"Sold to Holcim","value":"1 April 2021"},{"label":"Rebranded","value":"21 June 2022"},{"label":"Parent","value":"Amrize (since June 2025)"},{"label":"Head office","value":"Nashville, Tennessee"}],"regions":["North America","Global"],"aliases":["Holcim Elevate","Firestone Building Products","FSBP"],"related":["amrize","epdm-roofing","tpo-roofing","pvc-roofing","polyiso-insulation","carlisle-companies"],"company":{"headquarters":"Nashville, Tennessee, United States","website":"https://www.elevatecommercialbp.com","parent":"Amrize","known_for":["EPDM membranes (RubberGard)","TPO membranes (UltraPly)","Polyiso insulation"]},"sources":[{"title":"Firestone Building Products","url":"https://en.wikipedia.org/wiki/Firestone_Building_Products","publisher":"Wikipedia"},{"title":"Elevate","url":"https://www.elevatecommercialbp.com/us-en","publisher":"Elevate"}],"country":null},{"slug":"ember-resistant-roofing","title":"Ember-Resistant Roof Details","type":"term","summary":"Roof vents, gutters, closures and edges designed to keep wind-blown embers from igniting debris or entering the building during a wildfire.","body":"Ember-resistant roof details are the small components of a roof that determine whether wind-blown embers (firebrands) can lodge, ignite debris or enter the attic during a wildfire. A building with a fire-rated roof covering can still ignite if embers reach combustible material through vents or gaps.\n\n## Where embers get in\n\n- **Attic and roof vents.** Open vents draw air, and embers with it, into the attic.\n- **Gaps at eaves and ridges.** The curved profile of barrel tile and some metal panels leaves openings at the eave and ridge that can collect embers and nesting material.\n- **Gutters and valleys.** Accumulated leaves and needles ignite easily from embers and can then heat the roof edge and fascia.\n- **Open eaves.** Exposed rafter tails and open soffits provide many ledges and gaps.\n- **Junctions.** Where a roof meets a wall, dormer or chimney, debris collects and flashing gaps can admit embers.\n\n## Common measures\n\n- **Fine non-combustible mesh or ember-resistant vents.** Wire mesh over eave, gable, attic and roof vents fine enough to stop embers; tested vent products are available in some markets.\n- **Bird stops and eave closures** that fill the openings under the first course of tile or panels.\n- **Ridge closures** that block the gap under ridge tiles or caps.\n- **Non-combustible gutters and gutter guards**, plus regular cleaning.\n- **Enclosed soffits** built with non-combustible or ignition-resistant materials.\n- **Clearing debris** from the roof surface, valleys and around skylights and solar panels.\n\n## Vegetation and maintenance\n\nGuidance for the wildland-urban interface recommends keeping plants more than 1.5 m (5 ft) from walls, pruning tree limbs about 3 m (10 ft) back from roofs, and clearing debris from roofs and gutters. IBHS research on the area within about 1.5 m of a home found vegetation there can increase exposure even when watered. Embers can travel more than 1.6 km (1 mile) ahead of a fire front, so homes well inside a neighbourhood are also at risk.\n\n## Codes\n\nCalifornia's wildland-urban interface requirements, the International Wildland-Urban Interface Code, and Australia's AS 3959 all include provisions for vents, gaps and roof edges. In Australia the required detailing becomes stricter as the Bushfire Attack Level increases.","key_facts":[{"label":"Main entry points","value":"Vents, eave and ridge gaps, gutters"},{"label":"Tree clearance from roof","value":"About 3 m (10 ft)"},{"label":"Ember travel","value":"Can exceed 1.6 km (1 mile)"}],"regions":["North America","Oceania","Europe","Global"],"aliases":["ember resistance","ember-resistant vents","bird stop","ember guard"],"related":["wildfire-roofing","class-a-fire-rating","bushfire-attack-level"],"sources":[{"title":"Wildland-urban interface","url":"https://en.wikipedia.org/wiki/Wildland%E2%80%93urban_interface","publisher":"Wikipedia"},{"title":"Wildfire","url":"https://ibhs.org/wildfire/","publisher":"Insurance Institute for Business & Home Safety"},{"title":"ASTM E108-20a Standard Test Methods for Fire Tests of Roof Coverings","url":"https://store.astm.org/e0108-20a.html","publisher":"ASTM International"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"embodied-carbon-roofing","title":"Embodied Carbon of Roofing","type":"article","summary":"The greenhouse gas emissions from making, transporting, installing, maintaining and disposing of roofing materials, as opposed to operating the building.","body":"Embodied carbon is the greenhouse gas emitted in producing, transporting, installing, maintaining and disposing of building materials. It is distinct from operational carbon, the emissions from heating, cooling and powering a building. For roofs, embodied carbon includes the covering, underlayments, insulation, deck, fasteners and flashings, and the emissions from replacing them over a building's life.\n\n## Why it matters\n\nEmbodied carbon in buildings has been estimated at about 11 percent of global carbon emissions. As buildings become more energy-efficient, embodied emissions make up a growing share of their total footprint. Roofs contribute through materials that are often energy-intensive to produce, such as metals, petroleum-based membranes and insulation, and concrete or clay products fired or cured at high temperatures.\n\n## Measuring it\n\nEmbodied carbon is calculated through life cycle assessment (LCA). Results for specific products are published in Environmental Product Declarations (EPDs), which are verified by independent third parties and follow product category rules (in Europe, EN 15804; in North America and Asia, commonly ISO 21930). Comparing EPDs requires care: they must cover the same functional unit, the same life cycle stages, and comparable assumptions.\n\n## Factors that change a roof's footprint\n\n- **Service life.** A material with higher initial emissions can have a lower lifetime footprint if it lasts much longer and avoids replacements.\n- **Recycled content and recyclability.** Recycling aluminium requires only about 5 percent of the energy needed to produce primary aluminium, so recycled content sharply reduces embodied energy; end-of-life recycling also avoids landfill.\n- **Weight and transport.** Heavy materials shipped long distances carry higher transport emissions.\n- **Insulation type and thickness**, which affect both embodied and operational carbon.\n- **Maintenance**, such as recoating or periodic replacement of components.\n\n## Bio-based and low-carbon options\n\nTimber, cork, wool and cellulose-based materials store carbon absorbed during plant growth. Concrete products can use cement alternatives such as ground granulated blast-furnace slag to reduce emissions.\n\n## Policy\n\nEmbodied carbon is increasingly regulated. Buy Clean Colorado, signed in July 2021, uses EPDs for public projects; eight US states introduced embodied-carbon procurement policies in 2021; the Netherlands has limited embodied carbon since 2018, with other European countries following; and since May 2023 Toronto has required new city-owned buildings to keep upfront embodied emissions below 350 kg CO2e per m².","key_facts":[{"label":"Share of global emissions (buildings)","value":"About 11% (estimate)"},{"label":"Measured by","value":"Life cycle assessment, reported in EPDs"},{"label":"Recycled aluminium energy","value":"About 5% of primary production"},{"label":"Toronto limit (city buildings, 2023)","value":"Below 350 kg CO2e/m² upfront"}],"regions":["Global","Europe","North America"],"aliases":["embodied emissions","upfront carbon","embodied energy of roofing"],"related":["environmental-product-declaration","metal-roof-recycling","roof-lifespan-comparison","roof-life-cycle-cost","climate-change-and-roofing"],"sources":[{"title":"Embodied carbon","url":"https://en.wikipedia.org/wiki/Embodied_carbon","publisher":"Wikipedia"},{"title":"Environmental product declaration","url":"https://en.wikipedia.org/wiki/Environmental_product_declaration","publisher":"Wikipedia"},{"title":"Aluminium recycling","url":"https://en.wikipedia.org/wiki/Aluminium_recycling","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"emergency-roof-tarping","title":"Emergency Roof Tarping","category":"problems-maintenance","type":"article","summary":"Covering a damaged roof temporarily with a tarp or plastic sheeting to keep water out until permanent repairs can be made.","body":"Emergency tarping is the temporary covering of a damaged roof with a waterproof sheet to prevent further water entry. It is widely used after storms, fallen trees and fires, and insurers generally expect owners to take reasonable steps like this to limit further damage after a loss.\n\n## Materials\n\nTypical materials include heavy-duty polyethylene tarps with reinforced edges and grommets, or fibre-reinforced plastic sheeting supplied in rolls. Timber battens (furring strips) are used to clamp the sheet edges, and fasteners are driven through the battens rather than through the bare sheet, which would tear in wind. Sandbags are sometimes used where fastening is not possible, but they are less secure.\n\n## General method\n\n1. Cover well beyond the damaged area, ideally extending over the ridge so water runs off the top of the sheet rather than under it.\n2. Roll the upslope and edge parts of the tarp around battens and fix them to the roof framing or deck.\n3. Keep the sheet as taut as possible to prevent flapping, which loosens fasteners and tears the material.\n4. Leave the downslope edge so water drains off the roof, not into the building.\n5. Minimise new holes in sound roofing and note where fasteners were placed for later repair.\n\nOn tile, slate and metal roofs, methods differ, and fixings should avoid breaking more tiles or perforating panels unnecessarily.\n\n## Safety\n\nDamaged roofs are unstable, wet and littered with debris, and power lines may be down. Many homeowners are better served by a roofer or a disaster-response service. Anyone working on the roof needs proper footwear, a secured ladder and fall protection.\n\n## Operation Blue Roof\n\nIn the United States, the Army Corps of Engineers runs Operation Blue Roof on behalf of FEMA after some declared disasters. Contracted crews install fibre-reinforced sheeting free of charge on eligible primary residences. Eligibility criteria have included less than 50 percent structural damage to the roof and exclusions for flat roofs and for clay, slate or asbestos tile roofs.\n\nA tarp is a stop-gap: plastic degrades in sunlight and wind, so permanent repairs should follow as soon as practical.","key_facts":[{"label":"Purpose","value":"Prevent further water damage after a loss"},{"label":"Key technique","value":"Batten-clamped edges, over the ridge where possible"},{"label":"US programme","value":"Operation Blue Roof (USACE for FEMA)"}],"regions":["Global","North America"],"aliases":["roof tarp","blue roof","temporary roof covering"],"related":["storm-damage-inspection","wind-damage","roof-insurance-claims","roof-leak-detection"],"company":null,"sources":[{"title":"Temporary Roofing (archived)","url":"https://webcf.waybackmachine.org/web/20230516121335/http://www.usace.army.mil/Missions/Emergency-Operations/National-Response-Framework/Temporary-Roofing","publisher":"US Army Corps of Engineers"},{"title":"About Operation Blue Roof (archived)","url":"https://webcf.waybackmachine.org/web/20230419232638/http://www.usace.army.mil/Missions/Emergency-Operations/Blue-Roof-Information","publisher":"US Army Corps of Engineers"},{"title":"U.S. Army Corps of Engineers announces start of Blue Roof program in response to Hurricane Milton","url":"https://dvidshub.net/news/483171/us-army-corps-engineers-announces-start-blue-roof-program-response-hurricane-milton","publisher":"DVIDS"}],"country":null},{"slug":"en-10346","title":"EN 10346","summary":"EN 10346 is the European standard for continuously hot-dip coated steel sheet, covering zinc, zinc-magnesium, aluminium-zinc and other coatings used in roofing.","body":"EN 10346, *Continuously hot-dip coated steel flat products for cold forming – Technical delivery conditions*, is the European Standard for metallic-coated steel sheet and strip. It is the base specification for most steel roofing, wall cladding and rainwater products made in Europe, whether supplied bare or with an organic (paint) coating.\n\n## Editions\n\nThe 2015 edition replaced EN 10346:2009. CEN records show EN 10346:2015 revised by **EN 10346:2026**, with withdrawal of the 2015 edition effective in October 2026. National versions (such as BS EN 10346 and DIN EN 10346) follow the CEN edition.\n\n## Coating types\n\nThe standard covers several metallic coatings, each with its own code:\n\n- **Z** – zinc (galvanized)\n- **ZF** – zinc-iron alloy (galvannealed)\n- **ZA** – zinc-aluminium alloy\n- **AZ** – aluminium-zinc alloy (the 55% Al type sold as Galvalume or Aluzinc)\n- **AS** – aluminium-silicon alloy\n- **ZM** – zinc-magnesium alloy\n\nCoating mass is written after the code in grams per square metre, total for both sides (for example Z275 or AZ185). Steel grades for forming and structural uses are specified separately in the standard.\n\n## Use in roofing\n\nProfiled steel sheets, standing seam panels, steel tiles and rainwater systems in Europe are typically made from EN 10346 substrate. Pre-painted products add an organic coating on top of the metallic layer, and finished roofing sheets are assessed against separate European product standards for metal roofing. Zinc-magnesium coatings have grown in use because they offer good corrosion resistance at lower coating masses.\n\n## Comparison with North America\n\n- [ASTM A653](/astm-a653) covers zinc and zinc-iron coated sheet.\n- [ASTM A792](/astm-a792) covers 55% aluminum-zinc coated sheet.\n\nNorth American designations use different units (ounces per square foot), so coating masses must be converted rather than compared by number.","key_facts":[{"label":"Publisher","value":"CEN"},{"label":"Latest edition","value":"EN 10346:2026 (replacing 2015 edition)"},{"label":"Coating codes","value":"Z, ZF, ZA, AZ, AS, ZM"},{"label":"Coating mass unit","value":"g/m² both sides (e.g. Z275)"}],"regions":["Europe","Global"],"aliases":["BS EN 10346","DIN EN 10346","Z275","ZM coating","AZ185"],"related":["astm-a653","astm-a792","metal-roofing","ce-marking-construction-products"],"sources":[{"title":"EN 10346:2015","url":"https://genorma.com/en/standards/en-10346-2015","publisher":"Genorma (CEN catalogue data)"},{"title":"Hot-dip galvanization","url":"https://en.wikipedia.org/wiki/Hot-dip_galvanization","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"en-12326","title":"EN 12326","summary":"EN 12326 is the European standard for natural roofing slate, setting requirements for slate and carbonate slate used on roofs and walls.","body":"EN 12326 is the European Standard for natural slate used in roofing and cladding. **Part 1**, *Slate and stone for discontinuous roofing and external cladding – Specifications for slate and carbonate slate*, sets the product requirements. Test methods were historically published as a separate Part 2. The current edition of Part 1 is EN 12326-1:2014, which replaced the 2004 edition; CEN completed a periodic review of it in 2025.\n\n## Scope\n\nEN 12326-1 covers slate and carbonate slate (slate with a significant carbonate content) for discontinuous roofing, where individual slates overlap, and for external cladding. It excludes other stones and man-made products such as fibre-cement, concrete, polymer, metal and clay \"slates.\" It also does not deal with appearance, internal use, bonded cladding or installation rules.\n\n## What it measures\n\nThe standard sets out properties that a slate producer must test and declare, including:\n\n- dimensions, thickness and flatness tolerances\n- water absorption\n- resistance to freeze-thaw cycles\n- thermal cycling, which can reveal unstable minerals such as iron sulfides (pyrite) that may rust and stain or break down\n- carbonate content and resistance to sulfur dioxide exposure, which affects durability in polluted air\n- flexural strength, used to calculate minimum thickness\n\nResults are expressed using codes (for example for thermal cycling and water absorption) so that buyers can compare slates from different quarries. Because natural slate varies, quality depends on the specific quarry and seam.\n\n## Market context\n\nSpain is the world's largest producer and exporter of natural slate and supplies most of Europe's roofing slate; Brazil is the second-largest producer. Imported slates from outside Europe are also sold against EN 12326. Well-fixed slate roofs typically last many decades, and good slate can last far longer.\n\n## Related standards\n\n- In North America the equivalent is [ASTM C406](/astm-c406), which grades slate S1 to S3.\n- UK installation practice is in [BS 5534](/bs-5534); in France, slate roofing is governed by the [DTU 40](/dtu-40-series) series; in Germany, by the [ZVDH rules](/zvdh-fachregeln).","key_facts":[{"label":"Publisher","value":"CEN"},{"label":"Current edition","value":"EN 12326-1:2014"},{"label":"Replaced","value":"EN 12326-1:2004"},{"label":"Covers","value":"Slate and carbonate slate for roofing and cladding"},{"label":"Excludes","value":"Fibre-cement, concrete, polymer, metal and clay products"}],"regions":["Europe"],"aliases":["EN 12326-1","BS EN 12326","natural slate standard","EN 12326-2"],"related":["natural-slate","astm-c406","bs-5534","dtu-40-series","zvdh-fachregeln","spanish-slate","welsh-slate"],"sources":[{"title":"EN 12326-1:2014","url":"https://genorma.com/en/standards/en-12326-1-2014","publisher":"Genorma (CEN catalogue data)"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"},{"title":"EN 12326-1 Test Results: Welsh Penrhyn","url":"https://cdn.shopify.com/s/files/1/0242/1053/8577/files/Welsh_Penryn_Test_Results.pdf","publisher":"Test report (supplier data sheet)"},{"title":"The NHBC recently published a much-needed minimum specification for roofing slate","url":"https://www.barbourproductsearch.info/the-nhbc-recently-published-a-muchneeded-minimum-news013732.html","publisher":"Barbour Product Search"},{"title":"Roofing: Quality shows","url":"https://www.stonespecialist.com/news/roofing-quality-shows","publisher":"Natural Stone Specialist"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"en-1304","title":"EN 1304","summary":"EN 1304 is the European product standard defining requirements for clay roofing tiles and fittings for pitched roofs and wall cladding.","body":"EN 1304, *Clay roofing tiles and fittings – Product definitions and specifications*, is the European Standard that sets minimum requirements for clay (terracotta) roof tiles and their fittings, such as ridge, hip and verge pieces. It is published by CEN. The current edition is EN 1304:2013, which replaced EN 1304:2005. CEN confirmed the 2013 edition in 2023.\n\n## Scope\n\nThe standard applies to clay tiles and fittings for pitched roof coverings and for vertical wall cladding and lining. It covers the tile types defined in the standard, from plain double-lap tiles to single-lap profiled tiles, and applies to the products when they are placed on the market.\n\n## Key requirements\n\nEN 1304 deals with properties such as:\n\n- **Dimensions and regularity** – length, width, straightness and flatness tolerances so that tiles lay properly.\n- **Impermeability** – limits on water passing through the tile body.\n- **Flexural (breaking) strength** – minimum load a tile must carry.\n- **Frost resistance** – the ability to survive freeze-thaw cycles. Several test methods are used, reflecting different national traditions, with results declared by the manufacturer.\n- **Fire** – reaction to fire and external fire performance. Clay tiles are widely accepted as non-combustible and as meeting external fire requirements without testing.\n\nTest methods are given in the companion standard EN 539, which has separate parts for impermeability and frost resistance.\n\n## Why frost resistance matters\n\nClay is porous. Water absorbed into the tile can freeze and expand, causing flaking and cracking. Tile durability in cold climates depends heavily on firing quality and porosity, which is why frost-resistance declarations matter in northern and alpine Europe.\n\n## Related standards\n\n- [EN 490 and EN 491](/en-490-en-491) cover concrete tiles.\n- [EN 14437](/en-14437) tests the wind uplift resistance of installed clay or concrete tiles.\n- National codes of practice, such as [BS 5534](/bs-5534) in the UK, the German ZVDH rules and French DTU 40 series, govern installation.","key_facts":[{"label":"Publisher","value":"CEN (TC 128)"},{"label":"Current edition","value":"EN 1304:2013 (confirmed 2023)"},{"label":"Replaced","value":"EN 1304:2005"},{"label":"Test methods","value":"EN 539"},{"label":"Applies to","value":"Clay roof tiles and fittings"}],"regions":["Europe"],"aliases":["EN1304","BS EN 1304","clay tile standard"],"related":["clay-roof-tile","en-490-en-491","en-14437","bs-5534","dtu-40-series"],"sources":[{"title":"EN 1304:2013","url":"https://genorma.com/en/standards/en-1304-2013","publisher":"Genorma (CEN catalogue data)"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"en-13501-5","title":"EN 13501-5","summary":"EN 13501-5 is the European system for classifying how roofs perform when exposed to external fire, giving classes such as BROOF(t1) to FROOF(t4).","body":"EN 13501-5, *Fire classification of construction products and building elements – Part 5: Classification using data from external fire exposure to roofs tests*, is a European Standard published by CEN. It sets out how test results from the four methods in [CEN/TS 1187](/cen-ts-1187) are turned into a fire classification for a roof or roof covering. The current edition is EN 13501-5:2016, which replaced EN 13501-5:2005+A1:2009. CEN records list the 2016 edition as due for revision.\n\n## How classes are written\n\nA classification has two parts: a letter class and the test method it relates to.\n\n- The suffix **(t1), (t2), (t3)** or **(t4)** names the CEN/TS 1187 test used. Results from different tests are not interchangeable, because each test uses a different combination of burning brands, wind and radiant heat.\n- **BROOF** is the best class for each test. For the more severe tests (t3 and t4), intermediate classes such as CROOF and DROOF also exist.\n- **FROOF** means no performance was determined or the roof failed.\n\nSo a membrane system marked \"BROOF(t4)\" has met the top class in Test 4, while \"BROOF(t1)\" refers only to Test 1.\n\n## Why there are four tests\n\nThe four test methods reflect fire test traditions that existed in different European countries before harmonization. National building regulations still decide which test and class they require. A product sold in several countries may therefore need more than one classification. For example, UK guidance commonly refers to BROOF(t4), while other countries reference t1, t2 or t3.\n\n## Deemed-to-satisfy products\n\nSome roof coverings, such as natural slate, clay and concrete tiles and metal sheet, have been listed by European Commission decisions as deemed to satisfy external fire performance requirements without testing, within stated conditions. Other products, including bitumen membranes, single-ply membranes, green roofs and roofs with photovoltaic panels, generally need testing.\n\n## Role in CE marking\n\nUnder the EU Construction Products Regulation, external fire performance is one of the essential characteristics that can be declared in a product's Declaration of Performance. The EN 13501-5 class is the value that appears there. See [CE marking](/ce-marking-construction-products).\n\n## Outside Europe\n\nNorth America uses Class A, B and C ratings from [ASTM E108 / UL 790](/astm-e108-ul-790) instead. The two systems are not directly equivalent.","key_facts":[{"label":"Publisher","value":"CEN (TC 127)"},{"label":"Current edition","value":"EN 13501-5:2016"},{"label":"Replaced","value":"EN 13501-5:2005+A1:2009"},{"label":"Test basis","value":"CEN/TS 1187 Tests 1–4"},{"label":"Top class","value":"BROOF(t1) to BROOF(t4)"}],"regions":["Europe"],"aliases":["BROOF","Broof(t4)","BROOF(t1)","European roof fire classification"],"related":["cen-ts-1187","astm-e108-ul-790","ce-marking-construction-products","green-roof","uk-building-regulations"],"sources":[{"title":"EN 13501-5:2016","url":"https://genorma.com/en/standards/en-13501-5-2016","publisher":"Genorma (CEN catalogue data)"},{"title":"CEN/TS 1187:2012","url":"https://genorma.com/en/standards/cen-ts-1187-2012","publisher":"Genorma (CEN catalogue data)"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"en-14437","title":"EN 14437","summary":"EN 14437 is the European test method for measuring the wind uplift resistance of installed clay and concrete roof tiles on a test roof.","body":"EN 14437, *Determination of the uplift resistance of installed clay or concrete tiles for roofing – Roof system test method*, is a European Standard published by CEN. The current edition is EN 14437:2022, which replaced EN 14437:2004. It is adopted nationally as, for example, BS EN 14437 in the UK, NF EN 14437 in France and SS-EN 14437 in Sweden.\n\n## Scope\n\nThe method establishes how much uplift force an installed tile system can resist. It applies to clay tiles to [EN 1304](/en-1304) and concrete tiles to [EN 490](/en-490-en-491), whether they are laid without fixings or held by mechanical fixings such as clips, hooks, screws or nails.\n\nIt does not apply:\n\n- where fewer than one tile in three is fixed\n- to under-and-over tile systems (such as some Roman or Spanish profiles)\n\nA note in the standard says the method can be extended to other discontinuous roof elements, including natural and fibre-cement slates and stone, and, with adaptation, to solar panels fixed into tiled roofs.\n\n## How it is used\n\nResults from EN 14437 feed into national calculation methods. In the UK, [BS 5534](/bs-5534) uses tile uplift resistance data together with wind loads from [EN 1991-1-4](/en-1991-1-4) and its UK National Annex to determine which tiles must be fixed and with what fixings. Tile and fixing manufacturers use the results to produce fixing tables for different wind zones, roof pitches and building heights.\n\n## Why it matters\n\nSingle-lap tiles that lock into their neighbours rely partly on their own weight and partly on those side and head locks to resist wind. Testing a whole installed system captures how neighbouring tiles help hold each other down, which a test on a single tile would miss. This is why European practice increasingly calls for fixing schedules based on system tests rather than simple rules of thumb.","key_facts":[{"label":"Publisher","value":"CEN"},{"label":"Current edition","value":"EN 14437:2022 (replaced 2004 edition)"},{"label":"Applies to","value":"Clay tiles (EN 1304) and concrete tiles (EN 490)"},{"label":"Not applicable","value":"Fewer than every third tile fixed; under-and-over tiles"}],"regions":["Europe"],"aliases":["BS EN 14437","NF EN 14437","tile uplift test"],"related":["bs-5534","en-1304","en-490-en-491","en-1991-1-4","clay-roof-tile"],"sources":[{"title":"EN 14437:2022","url":"https://genorma.com/en/standards/en-14437-2022","publisher":"Genorma"},{"title":"SS-EN 14437:2022","url":"https://www.sis.se/en/produkter/construction-materials-and-building/construction-materials/ceramic-and-terracotta-building-products/ss-en-144372022/","publisher":"Swedish Institute for Standards"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"en-1991-1-3","title":"EN 1991-1-3 (Eurocode 1 Snow Loads)","summary":"EN 1991-1-3 is the part of Eurocode 1 that sets out how to calculate snow loads on roofs and structures in Europe.","body":"EN 1991-1-3, *Eurocode 1 – Actions on structures – Part 1-3: General actions – Snow loads*, is the European Standard for determining snow loads for the structural design of buildings and civil engineering works. It is one of the Eurocodes, the common European structural design standards published by CEN through technical committee CEN/TC 250.\n\n## Editions\n\nThe first-generation standard was EN 1991-1-3:2003, with a 2009 corrigendum and a 2015 amendment. It replaced the earlier pre-standard ENV 1991-2-3:1995. As part of the **second generation of Eurocodes**, CEN has published **EN 1991-1-3:2025**, and its catalogue records withdrawal of the 2003 edition from February 2025. National standards bodies set their own transition timetables, so the first-generation version may remain in use in some countries for a period.\n\n## Scope\n\nThe standard applies to sites at altitudes below 1,500 m (about 4,900 ft). Snow loads at higher altitudes may be dealt with in National Annexes. It does not cover all special cases, such as impact loads from snow sliding off a higher roof in every situation, or loads in regions with extreme snow conditions without national guidance.\n\n## How it works\n\nThe design snow load on a roof is calculated from:\n\n- **Characteristic ground snow load** – taken from national snow maps in each country's National Annex, based on location and altitude.\n- **Shape coefficients** – which convert ground snow to roof snow, depending on roof slope and shape (monopitch, duopitch, multi-span, cylindrical).\n- **Exposure and thermal coefficients** – which allow for wind exposure and heat loss through the roof.\n\nThe standard also covers **drifting** against parapets, higher roofs and obstructions, overhanging snow at eaves, and loads on snow guards.\n\n## Relevance to roofing\n\nRoofers and designers use EN 1991-1-3 results to size roof structures, select snow guards, and design for drifts where a low roof meets a taller wall. Drift zones are often where roof failures and leaks occur, because extra load and meltwater build up there.\n\n## National Annexes\n\nEach country publishes a National Annex with snow maps and nationally determined parameters. As a result, the same building may have quite different design snow loads in, for example, the UK, Germany or Norway. In North America, the equivalent role is played by ASCE 7 in the US and Part 4 of the [National Building Code of Canada](/national-building-code-of-canada).","key_facts":[{"label":"Publisher","value":"CEN (TC 250)"},{"label":"First generation","value":"EN 1991-1-3:2003 (+AC:2009, +A1:2015)"},{"label":"Second generation","value":"EN 1991-1-3:2025"},{"label":"Altitude limit","value":"Below 1,500 m (4,900 ft)"},{"label":"National data","value":"Snow maps in National Annexes"}],"regions":["Europe"],"aliases":["Eurocode 1 snow","EN 1991-1-3","BS EN 1991-1-3","snow load Eurocode"],"related":["en-1991-1-4","snow-load","snow-sliding","national-building-code-of-canada"],"sources":[{"title":"EN 1991-1-3:2003","url":"https://genorma.com/en/standards/en-1991-1-3-2003","publisher":"Genorma (CEN catalogue data)"},{"title":"Eurocode 1: Actions on structures","url":"https://en.wikipedia.org/wiki/Eurocode_1:_Actions_on_structures","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"en-1991-1-4","title":"EN 1991-1-4 (Eurocode 1 Wind Actions)","summary":"EN 1991-1-4 is the part of Eurocode 1 that sets out how to calculate wind loads on buildings, roofs and cladding in Europe.","body":"EN 1991-1-4, *Eurocode 1 – Actions on structures – Part 1-4: General actions – Wind actions*, is the European Standard for determining wind loads in structural design. It is published by CEN through technical committee CEN/TC 250 and forms part of Eurocode 1.\n\n## Editions\n\nThe first-generation standard was EN 1991-1-4:2005, with corrigenda in 2009 and 2010 and an amendment in 2010. It replaced the pre-standard ENV 1991-2-4:1995. As part of the second generation of Eurocodes, CEN has published **EN 1991-1-4:2026**, and its catalogue records withdrawal of the 2005 edition effective March 2026. Countries apply their own transition arrangements, so the earlier version may still be referenced locally for a time.\n\n## Scope\n\nThe standard gives rules for wind actions on:\n\n- buildings and civil engineering works up to 200 m (about 656 ft) high\n- bridges with no span longer than 200 m, if they meet dynamic response criteria\n- whole structures, parts of structures, and attached elements such as **cladding units, fixings** and barriers\n\nGuyed masts, lattice towers and lighting columns are covered elsewhere, and local thermal effects on wind and tornadoes are excluded.\n\n## How it applies to roofs\n\nWind pressure on a roof depends on:\n\n- the **basic wind velocity**, from national wind maps\n- **terrain** and **orography** (hills and escarpments)\n- building height and dimensions\n- **pressure coefficients** for different roof zones\n\nRoofs are divided into zones because suction is much higher at corners, edges and ridges than in the middle of the roof. Designers use separate coefficients for small loaded areas (such as individual fixings and tiles) and large areas (such as the roof structure).\n\n## Use with roofing codes\n\nNational roofing standards build on EN 1991-1-4. In the UK, [BS 5534](/bs-5534) uses its wind loads with the UK National Annex to determine tile and slate fixings, supported by uplift tests such as [EN 14437](/en-14437). Similar links exist with German and French roofing rules. Metal roof and membrane fixing calculations also rely on it.\n\n## National Annexes\n\nEach country's National Annex provides the wind map and choices for nationally determined parameters. In North America, ASCE 7 (US) and Part 4 of the [National Building Code of Canada](/national-building-code-of-canada) serve the same purpose.","key_facts":[{"label":"Publisher","value":"CEN (TC 250)"},{"label":"First generation","value":"EN 1991-1-4:2005 (+A1:2010)"},{"label":"Second generation","value":"EN 1991-1-4:2026"},{"label":"Height limit","value":"Structures up to 200 m (656 ft)"},{"label":"National data","value":"Wind maps in National Annexes"}],"regions":["Europe"],"aliases":["Eurocode 1 wind","BS EN 1991-1-4","wind load Eurocode"],"related":["en-1991-1-3","bs-5534","en-14437","wind-uplift","national-building-code-of-canada"],"sources":[{"title":"EN 1991-1-4:2005","url":"https://genorma.com/en/standards/en-1991-1-4-2005","publisher":"Genorma (CEN catalogue data)"},{"title":"Eurocode 1: Actions on structures","url":"https://en.wikipedia.org/wiki/Eurocode_1:_Actions_on_structures","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"en-490-en-491","title":"EN 490 and EN 491","summary":"EN 490 sets product requirements for concrete roof tiles and fittings in Europe, and EN 491 gives the matching test methods.","body":"EN 490 and EN 491 are the pair of European Standards that cover concrete roof tiles. **EN 490**, *Concrete roofing tiles and fittings for roof covering and wall cladding – Product specifications*, sets the requirements. **EN 491**, *Concrete roofing tiles and fittings for roof covering and wall cladding – Test methods*, describes how those requirements are tested. Both are published by CEN through technical committee CEN/TC 128.\n\n## Editions\n\n- **EN 491:2011** is the current test methods standard. It replaced EN 491:2004 and its 2005 corrigendum and was confirmed by CEN in 2024.\n- **EN 490:2011** replaced EN 490:2004 and its 2006 amendment. The CEN catalogue records the 2011 edition as withdrawn in January 2017. Users should check the current national version (for example BS EN 490 or DIN EN 490) before specifying.\n\n## What the standards cover\n\nThe scope covers concrete tiles and fittings for pitched roofs and for external and internal wall cladding. EN 490 also addresses tiles with surface coatings and fittings made from glued concrete components. Properties include:\n\n- dimensions and squareness\n- mass\n- transverse (flexural) strength\n- water impermeability\n- freeze-thaw resistance\n- fire behaviour\n\nAnnexes give information on surface characteristics and the performance of roof and wall assemblies.\n\n## Use\n\nConcrete tiles are a common lower-cost alternative to clay on pitched roofs. In Europe, compliance with EN 490 is the basis for CE marking of concrete tiles. Installation is governed by national practice such as [BS 5534](/bs-5534) in the UK.\n\n## Related standards\n\n- [EN 1304](/en-1304) covers clay tiles.\n- [EN 14437](/en-14437) tests uplift resistance of installed clay or concrete tiles.","key_facts":[{"label":"Publisher","value":"CEN (TC 128)"},{"label":"EN 491 current","value":"EN 491:2011 (confirmed 2024)"},{"label":"EN 490 status","value":"2011 edition recorded as withdrawn January 2017"},{"label":"Applies to","value":"Concrete roof tiles and fittings"}],"regions":["Europe"],"aliases":["EN 490","EN 491","BS EN 490","concrete tile standard"],"related":["concrete-roof-tile","en-1304","en-14437","bs-5534"],"sources":[{"title":"EN 490:2011","url":"https://genorma.com/en/standards/en-490-2011","publisher":"Genorma (CEN catalogue data)"},{"title":"EN 491:2011","url":"https://genorma.com/en/standards/en-491-2011","publisher":"Genorma (CEN catalogue data)"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"en-544","title":"EN 544","summary":"EN 544 is the European product standard for bitumen shingles with mineral and/or synthetic reinforcement, used for pitched roofs and wall cladding.","body":"EN 544, *Bitumen shingles with mineral and/or synthetic reinforcements – Product specification and test methods*, is the European Standard for what North Americans call asphalt shingles. It is published by CEN. The current edition is EN 544:2011, which replaced EN 544:2005. CEN records show the 2011 edition flagged for revision, with a draft revision (prEN 544) in development.\n\n## Scope\n\nThe standard specifies the properties, performance and test methods for finished bitumen shingles before they are laid. It also covers marking, labelling and the evaluation of conformity used for CE marking. It applies to shingles reinforced with mineral material (such as glass fibre), synthetic material, or both, intended for pitched roofs or wall cladding.\n\nIt does not cover roof design, installation methods or the performance of the complete roof system.\n\n## Characteristics covered\n\nAs a harmonised product standard, EN 544 lists the characteristics that a manufacturer declares in the Declaration of Performance, such as dimensions, mass, tensile and tear strength, nail shank pull-through, resistance to heat (flow resistance), water absorption, and reaction to and external fire performance. External fire performance is classified under [EN 13501-5](/en-13501-5).\n\n## Use in Europe\n\nBitumen shingles are used on houses, cabins and outbuildings in many European countries, though tile and slate remain the dominant pitched roof coverings in much of the continent. Installation rules come from national codes of practice, for example the German ZVDH rules or French DTU documents, rather than from EN 544 itself.\n\n## Comparison with North America\n\nThe US equivalent is [ASTM D3462](/astm-d3462). The two standards measure many similar properties but use different test methods and limits, so compliance with one does not demonstrate compliance with the other. North American wind ratings such as [ASTM D3161](/astm-d3161) are not part of EN 544.","key_facts":[{"label":"Publisher","value":"CEN"},{"label":"Current edition","value":"EN 544:2011 (revision in development)"},{"label":"Replaced","value":"EN 544:2005"},{"label":"Applies to","value":"Bitumen shingles, mineral and/or synthetic reinforcement"},{"label":"Used for","value":"CE marking and Declaration of Performance"}],"regions":["Europe"],"aliases":["EN544","bitumen shingle standard","BS EN 544"],"related":["astm-d3462","asphalt-shingle","en-13501-5","ce-marking-construction-products"],"sources":[{"title":"EN 544:2011","url":"https://genorma.com/en/standards/en-544-2011","publisher":"Genorma (CEN catalogue data)"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"en-988","title":"EN 988","summary":"EN 988 is the European specification for rolled zinc-copper-titanium sheet and strip used for roofing, cladding and rainwater goods.","body":"EN 988, *Zinc and zinc alloys – Specifications for rolled flat products for building*, is the European Standard for architectural zinc, the material often called titanium-zinc. It is published by CEN through technical committee CEN/TC 209 (Zinc and zinc alloys). The edition in use is EN 988:1996; CEN completed a periodic review of it in December 2024.\n\n## Scope\n\nThe standard sets requirements for rolled flat products made from a **zinc-copper-titanium alloy** and supplied as strip, sheet or cut lengths for building. It covers:\n\n- thicknesses from 0.6 to 1.0 mm (about 0.024 to 0.039 in)\n- widths from 100 to 1,000 mm (about 4 to 39 in)\n\nIt does not cover formed or shaped products, or products processed other than by cutting to size.\n\n## Why the alloy matters\n\nUnalloyed zinc is too brittle for roll-forming, folding and deep drawing. Small additions of copper and titanium improve strength, creep resistance and formability, which allows standing seam roofs, flat-lock panels, gutters and downpipes to be made from it. EN 988 sets limits for alloy composition, mechanical properties and dimensional tolerances so products from different mills behave consistently.\n\n## Use\n\nZinc roofing has a long history in continental Europe, especially France, Belgium, Germany and the Netherlands, and is used on roofs, façades and rainwater systems. Over time zinc forms a blue-grey patina of zinc carbonate that protects the metal. Pre-weathered and pigmented finishes are also produced so the patinated look is present from installation.\n\n## Installation considerations\n\nZinc must be detailed so that its underside is ventilated or otherwise protected, because moisture trapped against the back of the sheet can cause corrosion. Contact with copper run-off and some timbers should also be avoided. National rules such as the German [ZVDH](/zvdh-fachregeln) and French [DTU](/dtu-40-series) documents give detailing requirements.\n\n## Related standards\n\nEuropean product standards for metal roofing sheet reference EN 988 for zinc. In North America, there is no widely used equivalent ASTM product standard, and European zinc is commonly supplied to EN 988.","key_facts":[{"label":"Publisher","value":"CEN (TC 209)"},{"label":"Edition","value":"EN 988:1996 (reviewed 2024)"},{"label":"Alloy","value":"Zinc-copper-titanium"},{"label":"Thickness range","value":"0.6–1.0 mm (0.024–0.039 in)"},{"label":"Width range","value":"100–1,000 mm (4–39 in)"}],"regions":["Europe"],"aliases":["EN988","titanium zinc standard","BS EN 988"],"related":["zinc-roofing","standing-seam-metal-roof","astm-b370","copper-patina","dtu-40-series"],"sources":[{"title":"EN 988:1996","url":"https://genorma.com/en/standards/en-988-1996","publisher":"Genorma (CEN catalogue data)"},{"title":"Zinc","url":"https://en.wikipedia.org/wiki/Zinc","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"energy-star-roof-products","title":"ENERGY STAR Roof Products (discontinued)","summary":"ENERGY STAR Roof Products was a US EPA label for reflective roofing; the specification was sunset on June 1, 2022.","body":"ENERGY STAR is a US government energy-efficiency labelling program established in 1992 and run by the Environmental Protection Agency (EPA) with the Department of Energy. For many years it included a **Roof Products** category that labelled roofing materials with high solar reflectance, intended to lower cooling energy use. **The ENERGY STAR Roof Products specification was sunset on June 1, 2022**, and products can no longer earn the label.\n\n## Former criteria\n\nThe roof label rated the reflectance of the exterior surface only, not the full roof assembly. Criteria were split by slope:\n\n- **Low-slope roofs** – initial solar reflectance of at least 0.65 and weathered (aged) reflectance of at least 0.50.\n- **Steep-slope roofs** – initial solar reflectance of at least 0.25 and aged reflectance of at least 0.15.\n\nBecause it ignored insulation and thermal emittance, the label was considered less demanding than ENERGY STAR criteria in other product categories.\n\n## Sunset timeline\n\nAccording to EPA's specification page:\n\n- **5 June 2018** – EPA proposed sunsetting the specification and took public comment until 10 July 2018.\n- **28 May 2019** – EPA issued its decision memo to sunset.\n- **1 June 2022** – the specification ended.\n\nEPA published a decision memo and comment response explaining its reasoning; the specification page itself does not summarize the reasons.\n\n## What replaced it\n\nThere is no direct federal replacement label. In practice, the [Cool Roof Rating Council](/cool-roof-rating-council) (CRRC) product directory is now the main North American source of rated solar reflectance and thermal emittance values. Codes and programs that once referred to ENERGY STAR, such as some utility rebates and green building programs, generally refer to CRRC ratings or [SRI](/solar-reflectance-index) instead.\n\n## What owners should know\n\nOlder product literature, warranties and rebate paperwork may still mention ENERGY STAR roof qualification. Such claims refer to the program as it existed before mid-2022. Current compliance with energy codes such as [California Title 24](/title-24-cool-roof) or [ASHRAE 90.1](/ashrae-90-1) depends on rated reflectance and emittance values, not on the former label.","key_facts":[{"label":"Program owner","value":"US EPA (ENERGY STAR, est. 1992)"},{"label":"Status","value":"Sunset 1 June 2022"},{"label":"Former low-slope criteria","value":"Initial SR ≥ 0.65; aged SR ≥ 0.50"},{"label":"Former steep-slope criteria","value":"Initial SR ≥ 0.25; aged SR ≥ 0.15"}],"regions":["North America"],"aliases":["ENERGY STAR roofing","ENERGY STAR cool roof","Energy Star roof label"],"related":["cool-roof-rating-council","solar-reflectance-index","cool-roof","title-24-cool-roof"],"sources":[{"title":"ENERGY STAR Roof Products Specification Version 3.0","url":"https://www.energystar.gov/products/spec/roof_products_specification_version_3_0_pd","publisher":"US EPA ENERGY STAR"},{"title":"Cool roof","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"},{"title":"Energy Star","url":"https://en.wikipedia.org/wiki/Energy_Star","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"englert","title":"Englert","category":"manufacturers","type":"company","summary":"Englert is a US maker of metal roofing, gutter systems and roll-forming machines with more than 50 years in business; it joined Great Day Improvements in 2024.","body":"Englert is a North American manufacturer of metal roofing and seamless gutter systems, and of the roll-forming machines that contractors use to make them. The company describes more than 50 years of operation. In 2024 it became part of Great Day Improvements, a US home-improvement group.\n\n## Roofing products\n\nEnglert's roofing range includes:\n\n- Standing seam metal roof panels.\n- Metal wall panels and soffits.\n- Perimeter (edge) systems and roofing accessories.\n- Retrofit framing used to install a new metal roof over an existing roof.\n- Roofing coil supplied to fabricators.\n\n## Gutters\n\nEnglert's gutter lines include K-style gutters and the RainPro system, along with several leaf-protection products (MicroGuard, SureGuard and LeafGuard). It also sells gutter coil.\n\n## Machinery\n\nA distinctive part of Englert's business is equipment: it makes roofing and gutter roll-forming machines, as well as folding and shearing machines, and offers machine repair. Portable roll formers allow contractors to produce continuous-length metal panels or seamless gutters on or near the job site, from flat coil, rather than ordering pre-cut panels from a factory. This approach is common in North America and allows long panels without end laps, though transport, coil quality and on-site quality control become the installer's responsibility. Englert's warranty information covers panels produced on its portable roll-forming equipment.\n\n## Ownership\n\nEnglert joined the Great Day Improvements group in 2024. The company has not published its founding date on its main website.\n\n## Standing seam roofing\n\nStanding seam panels run from eave to ridge with raised seams joining neighbouring panels, and are fixed with concealed clips so that no fasteners pierce the weather surface. Clip design allows the panels to expand and contract with temperature changes.","key_facts":[{"label":"Years in business","value":"50+"},{"label":"Parent","value":"Great Day Improvements (since 2024)"},{"label":"Products","value":"Standing seam roofing, seamless gutters, roll-forming machines"}],"regions":["North America"],"aliases":["Englert Inc."],"related":["standing-seam-metal-roof","metal-roofing"],"company":{"website":"https://www.englertinc.com","parent":"Great Day Improvements","known_for":["Seamless gutter systems","Standing seam metal roofing","Portable roll-forming machines"]},"sources":[{"title":"About Englert","url":"https://www.englertinc.com/about-us","publisher":"Englert"},{"title":"Englert","url":"https://www.englertinc.com/","publisher":"Englert"}],"country":null},{"slug":"english-thatch","title":"English Thatch","type":"article","summary":"Thatched roofs of England in long straw, combed wheat reed or water reed, with regional styles and a 12-15 year ridge maintenance cycle.","body":"Thatch was the ordinary roof of rural England for centuries and remains a distinctive part of the countryside, especially in the south and east. A 2013 estimate put the number of thatched properties in the United Kingdom at about 60,000, maintained by roughly 1,000 full-time thatchers. Many are listed buildings, so the choice of material and style is often a heritage question as well as a practical one.\n\n## Materials\n\nThree materials dominate:\n\n- **Long straw** - threshed wheat straw, prepared so the stems lie in mixed directions. It gives a rounded, \"poured\" look and is traditional in much of southern and central England.\n- **Combed wheat reed** - wheat straw combed so the stems lie parallel with butts aligned, laid butt-end out. It is associated particularly with the south-west, including Devon.\n- **Water reed** - the common reed (*Phragmites*), harvested from wetlands. Traditionally it was used mainly in East Anglia, where it is often called Norfolk reed. It is applied as a single coat and stripped and replaced when worn out.\n\nWater reed is now used much more widely than in the past, and over 80% of the water reed used in the UK is imported, from sources including Turkey, Eastern Europe, China and South Africa. Thatching an average house with reed requires the harvest of roughly 4-5 acres (1.6-2 ha) of well-managed reed bed.\n\n## Pitch and lifespan\n\nThatch needs a steep roof, typically 45-55 degrees, so water runs off before it soaks in. With skilled work, straw thatch can last more than 50 years and imported water reed roughly 40 years on an average English roof. Between full re-thatches, the ridge, which takes the most weather, is usually replaced every 12-15 years. Some roofs in southern England retain base coats of thatch more than 500 years old, which are valued archaeologically.\n\n## Ridges and styles\n\nRidges may be laid flush with the main coat or as a raised \"block\" ridge, often cut into decorative scallops or points and pinned with hazel spars and liggers. Regional and individual thatchers' styles are a recognised part of the craft.\n\n## Fire and insurance\n\nThatch burns slowly, but sparks from chimneys and wood burners can ignite dry material; between 50 and 80 thatched roofs are destroyed by fire in the UK each year. Insurance is typically more expensive than for tiled or slate roofs. Good chimney maintenance, spark arrestors and smoke detectors in the roof space are standard precautions.","key_facts":[{"label":"UK thatched properties","value":"About 60,000 (2013 estimate)"},{"label":"Materials","value":"Long straw, combed wheat reed, water reed"},{"label":"Typical pitch","value":"45-55°"},{"label":"Ridge renewal","value":"Every 12-15 years"},{"label":"Imported water reed","value":"Over 80% of UK use"}],"regions":["Europe"],"aliases":["Thatched cottage","Norfolk reed thatch","Long straw thatch","Combed wheat reed"],"related":["thatch","irish-thatch","dutch-and-danish-reed-thatch","roofing-in-the-united-kingdom","roof-ridge"],"sources":[{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Architecture of Ireland","url":"https://en.wikipedia.org/wiki/Architecture_of_Ireland","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"environmental-product-declaration","title":"Environmental Product Declaration (EPD)","type":"standard","summary":"A verified document reporting the life cycle environmental impacts of a product, such as a roofing material, using standard rules.","body":"An Environmental Product Declaration (EPD) is a standardized, independently verified document that reports the environmental impacts of a product over its life cycle. EPDs are used across construction, including for roofing membranes, shingles, metal panels, tiles and insulation. They are a transparency tool: they disclose data so that products with the same function can be compared, but they do not certify that a product is environmentally friendly.\n\n## Standards\n\n- **ISO 14025** defines Type III environmental declarations, the category EPDs belong to, and sets the procedures for developing product category rules.\n- **ISO 14040 series** sets out the life cycle assessment (LCA) methods on which EPDs are based.\n- **EN 15804** (current version EN 15804:2012+A2:2019/AC:2021) is the European common product category rule for construction products.\n- **ISO 21930:2017** provides core rules for construction products and is commonly used by programme operators in North America and Asia.\n\n## Product category rules (PCRs)\n\nA PCR specifies how the LCA must be carried out and reported for a type of product, such as single-ply membranes or metal roofing. Sub-PCRs add detail for product subgroups. Following the same PCR is what makes EPDs within a category comparable.\n\n## Verification\n\nBefore publication, an EPD must be checked by an independent third-party verifier, who reviews the underlying LCA background report. The background report itself is usually not published.\n\n## What an EPD reports\n\nEPDs typically report indicators such as global warming potential (embodied carbon), ozone depletion, acidification, eutrophication, smog formation, resource use and waste. They state which life cycle stages are included, for example raw material supply and manufacturing only (cradle to gate) or the full life cycle including use and end of life.\n\n## Using EPDs for roofing decisions\n\n- Compare products only on the same functional unit (for example, per square metre of installed roof over a stated service life).\n- Check the life cycle stages covered; a cradle-to-gate EPD omits replacement and end-of-life effects that matter for roofs.\n- Note whether the EPD is product-specific or an industry-average EPD.\n- Consider service life and recyclability, which strongly influence a roof's lifetime impacts.\n\nEPDs are increasingly required by green building rating systems and by public procurement policies such as Buy Clean laws.","key_facts":[{"label":"Declaration type","value":"ISO 14025 Type III"},{"label":"European construction PCR","value":"EN 15804+A2"},{"label":"North American/Asian core rules","value":"ISO 21930:2017"},{"label":"Verification","value":"Independent third party"}],"regions":["Global","Europe","North America"],"aliases":["EPD","Type III environmental declaration"],"related":["embodied-carbon-roofing","roof-lifespan-comparison","metal-roof-recycling"],"sources":[{"title":"Environmental product declaration","url":"https://en.wikipedia.org/wiki/Environmental_product_declaration","publisher":"Wikipedia"},{"title":"Embodied carbon","url":"https://en.wikipedia.org/wiki/Embodied_carbon","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"epdm-roofing","title":"EPDM Roofing","category":"low-slope-systems","type":"article","summary":"Synthetic rubber single-ply membrane, usually black, joined with seam tapes or adhesives, and installed ballasted, mechanically attached or fully adhered.","body":"EPDM (ethylene propylene diene monomer) roofing is a thermoset synthetic rubber membrane. Because it is vulcanised, it cannot be heat-welded; seams and flashings are made with primers and seam tapes or adhesives. Its saturated polymer backbone gives it strong resistance to ozone, ultraviolet light and weathering.\n\n## Composition\n\nThe EPDM polymer is roughly half of a typical roofing compound. Carbon black (for reinforcement, UV screening and the black colour), processing oils (for low-temperature flexibility), antioxidants, antiozonants and curing agents make up much of the rest. White EPDM uses titanium dioxide instead. Properly formulated EPDM remains elastic to around minus 40 C (minus 40 F).\n\n## History\n\nEPDM entered the US commercial roofing market in the 1960s and spread widely in the 1980s, helped by bitumen price rises in the 1970s energy crisis and labour shortages. Roofs installed in the 1970s are reported to be still performing. In the 1980s factory seam tapes replaced liquid seam adhesives, reducing dependence on workmanship; self-adhering flashing accessories followed. EPDM is used worldwide, including large markets in North America and Europe; in New Zealand a related butyl rubber membrane is common.\n\n## Sheets\n\nStandard thicknesses are 45 mil (1.1 mm) and 60 mil (1.5 mm); 75 to 100 mil (1.9 to 2.5 mm) sheets are made for higher puncture resistance. Sheets are available in widths from about 1.4 m (54 in) to 15 m (50 ft) and lengths up to about 61 m (200 ft), so large roofs need few seams. Both non-reinforced and scrim-reinforced sheets are made.\n\n## Attachment\n\n- **Ballasted:** loose-laid and held by stone or pavers.\n- **Mechanically attached:** fasteners and plates in strips or at points.\n- **Fully adhered:** bonded with contact or water-based adhesive, or fleece-backed sheets in adhesive.\n\n## Considerations\n\nEPDM degrades in contact with bituminous materials, so separation layers or compatible products are needed when it is used over or beside bitumen. It does not contaminate rainwater runoff, which matters for rainwater harvesting.","key_facts":[{"label":"Type","value":"Thermoset (vulcanised) rubber"},{"label":"In US roofing since","value":"1960s"},{"label":"Common thickness","value":"45 and 60 mil (1.1, 1.5 mm)"},{"label":"Seaming","value":"Seam tape or adhesive (since 1980s, tape)"},{"label":"Max sheet width","value":"About 15 m (50 ft)"}],"regions":["Global","North America","Europe"],"aliases":["rubber roofing","EPDM membrane","ethylene propylene diene monomer"],"related":["single-ply-roofing","ballasted-roof-system","fully-adhered-roof-system","mechanically-attached-roof-system","cspe-hypalon-roofing"],"company":null,"sources":[{"title":"Technical Details: Thermoset Membranes - EPDM Technology and Repair","url":"https://roofingcontractor.com/articles/85516-technical-details-thermoset-membranes-epdm-technology-and-repairp","publisher":"Roofing Contractor"},{"title":"EPDM Historical Timeline","url":"https://epdmroofs.org/what-is-epdm/historical-timeline/","publisher":"EPDM Roofing Association"},{"title":"EPDM rubber","url":"https://en.wikipedia.org/wiki/EPDM_rubber","publisher":"Wikipedia"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"}],"country":null},{"slug":"eps-insulation","title":"EPS (Expanded Polystyrene) Roof Insulation","category":"low-slope-systems","type":"term","summary":"Lightweight closed-cell insulation board made by steam-expanding polystyrene beads, widely used in flat and tapered form on low-slope roofs.","body":"Expanded polystyrene (EPS) is rigid foam insulation made from polystyrene beads containing a blowing agent, usually pentane. The beads are pre-expanded with steam, then fused in moulds into large blocks that are cut into boards, including tapered boards for creating slope.\n\n## Properties\n\n- **Density:** commonly about 11-32 kg/m3 (0.7-2.0 lb/ft3); higher densities give higher compressive strength.\n- **Thermal conductivity:** about 0.032-0.038 W/(m.K), depending on density. Grey EPS with graphite or similar additives lowers this to roughly 0.029-0.034 W/(m.K).\n- **Vapour resistance factor:** about 30-70.\n- **Stability:** EPS uses air-filled cells once the pentane escapes, so its thermal value is relatively stable over time.\n\n## Uses on roofs\n\n- insulation under single-ply membranes, often with a cover board or separation layer\n- tapered insulation schemes\n- recovery boards and lightweight fill\n- composite boards laminated to polyiso or other facings\n\n## Fire\n\nPolystyrene foams are combustible. Unmodified EPS has an oxygen index near 18%, so flame retardant is added to meet North American requirements such as ASTM C578. In assemblies, fire performance depends on the deck, cover board, membrane and any thermal barrier.\n\n## Compatibility\n\nSolvent-based adhesives and some membranes, particularly plasticised PVC, can attack polystyrene, so manufacturers specify separation sheets or compatible adhesives. EPS is permeable to water through the gaps between beads, so it is not normally used above the membrane in inverted roofs, where XPS is preferred.\n\n## Water and freezing\n\nWater can collect in the gaps between bonded beads, and repeated freezing can loosen beads. EPS used on roofs is therefore kept dry beneath the membrane.","key_facts":[{"label":"Density","value":"About 11-32 kg/m3 (0.7-2.0 lb/ft3)"},{"label":"Conductivity","value":"About 0.032-0.038 W/(m.K)"},{"label":"Blowing agent","value":"Usually pentane"},{"label":"North American standard","value":"ASTM C578"}],"regions":["Global"],"aliases":["EPS","expanded polystyrene","beadboard"],"related":["xps-insulation","roof-insulation","tapered-insulation","polyiso-insulation"],"company":null,"sources":[{"title":"Polystyrene","url":"https://en.wikipedia.org/wiki/Polystyrene","publisher":"Wikipedia"},{"title":"Polyisocyanurate","url":"https://en.wikipedia.org/wiki/Polyisocyanurate","publisher":"Wikipedia"}],"country":null},{"slug":"eternit","title":"Eternit","category":"manufacturers","type":"company","summary":"Eternit is a fibre-cement trademark from Ludwig Hatschek's process patented in 1900, held in many markets by Belgium's Etex; other firms use it elsewhere.","body":"Eternit is a brand name for fibre-cement building products, including corrugated roofing sheets, slates and boards. It derives from the fibre-reinforced cement invented in the late nineteenth century by the Austrian Ludwig Hatschek, whose original mix was roughly 90 percent Portland cement and 10 percent asbestos fibre, formed in thin layers on a modified cardboard-making machine. The Eternit trademark is now owned by the Belgian building-materials group Etex.\n\n## Asbestos and its replacement\n\nFor much of the twentieth century asbestos-cement sheets were among the most widely used roof coverings in the world, especially on farm, industrial and low-cost housing roofs. Health risks led to asbestos being progressively prohibited from the 1970s onward in many countries, and cellulose and synthetic fibres were developed from the 1980s as replacements. Asbestos-free fibre cement is still produced, but some countries continue to permit asbestos in building materials.\n\n## Companies using the name\n\nBecause the Hatschek process was licensed widely, companies named Eternit were established in many countries, and not all of them belong to Etex:\n\n- **Eternit (Brazil)**, a roofing manufacturer active since 1940, makes fibre-cement roof sheets, ridge pieces and accessories, cement boards and cladding, and a concrete roof tile line called EternitMax.\n- **India**: the company now called Everest Industries, founded in 1934 as Asbestos Cement Ltd, traded as Eternit Everest Ltd from 1990 until adopting its current name in 2003.\n- In Europe, the brand is used by Etex for fibre-cement roofing and facade products in several countries.\n\n## Roofing use\n\nFibre-cement corrugated sheets remain common on agricultural and industrial buildings, and fibre-cement slates are used as a lighter, cheaper alternative to natural slate. Removal and disposal of old asbestos-cement roofs is regulated in many countries and generally requires specialist contractors.","key_facts":[{"label":"Invention","value":"Ludwig Hatschek, late 19th century"},{"label":"Trademark owner","value":"Etex (Belgium)"},{"label":"Product","value":"Fibre-cement sheets, slates and boards"}],"regions":["Global","Europe","Latin America","South Asia"],"aliases":["Eternit Brazil","Hatschek process"],"related":["fibre-cement-slate","asbestos-cement-roofing","everest-industries"],"company":{"known_for":["Fibre-cement roofing sheets","Fibre-cement slates"],"parent":"Etex (trademark)"},"sources":[{"title":"Eternit","url":"https://en.wikipedia.org/wiki/Eternit","publisher":"Wikipedia"},{"title":"Eternit","url":"https://www.eternit.com.br/","publisher":"Eternit S.A. (Brazil)"},{"title":"Everest Industries","url":"https://en.wikipedia.org/wiki/Everest_Industries","publisher":"Wikipedia"}],"country":null},{"regions":["Europe"],"company":null,"slug":"etruscan-terracotta-roofs","title":"Etruscan Terracotta Roofs","category":"history","type":"article","summary":"Etruscan temples of central Italy, from about 600 BC, had timber roofs edged with brightly painted terracotta antefixes, revetments and ridge statues.","aliases":["Etruscan roof terracottas","Etruscan temple roofs","architectural terracottas"],"body":"The Etruscans of central Italy built temples and halls whose most striking feature was the roof. Above walls of timber and mud brick, wide timber roofs were tiled and their edges covered with brightly painted terracotta, while rows of terracotta statues stood along the ridge. Unlike marble, terracotta could not be recycled, so a large amount of this roof decoration survives.\n\n## Early houses\n\nOrdinary Etruscan and early Italian houses were built largely of earth and organic materials. Villanovan hut urns, used for cremated remains, model houses with sloping roofs whose timbers cross at the ridge and project in V shapes, often with a smoke hole above the door. The so-called Casa Romuli on the Palatine in Rome was a hut of wooden posts, wattle-and-daub walls and thatch, possibly typical of ordinary housing.\n\n## Tiled halls and temples\n\nFired roof tiles reached Italy from Greece within about fifty years of their first use at Corinth around 700-650 BC. By the 6th century BC, large buildings such as the Archaic complex at Poggio Civitate (Murlo) and Zone F at Acquarossa had stone foundations, tiled roofs and elaborate architectural terracottas. Monumental temples began around 600 BC.\n\n## Roof decoration\n\n- **Revetments:** all the edges of the roof were faced with painted terracotta plaques. Large cavetto mouldings, often painted with vertical \"tongue\" patterns, formed the cornices, combined with round mouldings painted with scales.\n- **Antefixes:** decorated terracotta ends closed the cover tiles along the eaves; many attractively shaped and painted examples are in museums.\n- **Ridge sculpture:** Etruscan roofs often carried a row of statues along the central ridge, beyond the acroteria used on Greek temples. The Apollo of Veii belonged to such a group.\n- **Wide eaves:** reconstructions of the first Temple of Jupiter Optimus Maximus in Rome, traditionally dedicated in 509 BC and decorated by Etruscan specialists, show very deep eaves.\n\n## Tombs\n\nRock-cut chamber tombs, as in the Banditaccia necropolis, often reproduce wooden ceilings in stone, with carved beams that imitate the roofs of richer houses. They are an important source for how Etruscan roof frames looked.\n\n## Legacy\n\nThe Etruscan combination of tiled timber roofs and moulded terracotta passed into Roman temple building and the \"Tuscan\" temple later described by Vitruvius. The Etruscans also used the curved tile now called the coppo.","key_facts":[{"label":"Monumental temples","value":"From about 600 BC"},{"label":"Key sites","value":"Poggio Civitate, Acquarossa, Veii"},{"label":"Decoration","value":"Painted revetments, antefixes, ridge statues"}],"related":["roofing-in-italy","ancient-greek-roof-tiles","imbrex-and-tegula","coppo-tile","terracotta","antefix"],"sources":[{"title":"Etruscan architecture","url":"https://en.wikipedia.org/wiki/Etruscan_architecture","publisher":"Wikipedia"},{"title":"Coppo","url":"https://it.wikipedia.org/wiki/Coppo","publisher":"Wikipedia (Italian)"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"}],"country":null},{"slug":"european-federation-of-green-roof-associations","title":"European Federation of Green Roof and Green Wall Associations (EFB)","summary":"The EFB is a federation of national green roof and green wall associations in Europe, founded in 1997 by Austrian, German and Swiss groups.","body":"The European Federation of Green Roof and Green Wall Associations (EFB) brings together national associations for green roofs and living walls across Europe. It was established in 1997 as the European Federation of Green Roof and Living Wall Associations by the green roof associations of Austria, Germany and Switzerland. By 2026 it had 20 member associations. Its office team is based in Austria, and its website is efb-greenroof.eu.\n\n## Members\n\nAfter the three founders, associations joined from countries and regions including the Netherlands, Belgium, France, Scandinavia, Hungary, Italy, Poland, the Czech Republic, Portugal, England, Spain and Romania.\n\n## Aims and activities\n\nThe federation's shared goal is to make cities more resilient, healthy and attractive by putting vegetation on roofs, walls and facades, complementing other nature-based solutions in urban areas. Its activities include:\n\n- **EUGIC conference.** The EFB is behind the European Urban Green Infrastructure Conference (EUGIC), first held in Vienna in 2015, followed by Budapest (2017), London (2019) and Berlin (2023).\n- **EU research.** Green roof and wall technology has been included in EU research programmes such as Horizon 2020 and Horizon Europe, with EFB working groups engaging with the European Commission.\n- **Publications, webinars, seminars and training** for members and the public.\n- **Market research.** It is preparing a market report on the European building greening industry.\n\n## European context\n\nGreen roofs have a long history in Europe, from traditional sod roofs in Scandinavia and Iceland to modern extensive roofs in German-speaking countries, where many cities require or subsidise green roofs on flat roofs. Technical practice in much of Europe draws on the German FLL green roof guidelines, alongside national standards. Typical extensive systems are lightweight and planted with sedum and other drought-tolerant species, while intensive systems create usable roof gardens.\n\n## Related bodies\n\nIn North America, Green Roofs for Healthy Cities plays a similar role. National associations in member countries handle local training, certification and policy work.","key_facts":[{"label":"Founded","value":"1997"},{"label":"Founders","value":"Austrian, German and Swiss green roof associations"},{"label":"Members","value":"20 national associations (2026)"},{"label":"Conference","value":"EUGIC (first held 2015, Vienna)"}],"regions":["Europe"],"aliases":["EFB","European Federation of Green Roof and Living Wall Associations"],"related":["green-roof","green-roofs-for-healthy-cities","fll","sod-roof"],"company":{"founded":"1997","website":"https://efb-greenroof.eu","known_for":["European Urban Green Infrastructure Conference (EUGIC)"]},"sources":[{"title":"About us","url":"https://efb-greenroof.eu/about-us/","publisher":"EFB"},{"title":"EFB home page","url":"https://efb-greenroof.eu/","publisher":"EFB"}],"category":"organizations","type":"organization","country":null},{"slug":"everest-industries","title":"Everest Industries","category":"manufacturers","type":"company","summary":"Everest Industries is an Indian maker of fibre-cement roofing sheets, boards and pre-engineered steel buildings, founded in 1934 as Asbestos Cement Ltd.","body":"Everest Industries Limited is an Indian building-products company headquartered in Mumbai, with its registered office in Nashik district, Maharashtra. It was founded in 1934 under the name Asbestos Cement Ltd and is listed on India's two main stock exchanges, the BSE and NSE.\n\n## Name changes\n\n- **1934**: Founded as Asbestos Cement Ltd.\n- **1983**: Renamed Everest Building Products Ltd and listed on the Bombay Stock Exchange.\n- **1990**: Renamed Eternit Everest Ltd.\n- **1995**: Listed on the National Stock Exchange of India.\n- **2003**: Adopted the name Everest Industries.\n\nThe 1990s name reflects the company's place in the international family of fibre-cement producers that used the Eternit name, which descends from the Hatschek fibre-cement process.\n\n## Products\n\n- **Fibre-cement roofing sheets**: corrugated sheets, colour-coated sheets and \"cool roofing\" sheets designed to reduce heat gain.\n- **Boards and panels** for walls, ceilings, cladding and mezzanine flooring.\n- **Pre-engineered steel buildings (PEBs)**, produced at plants in Roorkee (Uttarakhand), Ranchi (Jharkhand) and Dahej (Gujarat).\n\n## Context\n\nCorrugated fibre-cement sheets are used in India on homes, farm buildings and small industrial units, fixed to light steel or timber frames. As the company's original name shows, the industry historically used asbestos as reinforcement. Fibre-cement sheets compete with coated steel sheets, which are made by companies such as Tata Steel and JSW Steel. The company's colour-coated and cool roofing sheets are aimed at reducing heat gain inside buildings in hot climates.\n\n## Listing\n\nAs a listed company, Everest reports to Indian stock exchanges and lists four subsidiaries.","key_facts":[{"label":"Founded","value":"1934, as Asbestos Cement Ltd"},{"label":"Headquarters","value":"Mumbai, India"},{"label":"Listing","value":"BSE, NSE"},{"label":"Products","value":"Fibre-cement roofing sheets, boards, PEBs"}],"regions":["South Asia"],"aliases":["Eternit Everest","Everest Building Products","Asbestos Cement Ltd"],"related":["fibre-cement-slate","eternit","asbestos-cement-roofing"],"company":{"founded":"1934","headquarters":"Mumbai, India","website":"https://www.everestind.com","known_for":["Fibre-cement roofing sheets","Fibre-cement boards","Pre-engineered steel buildings"]},"sources":[{"title":"Everest Industries","url":"https://en.wikipedia.org/wiki/Everest_Industries","publisher":"Wikipedia"},{"title":"Everest Industries","url":"https://www.everestind.com/","publisher":"Everest Industries"}],"country":null},{"slug":"fascia","title":"Fascia","category":"components","type":"term","summary":"A fascia is the vertical board fixed along the ends of the rafters at the eaves, closing the roof edge and usually supporting the gutter.","body":"A fascia (or fascia board) is the long, vertical board fixed across the ends of the rafters or truss tails at the eaves. It caps and protects the exposed timber ends from weather, provides a straight, finished line to the roof edge, supports the outer edge of the soffit, and in most houses carries the gutter brackets. The word comes from the Latin for band, and in classical architecture it refers to a flat horizontal band in an entablature.\n\n## Construction\n\n- Traditionally a sawn softwood board, painted for protection.\n- In North America, wood fascia is often wrapped with formed aluminium or steel coil, or replaced with composite or PVC trim.\n- In the UK, uPVC fascia boards are widely used on houses built since the late 20th century, often installed as a system with soffits, vents and dry verge components.\n- On some modern roofs a metal fascia system replaces the board entirely.\n\n## Relationship to other parts\n\nThe drip edge or eaves trim sits on top of the roof deck and over the top of the fascia so water drips clear of it. The gutter is fixed to the fascia, either with brackets or with hidden hangers. At gable ends the corresponding board along the sloping edge may be called a rake fascia, verge board or bargeboard.\n\n## Problems\n\nFascia boards are exposed to water from overflowing or leaking gutters and from water that wicks behind gutters where the drip edge is missing, so rot is common. Ice dams can also damage fascias and gutters. When fascia rot is found, the rafter tails behind it are often affected too.\n\n## In UK ventilation design\n\nOver-fascia vents mounted on top of the fascia are a common way to provide eaves ventilation into the roof and batten space in UK cold roofs.","key_facts":[{"label":"Fixed to","value":"Rafter or truss ends at eaves"},{"label":"Supports","value":"Gutters, outer edge of soffit"},{"label":"Common materials","value":"Timber, aluminium-wrapped wood, uPVC, PVC"}],"regions":["Global"],"aliases":["fascia board","eaves fascia"],"related":["soffit","eaves","rain-gutter","drip-edge","bargeboard"],"company":null,"sources":[{"title":"Eaves","url":"https://en.wikipedia.org/wiki/Eaves","publisher":"Wikipedia"},{"title":"Batten space ventilation for pitched roofs","url":"https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/LABCW%20Batten%20space%20ventilation%20for%20pitched%20roofs%20V2.pdf","publisher":"LABC Warranty"},{"title":"Drip Edge and the IRC","url":"https://www.jlconline.com/how-to/framing/drip-edge-and-the-irc_o/","publisher":"JLC"}],"country":null},{"slug":"fastener-back-out","title":"Fastener Back-Out","category":"problems-maintenance","type":"term","summary":"Gradual loosening of screws or nails so their heads rise above the roof surface, breaking the seal and creating leak points.","body":"Fastener back-out is the slow withdrawal of a fastener from its substrate so that its head sits proud of the surface. It is most discussed on exposed-fastener (through-fastened) metal roofing, where each screw passes through the panel and seals with a compressed washer, but the same mechanism affects nails on asphalt roofs (see nail pops) and fasteners in single-ply attachment plates.\n\n## Why screws back out\n\n- **Thermal movement.** Metal panels expand and contract daily. Repeated movement works on the screw and can enlarge the hole, especially in wood purlins or battens, until the screw loosens.\n- **Wood shrinkage and decay.** Timber supports dry out, shrink and lose holding power, or rot where water has entered.\n- **Wrong fastener or length.** Too short a screw, the wrong thread for the substrate, or missed purlins leave little grip.\n- **Driving errors.** Over-driving crushes or splits the washer; under-driving leaves it uncompressed. Angled screws do not seat squarely.\n- **Washer ageing.** Rubber or EPDM washers harden and crack with ultraviolet exposure and age, so even a screw that has not moved can leak.\n- **Vibration and wind** in exposed locations.\n\n## Signs\n\nRaised screw heads, tilted heads, washers that are cracked or missing, rust stains running from screw holes, and leaks along purlin lines are typical. Poorly installed screws can look normal, so careful close inspection is needed on older roofs.\n\n## Repair\n\nCommon remedies include re-seating loose screws, replacing them with slightly larger-diameter screws so the threads bite fresh material, and replacing degraded washers or entire fasteners. Owners of exposed-fastener roofs often plan periodic fastener checks as part of routine maintenance. Concealed-fastener systems such as standing seam use clips that allow panels to move, which reduces this problem but does not eliminate the need for correct installation.","key_facts":[{"label":"Main roof type affected","value":"Exposed-fastener metal roofing"},{"label":"Main drivers","value":"Thermal movement, substrate shrinkage, washer ageing"},{"label":"Typical fix","value":"Reseat or upsize screws; renew washers"}],"regions":["Global"],"aliases":["screw back-out","backed-out fasteners","loose roofing screws"],"related":["through-fastened-metal-panels","standing-seam-metal-roof","nail-pops","red-rust","oil-canning"],"company":null,"sources":[{"title":"Fastener Failure in a Metal Roofing World","url":"https://www.floridaroof.com/Fastener-Failure-in-a-Metal-Roofing-World-1-21588.html","publisher":"Florida Roofing Magazine"},{"title":"Metal roof fasteners backing out","url":"https://greenbuildingadvisor.com/question/metal-roof-fasteners-backing-out","publisher":"GreenBuildingAdvisor"},{"title":"Why exposed screws fail on a historic metal roof","url":"https://www.theroofingcompany.com/blog/p.260820000/why-exposed-screws-fail-on-a-historic-metal-roof/","publisher":"The Roofing Company"}],"country":null},{"slug":"fibre-cement-slate","title":"Fibre-Cement Slate","type":"term","summary":"A thin, flat roofing slate made of cement reinforced with fibres; a uniform, lower-cost manufactured alternative to natural slate.","body":"A fibre-cement slate is a manufactured roofing slate made from cement reinforced with fibres, pressed into thin, flat, uniform units. Fibre-cement slates resemble natural slate from a distance but are lighter, more regular and generally cheaper. They are also called man-made, artificial or composite slates.\n\n## Composition and history\n\nFibre cement was invented as asbestos cement: Ludwig Hatschek patented it in Austria in 1900 (some sources give 1901), and asbestos-cement slates became common across Europe during the 20th century. From the 1980s, manufacturers replaced asbestos with cellulose-based fibres because of the health risks. Modern slates are usually supplied with a factory-applied coloured surface coating. Old slates made before the change may contain asbestos and need careful handling.\n\n## Properties\n\n- **Uniformity**: every slate has the same size, thickness and colour, making setting out quick.\n- **Fire**: cement-based products are usually classed as non-combustible under the European fire classification system (EN 13501-1).\n- **Appearance**: they weather differently from natural slate; the surface coating can fade, and edges can show erosion over time.\n- **Life**: generally shorter than natural slate, and more dependent on coating quality.\n\n## Fixing\n\nFibre-cement slates are usually laid double-lap and nailed through pre-punched holes. Hook fixing, common on the continent for natural slate, is also used. Because they are thinner and more flexible than natural slate, manufacturers specify minimum pitches and headlaps that differ from natural slate, so their installation guides should always be followed.\n\n## Use\n\nFibre-cement slates are common on new estates, extensions and commercial buildings. Heritage bodies generally regard them as unsuitable replacements for natural slate on historic or listed buildings because they look and age differently.\n","key_facts":[{"label":"Material","value":"Cement reinforced with cellulose-based fibres"},{"label":"Asbestos replaced","value":"From the 1980s"},{"label":"Invention of fibre cement","value":"1900 (Hatschek, as asbestos cement)"}],"regions":["Europe","Latin America","Global"],"aliases":["man-made slate","artificial slate","composite slate","cement slate"],"related":["natural-slate","asbestos-cement-roofing","synthetic-slate","slate-hook-fixing","corrugated-fibre-cement-sheet"],"sources":[{"title":"Fiber cement siding","url":"https://en.wikipedia.org/wiki/Fiber_cement_siding","publisher":"Wikipedia"},{"title":"Eternit","url":"https://en.wikipedia.org/wiki/Eternit","publisher":"Wikipedia"},{"title":"Asbestos cement","url":"https://en.wikipedia.org/wiki/Asbestos_cement","publisher":"Wikipedia"},{"title":"Hook vs nail fixing: the facts","url":"https://www.ssqgroup.com/technical-articles/hook-vs-nail-fixing-the-facts","publisher":"SSQ"},{"title":"Ludwig Hatschek","url":"https://en.wikipedia.org/wiki/Ludwig_Hatschek","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"fiberglass-shingle","title":"Fibreglass Shingle","type":"term","summary":"An asphalt shingle built on a glass-fibre mat; the dominant form of asphalt shingle sold today.","body":"A fibreglass shingle (US spelling: fiberglass) is an asphalt shingle whose reinforcing core is a non-woven mat of glass fibres bonded with resin, usually urea-formaldehyde. The mat is coated with asphalt that contains powdered mineral filler, then surfaced with granules. Almost all asphalt shingles made today are of this type.\n\n## History\n\nGlass-fibre mats were introduced in 1960 with limited success at first. Improvements in mat and coating technology followed, and by about 1982 fibreglass shingles had overtaken organic-felt shingles in the United States. By 2011 organic shingles had disappeared from North American production.\n\n## Properties\n\n- **Lighter**: the glass mat needs less asphalt, so area weights are typically about 1.8-2.3 lb/sq ft (8.8-11.2 kg/m²).\n- **Fire resistance**: glass-mat shingles can achieve a Class A fire rating under ASTM E108 / UL 790, the highest class.\n- **Moisture**: the glass mat does not absorb water, so the shingle is less prone to rot-related curling.\n- **Brittleness**: early products could crack in cold weather or during handling; polymer-modified asphalts were later introduced to improve flexibility.\n\n## Standards\n\nIn the United States, ASTM D3462 is the main product standard for glass-felt asphalt shingles surfaced with mineral granules, and the International Building Code requires asphalt shingles to comply with it. The standard sets a minimum Elmendorf tear strength of 1,700 g. In Canada, CSA standards apply, and in Europe glass-fibre bitumen shingles are covered by the European harmonised standard for bitumen shingles.\n\n## Quality\n\nWeight alone is no longer a reliable sign of quality. Industry commentary notes that mat strength and coating quality vary between products, and a moderate-weight shingle with a strong mat can outperform a heavier one with a weak mat.\n","key_facts":[{"label":"Mat","value":"Glass-fibre, resin-bonded"},{"label":"Area weight","value":"About 1.8-2.3 lb/sq ft (8.8-11.2 kg/m²)"},{"label":"Fire rating","value":"Up to Class A"},{"label":"US standard","value":"ASTM D3462 (min. 1,700 g tear strength)"}],"regions":["North America","Global"],"aliases":["fiberglass shingle","glass-mat shingle","glass-fibre shingle"],"related":["asphalt-shingle","organic-mat-shingle","three-tab-shingle","architectural-shingle","bitumen-shingle"],"sources":[{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Q&A: Fiberglass vs. Organic Shingles","url":"https://www.jlconline.com/how-to/interiors/q-a-fiberglass-vs-organic-shingles_o/","publisher":"Journal of Light Construction"},{"title":"Asphalt Shingle Types (3-Tab vs. Laminated Architectural), ASTM Classifications & Thermal Behavior","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-types-astm-thermal","publisher":"Open Exam Prep"}],"category":"materials","company":null,"country":null},{"slug":"fijian-bure","title":"Fijian Bure","category":"world-roofing","type":"article","summary":"Traditional thatched Fijian house on a raised rock base with a steep hipped roof; once a men’s house, now also a resort bungalow.","body":"A *bure* is a traditional Fijian building of timber and thatch. In strict traditional usage it was the men's house of a clan, where initiated men met, ate and slept, while the family dwelling was the *vale*. In modern Fiji, and especially in tourism, \"bure\" has come to mean any thatched house or a detached resort bungalow.\n\n## Construction\n\nTraditional Fijian houses were built from whatever local materials were available, with components stacked, tied with rope, or both. Both bure and vale were dark and smoky inside, with no windows and usually a single low door. Vale had hearth pits for cooking, and their packed-earth floors were covered first with grass or fern leaves and then with mats of pandanus or coarse coconut leaf.\n\n## Cyclone performance\n\nResearchers from Massey University, writing in the *International Journal of Disaster Risk Reduction*, found that traditional bure are more likely to withstand tropical cyclones than many contemporary timber-framed houses. They identified several features that match international guidance for cyclone-resistant building:\n\n- relatively short walls;\n- few and small wall openings;\n- an elevated rock base;\n- a hipped roof with steep slopes and small eaves.\n\nA hipped roof avoids a tall gable wall exposed to the wind, and small eaves leave less overhang for wind to get under and lift. Bure can also be rebuilt quickly from locally gathered materials.\n\nAfter Tropical Cyclone Winston struck Fiji on 20 February 2016, residents of Navala village reported that their traditional houses performed better than contemporary ones, and that most damage came from debris torn from modern houses. The researchers warned that some villages appear to have lost traditional building knowledge and argued that it should be included in disaster relief and \"build back better\" programmes.\n\n## Modern use\n\nMost Fijian homes now have metal roofs; in the 2021 Multiple Indicator Cluster Survey, thatch, palm or coconut leaf was recorded for only about 0.1% of households. Tourist bure range from simple huts to luxury villas built to modern standards, often with plumbing and electricity that traditional bure lacked. Some writers note that *icili* would be a more traditionally correct older Fijian word for such cabins.\n\n## Related forms\n\nThe bure belongs to a wider Pacific family of steep-roofed, lashed and thatched buildings, including the Samoan [fale](/samoan-fale), the Kiribati [maneaba](/maneaba) and the Vanuatu [nakamal](/nakamal).","key_facts":[{"label":"Country","value":"Fiji"},{"label":"Traditional role","value":"Men’s house (family house: vale)"},{"label":"Roof form","value":"Steep hipped roof with small eaves"},{"label":"Base","value":"Elevated rock base"},{"label":"Modern share","value":"Thatch on about 0.1% of household roofs (MICS 2021)"}],"regions":["Oceania"],"aliases":["Bure","Vale","Fijian house"],"related":["roofing-in-fiji","samoan-fale","maneaba","nakamal","thatch","palm-thatch","hip-roof","wind-uplift"],"company":null,"sources":[{"title":"Bure (Fiji)","url":"https://en.wikipedia.org/wiki/Bure_(Fiji)","publisher":"Wikipedia"},{"title":"Traditional knowledge key to building cyclone-resistant homes in Fiji","url":"https://www.scimex.org/newsfeed/traditional-knowledge-key-to-building-cyclone-resistant-homes-in-fiji","publisher":"Scimex"},{"title":"Fiji MICS 2021, main material of roof (HC5)","url":"https://microdata.worldbank.org/catalog/5955/variable/V151","publisher":"World Bank Microdata Library"},{"title":"Fiji: Post-Disaster Needs Assessment - Tropical Cyclone Winston","url":"https://www.gfdrr.org/en/publication/fiji-post-disaster-needs-assessment-tropical-cyclone-winston-february-2016","publisher":"GFDRR / World Bank"}],"country":null},{"slug":"filippo-brunelleschi","title":"Filippo Brunelleschi","category":"history","type":"person","summary":"Florentine architect and engineer (1377-1446) who designed and built the dome of Florence Cathedral without timber centring.","body":"**Filippo Brunelleschi** (1377 - 15 April 1446) was a Florentine goldsmith, sculptor, architect and engineer, regarded as one of the founders of Renaissance architecture. His best-known work is the great brick dome of Florence Cathedral, a milestone in the history of large roofs.\n\n## Early career\n\nAt about fifteen Brunelleschi was apprenticed to a goldsmith and to a sculptor in cast bronze, and he became a master goldsmith in December 1398. In **1401** he entered the competition to design new bronze doors for the Florence Baptistery. The jury could not decide between him and **Lorenzo Ghiberti** and asked them to collaborate; Brunelleschi refused to share control.\n\n## Perspective\n\nBrunelleschi is credited with being the first to describe a precise system of **linear perspective**, which he demonstrated with paintings of Florentine buildings. It shaped Western painting until the 19th century.\n\n## The dome\n\nIn 1418 the wool merchants' guild held a competition for the unbuilt dome of the cathedral. Brunelleschi won, again over Ghiberti. Between **1420 and 1436** he built an octagonal double-shell brick dome without temporary wooden centring, using herringbone brickwork and new hoisting machines of his own invention. He also designed the lantern, begun shortly before his death and completed by Michelozzo in 1461.\n\n## Engineering and patents\n\nIn **1421** Brunelleschi received one of the first modern patents, for a river vessel intended to carry goods on the Arno more cheaply. In 1427 he built a boat, *Il Badalone*, to carry marble; it sank on its maiden voyage.\n\n## Other buildings\n\nAll in Florence:\n\n- **Ospedale degli Innocenti** (begun 1419), a foundling hospital;\n- **San Lorenzo**, including the nave, aisles and Old Sacristy;\n- **Santo Spirito**, begun in 1436, his last major commission;\n- the **Pazzi Chapel**, completed around 1469, after his death.\n\n## Burial\n\nBrunelleschi was buried in the crypt of Florence Cathedral, beneath the dome he built. His dome remains one of the most studied roofs in architectural history.","key_facts":[{"label":"Born","value":"1377, Florence"},{"label":"Died","value":"15 April 1446, Florence"},{"label":"Major work","value":"Dome of Florence Cathedral (1420-1436)"},{"label":"Early patent","value":"1421, river vessel"}],"regions":["Europe"],"aliases":["Brunelleschi","Pippo"],"related":["florence-cathedral-dome","pantheon-dome","dome"],"company":null,"sources":[{"title":"Filippo Brunelleschi","url":"https://en.wikipedia.org/wiki/Filippo_Brunelleschi","publisher":"Wikipedia"},{"title":"Florence Cathedral","url":"https://en.wikipedia.org/wiki/Florence_Cathedral","publisher":"Wikipedia"}],"country":null},{"slug":"flashing-failure","title":"Flashing Failure","category":"problems-maintenance","type":"article","summary":"Breakdown of the metal or membrane pieces that seal a roof at walls, chimneys, valleys and penetrations; a leading cause of roof leaks.","body":"Flashing failure is any loss of watertightness in the components that bridge the joint between a roof covering and something that interrupts it: a wall, chimney, skylight, vent pipe, valley or roof edge. Because these joints concentrate water and movement, flashings are among the first places a roof leaks, often long before the main covering is worn out.\n\nFlashings may be sheet metal (galvanised or coated steel, aluminium, copper, lead, zinc), flexible membrane, or preformed rubber boots. Many details use two parts: a base or step flashing integrated with the roof covering, and a counterflashing (cap flashing) fixed to the wall or chimney that laps over it.\n\n## Common failure modes\n\n- **Sealant used instead of laps.** Details that rely on caulk or roofing cement rather than shingle-fashion overlaps fail as the sealant ages and cracks.\n- **Missing or short step flashing** along sidewalls, so water runs behind the covering.\n- **Counterflashing pulling out of mortar joints** or surface-mounted counterflashing whose sealant has failed.\n- **Corrosion** of thin or incompatible metals, or galvanic corrosion where dissimilar metals touch.\n- **Cracked rubber pipe boots**, which degrade in sunlight.\n- **Missing kick-out (diverter) flashing** where a roof edge meets a wall, sending water into the wall rather than the gutter.\n- **Mortar flashings (fillets)** on tile and slate roofs that crack with movement.\n- **Physical damage** from ice, foot traffic, or reroofing where old flashings were reused.\n\n## Signs\n\nInside, failures show as stains at ceilings next to chimneys, skylights and walls, or wet sheathing around a penetration seen from the attic. Outside, look for gaps, lifted edges, rust, cracked sealant, displaced counterflashing and staining on siding below roof-to-wall joints.\n\n## Repair approach\n\nLasting repairs restore proper overlaps so water is shed by gravity. Re-caulking may stop a leak temporarily but is generally treated as maintenance, not a permanent fix. On many reroofing jobs, flashings are renewed rather than reused, particularly when they are corroded or were bent during removal. On historic slate and tile roofs, traditional lead soakers and cover flashings are usually replaced like for like.","key_facts":[{"label":"Usual locations","value":"Chimneys, sidewalls, skylights, valleys, vent pipes, roof edges"},{"label":"Key principle","value":"Overlaps shed water; sealant is a back-up only"},{"label":"Two-part details","value":"Base or step flashing plus counterflashing"}],"regions":["Global"],"aliases":["failed flashing","leaking flashing","chimney flashing leak"],"related":["step-flashing","counter-flashing","roof-leak-detection","kickout-flashing","roof-valley","pipe-boot"],"company":null,"sources":[{"title":"Troubleshooting Roof Leaks: Problems & Solutions","url":"https://www.jlconline.com/how-to/roofing/troubleshooting-roof-leaks-problems-solutions_o/?o=3","publisher":"Journal of Light Construction"},{"title":"NJ Home Inspector Explains Common Chimney Flashing Problems That Cause Roof Leaks","url":"https://looksmarthomeinspections.com/nj-home-inspector-explains-common-chimney-flashing-problems-that-cause-roof-leaks/","publisher":"Look Smart Home Inspections"},{"title":"Counter-Flashing - Roof Leak Protection Basics Guide","url":"https://www.jaspector.com/wiki/counter-flashing","publisher":"Jaspector"}],"country":null},{"slug":"flat-roof","title":"Flat Roof","category":"roof-forms","type":"article","summary":"A flat roof is a roof that is almost level, laid to a slight fall for drainage and covered with a continuous waterproof membrane rather than overlapping units.","body":"A flat roof is a roof with little or no visible slope. In practice, flat roofs are not truly level: they are laid to a small fall so water drains to gutters, scuppers or internal outlets, and they are covered with continuous waterproof membranes rather than the overlapping shingles, tiles or slates of pitched roofs. In North America they are usually called low-slope roofs.\n\n## History and geography\n\nFlat roofs are among the oldest roof forms, traditional in arid and low-rainfall regions of the Middle East, North Africa, South Asia, the Mediterranean and the American Southwest, where packed earth, mud or lime over timber beams formed usable roof terraces. Modern waterproofing materials have since made low-slope roofs practical in wet climates and on large commercial buildings, and they are now common on single-storey extensions and contemporary houses.\n\n## Drainage falls\n\nCodes and standards set minimum falls. British guidance commonly cites a minimum finished fall of 1 in 80 for flat roofs so that construction tolerances do not leave ponding; US codes likewise set minimum slopes for each type of low-slope covering. Tapered insulation and crickets are used to create falls and direct water to outlets.\n\n## Coverings\n\n- Built-up roofing (BUR) with multiple bitumen plies.\n- Modified bitumen (SBS or APP) sheets.\n- Single-ply membranes: EPDM, TPO, PVC.\n- Liquid-applied membranes.\n- Metal (such as zinc or copper with batten-roll or standing seams on very low slopes).\n- Asphalt and mastic asphalt, traditional in the UK.\n- Green (vegetated) roofs over a waterproofing layer.\n\n## Warm, cold and inverted\n\nFlat roofs are classified by insulation position: cold (insulation below the deck with a ventilated void), warm (insulation above the deck under the membrane) and inverted (insulation above the membrane). Many authorities now favour warm or inverted designs because ventilated cold flat roofs are prone to condensation.\n\n## Advantages and drawbacks\n\nFlat roofs can provide usable terraces and space for equipment and solar arrays, and avoid the volume of a pitched roof. They rely entirely on the membrane for waterproofing, are sensitive to ponding and detailing at upstands, and need regular inspection.","key_facts":[{"label":"Typical UK minimum fall","value":"1 in 80"},{"label":"North American term","value":"Low-slope roof"},{"label":"Classification","value":"Cold, warm, inverted"}],"regions":["Global","Europe"],"aliases":["low-slope roof","flat-roofed","deck roof","roof terrace","flat roofing","level roof"],"related":["warm-roof","cold-roof","shed-roof","parapet","butterfly-roof","low-slope-roof","positive-drainage","protected-membrane-roof","reinforced-bitumen-membrane","mastic-asphalt-roofing"],"company":null,"sources":[{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"},{"title":"Rain gutter","url":"https://en.wikipedia.org/wiki/Rain_gutter","publisher":"Wikipedia"},{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"},{"title":"BS 6229:2018 and flat roofing systems","url":"https://ikogroup.co.uk/?p=820","publisher":"IKO"},{"title":"Flat roof","url":"https://www.designingbuildings.co.uk/wiki/Flat_roof","publisher":"Designing Buildings Wiki"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"Top tips to help you get the most out of your flat roof","url":"https://www.sigroofing.co.uk/?p=12082","publisher":"SIG Roofing"}],"country":null},{"slug":"flat-seam-roofing","title":"Flat Seam (Flat-Lock) Roofing","category":"installation","type":"article","summary":"Flat seam roofing covers a roof with small rectangular metal pans whose folded edges lock together flat; seams are soldered on low slopes.","body":"Flat seam, or flat-lock, roofing uses small rectangular sheets of metal, traditionally about 18 x 24 in (460 x 610 mm) in copper, with edges folded so that each pan hooks into its neighbours on all four sides. Because the joints lie flat, the roof has a smooth, tiled appearance. The method suits flat and low-slope roofs, very steep surfaces, and curved forms such as domes, barrel vaults and cupolas, and was widely used historically with tinplate, terne and copper.\n\n## How it is built\n\n- Pan corners are clipped, then two adjacent edges are folded over and two folded under to form locks of about 3/4 in (19 mm).\n- Pans lock together in both directions. Seams running down the slope are continuous; cross seams are staggered.\n- Each pan is held by concealed cleats, 16 or 20 oz copper in copper roofs, engaged in the locks.\n- Pans are arranged so water always flows from one pan onto the pan below.\n\n## Soldering and sealing\n\n- On slopes of 3 in 12 or less, every seam is soldered. Edges are cleaned, fluxed and pre-tinned about 1.5 in (38 mm) wide before folding; after locking, seams are malleted down and sweated full of solder.\n- From about 3 in 12 to 6 in 12, seams may be sealed with concealed sealant or butyl tape instead.\n- Above 6 in 12, seams may be left dry.\n\n## Expansion\n\nLarge soldered flat seam roofs cannot move freely, so expansion battens or joints are placed at intervals of about 25 to 30 ft (7.6 to 9 m) in both directions.\n\n## Notes\n\nFlux residues must be neutralised and rinsed after soldering. Only as many pans should be laid each day as can be soldered that day.","key_facts":[{"label":"Typical copper pan","value":"18 x 24 in (460 x 610 mm), 20 oz"},{"label":"Lock width","value":"About 3/4 in (19 mm)"},{"label":"Soldered seams required","value":"Slopes 3:12 or less"},{"label":"Expansion joints","value":"About every 25-30 ft (7.6-9 m)"}],"regions":["Global"],"aliases":["flat-lock roofing","flat seam","flat lock seam","flat-seam copper"],"related":["copper-roofing","terne-plate","tin-roof","soldering-sheet-metal-roofing","batten-seam-roofing"],"company":null,"sources":[{"title":"8.5. Flat Seam Roofing","url":"https://www.copper.org/applications/architecture/arch_dhb/arch-details/roofing/flat_seam_roofing.php","publisher":"Copper Development Association"},{"title":"14.3. Copper Roofing (architectural specifications)","url":"https://archive.copper.org/applications/architecture/arch_dhb/specifications/arch_specs/sheet_roofing.php","publisher":"Copper Development Association"},{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"}],"country":null},{"slug":"fletcher-building","title":"Fletcher Building","category":"manufacturers","type":"company","summary":"Fletcher Building is an Auckland-based building-materials group formed in 2001, which owns the Australian steel roofing maker Stramit.","body":"Fletcher Building Limited is a New Zealand building-materials, distribution and construction group headquartered in Auckland. It was created in 2001 when it was split out of the conglomerate Fletcher Challenge, though the Fletcher business traces its building-supply history to 1910, when its first site opened in Dunedin. Fletcher Building operates in New Zealand and Australia, and its retail brand PlaceMakers dates from 1954.\n\n## Roofing interests\n\n- **Stramit**: an Australian roll-former of steel roofing, walling, rainwater and structural products, acquired in 2005 and described as a member of the Fletcher Building Group.\n- **Stone-coated steel**: the DECRA stone-coated steel roofing business, which originated in New Zealand, was owned by Fletcher Building for a period; a 2007 report described DECRA's North American operations as Fletcher-owned. DECRA products are now marketed under a different brand arrangement.\n\n## Corporate events\n\nThe group's recent history includes several high-profile issues in New Zealand. A fire broke out on 22 October 2019 at the New Zealand International Convention Centre, which Fletcher was building, and in June 2025 the casino operator SkyCity sued Fletcher Building and Fletcher Construction for NZD 330 million over the project. In 2021 the Commerce Commission opened an investigation into whether Fletcher's plasterboard business was blocking competitors, and in 2022 supply shortages led Fletcher to ration plasterboard orders. Andrew Reding became chief executive in August 2024.\n\n## Context\n\nFletcher Building's distribution businesses, such as PlaceMakers, sell roofing materials alongside other building supplies in New Zealand, while Stramit supplies steel roofing in Australia. The group is listed in New Zealand.","key_facts":[{"label":"Formed","value":"2001 (split from Fletcher Challenge)"},{"label":"Headquarters","value":"Auckland, New Zealand"},{"label":"Roofing business","value":"Stramit (Australia, since 2005)"}],"regions":["Oceania"],"aliases":["Fletcher Building Limited"],"related":["stramit","decra-roofing-systems","stone-coated-steel","bluescope"],"company":{"founded":"2001","headquarters":"Auckland, New Zealand","website":"https://www.fletcherbuilding.com","known_for":["Building materials","PlaceMakers distribution","Stramit steel roofing"]},"sources":[{"title":"Fletcher Building","url":"https://en.wikipedia.org/wiki/Fletcher_Building","publisher":"Wikipedia"},{"title":"Our history","url":"https://www.stramit.com.au/about-us/our-history","publisher":"Stramit"},{"title":"DECRA celebrates 50 years of strength","url":"https://www.roofingcontractor.com/articles/85479-decra-celebrates-50-years-of-strength","publisher":"Roofing Contractor"}],"country":null},{"slug":"fll","title":"FLL (Landscape Research, Development and Construction Society)","summary":"FLL is a German research society, founded in 1975 and based in Bonn, whose green roof guidelines are a widely used technical reference.","body":"The Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau e.V. (FLL), in English the Landscape Research, Development and Construction Society, is a German non-profit association founded in 1975. It is based in Bonn and produces technical guidelines for landscaping and building greening. Its website is fll.de.\n\n## Role\n\nFLL brings together experts from industry, research, public authorities and professional bodies in committees that write guidelines (Regelwerke) on topics such as landscape construction, tree care, playgrounds, sports grounds and the greening of buildings. A committee on building greening (Bauwerksbegrünung) handles green roofs and green facades.\n\n## Green roof guidelines\n\nFLL's guidelines for the planning, construction and maintenance of green roofs (Dachbegrünungsrichtlinie) have become one of the most widely cited green roof references in the world. They have been revised several times and translated into English. Topics include:\n\n- types of green roof (extensive, simple intensive and intensive) and suitable plants;\n- requirements for growing media, such as particle size, water retention, organic content and weight;\n- drainage and filter layers;\n- protection against root penetration, including a test method used to certify root-resistant membranes and root barriers;\n- roof slope, wind uplift and fire precautions;\n- care and maintenance during establishment and in later years.\n\nWaterproofing membranes sold in Europe and beyond are often described as root resistant according to the FLL test.\n\n## Influence\n\nBecause Germany was an early adopter of modern green roofs, many other countries, including in North America and Asia, based their first green roof guidance on FLL documents. They are used alongside national roofing rules, such as those of the German roofing trade, and standards such as EN 13948 for root penetration.\n\n## Related bodies\n\nThe European Federation of Green Roof and Green Wall Associations (EFB) and North America's Green Roofs for Healthy Cities draw on FLL guidance in their training and publications.","key_facts":[{"label":"Founded","value":"1975"},{"label":"Headquarters","value":"Bonn, Germany"},{"label":"Known for","value":"Green roof guidelines (Dachbegrünungsrichtlinie)"},{"label":"Type","value":"Non-profit research society (e.V.)"}],"regions":["Europe","Global"],"aliases":["FLL","Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau","FLL Guidelines"],"related":["green-roof","european-federation-of-green-roof-associations","zvdh"],"company":{"founded":"1975","headquarters":"Bonn, Germany","website":"https://www.fll.de","known_for":["FLL green roof guidelines","Root resistance test method"]},"sources":[{"title":"FLL home page","url":"https://www.fll.de/","publisher":"FLL"},{"title":"About us","url":"https://efb-greenroof.eu/about-us/","publisher":"EFB"}],"category":"organizations","type":"organization","country":null},{"slug":"florence-cathedral-dome","title":"Florence Cathedral Dome","category":"history","type":"place","summary":"Brunelleschi's brick double-shell dome over Florence Cathedral, built 1420-1436 and the first octagonal dome raised without temporary timber centring.","body":"The dome of **Florence Cathedral** (Santa Maria del Fiore) is one of the great engineering achievements of the Renaissance. Designed by **Filippo Brunelleschi** and built between **1420 and 1436**, it covers the octagonal crossing of the cathedral and dominates the city's skyline.\n\n## The problem\n\nThe cathedral's octagonal crossing was very wide, and the dome followed a design drafted by Neri di Fioravanti some fifty years earlier, but no one knew how to build it. Conventional practice would have needed a huge timber framework (centring) to support the masonry until it was complete.\n\n## The competition\n\nOn **19 August 1418** the wool merchants' guild (Arte della Lana) announced a design competition. Brunelleschi won over his rival Lorenzo Ghiberti and received the commission.\n\n## Construction\n\n- Work began in **1420** and the dome was finished in **1436**. Pope Eugene IV consecrated the cathedral on 25 March 1436.\n- The dome was the first octagonal dome built **without temporary wooden supporting centring**.\n- It has an **inner shell** and a thinner **outer shell**, both of brick, linked by ribs. Brick was chosen because it is lighter than stone.\n- Brunelleschi laid bricks in a **herringbone pattern** so that freshly laid courses transferred their weight to the nearest ribs and did not slide inwards.\n- More than 4 million bricks were used, and about 37,000 tons of material were lifted. A 1983 analysis estimated the dome's weight at about 25,000 tons.\n- Brunelleschi designed new hoisting machines to raise the materials.\n\n## Size\n\nSources give the internal span as about 42-44 m (138-144 ft), comparable to the Pantheon. With its lantern, the dome stands about 114.5 m (376 ft) high.\n\n## The lantern\n\nBrunelleschi designed the lantern on top, and construction began a few months before his death in 1446. Michelozzo completed it in **1461**, and Andrea del Verrocchio added the gilt copper ball in 1469.\n\n## Legacy\n\nThe dome remains the defining landmark of Florence and a standard case study in the history of structural engineering, showing how a very large masonry vault could be raised without full-height timber support.","key_facts":[{"label":"Competition","value":"Announced 19 August 1418"},{"label":"Built","value":"1420-1436"},{"label":"Bricks","value":"Over 4 million"},{"label":"Height with lantern","value":"About 114.5 m (376 ft)"},{"label":"Lantern completed","value":"1461"}],"regions":["Europe"],"aliases":["Brunelleschi's dome","Duomo of Florence dome","Santa Maria del Fiore dome"],"related":["filippo-brunelleschi","pantheon-dome","st-pauls-cathedral-dome","dome"],"company":null,"sources":[{"title":"Florence Cathedral","url":"https://en.wikipedia.org/wiki/Florence_Cathedral","publisher":"Wikipedia"},{"title":"Filippo Brunelleschi","url":"https://en.wikipedia.org/wiki/Filippo_Brunelleschi","publisher":"Wikipedia"}],"country":null},{"slug":"florida-building-code","title":"Florida Building Code","category":"standards-codes","type":"standard","summary":"Florida's statewide building code, in force since 2002 after Hurricane Andrew, with strict wind, roofing and product-approval rules.","body":"The Florida Building Code (FBC) is the statewide building code of Florida, United States. It is developed by the Florida Building Commission and based on the International Building Code family, with Florida-specific additions for hurricanes and high winds. The FBC is often described as the strictest building code in the United States for wind resistance.\n\n## Origins\n\nBefore Hurricane Andrew in 1992, Florida had more than 400 separate county and municipal building codes and no unified wind standard. Andrew destroyed about 63,500 homes. The 1994 South Florida Building Code created the High-Velocity Hurricane Zone (HVHZ), and a 1998 state law created the unified FBC. Its first edition took effect on 1 March 2002, including the HVHZ provisions and Florida's Roofing Application Standards (RAS) and Testing Application Standards (TAS).\n\n## Editions\n\nThe code is revised in cycles, often following hurricane experience:\n\n- **2007 edition and 2009 supplements:** after the 2004 and 2005 hurricane seasons, added roof replacement rules, including mandatory re-nailing of roof decks and potential evaluation and correction of roof-to-wall connections.\n- **2010:** significant changes to wind load design and wind speed maps.\n- **5th edition (2014):** changed underlayment rules, eliminated No. 15 asphalt felt and introduced self-adhering underlayment applied directly to the deck.\n- **6th edition (2017):** consolidated steep-slope underlayment provisions.\n- **7th edition (2020):** adopted ASCE 7-16 wind loads, added sealed-deck underlayment requirements to improve secondary water resistance, and extended roof deck attachment and roof-to-wall connection provisions to all applicable wood-deck structures.\n- **8th edition (2023):** in effect from 31 December 2023.\n- **9th edition (2026):** scheduled, as of November 2026, to take effect on 31 December 2026.\n\n## High-Velocity Hurricane Zone\n\nMiami-Dade and Broward counties form the HVHZ, with stricter design and testing requirements. Design wind speeds by risk category are:\n\n- **Miami-Dade:** 165, 175 and 185 mph (265, 282 and 298 km/h) for categories I, II and III;\n- **Broward:** 156, 170 and 180 mph (251, 274 and 290 km/h).\n\nImpact testing of building materials is carried out under TAS 201, 202 and 203.\n\n## Product approval\n\nRoofing products and other building envelope components sold for use in Florida must be approved, either through the state's Florida Product Approval system or, for the HVHZ, through Miami-Dade County's own approval process. Both maintain searchable databases of test results, drawings and installation instructions.\n\n## Existing buildings\n\nAbout 4.7 million Florida homes predate the 2002 code. Renovations, additions and other permitted work, including many reroofing projects, must comply with the current edition. A review after Hurricane Milton in 2024 reported that no homes built after the unified code was adopted in 2002 were destroyed.","key_facts":[{"label":"Jurisdiction","value":"State of Florida, USA"},{"label":"First effective","value":"1 March 2002"},{"label":"Developed by","value":"Florida Building Commission"},{"label":"Editions (as of November 2026)","value":"8th (2023) in force; 9th (2026) scheduled from 31 December 2026"},{"label":"HVHZ","value":"Miami-Dade and Broward counties"},{"label":"Impact tests","value":"TAS 201, 202, 203"}],"regions":["North America"],"aliases":["FBC","Florida code","HVHZ code"],"related":["florida-product-approval","miami-dade-noa","international-building-code","florida-roofing-and-sheet-metal-contractors-association"],"company":null,"sources":[{"title":"Florida Building Code","url":"https://en.wikipedia.org/wiki/Florida_Building_Code","publisher":"Wikipedia"},{"title":"Impact of Recent Hurricanes on Florida Building Codes - May 2022","url":"https://floridaroof.com/Impact-of-Recent-Hurricanes-on-Florida-Building-Codes---May-2022-1-13450.html","publisher":"Florida Roofing and Sheet Metal Contractors Association"}],"country":null},{"slug":"florida-construction-industry-licensing-board","title":"Florida Construction Industry Licensing Board (CILB)","summary":"The CILB licenses and regulates construction contractors in Florida, including certified (state-wide) and registered (local) roofing contractors.","body":"The Construction Industry Licensing Board (CILB) is the Florida state board responsible for licensing and regulating the construction industry, including roofing contractors. It works within the Florida Department of Business and Professional Regulation (DBPR), and licensing is governed by Chapter 489 of the Florida Statutes. Information is available on myfloridalicense.com.\n\n## What the board does\n\nThe CILB meets regularly to consider licence applications, review disciplinary cases and hold informal hearings. It also writes rules to carry out the licensing statutes.\n\n## Roofing contractor licences\n\nFlorida has two main kinds of roofing contractor licence:\n\n- **Certified roofing contractor.** Holds a certificate of competency from the state and may contract anywhere in Florida without meeting each local jurisdiction's competency requirements.\n- **Registered roofing contractor.** Has registered with the state after meeting the competency requirements of a particular local jurisdiction, and may contract only in those jurisdictions.\n\nThe roofing licence covers roofing work generally, including skylights, required roof-deck attachment, and repair or replacement of wood roof sheathing or fascia as part of roof work. Roof-to-wall connection improvements are covered only when done together with roof covering repair or replacement.\n\nGeneral, building and residential contractors also have defined scopes, and in many cases roofing work must be performed by a licensed roofing contractor.\n\n## Checking a licence\n\nConsumers can look up a contractor's licence status through the DBPR online licence search. The department also provides a database showing contractors' workers' compensation coverage status. Checking a licence before signing a contract is especially important after hurricanes, when unlicensed operators may solicit work.\n\n## Florida context\n\nFlorida's roofing is governed by the Florida Building Code, which includes strict wind provisions and a product approval system, with extra requirements in the High-Velocity Hurricane Zone of Miami-Dade and Broward counties. The Florida Roofing and Sheet Metal Contractors Association (FRSA) is the main trade association, separate from the licensing board.","key_facts":[{"label":"Jurisdiction","value":"Florida, USA"},{"label":"Parent","value":"Department of Business and Professional Regulation"},{"label":"Law","value":"Chapter 489, Florida Statutes"},{"label":"Roofing licences","value":"Certified (state-wide) and registered (local)"}],"regions":["North America"],"aliases":["CILB","Florida CILB","Florida Construction Industry Licensing Board"],"related":["florida-roofing-and-sheet-metal-contractors-association","how-to-find-a-licensed-roofer","florida-building-code","miami-dade-noa"],"company":{"website":"https://www2.myfloridalicense.com/construction-industry/","parent":"Florida Department of Business and Professional Regulation","known_for":["Florida contractor licensing"]},"sources":[{"title":"Construction Industry Licensing Board","url":"https://www2.myfloridalicense.com/construction-industry/","publisher":"Florida DBPR"},{"title":"About FRSA","url":"https://floridaroof.com/about-us/index","publisher":"FRSA"}],"category":"organizations","type":"organization","country":null},{"slug":"florida-product-approval","title":"Florida Product Approval","summary":"Florida Product Approval is the state system, under Statute 553.842 and Rule 61G20-3, for approving roofing and other envelope products.","body":"Florida Product Approval is the system the State of Florida uses to confirm that building products comply with the Florida Building Code. It is set out in Florida Statute 553.842 and administered under Florida Administrative Code Rule 61G20-3 by the Florida Building Commission. Approvals are published in an online database on floridabuilding.org, where each approved product receives an \"FL\" number (for example FL40569).\n\n## Which products are covered\n\nThe rule applies to products and systems that form the building envelope and structural frame. Statewide approval covers several categories for habitable structures, including roofing products, panel walls, exterior doors, windows, skylights, shutters, structural components and impact protective systems.\n\n## Statewide or local approval\n\nManufacturers can choose between two routes:\n\n- **Statewide approval** – one approval accepted by building departments across Florida.\n- **Local approval** – approval by the local building official for a specific jurisdiction or project.\n\nIn the High-Velocity Hurricane Zone (Miami-Dade and Broward counties), products must be approved specifically for HVHZ use, often through a [Miami-Dade NOA](/miami-dade-noa).\n\n## Methods of compliance\n\nRule 61G20-3 describes several ways to show compliance:\n\n- **Method 1** – for products with standard tests in the code. Evidence can be a certification mark or listing from an approved certification agency, a test report from an approved laboratory, an evaluation report from an approved evaluation entity or a Florida-licensed engineer or architect, or a legacy report from a national model code organization.\n- **Method 2** – for products without a standard test method, using an evaluation report that shows the product meets the intent of the code.\n\nRational engineering analysis cannot be used in place of a test that the code requires, except where a local official approves an alternative for a specific project.\n\n## Roofing in practice\n\nFor a roof covering, the approval document usually lists the deck types, underlayment, fastener type and spacing, and design pressures for which the product is approved. Many Florida counties ask permit applicants to fill in a roofing product approval form listing the FL number for each component (covering, underlayment, flashing, vents). Inspectors compare the installed system with the approval.","key_facts":[{"label":"Legal basis","value":"Florida Statute 553.842; Rule 61G20-3, F.A.C."},{"label":"Administered by","value":"Florida Building Commission"},{"label":"Identifier","value":"FL number"},{"label":"Routes","value":"Statewide or local approval"}],"regions":["North America"],"aliases":["FL approval","Florida product approval number","FL number","Rule 61G20-3"],"related":["miami-dade-noa","tas-100","florida-building-code","icc-es-evaluation-reports"],"sources":[{"title":"Product Approval Regulation in Florida","url":"https://www.engineeringplans.com/?p=1806","publisher":"EngineeringPlans.com"},{"title":"Florida Administrative Code 61G20-3.002","url":"https://regulations.justia.com/states/florida/61/61g20/chapter-61g20-3/section-61g20-3-002","publisher":"Justia"},{"title":"Roofing Florida Product Approval Form","url":"https://growth-management.alachuacounty.us/formsdocs/BLD_Roofing_Florida_Product_Approval_Form_060125.pdf","publisher":"Alachua County"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"florida-roofing-and-sheet-metal-contractors-association","title":"Florida Roofing and Sheet Metal Contractors Association (FRSA)","summary":"FRSA is Florida's statewide roofing contractors' association, founded in 1922 and based in Orlando.","body":"The Florida Roofing and Sheet Metal Contractors Association (FRSA) is a statewide trade association for roofing, sheet metal and air-conditioning contractors in Florida, United States. It was founded in 1922 and marked its centennial in 2022. Its headquarters is in Orlando, and its website is floridaroof.com.\n\nFRSA represents more than 1,000 member companies, including contractors as well as manufacturers, distributors and other businesses connected to roofing. It works through statewide affiliate councils that cover different parts of Florida.\n\n## Activities\n\n- **Education.** The FRSA Educational and Research Foundation, founded in 1982, is a non-profit that trains workers, managers and owners in the construction trades. The association runs a training centre for courses and exam preparation.\n- **Technical manuals.** FRSA has worked with the Tile Roofing Industry Alliance on the Florida High Wind Concrete and Clay Tile Installation Manual, which sets out tile installation methods for Florida's wind conditions.\n- **Convention and expo.** The association holds an annual convention and trade show.\n- **Publications.** It publishes *Florida Roofing* magazine.\n- **Insurance.** A self-insurers fund for workers' compensation was started in 1955; it now operates as BrightFund.\n\n## Florida context\n\nFlorida has some of the most demanding roofing requirements in North America because of hurricanes. The Florida Building Code includes strict wind-resistance and product-approval rules, with even stricter provisions in Miami-Dade and Broward counties (the High-Velocity Hurricane Zone). Roofing contractors in Florida must be licensed by the state through the Construction Industry Licensing Board. FRSA membership is voluntary and separate from licensing, but the association offers a member search to help consumers find licensed contractors.","key_facts":[{"label":"Founded","value":"1922"},{"label":"Headquarters","value":"Orlando, Florida, USA"},{"label":"Members","value":"Over 1,000 companies"},{"label":"Education foundation","value":"Founded 1982"}],"regions":["North America"],"aliases":["FRSA","Florida Roofing, Sheet Metal and Air Conditioning Contractors Association"],"related":["florida-construction-industry-licensing-board","tile-roofing-industry-alliance","nrca","florida-building-code"],"company":{"founded":"1922","headquarters":"Orlando, Florida, USA","website":"https://www.floridaroof.com","known_for":["Florida roofing education","Florida High Wind tile manual (with TRI Alliance)","Florida Roofing magazine"]},"sources":[{"title":"About FRSA","url":"https://floridaroof.com/about-us/index","publisher":"FRSA"},{"title":"Membership Information","url":"https://floridaroof.com/Membership-Information-6-33.html","publisher":"FRSA"},{"title":"Florida High Wind Tile Installation Manual, 6th Edition","url":"https://floridabuilding.org/upload/PR_Instl_Docs/FL24172_R1_II_Florida-High-Wind-Tile-Installation-Manual-6th-Edition-092020.pdf","publisher":"Florida Building Commission"},{"title":"Celebrating 100 years of Florida roofing excellence","url":"https://www.rooferscoffeeshop.com/post/celebrating-100-years-of-florida-roofing-excellence","publisher":"RoofersCoffeeShop"}],"category":"organizations","type":"organization","country":null},{"slug":"fm-global","title":"FM (FM Global)","summary":"FM, formerly FM Global, is a U.S.-based mutual commercial property insurer whose research, FM Approvals and data sheets strongly influence low-slope roof design.","body":"FM, long known as FM Global, is a mutual insurance company that specialises in commercial and industrial property insurance and loss prevention engineering. Its oldest predecessor, the Manufacturers Mutual Fire Insurance Company, was formed in 1835 after a textile mill owner, Zachariah Allen, sought lower premiums for a mill he had protected against fire. The company is headquartered in Johnston, Rhode Island, United States, and its website is fm.com.\n\nFM is included in an encyclopedia of roofing because of its large role in research, testing and standards for commercial roofs.\n\n## Research campus\n\nFM operates a research campus of about 1,600 acres (648 hectares) in West Glocester, Rhode Island. Testing there covers fire and explosion hazards and how building components perform in conditions such as hurricane winds.\n\n## FM Approvals\n\nFM Approvals is the company's testing and certification unit. It tests loss-prevention products and services and certifies those that meet recognised standards; it reports having tested more than 50,000 products. For roofing, FM Approvals certifies roof assemblies, membranes, insulation, fasteners and roof edge systems for properties such as:\n\n- **wind uplift resistance**, expressed in classes based on the pressure an assembly withstood in testing;\n- **fire performance**, both from above the roof (ASTM E108) and from below through the roof deck;\n- **hail damage resistance**;\n- **water leakage, foot traffic, corrosion and heat-damage resistance**.\n\nFor membrane roofs these tests are set out in FM Approvals Class Number 4470, which covers single-ply, polymer-modified bitumen, built-up and liquid-applied roof assemblies.\n\nApproved roof assemblies are listed in an online directory used by designers, contractors and insurers.\n\n## Property Loss Prevention Data Sheets\n\nFM publishes engineering guidance in Property Loss Prevention Data Sheets. Several deal with roofs, covering topics such as wind design of roof systems, roof deck securement, roof loads and drainage, and hail. Insurance policies written by FM may require buildings to follow these data sheets, which can be stricter than local building codes.\n\n## Wider influence\n\nFM worked with SPRI on edge securement standards, and its approval tests are referenced by many manufacturers worldwide. Owners insured by other companies may still specify FM-approved assemblies as a quality benchmark.","key_facts":[{"label":"Origins","value":"1835 (Manufacturers Mutual Fire Insurance Company)"},{"label":"Headquarters","value":"Johnston, Rhode Island, USA"},{"label":"Research campus","value":"About 1,600 acres (648 ha), West Glocester, Rhode Island"},{"label":"Testing arm","value":"FM Approvals"}],"regions":["North America","Global"],"aliases":["FM Global","Factory Mutual","FM Approvals"],"related":["ibhs","spri","wind-uplift","roof-deck"],"company":{"founded":"1835","headquarters":"Johnston, Rhode Island, USA","website":"https://www.fm.com","known_for":["FM Approvals roof assembly testing","Property Loss Prevention Data Sheets"]},"sources":[{"title":"FM Global","url":"https://en.wikipedia.org/wiki/FM_Global","publisher":"Wikipedia"},{"title":"FM home page","url":"https://www.fm.com/","publisher":"FM"},{"title":"Approval Standard Class Number 4470 (April 2022)","url":"https://www.fmapprovals.com/-/media/Feature/Approval-Standards/4470-pdf.pdf","publisher":"FM Approvals"}],"category":"organizations","type":"organization","country":null},{"slug":"fm-4470","title":"FM 4470","summary":"FM 4470 is the FM Approvals standard for membrane and liquid-applied roof assemblies, covering fire, wind uplift, hail, leakage and other hazards.","body":"FM 4470 is an approval standard published by FM Approvals, the product certification arm of the commercial property insurer FM. Its full title describes single-ply, polymer-modified bitumen sheet, built-up roof (BUR) and liquid-applied roof assemblies for use in Class 1 and noncombustible roof deck construction. The current edition listed by standards databases is dated April 2022.\n\nProducts that meet it can be described as [FM Approved](/fm-approved) and are listed in FM's RoofNav database.\n\n## What it evaluates\n\nFM 4470 looks at the whole roof assembly, from the structural deck and its attachment up to the weather surface, rather than at one product in isolation. Hazards it addresses include:\n\n- fire from above the deck (external fire) and from below (interior fire spread)\n- simulated wind uplift, using methods aligned with [ANSI/FM 4474](/fm-4474)\n- susceptibility to hail damage\n- water leakage\n- foot traffic\n- corrosion of metal components\n- susceptibility to heat damage\n\nOptional evaluations include puncture resistance, solar reflectance and a noncombustible-core rating for insulation.\n\n## Ratings\n\nAn FM-approved assembly carries a designation such as **Class 1-90**. \"Class 1\" indicates it met FM's fire requirements for interior fire spread and external fire, and the number is the wind uplift rating in psf (here 90 psf, about 4.3 kPa). Hail performance is shown as Moderate Hail (MH) or Severe Hail (SH) where tested.\n\n## Who uses it\n\nFM-insured commercial and industrial buildings are often required to use FM-approved roof assemblies installed according to FM Property Loss Prevention Data Sheets. Outside FM's own clients, many specifiers worldwide use FM 4470 approvals as a benchmark for commercial low-slope roofs, and FM test data is accepted in some building code compliance routes in the United States.\n\n## Related FM standards\n\nFM Approvals publishes other roofing standards, including [4473](/fm-4473) for impact resistance of rigid roofing and 4475 for roof components used in hail-prone areas.","key_facts":[{"label":"Publisher","value":"FM Approvals"},{"label":"Current edition","value":"April 2022"},{"label":"Applies to","value":"Single-ply, mod bit, BUR and liquid-applied roof assemblies"},{"label":"Example rating","value":"Class 1-90 (fire Class 1, 90 psf uplift)"},{"label":"Database","value":"RoofNav"}],"regions":["North America","Global"],"aliases":["FM Approval Standard 4470","Class 1-90","FM Class 1 roof"],"related":["fm-approved","fm-4474","fm-4473","single-ply-roofing","built-up-roofing"],"sources":[{"title":"FM 4470 Single-Ply, Polymer-Modified Bitumen Sheet, BUR and Liquid Applied Roof Assemblies","url":"https://standards.globalspec.com/std/14567203/4470","publisher":"GlobalSpec"},{"title":"Approval Standard 4470 (PDF)","url":"https://www.fmapprovals.com/-/media/Feature/Approval-Standards/4470-pdf.pdf","publisher":"FM Approvals"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"fm-approved","title":"FM Approved","type":"term","summary":"FM Approved is a certification mark from FM Approvals showing a product or roof assembly has passed FM's loss-prevention testing and factory audits.","body":"**FM Approved** is a certification mark issued by **FM Approvals**, the testing and certification arm of FM (formerly FM Global), a mutual commercial property insurer based in Johnston, Rhode Island. FM traces its origins to 1835, when New England mill owners led by Zachariah Allen formed a mutual fire insurance company built on loss prevention. FM operates a large research campus in West Glocester, Rhode Island, where it tests fire, explosion and natural hazard performance, including how building components behave in hurricane conditions.\n\nIn roofing, FM Approved status is one of the most widely recognised benchmarks for commercial low-slope roofs, both in North America and internationally.\n\n## What approval means\n\nA product or assembly earns FM approval by:\n\n- passing tests to a published FM Approvals standard\n- undergoing audits of the manufacturing facility, with follow-up audits to confirm that production continues to match the tested product\n\nApproved products and assemblies are listed in FM's online directories. For roofs, the **RoofNav** tool lists approved roof assemblies and components.\n\n## Roofing standards\n\nKey FM Approvals roofing standards include:\n\n- **[FM 4470](/fm-4470)** – single-ply, modified bitumen, built-up and liquid-applied roof assemblies, evaluating fire, wind uplift, hail, leakage, foot traffic and corrosion\n- **[ANSI/FM 4474](/fm-4474)** – simulated wind uplift testing\n- **[ANSI/FM 4473](/fm-4473)** – impact resistance of rigid roofing using ice balls\n- **4475** – roof components for hail-prone areas\n\n## Ratings\n\nApproved roof assemblies typically carry a designation such as **Class 1-90**. \"Class 1\" refers to meeting FM's fire criteria (including interior fire spread and external fire), and the number is the wind uplift rating in pounds per square foot (90 psf is about 4.3 kPa). Hail ratings may be shown as moderate or severe hail.\n\n## Who uses it\n\n- **FM-insured properties** are generally required to use FM Approved roof systems installed according to FM loss-prevention data sheets.\n- **Specifiers and owners** outside FM's client base often use FM approval as a quality benchmark.\n- **Code officials** in the US may accept FM test data as evidence of compliance, since codes reference FM 4474 among wind uplift test methods.\n\n## Limits\n\nFM approval applies only to the exact assembly listed: deck, insulation, fasteners, adhesives and membrane. Substituting components can void the approval. Approval also reflects FM's loss-prevention priorities, which can be stricter than local building code minimums in some respects and different in others.","key_facts":[{"label":"Issued by","value":"FM Approvals (part of FM, formerly FM Global)"},{"label":"Parent HQ","value":"Johnston, Rhode Island, USA"},{"label":"Parent origins","value":"1835"},{"label":"Roof database","value":"RoofNav"},{"label":"Typical rating","value":"Class 1-60, 1-90 and higher"}],"regions":["Global","North America"],"aliases":["FM Approval","FM Global approved","FM Approvals","Factory Mutual approved"],"related":["fm-4470","fm-4474","fm-4473","single-ply-roofing"],"sources":[{"title":"FM Global","url":"https://en.wikipedia.org/wiki/FM_Global","publisher":"Wikipedia"},{"title":"FM 4470","url":"https://standards.globalspec.com/std/14567203/4470","publisher":"GlobalSpec"},{"title":"Approval Standard 4473 (ANSI) PDF","url":"https://www.fmapprovals.com/-/media/Feature/Approval-Standards/4473ansi-pdf.pdf","publisher":"FM Approvals"}],"category":"standards-codes","company":null,"country":null},{"slug":"foguang-temple-east-hall","title":"Foguang Temple East Hall","category":"history","type":"place","summary":"The East Hall of Foguang Temple, Shanxi, completed in 857, is one of China's oldest timber halls, with a hipped tiled roof on Tang bracket sets.","body":"The East Great Hall (*Dongda Dian*) of Foguang Temple, on Mount Wutai in Shanxi province, China, is one of the oldest surviving timber buildings in China and one of the best-preserved examples of a Tang-dynasty roof. It was completed in **857**, after an earlier temple on the site was destroyed during the anti-Buddhist persecution of 845.\n\n## The building and its roof\n\nThe hall is a single-storey building of seven bays by four, measuring 34 by 17.7 m (110 by 58 ft). It is covered by a **hipped roof**, sloping on all four sides, a form that signalled the high importance of the building in the Tang period.\n\nThe roof rests on large, complex bracket sets (*dougong*). Each column top carries a bracket set built from seven different types of bracket, and the sets are very tall in relation to the columns. Crescent-shaped crossbeams join the bracket sets into an inner and an outer ring, and a lattice ceiling hides much of the roof framing from below.\n\n## Rank\n\nMeasured against the Song building manual *Yingzao Fashi* (1103), with its eight-rank system of timber sizes, the hall corresponds closely to a seventh-rank building. No other surviving building of the period is known to be of such high rank, which makes it a key reference for how large Tang halls and their roofs were built.\n\n## Rediscovery\n\nIn late June 1937 a survey team led by the architectural historians **Liang Sicheng** and **Lin Huiyin** reached the hall while searching for Tang buildings. The ridge purlin carried no construction date, but on 5 July 1937 the team found ink writing on the underside of a large beam naming the donor, Ning Gongyu. Lin Huiyin then found the same name and the date 857 on a stone dharani pillar in the courtyard, confirming the hall's age.\n\n## Heritage status\n\nFoguang Temple was inscribed on the UNESCO World Heritage List on 26 June 2009 as part of the Mount Wutai site. The only older dated timber hall in China is the smaller Great Buddha Hall of nearby Nanchan Temple (782), which has a hip-and-gable roof.","key_facts":[{"label":"Completed","value":"857, Tang dynasty"},{"label":"Size","value":"7 x 4 bays, 34 x 17.7 m (110 x 58 ft)"},{"label":"Roof","value":"Hipped, on dougong bracket sets"},{"label":"Rediscovered","value":"1937, Liang Sicheng and Lin Huiyin"},{"label":"UNESCO","value":"Mount Wutai, 2009"}],"regions":["East Asia"],"aliases":["Foguang Temple","East Great Hall of Foguang Temple","Dongda Dian"],"related":["dougong","yingzao-fashi","roofing-in-china","hip-roof","history-of-timber-roof-framing","forbidden-city-roofs"],"company":null,"sources":[{"title":"Foguang Temple","url":"https://en.wikipedia.org/wiki/Foguang_Temple","publisher":"Wikipedia"},{"title":"Nanchan Temple","url":"https://en.wikipedia.org/wiki/Nanchan_Temple","publisher":"Wikipedia"},{"title":"Yingzao Fashi","url":"https://en.wikipedia.org/wiki/Yingzao_Fashi","publisher":"Wikipedia"}],"country":null},{"slug":"fortified-roof","title":"FORTIFIED Roof","type":"standard","summary":"A voluntary US construction standard from IBHS that upgrades roof edges, deck sealing and attachment to reduce hurricane and high-wind damage.","body":"FORTIFIED Roof is the entry level of the FORTIFIED Home program run by the Insurance Institute for Business & Home Safety (IBHS), an insurance-funded research organization in the United States. FORTIFIED describes itself as a national standard for resilience. It sets out construction steps that go beyond typical building code minimums and requires third-party verification before a home receives a designation.\n\n## Requirements\n\nThe FORTIFIED Roof level focuses on the roof system:\n\n- **Stronger edges.** A wider drip edge and a fully adhered starter strip installed together.\n- **Sealed roof deck.** All deck seams are sealed so water cannot pass if the covering is torn away. IBHS testing indicates this can reduce water intrusion by up to 95 percent.\n- **Better deck attachment.** 8d ring-shank nails replace smooth-shank nails, installed in a closer pattern; IBHS testing indicates this can double uplift resistance.\n- **Wind-rated coverings.** Asphalt shingles must meet ASTM D3161 Class F or ASTM D7158 Class H. Metal, tile and low-slope systems must be rated for site-specific design pressures.\n- **Optional hail supplement.** Adds impact requirements, such as UL 2218 Class 4 for metal and low-slope coverings and FM 4473 Class 4 for tile.\n\n## Higher levels\n\nFORTIFIED Silver and Gold add requirements beyond the roof, such as protection of openings in hurricane-prone areas, gable end bracing, chimney bracing, anchored attached structures, and engineered connections from roof to wall and down to the foundation.\n\n## Versions and uptake\n\nFORTIFIED technical standards are periodically revised; a 2025 residential edition took effect on November 1, 2025. The program reports that more than 100,000 homes have received FORTIFIED designations.\n\n## Insurance and grants\n\nIn Alabama, homes with a FORTIFIED designation receive a discount on the wind portion of the homeowner's premium from admitted insurers, and the Strengthen Alabama Homes program has offered grants covering mitigation costs up to $10,000 for homes that reach the FORTIFIED Roof standard. Other states have adopted similar grant or discount programs, though terms vary.\n\n## Scope\n\nFORTIFIED is a US program. Comparable principles (continuous load path, sealed deck, rated coverings) appear in cyclone-region codes elsewhere, such as Australia, but the designation itself is specific to the United States.","key_facts":[{"label":"Developer","value":"Insurance Institute for Business & Home Safety (IBHS)"},{"label":"Levels","value":"Roof, Silver, Gold"},{"label":"Shingle wind rating required","value":"ASTM D3161 Class F or ASTM D7158 Class H"},{"label":"Designated homes","value":"More than 100,000 (program figure)"},{"label":"Latest edition noted","value":"2025 Residential, effective Nov 1, 2025"}],"regions":["North America"],"aliases":["FORTIFIED Home","IBHS FORTIFIED","FORTIFIED Roof standard"],"related":["sealed-roof-deck","secondary-water-barrier","roof-insurance-discounts","hurricane-roof-damage","impact-resistance-rating"],"sources":[{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/?p=2512","publisher":"Insurance Institute for Business & Home Safety (FORTIFIED Home)"},{"title":"FORTIFIED Roof Guide (Hurricane)","url":"https://www.smarthomeamerica.org/assets/uploads/ibhs-fortified-roof-guide-HUR.pdf","publisher":"IBHS / Smart Home America"},{"title":"Strengthen Alabama Homes","url":"https://strengthenalabamahomes.com/","publisher":"Alabama Department of Insurance"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"fouta-djallon-thatched-architecture","title":"Fouta Djallon Thatched Architecture","type":"article","summary":"Round earth houses and mosques of the Fulbe (Peul) of Guinea's Fouta Djallon highlands, crowned with heavy conical thatched roofs.","body":"The Fouta Djallon highlands of central Guinea are home to a distinctive Fulbe (Fula, Peul) building tradition of round earth-walled houses and square mosques covered by large, heavy thatched roofs. The highlands receive roughly 1,500-2,500 mm (60-100 in) of rain a year, most of it between June and September, and its roofs are designed above all to keep that water off unbaked earth walls.\n\n## Houses\n\nResidential buildings are usually circular, with a conical thatched roof over a single round room. Long rafters meet above the centre, run down over the walls and continue past them to rest on a ring of outer posts, forming a shaded veranda all round the house. The result is a very regular cone with wide eaves. There is no ceiling, so the underside of the thatch is visible from inside and may be decorated with horizontal rings of bound thatch. Walls, floors and beds can carry incised and painted geometric decoration.\n\n## Mosques\n\nFouta Djallon mosques reverse the usual relation between plan and roof. The prayer hall is a square earthen block, but it sits under a great conical or dome-like thatched roof that extends beyond the walls on a ring of stakes. Often cited as the largest and most elaborate example is the Friday Mosque of Dinguiraye, associated with the 19th-century leader El Hadj Umar Tall. Inside, a large central pillar flanked by smaller poles supports an earthen ceiling over the hall; above this, an inverted umbrella of radiating poles springing from the central pillar carries the thatch and stops the long rafters from sagging. The art historian Mark DeLancey describes it as a circular-plan roof centred on the pillar of a square-plan building.\n\n## Why heavy thatch\n\nDeLancey notes that the heavy thatch and wide eaves exist to protect the unbaked earth walls from the rains.\n\n## History\n\nA Fulbe Islamic state was founded in the Fouta Djallon in the early 18th century. Architecture of the region was documented by French colonial writers in the first half of the 20th century and later studied in detail by Labelle Prussin. A *case de couronnement* (coronation house) of the Almamy rulers of Fouta Djallon is on Guinea's tentative list for World Heritage nomination.","key_facts":[{"label":"Region","value":"Fouta Djallon, Guinea"},{"label":"People","value":"Fulbe (Fula, Peul)"},{"label":"Roof","value":"Conical thatch with veranda eaves"},{"label":"Rainfall","value":"About 1,500-2,500 mm (60-100 in) a year"},{"label":"Landmark","value":"Friday Mosque of Dinguiraye"}],"regions":["Africa"],"aliases":["Fulbe architecture","Peul round house","Dinguiraye mosque","case peule"],"related":["roofing-in-guinea","thatch","conical-roof","roofing-in-west-africa","roofing-in-senegal"],"sources":[{"title":"Localizing Fulbe Architecture","url":"https://condor.depaul.edu/mdelance/images/Pdfs/DeLancey%20-%20Localizing%20Fulbe%20Architecture.pdf","publisher":"Mark D. DeLancey, DePaul University"},{"title":"La case de couronnement des Almamy du Fouta Djallon","url":"https://whc.unesco.org/en/tentativelists/6820/","publisher":"UNESCO World Heritage Centre"},{"title":"Fouta Djallon","url":"https://en.wikipedia.org/wiki/Fouta_Djallon","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"fragile-roof","title":"Fragile Roof","category":"installation","type":"article","summary":"A roof or roof element, such as old fibre-cement sheeting or a rooflight, that will not safely carry a person's weight; a leading cause of roof-work deaths.","body":"A fragile roof is a roof or roof element that would not safely support the weight of a person, or of a person plus materials, if they stepped or fell onto it. Falls through fragile surfaces are among the most serious hazards in roof work. In Great Britain, the Health and Safety Executive (HSE) reports that they account for 22% of fatal falls from height in construction, and the National Association of Rooflight Manufacturers has cited a figure of about seven deaths a year (2014). People doing small, short maintenance and cleaning jobs are over-represented.\n\n## What can be fragile\n\nHSE lists typical fragile materials as:\n\n- non-reinforced fibre-cement sheets, whatever the profile, including older asbestos-cement sheets, which weathering makes more brittle;\n- rooflights, especially those in the roof plane, which can be hard to see in some light or when painted over;\n- liner panels on built-up sheeted roofs;\n- metal sheets that have corroded;\n- glass, including wired glass;\n- chipboard and similar boards that have rotted;\n- wood wool slabs, slates and tiles.\n\nHSE advises that every roof should be treated as fragile until a competent person confirms otherwise. Industry guidance adds that inspection cannot reliably prove that an existing roof is non-fragile, so existing roofs should be treated as possibly fragile unless documented evidence shows otherwise.\n\n## Testing and classification (UK)\n\nIn the mid-1990s the roofing industry and HSE formed the Advisory Committee for Roofsafety (ACR) to define non-fragility. Its test, ACR(M)001, drops a sand bag onto a roof assembly on a test rig to simulate a person stumbling and falling. Results are graded:\n\n- **Fragile:** fails the test.\n- **Class C:** holds the bag after one drop.\n- **Class B:** holds it after two drops in the same place, though damage is likely.\n- **Class A:** after two drops, no damage that would speed deterioration.\n\nClassification applies to the whole assembly (sheets, fixings, washers and supports), not the sheet alone. A rooflight cannot raise an assembly above the class of the surrounding roof, and poor fixing can lower it. ACR also publishes ACR(CP)002, a code of practice for safe working on fragile roofs.\n\n## Controls\n\nHSE's approach is to avoid work on fragile surfaces where possible, for example by working from below with a mobile elevating work platform. Where work must go ahead, risks are controlled with staging, guard rails, fall restraint, fall arrest and safety nets slung close beneath the roof. Warning signs should be fixed on the approach to any fragile surface, and workers trained and supervised. HSE's guide *Health and safety in roof work* (HSG33) covers fragile surfaces in detail, alongside the Work at Height Regulations 2005.\n\n## Other jurisdictions\n\nIn the United States, OSHA's construction standard 29 CFR 1926.501(b)(4) requires workers to be protected from falling through holes, explicitly including skylights, more than 1.8 m (6 ft) above a lower level, by personal fall arrest systems, covers or guardrails, and from stepping through such holes by covers.","key_facts":[{"label":"Share of UK construction fall deaths","value":"22% (HSE)"},{"label":"Common fragile materials","value":"Fibre-cement sheets, rooflights, corroded metal, glass"},{"label":"UK test","value":"ACR(M)001 drop test, Classes A, B, C"},{"label":"UK guidance","value":"HSE HSG33; ACR(CP)002"},{"label":"US rule","value":"OSHA 29 CFR 1926.501(b)(4), skylights over 6 ft (1.8 m)"}],"regions":["Global","Europe","North America"],"aliases":["fragile surface","fall-through hazard","non-fragile roof","skylight fall"],"related":["skylight","fibre-cement-slate","asbestos-cement-roofing","roofing-fall-protection","polycarbonate-roofing-sheet"],"company":null,"sources":[{"title":"Fragile surfaces","url":"https://www.hse.gov.uk/Construction/safetytopics/fragile.htm","publisher":"Health and Safety Executive"},{"title":"What is the point of a non-fragile roof?","url":"https://narm-3k7.pages.dev/what-is-the-point-of-a-non-fragile-roof/","publisher":"National Association of Rooflight Manufacturers"},{"title":"1926.501 - Duty to have fall protection","url":"https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.501","publisher":"US Occupational Safety and Health Administration"}],"country":null},{"slug":"francois-mansart","title":"François Mansart","category":"history","type":"person","summary":"French Baroque architect (1598-1666) whose frequent use of the double-sloped roof gave the mansard its name.","body":"**François Mansart** (23 January 1598 - 23 September 1666) was a French architect, born and died in Paris. He is regarded as one of the leading figures of French classical architecture in the 17th century. In roofing history he is remembered because the **mansard roof**, a four-sided double-sloped roof, carries his name.\n\n## Career\n\nMansart worked mainly for aristocratic and royal clients. His earliest surviving work is the **Château de Balleroy**. Other works include:\n\n- The **Temple du Marais** in Paris (1632), formerly the Church of St Mary of the Visitation;\n- The **Château de Maisons**, his best-preserved mature work, admired for its symmetry, original interior decoration and staircase;\n- The convent and church of **Val-de-Grâce** in Paris, begun in the 1640s for Anne of Austria. He was replaced by another architect, who largely followed his design.\n\n## The mansard roof\n\nMansart did not invent the double-pitched roof. The earliest known example is usually credited to Pierre Lescot at the Louvre around 1550, before Mansart was born. But he used the form so often and so elegantly that it became known by his name; \"mansard\" is a corruption of \"Mansart\". The design let architects fit a full storey of rooms within the roof, lit by dormers in the steep lower slope.\n\n## Family legacy\n\nHis great-nephew **Jules Hardouin-Mansart** (1646-1708) continued the family's architectural tradition and reused some of François's plans, notably for Les Invalides in Paris. The family name thus became attached both to a building type and to two generations of French classical architecture.\n\n## Influence on roofing\n\nTwo centuries after his death, the mansard roof was revived on a massive scale under Napoleon III and Haussmann, and from Paris it spread to Europe and North America. Its covering in zinc and slate on Paris apartment blocks remains one of the world's most recognisable roofscapes.","key_facts":[{"label":"Born","value":"23 January 1598, Paris"},{"label":"Died","value":"23 September 1666, Paris"},{"label":"Best-preserved work","value":"Château de Maisons"},{"label":"Relative","value":"Great-nephew Jules Hardouin-Mansart"}],"regions":["Europe"],"aliases":["Francois Mansart","Mansart"],"related":["mansard-roof-history","zinc-roofs-of-paris","mansard-roof"],"company":null,"sources":[{"title":"François Mansart","url":"https://en.wikipedia.org/wiki/Fran%C3%A7ois_Mansart","publisher":"Wikipedia"},{"title":"Mansard roof","url":"https://en.wikipedia.org/wiki/Mansard_roof","publisher":"Wikipedia"}],"country":null},{"slug":"freeze-thaw-damage","title":"Freeze-Thaw Damage","type":"term","summary":"Cracking, spalling and flaking of porous roofing materials caused by water freezing and thawing repeatedly inside pores and cracks.","body":"Freeze-thaw damage is the gradual breakdown of porous materials when water that has soaked into them freezes, thaws and freezes again. Clay and concrete roof tiles, natural stone and slate, masonry chimneys, mortar and some roof coatings are all vulnerable in climates where temperatures cross the freezing point many times each winter.\n\n## Mechanisms\n\nWater expands by about 9 percent when it freezes. If a pore is saturated and freezes from all sides, that expansion creates pressure that can crack the material. Research on frost weathering suggests that a related process called ice segregation is often more important: water is drawn through tiny capillaries toward growing ice lenses, which gradually pry the material apart. Ice growth can also pressurize unfrozen water in pores, a process called hydrofracture.\n\n## What it looks like\n\n- **Spalling:** flakes or layers breaking off the surface of tiles, slate or brick.\n- **Cracking** of tiles and mortar bedding at ridges and hips.\n- **Delamination** of slate along its natural layers.\n- **Crumbling** chimney masonry and mortar joints.\n- **Cracking of asphalt and pavement-like surfaces** where water enters existing cracks.\n\n## Material resistance\n\nWater absorption is a key indicator. Clay tiles with low porosity absorb little water; some manufacturers achieve moisture absorption below 2 percent, while concrete tiles average much higher absorption and are commonly resealed every few years. Standards specify freeze-thaw performance for roof tiles: ASTM C1167 in North America defines three grades of clay roof tile with differing resistance to weathering, and other regions have equivalent European and national standards. Choosing the grade suited to the local climate is important where winters are wet and cold.\n\n## Contributing conditions\n\n- Prolonged wetness, such as from blocked gutters, shaded north-facing slopes, moss and lichen;\n- Ponded water on low-slope roofs, which can freeze and break up the surface;\n- Ice dams that keep eaves saturated;\n- Poor ventilation beneath tiles and slates.\n\n## Prevention\n\nSpecifying frost-resistant materials, keeping roofs draining freely, removing moss, maintaining mortar and flashings, and ensuring adequate ventilation under tiles all reduce freeze-thaw damage.","key_facts":[{"label":"Water expansion on freezing","value":"About 9%"},{"label":"Most vulnerable","value":"Porous tile, stone, masonry, mortar"},{"label":"North American clay tile standard","value":"ASTM C1167 (three weathering grades)"}],"regions":["North America","Europe","East Asia","Arctic"],"aliases":["frost damage","frost weathering","freeze-thaw cycling","spalling"],"related":["clay-roof-tile","concrete-roof-tile","natural-slate","ice-dam","ponding-water"],"sources":[{"title":"Frost weathering","url":"https://en.wikipedia.org/wiki/Frost_weathering","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"ASTM C1167 Standard Specification for Clay Roof Tiles","url":"https://store.astm.org/c1167-11r17.html","publisher":"ASTM International"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"frei-otto","title":"Frei Otto","category":"history","type":"person","summary":"German architect and engineer (1925-2015), a pioneer of lightweight tensile and membrane roofs, including the Munich Olympic roofs.","body":"**Frei Otto** (31 May 1925 - 9 March 2015) was a German architect and structural engineer, born in Siegmar and died in Leonberg. He is regarded as the leading pioneer of lightweight tensile structures: roofs of cable nets and fabric membranes held in shape by tension rather than by rigid beams and arches.\n\n## Research\n\nIn **1964** Otto founded the **Institute for Lightweight Structures** at the University of Stuttgart. The institute became a centre for research into lightweight building, combining architecture and engineering.\n\n## Key roofs\n\n- **West German Pavilion, Expo 67, Montreal**, designed with Rolf Gutbrod, a tensile tent structure.\n- **Olympic Park, Munich**, 1972: Otto was development consultant to the architects Behnisch & Partner for the acrylic-glass cable-net roofs over the stadium and adjoining arenas.\n- **Multihalle, Mannheim**, 1975.\n- **Japan Pavilion, Expo 2000**, with architect Shigeru Ban: a roof structure made entirely of paper.\n\n## The Munich roofs\n\nMunich was Otto's best-known collaboration. Working with Günther Behnisch's office and the engineers Fritz Leonhardt, Wolf Andrä and Jörg Schlaich, he helped develop sweeping canopies of acrylic glass panels stabilised by steel cables. The stadium roof was completed on 21 April 1972, and was the first use of such a tent construction on this scale.\n\n## Pritzker Prize\n\nOtto was chosen to receive the **Pritzker Architecture Prize** in 2015. He died on 9 March 2015, shortly before the planned announcement, and the prize was made public on 10 March, earlier than intended, because of his death.\n\n## Legacy\n\nOtto's work is closely associated with the development of lightweight tensile and membrane roofs. The aim of enclosing large spaces with very little material connects his work with that of contemporaries such as Buckminster Fuller.","key_facts":[{"label":"Born","value":"31 May 1925, Siegmar, Germany"},{"label":"Died","value":"9 March 2015, Leonberg, Germany"},{"label":"Founded","value":"Institute for Lightweight Structures, Stuttgart, 1964"},{"label":"Pritzker Prize","value":"2015 (announced 10 March)"}],"regions":["Europe"],"aliases":["Frei Paul Otto"],"related":["munich-olympic-stadium-roof","tensile-membrane-roof","buckminster-fuller","jorn-utzon"],"company":null,"sources":[{"title":"Frei Otto","url":"https://en.wikipedia.org/wiki/Frei_Otto","publisher":"Wikipedia"},{"title":"Olympiastadion (Munich)","url":"https://en.wikipedia.org/wiki/Olympiastadion_(Munich)","publisher":"Wikipedia"}],"country":null},{"slug":"french-green-roof-law","title":"French Green Roof and Solar Law (2015)","type":"standard","summary":"A 2015 French law requiring roofs of new buildings in commercial zones to be partly covered with plants or solar panels.","body":"In March 2015, France approved a law requiring that the rooftops of new buildings in commercial zones be partially covered with vegetation or solar panels. The measure was reported internationally, including by the United Nations Framework Convention on Climate Change secretariat, as a significant national step toward greener roofs.\n\n## What it required\n\n- **Scope:** new buildings in commercial zones across France.\n- **Options:** roofs must be partly covered with plants (a green roof) or with renewable energy production such as solar panels.\n- **Partial coverage:** the law did not require full coverage of every roof, allowing owners to choose between, or combine, vegetation and solar.\n\n## Aims\n\nBoth options put otherwise unused roof space to work: vegetation for its insulating, rainwater-retention and habitat benefits, and solar panels for renewable electricity.\n\n## Checking current rules\n\nThe 2015 requirement should be read as a starting point. Building regulations change over time, so the obligations that apply to a specific French project should be checked against the regulations in force when it is permitted.\n\n## Comparison with other policies\n\nUnlike Toronto's bylaw, which sets coverage percentages by building size, or Basel's rule, which specifies substrate depth and native plants, the French law framed solar panels and green roofs as alternatives. This made it one of the first national laws to treat rooftop solar and vegetation as interchangeable ways to use roof space.\n\n## Practical implications for roofs\n\nThe two options place different demands on a building. An extensive green roof adds substrate and plants weighing roughly 50-120 kg/m² when established, and requires a root-resistant waterproofing layer, drainage and maintenance. Solar arrays add less weight in many cases but introduce attachments or ballast, electrical equipment and fire-access considerations. Designers therefore choose between the options based on structure, roof slope, orientation and the owner's priorities.","key_facts":[{"label":"Approved","value":"March 2015"},{"label":"Applies to","value":"New buildings in commercial zones"},{"label":"Options","value":"Vegetation or solar panels, partial coverage"}],"regions":["Europe"],"aliases":["France green roof law","French rooftop law","Paris green roof law"],"related":["green-roof","rooftop-solar-pv","toronto-green-roof-bylaw","basel-green-roof-policy"],"sources":[{"title":"France Mandates Green Roofs","url":"https://unfccc.int/news/france-mandates-green-roofs","publisher":"UNFCCC"},{"title":"France approves environmental law for commercial rooftops","url":"https://pv-magazine.com/2015/03/24/france-approves-environmental-law-for-commercial-rooftops_100018752","publisher":"pv magazine"},{"title":"France to Require Green Roofs for Commercial Buildings","url":"https://planetizen.com/node/75528","publisher":"Planetizen"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"fujian-tulou-roofs","title":"Fujian Tulou Roofs","type":"place","summary":"Tiled roofs with wide overhanging eaves that crown the circular and square earthen tulou of Fujian, China; a UNESCO World Heritage site.","body":"Fujian tulou are large, multi-storey earthen buildings in the mountains of south-western Fujian province, China, each designed to house an entire clan. Many were built by Hakka communities. Their thick earth walls are capped by continuous tiled roofs with very wide overhanging eaves. In 2008 UNESCO inscribed 46 of these buildings, spread over more than 120 km (75 miles), on the World Heritage List.\n\n## Form\n\nTulou are circular or square in plan and face inward around a central open courtyard, with usually only one entrance. Rooms line the outer wall on typically three to five floors, connected by timber galleries facing the courtyard. The UNESCO listing dates the buildings from the 13th or 15th to the 20th century, with the most elaborate examples from the 17th and 18th centuries.\n\n## The roof\n\nThe roof of a tulou follows the ring or square of rooms below it. It is a timber-framed, pitched roof covered in baked clay tiles. On round tulou the tiles are laid radially; because the outer circumference is longer than the inner, small extra tiles in a λ (lambda) shape are inserted to close the widening gaps. Unlike much formal Chinese architecture, the timber roof frame does not use *dougong* bracket sets.\n\nTwo features matter most:\n\n- **Wide eaves.** The earth walls are vulnerable to rain. Overhangs of about 2 m (6.5 ft) throw water clear of the wall face and shade the upper storeys.\n\n## Climate and defence\n\nSouthern Fujian has hot, humid summers and heavy rain from monsoon and typhoon systems. The combination of thick earth walls and deep tiled overhangs keeps interiors relatively cool and dry. The buildings were also defensive: the outer wall is high and almost windowless at lower levels, and the roof sits above it as a single protective lid.\n\n## Conservation\n\nMaintaining a tulou roof is labour-intensive. Broken or slipped tiles let water into the timber frame and onto the earth walls, which can then erode. Conservation work focuses on keeping the roof intact so the rest of the structure survives.","key_facts":[{"label":"Location","value":"South-western Fujian, China"},{"label":"Inscribed buildings","value":"46"},{"label":"Roof","value":"Timber-framed, fired clay tiles, wide eaves"},{"label":"Plan","value":"Circular or square around a courtyard"},{"label":"Communities","value":"Clans, many of them Hakka"}],"regions":["East Asia"],"aliases":["Hakka tulou","Tulou","Earthen buildings of Fujian"],"related":["roofing-in-china","siheyuan-roof","clay-roof-tile","eaves","rammed-earth"],"sources":[{"title":"Fujian Tulou","url":"https://whc.unesco.org/en/list/1113","publisher":"UNESCO World Heritage Centre"},{"title":"Fujian tulou","url":"https://en.wikipedia.org/wiki/Fujian_tulou","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"fully-adhered-roof-system","title":"Fully Adhered Roof System","category":"low-slope-systems","type":"term","summary":"A low-slope roof in which the entire underside of the membrane is bonded to the substrate with adhesive or by heat, with no loose areas.","body":"In a fully adhered roof system, the membrane is bonded continuously to the insulation, cover board or deck beneath it. Bonding may use contact adhesive applied to both surfaces, water-based or low-VOC adhesive, low-rise polyurethane foam adhesive, hot asphalt, torching, or a factory-applied self-adhesive backing.\n\n## Membranes\n\n- **EPDM:** bonded with contact adhesive or as fleece-backed sheet set in adhesive.\n- **TPO and PVC:** smooth or fleece-backed sheets in contact or foam adhesive.\n- **PIB:** usually fleece-backed and bonded with cold adhesive.\n- **Modified bitumen and BUR:** inherently adhered by mopping, torching or cold adhesive.\n- **Liquid-applied membranes and spray foam:** bonded by their nature.\n\n## Advantages\n\n- smooth, wrinkle-free appearance\n- no billowing, because wind cannot get under the sheet\n- uplift resistance governed by the bond and substrate attachment\n- easier leak tracing, since water cannot travel far under a bonded sheet\n- suits complex roofs, curved surfaces and areas where fasteners are undesirable\n\n## Limitations\n\nFull adhesion is slower than mechanical fastening, uses large quantities of adhesive, and is sensitive to temperature, humidity and substrate moisture. Solvent-based adhesives release VOCs and odour; water-based products need warm, dry curing conditions. The substrate must be clean, dry and strong enough; facer delamination of insulation or a weak cover board can become the failure point in high winds, which is one reason cover boards are common under adhered membranes.\n\n## Fleece-backed sheets\n\nFleece-backed membranes, made in EPDM, TPO, PVC and PIB, carry a non-woven fabric on the underside. The fleece provides a bonding surface for adhesives, protects the membrane from rough substrates, and makes these sheets popular for recovering old roofs.","key_facts":[{"label":"Bond types","value":"Contact, water-based, foam adhesive; hot bitumen; self-adhesive"},{"label":"Key advantage","value":"No billowing; smooth finish"},{"label":"Key limitation","value":"Weather- and substrate-sensitive"}],"regions":["Global"],"aliases":["adhered roof","fully bonded membrane","adhered single ply"],"related":["mechanically-attached-roof-system","ballasted-roof-system","cover-board","epdm-roofing","self-adhered-membrane"],"company":null,"sources":[{"title":"Technical Details: Thermoset Membranes - EPDM Technology and Repair","url":"https://roofingcontractor.com/articles/85516-technical-details-thermoset-membranes-epdm-technology-and-repairp","publisher":"Roofing Contractor"},{"title":"Thermoplastic Polyolefin (TPO) Roofing Systems","url":"https://buildings.com/articles/35297/thermoplastic-polyolefin-tpo-roofing-systems","publisher":"Buildings"},{"title":"Rhepanol hfk brochure","url":"https://produktinfo.blauer-engel.de/uploads/pdf_uploads/25837_DOS_FDT_Broschuere_Rhepanol-hfk_A4_ENG_WEB_en.pdf","publisher":"FDT FlachDach Technologie / Blauer Engel"},{"title":"Cool Roofs","url":"https://www.energy.gov/energysaver/cool-roofs","publisher":"U.S. Department of Energy"}],"country":null},{"slug":"fully-adhered-vs-mechanically-attached","title":"Fully Adhered vs Mechanically Attached","category":"installation","type":"article","summary":"Low-slope membranes are attached by gluing the whole sheet to the substrate (fully adhered), fastening it at laps (mechanically attached) or holding it with ballast.","body":"A low-slope roof membrane must be held against wind uplift. The three main attachment methods for single-ply membranes such as EPDM, TPO and PVC are **fully adhered**, **mechanically attached** and **ballasted**. Some systems also use induction-welded plates, and bituminous membranes can be torched, mopped or self-adhered. The choice affects wind performance, cost, appearance, noise and how the roof behaves if punctured.\n\n## Fully adhered\n\nThe membrane is bonded across its whole area to the insulation, cover board or deck. Canadian guidance describes folding back half the sheet, applying adhesive at the manufacturer's rate, rolling it back in and brooming or rolling out trapped air, while keeping adhesive out of the lap area. Most manufacturers limit adhered sheets to a maximum width of about 3 m (10 ft). Fleece-backed membranes can be set in hot asphalt or low-rise foam adhesive.\n\nAdvantages: smooth appearance, no membrane flutter, good performance on irregular roofs. Limitations: higher labour and adhesive cost and temperature limits on adhesives.\n\n## Mechanically attached\n\nThe membrane is fastened through the laps with plates or bars screwed into the deck; the next sheet covers the fasteners and is welded or taped over them. Canadian guidance notes that sheets usually run perpendicular to the deck flutes, and that fastener spacing follows the manufacturer and local wind pressures. A recommended minimum slope of 1:50 (2 percent) applies to both adhered and mechanically fastened thermoplastics.\n\nAdvantages: fast, fewer temperature limits, lighter than ballast. Limitations: the membrane can billow in wind and fastener pull-out must be designed for each zone of the roof.\n\n## Ballasted\n\nLoose-laid membranes are held by stone or pavers. Canadian guidance gives about 60 kg/m² (about 1200 lb per square), more in high-wind areas, and limits loose-laid ballasted roofs to slopes of no more than 1:6. The structure must carry the extra load.\n\n## Induction welding\n\nSome thermoplastic systems fasten coated plates to the deck under the membrane and bond the membrane to them with an induction tool, avoiding fasteners through the sheet.\n\n## Design basis\n\nIn all methods, perimeter and corner zones receive higher attachment rates than the field, following wind-load calculations and approval listings.","key_facts":[{"label":"Recommended minimum slope (Canada)","value":"1:50 (2%)"},{"label":"Typical ballast (Canada)","value":"About 60 kg/m² (1200 lb/square)"},{"label":"Max adhered sheet width","value":"About 3 m (10 ft)"}],"regions":["Global"],"aliases":["adhered membrane","mechanically fastened membrane","ballasted roof"],"related":["hot-air-welding","single-ply-roofing","epdm-roofing","tpo-roofing","wind-uplift"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 7.1.3 Thermoplastic Membrane Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-7-single-ply-roofing-membranes/7-1-thermoplastics/7-1-3-membrane-installation/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 7.2.2 Adhered System","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-7-single-ply-roofing-membranes/7-2-thermoset-membranes/7-2-2-adhered-system/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"funco","title":"Funco (Cabo Verde Round House)","type":"term","summary":"Traditional round stone house of Cabo Verde with a conical roof thatched with palm fronds, found mainly on Fogo, Santiago and Maio.","body":"The *funco* is the traditional rural house of Cabo Verde: a small circular building with stone walls and a conical thatched roof. It is found mainly on the islands of Fogo, Santiago and Maio, and is generally described as a house form of African origin, related to round houses on the West African mainland, including Guinea-Bissau.\n\n## Construction\n\nWalls are built of local stone; on Fogo, builders in the crater settlement of Chã das Caldeiras used black bricks made from lava. The roof is a cone of palm fronds, or straw, laid over a timber frame. The steep cone sheds rain quickly from the thatch.\n\n## Social history\n\nIn colonial Cabo Verde, the funco was associated with poorer and mainly Black rural households, while the two-storey *sobrado* town houses, concentrated in places such as São Filipe on Fogo, belonged to wealthier, mainly white families. The ethnographer António Carreira (1965) recorded that the word itself meant a small, poor building. The novelist Henrique Teixeira de Sousa wrote about the funco in his studies of Fogo society.\n\n## Chã das Caldeiras\n\nThe village of Chã das Caldeiras, inside the Fogo volcano crater, kept a high proportion of round, single-storey thatched houses; huts made up about a quarter of the village. It was rebuilt after the 1995 eruption, largely destroyed in the 2014-15 eruption, and new lava-built huts were constructed from early 2016.\n\n## Today\n\nThe funco has largely given way to block-built houses; since independence in 1975 many new buildings in Cabo Verde have flat roofs. Examples survive in villages and in the Museu Municipal de São Filipe on Fogo. Two settlements in São Lourenço dos Órgãos on Santiago, Funco Bandeira and Funco Marques, take their names from the type, and the national architects' association named its discussion portal \"Funco\" in its honour.","key_facts":[{"label":"Country","value":"Cabo Verde"},{"label":"Islands","value":"Mainly Fogo, Santiago, Maio"},{"label":"Plan","value":"Circular"},{"label":"Walls","value":"Stone; lava brick on Fogo"},{"label":"Roof","value":"Conical palm-frond or straw thatch"}],"regions":["Africa"],"aliases":["funco house","Cape Verdean round house"],"related":["roofing-in-cabo-verde","roofing-in-guinea-bissau","palm-thatch","thatch","conical-roof"],"sources":[{"title":"Funco (architecture)","url":"https://en.wikipedia.org/wiki/Funco_(architecture)","publisher":"Wikipedia"},{"title":"Architecture of Cape Verde","url":"https://en.wikipedia.org/wiki/Architecture_of_Cape_Verde","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"gable-roof","title":"Gable Roof","category":"roof-forms","type":"article","summary":"A gable roof has two sloping planes meeting at a central ridge, leaving a triangular wall section, the gable, at each end.","body":"A gable roof is the simple pitched roof with two slopes rising from opposite walls to meet at a horizontal ridge. The triangular portion of end wall enclosed by the two slopes is the gable. It is one of the most widespread roof forms in the world and is also called a ridged, saddle, span, peaked or dual-pitched roof.\n\n## Variants\n\n- **Front-gabled:** the gable faces the street, so the ridge runs perpendicular to it. Typical of Gothic-era German town houses and of American gablefront houses from the early 1800s to about 1920.\n- **Side-gabled:** the eaves face the street, with the ridge parallel to it.\n- **Cross-gabled:** two or more gable roofs intersect, usually at right angles, forming T, L or more complex plans with valleys at the junctions.\n- **Box gable:** the gable is enclosed as a separate element with boxed ends.\n- **Shaped, Dutch and crow-stepped gables:** decorative parapets that hide the sloping roof line behind curves or steps; common in the Netherlands, Belgium, Scotland and eastern England.\n- **Clipped or jerkinhead gable:** the top of the gable is cut off by a small hip.\n\n## Advantages\n\n- Simple to frame with rafters or common trusses and inexpensive to build.\n- Sheds rain and snow well, and accommodates nearly every roof covering.\n- Produces usable attic space and allows windows in the gable walls.\n- Gable ends are convenient places for attic ventilation louvres.\n\n## Weaknesses\n\nGable-ended roofs perform less well than hipped roofs in hurricane- and tornado-prone regions. Wind striking the flat gable wall, and uplift along the rake edges, can peel off roof sheathing and cause the gable wall to collapse. Building codes in high-wind regions therefore require bracing of gable end walls and stronger connections at the rakes. Wide overhangs at the rake also increase uplift.\n\n## Global use\n\nSteep gable roofs are typical of snowy or rainy climates and traditional thatched, tiled and shingled buildings across Europe, North America and East Asia. The A-frame is an extreme form in which the roof slopes reach nearly to the ground.","key_facts":[{"label":"Planes","value":"Two"},{"label":"Other names","value":"Saddle, span, ridged, peaked roof"},{"label":"Weakness","value":"Gable ends in high winds"}],"regions":["Global"],"aliases":["gabled roof","pitched roof","saddle roof","span roof","peaked roof"],"related":["hip-roof","cross-gabled-roof","jerkinhead-roof","a-frame-roof","roof-rake","bargeboard"],"company":null,"sources":[{"title":"Gable","url":"https://en.wikipedia.org/wiki/Gable","publisher":"Wikipedia"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"},{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"}],"country":null},{"slug":"gaf","title":"GAF","category":"manufacturers","type":"company","summary":"GAF is a US manufacturer of residential and commercial roofing, founded in 1886 and owned by Standard Industries.","body":"GAF is a North American roofing manufacturer headquartered in Parsippany, New Jersey. It traces its origins to the Standard Paint Company, founded in 1886 in Bound Brook, New Jersey, and is today an operating company of the privately held Standard Industries. GAF makes asphalt shingles for steep-slope homes as well as membranes and insulation for low-slope commercial roofs.\n\n## Corporate history\n\nThe company's early business was asphalt-based roofing. In 1893 it introduced a ready-to-lay asphalt roll roofing sold under the trademark Ruberoid, and by 1898 it was adding ceramic granules to the surface of those rolls, an approach later carried over into the modern granule-surfaced shingle. The firm took the name The Ruberoid Co. in 1921 and was listed on the New York Stock Exchange in 1935.\n\nIn 1967 Ruberoid merged with General Aniline & Film, and the combined business adopted the GAF name in 1968. The same period saw the launch of the Timberline line, described by the company as the first laminated (dimensional) shingle. In 2007 GAF merged with Elk Corporation (ElkCorp), another asphalt roofing producer. Standard Industries, the holding company that owns GAF, later added the European roofing group BMI and the low-slope specialist Siplast to its portfolio.\n\n## Products and operations\n\nGAF's residential range centres on laminated asphalt shingles, along with underlayments, ridge caps, ventilation and other accessories sold as a system. Its commercial range includes thermoplastic polyolefin (TPO) membranes, polyisocyanurate (polyiso) insulation, PVC accessories and coatings. The company reports around 30 locations across the United States. It announced commercial manufacturing expansions in Peru, Illinois and Valdosta, Georgia in 2022, and a new residential shingle plant in Kansas in 2024.\n\n## Solar roofing\n\nIn 2019 the group launched GAF Energy, a sister business focused on roof-integrated solar. In 2022 it introduced Timberline Solar, a solar shingle designed to be fastened with roofing nails like a conventional shingle rather than mounted on racking.\n\n## Warranties and programmes\n\nGAF offers manufacturer warranties on its shingle systems and runs contractor certification programmes in North America. In 2021 it introduced a process it calls RoofCycle, aimed at recovering material from torn-off shingles.","key_facts":[{"label":"Founded","value":"1886 (as Standard Paint Company)"},{"label":"Headquarters","value":"Parsippany, New Jersey, US"},{"label":"Parent","value":"Standard Industries"},{"label":"Main products","value":"Asphalt shingles, TPO membranes, polyiso insulation"}],"regions":["North America"],"aliases":["GAF Materials Corporation","General Aniline & Film","Ruberoid"],"related":["standard-industries","asphalt-shingle","tpo-roofing","bmi-group","building-integrated-photovoltaics"],"company":{"founded":"1886","headquarters":"Parsippany, New Jersey, United States","website":"https://www.gaf.com","parent":"Standard Industries","known_for":["Asphalt shingles","Timberline laminated shingles","TPO membranes","Timberline Solar shingles"]},"sources":[{"title":"GAF Materials Corporation","url":"https://en.wikipedia.org/wiki/GAF_Materials_Corporation","publisher":"Wikipedia"},{"title":"The History of GAF","url":"https://nationalroofingmuseum.org/the-history-of-gaf/","publisher":"National Roofing Museum"},{"title":"Who we are","url":"https://standardindustries.com/who-we-are","publisher":"Standard Industries"}],"country":null},{"slug":"galvalume","title":"Galvalume (55% Aluminium-Zinc Coated Steel)","category":"materials","type":"article","summary":"Galvalume is steel sheet hot-dip coated with an alloy of about 55% aluminium, 43% zinc and 1.5% silicon; it is the most common substrate for coated-steel roofs.","body":"Galvalume is the best-known trade name for steel sheet carrying a 55% aluminium-zinc alloy coating. The coating is roughly 55% aluminium, 43 to 44% zinc and about 1.5% silicon. The silicon controls the growth of the alloy layer between coating and steel and helps the coating stay attached when the sheet is roll-formed. GALVALUME is a registered trademark of BIEC International Inc., used under licence by steel producers; the same type of coating is sold under many other trade names around the world, such as ZINCALUME.\n\n## How it protects\n\nThe aluminium-rich part of the coating forms a durable barrier, while the zinc-rich part supplies some sacrificial (galvanic) protection at scratches and edges. Producers and coating specialists describe its atmospheric corrosion resistance as considerably better than that of galvanized steel; the GalvInfo Center reports that it outlasts galvanized steel by two to four times, depending on the environment. Like galvanized coatings it is consumed over time, and it is thinnest at cut edges.\n\n## Specification\n\nIn North America the product is covered by ASTM A792. Coating mass is given as total for both sides: AZ50 is 0.50 oz/ft2 (AZM150, about 150 g/m2) and AZ55 is 0.55 oz/ft2 (AZM165). The standard spans roughly 0.30 to 0.70 oz/ft2 (100 to 210 g/m2). Because aluminium is less dense than zinc, an AZ coating is thicker than a zinc coating of the same weight. AZ50 is often chosen where heavy forming is needed; AZ55 where corrosion resistance matters most. Comparable products are made to AS 1397 in Australia.\n\n## Limitations\n\n- It is a poor partner for copper; water running from copper onto it, or direct contact, accelerates corrosion.\n- Many roofing warranties restrict or exclude Galvalume installed close to salt water.\n- Some producers neither recommend nor warrant it for animal confinement buildings (swine, cattle, poultry), where waste by-products attack the coating.\n\nGalvalume takes paint well and is the usual base for factory-painted steel roofing.","key_facts":[{"label":"Coating composition","value":"About 55% Al, 43-44% Zn, 1.5% Si"},{"label":"Standard","value":"ASTM A792 (North America); AS 1397 (Australia)"},{"label":"Common coatings","value":"AZ50 (AZM150) and AZ55 (AZM165)"},{"label":"Trademark holder","value":"BIEC International, Inc."}],"regions":["Global"],"aliases":["Zincalume","Aluzinc","55% Al-Zn coated steel","aluminium-zinc coated steel","AZ steel"],"related":["galvanized-steel-roofing","metallic-coating-designations","colorbond-steel","galvanic-corrosion","coil-coating"],"company":null,"sources":[{"title":"Metallic-Coated Products and Specifications (GalvInfoNote 1.2)","url":"https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote_1_2.pdf","publisher":"GalvInfo Center"},{"title":"Metallic-Coated Products and Specifications (GalvInfoNote 1.1)","url":"https://www.galvinfo.com/wp-content/uploads/sites/8/2021/01/GalvInfoNote-1-1-Rev-4-0.pdf","publisher":"GalvInfo Center"},{"title":"Galvalume Sheet","url":"https://wheeling-nipponsteel.com/galvalume","publisher":"Wheeling-Nippon Steel"},{"title":"ASTM Coated Sheet Steel for Construction: Galvalume ASTM Coating Weights","url":"https://www.mcelroymetal.com/hubfs/assets/galvalume-astm-coating-weights.pdf","publisher":"McElroy Metal / U.S. Steel"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"GalvInfoNote 1.4: 55% Aluminum-Zinc Alloy-Coated Sheet Steel","url":"https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote_1_4.pdf","publisher":"GalvInfo Center"},{"title":"Aluminum vs. Galvalume vs. Steel Roofing Compared","url":"https://www.interlockroofing.com/kb/aluminum-vs-galvalume-vs-steel/","publisher":"Interlock Roofing"},{"title":"The Best Roof for Coastal and Salt-Air Homes","url":"https://www.interlockroofing.com/kb/best-roof-coastal-salt-air/","publisher":"Interlock Roofing"},{"title":"Durability: Compatibility (NZ Metal Roof and Wall Cladding Code of Practice)","url":"https://www.metalroofing.org.nz/cop/durability/compatibility","publisher":"NZ Metal Roofing Manufacturers"}],"country":null},{"slug":"galvanic-corrosion","title":"Galvanic Corrosion and Metal Compatibility","category":"problems-maintenance","type":"article","summary":"Galvanic corrosion is accelerated attack on one metal when it touches, or is wetted by run-off from, a more noble metal; it governs which roof metals can be combined.","body":"When two different metals are in electrical contact and wetted by an electrolyte such as rain, dew or salty air, they form a small battery. The more active metal (the anode) corrodes faster than it would alone, while the more noble metal (the cathode) is protected. On roofs this explains why some flashings, fasteners and gutters fail early when mixed with the wrong metal.\n\n## The galvanic series\n\nEngineers rank metals by an \"anodic index\". From more noble to more active, approximate values are:\n\n- Copper about -0.35 V\n- Stainless steel (18% chromium) about -0.50 V\n- Tin and tin-lead solder about -0.65 V\n- Lead about -0.70 V\n- Carbon steel about -0.85 V\n- Wrought aluminium about -0.90 V\n- Galvanized steel about -1.20 V\n- Zinc about -1.25 V\n\nOutdoors, a difference of more than about 0.15 V is considered risky. Copper with aluminium, zinc or galvanized steel is a classic bad pairing.\n\n## Area and flow\n\nA small anode attached to a large cathode corrodes fastest, so a steel screw in copper sheet fails quickly, while a copper rivet in steel is less severe. Water flowing from a noble metal onto an active one carries dissolved ions that also cause attack: copper run-off onto Galvalume, zinc or aluminium gutters is a common problem.\n\n## Practical rules\n\n- Use fasteners of the same metal or a compatible, more noble one: copper, bronze or 300-series stainless steel with copper; stainless or aluminium fasteners with aluminium, never bare or ordinary steel.\n- Separate dissimilar metals with bituminous coatings, membranes or non-conductive spacers.\n- Keep copper and its run-off away from aluminium, zinc, galvanized steel and aluminium-zinc coated steel.\n\n## Famous example\n\nThe Statue of Liberty suffered galvanic attack where its copper skin met its wrought iron framework after the original shellac insulation failed; restoration replaced the insulation with PTFE.","key_facts":[{"label":"Needed for corrosion","value":"Two metals, electrical contact, electrolyte"},{"label":"Outdoor risk threshold","value":"Anodic index difference above ~0.15 V"},{"label":"Classic bad pairing","value":"Copper with aluminium, zinc or galvanized steel"}],"regions":["Global"],"aliases":["bimetallic corrosion","dissimilar metal corrosion","galvanic series","metal compatibility"],"related":["copper-runoff-staining","metal-roof-fasteners","galvalume","aluminum-roofing","copper-roofing"],"company":null,"sources":[{"title":"Galvanic corrosion","url":"https://en.wikipedia.org/wiki/Galvanic_corrosion","publisher":"Wikipedia"},{"title":"14.3. Copper Roofing (architectural specifications)","url":"https://archive.copper.org/applications/architecture/arch_dhb/specifications/arch_specs/sheet_roofing.php","publisher":"Copper Development Association"},{"title":"Aluminum Roofing Fasteners: Concealed vs Exposed Explained","url":"https://www.interlockroofing.com/kb/aluminum-roofing-fasteners-concealed-vs-exposed/","publisher":"Interlock Roofing"},{"title":"Metal Roofing Problems: The Honest 20-Year Guide","url":"https://www.interlockroofing.com/kb/metal-roofing-problems/","publisher":"Interlock Roofing"},{"title":"Durability: Compatibility (NZ Metal Roof and Wall Cladding Code of Practice)","url":"https://www.metalroofing.org.nz/cop/durability/compatibility","publisher":"NZ Metal Roofing Manufacturers"}],"country":null},{"slug":"galvanized-steel-roofing","title":"Galvanized Steel Roofing","category":"materials","type":"article","summary":"Galvanized steel roofing is sheet steel coated with zinc, usually by hot-dipping, so the zinc corrodes sacrificially and protects the steel underneath.","body":"Galvanized steel is carbon steel sheet that has been coated with zinc. For roofing, the coating is almost always applied by continuous hot-dip galvanizing: the steel strip passes through a bath of molten zinc, and air knives wipe the surface to control how much zinc stays on. A small amount of aluminium in the bath improves adhesion and makes the coating easier to form.\n\nZinc protects steel in two ways. It acts as a barrier, and because zinc is more electrochemically active than iron it corrodes first, shielding small scratches and cut edges. That protection lasts only while zinc remains; once the coating is consumed, the steel beneath begins to rust.\n\n## History\n\nZinc galvanizing of iron was developed in France in 1837, and by the 1850s galvanized corrugated iron was being used on post offices, train sheds and factories. Early sheets were hand-dipped and carried heavy coatings. Continuous galvanizing lines, adopted from the 1930s, gave thinner, more uniform and more formable coatings.\n\n## Coating weights\n\nIn North America, ASTM A653 designates coatings by total zinc on both sides. G90 means a minimum average of 0.90 oz/ft2, equal to about 275 g/m2 and labelled Z275 in metric; G60 is about 183 g/m2. G90 adds roughly 42 micrometres (1.6 mils) of total coating thickness. For zinc coatings, corrosion life rises roughly in line with coating weight, so G90 lasts about half as long again as G60 in the same environment.\n\n## Use today\n\nPlain galvanized sheet is still used for agricultural, industrial and low-cost roofs, often painted. For many roofing products it has been largely displaced by aluminium-zinc coatings such as Galvalume, which generally last longer in most atmospheres. Galvanized steel corrodes faster in marine or acidic environments, and regular painting extends its life.","key_facts":[{"label":"Coating","value":"Zinc, applied by continuous hot-dip process"},{"label":"North American standard","value":"ASTM A653"},{"label":"G90 coating","value":"0.90 oz/ft2 total (about 275 g/m2, Z275)"},{"label":"Galvanizing developed","value":"France, 1837"}],"regions":["Global"],"aliases":["galvanised steel","zinc-coated steel","GI sheet","hot-dip galvanized steel"],"related":["galvalume","metallic-coating-designations","corrugated-iron","galvanic-corrosion","metal-roofing"],"company":null,"sources":[{"title":"Metallic-Coated Products and Specifications (GalvInfoNote 1.1)","url":"https://www.galvinfo.com/wp-content/uploads/sites/8/2021/01/GalvInfoNote-1-1-Rev-4-0.pdf","publisher":"GalvInfo Center"},{"title":"ASTM Coated Sheet Steel for Construction: Galvalume ASTM Coating Weights","url":"https://www.mcelroymetal.com/hubfs/assets/galvalume-astm-coating-weights.pdf","publisher":"McElroy Metal / U.S. Steel"},{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"},{"title":"Corrugated galvanised iron","url":"https://en.wikipedia.org/wiki/Corrugated_galvanised_iron","publisher":"Wikipedia"}],"country":null},{"slug":"gambrel-roof","title":"Gambrel Roof","category":"roof-forms","type":"article","summary":"A gambrel roof is a two-sided roof with two slopes on each side, a steep lower slope and a shallow upper one, giving a characteristic barn profile.","body":"A gambrel roof is a symmetrical roof with two slopes on each of its two sides: a steep lower pitch rising from the eaves and a shallower upper pitch meeting at the ridge. The ends are vertical gables. Because the lower slopes are steep, a gambrel encloses much more usable space than a simple gable roof of the same height, which is why it is strongly associated with barns and with two-storey houses whose upper floor sits within the roof.\n\nThe term is thought to derive from an older word for the hock of a horse's hind leg, which the bent profile resembles. In British English the same form is often called a curb or kerb roof; the horizontal line where the two pitches meet is the curb.\n\n## Gambrel versus mansard\n\nBoth are curb roofs with two pitches per side. A gambrel has two roof sides and gable ends; a mansard is hipped, with two pitches on all four sides. In continental Europe \"mansard\" is sometimes used for both.\n\n## History and use\n\n- **North America:** gambrel roofs appear on houses of the 17th and 18th centuries in New England and the Dutch-influenced Hudson Valley. A common form is seen on the 1752 Captain Joseph Atwood house in Chatham, Massachusetts. In the 19th and 20th centuries the gambrel became the classic profile of the American barn, where the large loft stored hay, and it was later revived in Dutch Colonial Revival houses.\n- **Europe:** similar double-pitched profiles appear on barns and houses in Britain and continental Europe, where they are often grouped with mansards.\n\n## Considerations\n\n- The break in slope (the curb) needs careful framing and flashing; the shallow upper slope may need extra underlayment or a low-slope-rated covering.\n- The flat gable ends present a large area to wind, so bracing matters in high-wind regions.\n- Snow can accumulate at the curb on the lower slope.\n- Gambrel trusses are widely available, making the form popular for sheds, garages and outbuildings.","key_facts":[{"label":"Slopes per side","value":"Two (steep lower, shallow upper)"},{"label":"Ends","value":"Vertical gables"},{"label":"UK name","value":"Curb (kerb) roof"},{"label":"Example","value":"Atwood house, Chatham, MA (1752)"}],"regions":["North America","Europe"],"aliases":["curb roof","kerb roof","barn roof","Dutch Colonial roof"],"related":["mansard-roof","gable-roof","bonnet-roof","roof-truss"],"company":null,"sources":[{"title":"Gambrel","url":"https://britannica.com/technology/gambrel","publisher":"Encyclopaedia Britannica"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"},{"title":"Mansard roof","url":"https://en.wikipedia.org/wiki/Mansard_roof","publisher":"Wikipedia"}],"country":null},{"slug":"gando-primary-school","title":"Gando Primary School","type":"place","summary":"School in Gando, Burkina Faso (2001), by Diébédo Francis Kéré, known for a raised metal roof floating over a ventilated earth-block ceiling.","body":"The primary school at Gando, a village on the southern plains of Burkina Faso about 200 km (125 miles) from Ouagadougou, was designed by the architect Diébédo Francis Kéré. Built between October 2000 and July 2001 and awarded the Aga Khan Award for Architecture in 2004, it became an internationally cited example of a climate-responsive roof made from simple materials.\n\n## The roof problem\n\nCorrugated metal sheet is a common roof for schools and houses in Burkina Faso, but fixed directly over a room it transmits a great deal of solar heat. The Gando design separates the two jobs of a roof: keeping off the rain and keeping out the heat.\n\n## The double roof\n\n- **Ceiling.** Over the classrooms is a ceiling of compressed earth blocks laid on steel bars that span between concrete beams. The earth mass absorbs heat and moderates the indoor temperature.\n- **Rain roof.** Above it, a corrugated metal roof sits on lightweight trusses made from ordinary steel reinforcing bar. Because the metal roof is raised clear of the ceiling, air can flow through the gap, carrying away the heat that the sheet absorbs. The overhanging roof also shades the walls.\n\nWalls are load-bearing stabilised compressed earth blocks.\n\n## Construction\n\nThe school was built largely by hand by the villagers, men, women and children. Funding came through the German association Schulbausteine für Gando, the government agency LOCOMAT trained local brickmakers, and the project managers all came from the village. The method kept money and skills in the community and avoided dependence on imported components other than the steel and roof sheet.\n\n## Influence\n\nLater buildings in the Gando school complex, including a library, developed the same approach, and the raised, ventilated metal roof over a heavy earth ceiling is often cited as a low-cost way to make metal-roofed buildings in hot climates more comfortable.","key_facts":[{"label":"Location","value":"Gando, Burkina Faso"},{"label":"Architect","value":"Diébédo Francis Kéré"},{"label":"Built","value":"October 2000 - July 2001"},{"label":"Roof","value":"Raised corrugated metal on rebar trusses over earth-block ceiling"},{"label":"Award","value":"Aga Khan Award for Architecture, 2004"}],"regions":["Africa"],"aliases":["Primary School in Gando","Gando school"],"related":["roofing-in-burkina-faso","corrugated-iron","nubian-vault","sahelian-earthen-roofs","cold-roof"],"sources":[{"title":"Primary School at Gando","url":"https://archnet.org/sites/4363","publisher":"Archnet / Aga Khan Award for Architecture"},{"title":"Gando Primary School Library by Kéré Architecture","url":"https://www.metalocus.es/en/news/gando-primary-school-library-kere-architecture-third-piece-complex","publisher":"Metalocus"},{"title":"Basic School in Gando","url":"https://www.archiweb.cz/en/b/zakladni-skola-v-gando","publisher":"Archiweb"}],"company":null,"category":"world-roofing","country":null},{"slug":"garantie-decennale","title":"Garantie Décennale","category":"standards-codes","type":"standard","summary":"France's ten-year builder liability for serious defects, set by the 1978 Spinetta law, with compulsory insurance for builders and owners.","body":"The **garantie décennale** (ten-year liability, often translated as decennial liability) is the French legal rule that makes builders responsible, for ten years after the works are accepted, for serious defects in what they build. It applies to roofers as to other trades, and it is one reason French roofing contracts, insurers and courts refer so closely to the NF DTU technical rules.\n\n## Legal basis\n\nThe modern regime comes from the Spinetta law of 1978, reflected in Article 1792 and following articles of the French Civil Code. Article 1792-1 defines who counts as a builder: architects, contractors and technicians bound to the owner by a contract for works, anyone who sells a building they built or had built, and certain agents with similar duties. Article 1792-6 defines acceptance (*réception*) of the works, which starts the ten-year period.\n\n## What it covers\n\nLiability is presumed: the owner does not have to prove fault. It covers damage of a certain seriousness, meaning damage that endangers the strength of the building or makes it unfit for its intended use. A collapsed wall would qualify; visible cracking or discolouration alone would not. Only hidden defects, those not observable at acceptance, can support a claim. Acceptance may be formal or tacit, for example through payment or taking possession.\n\nThe rule is a matter of public order. It cannot be excluded by contract, and it passes to each later owner of the building.\n\n## Compulsory insurance\n\nThe 1978 law pairs liability with two insurance obligations:\n\n- **Builders' liability insurance** (*assurance de responsabilité obligatoire*, Insurance Code Article L 241-1): every builder, including roofing contractors, must be insured for decennial liability.\n- **Owner's damage insurance** (*assurance dommages-ouvrage*, Article L 242-1): the owner commissioning the work must take out insurance that pays for repairs quickly, after which that insurer recovers the cost from the builders' insurers.\n\nFailing to take out the required insurance can be punished by up to six months' imprisonment and a fine of up to EUR 75,000. On larger projects architects normally check contractors' insurance certificates, and notaries are expected to check the insurance position when a property with recent works is sold.\n\n## Relevance to roofing\n\nInsurers and courts refer to the NF DTU documents when judging whether roofing work follows accepted practice, and products or methods outside them are usually covered by a CSTB *Avis Technique*. The word \"décennale\" in a roofer's paperwork in France refers to this statutory liability and its insurance, not to a manufacturer's product warranty.\n\n## Sources and gaps\n\nDetails of the shorter French warranties that run alongside it, for completion defects and for equipment: published information is limited.","key_facts":[{"label":"Country","value":"France"},{"label":"Duration","value":"10 years from acceptance of the works"},{"label":"Legal basis","value":"Spinetta law (1978); Civil Code Art. 1792 et seq."},{"label":"Builder insurance","value":"Compulsory (Insurance Code L 241-1)"},{"label":"Owner insurance","value":"Dommages-ouvrage (L 242-1)"},{"label":"Penalty for no insurance","value":"Up to 6 months' prison and/or EUR 75,000 fine"}],"regions":["Europe"],"aliases":["decennial liability","responsabilité décennale","assurance décennale","ten-year liability","Spinetta law"],"related":["dtu-40-series","roofing-in-france","roofing-warranty-types","roof-insurance-claims"],"company":null,"sources":[{"title":"French construction law: make sure you are insured","url":"https://larevue.squirepattonboggs.com/french-construction-law-make-sure-you-are-insured_a1800.html","publisher":"Squire Patton Boggs"},{"title":"La garantie décennale","url":"https://www.magnolia.fr/garantie-decennale/lois/spinetta","publisher":"Magnolia.fr"},{"title":"Responsabilité civile décennale","url":"https://www.smabtp.fr/sma/upload/docs/application/pdf/2022-09/responsabilite_civile_decennale_v2_1021.pdf","publisher":"SMABTP"}],"country":null},{"slug":"gassho-zukuri","title":"Gassho-zukuri","type":"article","summary":"Steep thatched farmhouse roofs of Shirakawa-go and Gokayama, Japan, shaped to shed heavy snow; part of a UNESCO World Heritage site.","body":"Gassho-zukuri is a style of Japanese farmhouse with a very steep, thatched gable roof, found mainly in the mountain villages of Shirakawa-go (Gifu Prefecture) and Gokayama (Toyama Prefecture). The name is usually translated as \"prayer-hands construction\", because the two roof slopes meet at the top like palms pressed together. The Historic Villages of Shirakawa-go and Gokayama were inscribed as a UNESCO World Heritage site in 1995.\n\nThe style is a form of *kayabuki*, the general Japanese term for grass-thatched roofs, and represents one of its most dramatic regional versions.\n\n## Designed for snow\n\nThe villages sit in valleys that receive very heavy snowfall. The steep roof pitch lets snow slide off rather than build up, and the heavy timber structure is built to carry what does remain. In some villages, forests on the slopes above are protected because they help hold back snow from the houses.\n\n## Use of the roof space\n\nThe tall roof creates several attic levels. Historically these upper floors were used mainly for raising silkworms, which needed room for trays of larvae and for storing mulberry leaves. Space beneath the ground floor was used to produce nitre, an ingredient of gunpowder. The roof was therefore both shelter and workplace.\n\n## Rethatching and community labour\n\nA gassho-zukuri roof was traditionally rethatched about every 30 to 40 years. The work relies on *yui*, a system of unpaid mutual labour among households. Preparations begin years in advance, and a re-roofing day can involve 200 to 300 people. Men work on the roof while others prepare food, and one side of a roof is typically finished in about two days. Today volunteers and heritage organisations support the villages with this work.\n\n## Surviving houses\n\nAround the time of inscription, Ogimachi in Shirakawa-go had 59 gassho-style farmhouses, Ainokura in Gokayama had 23, and Suganuma had 9. Fire is the main threat to thatch, so all three village areas have elaborate fire-extinguishing systems and organised resident fire-fighting squads.\n\n## Place in Japanese roofing\n\nGassho-zukuri contrasts with the clay *kawara* tile roofs common in Japanese towns. It shows how rural builders used locally harvested grasses and timber to deal with a severe snow climate.","key_facts":[{"label":"Location","value":"Shirakawa-go and Gokayama, Japan"},{"label":"Meaning","value":"Prayer-hands construction"},{"label":"Rethatching interval","value":"About 30-40 years"},{"label":"UNESCO inscription","value":"1995"},{"label":"Climate driver","value":"Heavy snowfall"}],"regions":["East Asia"],"aliases":["Gassho-style house","Gassho zukuri","Kayabuki farmhouse"],"related":["kayabuki","roofing-in-japan","thatch","snow-load","japanese-kawara-tile"],"sources":[{"title":"Historic Villages of Shirakawa-go and Gokayama","url":"https://en.wikipedia.org/wiki/Shirakawa-go","publisher":"Wikipedia"},{"title":"Historic Villages of Shirakawa-go and Gokayama","url":"https://whc.unesco.org/en/list/734","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing","country":null},{"slug":"ger-roof","title":"Ger Roof","category":"world-roofing","type":"term","summary":"The ger roof is the domed roof of the Mongolian yurt: straight uni poles rising to a wooden toono crown ring, covered with layers of felt and canvas.","body":"The roof of the Mongolian *ger* (yurt) is a lightweight, portable structure of timber poles and felt that can be dismantled, moved and re-erected. Its design, refined over more than two millennia on the Central Asian steppe, combines a compression ring at the top, straight radiating poles and insulating felt.\n\n## Parts of the roof\n\n- **Toono** - the wooden crown ring at the apex. It works as a compression ring for the roof poles, admits daylight and lets smoke escape from the central stove. In the Mongolian ger it is supported by one or more columns. Older crowns of the *sarkhinag* type gave way to the *khorlo toono*, shaped like the Buddhist dharma wheel.\n- **Uni** - the roof poles, which run from the top of the lattice wall to the crown. In the Mongolian ger they are straight, unlike the bent poles of some other Central Asian yurts.\n- **Khana** - the expanding lattice wall sections on which the poles rest.\n- **Ropes or bands** - tie the frame together around the wall head.\n\n## Covering\n\nThe frame is covered with pieces of felt. Depending on what is available, the felt is covered by canvas and, in summer, by sun covers. A thin undercover is laid on the roof slopes first and an outer cover goes on last. The whole structure is kept in compression by the weight of the covers, sometimes supplemented by a heavy weight hung from the centre of the roof.\n\n## Performance\n\nThe ger roof is light and portable, and the felt layers provide insulation against the steppe winter. Because the structure is light and flexible, gers have very low vulnerability to earthquakes.\n\n## History\n\nYurt-type tents have been used in Central Asia for at least 2,500 years, and the earliest written description is usually traced to Herodotus' account of the Scythians. During the 13th-century Mongol Empire the dwelling spread to parts of Europe and the Middle East. Its names in Manchu (*monggo boo*) and Chinese (*menggu bao*, 蒙古包) mean \"Mongol house\".\n\n## Use today\n\nGers remain the main dwelling of rural households in Mongolia and are common in the ger districts of Ulaanbaatar. Modern gers are typically described as wooden frames with durable, waterproof covering sheets.","key_facts":[{"label":"Crown ring","value":"Toono"},{"label":"Roof poles","value":"Uni (straight in Mongolia)"},{"label":"Wall","value":"Khana lattice"},{"label":"Covering","value":"Wool felt, canvas, sun cover"},{"label":"History","value":"At least 2,500 years on the steppe"}],"regions":["East Asia"],"aliases":["yurt roof","toono","uni poles","Mongolian ger"],"related":["roofing-in-mongolia","conical-roof","dome","prehistoric-shelters-and-early-thatch"],"company":null,"sources":[{"title":"Yurt","url":"https://en.wikipedia.org/wiki/Yurt","publisher":"Wikipedia"},{"title":"Construction practices: Mongolia (North Asia exposure model)","url":"https://docs.openquake.org/global_risk_model/north_asia/exposure/construction_practices.html","publisher":"Global Earthquake Model Foundation (OpenQuake)"},{"title":"Yurt (encyclopedic entry)","url":"https://www.nationalgeographic.org/encyclopedia/yurt/","publisher":"National Geographic Society"}],"country":null},{"slug":"zvdh","title":"German Roofers' Association (ZVDH)","summary":"The ZVDH is the national federation of Germany's roofing trade, founded in 1949 and based in Cologne, representing about 6,700 roofing firms.","body":"The Zentralverband des Deutschen Dachdeckerhandwerks (ZVDH), the Central Association of the German Roofing Trade, is the national umbrella organisation for roofers in Germany. It was founded on 2 April 1949 in Marburg an der Lahn and is headquartered in Cologne. Its website is dachdecker.de.\n\n## Structure\n\nGerman skilled trades (Handwerk) are organised in a system of guilds (Innungen) and chambers of crafts. The ZVDH sits at the top of the roofing trade's structure:\n\n- its direct members are 16 state-level roofing associations (Landesverbände and Landesinnungsverbände), whose names vary by region;\n- these in turn include local roofing guilds;\n- together they represent about 6,700 member companies (2024 figure), with combined annual turnover of roughly €10 billion.\n\n## Technical rules\n\nThe ZVDH issues the technical rules of the German roofing trade (often called the Fachregeln or the Regelwerk des Deutschen Dachdeckerhandwerks). These rules cover pitched roofs with slate, tile and metal, flat roof waterproofing, exterior wall cladding and roof drainage. They are widely treated in Germany as the recognised rules of good practice, and they are used in contracts and by expert witnesses when roofing disputes arise.\n\n## Training\n\nRoofer (Dachdecker) is a regulated craft in Germany. Training usually follows the dual system: apprentices work in a company and attend vocational school, over about three years. The master craftsman qualification (Meister) is traditionally required to run a roofing business. The ZVDH supports training, competitions and recruitment for the trade.\n\n## Publications and events\n\nThe ZVDH co-publishes the trade journal *DDH – Das Dachdecker-Handwerk*, which covers roofing, wall and waterproofing technology.\n\n## International role\n\nThe International Federation for the Roofing Trade (IFD), the global umbrella body for national roofing associations, is also based in Germany. Roofing in German-speaking Europe is showcased at trade fairs such as DACH+HOLZ International.","key_facts":[{"label":"Founded","value":"2 April 1949, Marburg"},{"label":"Headquarters","value":"Cologne, Germany"},{"label":"Member companies","value":"About 6,700 (2024)"},{"label":"Direct members","value":"16 state-level roofing associations"}],"regions":["Europe"],"aliases":["ZVDH","Zentralverband des Deutschen Dachdeckerhandwerks","Central Association of the German Roofing Trade"],"related":["dach-holz-international","international-federation-for-the-roofing-trade","fll","roofing-apprenticeship"],"company":{"founded":"1949","headquarters":"Cologne, Germany","website":"https://www.dachdecker.de","known_for":["Technical rules of the German roofing trade","DDH trade journal"]},"sources":[{"title":"Zentralverband des Deutschen Dachdeckerhandwerks","url":"https://de.wikipedia.org/wiki/Zentralverband_des_Deutschen_Dachdeckerhandwerks","publisher":"Wikipedia (German)"},{"title":"DACH+HOLZ International","url":"https://www.dach-holz.com/","publisher":"GHM"}],"category":"organizations","type":"organization","country":null},{"slug":"german-roofing-slate","title":"German Roofing Slate","category":"materials","type":"term","summary":"Roofing slate from Germany's Mosel, Hunsrück, Sauerland and Thuringian deposits, added to the IUGS heritage stone list in 2024.","body":"**German roofing slate** (*Dachschiefer*) comes from several deposits in the central uplands of Germany. It has been used on roofs and walls since Roman times and gives towns of the Mosel, Hunsrück, Eifel, Sauerland and Thuringia their dark, finely patterned roofs. Production has shrunk to a handful of mines, but German slate was recognised as a heritage stone by the International Union of Geological Sciences (IUGS) in 2024.\n\n## Regions\n\n- **Mosel slate** (*Moselschiefer*), from the area of Mayen, Polch, Müllenbach and Trier. Historically it was the largest German source, with more than half of West German output. Only the Katzenberg and Margareta mines in Mayen may still use the name Moselschiefer.\n- **Hunsrück slate**, from Altlay, Bundenbach, Kirn, Gemünden and Herrstein. The Altlay mine is still active and announced an open-pit phase in new deposits in 2020.\n- **Sauerland slate**, from Fredeburg, Brilon and Nuttlar, described as the largest known German deposit; a combined mine near Bad Fredeburg is active.\n- **Thuringian slate**, worked at sites including Unterloquitz, Schmiedebach and Tschirma. Nearby Steinach held a world monopoly on slate pencils until the 1960s.\n- **Bavaria**, where Lotharheiler slate is worked near Geroldsgrün.\n\n## History\n\nRoman builders on the Rhine and Mosel laid slate roofs to fixed rules, and the craft flourished in the Middle Ages. Slate was also made into writing tablets and slate pencils from the Middle Ages to the mid-20th century. In the early 1920s the national roofers' organisation and the slate industry negotiated a system of regional names for German slate, published on 7 August 1932 and reconfirmed in 1953 and 1967. Many mines closed in the 20th century, among them Wadrill in Saarland in 1953 and the roofing-slate mines of Kaub on the Rhine in 1972. Imported slate also has a long history in Germany: after the Hamburg fire of 1842, Germany became an important market for Welsh slate.\n\n## Characteristics and use\n\nGerman slating is known for its variety. Roofers work with around 250 formats, typically 4-6 mm (about 0.16-0.24 in) thick, and with methods such as the **Altdeutsche Deckung**, in which graded, shaped slates are laid in rising courses, and scale-shaped coverings. Slate is used for wall cladding as well as roofs. The Fell Exhibition Slate Mine near Trier presents the history of Mosel slate mining.\n\n## Market\n\nSpain is the largest producer of roofing slate in Europe, supplying about 90% of the continent's natural roofing slate, and imported slate is widely used in Germany alongside the remaining domestic production.\n\n## Sources and gaps\n\nCurrent German production volumes and import shares: published information is limited.","key_facts":[{"label":"Main regions","value":"Mosel, Hunsrück, Sauerland, Thuringia"},{"label":"Historic leader","value":"Moselschiefer (over half of West German output)"},{"label":"Naming scheme published","value":"7 August 1932"},{"label":"Typical thickness","value":"4-6 mm (0.16-0.24 in)"},{"label":"Heritage stone","value":"IUGS list, 2024"}],"regions":["Europe"],"aliases":["Dachschiefer","Moselschiefer","German slate"],"related":["natural-slate","altdeutsche-deckung","roofing-in-germany","welsh-slate","spanish-slate","ardennes-slate"],"company":null,"sources":[{"title":"Dachschiefer","url":"https://de.wikipedia.org/wiki/Dachschiefer","publisher":"Wikipedia (German)"},{"title":"Slate industry","url":"https://en.wikipedia.org/wiki/Slate_industry","publisher":"Wikipedia"},{"title":"Altdeutsche Deckung","url":"https://de.wikipedia.org/wiki/Altdeutsche_Deckung","publisher":"Wikipedia (German)"},{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"}],"country":null},{"slug":"glazed-roof-tile","title":"Glazed Roof Tile","type":"term","summary":"A clay roof tile coated with a glassy glaze before firing, giving a glossy, coloured surface; prominent in East Asian and some European architecture.","body":"A glazed roof tile is a clay tile whose exposed surface has been coated with a glaze, a thin layer of glass-forming minerals and colouring oxides that melts in the kiln into a glossy, hard skin. Glazed tiles offer strong, lasting colours such as green, yellow, blue and black, and a surface that sheds dirt and organic growth more easily than unglazed clay.\n\n## History\n\nColoured gloss glazes for roof tiles were developed to a high level in China, and the Song-dynasty building manual *Yingzao Fashi* standardised their manufacture. Imperial yellow glazed tiles became the mark of palaces such as the Forbidden City in Beijing. In Korea, the Goryeo dynasty invented celadon glazes, used on the roofs of upper-class buildings. In Europe, glazed tiles laid in coloured patterns are a feature of buildings in central Europe and Burgundy.\n\n## Glaze versus engobe\n\nMany modern clay tiles use an **engobe** instead of a full glaze. An engobe is a thin coating of liquid clay, sometimes coloured, applied before firing. It gives a matte or satin finish and consistent colour. A **glaze** gives a glossy, glass-like finish. Both resist fading because the colour is fired in, unlike the surface paint or slurry used on many concrete tiles.\n\n## Glazing and water resistance\n\nA common misconception is that glazing waterproofs a tile. In fact, glazing a porous clay tile does not make it watertight: moisture can still enter through unglazed backs and edges, and if the clay body itself is weak or porous, water trapped under the glaze can freeze and cause the glaze to flake. Durable glazed tiles therefore rely on a well-fired, low-absorption clay body; architectural ceramics intended for freezing climates are fired to or near vitrification.\n\n## Unglazed alternative\n\nUnglazed (natural) clay tiles, often called terracotta, take their colour entirely from the clay and its firing. They weather and develop a patina over time, which many people value on traditional buildings.\n","key_facts":[{"label":"Finish","value":"Glossy, fired-on glass layer"},{"label":"Historic centres","value":"China (Song-dynasty standards), Korea (Goryeo celadon)"},{"label":"Alternative","value":"Engobe (matte clay slip) or unglazed terracotta"}],"regions":["East Asia","Europe","Global"],"aliases":["glazed tile","glazed clay tile","ceramic glazed roof tile"],"related":["clay-roof-tile","terracotta","interlocking-clay-tile"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Terracotta","url":"https://en.wikipedia.org/wiki/Terracotta","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"spread-of-corrugated-iron","title":"Global Spread of Corrugated Iron","category":"history","type":"article","summary":"How corrugated galvanised iron travelled from Britain to colonial Australia, Africa, the Americas and Asia, becoming one of the world's most common roofs.","body":"After its invention in London in 1829 and the expiry of the original patent in 1843, corrugated galvanised iron (CGI) became one of the most widely used roofing materials in the world. It was light, strong, easy to ship flat, simple to fix with basic tools and fireproof. These qualities made it the material of frontiers, colonies, mining camps and, later, informal settlements.\n\n## Prefabricated buildings for export\n\nBy the 1840s British firms were making fully prefabricated iron buildings, many shipped to colonies, notably Australia and South Africa. In 1845 an \"iron palace\" made in Liverpool for export to Africa was put on public display before shipment. Firms supplied iron churches, chapels and schools in large numbers; in Britain these became known as \"tin tabernacles\". Some bishops are said to have refused to consecrate iron churches.\n\n## Settler countries\n\nCGI became common in rural areas of the United States, Argentina, Spain, New Zealand and Australia, and later India. In Australia and Argentina it remains a common roof even in cities. Australians call the classic profile \"custom orb\" or \"corro\".\n\n## Africa, the Caribbean and the tropics\n\nCGI also became a familiar roof across Africa, the Caribbean and India. Local names reflect how familiar it became: in Nigeria and Cyprus it is often simply called \"zinc\", and in Caribbean English \"pailing\". Today it is widely used in informal settlements in Africa and elsewhere.\n\n## War and status\n\nIn Britain CGI replaced thatch on many rural buildings between the late 19th and early 20th centuries. The First World War Nissen hut, named after Captain Peter Nissen, and the Second World War Anderson shelter, of which at least 1.5 million were distributed, gave it a utilitarian, temporary image. Mid-20th-century architects later used it deliberately for its industrial character.\n\n## Modern successors\n\nPlain galvanised sheet is gradually giving way to steel coated with a 55% aluminium-zinc alloy and to pre-painted sheet with more complex profiles, but traditional corrugated sheets are still produced worldwide.","key_facts":[{"label":"Prefabricated exports","value":"From the 1840s"},{"label":"Anderson shelters (UK, WWII)","value":"At least 1.5 million"},{"label":"Regional names","value":"Zinc (Nigeria, Cyprus); pailing (Caribbean); custom orb (Australia)"}],"regions":["Global","Oceania","Africa","Latin America","South Asia"],"aliases":["CGI history","tin roof history","colonial iron buildings"],"related":["invention-of-corrugated-iron","corrugated-iron"],"company":null,"sources":[{"title":"Corrugated Iron Architecture","url":"https://buildingconservation.com/articles/corrugated-iron-architecture/corrugated-iron-architecture.htm","publisher":"The Building Conservation Directory"},{"title":"Corrugated galvanised iron","url":"https://en.wikipedia.org/wiki/Corrugated_galvanised_iron","publisher":"Wikipedia"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"}],"country":null},{"slug":"gonjong-roof","title":"Gonjong Roof (Minangkabau)","category":"roof-forms","type":"term","summary":"Gonjong are the upswept, horn-like roof peaks of the Minangkabau rumah gadang in West Sumatra, Indonesia, said to recall buffalo horns.","body":"The gonjong is the curved, horn-like roof form of the rumah gadang, the traditional great house of the Minangkabau people of West Sumatra, Indonesia. The roof rises in tiers of upswept gables whose ridge ends sweep up into sharp points, creating one of the most distinctive silhouettes in world architecture.\n\n## Meaning\n\nThe pointed peaks are commonly said to resemble the horns of a water buffalo, an allusion to a legend of a contest between two buffaloes from which the name Minangkabau is thought to derive. The upward-reaching peaks are also described as symbolising reaching toward God. Within the matrilineal Minangkabau tradition, the number of horn-like extensions is said to reflect the number of married daughters in the house, and they are not always arranged symmetrically.\n\n## Materials\n\nTraditionally the roof is thatched with ijuk, black fibre from the sugar palm, laid in bundles shaped to the curved, multi-gabled form; the finials are bound thatch with decorative metal. Contemporary houses more often use corrugated metal sheeting instead of thatch.\n\n## Cultural significance\n\nThe gonjong has become a symbol of West Sumatra and of Minangkabau identity. It appears on government offices, hotels, the facades of Padang restaurants throughout Indonesia, and the terminal of Minangkabau International Airport.\n\n## Related forms\n\nUpswept, saddle-shaped or horned roofs are found in several building traditions across Indonesia and Southeast Asia.\n\n## Maintenance\n\nThe steep, curved thatch sheds the heavy tropical rain of the region quickly, but palm-fibre thatch must be renewed periodically, and the sharply curved ridges and finials are the most exposed parts of the roof. Replacing thatch with metal sheeting reduces maintenance but changes the appearance and the acoustic and thermal qualities of the interior.","key_facts":[{"label":"Region","value":"West Sumatra, Indonesia"},{"label":"Traditional covering","value":"Ijuk (sugar palm fibre) thatch"},{"label":"Symbolism","value":"Buffalo horns"}],"regions":["Southeast Asia"],"aliases":["gonjong","rumah gadang roof","Minangkabau roof","horn roof"],"related":["pagoda-roof","irimoya","saltbox-roof"],"company":null,"sources":[{"title":"Rumah gadang","url":"https://en.wikipedia.org/wiki/Rumah_Gadang","publisher":"Wikipedia"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"}],"country":null},{"slug":"granule-loss","title":"Granule Loss","category":"problems-maintenance","type":"term","summary":"The shedding of the mineral granules that coat asphalt shingles; normal in small amounts, a warning sign when heavy, patchy or premature.","body":"Granule loss is the detachment of the ceramic-coated mineral granules embedded in the top surface of asphalt shingles and mineral-surfaced roll roofing. The granules give colour, shield the asphalt from ultraviolet light and add fire and impact resistance. Once they are gone, the exposed asphalt dries, cracks and erodes faster.\n\nSome granule shedding is expected. New shingles carry loose surplus granules that come off in packaging, handling and installation, so a light layer in the gutters of a recently installed roof is common. Over the life of the roof, weathering slowly weakens the bond between granules and asphalt, and rain carries granules away.\n\n## Causes\n\n- **Normal ageing and weathering**, usually fairly uniform across a slope; sun-facing slopes tend to wear first.\n- **Hail**, which can knock granules off in random spots and, on older roofs, loosen them even with small stones.\n- **Blistering**, where the blister caps erode and leave pits.\n- **Foot traffic and scuffing**, often along a line where people walk, or at high points.\n- **Manufacturing variation** or flaking from defects in the asphalt or mat.\n- **Mechanical cleaning** such as pressure washing.\n- **Concentrated water flow** from downspouts that discharge onto a lower roof.\n\n## How it is assessed\n\nInspectors look at the pattern. Uniform, gradual loss across a slope generally indicates age. Random, circular spots of missing granules, sometimes with a soft bruise underneath, suggest hail. Linear wear points to traffic. Deep granule sediment in gutters on a fairly new roof can indicate a product or installation issue worth reporting to the manufacturer. Insurers generally treat long-term, uniform granule loss as wear rather than storm damage.\n\n## What to do\n\nGranule loss itself is not repaired; shingles that have lost much of their surface are replaced. Owners can reduce avoidable loss by limiting foot traffic, avoiding high-pressure washing, and fitting downspout extensions or splash diverters where upper roofs drain onto lower ones.","key_facts":[{"label":"Applies to","value":"Asphalt shingles and mineral-surfaced roll roofing"},{"label":"Normal on new roofs","value":"Light loss of surplus granules"},{"label":"Warning signs","value":"Bald patches, exposed asphalt, deep gutter sediment"}],"regions":["Global"],"aliases":["shingle granule loss","bald shingles"],"related":["asphalt-shingle","hail-damage","roof-blistering","roof-cleaning","roof-age-estimation"],"company":null,"sources":[{"title":"Mastering Roof Inspections: Asphalt Composition Shingles, Part 34","url":"https://www.nachi.org/asphalt-comp-shingles-part34-88.htm","publisher":"InterNACHI"},{"title":"Loss of mineral granules from asphalt shingle or roll roofing roofs","url":"https://inspectapedia.com/roof/Asphalt_Shingle_Granule_Loss.php","publisher":"InspectAPedia"},{"title":"Is It Hail Damage?","url":"https://ibhs.org/is-it-hail-damage/","publisher":"Insurance Institute for Business & Home Safety"}],"country":null},{"slug":"gravel-surfaced-roof","title":"Gravel-Surfaced Roof (Flood Coat and Gravel)","category":"low-slope-systems","type":"term","summary":"A built-up roof finish in which loose aggregate is embedded in a thick top pour of hot bitumen to shield the membrane from sun, hail and traffic.","body":"A gravel-surfaced roof is the classic \"tar and gravel\" finish on built-up roofing. After the last ply is laid, the roofer pours a heavier layer of hot asphalt or coal-tar pitch, called the flood coat, and immediately broadcasts gravel or slag into it so the aggregate sticks.\n\n## Purpose\n\n- **UV protection:** bitumen hardens and cracks in sunlight; the aggregate shades it.\n- **Mechanical protection:** gravel takes the wear from hail, foot traffic and debris.\n- **Wind:** the embedded aggregate helps the surface resist uplift.\n- **Weight:** gravel surfacing typically adds about 15 to 20 kg/m2 (3 to 4 lb/sq ft).\n\n## Edges and gravel stops\n\nAt roof edges, sheet-metal gravel stops hold the aggregate in place. These edges are a known weak point: felts stripped in over gravel stops often split because they cannot absorb the movement of the metal, and modified bitumen strip-in membranes are often used instead.\n\n## Problems\n\nLoose gravel can be moved by wind, water flow or foot traffic, leaving bare bitumen that then cracks or blisters. Wind scour at corners and perimeters is very common. Gravel also hides the membrane, making leaks harder to trace, and must be removed for repairs or reroofing.\n\n## Cool-roof variants\n\nWhere reflectivity matters, light-coloured aggregate such as marble chips or grey slag can replace dark gravel, or a reflective coating or cap sheet can be used instead of a flood coat.\n\n## Related systems\n\nLoose aggregate is also used as ballast on single-ply and inverted roofs, but there the stones are loose-laid on top rather than embedded in bitumen. Spray polyurethane foam can also be protected with aggregate, which adds about 49 kg/m2 (10 lb/sq ft).","key_facts":[{"label":"Typical added weight","value":"15-20 kg/m2 (3-4 lb/sq ft)"},{"label":"Common aggregates","value":"Gravel, slag, marble chips"},{"label":"Weak points","value":"Gravel stops, wind scour at corners"}],"regions":["North America","Global"],"aliases":["tar and gravel","flood coat","gravel surfacing","aggregate surfacing"],"related":["built-up-roofing","coal-tar-pitch-roofing","ballasted-roof-system","cool-roof"],"company":null,"sources":[{"title":"Built-Up Roofing (BUR): What It Is, Types, Issues & More","url":"https://roofonline.com/built-up-roofing-introduction/","publisher":"RoofOnline"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"Rules for long-lasting BUR systems (H. H. Pierce, Interface, Oct 2006)","url":"https://iibec.org/wp-content/uploads/2006-10-Pierce.pdf","publisher":"IIBEC"},{"title":"Cool Roofs","url":"https://www.energy.gov/energysaver/cool-roofs","publisher":"U.S. Department of Energy"}],"country":null},{"slug":"great-boston-fire-of-1872","title":"Great Boston Fire of 1872","category":"history","type":"event","summary":"A fire on 9-10 November 1872 that spread across wooden mansard roofs and destroyed 776 buildings in downtown Boston.","body":"The **Great Boston Fire** began at about 7:20 p.m. on **9 November 1872** in the basement of a warehouse at 83-87 Summer Street and was contained around midday on 10 November. It destroyed 776 buildings across about 26 ha (65 acres) of downtown Boston, including much of the financial district. It is one of the best-known examples of roofs helping a fire to spread.\n\n## The role of mansard roofs\n\nThe Second Empire style, with the mansard roof as its central feature, was popular in the United States and Canada between about 1865 and 1900; Boston's Old City Hall (1862-1865) is an example. Many Boston commercial buildings had brick or stone walls but wooden framing and timber-built mansard roofs. The first warehouse's wooden mansard caught fire, and flames passed from rooftop to rooftop along the street. Combustible roofs above masonry walls allowed fire to travel across the district.\n\n## Conditions in Boston\n\nBoston had no strictly enforced building code in 1872. Its fire service had installed the world's first telegraph-based fire alarm boxes in 1852, but this could not offset combustible construction. The fire came only a year after the Great Chicago Fire of 1871.\n\n## Aftermath\n\n- **1873:** Boston fire chief John Damrell founded the National Association of Fire Engineers, which identified flammable materials and excessive building height among key fire-safety concerns.\n- **1874:** Damrell resigned as chief engineer, and Boston began replacing its water mains.\n- **1877:** Damrell became Boston's building commissioner.\n- **1884:** he petitioned for a more formal building code.\n- **1892:** Boston set formal limits on building height and area, then unique among American cities.\n- **1905:** the National Board of Fire Underwriters published the first standardised US National Building Code.\n\n## Lessons for roofing\n\nThe fire showed that a roof is part of a building's fire defence. Combustible roof structures on otherwise masonry buildings let fire travel across a city. The code reforms that followed in Boston, and the national building code of 1905, reflected this lesson.","key_facts":[{"label":"Date","value":"9-10 November 1872"},{"label":"Buildings destroyed","value":"776"},{"label":"Area burned","value":"About 26 ha (65 acres)"},{"label":"Roof factor","value":"Wooden mansard roofs"}],"regions":["North America"],"aliases":["Boston fire 1872","Great Boston Fire"],"related":["mansard-roof-history","history-of-roofing-fire-regulations","great-fire-of-london"],"company":null,"sources":[{"title":"Great Boston fire of 1872","url":"https://en.wikipedia.org/wiki/Great_Boston_fire_of_1872","publisher":"Wikipedia"},{"title":"Second Empire architecture in the United States and Canada","url":"https://en.wikipedia.org/wiki/Second_Empire_architecture_in_the_United_States_and_Canada","publisher":"Wikipedia"}],"country":null},{"slug":"great-fire-of-london","title":"Great Fire of London (1666)","category":"history","type":"event","summary":"The fire of 2-5 September 1666 destroyed about 13,200 houses; the rebuilding laws that followed banned exterior timber and favoured brick, stone and tile.","body":"The **Great Fire of London** began shortly after midnight on Sunday **2 September 1666** at Thomas Farriner's bakery in Pudding Lane and burned until **5 September**, although some fires smouldered for weeks. It destroyed an estimated 13,200-13,500 houses, 86 or 87 parish churches, 44 livery company halls and the medieval St Paul's Cathedral. It is a landmark in the history of building and roofing regulation.\n\n## Why it spread\n\nLondon was densely built of timber, with overhanging upper storeys and many cheap roofs. Building in wood and roofing in thatch had been prohibited for centuries, notably after a major fire in 1212, but the rules were widely ignored because the materials were cheap. Wind-blown sparks and burning flakes landed on thatched roofs and set them alight, and wooden gutters also caught fire, so the blaze jumped from roof to roof.\n\n## The rebuilding rules\n\nParliament passed the **Rebuilding of London Act 1666**, which received royal assent on 8 February 1667. Among its provisions:\n\n- wood was banned from the exterior of buildings;\n- brick and stone were preferred as building materials;\n- jetties and similar overhangs were banned;\n- the cost of building materials and workers' wages was regulated;\n- a duty on coal helped fund civic rebuilding.\n\nA separate Fire of London Disputes Act set up a court to settle disputes over buildings destroyed by the fire. Further regulations followed in 1667 and in a second rebuilding act of 1670.\n\n## Effect on roofs\n\nRebuilding favoured brick and stone over timber, which made the new city far less vulnerable to fire spreading from building to building. The fire had shown how exposed thatch and wooden gutters were to wind-blown sparks, and the act is widely treated as a landmark in fire-safety building regulation.\n\n## Rebuilding\n\nChristopher Wren, Robert Hooke, John Evelyn and others proposed new street plans that were never adopted. Wren designed about 51 new churches, the new St Paul's Cathedral with its great dome, and, with Hooke, the Monument to the fire, built 1671-1676.","key_facts":[{"label":"Dates","value":"2-5 September 1666"},{"label":"Houses destroyed","value":"About 13,200-13,500"},{"label":"Rebuilding Act royal assent","value":"8 February 1667"},{"label":"Key rule","value":"No wood on building exteriors"}],"regions":["Europe"],"aliases":["Fire of London 1666"],"related":["history-of-roofing-fire-regulations","history-of-thatch-in-britain","st-pauls-cathedral-dome","great-boston-fire-of-1872"],"company":null,"sources":[{"title":"Great Fire of London","url":"https://en.wikipedia.org/wiki/Great_Fire_of_London","publisher":"Wikipedia"},{"title":"Rebuilding of London Act 1666","url":"https://en.wikipedia.org/wiki/Rebuilding_of_London_Act_1666","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"}],"country":null},{"slug":"great-zimbabwe","title":"Great Zimbabwe","category":"world-roofing","type":"place","summary":"Medieval stone-walled capital in Zimbabwe (c. 1100-1450) whose people lived in daga huts inside and around dry-stone enclosures; UNESCO site since 1986.","body":"Great Zimbabwe is the ruined capital of a southern African state that flourished between about 1100 and 1450 CE, near present-day Masvingo in Zimbabwe. It is famous for its mortarless granite walls, but the walls were enclosures, not roofed buildings: people lived in huts of daga (earth) built inside and around them. The site gave the modern country its name, from a Shona word usually translated as \"house of stone\".\n\n## Site and dates\n\nStone building began in the 11th century and continued for more than 300 years. The Hill Complex was occupied from the 11th to 13th centuries, the Great Enclosure from the 13th to 15th, and the Valley Complex from the 14th to 16th. The capital was abandoned around 1450, probably because of food shortages and deforestation. The property covers almost 800 ha (about 1,980 acres), of which the city occupies nearly 80 ha (about 200 acres). Population estimates vary: older figures suggest up to 18,000-20,000 people at its peak, while a more recent study suggests no more than 10,000. Earlier farming communities of the Gokomere or Ziwa cultures occupied the valley from around the 4th century but built no stone structures.\n\n## Daga huts\n\nUNESCO describes the Great Enclosure, built in the 14th century of cut granite blocks laid in regular courses, as containing a series of daga-hut living quarters. Daga bricks were made from granitic sand mixed with clay, and huts were built within the stone walls, which insulated each group of dwellings. A family area typically had a kitchen, two living huts and a court. In the Valley Ruins, living areas include daga huts, floors, benches and basins.\n\nMost of the population lived outside the walls in houses of mud on timber frames. Over the 13th century the ruling group shifted to houses of thick daga rather than daga and poles, and used stone walls to screen themselves from view.\n\n## Roofs\n\nPublished descriptions of the site do not record the roofs of its huts directly, since none survive. Village huts in the region were traditionally built of clay and sticks with conical thatched roofs, and rural homesteads in Zimbabwe still use mud walls under thatch, a pattern often linked to the dwellings of Great Zimbabwe.\n\n## Walls\n\nThe Great Enclosure walls stand up to 11 m (36 ft) high and are built without mortar. Inside is the Conical Tower, 5.5 m (18 ft) in diameter and 9 m (30 ft) high. The Hill Ruins use rougher granite rubble, with narrow, partly covered passageways between enclosures. The Valley Ruins show chevron and chequered decoration.\n\n## Protection\n\nThe site has been legally protected since 1893 and was inscribed on the World Heritage List in 1986. Its conical tower has been echoed in modern buildings such as the Reserve Bank of Zimbabwe (1996).","key_facts":[{"label":"Location","value":"Near Masvingo, Zimbabwe"},{"label":"Period","value":"C. 1100-1450 CE"},{"label":"Dwellings","value":"Daga (sand and clay) huts"},{"label":"Area","value":"Almost 800 ha (1,980 acres)"},{"label":"UNESCO inscription","value":"1986"}],"regions":["Africa"],"aliases":["Great Zimbabwe National Monument","Great Zimbabwe ruins"],"related":["roofing-in-zimbabwe","conical-roof","thatch","rondavel","roofing-in-southern-africa"],"company":null,"sources":[{"title":"Great Zimbabwe National Monument","url":"https://whc.unesco.org/en/list/364/","publisher":"UNESCO World Heritage Centre"},{"title":"Great Zimbabwe","url":"https://en.wikipedia.org/wiki/Great_Zimbabwe","publisher":"Wikipedia"},{"title":"Architecture of Zimbabwe","url":"https://en.wikipedia.org/wiki/Architecture_of_Zimbabwe","publisher":"Wikipedia"}],"country":null},{"slug":"green-roof","title":"Green Roof","type":"article","summary":"A roof partly or fully covered with vegetation and growing medium over a waterproofing membrane, used for stormwater, cooling and habitat.","body":"A green roof (also called a vegetated, living or eco-roof) is a roof covered wholly or partly with plants growing in a layer of substrate placed over waterproofing. A typical build-up includes a waterproof membrane, a root barrier, a drainage layer, a filter fabric, growing medium and vegetation. Modern green roof technology was developed in Germany in the 1960s and spread as cities sought ways to manage stormwater.\n\n## Types\n\n- **Extensive:** shallow substrate, roughly 2-13 cm (1-5 in) deep, planted with hardy species such as sedums and grasses. Saturated weight is roughly 50-120 kg/m² (10-25 lb/ft²). They need little maintenance and are the most common type on existing buildings.\n- **Intensive:** deeper substrate of about 13 cm (5 in) or more, supporting shrubs and small trees, with weights of roughly 390-730 kg/m² (80-150 lb/ft²). They often function as accessible roof gardens and need regular maintenance and stronger structures.\n- **Semi-intensive:** an intermediate category used in some guidelines.\n\n## Stormwater\n\nGreen roofs retain part of the rain that falls on them and slow the rest. The US EPA reports that extensive and intensive green roofs can reduce runoff by about 60 percent and up to 100 percent respectively, with best performance in small storms. A US General Services Administration review found reductions in peak runoff rates of up to 65 percent and delays in runoff of up to three hours; extensive roofs typically hold the first 13-19 mm (0.5-0.75 in) of rain.\n\n## Temperature and energy\n\nAccording to the EPA, green roof surfaces can be up to 31 °C (56 °F) cooler than conventional roofs, and they can reduce heat flow through the roof substantially. They also help reduce urban heat islands through evapotranspiration.\n\n## Membrane life\n\nBecause plants and substrate shield the waterproofing from UV and temperature extremes, the GSA review estimated a life expectancy of about 40 years for a green roof membrane versus about 17 years for a conventional roof.\n\n## Biodiversity\n\nGreen roofs can host insects, birds, bees and butterflies, even on tall buildings. Habitat value depends mainly on plant type, substrate depth and variation in structure; some cities, notably Basel, require native soils and plant mixes to support local species.\n\n## Costs and considerations\n\nGreen roofs cost more to install than conventional roofs and require structural capacity, careful waterproofing and leak detection, and ongoing maintenance such as weeding and, in some climates, irrigation. Savings from stormwater fees, energy and longer membrane life can offset part of the cost. Policies in cities such as Toronto, Copenhagen, Basel, Paris and Singapore have encouraged or required them.","key_facts":[{"label":"Origin of modern systems","value":"Germany, 1960s"},{"label":"Extensive depth / weight","value":"About 2-13 cm; 50-120 kg/m²"},{"label":"Intensive weight","value":"About 390-730 kg/m²"},{"label":"Runoff reduction (EPA)","value":"About 60% extensive, up to 100% intensive"},{"label":"Membrane life (GSA estimate)","value":"About 40 years vs 17 for conventional"}],"regions":["Global","Europe","North America","East Asia","Southeast Asia"],"aliases":["vegetated roof","living roof","eco-roof","roof garden","extensive green roof","intensive green roof","vegetative roof","sedum roof"],"related":["blue-roof","toronto-green-roof-bylaw","basel-green-roof-policy","copenhagen-green-roof-policy","french-green-roof-law","singapore-skyrise-greenery","green-roofs-in-germany","urban-heat-island","protected-membrane-roof","xps-insulation","pib-roofing-membrane","roof-deck"],"sources":[{"title":"Using Green Roofs to Reduce Heat Islands","url":"https://www.epa.gov/heatislands/using-green-roofs-reduce-heat-islands","publisher":"US Environmental Protection Agency"},{"title":"The Benefits and Challenges of Green Roofs on Public and Commercial Buildings","url":"https://www.gsa.gov/system/files/The_Benefits_and_Challenges_of_Green_Roofs_on_Public_and_Commercial_Buildings.pdf","publisher":"US General Services Administration"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"},{"title":"Rhepanol hfk brochure","url":"https://produktinfo.blauer-engel.de/uploads/pdf_uploads/25837_DOS_FDT_Broschuere_Rhepanol-hfk_A4_ENG_WEB_en.pdf","publisher":"FDT FlachDach Technologie / Blauer Engel"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"green-roofs-for-healthy-cities","title":"Green Roofs for Healthy Cities (GRHC)","summary":"Green Roofs for Healthy Cities is North America's industry association for green roofs and green walls, active since 1999.","body":"Green Roofs for Healthy Cities (GRHC) is a non-profit industry association for green roofs and green walls in North America. It describes itself as having worked to grow the green roof and wall industry since 1999. Its website is greenroofs.org.\n\nMembers include designers, landscape architects, roofing contractors, growers, manufacturers of green roof components, researchers and policy makers.\n\n## Activities\n\n- **Green Roof Professional (GRP) accreditation.** GRHC created and manages the GRP credential, which covers the design, installation and maintenance of green roofs. Training for the credential is offered as a self-paced online course through its Living Architecture Academy.\n- **CitiesAlive conference.** GRHC organises CitiesAlive, an annual conference on green roofs, walls and urban green infrastructure.\n- **Awards.** It runs the Green Roof & Wall Awards of Excellence for outstanding projects, people and organisations.\n- **Policy.** It promotes municipal policies that encourage or require green roofs, such as incentive programs and green roof bylaws in North American cities.\n\n## What a green roof is\n\nA green (vegetated) roof is a roof covered with a growing medium and plants, placed over a waterproofing membrane and root barrier. Main types are:\n\n- **Extensive** green roofs, with a thin, lightweight growing layer, often 50-150 mm (2-6 in), planted with hardy sedums and grasses and needing little maintenance;\n- **Intensive** green roofs, with deeper soil that can support shrubs, trees and amenity spaces, but adding much more weight;\n- **Semi-intensive** systems in between.\n\nBenefits can include stormwater retention, reduced roof surface temperatures, habitat for pollinators and longer membrane life due to protection from ultraviolet light and temperature swings. Structural capacity, drainage, wind uplift and fire breaks must be addressed in design.\n\n## Related organisations\n\nIn Europe, national green roof associations work together through the European Federation of Green Roof and Green Wall Associations (EFB). German FLL guidelines are a widely used technical reference internationally. In Canada, the Roofing Contractors Association of British Columbia has introduced a warranty program specifically for green roofs.","key_facts":[{"label":"Active since","value":"1999"},{"label":"Region","value":"North America"},{"label":"Credential","value":"Green Roof Professional (GRP)"},{"label":"Conference","value":"CitiesAlive"}],"regions":["North America"],"aliases":["GRHC"],"related":["green-roof","european-federation-of-green-roof-associations","fll"],"company":{"founded":"1999","website":"https://greenroofs.org","known_for":["Green Roof Professional accreditation","CitiesAlive conference"]},"sources":[{"title":"About GRHC","url":"https://greenroofs.org/about","publisher":"Green Roofs for Healthy Cities"},{"title":"Green Roofs for Healthy Cities home page","url":"https://www.greenroofs.org/","publisher":"Green Roofs for Healthy Cities"},{"title":"RCABC launches new green roofing program","url":"https://www.rcabc.org/rcabc-launches-new-green-roofing-program/","publisher":"RCABC"}],"category":"organizations","type":"organization","country":null},{"slug":"green-roofs-in-germany","title":"Green Roofs in Germany","type":"place","summary":"Germany pioneered modern green roof technology and guidelines, and many German cities support green roofs through planning rules and fees.","body":"Germany is widely regarded as the birthplace of the modern green roof industry. Lightweight green roof systems were developed there in the 1960s, and by the 1970s stormwater problems in growing cities encouraged their wider use. Germany was the first country to develop and market green roofs on a large scale, and its technical guidelines have influenced practice worldwide.\n\n## Technical guidelines\n\nThe FLL (Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau, the Landscape Research, Development and Construction Society) was founded in 1975. Its green roof working group produced guidelines covering design, construction and maintenance; the current Green Roof Guideline was published in 2011, and an English edition exists. The FLL guidelines are used or adapted in many countries that lack their own standards.\n\n## Scale\n\nPublished estimates suggest that about 10 percent of German roofs have been greened and that about 10 million square metres (roughly 108 million square feet) of new green roofs are built each year, around three-quarters of them extensive and one-quarter roof gardens.\n\n## Policy approach\n\nBy the early 2000s, many German metropolitan areas had laws requiring green roofs, and nearly a third of German cities have regulations supporting green roofs and rainwater technology. Requirements are typically set locally rather than nationally, so rules differ from city to city.\n\n## Influence abroad\n\nGerman manufacturers, research and guidelines shaped early green roof markets elsewhere in Europe and North America. Cities such as Basel in neighbouring Switzerland developed their own requirements, adding biodiversity criteria.\n\n## Stormwater emphasis\n\nGerman green roof policy grew largely out of stormwater management. Green roofs can retain up to about 75 percent of rainfall and slow the remainder, reducing peak flows to sewers. This link to water management is one reason many German regulations treat green roofs together with other rainwater technologies.","key_facts":[{"label":"Modern green roofs developed","value":"1960s"},{"label":"FLL founded","value":"1975"},{"label":"FLL Green Roof Guideline (current)","value":"2011"},{"label":"New green roofs per year (estimate)","value":"About 10 million m²"},{"label":"Share of roofs greened (estimate)","value":"About 10%"}],"regions":["Europe"],"aliases":["German green roofs","Dachbegrünung","FLL guidelines"],"related":["green-roof","basel-green-roof-policy","copenhagen-green-roof-policy","blue-roof"],"sources":[{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"},{"title":"A Review of Green Roof Laws & Policies","url":"https://guarinicenter.org/a-review-of-green-roof-laws-policies","publisher":"Guarini Center, NYU School of Law"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"grp-fibreglass-roofing","title":"GRP (Fibreglass) Flat Roofing","category":"low-slope-systems","type":"term","summary":"A flat-roof covering of polyester resin and chopped glass-fibre mat laminated on site over a timber deck and finished with a pigmented topcoat.","body":"GRP (glass-reinforced plastic) roofing, widely called fibreglass roofing in the UK, is a liquid-applied waterproofing made by laminating glass-fibre matting with resin on the roof. It is especially common on domestic flat roofs in Britain and Ireland, such as extensions, garages and dormers.\n\n## Construction\n\nA typical system is built in stages:\n\n1. a smooth, rigid timber deck, commonly OSB or plywood boards laid tight and fixed\n2. edge trims and drip details fixed and laminated in\n3. a laminate of catalysed polyester resin worked into chopped strand glass-fibre mat with rollers to remove air\n4. after curing, a pigmented topcoat that protects the laminate from UV and gives the finished colour\n\nSome systems use other resins, such as acrylic or polyurethane-modified chemistries, and are effectively reinforced liquid-applied membranes.\n\n## Characteristics\n\n- **Seamless:** the whole roof, including upstands and trims, is one laminate.\n- **Light and hard:** suitable for occasional foot traffic and easy to clean.\n- **Rigid:** GRP has limited ability to accommodate deck movement, so it needs a stable, well-fixed deck; cracking at board joints and trims is a common defect when decks move.\n- **Weather-sensitive:** the resin must cure in dry conditions within suitable temperature ranges.\n\n## Suitability\n\nBecause of its rigidity and dependence on a stable timber deck, GRP is considered less suited to large roofs, where single-ply, RBM or other liquid systems are generally preferred. Like other liquids, quality depends heavily on installer skill and correct resin and catalyst ratios.\n\n## Comparison with other liquids\n\nGRP is one of several resin-based flat-roof options. Modern cold-applied reinforced liquid systems using polyurethane or PMMA resins with polyester fleece are more flexible and are often chosen for larger roofs, balconies and detailing.","key_facts":[{"label":"Materials","value":"Polyester resin, chopped strand glass mat, topcoat"},{"label":"Typical deck","value":"OSB or plywood"},{"label":"Main market","value":"UK and Ireland domestic roofs"},{"label":"Limitation","value":"Rigid; suited to small, stable roofs"}],"regions":["Europe"],"aliases":["fibreglass roof","fiberglass roofing","GRP roof","glass-reinforced plastic roofing"],"related":["liquid-applied-roofing","flat-roof","roof-deck","pmma-roofing"],"company":null,"sources":[{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"Flat roof","url":"https://www.designingbuildings.co.uk/wiki/Flat_roof","publisher":"Designing Buildings Wiki"},{"title":"Top tips to help you get the most out of your flat roof","url":"https://www.sigroofing.co.uk/?p=12082","publisher":"SIG Roofing"},{"title":"Why the need for PMMA","url":"https://rcimag.co.uk/sika-roofing-hub/why-the-need-for-pmma","publisher":"RCI Magazine / Sika"}],"country":null},{"slug":"gunyah","title":"Gunyah","category":"world-roofing","type":"article","summary":"Aboriginal Australian shelter of bark, branches, leaves and grass, also called humpy, wurley, mia-mia or wiltija; often domed or a lean-to.","body":"A *gunyah* (also gunya) is a shelter traditionally built by Aboriginal Australians from bark, branches, leaves and grass. The same kind of structure is known by many names in different languages and regions: humpy, from the Turrubal language of the Brisbane area; wurley in South Australia, possibly from Kaurna; mia-mia among Wadawurrung speakers near Melbourne; and wiltija among Pitjantjatjara and Yankunytjatjara speakers. Other recorded words include nganu and goondie. Because there were hundreds of Aboriginal languages, these names are only a small sample.\n\n## Construction\n\nMany shelters were lean-tos, using a standing tree for support, with a covering of bark sheets, branches, leaves or grass. Researcher Paul Memmott found that many Aboriginal huts were dome structures. Designs varied with climate, local materials, family size and the needs of the community: some houses had triple layers of cladding and insulation, and fires kept burning around a gunyah gave warmth and drove away snakes and insects. In the rainforest near Cairns, domed villages were occupied for up to a year during the wet season.\n\n## Permanent and stone-based houses\n\nThe image of Aboriginal shelters as purely temporary has been challenged. Writer Bruce Pascoe argues that some gunyahs in the Channel Country could hold up to 50 people and formed part of settled communities. In south-west Victoria, the Gunditjmara built houses with circular basalt walls (see [Budj Bim stone houses](/budj-bim-stone-houses)), and circular stone house foundations on the Dampier Archipelago in Western Australia have been dated to about 9,000 years ago.\n\n## Influence on colonial roofing\n\nEarly European settlers learned from Aboriginal people which trees yielded good roofing bark, such as stringybark and box, and how to cure it, by soaking in salt water or smoking it over a fire so that it stayed flat. Bark roofs became common on colonial huts.\n\n## Later meaning\n\nThe word \"humpy\" later broadened to mean any makeshift shelter built from available materials, including canvas, flattened drums and corrugated iron.","key_facts":[{"label":"Region","value":"Australia"},{"label":"Materials","value":"Bark, branches, leaves, grass"},{"label":"Forms","value":"Lean-to or dome"},{"label":"Other names","value":"Humpy, wurley, mia-mia, wiltija, goondie, nganu"}],"regions":["Oceania"],"aliases":["Gunya","Humpy","Wurley","Wurlie","Mia-mia","Wiltija","Goondie"],"related":["roofing-in-australia","budj-bim-stone-houses","prehistoric-shelters-and-early-thatch","thatch"],"company":null,"sources":[{"title":"Humpy","url":"https://en.wikipedia.org/wiki/Humpy","publisher":"Wikipedia"},{"title":"Aboriginal houses","url":"https://www.creativespirits.info/aboriginalculture/land/aboriginal-houses","publisher":"Creative Spirits"},{"title":"Miles Lewis Heritage Building Collection: Roofing","url":"https://acahuch.msd.unimelb.edu.au/miles-lewis-heritage-building-collection/roofing2","publisher":"University of Melbourne (ACAHUCH)"}],"country":null},{"slug":"gutter-problems","title":"Gutter Problems","category":"problems-maintenance","type":"article","summary":"Common faults in roof gutters and downpipes, including clogging, overflow, incorrect pitch, ice build-up, leaking joints and sagging.","body":"Gutters (eavestroughs in Canada, rain gutters or spouting elsewhere) collect water from the roof edge and carry it to downpipes (downspouts) and away from the building. When they fail, water spills where it should not: onto fascia boards, down walls, and around foundations. Many roof-edge rot and basement water problems start with neglected gutters.\n\n## Clogging\n\nLeaves, needles, seed pods, roof granules, moss and nests collect in gutters and at downpipe outlets. Blocked gutters overflow, hold standing water that adds weight, and in winter can fill with ice. Cleaning frequency depends on nearby trees; many owners clean at least in spring and autumn. Gutter guards and outlet strainers reduce but do not eliminate maintenance.\n\n## Incorrect pitch\n\nGutters need a slight fall toward the outlet. A commonly cited guideline is about 1/4 inch of fall per 10 feet of gutter (roughly 2 mm per metre), with more fall in heavy-rain areas. Gutters that are too flat hold water and debris; gutters pitched backward overflow at the wrong end; gutters with too steep a slope can look crooked and may leave debris behind as water rushes past. Long runs often need an additional downpipe or to slope in two directions.\n\n## Overflow\n\nEven clean gutters can overflow if they are undersized for the roof area and local rainfall, if there are too few downpipes, or where valleys dump concentrated flow at one point. Splash guards at valley outlets and larger profiles or outlets help.\n\n## Ice\n\nIn cold climates, gutters can fill with ice and contribute to ice dams. Ice weight can bend gutters and pull hangers out. The lasting fix is reducing heat loss from the attic; heat cable is a localised measure.\n\n## Leaks, sagging and separation\n\nJoints, end caps and outlets leak as sealant ages. Hangers loosen or rot out of the fascia, causing sags that hold water. Gutters that pull away can let water run behind them; a correctly placed drip edge or gutter apron directs roof water into the gutter.\n\n## Discharge\n\nDownpipes should discharge well away from foundations, into extensions, drains or soakaways permitted by local rules. Rainwater harvesting systems need clean gutters and first-flush devices.","key_facts":[{"label":"Guideline fall","value":"About 1/4 in per 10 ft (about 2 mm/m)"},{"label":"Main failure","value":"Clogging and overflow"},{"label":"Linked problems","value":"Fascia rot, ice dams, foundation water"}],"regions":["Global"],"aliases":["eavestrough problems","clogged gutters","gutter overflow"],"related":["rain-gutter","downspout","drip-edge","ice-dam","wood-rot","roof-maintenance-checklist"],"company":null,"sources":[{"title":"How Much Slope Does a Gutter Need on Your Home?","url":"https://angi.com/articles/how-much-slope-does-gutter-need.htm","publisher":"Angi"},{"title":"7 Gutter Problems and How to Fix Them","url":"https://www.leecompany.com/resources/7-gutter-problems-and-how-to-fix-them","publisher":"Lee Company"},{"title":"Main Issues with Rain Gutters and Their Solutions","url":"https://alu-rex.com/en/blog/issues-solutions-rain-gutters","publisher":"Alu-Rex"}],"country":null},{"slug":"hagia-sophia-dome","title":"Hagia Sophia Dome","category":"history","type":"place","summary":"The great dome of Hagia Sophia in Istanbul, built 532-537, rebuilt after a collapse in 558 and repaired after further failures in 989 and 1346.","body":"**Hagia Sophia** in Istanbul (ancient Constantinople) was built for the Byzantine emperor **Justinian I** between **532 and 537**. Its vast central dome, seemingly floating above a ring of windows, was the largest of its time and set the model for Byzantine and later Ottoman domed architecture.\n\n## Design\n\nThe architects were **Anthemius of Tralles** and **Isidore of Miletus**. Their key structural device was the **pendentive**: curved triangular sections of masonry that make the transition from the square plan of four great piers to the circular base of the dome. Semi-domes to the east and west extend the covered space.\n\n## Collapse and rebuilding\n\nThe first dome proved too flat. Earthquakes in 553 and 557 cracked it, and in **558** part of the structure, including the eastern semi-dome, collapsed. **Isidore the Younger** rebuilt the vault about 6.25 m (20.5 ft) higher using lighter materials, as a ribbed dome on pendentives with a diameter of about 32.7-33.5 m (107-110 ft). The reconstruction was completed in **562**. The interior height reached about 55.6 m (182 ft).\n\n## Later failures\n\n- **989:** an earthquake brought down the western dome arch. The Armenian architect **Trdat** rebuilt the west side with 15 dome ribs; the church reopened on 13 May 994.\n- **1346:** cracks from an earthquake in October 1344 led to partial collapses on 19 May 1346. Repairs by Astras and Peralta began in 1354.\n\n## Roof covering\n\nThe dome's outer covering has been repaired many times. In the 20th century cracking of its copper roof contributed to deterioration that prompted international conservation funding, including grants from the World Monuments Fund.\n\n## Status\n\nHagia Sophia is part of the UNESCO World Heritage Site \"Historic Areas of Istanbul\", inscribed in 1985.\n\n## Significance\n\nThe building showed how a large dome could be raised over a square plan, a problem central to later church and mosque roofing. Its repeated collapses also made it an early, well-documented case study in the effects of earthquakes on masonry roofs.","key_facts":[{"label":"Built","value":"532-537"},{"label":"Architects","value":"Anthemius of Tralles, Isidore of Miletus"},{"label":"Rebuilt dome completed","value":"562"},{"label":"Dome diameter","value":"About 32.7-33.5 m (107-110 ft)"},{"label":"Interior height","value":"About 55.6 m (182 ft)"}],"regions":["Europe","Middle East"],"aliases":["Aya Sofya dome","Hagia Sophia"],"related":["pantheon-dome","florence-cathedral-dome","st-pauls-cathedral-dome","dome"],"company":null,"sources":[{"title":"Hagia Sophia","url":"https://en.wikipedia.org/wiki/Hagia_Sophia","publisher":"Wikipedia"},{"title":"Historic Areas of Istanbul","url":"https://whc.unesco.org/en/list/356","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"hail-damage","title":"Hail Damage to Roofs","type":"article","summary":"Damage caused when hailstones strike roofing: bruising and granule loss on shingles, cracked tiles and slates, dented metal and punctured membranes.","body":"Hail forms when thunderstorm updrafts carry raindrops into air cold enough to freeze them; the stones grow as supercooled droplets freeze onto them and fall once they are too heavy for the updraft to support. Roofs, being the most exposed surface of a building, take the brunt of hailstorms, and hail is one of the largest sources of residential property insurance claims in the central United States.\n\n## Size, speed and severity\n\nThe US National Weather Service treats hail 25 mm (1 in) in diameter, about the size of a quarter, as severe. Estimated fall speeds, which are uncertain, range from roughly 14-40 km/h (9-25 mph) for stones under 25 mm to 71-116 km/h (44-72 mph) for 50-100 mm (2-4 in) stones; the largest stones may exceed 160 km/h (100 mph). The US record hailstone fell at Vivian, South Dakota on June 23, 2010; it measured 20 cm (8 in) across and weighed about 0.88 kg (1 lb 15 oz).\n\n## Frequency and losses\n\nNOAA's Storm Prediction Center recorded 5,373 major hail events (stones 25 mm or larger) in the US in 2024 and 5,432 in 2025, according to the Insurance Information Institute. Texas had the most in 2025. One large US insurer alone reported paying more than $5.6 billion in hail claims in 2025.\n\n## How different roofs are damaged\n\nDamage thresholds vary widely by material, thickness, age and the substrate beneath. Industry summaries give approximate figures:\n\n- **Asphalt shingles:** standard products may show functional damage (fractured mat, granule loss exposing asphalt) from about 32 mm (1.25 in) hail; impact-rated products resist larger stones when new.\n- **Wood shakes:** splitting is common from about 38 mm (1.5 in) hail.\n- **Slate:** thinner slate can crack from 25-38 mm hail; thicker slate performs better.\n- **Concrete and clay tile:** cracking becomes widespread at larger sizes, around 50-75 mm (2-3 in) and above.\n- **Metal panels:** usually dented rather than punctured, even by very large hail; dents may be cosmetic or may affect coatings and seams.\n- **Low-slope membranes:** thin single-ply sheets over soft insulation can puncture from moderate hail, while thicker membranes over a cover board resist much larger stones.\n\n## Assessing damage\n\nInspectors distinguish functional damage (which shortens service life or allows leaks) from cosmetic damage (appearance only). Insurance policies in some US states treat cosmetic metal dents differently from functional damage, so endorsements matter.\n\n## Reducing risk\n\nOptions include impact-rated coverings (UL 2218 or FM 4473 Class 4), thicker or reinforced membranes, cover boards under low-slope systems, and timely replacement of aged roofing, since weathering makes many materials more brittle. Research by the Insurance Institute for Business & Home Safety (IBHS) uses field-measured hailstone properties to develop more realistic test methods.","key_facts":[{"label":"Severe hail threshold (US NWS)","value":"25 mm (1 in) diameter"},{"label":"US record stone","value":"Vivian, SD, June 23, 2010: 20 cm (8 in), about 0.88 kg"},{"label":"US major hail events","value":"5,373 (2024); 5,432 (2025)"},{"label":"Main mitigation","value":"Class 4 impact-rated coverings, cover boards"}],"regions":["North America","Europe","Global","Oceania","East Asia"],"aliases":["hail damage","hailstorm roof damage","hail impact","hail-damaged roof"],"related":["impact-resistance-rating","fortified-roof","roof-insurance-discounts","roof-insurance-depreciation","climate-change-and-roofing","storm-damage-inspection","wind-damage","granule-loss","roof-insurance-claims"],"sources":[{"title":"Severe Weather 101: Hail","url":"https://www.nssl.noaa.gov/education/svrwx101/hail/","publisher":"NOAA National Severe Storms Laboratory"},{"title":"Facts + Statistics: Hail","url":"https://www.iii.org/fact-statistic/facts-statistics-hail","publisher":"Insurance Information Institute"},{"title":"Roof Hail Impact Resistance","url":"https://roofobservations.com/roof-hail-impact-resistance/","publisher":"Roof Observations"},{"title":"Hail Impact Resistance Test Protocol for Asphalt Shingles (Natural Hazards Review, 2021)","url":"https://ascelibrary.com/doi/10.1061/%28ASCE%29NH.1527-6996.0000509","publisher":"ASCE Library"},{"title":"Is It Hail Damage?","url":"https://ibhs.org/is-it-hail-damage/","publisher":"Insurance Institute for Business & Home Safety"},{"title":"Call insurance adjuster to determine hail damage","url":"https://extension.missouri.edu/news/call-insurance-adjuster-to-determine-hail-damage","publisher":"University of Missouri Extension"},{"title":"Hail Damage","url":"https://inspectapedia.com/roof/Hail_Damage.pdf","publisher":"InspectAPedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"hail-resistance-metal-roofs","title":"Hail Resistance of Metal Roofs","category":"problems-maintenance","type":"article","summary":"Metal roofs are hard to puncture by hail; many assemblies reach UL 2218 Class 4, though large hailstones can still leave cosmetic dents.","body":"Hail is a major cause of roof damage in many regions. Metal roofing is generally difficult to puncture, which is why it is often chosen in hail-prone regions, but its behaviour depends on metal type, thickness, profile and what lies beneath it.\n\n## Testing\n\nThe most widely cited test in North America is UL 2218, which drops steel balls of increasing size onto a roof covering. Results are classed from 1 to 4, with Class 4 the highest. In the Class 4 test, 2 in (51 mm) steel balls are dropped from about 20 ft (6 m), and the covering passes only if it shows no cracking or penetration. Many metal panels over a solid deck, as well as stone-coated steel products, are listed as Class 4.\n\n## Dents versus leaks\n\nClass 4 ratings address whether the covering is broken, not whether it dents. Large hailstones can leave dimples in metal, especially in softer metals such as aluminium and copper or in thin panels. Dents are usually cosmetic and do not cause leaks. Very severe storms can still damage seams, flashings and fasteners, and long storms with large stones on low-slope roofs are the most damaging.\n\n## Reducing visible damage\n\n- Thicker, more rigid metal, which resists denting better than thin sheet.\n- Profiles with ribs, striations or deep textures that stiffen the panel and disguise small dents; smooth, flat panels show dents most.\n- Solid, well-supported decks.\n- Stone-coated or textured finishes.\n\n## Insurance\n\nSome insurers offer premium reductions for impact-rated roofs, while some policies or \"cosmetic damage\" waivers exclude dents that do not affect function. Owners in hail regions should read policy terms carefully, since waivers can lower premiums but limit claims.","key_facts":[{"label":"Key test (North America)","value":"UL 2218, Classes 1-4"},{"label":"Class 4 test","value":"2 in (51 mm) steel ball from about 20 ft (6 m)"},{"label":"Typical damage","value":"Cosmetic dents rather than punctures"}],"regions":["Global"],"aliases":["UL 2218","Class 4 metal roof","impact-resistant metal roofing","hail damage metal roof"],"related":["stone-coated-steel","sheet-metal-gauge","wind-uplift-testing-metal-roofs","metal-roofs-and-lightning"],"company":null,"sources":[{"title":"The myths of metal roofing damage from lightning and hail storms","url":"https://www.metalcoffeeshop.com/post/the-myths-of-metal-roofing-damage-from-lightning-and-hail-storms","publisher":"MetalCoffeeShop"},{"title":"Busting 5 Metal Roofing Myths","url":"https://www.rooferscoffeeshop.com/post/busting-5-metal-roofing-myths-2","publisher":"RoofersCoffeeShop"},{"title":"DECRA Metal Roofing","url":"https://www.decra.com/","publisher":"DECRA Roofing Systems"},{"title":"Are Metal Roofs Good for Hail?","url":"https://www.interlockroofing.com/kb/are-metal-roofs-good-for-hail/","publisher":"Interlock Roofing"},{"title":"Do Metal Roofs Dent? Impact Resistance Explained","url":"https://www.interlockroofing.com/kb/do-metal-roofs-dent/","publisher":"Interlock Roofing"},{"title":"Aluminum Roofing Gauge & Thickness Explained (2026)","url":"https://www.interlockroofing.com/kb/aluminum-roofing-gauge-thickness/","publisher":"Interlock Roofing"}],"country":null},{"category":"world-roofing","type":"article","company":null,"slug":"haitian-gingerbread-house","title":"Haitian Gingerbread House","summary":"Ornate timber and masonry house of Port-au-Prince (1885-1925) with steep roofs and turrets, now mostly corrugated steel; many survived the 2010 earthquake.","body":"Haitian gingerbread houses are ornate houses built in Port-au-Prince between about 1885 and 1925, mainly in the districts of Bois Verna, Pacot and Turgeau. They adapted French architectural styles and building methods of the period to Haiti's climate, materials and culture, and are known for steep roofs, tall turrets and bright colours.\n\n## Origins\n\nThe style is linked to three young Haitians who went to Paris in 1895 to study architecture and returned to adapt Parisian and Victorian Gothic styles to the Caribbean, adding local motifs such as Vodou *vèvè* symbols. After several destructive fires, Port-au-Prince banned wood construction in 1925, the year usually taken as the end of the gingerbread period; concrete and concrete block became normal for later additions and neighbouring buildings.\n\n## Roof\n\n- **Pitch**: roofs are steep, often steeper than 1:1 (45°), shedding heavy rain quickly.\n- **Turrets and tall roofs**: draw hot air up and out of the living rooms, a passive cooling strategy.\n- **Framing**: timber, often braced in the attic, joined with mortise-and-tenon joints and wooden pegs.\n- **Covering**: almost all roofs now have corrugated steel over spaced (skip) sheathing. A few keep their original thin slate on more closely spaced sheathing. The turrets of Le Manoir are covered in decorative pressed-metal shingles.\n\n## Walls\n\nConstruction includes timber frame, *colombage* (timber frame with masonry infill) and load-bearing masonry, sometimes with iron tie rods.\n\n## 2010 earthquake\n\nAfter the magnitude 7.0 earthquake of 12 January 2010, the World Monuments Fund and ICOMOS, with the Haitian foundation FOKAL, surveyed about 200 gingerbread houses between 18 and 24 April 2010. Timber-frame and *colombage* buildings generally performed best, masonry buildings less well, and concrete and block additions worst, often damaging the older houses by pounding against them. Wood rot and termite damage increased losses. Fewer than 5% of gingerbread houses collapsed completely, compared with an estimated 40% of modern conventional buildings. The findings led to preservation manuals, an exhibition and the restoration of a house as a conservation centre.\n\n## Significance\n\nThe houses show how a light, steep, well-ventilated roof on a flexible frame suits a hot, wet, seismic and hurricane-prone island, in contrast to the heavy concrete slab roofs that failed in 2010.","key_facts":[{"label":"Period","value":"C. 1885-1925"},{"label":"Location","value":"Port-au-Prince (Bois Verna, Pacot, Turgeau)"},{"label":"Roof pitch","value":"Often steeper than 45°"},{"label":"Covering today","value":"Corrugated steel; a few original slate"},{"label":"2010 collapse rate","value":"Under 5%, vs ~40% of modern buildings"}],"regions":["Latin America","North America"],"aliases":["Gingerbread house (Haiti)","Kay gingerbread","Gingerbread houses of Port-au-Prince"],"related":["roofing-in-haiti","corrugated-iron","natural-slate","metal-shingles","roofing-in-the-caribbean"],"sources":[{"title":"Gingerbread houses of Haiti: earthquake assessment","url":"https://hazards.colorado.edu/archive/workshop/2010/speakers/pubs/hammer_gingerbread.pdf","publisher":"Natural Hazards Center, University of Colorado (Martin Hammer)"},{"title":"Haiti's Gingerbread Houses Focus of Preservation Efforts","url":"https://architecturalrecord.com/articles/2229-haiti-s-gingerbread-houses-focus-of-preservation-efforts","publisher":"Architectural Record"},{"title":"Gingerbread Houses","url":"https://visithaiti.com/art-culture/gingerbread-houses/","publisher":"Visit Haiti"}],"country":null},{"slug":"hammerbeam-roof","title":"Hammerbeam Roof","category":"history","type":"term","summary":"An open timber roof truss of English Gothic origin in which short brackets (hammer beams) project from the walls, allowing spans longer than any single timber.","body":"A **hammerbeam roof** is a decorative open timber roof in which short horizontal beams, called hammer beams, project inward from the tops of the walls. Each hammer beam is supported by a curved brace beneath it and carries a vertical post (hammer post) and further braces above. This arrangement replaces a full-width tie beam, so the roof can cover a wider space than the length of any available timber. It is often called the most spectacular achievement of the English medieval carpenter.\n\n## How it works\n\nThe weight of the roof passes down through the hammer posts and braces onto the hammer beams, then through the wall braces into the masonry. Because there is no continuous tie beam, the truss pushes outwards on the walls, so hammerbeam roofs usually need thick walls or buttresses.\n\nTypes include:\n\n- **Single hammerbeam:** one tier of brackets.\n- **Double hammerbeam:** a second tier above the first, used for taller roofs.\n- **False hammerbeam:** the hammer beam has no post above it; the brace runs straight to the collar.\n\n## Early examples\n\nPossibly the earliest standing hammerbeam building in England is the **Pilgrims' Hall** in Winchester Cathedral Close, built about 1310. Hammer beams also appear, hidden behind timber vaulting, in the octagon lantern of **Ely Cathedral**, begun in 1334 by carpenter William Hurley.\n\n## Westminster Hall\n\nThe best-known example is Hugh Herland's roof over **Westminster Hall**, London, commissioned by Richard II in 1393. It spans about 20.7 m (68 ft) and is decorated with 26 carved angels.\n\n## Later examples\n\nNotable later hammerbeam or false hammerbeam roofs include the Great Halls of **Hampton Court Palace** and **Eltham Palace**, and many East Anglian parish churches with carved \"angel roofs\", such as St Mary's, Bury St Edmunds. At **Stirling Castle**, the Great Hall roof built around 1502 was reconstructed between 1991 and 1999 with 57 trusses of green oak.\n\n## Regions\n\nThe hammerbeam is essentially an English form. Continental European carpenters solved long spans more often with complex trussed or vaulted roofs hidden above masonry vaults.","key_facts":[{"label":"Earliest surviving (England)","value":"Pilgrims' Hall, Winchester, about 1310"},{"label":"Most famous","value":"Westminster Hall, commissioned 1393"},{"label":"Westminster span","value":"About 20.7 m (68 ft)"}],"regions":["Europe"],"aliases":["hammer-beam roof","hammer beam truss","angel roof"],"related":["westminster-hall-roof","history-of-timber-roof-framing","roof-truss","king-post-truss","collar-tie","rafter"],"company":null,"sources":[{"title":"Hammerbeam roof","url":"https://en.wikipedia.org/wiki/Hammerbeam_roof","publisher":"Wikipedia"},{"title":"The hammer-beam roof","url":"https://webtest.parliament.uk/about/living-heritage/building/palace/westminsterhall/architecture/the-hammer-beam-roof-","publisher":"UK Parliament"},{"title":"Westminster Hall","url":"https://en.wikipedia.org/wiki/Westminster_Hall","publisher":"Wikipedia"}],"country":null},{"slug":"hand-sealing-shingles","title":"Hand Sealing Shingles","category":"installation","type":"term","summary":"Hand sealing is applying dabs of asphalt cement under shingles where factory sealant cannot be relied on, such as on steep slopes or in cold weather.","body":"Most asphalt shingles have a factory-applied **sealant strip** that softens in the sun and bonds each course to the one below, which is essential to wind resistance. **Hand sealing** (or **hand-tabbing**) means applying asphalt roofing cement or a compatible adhesive by hand to bond shingles where the factory strip will not do the job.\n\n## When it is used\n\n- **Cold weather.** When temperatures are too low for the sealant to activate soon after installation.\n- **Steep slopes and mansards.** One manufacturer requires steep-slope application, defined as 21 in per foot (about 60 degrees) or more, to use six nails and three 1 in (25 mm) diameter spots of cement per shingle, about 2 in (50 mm) above the bottom edge.\n- **Starter courses** without factory sealant, where Canadian guidance calls for hand-tabbing the first course to the starter.\n- **Valleys, rakes and cut edges**, where shingles are trimmed and the sealant line is lost.\n- **High-wind programmes**, which may require cement along eaves, rakes, hips and ridges.\n\n## Method\n\n1. Use the material the shingle manufacturer specifies, typically asphalt plastic cement meeting ASTM D4586 or an SBS-modified mastic.\n2. Apply small dabs: one under each tab of 3-tab shingles, or several evenly spaced dabs along the lower edge of laminated shingles.\n3. Press the shingle into the cement.\n\n## Cautions\n\nManufacturers warn against using too much cement. Excess cement can cause blistering of the shingle. Cement should not be smeared across the surface or left exposed. Hand sealing does not replace correct nailing; it supplements it.","key_facts":[{"label":"Typical dab size","value":"About 1 in (25 mm) diameter (one manufacturer's steep-slope instructions)"},{"label":"Steep slope definition (one manufacturer)","value":"21 in per ft (about 60 degrees) or more"},{"label":"Material","value":"Asphalt plastic cement (ASTM D4586) or SBS mastic"}],"regions":["North America","Global"],"aliases":["hand-tabbing","hand sealing","manual shingle sealing"],"related":["cold-weather-roofing","shingle-nailing-pattern","starter-course","asphalt-shingle"],"company":null,"sources":[{"title":"TBR64 Proper Nailing for Laminated Shingles","url":"https://www.iko.com/na/document/tbr64-proper-nailing-for-laminated-shingles-product-bulletin","publisher":"IKO"},{"title":"Shingle Application Mechanics: Starter Courses, Offsets, Fastener Placement and Wind Sealant Activation","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-application-mechanics","publisher":"Open Exam Prep"},{"title":"Canadian Roofing Reference Manual: 9.1.2 Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-1-asphalt-shingles/9-1-2-installation/","publisher":"Canadian Roofing Contractors Association"},{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"}],"country":null},{"slug":"hand-seamer","title":"Hand Seamer","category":"tools-equipment","type":"term","summary":"A plier-like sheet metal tool with broad flat jaws used to bend, fold, flatten and close edges and seams on flashing and metal roofing.","body":"A hand seamer, also called hand tongs or simply tongs in some trades, is a manual tool for bending and seaming thin sheet metal. It looks like oversized pliers with broad, flat jaws and long handles that give leverage. Roofers, sheet metal workers, gutter installers and HVAC technicians use seamers for small bends and touch-ups where a sheet metal brake is impractical, such as on the roof itself.\n\n## Types\n\n- **Straight seamers** with forged straight jaws are the general-purpose type; a 3 in (about 75 mm) jaw is a common first tool, with 6 in (about 150 mm) and wider jaws for longer bends.\n- **Offset seamers** have handles angled up from the jaws so the user's knuckles clear the surface, which helps when bending metal lying flat on the roof.\n- **Standing seam seamers** have jaws sized to the seam height and are used to form or close mechanically seamed panels in places where power seamers cannot reach. First-stage and second-stage seamers form the 90-degree and 180-degree folds of a double-lock seam.\n- **Specialty seamers** include curved jaws for rounded flashing, narrow jaws for tight spaces, and combination tools that also crimp.\n\nMany jaws are scribed with depth marks, for example in 1/4 in (about 6 mm) increments, so bends can be made at a consistent depth.\n\n## Uses in roofing\n\n- Turning up and hemming the ends of standing seam panels at eaves, ridges and walls.\n- Forming and adjusting flashing around chimneys, skylights and pipes.\n- Closing seams and folds at details.\n- Shaping gutter end caps, corners and outlets.\n- Straightening damaged edges.\n\n## Choosing and using\n\nThe jaw opening should suit the depth of the hem or seam: too narrow and it will not grip, too wide and the fold may be weak. Seamers rated for the metal type and gauge avoid marking or cracking painted panels. Smooth jaws or protective sleeves help prevent scratches on coated metal, which can become corrosion points.","key_facts":[{"label":"Common jaw widths","value":"3 in (75 mm) and 6 in (150 mm)"},{"label":"Main types","value":"Straight, offset, standing seam, specialty"},{"label":"Typical users","value":"Metal roofers, gutter and sheet metal workers"}],"regions":["Global"],"aliases":["hand tongs","hand bender","sheet metal seamer"],"related":["power-seamer","hemming-tool","sheet-metal-brake","standing-seam-metal-roof","aviation-snips"],"company":null,"sources":[{"title":"Hand seamer","url":"https://en.wikipedia.org/wiki/Hand_seamer","publisher":"Wikipedia"},{"title":"Hand seamer guide","url":"https://www.stortz.com/hand-seamer-guide/","publisher":"John Stortz & Son"},{"title":"Offset Hand Seamer","url":"https://www.kleintools.com/catalog/seaming-folding-tools/offset-hand-seamer","publisher":"Klein Tools"}],"country":null},{"slug":"handsplit-shake","title":"Handsplit Shake","type":"term","summary":"A wooden shake with at least one face split along the grain, giving a rough, textured surface; often made as handsplit-and-resawn.","body":"A handsplit shake is a wooden roofing unit whose exposed face has been split along the natural grain of the wood rather than sawn. The split surface is rough and irregular, giving shake roofs their rugged texture and deep shadows.\n\n## Traditional method\n\nHistorically, shakes and shingles were split entirely by hand. A splitter drove a froe, a blade with a handle at right angles, into a short block (bolt) of straight-grained, knot-free wood with a wooden mallet, levering off one piece at a time. To produce a taper, the splitter flipped the block end-for-end between each split. Hand-split pieces were often dressed with a drawknife so they would lie flat on the roof.\n\n## Modern variants\n\n- **Handsplit and resawn**: a thick split blank is passed diagonally through a band saw, producing two shakes, each with a split face and a sawn back. This is the most common modern type.\n- **Tapersplit**: split on both faces, with the taper produced by turning the block between splits.\n- **Straight-split**: split on both faces without a taper, so the unit is the same thickness throughout.\n\nIn North America these are certified under the Cedar Shake & Shingle Bureau's Certi-Split label.\n\n## Characteristics\n\nBecause splitting follows the grain, the fibres are continuous through the shake. This makes handsplit shakes strong, less prone to warping and better at shedding water along their surface than units sawn across the grain. The irregular faces, however, leave gaps between courses, so felt interlay is normally used under shakes to keep out wind-driven rain and snow.\n\n## Heritage\n\nHand-riven shakes and shingles are used in the conservation of historic timber buildings in North America and Europe, where heritage guidance often favours reproducing the original splitting technique and species.\n","key_facts":[{"label":"Surface","value":"Split along the grain (rough)"},{"label":"Traditional tools","value":"Froe and mallet; drawknife"},{"label":"Certification label","value":"Certi-Split (CSSB)"}],"regions":["North America","Europe"],"aliases":["hand-split shake","handsplit and resawn shake","split shake","riven shingle"],"related":["wood-shake","tapersawn-shake","wood-shingle","cedar-shake-and-shingle-bureau"],"sources":[{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Cedar Shake & Shingle Bureau","url":"https://www.cedarbureau.org/","publisher":"Cedar Shake & Shingle Bureau"}],"category":"materials","company":null,"country":null},{"slug":"hanging-gardens-of-babylon","title":"Hanging Gardens of Babylon","category":"history","type":"place","summary":"A legendary terraced garden, one of the Seven Wonders, often cited as the first roof garden; its existence and location are disputed.","body":"The **Hanging Gardens of Babylon** were one of the Seven Wonders of the Ancient World, described by Greek and Roman writers as tiers of planted terraces rising above the city of Babylon in Mesopotamia. In the history of roofing they are often cited as the earliest roof garden, although whether they existed, and where, remains uncertain.\n\n## The traditional account\n\nLater tradition attributes the gardens to King **Nebuchadnezzar II**, who reigned from 605 to 562 BCE. The only ancient source to credit Nebuchadnezzar is **Berossus**, a Babylonian priest writing around 290 BCE. Other classical writers, including Diodorus Siculus and Quintus Curtius Rufus, attribute the gardens to an unnamed \"Syrian king\".\n\n## Descriptions\n\nDiodorus describes brick walls about 6.7 m (22 ft) thick supporting terraces with soil deep enough for large trees. Strabo describes water lifted from the Euphrates by screw devices to irrigate them. Accounts of how the terraces were waterproofed differ between sources.\n\n## Doubts\n\nNo surviving Babylonian text mentions the gardens. Nebuchadnezzar's long building inscriptions say nothing about them, and no definitive archaeological evidence has been found at Babylon. Scholars have proposed three main explanations:\n\n- the gardens were purely mythical or poetic;\n- they existed but were destroyed by around the 1st century CE;\n- the story refers to a different garden.\n\nAssyriologist **Stephanie Dalley** argues that the gardens were built by the Assyrian king **Sennacherib** (c. 704-681 BCE) at **Nineveh**, and that the two cities were later confused. Her evidence includes Sennacherib's inscriptions on water engineering, the Jerwan aqueduct, and a relief from his grandson Ashurbanipal's palace showing a mature garden.\n\n## Significance for roofing\n\nWhatever their reality, the gardens became a powerful image of plants grown on built structures, and they are routinely referenced in histories of green roofs and roof gardens.","key_facts":[{"label":"Traditional builder","value":"Nebuchadnezzar II (r. 605-562 BCE)"},{"label":"Earliest attribution","value":"Berossus, about 290 BCE"},{"label":"Alternative theory","value":"Sennacherib's garden at Nineveh (Dalley)"},{"label":"Archaeological proof","value":"None found at Babylon"}],"regions":["Middle East"],"aliases":["Hanging Gardens","Babylon roof garden"],"related":["history-of-green-roofs","scandinavian-sod-roofs"],"company":null,"sources":[{"title":"Hanging Gardens of Babylon","url":"https://en.wikipedia.org/wiki/Hanging_Gardens_of_Babylon","publisher":"Wikipedia"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"}],"country":null},{"slug":"hanok-roof","title":"Hanok Roof (Giwa and Choga)","type":"article","summary":"Roofs of the traditional Korean house: curved clay-tile giwa roofs of the upper classes and rice-straw choga thatch of rural commoners.","body":"The *hanok* is the traditional Korean house, and its roof is its most recognisable feature. Two main types are distinguished by covering: the *giwa-jip*, roofed with fired clay tiles, and the *choga-jip*, roofed with rice-straw thatch. In everyday usage \"hanok\" most often refers to the tiled house.\n\n## Giwa (tile) roofs\n\nFired-clay roof tiles were used in Korea from the Iron Age and give the hanok its typical silhouette: a heavy, gently curving roof whose eaves turn upward at the corners. The curve and depth of the eaves (*cheoma*) are carefully judged. A longer cheoma blocks the high summer sun while letting the lower winter sun reach into the rooms. Tiled roofs were built for upper- and middle-class households and gave equal weight to function and appearance.\n\nThe tiled roof is carried on a timber post-and-beam frame.\n\n## Choga (thatch) roofs\n\nHouses of provincial commoners, and of some impoverished aristocrats, were roofed with rice straw. These buildings were built more strictly for function. Straw was a by-product of the rice harvest, so the roof could be renewed with locally available material.\n\n## Climate and planning\n\nKorea has hot, humid summers and cold, dry winters. The hanok combines raised wooden floors for summer with *ondol* underfloor heating, already present in Iron Age houses, for winter. House plans vary with climate: southern houses tend to be open and in a single line, central houses L-shaped, and northern houses closed squares to block wind.\n\n## Heritage districts\n\nBukchon Hanok Village in Jongno District, Seoul, preserves many tile-roofed houses from the late 19th and early 20th centuries; it was designated a folk landscape area in 1976 and a conservation zone in 1983. Jeonju Hanok Village in North Jeolla contains more than 800 hanok.\n\n## Today\n\nNew hanok continue to be built, and preserved districts keep the giwa roofscape visible in Korean cities. Thatched choga are now seen mainly in folk villages and heritage settings.","key_facts":[{"label":"Tile roof","value":"Giwa (fired clay), curved eaves"},{"label":"Thatch roof","value":"Choga (rice straw)"},{"label":"Eaves","value":"Cheoma, sized for sun control"},{"label":"Heating","value":"Ondol underfloor system"},{"label":"Jeonju Hanok Village","value":"Over 800 houses"}],"regions":["East Asia"],"aliases":["Giwa","Choga","Giwa-jip","Choga-jip","Korean tile roof"],"related":["roofing-in-south-korea","clay-roof-tile","thatch","siheyuan-roof","japanese-kawara-tile"],"sources":[{"title":"Hanok","url":"https://en.wikipedia.org/wiki/Hanok","publisher":"Wikipedia"},{"title":"Bukchon Hanok Village","url":"https://en.wikipedia.org/wiki/Bukchon_Hanok_Village","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"harran-beehive-houses","title":"Harran Beehive Houses","category":"world-roofing","type":"place","regions":["Middle East"],"company":null,"summary":"Conical mud-brick domed houses (kümbet) of Harran in south-eastern Turkey, built without timber and vented at the top.","aliases":["Harran houses","kümbet evler","beehive houses","Harran trulli"],"body":"The beehive houses of Harran, near Şanlıurfa in south-eastern Turkey, are clusters of small rooms each roofed with a tall conical dome of brick and mud. The local name is *kümbet*. They are a well-known example of building a complete roof without timber in a region where wood was scarce.\n\n## Form and construction\n\nEach unit is a cubical base topped by a conical dome. Walls are typically 50-60 cm (20-24 in) thick and domes 20-30 cm (8-12 in). Builders used stone, brick and mud; many modern houses reused bricks salvaged from Harran's ancient ruins. The domes are corbelled upward to a small opening at the top, which provides ventilation.\n\n## Climate\n\nThe thick walls and domes, together with the vent at the crown, keep the interiors comparatively comfortable during the extreme heat of the Harran plain in summer. Because the plaster is weak, the houses need repair every one to three years.\n\n## Age\n\nMost of the present houses date from the early 20th century and none is thought to be older than the mid-19th century. The tradition is much older: earlier domed or circular buildings existed at Harran, and Assyrian reliefs of the 7th century BC show similar domed structures. Harran itself was founded around 2500-2000 BC.\n\n## Today\n\nA count in 2002 recorded 2,760 beehive houses in the area, but only a few dozen remain in the old town. Most are now used as stores and barns; some were lived in until the 1980s. They have been under conservation since 1979, and the Harran ruins were placed on Turkey's tentative World Heritage list in 2000. Similar domed villages exist across the border in northern Syria.","key_facts":[{"label":"Local name","value":"Kümbet"},{"label":"Wall thickness","value":"50-60 cm (20-24 in)"},{"label":"Dome thickness","value":"20-30 cm (8-12 in)"},{"label":"Count (2002)","value":"2,760 houses"},{"label":"Maintenance","value":"Replastering every 1-3 years"}],"related":["roofing-in-turkey","roofing-in-syria","dome","mud-roof","trulli-of-alberobello"],"sources":[{"title":"Harran","url":"https://en.wikipedia.org/wiki/Harran","publisher":"Wikipedia"},{"title":"Architecture of Turkey","url":"https://en.wikipedia.org/wiki/Architecture_of_Turkey","publisher":"Wikipedia"}],"country":null},{"slug":"hassan-fathy","title":"Hassan Fathy","category":"history","type":"person","summary":"Egyptian architect (1900-1989) who revived Nubian mud-brick vaults and domes for low-cost housing, most famously at New Gourna near Luxor.","body":"Hassan Fathy (23 March 1900 - 30 November 1989) was an Egyptian architect who argued that earth, the cheapest material available to rural Egyptians, could provide durable, comfortable roofs without steel, cement or imported timber. His revival of the Nubian vault and dome made him one of the best-known advocates of vernacular building in the 20th century.\n\n## Life\n\nFathy was born in Alexandria and graduated in 1926 from King Fuad University (now Cairo University). He began teaching at the College of Fine Arts in 1930. He died at his home in Cairo in 1989.\n\n## Roofs without timber\n\nFathy aimed to replace Western materials such as steel, cement and glass with mud brick. For roofs he turned to the Nubian tradition of the southern Nile, where masons built barrel vaults and domes of mud brick without any formwork, laying inclined courses against an end wall (see Nubian vault). He combined vaults and domes with dense brick walls, courtyards and windcatchers for passive cooling.\n\n## New Gourna\n\nHis best-known project, New Gourna on the west bank at Luxor, was built between 1946 and 1952 to rehouse residents of Old Gourna, whose houses stood over the Theban tombs. The village used local earth as its main material, with Nubian-inspired vaulted roofs and enclosed courtyards. Fathy later called the \"Gourna Experiment\" a failure: many intended residents did not move in, and roughly 40% of the original buildings had been lost by the time the site was placed on the 2010 World Monuments Watch. UNESCO began a safeguarding project for the village in 2009 (see New Gourna).\n\n## Writing and other work\n\nHis account of the project, *Gourna: A Tale of Two Villages*, was published in a limited edition by Egypt's Ministry of Culture in 1969 and republished by the University of Chicago Press in 1973 as *Architecture for the Poor: An Experiment in Rural Egypt*. His *Natural Energy and Vernacular Architecture* (1986) deals with passive cooling and windcatchers. He also designed the adobe mosque and madrasa of Dar al-Islam near Abiquiu, New Mexico, completed in 1981.\n\n## Recognition\n\nFathy received the Aga Khan Chairman's Award for Architecture, the Right Livelihood Award and the Balzan Prize, all in 1980. The Nubian vault he championed has, since 2000, also been promoted for housing in the Sahel (see Nubian vault).","key_facts":[{"label":"Born","value":"23 March 1900, Alexandria, Egypt"},{"label":"Died","value":"30 November 1989, Cairo"},{"label":"Known for","value":"Reviving Nubian mud-brick vaults and domes"},{"label":"Key project","value":"New Gourna, Luxor (1946-1952)"},{"label":"Book","value":"Architecture for the Poor (1973; first published 1969)"}],"regions":["Africa","Middle East"],"aliases":["Hasan Fathy","Hassan Fathi"],"related":["nubian-vault","new-gourna","roofing-in-egypt","mud-roof","dome","badgir","middle-eastern-domes"],"company":null,"sources":[{"title":"Hassan Fathy","url":"https://en.wikipedia.org/wiki/Hassan_Fathy","publisher":"Wikipedia"},{"title":"Safeguarding Project of Hassan Fathy's New Gourna Village","url":"https://whc.unesco.org/en/activities/637","publisher":"UNESCO World Heritage Centre"},{"title":"Safeguarding Hassan Fathy's Architectural Legacy in New Gourna","url":"https://moic.gov.eg/en/project/289","publisher":"Egyptian Ministry of International Cooperation"}],"country":null},{"slug":"hauran-basalt-corbelled-roofs","title":"Hauran Basalt Corbelled Roofs","category":"history","type":"article","regions":["Middle East"],"company":null,"summary":"Flat roofs of long basalt slabs on corbels and stone arches, used in late antique towns of the Hauran in Jordan and Syria.","aliases":["Hawran stone roofs","basalt slab roof","Umm el-Jimal roofs","stone corbelled roof"],"body":"In the Hauran (Hawrān), the volcanic basalt region straddling southern Syria and northern Jordan, Roman and late antique builders roofed houses, churches and baths almost entirely in stone. Basalt is strong in compression and there was little timber, so roofs were made of long, thin basalt slabs carried on projecting stone corbels or on stone arches. The town of Umm el-Jimal in Jordan, and Bosra in Syria, are key examples.\n\n## Corbel-and-slab roofs\n\nCorbels were set into the walls so that they projected inward, often two or three rows one above another. Long basalt slabs were then laid from corbel tip to corbel tip, and thin slabs covered the remaining gap. This system roofed single- and multi-storey buildings and both rectangular and semicircular rooms. Corbels were set into pockets in the bearing walls to a depth of the full wall thickness or half of it.\n\n## Arch-and-slab roofs\n\nFor wider rooms, builders spanned the space with transverse arches of small dry-laid blocks and laid long, thin slabs between them, a method described as the \"arches supporting stone slab system\". Big arches were often tied to internal buttresses that carried their thrust down to the ground. Lightweight volcanic scoria was used for vaults and domes, with hydraulic lime mortar containing scoria.\n\n## Dated examples\n\n- **Bosra, South Bath (Syria):** 2nd-3rd century AD, with a semidome under a flat basalt slab.\n- **Umm el-Jimal (Jordan):** the Barracks Chapel has a corbelled flat apse roof built about a year after the Julianos Church of 345 AD. The town had about 15 churches in late antiquity.\n- **Lubbēn Large Church:** 417 AD, with a flat-roofed apse on transverse arches.\n- **Bosra Cathedral:** 512-513 AD.\n\nA major earthquake in 747 AD destroyed Umm el-Jimal. Because so many basalt buildings still stand roofless or partly roofed, the Hauran is an important region for the study of ancient stone roofing.\n\n## Context\n\nThese roofs are a stone relative of the corbelled timber darbazi roofs of Georgia and the corbelled domes found elsewhere. Their tall basalt walls also allowed buildings of two or three storeys.","key_facts":[{"label":"Material","value":"Basalt slabs; scoria for vaults"},{"label":"Systems","value":"Corbel-and-slab; arch-and-slab"},{"label":"Region","value":"Hauran, southern Syria and northern Jordan"},{"label":"Key sites","value":"Umm el-Jimal, Bosra"},{"label":"Umm el-Jimal destroyed","value":"Earthquake, 747 AD"}],"related":["roofing-in-jordan","roofing-in-syria","darbazi","flat-roof","stone-slate","khmer-corbel-vault"],"sources":[{"title":"Engineering the reconstruction of Hawrān's Ecclesiae during late antiquity: case of Julianos church in Umm el-Jimal, Jordan (Al Rabady and Rababeh, 2022)","url":"https://www.nature.com/articles/s40494-022-00727-0","publisher":"npj Heritage Science"},{"title":"Jordan's 'Umm al-Jimal' added to UNESCO heritage list","url":"https://www.wam.ae/en/article/141gmc8-jordan’s-umm-al-jimal-added-unesco-heritage-list","publisher":"WAM (Emirates News Agency)"}],"country":null},{"slug":"haus-tambaran","title":"Haus Tambaran","category":"world-roofing","type":"article","summary":"Sepik spirit house of Papua New Guinea: a men’s ceremonial house with a towering painted gable and a thatched roof sloping to the ground.","body":"A *haus tambaran* (Tok Pisin, \"spirit house\") is the ceremonial men's house of the Sepik region of Papua New Guinea, used for initiations, meetings and rituals connected with ancestral spirits. The best-known forms come from the Maprik area of East Sepik, home of the Abelam people, where the house is essentially a giant roof: a tall, painted front gable from which a ridge slopes down to the rear, with the thatch often continuing all the way to the ground.\n\n## Form and structure\n\nEthnographers Anthony Forge and Donald Tuzin, summarised by architects Mike Austin and Jeremy Treadwell, describe Maprik ceremonial houses as built directly on the ground on a triangular plan, with no walls, no floor and no central ridge post. Heavy wall plates sloping to the rear sit on posts sunk about 3 m (10 ft) into the ground. The massive ridge pole is raised, usually at dawn, onto temporary supports in a task that is both structural and ritual. A framework of slender bamboo rafters is then fixed in place and acts as a diaphragm; when the temporary props are removed, the rafters bow slightly under the ridge, giving the house its characteristic hunched profile.\n\nAnthropologist Brigitta Hauser-Schäublin records that Abelam ceremonial houses often reached heights of up to 30 m (about 100 ft) and were built by communal labour without nails, their members bound with vines and liana ropes. Another account gives heights of up to 25 m (82 ft) for the Abelam *korambo* and notes that its roof is thatched with sago palm fronds over a timber and bamboo structure with elaborate lashing. Only major hamlets had one, standing in front of a large ceremonial ground.\n\n## The gable\n\nThe front gable is the building's face. It is clad with richly painted bark panels that tower over the surrounding courtyards, and the interior is lined with large flat painted faces, *ngwalndu*, which represent ancestral spirits. The Sepik peoples are known for painting and carving, which are often displayed on these buildings.\n\n## Change and survival\n\nHaus tambaran have become less common as Christian fundamentalism has spread in the region. Their form has nevertheless become a national symbol: the entrance of the National Parliament House in Port Moresby, opened on 8 August 1984, is modelled on haus tambaran architecture and appears on the 50 kina banknote, and the Papua New Guinea High Commission in Canberra also draws on the form.\n\n## In museums\n\n- A haus tambaran from Apangai, Maprik District (1984), is held by the National Museum of Ethnology in Leiden.\n- The gable wall of an Abelam ceremonial house, taken down around 1975, was shipped to Germany, restored and displayed at the Naturhistorisches Museum Nürnberg.\n- The Humboldt Forum in Berlin displays a replica Abelam cult house with a painted gable and two initiation chambers.\n\n## Roofing significance\n\nThe haus tambaran shows how a lashed bamboo and timber frame, with no metal fixings, could span and roof a very tall, steep structure in a high-rainfall climate, and how a roof can carry a community's religious and social identity.","key_facts":[{"label":"Region","value":"Sepik, especially Maprik (Abelam), Papua New Guinea"},{"label":"Height","value":"Up to about 25-30 m (82-100 ft)"},{"label":"Roof covering","value":"Sago palm frond thatch"},{"label":"Structure","value":"Timber posts, massive ridge, bamboo rafters, vine lashing; no nails"},{"label":"Modern echo","value":"National Parliament House, Port Moresby (1984)"}],"regions":["Oceania"],"aliases":["Spirit house","Haus tambaran","Korambo","Abelam ceremonial house","Sepik men’s house"],"related":["roofing-in-papua-new-guinea","sago-palm-thatch","palm-thatch","thatch","wharenui","palauan-bai","maneaba"],"company":null,"sources":[{"title":"Haus Tambaran","url":"https://en.wikipedia.org/wiki/Haus_Tambaran","publisher":"Wikipedia"},{"title":"Constructing the Pacific Hut (Austin and Treadwell)","url":"https://interstices.ac.nz/index.php/Interstices/article/download/360/359","publisher":"Interstices"},{"title":"Ceremonial houses of the Abelam, Papua New Guinea (Hauser-Schäublin, 2016)","url":"https://publications.goettingen-research-online.de/handle/2/93823","publisher":"University of Göttingen"},{"title":"Abelam - Settlements","url":"https://www.everyculture.com/Oceania/Abelam-Settlements.html","publisher":"Countries and Their Cultures"},{"title":"Bamboo and Palm Leaf Cathedrals","url":"https://www.museum.de/en/audioguide/65/52/EN/0","publisher":"Naturhistorisches Museum Nürnberg (museum.de)"},{"title":"More than a roof over one’s head","url":"https://humboldtforum.org/en/buildings-from-oceania","publisher":"Humboldt Forum"},{"title":"National Parliament House, Port Moresby","url":"https://en.wikipedia.org/wiki/National_Parliament_House,_Port_Moresby","publisher":"Wikipedia"}],"country":null},{"slug":"hausa-earth-vaults-and-domes","title":"Hausa Earth Vaults and Domes","type":"article","summary":"Flat roofs, arches and domes of earth over cantilevered deleb-palm timber, built by Hausa master masons in northern Nigeria and Niger.","body":"Hausa builders of northern Nigeria and southern Niger developed a structurally ambitious earth-roofing tradition. Using only earth and short lengths of palm timber, they roofed rooms with flat roofs, arches, vaults and domes, some spanning more than 8 m (26 ft). The tradition is centred on old cities such as Kano, Zaria and Katsina.\n\n## Materials\n\n- **Azara**: split timber from the deleb palm (*Borassus*). It is light, resists termites, and its fibrous surface bonds well with mud.\n- **Tubali**: hand-formed conical or egg-shaped sun-dried mud bricks.\n- **Kasa**: clay-rich earth used for mortar and plaster.\n- **Tabo**: swamp mud, used for daubing and plaster.\n- **Burgi**: gravelly clay used for rammed earth.\n\n## Flat roofs\n\nFor ordinary rooms, lengths of azara span between walls and are covered with mud. Because deleb palm timber is short, wider rooms needed a different approach.\n\n## Arches and vaults\n\nThe Hausa arch, built from cantilevered azara, gets round the short-timber problem. The first piece is set upright in the wall; further pieces are laid at progressively flatter angles, each overhanging the last and bound with cord. Masons work from both walls at once until the two halves meet, then add a reinforcing layer of timber over the joint. The whole frame is daubed with mud. In palaces, these arches support vaults spanning over 8 m (26 ft) and up to about 9 m (30 ft) high, and some arches carry an upper storey.\n\n## Domes\n\nDomes (*tulluwa*) rest on intersecting half-arches and were built without centring, rising in layers from the top of round walls. Recorded examples include the dome at Kafin Madaki (1861), about 8.2 by 8.65 m (27 by 28 ft) and 6.75 m (22 ft) high, and the Soron Inglia hall in the Kano palace (1935), about 7.5 by 8.25 m (25 by 27 ft) and 9 m (30 ft) high. The architectural historian Labelle Prussin compared the structural logic of these domes to reinforced concrete.\n\n## Waterproofing and drainage\n\nDome surfaces were sealed with *laso*, a traditional render made from dye-pit residue, indigo liquor, ash and a sticky plant extract. It stays watertight for about five years before it must be renewed. Long projecting eaves (*indororo*) and spouts throw rainwater clear of the roof and walls, and decorative roof pinnacles (*zankwaye*) crown the parapets.\n\n## Builders\n\nBuilding was organised through a masons' guild under a chief builder, the *Sarkin Magina*, with master builders (*gwanaye*) who trained apprentices for about ten years.\n\n## The Zaria Friday Mosque\n\nBuilt in the late 1830s or early 1840s by the master builder Mallam Mikhaila, known as Babban Gwani, the Friday mosque at Zaria has a domed earth roof carried on massive piers and arches.\n\n## Change\n\nWestern construction forms were adopted quickly in the 20th century. Mosque roofs, traditionally of mud or thatch, are now often of metal sheet (\"tin\"). Some architects argue that modern materials used within traditional Hausa forms continue the masons' long habit of absorbing outside influences.","key_facts":[{"label":"Region","value":"Northern Nigeria and southern Niger"},{"label":"Key timber","value":"Azara (deleb palm)"},{"label":"Largest recorded domes","value":"About 8 m (26 ft) span"},{"label":"Dome render","value":"Laso, renewed about every 5 years"},{"label":"Landmark","value":"Zaria Friday Mosque, c. 1840"}],"regions":["Africa"],"aliases":["Hausa vault","Hausa dome","tulluwa","azara roof","Hausa mud roof"],"related":["roofing-in-nigeria","roofing-in-niger","sahelian-earthen-roofs","nubian-vault","dome","barrel-vault-roof","mud-roof"],"sources":[{"title":"Hausa urban architecture: construction and design in a cosmopolitan African society","url":"https://www.africanhistoryextra.com/p/hausa-urban-architecture-construction","publisher":"African History Extra"},{"title":"Hausa architecture","url":"https://en.wikipedia.org/wiki/Hausa_architecture","publisher":"Wikipedia"},{"title":"Architecture of Nigeria","url":"https://en.wikipedia.org/wiki/Architecture_of_Nigeria","publisher":"Wikipedia"},{"title":"Friday Mosque at Zaria","url":"https://archnet.org/sites/4180","publisher":"Archnet"}],"company":null,"category":"world-roofing","country":null},{"slug":"health-and-safety-executive","title":"Health and Safety Executive (HSE)","summary":"The HSE is Great Britain's workplace health and safety regulator; its roof work guidance says almost one in five construction deaths involve roof work.","body":"The Health and Safety Executive (HSE) is the national regulator for workplace health and safety in Great Britain. It publishes guidance, inspects workplaces and enforces the law. Roof work is one of its priority topics in construction. Its website is hse.gov.uk.\n\n## Roof work risks\n\nHSE describes all roof work as highly dangerous, even short jobs, and reports that almost one in five construction deaths involve roof work. The main causes are:\n\n- falls from roof edges or through openings;\n- falls through fragile roofs, such as old cement sheet or corroded metal;\n- falls through fragile rooflights, which can be hard to see in some light or when painted over.\n\n## Key guidance\n\n- **Plan the work.** Employers must organise and plan all roof work so it is done safely. A method statement is the usual way to manage the job and communicate precautions.\n- **Fragile roofs.** Every roof should be treated as fragile until a competent person confirms it is not. No sheeted roof, including ridges and purlins, should be assumed to bear a person's weight.\n- **Rooflights.** These should be protected with secured, labelled barriers or covers.\n- **Edge protection.** Sloping roofs generally need scaffolding or edge protection at the eaves. Flat roofs need a secure double guardrail and toe board. For very short tasks, secured ladders and roof ladders may be acceptable.\n- **Access.** Options include scaffolds, stair towers, scaffold towers, mobile elevating platforms, ladders and roof hatches.\n- **Competence.** Workers must be trained, competent and told about the precautions.\n\n## Legal framework\n\nRelevant laws include the Work at Height Regulations 2005, the Management of Health and Safety at Work Regulations and the Construction (Design and Management) Regulations 2015. HSE's detailed guidance on roofing is set out in its publication HSG33, *Health and safety in roof work*.\n\n## Comparison\n\nIn the United States, the Occupational Safety and Health Administration (OSHA) sets a 6-foot trigger height for fall protection in construction. British rules do not use a single trigger height; instead they require any work at height to be planned to prevent falls that could cause injury. Northern Ireland has its own regulator.","key_facts":[{"label":"Jurisdiction","value":"Great Britain"},{"label":"Roof work share of construction deaths","value":"Almost one in five"},{"label":"Key regulations","value":"Work at Height Regulations 2005; CDM 2015"},{"label":"Roof work guidance","value":"HSG33, Health and safety in roof work"}],"regions":["Europe"],"aliases":["HSE","Health and Safety Executive"],"related":["osha","fragile-roof","roofing-fall-protection","citb"],"company":{"website":"https://www.hse.gov.uk","known_for":["Roof work safety guidance","HSG33"]},"sources":[{"title":"Roof work","url":"https://www.hse.gov.uk/construction/safetytopics/roofwork.htm","publisher":"HSE"},{"title":"Work at height","url":"https://www.hse.gov.uk/work-at-height/","publisher":"HSE"}],"category":"organizations","type":"organization","country":null},{"slug":"heat-island-group","title":"Heat Island Group (Lawrence Berkeley National Laboratory)","type":"organization","summary":"A research group at Lawrence Berkeley National Laboratory in California that studies cool roofs, cool pavements and urban heat islands.","body":"The Heat Island Group is a research group within the Energy Technologies Area of Lawrence Berkeley National Laboratory (LBNL), a US Department of Energy national laboratory in Berkeley, California. It studies how surfaces such as roofs and pavements affect building energy use, urban temperatures and air quality, and it is one of the best-known sources of research on cool roofs.\n\n## Research topics\n\n- **Cool roofs:** measuring how solar reflectance and thermal emittance affect roof temperatures and building energy use.\n- **Cool colours:** pigments that reflect near-infrared sunlight while appearing dark, allowing cooler tile, shingle and metal products in traditional colours.\n- **Urban heat islands:** modelling how citywide changes in surface reflectance affect air temperature.\n- **Cool pavements** and other urban surfaces.\n- **Aging and soiling:** how reflectance declines with dirt and weather, and how to measure aged values.\n\n## Findings often cited\n\nThe group's public materials report that, on a typical summer afternoon, a clean white roof reflecting 80 percent of sunlight stays about 31 °C (55 °F) cooler than a grey roof reflecting 20 percent, and that a black roof was measured about 30 °C (54 °F) warmer than a white one. Its research also concluded that winter heating penalties from cool roofs are usually small compared with summer cooling savings across most of the United States.\n\nWidely cited studies by Hashem Akbari and colleagues, published in 2009 and 2012, estimated the global cooling effect of increasing roof and pavement reflectance, expressed as equivalent offsets of greenhouse gas emissions (24 gigatonnes for whitening urban flat roofs in warm climates in the 2009 study).\n\n## Influence\n\nIts online resources explain cool roof science for homeowners, builders and policymakers.","key_facts":[{"label":"Parent","value":"Lawrence Berkeley National Laboratory (US DOE)"},{"label":"Location","value":"Berkeley, California, USA"},{"label":"Focus","value":"Cool roofs, cool pavements, urban heat islands"}],"regions":["North America","Global"],"aliases":["LBNL Heat Island Group","Berkeley Lab Heat Island Group"],"related":["cool-roof","urban-heat-island","solar-reflectance","cool-roof-rating-council"],"company":{"headquarters":"Berkeley, California, United States","website":"https://heatisland.lbl.gov/","parent":"Lawrence Berkeley National Laboratory","known_for":["cool roof research","urban heat island research","cool colour pigments"]},"sources":[{"title":"Cool Roofs","url":"https://heatisland.lbl.gov/coolscience/cool-roofs","publisher":"Lawrence Berkeley National Laboratory, Heat Island Group"},{"title":"Cool roof (reflective surfaces)","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"}],"category":"climate-sustainability","country":null},{"slug":"hemming-tool","title":"Hemming Tool","category":"tools-equipment","type":"term","summary":"A sheet metal tool that folds a panel edge back on itself, forming the hems used at metal roof eaves, valleys, rakes and trims.","body":"A hem is an edge of sheet metal folded back on itself. In metal roofing, hems remove sharp cut edges, stiffen panel ends, and create the hooks that lock panels onto drip edges, cleats and valley flashings. Hemming tools are the hand and power tools used to form these folds, particularly at the ends of standing seam panels.\n\n## Hem types\n\n- **Closed hem**: folded flat against itself, giving a stiff, weather-resistant exposed edge.\n- **Open hem**: folded with a gap, often a teardrop or U-shape, so another piece of metal can slide in to form a connection.\n\n## Typical roofing uses\n\n- **Eave hem**: the bottom of each panel is notched and hemmed so it hooks over the eave flashing or drip edge, holding the panel down while allowing thermal movement.\n- **Valley hem**: panels meeting a valley are hemmed to engage the valley flashing or a cleat.\n- **Box or ridge-end turn-ups**: the upslope end of a panel is turned up or folded into a box at the ridge or headwall to stop water and wind-driven rain.\n- **Trim edges** on rakes, copings and flashing.\n\n## Tools\n\n- **Hand hemming tools**: wide-jawed folding tools sized for panel widths, often used with a mallet to set the hem.\n- **Hand seamers** for short or awkward hems.\n- **Portable brakes** for long, straight hems on flashing and trim.\n- **Power hemmers and eave tools** that notch and hem panel ends in fewer steps.\n- **Roll formers**, which can produce panels with pre-formed features in the shop or on site.\n\nMany hand hemming tools are rated for particular materials and thicknesses; one supplier notes that many are rated up to 24 gauge steel. Using a tool slightly wider than the panel pan helps keep the bend straight.\n\n## Good practice\n\nMark bend lines accurately, apply even pressure along the length, and avoid cracking the paint at tight radii, especially in cold weather. Notching the seam legs correctly before hemming lets the panel engage the eave cleanly. Installation instructions from the panel manufacturer define the required hem details for warranty compliance.","key_facts":[{"label":"Hem types","value":"Closed (flat) and open (teardrop or U)"},{"label":"Main roofing uses","value":"Eave, valley and ridge-end panel details"},{"label":"Tool range","value":"Hand hemmers, seamers, brakes, power hemmers"}],"regions":["Global"],"aliases":["panel hemmer","eave hemming tool","hemmer"],"related":["hand-seamer","sheet-metal-brake","standing-seam-metal-roof","drip-edge","power-seamer"],"company":null,"sources":[{"title":"Hemming tools for metal roofing","url":"https://www.stortz.com/hemming-tools-metal-roofing/","publisher":"John Stortz & Son"},{"title":"Hemming an Eave and Rake on a Standing Seam Metal Roof","url":"https://protradecraft.com/hemming-eave-and-rake-standing-seam-metal-roof","publisher":"Pro Trade Craft"},{"title":"Brake: Definition, Uses & Benefits in Roofing","url":"https://www.interlockroofing.com/glossary/brake/","publisher":"Interlock Roofing"}],"country":null},{"slug":"hemudu-stilt-houses","title":"Hemudu Stilt Houses","category":"history","type":"place","summary":"Raised timber houses of the Hemudu culture of Zhejiang, China, about 7,000 years old, with the earliest known Chinese mortise-and-tenon joints.","body":"The Hemudu culture flourished in the lower Yangtze region of eastern China from about 5500 to 3300 BCE. Its type site, near Yuyao in Zhejiang province and about 22 km (14 mi) northwest of Ningbo, was discovered in 1973. Related sites include Tianluoshan, also in Yuyao, and sites on the Zhoushan islands. In the wet, low-lying landscape of the Yangtze delta, the Hemudu people lived in long houses raised on stilts.\n\n## Raised houses\n\nThe houses stood on timber piles above damp ground, with communal longhouses common at Hemudu sites; they have been compared to the longhouses of present-day Borneo. Raising the floor would have kept people and stores above damp ground and seasonal water.\n\n## Timber joinery\n\nThe waterlogged soil preserved hundreds of worked timber components. Many carry sunmao joints, the Chinese term for mortise-and-tenon joinery, in which a projecting tenon fits a cut socket. They are described as the earliest known use of this joinery in Chinese timber-frame building. Mortise-and-tenon joinery later became the basis of the traditional Chinese timber frame.\n\n## Roofs\n\nNo Hemudu roof survives intact. Reconstructions show pitched roofs on the raised timber frames, but the covering material and pitch are inferred rather than preserved.\n\n## End of settlement\n\nTwo major floods changed the course of the nearby Yaojiang River and salinised the soil, forcing residents to abandon their settlements.\n\n## Significance for roofing history\n\nHemudu shows that by about 7,000 years ago builders in China were joining timbers with shaped joints rather than only lashing them. Jointed frames are stiffer and can carry heavier roof coverings, which is a precondition for the tiled roofs that later developed in the region.","key_facts":[{"label":"Culture","value":"Hemudu, about 5500-3300 BCE"},{"label":"Location","value":"Yuyao, Zhejiang, China"},{"label":"Discovered","value":"1973"},{"label":"House type","value":"Long houses raised on timber piles"},{"label":"Joinery","value":"Earliest known Chinese mortise-and-tenon (sunmao)"}],"regions":["East Asia"],"aliases":["Hemudu site","Hemudu ganlan houses","Hemudu pile dwellings"],"related":["banpo-houses","prehistory-of-roofing","roofing-in-china"],"company":null,"sources":[{"title":"Hemudu culture","url":"https://en.wikipedia.org/wiki/Hemudu_culture","publisher":"Wikipedia"},{"title":"Hemudu site (China Daily Ningbo)","url":"https://ningbo.chinadaily.com.cn/2023-11/28/c_942690.htm","publisher":"China Daily"}],"country":null},{"slug":"henry-company","title":"Henry Company","category":"manufacturers","type":"company","summary":"Henry is a North American building envelope brand dating to 1933, known for roof coatings, cements and air barriers, owned by Carlisle since 2021.","body":"Henry Company is a North American manufacturer of roofing, waterproofing and building envelope products. The brand dates from 1933. Carlisle Companies acquired Henry in 2021, its largest acquisition, and Henry now operates as a brand of Carlisle Weatherproofing Technologies.\n\n## Products\n\nHenry's range spans several parts of the building envelope:\n\n- **Roof coatings**: acrylic, aluminium, asphalt and silicone coatings, plus spray polyurethane foam, used mainly to restore and extend the service life of existing low-slope roofs.\n- **Mastics, cements and sealants** for roof repairs, flashings and penetrations.\n- **Air and vapour barriers**: fluid-applied and self-adhered membranes in vapour-permeable and impermeable versions, with matching flashings, primers and sealants. Its products include the Blueskin line.\n- **Roofing systems**: polyiso insulation and single-ply TPO and EPDM membranes.\n- **Waterproofing** for below-grade and plaza applications, waterstops, and housewraps and water-resistive barriers for homes.\n\n## Role in the building envelope\n\nRoof coatings are typically applied over existing membranes, metal or modified-bitumen roofs to seal minor defects, add reflectivity and delay full replacement, which is why coatings manufacturers such as Henry are closely tied to the roof maintenance and restoration market. Air barriers, a separate Henry speciality, control air leakage through walls and roof-wall junctions and are addressed in North American energy codes.\n\n## Ownership\n\nUnder Carlisle, Henry forms a core part of the Weatherproofing Technologies segment, which complements Carlisle's membrane-focused Construction Materials segment. Henry describes itself as a leader in building envelope systems in North America. Its range serves both commercial buildings and homes. Product data sheets are published online.","key_facts":[{"label":"Since","value":"1933"},{"label":"Parent","value":"Carlisle Companies (acquired 2021)"},{"label":"Segment","value":"Carlisle Weatherproofing Technologies"},{"label":"Products","value":"Roof coatings, cements, air barriers, waterproofing"}],"regions":["North America"],"aliases":["Henry","Henry Building Envelope Systems"],"related":["silicone-roof-coating","vapor-retarder","carlisle-companies","roof-coating"],"company":{"founded":"1933","website":"https://www.henry.com","parent":"Carlisle Companies","known_for":["Roof coatings","Roof cements and mastics","Blueskin air barriers"]},"sources":[{"title":"Henry","url":"https://www.henry.com/","publisher":"Henry Company"},{"title":"Carlisle Companies","url":"https://en.wikipedia.org/wiki/Carlisle_Companies","publisher":"Wikipedia"}],"country":null},{"slug":"hidmo","title":"Hidmo","category":"world-roofing","type":"term","summary":"Traditional rectangular stone house of Tigray (Ethiopia) and highland Eritrea, with timber ceilings carried on posts and a flat roof of soil.","body":"The hidmo (Tigrinya, also written hïdmo) is the traditional house of the northern Ethiopian and Eritrean highlands. It has thick masonry walls of stone and mud, a timber ceiling held up by interior posts, and a flat roof made of soil. It is found in the Tigray Region of Ethiopia and in Eritrea's highlands and parts of the eastern escarpment.\n\n## Roof construction\n\nBeams rest on the walls and on large timber posts inside the house; the number of posts depends on the size of the house. The beams are covered with rods and branches, and soil is spread over them to form the roof. Building such a roof consumes a great deal of timber, so gathering wood is one of the largest tasks in constructing a hidmo. In Ïnderta in south-eastern Tigray, where stone was easy to obtain but wood scarce, a house that used more wood carried more prestige.\n\n## Performance\n\nThick walls, ceiling and roof, together with few openings, keep the indoor environment stable.\n\n## Plan and spaces\n\nA hidmo is organised around a main room (*midri-biet*) for living, eating and sleeping, with built-in stone-and-mud beds, benches and shelves. Other spaces include an entrance porch (*gebela*), a women's kitchen area (*wushate*) and a roofed animal shelter (*dembe*). In Eritrea the house is usually built by the owner with unpaid help from neighbours, who are thanked with a party.\n\n## Research\n\nA 2019 study by Shimizu, Ephrem Telele, Alula Tesfay and Miyake in *Nilo-Ethiopian Studies* documented the parcel layout, spatial components and building elements of the hidmo in Ïnderta and discussed the hierarchy of its spaces.\n\n## Today\n\nHidmo houses remain a recognised part of Tigray's and Eritrea's architectural heritage, and a Tigray tourism website promotes surviving examples in Mekelle. For the spread of corrugated iron in the region, see Roofing in Ethiopia.","key_facts":[{"label":"Region","value":"Tigray (Ethiopia) and highland Eritrea"},{"label":"Walls","value":"Stone and mud masonry"},{"label":"Roof","value":"Flat soil roof on branches and timber beams"},{"label":"Main room","value":"Midri-biet"}],"regions":["Africa"],"aliases":["hïdmo","hedmo","Tigrayan stone house"],"related":["roofing-in-ethiopia","roofing-in-eritrea","flat-roof","mud-roof","sod-roof","tukul"],"company":null,"sources":[{"title":"Fundamentals of Hïdmo in Ïnderta: A Traditional House Type in Tigray Region, Ethiopia","url":"https://www.jstage.jst.go.jp/article/niloethiopian/2019/24/2019_17/_article/-char/en","publisher":"Nilo-Ethiopian Studies (J-STAGE)"},{"title":"Hidmo: A traditional house in Eritrean highlands","url":"https://www.africa-press.net/eritrea/?p=2883","publisher":"Africa-Press"},{"title":"Exploring the Timeless Charm of Mekelle's Hidmo Houses","url":"https://mail.tourismtigrai.com/attraction/view/MTM2","publisher":"tourismtigrai.com"}],"country":null},{"slug":"roof-hip","title":"Hip (Roof)","category":"components","type":"term","summary":"A hip is the external, sloping edge formed where two roof planes meet at an outside corner, running from the eaves up to the ridge.","body":"A hip is the outward-projecting angle formed where two adjacent sloping roof planes meet at an external corner of a building. Unlike the horizontal ridge, a hip slopes, running from the corner of the eaves up to the ridge or to the apex of the roof. Roofs with hips on all corners are called hip (or hipped) roofs. The inward-facing equivalent, where two slopes meet at an internal corner, is a valley.\n\n## Framing\n\nIn stick-framed roofs, a hip rafter runs diagonally along the line of the hip, from the wall-plate corner to the ridge. Because it is longer than the common rafters and set at a lower pitch, it is cut with compound angles. Shortened jack rafters run from the wall plate up to the hip rafter. In medieval and traditional British carpentry, the foot of the hip rafter often sits on a dragon beam that projects diagonally from the corner. Truss roofs form hips using a set of stepped hip trusses or girder trusses with jack trusses.\n\n## Covering the hip\n\nHips are capped much like ridges:\n\n- **Hip tiles** in clay or concrete, fixed over the joint and secured at the bottom with a hip iron in UK tradition. Bonnet hip tiles and bonnet-shaped plain tiles are traditional alternatives.\n- **Hip cap shingles** on asphalt roofs, installed from the bottom up so each overlaps the one below.\n- **Formed metal hip caps** on metal roofs.\n- **Mitred or close-cut hips** in slate, with concealed soakers beneath.\n\n## Performance\n\nBecause water runs away from a hip rather than toward it, hips are less vulnerable to leaks than valleys, though wind uplift on hip tiles is a concern. Hipped roofs in general perform better in high winds than gable-ended roofs.","key_facts":[{"label":"Opposite of","value":"Valley"},{"label":"Framing member","value":"Hip rafter"},{"label":"Covering","value":"Hip tiles, hip cap shingles, metal caps"}],"regions":["Global"],"aliases":["hip","hip line","hip rafter"],"related":["hip-roof","roof-valley","roof-ridge","rafter"],"company":null,"sources":[{"title":"Rafter","url":"https://en.wikipedia.org/wiki/Rafter","publisher":"Wikipedia"},{"title":"Hip roof","url":"https://www.britannica.com/technology/hip-roof","publisher":"Encyclopaedia Britannica"},{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"}],"country":null},{"slug":"hip-roof","title":"Hip Roof","category":"roof-forms","type":"article","summary":"A hip roof slopes down to the eaves on all sides, with no vertical gable ends; on a rectangular plan it has two trapezoidal and two triangular faces.","body":"A hip (or hipped) roof is a roof in which every side slopes down toward the walls, so the eaves run around the whole building and there are no gables. On a rectangular building the two long sides are trapezoids meeting at a ridge, and the two short ends are triangles; the external corners where faces meet are the hips. On a square plan the faces meet at a single point, forming a pyramid roof.\n\n## Variants\n\n- **Simple hip:** four planes, usually of equal pitch.\n- **Cross-hipped:** two hip roofs joined in an L or T plan, with valleys at the junction; UK writers sometimes call this a hip-and-valley roof.\n- **Pyramid hip:** all four faces meeting at a point on a square plan.\n- **Half-hip (jerkinhead) and Dutch gable:** hybrids combining a hip and a gable.\n- **Mansard:** a hip roof with two slopes on each side.\n\n## Advantages\n\n- **Wind resistance:** with no flat gable walls and with edges braced by the hips, hip roofs generally perform better in hurricanes and strong winds than gable roofs, and are widely used in cyclone- and hurricane-prone regions.\n- **Eaves all round:** overhangs on every side shade and protect all the walls.\n- **Stable:** the inward slope of all faces makes the structure self-bracing.\n\n## Disadvantages\n\n- More complex framing, with hip and jack rafters or a set of hip trusses.\n- Less attic volume than a gable roof of the same pitch, and no gable walls for windows or louvres.\n- Short ridges limit the length available for ridge vents, so hip vents or individual roof vents may be needed.\n- More hips and valleys to cap and flash than a simple gable.\n\n## Global use\n\nHip roofs are widespread in the UK, Europe, Australia and North America for houses, and form the basis of traditional Chinese, Korean and Japanese roofs, including the hip-and-gable (irimoya) form.","key_facts":[{"label":"Faces (rectangle)","value":"Two trapezoids, two triangles"},{"label":"Gables","value":"None"},{"label":"Strength","value":"Good wind performance"}],"regions":["Global"],"aliases":["hipped roof","hip-roofed","four-sided roof"],"related":["roof-hip","gable-roof","pyramid-roof","jerkinhead-roof","dutch-gable-roof","mansard-roof","irimoya"],"company":null,"sources":[{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"},{"title":"Hip roof","url":"https://www.britannica.com/technology/hip-roof","publisher":"Encyclopaedia Britannica"},{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"}],"country":null},{"slug":"hiring-a-roofer","title":"Hiring a Roofer","category":"installation","type":"article","summary":"Hiring a roofer involves checking licensing or registration, insurance, references and written terms; licensing rules differ by country, state and province.","body":"Choosing a roofing contractor is often the biggest factor in how well a new roof performs, since most roof problems trace back to installation. The checklist below is neutral and general. Licensing and consumer protection rules differ between countries and often between states, provinces and cities, so local requirements should always be checked.\n\n## Licensing and registration\n\n- **United States.** Requirements are set by states and sometimes cities. For example, Oklahoma requires roofing contractors to register with its Construction Industries Board, and Minnesota licenses residential contractors through its Department of Labor and Industry. Some states have no state-level roofing licence.\n- **Canada.** Rules are provincial and municipal; workers' compensation coverage and safety training are commonly required.\n- **United Kingdom.** There is no specific roofing licence, but government-endorsed **TrustMark** registration and trade association membership show that a business has been vetted. Building control or a competent person scheme may be needed for some work.\n- **Australia and New Zealand.** Licensing and registration for roofing and building work vary by state, territory and work value.\n\n## Checklist\n\n1. **Verify licence or registration** where required, and confirm it covers roofing.\n2. **Check insurance**: liability insurance and workers' compensation or employer's liability.\n3. **Ask for references** and look at completed local jobs.\n4. **Get several written quotes** with the same scope, materials and details.\n5. **Confirm the scope**: tear-off or overlay, deck repairs (and their unit price), underlayment, ice barrier, flashings, ventilation, disposal and clean-up.\n6. **Permits**: who applies and pays.\n7. **Warranties**: obtain both the manufacturer's warranty terms and the contractor's workmanship warranty in writing.\n8. **Payment schedule**: avoid paying most of the price before work begins; link payments to progress.\n9. **Safety**: ask how workers will be protected from falls.\n10. **Written contract**: start and finish dates, change-order process, and how hidden damage will be handled.\n\n## Warning signs\n\nDoor-to-door offers after storms, pressure to sign immediately, requests for full payment in cash, no fixed business address and reluctance to put terms in writing are commonly cited warning signs.\n\n## Manufacturer and trade credentials\n\nMany manufacturers run contractor credential programmes, and trade associations such as NRCA in the United States, CRCA in Canada and national federations elsewhere maintain member directories. Membership shows participation in the association; it does not by itself confirm the quality of a contractor's work.","key_facts":[{"label":"Licensing","value":"Varies by country, state, province and city"},{"label":"Key documents","value":"Licence or registration, insurance, written contract, warranties"},{"label":"UK vetting scheme example","value":"TrustMark"}],"regions":["Global"],"aliases":["choosing a roofer","roofing contractor selection","how to hire a roofing contractor"],"related":["roofing-warranty-types","roofing-permits-and-inspections","roof-replacement-process","roofing-fall-protection"],"company":null,"sources":[{"title":"TrustMark","url":"https://www.trustmark.org.uk/","publisher":"TrustMark"},{"title":"Roofing FAQs","url":"https://www.normanok.gov/sites/default/files/documents/2023-07/roofing_faqs.pdf","publisher":"City of Norman, Oklahoma"},{"title":"Reroofing","url":"https://www.bloomingtonmn.gov/sites/default/files/2023-08/Reroofing.pdf","publisher":"City of Bloomington, Minnesota"},{"title":"National Roofing Contractors Association","url":"https://www.nrca.net/","publisher":"NRCA"},{"title":"Canadian Roofing Reference Manual","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"historic-england","title":"Historic England","summary":"Historic England is the public body that advises on England's historic environment, including the care and repair of historic roofs. It was formed in 2015.","body":"Historic England is a non-departmental public body sponsored by the UK Department for Culture, Media and Sport. It was formed on 1 April 2015 as the successor to the statutory functions of English Heritage, which had operated under that name since 1984. The management of the national collection of historic sites passed to a separate charity, the English Heritage Trust. Historic England's head office is in Swindon, and its website is historicengland.org.uk.\n\n## Role\n\nHistoric England protects and advises on England's historic environment. It:\n\n- maintains the National Heritage List for England, which includes listed buildings and scheduled monuments;\n- advises government and local planning authorities as a statutory consultee;\n- produces technical advice, guidance and training for owners and heritage professionals;\n- publishes research such as the annual Heritage at Risk register.\n\nHistoric England does not itself grant consent for alterations to listed buildings; that is the responsibility of local planning authorities, with Historic England advising on more significant cases.\n\n## Relevance to roofing\n\nRoofs are among the most important and most often altered parts of historic buildings. Historic England provides technical guidance used by roofers, architects and owners on traditional roofing, including:\n\n- natural slate and stone slate roofs, and sourcing matching materials;\n- clay plain tiles and pantiles;\n- thatch, including material choice and regional styles;\n- sheet lead and other metal roof coverings, including theft of lead and suitable replacements;\n- roof timbers, ventilation and moisture in historic buildings.\n\nChanging a roof covering on a listed building, for example from thatch to tile, or from natural slate to a man-made product, usually requires listed building consent. Like-for-like repairs are encouraged.\n\n## Other UK nations and countries\n\nScotland (Historic Environment Scotland), Wales (Cadw) and Northern Ireland have separate heritage bodies. Many other countries have similar national heritage agencies that publish roofing conservation guidance, such as the U.S. National Park Service's Preservation Briefs.","key_facts":[{"label":"Formed","value":"1 April 2015"},{"label":"Predecessor","value":"English Heritage (statutory functions)"},{"label":"Head office","value":"Swindon, England"},{"label":"Type","value":"Non-departmental public body"}],"regions":["Europe"],"aliases":["English Heritage (pre-2015)"],"related":["natural-slate","thatch","lead-roofing","national-society-of-master-thatchers"],"company":{"founded":"2015","headquarters":"Swindon, England","website":"https://historicengland.org.uk","known_for":["National Heritage List for England","Heritage technical advice"]},"sources":[{"title":"Historic England","url":"https://en.wikipedia.org/wiki/Historic_England","publisher":"Wikipedia"},{"title":"Historic England publications","url":"https://historicengland.org.uk/images-books/publications/","publisher":"Historic England"}],"category":"organizations","type":"organization","country":null},{"slug":"history-of-asbestos-cement-roofing","title":"History of Asbestos Cement Roofing","category":"history","type":"article","summary":"Asbestos cement sheets and slates, patented by Ludwig Hatschek in 1900 and sold as Eternit, roofed buildings worldwide until health risks led to bans.","body":"**Asbestos cement** (also called fibro, AC sheet or by trade names such as Eternit) is a composite of cement reinforced with asbestos fibres, pressed into thin sheets. In the 20th century it was one of the world's most widely used roofing materials, made into corrugated sheets, flat slates and shingles. Its decline followed recognition that asbestos fibres cause fatal diseases.\n\n## Invention\n\nThe Austrian industrialist **Ludwig Hatschek** patented the production process in **1900** (some sources give 1901). He mixed roughly 90% cement and 10% asbestos fibre with water and ran it through a machine adapted from cardboard making to form thin, strong sheets. In **1903** he named the product **Eternit**, from the Latin *aeternus*, \"eternal\". Rather than build most factories himself, Hatschek sold licences, and by 1910 Eternit factories existed in many countries.\n\n## Spread\n\nAsbestos cement was cheap, light, fire-resistant and watertight. Products included corrugated roofing sheets (such as the \"Super Six\" profile), flat sheets, pipes and moulded items, and slates and shingles imitating natural slate. It was used extensively for quick military buildings in the Second World War and became a common affordable cladding afterwards. Australia and New Zealand were among the heaviest users; there James Hardie was the main maker until the mid-1980s. On roofs it was particularly common on industrial, farm and garage buildings.\n\n## Health and bans\n\nBy the 1970s, exposure to asbestos was widely linked to asbestosis and mesothelioma. Weathering, cutting and drilling release fibres, and roof sheets are especially exposed to erosion. From the 1970s asbestos use became progressively restricted in many countries, and cellulose and other fibres were developed as replacements in the 1980s. Asbestos-containing fibro has since been banned in several countries, including Australia, though asbestos is still used in building materials in some others.\n\n## Legacy\n\nMany asbestos cement roofs remain in place. Because cutting, drilling and weathering release fibres, disturbing old sheets carries health risks, and removal is regulated in many countries. Modern **fibre cement** uses the same Hatschek process with non-asbestos fibres, and the Eternit trademark survives with the Belgian group Etex.\n\n## National bans\n\nBans came at different times. Great Britain banned white (chrysotile) asbestos in 1999, Australia banned the import and use of all asbestos from 31 December 2003, and Canada prohibited most asbestos products from 30 December 2018. In the United States, the Environmental Protection Agency finalised a ban on the ongoing uses of chrysotile asbestos in March 2024. The Australian ban did not cover materials already in place, and in many countries existing asbestos-cement roofs may stay until they are removed under regulated conditions.","key_facts":[{"label":"Patent","value":"1900, Ludwig Hatschek"},{"label":"Eternit name","value":"1903 (from Latin aeternus)"},{"label":"Original mix","value":"About 90% cement, 10% asbestos"},{"label":"Health concerns widespread","value":"By the 1970s"}],"regions":["Global","Europe","Oceania"],"aliases":["fibro","AC sheeting","asbestos roofing history","Eternit"],"related":["ludwig-hatschek","spread-of-corrugated-iron"],"company":null,"sources":[{"title":"Ludwig Hatschek","url":"https://en.wikipedia.org/wiki/Ludwig_Hatschek","publisher":"Wikipedia"},{"title":"Fibre cement","url":"https://en.wikipedia.org/wiki/Fibre_cement","publisher":"Wikipedia"},{"title":"Asbestos cement","url":"https://en.wikipedia.org/wiki/Asbestos_cement","publisher":"Wikipedia"},{"title":"Eternit","url":"https://en.wikipedia.org/wiki/Eternit","publisher":"Wikipedia"},{"title":"Asbestos and the law","url":"https://en.wikipedia.org/wiki/Asbestos_and_the_law","publisher":"Wikipedia"},{"title":"Biden-Harris Administration Finalizes Ban on Ongoing Uses of Asbestos to Protect People from Cancer","url":"https://www.epa.gov/newsreleases/biden-harris-administration-finalizes-ban-ongoing-uses-asbestos-protect-people-cancer","publisher":"U.S. Environmental Protection Agency"}],"country":null},{"slug":"history-of-asphalt-shingles","title":"History of Asphalt Shingles","category":"history","type":"article","summary":"Asphalt shingles were first cut from surfaced roll roofing around 1901-1903 in the United States and became North America's most common house roof.","body":"Asphalt shingles are the most common roof covering on houses in North America. They began in the United States around the turn of the 20th century as a cheaper, more fire-resistant alternative to wood shingles and slate.\n\n## Roll roofing forerunners\n\nComposition roofing developed in the United States in the mid-19th century. In the 1840s Samuel and Cyrus Warren of Cincinnati made roofing from cotton fabric coated with pine tar and sand. In the last quarter of the 19th century, built-up roofing components were adapted into factory-made rolls called \"ready roofing\", now known as roll roofing. An asphalt prepared roofing appeared in 1893, and slate granules were added to its surface in 1897.\n\n## The first shingles\n\nThe usual account credits **Reynolds of Grand Rapids, Michigan**, with hand-cutting stone-surfaced roll roofing into individual shingles in **1903**. Sources disagree on his first name: the US National Park Service gives Herbert M. Reynolds, while the National Roofing Museum and others give Henry M. Reynolds. Some sources also say material was first cut into strip shingles in 1901, and one manufacturer's history notes that other people and companies claimed to be making shingles at about the same time.\n\n## Rapid growth\n\n- **1906:** Bird and Son marketed a notched shingle that looked like two shingles when laid.\n- **By 1911:** asphalt shingles were in general use in parts of the US.\n- **1916:** the National Board of Fire Underwriters called for wood shingles to be eliminated as a fire hazard, boosting asphalt.\n- **First World War:** asphalt shingles used non-strategic materials and shipped more easily than wood or slate.\n- **1926:** Sears, Roebuck promoted slate-surfaced asphalt shingles in its house catalogue.\n- **By 1935:** all major makers offered the 12 by 36 in (305 by 914 mm) multi-tab strip, still the standard format; ceramic-coated granules broadened the colour range.\n- **1939:** 32 manufacturers produced about 11 million squares.\n\n## Fibreglass and laminates\n\nOrganic felt mats were gradually replaced by fibreglass. A fibreglass mat was introduced around 1960 with limited success; manufacturers switched in the 1970s and 1980s, and by 1982 fibreglass shingles had overtaken organic ones. Laminated, or architectural, shingles appeared in the 1970s and are steadily displacing flat three-tab shingles.","key_facts":[{"label":"First shingles","value":"1903, Grand Rapids, Michigan (most sources)"},{"label":"Inventor's name","value":"Disputed: Henry M. or Herbert M. Reynolds"},{"label":"Standard strip by 1935","value":"12 x 36 in (305 x 914 mm)"},{"label":"Fibreglass overtakes organic","value":"By 1982"}],"regions":["North America"],"aliases":["asphalt shingle history","composition shingle history"],"related":["history-of-roll-roofing","history-of-built-up-roofing","history-of-roofing-fire-regulations","asphalt-shingle"],"company":null,"sources":[{"title":"Asphalt Shingles - Roofing Exhibit","url":"https://www.nps.gov/crps/tps/roofingexhibit/asphalt.htm","publisher":"U.S. National Park Service"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Early Asphalt Litigation Helps Shape the Industry","url":"https://nationalroofingmuseum.org/early-asphalt-litigation-helps-shape-the-industry/","publisher":"National Roofing Museum"},{"title":"The History of Asphalt Shingles","url":"https://www.iko.com/blog/the-history-of-asphalt-shingles/","publisher":"IKO"}],"country":null},{"slug":"history-of-built-up-roofing","title":"History of Built-Up Roofing","category":"history","type":"article","summary":"Built-up roofing, the layered 'tar and gravel' roof of felts and bitumen, developed in 19th-century America and dominated flat roofs for decades.","body":"A **built-up roof (BUR)** is made on site from several layers, or plies, of reinforcing felt bonded together with hot bitumen, usually finished with a flood coat and gravel. It is often called a \"tar and gravel\" roof. For much of the 20th century it was the standard covering for commercial flat roofs in North America.\n\n## Origins\n\nFlat roofs are ancient, characteristic of the dry climates of Egypt, Persia and Arabia, where mud and plaster sufficed. Wetter climates needed a true waterproof layer. In the 1840s the Warren brothers of Cincinnati produced composition roofing from fabric coated with pine tar and sand, an early form of layered roofing. By the late 19th century built-up components were also being combined into factory-made roll roofing.\n\n## Coal tar and asphalt\n\nTwo bitumens dominated:\n\n- **Coal tar pitch**, a by-product of coke making, heated and mopped between layers of tar paper, usually on slopes of 1/4 in per foot (about 2%) or less. Coal tar roofs commonly last 50-70 years, and some have performed for more than a century.\n- **Asphalt**, a by-product of oil refining, graded into four types (I to IV) by the slope it suits.\n\nBUR systems dating from the early 1900s are still reported in service, though that claim is not well documented.\n\n## Gravel\n\nGravel or slag embedded in the top coat protects the bitumen from ultraviolet light, hail and foot traffic, and originally also helped hold the roof down.\n\n## Performance\n\nRoofers often quote 20-30 years for tar-and-gravel roofs. Studies give averages of 12-27 years, with some exceptional roofs lasting up to 120 years.\n\n## Competition\n\nFrom the 1960s onward BUR faced competition from new systems:\n\n- **Modified bitumen**, developed in Europe (APP from Italy and SBS from France). Sources differ on the date, giving the mid-1960s or the 1970s; US development followed in the late 1970s and early 1980s.\n- **Single-ply membranes** such as EPDM, PVC and, from the early 1990s, TPO.\n\nHot-applied BUR remains in use, but its share of new low-slope roofing has fallen as single-ply and modified bitumen have grown.","key_facts":[{"label":"Common name","value":"Tar and gravel roof"},{"label":"Typical slope","value":"1/4 in per foot (about 2%) or less"},{"label":"Coal tar roof life","value":"Commonly 50-70 years"},{"label":"Studied BUR averages","value":"12-27 years"}],"regions":["North America","Global"],"aliases":["BUR history","tar and gravel roof history"],"related":["history-of-roll-roofing","history-of-single-ply-membranes","built-up-roofing","modified-bitumen-roofing"],"company":null,"sources":[{"title":"Built-up roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"},{"title":"Membrane roofing","url":"https://en.wikipedia.org/wiki/Membrane_roofing","publisher":"Wikipedia"},{"title":"The History of Asphalt Shingles","url":"https://www.iko.com/blog/the-history-of-asphalt-shingles/","publisher":"IKO"}],"country":null},{"slug":"history-of-cool-roofs","title":"History of Cool Roofs","category":"history","type":"article","summary":"Cool roofs reflect sunlight to stay cooler; research at Lawrence Berkeley National Laboratory and the Cool Roof Rating Council (1998) shaped modern practice.","body":"A **cool roof** is a roof surface designed to reflect more sunlight and emit more absorbed heat than a conventional dark roof, so it stays cooler in the sun. Light-coloured and whitewashed roofs have long been used in hot climates, but the modern cool roof movement, with measured reflectance and policy targets, dates from the 1990s.\n\n## Traditional practice\n\nWhitening roofs to reflect heat is an old practice in hot regions. A modern example is the greenhouse district of south-eastern Spain, where farmers whitewash roofs in summer; a 2008 study linked the expansion of these whitened greenhouses to a regional cooling of about 1.6 °C (2.9 °F) over 20 years.\n\n## Research foundations\n\nThe **Heat Island Group** at Lawrence Berkeley National Laboratory (LBNL) in California, including Arthur Rosenfeld and Hashem Akbari, studied how dark roofs and pavements heat cities and raise air-conditioning demand. A 1997 study by Bretz and Akbari examined the long-term performance of high-albedo roof coatings. A 2001 LBNL-led study of a Texas retail building retrofitted with a white vinyl roof measured a large drop in surface temperature and about 11% less air-conditioning energy.\n\n## Rating and policy\n\n- **1998:** the **Cool Roof Rating Council** (CRRC) was established to develop methods for measuring and labelling the radiative properties of roofing products. It added wall products in 2019 and pavement products in 2024.\n- **2005:** California's energy efficiency standards encouraged reflective roofs.\n- **2009:** New York City launched **NYC CoolRoofs** under PlaNYC; it coated its 500th building in 2013. Akbari, Menon and Rosenfeld published \"Global Cooling\", arguing reflective roofs could offset carbon emissions.\n- **2010:** the US Department of Energy announced cool roofs for its facilities.\n- **2011:** a Columbia University study found white roofs in New York averaged 43 °F (about 24 °C) cooler than black roofs.\n\n## Debate\n\nNot all assessments are positive. A 2009 Royal Society report ranked white roofs among the less effective and more expensive climate engineering options, and studies such as Georgescu et al. (2014) found regional trade-offs, including possible effects on rainfall.\n\n## New materials\n\nResearch continues into pigments that stay cool in colour, including LBNL work on fluorescent ruby red (2016) and Egyptian blue (2018).","key_facts":[{"label":"CRRC founded","value":"1998"},{"label":"NYC CoolRoofs launched","value":"2009"},{"label":"White vs black roof (NYC study)","value":"About 24 °C (43 °F) cooler"},{"label":"Texas retrofit energy saving","value":"About 11% (2001)"}],"regions":["Global","North America","Europe"],"aliases":["reflective roof history","white roof history","high albedo roofs"],"related":["history-of-green-roofs","cool-roof","solar-reflectance-index","urban-heat-island"],"company":null,"sources":[{"title":"Reflective surfaces (climate engineering)","url":"https://en.wikipedia.org/wiki/Reflective_surfaces_(climate_engineering)","publisher":"Wikipedia"},{"title":"About the Cool Roof Rating Council","url":"https://coolroofs.org/about","publisher":"Cool Roof Rating Council"}],"country":null},{"slug":"history-of-copper-roofs","title":"History of Copper Roofs","category":"history","type":"article","summary":"Copper has roofed temples, cathedrals and castles for centuries, prized for its long life and the green patina it develops over decades.","body":"Copper is one of the longest-lasting roofing metals. Exposed to air it forms a thin protective film that slowly turns from bright orange-brown to dark brown and finally to the familiar blue-green patina. Many historic copper roofs have lasted for centuries.\n\n## Early use\n\nHistories of copper in architecture report copper roof shingles on the Lovamahapaya temple in Sri Lanka in the 3rd century BCE.\n\nThe Pantheon in Rome is sometimes listed as an early copper roof dated 27 BCE. That year belongs to the original temple begun by Agrippa, which was later destroyed by fire. The present Pantheon is a complete rebuilding completed under Hadrian in the early 2nd century CE (about 113-125 CE, possibly begun under Trajan; Britannica gives 118-128), and its dome was covered not with copper but with bronze tiles, described in some sources as gilded. The Byzantine emperor Constans II stripped them in 663 CE, and the dome was later covered with lead sheets.\n\n## Medieval and Renaissance Europe\n\n- **Hildesheim Cathedral**, Germany, received a copper roof in 1280. Sources disagree on its fate: one says the roof survives, while another says it was destroyed by Second World War bombing.\n- **Kronborg Castle**, Denmark, was roofed in copper in 1585; its tower copper was renovated in 2009.\n\n## How the patina forms\n\n- Within about six months an oxide film becomes noticeable, evening out after about nine months.\n- Over the first few years sulfide films darken the surface to brown and then to dull grey or black.\n- The blue-green sulfate patina then develops: in about 7-9 years in marine climates, 15-25 years in industrial areas and 10-30 years in clean rural air. In very dry climates it may never form.\n\nOnce the patina is established, corrosion averages about 0.0001-0.0003 mm per year. On a 0.6 mm (0.024 in) sheet this means less than 5% loss in a century. Tests on 18th-century European copper roofs suggested they could, in theory, last a thousand years.\n\n## Joining methods\n\nCopper is traditionally laid in pans joined by standing seams or batten (roll) seams, which allow the metal to expand and contract. These techniques are shared with lead and zinc work and are ancestors of modern standing seam roofing.\n\n## Today\n\nCopper remains in use for heritage roofs, church spires, flashings and high-end architecture, often chosen specifically for the way it ages.","key_facts":[{"label":"Hildesheim Cathedral copper roof","value":"1280"},{"label":"Kronborg Castle copper roof","value":"1585"},{"label":"Patina time (marine)","value":"About 7-9 years"},{"label":"Patina time (rural)","value":"About 10-30 years"}],"regions":["Global","Europe","South Asia"],"aliases":["copper roofing history","green copper roofs"],"related":["history-of-standing-seam-roofing","medieval-lead-roofs","zinc-roofs-of-paris","copper-roofing","copper-patina"],"company":null,"sources":[{"title":"Copper in architecture","url":"https://en.wikipedia.org/wiki/Copper_in_architecture","publisher":"Wikipedia"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Pantheon, Rome","url":"https://en.wikipedia.org/wiki/Pantheon,_Rome","publisher":"Wikipedia"},{"title":"Pantheon (building, Rome, Italy)","url":"https://www.britannica.com/topic/Pantheon-building-Rome-Italy","publisher":"Encyclopaedia Britannica"}],"country":null},{"slug":"history-of-green-roofs","title":"History of Green Roofs","category":"history","type":"article","summary":"From Scandinavian sod roofs to the modern German green roof industry of the 1970s and city mandates such as Toronto's 2009 by-law.","body":"A **green roof** is a roof deliberately covered with soil or growing medium and plants. The idea is old, but the modern engineered green roof, with root barriers, drainage layers and lightweight substrates, is a late-20th-century development led by Germany.\n\n## Legends and early examples\n\nThe **Hanging Gardens of Babylon** are often cited as the first roof garden, but their existence is disputed and no Babylonian text mentions them. Better documented are traditional **sod roofs** of Scandinavia, used on most rural houses in Norway from the Viking Age and Middle Ages until they were replaced by tile and corrugated iron; sources date their decline from the 18th to the late 19th century. Sod roofs are also common on traditional farm buildings in Iceland, and Kashmiri houses traditionally used *burze pash* roofs of birch topped with soil for winter insulation.\n\n## Early modern roof gardens\n\n- **1914:** the Moos water treatment plant roof in Switzerland, cited as one of Europe's oldest green roofs.\n- **1936:** the Rockefeller Center roof gardens in New York.\n- **1938:** the Kensington Roof Gardens in London.\n\n## The German movement\n\nThe modern green roof trend began in **Germany in the 1960s**. In the 1970s, stormwater problems pushed cities towards lightweight planted roofs, and by the 1980s the technology was widely known. The research society **FLL** was founded in 1975, and its green roof guidelines, most recently revised in 2011, became a reference across Europe. By the early 2000s many German cities required green roofs on certain buildings, and an estimated 10% of German roofs are now green.\n\n## Policy elsewhere\n\n- **Linz, Austria:** has paid developers to install green roofs since 1983.\n- **Switzerland:** federal rules since the late 1990s.\n- **Toronto:** a by-law of May 2009 required green roofs on certain new buildings.\n- **Washington, D.C.:** green roofing grew from 2.3 million sq ft (about 214,000 m²) in 2016 to 5.1 million sq ft (about 474,000 m²) by 2020.\n- **Denver:** an initiative took effect in January 2018.\n\n## Extensive and intensive\n\n**Extensive** roofs have 2-12.7 cm (about 1-5 in) of substrate and weigh about 50-120 kg/m² (10-25 lb/sq ft). **Intensive** roofs are deeper, support a wider range of plants and weigh about 390-730 kg/m² (80-150 lb/sq ft). Research summarised in 2023 found green roofs reduce summer roof surface temperatures substantially and cut stormwater runoff.","key_facts":[{"label":"Modern movement began","value":"Germany, 1960s"},{"label":"FLL founded","value":"1975"},{"label":"Toronto by-law","value":"May 2009"},{"label":"Extensive roof weight","value":"About 50-120 kg/m² (10-25 lb/sq ft)"}],"regions":["Global","Europe","North America"],"aliases":["vegetated roof history","living roof history","roof garden history"],"related":["scandinavian-sod-roofs","hanging-gardens-of-babylon","history-of-cool-roofs","green-roof"],"company":null,"sources":[{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"},{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"},{"title":"Hanging Gardens of Babylon","url":"https://en.wikipedia.org/wiki/Hanging_Gardens_of_Babylon","publisher":"Wikipedia"}],"country":null},{"slug":"history-of-japanese-kawara","title":"History of Japanese Kawara","category":"history","type":"article","summary":"How fired clay roof tiles (kawara) arrived in Japan with Buddhism in 588 and spread from temples to palaces, castles and ordinary houses.","body":"**Kawara** is the Japanese word for roof tile. Fired clay tiles are a defining feature of Japanese temples, castles and traditional houses, but they were a foreign technology introduced in the late 6th century.\n\n## Arrival in 588\n\nAccording to the *Nihon Shoki*, the Korean kingdom of Baekje sent craftsmen to Japan in 588, including four roof-tile experts, two temple builders, a specialist who probably made metal fittings, and a painter. They worked on **Asuka-dera**, the temple commissioned by Soga no Umako, which became the first fully fledged Buddhist temple complex in Japan. Tiles therefore arrived together with Buddhism and continental building methods.\n\n## Spread beyond temples\n\n- **Asuka period:** tiles were used only on temples. The oldest surviving kawara in Japan are on the Gokuraku-bo hall and Zenshitsu of Gangō-ji in Nara, the successor of Asuka-dera.\n- **Late 7th century:** palaces such as the Daigokuden of the Fujiwara capital were tiled.\n- **Nara and Heian periods:** government offices, provincial offices and provincial monasteries were tiled, supplied by official tile works. Aristocratic houses still used cypress-bark (*hiwada*) roofing.\n- **Medieval period:** imperial and shogunal buildings often returned to bark roofs.\n- **Azuchi-Momoyama period:** castles used gilded tiles, including the fish-shaped *shachi* ornaments and demon-faced *onigawara*.\n\n## Edo period changes\n\nPeace and dense wooden cities made fire the major threat. The shogunate and domains encouraged tile roofs as a fire precaution, and tiles spread to ordinary houses. In **1674** the tile maker Nishimura Hanbei developed the *sangawara*, a single-piece pantile combining pan and cover. It used less clay and weighed less, making tiles practical on lighter buildings. Copper and lead tiles were also used on some castle roofs to save weight.\n\n## Modern era\n\nIn the Meiji period, Western-style tiles were introduced and an improved hooked pantile, *hikkake sangawara*, was developed; it became a standard tile by 1926. Today Japan has more than 1,000 kinds of tile by style, use and region, fired in long tunnel kilns.","key_facts":[{"label":"Introduced","value":"588 (per Nihon Shoki)"},{"label":"First use","value":"Asuka-dera temple"},{"label":"Sangawara pantile","value":"Developed 1674 by Nishimura Hanbei"},{"label":"Oldest surviving tiles","value":"Gangō-ji, Nara"}],"regions":["East Asia"],"aliases":["kawara","Japanese roof tiles","sangawara"],"related":["asuka-dera","korean-giwa-history","chinese-glazed-roof-tiles"],"company":null,"sources":[{"title":"Kawara (tile)","url":"https://www.japanesewiki.com/culture/Kawara%20(tile).html","publisher":"Japanese Wiki Corpus"},{"title":"Asuka-dera","url":"https://en.wikipedia.org/wiki/Asuka-dera","publisher":"Wikipedia"}],"country":null},{"slug":"korean-giwa-history","title":"History of Korean Giwa","category":"history","type":"article","summary":"Giwa are Korean fired clay roof tiles, introduced with Buddhism in the 4th century and refined in the Three Kingdoms period with lotus-pattern roof-end tiles.","body":"**Giwa** is the Korean word for roof tile. Curved tiled roofs on wooden posts and bracket sets are the most recognisable feature of traditional Korean architecture, from palaces and temples to the tiled *hanok* houses of the Joseon period.\n\n## Origins\n\nClay tile technology first developed in China. Tiles were used on official buildings in the Chinese commanderies set up on the Korean peninsula after 108 BCE. The Smithsonian's National Museum of Asian Art states that fired roof tiles became established in Korea in the 4th century along with Buddhism. Before that, and for ordinary houses long afterwards, roofs were thatched; pit houses of the Mumun period had wattle-and-daub walls and thatch.\n\n## Three Kingdoms\n\n- **Goguryeo** palaces in Pyongyang used patterned tiles with ornate bracket systems.\n- **Baekje** (Sabi period, 538-660) produced roof-end tiles with lotus designs, the most popular Buddhist motif of the time. A rafter-end tile from Mireuksa temple, built in the reign of King Mu (600-641), is the earliest known use of green glaze on Korean roof tiles. Baekje craftsmen also carried tile making to Japan in 588.\n- **Silla** sites, notably the Wolji pond (Anapji) at the East Palace in Gyeongju, have produced elegant roof-end tiles.\n\n## Ridge ornaments\n\nLarge ceramic ornaments called **chimi** crowned both ends of the main ridge on important buildings and were believed to ward off evil. Unified Silla (676-935) examples from Wolji have a plain body and a strongly projecting rounded spine.\n\n## Parts of the roof\n\n- Round **roof-end tiles** capped the lowest convex cover tiles at the eaves.\n- **Rafter-end tiles** were nailed through a square central hole onto the ends of timber rafters to protect them from rot.\n- Lotus patterns with six, seven or eight petals are common, eight being the most frequent.\n\n## Later periods\n\nGoryeo (918-1392) and Joseon (founded 1392) architecture refined the bracket systems that carry the heavy tiled roof. A simple bracket system was already used under Goguryeo; a multiple-bracket system developed from the mid-Goryeo period under Chinese influence.","key_facts":[{"label":"Introduced","value":"4th century CE, with Buddhism"},{"label":"Earliest green glaze","value":"Mireuksa temple, reign of King Mu (600-641)"},{"label":"Ridge ornament","value":"Chimi"}],"regions":["East Asia"],"aliases":["giwa","Korean roof tiles","Korean roof-end tiles"],"related":["history-of-japanese-kawara","asuka-dera","chinese-glazed-roof-tiles"],"company":null,"sources":[{"title":"Once Upon a Roof: Vanished Korean Architecture","url":"https://asia.si.edu/once-upon-a-roof-gallery","publisher":"Smithsonian National Museum of Asian Art"},{"title":"Korean architecture","url":"https://en.wikipedia.org/wiki/Korean_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"history-of-roll-roofing","title":"History of Roll Roofing","category":"history","type":"article","summary":"Roll roofing grew from 19th-century American composition roofing into factory-made rolls of saturated felt, later surfaced with mineral granules.","body":"Roll roofing is a long sheet of saturated felt or mat coated with bitumen and usually surfaced with mineral granules, supplied in rolls and nailed or cemented to a roof deck. It is the direct ancestor of the asphalt shingle and a close relative of built-up roofing.\n\n## Composition roofing\n\nThe idea of making a roof from fabric or paper soaked in a waterproof binder developed in the United States in the mid-19th century. In the 1840s Samuel M. and Cyrus M. Warren of Cincinnati used a cotton fabric mat coated with pine tar and sand. Such site-applied \"composition\" roofs were layered on low-slope buildings, and the same principle underlies built-up roofing.\n\n## Ready roofing\n\nIn the last quarter of the 19th century, manufacturers began combining the components of built-up roofing into long, factory-made strips that could be rolled out on site. This product was marketed as **ready roofing**. It saved labour and made waterproof roofs available for farm buildings, sheds and low-cost houses.\n\n## Asphalt and granules\n\nAccording to standard accounts, asphalt prepared roofing, similar to modern roll roofing but without surface granules, was developed in 1893. In 1897 slate granules were added to the surface for durability. Granules protected the bitumen from sunlight, weather and foot traffic and limited early colours mainly to the natural shades of the surfacing, usually red, green or black.\n\n## From rolls to shingles\n\nAround 1901-1903 makers began cutting surfaced roll roofing into individual pieces, producing the first asphalt shingles. Shingles gave a more traditional appearance on pitched house roofs, while rolls remained the economical choice for low-slope and agricultural buildings.\n\n## Later developments\n\nRoll roofing followed shingles in moving from organic felts to fibreglass mats. Modified bitumen sheets, developed in Europe from the 1960s or 1970s depending on the source, extended the roll format to high-performance low-slope roofing with polymer-modified bitumen.\n\n## Use today\n\nMineral-surfaced roll roofing remains in use on sheds, porches and outbuildings, and as a cap sheet in multi-layer systems. It is usually regarded as a short-lived, low-cost covering compared with shingles or membranes.","key_facts":[{"label":"Composition roofing","value":"Mid-19th century, United States"},{"label":"Ready roofing","value":"Last quarter of the 19th century"},{"label":"Asphalt prepared roofing","value":"1893"},{"label":"Slate granules added","value":"1897"}],"regions":["North America"],"aliases":["ready roofing","rolled roofing","mineral surfaced roll roofing"],"related":["history-of-asphalt-shingles","history-of-built-up-roofing","roll-roofing","modified-bitumen-roofing"],"company":null,"sources":[{"title":"Asphalt Shingles - Roofing Exhibit","url":"https://www.nps.gov/crps/tps/roofingexhibit/asphalt.htm","publisher":"U.S. National Park Service"},{"title":"The History of Asphalt Shingles","url":"https://www.iko.com/blog/the-history-of-asphalt-shingles/","publisher":"IKO"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Membrane roofing","url":"https://en.wikipedia.org/wiki/Membrane_roofing","publisher":"Wikipedia"}],"country":null},{"slug":"history-of-roofing","title":"History of Roofing","category":"history","type":"article","summary":"An overview of how people have covered buildings, from brushwood huts and thatch to fired tiles, slate, metal sheet, asphalt and synthetic membranes.","body":"The history of roofing follows the materials people could gather, make and transport. For most of human history roofs were made from whatever grew or lay nearby: branches, grass, reed, turf, bark and animal hides. Fired clay tiles, cut stone and sheet metal arrived later and spread with trade, empires and religions. Industrialisation then made factory products such as corrugated iron, rolled zinc, asphalt shingles and plastic membranes available almost everywhere.\n\nDates in roofing history are often uncertain. Organic roofs rot and rarely survive, so archaeologists usually infer them from post holes, collapsed debris or fallen tiles.\n\n## Timeline of key developments\n\n- **About 23,000 years ago:** brushwood huts at Ohalo II on the Sea of Galilee, among the oldest known built shelters.\n- **About 2400-2200 BCE:** pan and cover clay tiles at Qiaocun on the Chinese Loess Plateau, described by its excavators as the earliest known composite-tiled roofs.\n- **7th century BCE:** the interfitting Protocorinthian tile system on the Old Temple at Corinth, Greece.\n- **Roman period:** flat tegula and curved imbrex tiles used across the empire; lead sheet used for watertight roofs.\n- **588 CE:** roof tiles reach Japan with Baekje craftsmen building Asuka-dera.\n- **1212:** new thatched roofs banned in London after a major fire.\n- **1393-1401:** the hammerbeam roof of Westminster Hall, the largest medieval timber roof in northern Europe.\n- **1406-1420:** the yellow glazed roofs of the Forbidden City, Beijing.\n- **1666:** the Great Fire of London leads to rebuilding rules favouring brick and stone.\n- **1829:** Henry Robinson Palmer patents corrugated metal sheets.\n- **1898:** Welsh slate output peaks at over 500,000 tons.\n- **1900:** Ludwig Hatschek patents his asbestos cement process (later sold as Eternit).\n- **1903:** asphalt shingles first cut from roll roofing in Grand Rapids, Michigan.\n- **1960s-1970s:** modern green roofs develop in Germany; modified bitumen develops in Europe.\n- **Early 1990s:** TPO single-ply membranes introduced.\n- **1998:** the Cool Roof Rating Council is founded in the United States.\n\n## Recurring themes\n\nThree forces shape most changes. **Fire** pushed cities to ban thatch and timber and to adopt tile, slate and metal. **Transport** decided which materials were affordable: canals and railways spread Welsh slate, and steamships carried prefabricated iron buildings to the colonies. **Industrial chemistry** produced asphalt, synthetic rubber and plastics in the 20th century, changing low-slope roofing completely. More recently, energy use and urban heat have driven interest in vegetated and reflective roofs.","key_facts":[{"label":"Oldest known built shelters","value":"About 23,000 years ago (Ohalo II)"},{"label":"Earliest composite clay tile roofs","value":"About 2400-2200 BCE (Qiaocun, China)"},{"label":"Corrugated metal patent","value":"1829"},{"label":"First asphalt shingles","value":"1903"}],"regions":["Global"],"aliases":["roofing history","timeline of roofing"],"related":["prehistoric-shelters-and-early-thatch","earliest-fired-clay-roof-tiles","imbrex-and-tegula","invention-of-corrugated-iron","history-of-asphalt-shingles","history-of-green-roofs","history-of-roofing-fire-regulations"],"company":null,"sources":[{"title":"Ohalo II","url":"https://en.wikipedia.org/wiki/Ohalo_II","publisher":"Wikipedia"},{"title":"Reconstructing the earliest known composite-tiled roofs from the Chinese Loess Plateau","url":"https://www.nature.com/articles/s41598-023-35299-x","publisher":"Scientific Reports (Nature Portfolio)"},{"title":"Research Spotlight: Roof Tile Manufacturing Techniques","url":"https://www.ascsa.edu.gr/news/newsDetails/sapirstein-dissertation","publisher":"American School of Classical Studies at Athens"},{"title":"Corrugated Iron Architecture","url":"https://buildingconservation.com/articles/corrugated-iron-architecture/corrugated-iron-architecture.htm","publisher":"The Building Conservation Directory"},{"title":"Asphalt Shingles - Roofing Exhibit","url":"https://www.nps.gov/crps/tps/roofingexhibit/asphalt.htm","publisher":"U.S. National Park Service"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"}],"country":null},{"slug":"history-of-roofing-fire-regulations","title":"History of Roofing Fire Regulations","category":"history","type":"article","summary":"How urban fires led cities to ban thatch and wood roofs, from London in 1212 to Boston in 1631 and 1872 and the US push against wood shingles in 1916.","body":"Fire has shaped roofing more than almost any other force. A roof of dry thatch or wooden shingles catches flying sparks easily, and in dense towns one burning roof can ignite the next. For centuries, authorities have responded by restricting combustible roofs and encouraging tile, slate and metal.\n\n## Medieval and early modern Europe\n\n- **London, 1212:** after a major fire, new thatched roofs were banned and existing ones had to be plastered over.\n- **1613:** the original Globe Theatre in London burned down when a stage cannon set its thatch alight, a famous illustration of the risk.\n- **London, 1666-1667:** after the Great Fire, the Rebuilding of London Act banned exterior wood and favoured brick and stone.\n- **Hamburg, 1842:** the city's great fire was followed by heavy rebuilding; Germany became an important export market for Welsh roofing slate afterwards.\n\n## Japan\n\nIn Edo-period Japan, dense timber cities were frequently destroyed by fire. The shogunate and domains encouraged clay tile roofs as a precaution, spreading tiles from temples and castles to ordinary houses. The lighter single-piece pantile developed in 1674 made this more practical.\n\n## North America\n\n- **Boston, 1631:** the town's first fire-prevention ordinance (dated 1630/31) banned thatched roofs and wooden chimneys, according to the Boston Fire Historical Society. Building rules of 1678 called for slate or tile roofs and brick walls.\n- **Boston, 1872:** a fire that spread across wooden mansard roofs destroyed 776 buildings. In its aftermath fire chief John Damrell campaigned for building codes, and Boston established height and area limits in 1892.\n- **1905:** the National Board of Fire Underwriters published the National Building Code, the first standardised US building code.\n- **1916:** the same body called for wood shingles to be eliminated as a fire hazard, which helped the rapid growth of asphalt shingles.\n\n## Modern fire ratings\n\nModern building codes generally regulate roofs through tested fire performance and rules for where combustible coverings may be used, rather than relying only on outright bans. Fire risk to traditional roofs persists: in the UK, 50-80 thatched roofs are destroyed by fire each year.\n\n## Pattern\n\nAcross these cases the sequence is similar: a catastrophic fire, a ban that is often poorly enforced at first, then gradual replacement of combustible roofs as non-combustible materials become cheaper.","key_facts":[{"label":"London thatch ban","value":"1212"},{"label":"Boston thatch ban","value":"1631"},{"label":"First US national building code","value":"1905"},{"label":"US call to eliminate wood shingles","value":"1916"}],"regions":["Global","Europe","North America","East Asia"],"aliases":["roof fire codes history","thatch bans"],"related":["great-fire-of-london","great-boston-fire-of-1872","history-of-thatch-in-britain","history-of-asphalt-shingles"],"company":null,"sources":[{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Great Fire of London","url":"https://en.wikipedia.org/wiki/Great_Fire_of_London","publisher":"Wikipedia"},{"title":"Great Boston fire of 1872","url":"https://en.wikipedia.org/wiki/Great_Boston_fire_of_1872","publisher":"Wikipedia"},{"title":"Asphalt Shingles - Roofing Exhibit","url":"https://www.nps.gov/crps/tps/roofingexhibit/asphalt.htm","publisher":"U.S. National Park Service"},{"title":"Kawara (tile)","url":"https://www.japanesewiki.com/culture/Kawara%20(tile).html","publisher":"Japanese Wiki Corpus"},{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"},{"title":"Boston History Before 1859","url":"https://bostonfirehistory.org/boston-history-before-1859","publisher":"Boston Fire Historical Society"}],"country":null},{"slug":"history-of-single-ply-membranes","title":"History of Single-Ply Membranes","category":"history","type":"article","summary":"How factory-made sheets of synthetic rubber and plastics (EPDM, CSPE, PVC, TPO) replaced much hot-applied built-up roofing on flat roofs.","body":"A **single-ply membrane** is a one-piece, factory-made waterproof sheet laid in a single layer over a low-slope roof, as opposed to the multiple plies of built-up roofing. Single-ply systems became possible after the growth of the synthetic rubber and plastics industries in the mid-20th century, and they now cover most new commercial flat roofs in North America.\n\n## Two families\n\n- **Thermosets** are cured elastomers. The best known is **EPDM** (ethylene propylene diene monomer) rubber, the synthetic rubber most commonly used in single-ply roofing. Seams are joined with adhesives or tapes because the cured sheet cannot be re-melted.\n- **Thermoplastics**, including **PVC**, KEE and **TPO**, soften with heat, so seams can be hot-air welded.\n\n## Milestones\n\n- **1964:** chlorosulfonated polyethylene (CSPE), sold by DuPont as Hypalon, entered roofing use.\n- **Early 1990s:** thermoplastic polyolefin (**TPO**) membranes were introduced.\n- **Late 1990s:** environmental concerns about chemical curing processes led some jurisdictions to restrict CSPE.\n- **June 2009:** DuPont discontinued Hypalon; by about 2011 CSPE roofing had nearly disappeared from the US market.\n- **2007-2012:** TPO sales by the six major US manufacturers grew to about four times those of other flat-roofing materials.\n- **2016:** TPO was the most popular commercial low-slope roof covering in the US.\n\n## Market today\n\nThermoplastics (PVC, KEE and TPO) together account for more than 55% of the US commercial roofing market, while thermosets account for no more than about 10%. Studies from the 1980s to the early 2000s put the average life of thermoset membranes at 15-20 years, although products have changed since. EPDM is now commonly offered with warranties of up to 30 years.\n\n## Early EPDM and PVC\n\n- **EPDM:** according to *Roofing Contractor*, EPDM single-ply membranes were first introduced in 1962. Their use grew in the 1970s, when the oil embargo raised the price of asphalt-based roofing. Early seams were cleaned with white gas and joined with neoprene-based splicing adhesive; butyl-based splice adhesives followed in the mid-1980s, and primers and double-sided seam tapes later still.\n- **PVC:** according to Sika, chemists at the Swiss company Sarna developed the first fabric-reinforced PVC roofing membrane in 1962, later sold as Sarnafil.\n\n## Relation to modified bitumen\n\nPolymer-modified bitumen sheets, developed in Europe from the 1960s or 1970s (sources differ), competed with single-ply membranes as the main replacement for multi-ply built-up roofing. Both technologies remain in wide use worldwide.","key_facts":[{"label":"CSPE (Hypalon) in roofing","value":"1964 to about 2011"},{"label":"TPO introduced","value":"Early 1990s"},{"label":"Most popular US low-slope cover (2016)","value":"TPO"},{"label":"Thermoplastics share of US commercial market","value":"Over 55%"},{"label":"EPDM introduced","value":"1962"},{"label":"First fabric-reinforced PVC membrane","value":"1962, Sarna (Switzerland)"}],"regions":["North America","Europe","Global"],"aliases":["single-ply roofing history","EPDM history","TPO history","PVC roofing history"],"related":["history-of-built-up-roofing","epdm-roofing","tpo-roofing","pvc-roofing","modified-bitumen-roofing"],"company":null,"sources":[{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"},{"title":"Built-up roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"Membrane roofing","url":"https://en.wikipedia.org/wiki/Membrane_roofing","publisher":"Wikipedia"},{"title":"The Evolution of EPDM Roofing Technology","url":"https://www.roofingcontractor.com/articles/91730-the-evolution-of-epdm-roofing-technology","publisher":"Roofing Contractor"},{"title":"Sika Sarnafil Celebrates 60th Anniversary of PVC Membrane","url":"https://www.roofingcontractor.com/articles/96787-sika-sarnafil-celebrates-60th-anniversary-of-pvc-membrane","publisher":"Roofing Contractor"}],"country":null},{"slug":"history-of-standing-seam-roofing","title":"History of Standing Seam Roofing","category":"history","type":"article","summary":"Standing seam roofing grew from centuries-old hand-folded joints in copper, lead and zinc sheet into today's machine-formed metal panel systems.","body":"A **standing seam** joins two metal sheets by turning up their edges and folding them together into a raised, watertight rib that sits above the drainage plane. The technique is far older than the modern roll-formed steel panel and has its roots in traditional European sheet-metal roofing.\n\n## Hand-folded metal roofs\n\nMetal roofs of copper, lead and later zinc and terne-coated iron were laid as relatively small sheets or \"pans\", joined by folded seams or by wrapping the metal over wooden battens or rolls. Raised and folded joints allowed each sheet to expand and contract with temperature while keeping water out, and put the joints above the flow of water. Early dated examples of large metal roofs include the copper roof of Hildesheim Cathedral (1280) and Kronborg Castle (1585), and the lead roofs of medieval cathedrals and halls such as Westminster Hall.\n\n## The 19th century\n\nCheap iron transformed metal roofing in the early 19th century. Iron sheet dipped in molten tin or zinc resisted rust, and **terne** plate, iron coated with a lead-tin alloy, became popular for roofs because it was cheaper than tinplate and more durable outdoors. In Paris, rolled zinc became the standard covering for the upper slopes of Second Empire mansard roofs, laid by specialist roofers using folded and batten seams.\n\n## Industrial production\n\nIn the 20th century, continuous rolled steel coil, metallic coatings and factory paint finishes allowed long panels to be formed by machine, either in a factory or with portable roll-formers on site. Concealed clip fixings, which hold the panel without piercing it, allow panels to move with temperature. Panels could now run the full length of a roof slope rather than being joined in short pans.\n\n## Continuity\n\nDespite industrial production, the basic profile of a folded double-lock seam remains recognisably the same as that formed by hand on copper and zinc roofs, and hand-seaming remains a core heritage skill in Europe.","key_facts":[{"label":"Principle","value":"Raised folded joint above the water line"},{"label":"Early metals","value":"Copper, lead, zinc, terne-coated iron"},{"label":"Early dated copper roof","value":"Hildesheim Cathedral, 1280"}],"regions":["Europe","North America","Global"],"aliases":["standing seam history","seamed metal roofing history"],"related":["history-of-copper-roofs","zinc-roofs-of-paris","medieval-lead-roofs","standing-seam-metal-roof","terne-plate"],"company":null,"sources":[{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Copper in architecture","url":"https://en.wikipedia.org/wiki/Copper_in_architecture","publisher":"Wikipedia"},{"title":"Toits de Paris","url":"https://fr.wikipedia.org/wiki/Toits_de_Paris","publisher":"Wikipédia (French)"}],"country":null},{"slug":"history-of-thatch-in-britain","title":"History of Thatch in Britain","category":"history","type":"article","summary":"Thatch was the main roof of rural England until the late 1800s; around 60,000 thatched properties survive in the UK, some with base coats over 500 years old.","body":"For most of recorded history, the ordinary rural roof in Britain was thatch: straw, reed or other plants laid thickly on a timber frame. It was cheap, locally grown and warm. Industrial materials displaced it in the 19th and 20th centuries, but Britain still has one of the largest stocks of thatched buildings in Europe.\n\n## Long dominance\n\nThatch remained the main roofing material for most of England's rural population until the late 1800s. Regional practice varied with local crops and wetlands. Research funded by Historic Scotland found Scottish thatch made of broom, heather, rushes, cereal straw, bracken, turf and clay, among other materials.\n\n## Urban bans\n\nTowns turned against thatch because of fire. After a major fire in 1212, London banned new thatched roofs and required existing ones to be plastered over. Bans on thatch and timber were repeatedly ignored because the materials were cheap, and thatch was still present when the Great Fire of 1666 led to stricter rebuilding rules. The original Globe Theatre burned down in 1613 when a stage cannon set its thatch alight; the modern reconstruction, opened in 1997, has water reed over a fire-protected roof.\n\n## Decline\n\nDistribution of Welsh slate from around 1820, then canals and railways, made slate and tile affordable far from their sources. Thatch numbers rose in the mid-1800s, then fell late in the century with agricultural recession and rural depopulation. Corrugated iron also replaced thatch on many farm buildings.\n\n## Materials\n\nThree main traditions survive in England:\n\n- **Long straw**, threshed wheat straw laid with a shaggy finish;\n- **Combed wheat reed**, straw combed to keep the stems aligned;\n- **Water reed**, traditionally used mainly in East Anglia; over 80% of the UK's water reed is now imported.\n\nModern short-stemmed wheat and combine harvesting weakened straw quality, and since the 1980s growers have revived older heritage wheat varieties for thatching.\n\n## Survival and age\n\nA 2013 estimate put the number of thatched properties in the UK at about 60,000, served by roughly 1,000 full-time thatchers. More than 250 roofs in southern England retain base coats laid more than 500 years ago, a valuable record of medieval crops. Because roofs are re-coated rather than stripped, thatch on some buildings has built up to over 2.1 m (7 ft) thick. Between 50 and 80 thatched roofs are lost to fire in the UK each year.","key_facts":[{"label":"UK thatched properties","value":"About 60,000 (2013 estimate)"},{"label":"Full-time thatchers","value":"About 1,000"},{"label":"London ban on new thatch","value":"1212"},{"label":"Oldest base coats","value":"Over 500 years (250+ roofs)"}],"regions":["Europe"],"aliases":["British thatch history","English thatching"],"related":["prehistoric-shelters-and-early-thatch","great-fire-of-london","history-of-roofing-fire-regulations","welsh-slate-industry","thatch"],"company":null,"sources":[{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"},{"title":"Corrugated Iron Architecture","url":"https://buildingconservation.com/articles/corrugated-iron-architecture/corrugated-iron-architecture.htm","publisher":"The Building Conservation Directory"}],"country":null},{"slug":"geodesic-dome-history","title":"History of the Geodesic Dome","category":"history","type":"article","summary":"Geodesic domes, spherical frames of triangles, were first built by Walther Bauersfeld in Jena in the 1920s and popularised by Buckminster Fuller after 1948.","body":"A **geodesic dome** is a spherical or part-spherical shell made from a network of triangles. Because triangles are rigid, the structure spreads loads across the whole frame, enclosing a large volume with little material and no internal columns. Geodesic domes have been used to roof planetariums, exhibition pavilions, attractions and homes.\n\n## Bauersfeld and Jena\n\nThe first geodesic dome was designed after the First World War by **Walther Bauersfeld**, chief engineer of the optical company **Carl Zeiss Jena** in Germany, to house a planetarium projector. Bauersfeld received a German patent on 19 June 1925. A small dome was built on the roof of the Zeiss works, and the larger planetarium known as \"The Wonder of Jena\" opened to the public on **18 July 1926**.\n\n## Fuller\n\nThe American designer **Buckminster Fuller** developed the idea independently. In 1948-1949, at Black Mountain College, he experimented with domes with the artist Kenneth Snelson and coined the term \"geodesic\". He received US patent 2,682,235 on **29 June 1954**. Fuller is often mistakenly credited as the inventor, but he did more than anyone to popularise the dome.\n\n## Milestones\n\n- **1953:** the oldest surviving Fuller-built dome is erected by students in three weeks at Woods Hole, Massachusetts.\n- **From 1954:** military tests showed a 9.1 m (30 ft) dome could be carried by helicopter at about 93 km/h (50 knots) without damage.\n- **1967:** the US Pavilion dome at Expo 67 in Montreal, by Fuller and Shoji Sadao. Its covering later burned, but the frame survives as the Montreal Biosphère.\n- **1982:** Spaceship Earth opened on 1 October at Epcot, Walt Disney World, Florida.\n\n## Records\n\nAs of May 2021, Guinness World Records listed the **Jeddah Super Dome** in Saudi Arabia, 210 m (690 ft) across, as the largest geodesic dome. The larger Seagaia Ocean Dome in Japan (216.5 m) was demolished in 2017.\n\n## Other large domes\n\nOther very large examples include the Poliedro de Caracas in Venezuela, about 143 m (469 ft) across, and the Ruwais Refinery Dome, about 135 m (443 ft).","key_facts":[{"label":"First geodesic dome","value":"Walther Bauersfeld, Zeiss, Jena (1920s)"},{"label":"Jena planetarium opened","value":"18 July 1926"},{"label":"Fuller's US patent","value":"29 June 1954"},{"label":"Largest (Guinness, 2021)","value":"Jeddah Super Dome, 210 m (690 ft)"}],"regions":["Global","Europe","North America"],"aliases":["geodesic dome","geodesic sphere"],"related":["buckminster-fuller","frei-otto","dome"],"company":null,"sources":[{"title":"Geodesic dome","url":"https://en.wikipedia.org/wiki/Geodesic_dome","publisher":"Wikipedia"},{"title":"Buckminster Fuller","url":"https://en.wikipedia.org/wiki/Buckminster_Fuller","publisher":"Wikipedia"}],"country":null},{"slug":"mansard-roof-history","title":"History of the Mansard Roof","category":"history","type":"article","summary":"The mansard is a double-sloped hip roof named after François Mansart; it first appeared around 1550 and boomed with Second Empire architecture.","body":"A **mansard roof** is a four-sided roof with two slopes on each side: a steep lower slope, often pierced by dormer windows, and a shallow upper slope that may be almost flat. It turns the roof into an extra habitable storey, the garret, while keeping the overall height down.\n\n## Origins\n\nThe earliest known example is usually credited to **Pierre Lescot** on part of the Louvre in Paris around 1550. The French architect **François Mansart** (1598-1666) used the form so heavily in the early 17th century that it took his name, but he did not invent it. His great-nephew Jules Hardouin-Mansart (1646-1708) continued the tradition.\n\n## Why Paris adopted it\n\nA popular story says mansards were built to avoid a tax on windows or storeys. This is unlikely: the French window tax dates from 1798, long after Mansart's death, and did not exempt mansard windows. A better explanation is a 1783 Paris rule limiting building height to 20 m (66 ft) measured to the cornice, which left space inside the roof uncounted. A 1902 revision allowed three or four storeys within the roof.\n\n## Second Empire boom\n\nUnder Napoleon III's Second Empire (1852-1870) and Haussmann's rebuilding of Paris from the 1850s, mansards became standard on apartment blocks, with zinc and slate coverings. The \"Second Empire\" style spread to civic buildings, hotels and railway stations in Europe and North America. In the United States and Canada, especially New England, it appeared on houses and mansions.\n\n## Fire risk\n\nTimber-framed mansards could be dangerous. In the Great Boston Fire of 1872, flames spread from the wooden mansard roof of the first warehouse along neighbouring rooftops; 776 buildings were destroyed.\n\n## Later uses\n\n- The 1916 New York City zoning rules suited mansards because of their setback requirements.\n- Soviet rules until 1981 limited dachas to one storey but did not count roof space, so many dachas have mansards.\n- In the 1960s and 1970s flat-topped mansards were used to hide rooftop mechanical equipment.\n\n## Mansard or gambrel?\n\nA mansard slopes on all four sides (a curb hip roof). A **gambrel** slopes on two sides only, like many North American barns. French and German usage often does not distinguish them, and \"mansarde\" can mean the attic room itself.","key_facts":[{"label":"Earliest known example","value":"Louvre, Pierre Lescot, about 1550"},{"label":"Named after","value":"François Mansart (1598-1666)"},{"label":"Paris height limit","value":"20 m (66 ft) to cornice, 1783"},{"label":"Revival","value":"Second Empire, 1852-1870"}],"regions":["Europe","North America"],"aliases":["French roof","Second Empire roof","mansard history"],"related":["francois-mansart","zinc-roofs-of-paris","great-boston-fire-of-1872","mansard-roof","gambrel-roof"],"company":null,"sources":[{"title":"Mansard roof","url":"https://en.wikipedia.org/wiki/Mansard_roof","publisher":"Wikipedia"},{"title":"François Mansart","url":"https://en.wikipedia.org/wiki/Fran%C3%A7ois_Mansart","publisher":"Wikipedia"},{"title":"Great Boston fire of 1872","url":"https://en.wikipedia.org/wiki/Great_Boston_fire_of_1872","publisher":"Wikipedia"}],"country":null},{"slug":"history-of-timber-roof-framing","title":"History of Timber Roof Framing","category":"history","type":"article","summary":"How carpenters moved from simple paired rafters to medieval trusses, hammerbeams and, in modern times, factory-made metal-plate trusses.","body":"Timber has framed pitched roofs for thousands of years. The central problem is always the same: sloping rafters push outwards at their feet, and that thrust must be contained or the walls spread and the roof sags. The history of roof framing is largely the history of solving that problem with longer spans and less timber.\n\n## Coupled rafters\n\nThe simplest roof uses pairs of rafters leaning together at the ridge, tied at the bottom by a horizontal beam. These coupled-rafter roofs were structurally weak and prone to racking, meaning sideways collapse, especially over wider buildings.\n\n## Medieval trusses\n\nMedieval carpenters developed the **truss**, a rigid triangulated frame placed at intervals to carry purlins and common rafters. Variants included:\n\n- **King post** trusses, with a central vertical post from tie beam to ridge;\n- **Queen post** trusses, with two posts; in Italy the type is called *palladiana* because Andrea Palladio used it so often;\n- **Arch-braced** trusses, with curved braces forming an arch;\n- **Hammerbeam** trusses, with short projecting beams that let a roof span further than any single timber.\n\nThe masterpiece of the period is Hugh Herland's hammerbeam roof at Westminster Hall, installed in the 1390s and spanning just over 20 m (66 ft).\n\n## Joints\n\nEarly trusses were held by mortise-and-tenon joints cut on site and secured with oak pegs. Carpenters drilled peg holes slightly off-centre so that driving the peg drew the joint tight, a technique called draw-boring. Shrinkage of unseasoned green timber could crack joints over time.\n\n## Exchange of ideas\n\nHistorians have traced how roof-framing knowledge moved from Italy to England in the 17th century through architects such as Inigo Jones and Christopher Wren. German settlers in the United States built *liegender Stuhl* (lying chair) trusses in the 18th and 19th centuries.\n\n## Modern trusses\n\nIn modern construction, factory-made trusses of dressed lumber joined by metal connector plates have replaced much site-cut framing, particularly in the United States. They use less timber and are made with machine accuracy, and a shortage of skilled carpenters has accelerated the move to factory production.","key_facts":[{"label":"Key medieval innovation","value":"The triangulated roof truss"},{"label":"Westminster Hall span","value":"Just over 20 m (66 ft)"},{"label":"Modern standard","value":"Metal-plate-connected trusses"}],"regions":["Global","Europe","North America"],"aliases":["roof framing history","roof truss history"],"related":["hammerbeam-roof","westminster-hall-roof","king-post-truss","queen-post-truss","roof-truss"],"company":null,"sources":[{"title":"Roof truss","url":"https://en.wikipedia.org/wiki/Roof_truss","publisher":"Wikipedia"},{"title":"Hammerbeam roof","url":"https://en.wikipedia.org/wiki/Hammerbeam_roof","publisher":"Wikipedia"},{"title":"The hammer-beam roof","url":"https://webtest.parliament.uk/about/living-heritage/building/palace/westminsterhall/architecture/the-hammer-beam-roof-","publisher":"UK Parliament"}],"country":null},{"slug":"hiwadabuki","title":"Hiwadabuki","category":"world-roofing","type":"term","summary":"Hiwadabuki is Japanese roofing made of many thin layers of hinoki cypress bark fixed with bamboo nails, used on shrines, palaces and temples.","body":"*Hiwadabuki* (檜皮葺 or 桧皮葺) is a traditional Japanese roof covering made from the bark of *hinoki*, the Japanese cypress. Strips of bark are laid in many overlapping layers to build up a thick, soft-looking roof that can be shaped into the smooth curves and upturned eaves of shrine and palace architecture. It is one of the most prestigious roof coverings in Japan.\n\n## Technique\n\nThe bark is cut into strips, usually about 45-60 cm (18-24 in) long and 4-15 cm (1.5-6 in) wide. Roofers lay them in successive courses, each shifted only about 1-2 cm (0.4-0.8 in) beyond the one below, so that the finished roof is made up of very many layers. Each course is fixed with bamboo nails. The result is a dense, thick covering whose edges at the eaves show the layered build-up. Bark for roofing is traditionally harvested by specialist craftsmen.\n\n## History\n\nHiwadabuki is native to Japan. In the Heian period (794-1185) aristocratic mansions were roofed with layered cypress bark rather than the ceramic tiles used on Buddhist temples, and the technique became associated with imperial palaces and Shinto shrines, where tile was often avoided. Many shrine main halls and some temple halls still use it.\n\n## Heritage status\n\nCypress-bark roofing is a recognised conservation skill in Japan. In December 2020 UNESCO inscribed \"Traditional skills, techniques and knowledge for the conservation and transmission of wooden architecture in Japan\" on the Representative List of the Intangible Cultural Heritage of Humanity. Among its 17 component skills are **cypress-bark and wooden-shingle roofing** and the **harvesting of Japanese cypress bark**. Because the materials and specialist roofers are scarce, preservation associations train new craftspeople.\n\n## Examples\n\nThe JAANUS dictionary of Japanese architecture illustrates the technique with the Chokushimon (imperial messenger gate) of Engaku-ji in Kamakura. Other well-known hiwadabuki roofs include the main hall of Kiyomizu-dera in Kyoto and the main sanctuary of Izumo Taisha.\n\n## Related coverings\n\n- *Kokerabuki* - thin wooden shingles, also fixed with bamboo nails.\n- *Kayabuki* - grass thatch.\n- *Kawarabuki* - clay tile roofing.","key_facts":[{"label":"Material","value":"Hinoki (Japanese cypress) bark"},{"label":"Strip size","value":"45-60 cm long, 4-15 cm wide"},{"label":"Exposure per course","value":"About 1-2 cm"},{"label":"Fixing","value":"Bamboo nails"},{"label":"UNESCO","value":"Part of wooden-architecture skills, 2020"}],"regions":["East Asia"],"aliases":["hiwada-buki","cypress bark roof","hinoki bark roofing"],"related":["kokerabuki","kayabuki","japanese-kawara-tile","roofing-in-japan","wood-shingle","irimoya"],"company":null,"sources":[{"title":"hiwadabuki","url":"https://projects.mcah.columbia.edu/jaanus/record/hiwadabuki","publisher":"JAANUS (Japanese Architecture and Art Net Users System)"},{"title":"UNESCO Intangible Cultural Heritage of Humanity in Japan","url":"https://www.nippon.com/en/features/h00347/","publisher":"Nippon.com"},{"title":"Traditional skills, techniques and knowledge for the conservation and transmission of wooden architecture in Japan","url":"https://ich.unesco.org/en/RL/traditional-skills-techniques-and-knowledge-for-the-conservation-and-transmission-of-wooden-architecture-in-japan-01618","publisher":"UNESCO Intangible Cultural Heritage"},{"title":"Japanese architecture","url":"https://en.wikipedia.org/wiki/Japanese_architecture","publisher":"Wikipedia"},{"title":"Curved hiwada-buki roof (niponica No. 32)","url":"https://web-japan.org/niponica/niponica32/en/feature/feature02-2.html","publisher":"Ministry of Foreign Affairs of Japan (web-japan.org)"}],"country":null},{"slug":"holcim","title":"Holcim","category":"manufacturers","type":"company","summary":"Holcim is a Swiss building-materials group founded in 1912 that built a large North American roofing business before spinning it off as Amrize in 2025.","body":"Holcim is a Swiss building-materials company headquartered in Zug. It was founded in 1912 by Adolf Gygi as Aargauische Portlandcementfabrik Holderbank-Wildegg, in Holderbank in the canton of Aargau, and is best known as one of the world's largest cement producers. In the early 2020s Holcim moved into roofing through large acquisitions in North America, then separated that business in 2025.\n\n## Roofing acquisitions\n\n- **Firestone Building Products**: bought from Bridgestone, completed on 1 April 2021. The commercial roofing business, maker of EPDM, TPO and PVC membranes and polyiso insulation, was rebranded Elevate on 21 June 2022.\n- **Malarkey Roofing Products**: a Portland, Oregon maker of residential asphalt shingles, founded in 1956, acquired in early 2022. Holcim projected its 2022 net sales at about USD 600 million and placed it in its Solutions & Products segment.\n- **Duro-Last**: a Saginaw, Michigan maker of prefabricated PVC roofing, whose acquisition by Holcim's building envelope business was completed in 2023.\n\n## Spin-off\n\nHolcim decided to separate its North American business with a full capital-market split. The process was completed on 23 June 2025, when the North American company was listed as Amrize. The roofing businesses (Elevate, Malarkey and Duro-Last) are part of Amrize's building envelope activities. Holcim remains listed on the SIX Swiss Exchange and continues to operate outside North America.\n\n## Context\n\nThe roofing acquisitions extended Holcim from cement and aggregates into building envelope products. Holcim later combined with the French cement group Lafarge, under a merger announced in 2014; Lafarge had earlier owned the European tile business that later became Braas Monier.","key_facts":[{"label":"Founded","value":"1912"},{"label":"Headquarters","value":"Zug, Switzerland"},{"label":"Roofing acquisitions","value":"Firestone BP (2021), Malarkey (2022), Duro-Last (2023)"},{"label":"Spin-off","value":"Amrize, 23 June 2025"}],"regions":["Global","Europe","North America"],"aliases":["Holcim Ltd","LafargeHolcim"],"related":["amrize","holcim-elevate","malarkey-roofing-products","duro-last","braas"],"company":{"founded":"1912","headquarters":"Zug, Switzerland","website":"https://www.holcim.com","known_for":["Cement","Former owner of Elevate, Malarkey and Duro-Last"]},"sources":[{"title":"Holcim","url":"https://en.wikipedia.org/wiki/Holcim","publisher":"Wikipedia"},{"title":"Holcim completes acquisition of Malarkey Roofing Products","url":"https://www.holcim.com/holcim-completes-acquisition-malarkey","publisher":"Holcim"},{"title":"Firestone Building Products","url":"https://en.wikipedia.org/wiki/Firestone_Building_Products","publisher":"Wikipedia"},{"title":"Duro-Last history","url":"https://duro-last.com/history/","publisher":"Duro-Last"}],"country":null},{"slug":"horsham-stone","title":"Horsham Stone","type":"term","summary":"A flaggy Cretaceous sandstone from the Weald around Horsham, England, split into heavy roofing slabs for churches, barns and manor houses.","body":"Horsham stone is a calcareous, flaggy sandstone from the Weald of south-east England, around the town of Horsham in West Sussex. Split into large, heavy slabs, it was used as roofing on churches, manor houses, mills, barns and dovecotes across Sussex and neighbouring counties, and its thickest slabs were used for paving.\n\n## Geology\n\nThe stone formed about 130 million years ago in the Lower Cretaceous, when sands rich in quartz and mica were deposited in the Wealden Basin. Ripple marks preserved on many slabs record the action of water on the ancient sea or lake bed. It occurs in bands about 10-13 cm (4-5 in) thick just below the surface of the Weald Clay, in an arc several kilometres around Horsham.\n\n## Use on roofs\n\nLike other English stone slates, Horsham slabs are laid in diminishing courses, with the largest at the eaves. Historic England classifies it among the sandstone stone slates of England, which should not be mixed with limestone slates on the same roof.\n\n## History\n\n- The earliest recorded use is from the Bronze Age, in quern fragments found at Amberley Mount.\n- The Romans used it for the Stane Street road and for floors and roof slates at the villas of Bignor and Fishbourne.\n- Large-scale commercial extraction had stopped by the 1880s, and regular quarrying ended in the 1930s.\n\n## Supply\n\nWith the old quarries closed, Purbeck stone was often used as a cheaper substitute in repairs, though it is a limestone. The Nowhurst quarry, reopened in 2004, produces roofing slates for historic buildings. Heritage guidance recommends like-for-like replacement where possible.\n","key_facts":[{"label":"Rock","value":"Calcareous sandstone, Lower Cretaceous (c. 130 million years)"},{"label":"Location","value":"Weald, around Horsham, West Sussex"},{"label":"Bed thickness","value":"About 10-13 cm (4-5 in)"},{"label":"Quarry reopened","value":"Nowhurst, 2004"}],"regions":["Europe"],"aliases":["Horsham slab","Horsham stone slate"],"related":["stone-slate","cotswold-stone-slate"],"sources":[{"title":"Horsham Stone","url":"https://en.wikipedia.org/wiki/Horsham_Stone","publisher":"Wikipedia"},{"title":"Stone Slate Roofing: Technical Advice Note","url":"https://cms.historicengland.org.uk/images-books/publications/stone-slate-roofing-technical-advice-note/stoneslate","publisher":"Historic England (English Heritage)"}],"category":"materials","company":null,"country":null},{"slug":"hot-weather-roofing","title":"Hot Weather Roofing","category":"installation","type":"article","summary":"Hot weather roofing addresses heat stress for workers and softening, scuffing and over-sealing of materials when roofs are installed in high temperatures.","body":"Roof surfaces can be far hotter than the surrounding air, and roofing is one of the trades most exposed to heat. Hot weather affects both people and materials, and roofing practice in hot climates, from the southern United States to the Middle East, Australia and South Asia, is organised around it.\n\n## Heat stress\n\nThe US Occupational Safety and Health Administration (OSHA) promotes **water, rest and shade** to prevent heat illness. Its guidance recommends scheduling heavy work for cooler times of day, shortening shifts, and taking frequent breaks in shade. New and returning workers need **acclimatisation**, with shorter shifts and frequent breaks during their first days in the heat. OSHA notes that wet bulb globe temperature (WBGT) is the most accurate measure of heat stress, and some US states, including California, Washington, Oregon, Minnesota and Colorado, have specific occupational heat rules. Federal enforcement relies on the general duty clause and a national emphasis programme on heat hazards.\n\nTypical roofing measures include early starts, rotating tasks, cool drinking water at roof level, shaded rest areas, buddy checks for symptoms of heat exhaustion and heat stroke, and light-coloured, breathable clothing worn with the required personal protective equipment.\n\n## Materials\n\n- **Asphalt shingles** soften in high heat and can be scuffed or marked by foot traffic, especially on dark colours. Crews limit walking on newly laid shingles, avoid twisting on the surface and stage materials to minimise traffic.\n- **Sealing.** Factory sealant strips activate quickly in heat, so shingles misaligned during installation can bond in place before they are corrected. Excess hand-applied cement can cause blistering and should be used sparingly.\n- **Bitumen and adhesives.** Hot conditions shorten open times for adhesives and coatings, and some coatings have maximum surface temperature limits.\n- **Metal panels.** Panels expand on hot days; clip and fastener layout must allow for movement. Metal surfaces can cause burns.\n- **Membranes.** Hot-air welding settings for thermoplastics are adjusted to conditions, with test welds after significant weather changes.\n\n## Storage\n\nBundles and rolls are stored flat, out of direct sun where possible, and not stacked higher than the manufacturer allows, since heat combined with weight can cause sticking and distortion.","key_facts":[{"label":"OSHA heat message","value":"Water, rest, shade"},{"label":"Best heat measure (OSHA)","value":"Wet bulb globe temperature (WBGT)"},{"label":"Main material issue","value":"Scuffing of softened shingles"}],"regions":["Global"],"aliases":["summer roofing","heat stress roofing"],"related":["cold-weather-roofing","hand-sealing-shingles","hot-air-welding"],"company":null,"sources":[{"title":"Heat Exposure","url":"https://www.osha.gov/heat-exposure","publisher":"U.S. Occupational Safety and Health Administration"},{"title":"TBR64 Proper Nailing for Laminated Shingles","url":"https://www.iko.com/na/document/tbr64-proper-nailing-for-laminated-shingles-product-bulletin","publisher":"IKO"},{"title":"Canadian Roofing Reference Manual: 7.1.3 Thermoplastic Membrane Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-7-single-ply-roofing-membranes/7-1-thermoplastics/7-1-3-membrane-installation/","publisher":"Canadian Roofing Contractors Association"},{"title":"NZ Metal Roof and Wall Cladding Code of Practice: Thermal Expansion and Contraction","url":"https://www.metalroofing.org.nz/cop/roofing/thermal-expansion-and-contraction","publisher":"NZ Metal Roofing Manufacturers Inc."}],"country":null},{"slug":"hot-air-welder","title":"Hot-Air Welder","category":"tools-equipment","type":"term","summary":"A tool that blows heated air between overlapping thermoplastic membrane sheets, fusing seams on TPO and PVC roofs.","body":"A hot-air welder joins thermoplastic roofing membranes such as TPO (thermoplastic polyolefin) and PVC (polyvinyl chloride) by heating the overlapping surfaces until they melt and then pressing them together so they fuse into a single, homogeneous seam. Both hand-held and automatic welders are used on most thermoplastic roofs.\n\n## Types\n\n- **Hand-held welders** have a heating element, a fan and a flat nozzle. The operator directs the nozzle into the seam and follows immediately with a silicone hand roller. They are used for flashings, details, corners, patches and short seams.\n- **Automatic welders** are wheeled machines that travel along field seams at a set speed, combining a hot-air nozzle with pressure rollers. They give consistent results on long seams.\n\n## Settings and test welds\n\nWeld quality depends on the balance between **temperature**, **speed** and **pressure**, and on ambient conditions. Membrane manufacturers publish starting settings for specific machines; one manufacturer's guide gives starting temperatures for automatic welders of roughly 990-1,000 °F (about 530-540 °C) for TPO and around 1,090 °F (about 590 °C) for PVC, at speeds of several feet per minute, adjusted for membrane thickness. Because sun, shade, wind, substrate and temperature change through the day, manufacturers recommend making test welds several times daily and peel-testing them (cutting a strip about 1 in or 25 mm wide across the weld and pulling it apart) to confirm a proper bond.\n\n## Common problems\n\n- **Cold welds**: too little heat or too fast travel leaves an unfused seam.\n- **Burned or overheated welds**: too much heat degrades the membrane.\n- **Contamination**: dirt, moisture or oxidised membrane surfaces prevent fusion and may need cleaning or preparation.\n- **Wrinkles and fishmouths** at seam intersections and step-offs.\n\nSeams should be probed with a seam probe after cooling, typically at the end of each work day.\n\n## Power and safety\n\nAutomatic welders need a stable power supply, often from a dedicated generator of adequate size and heavy-gauge extension cords. Hot nozzles and air can cause burns and ignite combustible materials, so welders are rested on stands and kept clear of debris.","key_facts":[{"label":"Materials","value":"TPO, PVC and other thermoplastic membranes"},{"label":"Key variables","value":"Temperature, speed, pressure"},{"label":"Quality checks","value":"Daily test welds, peel tests, seam probing"}],"regions":["Global"],"aliases":["heat welder","Leister-type welder","automatic welder","hand welder"],"related":["seam-probing","seam-failure","tpo-roofing","pvc-roofing","single-ply-roofing"],"company":null,"sources":[{"title":"TPO and PVC Welding Guidelines","url":"https://www.versico.com/Resources/Media/Blog/2020/01/14/TPO-and-PVC-Welding-Guidelines","publisher":"Versico"},{"title":"Combatting Common TPO Welding Problems","url":"https://floridaroof.com/news/blog/Combatting-Common-TPO-Welding-Problems-February2021","publisher":"Florida Roofing Magazine"},{"title":"Hot air welding machine TWINNY T5","url":"https://directindustry.com/prod/leister-technologies-ag/product-9088-2181189.html","publisher":"DirectIndustry"}],"country":null},{"slug":"hot-air-welding","title":"Hot-Air Welding","category":"installation","type":"term","summary":"Hot-air welding joins thermoplastic roofing membranes such as PVC and TPO by melting overlapping sheets with heated air and pressing them together.","body":"**Hot-air welding** is the standard way to join thermoplastic single-ply membranes, mainly **PVC** and **TPO** (and related materials such as KEE and FPO). A stream of heated air softens the top and bottom sheets in a lap, and a roller presses them together so they fuse into a single homogeneous layer. Properly done, the seam is as strong as or stronger than the sheet itself. Thermoset membranes such as EPDM cannot be welded and are joined with tape or adhesive instead.\n\n## Equipment\n\n- **Automatic (robotic) welders.** Wheeled machines that travel along long field seams at a set temperature and speed, with a built-in pressure roller.\n- **Hand welders.** Hand-held heat guns used for flashings, corners and details. Canadian guidance uses a 38 mm (1 1/2 in) nozzle for straight seams and a 19 mm (3/4 in) nozzle for corners.\n- **Seam rollers.** Silicone or brass rollers used with hand welders.\n\n## Hand welding technique\n\nCanadian guidance describes preheating the nozzle at full setting for at least a minute, then adjusting heat and making test welds. The back edge of the lap is first tacked with a thin continuous bead; the seam is then welded with the nozzle at about 45 degrees and the roller held at 90 degrees to it, moving steadily as the material begins to flow.\n\n## Test welds and settings\n\nThere is no single correct temperature: settings depend on the membrane, thickness, air temperature, wind and machine. Canadian guidance calls for test welds at the start of each work period and after significant weather changes. Too little heat gives a weak bond; too much damages the membrane.\n\n## Signs of a good weld\n\nFor PVC, a good weld shows a glossy surface, a little smoke while welding and a continuous bead of melted material at the seam edge. After cooling, every seam is checked by **seam probing**, and test cuts may be taken for peel testing. Seams must be clean and dry; dirt, moisture or chalking on aged membranes can prevent a bond, and older membranes may need cleaning or preparation before repair welds.","key_facts":[{"label":"Membranes","value":"PVC, TPO and other thermoplastics"},{"label":"Hand welder nozzles (Canada)","value":"38 mm (1 1/2 in) straight; 19 mm (3/4 in) corners"},{"label":"Quality check","value":"Test welds daily; probe all seams"}],"regions":["Global"],"aliases":["heat-welded seam","hot-air weld","welded lap","heat welding","thermoplastic seam welding","hot air seaming","Hot-Air Welded Seam"],"related":["pvc-roofing","tpo-roofing","kee-roofing-membrane","pib-roofing-membrane","single-ply-roofing","seam-probing","fully-adhered-vs-mechanically-attached"],"company":null,"sources":[{"title":"The ABCs of PVC Roof Membranes","url":"https://usa.sika.com/dms/getdocument.get/88a0c83a-9151-4100-84d6-dccadfebd4aa/the-abcs-of-pvc-roof-membranes.pdf","publisher":"Sika USA"},{"title":"Thermoplastic Polyolefin (TPO) Roofing Systems","url":"https://buildings.com/articles/35297/thermoplastic-polyolefin-tpo-roofing-systems","publisher":"Buildings"},{"title":"Sustaining a KEE standard for roofing membranes","url":"https://www.constructioncanada.net/sustaining-a-kee-standard-for-roofing-membranes/","publisher":"Construction Canada"},{"title":"Technical Details: Thermoset Membranes - EPDM Technology and Repair","url":"https://roofingcontractor.com/articles/85516-technical-details-thermoset-membranes-epdm-technology-and-repairp","publisher":"Roofing Contractor"},{"title":"Canadian Roofing Reference Manual: 7.1.3 Thermoplastic Membrane Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-7-single-ply-roofing-membranes/7-1-thermoplastics/7-1-3-membrane-installation/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 13.1.2 Potential Problem Areas","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/canadian-roofing-reference-manual-chapter-13-troubleshooting-and-repairs/13-1-identify-cause-of-problem/13-1-2-potential-problem-areas/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"hot-melt-rubberized-asphalt","title":"Hot-Melt Rubberised Bitumen","category":"low-slope-systems","type":"term","summary":"A thick, seamless waterproofing of polymer-modified bitumen melted on site and applied hot with fabric reinforcement, mainly for inverted, podium and buried roofs.","body":"Hot-melt rubberised bitumen, called hot rubberized asphalt in North America and simply \"hot melt\" in the UK, is a fluid-applied waterproofing made from bitumen modified with synthetic rubbers and fillers. It is supplied in blocks or cakes, melted in special double-jacketed oil-heated melters to control temperature, and spread with squeegees onto a primed concrete deck.\n\n## System\n\nA typical hot-melt system is built in two layers with a reinforcing fabric, usually polyester, embedded between them, giving a seamless, fully bonded, thick membrane. A protection sheet is laid over it before insulation or overburden. Because the membrane is bonded to the deck, water cannot travel beneath it, which makes leaks easier to locate and limits damage.\n\n## Where it is used\n\nHot melt is designed to be buried. It is the classic membrane for:\n\n- inverted (protected membrane) roofs on concrete decks\n- podium decks, plazas and terraces over occupied space\n- green and blue roofs\n- zero-fall roofs, where third-party certified systems are permitted\n\nUK warranty guidance for zero-fall roofs accepts BBA-certified liquid-applied or hot-melt systems approved for zero falls in an inverted build-up, and does not accept excess hot-melt material left around outlets that impedes drainage.\n\n## Codes of practice\n\nIn the UK the Liquid Roofing and Waterproofing Association publishes a Hot Melt Code of Practice, updated to reflect BS 6229:2025.\n\n## Considerations\n\n- deck must be sound, clean, dry and primed; it is mostly used on concrete\n- hot work requires fire precautions and trained operatives\n- the membrane is not UV-stable and must be covered\n- integrity testing, often electronic, is commonly carried out before overburden is placed","key_facts":[{"label":"Material","value":"Rubber-modified bitumen, hot-applied"},{"label":"Typical build","value":"Two coats with polyester reinforcement"},{"label":"Main uses","value":"Inverted, podium, green, blue and zero-fall roofs"},{"label":"UK guidance","value":"LRWA Hot Melt Code of Practice"}],"regions":["Europe","North America"],"aliases":["hot melt","hot rubberized asphalt","HRA","hot-applied rubberised bitumen"],"related":["protected-membrane-roof","green-roof","blue-roof","liquid-applied-roofing","mastic-asphalt-roofing"],"company":null,"sources":[{"title":"BS 6229:2018 and flat roofing systems","url":"https://ikogroup.co.uk/?p=820","publisher":"IKO"},{"title":"What is the minimum drainage falls for a single ply flat roof?","url":"https://ikogroup.co.uk/?p=829","publisher":"IKO"},{"title":"Major Projects: Zero falls flat roof policy","url":"https://labcwarranty.co.uk/blog/major-projects-zero-falls-flat-roof-policy/?hsLang=en","publisher":"LABC Warranty"},{"title":"Liquid Roofing and Waterproofing Association","url":"https://www.lrwa.org.uk/","publisher":"LRWA"},{"title":"Quality alert: flat and inverted roofs","url":"https://wa-uks-constructionqualitypathway-pr.azurewebsites.net/media/lsfeckuo/quality-alert-flat-and-inverted-roofs.pdf","publisher":"Construction Quality Pathway"}],"country":null},{"slug":"hot-mopped-built-up-roof","title":"Hot-Mopped Built-Up Roof Application","category":"installation","type":"article","summary":"Hot-mopped built-up roofing (BUR) bonds several plies of roofing felt with layers of hot asphalt or coal-tar pitch applied by mop or mechanical spreader.","body":"A **built-up roof (BUR)** is a low-slope membrane made of several layers (plies) of reinforcing felt bonded together with hot bitumen and finished with a surfacing such as gravel, a cap sheet or a coating. In hot-mopped application the bitumen is heated in a kettle or tanker, carried to the roof and spread by mop or mechanical applicator just ahead of each roll of felt.\n\n## Bitumen\n\nTwo bitumen families are used:\n\n- **Asphalt**, graded by softening point and suitable slope. Canadian guidance lists Type 1 (minimum 60 °C / 140 °F) for the flattest roofs, Type 2 (75 °C / 167 °F) and Type 3 (90 °C / 194 °F) for steeper slopes and flashings.\n- **Coal-tar pitch**, used only on very low slopes (below 1:25, or 4 percent) and never mixed with asphalt in the same membrane.\n\n## Temperature control\n\nThe key concept is the **equiviscous temperature (EVT)**, the temperature at which the bitumen has the right viscosity to flow, spread at the correct rate and bond. Canadian guidance says the application temperature should stay within 15 °C (27 °F) of the EVT at the point of application, checked with a thermometer, and that bitumen must never reach its flash point. Kettles are run slightly above EVT to allow for heat loss in transport.\n\n## Laying the plies\n\n1. Start at the lowest point of the roof, laying felts so water flows over the laps, not against them.\n2. Mop no more than about 900 mm (3 ft) ahead of the roll.\n3. Apply at the specified rate; Canadian guidance gives about 1.0 kg/m² (20 lb per square) for organic felts and 1.2 kg/m² (25 lb per square) for glass-fibre felts.\n4. Broom organic felts into the bitumen to expel trapped air; glass-fibre felts generally need no brooming.\n5. Shingle the plies so that the lap sets the number of layers: half-lapping gives two plies, two-thirds three plies and three-quarters four plies.\n\nCanadian guidance discourages **phased application**, where some plies are left for a later day, because dirt and moisture trapped between plies cause poor adhesion and blisters.\n\n## Surfacing and flashings\n\nThe finished membrane is protected with a flood coat and aggregate, a mineral-surfaced cap sheet or a reflective coating. Base and cap flashings at walls and curbs are built from reinforced membrane plies. Kettle operation, hoisting and carrying hot bitumen carry serious burn and fire risks and require trained crews.","key_facts":[{"label":"Application temperature","value":"Within 15 C (25 F) of the EVT"},{"label":"Mop ahead of roll","value":"No more than 900 mm (3 ft)"},{"label":"Typical plies","value":"3 or 4"},{"label":"Coal-tar pitch slope limit (Canada)","value":"Below 1:25 (4%)"}],"regions":["North America","Global"],"aliases":["BUR application","hot-mop roofing","tar and gravel roof installation"],"related":["torch-applied-roofing","roofing-kettle"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 4.1.1 Application of Bitumen","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-4-built-up-roof-membranes/4-1-hot-applied-built-up/4-1-1-application-of-bitumen/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 4.1.2 Application of Roofing Felts","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-4-built-up-roof-membranes/4-1-hot-applied-built-up/4-1-2-application-of-roofing-felts/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 5.2.2 Application of Membrane","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-5-modified-bituminous-membranes/5-2-membrane-installation/5-2-2-application-of-membrane/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"how-to-find-a-licensed-roofer","title":"How to Find a Licensed Roofer (by Country)","type":"article","summary":"A country-by-country guide to how roofers are licensed or registered, and where homeowners can check a contractor's credentials.","body":"Rules for who may work on a roof differ greatly around the world. In some places roofing contractors need a government licence; in others there is no licence at all and homeowners rely on trade association membership, voluntary schemes and references. This guide summarises the main systems and the public bodies where credentials can be checked. Rules change, so always confirm with the local authority.\n\n## United States\n\nLicensing is handled by states and sometimes by cities or counties, not nationally.\n\n- **Florida** licenses roofing contractors through the Construction Industry Licensing Board (CILB). A *certified* roofing contractor may work anywhere in the state; a *registered* roofing contractor may work only in the local jurisdictions where they met competency requirements. Licences can be checked through the state's online licence search.\n- **Texas** has no state roofing licence. The Roofing Contractors Association of Texas (RCAT) offers a voluntary \"RCAT Roofing License\" that requires exams, insurance, a background check and continuing education.\n- Other states range from full contractor licensing to simple registration. State contractor boards usually offer online lookups.\n\n## Canada\n\nContractor licensing is mostly municipal or provincial, while trade certification is provincial. In **Ontario**, Skilled Trades Ontario issues Certificates of Qualification and keeps a Public Register for compulsory trades. In **British Columbia**, the Roofing Contractors Association of British Columbia (RCABC) lists member contractors eligible for its RoofStar Guarantee warranty program. The Canadian Roofing Contractors Association (CRCA) is the national trade body.\n\n## United Kingdom\n\nThere is no general legal licence for roofers. Common checks include:\n\n- **TrustMark**, the Government Endorsed Quality Scheme, with a \"Find a tradesperson\" search;\n- **Competent Person Scheme** registration, such as the NFRC scheme, which lets firms self-certify re-roofing under building regulations;\n- membership of trade bodies such as the **NFRC** or **CORC**, and whether an insurance-backed warranty is offered.\n\n## New Zealand\n\nRoofing on homes is restricted building work and must be done or supervised by a **Licensed Building Practitioner** holding a roofing licence, with classes for membrane, metal tile, profiled metal, shingles, torch-on and liquid roofing. The Roofing Association of New Zealand (RANZ) lists vetted members.\n\n## Australia\n\nLicensing is set by each state and territory. Depending on the state, roofing, roof tiling or roof plumbing may need a licence, and thresholds based on the value of work often apply. Check with the state building, plumbing or fair trading regulator. Master Builders associations and specialist roofing associations provide member directories.\n\n## Germany\n\nRoofing (Dachdecker) is a regulated craft. Running a roofing business traditionally requires a master craftsman qualification or equivalent and registration with the local chamber of crafts. Local roofing guilds belong to the national ZVDH.\n\n## General checks anywhere\n\n- Ask for licence or registration numbers and verify them directly with the issuing body.\n- Confirm liability and workers' insurance.\n- Get written, itemised quotes and ask who will do the work.\n- Ask what warranty covers workmanship and materials, and in writing.\n- Be cautious with door-to-door offers after storms.","key_facts":[{"label":"United States","value":"State-by-state; e.g. Florida CILB licenses roofers, Texas has no state roofing licence"},{"label":"United Kingdom","value":"No general licence; TrustMark and Competent Person Schemes"},{"label":"New Zealand","value":"Licensed Building Practitioner roofing licence for restricted building work"},{"label":"Germany","value":"Regulated craft; master qualification traditionally required"}],"regions":["Global","North America","Europe","Oceania"],"aliases":["roofer licensing","find a roofer","contractor licence check"],"related":["florida-construction-industry-licensing-board","roofing-contractors-association-of-texas","skilled-trades-ontario","trustmark","roofing-association-of-new-zealand","zvdh"],"company":null,"sources":[{"title":"Construction Industry Licensing Board","url":"https://www2.myfloridalicense.com/construction-industry/","publisher":"Florida DBPR"},{"title":"RCAT creates a licensing program to help prevent scams","url":"https://www.roofingcontractor.com/articles/92243-the-roofing-contractors-association-of-texas-creates-a-licensing-program-to-help-prevent-scams","publisher":"Roofing Contractor"},{"title":"About Skilled Trades Ontario","url":"https://www.skilledtradesontario.ca/about-us/","publisher":"Skilled Trades Ontario"},{"title":"TrustMark","url":"https://www.trustmark.org.uk/","publisher":"TrustMark"},{"title":"Roofing licence classes","url":"https://www.lbp.govt.nz/about-lbp/licence-classes/roofing/","publisher":"Licensed Building Practitioners (MBIE)"}],"category":"organizations","country":null},{"slug":"hurricane-roof-damage","title":"Hurricane Roof Damage","type":"article","summary":"How tropical cyclones (hurricanes, typhoons and cyclones) damage roofs, from lost coverings and edges to deck blow-off and wind-driven rain.","body":"Tropical cyclones are called hurricanes in the Atlantic and northeastern Pacific, typhoons in the northwestern Pacific, and cyclones or severe cyclonic storms in the Indian Ocean and South Pacific. Whatever the local name, the roof is usually the first part of a building to fail, and roof damage is a leading cause of the water damage that follows a storm.\n\nPost-storm investigations by the US Federal Emergency Management Agency (FEMA) and others, from Hurricane Andrew (1992) to Hurricane Michael (2018), show the same chain of failures repeating: the roof covering is lost first, water then enters through the exposed deck, and in stronger winds the deck and framing can be lifted away.\n\n## How wind attacks a roof\n\nWind flowing over a building creates suction (negative pressure) on the roof surface. Suction is strongest at corners, eaves, rakes, hips and ridges, which is why damage tends to start at these locations. If a window, door or garage door is broken, wind entering the building adds internal pressure that pushes the roof upward from below, greatly increasing the load on the roof deck and its connections.\n\n## Common failure modes\n\n- **Roof covering loss.** Shingles, tiles and panels are torn off when fasteners are too few, misplaced or poorly driven, or when sealant strips do not bond. Investigators after the 2004 Florida storms and after Michael repeatedly found shingle nails placed too high on the shingle.\n- **Edge and ridge failures.** Drip edge, fascia, gutters, ridge caps and ridge vents fail early because pressures there are highest. Lost ridge vents leave an open slot in the deck.\n- **Soffit failure.** Soffit panels that blow out let wind-driven rain into attics, even on roofs that otherwise survive.\n- **Deck (sheathing) loss.** Panels pull off rafters or trusses when nailing is inadequate, often after the building envelope is breached.\n- **Structural loss.** In the most severe winds, weak roof-to-wall connections allow the entire roof structure to lift off.\n\n## Water intrusion\n\nEven moderate damage can lead to large losses. Wind-driven rain entering through missing coverings, open deck joints, vents and soffits soaks insulation and ceilings and promotes mold. After Michael, FEMA noted buildings that were unusable for extended periods because of this water damage rather than structural failure.\n\n## Codes and mitigation\n\nFlorida strengthened its code after Andrew, and later reviews found that homes built under newer rules in Charlotte County needed fewer roof covering replacements than older homes after the 2004 storms. Current mitigation focuses on a continuous load path (deck nailing and roof-to-wall connectors), stronger edge details, wind-rated coverings, and a secondary water barrier or sealed roof deck. Programs such as FORTIFIED in the United States package these measures into a designation.\n\n## Saffir-Simpson scale and roofs\n\nThe US National Hurricane Center's Saffir-Simpson Hurricane Wind Scale describes expected damage to well-built homes by category: Category 1 (119-153 km/h, 74-95 mph) damages roof coverings and gutters; Category 3 (178-208 km/h, 111-129 mph) can remove roof decking and gable ends; Category 5 (252 km/h, 157 mph or higher) can cause total roof failure. The scale rates wind only, not storm surge or rainfall.","key_facts":[{"label":"First component to fail","value":"Usually the roof covering, at corners, edges and ridges"},{"label":"Category 1 winds","value":"119-153 km/h (74-95 mph): roof covering and gutter damage"},{"label":"Category 3 winds","value":"178-208 km/h (111-129 mph): possible loss of decking and gable ends"},{"label":"Regional names","value":"Hurricane, typhoon, cyclone"}],"regions":["Global","North America","East Asia","Southeast Asia","South Asia","Oceania"],"aliases":["typhoon roof damage","cyclone roof damage","tropical cyclone roof damage","wind damage to roofs"],"related":["roof-to-wall-connection","hurricane-tie","secondary-water-barrier","sealed-roof-deck","fortified-roof","wind-uplift","roof-wind-pressure-zones","climate-change-and-roofing"],"sources":[{"title":"From Hurricanes Andrew to Michael: Lessons Learned for Residential Roofing","url":"https://iibec.org/publication-post/from-hurricanes-andrew-to-michael-lessons-learned-for-residential-roofing/","publisher":"IIBEC"},{"title":"Summary Report on Building Performance: 2004 Hurricane Season (FEMA 490)","url":"https://www.fema.gov/sites/default/files/2020-08/fema490.txt","publisher":"FEMA"},{"title":"Saffir-Simpson Hurricane Wind Scale","url":"https://www.nhc.noaa.gov/aboutsshws.php","publisher":"NOAA National Hurricane Center"},{"title":"Tropical cyclone","url":"https://en.wikipedia.org/wiki/Tropical_cyclone","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"hurricane-tie","title":"Hurricane Tie","type":"term","summary":"A metal strap or clip that fastens a rafter or truss to the wall to resist wind uplift; also called a hurricane clip or hurricane strap.","body":"A hurricane tie is a formed metal connector that links roof framing to the wall below. It is also called a hurricane clip, hurricane strap or, in some regions, a cyclone tie. Ties are generally made of galvanized or stainless steel and are nailed or screwed to both the rafter or truss and the wall top plate (or embedded in a masonry bond beam).\n\n## What it does\n\nDuring high winds, suction on the roof surface and pressure inside the building try to lift the roof. A hurricane tie resists this uplift and also helps resist sliding, racking and overturning. It is one link in a continuous load path from roof deck to foundation.\n\n## Types\n\n- **Clips** that wrap around the side of a rafter or truss and fasten to the top plate.\n- **Twist straps** that turn 90 degrees so they can fasten to the face of a truss at its heel and the face of a wall stud or plate.\n- **Straps** that run from framing down the wall and may continue to studs or lower floors.\n- **Embedded straps** cast into concrete or grouted masonry walls, common in Florida and the Caribbean.\n\n## Performance in the field\n\nFEMA's investigation of the 2011 tornadoes in Alabama and Joplin, Missouri found that metal connectors performed better than toenailed connections, but only when installed as the manufacturer specified. Common errors included wrong nail type or size, too few nails, and connectors on only some rafters. Because each product has a published load rating that depends on the fastener schedule, substituting nails can greatly reduce capacity.\n\n## Codes and retrofits\n\nBuilding codes in hurricane-prone areas of the United States require uplift connections designed for local wind speeds, and the Florida Building Code addresses roof-to-wall attachment for both new construction and certain reroofing projects. Retrofit ties can be added to existing homes, often from outside while the roof covering is removed. Wind mitigation inspections in Florida record the type of connection (toenail, clip, single wrap, double wrap) because insurers offer credits for stronger connections.\n\n## Corrosion\n\nIn coastal areas, salt spray can corrode connectors over time. Heavier galvanizing or stainless steel is often specified where exposure is severe, and connectors should be compatible with treated lumber.","key_facts":[{"label":"Materials","value":"Galvanized or stainless steel"},{"label":"Resists","value":"Uplift, sliding, racking"},{"label":"Critical detail","value":"Use the exact fasteners listed by the manufacturer"}],"regions":["North America","Latin America","Oceania","Global"],"aliases":["hurricane clip","hurricane strap","cyclone tie","rafter tie-down"],"related":["roof-to-wall-connection","hurricane-roof-damage","tornado-roof-damage","coastal-corrosion","roof-insurance-discounts"],"sources":[{"title":"Hurricane tie","url":"https://en.wikipedia.org/wiki/Hurricane_tie","publisher":"Wikipedia"},{"title":"Tornado Outbreak of 2011 Mitigation Assessment Team Report, Chapter 4 (FEMA P-908)","url":"https://webarchive.library.unt.edu/web/20161127152300/https://www.fema.gov/media-library-data/20130726-1827-25045-9156/tornado_mat_chapter4_508.pdf","publisher":"FEMA (archived by UNT Libraries)"},{"title":"Strengthening Roof-to-Wall Connections","url":"https://www.jlconline.com/coastal-contractor/strengthening-roof-to-wall-connections.aspx","publisher":"JLC (Journal of Light Construction)"},{"title":"Hurricane Mitigation Techniques, Proposed IBHS Language","url":"https://www.floridabuilding.org/fbc/thecode/Hurri_Mit_Techniq_compar_1207_ibhs.htm","publisher":"Florida Building Commission"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"hyperbolic-paraboloid-roof","title":"Hyperbolic Paraboloid Roof (Hypar)","category":"roof-forms","type":"article","summary":"A hyperbolic paraboloid roof is a saddle-shaped, doubly curved roof that can be built from straight members, used for thin concrete shells and tensile structures.","body":"A hyperbolic paraboloid, often shortened to hypar, is a saddle-shaped surface that curves upward in one direction and downward in the direction at right angles. Mathematically it is a doubly ruled surface: although it is curved, it can be generated entirely by straight lines. This property makes hypar roofs practical to build, because the curved form can be produced with straight timber boards, straight formwork for concrete, or straight steel members.\n\n## Why it works structurally\n\nThe double curvature gives the surface great stiffness, so a hypar can span large areas with a very thin shell. Loads are carried largely by direct tension and compression within the surface rather than by bending. The edges typically need stiffening beams that collect forces and carry them to a small number of supports.\n\n## Notable designers and examples\n\n- **Félix Candela (1910-1997):** the Spanish-born architect and engineer who worked in Mexico became the best-known builder of thin reinforced-concrete hypar shells. Examples include the Cosmic Rays Pavilion at the National Autonomous University of Mexico (1951) and the Los Manantiales restaurant in Xochimilco, Mexico City (1958), designed with Joaquín Álvarez Ordóñez.\n- **Warszawa Ochota railway station,** Warsaw, Poland (1962), has a hypar saddle roof.\n- **Scotiabank Saddledome,** Calgary, Canada (1983), uses a hypar saddle roof.\n- Le Corbusier also used hypar surfaces.\n\n## Construction methods\n\n- **Concrete shells:** cast on timber formwork made of straight boards set along the ruling lines.\n- **Timber:** layered boards or glulam edge beams.\n- **Steel and cable nets:** tensioned cables and membranes forming saddle surfaces.\n\n## Roofing considerations\n\nWaterproofing a doubly curved surface is demanding: membranes, liquid-applied coatings, flexible metal or shingles that can follow the curve are used. Low points at the corners concentrate drainage, and the edges need robust flashing and gutters.","key_facts":[{"label":"Geometry","value":"Doubly curved, doubly ruled saddle"},{"label":"Key designer","value":"Félix Candela (1910-1997)"},{"label":"Los Manantiales","value":"Xochimilco, 1958"},{"label":"Saddledome","value":"Calgary, 1983"}],"regions":["Global","Latin America","North America","Europe"],"aliases":["hypar","saddle roof","hyperbolic paraboloid shell"],"related":["barrel-vault-roof","dome","butterfly-roof"],"company":null,"sources":[{"title":"Hyperboloid structure","url":"https://en.wikipedia.org/wiki/Hyperboloid_structure","publisher":"Wikipedia"},{"title":"Félix Candela","url":"https://en.wikipedia.org/wiki/Félix_Candela","publisher":"Wikipedia"},{"title":"Roof","url":"https://www.designingbuildings.co.uk/wiki/Roof","publisher":"Designing Buildings Wiki"}],"country":null},{"slug":"ibhs-fortified-roof","title":"IBHS FORTIFIED Roof","summary":"FORTIFIED Roof is a voluntary US construction standard from IBHS that strengthens roofs against high wind, hurricanes and hail, verified by third-party evaluators.","body":"FORTIFIED is a voluntary building program run by the Insurance Institute for Business & Home Safety (IBHS), a US research organization funded by property insurers. **FORTIFIED Roof** is its first and most widely used level; FORTIFIED Silver and Gold add requirements for windows, doors, gable ends and the connection of the roof to the walls. The program is based on IBHS laboratory and field research into how homes fail in storms.\n\nUnlike a product rating, FORTIFIED is a designation for a whole home. A trained evaluator inspects and documents the work during installation, and IBHS issues a certificate when the requirements are met.\n\n## Key requirements\n\nThe FORTIFIED Roof standard asks for several upgrades beyond typical code minimums:\n\n- **Sealed roof deck.** The joints in the roof sheathing are sealed, so if wind strips off the roof covering, rain cannot pour through the gaps. IBHS says this can reduce water entry by up to 95%.\n- **Ring-shank nails.** Sheathing is fastened with 8d ring-shank nails at closer spacing instead of smooth nails. IBHS testing indicates this can roughly double uplift resistance.\n- **Locked-down edges.** A wider drip edge and a fully adhered starter strip help keep wind from getting under the roof edge.\n- **Rated roof covers.** Asphalt shingles must carry an [ASTM D3161](/astm-d3161) Class F or [ASTM D7158](/astm-d7158) Class H wind rating, and all roof systems must be rated for the design pressures at the site.\n\n## Hail supplement\n\nAn optional hail supplement targets hail-prone regions. It calls for asphalt shingles rated \"Good\" or \"Excellent\" in IBHS's own hail impact ratings, [UL 2218](/ul-2218) Class 4 for metal and low-slope roofs, and [FM 4473](/fm-4473) Class 4 for tile.\n\n## Insurance and public programs\n\nSeveral US states have linked insurance rules and grants to FORTIFIED. Alabama is the best-known case: a 2009 state insurance law requires insurers to offer premium discounts for homes certified as FORTIFIED, with savings reported of up to 50% on the wind portion of a policy, and a state grant program has paid for FORTIFIED roofs in coastal counties. Georgia, Mississippi, North Carolina and Oklahoma have passed similar insurance laws, and other states, including Louisiana and South Carolina, encourage FORTIFIED construction. Discount levels and eligibility differ by state and insurer.\n\n## Relationship to building codes\n\nFORTIFIED is not a building code. In most places it is an above-code option chosen by homeowners, builders or grant programs. Some features, such as sealed roof decks, have been proposed or adopted in code updates in hurricane-prone states.","key_facts":[{"label":"Run by","value":"Insurance Institute for Business & Home Safety (IBHS)"},{"label":"Levels","value":"FORTIFIED Roof, Silver, Gold"},{"label":"Sheathing nails","value":"8d ring-shank"},{"label":"Shingle wind rating","value":"ASTM D3161 Class F or ASTM D7158 Class H"},{"label":"Verification","value":"Third-party FORTIFIED evaluator"}],"regions":["North America"],"aliases":["FORTIFIED","FORTIFIED Home","FORTIFIED Roof standard","IBHS FORTIFIED"],"related":["sealed-roof-deck","ul-2218","astm-d3161","impact-resistant-roof-insurance-discounts"],"sources":[{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/?p=2512","publisher":"IBHS FORTIFIED"},{"title":"Using Special Nails to Save Roofs — and Dollars","url":"https://www.pewtrusts.org/research-and-analysis/blogs/stateline/2017/06/21/using-special-nails-to-save-roofs-and-dollars","publisher":"Pew / Stateline"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"ibr-roof-sheeting","title":"IBR Roof Sheeting","category":"materials","type":"term","summary":"IBR (inverted box rib) is a trapezoidal profiled steel roof and wall sheet widely used in southern Africa, typically covering 686 mm per sheet.","body":"IBR, short for inverted box rib, is a trapezoidal profiled metal sheet used for roofs and walls of houses, farm buildings, warehouses and factories in South Africa and neighbouring countries. It is the southern African counterpart of the box-profile or trapezoidal sheets used elsewhere.\n\n## Profile\n\nManufacturers' data for a typical South African IBR sheet give:\n\n- Effective cover width: 686 mm (27 in); overall width 740 mm (29 in).\n- Broad flute pitch: 171.5 mm (6.75 in), with stiffening ribs between the main ribs.\n- Thicknesses: 0.40, 0.47, 0.50, 0.55, 0.58 and 0.80 mm (0.016 to 0.031 in).\n\n## Materials and finishes\n\nIBR is roll-formed from steel coil with:\n\n- Galvanised zinc coatings (Z150, Z200, Z275).\n- Aluminium-zinc coatings (AZ150).\n- Pre-painted finishes on coated steel.\n\n## Pitch and spans\n\nThe minimum recommended roof pitch is 5 degrees for roof slopes shorter than 30 m (98 ft) and 7.5 degrees for longer slopes. Recommended maximum purlin spacings for roofs, from one manufacturer's data, are:\n\n| Sheet thickness | Single span | Double span |\n|---|---|---|\n| 0.40 mm | 1.25 m (4.1 ft) | 1.40 m (4.6 ft) |\n| 0.47-0.50 mm | 1.65 m (5.4 ft) | 1.95 m (6.4 ft) |\n| 0.55-0.58 mm | 1.75 m (5.7 ft) | 2.10 m (6.9 ft) |\n| 0.80 mm | 2.25 m (7.4 ft) | 2.50 m (8.2 ft) |\n\nWall rails can be spaced further apart, for example 1.70 m (5.6 ft) single span for 0.40 mm sheet. These are general guidelines, and an engineer's design is advised for specific buildings.\n\n## Use\n\nIn South Africa, corrugated iron or zinc sheet, the census category that includes profiled steel sheet such as IBR, was the most common roof material recorded in the 2011 census sample file.","key_facts":[{"label":"Full name","value":"Inverted box rib"},{"label":"Cover width","value":"686 mm (27 in)"},{"label":"Thickness range","value":"0.40-0.80 mm (0.016-0.031 in)"},{"label":"Minimum pitch","value":"5 degrees (slopes under 30 m)"},{"label":"Region","value":"Southern Africa"}],"regions":["Africa"],"aliases":["inverted box rib","IBR sheet","IBR profile"],"related":["metal-roofing","corrugated-iron","roofing-in-south-africa","sheet-metal-gauge"],"company":null,"sources":[{"title":"IBR sheeting technical data","url":"https://www.specifile.co.za/wp-content/uploads/2019/04/IBR.pdf","publisher":"Clotan Steel (via Specifile)"},{"title":"IBR 686","url":"https://globalroofs.co.za/ibr-686","publisher":"Global Roofing Solutions"}],"country":null},{"slug":"icc-es-evaluation-reports","title":"ICC-ES Evaluation Reports (ESR)","type":"term","summary":"ICC-ES Evaluation Reports are technical reports that show whether a building product, such as a roofing system, complies with US model codes like the IBC and IRC.","body":"**ICC Evaluation Service (ICC-ES)** is a subsidiary of the International Code Council, the publisher of the [International Building Code](/international-building-code) and [International Residential Code](/international-residential-code). It evaluates building products, materials and systems to help building officials decide whether they comply with codes.\n\nIts main output is the **Evaluation Report**, usually identified by the prefix **ESR** followed by a number.\n\n## What an evaluation report is\n\nAn ESR presents the findings of a technical evaluation of a product. It is mainly used for new and innovative products whose code compliance cannot simply be demonstrated by citing a product standard listed in the code. Each report typically includes:\n\n- product identification and description\n- the code sections and acceptance criteria used in the evaluation\n- design and installation requirements\n- conditions of use and limitations\n\nAn optional **Supplement Report** can add state or local code requirements, such as those of the Florida Building Code, to the base report, giving code officials jurisdiction-specific documentation.\n\n## Acceptance criteria\n\nWhere codes do not contain a test standard for a product, ICC-ES develops **Acceptance Criteria (ACs)**, which define the tests and evidence required. Proposed criteria are reviewed by an Evaluation Committee. Acceptance criteria exist for many roofing-related products, such as synthetic underlayments, roof coatings and some roof covering types.\n\n## Use in roofing\n\nRoofing manufacturers obtain ESRs for products such as:\n\n- synthetic and self-adhered underlayments\n- stone-coated steel and other non-traditional roof coverings\n- composite or polymer shingles and slates\n- roof coatings and spray foam systems\n\nBuilding officials can accept an ESR as evidence that a product complies with the code, although the final decision rests with the local authority. Contractors are expected to install the product according to the report's conditions.\n\n## Other ICC-ES programs\n\nICC-ES also runs listing and certification programs for plumbing, mechanical and electrical products, environmental product declarations and verification, testing services, and a Florida approval program.\n\n## Comparable systems\n\n- In Florida, statewide [Florida Product Approval](/florida-product-approval) accepts evaluation reports from approved entities.\n- In Canada, the [National Research Council's](/national-building-code-of-canada) Canadian Construction Materials Centre performs a similar role.\n- In the UK, [BBA Agrément Certificates](/bba-agrement) serve a comparable function.","key_facts":[{"label":"Issuer","value":"ICC Evaluation Service (ICC-ES)"},{"label":"Parent","value":"International Code Council"},{"label":"Report identifier","value":"ESR number"},{"label":"Evaluation basis","value":"Code provisions and Acceptance Criteria (ACs)"},{"label":"Add-on","value":"Supplement Reports for state/local codes"}],"regions":["North America"],"aliases":["ICC-ES","ESR","ICC-ES report","evaluation report"],"related":["international-building-code","florida-product-approval","bba-agrement","roofing-underlayment"],"sources":[{"title":"ICC Evaluation Service","url":"https://icc-es.org/","publisher":"ICC-ES"},{"title":"Evaluation Report Program","url":"https://icc-es.org/evaluation-report-program/","publisher":"ICC-ES"},{"title":"Product Approval Regulation in Florida","url":"https://www.engineeringplans.com/?p=1806","publisher":"EngineeringPlans.com"}],"category":"standards-codes","company":null,"country":null},{"slug":"ice-and-water-shield","title":"Ice and Water Shield (Self-Adhered Ice Barrier)","category":"components","type":"article","summary":"Ice and water shield is a self-adhering polymer-modified bitumen membrane applied at eaves, valleys and penetrations to stop water backed up by ice dams.","body":"\"Ice and water shield\" is the common trade name for self-adhered underlayment membranes, usually rubberised or polymer-modified bitumen with a peel-off release film and a surfacing of film, sand or fabric. The membrane bonds directly to the roof deck and seals around nail shanks driven through it, so it resists water that is pushed uphill under shingles or tiles. Building codes call it an ice barrier, and in Canada the comparable requirement is called eave protection.\n\n## Why it is used\n\nIn cold climates, heat escaping from a house can melt snow on the upper roof. The meltwater refreezes at the colder overhang, forming an ice dam, and water ponds behind it and backs up under the roof covering. A sealed membrane at the eaves keeps that water out of the building.\n\n## Code requirements (United States)\n\nUnder International Residential Code section R905.1.2, where the local jurisdiction has a history of ice forming at the eaves, an ice barrier is required. It must extend from the lowest edges of the roof surfaces to a point at least 24 in (610 mm) inside the exterior wall line of the building, measured horizontally. The barrier can be either at least two layers of underlayment cemented together or a self-adhering polymer-modified bitumen sheet. Detached accessory structures without conditioned space are commonly exempt; local amendments often extend coverage further.\n\n## Other common uses\n\n- Valleys, where water concentrates.\n- Around chimneys, skylights, and sidewall and headwall flashings.\n- Low-slope sections and roof-to-wall transitions.\n- Full-deck coverage in hurricane zones or under metal roofs, depending on manufacturer and code.\n\n## Cautions\n\nSelf-adhered membranes are generally vapour-impermeable, so covering an entire roof can affect how the assembly dries. Some products are not rated for the high temperatures under metal roofing, and the membrane should not be left exposed longer than the manufacturer allows.","key_facts":[{"label":"US code section","value":"IRC R905.1.2"},{"label":"Minimum extent (IRC)","value":"24 in (610 mm) inside exterior wall line"},{"label":"Canadian term","value":"Eave protection"}],"regions":["North America","Europe"],"aliases":["ice barrier","self-adhered underlayment","peel-and-stick membrane","ice and water barrier"],"related":["eave-protection","roofing-underlayment","eaves","roof-valley","ice-dam"],"company":null,"sources":[{"title":"Ice barrier code (IRC 2021 R905.1.2)","url":"https://www.jaspector.com/codes/irc-2021/ch09-roof-assemblies/ice-barrier-code/","publisher":"Jaspector"},{"title":"Ice-Dam Protection: How Far Up the Roof Slope?","url":"https://www.finehomebuilding.com/project-guides/roofing/ice-barriers-explained-far-roof-slope","publisher":"Fine Homebuilding"},{"title":"Asphalt Shingle Installation (2022 Connecticut State Building Code)","url":"https://www.meridenct.gov/Customer-Content/www/CMS/files/Building/Asphalt_Shingle_Installation.pdf","publisher":"City of Meriden, Connecticut, Building Division"},{"title":"Roof Replacements","url":"https://pwcaws.pwcva.gov/assets/2021-04/roofreplacements.pdf","publisher":"Prince William County, Virginia"}],"country":null},{"slug":"ice-barrier-installation","title":"Ice Barrier Installation","category":"installation","type":"article","summary":"An ice barrier is a self-adhering membrane or cemented underlayment installed at the eaves to resist water backing up under shingles from ice dams.","body":"An **ice barrier**, also called **eave protection** or an **ice and water shield**, is a waterproof membrane installed along the lower edge of a pitched roof. Its purpose is to keep out water that backs up behind ice dams, which form when snow melts over a warm roof and refreezes at the colder eaves. Ice barriers are standard in North America and other cold climates; they are uncommon in mild-winter regions.\n\n## When it is required\n\nUnder the US International Residential Code, an ice barrier is required in areas where ice damming has historically occurred. Each jurisdiction decides where the requirement applies, based on its local history of ice damming. Canadian practice treats eave protection as standard over most of the country.\n\n## Materials\n\nBuilding America guidance lists two acceptable forms:\n\n- at least two layers of underlayment cemented together; or\n- a self-adhering polymer-modified bitumen membrane.\n\nSelf-adhered membranes are the common modern choice because they seal around nail shanks.\n\n## Coverage\n\nThe IRC requires the barrier to run from the eave edge to a point at least 24 in (610 mm) inside the exterior wall line of the building. On homes with deep overhangs, this often means two or more courses. Building America guidance adds that on slopes steeper than 8:12, the barrier should extend at least 36 in (914 mm) measured along the slope. Canadian tile guidance specifies eave protection extending at least 1220 mm (48 in) up the slope.\n\n## Installation steps\n\n1. Clean the deck and check that it is dry and within the membrane's temperature range.\n2. Measure the required coverage from the eave edge to the point inside the wall line.\n3. Unroll, position and remove the release film, pressing the sheet down from the centre outward.\n4. Lap successive courses and end joints as the manufacturer specifies.\n5. Integrate with drip edge, valleys and penetrations.\n\nIn Bloomington, Minnesota, the code allows an existing adhered ice barrier to remain and be covered with a new layer during re-roofing. Ice barriers reduce the effects of ice dams but do not prevent them; insulation, air sealing and ventilation address the cause.","key_facts":[{"label":"IRC coverage","value":"At least 24 in (610 mm) inside the exterior wall line"},{"label":"Extra coverage on steep slopes (Building America)","value":"36 in (914 mm) along slope above 8:12"},{"label":"Common material","value":"Self-adhered polymer-modified bitumen"}],"regions":["North America","Europe","East Asia"],"aliases":["eave protection","ice and water shield","ice dam protection membrane"],"related":["underlayment-installation","ice-dam","cold-weather-roofing","roof-replacement-process"],"company":null,"sources":[{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"},{"title":"Asphalt shingle installation requirements, IRC 2024","url":"https://www.jaspector.com/codes/irc-2024/ch09-roof-assemblies/asphalt-shingle-installation-irc-2024/","publisher":"Jaspector"},{"title":"Reroofing","url":"https://www.bloomingtonmn.gov/sites/default/files/2023-08/Reroofing.pdf","publisher":"City of Bloomington, Minnesota"},{"title":"Canadian Roofing Reference Manual: 9.3.3 Tile Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-3-tiles-clay-concrete-slate-metal/9-3-3-installation/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"ice-dam","title":"Ice Dam","type":"term","summary":"A ridge of ice that forms at the eaves of a snow-covered roof and traps meltwater, which can then back up under the roofing and leak.","body":"An ice dam is a ridge of ice that builds up along the lower edge of a sloped roof in winter. Water from melting snow higher up runs down to the cold eaves, refreezes, and forms a barrier. Further meltwater pools behind the dam and can work its way up under shingles or tiles and into the building, damaging ceilings, walls and insulation.\n\n## How ice dams form\n\nThree conditions must occur together:\n\n1. Outdoor air well below freezing.\n2. A layer of snow on the roof, which insulates the roof surface.\n3. Heat reaching the underside of the roof deck, usually from the building below.\n\nThe upper roof, warmed from beneath, stays above freezing and melts the bottom of the snow. The eaves, which overhang the exterior walls and receive no building heat, stay below freezing. Ice dams are associated with conditions where the roof deck under the snow is above about -1 °C (30 °F) while outdoor air is below about -6 °C (22 °F).\n\n## Causes inside the building\n\nBuilding science research identifies air leakage as the main way heat reaches the roof deck: warm air escaping through ceiling penetrations, leaky ductwork in attics, recessed lights and gaps in the ceiling air barrier. Insufficient insulation also contributes.\n\n## Prevention\n\n- **Air sealing** the ceiling plane and attic penetrations, usually the most effective step.\n- **Adequate insulation** to keep heat in the living space.\n- **Attic ventilation** to keep the roof deck cold, creating a so-called cold roof.\n- **Roof design:** steep, smooth roofs with few valleys shed snow before it can melt and refreeze.\n- **Eave protection:** a self-adhered membrane (often called ice and water barrier) at the eaves is required by US building codes in cold regions. It reduces leaks if a dam forms but does not prevent the dam.\n- **Metal eave bands** provide a slippery surface that may reduce dam formation.\n\n## Heat cables and removal\n\nElectric heat cables melt channels through the ice to let water drain, but they use energy, may damage some roofing over time, can be a fire hazard and are disallowed by some insurers. Ice may still form just above the cable. Chipping ice with tools often damages the roof; steam removal by professionals is a common alternative.\n\n## Where they occur\n\nIce dams are common in Canada, the northern United States, Scandinavia, the Alps, northern Japan and other snowy regions, particularly on older homes with poorly sealed attics.","key_facts":[{"label":"Conditions","value":"Sub-freezing air, snow cover, heat reaching roof deck"},{"label":"Typical temperatures","value":"Deck above about -1 °C (30 °F), air below about -6 °C (22 °F)"},{"label":"Main cause","value":"Air leakage and heat loss into the attic"},{"label":"Code measure (US)","value":"Ice barrier membrane at eaves"}],"regions":["North America","Europe","East Asia","Arctic"],"aliases":["ice damming","eave icing","eave ice"],"related":["attic-condensation","snow-load","snow-sliding","roof-ventilation","ice-and-water-shield","gutter-problems","roof-leak-detection"],"sources":[{"title":"Ice dam (roof)","url":"https://en.wikipedia.org/wiki/Ice_dam_(roof)","publisher":"Wikipedia"},{"title":"BSD-102: Understanding Attic Ventilation","url":"https://buildingscience.com/documents/digests/bsd-102-understanding-attic-ventilation","publisher":"Building Science Corporation"},{"title":"Protecting your home from rain and ice","url":"https://extension.umn.edu/caring-your-home/protecting-home-rain-and-ice","publisher":"University of Minnesota Extension"},{"title":"Preventing ice-dams on Minnesota homes","url":"https://conservancy.umn.edu/items/af092c48-2b09-4276-8dbf-bd2dbf4d4330","publisher":"University of Minnesota"},{"title":"Dealing with and preventing ice dams","url":"https://basc.pnnl.gov/library/dealing-and-preventing-ice-dams","publisher":"Building America Solution Center (PNNL)"},{"title":"Roof Snow and Ice Dam Prevention","url":"https://inspectapedia.com/ventilation/Roof-Snow-Ice-Dam-Prevention-Grange.pdf","publisher":"InspectAPedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"icelandic-turf-house","title":"Icelandic Turf House","type":"article","summary":"Traditional Icelandic building of turf blocks over a timber frame on a stone base, with a turf-covered roof; on Iceland's UNESCO Tentative List.","body":"The Icelandic turf house (*torfbær*) is a building type in which walls and roof are made largely of cut turf supported by a wooden frame on a stone foundation. Turf houses were built in Iceland from settlement in the 9th century until the early 20th century, and \"The Turf House Tradition\" is on Iceland's Tentative List for UNESCO World Heritage nomination.\n\n## Construction\n\nA typical turf house starts with a base of flat stones. Above it stands a timber frame, and turf blocks are stacked around the frame to form the walls, often in decorative patterns such as herringbone courses. The roof is also covered with turf, laid over the timber structure.\n\nTimber was scarce. Native birch was the main framing wood, because oak, preferred elsewhere in Scandinavia, did not grow on the island, and driftwood was valuable. On many older houses the only exposed wood on the outside was the doorway, which was often decorated.\n\n## Why turf?\n\nTurf was available almost everywhere and gave far better insulation than thin timber or uninsulated stone, which mattered in Iceland's cold, wet and windy climate. Its drawback is that it needs regular maintenance: walls and roofs settle, absorb water and must be rebuilt every few decades.\n\n## Development\n\nThe early houses followed the Norse longhouse. From the 14th century, longhouses were gradually replaced by clusters of smaller, specialised and interconnected rooms. In the late 18th century the *burstabær* became popular: a row of buildings with timber gable fronts facing the yard and turf behind. It is the form most often pictured today and survived well into the 20th century.\n\nTurf buildings were then replaced by timber houses clad in corrugated iron, and later by reinforced concrete, which better resists earthquakes. A house at Sveinatunga in Borgarfjörður, built in 1895 with cast-in-place concrete walls, is regarded as the first of its kind in Iceland.\n\n## Preservation\n\nIn 2011 Iceland placed twelve turf farmsteads and two turf churches on its UNESCO Tentative List. Restoration projects and training courses in recent decades have helped revive the craft of cutting and laying turf, which the buildings depend on. Eiríksstaðir in West Iceland is one preserved example open to visitors.\n\n## Related traditions\n\nThe Icelandic turf house is closely related to the Norwegian and Faroese *torvtak* roofs, though in Iceland turf formed the walls as well as the roof covering.","key_facts":[{"label":"Period of use","value":"9th to early 20th century"},{"label":"Materials","value":"Turf, stone base, birch and driftwood frame"},{"label":"Later form","value":"Burstabær (gabled row), from late 18th century"},{"label":"Heritage status","value":"UNESCO Tentative List since 2011"}],"regions":["Europe","Arctic"],"aliases":["Torfbær","Turf farmhouse","Burstabær"],"related":["torvtak","roofing-in-iceland","green-roof","corrugated-iron"],"sources":[{"title":"Icelandic turf house","url":"https://en.wikipedia.org/wiki/Icelandic_turf_house","publisher":"Wikipedia"},{"title":"The homes that built Iceland","url":"https://www.west.is/en/moya/news/the-homes-that-built-iceland-1","publisher":"West Iceland"},{"title":"The Turf House Tradition","url":"https://whc.unesco.org/en/tentativelists/5589","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing","country":null},{"slug":"icopal","title":"Icopal","category":"manufacturers","type":"company","summary":"Icopal is a Danish-origin flat-roofing and waterproofing brand bought by Standard Industries in 2016 and merged into BMI Group in 2017.","body":"Icopal is a European roofing and waterproofing business originating in Denmark, specialising in flat and low-slope roof systems. Standard Industries, the US owner of GAF, bought Icopal in January 2016 for about EUR 1 billion. After Standard acquired the pitched-roof group Braas Monier in April 2017, it combined the two companies as BMI Group, and Icopal continues as one of BMI's flat-roofing brands.\n\n## Products\n\nIcopal's main products are bituminous roofing membranes: reinforced sheets of bitumen, often polymer-modified, applied in one or more layers by torching, hot bitumen, cold adhesive or self-adhesion. Bituminous membranes have long been the standard covering for flat roofs in northern Europe, including on housing, schools and commercial buildings. BMI's flat-roof range, in which Icopal is a lead brand, covers:\n\n- Bitumen membranes.\n- Synthetic membranes and liquid-applied waterproofing.\n- Green roofs and blue roofs, which hold vegetation or temporarily store rainwater.\n- Waterproofing for civil engineering structures.\n\n## Place within BMI\n\nBMI organises its business into pitched-roof systems, drawn largely from the former Braas Monier tile operations, and flat-roof systems, in which Icopal sits alongside other bituminous and synthetic membrane brands such as Vedag, Villas, Sealoflex and Wolfin, and, in the low-slope market, Siplast and EverGuard. The pairing of Icopal and Braas Monier in 2017 gave Standard Industries a European roofing presence covering both main roof types, complementing GAF's North American business.\n\n## Significance\n\nThe Icopal purchase preceded the Braas Monier deal by about 15 months and was the first step toward the creation of BMI.","key_facts":[{"label":"Origin","value":"Denmark"},{"label":"Acquired by Standard Industries","value":"January 2016 (about EUR 1 billion)"},{"label":"Current group","value":"BMI Group (since 2017)"},{"label":"Products","value":"Bituminous and synthetic flat-roof membranes"}],"regions":["Europe"],"aliases":["BMI Icopal"],"related":["bmi-group","standard-industries","modified-bitumen-roofing","green-roof","blue-roof"],"company":{"website":"https://www.bmigroup.com","parent":"BMI Group","known_for":["Bituminous roofing membranes","Flat-roof waterproofing"]},"sources":[{"title":"Standard Industries","url":"https://en.wikipedia.org/wiki/Standard_Industries","publisher":"Wikipedia"},{"title":"Braas Monier","url":"https://en.wikipedia.org/wiki/Braas_Monier","publisher":"Wikipedia"},{"title":"BMI Group","url":"https://www.bmigroup.com/","publisher":"BMI Group"}],"country":null},{"slug":"ifugao-house","title":"Ifugao House (Bale)","category":"world-roofing","type":"article","summary":"The bale, the traditional raised one-room house of the Ifugao of northern Luzon, Philippines, with a steep pyramidal thatched roof and rat-guarded posts.","body":"The Ifugao house, called *bale*, is the traditional dwelling of the Ifugao people of the Cordillera mountains in northern Luzon, Philippines. It is a compact one-room house raised high on posts beneath a steep, pyramid-shaped thatched roof, and it is closely associated with the Ifugao rice terraces, a UNESCO World Heritage site.\n\n## Form and structure\n\nThe house stands on posts almost 2 m (about 6.5 ft) high. Near the top of each post is a heavily thickened ledge that stops rats climbing into the house and its stored rice. The living floor is small, usually 5-8 m2 (about 54-86 sq ft), and the walls lean slightly inward toward the top. Front and back doors are the only openings.\n\n## The roof\n\nThe roof is thatched and rises to a point, giving the house its pyramidal silhouette. Because the hearth sits inside, in the right rear corner as seen from the front door, a smoke outlet at the top of the roof vents the fire. The tall, steep thatch sheds the heavy rain of the mountains and dominates the whole building, wrapping down over the small living room.\n\nEthnographic sources from the early 20th century record that the bale had the same shape and construction throughout the Ifugao area, which made it one of the most standardised house types in the Philippines.\n\n## House, granary and landscape\n\nThe Ifugao distinguish the *bale* (house) from the *abong* (hut). Rice granaries, *alang*, follow a related raised, thatched form. In the Mayoyao cluster of the Rice Terraces of the Philippine Cordilleras, the terraces are interspersed with these farmhouses and granaries, and the Bangaan and Batad clusters frame traditional villages. According to UNESCO, the terracing technique is about 2,000 years old.\n\n## Change\n\nThe UNESCO site was placed on the List of World Heritage in Danger in 2001 and removed from it in 2012. Migration away from farming, climate change and social change all strain the system of terraces and villages. Elsewhere in the Philippines, traditional thatch has largely given way to metal sheet; in the 2020 census, only 4.7% of occupied housing units nationally were roofed with cogon, nipa or anahaw.\n\n## Local terms\n\n- *bale* - house\n- *abong* - hut\n- *alang* - granary","key_facts":[{"label":"People","value":"Ifugao, Cordillera, northern Luzon"},{"label":"Roof","value":"Steep pyramidal thatch with smoke outlet at top"},{"label":"Posts","value":"Almost 2 m (6.5 ft) high, with rat-guard ledges"},{"label":"Floor area","value":"About 5-8 m2 (54-86 sq ft)"}],"regions":["Southeast Asia"],"aliases":["bale","Ifugao bale","Ifugao native house"],"related":["roofing-in-the-philippines","bahay-kubo","thatch","palm-thatch","pyramid-roof"],"company":null,"sources":[{"title":"House model (Balbale)","url":"https://philippinestudies.uk/mapping/items/show/14911","publisher":"Philippine Studies at SOAS (Mapping Philippine Material Culture)"},{"title":"Rice Terraces of the Philippine Cordilleras","url":"https://whc.unesco.org/en/list/722/","publisher":"UNESCO World Heritage Centre"},{"title":"Housing units in PH reach 28.5 million in 2020 (PSA census results)","url":"https://realestatenews.ph/national/housing-units-in-ph-reach-285-million-in-2020","publisher":"Real Estate News PH"}],"country":null},{"slug":"ijuk-thatch","title":"Ijuk Thatch","category":"materials","type":"term","summary":"Ijuk is the black fibre of the sugar palm, used in Indonesia as durable thatch and binding cord on Minangkabau, Batak and Balinese roofs.","body":"*Ijuk* is the black, wiry fibre that grows around the leaf bases of the sugar palm (*Arenga pinnata*). In Indonesia it is used as a thatching material and as binding cord, and it gives the traditional roofs of the Minangkabau, Karo Batak and Balinese temples their distinctive dark colour.\n\n## Uses in roofing\n\n- **Thatch:** bundles of fibre are laid in overlapping courses on battens. Ijuk thatch covers the curved *gonjong* roofs of the Minangkabau *rumah gadang* in West Sumatra, where it is laid to follow the upswept gables.\n- **Binding:** in Karo Batak houses of North Sumatra, ijuk fibres both bind the roof structure, without nails or screws, and thatch the roof.\n- **Temple roofs:** in Bali, thatched roofs of black ijuk are paired with gold-coloured pinnacles on shrines and pavilions. Balinese builders also thatch with coconut or rumbia (sago palm) leaves, and use *sirap*, hardwood shingles.\n\n## Properties\n\nIts dark colour and coarse texture distinguish it from straw-coloured grass (*alang-alang*) and leaf thatch.\n\n## Status\n\nKaro Batak roofs bound and thatched with ijuk can rise up to about 15 m (49 ft), showing that the material can cover very large, complex roof forms. The fibre is also used on Balinese pavilions (*bale*), which are thatched structures with or without walls, similar to the Javanese *pendopo*.\n\nIjuk remains in use on heritage houses and temples.\n## Sources and gaps\n\nFigures on how many roofs still use ijuk: published information is limited.","key_facts":[{"label":"Source plant","value":"Sugar palm (Arenga pinnata)"},{"label":"Main regions","value":"Sumatra, Bali"},{"label":"Uses","value":"Thatch and binding without nails"}],"regions":["Southeast Asia"],"aliases":["ijuk","sugar palm fibre thatch","aren fibre"],"related":["palm-thatch","thatch","rumah-gadang","gonjong-roof","batak-toba-house","roofing-in-indonesia"],"company":null,"sources":[{"title":"Batak architecture","url":"https://en.wikipedia.org/wiki/Batak_architecture","publisher":"Wikipedia"},{"title":"Balinese architecture","url":"https://en.wikipedia.org/wiki/Balinese_architecture","publisher":"Wikipedia"},{"title":"Indonesian architecture","url":"https://en.wikipedia.org/wiki/Indonesian_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"iko","title":"IKO","category":"manufacturers","type":"company","summary":"IKO is a family-owned roofing manufacturer founded in Calgary, Canada in 1951, producing asphalt shingles, low-slope membranes and insulation in North America and Europe.","body":"IKO is a privately held roofing manufacturer founded in 1951 in Calgary, Alberta, by Isidore Koschitzky. It remains owned and run by members of the Koschitzky family and operates plants in North America and Europe.\n\n## History\n\nIKO's early products were building paper and coated roll roofing. The company made its first asphalt shingle in 1954. In 1956 a fire destroyed much of the Calgary plant, which was rebuilt and back in operation within about six months. IKO opened a shingle plant in Brampton, Ontario in 1959, and in 1972 built a shingle plant in Ham, Belgium, an early move into Europe for a North American shingle maker. A facility in Hawkesbury, Ontario followed in 1976, and in 1979 the company entered the United States through acquisitions. It has since added plants across North America, including in Hillsboro, Texas.\n\n## Scale\n\nAccording to company material published in 2021, IKO then operated 35 plants in six countries and sold to customers in 94 countries.\n\n## Products\n\nIKO's steep-slope range consists mainly of asphalt shingles, both laminated and three-tab, together with underlayments, starter strips, cap shingles and ice and water protection membranes. The company has also offered metal shingle products under the IKO Metals name. Its commercial range includes modified-bitumen and other low-slope roofing membranes, as well as roof insulation boards. In Europe it supplies bituminous waterproofing and insulation products, where flat and low-slope roofs are common on residential and commercial buildings.\n\n## Ownership\n\nIKO describes itself as family-owned and operated across several generations, and it does not publish public financial statements.","key_facts":[{"label":"Founded","value":"1951, Calgary, Alberta"},{"label":"Founder","value":"Isidore Koschitzky"},{"label":"Ownership","value":"Family-owned (private)"},{"label":"First shingle","value":"1954"}],"regions":["North America","Europe"],"aliases":["IKO Industries","IKO Industries Ltd."],"related":["asphalt-shingle","modified-bitumen-roofing","ice-and-water-shield","polyiso-insulation"],"company":{"founded":"1951","website":"https://www.iko.com","known_for":["Asphalt shingles","Modified bitumen membranes","Roof insulation"]},"sources":[{"title":"Seven things you probably didn't know about IKO","url":"https://www.iko.com/blog/seven-things-you-probably-didnt-know-about-iko/","publisher":"IKO"},{"title":"IKO celebrates 70 years of roofing elevated","url":"https://www.rooferscoffeeshop.com/post/iko-celebrates-70-years-of-roofing-elevated","publisher":"RoofersCoffeeShop"}],"country":null},{"slug":"imbrex-and-tegula","title":"Imbrex and Tegula","type":"term","category":"history","summary":"The ancient Greek and Roman roof tile system of flat tiles (tegulae) with half-round tiles (imbrices) covering the joints.","body":"The imbrex and tegula system is the roof tiling method used across the ancient Greek and Roman world. A **tegula** is a flat tile, usually with raised side edges, laid on the roof slope; an **imbrex** is a half-cylindrical tile laid over the joint between two neighbouring tegulae. Together they form a ribbed, weathertight roof that needed little or no extra sealing when well made.\n\n## Origins\n\nThe Greeks made the first tiles of this kind, pressing wet clay into four-sided moulds and firing it in kilns. Some of the earliest fired roof tiles come from temples near Corinth, dated to around 700-650 BC. Early tegulae were flat or had a single ridge to hang them on the slope; later ones gained raised borders to channel water, and some borders converged towards the lower end so tiles nested together.\n\nMarble tiles came into use around 620 BC and were used on major temples, including the Temple of Zeus at Olympia and the Parthenon. Bronze and gilded tiles were used on a few especially prestigious buildings.\n\n## Roman use\n\nIn Rome, tiles replaced wooden shingles and were used on nearly every type of building. Tiles were made in vast numbers, and those produced by army units were often stamped with the legion's insignia, which helps archaeologists date sites. A 1993 excavation in Merseyside, England, recovered over 300 kg (660 lb) of tile and kiln material, some stamped by Legio XX Valeria Victrix. Broken tiles were commonly crushed and reused in mortar.\n\n## Roof details\n\nDecorated end pieces called antefixes closed the open ends of the imbrices along the eaves. Gutters ran above the cornice, with spouts often carved as lions' heads or grotesque faces.\n\n## Legacy\n\nThe pan-and-cover principle survives in modern two-piece curved tiles such as mission or barrel tiles, and in the German *Mönch und Nonne* (monk and nun) tile. The English word \"imbrication\", meaning an arrangement of overlapping layers, comes from *imbrex*.\n","key_facts":[{"label":"Tegula","value":"Flat tile with raised edges"},{"label":"Imbrex","value":"Half-round cover tile over joints"},{"label":"Earliest examples","value":"c. 700-650 BC, near Corinth"},{"label":"Marble tiles","value":"From about 620 BC"}],"regions":["Europe","Middle East","Africa"],"aliases":["tegula and imbrex","Roman tiles","Greek tiles","tegulae and imbrices","Roman roof tiles","tegulae","imbrices"],"related":["clay-roof-tile","mission-tile","pantile","ancient-greek-roof-tiles","antefix","earliest-fired-clay-roof-tiles","spanish-tile"],"sources":[{"title":"Imbrex and tegula","url":"https://en.wikipedia.org/wiki/Imbrex_and_tegula","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Research Spotlight: Roof Tile Manufacturing Techniques","url":"https://www.ascsa.edu.gr/news/newsDetails/sapirstein-dissertation","publisher":"American School of Classical Studies at Athens"}],"company":null,"country":null},{"slug":"impact-resistance-rating","title":"Impact Resistance Rating (UL 2218 and FM 4473)","type":"standard","summary":"Laboratory classifications (Class 1 to Class 4) that rank roof coverings by resistance to simulated hail impacts.","body":"Impact resistance ratings are laboratory classifications that indicate how well a roof covering resists damage from simulated hail. In North America, the two most widely cited methods are UL 2218 and FM 4473. Both rank products from Class 1 (lowest) to Class 4 (highest), and Class 4 products may qualify for insurance premium discounts in some US states.\n\n## UL 2218\n\nUL 2218, Standard for Impact Resistance of Prepared Roof Covering Materials, covers asphalt, wood, tile, fiber-cement, plastic and metal shingles and panels. A 0.9 by 0.9 m (3 by 3 ft) specimen of new product is struck twice in the same spot at several vulnerable locations by steel balls dropped from set heights:\n\n- Class 1: 32 mm (1.25 in) ball\n- Class 2: 38 mm (1.5 in) ball dropped about 4.6 m (15 ft)\n- Class 3: 44 mm (1.75 in) ball dropped about 5.2 m (17 ft)\n- Class 4: 51 mm (2 in) ball dropped about 6.1 m (20 ft)\n\nA product passes a class if there is no tearing, cracking, splitting, rupture or opening on the exposed surface, back surface or underlying layers. Cosmetic marks alone do not count as failure.\n\n## FM 4473\n\nFM 4473 is used for rigid materials such as clay and concrete tile and slate. Instead of steel balls, it fires pre-molded ice balls of 32 to 51 mm (1.25 to 2 in) at the specimen. A pass requires no visible cracking or breaking.\n\n## Criticisms and newer methods\n\nExperts have noted several limits. Tests use new, unweathered products, but hail usually strikes aged roofs; outdoor exposure reduces the impact resistance of many materials. UL 2218 is run at room temperature, while real hail often falls during sudden cooling. Steel balls do not behave like natural hailstones, and pass/fail classes give little way to compare products, since many shingles carry the same rating.\n\nThe Insurance Institute for Business & Home Safety (IBHS) developed an alternative protocol for asphalt shingles, published in 2021, that uses manufactured ice spheres matched to field-measured hail strength and scores damage modes such as dents and granule loss on a continuous scale. IBHS publishes shingle ratings from this testing, and the FORTIFIED Roof hail supplement accepts shingles rated Good or Excellent by IBHS.\n\n## Terminology\n\nBecause ratings are tied to specific test methods, technical writers recommend citing the method and class (for example, \"UL 2218 Class 4\") rather than describing a product as hail-proof.","key_facts":[{"label":"Classes","value":"1 (lowest) to 4 (highest)"},{"label":"UL 2218 Class 4","value":"51 mm (2 in) steel ball from about 6.1 m (20 ft)"},{"label":"FM 4473 projectile","value":"Ice balls 32-51 mm (1.25-2 in)"},{"label":"Main limitation","value":"Tests new, unweathered products"}],"regions":["North America"],"aliases":["UL 2218","FM 4473","Class 4 impact resistance","hail rating","impact-resistant shingles"],"related":["hail-damage","fortified-roof","roof-insurance-discounts","asphalt-shingle"],"sources":[{"title":"Tech Today: impact resistance test methods","url":"https://www.professionalroofing.net/articles/article/1363","publisher":"Professional Roofing (NRCA)"},{"title":"Roof Hail Impact Resistance","url":"https://roofobservations.com/roof-hail-impact-resistance/","publisher":"Roof Observations"},{"title":"Hail Impact Resistance Test Protocol for Asphalt Shingles (Natural Hazards Review, 2021)","url":"https://ascelibrary.com/doi/10.1061/%28ASCE%29NH.1527-6996.0000509","publisher":"ASCE Library"},{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/?p=2512","publisher":"Insurance Institute for Business & Home Safety (FORTIFIED Home)"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"impact-resistant-roof-insurance-discounts","title":"Impact-Resistant Roof Insurance Discounts","category":"standards-codes","type":"article","summary":"Some insurers and states give premium credits for roofs that carry a recognised hail impact rating, most often UL 2218 Class 4.","body":"In hail-prone parts of North America, many home insurers reduce premiums for roofs that have passed a recognised impact test. The rating most often required is [UL 2218](/ul-2218) Class 4, though some programs also credit lower classes or accept [FM 4473](/fm-4473) for tile. The aim is to reduce claims: hail is one of the largest causes of insured roof losses in the central United States.\n\n## How programs work\n\nDiscounts are usually set by each insurer within rules approved by the state regulator. Texas is a well-documented example. The Texas Department of Insurance explains that the Texas Windstorm Insurance Association (TWIA) gives credits for roofs rated Class 1 to 4 under UL 2218, with Class 4 receiving the largest credit. To qualify, the product must be labelled with the testing laboratory's mark, impact class, manufacturer, brand and year of manufacture, and the contractor must fill out TDI form PC068 after installation. Other insurers set their own criteria and discount amounts.\n\nOther states and insurers run their own hail or wind mitigation credits. Programs change often, so details should be checked with the state insurance department or the insurer.\n\n## What owners usually need\n\n- product documentation showing the impact class and test standard\n- labels or packaging marks on the installed material\n- a contractor's certificate or state form confirming the installation\n- sometimes photos or an inspection\n\n## Things to know\n\n- **Discount size varies.** There is no standard percentage. It depends on the insurer, state, deductible and policy type.\n- **Cosmetic damage exclusions.** Some insurers that credit Class 4 roofs also add exclusions for cosmetic hail damage, especially for metal roofs, so a dented but watertight roof may not be covered.\n- **Ratings are not identical.** A Class 4 rating under UL 2218 is not the same as a good result in the IBHS shingle hail ratings, and insurers may prefer one or the other.\n- **Wind credits are separate.** In hurricane states, discounts often relate to wind mitigation features (roof-to-wall connections, roof deck attachment, secondary water barriers) rather than hail, and may be linked to [FORTIFIED](/ibhs-fortified-roof) designation.\n\n## Outside the US\n\nImpact-resistance credits are mainly a US practice. Insurers in other hail-prone regions, including parts of Canada and central Europe, use their own approaches, and owners should ask their insurer which ratings, if any, are recognised.","key_facts":[{"label":"Most common rating required","value":"UL 2218 Class 4"},{"label":"Texas form","value":"TDI PC068 Impact-Resistant Roofing Installation Form"},{"label":"Discount amount","value":"Set by each insurer"},{"label":"Common caveat","value":"Cosmetic damage exclusions"}],"regions":["North America"],"aliases":["Class 4 roof discount","hail roof discount","impact-resistant roofing credit"],"related":["ul-2218","fm-4473","ibhs-fortified-roof","hail-damage","roof-insurance-claims"],"sources":[{"title":"Roofing discounts","url":"https://tdi.texas.gov/company/roofing-discounts.html","publisher":"Texas Department of Insurance"},{"title":"Insurance industry presses for impact-resistant roofing","url":"https://www.jlconline.com/products-tools/exteriors-roofing/insurance-industry-presses-for-impact-resistant-roofing/","publisher":"JLC Online"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"}],"company":null,"country":null},{"slug":"impact-resistant-shingle","title":"Impact-Resistant Shingle","type":"term","summary":"A roofing product rated for hail resistance, most often to UL 2218 Class 4, the highest class, tested with a 2 in (51 mm) steel ball.","body":"An impact-resistant shingle is a roofing product, usually an asphalt shingle, that has been tested and classified for resistance to hail. In North America the most common rating is from UL 2218, a standard established in 1996 that ranks products from Class 1 to Class 4. A \"Class 4 shingle\" is one that has achieved the highest class.\n\n## The UL 2218 test\n\nSteel balls of increasing size are dropped onto installed samples, simulating hailstones. For Class 4, a 2 in (51 mm) steel ball is dropped twice on the same spot from about 20 ft (6.1 m). The product passes if there are no ruptures or cracks through the shingle when examined immediately afterwards. Classes 1-3 use smaller balls.\n\n## How shingles achieve it\n\nManufacturers use one or more of these methods:\n\n- **Polymer-modified asphalt** (often SBS rubber), which makes the shingle more flexible so it absorbs energy instead of cracking.\n- **Reinforcing scrim or fabric** on the back of the shingle.\n- **Thicker laminated construction**.\n\nOther materials can also carry Class 4 ratings, including many synthetic slates and shakes, some metal panels and some concrete tiles.\n\n## Insurance and codes\n\nTexas required insurers to offer premium discounts for Class 4 roofs as early as 1998, and several other US states and insurers offer discounts or credits; availability varies widely. Studies from the 1960s found that hail damage to shingles typically starts with stones larger than about 1.5 in (38 mm).\n\n## Limitations\n\nThe rating describes resistance on a new product under laboratory conditions. Shingles age, and stiffened asphalt is more vulnerable. A Class 4 label does not mean the roof cannot be damaged by very large hail, and cosmetic dents or granule loss may not be covered by a manufacturer's warranty.\n","key_facts":[{"label":"Main standard","value":"UL 2218 (Classes 1-4), established 1996"},{"label":"Class 4 test","value":"2 in (51 mm) steel ball, dropped twice from about 20 ft (6.1 m)"},{"label":"Common methods","value":"SBS-modified asphalt, reinforcing scrim"}],"regions":["North America"],"aliases":["Class 4 shingle","hail-resistant shingle","IR shingle","UL 2218 shingle"],"related":["asphalt-shingle","ul-2218","hail-damage","synthetic-slate","designer-shingle"],"sources":[{"title":"What you need to know about impact resistant shingles","url":"https://www.gaf.com/en-us/blog/your-home/what-you-need-to-know-about-impact-resistant-shingles-281474980211483","publisher":"GAF"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Asphalt Shingle Types (3-Tab vs. Laminated Architectural), ASTM Classifications & Thermal Behavior","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-types-astm-thermal","publisher":"Open Exam Prep"}],"category":"materials","company":null,"country":null},{"slug":"induction-welding-roofing","title":"Induction Welding (Roofing)","category":"low-slope-systems","type":"term","summary":"Attaching single-ply membrane by bonding it to coated plates fastened to the deck, using an induction heating tool, so the sheet is not pierced.","body":"Induction welding is a mechanical attachment method for single-ply roofing in which the fasteners go under the membrane rather than through it. Steel plates coated with a heat-activated bonding material are screwed through the insulation into the deck in a grid. The membrane is then rolled out over them, and a hand-held or walk-behind induction tool is placed over each plate.\n\n## How it works\n\nInduction heating uses a coil carrying high-frequency alternating current to create a rapidly changing magnetic field. A metal object in that field heats up from eddy currents and, in magnetic metals, hysteresis. Because plastics do not respond to the field directly, the metal plate acts as the heat source: it warms its coating and the underside of the membrane until they fuse.\n\n## Advantages\n\n- the membrane is not punctured by fasteners in the field of the roof\n- fastener patterns can be spread across the sheet rather than concentrated in seams\n- wind loads are spread across many bonded points\n- it avoids the large quantities of adhesive needed for full adhesion\n\n## Use\n\nInduction-welded systems are used mainly with thermoplastic membranes such as TPO and PVC. Plate density is set by wind-uplift design, with more plates at perimeters and corners. Systems are tested and listed as assemblies by bodies such as FM Approvals and UL in North America.\n\n## Limitations\n\nCorrect heating is essential; under- or overheating weakens the bond. The method also depends on accurate plate layout so the installer can locate each plate under the sheet.","key_facts":[{"label":"Principle","value":"Electromagnetic induction heats coated metal plates"},{"label":"Membrane penetrations","value":"None in the field of the sheet"},{"label":"Typical membranes","value":"TPO, PVC; some EPDM"},{"label":"Design basis","value":"Wind-uplift rated plate patterns"}],"regions":["North America","Europe"],"aliases":["induction-welded attachment","RhinoBond-type systems","plate bonding"],"related":["mechanically-attached-roof-system","tpo-roofing","pvc-roofing","single-ply-roofing"],"company":null,"sources":[{"title":"Induction welding","url":"https://en.wikipedia.org/wiki/Induction_welding","publisher":"Wikipedia"},{"title":"Thermoplastic Polyolefin (TPO) Roofing Systems","url":"https://buildings.com/articles/35297/thermoplastic-polyolefin-tpo-roofing-systems","publisher":"Buildings"},{"title":"SPRI - Single Ply Roofing Industry","url":"https://www.spri.org/","publisher":"SPRI"}],"country":null},{"slug":"infrared-roof-thermography","title":"Infrared Roof Thermography","category":"tools-equipment","type":"term","summary":"Thermal imaging of a roof, usually after sunset, to find areas where wet insulation holds heat differently from dry areas.","body":"Infrared roof thermography uses a thermal imaging camera to detect differences in surface temperature on a roof. Wet insulation and substrates have greater thermal mass than dry ones, so after a sunny day they stay warmer longer into the evening and show up as warm patches. ASTM C1153 is the standard practice in North America for locating wet insulation in roofing systems by infrared imaging.\n\n## How surveys are done\n\n- **Timing**: scans are typically made in the evening or at night after a clear, sunny day that has warmed the roof, with the roof surface dry.\n- **Weather**: low wind, no rain and no standing water or dew on the surface; heavy cloud cover overnight can reduce contrast.\n- **Platforms**: handheld cameras on the roof, or images taken from aircraft or drones over large areas.\n- **Marking**: anomalies are outlined on the roof surface with paint or recorded on a roof plan.\n- **Verification**: suspect areas are confirmed with core cuts or other moisture tests.\n\n## Where it works best\n\nInfrared surveys are most effective on low-slope roofs with absorbent insulation, such as perlite, fibreboard and fibreglass, directly under the membrane. They are less reliable on roofs with heavy ballast or pavers, roofs with reflective surfaces that make readings harder to interpret, very thick or closed-cell insulation that absorbs little water, and roofs where the heat source is mainly from inside the building.\n\n## Limits\n\nAn infrared camera does not see water. It sees surface temperature differences, which can also come from variations in surfacing, extra layers of membrane, patches, flashings, rooftop equipment, reflections and differing insulation thicknesses. Professional guidance stresses that thermographers should be trained and that all anomalies need confirmation. A survey that skips verification can lead to unnecessary removal of dry material, or miss wet areas.\n\n## Other uses\n\nThermal imaging also helps find air leaks, missing insulation and heat loss in attics and buildings, and some fire safety practices propose thermal cameras for checking for hidden hot spots after torch-applied roofing.","key_facts":[{"label":"Standard (North America)","value":"ASTM C1153"},{"label":"Typical timing","value":"Evening after a sunny day, dry roof"},{"label":"Must be verified by","value":"Core cuts or other moisture tests"}],"regions":["Global"],"aliases":["infrared roof scan","IR roof survey","thermal imaging roof"],"related":["roof-moisture-survey","moisture-meter","drone-roof-inspection","electronic-leak-detection","roofing-torch"],"company":null,"sources":[{"title":"Surveying roof moisture","url":"https://professionalroofing.net/articles/article/5681","publisher":"Professional Roofing"},{"title":"Infrared roof moisture survey","url":"https://atslab.com/engineering/commercial-properties/infrared-roof-moisture-survey/","publisher":"ATS"},{"title":"ASTM C1153-23 sample","url":"https://cdn.standards.iteh.ai/samples/116377/f2c792c09e3c48379f45e417e473ff4c/ASTM-C1153-23.pdf","publisher":"ASTM International via iTeh"},{"title":"A reminder to cut the roof","url":"https://irinfo.org/tip-of-week-alphabeta/a-reminder-to-cut-the-roof","publisher":"Infrared Training Center"}],"country":null},{"slug":"metal-roof-over-existing-shingles","title":"Installing a Metal Roof Over Existing Shingles","category":"installation","type":"article","summary":"Because metal is light, it can often be installed over one existing roof layer where local codes allow, but deck condition, ventilation and fixing must be checked.","body":"Re-covering, sometimes called a roof-over or overlay, means installing new metal roofing on top of an existing asphalt shingle roof instead of tearing it off. Metal is light, roughly half the weight of asphalt shingles by one industry estimate, so it is often possible to add it without overloading the structure. Industry associations note that metal can often be installed over an existing roof, subject to local rules.\n\n## Code and permit considerations\n\nBuilding codes in many jurisdictions limit how many roof coverings may be stacked and expect the existing roof and deck to be sound. Requirements vary by country, state, province and city, so the local building department or code should always be checked before planning a roof-over.\n\n## Technical checks\n\n- **Deck condition**: soft, rotten or delaminated decking must be repaired; fasteners must reach sound wood.\n- **Flatness**: curled or uneven shingles can telegraph through flat panels and increase oil canning. Some installers add battens or a new underlayment layer to create a flat plane.\n- **Underlayment and separation**: a new underlayment or slip sheet is usually installed; manufacturers specify compatible products.\n- **Ventilation and condensation**: trapping moisture between layers must be avoided; ridge and eave ventilation details may need upgrading.\n- **Flashings**: new flashings at walls, chimneys and penetrations are normally required rather than reusing old ones.\n- **Fire and wind ratings**: ratings apply to tested assemblies, which may or may not include a recover layer.\n\n## Pros and cons\n\nA roof-over saves tear-off labour and disposal and keeps the house covered during work. Disadvantages include hiding deck problems, limits on future re-covering, and the extra care needed to keep panels flat.","key_facts":[{"label":"Main enabler","value":"Light weight of metal"},{"label":"Key requirement","value":"Sound, dry existing roof and deck"},{"label":"Governing rules","value":"Local building code layer limits"}],"regions":["North America","Global"],"aliases":["metal roof over shingles","roof-over","re-cover","overlay roofing"],"related":["metal-roofing","metal-shingles","oil-canning","ventilation-under-metal-roofs"],"company":null,"sources":[{"title":"FAQs","url":"https://www.metalroofing.com/faqs","publisher":"Metal Roofing Alliance"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Can You Install a Metal Roof Over Existing Shingles?","url":"https://www.interlockroofing.com/kb/metal-roof-over-shingles/","publisher":"Interlock Roofing"},{"title":"How Is a Standing Seam Metal Roof Installed? (Step by Step)","url":"https://www.interlockroofing.com/kb/how-is-a-standing-seam-metal-roof-installed/","publisher":"Interlock Roofing"}],"country":null},{"slug":"institute-of-roofing","title":"Institute of Roofing (IoR)","summary":"The Institute of Roofing was a UK professional body for people in the roofing industry; it has ceased operations and is being dissolved.","body":"The Institute of Roofing (IoR) was a professional membership body for individuals working in the roofing industry in the United Kingdom. Unlike trade associations, which represent companies, the institute was aimed at individual professionals such as contractors' managers, estimators, surveyors, technical staff and manufacturers' representatives.\n\n## Current status\n\nAccording to its website, the Institute of Roofing has ceased operations and is in the process of being dissolved. The website directs people seeking continuing professional development (CPD) to the Chartered Institute of Building (CIOB), a broader professional body for the construction industry.\n\n## Background\n\nProfessional institutes in construction usually offer graded membership based on qualifications and experience, a code of conduct, technical events and CPD programmes. In roofing, these functions overlap with the work of trade associations. In the UK, the National Federation of Roofing Contractors (NFRC), the Liquid Roofing and Waterproofing Association, the Single Ply Roofing Association and other bodies provide technical guidance and training, while the Construction Industry Training Board (CITB) funds training across the sector.\n\n## Where roofing professionals turn now\n\nPeople who were members or who seek similar recognition may look to:\n\n- the **Chartered Institute of Building (CIOB)** for professional membership and CPD in construction management;\n- **specialist trade associations** for technical training and product-specific courses;\n- **qualifications** such as NVQs and Specialist Applied-skills Programmes delivered through approved training organisations;\n- in North America, the **International Institute of Building Enclosure Consultants (IIBEC)**, which offers individual credentials for roof consultants and observers.","key_facts":[{"label":"Country","value":"United Kingdom"},{"label":"Type","value":"Individual professional membership body"},{"label":"Status","value":"Ceased operations; being dissolved"},{"label":"CPD referral","value":"Chartered Institute of Building"}],"regions":["Europe"],"aliases":["IoR"],"related":["national-federation-of-roofing-contractors","citb","iibec"],"company":{"website":"https://www.instituteofroofing.org","known_for":["Former UK professional body for roofing"]},"sources":[{"title":"Institute of Roofing","url":"https://www.instituteofroofing.org/","publisher":"Institute of Roofing"},{"title":"About CITB","url":"https://www.citb.co.uk/about-citb/","publisher":"CITB"}],"category":"organizations","type":"organization","country":null},{"slug":"ibhs","title":"Insurance Institute for Business & Home Safety (IBHS)","summary":"IBHS is a U.S. research body funded by property insurers, formed in 1977, that tests roofs against wind, hail and fire and runs the FORTIFIED program.","body":"The Insurance Institute for Business & Home Safety (IBHS) is a non-profit scientific research and communications organisation supported by the property-casualty insurance industry in the United States. It was formed in 1977 under the name National Committee on Property Insurance. Its website is ibhs.org.\n\n## Research Center\n\nIn 2010 IBHS opened its Research Center in Chester County, South Carolina. The facility contains a large test chamber where full-scale buildings can be exposed to simulated hurricane-force winds, wind-driven rain, hail and wildfire embers. Much of the research focuses on roofs, because roof damage is one of the main causes of insured losses in severe weather.\n\nTypical research areas include:\n\n- **Wind.** How roof coverings, roof edges and roof deck attachment fail in high winds, and how sealing the roof deck reduces water entry if the covering is lost.\n- **Hail.** Hail impact resistance of shingles, metal, tile and other materials, including the development of tests that use realistic ice hailstones.\n- **Wildfire.** How embers ignite roof coverings, gutters and vents.\n\n## FORTIFIED program\n\nIBHS runs FORTIFIED, a voluntary construction and re-roofing standard for homes and commercial buildings in high-wind and hail-prone areas. It has three levels: FORTIFIED Roof, FORTIFIED Silver and FORTIFIED Gold. Requirements for the Roof level include:\n\n- a wider drip edge and a fully adhered starter strip at the roof edges;\n- a sealed roof deck, so that water cannot enter through deck joints if the roof covering is torn off;\n- ring-shank nails in an enhanced nailing pattern for the deck;\n- roof coverings tested and rated for wind; for asphalt shingles, ASTM D3161 Class F or ASTM D7158 Class H.\n\nThird-party evaluators verify the work and the home receives a designation. Some U.S. states and insurers offer incentives or premium discounts for FORTIFIED homes.\n\n## Context\n\nIBHS research is used by building code bodies, insurers and manufacturers. Its findings complement work by other research bodies such as FM (formerly FM Global) for commercial property, and national building research institutes in other countries.","key_facts":[{"label":"Formed","value":"1977 (as National Committee on Property Insurance)"},{"label":"Research Center","value":"Chester County, South Carolina; opened 2010"},{"label":"Funding","value":"Property-casualty insurers"},{"label":"Program","value":"FORTIFIED Roof, Silver, Gold"}],"regions":["North America"],"aliases":["IBHS","Insurance Institute for Business and Home Safety","FORTIFIED"],"related":["fortified-roof","fm-global","hail-damage","wind-uplift","sealed-roof-deck"],"company":{"founded":"1977","website":"https://ibhs.org","known_for":["Full-scale wind, hail and wildfire testing","FORTIFIED program"]},"sources":[{"title":"About IBHS","url":"https://www.ibhs.org/about-ibhs/","publisher":"IBHS"},{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/roof/","publisher":"IBHS FORTIFIED"},{"title":"RICOWI sponsor members","url":"https://www.ricowi.com/","publisher":"RICOWI"}],"category":"organizations","type":"organization","country":null},{"slug":"interlocking-clay-tile","title":"Interlocking Clay Tile","type":"term","summary":"A pressed clay roof tile with grooves on its sides and head that lock into neighbouring tiles; the French or Marseille tile is the classic form.","body":"An interlocking clay tile is a fired clay roof tile with raised ribs and channels along its edges that hook into matching grooves on the adjoining tiles. The interlocks guide water away from the joints, allow a single-lap layout, and reduce the number of tiles needed compared with plain or two-piece curved tiling.\n\n## Origins\n\nInterlocking clay tiles date to the 1840s. The Gilardoni brothers of Altkirch, in Alsace, France, began making them in 1835 and patented their first design in 1841. In English the type is often called the \"French tile\" or \"Marseille tile\". In Germany, Wilhelm Ludowici developed his own influential interlocking design in 1881. Large-scale production of interlocking tiles required the mechanical tile press, which shaped damp clay between steel dies.\n\n## Global spread\n\nIn India, the Basel Mission tile works at Mangalore, founded in the 1860s, first followed the Gilardoni design and later the Ludowici pattern. \"Mangalore tiles\" became standard across the west coast of India and were exported throughout the Indian Ocean region.\n\n## Features\n\n- **Single-lap** coverage, giving a lighter roof than double-lap plain tiling.\n- **Side and head interlocks** that resist wind-driven rain.\n- **Nibs** on the underside for hanging on battens, and often nail or clip holes for mechanical fixing.\n- Profiles range from nearly flat with shallow ribs to deeply curved interlocking pantiles.\n\n## Concrete versions\n\nConcrete tile manufacturers adopted the same interlocking principle, and many concrete tiles reproduce clay interlocking profiles.\n\n## Named patterns\n\nBesides the generic French or Marseille tile, designs such as the Ludowici and Conosera tiles are listed among the main interlocking types. All rely on precise pressing so that the ribs and grooves of neighbouring tiles fit closely.\n","key_facts":[{"label":"First patent","value":"1841, Gilardoni brothers, Altkirch, France"},{"label":"Other key design","value":"Ludowici tile, Germany, 1881"},{"label":"Lap","value":"Single lap"}],"regions":["Europe","Global","South Asia","Latin America","Oceania"],"aliases":["French tile","Marseille tile","Marseilles tile","tuile mécanique"],"related":["clay-roof-tile","mangalore-tile","pantile","concrete-roof-tile"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Mangalore tiles","url":"https://en.wikipedia.org/wiki/Mangalore_tiles","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"international-building-code","title":"International Building Code (IBC) Chapter 15","summary":"The International Building Code is the main US model building code; its Chapter 15 sets rules for roof assemblies and rooftop structures.","body":"The **International Building Code (IBC)** is a model building code published by the International Code Council (ICC), a US non-profit formed in 1994 by merging three regional code bodies (BOCA, ICBO and SBCCI). The first IBC was published in 2000, and new editions follow every three years (2003, 2006 ... 2021, 2024). Most US states and many local governments adopt it, often with amendments. It is also used or adapted in some other countries and territories.\n\nThe IBC covers all buildings except detached one- and two-family dwellings and small townhouses, which fall under the [International Residential Code](/international-residential-code).\n\n## Chapter 15: Roof Assemblies and Rooftop Structures\n\nRoofing rules sit mainly in Chapter 15. In the 2024 edition its sections include general provisions, roof drainage, weather protection (flashing, coping, crickets), performance requirements, fire classification, materials, requirements for each type of roof covering, insulation, reroofing and rooftop structures.\n\nKey topics include:\n\n- **Performance requirements (Section 1504).** Roof coverings must resist wind. Membrane roofs must be tested to [UL 580](/ul-580), [UL 1897](/ul-1897) or [FM 4474](/fm-4474); metal panel roofs to UL 580 or equivalent. Asphalt shingles must be wind-classified under [ASTM D7158](/astm-d7158) or [ASTM D3161](/astm-d3161).\n- **Fire classification.** Roofs are classified Class A, B or C under [ASTM E108 or UL 790](/astm-e108-ul-790), with the required class depending on construction type and location.\n- **Roof coverings.** Separate requirements apply to asphalt shingles, clay and concrete tile, metal panels and shingles, slate, wood shingles and shakes, built-up, modified bitumen, single-ply membranes, sprayed foam, liquid-applied coatings and photovoltaic systems. These specify minimum slopes, underlayment, fastening and referenced product standards such as [ASTM D3462](/astm-d3462).\n- **Reroofing.** Rules on when an existing roof must be removed, how many layers are allowed, and when recovering is permitted.\n\n## Related chapters\n\nStructural loads on roofs (dead, live, snow, wind, rain) are in Chapter 16, which references ASCE 7. Energy requirements for roof insulation come from the International Energy Conservation Code or [ASHRAE 90.1](/ashrae-90-1). Some states, notably Florida, publish their own code based on the IBC with additional hurricane provisions.\n\n## Using the code\n\nBecause the IBC is a model code, the edition and amendments in force vary by jurisdiction. Roofers and designers must check which edition the local authority has adopted.","key_facts":[{"label":"Publisher","value":"International Code Council (ICC)"},{"label":"First edition","value":"2000"},{"label":"Update cycle","value":"Every 3 years"},{"label":"Roofing chapter","value":"Chapter 15, Roof Assemblies and Rooftop Structures"},{"label":"Excludes","value":"One- and two-family dwellings (see IRC)"}],"regions":["North America"],"aliases":["IBC","IBC Chapter 15","International Building Code roofing"],"related":["international-residential-code","ul-580","astm-e108-ul-790","ashrae-90-1"],"sources":[{"title":"International Building Code","url":"https://en.wikipedia.org/wiki/International_Building_Code","publisher":"Wikipedia"},{"title":"2024 IBC Chapter 15 Roof Assemblies and Rooftop Structures","url":"https://codes.iccsafe.org/content/IBC2024V1.0/chapter-15-roof-assemblies-and-rooftop-structures","publisher":"International Code Council"},{"title":"An uplifting experience","url":"https://code-authorities.ul.com/about/blog/certifying-roof-deck-constructions-for-wind-resistance/","publisher":"UL Solutions"},{"title":"Understanding asphalt shingle standards","url":"https://www.professionalroofing.net/articles/article/4817","publisher":"Professional Roofing (NRCA)"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"international-federation-for-the-roofing-trade","title":"International Federation for the Roofing Trade (IFD)","summary":"The IFD is an international federation of national roofing contractor associations, founded in 1952 and based in Germany.","body":"The International Federation for the Roofing Trade, known by its German initials IFD (Internationale Föderation des Dachdeckerhandwerks), is an umbrella body that links national roofing trade associations across many countries. It was founded in 1952 and is registered in Germany, where its office is located in the town of Rees in North Rhine-Westphalia.\n\nUnlike a national association, the IFD does not usually sign up individual roofing firms as its core members. Its members are mainly the national federations of roofers and roofing contractors, along with associated partners such as manufacturers and trade media. It acts as a meeting point where roofing organisations from Europe, North America, Asia and elsewhere compare practices, training systems and technical rules.\n\n## Activities\n\n- **Annual Congress.** The IFD holds a congress each year in a different host country. The 73rd congress took place in Bratislava, Slovakia, in October 2025.\n- **Young roofer competition.** The federation runs an international competition for young roofers, often called the World Championship of Young Roofers. Teams compete in flat (low-slope) roofing, pitched roofing and metal roofing disciplines. A competition in Budapest, Hungary, is planned for 2027.\n- **Working groups.** Members meet in working groups on technical subjects and on training, and the federation supports the development of technical standards and shared guidance.\n- **Awards.** The IFD presents awards recognising outstanding roofing projects submitted by member countries.\n\n## Why it matters\n\nRoofing traditions differ widely from country to country. Slate and tile details used in central Europe, single-ply membranes common in North America and metal roofing systems used in Scandinavia all depend on local climate, codes and training. The IFD gives these traditions a forum where contractors can see how other countries train apprentices, organise safety, and approach new issues such as rooftop solar and green roofs. For a homeowner, the IFD itself is not a licensing or certification body; local national associations remain the main point of contact.","key_facts":[{"label":"Founded","value":"1952"},{"label":"Seat","value":"Germany (office in Rees)"},{"label":"Members","value":"National roofing trade associations and partner companies"},{"label":"Known for","value":"Annual congress; young roofer world competition"}],"regions":["Global","Europe"],"aliases":["IFD","Internationale Föderation des Dachdeckerhandwerks","International Federation of the Roofing Trade"],"related":["zvdh","nrca","roofing-apprenticeship"],"company":{"founded":"1952","headquarters":"Rees, Germany","website":"https://www.ifd-roof.com","known_for":["International roofing congress","World Championship of Young Roofers"]},"sources":[{"title":"International Federation of the Roofing Trade directory listing","url":"https://www.rooferscoffeeshop.com/directory/international-federation-of-the-roofing-trade","publisher":"RoofersCoffeeShop"},{"title":"IFD Congress Award 2025 in Bratislava","url":"https://www.rooferscoffeeshop.com/post/ifd-congress-award-2025-in-bratislava-new-president-global-recognition-and-strong-signals-of-cooperation","publisher":"RoofersCoffeeShop"},{"title":"International roofing community gathers for IFD Congress 2019","url":"https://roofingtoday.co.uk/international-roofing-community-gathers-for-ifd-congress-2019","publisher":"Roofing Today"}],"category":"organizations","type":"organization","country":null},{"slug":"iibec","title":"International Institute of Building Enclosure Consultants (IIBEC)","summary":"IIBEC is a professional body for roof, waterproofing and building enclosure consultants, founded in 1983 as RCI and renamed in 2019.","body":"The International Institute of Building Enclosure Consultants (IIBEC) is a non-profit professional association for consultants, architects, engineers and others who design, inspect and assess roofs, waterproofing and exterior walls. It was incorporated in 1983 as the Roof Consultants Institute (RCI), later known as RCI, Inc. On 1 April 2019 it adopted its current name to reflect a wider focus on the whole building enclosure. Its headquarters is in Raleigh, North Carolina.\n\n## Credentials\n\nIIBEC runs a set of professional registrations and certifications. Each requires experience and passing an exam:\n\n- **RRC** – Registered Roof Consultant\n- **RRO** – Registered Roof Observer (for field observation of roof work)\n- **RWC** – Registered Waterproofing Consultant\n- **REWC** – Registered Exterior Wall Consultant\n- **CBECxP** – Certified Building Enclosure Commissioning Provider\n\nBuilding owners, especially for large commercial and institutional projects, often hire consultants with these credentials to write roof specifications, review contractor submittals and observe installation.\n\n## Activities\n\n- **Publications.** IIBEC publishes the *IIBEC Interface* journal with technical articles on roofing and enclosure topics.\n- **Education.** It holds an international convention and trade show, symposia, and courses.\n- **Chapters.** It has regional chapters in the United States, Canada and other countries.\n- **Advocacy.** It comments on codes and standards affecting building enclosures.\n\n## Role in the roofing process\n\nOn many commercial projects, the roofing consultant sits between the owner, the designer and the contractor. They may survey existing roofs, carry out moisture scans or core cuts, prepare repair or replacement designs, and inspect the work in progress. Consultants are usually independent of manufacturers and contractors, though practices differ by country. Similar consultant roles exist in Europe and Australia under different professional titles.","key_facts":[{"label":"Founded","value":"1983 (as Roof Consultants Institute)"},{"label":"Renamed","value":"1 April 2019"},{"label":"Headquarters","value":"Raleigh, North Carolina, USA"},{"label":"Credentials","value":"RRC, RRO, RWC, REWC, CBECxP"}],"regions":["North America","Global"],"aliases":["IIBEC","RCI","RCI, Inc.","Roof Consultants Institute"],"related":["nrca","spri"],"company":{"founded":"1983","headquarters":"Raleigh, North Carolina, USA","website":"https://iibec.org","known_for":["Registered Roof Consultant (RRC) credential","IIBEC Interface journal"]},"sources":[{"title":"RCI becomes IIBEC","url":"https://iibec.org/rci-becomes-iibec/","publisher":"IIBEC"},{"title":"RCI Inc. is now the International Institute of Building Enclosure Consultants (IIBEC)","url":"https://roofingmagazine.com/rci-inc-is-now-the-international-institute-of-building-enclosure-consultants-iibec/","publisher":"Roofing Magazine"},{"title":"RCI rebrands as International Institute of Building Enclosure Consultants","url":"https://roofingcontractor.com/articles/93560-rci-rebrands-as-international-institute-of-building-enclosure-consultants","publisher":"Roofing Contractor"}],"category":"organizations","type":"organization","country":null},{"slug":"international-residential-code","title":"International Residential Code (IRC) Chapter 9","summary":"The International Residential Code is the US model code for one- and two-family homes; Chapter 9 covers roof assemblies and roof coverings.","body":"The **International Residential Code (IRC)** is a model code published by the International Code Council (ICC) for detached one- and two-family dwellings and townhouses. It sits alongside the [International Building Code](/international-building-code), which covers other buildings. Like the IBC, it is updated every three years and is adopted, often with local amendments, by most US states and many municipalities.\n\nThe IRC is written in a prescriptive style so that builders can follow it without engineering design in most cases.\n\n## Chapter 9: Roof Assemblies\n\nChapter 9 of the 2024 IRC includes sections on:\n\n- general requirements\n- fire classification\n- weather protection (flashing, crickets, drainage)\n- materials\n- requirements for roof coverings (Section R905)\n- roof insulation\n- rooftop photovoltaic systems\n- reroofing\n\nSection R905 is the part roofers use most. It sets rules for each roof covering type, including:\n\n- **Asphalt shingles** – minimum slope, underlayment, fastening, ice barrier requirements in cold climates, flashing details and wind classification under [ASTM D7158](/astm-d7158) or [ASTM D3161](/astm-d3161) depending on design wind speed.\n- **Clay and concrete tile, metal roof shingles and panels, slate, wood shingles and shakes** – minimum slopes, underlayment and attachment.\n- **Low-slope coverings** – built-up, modified bitumen, single-ply, sprayed foam and liquid-applied systems.\n\nReferenced product standards include [ASTM D3462](/astm-d3462) for asphalt shingles and [UL 2218](/ul-2218) where impact resistance is claimed.\n\n## Other relevant chapters\n\nRoof framing, sheathing and ventilation of attics and enclosed rafter spaces are in Chapter 8 (Roof-Ceiling Construction). Energy efficiency, including roof and ceiling insulation, is in Chapter 11, based on the International Energy Conservation Code.\n\n## Regional differences\n\nLocal amendments are common in roofing, for example:\n\n- extra wind provisions in hurricane-prone coastal areas\n- requirements for ice barrier underlayment in snow regions\n- Class A roofs in wildland-urban interface areas\n\nHomeowners and contractors should confirm the edition and amendments adopted locally before planning a roof replacement.","key_facts":[{"label":"Publisher","value":"International Code Council (ICC)"},{"label":"Scope","value":"One- and two-family dwellings and townhouses"},{"label":"Roofing chapter","value":"Chapter 9, Roof Assemblies"},{"label":"Roof covering section","value":"R905"},{"label":"Update cycle","value":"Every 3 years"}],"regions":["North America"],"aliases":["IRC","IRC Chapter 9","R905"],"related":["international-building-code","astm-d7158","astm-d3462","ice-and-water-shield","roof-ventilation"],"sources":[{"title":"2024 IRC Chapter 9 Roof Assemblies","url":"https://codes.iccsafe.org/content/IRC2024V1.0/chapter-9-roof-assemblies","publisher":"International Code Council"},{"title":"International Building Code","url":"https://en.wikipedia.org/wiki/International_Building_Code","publisher":"Wikipedia"},{"title":"Understanding asphalt shingle standards","url":"https://www.professionalroofing.net/articles/article/4817","publisher":"Professional Roofing (NRCA)"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"international-roofing-expo","title":"International Roofing Expo (IRE)","summary":"The International Roofing Expo is a large annual roofing trade show in the United States, organised by Informa Markets with NRCA as official sponsor.","body":"The International Roofing Expo (IRE) is an annual trade show and conference for the roofing industry, held in the United States. The show's organisers say it has more than 65 years of history. It is run by Informa Markets, a division of Informa PLC. The National Roofing Contractors Association (NRCA) is the official show sponsor, and *Roofing Contractor* magazine is the official show publication. Its website is theroofingexpo.com.\n\n## Format\n\nThe expo combines an exhibit hall with an education programme. Exhibitors include manufacturers of roofing materials, equipment, tools, software, vehicles and safety products. Attendees are mainly roofing contractors, along with distributors, consultants, architects, building owners and facility managers.\n\nThe education programme includes seminars, workshops and product demonstrations on technical topics, business management, safety and workforce. NRCA holds events and education sessions as part of the show.\n\n## Location\n\nThe show rotates among large U.S. convention cities. The 2027 edition is scheduled for 16-18 February 2027 at the Las Vegas Convention Center, West Hall, in Las Vegas, Nevada.\n\n## Role in the industry\n\nTrade shows like IRE are where many new roofing products are introduced and where contractors meet suppliers. They also host awards, association meetings and networking events. Other North American roofing events include regional shows run by state and regional contractor associations, such as the Texas Roofing Conference and the conventions of the Western States Roofing Contractors Association and the Midwest Roofing Contractors Association.\n\n## International counterparts\n\nIn Europe, major events for the roofing trade include DACH+HOLZ International in Germany, BAU in Munich for the wider building materials market, and Batimat in France. Many countries also hold national roofing exhibitions linked to their contractor associations.","key_facts":[{"label":"History","value":"More than 65 years"},{"label":"Organiser","value":"Informa Markets"},{"label":"Official sponsor","value":"NRCA"},{"label":"2027 show","value":"16-18 February 2027, Las Vegas"}],"regions":["North America"],"aliases":["IRE","The Roofing Expo"],"related":["nrca","roofing-contractor-magazine","dach-holz-international","bau-munich"],"company":{"website":"https://theroofingexpo.com","parent":"Informa Markets","known_for":["Annual roofing trade show and conference"]},"sources":[{"title":"International Roofing Expo home page","url":"https://theroofingexpo.com/en/home.html","publisher":"Informa Markets"},{"title":"About NRCA","url":"https://theroofingexpo.com/en/about/nrca.html","publisher":"International Roofing Expo"}],"category":"organizations","type":"organization","country":null},{"slug":"invention-of-corrugated-iron","title":"Invention of Corrugated Iron (1829)","category":"history","type":"event","summary":"In 1829 Henry Robinson Palmer of the London Dock Company patented corrugated metal sheets, whose ridges let thin iron span roofs unsupported.","body":"Corrugated iron was invented in London in the late 1820s. In **1829**, **Henry Robinson Palmer**, architect and engineer to the London Dock Company, was granted a patent for \"indented or corrugated metallic sheets\". Bending thin metal into a wave profile made it far stiffer than a flat sheet of the same weight, so it could span between widely spaced supports, or even form a self-supporting arch.\n\n## The first buildings\n\nPalmer saw the material as suited to wide-span roofs. In 1830 he built a shed at the London docks with a span of about 12 m (40 ft), roofed entirely in self-supporting corrugated iron. A contemporary account praised it as the lightest and strongest roof, for its weight, ever made. Early railway and dockyard roofs followed, including at Chatham Dockyard and Liverpool Lime Street station.\n\n## Material and protection\n\nThe first sheets were wrought iron produced by puddling. Plain iron rusts quickly, so galvanising, coating the iron with zinc, became essential. British sources say galvanising was perfected soon after corrugated iron appeared, and the combination became known as corrugated galvanised iron (CGI). Sources do not agree on a precise date for the first galvanised corrugated sheet.\n\n## After the patent\n\nPalmer's patent expired in **1843**. With no monopoly, manufacturers multiplied and corrugated iron became a worldwide roofing material. From the 1890s mild steel gradually replaced wrought iron, but the name \"corrugated iron\" stuck.\n\n## Typical early sheets\n\nHistoric British sheets were usually 0.9-3 m (3-10 ft) long with a corrugation pitch of about 75-125 mm (3-5 in). Roofing sheets were commonly 18 Standard Wire Gauge, about 1.2 mm (0.048 in) thick, considerably heavier than most modern sheet.\n\n## Significance\n\nThe invention made it possible to roof large spaces cheaply with a light, prefabricated, easily shipped product. Within two decades it was being exported in prefabricated buildings to Australia, Africa and beyond.","key_facts":[{"label":"Patent","value":"1829, Henry Robinson Palmer"},{"label":"First building","value":"1830 dock shed, about 12 m (40 ft) span"},{"label":"Patent expired","value":"1843"},{"label":"Steel replaces iron","value":"From the 1890s"}],"regions":["Europe","Global"],"aliases":["corrugated iron patent","Henry Palmer corrugated iron"],"related":["spread-of-corrugated-iron","corrugated-iron","galvanized-steel-roofing","history-of-roofing"],"company":null,"sources":[{"title":"Corrugated galvanised iron","url":"https://en.wikipedia.org/wiki/Corrugated_galvanised_iron","publisher":"Wikipedia"},{"title":"Corrugated Iron Architecture","url":"https://buildingconservation.com/articles/corrugated-iron-architecture/corrugated-iron-architecture.htm","publisher":"The Building Conservation Directory"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"}],"country":null},{"slug":"irimoya","title":"Irimoya (East Asian Hip-and-Gable Roof)","category":"roof-forms","type":"article","summary":"Irimoya is the Japanese hip-and-gable roof: a hip roof whose upper part rises into gables on two sides, known as xieshan in China and paljak in Korea.","body":"Irimoya (入母屋) is the Japanese name for the hip-and-gable roof, a roof that slopes down on all four sides like a hip roof but whose upper portion, on two opposite ends, is formed as a vertical gable. The resulting silhouette, with a triangular gable above a broad, sweeping hipped skirt, is one of the most recognisable forms in East Asian architecture. It is also called the \"resting hill\" roof, and in Japan moya-zukuri.\n\n## Regional names\n\n- **China:** xieshan (歇山). Tradition credits its development, as an adaptation of the hip roof, to the Eastern Han dynasty.\n- **Korea:** paljakjibung (팔작지붕). It was the most common roof type in authoritative buildings of the Joseon dynasty.\n- **Japan:** irimoya, introduced from China in the 6th century.\n\n## Structure\n\nIn Japanese temple architecture the gable sits over the moya (the core of the building), while the lower hipped part covers the hisashi, the surrounding aisle or veranda. The arrangement allows a deep, sheltering eave all around the building while keeping the visual emphasis of a gable.\n\n## History and use in Japan\n\nIrimoya roofs were first used for the main halls and lecture halls of Buddhist temple compounds. They were later adopted for the main sanctuaries (honden) of Shinto shrines and for palaces, castles and, during the Middle Ages, folk dwellings. They remain in wide use in temples and shrines. Examples include the Tamamushi Shrine, Shimogamo Shrine and the main gate of Shitennō-ji. Shikorobuki is recorded as a variant of the form.\n\n## Other notable examples\n\n- The Great Buddha Hall of Nanchan Temple in China, dating from the Tang dynasty.\n- Muryangsujeon Hall at Buseoksa temple in Korea.\n\n## Roofing materials\n\nIrimoya roofs are covered with clay tiles, copper sheet, cypress bark, wooden shingles or thatch, depending on the building's rank and period. Ornamental ridge tiles and gable boards are characteristic.","key_facts":[{"label":"Chinese name","value":"Xieshan"},{"label":"Korean name","value":"Paljakjibung"},{"label":"Arrived in Japan","value":"6th century, from China"}],"regions":["East Asia"],"aliases":["hip-and-gable roof","xieshan","paljakjibung","moya-zukuri","resting hill roof"],"related":["hip-roof","dutch-gable-roof","pagoda-roof","gable-roof"],"company":null,"sources":[{"title":"Irimoya","url":"https://en.wikipedia.org/wiki/Irimoya","publisher":"Wikipedia"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"}],"country":null},{"slug":"irish-thatch","title":"Irish Thatch","type":"article","summary":"Straw and reed thatched roofs on whitewashed Irish cottages, an ancient building tradition now mostly preserved on heritage and holiday homes.","body":"The whitewashed, thatched cottage is one of the most familiar images of traditional Irish architecture. Thatched dwellings, together with related forms such as the blackhouse, belong to a building tradition in Ireland that is very old, and straw was among the most common materials of vernacular building on the island.\n\n## Construction\n\nTraditional Irish cottages were long, narrow, single-storey buildings with thick stone or mud walls and a roof of timber couples (rafters) carrying a covering of thatch. Common thatching materials were straw from oats, wheat or rye and, near rivers and lakes, water reed. Thatch was often laid over a base layer of sods, and in exposed western districts roofs were frequently tied down with ropes weighted by stones or fixed to pegs set into the walls to resist Atlantic gales.\n\nThatch needs a steep pitch, generally about 45-55 degrees, and regular maintenance, with the ridge being the first part to wear.\n\n## Decline and survival\n\nAs slate, and later corrugated iron and concrete tile, became cheaper and more available in the 19th and 20th centuries, thatch declined sharply. Surviving thatched cottages are now often regarded as quaint, and many are rented to tourists as holiday homes. Examples can be seen in villages such as Kilmore Quay in County Wexford and Cahir in County Tipperary.\n\n## Slate\n\nSlate largely replaced thatch on towns and farmhouses. North Wales, whose quarries dominated world roofing slate production from about 1780 to 1940, exported both slate and skilled workers to Ireland, and Irish quarries also produced roofing slate.\n\n## Conservation\n\nKeeping a thatched roof in Ireland today involves the same issues as elsewhere in Britain and Europe: a shortage of skilled thatchers, the availability of suitable straw and reed, higher insurance costs and fire safety. Heritage grant schemes have been used in Ireland to help owners re-thatch traditional cottages, but the number of thatched homes remains small compared with the past.","key_facts":[{"label":"Typical building","value":"Whitewashed single-storey cottage"},{"label":"Thatch materials","value":"Cereal straw, water reed"},{"label":"Typical pitch","value":"45-55°"},{"label":"Successor materials","value":"Slate, corrugated iron, concrete tile"}],"regions":["Europe"],"aliases":["Irish thatched cottage","Thatched cottage Ireland"],"related":["english-thatch","thatch","roofing-in-ireland","natural-slate"],"sources":[{"title":"Architecture of Ireland","url":"https://en.wikipedia.org/wiki/Architecture_of_Ireland","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"The Slate Landscape of Northwest Wales","url":"https://whc.unesco.org/en/list/1633","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing","country":null},{"category":"world-roofing","type":"article","company":null,"slug":"longhouse-roof","title":"Iroquoian Longhouse Roof","summary":"Rounded bark roof of the Haudenosaunee and Wendat longhouse: bent poles sheathed in elm or cedar bark, with smoke vents over a line of hearths.","body":"The longhouse was the principal dwelling of the Iroquoian-speaking peoples of the Eastern Woodlands, including the Haudenosaunee (Iroquois) of present-day New York and the Huron-Wendat, Petun and Neutral of Southern Ontario. It sheltered several related families under a single long, rounded bark roof, and remained the common residence of the region until about the 18th century.\n\n## Frame\n\nBuilders set stiff posts in the ground along both sides of the house, then bent flexible poles over and fastened them to the tops of the wall posts to form the roof. Horizontal poles were lashed across with strips of bark or bark rope to stiffen the frame. The result was a long building with straight sides and a rounded, arbour-like roof.\n\n## Bark covering\n\nThe whole frame was sheathed in sheets of bark. The Huron-Wendat used cedar bark, while the Haudenosaunee used elm bark. Because walls and roofs do not survive, archaeologists reconstruct them from post moulds in the soil, from the accounts of French missionaries and explorers, and from oral histories.\n\n## Hearths and smoke\n\nHearths ran down a central aisle, typically 6-13 m (20-43 ft) apart, with about four to twelve in a house and two families sharing each fire. Vents or smoke holes in the roof above the hearths let smoke escape.\n\n## Size\n\nWidths of about 6-9 m (20-30 ft) are recorded; the 18th-century writer Joseph-François Lafitau gave figures in this range. Houses could be lengthened as households grew. One longhouse excavated in 1970-72 at the Moyer site in Southern Ontario was 93 m (305 ft) long.\n\n## Reconstructions\n\nSainte-Marie among the Hurons, near Midland, Ontario, is a reconstruction of a mission founded about 1640, rebuilt in the 1960s, and includes longhouses that show the roof form.\n\n## Related forms\n\nOn the Pacific Northwest coast, similarly long communal houses developed independently but were roofed with split cedar planks rather than bark (see plank-house).","key_facts":[{"label":"Peoples","value":"Haudenosaunee, Huron-Wendat, Petun, Neutral"},{"label":"Bark","value":"Elm (Haudenosaunee); cedar (Wendat)"},{"label":"Roof form","value":"Rounded, on bent poles"},{"label":"Width","value":"About 6-9 m (20-30 ft)"},{"label":"Long example","value":"93 m (305 ft), Moyer site, Ontario"}],"regions":["North America"],"aliases":["Longhouse","Haudenosaunee longhouse","Iroquois longhouse","Bark longhouse"],"related":["roofing-in-canada","roofing-in-the-united-states","plank-house","prehistoric-shelters-and-early-thatch"],"sources":[{"title":"Longhouse","url":"https://www.thecanadianencyclopedia.ca/en/article/longhouse","publisher":"The Canadian Encyclopedia"},{"title":"Longhouse","url":"https://en.wikipedia.org/wiki/Longhouse","publisher":"Wikipedia"}],"country":null},{"slug":"japanese-kawara-tile","title":"Japanese Kawara Tile","type":"article","summary":"Fired clay roof tiles of Japan, used on temples since Buddhism's arrival and on houses since the Edo period, made in centres such as Sanshu and Sekishu.","body":"*Kawara* (瓦) is the Japanese word for a fired clay roof tile. Kawara roofs, with their regular rows of grey or reddish-brown tiles and heavy ornamented ridges, are one of the most recognisable features of Japanese temples, castles and houses.\n\n## History\n\nCeramic roof tiles came to Japan with Buddhist temple building. The Kondō (main hall) of Hōryū-ji near Nara is roofed with ceramic tiles on an *irimoya* (hip-and-gable) form. For many centuries tiles were largely reserved for temples, palaces and castles, while ordinary houses were thatched or shingled. In the Edo period, urban townhouses (*machiya*) and storehouses (*dōzō*) adopted tiles because they resisted fire better than thatch; storehouses combined thick earth plaster walls with tiled roofs.\n\n## Ornaments\n\nRidge ends carry *onigawara*, ornamental tiles or statues depicting an ogre (*oni*) or fearsome beast. They were historically used on Buddhist temples and now appear on many traditionally styled buildings. Their likely ancestor is the *oni-ita*, a painted board meant to protect against roof leaks, and before them came floral ornaments called *hanagawara*. Onigawara became strongly three-dimensional over time.\n\n## Production centres\n\nKawara are made in several regional centres, each with its own clays and finishes. The best known are:\n\n- **Sanshu** (Mikawa), in Aichi Prefecture around Takahama, a major centre of the ceramic industry.\n- **Sekishu**, centred on Gōtsu in Shimane Prefecture, long known for its reddish-brown glazed tiles.\n- **Awaji**, on Awaji Island in Hyōgo Prefecture, known for smoked silver-grey (*ibushi*) tiles.\n\n## Types and fixing\n\nTraditional roofs used separate concave and convex tiles (*hongawara*), while the single-piece S-shaped *sangawara* became standard on houses. Older roofs bedded tiles in a thick layer of clay, which made them heavy. Modern guidelines require tiles to be fixed mechanically to battens with nails, screws or wire, improving resistance to typhoon winds and earthquakes.\n\n## Today\n\nKawara compete with lighter metal and fibre-cement roofing on new houses, but remain the standard for temples, shrines and traditional-style homes.","key_facts":[{"label":"Material","value":"Fired clay, glazed or smoked"},{"label":"Early use","value":"Buddhist temples (e.g. Hōryū-ji)"},{"label":"Spread to houses","value":"Edo period, for fire protection"},{"label":"Production centres","value":"Sanshu (Aichi), Sekishu (Shimane), Awaji (Hyōgo)"},{"label":"Ridge ornament","value":"Onigawara"}],"regions":["East Asia"],"aliases":["Kawara","Japanese roof tile","Sanshu-gawara","Sekishu-gawara","Awaji-gawara"],"related":["roofing-in-japan","clay-roof-tile","hanok-roof","gassho-zukuri"],"sources":[{"title":"Onigawara","url":"https://en.wikipedia.org/wiki/Onigawara","publisher":"Wikipedia"},{"title":"Japanese architecture","url":"https://en.wikipedia.org/wiki/Japanese_architecture","publisher":"Wikipedia"},{"title":"Gōtsu, Shimane","url":"https://en.wikipedia.org/wiki/G%C5%8Dtsu,_Shimane","publisher":"Wikipedia"},{"title":"Takahama, Aichi","url":"https://en.wikipedia.org/wiki/Takahama,_Aichi","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"jerkinhead-roof","title":"Jerkinhead Roof (Clipped Gable)","category":"roof-forms","type":"term","summary":"A jerkinhead roof is a gable roof whose peak is clipped by a small hip, combining a mostly vertical gable with a short sloping face at the top.","body":"A jerkinhead roof, also called a clipped gable, half-hipped or snub-gable roof, is a hybrid of a gable roof and a hip roof. The ends of the building rise as gable walls for most of their height, but the very top of each gable is cut off by a short hipped slope that runs back to the ridge. It is the reverse of the Dutch gable (gablet) roof, where the hip is below and the small gable is above.\n\n## Where it is found\n\nJerkinhead roofs are common across the UK, particularly on traditional houses with clay tiles, and in parts of Germany and central Europe, where they are known by terms such as Krüppelwalmdach. In North America they appear on Craftsman and Arts and Crafts bungalows and in some Tudor Revival and Queen Anne houses.\n\n## Advantages\n\n- **Wind resistance:** clipping the top of the gable reduces the large flat gable face and the exposed peak, improving wind performance compared with a full gable.\n- **Headroom:** a jerkinhead retains more usable roof space than a full hip roof because most of the end wall is still vertical.\n- **Appearance:** it softens the silhouette of a steep gable and is valued for its traditional character.\n\n## Construction\n\nThe roof is framed as a gable with a short hip at each end: hip rafters run from the top of the clipped gable wall to the ridge, with short jack rafters between. The small hip face is covered in the same material as the main roof and capped with hip tiles or cap shingles. Flashing details at the clipped corners must shed water from the short hips onto the gable wall's verge.\n\n## Terminology\n\n\"Jerkinhead\", \"half-hip\", \"clipped gable\" and \"snub gable\" are used interchangeably; the preferred term varies by region and author.","key_facts":[{"label":"Also called","value":"Clipped gable, half-hip, snub gable"},{"label":"Reverse of","value":"Dutch gable (gablet)"},{"label":"Benefit","value":"Better wind resistance than a full gable"}],"regions":["Europe","North America"],"aliases":["clipped gable roof","half-hipped roof","half-hip roof","snub gable","Krüppelwalmdach"],"related":["gable-roof","hip-roof","dutch-gable-roof","roof-hip"],"company":null,"sources":[{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"},{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"}],"country":null},{"slug":"jesuit-mission-roof-tiles","title":"Jesuit Mission Roof Tiles of South America","category":"history","type":"article","summary":"Fired clay roof tiles made at the Jesuit missions of Paraguay, Argentina, Brazil and Bolivia from the 17th century, replacing straw roofs.","body":"The Jesuit missions (*reducciones*) founded among the Guaraní of present-day Paraguay, Argentina and Brazil from 1609, and later among the Chiquitos of eastern Bolivia, produced their own fired clay roof tiles on a large scale. Tile roofs on churches, colleges and Indigenous houses became one of the defining features of mission towns, several of which are now UNESCO World Heritage Sites.\n\n## From straw to tile\n\nEarly mission buildings were roofed with straw. A 2016 archaeological study by María Victoria Roca of the decorated tiles of the church of Santa Ana in Misiones, Argentina, summarises the history. Historians date a second building phase, about 1641 to 1695, as the era of churches and Indigenous houses with tile roofs. Tiles were adopted partly as protection against fire after raids by slavers from São Paulo, and later Jesuit instructions, from 1714, called for straw roofs to be replaced with tile. During the second term of the provincial Luis de la Roccafiorita (1722 to 1726) it became the rule that each mission should have its own tile workshop.\n\n## Making the tiles\n\nAccording to the sources Roca reviews, clay was kneaded and left to rest for days, trampled by cattle and oxen, pressed into moulds, dried on a rack and fired in kilns. The Jesuit Anton Sepp described three kilns, each holding about 4,000 tiles. Tiles from San Ignacio Miní measure about 46 to 55 cm (18 to 22 in) long, 19 to 22 cm (7.5 to 8.7 in) wide and about 1 cm (0.4 in) thick. Roca notes two colonial traditions in the region: Spanish curved tiles with a parabolic profile and Portuguese tiles with a semicircular profile.\n\nAt Santa Ana, 67 decorated fragments were recovered, almost all from inside the church. Most carry a border with a crescent motif at one end, and the author concludes that decorated tiles covered a large part of the church roof, not only the edges. Some show traces of burning from the destruction of the mission in the early 19th century. When the explorer Juan Bautista Ambrosetti visited in 1894 the roofs had collapsed.\n\n## Chiquitos\n\nIn the Chiquitos missions of Bolivia, built in the 18th century, the structure works the other way round from European masonry churches. A wooden skeleton of columns set into the ground carries the tiled roof, which was built first; the adobe walls carry no load. Wide porches and low eaves protect the walls from tropical rain, and roof and floor tiles came from local tile works. The churches, restored from 1972 under the architect Hans Roth and later local teams, were inscribed by UNESCO in 1990.\n\n## World Heritage\n\n- Jesuit Missions of the Guaranis (Argentina and Brazil), 1983\n- Jesuit Missions of the Chiquitos (Bolivia), 1990\n- Jesuit Missions of La Santísima Trinidad de Paraná and Jesús de Tavarangue (Paraguay), 1993","key_facts":[{"label":"Region","value":"Paraguay, northeast Argentina, southern Brazil, eastern Bolivia"},{"label":"Period","value":"17th-18th centuries"},{"label":"Tile size (San Ignacio Miní)","value":"46-55 cm long, 19-22 cm wide"},{"label":"Kilns","value":"About 4,000 tiles per firing (Sepp)"},{"label":"UNESCO","value":"1983, 1990, 1993 listings"}],"regions":["Latin America"],"aliases":["Guaraní mission tiles","tejas misioneras","reducciones roof tiles"],"related":["clay-roof-tile","spanish-tile","roofing-in-paraguay","roofing-in-argentina","roofing-in-bolivia","roofing-in-brazil"],"company":null,"sources":[{"title":"Arqueología en las Misiones Jesuitas de Guaraníes: las tejas decoradas de la iglesia de Santa Ana","url":"https://cau.iaa.fadu.uba.ar/wp-content/uploads/2019/03/Roca_Tejas-decoradas_SantaAna.pdf","publisher":"Instituto de Arte Americano, FADU-UBA"},{"title":"Jesuit Missions of the Chiquitos","url":"https://en.wikipedia.org/wiki/Jesuit_Missions_of_the_Chiquitos","publisher":"Wikipedia"},{"title":"Jesuit Missions of La Santísima Trinidad de Paraná and Jesús de Tavarangue","url":"https://whc.unesco.org/en/list/648","publisher":"UNESCO World Heritage Centre"},{"title":"Jesuit Missions of La Santísima Trinidad de Paraná and Jesús de Tavarangue","url":"https://en.wikipedia.org/wiki/Jesuit_Missions_of_La_Sant%C3%ADsima_Trinidad_de_Paran%C3%A1_and_Jes%C3%BAs_de_Tavarangue","publisher":"Wikipedia"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"}],"country":null},{"slug":"joglo","title":"Joglo Roof","category":"roof-forms","type":"term","summary":"The joglo is the steep, two-peaked Javanese roof over four tall central columns and a stepped tumpang sari ceiling, historically reserved for nobility.","body":"The *joglo* is the most complex of the traditional Javanese roof types, found on the main houses (*omah*) and open pavilions (*pendopo*) of noble families, palaces and official residences in Central and East Java, Indonesia. Its steep central roof, nearly a pyramid with two peaks, rises over four tall central columns topped by a stepped timber ceiling.\n\n## Roof hierarchy\n\nJavanese roofs were ranked by the social and economic status of the owner. In ascending order of complexity the main types are:\n\n- **Kampung** - a simple gabled roof for ordinary houses;\n- **Limasan** - a hipped roof;\n- **Joglo** - the most elaborate, traditionally reserved for the palace, official residences, government estates and noble houses.\n\nUnlike limasan and kampung roofs, the joglo does not use king posts.\n\n## Structure\n\nThe roof is built around four innermost columns, the tallest in the house, which support the steepest roof of all Javanese types. Above them sits the *tumpang sari*, a layered beam structure forming a ceiling shaped like an inverted stepped pyramid. The space below it, the *dalem*, is the most sacred part of the house and is usually left empty; incense was traditionally burned there, and the bride and groom sit there during weddings.\n\nAdditional rings of columns and lower roof extensions enlarge the basic form. Very large joglo roofs, such as the Grand Pendopo of the Mangkunegaran Palace in Surakarta, look almost like a mountain.\n\n## Variants\n\nSources list seven joglo types: Kepuhan, Taraju Mas, Lambang Gantung (Pangrawit), Wantah, Ceblokan, Tawon Boni and Semar Tinandu. There are also \"male\" and \"female\" styles, the male being larger.\n\n## Coverings\n\nJavanese houses are not raised on piles, unlike most Indonesian vernacular houses. Across Java, clay tile is now the dominant roof covering: in BPS data, more than 80% of houses in Central Java, East Java, West Java and Yogyakarta have tiled roofs.\n\n## Influence\n\nJoglo and limasan roof structures were adopted in mid-18th-century Dutch \"Indies style\" buildings and continue to appear on modern halls, university buildings and airport terminals.","key_facts":[{"label":"Region","value":"Central and East Java, Indonesia"},{"label":"Rank","value":"Highest of kampung, limasan, joglo"},{"label":"Key structure","value":"Four central columns and tumpang sari ceiling"},{"label":"Typical covering today","value":"Clay tile"}],"regions":["Southeast Asia"],"aliases":["joglo house","rumah joglo","Javanese roof"],"related":["roofing-in-indonesia","hip-roof","pyramid-roof","clay-roof-tile","pagoda-roof"],"company":null,"sources":[{"title":"Joglo","url":"https://en.wikipedia.org/wiki/Joglo","publisher":"Wikipedia"},{"title":"Indonesian architecture","url":"https://en.wikipedia.org/wiki/Indonesian_architecture","publisher":"Wikipedia"},{"title":"Ini Dia 10 Provinsi dengan Persentase Rumah Genting Tertinggi","url":"https://goodstats.id/article/ini-dia-10-provinsi-dengan-persentase-rumah-genting-tertinggi-5B3q0","publisher":"GoodStats (citing BPS)"}],"country":null},{"slug":"johns-manville","title":"Johns Manville","category":"manufacturers","type":"company","summary":"Johns Manville is a Denver-based maker of commercial roofing systems, insulation and engineered products, founded in 1858 and owned by Berkshire Hathaway since 2001.","body":"Johns Manville (JM) is a US manufacturer of insulation, commercial roofing materials and engineered products, headquartered in Denver, Colorado. Its history begins in 1858, when Henry Ward Johns started a business in New York City; among his earliest products were roofing materials made by coating cloth with hot tar. The company has been a wholly owned subsidiary of Berkshire Hathaway since 2001.\n\n## History\n\nIn 1886 Charles B. Manville and his sons founded the Manville Covering Company in Milwaukee, a pipe-insulation business. The two firms merged in 1901 as the H.W. Johns-Manville Company, later reincorporated as Johns-Manville Corporation and listed on the New York Stock Exchange. For much of the twentieth century the company was a major producer of asbestos-containing products. Faced with large numbers of asbestos injury claims, it filed for Chapter 11 protection in 1982 and emerged in 1988 as Manville Corporation,. It took the name Johns Manville, without a hyphen, in 1997. Berkshire Hathaway acquired it in 2001.\n\n## Roofing\n\nJM's roofing business serves the commercial low-slope market. Its range covers membrane roofing systems and roof insulation, sold through distributors to roofing contractors.\n\n## Other activities\n\nThe company also makes building insulation (fibreglass batts and other formats), mechanical insulation, and engineered glass-fibre and nonwoven products used by other manufacturers, including mats for roofing.\n\n## Ownership\n\nAs a Berkshire Hathaway company, JM does not publish separate stock-market accounts; its results are reported within its parent's manufacturing businesses. Its research and development centre is in Littleton, Colorado. JM's long history means its name also appears on many older roofs and insulation systems in North America.","key_facts":[{"label":"Founded","value":"1858, New York City"},{"label":"Headquarters","value":"Denver, Colorado, US"},{"label":"Parent","value":"Berkshire Hathaway (since 2001)"},{"label":"Business lines","value":"Insulation, roofing materials, engineered products"}],"regions":["North America","Europe"],"aliases":["JM","Johns-Manville","Manville Corporation"],"related":["built-up-roofing","modified-bitumen-roofing","tpo-roofing","polyiso-insulation"],"company":{"founded":"1858","headquarters":"Denver, Colorado, United States","website":"https://www.jm.com","parent":"Berkshire Hathaway","known_for":["Commercial roofing systems","Insulation","Engineered glass-fibre products"]},"sources":[{"title":"Johns Manville","url":"https://en.wikipedia.org/wiki/Johns_Manville","publisher":"Wikipedia"},{"title":"History & Heritage","url":"https://www.jm.com/en/our-company/HistoryandHeritage/","publisher":"Johns Manville"}],"country":null},{"slug":"jomon-pit-dwellings","title":"Jomon Pit Dwellings","category":"history","type":"article","summary":"Semi-sunken houses of Japan's Jomon period, with post-supported roofs of thatch or packed earth, best known from Sannai-Maruyama and Goshono.","body":"Jomon pit dwellings are the semi-subterranean houses of Japan's Jomon period (about 13,000 to 400 BCE). In Japanese they are called tateana (竪穴) dwellings, also written dateana tatemono. A shallow oval or round pit was dug, posts were set in the floor, and a roof framed on those posts was brought down to the edge of the pit. The type was not new to the Jomon: pit dwellings have been traced back to Palaeolithic sites in Hokkaido and Kyushu.\n\n## Sannai-Maruyama\n\nThe Sannai-Maruyama site in Aomori was occupied from the Early to Middle Jomon, about 3900 to 2200 BCE. With 648 pit dwellings it is one of the largest Jomon settlements known. Early dwellings were usually about 3-4 m (10-13 ft) across.\n\nAround 2900 BCE the settlement added other building types:\n\n- **Raised storehouses** on pillars, without fire pits, replacing storage pits.\n- **Longhouses**, large oval buildings, the longest about 32 m (105 ft) long, used while pit dwellings continued.\n- **A six-pillar structure**, built around 2600 BCE, of six chestnut posts about 1 m (3.3 ft) in diameter in two lines 4.2 m (13.8 ft) apart, set in holes 2 m (6.6 ft) wide and deep. Only the waterlogged bases survived.\n\n## Goshono and earth-covered roofs\n\nAt the Goshono site in Iwate, from around 2500 BCE, more than 800 pit dwellings have been found. Most were supported by four or six pillars set in an oval pit, with eaves reaching the upper edges of the pit so that the house looked like a low mound. Each had a hearth, and some may have had a loft-like storage space.\n\nJomon pit dwellings were long assumed to be thatched. Studies of burned houses at Goshono suggest that some instead had roofs of packed earth laid over the timber frame. The charred remains of one dwelling about 4,200 years old are displayed under a glass floor in the Goshono Jomon Museum, and several houses have been rebuilt on the site with earth roofs.\n\n## World Heritage\n\nSannai-Maruyama and Goshono are among the Jomon Prehistoric Sites in Northern Japan, inscribed on the UNESCO World Heritage List on 27 July 2021.\n\n## Significance for roofing history\n\nThe Goshono evidence is a reminder that reconstructions often default to thatch because it is familiar, while the archaeological traces can point elsewhere. Earth over timber, as in the later Plains earth lodge and in turf-roofed houses of northern Europe, gives insulation and fire resistance at the cost of a heavy load on the frame.","key_facts":[{"label":"Period","value":"Jomon, about 13,000-400 BCE"},{"label":"Japanese term","value":"Tateana (竪穴) dwelling"},{"label":"Sannai-Maruyama","value":"648 pit dwellings, about 3900-2200 BCE"},{"label":"Goshono","value":"800+ pit dwellings; evidence of earth-covered roofs"},{"label":"World Heritage","value":"Jomon Prehistoric Sites in Northern Japan, 2021"}],"regions":["East Asia"],"aliases":["tateana","dateana tatemono","Jomon houses","Japanese pit house"],"related":["pit-house","prehistory-of-roofing","sod-roof","earth-lodge","roofing-in-japan"],"company":null,"sources":[{"title":"Sannai-Maruyama Site","url":"https://en.wikipedia.org/wiki/Sannai-Maruyama_Site","publisher":"Wikipedia"},{"title":"Goshono Site","url":"https://www.mlit.go.jp/tagengo-db/en/R2-00507.html","publisher":"Japan Tourism Agency multilingual commentary database"},{"title":"Pit-house","url":"https://en.wikipedia.org/wiki/Pit-house","publisher":"Wikipedia"}],"country":null},{"slug":"jorn-utzon","title":"Jørn Utzon","category":"history","type":"person","summary":"Danish architect (1918-2008) who designed the Sydney Opera House, with its tiled shell roofs, and won the Pritzker Prize in 2003.","body":"**Jørn Utzon** (9 April 1918 - 29 November 2008) was a Danish architect, born in Copenhagen, best known for designing the **Sydney Opera House**. His work is notable for expressive roofs, often inspired by natural forms such as clouds, sails and waves.\n\n## Sydney Opera House\n\nIn **1957** Utzon won the international competition for the Sydney Opera House against 233 other entries. UNESCO describes the design as a radically new approach to construction, and its roof proved extremely hard to define and build. Working with engineers Ove Arup & Partners, the team eventually adopted the \"spherical solution\", in which all the shells are cut from a single sphere, allowing them to be built from repeated precast concrete ribs and panels.\n\nDisputes with the New South Wales government led Utzon to resign in **1966**. He left Australia on 28 February that year and never returned, so he never saw the completed building, which opened in 1973.\n\n## Other roof-focused works\n\n- **Bagsværd Church**, near Copenhagen (completed 1976), has a concrete ceiling of softly rounded vaults inspired by clouds.\n- **Kuwait National Assembly Building** (completed 1982) has a waving roof that gives the impression of moving fabric.\n\n## Recognition\n\nUtzon received the **Pritzker Architecture Prize** in **2003**.\n\n## Influence\n\nThe Sydney roofs are a frequently cited example of a roof form becoming the main expression of a building, and of collaboration between architect and engineer in solving an unprecedented geometry.\n\n## Death\n\nUtzon died on 29 November 2008 in Denmark. Sources differ on the place: some give Helsingør and others Copenhagen.","key_facts":[{"label":"Born","value":"9 April 1918, Copenhagen"},{"label":"Died","value":"29 November 2008, Denmark"},{"label":"Sydney competition","value":"Won 1957 (233 other entries)"},{"label":"Pritzker Prize","value":"2003"}],"regions":["Europe","Oceania","Middle East"],"aliases":["Jorn Utzon","Utzon"],"related":["sydney-opera-house-roof","frei-otto"],"company":null,"sources":[{"title":"Jørn Utzon","url":"https://en.wikipedia.org/wiki/J%C3%B8rn_Utzon","publisher":"Wikipedia"},{"title":"Sydney Opera House","url":"https://en.wikipedia.org/wiki/Sydney_Opera_House","publisher":"Wikipedia"}],"country":null},{"slug":"joseph-paxton","title":"Joseph Paxton","category":"history","type":"person","summary":"English gardener, glasshouse designer and MP (1803-1865) who designed the Crystal Palace and its ridge-and-furrow glass roof.","body":"**Sir Joseph Paxton** (3 August 1803 - 8 June 1865) was an English gardener, glasshouse designer, engineer and politician. He is best known as the designer of the **Crystal Palace** for the Great Exhibition of 1851, whose iron-and-glass roof transformed ideas about how large spaces could be enclosed.\n\n## Chatsworth\n\nPaxton was offered the post of head gardener at **Chatsworth** when he was about 20. There he experimented with glasshouses. His **Great Conservatory**, begun in 1836, was about 69 m (227 ft) long.\n\nIn 1849 Paxton succeeded in making the giant waterlily *Victoria regia* flower at Chatsworth, about a month after receiving a seedling. He built a special lily house for it, with flat ridge-and-furrow glazing. He described the lily's ribbed leaves as an inspiration for his roof structures.\n\n## Ridge-and-furrow glazing\n\nPaxton's roof system arranged glass in long folded rows, with ridges and valleys, carried on light supports. Rainwater ran into timber channels in the valleys, which doubled as rails for glazing trolleys. This channel became known as the \"Paxton gutter\".\n\n## The Crystal Palace\n\nFor the 1851 Great Exhibition, Paxton sketched an idea on blotting paper during a railway board meeting in Derby. The resulting building, of cast iron and about 293,000 glass panes, was built in Hyde Park and opened on 1 May 1851. Paxton, Fox and Cubitt, who were involved in delivering the building, were all knighted.\n\n## Later life\n\nPaxton served as Liberal **Member of Parliament for Coventry** from 1854 until his death in 1865.\n\n## Legacy\n\nPaxton showed that roofs could be made from standardised, factory-produced parts and erected quickly. His methods anticipated later prefabricated construction.","key_facts":[{"label":"Born","value":"3 August 1803"},{"label":"Died","value":"8 June 1865"},{"label":"Great Conservatory","value":"Begun 1836, about 69 m (227 ft) long"},{"label":"Key work","value":"Crystal Palace, 1851"},{"label":"MP for Coventry","value":"1854-1865"}],"regions":["Europe"],"aliases":["Sir Joseph Paxton","Paxton"],"related":["crystal-palace"],"company":null,"sources":[{"title":"Joseph Paxton","url":"https://en.wikipedia.org/wiki/Joseph_Paxton","publisher":"Wikipedia"},{"title":"The Crystal Palace","url":"https://en.wikipedia.org/wiki/The_Crystal_Palace","publisher":"Wikipedia"}],"country":null},{"slug":"joya-de-ceren","title":"Joya de Cerén","category":"history","type":"place","summary":"Maya farming village in El Salvador buried by a volcanic eruption around 600 CE, preserving earthen buildings and their thatched roofs.","body":"Joya de Cerén is a small pre-Hispanic Maya farming village in El Salvador that was buried by an eruption of the Loma Caldera vent around 600 CE. Because the village was covered quickly by fine, moist volcanic ash, it preserved everyday buildings, their contents and the remains of their roofs in a way that is very rare in the humid tropics. It was inscribed on the UNESCO World Heritage List in 1993.\n\nThe site was found by accident in 1976, when a bulldozer driver levelling ground for a government agricultural project uncovered buried structures. Archaeological survey has identified 18 structures, of which 10 have been fully or partly excavated, according to UNESCO.\n\n## Buildings\n\nAll the buildings are made of earth. UNESCO notes that public buildings and the sweat bath used rammed earth, while household buildings used wattle and daub (*bajareque*), a technique of poles and woven sticks plastered with clay that copes well with earthquakes. Crack patterns in the walls suggest a small earthquake struck shortly before the eruption.\n\nExcavated buildings include a large communal building beside a plaza, two dwellings, three storehouses, a kitchen, a sweat bath and two religious buildings. Each household used several separate small structures rather than a single house.\n\n## Roofs\n\nThe roofs were thick thatch carried on a timber frame. In their 1990 report on household archaeology at Cerén, Payson Sheets and colleagues describe wall poles that rose above the clay to support the roof, vertical posts tied into the ceiling system, and in places a raised pole platform (*tabanco*) spanning between walls. Adobe columns sometimes served as bases for roof posts. The roofs of some structures projected well beyond the walls, giving deep eaves that kept rain off the earthen walls, and pottery was found in fallen roofing material under the eaves.\n\nWhen the ash fell, the thatch collapsed onto the floors but remained identifiable, and the excavators collected large amounts of roofing material for radiocarbon dating. Residents also tucked obsidian blades into the thatch for storage, and some were recovered there with organic residues still on them.\n\n## Why it matters for roofing history\n\nThatched roofs rarely survive more than a few decades, so most knowledge of ancient Mesoamerican house roofs comes from post holes, depictions in stone or modern ethnography. Cerén provides direct physical evidence of how ordinary Classic-period roofs were framed, how far eaves projected, and how roof space was used for storage. Its combination of earthen walls, separate small buildings and steep thatch is similar to rural houses still built in parts of Central America.","key_facts":[{"label":"Location","value":"El Salvador"},{"label":"Buried","value":"About 600 CE (Loma Caldera eruption)"},{"label":"Discovered","value":"1976"},{"label":"Structures","value":"18 identified, 10 excavated"},{"label":"Roofs","value":"Thick thatch on timber poles, deep eaves"},{"label":"UNESCO","value":"World Heritage Site, 1993"}],"regions":["Latin America"],"aliases":["Cerén","Ceren","Joya de Ceren"],"related":["roofing-in-el-salvador","maya-thatched-house","thatch","palm-thatch","prehistoric-shelters-and-early-thatch"],"company":null,"sources":[{"title":"Joya de Cerén Archaeological Site","url":"https://whc.unesco.org/en/list/675","publisher":"UNESCO World Heritage Centre"},{"title":"Joya de Cerén","url":"https://en.wikipedia.org/wiki/Joya_de_Cer%C3%A9n","publisher":"Wikipedia"},{"title":"Household archaeology at Cerén, El Salvador (Ancient Mesoamerica 1, 1990)","url":"https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A458CD7DAF7B5CC22BD9E6A81E8C2270/S0956536100000092a.pdf/household_archaeology_at_ceren_el_salvador.pdf","publisher":"Cambridge University Press"},{"title":"Joya de Cerén: An Intimate Portrait of the Ancient Maya","url":"https://popular-archaeology.com/article/joya-de-ceren-an-intimate-portrait-of-the-ancient-maya/","publisher":"Popular Archaeology"}],"country":null},{"slug":"kalambo-falls-wooden-structure","title":"Kalambo Falls Wooden Structure","category":"history","type":"place","summary":"Two notched, joined logs from Kalambo Falls, Zambia, dated to at least 476,000 years ago: the oldest known structural use of wood.","body":"The Kalambo Falls wooden structure is a pair of worked logs found beside the Kalambo River in Zambia, near the border with Tanzania at the southeast end of Lake Tanganyika. The two logs were joined crosswise by a notch cut on purpose, and were dated by luminescence to at least 476,000 years ago. The find was published in *Nature* on 20 September 2023 under the title \"Evidence for the earliest structural use of wood at least 476,000 years ago\".\n\nIt is not a roof, and no shelter has been reconstructed from it. Its importance for roofing history is that it pushes the earliest known deliberate joining of timbers back by hundreds of thousands of years. Roof frames of every later period, from brush huts to timber longhouses, depend on the same basic skill.\n\n## The find\n\n- **Structure:** two logs fitted together; the upper one was shaped, and tool marks appear on both.\n- **Excavation:** 2019, by a team led by Larry Barham of the University of Liverpool, with dating by Geoff Duller of Aberystwyth University.\n- **Dating:** luminescence dating of the sand minerals around the wood. Smaller wooden objects from the site were buried about 390,000 and 324,000 years ago.\n- **Preservation:** the wood is thought to have survived because it stayed waterlogged near the waterfall.\n\n## Interpretation\n\nThe researchers suggested the logs might have formed a raised platform, a walkway or the foundation for dwellings on a floodplain that was periodically wet. Barham described one possibility as a platform by the river for daily tasks. The structure predates the appearance of *Homo sapiens*, so the builders may have been an earlier hominin species, possibly *Homo heidelbergensis*; this attribution is speculative. The team argued the find challenges the view that Stone Age people were always on the move.\n\n## Earlier work at the site\n\nKalambo Falls was excavated by J. Desmond Clark in 1953, 1956, 1959 and 1963. He recovered Late Acheulean stone tools, hearths and wooden objects including a club and digging sticks, showing that the site preserves organic material unusually well.\n\n## Significance for roofing history\n\nWood rots quickly, so the record of early building is biased toward stone. Kalambo Falls shows that hominins were shaping and joining timber long before any surviving evidence of a roofed dwelling. Whether such skills were used for shelters at this date is unknown.","key_facts":[{"label":"Age","value":"At least 476,000 years"},{"label":"Location","value":"Kalambo River, Zambia"},{"label":"Dating method","value":"Luminescence"},{"label":"Published","value":"Nature, 20 September 2023"},{"label":"Joint","value":"Two logs joined crosswise by a cut notch"}],"regions":["Africa"],"aliases":["Kalambo Falls logs","oldest wooden structure"],"related":["prehistory-of-roofing","prehistoric-shelters-and-early-thatch"],"company":null,"sources":[{"title":"Kalambo Falls","url":"https://en.wikipedia.org/wiki/Kalambo_Falls","publisher":"Wikipedia"},{"title":"Archaeologists uncover notched logs that may be the oldest known wooden structure","url":"https://www.smithsonianmag.com/smart-news/archaeologists-uncover-notched-logs-that-may-be-the-oldest-known-wooden-structure-180982942/","publisher":"Smithsonian Magazine"},{"title":"476,000-Year-Old Wooden Structure Unearthed in Zambia","url":"https://www.sci.news/archaeology/wooden-structure-kalambo-falls-zambia-12283.html","publisher":"Sci.News"},{"title":"Evidence for the earliest structural use of wood at least 476,000 years ago","url":"https://www.nature.com/articles/s41586-023-06557-9","publisher":"Nature"}],"country":null},{"slug":"kath-kuni","title":"Kath-kuni","category":"world-roofing","type":"term","summary":"Kath-kuni is the Himachal Pradesh building tradition of mortarless timber-and-stone walls under overhanging roofs of local slate or wooden shingles.","body":"**Kath-kuni** (also written *kath-khuni*) is the traditional way of building in the hills of Himachal Pradesh in northern India. Walls are made of alternating courses of dressed stone and timber laid without mortar, and the house is capped by a heavy, overhanging roof of local slate or wooden shingles. The name is usually explained as coming from Sanskrit *kashth* (wood) and *kona* (corner), after the jointed timber corners; local variants include *kath-kona* and, around Sarahan, *kath-ki-kanni*. The technique is believed to be roughly a thousand years old.\n\n## The roof\n\nThe roof is framed with timber. Beams laid across the tops of the walls carry purlins and rafters, and the ridge beam is set last, an event that marks the completion of the house. The covering is either local slate or wooden shingles:\n\n- **Slate** is the commonest covering. Some houses use slate cut into regular rectangles, others use irregular slabs laid as they come from the quarry. Slate is waterproof and resists frost, and its weight helps hold the timber structure down.\n- **Wooden shingles** are used where slate is not available.\n\nRoofs are usually **pent** (single-pitch) or **gable**, or a combination of the two, and their pitch and shape vary with altitude across the state. A steeper part sheds snow, while a flatter part can hold a layer of snow as insulation. The eaves overhang well beyond the walls to keep rain and snow off the timber, and are often hung with carved wooden pendants called *jhalar*.\n\n## Walls and timber\n\nDeodar, the western Himalayan cedar, is the main timber for walls, floors and roof framing; a local saying claims it lasts a thousand years in water. In the walls, pairs of long timber beams are laid with infill between them and tied across with dovetailed cross-pieces (*maanvi*) and wooden pegs (*kadil*). Higher up the wall, the share of timber increases and that of stone decreases. The building's own weight, including the roof, holds it together.\n\n## Earthquake performance\n\nHimachal Pradesh is seismically active. The nail-less timber joints can flex while staying locked, the stone plinth adds mass and stability, and the gap inside the double-skinned walls helps dissipate seismic forces. Houses are typically oriented with the long side facing the valley and the back to the mountain.\n\n## Building types\n\nOrdinary houses are two or three storeys, with cattle on the ground floor (*gaushala*) and living rooms above. Temples and tower temples can reach five to seven storeys, as at Summerkot and Chitkul in Kinnaur.\n\n## Today\n\nNew building materials are replacing kath-kuni construction, and the future of the craft is uncertain.","key_facts":[{"label":"Region","value":"Himachal Pradesh, western Himalaya, India"},{"label":"Roof covering","value":"Local slate or wooden shingles"},{"label":"Roof form","value":"Pent, gable or combined, with deep overhang"},{"label":"Main timber","value":"Deodar (Himalayan cedar)"},{"label":"Heights","value":"Houses 2-3 storeys; temples up to 7"}],"regions":["South Asia"],"aliases":["kath-khuni","kath kuni","kath-kona","kath-ki-kanni"],"related":["natural-slate","stone-slate","wood-shingle","earthquake-roofing","roofing-in-india","roofing-in-nepal","gable-roof"],"company":null,"sources":[{"title":"Kath kuni architecture","url":"https://en.wikipedia.org/wiki/Kath_kuni_architecture","publisher":"Wikipedia"},{"title":"The Himalayan Vernacular: Kath-Khuni Architecture","url":"https://www.sahapedia.org/the-himalayan-vernacular-kath-khuni-architecture","publisher":"Sahapedia"}],"country":null},{"slug":"kayabuki","title":"Kayabuki","category":"world-roofing","type":"term","summary":"Kayabuki is Japanese grass thatch, usually miscanthus or reed, used on farmhouses, shrines and the steep gassho-zukuri roofs of Shirakawa-go.","body":"*Kayabuki* (茅葺) is the Japanese term for roofs thatched with grasses (*kaya*), most often miscanthus (*susuki*) or reed. For most of Japanese history it was the ordinary roof of rural houses, and it survives today on preserved farmhouses, in heritage villages and on some of the country's most sacred shrines.\n\n## Materials and form\n\nThatch was made mainly from miscanthus; where it was hard to obtain, builders used wooden shingles instead. Farmhouses (*nōka*) were most often hipped (*yosemune*), with a thick thatch sloping on all four sides, while more elaborate houses combined thatched and shingled sections in *irimoya* (hip-and-gable) form. Steep pitches shed rain and snow. Along the ridge, crossed timbers (*umanori*) or bundles of reed finished the thatch and could indicate a family's standing in the village.\n\n## Regional forms\n\n- **Gasshō-zukuri** - the very steep \"praying hands\" roofs of Shirakawa-go and Gokayama, an enlarged form of the *sasu* rafter structure. Their large attics were used for rearing silkworms. The villages were inscribed as a UNESCO World Heritage site in 1995.\n- **Shrine thatch** - the main halls of Ise Grand Shrine are roofed with thatched reed in the ancient *shinmei-zukuri* style and are rebuilt every 20 years; the 62nd rebuilding was completed in 2013, and the first is recorded in 692.\n\n## History\n\nPrehistoric pit dwellings in Japan were roofed with grass, and thatch remained the common rural roof through the Edo period, when distinctive farmhouse types matured. In towns, thatch gave way to clay tile for fire protection, and in the 20th century most thatched houses were re-roofed or replaced.\n\n## Heritage and maintenance\n\nThatch needs regular renewal and community labour. In 2020 UNESCO inscribed Japan's traditional skills for the conservation of wooden architecture, which include both **thatching** and the **harvesting of plants for thatch**, as intangible cultural heritage.\n\n## See also\n\nSimilar grass-thatch traditions in the region include Korean *choga* (rice-straw thatch).","key_facts":[{"label":"Material","value":"Miscanthus (susuki), reed"},{"label":"Typical farmhouse form","value":"Yosemune (hipped)"},{"label":"Best-known form","value":"Gasshō-zukuri, Shirakawa-go"},{"label":"Shrine use","value":"Ise Grand Shrine, rebuilt every 20 years"},{"label":"UNESCO","value":"Thatching skills inscribed 2020"}],"regions":["East Asia"],"aliases":["kaya-buki","Japanese thatch","kaya thatch"],"related":["gassho-zukuri","thatch","water-reed-thatch","hiwadabuki","kokerabuki","roofing-in-japan","choga","prehistoric-shelters-and-early-thatch"],"company":null,"sources":[{"title":"Minka","url":"https://en.wikipedia.org/wiki/Minka","publisher":"Wikipedia"},{"title":"Ise Grand Shrine","url":"https://en.wikipedia.org/wiki/Ise_Grand_Shrine","publisher":"Wikipedia"},{"title":"Shirakawa-go","url":"https://en.wikipedia.org/wiki/Shirakawa-go","publisher":"Wikipedia"},{"title":"Historic Villages of Shirakawa-go and Gokayama","url":"https://whc.unesco.org/en/list/734","publisher":"UNESCO World Heritage Centre"},{"title":"UNESCO Intangible Cultural Heritage of Humanity in Japan","url":"https://www.nippon.com/en/features/h00347/","publisher":"Nippon.com"},{"title":"Japanese architecture","url":"https://en.wikipedia.org/wiki/Japanese_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"kee-roofing-membrane","title":"KEE Roofing Membrane","category":"low-slope-systems","type":"term","summary":"Single-ply membrane based on ketone ethylene ester, a high-molecular-weight polymer that keeps PVC flexible without migrating plasticisers.","body":"KEE (ketone ethylene ester) membranes are thermoplastic single-ply roof sheets in which a high-molecular-weight KEE polymer acts as a permanent flexibiliser for PVC. The best-known KEE modifier was DuPont's Elvaloy. Because KEE and PVC are fully miscible and both have high molecular weights, the KEE does not migrate out of the sheet the way liquid plasticisers can. PVC in turn adds strength, abrasion resistance and flame retardancy.\n\n## History\n\nThe technology traces back to 1974, when a geomembrane using a KEE modifier was introduced for environmental containment. In the early 1980s roofing products based on it were called EIP (ethylene interpolymer), a term later recognised in the NRCA low-slope guide. An ASTM subcommittee for the product formed in 1987, and ASTM D6754, the standard specification for ketone ethylene ester based sheet roofing, was issued in 2002 and later revised.\n\n## Standard and terminology\n\nASTM D6754 assumes KEE is the primary polymer in the membrane. Many products sold as \"PVC-KEE\" or \"KEE-enhanced PVC\" contain only part KEE and are tested to the PVC standard, ASTM D4434, which requires PVC to exceed 50% of polymer content. Specifiers therefore check which standard a product meets.\n\n## Properties and uses\n\nKEE membranes are hot-air fused like PVC, without torches or adhesives at seams, and are valued for chemical resistance and flexibility retained with age. Reported installations include mechanically fastened and adhered roofs and a large roof beneath a garden deck.\n\n## Naming in the market\n\nTerms such as EIP, KEE, PVC-KEE and KEE-enhanced PVC are used for overlapping products. Some PVC membranes are also described by the type of plasticiser chemistry they use, such as CPA, EIP or NBP, so data sheets and the governing ASTM standard are the reliable guide to what a membrane contains.","key_facts":[{"label":"Polymer","value":"Ketone ethylene ester (e.g., Elvaloy)"},{"label":"Origins","value":"1974 geomembrane; EIP roofing early 1980s"},{"label":"US standard","value":"ASTM D6754 (2002)"},{"label":"Seaming","value":"Hot-air welding"}],"regions":["North America","Global"],"aliases":["KEE","EIP membrane","PVC-KEE","ketone ethylene ester"],"related":["pvc-roofing","single-ply-roofing","hot-air-welding"],"company":null,"sources":[{"title":"Sustaining a KEE standard for roofing membranes","url":"https://www.constructioncanada.net/sustaining-a-kee-standard-for-roofing-membranes/","publisher":"Construction Canada"},{"title":"The ABCs of PVC Roof Membranes","url":"https://usa.sika.com/dms/getdocument.get/88a0c83a-9151-4100-84d6-dccadfebd4aa/the-abcs-of-pvc-roof-membranes.pdf","publisher":"Sika USA"}],"country":null},{"slug":"kerala-sloping-roof","title":"Kerala Sloping Roof","type":"article","summary":"The long, steep, deep-eaved timber roofs of traditional Kerala architecture in south-west India, shaped by heavy monsoon rain.","body":"Traditional buildings in Kerala, on the south-west coast of India, are recognisable by their roofs: long, steep slopes with deep projecting eaves that make the buildings look low and broad. The form is a response to one of the wettest climates in India, where the south-west monsoon brings intense rain for months each year, combined with strong sun for the rest of the year.\n\n## Structure\n\nKerala roofs are carried on timber. The roof frame rests on wooden pillars and wall plates, and carpentry was guided by an indigenous body of knowledge known as *Thachu Shastra*, the science of carpentry, which treated timber with great care. Laterite stone was widely used for walls, but the roof itself was a timber structure.\n\nKey features include:\n\n- **Steep pitch** to move water off quickly.\n- **Projecting eaves** that keep rain and sun off the walls.\n- **Gable windows** (*mukhappu*) at the ends of the roof, which ventilate the roof space when it is used as living or storage area.\n- **Inward-sloping roofs** around the central courtyard of the *nalukettu* house type, where four halls surround an open court that admits rain and light.\n\n## Coverings\n\nMost buildings were originally thatched with palm leaves, while clay tiles were mostly reserved for palaces and temples. During the British period, Mangalore-pattern interlocking tiles replaced older pan tiles and much of the thatch, and they became the typical covering of Kerala houses through the 20th century. Temple roofs sometimes carry copper sheet and copper finials.\n\n## Landmark example\n\nPadmanabhapuram Palace, built in timber with sloping roofs, granite and rosewood and teak woodwork, is often described as the largest wooden palace in the world and is a major example of the style.\n\n## Relevance today\n\nThe principles of the Kerala roof, a steep pitch, generous overhangs and a ventilated roof space, remain directly relevant to building in any heavy-rainfall tropical climate, whatever covering is used.","key_facts":[{"label":"Region","value":"Kerala, south-west India"},{"label":"Climate driver","value":"South-west monsoon rainfall"},{"label":"Structure","value":"Timber frame on pillars and wall plates"},{"label":"Coverings","value":"Palm thatch, later Mangalore tiles"},{"label":"Notable example","value":"Padmanabhapuram Palace"}],"regions":["South Asia"],"aliases":["Nalukettu roof","Kerala roof"],"related":["mangalore-tile","roofing-in-india","eaves","thatch"],"sources":[{"title":"Architecture of Kerala","url":"https://en.wikipedia.org/wiki/Architecture_of_Kerala","publisher":"Wikipedia"},{"title":"Mangalore tiles","url":"https://en.wikipedia.org/wiki/Mangalore_tiles","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"kershef","title":"Kershef","category":"world-roofing","type":"term","summary":"Building material of Egypt's Siwa Oasis made of salt rock and mud, used with palm-trunk roofs in the old fortress-town of Shali.","body":"Kershef (also karshef) is the traditional building material of Siwa Oasis in Egypt's Western Desert: lumps of hardened salt from the edges of the oasis's salt lakes, bound with mud. It was used to build Shali, the fortified old town of Siwa, whose houses were roofed with palm trunks.\n\n## Material\n\nThe salt forms as a crust on the shores of Siwa's lakes. Builders mixed it with local silt as a binder and built thick walls of salt and mud, with local silts and oxides used for decoration. The material suits a place where it almost never rains, but it is vulnerable to water: salt, mud and plaster resist weather and erosion poorly, and many of Shali's buildings gradually fell into ruin once they were no longer maintained.\n\n## Roofs\n\nShali's roofs were built of palm trunks, with palm wood also used for ceilings. Siwan builders soaked palm wood in salt-lake water to remove the sap that attracts biting insects. Olive wood was used for reinforcement, doors and window frames.\n\n## Shali\n\nShali is dated to about 1203 AD (600 AH). A restoration and revival project, completed in 2020, was carried out by EQI with the Egyptian Ministry of Tourism and Antiquities as client. It restored kershef buildings as a non-residential zone for small Siwan businesses and added new community facilities.\n\n## Significance\n\nKershef is one of very few vernacular building materials based on salt. Its survival depends on the oasis's extreme aridity, and it shows how desert builders combined whatever local materials were available, salt, mud and palm, into a complete wall-and-roof system.","key_facts":[{"label":"Composition","value":"Hardened salt rock bound with mud"},{"label":"Roof structure","value":"Palm trunks; salt-treated palm-wood ceilings"},{"label":"Main site","value":"Shali, Siwa Oasis, Egypt (c. 1203 AD)"},{"label":"Restoration","value":"Shali project completed 2020"}],"regions":["Africa","Middle East"],"aliases":["karshef","kershif","Siwa salt architecture"],"related":["roofing-in-egypt","mud-roof","flat-roof","roofing-in-libya","old-town-of-ghadames"],"company":null,"sources":[{"title":"Restoration and Revival of the Shali Fortress","url":"https://next.archnet.org/sites/21598","publisher":"Archnet"},{"title":"Shali Village in Siwa Oasis","url":"https://iwh.icesco.org/shali-village-in-siwa-oasis/","publisher":"ICESCO Islamic World Heritage"}],"country":null},{"slug":"khmer-corbel-vault","title":"Khmer Corbel Vault","category":"history","type":"article","summary":"The stepped stone and brick vaulting, without a true arch, used to roof the temples and galleries of Angkor in Cambodia from the 9th century.","body":"Khmer corbel vaulting is the method used by the builders of the Angkorian empire (9th-15th centuries, in present-day Cambodia and neighbouring countries) to roof stone and brick temples without a true arch. Each course of masonry projects a little further inward than the one below, until the two sides meet at the top and can be closed with a capstone.\n\n## How it works\n\nIn a true arch, wedge-shaped stones push sideways against each other and transfer load around a curve. In a corbel vault the stones are laid flat; each is held in place by the weight of the masonry above its inner end. The result looks like a pointed or stepped vault from inside, but it is structurally a pair of cantilevers. Khmer builders used the same principle for doorways, passages, galleries and the hollow interiors of towers, and used lintels for other openings.\n\n## Materials\n\n- **Brick** in the earliest Angkorian temples, such as Preah Ko, Lolei and Bakong (dedicated 881).\n- **Sandstone** from the Kulen hills, at first only for door frames and details; Ta Keo, in the 10th century, was the first temple built almost entirely of sandstone.\n- **Laterite** for foundations and concealed parts.\n\n## Limitations\n\nCorbelling is weaker than the true arch and limits how wide a stone-roofed space can be. Khmer galleries are therefore long and narrow. Galleries developed in the 10th century from hallways around the central sanctuary; in the Angkor Wat period (first half of the 12th century) half-galleries were added along one side to buttress the structure.\n\nCorbelled roofs are also prone to collapse once maintenance stops, a central conservation problem at Angkor today. Where a wider room was needed, builders often topped stone walls with a light timber roof instead. The late 12th-century \"halls of dancers\" at Ta Prohm, Preah Khan and Banteay Kdei had such perishable roofs; only their walls survive.\n\n## Timber roofs beside the stone\n\nMost Angkorian buildings were timber and have vanished. A 13th-century Chinese visitor described palace buildings with lead-tiled roofs, and reliefs at the Bayon and Banteay Chhmar show gabled and double-tiered timber roofs. These forms continue in the tiled pagoda and palace roofs of modern Cambodia.","key_facts":[{"label":"Period","value":"9th-15th centuries (Angkorian)"},{"label":"Materials","value":"Brick, Kulen sandstone, laterite"},{"label":"Principle","value":"Overlapping courses; no true arch"},{"label":"Main weakness","value":"Narrow spans; collapse when neglected"}],"regions":["Southeast Asia"],"aliases":["corbelled vault Angkor","Khmer corbelling","false arch Angkor"],"related":["roofing-in-cambodia","barrel-vault-roof","roofing-in-thailand","roofing-in-laos"],"company":null,"sources":[{"title":"Khmer architecture","url":"https://en.wikipedia.org/wiki/Khmer_architecture","publisher":"Wikipedia"},{"title":"CSES housing: occupied dwellings by kind of roof materials and geographical domain, 2004 and 2007-2013","url":"https://nis.gov.kh/nis/CSES/Data/CSES_2013/CSES_Housing_files/sheet001.htm","publisher":"National Institute of Statistics, Cambodia"}],"country":null},{"slug":"kickout-flashing","title":"Kickout Flashing (Diverter)","category":"components","type":"term","summary":"Kickout flashing is a bent piece of flashing at the bottom of a roof-to-wall junction that turns water away from the wall and into the gutter.","body":"A kickout flashing, also called a diverter or kick-out, is installed where the lower edge of a roof meets a wall that continues down past the eaves, for example where a garage roof ends against the side of a two-storey house. Without it, water flowing down the step flashing reaches the end of the roof and runs straight down the face of the wall, often behind the cladding, causing hidden rot and mould.\n\n## How it works\n\nThe kickout is effectively the bottom piece of step flashing with an angled lip that projects out from the wall, deflecting water onto the roof edge and into the gutter. US Department of Energy guidance describes it as directing rainwater off the eave and into the gutter, away from the wall.\n\n## Code status\n\nThe US International Residential Code requires flashing at roof-wall intersections, and section R903.2.1 addresses kickout (diverter) flashing where a roof meets a wall at the eaves. Building departments in jurisdictions that adopt the IRC publish guidance on the detail.\n\n## Installation guidance\n\nAccording to the Building America Solution Center:\n\n- Prefabricated seamless, non-corrosive diverters are preferred over site-bent pieces, which can leak at seams.\n- The diverter is installed as the first piece of step flashing, flat on the roof and flush with the sidewall.\n- It is fastened to the roof deck and starter course, not to the sidewall.\n- The first shingle and next step flashing lap at least 4 in (102 mm) over the diverter.\n- The wall's water-resistive barrier is lapped over the top of the diverter so water drains outward.\n\n## Retrofitting\n\nKickouts are frequently missing on older houses, and staining or rot on the wall below the end of a roof is a typical sign. Adding one usually means removing some cladding to integrate it with the wall's drainage plane.","key_facts":[{"label":"Location","value":"Bottom of roof-sidewall junction"},{"label":"US code reference","value":"IRC R903.2.1"},{"label":"Lap over diverter","value":"At least 4 in (102 mm)"}],"regions":["North America"],"aliases":["kick-out flashing","diverter flashing","kickout"],"related":["step-flashing","rain-gutter","roof-flashing","eaves"],"company":null,"sources":[{"title":"Step and Kick-Out Flashing at Roof-Wall Intersections","url":"https://basc.pnnl.gov/resource-guides/step-and-kick-out-flashing-roof-wall-intersections","publisher":"Building America Solution Center (PNNL / US DOE)"},{"title":"Inspecting Step and Kick-Out Flashing","url":"https://nachi.org/inspecting-step-kick-out-flashing.htm","publisher":"InterNACHI"},{"title":"Flashing (weatherproofing)","url":"https://en.wikipedia.org/wiki/Flashing_(weatherproofing)","publisher":"Wikipedia"},{"title":"Flashing","url":"https://hopkinsmn.com/616/Flashing","publisher":"City of Hopkins, Minnesota"}],"country":null},{"slug":"king-post-truss","title":"King Post Truss","category":"components","type":"term","summary":"A king post truss is a simple triangular roof frame with a single central vertical post rising from the tie beam to the apex.","body":"A king post truss is a triangular frame made of two sloping principal rafters, a horizontal tie beam across the bottom, and a single vertical post (the king post) running from the centre of the tie beam up to the apex. It is one of the simplest truss forms and has been used for centuries in timber roofs and bridges.\n\n## How it works\n\nThe rafters push down and outward; the tie beam resists the outward spread in tension, so the frame does not push the walls apart. The king post connects the apex to the middle of the tie beam. In many designs the post actually hangs from the apex and helps hold the tie beam up, so it works in tension rather than as a prop. Diagonal struts are often added from the foot of the king post up to the rafters to shorten their unsupported length.\n\nIn historic British usage the king post is described as the vertical timber supporting the ridge. Historians distinguish it from a crown post, which rises from the tie beam only as far as a collar and carries a collar purlin rather than the ridge.\n\n## Use today\n\nThe king post form remains common in short-span modern trusses, including small prefabricated timber trusses and garages, and as an exposed decorative feature in timber-framed buildings, porches and gable ends. For longer spans, builders move to queen post trusses or more complex web arrangements.\n\n## Related terms\n\n- **Queen post truss:** two vertical posts instead of one, with a straining beam between them.\n- **Crown post:** a central post from tie beam to collar, typical of medieval south-east England.","key_facts":[{"label":"Members","value":"Two rafters, tie beam, central king post"},{"label":"Typical use","value":"Short spans"},{"label":"Related forms","value":"Queen post, crown post"}],"regions":["Global","Europe","North America"],"aliases":["kingpost truss","king-post roof"],"related":["queen-post-truss","roof-truss","rafter","collar-tie","hammerbeam-roof"],"company":null,"sources":[{"title":"King post","url":"https://en.wikipedia.org/wiki/King_post","publisher":"Wikipedia"},{"title":"King post","url":"https://treeterms.co.uk/definitions/king-post/","publisher":"Tree Terms"},{"title":"Roof glossary","url":"https://www.mkheritage.org.uk/wdahs/Thornton/docs/roofglossary.html","publisher":"Milton Keynes Heritage Association"}],"country":null},{"slug":"kingspan","title":"Kingspan Group","category":"manufacturers","type":"company","summary":"Kingspan is an Irish building-envelope group founded in 1965, known for insulated metal roof and wall panels and, since 2022, a roofing and waterproofing division.","body":"Kingspan Group is an Irish manufacturer of insulated building envelope products, headquartered in Kingscourt, County Cavan. It was founded in 1965 by Eugene Murtagh, reportedly starting in a yard behind his family's pub, and is led by his son Gene Murtagh as chief executive. Kingspan trades in more than 80 countries and operates over 270 sites. Its primary share listing is on Euronext Dublin; its London listing was cancelled in 2023.\n\n## Divisions\n\nKingspan reports several divisions: Insulated Panels (its largest, at roughly half of turnover), Insulation boards, Light, Air and Water, Data Solutions, and Roofing and Waterproofing.\n\n## Roofing activities\n\nInsulated metal panels for roofs and walls of industrial, commercial and agricultural buildings are Kingspan's best-known product. These panels bond a foam insulation core between two steel skins and are installed in one pass; product lines include QuadCore panels and, from 2025, PowerPanel, a roof panel supplied with factory-fitted solar photovoltaic modules.\n\nIn 2022 Kingspan built a dedicated Roofing and Waterproofing division around its acquisition of the waterproofing business Ondura (about EUR 516 million). It added the Belgian bituminous membrane maker Derbigum in 2022 and CaPlast in 2023, took a controlling stake in Nordic Waterproofing in 2024 (later raised to about 63 percent), bought 90 percent of the US PVC membrane maker IB Roof Systems in 2024, and acquired the UK roofing and cladding firm Coverworld in 2025.\n\n## Other acquisitions\n\nEarlier milestones include the purchase of CRH's European insulation business in 2011, parts of ThyssenKrupp's construction business in 2012, and the Belgian panel maker Joris Ide in 2015.","key_facts":[{"label":"Founded","value":"1965"},{"label":"Founder","value":"Eugene Murtagh"},{"label":"Headquarters","value":"Kingscourt, County Cavan, Ireland"},{"label":"Listing","value":"Euronext Dublin (KRX)"},{"label":"Roofing acquisitions","value":"Ondura, Derbigum, Nordic Waterproofing, IB Roof Systems"}],"regions":["Europe","North America","Global"],"aliases":["Kingspan","Kingspan plc"],"related":["nordic-waterproofing","pvc-roofing"],"company":{"founded":"1965","headquarters":"Kingscourt, County Cavan, Ireland","website":"https://www.kingspan.com","known_for":["Insulated metal panels","Rigid insulation boards","Roofing and waterproofing (Ondura, Derbigum)"]},"sources":[{"title":"Kingspan Group","url":"https://en.wikipedia.org/wiki/Kingspan_Group","publisher":"Wikipedia"},{"title":"Kingspan","url":"https://www.kingspan.com","publisher":"Kingspan Group"}],"country":null},{"slug":"kokerabuki","title":"Kokerabuki","category":"world-roofing","type":"term","summary":"Kokerabuki is a Japanese roof of very thin split cypress shingles, a few millimetres thick, fixed in close courses with bamboo nails.","body":"*Kokerabuki* (柿葺, also 杮葺) is a traditional Japanese roof covering of very thin wooden shingles. The shingles, called *kokera*, are split rather than sawn, and are laid in many closely spaced courses to form a light, finely textured roof. It is used on temple halls, pagodas and pavilions, and is one of the techniques used to roof Kyoto's Golden and Silver Pavilions.\n\n## Material and size\n\nKokera are traditionally split from Japanese cypress (*hinoki*), though other woods such as cedar are sometimes used. A typical shingle is about 3-5 mm (0.1-0.2 in) thick, 9-15 cm (3.5-6 in) wide and about 30 cm (12 in) long. They are fixed with bamboo nails.\n\n## Technique\n\nThe shingles are laid in tight, overlapping courses so that only a small part of each is exposed, building up a roof several layers thick. The thinness of the shingles allows them to follow curved roof surfaces and sweeping eaves.\n\n## Relationship to other wooden roofs\n\nJapanese builders used a family of wooden roof coverings. Thin shingles were common on houses in medieval Kyoto, where they were often held down with stones. *Hiwadabuki*, layered cypress bark, uses a similar nailing method but a different material. Where thatch was hard to obtain, minka builders also used shingles instead.\n\n## Heritage\n\nWooden-shingle roofing, together with cypress-bark roofing, is among the 17 traditional skills inscribed by UNESCO in 2020 as \"Traditional skills, techniques and knowledge for the conservation and transmission of wooden architecture in Japan\". The production of wooden roofing materials is listed as a separate skill.\n\n## Examples\n\n- **Kinkaku-ji and Ginkaku-ji**, Kyoto - very thin split-wood shingles fixed with bamboo nails.\n- **Anraku-ji octagonal three-storey pagoda**, Nagano - used by the JAANUS dictionary to illustrate the entry.","key_facts":[{"label":"Material","value":"Split hinoki cypress, sometimes cedar"},{"label":"Shingle thickness","value":"About 3-5 mm (0.1-0.2 in)"},{"label":"Shingle size","value":"9-15 cm wide, about 30 cm long"},{"label":"Fixing","value":"Bamboo nails"},{"label":"Examples","value":"Kinkaku-ji, Ginkaku-ji"}],"regions":["East Asia"],"aliases":["kokera-buki","kokera shingle roof","Japanese wood shingle roof"],"related":["hiwadabuki","kayabuki","wood-shingle","roofing-in-japan","pagoda-roof"],"company":null,"sources":[{"title":"kokerabuki","url":"https://projects.mcah.columbia.edu/jaanus/record/kokerabuki","publisher":"JAANUS (Japanese Architecture and Art Net Users System)"},{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Minka","url":"https://en.wikipedia.org/wiki/Minka","publisher":"Wikipedia"},{"title":"UNESCO Intangible Cultural Heritage of Humanity in Japan","url":"https://www.nippon.com/en/features/h00347/","publisher":"Nippon.com"}],"country":null},{"slug":"korean-asbestos-slate-roofs","title":"Korean Asbestos Slate Roofs","category":"problems-maintenance","type":"article","summary":"Asbestos-cement slate roofs spread across rural South Korea from the 1970s; since 2011 local governments subsidise their removal and replacement.","body":"In South Korean usage, rural \"slate\" (슬레이트) roofs are usually **asbestos-cement sheet** rather than natural stone: a cheap, light roofing material that spread rapidly across the countryside from the 1970s. It replaced much of the rice-straw thatch (*choga*) of rural houses and was used on warehouses and livestock sheds. Decades later, ageing slate roofs are treated as a health hazard, and local governments run subsidised programmes to remove them.\n\n## Origins\n\nKorea's traditional rural roof was rice-straw thatch, which needed renewing every one to three years. The decline of thatch began in the 1960s, and the New Village Movement (*Saemaul Undong*), launched in 1970, promoted modern roofs across the countryside. By the 1980s thatched roofs had largely been replaced by cement and slate roofs. Asbestos slate was widely used for roofs and ceilings from the 1970s.\n\n## Health concern\n\nKorean asbestos slate contains roughly 10-15 per cent asbestos, a Class 1 carcinogen. As the sheets weather, crack or are broken during repairs, fibres can be released, and long-term exposure is linked to lung cancer and other serious diseases.\n\n## Removal programmes\n\nSince 2011, local governments have run slate removal support projects. Typical schemes cover houses, warehouses and livestock sheds, with recent extensions to facilities for older people and children. In Gwangju, for example, the 2025 budget of 1.328 billion won was intended for 360 buildings; ordinary households could receive 3.52-7 million won toward removal of slate from a house, priority households such as basic-livelihood recipients received full support, non-residential buildings were covered for up to 200 m² (2,150 sq ft) of slate, and priority households could receive 3.14 million won for a new roof. Gwangju had removed or supported 4,462 slate buildings since 2011. Similar schemes run in rural counties such as Yeonggwang.\n\n## Replacement roofs\n\nRemoval grants and re-roofing grants are separate. In Gwangju's scheme, roof improvement funding applies to houses only and is reserved for priority households; other owners receive support for removal and arrange the new roof themselves. Tenants may apply with the owner's consent.\n\n## Context\n\nAsbestos-cement roofing was used worldwide in the 20th century and is now banned or restricted in many countries. Korea's case is notable for how quickly slate spread through a single national rural modernisation drive and for the scale of the public removal effort that followed.","key_facts":[{"label":"Material","value":"Asbestos-cement sheet"},{"label":"Asbestos content","value":"About 10-15%"},{"label":"Widespread from","value":"1970s"},{"label":"Removal subsidies","value":"Since 2011, run by local governments"},{"label":"Example","value":"Gwangju: 4,462 buildings by 2025"}],"regions":["East Asia"],"aliases":["Korean slate roofs","asbestos slate (Korea)","seokmyeon slate"],"related":["asbestos-cement-roofing","history-of-asbestos-cement-roofing","corrugated-fibre-cement-sheet","choga","roofing-in-south-korea","roofing-waste"],"company":null,"sources":[{"title":"Gwangju City urges removal of carcinogenic asbestos slate","url":"https://www.asiae.co.kr/en/article/2025032410080700119","publisher":"Asia Economy"},{"title":"Yeonggwang-gun promotes slate roof removal support project","url":"https://www.asiae.co.kr/en/article/2021011311345929285","publisher":"Asia Economy"},{"title":"Choga (architecture)","url":"https://en.wikipedia.org/wiki/Choga_(architecture)","publisher":"Wikipedia"},{"title":"Saemaul Undong","url":"https://en.wikipedia.org/wiki/Saemaul_Undong","publisher":"Wikipedia"}],"country":null},{"regions":["Europe"],"company":null,"slug":"kozolec","title":"Kozolec (Slovenian Hayrack)","category":"world-roofing","type":"term","summary":"A kozolec is a permanent, usually roofed timber hayrack used to dry hay and maize, regarded as a symbol of Slovenian vernacular architecture.","aliases":["Slovenian hayrack","toplar","kozuc","Harpfe"],"body":"A **kozolec** (plural *kozolci*) is a freestanding, permanent drying rack, usually of timber, on which farmers dry hay, other animal fodder and field maize. It is found chiefly in Slovenia, where it is regarded as a distinctive form of vernacular architecture and a marker of national identity, and many are carefully designed and handcrafted.\n\nSimilar structures exist in neighbouring Friuli in Italy and in southern Carinthia and East Tyrol in Austria, but around 80% of all such hayracks are in Slovenia. Within Slovenia they are found everywhere except Prekmurje, eastern Styria and the Slovenian Littoral.\n\n## Roofs\n\nThe roof protects the drying crop from rain. Roofs were originally thatched with straw, later covered with wood, and more recently with metal tiles. Roofing ranges from the small protective roof over a single straight rack to a full roof spanning two racks and the space between them.\n\n## Types\n\nMore than thirty types can be distinguished. Slovenian terms include:\n\n- *enojni stegnjeni kozolec* - single straight-line hayrack\n- *stegnjeni kozolec s plaščem* - single hayrack with a catslide roof\n- *dvojni stegnjeni kozolec* - double straight-line hayrack\n- *dvojni vezani kozolec* - roofed double hayrack\n- *toplar* or *doplar* - roofed double hayrack with two struts, from Austrian German *Doppler*, \"double structure\"\n- *toplar z repom* - roofed double hayrack with an extension\n- *kozolec s hišo* - roofed double hayrack with a shed\n- *kozolec na kozla*, *kozolec na psa* - split-level double hayrack\n\nThe word *kozolec*, and the colloquial *kozuc*, probably derive from *kozel*, \"goat\". In Upper Carniola and around Bohinj the word *stog* is also used. German names are *Harpfe* or *Köse*.\n\n## Heritage\n\nHayracks are treated as cultural heritage in regional and local plans in Slovenia, Austria, Italy and Germany, and about 250 are registered with the Slovenian Ethnographic Museum. More than 650 have been counted in the Mirna Valley alone. The Municipality of Šentrupert built the open-air museum *Dežela kozolcev* (Land of Hayracks) between 2010 and 2013; it holds 19 drying structures, including 17 hayracks, the oldest dating from 1795. The largest hayrack in Slovenia is the Simončič Hayrack. Three countries have been reported as seeking UNESCO recognition for hayracks.","key_facts":[{"label":"Function","value":"Drying hay, fodder and maize"},{"label":"Share in Slovenia","value":"About 80% of all such hayracks"},{"label":"Roofing","value":"Straw, then wood, more recently metal tiles"},{"label":"Types","value":"More than 30"}],"related":["roofing-in-slovenia","thatch","wood-shingle","saltbox-roof","roofing-in-austria","roofing-in-italy"],"sources":[{"title":"Kozolec","url":"https://en.wikipedia.org/wiki/Kozolec","publisher":"Wikipedia"},{"title":"Past, Present and Future of Hay-making Structures in Europe (Sustainability, 2019)","url":"https://www.mdpi.com/2071-1050/11/20/5581","publisher":"MDPI Sustainability"},{"title":"Three countries seek to get hayracks onto UNESCO list","url":"https://english.sta.si/2364484/three-countries-seek-to-get-hayracks-onto-unesco-list","publisher":"Slovenian Press Agency (STA)"}],"country":null},{"slug":"krio-board-house","title":"Krio Board House","type":"term","summary":"Timber house of Freetown's Krio community in Sierra Leone, traced to 18th-century settlers from North America; now rare and often roofed in metal.","body":"The board house (*bod os* in Krio) is the traditional timber dwelling of the Krio community of Freetown, Sierra Leone. Built of sawn planks, often painted in bright colours, with shuttered windows and porches, board houses once lined much of the city. Today they are a threatened heritage type.\n\n## Origins\n\nThe Krio descend from free and freed people of African descent who settled in Sierra Leone in the late 18th and early 19th centuries. They included Black Loyalists who had sided with the British in the American Revolutionary War and were evacuated to Nova Scotia before a group sailed to Sierra Leone in 1792, as well as Jamaican Maroons and Africans rescued from illegal slave ships. Researchers such as the documentary producer Isa Blyden link the single-storey board house to cabin-like houses of the American eastern seaboard, and observers often compare surviving examples to houses of colonial South Carolina.\n\n## Construction\n\nThe houses are framed and clad in timber; some of the wood reportedly arrived in Sierra Leone as ships' ballast. Many have two storeys, sometimes with a garret in the roof. Over time, painted metal has been applied to walls in some examples, and many roofs and walls have been patched with sheets of metal to keep out the heavy Freetown rains.\n\n## Decline\n\nThe style has been in decline for decades as stone and concrete houses became more fashionable. Wooden houses burned easily during the 1991-2002 civil war, when hundreds were destroyed, and many others have been demolished for concrete buildings or left to decay when owners moved abroad. Surviving examples are concentrated in Freetown neighbourhoods including Kroo Town (Kroo Tong), Congo Town, King Tom, Fourah Bay, Murray Town and Brookfields, and in Regent village.\n\n## Conservation\n\nThe Sierra Leone National Museum and heritage consultants have called for urgent conservation, including a heritage trust fund and incentives for owners, penalties for destroying board houses, and their inclusion in school and university curricula.\n\n## Related buildings\n\nOn the higher ground of Hill Station above Freetown, British colonial officials built large timber houses on metal stilts set into concrete piles, after research linking mosquitoes to malaria encouraged a move to higher ground in the early 20th century.","key_facts":[{"label":"Location","value":"Freetown, Sierra Leone"},{"label":"Community","value":"Krio"},{"label":"Structure","value":"Timber frame and plank cladding"},{"label":"Typical repairs","value":"Metal sheet patching of roofs and walls"},{"label":"Status","value":"Declining; conservation called for"}],"regions":["Africa"],"aliases":["bod os","Krio house","Freetown board house"],"related":["roofing-in-sierra-leone","roofing-in-liberia","corrugated-iron","roofing-in-west-africa"],"sources":[{"title":"Colonial-era wooden buildings decay in Sierra Leone","url":"https://www.nbcnews.com/news/world/colonial-era-wooden-buildings-decay-sierra-leone-flna751400","publisher":"NBC News / Reuters"},{"title":"Once influential, slave descendants in Sierra Leone face a less certain future","url":"https://csmonitor.com/World/Africa/2015/0908/Once-influential-slave-descendants-in-Sierra-Leone-face-a-less-certain-future","publisher":"Christian Science Monitor"},{"title":"The Enduring Legacy of Sierra Leone's Board Houses","url":"https://artsandculture.google.com/story/the-enduring-legacy-of-sierra-leone-39-s-board-houses-sierra-leone-national-museum/cgWB9MwhZFW9Gw?hl=en","publisher":"Sierra Leone National Museum / Google Arts & Culture"}],"company":null,"category":"world-roofing","country":null},{"regions":["Europe"],"company":null,"slug":"kulla-tower-house","title":"Kulla (Balkan Tower House)","category":"world-roofing","type":"term","summary":"A kulla is a fortified stone tower house of Albania, Kosovo and neighbouring Balkan lands, with thick walls, small openings and tall stone storeys.","aliases":["kullë","kula","odžak","Balkan tower house"],"body":"A **kulla** (Albanian *kullë*, Serbo-Croatian *kula*) is a fortified stone tower house found across the western Balkans, especially in northern Albania and the Dukagjini region of Kosovo, with related types in Montenegro, North Macedonia, Serbia and Bosnia and Herzegovina. The word comes from Arabic *qalʿa*, \"fort\", through Persian and Turkish.\n\n## Form\n\nKullas are usually square or rectangular towers of local stone, three or four storeys high (two or three in Kosovo). External walls can be up to 1 m (3.3 ft) thick at ground level, thinning towards the roof, and are pierced by narrow openings (*frëngji*) that admitted light and air and served as loopholes. The ground floor held storage and livestock, and the upper floors living quarters and rooms for receiving guests. In Kosovo, men lived in the kulla while women and children lived in an adjoining annex, the *çardak*, with separate entrances and stairs.\n\nThe thick stone walls also insulated against the continental climate, keeping interiors cool in summer and warm in winter.\n\n## Roofs\n\nFor the related Bosnian tower (*odžak* or *kula*), roofs were tented, that is pyramidal, and covered with wooden shingles or limestone slabs. In southern Albania, the tall stone houses of Gjirokastër, which UNESCO also describes as kullë, are roofed with flat dressed stones.\n\n## History\n\nFortified towers existed in Gjirokastër in the 13th century. The first Albanian kullas in the Dukagjini region were built in the 17th century, and most surviving Kosovar kullas date from the 18th and 19th centuries, with building continuing into the early 20th century. In Serbia, the Despot Stefan Tower in Belgrade dates from about 1405 and the Nenadović Tower in Valjevo from 1813. In the mountains of northern Albania, \"locked towers\" (*kulla ngujimi*), as at Theth, served as refuges for men during blood feuds (*gjakmarrja*).\n\n## Examples\n\n- Kosovo: Jashar Pasha's Tower (Gjakova), Haxhi Zeka's Tower (Peja), Mazrekaj Tower (Junik), Zahir Pajaziti's Tower (Orllan)\n- Albania: towers of Theth; tower houses of Gjirokastër and Berat\n- Montenegro: Ganić tower house, Rožaje\n## Sources and gaps\n\nDetailed descriptions of the roofs of Albanian and Kosovar kullas: published information is limited.","key_facts":[{"label":"Walls","value":"Stone, up to 1 m (3.3 ft) thick"},{"label":"Height","value":"2-4 storeys"},{"label":"Main period","value":"17th-early 20th centuries"},{"label":"Bosnian tower roofs","value":"Tented; wood shingle or limestone slab"}],"related":["roofing-in-albania","roofing-in-kosovo","roofing-in-montenegro","roofing-in-bosnia-and-herzegovina","roofing-in-serbia","gjirokaster-stone-roofs","stone-slate","wood-shingle"],"sources":[{"title":"Tower houses in the Balkans","url":"https://en.wikipedia.org/wiki/Tower_houses_in_the_Balkans","publisher":"Wikipedia"},{"title":"Historic Centres of Berat and Gjirokastra","url":"https://whc.unesco.org/en/list/569","publisher":"UNESCO World Heritage Centre"},{"title":"Gjirokastër","url":"https://en.wikipedia.org/wiki/Gjirokast%C3%ABr","publisher":"Wikipedia"}],"country":null},{"slug":"ladder-safety","title":"Ladder Safety for Roofing","category":"installation","type":"article","summary":"Ladder safety for roof access centres on the 4-to-1 angle rule, extending the ladder about 1 m (3 ft) above the roof edge and securing it top and bottom.","body":"Ladders are the most common way to reach a roof and a frequent source of serious falls. Rules for portable ladders are broadly similar across jurisdictions, and most roofing safety programmes teach the same core practices.\n\n## The 4-to-1 rule\n\nA straight or extension ladder should be set so that its base is one unit out from the wall for every four units of height to the top support. The US OSHA construction standard, 29 CFR 1926.1053, expresses this as a horizontal distance equal to one-quarter of the working length of the ladder, which gives an angle of about 75 degrees. Canadian industry guidance allows a horizontal-to-vertical ratio between 1/4 and 1/3.\n\n## Extension above the roof\n\nFor access to a roof, OSHA requires the side rails to extend at least **3 ft (0.9 m)** above the upper landing; where that is not possible, a secure grab rail must be provided. Canadian guidance specifies at least 900 mm (3 ft) above the landing or roof edge.\n\n## Securing\n\n- Set the base on firm, level footing with non-slip feet.\n- Tie off the top to the structure, and secure the bottom against slipping.\n- On extension ladders, overlap the sections by at least three rungs, or more if the manufacturer requires.\n- Do not set up or extend a ladder in doorways or driveways without barricades.\n\n## Use\n\n- Face the ladder when climbing, keep a firm handhold and do not carry loads that prevent holding on; hoists or ladder lifts are used to raise materials.\n- Do not stand on the top two steps of a stepladder.\n- Choose a ladder rated for the user, tools and materials.\n\n## Inspection and electrical hazards\n\nLadders are inspected before use and after any incident; defective ladders are tagged and taken out of service. Canadian guidance says aluminium ladders must not be used near overhead power lines, and OSHA requires non-conductive side rails where a ladder could contact energised equipment.\n\n## Roof ladders\n\nOn steep pitched roofs, separate **roof ladders** with hooks over the ridge, and **roof brackets** with planks, provide footing on the slope itself.","key_facts":[{"label":"Angle rule","value":"1 out for every 4 up (about 75 degrees)"},{"label":"Extension above landing","value":"At least 3 ft (0.9 m)"},{"label":"Extension ladder section overlap (Canada)","value":"At least 3 rungs"}],"regions":["Global"],"aliases":["4 to 1 ladder rule","ladder angle rule","extension ladder safety"],"related":["roofing-fall-protection","roof-brackets","personal-fall-arrest-system"],"company":null,"sources":[{"title":"OSHA Ladder Requirements: 29 CFR 1910.23 and 1926.1053 Explained","url":"https://wcsafety.com/blogs/reference/osha-ladder-requirements","publisher":"WC Safety"},{"title":"Canadian Roofing Reference Manual: 1.7.1 Ladders","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-1-safety/1-7-ladders-scaffolds-roof-jacks/1-7-1-ladders/","publisher":"Canadian Roofing Contractors Association"},{"title":"Roof work","url":"https://hse.gov.uk/construction/safetytopics/roofwork.htm","publisher":"Health and Safety Executive (UK)"}],"country":null},{"slug":"ladder-standoff","title":"Ladder Standoff and Roof Ladder Accessories","category":"tools-equipment","type":"term","summary":"Attachments that hold a ladder away from gutters and walls, extend its rails above the roof edge, or secure it, improving access to roofs.","body":"Many roof falls happen while getting on or off the roof at the top of a ladder. Ladder accessories reduce this risk by improving the ladder's position, stability and handhold at the transition from ladder to roof.\n\n## Types\n\n- **Standoffs (stabilisers)**: U-shaped or arm-shaped brackets clamped to the top of an extension ladder. They rest against the wall or roof rather than against the gutter, keeping the ladder from crushing gutters and spreading its load more widely. Some are designed to straddle a window or reach around an overhang.\n- **Ladder extensions and rail extenders**: devices that add handrail height above the roof edge so the worker has something to hold while stepping on and off.\n- **Top securing devices**: brackets, straps or hooks that tie the top of the ladder to the building to stop it sliding sideways.\n- **Ladder levellers** and **foot anchors** for uneven ground.\n- **Roof ladders (cat ladders)**: separate ladders with hooks or wheels that hook over the ridge and lie on the roof slope, widely used on tile and slate roofs in Europe to avoid walking on the covering.\n\n## US ladder rules (example)\n\nOSHA's construction ladder standard (29 CFR 1926.1053(b)(1)) requires that when a portable ladder is used to reach an upper landing such as a roof, its side rails extend at least 3 ft (0.9 m) above the landing. If that is not possible, the ladder must be secured at the top to a rigid support and a grab rail or similar device provided. OSHA has indicated that a properly engineered device securing the ladder top to a rafter end or gutter board can satisfy the securing requirement, while noting that it does not approve specific products.\n\n## Good practice\n\n- Set extension ladders at about a 4-to-1 angle. OSHA's construction rule (29 CFR 1926.1053(b)(5)(i)) puts the foot of a non-self-supporting ladder about one-quarter of the ladder's working length out from the top support.\n- Secure the ladder top and foot.\n- Keep three points of contact while climbing.\n- Avoid placing ladders against fragile gutters without a standoff.\n- Check for overhead power lines before raising metal or wet ladders.\n\nNational ladder standards and work-at-height regulations in other countries set similar but not identical requirements.","key_facts":[{"label":"US rail extension above landing","value":"At least 3 ft (0.9 m)"},{"label":"Standoff purpose","value":"Keeps ladder off gutters, spreads load"},{"label":"Ladder angle rule of thumb","value":"About 4 to 1"}],"regions":["Global","North America"],"aliases":["ladder stabilizer","ladder standoff","ladder extension","roof ladder"],"related":["personal-fall-arrest-system","roof-jacks","roofing-hoist","gutter-problems"],"company":null,"sources":[{"title":"Standard interpretation: ladder extension above landing","url":"https://www.osha.gov/laws-regs/standardinterpretations/2004-02-26","publisher":"OSHA"},{"title":"Safe-T Ladder Extension System","url":"https://guardianfall.com/product/10800","publisher":"Guardian Fall Protection"},{"title":"Ladder extension system helps provide safe access to rooftops","url":"https://roofingmagazine.com/ladder-extension-system-helps-provide-safe-access-to-rooftops/","publisher":"Roofing Magazine"},{"title":"Reducing Falls While Installing Tile Roofs","url":"https://www.osha.gov/sites/default/files/publications/reducing-falls-installing-tile-roofs-factsheet.pdf","publisher":"OSHA"},{"title":"29 CFR § 1926.1053 - Ladders","url":"https://www.law.cornell.edu/cfr/text/29/1926.1053","publisher":"Legal Information Institute, Cornell Law School"}],"country":null},{"slug":"laeso-seaweed-roof","title":"Læsø Seaweed Roof","category":"world-roofing","type":"article","summary":"A thick roof of dried eelgrass laid over timber on the Danish island of Læsø, developed in the 17th century when salt boiling had stripped the island of trees.","body":"The seaweed roofs (*tangtag*) of Læsø, an island in the Kattegat between Denmark and Sweden, are among the most unusual roofs in Europe. Instead of straw or reed, islanders covered their houses with great mounds of dried eelgrass (*Zostera marina*), a marine flowering plant that washes up on the shore. The roofs are massive: up to 1.5 m (4.9 ft) thick and weighing 35-40 tonnes (34-39 long tons).\n\n## Origins\n\nLæsø's salt works consumed huge amounts of fuel, and by the 17th century the island had been largely deforested. Thatching reed was difficult to ship to the island and straw was too valuable as animal fodder, so islanders turned to eelgrass. The oldest surviving seaweed roofs date from the 1650s, and the last building in the tradition was built in the 1870s. Similar roofs once existed in Halland on the Swedish coast opposite Læsø, but none survive there.\n\n## Construction\n\nBuilding a seaweed roof was a collective task. Women harvested the eelgrass and did the roofing, while men, often away at sea as fishermen, gathered driftwood for the frame. Teams of 40-50 people, or up to 100, worked together. The eelgrass was laid in layers directly on the roof beams, often over sheaves of twisted seaweed, and built up into a very thick covering.\n\nThe material has several advantages. It insulates well, is air-permeable, resists rot and pests, and resists fire. A well-made seaweed roof can last up to about 300 years, according to the Danish foundation Realdania.\n\n## Decline\n\nSeaweed houses have almost disappeared over the last 75 years, partly because disease reduced local eelgrass beds and partly because the labour-intensive seaweed economy declined. Accounts of the numbers differ: one count gives about 230 seaweed-roofed buildings in the 1930s and 34 in 2014, while Realdania gives about 300 once and about 20 surviving with intact seaweed roofs.\n\n## Conservation\n\nRealdania By & Byg bought and restored Kaline's House in 2010, a small protected seaweed-roofed longhouse from 1865 on the meadows south of Østerby. A new seaweed-roofed house was built in 2012-2013 as part of a conservation project, and old roofs continue to be repaired with the traditional technique. Most seaweed houses are privately owned; a marked \"seaweed route\" lets visitors see two of them. The houses form part of the salt-production cultural landscape of Læsø, on Denmark's UNESCO Tentative List since 2023.\n\n## Significance\n\nThe Læsø roofs show how a roofing tradition can adapt to scarcity. Realdania describes the material as non-toxic and carbon-neutral, which has drawn interest from architects seeking low-carbon materials.","key_facts":[{"label":"Material","value":"Dried eelgrass (Zostera marina)"},{"label":"Thickness","value":"Up to 1.5 m (4.9 ft)"},{"label":"Weight","value":"35-40 tonnes per roof"},{"label":"Oldest surviving","value":"1650s"},{"label":"Lifespan","value":"Up to about 300 years"}],"regions":["Europe"],"aliases":["seaweed roof","tangtag","Læsø seaweed houses","eelgrass roof","tanghuse"],"related":["roofing-in-denmark","thatch","dutch-and-danish-reed-thatch","water-reed-thatch","roofing-in-sweden","thatch-maintenance"],"company":null,"sources":[{"title":"Seaweed roofs on Læsø","url":"https://en.wikipedia.org/wiki/Seaweed_roofs_on_L%C3%A6s%C3%B8","publisher":"Wikipedia"},{"title":"Seaweed houses on Læsø – Kaline's House","url":"https://realdaniabyogbyg.org/projects/seaweed-houses-on-laeso-kaline-s-house","publisher":"Realdania By & Byg"}],"country":null},{"slug":"lauze","title":"Lauze","category":"world-roofing","type":"term","summary":"A lauze is a flat stone slab of schist or limestone used as a heavy roof covering in the mountains and plateaux of southern and central France.","body":"A **lauze** is a flat slab of stone used to cover roofs and, in some places, to pave floors. Lauze roofs are characteristic of the Cévennes and Causses and neighbouring parts of the Massif Central such as the Cantal and Aveyron, and survive in other areas such as northern Isère, where they give villages their grey, heavy-looking roofscapes. They belong to the wider European family of stone roofs, alongside English stone slates and the *piode* of the southern Alps.\n\n## Rock types\n\nIn the département of Lozère, which has one of the best-documented lauze traditions, two families of stone are used:\n\n- **Schist lauzes** (*lauzes de schiste*), quarried in the Cévennes, Mont Lozère, Margeride, the Lot valley and parts of Aubrac and the Tarn valley. Their thickness follows the natural bands of the rock, and quarries such as Lachamp near Marvejols, Le Tournel in the upper Lot valley and Galta in the Cévennes each produced stone with its own hardness and colour.\n- **Limestone lauzes** (*lauzes calcaires*), used on the limestone plateaux of the Causses (Sauveterre, Méjean, Noir) and in the Tarn and Jonte gorges. These are split to their final thickness.\n\n## Laying\n\nSchist lauzes usually sit on a timber roof structure with boarding (*douelle* or *volige*). Traditionally each stone was fixed with a wooden peg driven into the boarding; today they are usually nailed. Courses overlap by about two-thirds, leaving a third exposed (the *pureau*), increased to three-quarters on the lowest pitches, and stones are graded from the largest at the eaves to the smallest at the ridge. The biggest slabs, over 60 cm (24 in), are kept for gutters and ridges.\n\nOn the Causses, where wood was scarce, limestone lauzes were often laid dry on a bed of stone chips directly over a masonry vault, giving a \"vault on vault\" roof. Such roofs typically have a slope of 40-60% (about 22-31 degrees), set by the curve of the vault, and use mortar only at gutters and ridge. In northern Isère, where the technique has also been revived, slabs of schist or limestone held in place by their own weight on a strong oak or poplar frame are reported to last about a century.\n\n## Decline and revival\n\nLauzes were often quarried close to the house as a sideline to farming, with commercial quarries organised only in the 20th century. The craft declined because of low output, high laying costs, heavy reuse of salvaged stone and the spread of industrial substitutes; imported limestone lauzes that proved frost-prone caused failures around 1996-1999. Repopulation of rural areas from the 1980s and financial aid helped revive the trade, and heritage services have worked on it for more than 30 years. The Causses and Cévennes were inscribed on the UNESCO World Heritage List on 28 June 2011 as an evolving cultural landscape.\n\n## Local terms\n\n- *Lauzier*: a craftsman who lays lauzes.\n- *Lauze qui chante*: \"a singing lauze\", a stone that rings when struck, a sign of sound quality.\n- *Gouttier*: large slab at the eaves.\n- *Lignolet*: a ridge made of crossed lauzes.\n- *Coyau*: a small piece that kicks out the roof slope at the eaves.\n- *Cailloutis*: the stone-chip bed on a vault.\n\n## Sources and gaps\n\nWeights per square metre for lauze roofs vary with the stone used; typical figures are not well documented in published sources.","key_facts":[{"label":"Material","value":"Schist or limestone slabs"},{"label":"Regions","value":"Cévennes, Causses, Massif Central, northern Isère"},{"label":"Traditional fixing","value":"Wooden pegs into boarding; now usually nails"},{"label":"Overlap","value":"About two-thirds (three-quarters at low pitch)"},{"label":"Reported life","value":"About a century (Isère)"},{"label":"UNESCO landscape","value":"Causses and Cévennes, 28 June 2011"}],"regions":["Europe"],"aliases":["lauzes","toit de lauzes","lauze roof","stone slab roof"],"related":["stone-slate","piode","roofing-in-france","natural-slate","cotswold-stone-slate"],"company":null,"sources":[{"title":"Expo Lauze","url":"https://www.lozere.gouv.fr/index.php/contenu/telechargement/9273/57500/file/Expo_Lauze.pdf","publisher":"Préfecture de la Lozère"},{"title":"La lauze : un patrimoine à transmettre","url":"https://www.ffbatiment.fr/revues-guides/bam/44-septembre-2016/un-patrimoine-a-transmettre","publisher":"Fédération Française du Bâtiment"},{"title":"Lauze","url":"https://fr.wikipedia.org/wiki/Lauze","publisher":"Wikipédia"}],"country":null},{"slug":"lazaret-cave-shelter","title":"Lazaret Cave Shelter","category":"history","type":"place","summary":"A cave in Nice, France, where a line of stones has been interpreted as the base of a skin tent pitched against the wall about 186,000-127,000 years ago.","body":"The Grotte du Lazaret is a cave in the eastern suburbs of Nice, France, overlooking the Mediterranean. Layers excavated in the 1970s, belonging to marine isotope stage 6 (about 186,000 to 127,000 years ago), contain what Henry de Lumley interpreted as the remains of a shelter built inside the cave. It is one of a small number of Middle Pleistocene sites put forward as evidence of a roofed structure.\n\n## The proposed shelter\n\nThe occupation area measured about 11 by 3.5 m (36 by 11 ft). The cave wall closed it on three sides, and a winding line of large stones formed the fourth. De Lumley suggested the stones were packing that held upright the poles of a tent of animal skins leaning against the rock. No poles or hides would survive, so the reconstruction rests on the stones and on how debris was spread:\n\n- stone flakes and bone spill outward through two gaps in the stone line, which may mark entrances;\n- two circular concentrations of charcoal with burnt bone are probably hearths;\n- tiny marine shells around the hearths may come from seaweed brought in as bedding, hinting at an inner living area and an outer zone under the same cover.\n\n## Who lived there\n\nCranial fragments of a child about nine years old, roughly 200,000 years old, have been assigned to *Homo heidelbergensis* or an early Neanderthal. More than 20,000 fragments of animal bone have been recovered, along with Acheulean stone tools found near the mouth of the cave along one wall. The Laboratoire de Préhistoire du Lazaret, close to the cave, continues to study the material.\n\n## Caveats\n\nThe stone line could also have formed by natural processes, and other proposed early shelters, such as La Baume Bonne and Orgnac cave in France, have weaker evidence still. Evidence for built housing before about 50,000 years ago is generally slim, partly because light structures leave few traces.\n\n## Significance for roofing history\n\nIf the interpretation is right, the Lazaret shelter shows early humans adding a light hide roof to a natural overhang rather than building a free-standing hut. Combining a rock shelter with a lean-to cover remained common in many later periods.","key_facts":[{"label":"Location","value":"Nice, France"},{"label":"Period","value":"Marine isotope stage 6 (about 186,000-127,000 years ago)"},{"label":"Occupation area","value":"About 11 x 3.5 m (36 x 11 ft)"},{"label":"Proposed covering","value":"Animal skins on poles against the cave wall"},{"label":"Hominins","value":"Homo heidelbergensis or early Neanderthal"}],"regions":["Europe"],"aliases":["Grotte du Lazaret","Lazaret cave"],"related":["terra-amata","prehistory-of-roofing","prehistoric-shelters-and-early-thatch"],"company":null,"sources":[{"title":"Grotte du Lazaret","url":"https://en.wikipedia.org/wiki/Grotte_du_Lazaret","publisher":"Wikipedia"},{"title":"Terra Amata (archaeological site)","url":"https://en.wikipedia.org/wiki/Terra_Amata_(archaeological_site)","publisher":"Wikipedia"}],"country":null},{"slug":"lead-roofing","title":"Lead Roofing","category":"materials","type":"article","summary":"Lead roofing uses heavy, highly malleable rolled lead sheet for flat roofs, dormers, bays and flashings, laid in limited bay sizes to control creep and movement.","body":"Lead has been used on roofs since antiquity because it is easy to cast, roll and dress into complicated shapes without cracking. In the UK and Ireland it remains a standard material for flashings, valleys, dormer cheeks and roofs, bay windows, canopies, small flat roofs and the roofs of historic churches and public buildings. In North America lead roofs are rarer and mostly found on historic buildings; one notable eighteenth-century example was the Rosewell mansion in Virginia.\n\n## Material\n\nRolled lead sheet in the UK and much of Europe is made to BS EN 12588 and specified by \"code\" numbers from 3 to 8, which indicate thickness. Codes 5 to 8 (2.24 to 3.55 mm) are typical for roofs and gutters; codes 3 and 4 are used for soakers and flashings.\n\n## Key design principles\n\nGuidance from the Lead Sheet Association (now the Lead Sheet Training Academy) sets out how to size and fix lead:\n\n- **Bay size**: pieces must not be too long or large for their thickness, otherwise thermal movement causes fatigue cracking and the soft metal creeps downhill.\n- **Joints**: long runs are broken up with drips on flat roofs and with wood-cored or hollow rolls along the slope; welded joints are used in some details.\n- **Falls**: flat lead roofs need a minimum fall of 1:80 to avoid ponding.\n- **Flashing lengths**: limited to about 1.5 m (5 ft), or 1 m (3.3 ft) where bonded to bitumen or single-ply membranes.\n- **Laps**: depend on pitch, from about 75 mm (3 in) on vertical work to around 395 mm (15.5 in) on pitched roofs.\n- **Ventilation**: lead on decks is laid over a through-ventilated void of at least 50 mm (2 in), or 25 mm (1 in) on vertical work, to prevent underside corrosion from condensation.\n- **Edges and contact with mortar**: free edges are clipped; lead built into masonry is coated with bitumen paint to protect it from alkali.\n\n## Durability\n\nWell-detailed lead roofs last many decades. Failures are usually linked to oversize bays, poor fixing, inadequate ventilation or the wrong code.","key_facts":[{"label":"Standard","value":"BS EN 12588 (rolled lead sheet)"},{"label":"Roofing codes","value":"Code 5-8 (2.24-3.55 mm)"},{"label":"Minimum fall on flat roofs","value":"1:80"},{"label":"Minimum ventilated void under decks","value":"50 mm (2 in)"}],"regions":["Europe","Global"],"aliases":["leadwork","rolled lead sheet roofing","lead flat roof"],"related":["lead-sheet-codes","lead-sheet-training-academy","creep-in-sheet-metal","ventilation-under-metal-roofs"],"company":null,"sources":[{"title":"The top ten dos and don'ts of rolled lead sheet","url":"https://ribaj.com/products/the-top-ten-dos-and-don-ts-of-rolled-lead-sheet","publisher":"RIBA Journal"},{"title":"Lead Code Thicknesses","url":"https://www.roofingsuperstore.co.uk/blog/lead-code-thicknesses/","publisher":"Roofing Superstore"},{"title":"Lead Sheet Codes Explained","url":"https://www.leadworx.com/ie/?p=24621","publisher":"Leadworx"},{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"}],"country":null},{"slug":"lead-sheet-codes","title":"Lead Sheet Codes","category":"standards-codes","type":"term","summary":"Lead codes (3 to 8) are the UK and European shorthand for rolled lead sheet thickness under BS EN 12588, from about 1.3 mm to 3.6 mm.","body":"In the UK, Ireland and much of Europe, rolled lead sheet is ordered by code number rather than by millimetres. Each code corresponds to a nominal thickness and weight per square metre under BS EN 12588. Choosing the right code matters: too thin a sheet in an exposed position may split or lift, while too thick a sheet is hard to dress and wasteful.\n\n## Code table\n\n| Code | Thickness | Weight |\n|---|---|---|\n| 3 | 1.32 mm (0.052 in) | 14.97 kg/m2 |\n| 4 | 1.80 mm (0.071 in) | 20.41 kg/m2 |\n| 5 | 2.24 mm (0.088 in) | 25.40 kg/m2 |\n| 6 | 2.65 mm (0.104 in) | 30.10 kg/m2 |\n| 7 | 3.15 mm (0.124 in) | 35.72 kg/m2 |\n| 8 | 3.55 mm (0.140 in) | 40.26 kg/m2 |\n\nThickness is allowed to vary by about plus or minus 5% along the sheet.\n\n## Typical uses\n\n- **Code 3**: soakers.\n- **Code 4**: soakers, general flashings and vertical cladding; it is the usual choice for everyday flashing work.\n- **Codes 5 and 6**: flashings, flat and pitched roofs, parapet and tapered valley gutters, dormers, bay roofs and canopies.\n- **Codes 7 and 8**: heavier-duty flat roofs, gutters, dormers and canopies.\n\n## Marking and regional practice\n\nSheets should be marked with the standard, code, thickness, weight, producer and batch. Outside the UK and Europe, lead is more often specified directly by thickness or by weight per area.\n\n## Origin of the name\n\nThe code number is a practical label rather than a metric dimension, and the code system remains the everyday language of UK and Irish roofers and builders' merchants.","key_facts":[{"label":"Standard","value":"BS EN 12588"},{"label":"Code 4","value":"1.80 mm, 20.41 kg/m2 (general flashings)"},{"label":"Code 8","value":"3.55 mm, 40.26 kg/m2"},{"label":"Thickness tolerance","value":"About +/-5%"}],"regions":["Europe"],"aliases":["lead codes","lead code thickness","code 4 lead","code 5 lead"],"related":["lead-roofing","lead-sheet-training-academy"],"company":null,"sources":[{"title":"Lead Code Thicknesses","url":"https://www.roofingsuperstore.co.uk/blog/lead-code-thicknesses/","publisher":"Roofing Superstore"},{"title":"Lead Sheet Codes Explained","url":"https://www.leadworx.com/ie/?p=24621","publisher":"Leadworx"}],"country":null},{"slug":"lead-sheet-training-academy","title":"Lead Sheet Training Academy (LSTA)","summary":"The Lead Sheet Training Academy is a UK training centre in Kent for leadwork and hard-metal roofing skills, approved by CITB.","body":"The Lead Sheet Training Academy (LSTA) is a training organisation in the United Kingdom that teaches the craft of working with sheet lead and other traditional roofing metals, such as copper and zinc (often called \"hard metals\" in the UK trade). Its purpose-built training facility is near Tonbridge in Kent, England, and it can also run courses at other UK locations. The academy marks a centenary covering 1926 to 2026.\n\n## Role\n\nSheet lead has long been used in British building for flashings, gutters, valleys, roofs on bays and dormers, and whole roofs on churches and historic buildings. Working lead well requires hand skills such as bossing (shaping the metal with wooden tools), welding (lead burning) and correct sizing of pieces to allow for thermal movement. The LSTA keeps these skills in use for new building and conservation work.\n\n## Courses and qualifications\n\n- **Specialist Applied-skills Programmes (SAP)** at Level 2 and Level 3 in lead or hard metal. The LSTA states that the Construction Industry Training Board (CITB) appointed it as the sole UK provider of these programmes.\n- **City & Guilds accredited programmes** in leadwork and hard metal at basic, intermediate and advanced levels.\n- **NVQ Level 2 and Level 3** On-site Assessment and Training (OSAT) for experienced workers who need a formal qualification.\n- **Bespoke and safety training**, including cut-off saw operation.\n\nThe academy is a CITB Approved Training Organisation, and its tutors are CITB-approved assessors.\n\n## Other resources\n\nThe LSTA publishes a technical manual on leadwork and keeps a directory of traditional metal roofers.\n\n## Context\n\nLead sheet for building in the UK and Europe is made to the standard BS EN 12588, and thicknesses are described by \"code\" numbers, for example Code 4 or Code 5. Because lead is toxic, safe handling, hygiene and avoiding run-off onto other materials are part of modern training. In other countries, sheet metal and roofing apprenticeships cover similar skills, though lead is used less widely in North America.","key_facts":[{"label":"Location","value":"East Peckham, Tonbridge, Kent, England"},{"label":"Approval","value":"CITB Approved Training Organisation"},{"label":"Qualifications","value":"SAP Level 2/3, City & Guilds, NVQ Level 2/3"},{"label":"Centenary","value":"1926-2026"}],"regions":["Europe"],"aliases":["LSTA","Lead Sheet Association","LSA"],"related":["lead-roofing","citb","lead-sheet-codes"],"company":{"headquarters":"East Peckham, Kent, England","website":"https://www.leadsheet.co.uk","known_for":["Leadwork and hard-metal training","SAP qualifications in lead"]},"sources":[{"title":"Lead Sheet Training Academy","url":"https://www.leadsheet.co.uk/","publisher":"Lead Sheet Training Academy"},{"title":"About CITB","url":"https://www.citb.co.uk/about-citb/","publisher":"CITB"},{"title":"History of the Lead Sheet Training Academy (LSTA)","url":"https://www.leadworx.com/?p=35855","publisher":"Leadworx"},{"title":"The top ten dos and don'ts of rolled lead sheet","url":"https://ribaj.com/products/the-top-ten-dos-and-don-ts-of-rolled-lead-sheet","publisher":"RIBA Journal"}],"category":"organizations","type":"organization","country":null},{"slug":"lead-soakers","title":"Lead Soakers","category":"components","type":"term","summary":"Lead soakers are small sheets of lead interleaved with each course of slates or tiles at an abutment, the UK and Irish counterpart of step flashing.","body":"Soakers are pieces of sheet lead (or sometimes other metal) bent to an L-shape and laid between each course of slates or plain tiles where the roof abuts a wall, chimney or dormer cheek. One leg lies flat under the slate or tile; the other turns up the wall. A stepped cover flashing, let into the mortar joints of the masonry above, is then dressed down over the upturned legs. The combination of soakers and stepped cover flashing is the traditional British and Irish abutment detail and the equivalent of North American step flashing with counter-flashing.\n\n## Layout\n\nUK building control guidance notes that soakers should be roughly the same length as the slates, each fitted over the slate or tile beneath it so that the fixings of the covering above do not puncture the soaker below. The stepped cover flashing is laid over the line of soakers to direct water down the roof to the gutter.\n\n## Lead codes\n\nUK lead sheet is specified by \"code\" numbers related to thickness and weight. Guidance from the Lead Sheet Association, as cited by LABC, gives Code 3 as the minimum for soakers and Code 4 as the minimum for cover flashings, with heavier codes for exposed locations. Lead flashings are typically limited in length to allow for thermal movement.\n\n## When soakers are used\n\nSoakers suit small-format, flat coverings such as natural slate and plain clay or concrete tiles, which lie flat enough for the soaker to sit between courses. Profiled single-lap profiled tiles are usually finished with a lead cover flashing dressed over the tile profile, or with proprietary abutment flashings, rather than soakers.\n\n## Alternatives\n\nLightweight lead substitutes and proprietary flexible flashings exist; their use depends on the covering manufacturer's instructions and local acceptance.","key_facts":[{"label":"Minimum lead (LSA, per LABC)","value":"Code 3 soakers, Code 4 cover flashings"},{"label":"Paired with","value":"Stepped cover flashing"},{"label":"North American equivalent","value":"Step flashing"}],"regions":["Europe"],"aliases":["soakers","soaker","lead soaker"],"related":["step-flashing","counter-flashing","chimney-flashing","roof-flashing"],"company":null,"sources":[{"title":"How to get it right: Too much abutment flashing?","url":"https://www.labc.co.uk/news/how-get-it-right-too-much-abutment-flashing","publisher":"LABC"},{"title":"Lead Soakers: Lightweight Roof Detailing Guide","url":"https://theleadlads.co.uk/lead-soakers-lightweight-roof-detailing-guide-the-lead-lads/","publisher":"The Lead Lads"}],"country":null},{"slug":"leaky-homes-crisis","title":"Leaky Homes Crisis","category":"problems-maintenance","type":"event","summary":"New Zealand’s weathertightness failure affecting timber-framed buildings built 1988-2004, estimated in 2009 to cost about NZ$11.3 billion.","body":"The leaky homes crisis (also called the leaky building crisis) is the widespread failure of weathertightness in New Zealand timber-framed buildings constructed between 1988 and 2004. Water entered through claddings, junctions and roofs and could not escape, causing timber framing to rot. It became one of the most expensive building failures in the country's history and reshaped its building regulation.\n\n## Causes\n\nSeveral factors combined:\n\n- **Face-sealed claddings** such as fibre-cement sheet and expanded polystyrene systems, which relied on paint as the main barrier; hairline cracks let water in.\n- **Reduced drying**: sheet claddings and insulation cut airflow, so moisture stayed in the wall.\n- **Untreated framing**: a 1995 change allowed untreated radiata pine for wall framing, which rots quickly when wet.\n- **Design fashion**: \"Mediterranean\" styles with flat or complex roofs, minimal or no eaves, parapets, recessed windows, balconies and many wall penetrations.\n- **Process failures**: poor installation, products used outside their specifications, missing detailed drawings, fewer apprenticeships, and council inspectors without weathertightness expertise, under the self-regulating regime introduced by the Building Act 1991.\n\n## Roofing lessons\n\nSeveral of the identified causes concern the roof. Minimal or missing eaves left wall tops and window heads exposed to rain, parapets and complex roof shapes multiplied junctions that depended on flashings, and flat roofs and balconies over living spaces relied entirely on membranes and their detailing. The revised E2/AS1 responded with more detailed requirements for flashings and junctions.\n\n## Scale and cost\n\nA 2009 PwC consensus estimate put repair costs at about NZ$11.3 billion for 42,000 buildings; other experts estimated NZ$23 billion for 89,000. Schools were also affected: 73 in 2009, 157 needing repair by 2011 at a cost of at least NZ$1.5 billion, and 309 with leakiness problems by 2013.\n\n## Response\n\n- The **Building Act 2004** replaced the 1991 Act and introduced licensing of designers, builders and trades.\n- **NZS 3602:2003** again required treated radiata pine in external wall framing.\n- The Acceptable Solution for Building Code clause [E2 External Moisture](/nzbc-e2), E2/AS1, was substantially expanded, with more detailed flashings and cavity construction behind many claddings.\n- The **Weathertight Homes Resolution Services Act 2006** set up claims resolution, and a Financial Assistance Package (2010-2016) split repair costs: owners 50%, councils and government 25% each.\n\nCourts have generally held councils responsible for about one-third of costs, and a 10-year limit after construction applies to claims.","key_facts":[{"label":"Country","value":"New Zealand"},{"label":"Buildings affected","value":"Timber-framed, built 1988-2004"},{"label":"Cost estimate","value":"About NZ$11.3 billion, 42,000 buildings (PwC, 2009)"},{"label":"Key roof factors","value":"No eaves, flat/complex roofs, parapets, poor flashings"},{"label":"Main legal response","value":"Building Act 2004"}],"regions":["Oceania"],"aliases":["Leaky building crisis","Leaky homes","NZ weathertightness crisis"],"related":["roofing-in-new-zealand","nzbc-e2","roof-flashing","flashing-failure","flat-roof","parapet"],"company":null,"sources":[{"title":"Leaky homes crisis","url":"https://en.wikipedia.org/wiki/Leaky_homes_crisis","publisher":"Wikipedia"},{"title":"Leaky homes report reveals problem is bigger","url":"https://www.rnz.co.nz/news/national/16993/leaky-homes-report-reveals-problem-is-bigger","publisher":"RNZ"},{"title":"E2 External moisture","url":"https://www.building.govt.nz/building-code-compliance/e-moisture/e2-external-moisture/","publisher":"Ministry of Business, Innovation and Employment"}],"country":null},{"slug":"leed-heat-island-reduction","title":"LEED Heat Island Reduction Credit","summary":"LEED's Heat Island Reduction credit rewards projects whose roofs and paving reflect sunlight or are vegetated, using Solar Reflectance Index thresholds.","body":"LEED (Leadership in Energy and Environmental Design) is a green building rating system developed by the US Green Building Council (USGBC), founded in 1993. It has evolved since 1998 through several versions, including LEED v4 (2013), v4.1 (2019) and LEED v5 (released 2025). Projects earn points across categories, with certification levels of Certified, Silver, Gold and Platinum.\n\nThe **Heat Island Reduction** credit, in the Sustainable Sites category, is the LEED credit most directly tied to roofing. It aims to reduce the \"heat island\" effect, in which dark roofs and paving absorb sunlight and raise urban temperatures.\n\n## How roofs earn the credit\n\nProjects can comply using:\n\n- **High-reflectance roofing** – roof surfaces that meet a minimum [Solar Reflectance Index](/solar-reflectance-index) (SRI).\n- **Vegetated roofs** – green roofs, which cool by shading and evaporation.\n- **A combination**, using a weighted area formula.\n\nUnder LEED 2009 (Sustainable Sites Credit 7.2), for example, at least 75% of the roof area had to have an SRI of 78 or higher for low-slope roofs (29 or higher for steep-slope roofs), or at least 50% had to be vegetated, or an equivalent combination. LEED v4 and v4.1 retained the approach but moved to thresholds based on both initial and three-year aged SRI, reflecting the fact that roofs lose reflectance as they weather. The US EPA cites the LEED v4.1 Heat Island Reduction credit as an example of a voluntary program requiring minimum roof reflectance.\n\n## Data sources\n\nProjects normally use reflectance and emittance values from the [Cool Roof Rating Council](/cool-roof-rating-council) directory to calculate SRI or to document aged values.\n\n## Practical effects on roofing choices\n\nThe credit has encouraged white and light-coloured membranes (such as TPO and PVC), reflective coatings and green roofs on LEED projects. On steep-slope roofs, lower thresholds make some light-coloured shingles, tiles and coated metal eligible.\n\n## Related programs\n\nOther rating systems have similar credits, such as Green Globes in North America and [BREEAM](/breeam) in the UK and Europe, though their criteria and metrics differ.","key_facts":[{"label":"Program","value":"LEED (US Green Building Council)"},{"label":"Category","value":"Sustainable Sites"},{"label":"Compliance options","value":"High-SRI roofing, vegetated roof, or combination"},{"label":"LEED 2009 roof SRI","value":"Low slope ≥ 78; steep slope ≥ 29"},{"label":"Later versions","value":"Initial and 3-year aged SRI thresholds"}],"regions":["Global","North America"],"aliases":["LEED heat island credit","LEED SS heat island","LEED cool roof credit"],"related":["solar-reflectance-index","cool-roof-rating-council","green-roof","breeam","cool-roof"],"sources":[{"title":"Leadership in Energy and Environmental Design","url":"https://en.wikipedia.org/wiki/Leadership_in_Energy_and_Environmental_Design","publisher":"Wikipedia"},{"title":"Cool roof","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"},{"title":"Using Cool Roofs to Reduce Heat Islands","url":"https://www.epa.gov/heatislands/using-cool-roofs-reduce-heat-islands","publisher":"US EPA"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"lepenski-vir-houses","title":"Lepenski Vir Houses","category":"history","type":"place","summary":"Trapezoidal Mesolithic-Neolithic houses on the Danube in Serbia with plastered floors and stone hearths; how they were roofed is still debated.","body":"Lepenski Vir is a prehistoric settlement on the right bank of the Danube in the Iron Gates gorge of eastern Serbia. Its chronology spans roughly 9500/7200 to 5500 BCE, and its distinctive trapezoidal houses belong to a late phase dated about 6300-6000 BCE. Dragoslav Srejović began excavations on 6 August 1965; work continued until 1971. The site is widely cited for its stone sculptures and for being one of the earliest planned settlements in Europe.\n\n## The houses\n\nRemains of 136 residential and sacred buildings were found, in seven successive settlements on a promontory sloping about 11 degrees toward the river.\n\n- **Plan:** each base is a segment of a circle of 60 degrees, giving a trapezoid with the narrow end facing the košava, the strong local wind.\n- **Size:** from about 1.5 m² (16 sq ft) for the smallest, House 49, to around 30-42 m² (320-450 sq ft) for the largest.\n- **Floors:** local limestone clay mixed with animal dung and ash, which hardens like concrete. A reddish clay plaster called lep is the source of the site's name.\n- **Hearths:** an elongated rectangular hearth of stone blocks on the long axis, averaging about 78 by 24 cm (31 by 9 in).\n\n## The roof question\n\nStone reinforcements along the edges of the floors show that the houses carried a superstructure. The roofing material was either perishable or similar to the surrounding loess, so it did not survive. As a result, at least seven reconstructions have been proposed:\n\n- pyramidal or tent-like frames, the form used in most reconstructions;\n- a long arched wattle frame (Dević);\n- transverse arches (Andrejić);\n- diagonally crossing arches (Pavlović);\n- a version with a sloped purlin and no central pillar, shown to be technically feasible by 2011 (Mitrović);\n- a three-pole hut (Jovanović);\n- vertical walls (Borić).\n\nSome digital reconstructions show animal hides on the roof; others suggest timber or wattle coated in red clay.\n\n## Relocation\n\nThe Iron Gate I dam would have flooded the site, so in 1971 most of the houses were moved about 100 m (330 ft) downstream and 29.7 m (97 ft) higher. The original location now lies under the reservoir.\n\n## Significance for roofing history\n\nLepenski Vir illustrates the gap between well-preserved floors and lost roofs: the plan of every house is precisely known, but competing roof reconstructions remain plausible.","key_facts":[{"label":"Location","value":"Iron Gates gorge, Danube, Serbia"},{"label":"Trapezoidal house phase","value":"About 6300-6000 BCE"},{"label":"Buildings","value":"136 residential and sacred structures"},{"label":"Roof evidence","value":"Stone reinforcements at floor edges; covering not preserved"},{"label":"Relocated","value":"1971, about 29.7 m (97 ft) higher"}],"regions":["Europe"],"aliases":["Lepenski Vir","Lepenski Vir trapezoidal houses"],"related":["prehistory-of-roofing","pit-house","linear-pottery-longhouse"],"company":null,"sources":[{"title":"Lepenski Vir","url":"https://en.wikipedia.org/wiki/Lepenski_Vir","publisher":"Wikipedia"},{"title":"Lepenski Vir","url":"https://www.worldhistory.org/Lepenski_Vir/","publisher":"World History Encyclopedia"}],"country":null},{"slug":"lichen-on-roofs","title":"Lichen on Roofs","category":"problems-maintenance","type":"term","summary":"Crusty, slow-growing patches formed by a fungus and alga partnership that cling tightly to roofs and are hard to remove without damage.","body":"Lichens are composite organisms made of a fungus living in partnership with an alga or cyanobacterium. On roofs they form flat, crusty or leafy patches, often grey-green, yellow, orange or white, and they are common on asphalt shingles, wood, slate, stone and clay or concrete tiles. Unlike moss, lichens grow very slowly and can survive long dry periods, so they also appear in drier, sunnier locations.\n\n## Effects on the roof\n\nLichens anchor themselves firmly to the surface. On asphalt shingles, inspectors often find that when a lichen patch is removed, the granules beneath come away with it, leaving a bare spot. Over many years lichens may contribute to surface erosion of porous materials. On old slate and stone roofs, many conservation bodies regard lichen as part of a building's character and a sign of clean air, and advise against aggressive removal unless it is causing a defect.\n\n## Removal\n\n- Lichens are difficult to scrape off without damaging the surface.\n- Treatments marketed for moss and algae, including diluted bleach or zinc-based products, can kill lichen, but the dead patches often take months to weather away.\n- Pressure washing is generally discouraged because it can damage shingles and tiles and drive water under laps.\n- Patience is often the safest approach: treat, then let rain and time loosen the growth.\n\n## Prevention\n\nCopper or zinc strips near the ridge, reducing shade, and keeping debris off the roof can slow regrowth. Because lichens are so slow-growing, a few small patches on an otherwise healthy roof are usually a low priority compared with structural or leak issues. Heavily colonised shingles on an old roof are more often a sign of age than a cause of failure in their own right. See also roof moss and roof algae.","key_facts":[{"label":"Nature","value":"Fungus plus alga or cyanobacterium"},{"label":"Growth rate","value":"Very slow"},{"label":"Removal caution","value":"Scraping can strip shingle granules"}],"regions":["Global"],"aliases":["lichens","roof lichen"],"related":["roof-moss","roof-algae","roof-cleaning","zinc-and-copper-strips","natural-slate"],"company":null,"sources":[{"title":"Lichen and Moss Roof Remediation","url":"https://www.finehomebuilding.com/project-guides/roofing/lichen-moss-roof-remediation","publisher":"Fine Homebuilding"},{"title":"Roof Lichens Damage","url":"https://inspectapedia.com/roof/Roof_Lichens_Damage.php","publisher":"InspectAPedia"},{"title":"Mastering Roof Inspections: Asphalt Composition Shingles, Part 43","url":"https://www.nachi.org/asphalt-comp-shingles-part43-97.htm","publisher":"InterNACHI"}],"country":null},{"slug":"linear-pottery-longhouse","title":"Linear Pottery Longhouse","category":"history","type":"article","summary":"The long timber houses of Europe's first farmers, the Linear Pottery (LBK) culture, with thatched roofs carried on three internal rows of posts.","body":"The Linear Pottery culture, known by the German abbreviation LBK (Linearbandkeramik), was the culture of the first farming communities across much of central Europe. It probably originated north of the Hungarian Plain and spread west as far as the Netherlands. Its most distinctive building is the longhouse: a rectangular timber house, often tens of metres long, of remarkably consistent design across a vast area.\n\n## Plan and frame\n\nMost of what is known comes from ground plans of post holes. W. Startin's 1978 study of LBK house reconstruction, following Modderman's classification of Dutch houses, described the standard plan:\n\n- **Five rows of posts** run the length of the house. Rows 1 and 5 are the outer wall posts; rows 2, 3 and 4 inside carried the roof.\n- **Three parts:** houses may be single, two-part or three-part. The end sections were more heavily built than the centre.\n- **Y-shaped post groups** often appear among the inner posts of the central section in earlier houses.\n\nWidths were typically 5.5-7 m (18-23 ft). Lengths varied; a house at Bylany in the Czech Republic was 45 m (148 ft) long.\n\n## Walls and roof\n\nOuter walls were of wattle and daub, sometimes alternating with split logs, with oak preferred for the massive wall posts. The roof was pitched and thatched, carried by the internal rows of posts. Extra posts at one end of some houses may indicate a partial upper floor. Houses are thought to have had one doorway at one end and no windows, with one or two internal partitions. Long pits beside the outer walls, especially at the closed end, probably collected waste and rainwater.\n\n## Lifespan and households\n\nSome houses stood for as long as 30 years. They required too much labour for a single small family, and archaeologists debate whether each housed an extended family or a larger group. At Vráble in Slovakia about 70 longhouses stood at the same time around 5100 BCE.\n\n## Experimental reconstructions\n\nBecause only post holes survive, roof pitch and covering are reconstructed rather than observed. Museums and experimental archaeologists, for example at the MAMUZ prehistory museum in Austria, have built full-scale and model longhouses to test such reconstructions, and Startin's study estimated the manpower needed to build them.\n\n## Significance for roofing history\n\nThe LBK longhouse is one of the earliest large, standardised roof structures in Europe. Its internal post rows allowed a wide building to be roofed with short timbers, an aisled principle that reappears in later European longhouses, barns and halls.","key_facts":[{"label":"Culture","value":"Linear Pottery (LBK), Early Neolithic central Europe"},{"label":"Width","value":"5.5-7 m (18-23 ft)"},{"label":"Longest cited","value":"45 m (148 ft), Bylany"},{"label":"Frame","value":"Five rows of posts; three inner rows carry the roof"},{"label":"Roof","value":"Pitched, thatched"}],"regions":["Europe"],"aliases":["LBK longhouse","Linearbandkeramik house","Danubian longhouse","Neolithic longhouse"],"related":["prehistory-of-roofing","thatch","viking-age-longhouse","longhouse-roof","bronze-age-roundhouse"],"company":null,"sources":[{"title":"Linear Pottery culture","url":"https://en.wikipedia.org/wiki/Linear_Pottery_culture","publisher":"Wikipedia"},{"title":"Linear Pottery Culture Houses: Reconstruction and Manpower","url":"https://www.cambridge.org/core/journals/proceedings-of-the-prehistoric-society/article/abs/linear-pottery-culture-houses-reconstruction-and-manpower/55DFDD359A620D04364DB6CDA64CA589","publisher":"Proceedings of the Prehistoric Society"},{"title":"Construction of a Neolithic Longhouse Model in the Museum of Prehistory (MAMUZ)","url":"https://exarc.net/sites/default/files/2025-11/Construction%20of%20a%20Neolithic%20Longhouse%20Model%20in%20the%20Museum%20of%20Prehistory%20Urgeschichtemuseum%20%28MAMUZ%29%20_%20The%20EXARC%20Journal.pdf","publisher":"EXARC Journal"}],"country":null},{"slug":"liquid-roofing-and-waterproofing-association","title":"Liquid Roofing and Waterproofing Association (LRWA)","summary":"The LRWA is a UK trade association for liquid-applied roofing and waterproofing, founded in 1979 and based in London.","body":"The Liquid Roofing and Waterproofing Association (LRWA) is a trade association in the United Kingdom for the liquid-applied roofing and waterproofing sector. It was founded in 1979. Its contact address is Roofing House on Worship Street in London, which it shares with the National Federation of Roofing Contractors. Its website is lrwa.org.uk.\n\nMembers include manufacturers of liquid waterproofing systems, contractors and installers, service providers and technical professionals.\n\n## What liquid roofing is\n\nLiquid-applied systems are coatings or membranes applied as a liquid that cure to form a seamless waterproof layer. Types include polyurethane, polyester, PMMA (polymethyl methacrylate) and bitumen-based products, often reinforced with a fleece or mat. They are used for new flat roofs, refurbishing existing roofs, balconies, walkways, gutters and complex details where sheet materials are hard to fit. Hot-melt systems, applied as heated rubberised bitumen, are a related category often used under green roofs and paving.\n\n## Activities\n\n- **Codes of practice and guidance.** The LRWA publishes codes of practice and technical guidance. It has issued an updated Hot Melt Code of Practice aligned with the 2025 edition of BS 6229, the British code of practice for flat roofs.\n- **Competence.** It has published a competence framework for designing and specifying liquid roofing and waterproofing, and supports members with compliance under the UK Building Safety Act.\n- **Training.** It offers accredited training for trainees, experienced workers and specific manufacturer products, including online courses.\n- **Standards.** It works with other UK roofing associations to represent liquid systems in standards development.\n- **Product register.** It runs the Liquid Roofing Finder, a register of products.\n- **Awards and events** for members.\n\n## Context\n\nIn Europe, liquid-applied roof waterproofing kits are assessed under the European Assessment Document system (formerly ETAG 005). Other countries have their own associations for liquid waterproofing. As with any roof system, performance depends on correct surface preparation, thickness and curing conditions.","key_facts":[{"label":"Founded","value":"1979"},{"label":"Address","value":"Roofing House, London, England"},{"label":"Sector","value":"Liquid-applied roofing and waterproofing"},{"label":"Recent guidance","value":"Hot Melt Code of Practice aligned with BS 6229:2025"}],"regions":["Europe"],"aliases":["LRWA"],"related":["national-federation-of-roofing-contractors","flat-roof"],"company":{"founded":"1979","headquarters":"London, England","website":"https://www.lrwa.org.uk","known_for":["Liquid roofing codes of practice","Liquid Roofing Finder product register"]},"sources":[{"title":"Liquid Roofing and Waterproofing Association","url":"https://www.lrwa.org.uk/","publisher":"LRWA"},{"title":"NFRC home page","url":"https://www.nfrc.co.uk/","publisher":"NFRC"}],"category":"organizations","type":"organization","country":null},{"slug":"liquid-applied-roofing","title":"Liquid-Applied Roofing","category":"low-slope-systems","type":"article","summary":"Seamless waterproofing formed by applying liquid resin by brush, roller or spray, often with a fleece or fabric reinforcement, that cures into a membrane.","body":"Liquid-applied roofing, also called liquid-applied membrane (LAM) or fluid-applied roofing, is waterproofing delivered to the roof as a liquid that cures in place into a continuous, seamless, fully bonded membrane. It is used for whole roofs, for refurbishment over existing coverings, and especially for complex details, balconies, terraces and walkways.\n\n## Chemistries\n\n- **Polyurethane:** single- or two-component; elastic and widely used for roofs and balconies.\n- **PMMA (polymethyl methacrylate):** two-component resin cured by a peroxide catalyst; very fast cure, even near 0 C (32 F).\n- **Unsaturated polyester and GRP:** glass-fibre reinforced resin laminates.\n- **Acrylic:** water-based elastomeric coatings, common for restoration and cool roofs.\n- **Silicone:** high-solids coatings with strong UV and ponding resistance.\n- **Bitumen-based and rubberised bitumen:** cold emulsions and hot-melt systems.\n- **Polyurea and hybrid systems:** spray-applied, fast-setting.\n\n## Reinforced systems\n\nMany roof-grade liquids are \"cold-applied reinforced\" systems: a base coat is applied, a polyester fleece or glass mat is embedded while wet, and a top coat saturates it. This wet-on-wet method gives uniform thickness and crack-bridging. PMMA systems with fleece typically reach about 2.3 mm (90 mil).\n\n## Codes and standards\n\nThe IBC requires liquid-applied roofs to have a design slope of at least 1/4 in per 12 in (2%). In the UK the Liquid Roofing and Waterproofing Association (founded 1979) publishes guidance and training, including a code of practice for hot-melt systems.\n\n## Advantages\n\n- no seams, laps or mechanical fixings\n- self-flashing around penetrations and irregular shapes\n- often cold-applied with no hot works\n- can be applied over many existing roofs\n\n## Limitations\n\nThickness depends on the installer, so coverage rates must be checked; a common site method is to mark grid areas matching each container's coverage. Many products are sensitive to rain, humidity and temperature during curing, and substrate preparation and priming are critical.","key_facts":[{"label":"Form","value":"Liquid cured on site into a seamless membrane"},{"label":"Main chemistries","value":"PU, PMMA, polyester, acrylic, silicone, bitumen"},{"label":"IBC minimum slope","value":"1/4:12 (2%)"},{"label":"UK trade body","value":"LRWA (founded 1979)"}],"regions":["Global","Europe","North America"],"aliases":["LAM","fluid-applied roofing","liquid waterproofing","cold liquid roofing"],"related":["pmma-roofing","acrylic-roof-coating","silicone-roof-coating","grp-fibreglass-roofing","hot-melt-rubberized-asphalt","roof-coating"],"company":null,"sources":[{"title":"Liquid Roofing and Waterproofing Association","url":"https://www.lrwa.org.uk/","publisher":"LRWA"},{"title":"Why the need for PMMA","url":"https://rcimag.co.uk/sika-roofing-hub/why-the-need-for-pmma","publisher":"RCI Magazine / Sika"},{"title":"Kemperol AC","url":"https://www.kemper-system.com/US/eng/products/kemperol-ac/","publisher":"Kemper System"},{"title":"Minn. R. 1305.1507 - Requirements for Roof Coverings (IBC Section 1507 amendments)","url":"https://www.law.cornell.edu/regulations/minnesota/Minn-R-1305-1507","publisher":"Cornell Law School LII"},{"title":"Top tips to help you get the most out of your flat roof","url":"https://www.sigroofing.co.uk/?p=12082","publisher":"SIG Roofing"},{"title":"Roof coating","url":"https://en.wikipedia.org/wiki/Roof_coating","publisher":"Wikipedia"}],"country":null},{"slug":"long-straw-thatch","title":"Long Straw Thatch","type":"term","summary":"Thatch made from threshed wheat or rye straw laid with ears and butts mixed, giving a shaggy, 'poured-on' look; traditional in lowland England.","body":"Long straw thatch is thatch made from cereal straw that has been threshed (historically by flail) without being combed, so the stems are mixed, bruised and laid with both ears and butts visible on the surface. It was once the most widespread thatch across the corn-growing regions of England from Dorset northward and is now most closely associated with East Anglia.\n\n## Preparation\n\nStraw from tall, hollow-stemmed winter wheat is cut with a binder while the nodes are still green and stooked in the field for two to three weeks. The thatcher dampens the straw, shakes it onto a bed and draws out double handfuls, which are straightened into bundles called **yealms**, typically 18-24 in (46-61 cm) wide and 4-5 in (10-13 cm) deep. Straw should average at least 30 in (76 cm) long. Because modern short-stemmed wheats are unsuitable, growers maintain old varieties such as Maris Widgeon and Maris Huntsman; rye and triticale are also used.\n\n## Application\n\nYealms are laid onto a base coat and fixed with split hazel spars. The finished roof is raked rather than trimmed, giving a soft, \"poured-on\" appearance in which the long straws can be seen. Distinguishing features are external hazel rods (liggers) along the eaves and gables, and usually wire netting over the whole roof to keep out birds. For rethatching, new straw is normally fixed into the existing thatch after the old surface has been stripped back to a sound base.\n\n## Lifespan\n\nMany long straw roofs have lasted at least 25 years and some up to 50. Ridges need more frequent renewal.\n\n## History and supply\n\nWheat straw was the main thatching material in lowland England from medieval times until the 1950s, when combine harvesters and short-stemmed wheat reduced the supply of suitable straw. Supply remains fragile: after a wet autumn in 2019 and a dry spring in 2020, many growers reported harvests down by roughly 20-80%. Historic England advises against replacing long straw with water reed on listed buildings without clear justification.\n","key_facts":[{"label":"Material","value":"Threshed (uncombed) wheat or rye straw"},{"label":"Bundle name","value":"Yealm, about 18-24 in (46-61 cm) wide"},{"label":"Typical life","value":"About 25-50 years"},{"label":"Main region today","value":"East Anglia, England"}],"regions":["Europe"],"aliases":["longstraw","long-straw thatch","threshed straw thatch"],"related":["thatch","combed-wheat-reed","water-reed-thatch"],"sources":[{"title":"Long straw","url":"https://eamta.co.uk/about-thatch/long-straw/","publisher":"East Anglia Master Thatchers Association"},{"title":"Thatched Roofs - An Introduction","url":"https://www.buildingconservation.com/articles/thatchrf/thatchrf.htm","publisher":"Building Conservation"},{"title":"Traditional straw thatching in times of shortage","url":"https://historicengland.org.uk/content/docs/advice/traditional-straw-thatching-times-of-shortage-context167-mar21","publisher":"Historic England"},{"title":"About thatch","url":"https://eamta.co.uk/about-thatch/","publisher":"East Anglia Master Thatchers Association"}],"category":"materials","company":null,"country":null},{"slug":"low-slope-roof","title":"Low-Slope Roof","category":"low-slope-systems","type":"article","summary":"A roof with only a slight incline, usually 2:12 or less, covered with a continuous waterproof membrane rather than overlapping shingles or tiles.","body":"A low-slope roof is a roof that is nearly level but still built with a small incline so water can drain away. Because water moves slowly across such a surface, these roofs are covered with continuous waterproofing membranes, such as built-up roofing, modified bitumen, single-ply sheets, spray foam or liquid-applied systems, instead of the overlapping water-shedding units used on steep roofs.\n\nLow-slope roofs are the norm on commercial, industrial and institutional buildings, and are common on apartment blocks, extensions and garages worldwide. The term \"flat roof\" is often used for the same thing, especially in the UK and Europe, even though a correctly built roof is never truly flat.\n\n## How the threshold is defined\n\nDefinitions vary by code and organisation:\n\n- **International Building Code (US):** a low-slope roof has a slope of 2:12 (about 17%, or 9.5 degrees) or less. Most membrane assemblies in North America are tested and listed only up to this slope.\n- **NRCA (US):** the National Roofing Contractors Association uses a broader limit of 3:12 (25%) or less for low-slope roofing.\n- **UK (BS 6229):** the British code of practice for flat roofs covers roofs pitched up to 10 degrees with continuously supported flexible waterproofing.\n\n## Minimum slope for drainage\n\nThe IBC sets a minimum design slope of 1/4 in per 12 in (2%, roughly 21 mm per metre) for most membrane coverings, including built-up, modified bitumen, single-ply, spray foam and liquid-applied roofs. Coal-tar built-up roofs are permitted at 1/8 in per 12 in (1%). Roofs designed below these minimums generally need a structural check for ponding instability. In the UK the governing target is a minimum finished fall of 1:80 (about 0.7 degrees).\n\n## Typical assembly\n\nFrom the bottom up, a low-slope roof usually includes a structural deck, an optional vapour retarder or air barrier, thermal insulation (often tapered to create slope), a cover board, the waterproofing membrane, and a surfacing or ballast layer. Edges, parapets, curbs, penetrations and drains are sealed with flashings.\n\n## Why slope and drainage matter\n\nIndustry experience consistently links poor drainage to early failures. Standing water accelerates membrane ageing, adds load to the structure, collects debris and freezes in cold climates. For this reason codes and manufacturers place great weight on falls, drains, overflows and crickets.","key_facts":[{"label":"IBC low-slope limit","value":"2:12 (about 17%) or less"},{"label":"NRCA low-slope limit","value":"3:12 (25%) or less"},{"label":"UK flat roof limit (BS 6229)","value":"Up to 10 degrees"},{"label":"IBC minimum design slope","value":"1/4:12 (2%); 1/8:12 (1%) for coal-tar BUR"},{"label":"UK minimum finished fall","value":"1:80"}],"regions":["Global","North America","Europe"],"aliases":["flat roof","low slope roof","membrane roof","commercial roof"],"related":["flat-roof","positive-drainage","ponding-water","built-up-roofing","single-ply-roofing","modified-bitumen-roofing","tapered-insulation"],"company":null,"sources":[{"title":"Minn. R. 1305.1507 - Requirements for Roof Coverings (IBC Section 1507 amendments)","url":"https://www.law.cornell.edu/regulations/minnesota/Minn-R-1305-1507","publisher":"Cornell Law School LII"},{"title":"Roofing Industry Associations Fact Sheet on Roofs (Feb 2026)","url":"https://iibec.org/wp-content/uploads/2026/02/Roofing-Industry-Associations-Fact-Sheet-on-Roofs-Feb-2026.pdf","publisher":"IIBEC"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"},{"title":"Tech Today: roof slope and positive drainage (M. Graham, March 2005)","url":"https://professionalroofing.net/articles/article/615","publisher":"Professional Roofing / NRCA"}],"country":null},{"slug":"roof-insulation","title":"Low-Slope Roof Insulation","category":"low-slope-systems","type":"article","summary":"Rigid board or sprayed insulation laid above the deck of a low-slope roof, chosen for long-term thermal value, strength, fire and moisture behaviour.","body":"Insulation on low-slope roofs is usually placed above the structural deck as continuous rigid boards, so it insulates without thermal bridging through framing. In a conventional (warm) roof the insulation sits below the membrane; in a protected membrane (inverted) roof it sits above it. Spray polyurethane foam combines insulation and roof substrate in one layer.\n\n## Main materials\n\n- **Polyisocyanurate (polyiso, PIR):** the most common North American roof board; high thermal resistance per thickness, foil or fibre-glass facers.\n- **Expanded polystyrene (EPS):** economical, available in many densities and as tapered boards.\n- **Extruded polystyrene (XPS):** low water absorption; the standard inverted-roof board.\n- **Mineral (stone) wool:** non-combustible, dense boards used where fire performance or acoustics matter.\n- **Cellular glass:** rigid, vapour-tight, high compressive strength; used under heavy loads and in buried roofs.\n- **Wood fibre, perlite and phenolic boards** in some markets.\n\n## Thermal performance and LTTR\n\nInsulation performance is stated as R-value (imperial) or thermal conductivity, lambda, in W/(m.K), and RSI or U-value in metric. Some foams lose thermal resistance as blowing gases diffuse out and air diffuses in, so North America uses long-term thermal resistance (LTTR), a time-weighted value intended to reflect performance over years of service, for polyiso and spray foam. Medium-density closed-cell spray foam has LTTR values of roughly R-5 to R-6 per inch.\n\n## Selection factors\n\n- thermal value and its long-term stability\n- compressive strength under traffic, equipment and ballast\n- moisture tolerance (crucial for inverted and green roofs)\n- fire classification of the assembly\n- compatibility with the membrane and adhesives\n- dimensional stability and ability to be tapered\n\n## Codes\n\nEnergy codes set minimum roof R-values or U-values; in the UK, BS 6229 references a maximum U-value of 0.35 W/m2K at any point on a heated roof, including low points of tapered schemes. Insulation also forms part of wind-uplift and fire-rated assemblies, so boards, fasteners and adhesives must match tested systems.","key_facts":[{"label":"Common boards","value":"Polyiso, EPS, XPS, mineral wool, cellular glass"},{"label":"Long-term rating (N. America)","value":"LTTR for polyiso and spray foam"},{"label":"UK limit at any point (BS 6229:2025)","value":"U = 0.35 W/m2K"},{"label":"Inverted roof board","value":"Usually XPS"}],"regions":["Global"],"aliases":["roof insulation","rigid roof insulation","above-deck insulation"],"related":["polyiso-insulation","eps-insulation","xps-insulation","mineral-wool-roof-insulation","cellular-glass-insulation","tapered-insulation","cover-board"],"company":null,"sources":[{"title":"Polyisocyanurate","url":"https://en.wikipedia.org/wiki/Polyisocyanurate","publisher":"Wikipedia"},{"title":"Polystyrene","url":"https://en.wikipedia.org/wiki/Polystyrene","publisher":"Wikipedia"},{"title":"Mineral wool","url":"https://en.wikipedia.org/wiki/Mineral_wool","publisher":"Wikipedia"},{"title":"Foam glass","url":"https://en.wikipedia.org/wiki/Foam_glass","publisher":"Wikipedia"},{"title":"Spray foam","url":"https://en.wikipedia.org/wiki/Spray_foam","publisher":"Wikipedia"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"}],"country":null},{"slug":"ludowici","title":"Ludowici Roof Tile","category":"manufacturers","type":"company","summary":"Ludowici is a US clay roof tile maker in New Lexington, Ohio, with roots in an 1857 German tile works; it is now part of Wienerberger.","body":"Ludowici Roof Tile is a manufacturer of terracotta (fired clay) roof tile based in New Lexington, Ohio. Its name comes from the Ludowici family of Germany: Carl Ludowici bought a roof tile factory there in 1857, and after his death in 1881 his sons Wilhelm and Franz ran the business, Franz on the commercial side and Wilhelm on design. The American company grew from the Celadon Terra Cotta Company, founded in 1888 in Alfred, New York.\n\n## Corporate history\n\n- **1905**: Celadon bought the Imperial Clay Company and its factory in New Lexington, Ohio.\n- **1906**: The two companies merged as the Ludowici-Celadon Company.\n- **1976**: CSC Inc. of Chicago acquired Ludowici-Celadon.\n- **1989**: CertainTeed, part of Saint-Gobain, bought the company.\n- **1994**: The name was shortened to Ludowici Roof Tile.\n- **Around 2002**: Management passed from CertainTeed to Terreal, another Saint-Gobain clay products business, which left Saint-Gobain the following year with Ludowici included.\n- **2024**: The Austrian group Wienerberger completed its acquisition of Terreal; Ludowici's management moved to Wienerberger's US brick business, General Shale.\n\n## Products\n\nLudowici produces extruded and pressed clay roof tiles in many historic profiles, including Spanish (barrel) tile, single-lap tile and flat shingle tile, along with trim pieces and glazed finishes. Clay tile is fired at high temperature, which gives it colour stability and resistance to weathering.\n\n## Notable buildings\n\nLudowici tile has been used on many landmark buildings in the United States, including the White House, the dome of the Pennsylvania State Capitol, the corner towers of the New York State Capitol, the Plaza Hotel and the New York Life Building in New York, Wrigley Field in Chicago, and the Basilica of the National Shrine of the Immaculate Conception in Washington, DC.","key_facts":[{"label":"Roots","value":"1857 (Germany); US company 1888"},{"label":"Plant","value":"New Lexington, Ohio"},{"label":"Parent","value":"Wienerberger (via Terreal / General Shale)"},{"label":"Product","value":"Clay (terracotta) roof tile"}],"regions":["North America"],"aliases":["Ludowici-Celadon","Celadon Terra Cotta Company"],"related":["clay-roof-tile","terreal","wienerberger","certainteed","spanish-tile"],"company":{"founded":"1888","headquarters":"New Lexington, Ohio, United States","website":"https://ludowici.com","parent":"Wienerberger","known_for":["Clay roof tile","Historic restoration tile"]},"sources":[{"title":"Ludowici Roof Tile","url":"https://en.wikipedia.org/wiki/Ludowici_Roof_Tile","publisher":"Wikipedia"},{"title":"History","url":"https://ludowici.com/ludowici-difference/history/","publisher":"Ludowici"},{"title":"Ludowici","url":"https://terreal.co.uk/en/location/ludowici","publisher":"Terreal UK"}],"country":null},{"slug":"ludwig-hatschek","title":"Ludwig Hatschek","category":"history","type":"person","summary":"Austrian industrialist (1855-1914) who patented the asbestos cement sheet process in 1900 and named the product Eternit in 1903.","body":"**Ludwig Hatschek** (9 October 1855 - 15 July 1914) was an Austrian industrialist who invented the manufacturing process for asbestos cement sheets. His product, **Eternit**, became one of the most widely used roofing and cladding materials of the 20th century.\n\n## Background\n\nIn 1893 Hatschek bought a former paper mill at Schöndorf near Vöcklabruck, Austria. Paper-making machinery would prove central to his invention: he adapted a cardboard machine to build up thin layers of a cement slurry into sheets.\n\n## The invention\n\nHatschek mixed roughly 90% cement with about 10% asbestos fibre and water. The fibres held the cement together in thin layers that could be pressed into sheets much lighter and thinner than conventional concrete. In **1900** he patented the production process under the title \"Production of artificial stone slabs with hydraulic binders\". The method, now called the **Hatschek process**, remains the basis of fibre cement manufacture, using cellulose and synthetic fibres instead of asbestos.\n\n## Eternit\n\nIn **1903** Hatschek gave the product the trade name Eternit, from the Latin *aeternus*, meaning eternal. Rather than build most factories himself, he earned income from royalties and production licences sold around the world. By 1910 Eternit factories operated in many countries. In many markets the Eternit trademark is now held by the Belgian group Etex, although unrelated companies use the name in some countries, such as Eternit S.A. in Brazil.\n\n## Legacy\n\nHatschek's sheets offered a light, fire-resistant and cheap roof covering, used for corrugated sheeting, flat sheets and imitation slates. Their success spread asbestos into buildings on every continent. From the 1970s, recognition of the link between asbestos and diseases such as mesothelioma led to progressive restrictions, and many countries now ban asbestos products. Hatschek died in 1914, decades before these health effects were widely understood, but his name is attached to both a major roofing innovation and one of the largest occupational health problems of the modern era.\n\nWorkers' housing built in Vöcklabruck for the Eternit works is part of his local legacy.","key_facts":[{"label":"Born","value":"9 October 1855"},{"label":"Died","value":"15 July 1914"},{"label":"Patent","value":"1900"},{"label":"Trade name Eternit","value":"1903"}],"regions":["Europe"],"aliases":["Hatschek process","inventor of Eternit"],"related":["history-of-asbestos-cement-roofing"],"company":null,"sources":[{"title":"Ludwig Hatschek","url":"https://en.wikipedia.org/wiki/Ludwig_Hatschek","publisher":"Wikipedia"},{"title":"Fibre cement","url":"https://en.wikipedia.org/wiki/Fibre_cement","publisher":"Wikipedia"},{"title":"Eternit","url":"https://en.wikipedia.org/wiki/Eternit","publisher":"Wikipedia"}],"country":null},{"slug":"m-shaped-roof","title":"M-Shaped Roof","category":"roof-forms","type":"term","summary":"An M-shaped roof is two parallel gable roofs side by side, joined by a central valley or gutter, giving an M-shaped end profile.","body":"An M-shaped roof (also called a double-pitched or twin-gable roof) consists of two parallel gable roofs built side by side, with their outer slopes resting on the outer load-bearing walls and their inner slopes meeting in a central valley. Seen from the gable end, the profile forms the letter M. The arrangement allows a deep building to be roofed with two shorter-span gables instead of one very tall roof.\n\n## Where it is found\n\n- **British terraced and older houses:** many deep Georgian and Victorian houses use double-pile roofs with a central valley gutter, sometimes hidden behind a front parapet. A related form with an inverted V is the London roof or butterfly roof.\n- **Industrial and agricultural buildings:** multiple-span roofs, sometimes extended to three or more bays, are used on warehouses, barns and factories; with glazing on one face of each span they become sawtooth roofs.\n- **Contemporary houses:** the M-shape is used as a deliberate design feature.\n\n## Drainage\n\nThe central valley must collect water from two inner slopes and carry it to the ends of the building or to internal outlets. It is commonly formed as a lined valley gutter or box gutter, traditionally in lead in the UK, sized for the combined area. Because the valley is enclosed by the roof, blockages or undersized gutters can overflow into the building, so access for cleaning, adequate fall and overflow outlets are important.\n\n## Advantages and drawbacks\n\n- Reduces overall roof height and rafter length on deep plans.\n- Allows two smaller attic spaces or vaulted ceilings.\n- The central gutter is a long-term maintenance point, and snow can accumulate in the valley in cold climates.","key_facts":[{"label":"Structure","value":"Two parallel gables with a central valley"},{"label":"Drainage","value":"Central valley or box gutter"},{"label":"Related forms","value":"Butterfly roof, sawtooth roof"}],"regions":["Europe","Global"],"aliases":["double gable roof","twin-gable roof","double-pile roof","valley roof"],"related":["gable-roof","butterfly-roof","sawtooth-roof","rain-gutter","roof-valley"],"company":null,"sources":[{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"},{"title":"Roof","url":"https://www.designingbuildings.co.uk/wiki/Roof","publisher":"Designing Buildings Wiki"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"}],"country":null},{"slug":"maasai-enkaji","title":"Maasai Enkaji","category":"world-roofing","type":"term","summary":"The enkaji is the Maasai house of Kenya and Tanzania: a low, loaf-shaped shell of poles and sticks whose roof is plastered with cow dung and mud by women.","body":"The *enkaji* (also written *ekanji*) is the traditional house of the Maasai, pastoralists of southern Kenya and northern Tanzania. It is a low, rounded, loaf-shaped dwelling of wooden poles and woven sticks, plastered all over, roof included, with cow dung or a mix of dung and mud. Women design, build, repair and maintain the house, while the family homestead around it is organised around the cattle.\n\n## Form\n\nThe enkaji has no sharp corners: its walls curve continuously into the roof, which one study describes as hyperboloid, so the whole house reads as a single monolithic shell. Traditional houses average about 3.2 by 5.6 m (10.5 by 18.4 ft). Low, domed houses packed with leaves and plastered with cattle dung are described as typical of the Maasai in general surveys of African architecture.\n\n## Construction\n\n1. Wooden poles are set in the ground and fastened with horizontal woven sticks.\n2. Gaps are filled with smaller sticks, branches and twigs.\n3. The wall and roof supports are interwoven so that they act as one integrated structure.\n4. The frame is covered with grass and then plastered with cow dung, or a cow dung and mud mix, which hardens into the roof and wall surface.\n\nThe dung plaster must be renewed regularly to protect the house against wear in the wet season. Maintenance is a continuing responsibility of the woman of the house.\n\n## Homestead\n\nSeveral houses stand inside a family homestead (*enkang*, also *ekang*), a fenced compound sited on higher ground with clear sightlines, enclosing a central cattle kraal (*boo*) with separate pens for cattle, goats, sheep and calves. Separate dwellings were made for the mother, with space for young children and young animals (*ekanji ensat*), and for the father (*ekanji orripie*).\n\n## Change\n\nIn the 21st century many Maasai houses have timber roof frames covered with metal sheets, kitchens have moved to separate structures, and spaces once used for animals and hearths are used for storage. The fenced homestead layout has largely persisted.\n\n## Local terms\n\n- *enkaji* / *ekanji* (Maa): house.\n- *enkang* / *ekang* (Maa): family homestead.\n- *boo* (Maa): cattle enclosure.","key_facts":[{"label":"People","value":"Maasai (Kenya and Tanzania)"},{"label":"Roof","value":"Grass covered with cow dung or dung and mud plaster"},{"label":"Builders","value":"Women"},{"label":"Typical size","value":"About 3.2 x 5.6 m (10.5 x 18.4 ft)"},{"label":"Modern change","value":"Timber frame with metal sheets"}],"regions":["Africa"],"aliases":["enkaji","ekanji","Maasai house","Maasai dung hut"],"related":["roofing-in-kenya","roofing-in-tanzania","mud-roof","thatch","corrugated-iron","roofing-in-east-africa"],"sources":[{"title":"Through the Maasai built landscapes","url":"https://artsandculture.google.com/story/ngWxTk735YTJIw","publisher":"Google Arts & Culture"},{"title":"African architecture: Geographic influences","url":"https://www.britannica.com/art/African-architecture/Geographic-influences","publisher":"Encyclopaedia Britannica"},{"title":"Eco-Living the Maasai Way","url":"https://artsandculture.google.com/story/aQXhEHjs026CJA","publisher":"Google Arts & Culture"}],"company":null,"country":null},{"slug":"mabati-rolling-mills","title":"Mabati Rolling Mills","category":"manufacturers","type":"company","summary":"Mabati Rolling Mills is a Kenyan maker of coated steel roofing sheets and tiles and part of Safal Group, which operates in nine African countries.","body":"Mabati Rolling Mills (MRM) is a Kenyan manufacturer of coated steel and steel roofing products and a member of Safal Group. The word mabati is Swahili for metal roofing sheets. MRM cites more than 60 years of experience.\n\n## Safal Group\n\nSafal Group, MRM's parent, dates its history to 1962 and describes more than 60 years in steel building products. It operates in nine countries in eastern and southern Africa: Kenya, Tanzania, Uganda, Rwanda, Ethiopia, Zambia, Mozambique, Namibia and South Africa. Its activities include metallic-coated steel made with its Zincal technology, roofing systems, engineered trusses, ventilation products, hollow sections, pipes and beams.\n\n## Products\n\nMRM's range covers:\n\n- **Residential roofing**: steel roofing sheets and tiles sold under names such as Versatile, Orientile, Elegantile and Minicorr.\n- **Industrial and commercial roofing**: profiles including IT-5 Tekdek, Saflok 700, Newlok 410 and Safdeck.\n- **Coated steel**: metallic-coated and pre-painted coil and sheet under the Zincal, Optima, Optima Plus and Colorplus names.\n- **Structures**: Ultra Span light steel trusses and Safbuild pre-engineered buildings.\n- **Accessories**: flashings, ventilators and louvres, pipes and tubes, and cold rooms (SAFCOOL).\n\n## Context\n\nIn East Africa, steel roofing sheets are used on buildings ranging from rural homes to factories. Steel thickness and the type and mass of the metallic coating are the main factors buyers compare, because they govern resistance to corrosion, particularly in coastal and humid climates. The company also supplies flashings and ridges to complete roofs. Products are designed for residential, industrial and commercial buildings. Coated coil is also sold to other fabricators.","key_facts":[{"label":"Country","value":"Kenya"},{"label":"Parent","value":"Safal Group (since 1962, 9 African countries)"},{"label":"Products","value":"Steel roofing sheets and tiles, coated steel, trusses"},{"label":"Coating brand","value":"Zincal"}],"regions":["Africa"],"aliases":["MRM","Safal Group","Mabati"],"related":["corrugated-iron","metal-roofing","galvanized-steel-roofing"],"company":{"website":"https://www.mabati.com","parent":"Safal Group","known_for":["Steel roofing sheets","Zincal coated steel","Steel roof trusses"]},"sources":[{"title":"Mabati Rolling Mills","url":"https://www.mabati.com/","publisher":"Mabati Rolling Mills"},{"title":"Safal Group","url":"https://www.safalgroup.com/","publisher":"Safal Group"}],"country":null},{"slug":"macuti-house","title":"Macuti House","category":"world-roofing","type":"article","summary":"Traditional house of Mozambique Island with a hipped roof of coconut palm leaves (macuti) on mangrove poles; it gave the island's southern Macuti Town its name.","body":"The macuti house is the traditional dwelling of the Island of Mozambique, off northern Mozambique. Its name comes from *macuti* (also spelled *makuti*), the coconut palm leaves that originally covered its roof. The southern half of the island, where most residents live, is known as Macuti Town, in contrast to the stone and lime town of the north. Both halves are part of the World Heritage property inscribed in 1991.\n\n## Construction\n\nA 2011 study by Silje Eroy Sollien, presented at the ICOMOS General Assembly, describes the house:\n\n- **Frame**: mangrove poles (*siki*) and bamboo.\n- **Roof**: a generous hipped canopy carried on two main posts about 2.5 m (8 ft) high and covered with coconut palm leaves.\n- **Walls**: a curtain of vertical mangrove sticks (*laca laca*) tied together at the centre and filled with stones, earth and sand (*pau a pique*). A heavier version uses large amounts of stone and lime, approaching a coral-stone double wall with laca laca at its core.\n- **Additive**: an extract of the plant *Cissus integrifolia* (*murrapa*) was mixed in for strength and water resistance.\n\n## Decline\n\nSince the 1950s, and especially from the late 1970s, new houses on the island have increasingly been built with cement blocks and fibre-cement or corrugated iron roofs. The reasons given are economic and practical: block and sheet-roofed houses have become cheaper and need less maintenance, natural materials and the money to buy them are scarce, many owners cannot afford upkeep, and conventional construction is seen as a sign of development. By the time of the study, under a quarter of houses still had mangrove-based construction and about 35% had macuti or other leaves on the roof. *Macarasse* leaves, which are easier to find, have largely replaced coconut macuti.\n\nUNESCO notes that after the 1976-1992 war an influx of people caused overcrowding, and that the scarcity and cost of materials have hindered maintenance. Replacing traditional materials with modern ones is identified as a risk to authenticity because house forms and designs have changed.\n\n## Related forms\n\nPalm-leaf thatch of the same name, *makuti*, is used along the East African coast; see Palm thatch.","key_facts":[{"label":"Location","value":"Island of Mozambique"},{"label":"Roof","value":"Hipped, coconut palm leaf (macuti)"},{"label":"Frame","value":"Mangrove poles (siki) and bamboo"},{"label":"Main posts","value":"About 2.5 m (8 ft)"},{"label":"Leaf roofs remaining","value":"About 35% of houses (2011 study)"}],"regions":["Africa"],"aliases":["makuti house","Macuti Town house"],"related":["roofing-in-mozambique","palm-thatch","corrugated-iron","corrugated-fibre-cement-sheet","roofing-in-east-africa"],"company":null,"sources":[{"title":"The Macuti House, Traditional Building Techniques and Sustainable Development in Ilha de Mocambique (ICOMOS 17th General Assembly, 2011)","url":"https://vbn.aau.dk/ws/portalfiles/portal/310575981/SOLLIEN_ARTICLE_PROCEEDINGS.pdf","publisher":"Silje Eroy Sollien / Aalborg University repository"},{"title":"Island of Mozambique","url":"https://whc.unesco.org/en/list/599/","publisher":"UNESCO World Heritage Centre"},{"title":"Island of Mozambique","url":"https://en.wikipedia.org/wiki/Island_of_Mozambique","publisher":"Wikipedia"}],"country":null},{"slug":"magnetic-sweeper","title":"Magnetic Sweeper","category":"tools-equipment","type":"term","summary":"A wheeled or hand-held magnet used to pick up dropped roofing nails and metal debris from lawns, driveways and decks after roof work.","body":"A magnetic sweeper is a cleanup tool that uses a strong permanent magnet to collect nails, staples, screws and metal offcuts. On reroofing jobs, thousands of old nails fall from the roof during tear-off, and new nails are dropped during installation. Loose nails on lawns, driveways and paths are a hazard to people, pets, tyres and mowers, so sweeping the site is a standard part of job cleanup and of many contractors' quality checklists.\n\n## Types\n\n- **Rolling sweepers** look like a push broom or small lawn mower, with a magnetic bar mounted between two wheels and a handle. Product listings show widths from about 17 in to 30 in (roughly 43 to 76 cm). Many have a quick-release lever that lets the collected nails drop into a bin or onto a tarp.\n- **Hand-held magnetic pickups and wands** reach into flower beds, gravel and gutters.\n- **Large tow-behind sweepers** cover car parks and large sites.\n- **Magnetic trays and bowls** hold fasteners on the roof to reduce drops in the first place.\n\n## Use\n\nSweeping in overlapping passes, slowly, picks up more nails than a fast single pass. Grass length, gravel, mulch and leaf litter affect how close the magnet gets to buried nails, so crews often sweep more than once, including after mowing or rain. Nails can be thrown well beyond the drip line of the roof, especially from steep roofs and when debris is dropped into dumpsters, so the swept area typically extends well out from the house. Tarps laid around the base of the walls during tear-off catch much of the debris.\n\n## Limits\n\nMagnets only collect ferrous metals. Aluminium, copper and most stainless-steel fasteners, and plastic cap fasteners, are not picked up and must be gathered by hand or by other means.\n\n## Related tools\n\nRoofing shovels and pry bars for tear-off; chutes, dumpsters and trailers for debris; and leaf blowers or brooms for clearing granules and dust from roofs and driveways.","key_facts":[{"label":"Purpose","value":"Collect dropped nails and metal debris"},{"label":"Common widths","value":"About 17-30 in (43-76 cm)"},{"label":"Limitation","value":"Only picks up ferrous metal"}],"regions":["Global"],"aliases":["nail sweeper","magnetic nail sweeper","magnet roller"],"related":["roofing-shovel","roofing-nailer","repair-vs-replace"],"company":null,"sources":[{"title":"30 in Rolling Magnetic Sweeper","url":"https://www.bigrocksupply.com/store/p/7041-30-in-Rolling-Magnetic-Sweeper.aspx","publisher":"Big Rock Supply"},{"title":"Magnetic sweeper 24 inch rolling","url":"https://gutterall.com/products/magnetic-sweeper-24-inch-rolling","publisher":"GutterAll"},{"title":"Homeowners magnetic sweepers","url":"https://www.bluestreakequipment.com/shop/magnetic-sweepers/magnetic-sweepers-by-industry/homeowners-magnetic-sweepers/","publisher":"Blue Streak Equipment"}],"country":null},{"slug":"makuti-thatch","title":"Makuti Thatch","category":"world-roofing","type":"term","summary":"Makuti is East African coastal thatch made of coconut palm leaves stitched over sticks into panels, tied to roof battens with sisal fibre.","body":"*Makuti* (Swahili) is a thatch made from the leaves of the coconut palm (*Cocos nucifera*, Swahili *mnazi*), widely used in East Africa and especially on the Kenyan coast. Unlike loose grass thatch, makuti is made up in advance as small panels of folded leaves, which are then tied to the roof in overlapping rows. It is a traditional roof for coastal houses and outbuildings and also a signature of beach hotels and eco-lodges.\n\n## How makuti is made\n\nA description of production on the Kenyan coast sets out the steps:\n\n1. Leaves are harvested when they turn brown and are sun-dried.\n2. They are soaked in water so they fold without cracking.\n3. Sticks are cut to length, for example about 30 cm (12 in), and the leaves are folded over them.\n4. The folded leaves are stitched over the stick with a back-stitch.\n5. Finished panels are packed in bundles and stored until use.\n\nOn the Kenyan coast, makuti is mostly produced by Mijikenda communities, and it is sold as a local, low-cost product that supports palm growers.\n\n## Installation\n\nEach panel is tied to the roof structure with sisal fibre, starting at the eaves and working up to the ridge. Successive rows overlap by about 10 cm (4 in) so that rain runs off rather than dripping through. The layered panels leave air gaps that help ventilate the roof space.\n\n## Performance\n\n- **Comfort**: makuti roofs are reported to keep interiors cooler than iron-sheet roofs, which is one reason for their popularity on the hot, humid coast.\n- **Cost**: makuti is described as one of the cheapest and most readily available roofing options on the Kenyan coast.\n- **Lifespan**: a makuti roof lasts about 5 to 7 years before renewal, against the 50 to 100 years quoted for clay tiles.\n- **Fire**: makuti is highly flammable. Fires at hotels in Watamu, Malindi, Kilifi, Diani and Mombasa have caused major losses, and by 2026 insurers were reported to be reluctant to cover makuti-roofed properties. Hoteliers have been urged to adopt fire-resistant thatching technologies.\n\n## Uses\n\nIn Swahili coral-stone towns such as Lamu, small thatched roofs sheltered rooftop or courtyard kitchens so that smoke did not damage lime plaster. Makuti remains common on rural coastal houses and is used deliberately in tourism architecture, where it is treated as a mark of coastal identity and prestige. Contemporary architects have also explored its limits: the Red Pepper House in Lamu by Urko Sánchez Architects uses makuti as its key constructive element together with coral stone, lime and mangrove timber.\n\n## Related practice\n\nMakuti is one of many palm-leaf thatches used in the tropics; others include the nipa and sago thatches of South-East Asia and Oceania and the palm thatches of West and Central Africa. See palm thatch.","key_facts":[{"label":"Material","value":"Sun-dried coconut palm leaves (mnazi)"},{"label":"Form","value":"Leaves folded and back-stitched over sticks about 30 cm (12 in) long"},{"label":"Fixing","value":"Tied with sisal fibre, about 10 cm (4 in) overlap"},{"label":"Lifespan","value":"About 5-7 years"},{"label":"Main risk","value":"Fire"},{"label":"Region","value":"Kenyan and Tanzanian coast, Zanzibar"}],"regions":["Africa"],"aliases":["makuti","makuti roof","coconut palm thatch"],"related":["palm-thatch","thatch","roofing-in-kenya","roofing-in-tanzania","swahili-coral-stone-house","sago-palm-thatch","thatch-maintenance","roofing-in-east-africa"],"sources":[{"title":"Traditional Roofing in Kenya","url":"https://www.wildlifeworks.com/post/traditional-roofing-in-kenya","publisher":"Wildlife Works"},{"title":"Makuti thatched roofs in Kenya's coast under scrutiny amid fire losses and insurance challenges","url":"https://tnx.africa/county/article/2001550179/makuti-thatched-roofs-in-kenyas-coast-under-scrutiny-amid-fire-losses-and-insurance-challenges","publisher":"The Standard / TNX Africa"},{"title":"Makuti thatching","url":"https://en.wikipedia.org/wiki/Makuti_thatching","publisher":"Wikipedia"},{"title":"Why makuti roof is a lasting feature in Coast hotel design","url":"https://www.standardmedia.co.ke/article/2001380550/why-makuti-roof-is-a-lasting-feature-in-coast-hotel-design","publisher":"The Standard"},{"title":"The Red Pepper House in Lamu: An Exploration of the Limits of Makuti","url":"https://traditionalarchitecturejournal.com/index.php/home/article/view/873","publisher":"Journal of Traditional Building, Architecture and Urbanism"},{"title":"Vernacular Housing of Lamu (Swahili Housing)","url":"https://www.archnet.org/sites/6076","publisher":"Archnet"}],"company":null,"country":null},{"slug":"malarkey-roofing-products","title":"Malarkey Roofing Products","category":"manufacturers","type":"company","summary":"Malarkey Roofing Products is a Portland, Oregon asphalt shingle maker founded in 1956, acquired by Holcim in 2022 and now part of Amrize.","body":"Malarkey Roofing Products is a North American manufacturer of residential roofing, headquartered in Portland, Oregon. It was founded in 1956 by Herbert Malarkey and operated as a family business for more than six decades before being sold to the Swiss building-materials group Holcim in 2022.\n\n## Ownership\n\nHolcim announced the completion of its purchase of Malarkey in early 2022 and placed it within its Solutions & Products segment, alongside the commercial roofing business it had bought from Bridgestone the previous year. At the time Holcim projected Malarkey's 2022 net sales at about USD 600 million. When Holcim separated its North American operations into the independently listed company Amrize in June 2025, its North American roofing businesses went with it.\n\n## Products\n\nMalarkey makes a complete residential roofing system, from asphalt shingles to underlayments and ice and water barriers, plus starter, hip and ridge products. The products are sold through roofing distributors to residential contractors.\n\n## Manufacturing\n\nAt the time of the Holcim acquisition, Malarkey operated production facilities in Oregon, California and Oklahoma.\n\n## Context\n\nMalarkey's sale was one of several acquisitions in the early 2020s in which large international materials groups bought established North American roofing manufacturers, reflecting the size and steady replacement demand of the US re-roofing market.\n\n## Residential roofing systems\n\nNorth American shingle manufacturers, Malarkey among them, typically sell shingles together with matching underlayments, starter strips and hip and ridge caps. Using components from one manufacturer is usually a condition of the extended system warranties they offer to homeowners through certified or registered contractors.","key_facts":[{"label":"Founded","value":"1956"},{"label":"Founder","value":"Herbert Malarkey"},{"label":"Headquarters","value":"Portland, Oregon, US"},{"label":"Acquired","value":"By Holcim, 2022; now within Amrize"}],"regions":["North America"],"aliases":["Malarkey","Malarkey Roofing"],"related":["amrize","holcim-elevate","asphalt-shingle","ice-and-water-shield"],"company":{"founded":"1956","headquarters":"Portland, Oregon, United States","website":"https://www.malarkeyroofing.com","parent":"Amrize","known_for":["Asphalt shingles","Underlayments","Ice and water barriers"]},"sources":[{"title":"Holcim completes acquisition of Malarkey Roofing Products","url":"https://www.holcim.com/holcim-completes-acquisition-malarkey","publisher":"Holcim"},{"title":"Holcim completes roofing acquisition","url":"https://rockproducts.com/2022/03/01/holcim-completes-roofing-acquisition/","publisher":"Rock Products"},{"title":"Elevate","url":"https://www.elevatecommercialbp.com/us-en","publisher":"Elevate"}],"country":null},{"slug":"maloca","title":"Maloca","category":"world-roofing","type":"article","summary":"Large communal thatched longhouse of Indigenous peoples of the northwest Amazon, especially the Tukanoan peoples of Colombia and Brazil.","body":"A *maloca* is a large communal house built by Indigenous peoples of the Amazon, especially in Colombia and Brazil. It is the classic dwelling of the Eastern Tukanoan peoples of the Vaupés region, including the Barasana, Makuna, Tanimuka, Taiwano and Desana, along the Vaupés, Papurí, Pirá-Paraná and Apaporis rivers.\n\n## Social space\n\nSeveral related families live together in one maloca, each with its own compartment and hearth, and the house is linked to a patrilineal descent group. The headman's family lives nearest the back wall. Malocas traditionally have two entrances, one used mainly by men and one by women. During festivals and ceremonies, including men's dances, the interior is rearranged and the centre of the house becomes the main dancing ground.\n\nEach maloca is traditionally surrounded by two gardens: an inner kitchen garden with bananas, papaya, mango and pineapple, and an outer field of manioc.\n\n## Thatch\n\nMaloca roofs are thatched with palm leaves. In the Colombian Amazon one of the most valued thatches comes from the small palm *Lepidocaryum tenue*, whose leaves are braided along split stems of the stilt palm *Socratea exorrhiza*. A 2020 study by Jaime Navarro López, Rodrigo Bernal and Gloria Galeano, carried out with five Indigenous communities north of Leticia, estimated that thatching a house of 48 m² (517 sq ft) needs the *Socratea* from about 1 ha (2.5 acres) of forest and the *Lepidocaryum* from about 0.81 ha (2 acres). Traditional harvesting takes all but the three youngest leaves of each *Lepidocaryum* plant, allowing it to recover, but the authors found overexploitation near settlements.\n\n## Influence\n\nThe Jesuit mission churches of Chiquitos in Bolivia are thought to have been partly inspired by Indigenous architecture.","key_facts":[{"label":"Region","value":"Northwest Amazon (Colombia, Brazil)"},{"label":"Peoples","value":"Eastern Tukanoan and others"},{"label":"Roof","value":"Palm thatch, e.g. Lepidocaryum tenue on Socratea stems"},{"label":"Residents","value":"Several related families, each with a hearth"}],"regions":["Latin America"],"aliases":["maloka","Tukano longhouse","Amazonian longhouse"],"related":["palm-thatch","thatch","shabono","roofing-in-colombia","roofing-in-brazil"],"company":null,"sources":[{"title":"Maloca","url":"https://en.wikipedia.org/wiki/Maloca","publisher":"Wikipedia"},{"title":"Del mito de la invisibilidad femenina a la complementariedad (Amazonia colombiana)","url":"https://core.ac.uk/download/427651266.pdf","publisher":"Universidad Nacional de Colombia, Sede Amazonía"},{"title":"Management of Lepidocaryum tenue and Socratea exorrhiza, two Amazonian palms used for thatching","url":"https://www.ethnobotanyjournal.org/index.php/era/article/view/1583","publisher":"Ethnobotany Research and Applications"}],"country":null},{"regions":["Europe"],"company":null,"slug":"maltese-deffun-roof","title":"Maltese Deffun Roof","category":"world-roofing","type":"term","summary":"The traditional Maltese flat roof: limestone slabs, a lime-and-stone fill, and a beaten surface of lime and crushed pottery called deffun.","aliases":["deffun","Maltese flat roof","traditional Maltese roof"],"body":"The **deffun roof** is the traditional flat roof of Malta and Gozo. It spans rooms with slabs of local limestone and seals them with lime-based layers, the top one being *deffun*, a waterproof mortar of hydrated lime and crushed pottery. Roofs of this kind were the norm on the islands for hundreds of years, notably in buildings of the Knights of St John (1530-1798), and University of Malta researchers note that similar layered roofs are found in many neighbouring Mediterranean countries.\n\n## Build-up\n\nFrom the bottom up:\n\n1. **Structural slabs** of limestone resting on stone arches, or in later buildings on timber or iron beams.\n2. **Fill** of limestone chippings mixed with stone dust and lime.\n3. **Deffun surface** of lime mixed with crushed pottery. Water is sprinkled on it and it is beaten and compacted, by hand in the past, then covered with straw to slow evaporation and help it cure.\n\nA slight fall carries rain quickly to the cistern that every traditional house had. The roof therefore doubled as the household's water catchment.\n\n## Performance\n\nThe deffun surface is porous. It absorbs moisture, including heavy dew on hot summer nights, and the evaporation of that water during the day cools the surface through latent heat. A University of Malta project, EO4HBCS (2020-2022), funded by the Malta Council for Science and Technology, compared traditional, \"hybrid\" and modern roofs using satellite data, drones and sensors. It found that traditional roofs offered the best balance between dispersing heat and insulating, and described them as the cooler type, although more research is needed. Very high resolution satellite imagery could also identify traditional roofs from their colour.\n\n## Maintenance and change\n\nDeffun roofs need yearly maintenance after the summer heat and before the first September rains. In some recent interventions the deffun has been replaced by a concrete slab and screed on the original arches and fill, or covered with a bituminous membrane. The researchers are developing guidelines to protect remaining traditional roofs and exploring a modern version for new buildings, with possible benefits for energy use and the urban heat island.\n\n## Related Maltese terms\n\n- *torba* - a covering layer, used with gravel on the corbelled huts called *giren*\n- *ċagħqija* - a pebbly material sometimes used on girna roofs","key_facts":[{"label":"Surface","value":"Lime mixed with crushed pottery (deffun)"},{"label":"Structure","value":"Limestone slabs on arches or beams"},{"label":"Maintenance","value":"Yearly, before September rains"},{"label":"Thermal behaviour","value":"Evaporative cooling; best heat/insulation balance in 2020-22 study"}],"related":["roofing-in-malta","flat-roof","cool-roof","cycladic-flat-roof"],"sources":[{"title":"A first-ever research on the thermal properties of Malta's traditional roofs","url":"https://www.um.edu.mt/newspoint/news/2022/10/a-first-ever-research-on-the-thermal-properties-of-malta-s-traditional-roofs","publisher":"University of Malta"},{"title":"A New Approach to Studying Traditional Roof Behaviour in a Changing Climate: A Case Study from the Mediterranean Island of Malta (Heritage, 2021)","url":"https://www.mdpi.com/2571-9408/4/4/196","publisher":"MDPI Heritage"},{"title":"Sustainability of Traditional, Historical Roofs in the Mediterranean (Sustainability, 2023)","url":"https://www.mdpi.com/2071-1050/15/17/12723","publisher":"MDPI Sustainability"},{"title":"Girna","url":"https://en.wikipedia.org/wiki/Girna","publisher":"Wikipedia"}],"country":null},{"slug":"maneaba","title":"Maneaba","category":"world-roofing","type":"article","summary":"The great pandanus-thatched meeting house of Kiribati, built of coconut wood and coral without nails; the centre of village governance.","body":"The *maneaba* (also *mwaneaba*) is the community meeting house of Kiribati and the heart of village life. It is usually the largest building in a village, and its thatched roof has been called the largest single cultural artefact in the country, visible from the air. Tuvalu's equivalent, from the shared history of the Gilbert and Ellice Islands colony, is the *maneapa* or *ahiga*.\n\n## Construction\n\nA traditional maneaba stands on slabs of coral and is built mainly from coconut and pandanus trees, with a large roof of coconut wood tied with coconut-fibre string and thatched with pandanus leaves. Researcher Kerry Whincup records that it uses no nails, screws or glue. Joints are made with wooden pins, fitted joinery and coconut-husk string (*te kora*), each with its own specified lashing; some knots are very complex. Husks are soaked under the lagoon sand for about three months, then the fibre is dried and rolled into string by hand. Men build and repair the maneaba, and women make the string.\n\nKey parts include:\n\n- **Boua**: coral supports.\n- **Tatanga**: horizontal beams forming the low eaves.\n- **Boutabu** and **boua ni kaua**: vertical posts.\n- **Oka**: diagonal roof beams carrying slats (*kaukau* and *bwai ni kakori*).\n- **Te rau**: pandanus thatch lashed to the slats.\n- **Te taubuki**: the ridge pole, hauled into place at about 12-13 m (39-43 ft).\n\nThe floor is spread with fine coral stones covered with coarse palm-frond mats (*inaai*). Three traditional styles, Tabontebike, Tabiang and Maungatabu, differ in the proportions of length to width and in the number and placement of beams. Size depends on the expected users, the land and the builder: the Atanikarawa maneaba on Tabiteuea North is about 40 by 20 m (130 by 65 ft), and the Catholic maneaba at Koinawa on Abaiang about 60 by 17 m (200 by 55 ft).\n\n## Social role\n\nOld men (*unimwane*) sit in hereditary clan positions (*boti*) around the edge, and the post each family sits against reflects social hierarchy; disputes over these places can be serious. The building is the basis of island and national governance, and the national parliament is named the Maneaba ni Maungatabu (\"Maneaba of the Sacred Mountain\").\n\n## Modern change\n\nOn South Tarawa nearly all meeting houses now use imported materials, Eita being an exception. Iron roofs need less maintenance and carry status, but Whincup notes that they heat up quickly, drown out speech in heavy rain and reduce the passing on of building skills; concrete floors are uncomfortable for long meetings. Even so, thatch remains common in Kiribati: in the 2018-19 Multiple Indicator Cluster Survey, 55.5% of household records listed thatch or palm leaf as the main roof material.","key_facts":[{"label":"Country","value":"Kiribati (Tuvalu: maneapa/ahiga)"},{"label":"Roof covering","value":"Pandanus thatch (te rau)"},{"label":"Structure","value":"Coconut wood on coral supports; lashed, no nails"},{"label":"Ridge height","value":"About 12-13 m (39-43 ft)"},{"label":"Large example","value":"Koinawa, Abaiang, about 60 x 17 m"}],"regions":["Oceania"],"aliases":["Mwaneaba","Maneapa","Ahiga","Kiribati meeting house"],"related":["roofing-in-kiribati","roofing-in-tuvalu","palm-thatch","thatch","samoan-fale","fijian-bure","haus-tambaran"],"company":null,"sources":[{"title":"Maneaba","url":"https://en.wikipedia.org/wiki/Maneaba","publisher":"Wikipedia"},{"title":"Whincup, The Kiribati maneaba (Shima vol. 4 no. 1)","url":"https://www.shimajournal.org/issues/v4n1/k.-Whincup-Shima-v4n1-113-130.pdf","publisher":"Shima: The International Journal of Research into Island Cultures"},{"title":"Kiribati MICS 2018-19, main material of roof (HC5)","url":"https://catalog.ihsn.org/catalog/10024/variable/F4/V904?name=HC5","publisher":"IHSN Survey Catalog"}],"country":null},{"slug":"mangalore-tile","title":"Mangalore Tile","type":"article","summary":"Interlocking red clay roof tile first made industrially in Mangalore, India, in 1865; widely used on the west coast of India.","body":"The Mangalore tile is an interlocking, kiln-fired clay roof tile named after the port city of Mangalore (Mangaluru) in Karnataka, India. It became the standard pitched-roof covering along much of India's western coast and is still recognisable on houses, schools and public buildings from Goa to Kerala.\n\n## Origins\n\nThe tiles were introduced by German missionaries of the Basel Mission. Georg Plebst, who had been in India with the mission since 1851, studied industrial ceramics in Alsace before setting up a tile works in Mangalore. Production began on 4 December 1865 with two workers, making it the first industrial tile factory in India. Early designs followed those of the Gilardoni brothers of Altkirch, France; later the dominant pattern was based on a design by Wilhelm Ludowici from 1881.\n\nOther factories followed quickly, including Albuquerque (1868) and Alvares (1878). Around 25 factories existed by the early 1900s and roughly 75 by 1994.\n\n## Material and form\n\nThe tiles are made from laterite clay dug from the banks of local rivers such as the Gurupura and Nethravathi. High iron content gives them their characteristic red colour. Because the tiles engage with one another, fewer are are needed to cover a given area than with older pan tiles, which reduced roof weight. Each tile weighs roughly 2-3 kg (4.4-6.6 lb), and the tiles are commonly laid on timber battens at a pitch of about 45 degrees, which sheds heavy monsoon rain.\n\n## Spread\n\nMangalore-pattern tiles are most common in coastal Karnataka (Canara), Goa, Kerala and the Konkan. In Kerala they replaced much palm-leaf thatch and older pan tiles during the British period. The tiles were also exported to East Asia, Africa, Australia, Europe and the Middle East.\n\n## Decline\n\nShortages of suitable clay and restrictions on clay extraction have closed many factories; about ten shut in 2007 alone. Raw-material supply remains the industry's main constraint.","key_facts":[{"label":"First production","value":"4 December 1865, Mangalore"},{"label":"Founder","value":"Basel Mission (Georg Plebst)"},{"label":"Material","value":"Iron-rich laterite clay"},{"label":"Weight","value":"About 2-3 kg (4.4-6.6 lb) per tile"},{"label":"Typical pitch","value":"About 45°"}],"regions":["South Asia"],"aliases":["Mangalore pattern tile","Mangalorean tile","Basel Mission tile","Mangaluru tile"],"related":["kerala-sloping-roof","roofing-in-india","clay-roof-tile","interlocking-clay-tile","terracotta"],"sources":[{"title":"Mangalore tiles","url":"https://en.wikipedia.org/wiki/Mangalore_tiles","publisher":"Wikipedia"},{"title":"Architecture of Kerala","url":"https://en.wikipedia.org/wiki/Architecture_of_Kerala","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"mangh-windcatcher","title":"Mangh (Sindhi Windcatcher)","category":"world-roofing","type":"term","summary":"A mangh is a fixed rooftop windcatcher of Hyderabad, Sindh, in Pakistan, that scooped the south-west breeze down into the rooms below.","body":"A **mangh** is a rooftop wind scoop, the Sindhi form of the windcatcher. In the old city of Hyderabad in Sindh, Pakistan, nearly every house once had one or more manghs rising from its flat roof, all facing the same way to catch the cool breeze that blows inland from the Arabian Sea in summer. The city was nicknamed *Manghan jo Shahar*, \"city of windcatchers\". In southern Sindh the device is also called *badigar*.\n\n## How it works\n\nHyderabad's manghs were fixed, one-directional scoops. Because the cooling summer wind came reliably from the south-west, the scoops could be built permanently in one position. Each mangh was a triangular, chimney-like shaft with a lip opening towards the breeze. The shaft carried air down through the roof into the main room of the house, called the *wado sufo*. Older houses usually had one mangh per room, though one placed on a shared corner wall could serve two rooms.\n\nThe opening was fitted with shutters worked by a lever and rope from inside, so the household could control the airflow. In summer the shutters were opened before sunset and closed late the next morning, around 11:00; in winter they were opened only in the middle of the day, from about 11:00 to 14:30, to let in daylight and a little warm air.\n\nThe design suited old Hyderabad, where narrow lanes left little room for street-facing windows and the town lay between the Indus and the Phuleli canal.\n\n## History\n\nSome accounts say the technique was in use in Hyderabad about 500 years ago, and old photographs of the Hirabad district show manghs on most houses. Bernard Rudofsky's 1964 book *Architecture Without Architects* introduced the Hyderabad skyline to architects around the world, and it has since become a common example in discussions of passive cooling.\n\n## Decline\n\nThe decline of the mangh is linked to the power station built by the British in the 1920s, which brought electricity to the city. Other suggested reasons are the lack of attention in town planning and education, the unsuitability of the device for mass housing, and a tendency to treat manghs as heritage rather than as working climate control.\n\n## Related forms\n\nThe mangh belongs to the wider family of windcatchers found from Egypt to the Persian Gulf and Iran; see *badgir*. Its distinguishing feature is that it is permanently aimed in a single direction.","key_facts":[{"label":"Location","value":"Hyderabad and southern Sindh, Pakistan"},{"label":"Orientation","value":"Fixed, facing the south-west summer breeze"},{"label":"Other name","value":"Badigar (southern Sindh)"},{"label":"City nickname","value":"Manghan jo Shahar, city of windcatchers"},{"label":"Decline","value":"From the 1920s, after electricity arrived"}],"regions":["South Asia"],"aliases":["mangh","manghs","badigar","Hyderabad windcatcher","Sindhi wind scoop"],"related":["badgir","roof-ventilation","flat-roof","roofing-in-pakistan","climate-change-and-roofing"],"company":null,"sources":[{"title":"Back to the Basics: Wind Catchers of Hyderabad","url":"https://www.thefridaytimes.com/2021/07/24/back-to-the-basics-wind-catchers-of-hyderabad/","publisher":"The Friday Times"},{"title":"Allegory of the sustainable city: the wind catchers of Hyderabad, Pakistan","url":"https://roesler.arc.usi.ch/publications/allegory-of-the-sustainable-city-the-wind-catchers-of-hyderabad-pakistan-and-their-spread-in-the-modern-architectural-discourse","publisher":"Universita della Svizzera italiana"}],"country":null},{"slug":"mansard-roof","title":"Mansard Roof","category":"roof-forms","type":"article","summary":"A mansard roof is a four-sided roof with two slopes on each face, the lower one steep and often pierced by dormers, the upper one shallow.","body":"A mansard roof is a hipped roof with a double slope on each of its four sides. The lower slope is very steep, sometimes nearly vertical and sometimes curved, and the upper slope is shallow and may be barely visible from the street. The steep lower slope creates almost a full storey of habitable space within the roof, typically lit by dormer windows. The horizontal line where the two slopes meet is the curb, and mansards and gambrels are both classed as curb roofs.\n\n## History\n\nThe earliest known example is on part of the Louvre in Paris, built by Pierre Lescot around 1550. The form takes its name from the French architect François Mansart (1598-1666), who did not invent it but used it extensively in the early 17th century; his great-nephew Jules Hardouin-Mansart continued the tradition.\n\nThe mansard became fashionable again during the French Second Empire (1852-1870) and Baron Haussmann's rebuilding of Paris from the 1850s. A popular story holds that mansards were built to avoid taxes on storeys or windows; the window tax dates from 1798 and did not exempt mansard windows, and a more plausible reason is that Paris height limits were measured to the cornice, so space within the roof did not count.\n\nIn the United States and Canada, the \"Second Empire\" style spread to public buildings, hotels, railway stations and houses from about the 1860s. In the 1960s and 1970s, flat-topped \"neo-mansard\" walls were used on commercial buildings, often to hide rooftop equipment.\n\n## Mansard versus gambrel\n\nBoth have two pitches per side. A mansard is sloped on all four sides (a curb hip roof), while a gambrel is sloped on two sides only and has gable ends (a curb gable roof). In France and Germany, \"mansard\" can refer to both forms and also to the attic room itself.\n\n## Construction and maintenance\n\nThe steep lower slopes are usually clad in slate, shingles, tiles or metal, and the shallow upper slope may need a membrane. The junctions at the curb and around numerous dormers need careful flashing. Mansards are popular in UK loft conversions and terrace extensions because they add space within planning limits.","key_facts":[{"label":"Earliest known example","value":"Louvre, Pierre Lescot, c. 1550"},{"label":"Named after","value":"François Mansart (1598-1666)"},{"label":"Revival","value":"French Second Empire (1852-1870)"},{"label":"Slopes per side","value":"Two"}],"regions":["Europe","North America","Global"],"aliases":["mansard","French roof","curb roof","Second Empire roof"],"related":["gambrel-roof","dormer","hip-roof","bonnet-roof"],"company":null,"sources":[{"title":"Mansard roof","url":"https://en.wikipedia.org/wiki/Mansard_roof","publisher":"Wikipedia"},{"title":"Second Empire/Mansard Style 1860 - 1900","url":"https://www.phmc.state.pa.us/portal/communities/architecture/styles/second-empire.html","publisher":"Pennsylvania Historical and Museum Commission"},{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"}],"country":null},{"slug":"maramures-church-roofs","title":"Maramureș Wooden Church Roofs","category":"world-roofing","type":"article","summary":"The steep shingle roofs and needle-like spires of the wooden churches of Maramureș, Romania, eight of which are on the UNESCO World Heritage List.","body":"The wooden churches of Maramureș in northern Romania are known for roofs that dominate their buildings: a massive, steep roof that seems to dwarf the log walls beneath, and a tall, slender bell tower rising from the western end. Built between the 17th and 19th centuries, they are among the most striking examples of timber roofing in Europe.\n\n## UNESCO listing\n\nIn 1999 UNESCO inscribed eight of the churches as the Wooden Churches of Maramureș, under criterion (iv): Bârsana, Budești, Desești, Ieud Hill, Plopiș, Poienile Izei, Rogoz and Șurdești. Almost 100 wooden churches still stand in the region, roughly a third of the number recorded two centuries ago.\n\n## Roof form\n\n- **Main roof:** a massive roof over the church body. Its scale gives the churches their characteristic silhouette.\n- **Bell tower:** a tall, narrow tower at the west end topped with a needle-like spire. At Șurdești, built in the 18th century on a stone base, the church is reported to be about 72 m (236 ft) high including a spire of about 54 m (177 ft). A new wooden church at Săpânța-Peri, a few miles away, is reported to be about 75 m (246 ft) high and is often described as the tallest wooden church in the world.\n\n## Shingles\n\nRomanian builders traditionally made roof shingles (*șindrilă*) of fir and fixed them to the laths with wooden pegs of yew. The two woods have different densities and respond differently to moisture, which was thought to help keep water from getting behind the shingles. In Maramureș, Moldavia and Wallachia shingle ends are traditionally rounded, while in Transylvania they are cut straight. The fan-like courses needed to cover curved and conical surfaces are harder to make watertight than straight courses.\n\n## Wider tradition\n\nSimilar roofing appears across the Carpathians: the Wooden Tserkvas of the Carpathian Region in Poland and Ukraine and the wooden churches of the Slovak Carpathians are also UNESCO-listed. In Moldavia, wooden roofs with broad eaves, up to about 2.7 m (9 ft) deep at Voroneț Monastery (1488), have helped protect painted exterior walls from the weather.\n\n## Maintenance\n\nShingle roofs and spires need periodic renewal. Tall spires are especially exposed to wind-driven rain and snow.","key_facts":[{"label":"UNESCO inscription","value":"1999, eight churches"},{"label":"Built","value":"17th-19th centuries"},{"label":"Shingle wood","value":"Fir, pegged with yew"},{"label":"Surviving churches","value":"Almost 100 in the region"}],"regions":["Europe"],"aliases":["Maramures churches","Maramureș wooden churches","Romanian wooden church roofs"],"related":["roofing-in-romania","wood-shingle","wooden-tserkva-roofs","wooden-churches-of-southern-malopolska","aspen-ploughshare-shingles","roofing-in-ukraine"],"company":null,"sources":[{"title":"Wooden churches of Maramureș","url":"https://en.wikipedia.org/wiki/Wooden_churches_of_Maramure%C8%99","publisher":"Wikipedia"},{"title":"Roofing in Romania: Lessons From the Past","url":"https://roofingmagazine.com/roofing-in-romania-lessons-from-the-past/3/","publisher":"Roofing Magazine"},{"title":"Wooden Churches of Maramureş","url":"https://whc.unesco.org/en/list/904/","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"marley","title":"Marley","category":"manufacturers","type":"company","summary":"Marley is a UK maker of concrete and clay roof tiles, battens and integrated solar roofing, now part of Marshalls.","body":"Marley is a British manufacturer of pitched-roof products, including concrete and clay roof tiles, timber battens, underlays and roof-integrated solar panels. The business is part of the UK landscaping and building-products company Marshalls.\n\n## Products\n\n- **Roof tiles**: concrete single-lap tiles and clay plain and single-lap tiles, including heritage-style products for conservation work (such as the Acme range).\n- **Battens and underlays**: timber roofing battens (for example its JB Red and Type A battens) and underlays.\n- **Solar**: SolarTile, an in-roof solar photovoltaic system designed to sit flush with surrounding tiles, together with inverters and battery storage.\n- **Roof systems and fittings**: accessories, fixings and fittings.\n- **Other**: cedar shingles and shakes, and Marley Weatherboard cladding.\n\nIn the UK, wind-uplift fixing of tiles is governed by BS 5534, which led manufacturers to supply tested mechanical fixing and dry-fix systems in place of mortar bedding.\n\n## History and ownership\n\nMarley's roofing interests were once international. In 1991 the British tile maker Redland bought Marley's US roof tile subsidiary for GBP 6.6 million. The UK Marley roofing business now operates within the Marshalls group, and the company's website describes Marley as part of Marshalls.\n\n## Context\n\nConcrete tiles, introduced in Britain in the early twentieth century, became the most common roof covering on new UK housing, while clay plain tiles remain important for traditional and listed buildings.\n\n## Solar roofing\n\nIn-roof (integrated) solar systems replace a section of tiles with panels mounted flush in the roof plane, using flashing kits to keep water out. They are an alternative to on-roof panels fixed above the tiles with hooks and rails.","key_facts":[{"label":"Country","value":"United Kingdom"},{"label":"Parent","value":"Marshalls"},{"label":"Products","value":"Concrete and clay tiles, battens, SolarTile"}],"regions":["Europe"],"aliases":["Marley Roofing"],"related":["concrete-roof-tile","clay-roof-tile","redland","roof-battens","building-integrated-photovoltaics","bs-5534"],"company":{"website":"https://www.marley.co.uk","parent":"Marshalls","known_for":["Concrete and clay roof tiles","Roofing battens","SolarTile in-roof solar"]},"sources":[{"title":"Marley","url":"https://www.marley.co.uk/","publisher":"Marley"},{"title":"Redland plc","url":"https://en.wikipedia.org/wiki/Redland_plc","publisher":"Wikipedia"}],"country":null},{"slug":"master-builders-australia","title":"Master Builders Australia","summary":"Master Builders Australia is the national federation of state and territory builders' associations, with roots over 130 years old and about 32,000 members.","body":"Master Builders Australia is the national peak body for the building and construction industry in Australia. It is a federation of eight state and territory Master Builders Associations, covering New South Wales, Victoria, Queensland, South Australia, Western Australia, Tasmania, the Northern Territory and the Australian Capital Territory. The organisation says it has been building Australia for more than 130 years, and its national office is in Barton, Canberra. Its website is masterbuilders.com.au.\n\n## Role\n\nMaster Builders Australia describes itself as the national voice of the building and construction industry, which it values at about A$200 billion. It represents around 32,000 member businesses nationwide, from small builders and trade contractors to large construction companies. Its work includes:\n\n- advocating to the federal government on industrial relations, taxation, building regulation, skills and housing policy;\n- contributing to the National Construction Code (NCC) and Australian Standards;\n- supporting state associations, which deliver most direct member services such as contracts, training, legal advice and building awards.\n\n## Roofing connections\n\nRoofing contractors and roof plumbers in Australia are often members of their state Master Builders Association or of specialist roofing associations, some of which are affiliated with state Master Builders bodies. State associations run awards and training programmes that include roofing work.\n\n## Australian roofing context\n\nAustralia's dominant roof coverings are coated steel sheet (such as corrugated and trapezoidal profiles) and concrete and terracotta tiles. Key standards include AS 1562.1 for metal roof and wall cladding and AS 2050 for installation of roof tiles. Bushfire-prone areas have additional requirements under AS 3959.\n\nContractor licensing is handled by each state and territory, not nationally. Roofing and roof plumbing may require a licence depending on the state and the type and value of work. Consumers should check with their state building or fair trading regulator before hiring a roofer.","key_facts":[{"label":"Type","value":"National federation of state and territory builders' associations"},{"label":"Members","value":"About 32,000"},{"label":"National office","value":"Barton, Canberra"},{"label":"History","value":"More than 130 years"}],"regions":["Oceania"],"aliases":["MBA","Master Builders"],"related":["how-to-find-a-licensed-roofer","national-construction-code-australia","roofing-association-of-new-zealand"],"company":{"headquarters":"Canberra, Australia","website":"https://www.masterbuilders.com.au","known_for":["National building industry advocacy in Australia"]},"sources":[{"title":"About us","url":"https://www.masterbuilders.com.au/about-us/","publisher":"Master Builders Australia"},{"title":"mrcaa.com.au home page (affiliate of MBA NSW)","url":"https://www.mrcaa.com.au/","publisher":"MRCAA"}],"category":"organizations","type":"organization","country":null},{"slug":"mastic-asphalt-roofing","title":"Mastic Asphalt Roofing","category":"low-slope-systems","type":"article","summary":"A traditional UK and European flat-roof waterproofing of hot bitumen and fine mineral aggregate, spread by hand into a seamless, monolithic layer.","body":"Mastic asphalt is a dense, void-free mixture of bitumen and finely graded mineral aggregate, typically limestone, that is heated until it is fluid and then spread by hand with wooden floats. On cooling it forms a hard, seamless and fully monolithic waterproof layer. It has been used for roofs, balconies, car parks and tanking in Britain and continental Europe since the nineteenth century, when natural rock asphalts from sites such as Seyssel in France were first used for paving in the 1820s and 1830s.\n\n## How it is laid\n\nThe material is delivered as blocks or hot in mixers, heated on site in cauldrons or mixers, and carried to the roof in buckets. The asphalter spreads it in successive coats over an isolating underlay, usually a loose-laid sheathing felt that separates the asphalt from the deck and lets each move independently. Upstands and skirtings are formed in the same material so the roof, edges and details are one continuous piece. A solar-reflective finish such as chippings or a coating is usually applied to reduce heat gain and surface crazing.\n\n## Characteristics\n\n- **Seamless and monolithic:** no laps or seams, which suits complex shapes and detailing.\n- **Hard-wearing:** can take foot traffic and, in paving grades, vehicles; widely used on podiums and car-park decks.\n- **Durable:** long service lives are reported where well maintained.\n- **Heavy and rigid:** needs a stable deck, typically concrete; less able to accommodate movement than flexible membranes.\n- **Hot work:** application involves heating to high temperatures.\n\n## Current use\n\nMastic asphalt remains an established UK flat roofing method for new build and refurbishment, often in inverted and podium roofs, and in balconies and walkways. Its market share has declined as reinforced bitumen membranes, single-ply and liquid systems have grown.","key_facts":[{"label":"Composition","value":"Bitumen plus fine limestone aggregate"},{"label":"Application","value":"Hot, hand-floated in coats over a sheathing underlay"},{"label":"Main regions","value":"UK and continental Europe"},{"label":"Key feature","value":"Seamless, monolithic, trafficable"}],"regions":["Europe"],"aliases":["mastic asphalt","asphalt roofing (UK)","poured asphalt"],"related":["hot-melt-rubberized-asphalt","reinforced-bitumen-membrane","flat-roof","protected-membrane-roof"],"company":null,"sources":[{"title":"BS 6229:2018 and flat roofing systems","url":"https://ikogroup.co.uk/?p=820","publisher":"IKO"},{"title":"What is the minimum drainage falls for a single ply flat roof?","url":"https://ikogroup.co.uk/?p=829","publisher":"IKO"},{"title":"Flat roof","url":"https://www.designingbuildings.co.uk/wiki/Flat_roof","publisher":"Designing Buildings Wiki"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"Asphalt concrete (history of asphalt mastic)","url":"https://en.wikipedia.org/wiki/Mastic_asphalt","publisher":"Wikipedia"}],"country":null},{"slug":"matmata-troglodyte-houses","title":"Matmata Troglodyte Houses","category":"world-roofing","type":"place","summary":"Underground pit dwellings in southern Tunisia: rooms carved around a large open pit, so the ground itself forms the roof.","body":"The troglodyte houses of Matmata in southern Tunisia are a rare case of dwellings without a built roof. Instead of raising walls and spanning them, Amazigh (Berber) builders dug a large pit into the ground and carved rooms into its sides, leaving the undisturbed earth above as the roof.\n\n## Form\n\nEach house is centred on a large open pit that acts as a courtyard. Artificial caves dug into the pit's perimeter serve as rooms. Larger homes have several pits connected by trench-like passageways.\n\n## Strengths and weaknesses\n\nThe main weakness of the type is water. In 1969, intensive rains lasting 22 days flooded the pit houses and caused many to collapse. Aid was organised after a delegation went to Gabès, and a new above-ground settlement was built. Only a few families moved to the new surface houses; most rebuilt their underground homes.\n\n## Roofing significance\n\nIn roofing terms, the pit house does without timber, tiles or any waterproof covering: the earth left above each room is both structure and roof. The trade-off is drainage. Water that collects in the open pit or soaks into the ground above has no easy way out, which is why prolonged rain, as in 1969, is the type's greatest threat.\n\n## Film fame\n\nThe Hotel Sidi Idriss, built as a traditional troglodyte dwelling, was used in 1976 as Luke Skywalker's home on the planet Tatooine in *Star Wars* and appeared again in *Attack of the Clones* (2002), bringing international attention to the house type.\n\n## Related forms\n\nMatmata belongs to a wider North African tradition of building into the ground and with earth. The island of Djerba also has troglodytic structures, including inland mosques that served as refuges.","key_facts":[{"label":"Location","value":"Matmata, southern Tunisia"},{"label":"Roof","value":"Undisturbed ground above carved rooms"},{"label":"Main hazard","value":"Flooding (1969 rains lasted 22 days)"}],"regions":["Africa"],"aliases":["Matmata pit houses","Berber troglodyte dwellings"],"related":["roofing-in-tunisia","roofing-in-north-africa","sod-roof","mud-roof"],"company":null,"sources":[{"title":"Matmata, Tunisia","url":"https://en.wikipedia.org/wiki/Matmata,_Tunisia","publisher":"Wikipedia"},{"title":"Djerba: Testimony to a settlement pattern in an island territory","url":"https://whc.unesco.org/en/list/1640/","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"maya-thatched-house","title":"Maya Thatched House","category":"world-roofing","type":"article","summary":"The pole-and-thatch house of the Maya world, roofed with palm leaves or grass, used from ancient times to the present in Mexico and Central America.","body":"The Maya thatched house is the everyday dwelling of the Maya region of southern Mexico, Guatemala, Belize, Honduras and El Salvador: a timber or pole frame with walls of poles, wattle or clay, under a steep roof of palm leaves or grass. In Yucatec and Mopan Maya the word for house is *naj* (also written *na* or *nah*); a temple pyramid could be called *k'uj naj*, a dwelling of deities.\n\n## Ancient houses\n\nWhile stone palaces and temples survive at sites such as Tikal and Copán, most ancient Maya people lived in houses of perishable materials. A Cambridge University Press study of everyday Classic Maya life describes middle-ranking homes on small platforms with wooden walls and thatched roofs, and the simplest homes at ground level with packed dirt floors. Wall poles were lashed together with agave twine, and roofs of palm fronds were tied on with agave-fibre rope. These materials were easy to gather and quick to repair, but a stray spark in the dry season could set a roof alight.\n\nArchaeologists at the Paynes Creek salt works in Belize, where waterlogged posts survive, describe pole-and-thatch buildings as probably the dominant form of construction in the prehistoric Maya area. The posts there came from palmetto palm, mangrove, buttonwood and hardwoods, and canoes probably carried posts and palm thatch to the site. At Joya de Cerén in El Salvador, ash from an eruption around 600 CE preserved thick thatch roofs with deep eaves over earthen walls.\n\nThe stone corbel vault of Maya temples and palaces, in which courses of stone step inward until they meet, is often said to imitate the steep profile of the thatched hut. It needed very thick walls and gave little interior width.\n\n## Construction\n\nA study by Reed College of houses near Labná in Yucatán records frame members that are notched and lashed with local vines: main posts, crossbeams, A-frame posts and a wall plate, with two main A-frame poles carrying the ridge pole at a rounded (apsidal) end. Walls were pole-and-stick frames covered with red clay, on a lime-mortar base where the clay met the ground. Roofs were thatched with plaited palm, and one new roof had a metal ridge cover.\n\n## Thatch materials\n\nThe plants used vary by region. FLAAR, a foundation that documents Maya ethnobotany, identifies *guano* palm (*Sabal mayarum*) as the main thatch palm of the Petén around Tikal, Uaxactún and Lake Yaxhá in Guatemala; corozo or cohune palm as the usual thatch of Q'eqchi' houses; and *junco* (*Carludovica palmata*), which is not a true palm, in Alta Verapaz. Grasses and sedges are also used. In Toledo District, Belize, builders distinguish durable bay leaf palm, which grows only in well-forested areas and may take up to ten years to produce usable leaves, from the cheaper and less durable cohune palm of disturbed land.\n\n## Today\n\nThatched houses persist mainly in rural and Indigenous communities and in tourism buildings, alongside metal sheet and concrete. Guatemala's 2018 census counted 1.7% of homes with straw, palm or similar roofs, against 68.1% with metal sheet.","key_facts":[{"label":"Region","value":"Southern Mexico, Guatemala, Belize, Honduras, El Salvador"},{"label":"Maya term","value":"naj (house), Yucatec and Mopan Maya"},{"label":"Roof","value":"Palm leaf or grass thatch on lashed poles"},{"label":"Common palms","value":"Guano (Sabal), cohune, bay leaf"},{"label":"Earliest direct evidence","value":"Joya de Cerén, about 600 CE"}],"regions":["Latin America"],"aliases":["naj","na","nah","Maya hut","Maya pole-and-thatch house"],"related":["palm-thatch","thatch","palapa","joya-de-ceren","roofing-in-guatemala","roofing-in-belize","roofing-in-mexico","roofing-in-honduras"],"company":null,"sources":[{"title":"Everyday Life in the Classic Maya World: Domestic world","url":"https://core-prod.cambridgecore.org/core/books/everyday-life-in-the-classic-maya-world/domestic-world/6B4D1679CC65B2858F7EA6673F4F2B3D","publisher":"Cambridge University Press"},{"title":"Maya architecture","url":"https://en.wikipedia.org/wiki/Maya_architecture","publisher":"Wikipedia"},{"title":"What is used to thatch houses of the Mayan people?","url":"https://www.maya-archaeology.org/maya-architecture-houses-buildings-temples-palaces-pyramid-structure/guano-huano-junco-palm-thatch-mayan-house-architecture-qeqchi-kekchi-kala-alta-verapaz.php","publisher":"FLAAR (maya-archaeology.org)"},{"title":"Labná: typical Yucatec Maya thatched domestic hut","url":"https://www.reed.edu/uxmal/galleries/Thumbnails/Labna/Labna-Huts-1.htm","publisher":"Reed College"},{"title":"naj (Mopan and Yucatec Maya)","url":"https://kaweah.freedombox.rocks/kiwix/wiktionary_en_all_maxi_2023-04/naj","publisher":"Wiktionary (mirror)"},{"title":"Focusing on individual wooden buildings ... at the Paynes Creek Salt Works (Research Reports in Belizean Archaeology 18)","url":"https://par.nsf.gov//servlets/purl/10526553","publisher":"NSF Public Access Repository"},{"title":"Building with thatch","url":"https://ambergriscaye.com/pages/mayan/building-with-thatch.html","publisher":"Ambergris Caye (The Lodge at Big Falls)"},{"title":"Datos del censo presentan dura realidad para los guatemaltecos","url":"https://lahora.gt/?p=284086","publisher":"La Hora"}],"country":null},{"slug":"mcelroy-metal","title":"McElroy Metal","category":"manufacturers","type":"company","summary":"McElroy Metal is an employee-owned US maker of metal roofing and wall systems, founded in 1963 and headquartered in Bossier City, Louisiana.","body":"McElroy Metal is a US manufacturer of metal roofing, wall panels and components, headquartered in Bossier City, Louisiana. It was founded in 1963 by Thomas E. McElroy Sr. and was led by three generations of the family before becoming employee-owned through an Employee Stock Ownership Plan (ESOP) in 2022.\n\n## History\n\n- **1963**: Founded by Thomas E. McElroy Sr.\n- **1975**: Tem McElroy becomes the second-generation president.\n- **1976**: First satellite manufacturing plant, in Clinton, Illinois.\n- **1983**: Acquisition of Angle Steel and a new plant in Marshall, Michigan.\n- **1985**: First Metal Mart retail location.\n- **1990**: A plant in Adelanto, California makes the company national in scope.\n- **1995**: Acquisition of Pioneer Metals and a plant in Lewisport, Kentucky.\n- **2007**: Ian McElroy becomes third-generation president.\n- **2009**: Acquisitions of Components Plus (Sunnyvale, Texas) and Met-Tile.\n- **2012**: Acquisition of Architectural Building Components (Houston) and a joint venture with Green Span Profiles for insulated metal panels.\n- **2018**: Thirteenth plant opens in Diamond, Missouri.\n- **2022**: A fourteenth plant is announced in Lockhart, Texas, and the company becomes an ESOP.\n\n## Footprint\n\nThe company reports 14 manufacturing facilities, about 30 service centres and 44 Metal Mart stores across the US. It has installed rooftop solar systems at some of its own plants, including a 500 kW array at Peachtree City, Georgia in 2013.\n\n## Products\n\nMcElroy makes standing seam roof systems (for example the Maxima and 138T/238T profiles), exposed-fastener roof and wall panels, insulated metal panels, slit coil and flat sheet, soffit, fascia and canopy products, structural components, and cold-formed steel building frames. Its products are used on commercial, industrial, agricultural and residential buildings, including retrofit roofs installed over existing low-slope roofs.","key_facts":[{"label":"Founded","value":"1963"},{"label":"Founder","value":"Thomas E. McElroy Sr."},{"label":"Headquarters","value":"Bossier City, Louisiana, US"},{"label":"Ownership","value":"Employee-owned (ESOP, 2022)"},{"label":"Plants","value":"14"}],"regions":["North America"],"aliases":["McElroy Metal Mill","McElroy"],"related":["standing-seam-metal-roof","through-fastened-metal-panels","metal-roofing"],"company":{"founded":"1963","headquarters":"Bossier City, Louisiana, United States","website":"https://www.mcelroymetal.com","known_for":["Standing seam roof systems","Metal wall panels","Metal Mart stores"]},"sources":[{"title":"About McElroy Metal","url":"https://www.mcelroymetal.com/about-us","publisher":"McElroy Metal"},{"title":"McElroy Metal","url":"https://www.mcelroymetal.com/","publisher":"McElroy Metal"}],"country":null},{"slug":"power-seamer","title":"Mechanical and Electric Seamers","category":"tools-equipment","type":"term","summary":"Motorised or hand-cranked machines that travel along standing seam metal roof panels, folding the seams into single or double locks.","body":"Mechanical seamers close the seams of mechanically seamed standing seam metal roofs. After the panels are installed with their vertical legs overlapping, the seamer is placed on the seam and travels along it, using a series of rollers to fold the legs together. Electric (power) seamers are driven by a motor; manual mechanical seamers are pushed or cranked by hand. Both produce a more consistent and faster seam than hand seaming over long panel runs.\n\n## Single and double lock\n\n- A **single-lock (90-degree)** seam folds the panel legs over once.\n- A **double-lock (180-degree)** seam folds them a second time, locking the legs together more tightly and giving greater resistance to water and wind uplift.\n\nSome seamers form both stages in one pass, others in two passes, and some double-lock systems use separate first-stage and finishing seamers. Hand seamers designed for each stage are used at the ends of panels, at details, and where the machine cannot start or finish.\n\n## Matching to the profile\n\nSeamers are almost always profile-specific. Each panel manufacturer's seam has its own height, leg geometry and clip design, so the seamer must be the model specified for that panel. Using the wrong machine can form a poor seam, damage the coating or fail to engage the clips. Panel suppliers often rent or lend compatible seamers.\n\n## Use\n\n- Hand-crimp the start of the seam so the machine can engage.\n- Set the seamer on the seam and let it run upslope or downslope as recommended, keeping power cords managed and clear of the operator.\n- Inspect the finished seam for full engagement along the length and at clips.\n- Finish ends and details with hand tools.\n\n## Safety and care\n\nSeamers are heavy and can pull themselves along the roof, so operators are tied off with fall protection, and the machine may be tethered on steep slopes. Rollers should be kept clean and adjusted to avoid scratching painted metal. Electric models need appropriate power supply and cord protection, often from a generator on site.","key_facts":[{"label":"Seam types","value":"Single-lock (90 degree) and double-lock (180 degree)"},{"label":"Key requirement","value":"Seamer must match the panel profile"},{"label":"Finishing","value":"Hand seamers at panel ends and details"}],"regions":["Global"],"aliases":["electric seamer","power seamer","mechanical seamer","roof seamer"],"related":["standing-seam-metal-roof","hand-seamer","portable-roll-former","hemming-tool","seam-failure"],"company":null,"sources":[{"title":"ESE K9 Double Lock Power Seamer","url":"https://bigrocksupply.com/store/p/8498-ESE-K9-Double-Lock-Power-Seamer.aspx","publisher":"Big Rock Supply"},{"title":"ESE 099-700 Top Double Lock Second Stage Hand Seamer","url":"https://www.bigrocksupply.com/ese-099-700-11/16-top-double-lock-second-stage-hand-seamer.aspx","publisher":"Big Rock Supply"},{"title":"US8336178B2 - Roof panel seaming apparatus","url":"https://patents.google.com/patent/US8336178","publisher":"Google Patents"},{"title":"5 standing seam tools to do kick ass work","url":"https://www.stortz.com/5-standing-seam-tools-kick-ass-work/","publisher":"John Stortz & Son"}],"country":null},{"slug":"mechanical-seaming","title":"Mechanical Seaming","category":"installation","type":"term","summary":"Mechanical seaming folds the raised edges of adjoining metal roof panels together with a hand or powered seamer, forming single-lock or double-lock seams.","body":"**Mechanical seaming** is the joining of standing seam metal panels by folding their mating edges together with a tool. The result is a continuous, folded joint that is more weather resistant than a snap-together seam and allows the panels to be used on lower slopes.\n\n## Seam forms\n\n- **Single lock (90 degree).** The upper edge is folded once over the adjoining edge.\n- **Double lock (180 degree).** The fold is turned a second time so the edges are locked tightly together, the form traditionally used on copper and zinc roofing in Europe.\n- **Triple or 360-degree locks.** Some proprietary systems roll the seam further for additional water resistance.\n\nDouble-lock seams are generally the most weather resistant and the most expensive of the common standing seam types.\n\n## Tools\n\n- **Hand seamers and tongs.** Used to start seams, finish ends and work around details.\n- **Powered (electric) seamers.** Machines that run along the seam, folding it in one or more passes. They are matched to the specific panel profile.\n- **Hand seaming tools for traditional work.** On copper and zinc roofs in Europe, seams are often closed by hand with specialised tongs and mallets.\n\n## Use on low slopes\n\nCanadian guidance notes that most architectural metal roofs are designed for slopes of 1:4 (3:12) or steeper, and that below that a machine- or mechanically-seamed standing seam is required, with seam sealant or tape adding to the seam's water resistance. Panel manufacturers publish their own minimum slopes for each seam type.\n\n## Practice notes\n\nSeams are usually started by hand at the eave, then run with the seamer toward the ridge. Clips must be engaged in the seam before it is closed. Because the seamer is profile-specific, using the wrong tool can distort the seam and void the manufacturer's warranty. Mechanically seamed roofs are harder to dismantle and repair than snap-lock roofs, since seams must be opened with special tools.","key_facts":[{"label":"Seam forms","value":"Single lock, double lock, proprietary 360-degree"},{"label":"Tools","value":"Hand seamers, powered seamers"},{"label":"Low-slope use (Canada)","value":"Required below 1:4 (3:12) for most systems"}],"regions":["Global"],"aliases":["roof seaming","double-lock seam","single-lock seam","seamer"],"related":["standing-seam-installation","standing-seam-clips","standing-seam-metal-roof","copper-roofing","zinc-roofing"],"company":null,"sources":[{"title":"Standing seam metal roof","url":"https://en.wikipedia.org/wiki/Standing_seam_metal_roof","publisher":"Wikipedia"},{"title":"Canadian Roofing Reference Manual: 10.8 Metal Roofing Application","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-10-metal-roofing/10-8-application/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 10.5 Seam Types","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-10-metal-roofing/10-5-seam-types/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"mechanically-attached-roof-system","title":"Mechanically Attached Roof System","category":"low-slope-systems","type":"term","summary":"A low-slope roof in which the membrane is secured to the deck with screws and plates or bars, typically placed in the sheet laps.","body":"In a mechanically attached roof system, the membrane is held down by fasteners driven through it into the structural deck. Most often the fasteners and plates (or continuous metal bars) are placed in the overlap of each seam, so the next sheet covers them and the seam is welded or taped over the top.\n\n## Variations\n\n- **In-seam (lap) fastening:** fasteners along one edge of each sheet, covered by the next sheet's lap. This is the most common method for TPO.\n- **Strip or bar attachment:** continuous bars in or over the seams, or across the field with cover strips.\n- **Point attachment:** individual plates through the sheet with cover patches.\n- **Induction welding:** coated plates under the membrane, bonded by induction heat, with no penetrations.\n\nInsulation is usually fastened separately with its own screws and plates, or held by the same fasteners.\n\n## Wind design\n\nFastener spacing and sheet width are set by wind-uplift calculations. Because suction is highest at roof corners and perimeters, these zones use narrower half-sheets or closer fastener spacing. In North America assemblies are tested and listed by FM Approvals and UL, and fastener pull-out strength in existing decks can be checked with the ANSI/SPRI FX-1 field test.\n\n## Advantages and limitations\n\nMechanical attachment is fast, lightweight, works in cold weather when adhesives struggle, and suits steel decks. Its drawbacks include \"billowing\", where wind lifts the sheet between fastener rows and draws interior air into the roof, possible fastener back-out, and the need for a deck with adequate pull-out strength. Steel deck must be thick enough to hold screws, and some concrete or gypsum decks need special fasteners.","key_facts":[{"label":"Fastener location","value":"Usually in sheet laps"},{"label":"Common membranes","value":"TPO, PVC, EPDM, modified bitumen base sheets"},{"label":"Field fastener test","value":"ANSI/SPRI FX-1"},{"label":"Known issue","value":"Membrane billowing in wind"}],"regions":["Global"],"aliases":["mechanically fastened roof","mechanically fixed single ply","MA system"],"related":["induction-welding-roofing","ballasted-roof-system","fully-adhered-roof-system","tpo-roofing","roof-deck"],"company":null,"sources":[{"title":"Technical Details: Thermoset Membranes - EPDM Technology and Repair","url":"https://roofingcontractor.com/articles/85516-technical-details-thermoset-membranes-epdm-technology-and-repairp","publisher":"Roofing Contractor"},{"title":"Thermoplastic Polyolefin (TPO) Roofing Systems","url":"https://buildings.com/articles/35297/thermoplastic-polyolefin-tpo-roofing-systems","publisher":"Buildings"},{"title":"Rules for long-lasting BUR systems (H. H. Pierce, Interface, Oct 2006)","url":"https://iibec.org/wp-content/uploads/2006-10-Pierce.pdf","publisher":"IIBEC"},{"title":"Cool Roofs","url":"https://www.energy.gov/energysaver/cool-roofs","publisher":"U.S. Department of Energy"},{"title":"Standards","url":"https://www.spri.org/standards/","publisher":"SPRI"}],"country":null},{"slug":"mechanically-seamed-standing-seam","title":"Mechanically Seamed Standing Seam (Single and Double Lock)","category":"installation","type":"article","summary":"Mechanically seamed panels have their raised seams folded together on the roof by a seaming tool, forming single-lock or watertight double-lock joints.","body":"In a mechanically seamed standing seam roof, neighbouring panels are first engaged loosely over concealed clips, and then a hand tool or electric seaming machine is run along each seam to fold the metal edges around each other. The fold locks the panels and the clip tabs together.\n\n## Single lock and double lock\n\n- **Single lock (90 degree)**: the seam is folded once. It is quicker to form and easier to undo but less resistant to water standing against the seam.\n- **Double lock (180 degree)**: the seam is folded a second time, producing a compact, multi-layer joint. A typical copper specification calls for a \"5-ply\" double lock finished about 1 in (25 mm) high. Double-lock seams are the usual choice for low slopes and for areas with heavy snow or wind-driven rain.\n\nTraditional European zinc and copper roofs use the same principle, with the double-lock standing seam (sometimes called a double welt) formed by hand tools; an angled variant, the angle seam, is folded only part-way and is mainly used on steeper roofs and facades.\n\n## Advantages\n\n- High weathertightness because the folded, locked seams resist water entry without relying on sealants alone.\n- Strong resistance to wind uplift: the folded seam grips the clips firmly, and many engineered systems with mechanical seams achieve high uplift ratings in tests such as ASTM E1592 or UL 580.\n- Suitable for long panels with sliding clips.\n\n## Trade-offs\n\n- Mechanically seamed systems are generally the most expensive standing seam type because of the extra labour and equipment.\n- Seaming tools must match the panel profile.\n- Repairs require unseaming and reseaming.","key_facts":[{"label":"Seam types","value":"Single lock (90 degrees), double lock (180 degrees)"},{"label":"Typical copper double lock","value":"5-ply, about 1 in (25 mm) high"},{"label":"Best suited to","value":"Low slopes, high wind, heavy snow"}],"regions":["Global"],"aliases":["double lock standing seam","single lock standing seam","double welt","mechanical seam","angle seam"],"related":["standing-seam-metal-roof","snap-lock-standing-seam","standing-seam-clips","wind-uplift-testing-metal-roofs"],"company":null,"sources":[{"title":"Section 07 61 16 Sheet Metal Roofing (VA master specification)","url":"https://www.wbdg.org/FFC/VA/VANCAS/VANCA076116.pdf","publisher":"Whole Building Design Guide / U.S. Department of Veterans Affairs"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Myths About Metal Roofing: Heat, Wind and Lightning","url":"https://www.mbci.com/blog/myths-about-metal-roofing/","publisher":"MBCI"},{"title":"Standing Seam Types: Snap-Lock vs Mechanical Seam Explained","url":"https://www.interlockroofing.com/kb/standing-seam-types-snap-lock-vs-mechanical-seam/","publisher":"Interlock Roofing"},{"title":"What Is a Standing Seam Metal Roof? Definition, Pros & Costs","url":"https://www.interlockroofing.com/glossary/standing-seam-system/","publisher":"Interlock Roofing"}],"country":null},{"slug":"medieval-lead-roofs","title":"Medieval Lead Roofs","category":"history","type":"article","summary":"Sheet lead was the prestige covering for medieval cathedrals, abbeys and halls in Europe, valued for its watertightness and ease of shaping.","body":"Lead was the premium metal roofing material of medieval Europe. Cathedrals, abbey churches, royal halls and castle towers were covered in heavy sheets of cast lead laid over timber boarding. Many survive or have been relaid, and lead remains the traditional covering for low-pitched church roofs in Britain and northern Europe.\n\n## Roman background\n\nThe Romans had already exploited lead widely. It was cheap, as a by-product of silver smelting, and its low melting point made it easy to cast into sheets and pipes. In Rome, when the bronze tiles of the Pantheon were stripped and shipped to Constantinople in 663, Pope Gregory III (731-741) later re-covered the roof with lead sheets.\n\n## Medieval use\n\nLead can be shaped over curves and junctions and joined watertight, which made it suitable for domes, spires and low-pitched church roofs. Medieval craftsmen also gilded, painted or tinned lead on domes, lanterns and spires. Major examples include:\n\n- **Westminster Hall, London:** the hammerbeam roof built from 1393 carried about 176 tons of lead.\n- **Notre-Dame de Paris:** before the 2019 fire, the roof and spire carried more than 400 tonnes of lead over 13th-century oak.\n\n## Loss and recycling\n\nLead's value made it a target. During the Dissolution of the Monasteries in England in the 1530s and 1540s, monastic roofs were stripped and the lead recast for secular buildings, leaving many abbeys roofless ruins. Theft of church roof lead remains a problem today.\n\n## Sheet thickness\n\nTraditional British practice described lead by weight per square foot. The modern Lead Sheet Association codes still follow this: Code 6, for example, weighs about 6 lb per sq ft (roughly 29 kg/m²).\n\n## Revival\n\nDecorative leadwork largely moved to country houses after the 1630s, then revived in the late 19th century under Arts and Crafts architects. Sand-cast lead, made by pouring molten metal over a bed of sand, is still produced for conservation work.","key_facts":[{"label":"Westminster Hall lead","value":"About 176 tons"},{"label":"Notre-Dame roof lead (pre-2019)","value":"Over 400 tonnes"},{"label":"Code 6 lead","value":"About 6 lb/sq ft (about 29 kg/m²)"}],"regions":["Europe"],"aliases":["lead roofing history","cathedral lead roofs"],"related":["westminster-hall-roof","notre-dame-de-paris-roof-fire","pantheon-dome","lead-roofing","history-of-copper-roofs"],"company":null,"sources":[{"title":"Church Leadwork","url":"https://buildingconservation.com/articles/churchleadwork/churchleadwork.htm","publisher":"The Building Conservation Directory"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"The hammer-beam roof","url":"https://webtest.parliament.uk/about/living-heritage/building/palace/westminsterhall/architecture/the-hammer-beam-roof-","publisher":"UK Parliament"},{"title":"Pantheon, Rome","url":"https://en.wikipedia.org/wiki/Pantheon,_Rome","publisher":"Wikipedia"},{"title":"Notre-Dame fire","url":"https://en.wikipedia.org/wiki/Notre-Dame_fire","publisher":"Wikipedia"}],"country":null},{"slug":"membrane-shrinkage","title":"Membrane Shrinkage","category":"problems-maintenance","type":"term","summary":"Permanent loss of size in some single-ply roof membranes, which can pull on flashings, tear seams and lift edges.","body":"Membrane shrinkage is a permanent reduction in the dimensions of a roof membrane over time. It is different from the normal, reversible expansion and contraction caused by temperature. Shrinkage has been most widely documented in EPDM (ethylene propylene diene monomer) rubber membranes, though dimensional change can affect other sheet materials too.\n\n## How it shows up\n\nAs the membrane slowly gets smaller, it pulls against wherever it is held: perimeter edges, curbs, walls, drains and penetrations. Typical signs include:\n\n- **Bridging** or **tenting**, where the membrane spans across an inside corner (for example where the roof meets a parapet) instead of lying tight into the angle.\n- Base flashings pulled away from walls or curbs, sometimes with the edge securement detached.\n- Stress at seams and splices, which can open.\n- Membrane pulled tight across drains and penetrations.\n\nThe EPDM Roofing Association has described bridging at angle changes in some loose-laid applications, and the problem has been observed most commonly on loosely laid, ballasted systems and on some mechanically attached ones.\n\n## Why it matters\n\nShrinkage-related failures often occur at the perimeter and details, where leaks are hard to trace. Water can travel through the insulation before appearing inside, so the insulation may be saturated by the time a leak is noticed. This is a particular risk in recover projects where the new membrane is installed over existing roofing.\n\n## Remedies\n\nResponses range from isolated repairs at pulled flashings to full replacement. Repairs typically involve releasing and re-securing the membrane edge, adding strips of new membrane or flashing to relieve tension, and adding perimeter restraint. Industry commentary has warned that repeated patch repairs treat symptoms rather than causes. Prevention focuses on adequate membrane restraint at edges and details at installation. Owners of older single-ply roofs should include perimeter and corner details in routine inspections.","key_facts":[{"label":"Most documented in","value":"EPDM single-ply membranes"},{"label":"Typical symptom","value":"Bridging or tenting at walls and curbs"},{"label":"Risk area","value":"Perimeters, curbs, penetrations, seams"}],"regions":["Global"],"aliases":["EPDM shrinkage","bridging","tenting"],"related":["epdm-roofing","single-ply-roofing","seam-failure","roof-moisture-survey"],"company":null,"sources":[{"title":"EPDM Membrane Shrinkage","url":"https://iibec.org/publication-post/epdm-membrane-shrinkage/","publisher":"IIBEC"},{"title":"What is the cause of bridging that has been seen in the past at angle changes in some EPDM loose-laid applications?","url":"https://epdmroofs.org/faq/what-is-the-cause-of-bridging-that-has-been-seen-in-the-past-at-angle-changes-in-some-epdm-loose-laid-applications/","publisher":"EPDM Roofing Association"},{"title":"Understanding and Inspecting EPDM Roofing, Part 1","url":"https://www.homeinspector.org/reporter-articles/understanding-and-inspecting-epdm-roofing-part-1","publisher":"ASHI Reporter"}],"country":null},{"slug":"metal-construction-association","title":"Metal Construction Association (MCA)","summary":"The MCA is a North American trade association that promotes metal in building construction, launched in 1983 in Illinois.","body":"The Metal Construction Association (MCA) is a trade association for companies that make and supply metal products used in building construction in North America, including metal roof and wall panels, metal composite material, insulated metal panels and coil coatings. It was launched on 1 June 1983 as a successor to the defunct Metal Building Component Manufacturers Association, and it is based in Illinois. Some sources give 1984, when operations were fully under way, as its starting year.\n\n## Mission and activities\n\nMCA works to expand the use of metal in construction through marketing, education, technical work and advocacy on public policy. Its main areas include:\n\n- **Technical resources.** The association publishes technical bulletins and guides on topics such as panel attachment, wind uplift, thermal performance and corrosion for designers and contractors.\n- **Certification programs.** MCA operates certification programs for metal construction products, including a roofing certification and a certification for fabricators of metal composite material (MCM) wall systems.\n- **Education.** It offers online courses through MCA Metal University, aimed at architects and other building professionals.\n- **Meetings.** MCA is linked with METALCON, a trade show for the metal construction industry, and holds winter and summer member meetings.\n- **Research.** It funds research with outside organisations, for example on energy performance and resilience of metal building envelopes.\n\n## Related initiatives\n\nIn 2002 MCA joined the Steel Coalition, and in 2004 it launched The Metal Initiative to inform commercial building decision makers. In 1998 it helped set up the Metal Roofing Alliance, a separate but closely aligned group focused on residential metal roofing.\n\n## Relevance to roofing\n\nMetal roofing ranges from exposed-fastener corrugated sheets to standing seam systems and stamped metal shingles. MCA's technical work helps define how these products are tested and installed in North America, alongside standards from ASTM, UL and building codes.","key_facts":[{"label":"Launched","value":"1 June 1983"},{"label":"Country","value":"United States (Illinois)"},{"label":"Predecessor","value":"Metal Building Component Manufacturers Association"},{"label":"Spin-off","value":"Metal Roofing Alliance (1998)"}],"regions":["North America"],"aliases":["MCA"],"related":["metal-roofing-alliance","standing-seam-metal-roof","metal-roofing"],"company":{"founded":"1983","website":"https://www.metalconstruction.org","known_for":["Metal construction technical bulletins","Product certification programs","MCA Metal University"]},"sources":[{"title":"Celebrating 40 Years of MCA","url":"https://www.metalconstruction.org/index.php/about/40th-anniversary","publisher":"Metal Construction Association"},{"title":"Metal Construction Association","url":"https://en.wikipedia.org/wiki/Metal_Construction_Association","publisher":"Wikipedia"},{"title":"The Metal Construction Association is turning 40","url":"https://www.metalcoffeeshop.com/post/the-metal-construction-association-is-turning-40","publisher":"MetalCoffeeShop"}],"category":"organizations","type":"organization","country":null},{"slug":"metal-roof-fasteners","title":"Metal Roof Fasteners","category":"components","type":"article","summary":"Metal roofs are attached with screws, clips, cleats and nails whose metal must suit the panel, substrate and exposure.","body":"Fasteners are the anchor points of a metal roof. In standing seam roofs they are hidden, holding clips to the deck; in exposed-fastener roofs they pass through the panel face and must also keep water out. The right fastener depends on the panel system, the metal, the substrate and the environment.\n\n## Main types\n\nRoofing fasteners include screws, nails, staples, bolts, clips and specialised anchors. On metal roofs they fall into two groups:\n\n- **Concealed fastening**: screws hold clips, or a fastening flange along the panel edge, to the deck; the next panel's seam or locking joint covers them, so nothing pierces the weather surface. Clips also let the metal expand and contract.\n- **Exposed (washer-head) screws**: driven through the panel face, with a rubber washer, typically EPDM, under the head to seal the hole. They are used on corrugated and ribbed through-fastened sheets.\n- **Nails and cleats**: in traditional copper roofing, copper or hardware bronze nails secure concealed copper cleats to wood decks; screws and bolts are copper, bronze, brass or 300-series stainless steel.\n\n## Materials and corrosion\n\nFastener metal must be compatible with the roofing metal, or moisture can drive galvanic corrosion at the connection, staining the panel and weakening the fixing:\n\n- Copper, bronze, brass or 300-series stainless with copper roofs.\n- Aluminium or stainless steel with aluminium roofs, never bare or ordinary steel.\n\nFastener type, number and spacing are set by the manufacturer's specifications, local building codes, roof type and wind zone. Inferior or incompatible substitutes can void manufacturer warranties.\n\n## Ageing and maintenance\n\nWashers are usually the shortest-lived part of an exposed-fastener roof. Sunlight hardens them and daily thermal movement can loosen screws, so washers may begin to crack and screws back out after roughly 10 to 15 years, and periodic checking and re-screwing is part of maintenance. Concealed systems avoid these penetrations.\n\n## Installation\n\nScrews should be driven square and not overtightened. Over-driven or angled fasteners distort the panel, can damage washers and contribute to visible waviness (oil canning).","key_facts":[{"label":"Concealed fastening","value":"Clips or fastening flange hidden under seams"},{"label":"Exposed fastener seal","value":"EPDM rubber washer"},{"label":"Aluminium roofs","value":"Aluminium or stainless steel fasteners"}],"regions":["Global"],"aliases":["metal roofing screws","gasketed screws"],"related":["through-fastened-metal-panels","standing-seam-clips","galvanic-corrosion","oil-canning"],"company":null,"sources":[{"title":"14.3. Copper Roofing (architectural specifications)","url":"https://archive.copper.org/applications/architecture/arch_dhb/specifications/arch_specs/sheet_roofing.php","publisher":"Copper Development Association"},{"title":"Product Advisory Bulletin PAB05: Oil Canning","url":"https://cdn.dcs.lysaght.com/download/lysaght-product-advisory-bulletin-pab05-oil-canning","publisher":"Lysaght (BlueScope)"},{"title":"Aluminum Roofing Fasteners: Concealed vs Exposed Explained","url":"https://www.interlockroofing.com/kb/aluminum-roofing-fasteners-concealed-vs-exposed/","publisher":"Interlock Roofing"},{"title":"Fasteners: Definition, Types & Benefits for Roofing","url":"https://www.interlockroofing.com/glossary/fasteners/","publisher":"Interlock Roofing"},{"title":"Metal Roofing Problems: The Honest 20-Year Guide","url":"https://www.interlockroofing.com/kb/metal-roofing-problems/","publisher":"Interlock Roofing"}],"country":null},{"slug":"metal-roof-noise","title":"Metal Roof Noise: Myth and Fact","category":"problems-maintenance","type":"article","summary":"Metal roofs over a solid deck and insulation are generally no louder in rain than other roofs; noise is mainly an issue with sheets over open framing.","body":"A common belief is that metal roofs are loud whenever it rains or hails. Industry bodies and manufacturers report that, on typical homes, there is little difference in rain noise between metal and other roofing materials. The perception largely comes from barns, sheds and verandas where thin sheets are fixed directly to open purlins with no deck, insulation or ceiling below.\n\n## What controls noise\n\n- **Substrate**: metal laid over solid plywood, OSB or boarding, with underlayment, is acoustically damped by the deck.\n- **Insulation and ceiling**: attic insulation and interior ceilings absorb and block much of the remaining sound.\n- **Open framing**: exposed-fastener panels over open framing transmit more sound into the space below.\n\n## Other noises\n\nMetal roofs can also make ticking, popping or creaking sounds as panels heat or cool. This usually indicates restrained thermal movement, for example panels bound by fasteners, trims or tight clips, and can accompany oil canning. Good detailing that lets panels slide reduces it.\n\n## Practical points\n\n- When replacing an older roof, adding or keeping a solid deck and adequate insulation addresses most noise concerns.\n- On open buildings, adding insulation under the sheets reduces drumming.\n\n## Summary\n\nNoise is a function of the whole roof assembly, not the metal alone. An experienced installer and an appropriate substrate make the largest difference.\n\n## Comparison with other materials\n\nThe Metal Roofing Alliance, a North American industry group, states that there is little difference between metal and other roofing materials in noise from rain or hail on typical houses. Metal roofs are also reported to weigh about half as much as asphalt shingles, so adding or keeping a solid deck does not usually create structural problems.","key_facts":[{"label":"Typical finding","value":"Little difference vs other materials on decked, insulated homes"},{"label":"Noisier case","value":"Sheets over open framing without deck or insulation"},{"label":"Ticking/popping","value":"Usually restrained thermal movement"}],"regions":["Global"],"aliases":["are metal roofs loud","metal roof rain noise","tin roof rain"],"related":["through-fastened-metal-panels","thermal-movement-in-metal-roofs","metal-roofs-and-lightning","stone-coated-steel"],"company":null,"sources":[{"title":"FAQs","url":"https://www.metalroofing.com/faqs","publisher":"Metal Roofing Alliance"},{"title":"Busting 5 Metal Roofing Myths","url":"https://www.rooferscoffeeshop.com/post/busting-5-metal-roofing-myths-2","publisher":"RoofersCoffeeShop"},{"title":"Are Metal Roofs Loud When It Rains?","url":"https://www.interlockroofing.com/kb/are-metal-roofs-noisy/","publisher":"Interlock Roofing"},{"title":"Thermal Expansion & Oil Canning in Aluminum Roofs Explained","url":"https://www.interlockroofing.com/kb/aluminum-roof-thermal-expansion-oil-canning/","publisher":"Interlock Roofing"}],"country":null},{"slug":"metal-roof-paint-systems","title":"Metal Roof Paint Systems (Polyester, SMP, PVDF, Plastisol)","category":"components","type":"article","summary":"Factory paint systems for metal roofing range from polyester and SMP to PVDF and thick plastisol, differing in durability, colour retention and cost.","body":"Nearly all coloured metal roofing is painted at the mill on a coil coating line, not on site. The paint system is a stack of layers over the metallic coating: a chemical pretreatment for adhesion, a primer that supports corrosion resistance, and a topcoat on the exposed face, with a thinner backer coat underneath. The topcoat resin family largely determines how long colour and gloss will last.\n\n## Main resin families\n\n- **Polyester**: economical, widely used for agricultural, industrial and general roofing.\n- **Silicone-modified polyester (SMP)**: polyester modified with silicone for better gloss and chalk resistance; common on residential and agricultural steel in North America.\n- **PVDF (fluoropolymer)**: premium resin, such as Kynar 500 or Hylar 5000, with very good colour and gloss retention; standard for architectural standing seam.\n- **Plastisol**: a thick PVC-based coating, typically many times the thickness of other paints and often embossed with a leather-grain texture; historically popular in the UK and northern Europe for its toughness.\n- **Polyurethane**: also applied on coil lines, typically for tougher, scratch-resistant finishes.\n\n## Choosing a system\n\nFactors include climate (UV intensity, coastal salt, industrial pollution), roof slope, colour (dark colours fade more visibly), expected life, and whether a paint warranty for chalk and fade is required. Paint warranties typically set limits for chalking and colour change measured by standard tests, and are often shorter or unavailable near the coast.\n\n## Related products\n\nSome regional product lines combine a specific metallic coating and paint system under one trade name, such as Colorbond steel in Australia. Highly reflective \"cool\" pigments can be used in several resin families.\n\n## Care\n\nFactory finishes are generally maintenance-light. Scratches should be treated with manufacturer touch-up paint sparingly, since touch-up can weather differently from the baked coating.","key_facts":[{"label":"Layer stack","value":"Pretreatment, primer, topcoat, backer"},{"label":"Economy resins","value":"Polyester, SMP"},{"label":"Premium resin","value":"PVDF"},{"label":"Thick-film option","value":"Plastisol (PVC-based)"}],"regions":["Global"],"aliases":["SMP paint","silicone-modified polyester","polyester paint","plastisol","prepainted steel finishes","PPGI"],"related":["pvdf-coating","coil-coating","colorbond-steel","cool-metal-roofing","galvalume"],"company":null,"sources":[{"title":"Coil coating","url":"https://en.wikipedia.org/wiki/Coil_coating","publisher":"Wikipedia"},{"title":"COLORBOND steel technology","url":"https://colorbond.com/why-colorbond-steel/technology","publisher":"BlueScope"},{"title":"Kynar 500 PVDF resin-based coatings","url":"https://kynar500.arkema.com/en/","publisher":"Arkema"},{"title":"Polyvinylidene fluoride","url":"https://en.wikipedia.org/wiki/Polyvinylidene_fluoride","publisher":"Wikipedia"}],"country":null},{"slug":"metal-roof-tiles","title":"Metal Roof Tiles (Press-Formed Tile Sheets)","category":"materials","type":"article","summary":"Metal roof tiles are steel or aluminium sheets press-formed into rows of tile shapes, either painted or stone-coated, to give a tiled look at light weight.","body":"Metal roof tiles, also called pressed metal tiles or tile-effect sheets, are made by pressing metallic-coated steel or aluminium in a die so that one panel carries several rows and columns of tile shapes. Each panel replaces many individual clay or concrete tiles. Finishes are either factory paint, often with a matte or textured coating, or a stone-granule coating.\n\n## Typical products\n\n- **Painted press-formed tile sheets**: often sold in long sheets with stepped tile courses.\n- **Stone-coated tile panels**: steel with an acrylic base, stone granules and glaze, imitating barrel or scalloped tile.\n- **Individual pressed metal tiles**: smaller units, sometimes with locking edges, used where very complex roof shapes must be covered.\n\n## Construction\n\nPanels are generally fixed to timber battens or purlins, with screws or nails placed at the step of each course where the next sheet covers them, or through the top of the profile. Side laps engage or overlap by a profile. Matching ridge, hip, gable and valley pieces complete the roof.\n\n## Characteristics\n\n- Much lighter than clay or concrete tile, reducing structural load.\n- Quick to install over large areas.\n- The deep three-dimensional profile hides minor dents and stiffens the sheet.\n- Exposed or semi-exposed fasteners need correct washers and positioning.\n- Thermal movement is accommodated mainly at laps and fixings, so manufacturers limit sheet lengths.\n\n## Durability\n\nLife depends mainly on the metallic coating (zinc, aluminium-zinc or zinc-aluminium-magnesium), the paint or granule system, the environment and the condition of cut edges and fixings.","key_facts":[{"label":"Base materials","value":"Metallic-coated steel, aluminium"},{"label":"Finishes","value":"Factory paint or stone granules"},{"label":"Main advantage","value":"Tile appearance at a fraction of tile weight"}],"regions":["Global"],"aliases":["pressed metal tiles","metal tile sheet","tile-effect metal roofing","metal tile roofing"],"related":["stone-coated-steel","metal-shingles","metallic-coating-designations","metal-roof-paint-systems"],"company":null,"sources":[{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"DECRA Metal Roofing","url":"https://www.decra.com/","publisher":"DECRA Roofing Systems"},{"title":"Interlock Mediterranean Metal Tile Roofing Explained","url":"https://www.interlockroofing.com/kb/mediterranean-metal-tile-roofing/","publisher":"Interlock Roofing"},{"title":"Stone coated steel roofing: Definition, Pros & Benefits","url":"https://www.interlockroofing.com/glossary/stone-coated-steel-roofing/","publisher":"Interlock Roofing"}],"country":null},{"slug":"metal-roofing","title":"Metal Roofing","category":"materials","type":"article","summary":"Metal roofing is any roof covering made from sheet metal, such as coated steel, aluminium, copper, zinc or lead, formed into panels, shingles or tiles.","body":"Metal roofing covers a family of roof systems in which thin metal, rather than clay, slate, wood or asphalt, forms the weathering surface. The metal may be laid over a solid deck as a waterproof skin, or it may be rolled into profiled sheets stiff enough to span between purlins on their own. Common base metals are steel with a metallic coating (zinc, aluminium-zinc or similar), aluminium, copper, zinc alloy, stainless steel and lead.\n\nMetal has been used on roofs for well over two thousand years. Lead and copper were the first choices because they were easy to work; iron became economical in the early nineteenth century, and the 1829 English patent for corrugated sheet opened the way for cheap, lightweight industrial and colonial roofs. Steel later replaced wrought iron, allowing thinner sheets.\n\n## Main system types\n\n- **Through-fastened (exposed-fastener) panels**: corrugated or trapezoidal sheets screwed through the face into the structure.\n- **Standing seam**: long pans joined by raised seams and held down by concealed clips, letting the metal move with temperature.\n- **Traditional seamed roofing**: batten seam, flat (flat-lock) seam and related techniques used mainly with copper, zinc, lead and terne-coated metals.\n- **Modular products**: metal shingles, shakes and press-formed tiles, including stone-coated steel.\n\n## Performance\n\nService lives of roughly 30 to 70 years or more are commonly cited for metal roofs, depending on metal, coating and climate, compared with about 12 to 20 years often quoted for asphalt shingles. Metal is noncombustible, lighter than many alternatives and widely recycled. Weak points are usually at fasteners, seams, cut edges and flashings, and at junctions with incompatible metals.\n\n## Regional terms\n\nIn the UK, Ireland, Australia and New Zealand, profiled steel is still often called \"corrugated iron\" or CGI, while North Americans may say \"tin roof\" or \"metal roof\". Trade names such as Galvalume, Zincalume and Colorbond have become everyday words in some markets.","key_facts":[{"label":"Common metals","value":"Coated steel, aluminium, copper, zinc, stainless steel, lead"},{"label":"Typical cited service life","value":"About 30-70+ years depending on metal and coating"},{"label":"Corrugated sheet patent","value":"1829, England (Henry Robinson Palmer)"},{"label":"Fire behaviour","value":"Noncombustible"}],"regions":["Global"],"aliases":["metal roof","sheet metal roofing","tin roof"],"related":["standing-seam-metal-roof","through-fastened-metal-panels","corrugated-iron","galvalume","copper-roofing","zinc-roofing","aluminum-roofing","stone-coated-steel"],"company":null,"sources":[{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"},{"title":"FAQs","url":"https://www.metalroofing.com/faqs","publisher":"Metal Roofing Alliance"},{"title":"Myths About Metal Roofing: Heat, Wind and Lightning","url":"https://www.mbci.com/blog/myths-about-metal-roofing/","publisher":"MBCI"},{"title":"Metal Roofing Problems: The Honest 20-Year Guide","url":"https://www.interlockroofing.com/kb/metal-roofing-problems/","publisher":"Interlock Roofing"},{"title":"Aluminum vs. Steel Roofing: Which Is Better?","url":"https://www.interlockroofing.com/kb/aluminum-vs-steel-roofing/","publisher":"Interlock Roofing"}],"country":null},{"slug":"metal-roofing-alliance","title":"Metal Roofing Alliance (MRA)","summary":"The Metal Roofing Alliance is a North American non-profit trade group, formed in 1998, that promotes metal roofing for homes.","body":"The Metal Roofing Alliance (MRA) is a non-profit trade association that promotes residential metal roofing in North America. It was established in 1998 with help from the Metal Construction Association (MCA) as a national marketing initiative aimed at homeowners. It operates separately from MCA but its goals are closely aligned.\n\nMRA members include metal roofing manufacturers, suppliers, coil coaters, contractors, distributors and trade media. The group runs the consumer website metalroofing.com.\n\n## Activities\n\n- **Consumer education.** MRA publishes information for homeowners about metal roof types, colours, cost factors, energy use and maintenance. Much of its work is aimed at the re-roofing market, where asphalt shingles have long been the most common choice in the United States and Canada.\n- **Contractor directory.** Its website lists member contractors and manufacturers by region.\n- **Promotion.** The alliance runs marketing campaigns, awards and media outreach to raise awareness of metal roofing for homes.\n\n## Context\n\nResidential metal roofing includes standing seam panels, exposed-fastener panels and metal shingles or tiles that imitate slate, shake or clay tile. Common materials are steel with metallic coatings, aluminium, copper and zinc. Because MRA is an industry marketing body, its material reflects the views of its members. Independent technical guidance on metal roofs is also available from building codes, standards bodies and research organisations such as building science laboratories.\n\n## Not a licensing body\n\nMembership in MRA is voluntary and is not a licence or certification of a contractor's skills. Homeowners should still confirm local licensing, insurance and references and review the manufacturer's warranty terms.","key_facts":[{"label":"Founded","value":"1998"},{"label":"Type","value":"Non-profit industry trade association"},{"label":"Focus","value":"Residential metal roofing"},{"label":"Website","value":"metalroofing.com"}],"regions":["North America"],"aliases":["MRA"],"related":["metal-construction-association","metal-roofing","standing-seam-metal-roof","metal-shingles"],"company":{"founded":"1998","website":"https://www.metalroofing.com","known_for":["Consumer education on residential metal roofing"]},"sources":[{"title":"About the Metal Roofing Alliance","url":"https://www.metalroofing.com/v2/content/about/","publisher":"Metal Roofing Alliance"},{"title":"Metal Construction Association (covers MRA founding)","url":"https://en.wikipedia.org/wiki/Metal_Construction_Association","publisher":"Wikipedia"},{"title":"Metal Roofing Alliance launches new website","url":"https://designandbuildwithmetal.com/industry-news/2026/02/03/metal-roofing-alliance-launches-new-website","publisher":"Design and Build with Metal"}],"category":"organizations","type":"organization","country":null},{"slug":"metal-roof-recycling","title":"Metal Roofing Recycling","type":"article","summary":"Recovery of aluminium, steel, copper and zinc roofing at end of life, and the recycled content used in new metal roofing.","body":"Metal roofing materials, including aluminium, steel, copper and zinc, can be recycled repeatedly without losing their essential properties. Scrap from new production (offcuts and trimmings) and from demolition (old panels, flashings and gutters) has value, so it is commonly collected and sold to metal recyclers rather than landfilled.\n\n## Aluminium\n\nRecycling aluminium requires only about 5 percent of the energy needed to produce new aluminium from ore, an energy saving of up to 95 percent. About 75 percent of all aluminium ever produced is still in use, which the International Aluminium Institute's 2020 data put at nearly 1.5 billion tonnes. The Aluminum Association reports recycling rates of up to 90 percent for aluminium in building and automotive markets.\n\n## Steel\n\nSteel roofing is made from steel coated with zinc or zinc-aluminium alloys and usually painted. It is readily separated magnetically from mixed demolition waste and recycled through steelmaking. Recycled steel content in new coil depends on the steelmaking route.\n\n## Copper and zinc\n\nCopper and zinc roofing have high scrap value and are usually salvaged when roofs are replaced. Copper roofs can last for many decades; InterNACHI's life expectancy chart lists copper at 70 years or more.\n\n## Coatings and contaminants\n\nPaint coatings, sealants, underlayment residues and fasteners are removed or burned off during remelting. Separating different metals (for example, copper flashings from aluminium panels) improves the value of scrap.\n\n## End of life versus recycled content\n\nTwo different measures are often confused:\n\n- **Recycled content:** the share of recycled metal in a new product.\n- **End-of-life recovery rate:** the share of old roofing collected and recycled when removed.\n\nBoth influence a product's environmental footprint and are reported in Environmental Product Declarations, which may credit recycling at end of life depending on the rules followed.\n\n## Practical recovery\n\nOn reroofing jobs, metal is often stripped and kept separate for scrap. Long service life is itself a sustainability factor: InterNACHI lists metal roofs at 40 to 80 years, which reduces the number of replacements and the waste they generate over a building's life.","key_facts":[{"label":"Energy for recycled aluminium","value":"About 5% of primary production"},{"label":"Aluminium ever produced still in use","value":"About 75%"},{"label":"Building-sector aluminium recycling","value":"Up to 90% (Aluminum Association)"},{"label":"Metal roof life (InterNACHI)","value":"40-80 years"}],"regions":["Global"],"aliases":["recycling metal roofs","aluminium roof recycling","steel roof recycling","metal roof sustainability","recycled content metal roofing"],"related":["embodied-carbon-roofing","environmental-product-declaration","roofing-waste","roof-lifespan-comparison","aluminum-roofing","copper-roofing","metal-roofing","zinc-roofing","cool-metal-roofing"],"sources":[{"title":"Aluminium recycling","url":"https://en.wikipedia.org/wiki/Aluminium_recycling","publisher":"Wikipedia"},{"title":"InterNACHI's Standard Estimated Life Expectancy Chart for Homes","url":"https://www.nachi.org/life-expectancy.htm","publisher":"InterNACHI"},{"title":"Environmental product declaration","url":"https://en.wikipedia.org/wiki/Environmental_product_declaration","publisher":"Wikipedia"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Essential Zinc: Building for the Future","url":"https://continuingeducation.bnpmedia.com/courses/umicore-building-products-usa-inc/essential-zinc-building-for-the-future/2/","publisher":"Continuing Education Center (BNP Media) / Umicore Building Products"},{"title":"Copper Availability and Attributes","url":"https://atas.com/did-you-know-series/copper-availability-and-attributes","publisher":"ATAS International"},{"title":"Is Aluminum Roofing Recyclable? Sustainability Explained (2026)","url":"https://www.interlockroofing.com/kb/is-aluminum-roofing-recyclable/","publisher":"Interlock Roofing"},{"title":"Copper Roof Pros and Cons (Is It Worth It? 2026)","url":"https://www.interlockroofing.com/kb/copper-roof-pros-and-cons/","publisher":"Interlock Roofing"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"metal-roofs-and-lightning","title":"Metal Roofs and Lightning: Myth and Fact","category":"problems-maintenance","type":"article","summary":"Metal roofs do not attract lightning; strike risk depends on height, terrain and storm frequency, and metal's noncombustibility can reduce fire risk.","body":"Many homeowners worry that a metal roof will draw lightning. Research summarised by the Metal Construction Association (MCA) indicates that roofing material does not meaningfully change the probability of a strike. A metal roof neither attracts lightning nor protects a building from it.\n\n## What determines strike risk\n\n- Height and size of the building relative to its surroundings.\n- Terrain: hilltops and open ground are more exposed.\n- Nearby taller objects such as trees, towers and other buildings.\n- Local frequency and severity of thunderstorms.\n\n## If lightning does strike\n\nMetal is electrically conductive and noncombustible. The MCA notes that a conductive path lets the strike's energy pass with little resistive heating, reducing the chance of fire or explosion, and that noncombustible roofing lowers fire risk compared with combustible coverings. A metal roof is not, however, a lightning protection system.\n\n## Lightning protection\n\nWhere protection is needed, for example on tall or isolated buildings, a properly designed lightning protection system (LPS) with air terminals, down conductors and earthing should be installed. In the United States, NFPA 780 covers the materials and installation of such systems; other countries have equivalent national or IEC-based standards. Metal roofing can be incorporated into an LPS design when a qualified designer specifies it.\n\n## Bottom line\n\nChoosing metal neither raises nor lowers the chance of a strike, and its noncombustible nature can be an advantage if a strike occurs.\n\n## Common sources of confusion\n\nLightning rods are metal, which leads some people to assume that metal draws strikes. In fact, lightning protection systems work by giving a strike that would occur anyway a controlled, low-resistance path to earth. A metal roof without such a system does not change where lightning strikes.","key_facts":[{"label":"Effect on strike probability","value":"No significant effect (MCA)"},{"label":"Main risk factors","value":"Height, terrain, surroundings, storm frequency"},{"label":"US protection standard","value":"NFPA 780"},{"label":"Fire behaviour","value":"Noncombustible"}],"regions":["Global"],"aliases":["do metal roofs attract lightning","lightning and metal roofs"],"related":["metal-roof-noise","metal-roofing","hail-resistance-metal-roofs"],"company":null,"sources":[{"title":"MCA updates bulletin about lightning strikes and metal roofing","url":"https://designandbuildwithmetal.com/industry-news/2018/07/26/mca-updates-bulletin-about-lightning-strikes-and-metal-roofing","publisher":"Design & Build with Metal"},{"title":"Myths About Metal Roofing: Heat, Wind and Lightning","url":"https://www.mbci.com/blog/myths-about-metal-roofing/","publisher":"MBCI"},{"title":"The myths of metal roofing damage from lightning and hail storms","url":"https://www.metalcoffeeshop.com/post/the-myths-of-metal-roofing-damage-from-lightning-and-hail-storms","publisher":"MetalCoffeeShop"},{"title":"Busting 5 Metal Roofing Myths","url":"https://www.rooferscoffeeshop.com/post/busting-5-metal-roofing-myths-2","publisher":"RoofersCoffeeShop"},{"title":"Do Metal Roofs Attract Lightning?","url":"https://www.interlockroofing.com/kb/do-metal-roofs-attract-lightning/","publisher":"Interlock Roofing"}],"country":null},{"slug":"metal-shingles","title":"Metal Shingles and Shakes","category":"materials","type":"article","summary":"Metal shingles are small locking units of steel, aluminium, copper or stainless steel stamped to resemble slate, wood shake or asphalt shingles.","body":"Metal shingles divide a roof into small, overlapping or locking units rather than long panels. They are pressed or stamped from coated steel, aluminium, copper, stainless steel or zinc, and many are embossed to imitate slate, cedar shakes, clay tile or asphalt shingles. Stone-coated steel shingles are a related group with a granular surface.\n\n## History\n\nMetal shingles are not new. The Arch Street Meetinghouse in Philadelphia (1804) had tin shingles laid in a herringbone pattern, and embossed tin shingles were popular across the United States in the late nineteenth century. Pressed metal shingles and tiles were also made in Britain, Australia and elsewhere.\n\n## Construction\n\n- Units typically lock together on all four sides, or on top and side edges, so water is shed and wind uplift is resisted.\n- Fasteners are generally concealed in the locking joint or covered by the next course.\n- Some systems are fixed to battens, others directly to a solid deck over underlayment.\n- Ridge, hip, valley and edge trims are supplied to match.\n\n## Advantages and trade-offs\n\n- Small units suit complex roofs with many hips, valleys and dormers, and steep slopes.\n- The broken surface makes oil canning invisible and hides minor dents.\n- Light weight allows installation over some existing roofs where codes permit.\n- More joints mean more reliance on correct locking and flashing than a long standing seam panel.\n- Allowance for thermal movement is distributed across many small joints.\n\n## Naming\n\nIn North America, slate-look, shake-look and shingle-look metal products are often grouped under \"metal shingles\". In Australia, New Zealand and the UK, locking pressed steel units shaped like tile are more often called metal tiles or pressed metal tiles.","key_facts":[{"label":"Materials","value":"Coated steel, aluminium, copper, stainless steel, zinc"},{"label":"Typical styles","value":"Slate, shake, tile and shingle look"},{"label":"Early example","value":"Tin shingles, Arch Street Meetinghouse (1804)"}],"regions":["Global"],"aliases":["metal shakes","metal slate","slate-look metal roofing","locking metal shingles","stamped metal shingles"],"related":["metal-roof-tiles","stone-coated-steel","tin-roof","metal-roof-over-existing-shingles"],"company":null,"sources":[{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"DECRA Metal Roofing","url":"https://www.decra.com/","publisher":"DECRA Roofing Systems"},{"title":"Metal Shingles: Styles, Materials & Costs","url":"https://www.interlockroofing.com/metal-roofing/metal-shingles/","publisher":"Interlock Roofing"},{"title":"What Is Oil Canning? Metal Roof Waviness Explained","url":"https://www.interlockroofing.com/glossary/oil-canning/","publisher":"Interlock Roofing"}],"country":null},{"slug":"metallic-coating-designations","title":"Metallic Coating Designations (G90, AZ50, Z275)","category":"standards-codes","type":"term","summary":"Codes such as G90, AZ55, Z275 or AZM150 state how much zinc or aluminium-zinc coating a steel roofing sheet carries, measured on both sides combined.","body":"Steel used for roofing is protected by a thin metallic coating, and the amount of that coating is stated with a short code. The letters identify the coating alloy and the number gives the minimum coating mass, totalled over both faces of the sheet. Reading these codes is the simplest way to compare how much corrosion protection two steel products carry before any paint is applied.\n\n## Common North American codes\n\n- **G (galvanized, ASTM A653)**: G60 = 0.60 oz/ft2; G90 = 0.90 oz/ft2.\n- **AZ (55% aluminium-zinc, ASTM A792)**: AZ50 = 0.50 oz/ft2; AZ55 = 0.55 oz/ft2.\n- **GF (zinc-5% aluminium)**: for example GF60 and GF90; this alloy is sold under the Galfan name.\n- **ZM (zinc-aluminium-magnesium, ASTM A1046)**: ZM60 and ZM90, used where extra corrosion resistance is wanted.\n\n## Metric equivalents\n\nOne ounce per square foot equals about 305 g/m2. Metric designations therefore read G90 as Z275 and G60 as about Z180, while AZ50 becomes AZM150 and AZ55 becomes AZM165.\n\n## How the number is measured\n\nThe figure is a \"triple-spot\" average: three samples are taken across the strip width, at the centre line and at least 50 mm (2 in) from each edge, and the coating mass on both sides is averaged. A single spot may fall slightly below that value. Producers usually measure on-line with X-ray or isotope gauges, with chemical strip-and-weigh tests as the reference method.\n\n## Comparing coatings\n\nEqual weights do not mean equal thickness, because zinc is denser than aluminium: AZ coatings are thicker than G coatings of the same mass. For plain zinc, life is roughly proportional to coating weight, but alloy coatings do not follow a simple ratio, so codes should only be compared within the same alloy family.","key_facts":[{"label":"Conversion","value":"1 oz/ft2 = about 305 g/m2"},{"label":"G90","value":"0.90 oz/ft2 total = Z275"},{"label":"AZ55","value":"0.55 oz/ft2 total = AZM165"},{"label":"Measurement basis","value":"Triple-spot average, both sides combined"}],"regions":["Global"],"aliases":["coating weight","coating mass","G90","AZ50","AZ55","Z275","AZM150"],"related":["galvanized-steel-roofing","galvalume","sheet-metal-gauge","metal-roofing"],"company":null,"sources":[{"title":"Metallic-Coated Products and Specifications (GalvInfoNote 1.1)","url":"https://www.galvinfo.com/wp-content/uploads/sites/8/2021/01/GalvInfoNote-1-1-Rev-4-0.pdf","publisher":"GalvInfo Center"},{"title":"ASTM Coated Sheet Steel for Construction: Galvalume ASTM Coating Weights","url":"https://www.mcelroymetal.com/hubfs/assets/galvalume-astm-coating-weights.pdf","publisher":"McElroy Metal / U.S. Steel"},{"title":"Metallic-Coated Products and Specifications (GalvInfoNote 1.2)","url":"https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote_1_2.pdf","publisher":"GalvInfo Center"}],"country":null},{"slug":"mezhyrich-mammoth-bone-dwellings","title":"Mezhyrich Mammoth-Bone Dwellings","category":"history","type":"place","summary":"Ice Age shelters in central Ukraine built around a base of mammoth skulls and long bones, probably covered with hides or bark and weighted with tusks.","body":"Mezhyrich is an Upper Palaeolithic site near the village of the same name in central Ukraine, southeast of Kyiv. It is the best-known of several sites in the region where people built shelters using mammoth bone. A farmer found the first bone, a lower jaw, in 1965 while enlarging his cellar, and excavations followed. Four dwellings are recorded.\n\n## Dating\n\nEarlier radiocarbon dates spread between roughly 19,000 and 12,000 years ago, and the site has often been given as about 15,000 years old. A study published in November 2025 dated remains of about a dozen small animals found around the dwellings, placing the largest structure at about 18,323 to 17,839 years ago, just after the Last Glacial Maximum, with a possible span of use of up to 429 years. François Djindjian, who was not involved, cautioned that more dates from across the site are needed.\n\n## How the shelters were built\n\n- **Base:** mammoth skulls and large long bones set upright in the ground formed a low plinth or foundation.\n- **Frame:** a wooden framework may have covered parts of the shelter.\n- **Covering:** most likely hides of smaller animals, or possibly birch bark.\n- **Roof weights:** tusks and large flat bones were placed on top, holding the cover down and protecting it from wind.\n- **Size:** the base of the best-known reconstruction is about 3.7-4.3 m (12-14 ft) across.\n\nThe 2025 study suggested each shelter housed five to seven people, who knapped flint, processed skins and butchered small animals inside. The authors concluded the shelters were practical survival structures rather than permanent settlements.\n\n## Related sites\n\nMezhyrich is often discussed alongside other mammoth-bone sites such as Mezin, Gontsy and Dobranichevka, which I. H. Pidoplichko surveyed together in a book published in 1998. Other finds at Mezhyrich include a bone engraved with what may be a map and a mammoth skull painted with red ochre that has been interpreted as a drum.\n\n## Significance for roofing history\n\nOn a treeless Ice Age steppe, bone replaced timber for the heavy parts of a shelter. The arrangement of a heavy, durable base with a light flexible cover held down by weights is a pattern seen in many later roofs, from turf weighted with stones to thatch pinned with ropes.","key_facts":[{"label":"Location","value":"Mezhyrich, central Ukraine (southeast of Kyiv)"},{"label":"Largest structure","value":"About 18,323-17,839 years ago (2025 study)"},{"label":"Dwellings","value":"Four"},{"label":"Likely covering","value":"Hides of smaller animals or birch bark"},{"label":"Roof weights","value":"Tusks and large flat bones"}],"regions":["Europe"],"aliases":["Mezhirich","Mezhyrich mammoth houses","mammoth bone huts"],"related":["prehistoric-shelters-and-early-thatch","prehistory-of-roofing","pit-house"],"company":null,"sources":[{"title":"Mezhyrich","url":"https://en.wikipedia.org/wiki/Mezhyrich","publisher":"Wikipedia"},{"title":"18,000 years ago, ice age humans built dwellings out of mammoth bones in Ukraine","url":"https://livescience.com/archaeology/18-000-years-ago-ice-age-humans-built-dwellings-out-of-mammoth-bones-in-ukraine","publisher":"Live Science"},{"title":"Pit-house","url":"https://en.wikipedia.org/wiki/Pit-house","publisher":"Wikipedia"}],"country":null},{"slug":"miami-dade-noa","title":"Miami-Dade Notice of Acceptance (NOA)","summary":"A Miami-Dade NOA is a county product approval showing a building product meets the Florida Building Code's High-Velocity Hurricane Zone rules.","body":"A **Notice of Acceptance (NOA)** is a product approval document issued by the Product Control Section of Miami-Dade County's building department in Florida. It confirms that a building product, such as a roof covering, underlayment, vent, window or shutter, has been tested and evaluated to the requirements of the Florida Building Code, including the **High-Velocity Hurricane Zone (HVHZ)** provisions. The HVHZ covers Miami-Dade and Broward counties, where the code's wind and impact rules are the strictest in the United States.\n\nMiami-Dade's product approval system grew out of the South Florida Building Code and was tightened after Hurricane Andrew struck South Florida in 1992, a storm in which many roofs failed. An NOA is often treated in the industry as a sign of very high wind performance, and manufacturers outside Florida sometimes cite it in marketing.\n\n## What an NOA contains\n\nEach NOA is a public PDF identified by a number (for example 25-0528.01). It typically lists:\n\n- the product, manufacturer and plant location\n- the approved uses, such as roof slope limits, deck types and fastening schedules\n- the test reports and standards it is based on, such as [TAS 100](/tas-100) (wind-driven rain), TAS 114, ASTM methods, or wind uplift tests\n- installation and labelling conditions\n- the approval and expiry dates\n\nNOAs are generally valid for five years. Renewal requires an application and is granted only if code changes have not affected the product's compliance. An NOA ends if the product's materials, use or manufacturing change.\n\n## Relationship to Florida Product Approval\n\nOutside Miami-Dade, Florida uses a statewide [Florida Product Approval](/florida-product-approval) system. An NOA can be one route for showing compliance for statewide approval, and products used in the HVHZ normally need an approval that specifically covers HVHZ use. \n\n## Practical use\n\nBuilding inspectors in the HVHZ check that the installed product, fasteners and details match the NOA. For roofers, the NOA works as a binding installation specification: deviating from the listed fastening or underlayment can mean a failed inspection.","key_facts":[{"label":"Issued by","value":"Miami-Dade County Product Control Section"},{"label":"Region covered","value":"High-Velocity Hurricane Zone (Miami-Dade and Broward)"},{"label":"Typical validity","value":"5 years"},{"label":"Basis","value":"Florida Building Code and Testing Application Standards (TAS)"}],"regions":["North America"],"aliases":["NOA","Miami-Dade approval","Miami-Dade product approval","HVHZ approval"],"related":["florida-product-approval","tas-100","florida-building-code"],"sources":[{"title":"Notice of Acceptance 25-0528.01","url":"https://www.miamidade.gov/building/library/productcontrol/noa/25052801.pdf","publisher":"Miami-Dade County"},{"title":"Using Special Nails to Save Roofs — and Dollars","url":"https://www.pewtrusts.org/research-and-analysis/blogs/stateline/2017/06/21/using-special-nails-to-save-roofs-and-dollars","publisher":"Pew / Stateline"},{"title":"Product Approval Regulation in Florida","url":"https://www.engineeringplans.com/?p=1806","publisher":"EngineeringPlans.com"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"middle-eastern-domes","title":"Middle Eastern Domes","type":"article","summary":"Masonry domes of mud brick, baked brick and stone used across the Middle East where timber was scarce, from village houses to great mosques.","body":"Domes have roofed buildings in the Middle East for thousands of years. Where long, straight timber was scarce, masonry domes and vaults offered a way to span rooms using only earth, brick or stone. The form runs from small domed houses, cisterns and ice houses in the countryside to the great tiled domes of Islamic monuments.\n\n## Materials\n\nThe earliest Middle Eastern domes were built of mud brick, followed by baked brick and stone. Mud-brick and baked-brick domes were sometimes covered with ceramic tiles to protect them from rain and snow. In Syria, corbelled domes were made from a spiral of earth bricks set in earth mortar, and studies suggest these behave more like continuous shells than stacked rings.\n\n## Vernacular domes in Iran\n\nWood was scarce on the Iranian plateau, so domes were an important part of ordinary building throughout Persian history. Domed water cisterns and ice houses remain common in the Iranian countryside. In cities such as Yazd, earth vaults and domes roof houses and bazaars, combined with windcatchers and courtyards to manage heat.\n\n## Monumental domes\n\nThe Sasanian Empire built the first large-scale domes in Iran. Later builders developed taller and more complex domes, including double-shell domes, in which a high outer dome sits over a lower inner one. The Dome of Soltaniyeh, about 50 m (164 ft) tall and 25 m (82 ft) in diameter, is regarded as one of the largest masonry domes ever built. Squinches and *muqarnas* make the transition from square rooms to circular domes, and Persian domes are known for exteriors covered in coloured glazed tile.\n\nBy the end of the 7th century, the dome had become a symbol of Islamic architecture, and it remains central to mosque design across the region.\n\n## Climate performance\n\nThick masonry domes store heat and moderate indoor temperatures. A curved roof is also partly shaded at any time of day, and its height lets warm air rise away from occupants. These qualities, together with the absence of timber, explain the dome's long use in hot, dry regions.\n\n## Today\n\nConcrete flat roofs dominate new construction across much of the region, but domes remain common on religious buildings and are used in some contemporary earth and low-energy architecture.","key_facts":[{"label":"Materials","value":"Mud brick, baked brick, stone, tile cladding"},{"label":"Reason for use","value":"Scarcity of timber, thermal mass"},{"label":"Dome of Soltaniyeh","value":"About 50 m tall, 25 m diameter"},{"label":"Vernacular uses","value":"Houses, cisterns, ice houses, bazaars"}],"regions":["Middle East"],"aliases":["Mud-brick dome","Persian dome","Islamic dome"],"related":["badgir","roofing-in-iran","roofing-in-the-middle-east-and-gulf","nubian-vault","dome"],"sources":[{"title":"Dome","url":"https://en.wikipedia.org/wiki/Dome","publisher":"Wikipedia"},{"title":"Iranian architecture","url":"https://en.wikipedia.org/wiki/Iranian_architecture","publisher":"Wikipedia"},{"title":"Historic City of Yazd","url":"https://whc.unesco.org/en/list/1544","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing","country":null},{"slug":"midwest-roofing-contractors-association","title":"Midwest Roofing Contractors Association (MRCA)","summary":"MRCA is a U.S. roofing contractors' association that began in 1950 in Topeka, Kansas, and is now headquartered in Dayton, Ohio.","body":"The Midwest Roofing Contractors Association (MRCA) is a regional trade association for roofing and sheet metal contractors, mainly in the central United States. It officially began in 1950 after a roofing clinic held in Topeka, Kansas, on January 12 of that year. Its first members were six firms from Kansas and three from Nebraska.\n\nMembership was originally limited to contractors in Nebraska, Kansas, Oklahoma and the Missouri cities along the Kansas border. It later expanded to cover a much larger part of the Midwest and beyond. Today the association lists its headquarters in Dayton, Ohio.\n\n## Technical history\n\nMRCA began its first technical and research project in the early 1960s. In 1965 it issued its first publication, a brochure on roof drainage titled *Don't Panic – Here's How to Make a Roof Drain*. The brochure influenced the minimum roof slope for drainage that architects recommended, an early example of contractor associations shaping design practice on low-slope roofs.\n\n## Programs\n\n- **Conference and EXPO.** MRCA holds an annual conference and trade show that moves between Midwestern cities.\n- **Safety.** The association runs the ELITE Safety Awards program and a safety certification program.\n- **CERTA.** MRCA created CERTA, a training program on safe use of torches when applying torch-applied roofing materials. This addresses the fire risk of open-flame roofing work.\n- **Awards and history.** It presents the James Q. McCawley Award and maintains an online \"Living History\" archive.\n\n## Regional context\n\nThe Midwest has hot summers, cold winters with freeze-thaw cycles, and frequent hail and severe storms. Low-slope commercial roofs, asphalt shingles on homes and metal roofs on agricultural buildings are all common. MRCA's emphasis on drainage, safety and storm-related work reflects those conditions. Membership is voluntary and does not replace state or local licensing.","key_facts":[{"label":"Founded","value":"1950 (Topeka, Kansas)"},{"label":"Headquarters","value":"Dayton, Ohio, USA"},{"label":"First publication","value":"Roof drain brochure, 1965"},{"label":"Known for","value":"CERTA torch safety training"}],"regions":["North America"],"aliases":["MRCA"],"related":["nrca","western-states-roofing-contractors-association","torch-applied-roofing","roof-drainage-design"],"company":{"founded":"1950","headquarters":"Dayton, Ohio, USA","known_for":["CERTA torch-safety training","ELITE Safety Awards","Annual Conference and EXPO"]},"sources":[{"title":"MRCA History","url":"https://www.associationdatabase.com/aws/MRCA/pt/sp/history","publisher":"Midwest Roofing Contractors Association"},{"title":"About MRCA","url":"https://associationdatabase.com/aws/MRCA/pt/sp/about","publisher":"Midwest Roofing Contractors Association"},{"title":"MRCA directory","url":"https://metalcoffeeshop.com/directory/mrca","publisher":"MetalCoffeeShop"}],"category":"organizations","type":"organization","country":null},{"slug":"millennium-dome","title":"Millennium Dome","category":"history","type":"place","summary":"London's fabric-roofed dome, 365 m (1,200 ft) across with 12 masts, opened for the year 2000 and now housing the O2 entertainment complex.","body":"The **Millennium Dome** on the Greenwich Peninsula in south-east London was built to house an exhibition celebrating the start of the third millennium. With one of the world's largest fabric roofs, it is a landmark of tensioned membrane construction. Since 2007 it has housed the O2 entertainment district and arena.\n\n## Design\n\nThe dome was designed by architect **Richard Rogers**, with **Buro Happold** as structural and services engineers. Its dimensions were chosen symbolically:\n\n- a plan diameter of **365 m (1,200 ft)**, roughly one metre for each day of the year;\n- a central height of **52 m (170 ft)**, roughly one metre for each week;\n- **twelve** yellow towers, each about 100 m (330 ft) high.\n\n## Structure and fabric\n\nThe towers support a network of steel cables from which the canopy is suspended. The canopy is made of **PTFE-coated glass-fibre fabric**, in 72 segments of two panels each. Plans to use PVC-coated polyester were dropped after a protest led by Greenpeace over PVC. The entire roof structure is said to weigh less than the air contained inside the building.\n\n## Opening and cost\n\nA private opening took place on **31 December 1999**, and the public were admitted from **1 January 2000**. The exhibition ran through 2000 and then closed. The dome structure itself cost about £43 million, while the whole project, including the exhibition, cost about £789 million.\n\n## Conversion to the O2\n\nThe dome was leased for redevelopment in December 2001. Because cranes could not be used under the canopy, the new arena's roof was assembled on the ground inside the dome and lifted into place. The arena, occupying about 40% of the dome, opened on **24 June 2007**.\n\n## Storm damage\n\nOn **18 February 2022**, during **Storm Eunice**, six segments of the fabric roof were torn away and around 1,000 people were evacuated. The venue reopened on 25 February after repairs.\n\n## Significance\n\nThe dome demonstrated the scale achievable with cable-supported fabric roofs and is a key reference in the history of tensile membrane architecture.","key_facts":[{"label":"Diameter","value":"365 m (1,200 ft)"},{"label":"Height","value":"52 m (170 ft)"},{"label":"Masts","value":"12, about 100 m (330 ft) high"},{"label":"Fabric","value":"PTFE-coated glass fibre"},{"label":"Opened","value":"31 December 1999 (public 1 January 2000)"}],"regions":["Europe"],"aliases":["The O2","O2 dome","Greenwich dome"],"related":["munich-olympic-stadium-roof","frei-otto","tensile-membrane-roof"],"company":null,"sources":[{"title":"Millennium Dome","url":"https://en.wikipedia.org/wiki/Millennium_Dome","publisher":"Wikipedia"},{"title":"The O2 Arena","url":"https://en.wikipedia.org/wiki/The_O2_Arena","publisher":"Wikipedia"}],"country":null},{"slug":"mineral-wool-roof-insulation","title":"Mineral Wool Roof Insulation","category":"low-slope-systems","type":"term","summary":"Dense non-combustible boards of stone or slag fibres used as flat-roof insulation where fire resistance, acoustics or dimensional stability matter.","body":"Mineral wool roof boards are rigid insulation made from fibres spun from molten rock (stone wool) or industrial slag, bonded with a binder and compressed to a high density. Glass wool belongs to the same broad family but is rarely used as rigid flat-roof board.\n\n## Manufacture and history\n\nStone wool is produced by melting rock at about 1,600 C (2,900 F) and spinning or blowing the melt into fibres typically 2-6 micrometres thick. Slag wool was made in Wales by Edward Parry in 1840, and commercial production began in Germany in 1871. Rock wool insulation was being produced in Ontario, Canada, by the mid-1930s.\n\n## Properties\n\n- **Thermal conductivity:** about 0.030-0.045 W/(m.K) for mineral wool insulation in general; dense roof boards sit at the higher end.\n- **Fire:** stone wool withstands about 700-850 C (1,300-1,560 F), far above foam plastics, and is used where non-combustible roof build-ups are required.\n- **Acoustics:** the fibrous structure absorbs sound, useful on lightweight steel-deck roofs.\n- **Stability:** boards do not shrink or expand significantly with temperature and are vapour-open.\n\n## Use on low-slope roofs\n\nDense stone wool boards are laid over steel or concrete decks under single-ply, bitumen and liquid membranes, either as the full insulation layer or as a fire-resistant layer and cover board over foam. Tapered stone wool schemes are available for creating falls. Boards with a bitumen-compatible or torchable upper layer are made for bituminous systems.\n\n## Considerations\n\nMineral wool is heavier than foam insulation for the same thermal value, so more thickness or weight is needed. It must be kept dry during installation, and boards need adequate compressive strength for foot traffic. The IARC classifies insulation stone wool and glass wool in Group 3, not classifiable as to carcinogenicity in humans.\n\n## Fire toxicity comparisons\n\nResearch on insulation fire behaviour has compared mineral wools with foam plastics. A 2011 University of Central Lancashire study, for example, found that polyisocyanurate released considerably more toxic combustion products than stone wool and glass wool, among other materials, which is one reason specifiers consider mineral wool where fire performance is a priority.","key_facts":[{"label":"Raw material","value":"Molten rock or slag spun into fibres"},{"label":"Conductivity","value":"About 0.030-0.045 W/(m.K)"},{"label":"Heat resistance (stone wool)","value":"About 700-850 C"},{"label":"IARC classification","value":"Group 3 for insulation wools"}],"regions":["Global","Europe"],"aliases":["stone wool","rock wool","slag wool","mineral fibre board"],"related":["roof-insulation","cover-board","tapered-insulation","polyiso-insulation"],"company":null,"sources":[{"title":"Mineral wool","url":"https://en.wikipedia.org/wiki/Mineral_wool","publisher":"Wikipedia"},{"title":"Polyisocyanurate","url":"https://en.wikipedia.org/wiki/Polyisocyanurate","publisher":"Wikipedia"}],"country":null},{"slug":"mission-tile","title":"Mission Tile","type":"term","summary":"A two-piece curved clay roof tile system of half-round pans and covers, also called barrel tile or monk-and-nun tile.","body":"Mission tile is a curved clay roof tile laid in two layers: a row of concave pans (or \"nuns\") with their edges turned up, and a row of convex covers (or \"monks\") laid over the joints between them. The result is the deeply ribbed, wavy roof associated with Mediterranean, Spanish Colonial and California Mission architecture. In English the system is also known as **barrel tile**, and in German as *Mönch und Nonne*.\n\n## Shape\n\nEach tile is a tapered half-cylinder, slightly wider at one end so that each tile fits into the next one up the slope. The same tile can be used as either pan or cover simply by turning it over, although many modern systems make the two parts in different sizes. A popular story says early tiles were shaped over a worker's thigh; whatever the truth, the hand-made tapered form produced the irregular look many people associate with old roofs.\n\n## History\n\nThe two-piece pan-and-cover principle goes back to ancient Greece and Rome, where flat tegulae were combined with half-round imbrices. Fully curved pans and covers became the standard form around the Mediterranean and were carried to the Americas by Spanish and Portuguese settlers. In California, mission-style clay tile was first produced in 1780 for the Franciscan missions, which gave the tile its English name. In Germany, flat beaver-tail tiles gradually replaced two-piece curved tiles from the late Middle Ages.\n\n## Performance\n\nMission tile roofs are heavy and use more tiles per square metre than one-piece pantiles or interlocking tiles. The curved shape creates an air space under the tiles that helps reduce heat gain, which is one reason the form is common in hot climates. In high-wind regions the covers must be mechanically fixed with nails, wire, clips or approved adhesives, since loose covers can be lifted by the wind.\n\n## Modern versions\n\nTwo-piece clay mission tiles are still manufactured, along with one-piece \"S\" tiles and concrete imitations that reproduce the look at lower cost.\n","key_facts":[{"label":"System","value":"Two-piece: concave pan plus convex cover"},{"label":"First made in California","value":"1780"},{"label":"Other names","value":"Barrel tile, monk-and-nun, Mönch und Nonne"}],"regions":["Europe","North America","Latin America","Middle East"],"aliases":["barrel tile","monk and nun tile","Mönch und Nonne","two-piece barrel tile","cover-and-pan tile"],"related":["clay-roof-tile","spanish-tile","imbrex-and-tegula","pantile","concrete-roof-tile"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Imbrex and tegula","url":"https://en.wikipedia.org/wiki/Imbrex_and_tegula","publisher":"Wikipedia"},{"title":"Biberschwanzziegel","url":"https://de.wikipedia.org/wiki/Biberschwanzziegel","publisher":"Wikipedia (German)"}],"category":"materials","company":null,"country":null},{"slug":"modified-bitumen-roofing","title":"Modified Bitumen Roofing","category":"low-slope-systems","type":"article","summary":"Factory-made roofing sheets of asphalt blended with polymers such as SBS or APP and reinforced with polyester or glass fibre, laid in one or more plies.","body":"Modified bitumen, often shortened to \"mod-bit\", is a family of prefabricated roofing membranes made by blending asphalt with polymers that improve flexibility, elasticity and resistance to ageing. The modified asphalt is coated onto a reinforcing mat in the factory, and the resulting rolls are installed on site, typically in a two-ply system of base sheet and cap sheet.\n\n## Origins\n\nPolymer-modified bitumens were developed in Europe in the 1960s. Atactic polypropylene (APP) modification was first reported in Italy in 1967, and SBS (styrene-butadiene-styrene) modification was developed in France and Germany for colder climates. According to a trade history published by *Buildings*, by the mid-1980s modified bitumen held nearly 90% of the roofing market in Italy and about 60% in France and Norway. The systems reached the US commercial market in the late 1970s.\n\n## Construction of the sheet\n\n- **Polymer:** SBS (roughly 10-15% of the blend) gives rubber-like elasticity; APP (roughly 25-30%) gives a plastic, heat-resistant compound.\n- **Reinforcement:** polyester mats for elongation, puncture and tear resistance; glass-fibre mats for dimensional stability and tensile strength. Some sheets combine both.\n- **Surfacing:** mineral granules, metal foil, sand or film. Reflective granules and coatings are used for cool-roof cap sheets.\n- **Size:** rolls are typically about 0.9-1.0 m (36-39 in) wide and 1.8-4.3 mm (70-170 mil) thick.\n\n## Installation methods\n\n- torch-applied (heat-welded with propane torches or hot-air equipment)\n- mopped in hot asphalt (mainly SBS)\n- cold-applied adhesives, solvent- or water-based\n- self-adhered sheets with factory-applied adhesive\n\nModified bitumen can also be combined with built-up plies to form hybrid roofs, and is widely used as flashing material on BUR roofs.\n\n## Uses beyond the field membrane\n\nThe same sheets are used for temporary roofs, vapour retarders, air barriers and below-grade waterproofing. In the UK and Europe the broadly equivalent products are called reinforced bitumen membranes (RBM) or torch-on felt.\n\n## Performance\n\nMulti-ply systems provide redundancy at terminations and penetrations, where most leaks begin. Industry sources report US mod-bit roofs in service for more than 25 years, and many products hold FM Approvals listings for very severe hail.","key_facts":[{"label":"Developed","value":"Europe, 1960s (APP reported in Italy, 1967)"},{"label":"Introduced to US","value":"Late 1970s"},{"label":"Main polymers","value":"SBS and APP"},{"label":"Typical roll width","value":"0.9-1.0 m (36-39 in)"},{"label":"Typical thickness","value":"1.8-4.3 mm (70-170 mil)"}],"regions":["Global","North America","Europe"],"aliases":["mod-bit","modified bitumen","polymer-modified bitumen","MB roofing"],"related":["sbs-modified-bitumen","app-modified-bitumen","torch-applied-roofing","self-adhered-membrane","reinforced-bitumen-membrane","built-up-roofing"],"company":null,"sources":[{"title":"Low-slope roofing systems: built-up roofs and modified bitumen","url":"https://buildingenclosureonline.com/articles/82366-low-slope-roofing-systems-built-up-roofs-and-modified-bitumen","publisher":"Building Enclosure"},{"title":"Who Put the Modified in Modified Bitumens?","url":"https://buildings.com/feature/article/10187932/who-put-the-modified-in-modified-bitumens","publisher":"Buildings"},{"title":"Fit for Mod-Bit","url":"https://roofingcontractor.com/articles/95892-fit-for-mod-bit","publisher":"Roofing Contractor / ARMA"},{"title":"Cool Roofs","url":"https://www.energy.gov/energysaver/cool-roofs","publisher":"U.S. Department of Energy"}],"country":null},{"slug":"moisture-meter","title":"Moisture Meter (Roofing)","category":"tools-equipment","type":"term","summary":"A handheld instrument that indicates moisture in roof materials, either through pins that measure resistance or pinless sensors.","body":"A moisture meter is a handheld instrument that gives a reading related to the moisture content of a material. In roofing it is used to check wood decks and framing for wetness, to compare dry and wet areas of insulation, to examine core samples during moisture surveys, and to help trace leaks.\n\n## Types\n\n- **Pin (resistance) meters** have two metal pins pushed into the material. Electrical resistance between the pins falls as moisture rises, and the meter converts this into a reading. Pin meters were developed mainly for wood, and ASTM D7438 covers their use for wood-based materials; readings depend on wood species and temperature corrections.\n- **Pinless (capacitance or impedance) meters** have a flat sensor pad pressed against the surface. They send a low-energy electrical field into the material and measure changes caused by moisture, without making holes. Readings are relative and depend on the material's density and the depth of the field.\n- **Roof scanners** are larger, wheeled impedance instruments used across low-slope roofs on a grid, covered by ASTM D7954 (see roof moisture survey).\n- **Probe attachments** with long insulated pins reach into insulation and through membranes in some kits.\n\n## Using meters on roofs\n\nTechnical guidance on roof moisture testing stresses several points:\n\n- Readings on insulation are **relative**, not true moisture contents. Scales intended for wood do not translate directly to polyisocyanurate, expanded polystyrene, fibreboard or perlite.\n- Moisture is often uneven through the thickness of insulation, so tests should cover the top, middle and bottom of samples and both facers.\n- Pin meters only measure the small area between the pins and can miss wet zones.\n- Facers, adhesives and foil can distort readings.\n- Quantitative results require **gravimetric analysis** of core samples: weigh, oven-dry, reweigh, and calculate moisture content relative to dry weight.\n\n## Practical tips\n\nTake baseline readings in known dry areas for comparison, use the correct scale and temperature correction, and record readings on a roof plan. For wood decks, readings well above the material's normal equilibrium range indicate wetting worth investigating. A meter is a screening tool; its results support, but do not replace, inspection and core sampling.","key_facts":[{"label":"Types","value":"Pin (resistance) and pinless (capacitance/impedance)"},{"label":"Wood meter standard","value":"ASTM D7438"},{"label":"Roof scanner standard","value":"ASTM D7954"}],"regions":["Global"],"aliases":["pin meter","pinless moisture meter","moisture detector"],"related":["roof-moisture-survey","infrared-roof-thermography","roof-leak-detection","attic-mold","wood-rot"],"company":null,"sources":[{"title":"Surveying roof moisture","url":"https://professionalroofing.net/articles/article/5681","publisher":"Professional Roofing"},{"title":"Technical Details: How to properly determine moisture content in roof systems","url":"https://www.roofingcontractor.com/articles/83510-technical-details-how-to-properly-determine-moisture-content-in-roof-systems","publisher":"Roofing Contractor"},{"title":"Tramex Moisture Encounter Plus","url":"https://inspectandtest.net/guides/tramex-moisture-encounter-plus/","publisher":"Inspect and Test"}],"country":null},{"slug":"mongulu","title":"Mongulu (Baka Leaf Hut)","category":"world-roofing","type":"term","summary":"The móngulu is the dome-shaped leaf hut of the Baka of the Central African rainforest: thin branches bent into a hemisphere and shingled with large leaves.","body":"The *móngulu* is the traditional hut of the Baka, forest hunter-gatherers of the rainforests of Cameroon, Gabon and the Republic of the Congo. It is a small, hemispherical dome made for one family, built mainly by women from materials gathered around the camp. Similar leaf-covered domes are built by other forest peoples of Central Africa; in the Ituri forest of the Democratic Republic of the Congo, Mbuti (Bambuti) shelters are covered with layered *mongongo* leaves.\n\n## Construction\n\n1. Flexible thin branches are pushed into the ground in a circle and bent over to form a hemispheric framework.\n2. Large, freshly gathered leaves of plants of the Marantaceae family are laid over the frame to cover it.\n3. Other plant material is sometimes added to make the covering more compact and waterproof.\n4. A panel of bark or banana leaves can serve as a door.\n\nThe huts belong to forest camps rather than permanent villages, so the technique survives as living practice rather than in old buildings.\n\n## Change\n\nGovernment programmes to replace forest dwellers' huts have not always been well received: in Rwanda, the national campaign against thatched houses in 2009-2011 bore heavily on Batwa families (see Nyakatsi).\n\n## Significance for roofing\n\nThe móngulu is an extremely light roof. Its leaf covering follows the same principle as any lapped roof covering, with each course shedding water onto the next, but on a frame that is also the wall.\n\n## Sources and gaps\n\nHut dimensions, building time and the exact Marantaceae species used were not stated in published sources.","key_facts":[{"label":"People","value":"Baka (Cameroon, Gabon, Republic of the Congo)"},{"label":"Form","value":"Hemispherical dome for one family"},{"label":"Frame","value":"Thin flexible branches"},{"label":"Covering","value":"Large fresh Marantaceae leaves"},{"label":"Builders","value":"Mainly women"}],"regions":["Africa"],"aliases":["móngulu","Baka hut","Pygmy leaf hut","leaf dome"],"related":["roofing-in-cameroon","roofing-in-gabon","roofing-in-the-republic-of-the-congo","roofing-in-the-democratic-republic-of-the-congo","roofing-in-the-central-african-republic","prehistoric-shelters-and-early-thatch","dome","thatch"],"sources":[{"title":"Pygmy camp with leaf and bark huts","url":"https://pygmies.org/baka/camps.php","publisher":"pygmies.org"},{"title":"African architecture: Geographic influences","url":"https://www.britannica.com/art/African-architecture/Geographic-influences","publisher":"Encyclopaedia Britannica"}],"company":null,"country":null},{"slug":"moroccan-green-roof-tiles","title":"Moroccan Green Roof Tiles","category":"world-roofing","type":"article","summary":"Green glazed ceramic tiles covering pitched wooden roofs of Moroccan mosques, minaret caps, fountains and shrines, as at Fez's Al-Hamra Mosque.","body":"In Moroccan cities, green glazed ceramic roof tiles mark buildings of religious or civic importance. Pitched wooden roofs over mosque prayer halls, small pyramidal caps on minarets, and the canopies of fountains are covered in green tile.\n\n## Where they are used\n\n- **Mosque prayer halls**: at the Al-Hamra Mosque in Fez, generally attributed to the Marinid period (most likely the 14th century), the prayer hall's pitched wooden roofs are topped with green ceramic tiles, a style described as common to Moroccan mosques.\n- **Minarets**: the minaret of the Zellja Mosque, a neighbourhood mosque in Fez, is capped by a small pyramidal roof of green tiles.\n- **Fountains**: the Nejjarine Fountain in Fez, commissioned by Sultan Abd al-Rahman (ruled 1822-1859), has a carved wooden canopy topped by a short green-tiled roof.\n\n## Construction\n\nThe tiles sit on a timber roof structure. Inside, the same buildings often have painted wooden ceilings: the sloped wood-frame ceilings known locally as *berchla*, traditionally made of Moroccan cedar.\n\nIn larger mosques the timber structure is also used to carry decorative ceilings: at the Qarawiyyin Mosque in Fez, *muqarnas* vaults in the central nave hang from a hidden wooden framework, while the rest of the prayer hall has plain wooden ceilings.\n\n## Relationship to zellij\n\nGreen roof tiles are distinct from *zellij*, the cut-glazed mosaic tilework used on lower walls, floors and fountains. Both are glazed ceramics and both are part of Morocco's decorative tradition, but roof tiles are shaped to shed water, while zellij is purely a surface finish.\n\n## Context\n\nGlazed roof tiles are also found in other traditions, notably in China (see Chinese glazed roof tiles), but the Moroccan practice developed within western Islamic architecture.","key_facts":[{"label":"Colour","value":"Green glaze"},{"label":"Typical uses","value":"Mosque prayer halls, minaret caps, fountain canopies"},{"label":"Example","value":"Al-Hamra Mosque, Fez (probably 14th century)"},{"label":"Substrate","value":"Pitched timber roof"}],"regions":["Africa","Middle East"],"aliases":["green glazed tiles Morocco","Moroccan glazed roof tiles"],"related":["roofing-in-morocco","glazed-roof-tile","roofing-in-north-africa","chinese-glazed-roof-tiles","clay-roof-tile"],"company":null,"sources":[{"title":"Al-Hamra Mosque","url":"https://en.wikipedia.org/wiki/Al-Hamra_Mosque","publisher":"Wikipedia"},{"title":"Architecture of Fez","url":"https://en.wikipedia.org/wiki/Architecture_of_Fez","publisher":"Wikipedia"},{"title":"Moroccan architecture","url":"https://en.wikipedia.org/wiki/Moroccan_architecture","publisher":"Wikipedia"},{"title":"Al-Qarawiyyin Mosque","url":"https://en.wikipedia.org/wiki/Al-Qarawiyyin_Mosque","publisher":"Wikipedia"}],"country":null},{"slug":"mud-roof","title":"Mud Roof","category":"materials","type":"article","summary":"A roof finished with compacted earth or clay over timber beams and a layer of matting or brush, traditional in dry regions worldwide; also called an earth roof.","body":"A mud roof, or earth roof, is a roof whose weatherproof layer is compacted earth, clay or a clay-straw mix laid over a timber structure. Most are flat or very low-slope and are found in dry climates, from the American Southwest and North Africa through the Middle East and Iran to Central Asia and the Himalaya. Domes and vaults built of unfired mud brick are a related family, used where structural timber is scarce.\n\n## Typical build-up\n\nDetails vary by region, but the sequence is similar almost everywhere:\n\n1. **Main beams** span from wall to wall. In the Pueblo and Hispanic tradition of the American Southwest these are vigas; in Iran they are called tir.\n2. **Secondary members** lie across them: smaller poles (latillas in the Southwest) or boards.\n3. **A mat layer** of brush, reeds or cane matting stops the earth falling through.\n4. **Earth layers:** one or more coats of mud, often mixed with straw, then a thicker layer of earth. A Southwest roof of about 1850 had about 8 cm (3 in) of adobe mud over the latillas and about 45 cm (18 in) of dry earth on top.\n5. **Fall and drainage:** the top is shaped to a slight slope toward a spout (canal or canale in the Southwest) that throws water clear of the wall.\n\nWhen wetted, clay particles swell and close up, so the surface becomes relatively watertight. In Iran a stone roller (ḡaltabān) is used to compact the mud layers.\n\n## Maintenance\n\nMud roofs work only with regular care. In Iran, a new layer of clay-straw plaster (kāh-gel) about 2-3 cm (0.8-1.2 in) thick is traditionally added each year, and the roof is rolled or patched after rain. In the Southwest, weeds were pulled and the earth re-sloped annually. Neglect leads quickly to leaks, erosion of parapets and rot in the beams.\n\n## Strengths and limits\n\n- **Insulation:** thick earth roofs moderate heat and are valued in hot, dry climates; flat roofs are often used for sleeping in summer.\n- **Fire:** depending on materials, they can be highly fire resistant.\n- **Climate limits:** they suit dry climates without heavy snow loads. Prolonged rain softens and erodes them.\n- **Weight:** a thick earth layer is very heavy and needs large beams and sound bearings at the wall tops.\n\n## Domes and vaults\n\nWhere wood is rare, as on the central Iranian plateau, builders roofed rooms with barrel vaults and domes of unfired mud brick laid without centering, then plastered them inside and out. A second flat roof was often built above them for protection and summer use. Wood-framed pitched roofs in Iran are mostly confined to the wetter, forested Caspian provinces.\n\n## Regional traditions\n\nEarth roofs appear in Najdi architecture of central Arabia, in the Sahel of West Africa, in Hausa vaults and domes of northern Nigeria, in the Nubian vault, and in Iranian village building. Earth over timber was also used in colder climates: Plains earth lodges in North America and some Jomon pit dwellings in Japan carried heavy earth roofs over timber frames.\n\n## Modern use\n\nContemporary earth roofs may use steel or engineered timber framing with mesh and earth spread like cob, and builders sometimes add cement to help the earth dry evenly without cracking, which can reduce its permeability and adds the carbon cost of cement.","key_facts":[{"label":"Also called","value":"Earth roof, adobe roof, clay roof"},{"label":"Typical structure","value":"Beams, poles or boards, matting, earth layers"},{"label":"Example thickness","value":"About 8 cm (3 in) mud + 45 cm (18 in) earth (US Southwest, c. 1850)"},{"label":"Annual upkeep (Iran)","value":"New 2-3 cm (0.8-1.2 in) kah-gel layer"},{"label":"Best suited to","value":"Dry climates without heavy snow"}],"regions":["Global","Middle East","North America","Africa","Central Asia","South Asia"],"aliases":["earth roof","adobe roof","flat mud roof","bam","kah-gel roof"],"related":["najdi-mud-roofs","sahelian-earthen-roofs","hausa-earth-vaults-and-domes","nubian-vault","middle-eastern-domes","rammed-earth","earth-lodge","sod-roof","flat-roof"],"company":null,"sources":[{"title":"Adobe","url":"https://en.wikipedia.org/wiki/Adobe","publisher":"Wikipedia"},{"title":"Bannai (construction)","url":"https://www.iranicaonline.org/articles/bannai-construction/","publisher":"Encyclopaedia Iranica"}],"country":null},{"slug":"mudhif","title":"Mudhif","category":"world-roofing","type":"term","regions":["Middle East"],"company":null,"summary":"A vaulted guest house of bundled and arched reeds built by the Marsh Arabs of southern Iraq, a form traced back about 5,000 years.","aliases":["mudheef","mudif","al-mudhif","reed guest house","Marsh Arab reed house"],"body":"A mudhif (Arabic *al-muḍīf*) is a long, tunnel-like hall built entirely of reeds in the marshes of southern Iraq. It is the communal guest house of a village or tribal sheikh, and is often described as one of the oldest continuously built roof forms: the structure is the roof, with no separate walls or timber frame.\n\nMudhifs have been built in the marshes for at least 5,000 years. A carved image of a typical mudhif from Uruk, dated to about 3300 BC, is held by the British Museum. The marshes and the nearby Sumerian cities of Uruk, Ur and Eridu are together inscribed by UNESCO as the Ahwar of Southern Iraq.\n\n## Construction\n\n- **Arches:** thick reeds are bundled and woven into columns. Pairs of bundles are set into the ground and bent together into parabolic arches that form the spine of the building. Setting them at opposing angles pre-stresses the arches and stiffens them.\n- **Purlins:** smaller reed bundles are laid along the length of the building across the arches and lashed in place.\n- **Covering:** woven reed mats form the outer skin. Some mats are made open like a mesh to let in light and air.\n- **End walls:** the front and back are framed by two large vertical reed columns and closed with more mats; decorative bundles on the facade can identify the tribe.\n\nThe number of arches is chosen by the family or tribe rather than fixed. The traveller Gertrude Bell described one mudhif as roughly 50 yards (about 46 m) long. The entrance traditionally faces Mecca.\n\n## Why reed works\n\nThe common building reed in the marshes is called *ihdri*. Reed is cheap and flexible, insulates against heat and noise, and resists water and insects; its high silica content helps it shed water. A mudhif still needs rebuilding roughly every ten years.\n\n## Related reed buildings\n\nThe mudhif belongs to a wider family of reed structures (*sarifa*). A *raba* is a family reed house with doors at both ends, and a *bayt* a small single-room reed dwelling.\n\n## Drainage and return\n\nThe marsh communities, known as the Ahwari or Marsh Arabs, numbered about half a million in the 1980s. From around 1993 the marshes were deliberately drained by the Iraqi government. After 2003 local people broke the dykes, water returned to parts of the marshes, and reed building resumed. UNESCO notes that the Huwaizah marshes were not drastically drained in the 1980s and 1990s.","key_facts":[{"label":"Material","value":"Reed (ihdri) bundles and woven mats"},{"label":"Structure","value":"Bundled reed parabolic arches"},{"label":"Earliest image","value":"Uruk carving, c. 3300 BC"},{"label":"Rebuild interval","value":"About every 10 years"},{"label":"Region","value":"Marshes of southern Iraq (Ahwar)"}],"related":["roofing-in-iraq","water-reed-thatch","thatch","barrel-vault-roof","roofing-in-iran"],"sources":[{"title":"Mudhif","url":"https://en.wikipedia.org/wiki/Mudhif","publisher":"Wikipedia"},{"title":"The Ahwar of Southern Iraq: Refuge of Biodiversity and the Relict Landscape of the Mesopotamian Cities","url":"https://whc.unesco.org/en/list/1481","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"mugamba-rugo","title":"Mugamba Rugo","category":"world-roofing","type":"term","summary":"The rugo is Burundi's traditional round house: a dome of bent poles bound with papyrus rings and thatched in straw, on UNESCO's tentative list since 2007.","body":"The *rugo* (Kirundi: house or housing complex) is the traditional dwelling of Burundi, best preserved as a cultural model in the Mugamba highlands. It is a round, dome-shaped house built entirely of plant materials, with a thick straw thatch over a woven frame. Burundi placed the traditional rugo of Mugamba on its UNESCO World Heritage tentative list on 9 May 2007.\n\n## Form and size\n\nThe house is circular, and its diameter was traditionally set out using the *intambwe*, a body measure taken from a man lying on the ground with one arm extended; a stake marked the end of his finger. Size reflected status and need. A 2018 study gives typical floor areas of 20 to 28 m² (215 to 300 sq ft), an average height of about 3 m (10 ft) and a radius of about 2.5 m (8 ft) for a young household, about 3 m for a large family and up to 5 m (16 ft) for a chief. The royal hut (*ingoro*) was about 10 m (33 ft) across and 4 m (13 ft) high, under thatch about 90 cm (3 ft) thick.\n\n## Roof structure\n\nThe rugo is essentially all roof. Some 45 to 60 piles are set in a circle, 30 to 40 cm (12 to 16 in) apart; 120 to 200 bent poles about 4 m (13 ft) long rise from them and are folded together near the top (*guheta*). Horizontal rings of reed core wrapped in papyrus bind the frame. Inside, 8 to 13 carved pillars help carry the dome, and a spiral coil (*umutente*) about 200 m long stiffens the roof. The inner roof (*igisenge*) is lined with palm reed or papyrus, the walls with split bamboo, and the outside with straw. A topknot finishes the apex.\n\nStraw thatch was vulnerable to moisture. Roofs were sloped to shed rain, damaged straw was replaced regularly and old straw was reused as crop fertiliser.\n\n## The compound\n\nThe rugo is also the whole homestead: a bamboo fence encloses a front courtyard (*urugo*) used to keep livestock, with a central hearth (*igicaniro*) whose smoke kept flies off the animals, and a rear courtyard (*ikigo*). A post (*icishinzo*) was set up for cattle to rub against.\n\n## Building practice\n\nBuilders gathered materials (*guhumbira*) through the rainy season and built in the dry season. The household head called helpers (*kurarika abubatsi*), usually 20 to 30 people, who split into a roof team and a wall team.\n\n## Relationship to neighbouring forms\n\nThe rugo belongs to the family of beehive and domed grass houses of the Great Lakes region, alongside Rwanda's thatched houses (*nyakatsi*) and the great thatched dome of the Ganda royal tombs at Kasubi in Uganda.","key_facts":[{"label":"Country","value":"Burundi (Mugamba highlands)"},{"label":"Form","value":"Round dome of bent poles, straw thatch"},{"label":"Frame","value":"45-60 piles; 120-200 poles about 4 m (13 ft); papyrus-wrapped reed rings"},{"label":"Royal hut thatch","value":"About 90 cm (3 ft) thick"},{"label":"UNESCO tentative list","value":"9 May 2007"}],"regions":["Africa"],"aliases":["rugo","Burundian rugo","ingoro"],"related":["roofing-in-burundi","nyakatsi","muzibu-azaala-mpanga","thatch","dome","rondavel"],"sources":[{"title":"Ecological Traditional Architecture Research in Burundi","url":"https://www.scitepress.org/Papers/2018/75634/75634.pdf","publisher":"SCITEPRESS"},{"title":"Mugamba natural region","url":"https://en.wikipedia.org/wiki/Mugamba_natural_region","publisher":"Wikipedia"},{"title":"Le rugo traditionnel du Mugamba","url":"https://www.worldheritagesite.org/tentative/id/5142","publisher":"WorldHeritageSite.org"}],"company":null,"country":null},{"slug":"munich-olympic-stadium-roof","title":"Munich Olympic Stadium Roof","category":"history","type":"place","summary":"The cable-net tent roof of acrylic glass over Munich's Olympic Park, designed by Behnisch & Partner with Frei Otto and completed in 1972.","body":"The roof of the **Olympiastadion** in Munich, Germany, and the adjoining Olympic Park buildings is one of the most famous lightweight roofs ever built. Its sweeping canopies of transparent acrylic panels on steel cable nets were the first use of such a tent construction on this scale.\n\n## Origins\n\nThe stadium was the main venue of the 1972 Summer Olympics. Its design was meant to evoke the skyline of the Alps and to contrast with the 1936 Berlin Olympics. The architects **Behnisch & Partner**, led by **Günther Behnisch**, won the competition, announced on **13 October 1967**. An employee, Cordel Wehrse, is credited with proposing the tent roof idea.\n\n## Design team\n\nThe engineering of such a roof had never been attempted at this size. **Frei Otto**, the leading pioneer of tensile structures, was brought in as development consultant, with engineers **Fritz Leonhardt** and **Wolf Andrä**. **Jörg Schlaich** directed the construction work, with **John Argyris** also assisting.\n\n## Structure\n\nThe roof is a lightweight tent construction: large sweeping canopies of **acrylic glass** panels stabilised by **steel cables**. The transparent covering shelters the seats while letting daylight through. The roof originally covered almost 45,000 seats; after later changes the stadium has fewer than 40,000. A planned extra tent roof over 15,000 seats in the eastern stands was never completed.\n\n## Completion\n\nThe stadium roof was completed on **21 April 1972**, and the stadium opened on **26 May 1972**. The tent roof cost about 170.6 million Deutsche Marks, out of a total Olympic project cost of about 1.35 billion.\n\n## Significance\n\nThe roof showed that a large, permanent, tensioned cable-net structure could be designed, analysed and built reliably. It remains one of the best-known examples of tensile roof architecture.","key_facts":[{"label":"Competition result","value":"13 October 1967"},{"label":"Architects","value":"Behnisch & Partner, with Frei Otto"},{"label":"Covering","value":"Acrylic glass on steel cable nets"},{"label":"Roof completed","value":"21 April 1972"},{"label":"Stadium opened","value":"26 May 1972"}],"regions":["Europe"],"aliases":["Olympiastadion roof","Munich Olympic Park roof"],"related":["frei-otto","millennium-dome","tensile-membrane-roof"],"company":null,"sources":[{"title":"Olympiastadion (Munich)","url":"https://en.wikipedia.org/wiki/Olympiastadion_(Munich)","publisher":"Wikipedia"},{"title":"Frei Otto","url":"https://en.wikipedia.org/wiki/Frei_Otto","publisher":"Wikipedia"}],"country":null},{"slug":"musgum-tolek","title":"Musgum Tolek (Earthen Dome House)","category":"world-roofing","type":"term","summary":"The tolek is the Musgum earthen dome house of northern Cameroon: a self-supporting mud shell up to about 9 m tall, built in coils with raised ribs.","body":"The *tolek* is the traditional house of the Musgum (Mousgoum) people of Cameroon's Far North Region, notably around Maga in the Mayo-Danay division. It is a tall dome or cone in which wall and roof are a single shell of compressed, sun-dried mud, described in some accounts as laid over lashed reeds; there is no separate roof structure. French speakers called these houses *cases obus*, \"shell houses\", for their artillery-shell profile.\n\n## Form\n\nDomes reach nearly 9 m (30 ft) in height. Their profile has been compared by architects to a catenary arch, the curve in which a self-supporting masonry shell carries its own weight in pure compression, which lets the walls be thick at the base and thin toward the top. Some are rounded beehives; others rise to an inverted-V point. A small round opening at the apex, a few centimetres across, ventilates the house, can be used as an escape hatch in floods and is closed with a slab or pot when it rains. The single door is keyhole-shaped, narrow at knee height and wider at the shoulders.\n\n## Construction\n\nThe tolek is built like a coiled pot. Mud mixed with water, sometimes with grass or other fibre, is laid in spiral rings about 0.5 m (20 in) high; each ring dries before the next is added. Few tools are needed. Instead of scaffolding, the raised geometric relief patterns on the outside give builders footholds during construction and later maintenance, and their V-shaped or straight grooves channel rainwater off the surface.\n\n## The compound\n\nSeveral domes, together with granaries, are grouped around a central courtyard within a thatched enclosure wall; new dwellings could be added for new wives or daughters-in-law.\n\n## Decline and revival\n\nWith the arrival of cement and metal roofing, the tolek came to be seen as old-fashioned, and very few Musgum now build them; general surveys of African architecture describe them as no longer made. Renewed appreciation of their place in Musgum history has, however, led to some recent construction. The art historian Steven Nelson studied the form and its afterlife in *From Cameroon to Paris: Mousgoum Architecture In and Out of Africa* (2007), following an earlier article on the tolek in *African Arts* (2001).\n\n## Significance\n\nThe tolek is often cited as an example of how a vernacular builder can arrive at an efficient structural shape without calculation: a roof that is also a wall, built from the ground it stands on.","key_facts":[{"label":"People","value":"Musgum (Mousgoum), Far North Region, Cameroon"},{"label":"Height","value":"Up to nearly 9 m (30 ft)"},{"label":"Material","value":"Sun-dried mud, sometimes with fibre"},{"label":"Method","value":"Coiled courses about 0.5 m (20 in) high"},{"label":"French name","value":"Case obus"}],"regions":["Africa"],"aliases":["Musgum mud hut","Mousgoum house","case obus","tolek"],"related":["roofing-in-cameroon","roofing-in-chad","dome","mud-roof","hausa-earth-vaults-and-domes","nubian-vault","sahelian-earthen-roofs","harran-beehive-houses"],"sources":[{"title":"Musgum mud hut","url":"https://en.wikipedia.org/wiki/Musgum_mud_hut","publisher":"Wikipedia"},{"title":"African architecture: Geographic influences","url":"https://www.britannica.com/art/African-architecture/Geographic-influences","publisher":"Encyclopaedia Britannica"},{"title":"From Cameroon to Paris: Mousgoum Architecture In and Out of Africa","url":"https://www.naoslibros.es/libros/from-cameroon-to-paris-mousgoum-architecture-in-and-ouy-of-africa/978-0-226-57183-6/","publisher":"University of Chicago Press (catalogue listing)"},{"title":"Architectural designs that adapt to environment: Mousgoum dwellings, Pouss, Cameroon","url":"https://radio-future-africa.org/adaptive-architecture-mousgoum-dwellings-pouss-cameroon/","publisher":"Radio Future Africa"}],"company":null,"country":null},{"slug":"must-farm","title":"Must Farm","category":"history","type":"place","summary":"A Bronze Age stilt village in Cambridgeshire, England, that burned about 850 BCE, preserving roundhouse roofs of straw, turf and clay in the river silt.","body":"Must Farm is a Late Bronze Age settlement near Whittlesey, east of Peterborough in Cambridgeshire, England. Around 850 BCE a group of timber roundhouses built on stilts over a slow-moving river caught fire and collapsed into the water. Silt sealed the charred structures, preserving posts, walls, roofs and household contents. The Cambridge Archaeological Unit excavated the site in 2015-16 in a £1.1 million project funded by Historic England and the building-products company Forterra, and the full results were published in 2024 in two reports by the McDonald Institute for Archaeological Research.\n\n## The settlement\n\n- **Structures:** four large roundhouses and a square entrance structure were uncovered. About half the original settlement was destroyed by 20th-century quarrying, so it was probably about twice as large.\n- **Stilts:** buildings stood about 2 m (6.6 ft) above the river, with walkways linking some houses, inside a 2 m high fence of sharpened posts.\n- **Size:** the largest roundhouse had almost 50 m² (540 sq ft) of floor space; roundhouse one was about 8 m (26 ft) across.\n- **Lifespan:** unseasoned timber shows the village was built less than a year before it burned. Remains of young lambs suggest the fire happened in late summer or early autumn.\n- **Population:** up to about 60 people in family units.\n\n## The roofs\n\nMust Farm gives unusually complete evidence of a prehistoric British roof.\n\n- **Frame:** rafters met at an apex over the centre of each house and probably overhung the walls as short eaves. They rested on a ring of large split timbers at the top of the wall, carried on posts. The wall plates have mortise joints; the rafters do not. Rafters were closely spaced, so purlins may not have been needed. Many fell in a fan pattern onto the channel floor.\n- **Covering:** the final reports describe a roof of three layers: straw for insulation, then turf, then clay on top. During excavation the team noted large quantities of burnt turf, often containing charred cereal roots, indicating it was cut from cultivated ground.\n- **Clay:** deposits of mostly unburnt clay, roughly a tonne per house, clustered around the central posts. One theory is that clay packed around the rafters at the apex shielded them from fire, possibly forming part of a smoke outlet; this would explain why apex rafters survived unburnt while the eave ends were heavily charred.\n\nThe weight of turf and clay implies carefully engineered stilts and a stout frame.\n\n## Significance for roofing history\n\nMany earlier reconstructions of British roundhouses assumed a covering of reed or straw thatch alone. The evidence of a layered roof with turf and clay over straw shows that roundhouse roofs could be heavier and more fire-resistant than many reconstructions assume. The site gives a rare physical check on assumptions about covering and smoke venting used in other roundhouse reconstructions.","key_facts":[{"label":"Date","value":"About 850 BCE"},{"label":"Location","value":"Near Whittlesey, Cambridgeshire, England"},{"label":"Excavated","value":"2015-16, Cambridge Archaeological Unit"},{"label":"Roof layers","value":"Straw, turf and clay"},{"label":"Stilt height","value":"About 2 m (6.6 ft) above the river"}],"regions":["Europe"],"aliases":["Must Farm pile-dwelling settlement","Must Farm Bronze Age settlement","Britain's Pompeii"],"related":["bronze-age-roundhouse","crannog","sod-roof","thatch","prehistory-of-roofing"],"company":null,"sources":[{"title":"Must Farm Bronze Age settlement findings (press release)","url":"https://sciencedaily.com/releases/2024/03/240320122600.htm","publisher":"ScienceDaily / University of Cambridge"},{"title":"Dig Diary 30: Our Houses: What We Know and What We Don't - Part Three","url":"https://mustfarm.com/?p=836","publisher":"Must Farm"},{"title":"Roundhouse (dwelling)","url":"https://en.wikipedia.org/wiki/Roundhouse_(dwelling)","publisher":"Wikipedia"}],"country":null},{"slug":"muzibu-azaala-mpanga","title":"Muzibu Azaala Mpanga (Kasubi Tombs)","category":"world-roofing","type":"place","summary":"The Muzibu Azaala Mpanga at Kasubi, Kampala, is the great thatched dome housing Buganda royal tombs; burned in 2010, it was rebuilt by 2023.","body":"The Muzibu Azaala Mpanga is the main building of the Tombs of Buganda Kings at Kasubi, on a hill in Kampala, Uganda. It is a circular structure under a vast dome of grass thatch, built of wooden poles, reeds and wattle without any structural masonry in its original form. It is widely described as one of the most remarkable buildings in sub-Saharan Africa made entirely of plant materials.\n\n## History\n\nKasubi was the palace of Muteesa I, the 35th Kabaka (king) of Buganda, who built it in 1882 to replace an earlier palace of 1820. When he died in 1884 he was buried there, and the palace became a royal burial ground. Four Kabakas lie in the main building: Muteesa I, Mwanga II (who died in exile in the Seychelles; his remains were returned in 1910), Daudi Chwa II, and Sir Edward Muteesa II (who died in London; his remains were returned in 1971).\n\nA renovation in 1938 added steel, concrete columns and bricks, mostly concealed within the traditional fabric. The site was inscribed on the UNESCO World Heritage List in December 2001 under criteria (i), (iii), (iv) and (vi); the property covers 26.8 ha (66 acres).\n\n## Construction\n\nThe building is round in plan and roughly 31 m (102 ft) in circumference and 7.5 m (25 ft) high. Its thatch rests on structural rings of palm fronds; one widely cited account counts 52 rings, matching the 52 traditional clans of the Baganda. The floor is laid with lemongrass and palm-leaf mats, and bark cloth hangs inside, including a curtain that screens the tombs. Thatching at Kasubi is a hereditary specialism of the Ngeye clan, while bark cloth comes from the Ngo clan.\n\n## The 2010 fire and rebuilding\n\nOn the evening of 16 March 2010 a fire largely destroyed the main buildings. The inner sanctum was reported protected and the royal remains intact. In July 2010 the World Heritage Committee placed the site on the List of World Heritage in Danger.\n\nReconstruction, led by the Ugandan authorities with UNESCO, started in 2014. It was financed partly by a crowd-funding campaign called *Etofaali* and by the government of Japan. The rebuilt Muzibu Azaala Mpanga was completed in the summer of 2023. On 12 September 2023, at its session in Riyadh, the World Heritage Committee removed the site from the Danger List, noting a new fire-fighting system and volunteer fire-fighters trained from the local community.\n\n## Significance for roofing\n\nKasubi shows the limits and strengths of large thatched structures: a grass dome of this size gives a cool, quiet interior and can be built with local skills, but it is exposed to fire and needs regular renewal by trained thatchers. The rebuilding kept traditional materials and clan roles while adding a modern fire-fighting system.\n\n## Sources and gaps\n\nExact diameter and thatch thickness, the species of grass used, and the cause of the 2010 fire: published information is limited.","key_facts":[{"label":"Location","value":"Kasubi hill, Kampala, Uganda"},{"label":"Built","value":"1882 (palace of Muteesa I); royal tomb from 1884"},{"label":"Size","value":"About 7.5 m (25 ft) high, about 31 m (102 ft) circumference"},{"label":"Materials","value":"Wooden poles, reeds, wattle and daub, grass thatch on palm-frond rings"},{"label":"UNESCO","value":"Inscribed December 2001; in Danger 2010-2023"},{"label":"Fire","value":"16 March 2010; rebuilt 2014-2023"}],"regions":["Africa"],"aliases":["Kasubi Tombs","Tombs of Buganda Kings at Kasubi","Kasubi royal tombs"],"related":["roofing-in-uganda","thatch","thatch-maintenance","dome","roofing-in-east-africa"],"sources":[{"title":"Tombs of Buganda Kings at Kasubi","url":"https://whc.unesco.org/en/list/1022","publisher":"UNESCO World Heritage Centre"},{"title":"Kasubi Tombs","url":"https://en.wikipedia.org/wiki/Kasubi_Tombs","publisher":"Wikipedia"},{"title":"Tombs of Buganda Kings at Kasubi removed from the List of World Heritage in Danger","url":"https://whc.unesco.org/en/news/2607/","publisher":"UNESCO World Heritage Centre"},{"title":"UN to assist Uganda rebuild burned World Heritage List site","url":"https://news.un.org/en/story/2010/04/335202","publisher":"UN News"}],"company":null,"country":null},{"slug":"nail-pops","title":"Nail Pops","category":"problems-maintenance","type":"term","summary":"Roofing or deck nails that work upward and lift or puncture the shingle above, creating a bump and a possible leak point.","body":"A nail pop occurs when a nail that holds a shingle, or the sheathing below it, backs out of the wood far enough to raise the shingle above or push through it. On an asphalt shingle roof it often appears as a small bump or a tented spot in an otherwise flat course. Sometimes the nail head breaks through and is exposed to rain.\n\n## Causes\n\n- **Wood movement.** Rafters, trusses and sheathing swell and shrink with seasonal moisture. Each cycle can push a smooth-shank nail slightly outward.\n- **Nails that missed framing.** Sheathing nails that missed the rafter, or shingle nails driven into a gap between boards, have little holding power.\n- **Under-driven nails** left standing above the surface by an incorrectly set nail gun.\n- **Short or wrong nails** that do not penetrate the deck properly.\n- **Attic moisture** that makes the deck wood move more than normal.\n- **Thermal and wind loads** that tug on shingles over time.\n\n## Why it matters\n\nA lifted shingle can lose its seal and be more vulnerable to wind. A nail head that has punched through the shingle above can let water run down the shank into the deck, causing localised rot and leaks. Inspectors also note that pops cluster where moisture problems exist below.\n\n## Repair\n\nTypical repairs involve carefully lifting the shingle, pulling or driving the popped nail, refastening with a new nail beside the old hole (into solid wood where possible), sealing the old hole, and replacing any damaged shingle. Where many sheathing nails are popping, the cause is often in the deck or attic, for example excessive moisture or nails that missed the framing, and screws or ring-shank nails may be used when the roof is next replaced. A related issue on metal roofs is fastener back-out.","key_facts":[{"label":"Appearance","value":"Small bumps or exposed nail heads in shingle courses"},{"label":"Main cause","value":"Seasonal wood movement and poor nail holding"},{"label":"Linked issue","value":"Attic moisture"}],"regions":["Global","North America"],"aliases":["popped nails","nail backing out"],"related":["fastener-back-out","asphalt-shingle","roof-deck","attic-condensation","roofing-nailer"],"company":null,"sources":[{"title":"Nail Pops in Roof Shingles","url":"https://www.jlconline.com/how-to/exteriors/nail-pops-in-roof-shingles_o/","publisher":"Journal of Light Construction"},{"title":"Q&A: Sheathing Nails Popping Through Shingles","url":"https://www.jlconline.com/how-to/roofing/q-a-sheathing-nails-popping-through-shingles_o","publisher":"Journal of Light Construction"},{"title":"Roofing Nails That Pop Up","url":"https://www.askthebuilder.com/roofing-nails-that-pop-up/","publisher":"Ask the Builder"}],"country":null},{"slug":"nail-sickness","title":"Nail Sickness","category":"problems-maintenance","type":"term","summary":"Failure of the nails holding slates or tiles, usually through corrosion, so units slip or fall even though the slates themselves are sound.","body":"Nail sickness is a long-established British and Irish term for the failure of the fixings on a slate or tile roof. Iron or poorly protected steel nails corrode, their heads rust off, or the shank thins just above the batten or deck, so slates slide out of position or fall. It can occur while the slates themselves still have many years of life left.\n\n## Causes\n\n- **Nail material.** Plain iron, steel cut nails, steel wire nails and lightly zinc-coated nails tend to corrode. Copper, stainless steel and some high-quality alloy nails usually outlast the slate; US slate specialists report that copper and stainless steel slating nails are typically found in good condition on older roofs.\n- **Moisture concentration.** Corrosion is often worst where water collects: below valleys, around dormers, or where a low-slope roof drains onto the slates.\n- **Condensation** under unventilated roofs.\n- **Ageing timber battens** that lose their grip on the nail.\n\n## Signs\n\nThe most visible symptom is individual slates slipping down the roof or lying loose in gutters. Rows of slipped slates, rust staining, and slates that lift easily in wind all suggest widespread nail failure.\n\n## Repair options\n\n- **Isolated slips** can be refixed with metal strips known as tingles or slate hooks, typically copper, lead or stainless steel, nailed between the slates of the course below and bent up to hold the slate. These are a recognised repair but are visible and are generally treated as a short- to medium-term measure on heritage roofs.\n- **Widespread nail sickness** usually calls for stripping the roof, salvaging the sound slates, replacing battens or underlay as needed, and relaying the slates with copper or stainless fixings.\n\nWhen reinstalling, slaters keep exposure and headlap consistent. Slate specialists note that reducing headlap to gain exposure is not acceptable because it weakens weather resistance. Heritage authorities generally advise like-for-like repair and expert advice on listed or historic buildings.","key_facts":[{"label":"Main cause","value":"Corrosion of iron or poorly coated steel nails"},{"label":"Visible sign","value":"Slipped or fallen slates"},{"label":"Spot repair","value":"Tingles or slate hooks"}],"regions":["Europe","North America","Global"],"aliases":["slate nail failure","nail-sick roof"],"related":["natural-slate","slate-delamination","slate-ripper","tile-slippage"],"company":null,"sources":[{"title":"Slate Roof Condition Assessment Surveys - Part 2 - Slating Nails","url":"https://www.slateassociation.org/slate-roof-condition-assessment-surveys-part-2/","publisher":"Slate Roofing Contractors Association of North America"},{"title":"True slate roofing","url":"https://spab.org.uk/node/405","publisher":"Society for the Protection of Ancient Buildings"},{"title":"Replacing roof slates","url":"https://www.practicaldiy.com/general-building/roof-repair/slates-repair.php","publisher":"Practical DIY"},{"title":"Technical note: roofs","url":"https://www.communities-ni.gov.uk/technical-note-roofs","publisher":"Department for Communities Northern Ireland"}],"country":null},{"slug":"najdi-mud-roofs","title":"Najdi Mud Roofs","category":"world-roofing","type":"article","regions":["Middle East"],"company":null,"summary":"Flat earth roofs on tamarisk timber of the Najdi mud-brick architecture of central Arabia, edged by shurfat parapets.","aliases":["Najdi roof","Najdi architecture","Diriyah mud architecture","shurfat"],"body":"Najdi architecture is the mud-brick building tradition of Najd, the central plateau of the Arabian Peninsula in present-day Saudi Arabia. Its houses, palaces and mosques have flat roofs carried on timber and finished with earth, and walls topped with distinctive stepped parapets. The style's best-known ensemble is At-Turaif in ad-Diriyah, near Riyadh, a UNESCO World Heritage site founded in the 15th century and described by UNESCO as an outstanding example of the Najdi architectural and decorative style.\n\n## Materials\n\nStone and good timber were scarce on the plateau, so builders worked mainly in mud: sun-dried bricks made from earth, water, straw and other fibres, finished with mud plaster. Roofs and doors were made of tamarisk wood, and the roofs of mosques also used tamarisk log beams with clay and thatch. Walls were very thick, which helped insulate interiors from extreme heat. UNESCO highlights the use of adobe even in major palatial complexes at At-Turaif.\n\n## The roof edge\n\n- **Shurfat:** hand-moulded, upward-tapering, crenellated battlements at the tops of walls. They act as the parapet of the roof terrace and help protect the facade from rainwater.\n- **Triangle frieze:** a horizontal band of incised, inverted triangles beneath the shurfat also serves as rainwater protection.\n- **Furjat (or luhuj):** small rectangular, triangular, square or arrow-shaped openings high in walls that let air and light in and can vent smoke and hot air.\n\n## Layout\n\nHouses were typically one or two low storeys around an inner courtyard. The style influenced building in Kuwait and inland Qatar, and many examples survive in Riyadh, including Masmak Fortress and the Murabba Palace.\n\n## Care\n\nLike all earth roofs, Najdi roofs depend on regular replastering after rain. The geometric decoration and parapets are part of the same protective skin.\n## Sources and gaps\n\nDetailed figures for roof thickness and timber spacing: published information is limited.","key_facts":[{"label":"Region","value":"Najd, central Saudi Arabia"},{"label":"Walls","value":"Sun-dried mud brick with mud plaster"},{"label":"Roof timber","value":"Tamarisk"},{"label":"Parapet","value":"Shurfat (crenellated battlements)"},{"label":"Key site","value":"At-Turaif, ad-Diriyah (UNESCO)"}],"related":["roofing-in-saudi-arabia","mud-roof","flat-roof","parapet","roofing-in-kuwait","roofing-in-qatar"],"sources":[{"title":"Najdi architecture","url":"https://en.wikipedia.org/wiki/Najdi_architecture","publisher":"Wikipedia"},{"title":"At-Turaif District in ad-Dir'iyah","url":"https://whc.unesco.org/en/list/1329","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"nakamal","title":"Nakamal","category":"world-roofing","type":"article","summary":"Traditional meeting house of chiefs in Vanuatu, a centre of kastom governance, anecdotally built to withstand cyclones.","body":"A *nakamal* is the traditional meeting place of chiefs in Vanuatu, used for meetings on governance, decision-making and teaching. It is central to *kastom*, the body of customary practice; one local saying holds that without the nakamal there is no place to house kastom. Nakamals are roofed buildings made from local materials, and in rural areas they are often described as hurricane shelters, being believed, on anecdotal evidence, to have been designed to resist high winds and cyclones.\n\n## Materials and skills\n\nThe built form depends on knowledge and skills held within each community and passed between generations. Across Vanuatu, the main traditional roof covering is *natangura*, thatch made from sago-palm leaves (see [sago palm thatch](/sago-palm-thatch)); in the 2010 Household Income and Expenditure Survey, natangura was recorded on 41.7% of main houses.\n\n## Cyclone Pam\n\nCategory 5 Tropical Cyclone Pam crossed Vanuatu on 13 March 2015 and destroyed large quantities of traditional building materials. Together with an El Niño drought that prevented new plantings, it left communities short of the materials needed to repair nakamals.\n\nIn response, UNESCO's Intangible Cultural Heritage Fund supported a project from August to December 2015 (US$23,908) to safeguard indigenous vernacular architecture. It documented six damaged nakamals before and after the cyclone, assessed their structural condition, and evaluated the risk of losing the building knowledge held in each community, with the aim of compiling good practice for reviving building skills.\n\n## Threats\n\nIdentified threats include imported building materials and techniques, lack of heritage recognition, shortages of local materials, loss of skills across generations, future cyclones and lack of funding for urgent protection.\n\n## Related forms\n\nThe nakamal belongs to a Pacific family of community meeting houses that includes the Fijian [bure](/fijian-bure), the Kiribati [maneaba](/maneaba) and the Samoan [fale tele](/samoan-fale).\n## Sources and gaps\n\nDetailed published descriptions of nakamal construction are scarce.","key_facts":[{"label":"Country","value":"Vanuatu"},{"label":"Use","value":"Chiefs’ meetings, governance, teaching (kastom)"},{"label":"Typical thatch","value":"Natangura (sago-palm leaf)"},{"label":"Hazard","value":"Cyclones (TC Pam, 2015)"},{"label":"Safeguarding","value":"UNESCO ICH project, 2015"}],"regions":["Oceania"],"aliases":["Nakamal","Vanuatu meeting house"],"related":["roofing-in-vanuatu","sago-palm-thatch","palm-thatch","maneaba","fijian-bure","samoan-fale"],"company":null,"sources":[{"title":"Nakamals, an indigenous architecture form","url":"https://www.preventionweb.net/go/52980","publisher":"PreventionWeb"},{"title":"Safeguarding indigenous vernacular architecture and building knowledge in Vanuatu","url":"https://ich.unesco.org/en/assistances/safeguarding-indigenous-vernacular-architecture-and-building-knowledge-in-vanuatu-01214","publisher":"UNESCO Intangible Cultural Heritage"},{"title":"Vanuatu HIES 2010, roof material (H4)","url":"https://catalog.ihsn.org/catalog/8492/variable/F2/V14?name=H4","publisher":"IHSN Survey Catalog"}],"country":null},{"slug":"national-building-code-of-canada","title":"National Building Code of Canada (NBC)","summary":"The National Building Code of Canada is the model building code published by the National Research Council and adopted, with changes, by provinces and territories.","body":"The **National Building Code of Canada (NBC)** is Canada's model building code. It is developed by the Canadian Commission on Building and Fire Codes and published by the National Research Council of Canada (NRC) as part of the \"Codes Canada\" family, which also includes national fire, plumbing and energy codes. The current edition is NBC 2020, published in two volumes and available as a free PDF from the NRC as well as in print.\n\n## History and legal status\n\nThe federal government published the first National Building Code in 1941. It was revised roughly every five years from 1960 to 1995, followed by editions in 2005, 2010, 2015 and 2020. The 2005 edition introduced an objective-based format, linking each requirement to the objective it serves.\n\nThe NBC is a **model code**: it has no legal force until a province, territory or municipality adopts it. Some provinces adopt it largely as written; others, such as British Columbia, Alberta, Ontario and Quebec, publish their own codes based on it with provincial changes. Users must check which edition applies in their jurisdiction.\n\n## Structure and roofing\n\nThe NBC is divided into Parts. Two matter most for roofing:\n\n- **Part 9 – Housing and Small Buildings.** Covers buildings of three storeys or less and up to 600 m² (about 6,460 ft²) in building area. It is highly prescriptive, designed so that builders can apply it directly. Part 9 contains rules for roofing materials, slopes, underlays, eave protection in snow climates, flashing and attic ventilation.\n- **Part 5 – Environmental Separation, and Part 4 – Structural Design.** For larger buildings, roofs must be designed to resist wind, snow and rain loads using Part 4, and to control heat, air and moisture under Part 5.\n\n## Referenced standards\n\nThe NBC references many CSA standards for roofing products, including the [CSA A123](/csa-a123-series) series for asphalt shingles, roll roofing and membranes, and [CSA A123.21](/csa-a123-21) for the dynamic wind uplift testing of membrane roofs. Fire performance of roof coverings is tested under CAN/ULC-S107.\n\n## Product evaluation\n\nInnovative products not covered by referenced standards can be evaluated by the [Canadian Construction Materials Centre](/ccmc) (CCMC), whose assessments help building officials accept them under the code.","key_facts":[{"label":"Publisher","value":"National Research Council of Canada"},{"label":"Developer","value":"Canadian Commission on Building and Fire Codes"},{"label":"First edition","value":"1941"},{"label":"Current edition","value":"NBC 2020"},{"label":"Part 9 limits","value":"Up to 3 storeys and 600 m² (6,460 ft²)"}],"regions":["North America"],"aliases":["NBC","NBCC","National Building Code of Canada 2020","Codes Canada"],"related":["csa-a123-21","roof-ventilation","eave-protection"],"sources":[{"title":"National Building Code of Canada 2020","url":"https://nrc.canada.ca/en/certifications-evaluations-standards/codes-canada/codes-canada-publications/national-building-code-canada-2020","publisher":"National Research Council Canada"},{"title":"National Building Code of Canada","url":"https://en.wikipedia.org/wiki/National_Building_Code_of_Canada","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"national-building-code-of-india","title":"National Building Code of India and IS Roofing Standards","summary":"The National Building Code of India, published by the Bureau of Indian Standards, guides building design; roofing is covered through IS standards.","body":"The **National Building Code of India (NBC)** is a national instrument giving guidelines for regulating building construction across India. It is published by the **Bureau of Indian Standards (BIS)**, the national standards body. The code was first published in 1970 and has since been revised, with the current edition being **NBC 2016**.\n\nThe NBC is a model document. Local authorities, development authorities and states incorporate it into their building bye-laws, sometimes with changes, so the rules in force can differ from city to city.\n\n## Structure of NBC 2016\n\nNBC 2016 is organized into Parts 0 to 12 across two volumes:\n\n- **Volume 1** – Part 0 Integrated Approach; Part 1 Definitions; Part 2 Administration; Part 3 Development Control Rules; Part 4 Fire and Life Safety; Part 5 Building Materials; Part 6 Structural Design.\n- **Volume 2** – Part 7 Construction Management; Part 8 Building Services; Part 9 Plumbing Services; Part 10 Landscape, Signs and Outdoor Display Structures; Part 11 Approach to Sustainability; Part 12 Asset and Facility Management.\n\n## Roofing in the NBC\n\nRoofing is not a single chapter. Relevant provisions are spread across:\n\n- **Part 4** – fire safety, including combustibility of roof coverings\n- **Part 5** – building materials, which references Indian Standards (IS) for roofing products\n- **Part 6** – structural design, including loads such as wind on roofs and cladding\n- **Part 9** – plumbing, including rainwater drainage from roofs\n- **Part 11** – sustainability, covering topics such as rainwater harvesting and reflective roofs\n\n## IS standards\n\nBIS publishes Indian Standards (IS) for roofing materials such as coated steel sheet, clay and concrete tiles, fibre-cement sheets and waterproofing systems. Some products must carry the BIS (ISI) certification mark by government order, while certification is voluntary for most others. Steel products are among the categories where certification is mandatory.\n\n## Background on BIS\n\nBIS's predecessor, the Indian Standards Institution, was set up by a resolution in 1946. BIS was established as a statutory body in 1986, and the Bureau of Indian Standards Act, 2016, which replaced the 1986 Act, came into force on 12 October 2017.\n\n## Practice\n\nFlat reinforced concrete roofs with waterproofing and surface treatments are common in Indian cities, while metal sheet and tile roofs are widespread in industrial, rural and coastal buildings. The NBC and IS standards apply across all of these, but enforcement depends on local building authorities.","key_facts":[{"label":"Publisher","value":"Bureau of Indian Standards (BIS)"},{"label":"First published","value":"1970"},{"label":"Current edition","value":"NBC 2016 (Parts 0–12, two volumes)"},{"label":"Legal status","value":"Adopted through local building bye-laws"},{"label":"Product standards","value":"Indian Standards (IS)"}],"regions":["South Asia"],"aliases":["NBC India","NBC 2016","IS codes","Indian Standards roofing"],"related":["metal-roofing","clay-roof-tile","flat-roof"],"sources":[{"title":"National Building Code","url":"https://www.bis.gov.in/standards/technical-department/national-building-code/","publisher":"Bureau of Indian Standards"},{"title":"Bureau of Indian Standards","url":"https://en.wikipedia.org/wiki/Bureau_of_Indian_Standards","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"national-construction-code-australia","title":"National Construction Code (Australia)","summary":"Australia's National Construction Code is the national set of minimum technical requirements for buildings and plumbing, published by the Australian Building Codes Board.","body":"The **National Construction Code (NCC)** is Australia's primary set of technical design and construction provisions for buildings and plumbing. It is maintained and published by the Australian Building Codes Board (ABCB), a joint body of the federal, state and territory governments, and is given legal effect through state and territory building legislation. The NCC is revised on a three-year cycle; NCC 2022 replaced NCC 2019.\n\n## Structure\n\nThe NCC has three volumes:\n\n- **Volume One** – mainly commercial, multi-residential and public buildings (Class 2 to 9 buildings).\n- **Volume Two** – mainly houses and small domestic buildings (Class 1 and 10 buildings).\n- **Volume Three** – the Plumbing Code of Australia, which includes roof drainage.\n\nVolumes One and Two together form the **Building Code of Australia (BCA)**.\n\n## How compliance works\n\nThe NCC sets performance requirements. They can be met by:\n\n- a **Deemed-to-Satisfy (DTS)** solution, the most common route, which follows prescriptive provisions and referenced Australian Standards; or\n- a **Performance Solution** (formerly \"alternative solution\"), which shows by analysis, testing or expert judgement that the performance requirements are met.\n\n## Roofing provisions\n\nRoofs are affected by several parts of the NCC, including structure (wind, snow and other loads), weatherproofing, fire, energy efficiency, condensation management and bushfire protection. The NCC calls up Australian Standards for detailed rules. Among those commonly used for roofs are AS/NZS 1170 for structural design actions (with Part 2 covering wind), AS 1562 for the design and installation of sheet roof and wall cladding, and AS 3959 for construction in bushfire-prone areas, which sets requirements by Bushfire Attack Level (BAL).\n\nNCC 2022 also increased energy-efficiency requirements and introduced more detailed condensation management provisions, which affect roof ventilation and sarking, and raised the minimum freeboard for valley gutters to 15 mm (0.6 in).\n\n## Roof drainage\n\nThe Plumbing Code (Volume Three) and its referenced standards govern the sizing of gutters, downpipes and overflow provisions. Overflow from box and valley gutters into buildings has been a recurring cause of damage, which is reflected in tighter provisions.\n\n## Related schemes\n\nProduct conformity can be demonstrated through evidence such as test reports, certificates and, historically, the CodeMark certification scheme. Building surveyors (certifiers) in each state check compliance.","key_facts":[{"label":"Publisher","value":"Australian Building Codes Board (ABCB)"},{"label":"Volumes","value":"One (commercial), Two (housing), Three (plumbing)"},{"label":"BCA","value":"Volumes One and Two"},{"label":"Update cycle","value":"Every 3 years"},{"label":"Compliance routes","value":"Deemed-to-Satisfy or Performance Solution"}],"regions":["Oceania"],"aliases":["NCC","Building Code of Australia","BCA","NCC 2022"],"related":["wildfire-roofing","nzbc-e2"],"sources":[{"title":"National Construction Code","url":"https://en.wikipedia.org/wiki/National_Construction_Code","publisher":"Wikipedia"},{"title":"NCC","url":"https://ncc.abcb.gov.au/","publisher":"Australian Building Codes Board"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"national-federation-of-roofing-contractors","title":"National Federation of Roofing Contractors (NFRC)","summary":"The NFRC is the UK's largest roofing trade association, founded in 1892 and based in London, with over 1,350 members.","body":"The National Federation of Roofing Contractors (NFRC) is a trade association for the roofing industry in the United Kingdom. It was founded in 1892 and describes itself as the largest roofing trade association in the UK. It is based at Roofing House in central London, and its website is nfrc.co.uk.\n\nNFRC has over 1,350 members, including specialist roofing contractors, manufacturers and distributors of roofing products, merchants and service providers.\n\n## Activities\n\n- **Technical guidance.** NFRC's technical team produces guidance notes and technical documents in response to member concerns, covering pitched roofing (slate, tile), flat roofing, roof windows, fixings and more. These are available through its Knowledge Hub and technical library; some are free to the public.\n- **Competent Person Scheme.** In 2012 NFRC set up a Competent Person Scheme (CPS) that allows registered roofers to self-certify that roof refurbishment work in England and Wales meets current building regulations, instead of applying separately to building control.\n- **Standards.** NFRC takes part in British and European standards work affecting roofing, such as the UK code of practice for slating and tiling (BS 5534).\n- **Safety and skills.** It promotes training, safety and competence, including support for apprenticeships and work under the Building Safety Act.\n- **Awards and events.** It runs the UK Roofing Awards.\n\n## For consumers\n\nHomeowners can check whether a contractor is an NFRC member through the federation, and can ask whether re-roofing work will be self-certified through the Competent Person Scheme or notified to building control.\n\n## Related UK bodies\n\nThe UK has a number of specialist roofing associations, several of which share offices with NFRC, such as the Liquid Roofing and Waterproofing Association. Others include the Single Ply Roofing Association and the Confederation of Roofing Contractors. The Construction Industry Training Board (CITB) funds training across the sector, and the Health and Safety Executive (HSE) regulates safety. Membership of NFRC is voluntary; the UK has no general licensing requirement for roofers.","key_facts":[{"label":"Founded","value":"1892"},{"label":"Headquarters","value":"London, England"},{"label":"Members","value":"Over 1,350"},{"label":"Competent Person Scheme","value":"Since 2012"}],"regions":["Europe"],"aliases":["NFRC"],"related":["confederation-of-roofing-contractors","liquid-roofing-and-waterproofing-association","citb","bs-5534","trustmark"],"company":{"founded":"1892","headquarters":"London, England","website":"https://www.nfrc.co.uk","known_for":["UK roofing technical guidance","NFRC Competent Person Scheme","UK Roofing Awards"]},"sources":[{"title":"NFRC home page","url":"https://www.nfrc.co.uk/","publisher":"NFRC"},{"title":"About us","url":"https://www.nfrc.co.uk/about-us","publisher":"NFRC"},{"title":"International roofing community gathers for IFD Congress 2019","url":"https://roofingtoday.co.uk/international-roofing-community-gathers-for-ifd-congress-2019","publisher":"Roofing Today"}],"category":"organizations","type":"organization","country":null},{"slug":"nrca","title":"National Roofing Contractors Association (NRCA)","summary":"NRCA is the main U.S. trade association for roofing contractors, founded in 1886, publishing technical manuals and Professional Roofing magazine.","body":"The National Roofing Contractors Association (NRCA) is a trade association representing roofing contractors and related businesses in the United States, with members in other countries as well. Founded in 1886, it is one of the oldest construction trade associations in North America. Its website is nrca.net.\n\nNRCA's members include roofing contractors of all sizes, along with manufacturers, distributors, architects, consultants and building owners. The association works on technical guidance, education, workforce development and government relations for the roofing trade.\n\n## Technical work\n\nNRCA is widely known for its technical publications, which describe accepted practice for installing low-slope and steep-slope roof systems. These manuals are used by contractors, designers and inspectors as reference documents, alongside building codes and manufacturer instructions. NRCA also takes part in the development of building codes and industry standards that affect roofing.\n\n## Publications and education\n\nThe association publishes *Professional Roofing*, a monthly magazine for roofing professionals. It also offers training courses, online learning and certification programmes for installers and supervisors. NRCA is the official sponsor of the International Roofing Expo, a large annual roofing trade show in the United States, where it also runs education sessions.\n\n## Advocacy\n\nNRCA represents the industry before the U.S. Congress and federal agencies on topics such as worker safety, immigration and workforce, taxes and building regulation. It works with state and regional roofing associations on these issues.\n\n## Relationship to other bodies\n\nMany U.S. states and regions have their own roofing contractor associations, such as the Florida Roofing and Sheet Metal Contractors Association and the Western States Roofing Contractors Association. These regional bodies often work alongside NRCA. In Canada, the Canadian Roofing Contractors Association plays a similar national role. Membership in NRCA is voluntary and is not a licence; contractor licensing in the United States is handled by states and local governments.","key_facts":[{"label":"Founded","value":"1886"},{"label":"Country","value":"United States"},{"label":"Magazine","value":"Professional Roofing (monthly)"},{"label":"Website","value":"nrca.net"}],"regions":["North America"],"aliases":["NRCA","National Roofing Contractors' Association"],"related":["professional-roofing-magazine","international-roofing-expo","canadian-roofing-contractors-association","how-to-find-a-licensed-roofer"],"company":{"founded":"1886","website":"https://www.nrca.net","known_for":["Roofing technical manuals","Professional Roofing magazine","Industry advocacy"]},"sources":[{"title":"National Roofing Contractors Association","url":"https://en.wikipedia.org/wiki/National_Roofing_Contractors_Association","publisher":"Wikipedia"},{"title":"About NRCA","url":"https://theroofingexpo.com/en/about/nrca.html","publisher":"International Roofing Expo"},{"title":"National Roofing Contractors' Association publications","url":"https://www.thenbs.com/PublicationIndex/documents?Pub=NRCA","publisher":"NBS"}],"category":"organizations","type":"organization","country":null},{"slug":"national-slate-association","title":"National Slate Association (NSA)","summary":"The National Slate Association is a U.S. organisation for the natural slate roofing industry, first formed in 1922 and reformed in 2002.","body":"The National Slate Association (NSA) is a non-profit organisation in the United States that brings together slate quarries, roofing contractors, consultants, architects and suppliers working with natural slate roofing. An association under this name started in 1922. It later became inactive and was reformed in 2002. The association lists a business address in Falconer, New York, and its website is slateassociation.org.\n\n## History\n\nIn the early 20th century, slate was a major roofing material in the eastern United States, with quarries in Pennsylvania, Vermont, New York, Virginia and Maine. Slate use later declined as cheaper roofing materials spread, and the original association did not continue. A new association under the same name was formed in 2002, at a time of renewed interest in slate for restoration and new construction.\n\n## Publications\n\n- **Slate Roofs: Design and Installation Manual.** The NSA's main publication sets out recommended practice for designing, installing and repairing slate roofs in North America. It covers slate grading, headlap, fastening with copper or stainless steel nails, flashing details and roof deck requirements.\n- **Slate specification guide** for architects and specifiers.\n- **Technical bulletins** and a mobile field guide for contractors.\n\n## Why guidance matters\n\nA well-made slate roof can last a very long time, but performance depends on details. Common problems include using the wrong nails, nailing too tightly, insufficient headlap on low pitches, and mismatched replacement slates. Because many slate roofs are on older or listed buildings, repairs often need to match the original slate source, size and colour.\n\n## International context\n\nSlate roofing traditions are strong in Wales, Spain, France, Germany and Brazil, each with its own sizes and fixing methods. European slate is covered by the standard EN 12326. The NSA focuses on North American practice, but it shares interests with groups such as the Slate Roofing Contractors Association of North America and European slate federations.","key_facts":[{"label":"First formed","value":"1922"},{"label":"Reformed","value":"2002"},{"label":"Address","value":"Falconer, New York, USA"},{"label":"Key publication","value":"Slate Roofs: Design and Installation Manual"}],"regions":["North America"],"aliases":["NSA"],"related":["natural-slate","slate-roofing-contractors-association"],"company":{"founded":"1922","headquarters":"Falconer, New York, USA","website":"https://www.slateassociation.org","known_for":["Slate Roofs: Design and Installation Manual"]},"sources":[{"title":"National Slate Association","url":"https://www.slateassociation.org/","publisher":"National Slate Association"},{"title":"Slate Roofing Contractors Association of North America","url":"https://www.slateroofers.org/","publisher":"SRCA"}],"category":"organizations","type":"organization","country":null},{"slug":"national-society-of-master-thatchers","title":"National Society of Master Thatchers (NSMT)","summary":"The National Society of Master Thatchers is a UK body of individual master thatchers, formed in 1967, which inspects members' work.","body":"The National Society of Master Thatchers (NSMT) is an organisation in the United Kingdom whose members are individual master thatchers. It was first formed in September 1967 as the National Society of Master Thatchers Associations, linking county and regional thatching groups. It took its current name in 1977. The legal entity is National Society of Master Thatchers Limited, and its website is nsmt.co.uk.\n\n## Membership\n\nUnlike many trade associations, the NSMT admits individual thatchers rather than companies. Thatchers who apply have their work inspected, and those whose work meets the society's standard become members as Master Thatchers. The society publishes its members list so homeowners can find thatchers.\n\n## Thatching in the UK\n\nEngland has one of the largest concentrations of thatched buildings in Europe, many of them listed as historic. Three main materials are used:\n\n- **Water reed** (Phragmites), a long-lasting material laid with the butt ends exposed to give a smooth, brushed finish.\n- **Combed wheat reed**, wheat straw laid butt-end down, common in south-west England.\n- **Long straw**, threshed wheat straw laid more loosely, giving a softer, shaggier look, traditional in parts of southern and eastern England.\n\nRidges are often renewed more frequently than the main coat. Choice of material is often controlled on listed buildings to preserve local character, which involves the local planning authority and heritage advisers such as Historic England.\n\n## Related topics\n\nFire safety is an important issue for thatched buildings. Measures include chimney maintenance, spark arrestors, fire barriers under new thatch and fire-retardant treatments. Specialist firms such as Thatching Advisory Services provide advice and products in this area.\n\n## Other countries\n\nThatch is also used in the Netherlands, Denmark, Germany, Ireland, South Africa and Japan, each with its own associations and techniques. In the Netherlands, for example, reed thatch is common on modern houses as well as historic ones.","key_facts":[{"label":"Formed","value":"September 1967"},{"label":"Current name since","value":"1977"},{"label":"Members","value":"Individual master thatchers, admitted after work inspection"},{"label":"Country","value":"United Kingdom"}],"regions":["Europe"],"aliases":["NSMT","National Society of Master Thatchers Associations"],"related":["thatch","water-reed-thatch","thatching-advisory-services","historic-england"],"company":{"founded":"1967","website":"https://www.nsmt.co.uk","known_for":["Inspection-based membership for master thatchers"]},"sources":[{"title":"National Society of Master Thatchers","url":"https://www.nsmt.co.uk/","publisher":"National Society of Master Thatchers"},{"title":"Thatching Advisory Services","url":"https://www.thatchingadvisoryservices.co.uk/","publisher":"Thatching Advisory Services"}],"category":"organizations","type":"organization","country":null},{"slug":"natufian-round-houses","title":"Natufian Round Houses","category":"history","type":"article","summary":"Round, semi-sunken houses with dry-stone footings built by the Natufian culture of the Levant about 15,000-11,500 years ago, before farming.","body":"The Natufian culture of the Levant, dated roughly 15,000 to 11,500 years before present, built some of the earliest permanent houses in the world. Natufian communities were sedentary or semi-sedentary before agriculture, and their settlements were larger and longer-lived than those of earlier hunter-gatherers. Their characteristic dwelling was a round, one-room house with its floor cut into the ground and its lower walls faced with stone.\n\n## Ain Mallaha (Eynan)\n\nThe best-known example is Ain Mallaha in the upper Jordan Valley of northern Israel, discovered in 1954 and excavated by Jean Perrot, Monique Lechevalier and François Valla of the CNRS. It was occupied about 14,326 to 12,180 calibrated years before present, and the village was built in three phases. The first two phases had massive stone-built structures; the third had smaller ones.\n\nFeatures of the houses:\n\n- **Form:** circular, semi-subterranean, one-room huts, in Kathleen Kenyon's description, who counted about 50.\n- **Walls:** dry stone lining the sunken floor, with surrounding walls up to 1.2 m (3.9 ft) high.\n- **Floors:** paved with flat slabs in places, with hearths inside and decoration in white or red.\n- **Roof:** wooden posts set inside the house carried the roof, which was probably covered with brushwood or animal hides. Nothing of the superstructure survives.\n\nBurials were placed inside some dwellings; one house contained the graves of 11 people and another, dwelling 131, held 12.\n\n## Other sites\n\nNatufian occupation also used caves and their terraces, as at El Wad on Mount Carmel. At Abu Hureyra in Syria, phase 1A dwellings of about 11,300-10,800 cal BCE are described as pit dwellings. Storage facilities appear at some sites but not all.\n\n## Significance for roofing history\n\nThe Natufian house combines three ideas that recur through later building: digging the floor down to gain height and shelter, using stone for the part of the wall most exposed to damp and wear, and carrying a light roof on internal posts. Because the roof sat on posts inside the stone ring rather than on the wall itself, its span and weight were limited, which fits the modest diameters of these houses. The round plan continued into the early Neolithic of the region before rectangular houses became common.","key_facts":[{"label":"Culture","value":"Natufian, about 15,000-11,500 years BP"},{"label":"Key site","value":"Ain Mallaha, northern Israel"},{"label":"Plan","value":"Round, semi-subterranean, one room"},{"label":"Roof support","value":"Internal wooden posts"},{"label":"Likely covering","value":"Brushwood or animal hides"}],"regions":["Middle East"],"aliases":["Ain Mallaha houses","Eynan houses","Natufian houses"],"related":["ohalo-ii","pit-house","prehistory-of-roofing","prehistoric-shelters-and-early-thatch"],"company":null,"sources":[{"title":"Ain Mallaha","url":"https://en.wikipedia.org/wiki/Ain_Mallaha","publisher":"Wikipedia"},{"title":"Natufian culture","url":"https://en.wikipedia.org/wiki/Natufian_culture","publisher":"Wikipedia"}],"country":null},{"slug":"natural-slate","title":"Natural Slate","type":"article","summary":"A fine-grained metamorphic rock split into thin, durable roofing units; among the longest-lasting roof coverings in use.","body":"Natural slate is a fine-grained metamorphic rock that can be split into thin, flat sheets and used as a roof covering. It forms when shale, mudstone or volcanic ash is compressed and mildly heated deep underground. The pressure aligns flat mineral grains so that the rock develops a strong cleavage, a set of planes along which it splits cleanly. That property, combined with very low water absorption, makes slate one of the most durable natural roofing materials.\n\n## Composition and properties\n\nQuartz, illite and chlorite typically make up most of the rock. Accessory minerals can include iron sulphides such as pyrite, iron oxides and carbonates. These minor minerals matter: pyrite can oxidise and rust-stain or weaken a slate, and carbonates can dissolve in acidic rain. Good roofing slate absorbs less than about 0.4% water by weight, which gives strong frost resistance, and it is non-combustible.\n\n## Quarrying and production\n\nSlate is extracted in blocks from open pits or underground workings, cut into manageable pieces, and then split by hand along the cleavage using a chisel. The split sheets are trimmed (\"dressed\") to rectangular or patterned shapes and, for nail fixing, holed. Splitting remains a skilled manual job even in highly mechanised modern quarries.\n\n## Producing regions\n\nHistoric and current sources include Wales, Cornwall and Cumbria in Britain; Galicia in Spain; the Anjou region of France; Belgium, Germany, Italy and Portugal; Vermont, New York, Pennsylvania, Virginia and Maine in the United States; Newfoundland in Canada; Minas Gerais in Brazil; China; and parts of Australia. Spain is the largest producer and exporter today and supplies about 90% of Europe's natural roofing slate.\n\n## Standards and quality\n\n- **Europe**: EN 12326 sets test methods and classifies slate for water absorption (A1/A2), sulphur-dioxide exposure (S1-S3) and thermal cycling (T1-T3). UK house-builder guidance has asked for A1, S1 and T1 slates.\n- **North America**: ASTM C406 grades slate S1, S2 or S3 by expected service life, with S1 rated at over 75 years; the International Building Code requires roofing slate to comply with it.\n\n## On the roof\n\nUS model codes set a minimum slope of 4:12 (about 18°) for slate, with a headlap of 2-4 in (51-102 mm) depending on pitch. Standard slate weighs about 700-900 lb per square (roughly 34-44 kg/m²), and heavy architectural slate can exceed 1,200 lb per square, so roof framing must be checked. Slates are fixed with copper or stainless-steel nails, or with metal hooks.\n\n## Lifespan\n\nProperly installed nailed or hooked slate roofs are commonly expected to last about 60-125 years, and the best slates can last several centuries. Failure usually comes from corroded nails (\"nail sickness\"), damaged flashings or deteriorating battens rather than from the stone itself.\n","key_facts":[{"label":"Rock type","value":"Fine-grained metamorphic (from shale, mudstone or ash)"},{"label":"Water absorption","value":"Typically under 0.4%"},{"label":"Weight (standard)","value":"About 700-900 lb per square (34-44 kg/m²)"},{"label":"Minimum slope (IBC)","value":"4:12 (about 18°)"},{"label":"Standards","value":"EN 12326 (Europe); ASTM C406 (North America)"},{"label":"Typical life","value":"About 60-125 years; best slates far longer"}],"regions":["Global","Europe","North America","Latin America","East Asia"],"aliases":["roofing slate","slate roof","slate tile"],"related":["welsh-slate","spanish-slate","vermont-slate","brazilian-slate","slate-hook-fixing","en-12326","astm-c406","fibre-cement-slate","synthetic-slate","nail-sickness","stone-slate"],"sources":[{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"},{"title":"Slate industry","url":"https://en.wikipedia.org/wiki/Slate_industry","publisher":"Wikipedia"},{"title":"Slate Roofing: Innovation in an Old Industry, Part II: Standards, Codes, Testing and More","url":"https://iibec.org/publication-post/slate-roofing-innovation-in-an-old-industry-part-ii-standards-codes-testing-and-more/","publisher":"IIBEC"},{"title":"Natural Slate & Synthetic Tile Roofing: Installation Fundamentals, Headlap & Fastening","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/metal-tile-slate-steep-slope-systems/slate-synthetic-tile-roofing","publisher":"Open Exam Prep"}],"category":"materials","company":null,"country":null},{"slug":"ndebele-house-painting","title":"Ndebele House Painting","category":"world-roofing","type":"article","summary":"Southern Ndebele tradition, from the 18th century, of painting bold geometric designs on the mud walls of homesteads in South Africa.","body":"Ndebele house painting is the practice, mainly by women, of decorating the walls of homesteads with bold geometric patterns. It is associated above all with the Southern Ndebele of South Africa, and is also practised by Northern Ndebele communities in the Matobo area of Zimbabwe. It is one of the best-known forms of African architectural decoration.\n\n## Origins\n\nIn the early 18th century the Ndebele lived in grass huts. From the mid-18th century they began building mud-walled houses, and symbols began to appear on houses and walls; the Ndzundza Ndebele developed their characteristic style during the 18th century. The war with the Boers in 1883 and the hardship that followed are often linked to the development of expressive symbols in the paintings. In 2016 the US Ambassadors' Fund for Cultural Preservation funded documentation of the tradition.\n\n## Technique\n\nWalls are first whitewashed. Early paints were natural earth pigments in browns and black, applied with the fingers in V shapes and triangles, often based on beadwork patterns. Later painters used bundles of twigs and feathers as brushes, and the palette widened to red, yellow to gold, sky blue, green and sometimes pink, outlined in black on a white ground. Large tools fill flat areas and small brushes do outlines and detail.\n\n## The house and its roof\n\nThe painted wall is part of a homestead of thatched houses. A Southern Ndebele building vocabulary recorded by Franco Frescura includes:\n\n- *amakapa*: the roof; *amakapa ibalelo*: a roof rafter.\n- *ibalelo*: a member spanning between posts, used as a batten or ring beam.\n- *apokorwana*: the eaves overhang.\n- *intuthi*: a tie-beam at the inner apex that holds a central post during construction and remains after thatching.\n- *isidlogorwana*: the capping at the roof apex.\n- *iboda*: the drum wall of a cone-on-cylinder house.\n- *amathuri*: the verandah; *ithuri*: a low wall enclosing a verandah room.\n- *ikhuphu*: clay wall plaster, often mixed with cow dung; *ubulongo*: clay and dung floor finish.","key_facts":[{"label":"Region","value":"South Africa (Southern Ndebele); Matobo, Zimbabwe"},{"label":"Period","value":"From the 18th century"},{"label":"Surface","value":"Whitewashed mud walls"},{"label":"Roof term","value":"Amakapa (roof)"}],"regions":["Africa"],"aliases":["Ndebele painted houses","Ndebele wall painting"],"related":["roofing-in-south-africa","roofing-in-zimbabwe","rondavel","thatch","roofing-in-southern-africa"],"company":null,"sources":[{"title":"Ndebele house painting","url":"https://en.wikipedia.org/wiki/Ndebele_house_painting","publisher":"Wikipedia"},{"title":"Glossary - South Ndebele terms","url":"https://francofrescura.sahistory.org.za/glossary/glossary-south-ndebele-terms/","publisher":"Franco Frescura / South African History Online"}],"country":null},{"slug":"new-gourna","title":"New Gourna","category":"world-roofing","type":"place","summary":"Village near Luxor, Egypt, built 1946-1952 by Hassan Fathy with mud-brick Nubian vaults and domes; subject of a UNESCO safeguarding project.","body":"New Gourna (also spelled New Qurna) is a planned village on the west bank of the Nile at Luxor, designed by the Egyptian architect Hassan Fathy and built between 1946 and 1952. It is a widely cited modern attempt to roof an entire community with earth, using mud-brick vaults and domes in place of timber, steel or concrete.\n\n## Purpose\n\nThe village was built to rehouse the community of Old Gourna, whose houses stood on top of the ancient Theban tombs. Moving residents was intended to reduce damage to the tombs.\n\n## Roofs\n\nEarth was the main construction material. Fathy used mud brick and Nubian-inspired forms: rooms roofed with barrel vaults and domes built without formwork, enclosed courtyards and thick walls for passive cooling (see Nubian vault and Hassan Fathy). Public buildings included a khan and a market.\n\n## Outcome\n\nMany intended residents did not settle in the village, and Fathy himself later described the experiment as a failure. Around 40% of the original buildings had been lost when the site was placed on the World Monuments Watch in 2010.\n\n## Safeguarding\n\nUNESCO launched a safeguarding project for New Gourna in 2009, in consultation with Egypt's Ministry of Culture and the Luxor Governorate. Surveys ran in 2010 and a first scientific committee met in October 2010. UNESCO identified these threats:\n\n- lack of maintenance, with major buildings collapsing;\n- a falling number of original mud-brick houses;\n- collapse of public buildings, including the khan and market;\n- encroachment on open spaces;\n- inadequate infrastructure;\n- reinforced-concrete buildings out of scale with the village.\n\nThe village's condition illustrates a recurring issue with earth roofs: they depend on regular maintenance, and the spread of concrete buildings is listed among the threats to it.","key_facts":[{"label":"Built","value":"1946-1952"},{"label":"Architect","value":"Hassan Fathy"},{"label":"Roof type","value":"Mud-brick vaults and domes"},{"label":"UNESCO safeguarding project","value":"Launched 2009"}],"regions":["Africa","Middle East"],"aliases":["New Qurna","New Gurna","Gourna al-Jadida"],"related":["hassan-fathy","nubian-vault","roofing-in-egypt","mud-roof","dome"],"company":null,"sources":[{"title":"Safeguarding Project of Hassan Fathy's New Gourna Village","url":"https://whc.unesco.org/en/activities/637","publisher":"UNESCO World Heritage Centre"},{"title":"Hassan Fathy","url":"https://en.wikipedia.org/wiki/Hassan_Fathy","publisher":"Wikipedia"},{"title":"Safeguarding Hassan Fathy's Architectural Legacy in New Gourna","url":"https://moic.gov.eg/en/project/289","publisher":"Egyptian Ministry of International Cooperation"}],"country":null},{"slug":"nzbc-e2","title":"New Zealand Building Code Clause E2 (External Moisture)","summary":"Clause E2 of the New Zealand Building Code requires roofs and walls to resist the entry and build-up of external moisture; E2/AS1 is the main acceptable solution.","body":"The **New Zealand Building Code (NZBC)** is a performance-based code set out in Schedule 1 of the Building Regulations 1992. Clause **E2 External Moisture** requires buildings to provide adequate resistance to penetration by, and accumulation of, moisture from outside. It applies to roofs, walls and other parts of the building envelope, and is administered by the Ministry of Business, Innovation and Employment (MBIE).\n\n## Requirements\n\nE2's performance requirements include:\n\n- preventing water from entering the building\n- preventing absorption and transmission of moisture that could cause damage or undue dampness\n- preventing water from accumulating within the construction\n- allowing any moisture that does enter to dissipate\n\n## Compliance documents\n\nBecause the NZBC is performance-based, MBIE publishes compliance documents that are deemed to satisfy the code:\n\n- **E2/AS1** – the main Acceptable Solution, widely used for timber-framed buildings. It contains details for roof claddings (including profiled metal, membranes and tiles), flashings, penetrations and junctions within its scope limits.\n- **E2/AS2, E2/AS3 and E2/AS4** – other Acceptable Solutions for specific construction types.\n- **E2/VM1 and E2/VM2** – Verification Methods, which use testing to demonstrate compliance.\n\nMBIE's current set includes fourth editions of E2/AS1, AS2, AS3 and VM1 effective from 28 July 2025, along with E2/VM2 (2nd edition, 2021) and E2/AS4 (1st edition, 2019).\n\nDesigners can also use alternative solutions outside these documents, which the building consent authority assesses case by case.\n\n## Context: the leaky building crisis\n\nE2 has been central to New Zealand construction since the \"leaky building\" crisis of the 1990s and 2000s, when many monolithic-clad homes suffered water damage and decay. Revisions to E2/AS1 introduced cavity construction for many wall claddings and stricter flashing details, and greater scrutiny of roof-to-wall junctions.\n\n## Roofing practice\n\nFor metal roofing, E2/AS1 is often used together with the industry's [NZ Metal Roof and Wall Cladding Code of Practice](/nz-metal-roof-code-of-practice), which gives far more detail on profiles, fastening, flashings and minimum pitches. Structural wind and snow loads on roofs are addressed under Clause B1 (Structure), which references the AS/NZS 1170 loading standards.","key_facts":[{"label":"Code","value":"New Zealand Building Code, Clause E2"},{"label":"Administered by","value":"MBIE"},{"label":"Main Acceptable Solution","value":"E2/AS1 (4th edition, effective 28 July 2025)"},{"label":"Verification Methods","value":"E2/VM1, E2/VM2"},{"label":"Covers","value":"Roofs, walls and envelope moisture"}],"regions":["Oceania"],"aliases":["E2/AS1","NZBC E2","E2 External Moisture"],"related":["nz-metal-roof-code-of-practice","national-construction-code-australia","roof-flashing","leaky-homes-crisis"],"sources":[{"title":"E2 External moisture","url":"https://www.building.govt.nz/building-code-compliance/e-moisture/e2-external-moisture/","publisher":"Ministry of Business, Innovation and Employment (NZ)"},{"title":"NZ Metal Roof and Wall Cladding Code of Practice","url":"https://www.metalroofing.org.nz/cop","publisher":"New Zealand Metal Roofing Manufacturers"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"new-zealand-metal-roofing-manufacturers","title":"New Zealand Metal Roofing Manufacturers (NZMRM)","summary":"NZMRM is the association of New Zealand metal roofing manufacturers that publishes the NZ Metal Roof and Wall Cladding Code of Practice.","body":"The New Zealand Metal Roofing Manufacturers association (NZMRM) is an industry body representing companies that roll-form and supply metal roofing and wall cladding in New Zealand. Its website is metalroofing.org.nz.\n\n## Code of Practice\n\nNZMRM's best-known work is the **NZ Metal Roof and Wall Cladding Code of Practice**, a comprehensive design and installation guide for metal roofs and walls. It is recognised as a related document for Acceptable Solution E2/AS1 of the New Zealand Building Code, which covers external moisture (weathertightness). The code is updated regularly; the version listed on the association's website in 2026 was v26.09. It is published online so designers, roofers and building consent authorities can use the current version.\n\nThe Code of Practice covers topics such as:\n\n- choice of material and coating for different exposure environments, from sheltered inland sites to severe marine and geothermal areas;\n- minimum roof pitches for different profiles;\n- fastener types, spacing and placement for wind loads;\n- flashing design, including ridge, barge, apron and penetration flashings;\n- allowance for thermal expansion of long sheets;\n- compatibility between metals and with other materials, to avoid corrosion;\n- maintenance, including washing of areas not rain-washed.\n\n## Context\n\nProfiled metal roofing, mainly corrugated and trapezoidal coated steel, is the most common roof type in New Zealand, and metal tiles are also widely used. Strong winds, high rainfall and salt-laden air near the coast make correct design and installation important for service life.\n\n## Related bodies\n\nThe Roofing Association of New Zealand (RANZ) represents roofing contractors, while BRANZ carries out independent building research. Roofing work on homes is also subject to New Zealand's Licensed Building Practitioner scheme. In Australia, roofing practice for metal is guided by standards such as AS 1562.1 and by manufacturers' and industry guides.","key_facts":[{"label":"Country","value":"New Zealand"},{"label":"Key publication","value":"NZ Metal Roof and Wall Cladding Code of Practice"},{"label":"Code status","value":"Related document for E2/AS1 of the NZ Building Code"},{"label":"Version (2026)","value":"v26.09"}],"regions":["Oceania"],"aliases":["NZMRM","New Zealand Metal Roofing Manufacturers Association","NZ Metal Roof and Wall Cladding Code of Practice"],"related":["roofing-association-of-new-zealand","branz","corrugated-iron"],"company":{"website":"https://www.metalroofing.org.nz","known_for":["NZ Metal Roof and Wall Cladding Code of Practice"]},"sources":[{"title":"NZ Metal Roofing Manufacturers","url":"https://www.metalroofing.org.nz/","publisher":"NZMRM"},{"title":"Roofing Association of New Zealand","url":"https://www.ranz.co.nz/","publisher":"RANZ"}],"category":"organizations","type":"organization","country":null},{"slug":"newar-pagoda-roof","title":"Newar Pagoda Roof","category":"world-roofing","type":"term","summary":"The Newar pagoda roof is the tiered timber roof of Kathmandu Valley temples, carried on carved struts and covered with small terracotta jhingati tiles.","body":"The **Newar pagoda roof** is the stacked, multi-roofed form of the temples built by the Newar people of the Kathmandu Valley in Nepal. A brick shrine is topped by a series of diminishing roofs, each a pyramid of timber covered with small terracotta tiles and carried on a ring of carved wooden struts. These roofs dominate the Durbar Squares of Kathmandu, Patan and Bhaktapur, which with four other monument zones form the Kathmandu Valley World Heritage Site, a UNESCO World Heritage Site.\n\n## Structure\n\nThe temples are built of fired brick laid in mud mortar, with timber for the floors, the roof frames and the decorated windows and doors. Each roof projects well beyond the wall below it and is propped by inclined wooden **struts** set between the wall and the eaves. The struts are richly carved with deities, mythical animals and other figures, and they are among the most celebrated woodwork in South Asia. The roof tiers step in as they rise, so each wall storey is shaded and sheltered from monsoon rain by the roof above it.\n\n## Tiles and metal\n\nThe roofs are covered with **small, overlapping terracotta tiles**, known in the valley as *jhingati*. The most important temples have roof ornaments, finials and sometimes entire roofs of gilded brass or copper. Records of the building of the Nyatapola Temple note that its lowest roof had been tiled with jhingati by May 1702.\n\n## History\n\nAccording to UNESCO, the blending of Buddhist and Hindu art in the valley goes back at least to the 5th century CE, and the greatest period of building was roughly 1500 to 1800, under the Malla kings. The roots of the Newar style are traced to the Licchavi period (about 400-750 CE). Nepalese craftsmen, among them Arniko, carried the style abroad, and some writers suggest that the multiple-roofed pagoda may have originated in the valley and spread from there to India, China, Indochina and Japan, a claim that remains speculative.\n\n## Notable examples\n\n- **Nyatapola Temple, Bhaktapur**: built between December 1701 and July 1702 for King Bhupatindra Malla, with five roofs. It is one of only two five-roofed temples in the valley and is around 30 m (about 100 ft) high, with figures varying between sources. It survived both the 1934 Nepal-Bihar earthquake and the 2015 Gorkha earthquake.\n- **Changu Narayan**: a pagoda temple on one of the oldest religious sites in the valley, with an inscription of the 5th century CE.\n- The temples of **Hanuman Dhoka (Kathmandu), Patan and Bhaktapur Durbar Squares**.\n\n## Earthquakes\n\nThe Kathmandu Valley is highly seismic. The 2015 Gorkha earthquake damaged or brought down many historic temples, and restoration has been carried out by local communities with international support including UNESCO.","key_facts":[{"label":"Region","value":"Kathmandu Valley, Nepal"},{"label":"Covering","value":"Small overlapping terracotta tiles (jhingati); gilded metal on some temples"},{"label":"Structure","value":"Brick walls, timber roofs on carved struts"},{"label":"Tallest example","value":"Nyatapola, Bhaktapur (1702), five roofs"},{"label":"Main period","value":"About 1500-1800 CE"}],"regions":["South Asia"],"aliases":["Nepalese pagoda","Newari pagoda","tiered temple roof","jhingati tile"],"related":["pagoda-roof","clay-roof-tile","roofing-in-nepal","earthquake-roofing","pyatthat","bhutanese-shingle-roof"],"company":null,"sources":[{"title":"Kathmandu Valley","url":"https://whc.unesco.org/en/list/121/","publisher":"UNESCO World Heritage Centre"},{"title":"Nyatapola","url":"https://en.wikipedia.org/wiki/Nyatapola","publisher":"Wikipedia"},{"title":"Newar architecture","url":"https://en.wikipedia.org/wiki/Newar_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"nordic-waterproofing","title":"Nordic Waterproofing","category":"manufacturers","type":"company","summary":"Nordic Waterproofing is a Helsingborg, Sweden-based group of roofing and waterproofing brands in northern Europe, majority-owned by Kingspan since 2024.","body":"Nordic Waterproofing Holding AB is a producer and supplier of waterproofing products for buildings and infrastructure in the Nordic countries and nearby markets. It is headquartered in Helsingborg, Sweden. The Irish building-envelope group Kingspan took a controlling stake in 2024 and later increased it to about 63 percent; the company's application to delist its shares was approved in March 2025.\n\n## Brands\n\nThe group operates through a number of national brands, including:\n\n- Mataki and Trebolit.\n- Phonix Tag and Phonix Tag Materialer.\n- Kerabit and Vesikattopalvelu.\n- SealEco.\n- Byggpartner, Hetag Tagdaekning and RVT.\n- Taasinge Elementer.\n- Veg Tech and Urban Green.\n- Distri Pond and EG Trading.\n\n## Products and services\n\nNordic Waterproofing's range covers bituminous roofing membranes, EPDM products, prefabricated roof elements, green infrastructure such as sedum roofs, and solar energy solutions mounted on or integrated with roofs. Unlike many manufacturers, it also provides installation services, so part of its business is roofing contracting.\n\n## Context\n\nBituminous membranes are the dominant covering for flat roofs in Scandinavia, where roofs must cope with snow loads, freeze-thaw cycles and long wet periods. Kingspan's acquisition of Nordic Waterproofing was part of its wider move into roofing and waterproofing, following purchases of Ondura and Derbigum in 2022.\n\n## Green roofs\n\nVegetated roofs, such as sedum roofs, add a drainage layer, growing medium and plants over the waterproofing. They retain rainwater, slow run-off and protect the membrane from ultraviolet light and temperature swings, but add weight that the structure must be designed to carry.","key_facts":[{"label":"Headquarters","value":"Helsingborg, Sweden"},{"label":"Majority owner","value":"Kingspan (controlling stake 2024, about 63%)"},{"label":"Brands","value":"Mataki, Phonix Tag, Kerabit, SealEco, Veg Tech"}],"regions":["Europe"],"aliases":["Nordic Waterproofing Holding","Mataki","Phonix Tag","Kerabit"],"related":["kingspan","epdm-roofing","green-roof"],"company":{"headquarters":"Helsingborg, Sweden","website":"https://www.nordicwaterproofing.com","parent":"Kingspan Group","known_for":["Roofing membranes","EPDM products","Green roof systems"]},"sources":[{"title":"Nordic Waterproofing","url":"https://www.nordicwaterproofing.com/","publisher":"Nordic Waterproofing"},{"title":"Kingspan Group","url":"https://en.wikipedia.org/wiki/Kingspan_Group","publisher":"Wikipedia"}],"country":null},{"slug":"notre-dame-de-paris-roof-fire","title":"Notre-Dame de Paris Roof Fire (2019)","category":"history","type":"event","summary":"The fire of 15 April 2019 destroyed Notre-Dame's 13th-century oak roof 'forest', its lead covering and spire; both were rebuilt in oak and lead by 2024.","body":"On **15 April 2019**, a fire broke out in the roof of **Notre-Dame de Paris** at about 18:18 local time. Within hours it destroyed the cathedral's medieval timber roof and its 19th-century spire, and brought down part of the stone vaults. The reconstruction that followed became one of the most closely watched roofing projects in history.\n\n## The medieval roof\n\nThe cathedral's roof framing was made largely of **13th-century oak**, so dense with timbers that it was nicknamed the **\"forest\"**. It was sheathed in lead; the roof and spire together carried more than 400 tonnes of lead. The original 13th-century spire (*flèche*), probably built around 1220-1230, was removed in 1786. In the 19th century the architect **Eugène Viollet-le-Duc** recreated it as an oak structure covered in lead; the whole flèche weighed about 750 tonnes.\n\n## The fire\n\nThe fire destroyed the flèche and the oak beams that supported the lead roof.\n\n## Rebuilding decisions\n\nA national debate followed over whether to rebuild the roof in modern materials such as steel, titanium or concrete, or as it was. A Senate amendment requiring identical restoration was rejected by the National Assembly, and the July 2019 law left the spire's form open. In the end the roof and spire were rebuilt largely in their original form and materials: **oak timber sheathed in lead**.\n\n## Timber\n\nFrom February 2021, about 1,000 mature oaks were selected from French forests. Each was 50-90 cm (20-35 in) in diameter, 8-14 m (26-46 ft) tall and several hundred years old. The cut timber had to dry for 12-18 months. Wood and stone were sourced from regions used in the original construction, and the felled trees were to be replaced by new planting.\n\n## Completion\n\nThe new flèche was put in place on **16 December 2023**, topped by a gilded cockerel designed by architect Philippe Villeneuve. Notre-Dame reopened on **7 December 2024**, while work on the surroundings continued into 2025-2028.\n\n## Funding\n\nPledges exceeded €1 billion within a week. By September 2021 more than 320,000 donors had given over €840 million.","key_facts":[{"label":"Date of fire","value":"15 April 2019"},{"label":"Original roof timber","value":"13th-century oak"},{"label":"Lead on roof and spire","value":"Over 400 tonnes"},{"label":"Oaks selected for rebuild","value":"About 1,000"},{"label":"Reopened","value":"7 December 2024"}],"regions":["Europe"],"aliases":["Notre-Dame fire","Notre-Dame roof","the forest"],"related":["medieval-lead-roofs","history-of-timber-roof-framing","westminster-hall-roof"],"company":null,"sources":[{"title":"Notre-Dame fire","url":"https://en.wikipedia.org/wiki/Notre-Dame_fire","publisher":"Wikipedia"},{"title":"Notre-Dame de Paris","url":"https://en.wikipedia.org/wiki/Notre-Dame_de_Paris","publisher":"Wikipedia"}],"country":null},{"slug":"nubian-vault","title":"Nubian Vault","type":"article","summary":"Earth-brick vaulted roof built without formwork or timber, revived in Egypt by Hassan Fathy and now promoted across the Sahel.","body":"The Nubian vault is a method of roofing a room with a barrel vault of sun-dried earth bricks, built without any centring or formwork. The technique originated in Nubia, along the Nile in southern Egypt and northern Sudan, and is now used in the Sahel as an alternative to roofs that depend on imported sheet metal or scarce timber.\n\n## How it is built\n\nThe mason first builds the end (gable) walls. Bricks are then laid in inclined courses leaning against a gable wall, so each new course sticks to the one behind it while the mortar sets. Because the courses are tilted rather than vertical, no temporary support is needed. The curve of the vault follows the shape of a hanging chain, which keeps the structure in compression. The same principle can be used to build domes.\n\nThe whole roof is earth: walls, vault and finishing layers. Waterproofing is provided by a thick earth render on top, which needs maintenance after the rainy season.\n\n## Revival\n\nThe Egyptian architect Hassan Fathy saw the technique in the Nubian village of Abu al-Riche and revived it in the 1940s. He used it at New Gourna near Luxor, a planned village that was influential architecturally even though many intended residents did not settle there.\n\n## Sahel programme\n\nSince 2000 the association La Voûte Nubienne (AVN) has simplified and codified the method and trained local masons. Early work focused on Burkina Faso, Mali and Senegal. The association reports more than 8,500 buildings completed, including homes, schools and health centres, more than 4,900 masons trained and certified, and activity in seven countries.\n\n## Why it is used\n\n- **No timber.** Wood for roof beams is increasingly scarce and costly in the Sahel.\n- **No imported metal.** Corrugated iron roofs are expensive and become very hot.\n- **Thermal comfort.** Thick earth roofs and walls buffer daytime heat.\n- **Local skills.** The technique creates employment for trained masons.\n\n## Limitations\n\nEarth vaults are heavy, require skilled bricklaying and need a good protective render; standing water or poor drainage can damage them. Spans are modest, typically single rooms.","key_facts":[{"label":"Material","value":"Sun-dried earth bricks and earth mortar"},{"label":"Formwork","value":"None required"},{"label":"Revived by","value":"Hassan Fathy, 1940s"},{"label":"Promoted by","value":"La Voûte Nubienne (since 2000)"},{"label":"Reported buildings","value":"Over 8,500 (AVN)"}],"regions":["Africa","Middle East"],"aliases":["Voûte nubienne","Nubian vault technique"],"related":["roofing-in-west-africa","sahelian-earthen-roofs","djenne-earthen-architecture","barrel-vault-roof","mud-roof"],"sources":[{"title":"Nubian vault","url":"https://en.wikipedia.org/wiki/Nubian_vault","publisher":"Wikipedia"},{"title":"La Voûte Nubienne","url":"https://www.lavoutenubienne.org/","publisher":"Association La Voûte Nubienne"}],"company":null,"category":"world-roofing","country":null},{"slug":"nyakatsi","title":"Nyakatsi (Rwandan Thatched House)","category":"history","type":"event","summary":"Nyakatsi is the Kinyarwanda term for a grass-thatched house; Rwanda's 2009-2011 'Bye Bye Nyakatsi' campaign replaced them with metal-roofed homes.","body":"*Nyakatsi* is the Kinyarwanda term used for grass-thatched houses, the traditional dwellings of Rwanda, whose grass covering formed a dome or beehive shape. The form was used at every social level, up to the royal palace. From December 2009 the Rwandan government ran a national campaign, widely known as \"Bye Bye Nyakatsi\", to eliminate thatched houses and move families into homes with metal roofs.\n\n## The traditional house\n\nRwandan houses were roofed with grass. The royal residence was the grandest version. At the King's Palace Museum in Nyanza, a reconstruction of the 19th-century palace in traditional materials shows a beehive-shaped thatched dwelling formed of three huts, and visitor information notes that the huts of the old capital were built by the same methods. Similar beehive houses of poles and grass were built in neighbouring Burundi, where they are called *rugo* (see Mugamba rugo).\n\n## The Bye Bye Nyakatsi campaign\n\nThe Ministry of Local Government said the campaign began in December 2009, when about 120,000 Rwandan families lived in grass-thatched houses. By the end of March 2011, about 18,000 families remained to be rehoused; in Kigali, 1,093 replacement houses had been built for the 1,559 thatched houses recorded before the campaign. Officials gave as reasons the fire risk of thatch, especially as electricity spread, snakes and insects living in roofs, the recurring cost of repairing thatch through the rainy seasons, and the view that thatch was a symbol of poverty.\n\nThe government budgeted about US$10 million. The army distributed corrugated metal sheets and other materials, and many new houses of brick or stone were built through *umuganda*, Rwanda's community work days.\n\n## Criticism\n\nThe campaign was criticised by Batwa advocacy groups and international organisations. The Batwa organisation COPORWA reported that roofs, and in some cases whole homes, of 720 Batwa families were removed before replacement housing or sheets were supplied, leaving many in crowded temporary shelters; only about 100 of those families had new homes at the time. The local government minister acknowledged mistakes by some local leaders and said they had been ordered to find rented or shared housing for those affected. Commentators also suggested that national image was a motive alongside welfare.\n\n## Outcome\n\nBy the 2022 census, grass roofs had all but disappeared: in the public microdata file, grass accounted for about 0.01% of records, against 73.6% iron sheets and 26% local clay tiles (unweighted shares).\n\n## Sources and gaps\n\nThe final completion date of the campaign and the total number of houses rebuilt: published information is limited. The Kinyarwanda term for the traditional house type as a whole and details of traditional grass species and thatching technique were not found in published sources.","key_facts":[{"label":"Meaning","value":"Grass-thatched house (Kinyarwanda)"},{"label":"Campaign start","value":"December 2009"},{"label":"Families in thatched houses at start","value":"About 120,000"},{"label":"Remaining, March 2011","value":"About 18,000 families"},{"label":"Replacement roofing","value":"Corrugated metal sheets"},{"label":"Budget","value":"About US$10 million"}],"regions":["Africa"],"aliases":["Bye Bye Nyakatsi","anti-nyakatsi campaign","Rwandan beehive hut"],"related":["roofing-in-rwanda","thatch","corrugated-iron","mugamba-rugo","roofing-in-burundi","spread-of-corrugated-iron"],"sources":[{"title":"Rwanda: 'Bye Bye Nyakatsi' campaign","url":"https://www.ipsnews.net/?p=46195","publisher":"Inter Press Service"},{"title":"Rwandan 'anti-thatch' campaign leaves thousands of 'Pygmies' homeless","url":"https://survivalinternational.org/news/7154","publisher":"Survival International"},{"title":"Batwa Communities Respond to Anti-thatch Campaign in Rwanda","url":"https://firelightfoundation.org/blog/2011/05/04/batwa-communities-respond-to-the-anti-thatch-campaign-in-rwanda","publisher":"Firelight Foundation"},{"title":"King's Palace","url":"https://www.visitrwanda.com/interests/kings-palace/","publisher":"Visit Rwanda"},{"title":"King's Palace Museum Rukari","url":"https://en.wikipedia.org/wiki/King%27s_Palace_Museum_Rukari","publisher":"Wikipedia"},{"title":"Rwanda Population and Housing Census 2022: main material used for the roof (h05)","url":"https://microdatabk.statistics.gov.rw/catalog/109/variable/F2/V310?name=h05","publisher":"National Institute of Statistics of Rwanda"}],"company":null,"country":null},{"slug":"nz-metal-roof-code-of-practice","title":"NZ Metal Roof and Wall Cladding Code of Practice","summary":"The NZ Metal Roof and Wall Cladding Code of Practice is the industry guide to designing and installing metal roofing in New Zealand, published by NZMRM.","body":"The **New Zealand Metal Roof and Wall Cladding Code of Practice (COP)** is a technical guide published by the New Zealand Metal Roofing Manufacturers Inc. (NZMRM). It covers the design, installation, performance and transport of metal roof and wall cladding in New Zealand and is used by roofers, designers, building consent authorities and manufacturers.\n\n## Scope\n\nThe COP applies to buildings designed under NZS 3604 (the standard for timber-framed buildings), AS/NZS 1170 (structural loadings) and specific engineering design. It is presented as a means of meeting the performance provisions of the [New Zealand Building Code](/nzbc-e2) and supports compliance with the Health and Safety at Work Act 2015, including safe handling and installation.\n\nTopics include:\n\n- roof pitch and profile selection\n- fastener types, spacing and wind load resistance\n- flashings, penetrations, gutters and spouting\n- thermal expansion, condensation and underlay\n- corrosion, environmental categories and material compatibility (for example dissimilar metals and run-off)\n- foot traffic, handling, storage and transport\n- maintenance requirements\n\n## Versions and access\n\nThe COP is a living document, revised regularly. Version v26.09 was issued on 1 September 2026, described by NZMRM as one of its busiest revisions. It is available online after a simple one-time registration per device, and as a PDF for offline use.\n\n## Relationship to E2/AS1\n\nThe NZBC Acceptable Solution E2/AS1 includes basic metal roofing details, but within limits. The COP goes much further, covering more profiles, steeper and lower pitches, curved and crimped roofing, and specific situations such as severe marine environments. Designers often cite the COP in specifications, and it is widely treated as the reference for good practice.\n\n## Why it matters\n\nNew Zealand's climate combines high winds, heavy rainfall, strong UV and, in many areas, salt-laden coastal air. Metal roofing is the dominant residential roof covering in the country, so correct detailing has a large effect on building durability. The COP brings together manufacturer research and field experience, including the durability statements and environmental classifications that affect product choice and warranty conditions.\n\n## Comparable documents\n\nIn Australia, metal roofing design and installation is covered mainly by Australian Standards referenced through the [National Construction Code](/national-construction-code-australia), supported by manufacturer installation guides.","key_facts":[{"label":"Publisher","value":"New Zealand Metal Roofing Manufacturers Inc. (NZMRM)"},{"label":"Version","value":"v26.09 (1 September 2026)"},{"label":"Applies to","value":"Buildings under NZS 3604, AS/NZS 1170 or specific design"},{"label":"Access","value":"Online after registration; PDF available"}],"regions":["Oceania"],"aliases":["NZ Metal Roofing COP","Metal Roof Code of Practice","NZMRM COP"],"related":["nzbc-e2","metal-roofing","roof-flashing","national-construction-code-australia"],"sources":[{"title":"NZ Metal Roof and Wall Cladding Code of Practice","url":"https://www.metalroofing.org.nz/cop","publisher":"New Zealand Metal Roofing Manufacturers"},{"title":"E2 External moisture","url":"https://www.building.govt.nz/building-code-compliance/e-moisture/e2-external-moisture/","publisher":"Ministry of Business, Innovation and Employment (NZ)"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"oak-ridge-national-laboratory-building-envelope-research","title":"Oak Ridge National Laboratory Building Envelope Research","summary":"Oak Ridge National Laboratory's building research centre (BTRIC), set up in 1993, studies building envelopes and energy use for the U.S. Department of Energy.","body":"Oak Ridge National Laboratory (ORNL), a U.S. Department of Energy (DOE) research laboratory in Oak Ridge, Tennessee, carries out a long-running research program on building envelopes, including roofs and attics. Much of this work is based at the Building Technologies Research and Integration Center (BTRIC), established in 1993. BTRIC is DOE's only designated user facility dedicated to early-stage research and development in building technologies.\n\n## Facilities\n\nBTRIC is a research campus of about 60,000 square feet (5,600 m²). Its flagship facility is the Maximum Building Energy Efficiency Research Laboratory (MAXLAB), which supports large-scale testing of wall and building assemblies. Other test chambers measure how envelope components resist heat flow, how airtight they are, and how they handle moisture.\n\n## Research areas\n\nBTRIC research covers building envelopes, heating and cooling equipment, building systems integration, energy storage, interaction between buildings and the electric grid, sensors and controls, and modelling. In envelope work, it looks at the building as a filter that can store or reject solar energy.\n\nFor roofing, this envelope work includes how roof and attic assemblies gain, store and lose heat, how reflective surfaces affect the heat a roof absorbs from the sun, and how assemblies handle air leakage and moisture. Findings from national laboratory research of this kind feed into energy codes, product rating programs and design tools.\n\n## Access\n\nAs a user facility, BTRIC allows companies, universities and other researchers to use its equipment and expertise, typically through partnership agreements with DOE.\n\n## International context\n\nOther countries have similar public building research bodies, such as BRANZ in New Zealand, the Fraunhofer Institute for Building Physics in Germany, and the National Research Council Canada.","key_facts":[{"label":"Centre","value":"Building Technologies Research and Integration Center (BTRIC)"},{"label":"Established","value":"1993"},{"label":"Location","value":"Oak Ridge, Tennessee, USA"},{"label":"Size","value":"About 60,000 sq ft (5,600 m²)"}],"regions":["North America"],"aliases":["ORNL","BTRIC","ORNL Building Technologies Research and Integration Center"],"related":["cool-roof","cool-roof-rating-council","roof-ventilation","branz"],"company":{"founded":"1993","headquarters":"Oak Ridge, Tennessee, USA","website":"https://www.ornl.gov/facility/btric","parent":"Oak Ridge National Laboratory (U.S. Department of Energy)","known_for":["Building envelope and roof energy research","MAXLAB"]},"sources":[{"title":"Building Technologies Research and Integration Center","url":"https://www.ornl.gov/facility/btric","publisher":"Oak Ridge National Laboratory"},{"title":"CRRC: Cool Roof Rating Council","url":"https://basc.pnnl.gov/library/crrc-cool-roof-rating-council","publisher":"Pacific Northwest National Laboratory"}],"category":"organizations","type":"organization","country":null},{"slug":"osha","title":"Occupational Safety and Health Administration (OSHA)","summary":"OSHA is the U.S. federal agency that sets and enforces workplace safety rules, including fall protection for roofing work at 6 feet (1.8 m).","body":"The Occupational Safety and Health Administration (OSHA) is an agency of the U.S. Department of Labor that sets and enforces workplace safety and health standards. For roofing, its most important role is regulating fall protection, since roofing is one of the most dangerous construction trades. Its website is osha.gov.\n\n## Falls in construction\n\nOSHA states that falls are the leading cause of death in construction. Citing U.S. Bureau of Labor Statistics data, it reports that in 2024 there were 389 fatal falls to a lower level out of 1,034 construction fatalities. Roofs, ladders and scaffolds are the main sources of these falls.\n\n## Fall protection rules\n\n- In construction, OSHA requires fall protection when workers are at heights of **6 feet (1.8 m)** or more above a lower level. Other industries have different triggers: 4 feet in general industry, 5 feet in shipyards and 8 feet in longshoring.\n- Fall protection is required regardless of height when working over dangerous equipment or machinery.\n- Acceptable systems for roofing typically include guardrails, safety nets and personal fall arrest systems (PFAS) with full-body harnesses and anchors. On low-slope roofs, warning lines combined with safety monitoring may be used in some situations.\n- Holes, skylights and leading edges must be identified and protected.\n\n## Fall prevention campaign\n\nSince 2012, OSHA has run a fall prevention campaign with the National Institute for Occupational Safety and Health (NIOSH) and the NORA Construction Sector Council. Its message is to **Plan, Provide, Train**:\n\n- **Plan** each job, including the cost of safety equipment in estimates;\n- **Provide** the right fall protection, ladders and scaffolds, with fitted and inspected harnesses for workers who tie off;\n- **Train** every worker to recognise hazards and use equipment correctly.\n\nOSHA also promotes an annual National Safety Stand-Down, when employers pause work to talk about fall hazards.\n\n## State plans and other countries\n\nSome U.S. states run their own OSHA-approved safety programs with equal or stricter rules. Other countries have their own regulators, such as the Health and Safety Executive in Great Britain, WorkSafeBC in British Columbia and Safe Work Australia, each with different height thresholds and requirements.","key_facts":[{"label":"Parent","value":"U.S. Department of Labor"},{"label":"Construction fall protection trigger","value":"6 feet (1.8 m)"},{"label":"Fatal falls in construction (2024)","value":"389 of 1,034 deaths"},{"label":"Campaign","value":"Plan, Provide, Train (since 2012)"}],"regions":["North America"],"aliases":["OSHA","U.S. Occupational Safety and Health Administration"],"related":["roofing-fall-protection","personal-fall-arrest-system","health-and-safety-executive"],"company":{"website":"https://www.osha.gov","parent":"U.S. Department of Labor","known_for":["Fall protection standards","National Safety Stand-Down"]},"sources":[{"title":"Fall Protection","url":"https://www.osha.gov/fall-protection","publisher":"OSHA"},{"title":"Fall Prevention Campaign","url":"https://www.osha.gov/stopfalls","publisher":"OSHA"}],"category":"organizations","type":"organization","country":null},{"slug":"ohalo-ii","title":"Ohalo II","category":"history","type":"place","summary":"A submerged camp on the Sea of Galilee, Israel, about 23,000 years old, with six oval brush huts: among the oldest well-preserved built shelters.","body":"Ohalo II is a hunter-gatherer camp on the southwestern shore of the Sea of Galilee in Israel, dated to about 23,000 calibrated years before present. It came to light in 1989, when a long drought lowered the lake by about 9 m (30 ft). Dani Nadel of the University of Haifa led excavations in 1989-1991 and 1999-2000. Because the remains were sealed under water, the site preserves the floors of brush huts in unusual detail.\n\n## The huts\n\n- **Number:** six oval rings of charcoal mark where the dwellings stood.\n- **Size:** about 2.7 to 4.9 m (9 to 16 ft) long.\n- **Materials:** branches and brushwood. The simple design probably took only a few hours to put up.\n- **Hearths:** located outside the huts rather than inside.\n\nThe best-studied dwelling, Hut 1, was analysed by Nadel and Ella Werker in a 1999 paper in *Antiquity* describing the plant remains of a brush hut, which they then dated to about 19,000 years ago on an uncalibrated radiocarbon scale. The floor of Hut 1 produced more than 90,000 seeds of over 100 species, a grinding stone about 40 cm (16 in) long set on a sand and cobble base, and 132 retouched flint tools concentrated near the entrance. The excavation also produced some of the earliest known evidence of plant bedding.\n\n## How it survived\n\nThe camp burned after a short occupation, probably a few generations at most. Rising water then covered it, and fine clay and silt sealed the charred remains. Low-oxygen conditions slowed decay for millennia. The site covers a large area and may extend beyond what has been excavated.\n\n## Significance for roofing history\n\nOhalo II is often cited as the oldest known example of brush dwellings. It shows a light structure of branches forming both wall and roof, the kind of shelter that ethnographic records suggest was used widely by mobile groups. Most comparable sites have left only post holes; at Ohalo II, the burnt plant matter itself survives, which allows the materials to be identified rather than assumed.","key_facts":[{"label":"Age","value":"About 23,000 calibrated years BP"},{"label":"Location","value":"Sea of Galilee, Israel"},{"label":"Huts","value":"Six oval brush huts, 2.7-4.9 m (9-16 ft) long"},{"label":"Discovered","value":"1989, during a drought"},{"label":"Excavator","value":"Dani Nadel, University of Haifa"}],"regions":["Middle East"],"aliases":["Ohalo 2","Ohalo brush huts"],"related":["prehistoric-shelters-and-early-thatch","prehistory-of-roofing","natufian-round-houses","thatch"],"company":null,"sources":[{"title":"Ohalo II","url":"https://en.wikipedia.org/wiki/Ohalo_II","publisher":"Wikipedia"},{"title":"The oldest ever brush hut plant remains from Ohalo II, Jordan Valley, Israel (19,000 BP)","url":"https://cris.haifa.ac.il/en/publications/the-oldest-ever-brush-hut-plant-remains-from-ohalo-ii-jordan-vall/","publisher":"University of Haifa"}],"country":null},{"slug":"oil-canning","title":"Oil Canning","category":"problems-maintenance","type":"term","summary":"Oil canning is visible waviness in the flat areas of metal panels caused by locked-in stress or restrained movement; it is generally cosmetic.","body":"Oil canning, also called stress wrinkling or elastic buckling, is the rippled or wavy look that can appear in the flat parts of metal roof and wall panels. It occurs in steel, aluminium, copper and zinc. It is most noticeable on wide flat pans, thinner metal, glossy or dark finishes, and when low-angle sunlight strikes the roof. The waves may appear and fade through the day as the panels heat and cool.\n\n## Causes\n\nThe Metal Construction Association and panel manufacturers in North America and Australia list similar causes:\n\n- **Coil stresses**: uneven strain left from steel rolling, such as a longer centre (\"full centre\"), wavy edges or camber.\n- **Slitting and roll-forming**: cutting coil to width and forming edges can redistribute or trap stresses in the flat.\n- **Supports**: decks or purlins that are out of plane, structural movement, or cambered framing.\n- **Installation**: over-engaged seams, over-driven or angled fasteners, clips that are too tight or loose, and misaligned panels.\n- **Restrained thermal movement**: panels pinned at both ends, or bound by trims and flashings, buckle when they expand.\n- **Handling and storage**: twisting panels or carrying them flat.\n\n## Reducing it\n\n- Use thicker metal or tension-levelled coil.\n- Choose narrower panels, profiles with stiffening ribs or striations, or formed shingle, shake and tile profiles, which have little flat area.\n- Specify low-gloss, textured or embossed finishes and lighter colours.\n- Install on a flat, in-plane substrate, use clips that allow movement and avoid overtightening.\n- Handle and store panels carefully so they are not twisted or distorted.\n\n## Is it a defect?\n\nIndustry guidance treats oil canning as an aesthetic condition that normally does not affect structural performance or weathertightness. Unless the contract sets specific flatness criteria, it is generally not accepted as sole grounds for rejecting panels, and paint or panel warranties usually exclude it. Severe distortion can, however, point to structural movement or distressed connections and should be investigated.","key_facts":[{"label":"Also called","value":"Stress wrinkling, elastic buckling"},{"label":"Structural effect","value":"Generally none (aesthetic)"},{"label":"Main mitigations","value":"Thicker metal, narrower pans, ribs, low gloss, free movement"}],"regions":["Global"],"aliases":["oil-canning","stress wrinkling","elastic buckling","panel waviness"],"related":["standing-seam-metal-roof","tension-leveling","thermal-movement-in-metal-roofs","standing-seam-clips","sheet-metal-gauge","metal-roofing","fastener-back-out","portable-roll-former"],"company":null,"sources":[{"title":"Oil Canning (MCA technical sheet)","url":"https://www.mcelroymetal.com/hubfs/assets/OilCanningTechSheetfromMCA.pdf","publisher":"Metal Construction Association"},{"title":"Product Advisory Bulletin PAB05: Oil Canning","url":"https://cdn.dcs.lysaght.com/download/lysaght-product-advisory-bulletin-pab05-oil-canning","publisher":"Lysaght (BlueScope)"},{"title":"What Is Oil Canning? Metal Roof Waviness Explained","url":"https://www.interlockroofing.com/glossary/oil-canning/","publisher":"Interlock Roofing"},{"title":"Thermal Expansion & Oil Canning in Aluminum Roofs Explained","url":"https://www.interlockroofing.com/kb/aluminum-roof-thermal-expansion-oil-canning/","publisher":"Interlock Roofing"},{"title":"Tech Today: Oil canning","url":"https://www.professionalroofing.net/articles/article/3700","publisher":"Professional Roofing"},{"title":"What is oil canning of a metal roof","url":"https://blog.mcelroymetal.com/metal-roofing-contractors/what-is-oil-canning-of-a-metal-roof","publisher":"McElroy Metal"}],"country":null},{"slug":"old-town-of-ghadames","title":"Old Town of Ghadames","category":"world-roofing","type":"place","summary":"Libyan oasis town of mud-brick houses with palm-timber roofs, roofed streets, and rooftop terraces reserved for women; a World Heritage site since 1986.","body":"The old town of Ghadames is an oasis settlement in western Libya whose roofs form a second, private town above the streets. Houses are built of mud brick with palm-trunk timber, and their open roof terraces were reserved for women, while the streets below are largely roofed over.\n\n## Construction\n\nWalls are mud brick on stone foundations, finished with lime. Palm trunks, other woodwork and masonry complete the structure, and building materials have traditionally been reused. Most houses have two storeys: the ground floor for stores, the upper floor for the family, and above that the open-air terrace.\n\n## Two levels of town\n\nGhadames is often described as having a vertical division of public life:\n\n- **Roof level**: open-air terraces reserved for women, giving them privacy, and also used by children. Compact roofs are enclosed by high parapets.\n- **Street level**: public spaces, mostly covered, served as meeting places for men and children. Alleys pass beneath the houses and form an almost underground network, lit and ventilated by regular openings in the roof called *tinawt* or *klava*.\n\nResidents who moved to new houses built outside the old town from the 1970s onward still return in summer, because the old town gives better protection from the heat.\n\n## History\n\nGhadames was occupied by the indigenous Phazanii from at least the late first millennium BC and has served trans-Saharan trade for at least 2,000 years. It had an estimated population of about 10,000 in 2011, but the old town itself was depopulated during the 1990s.\n\n## Heritage and threats\n\nThe old town was inscribed on the World Heritage List in 1986 and placed on the List of World Heritage in Danger in 2016, with Libya's other World Heritage sites. It is protected by Law No. 3/1994. UNESCO lists changes in water supply, humidity, temperature and population, as well as heavy rains and fire, as threats. Its management plan includes the safeguarding of traditional construction techniques.","key_facts":[{"label":"Country","value":"Libya"},{"label":"Materials","value":"Mud brick on stone foundations, palm trunks, lime"},{"label":"Roof use","value":"Terraces reserved for women"},{"label":"World Heritage","value":"Inscribed 1986; in Danger since 2016"}],"regions":["Africa","Middle East"],"aliases":["Ghadamès","Ghadames roofs"],"related":["roofing-in-libya","roofing-in-north-africa","flat-roof","mud-roof","kershef"],"company":null,"sources":[{"title":"Old Town of Ghadamès","url":"https://whc.unesco.org/en/list/362/","publisher":"UNESCO World Heritage Centre"},{"title":"Ghadames","url":"https://en.wikipedia.org/wiki/Ghadames","publisher":"Wikipedia"}],"country":null},{"slug":"onduline","title":"Onduline","category":"manufacturers","type":"company","summary":"Onduline is a French roofing manufacturer founded about 80 years ago, known for lightweight corrugated roofing sheets and present in more than 100 countries.","body":"Onduline is a roofing and waterproofing manufacturer founded in France. The company marked its 80th anniversary in 2024, placing its origins in the mid-1940s, and is headquartered at Suresnes, on the western edge of Paris. Onduline Group states that it is present in more than 100 countries and operates around 30 national websites.\n\n## Products\n\nThe company's best-known product is its range of lightweight corrugated roofing sheets sold under the ONDULINE brand. The company states that its sheets contain between 45 and 51 percent recycled material. Its range also includes:\n\n- **ONDUVILLA**: roofing tiles in panel form, imitating traditional tiles.\n- **BARDOLINE**: asphalt (bitumen) shingles.\n- **BITULINE**: waterproofing membranes.\n- **ONDUCLAIR**: translucent and opaque plastic sheets, in polyester and polycarbonate, used for rooflights and canopies.\n- **ISOLINE**: under-roofing sheets laid beneath tiles.\n- **FONDALINE**: a product for below-ground and foundation protection.\n\n## Manufacturing\n\nThe company's production is international. In November 2024 it opened a new plant at Pasuruan in East Java, Indonesia.\n\n## Use\n\nCorrugated roofing sheets of this lightweight type are installed with nails or screws and caps through the crowns of the corrugations, with overlaps at sides and ends to shed water. Manufacturers specify minimum roof pitches, purlin spacings and fixing patterns for each product, and these differ from the requirements for metal or fibre-cement sheets.\n\n## Ownership\n\nThe company's own website does not identify its owner.\n\n## Translucent sheets\n\nPolycarbonate and polyester sheets such as those in the ONDUCLAIR range are used to bring daylight into canopies, carports, greenhouses and farm buildings, often combined with opaque sheets of matching profile.","key_facts":[{"label":"Origin","value":"France, mid-1940s (80th anniversary 2024)"},{"label":"Headquarters","value":"Suresnes, France"},{"label":"Presence","value":"100+ countries"},{"label":"Recycled content","value":"45-51% in roofing sheets"}],"regions":["Europe","Southeast Asia","Global"],"aliases":["Onduline Group","ONDULINE SAS"],"related":["asphalt-shingle"],"company":{"headquarters":"Suresnes, France","website":"https://www.onduline.com","known_for":["Lightweight corrugated roofing sheets","ONDUVILLA roof tiles","ONDUCLAIR plastic sheets"]},"sources":[{"title":"Onduline","url":"https://www.onduline.com/","publisher":"Onduline"},{"title":"Onduline (English)","url":"https://www.onduline.com/en","publisher":"Onduline"}],"country":null},{"slug":"onion-dome","title":"Onion Dome","type":"article","summary":"Bulb-shaped dome tapering to a point, typical of Russian Orthodox churches and also common on churches in Bavaria and Austria.","body":"An onion dome is a dome whose profile swells out beyond the diameter of its supporting drum and then tapers to a point, like an onion bulb. It is the defining roof form of Russian Orthodox church architecture and is also widespread on Baroque churches in Bavaria, Austria and neighbouring regions.\n\n## Origins\n\nThe origin of the shape is debated. Some historians trace it to Syria and the Islamic world, with early prototypes in 11th-century Iran, and suggest Russian builders may have adopted it through contact with Muslim states such as the Khanate of Kazan. Onion domes appear on Russian buildings as early as the 13th century and were most popular in the 17th and 18th centuries. The domes of St Basil's Cathedral in Moscow, built to commemorate the conquest of Kazan in 1552, have remained unchanged since the reign of Fyodor I (1584-1598).\n\n## Construction and coverings\n\nThe onion dome is usually not a structural masonry dome but a light outer shell. In Russia, each drum is topped by a metal or timber framework clad in sheet iron or tiles. In central Europe the domes are typically clad in copper sheet, which weathers to green.\n\nWooden churches in northern Russia used timber shingles. The Church of the Transfiguration at Kizhi Pogost on Lake Onega, begun in 1714 and about 37 m (121 ft) tall, carries 22 domes covered in aspen shingles, using roughly 60,000 shingles held by about 180,000 nails. Kizhi Pogost is a UNESCO World Heritage site.\n\n## Snow and weather\n\nIt is sometimes said that the onion shape sheds snow better than a hemispherical dome in severe winters. Some scholars accept this as a practical advantage; others, such as Prince Evgenii Trubetskoy, argued the shape is primarily symbolic and aesthetic.\n\n## In central Europe\n\nThe first Baroque onion dome in the Holy Roman Empire is recorded in Augsburg in 1576. Onion domes now crown many village churches across Bavaria, Austria and the Alps, usually as copper-clad timber structures on church towers.\n\n## Maintenance\n\nCopper and sheet-iron domes need periodic re-cladding and gilding, while shingled domes need replacement of weathered shingles. Restoration of Kizhi from 1999 onward involved dismantling, recording and reassembling the church and replacing elements that had decayed.","key_facts":[{"label":"Shape","value":"Bulb wider than drum, tapering to a point"},{"label":"Main regions","value":"Russia, Bavaria, Austria"},{"label":"Typical coverings","value":"Sheet iron, copper, gilding, wooden shingles"},{"label":"Notable example","value":"Kizhi Transfiguration Church, 22 domes"}],"regions":["Europe","South Asia","Middle East"],"aliases":["Bulbous dome","Lukovitsa","Zwiebelturm","bulbous dome","onion cupola"],"related":["roofing-in-russia","dome","copper-roofing","wood-shingle","wooden-churches-of-southern-malopolska","conical-roof","pagoda-roof"],"sources":[{"title":"Onion dome","url":"https://en.wikipedia.org/wiki/Onion_dome","publisher":"Wikipedia"},{"title":"Kizhi Pogost","url":"https://en.wikipedia.org/wiki/Kizhi_Pogost","publisher":"Wikipedia"},{"title":"Kizhi Pogost","url":"https://whc.unesco.org/en/list/544","publisher":"UNESCO World Heritage Centre"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"onorm-b-3419","title":"ÖNORM B 3419","category":"standards-codes","type":"standard","summary":"Austrian standard for the design and construction of roof and wall coverings, setting permitted pitches, substrates and wind-load fastening.","body":"**ÖNORM B 3419**, *Design and construction of roofings and wall coverings* (*Planung und Ausführung von Dacheindeckungen und Wandbekleidungen*), is the Austrian national standard for pitched roof coverings and similar wall claddings. It is published by Austrian Standards International; as of 2026 the current edition is dated 1 April 2018, replacing earlier editions including those of 2011 and December 2017.\n\n## Scope\n\nThe standard sets out rules for planning and building roof and wall coverings. It covers:\n\n- **permitted roof pitches** for each type of covering material;\n- **suitable substrates**, such as battens and boarding;\n- **wind-load fastening**, including how to calculate the fixings needed against wind suction;\n- a **simplified wind-load method** for single-shell and double-shell roofs with dense or porous (air-permeable) coverings.\n\nIt does not cover non-ventilated coverings, metal roofing, or curtain walling governed by ÖNORM EN 13830. Procedural and contractual matters, such as measurement and billing, are covered by the separate work-contract standard ÖNORM B 2219.\n\n## Place in Austrian regulation\n\nBuilding law in Austria belongs to the nine federal states, each with its own building code. Since 2008 their technical requirements have been harmonised through the OIB guidelines (*OIB-Richtlinien*) 1 to 6, which the states have declared binding in their building technology regulations. Standards such as ÖNORM B 3419 sit alongside these guidelines as the detailed technical rules for a particular trade, and European EN product standards apply to the roofing materials themselves.\n\n## Comparable documents\n\nNeighbouring countries handle the same subject in different ways. In Germany, roof-covering rules are set by the technical rules of the roofers' federation ZVDH; in France, by the NF DTU 40 series; and in the United Kingdom, by the code of practice BS 5534, which likewise combines minimum pitch, lap and wind-uplift fixing requirements.\n\n## Sources and gaps\n\nSpecific minimum pitch values set by the standard were not found in published summaries; the standard itself is the authority for them.","key_facts":[{"label":"Country","value":"Austria"},{"label":"Publisher","value":"Austrian Standards International"},{"label":"Current edition (as of 2026)","value":"1 April 2018"},{"label":"Covers","value":"Roof pitches, substrates, wind-load fastening"},{"label":"Excludes","value":"Metal roofing, non-ventilated coverings"}],"regions":["Europe"],"aliases":["ÖNORM B3419","OENORM B 3419","Austrian roofing standard"],"related":["roofing-in-austria","zvdh-fachregeln","dtu-40-series","bs-5534","en-1991-1-4"],"company":null,"sources":[{"title":"ÖNORM B 3419:2018-04-01","url":"https://www.austrian-standards.at/en/shop/onorm-b-3419-2018-04-01~p2371153","publisher":"Austrian Standards International"},{"title":"ÖNORM B 3419:2017-12-15","url":"https://www.austrian-standards.at/en/shop/onorm-b-3419-2017-12-15~p2105360","publisher":"Austrian Standards International"},{"title":"Baurecht und Bauordnungen","url":"https://www.oesterreich.gv.at/de/themen/bauen_und_wohnen/bauen/Seite.2260200","publisher":"oesterreich.gv.at"}],"country":null},{"slug":"organic-mat-shingle","title":"Organic-Mat Shingle","type":"term","summary":"An older type of asphalt shingle built on a felt mat of paper, rag or wood fibre, largely discontinued in North America by 2011.","body":"An organic-mat shingle is an asphalt shingle whose core is a felt made from cellulose fibres such as recycled paper, rag or wood pulp. It was the standard form of asphalt shingle for most of the 20th century before glass-fibre mats took over.\n\n## Construction\n\nOrganic shingles were built in more steps than modern glass-mat products. The felt was first saturated with a soft asphalt, then coated on both sides with a harder, stabilised coating asphalt, surfaced with mineral granules on top, and backed with sand, talc, slag or limestone dust. Organic shingles contain about 40% more asphalt per unit area than fibreglass shingles, which made them heavier and somewhat more flexible.\n\n## Performance\n\n- **Cold weather**: organic shingles were less brittle in low temperatures, which made them popular in northern climates and in Canada.\n- **Tear strength**: most organic shingles exceeded 2,000 g on the Elmendorf tear test, above the 1,700 g minimum set for glass-mat shingles in ASTM D3462.\n- **Fire**: the absorbent felt limited the best available fire rating to Class B, compared with Class A for glass-mat products.\n- **Moisture**: the felt could absorb water if the coating was damaged, leading to curling, blistering and \"fishmouthing\".\n\nBefore the early 1980s, some organic felts contained asbestos fibres, which matters when old roofs are removed.\n\n## Decline\n\nGlass-mat shingles were introduced in 1960 and overtook organic shingles in the United States by about 1982. Most manufacturers stopped making organic shingles in the mid-to-late 2000s, and the last North American maker, Building Products of Canada, ended production in 2011.\n\n## Today\n\nOrganic shingles are no longer sold new in North America, but many remain on older roofs. Inspectors identify them by their thickness, flexibility and a fibrous, paper-like core at a cut edge.\n","key_facts":[{"label":"Mat","value":"Cellulose felt (paper, rag, wood fibre)"},{"label":"Best fire rating","value":"Class B"},{"label":"Overtaken by glass-mat","value":"About 1982 (US)"},{"label":"Production ended","value":"2011 (last North American maker)"}],"regions":["North America"],"aliases":["organic shingle","felt-mat shingle","organic asphalt shingle"],"related":["asphalt-shingle","fiberglass-shingle","asbestos-cement-roofing","roofing-felt"],"sources":[{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Q&A: Fiberglass vs. Organic Shingles","url":"https://www.jlconline.com/how-to/interiors/q-a-fiberglass-vs-organic-shingles_o/","publisher":"Journal of Light Construction"}],"category":"materials","company":null,"country":null},{"regions":["Europe"],"company":null,"slug":"ottoman-domes-in-the-balkans","title":"Ottoman Domes in the Balkans","category":"history","type":"article","summary":"Domed mosques built under Ottoman rule across the Balkans, usually brick domes covered with tiles at first and with lead sheet by the 16th century.","aliases":["Ottoman lead domes","Balkan mosque domes"],"body":"Ottoman rule brought the domed mosque to the Balkans. Ottoman builders favoured simple hemispherical domes, often grouped with semi-domes and smaller domes, and by the 16th century covered them with lead. Mosques of this type shape the skylines of historic towns such as Sarajevo and Skopje.\n\n## Construction\n\n- **Structure:** domes were usually built of brick, which is light, using timber centring during construction; this continued even after stone replaced brick for walls.\n- **Form:** Ottoman architects consistently used simple hemispherical domes, usually single-shelled; Mimar Sinan, chief court architect from 1538 to 1588, used double shells on some mausoleums. Central domes were often surrounded by semi-domes and smaller corner domes.\n- **Covering:** early Ottoman domes were usually covered with terracotta tiles, but by the 16th century domes were generally covered with lead sheet. Byzantine builders before them had likewise covered domes with lead or regional tiles.\n\n## Balkan examples\n\n- **Mustafa Pasha Mosque, Skopje (1492):** a square prayer hall under a single dome about 16 m (52 ft) in diameter.\n- **Gazi Husrev-beg Mosque, Sarajevo (1530-1531):** an early classical Ottoman mosque with nine domes. The main dome, on pendentives, is 13 m (43 ft) in outer diameter and 26 m (85 ft) high, with a semi-dome over the qibla side, lower domes over the side spaces and small domes over the portico. It was badly damaged during the Siege of Sarajevo and reconstructed from 1996.\n- **Ferhadija Mosque, Banja Luka (1579):** destroyed in 1993.\n- **Selimiye Mosque, Edirne (1568-1574):** in European Turkey, a mosque dominated by a single huge dome roughly equal in diameter to the main dome of Hagia Sophia.\n\n## Maintenance\n\nLead can be shaped over curved surfaces and joined watertight, which suits domes, but its value has long made it a target for theft. War damage in Sarajevo also made dome repair part of post-war reconstruction, as at the Gazi Husrev-beg Mosque from 1996.","key_facts":[{"label":"Dome structure","value":"Usually brick, hemispherical"},{"label":"Covering","value":"Tiles early; generally lead by the 16th century"},{"label":"Examples","value":"Skopje (1492), Sarajevo (1530-1531), Banja Luka (1579)"}],"related":["dome","hagia-sophia-dome","medieval-lead-roofs","lead-roofing","middle-eastern-domes","roofing-in-bosnia-and-herzegovina","roofing-in-north-macedonia","roofing-in-turkey"],"sources":[{"title":"Ottoman architecture","url":"https://en.wikipedia.org/wiki/Ottoman_architecture","publisher":"Wikipedia"},{"title":"Gazi Husrev-beg Mosque","url":"https://en.wikipedia.org/wiki/Gazi_Husrev-beg_Mosque","publisher":"Wikipedia"},{"title":"Architecture of North Macedonia","url":"https://en.wikipedia.org/wiki/Architecture_of_North_Macedonia","publisher":"Wikipedia"},{"title":"Architecture of Bosnia and Herzegovina","url":"https://en.wikipedia.org/wiki/Architecture_of_Bosnia_and_Herzegovina","publisher":"Wikipedia"},{"title":"Byzantine architecture","url":"https://en.wikipedia.org/wiki/Byzantine_architecture","publisher":"Wikipedia"},{"title":"Ferhat Pasha Mosque (Banja Luka)","url":"https://en.wikipedia.org/wiki/Ferhat_Pasha_Mosque_(Banja_Luka)","publisher":"Wikipedia"}],"country":null},{"slug":"overflow-drainage","title":"Overflow (Secondary) Roof Drainage","category":"low-slope-systems","type":"term","summary":"Emergency drains or scuppers set above the primary drains so that water can leave a low-slope roof if the main outlets are blocked.","body":"Overflow drainage, also called secondary or emergency drainage, provides a second path for water to leave a roof when the primary drains are blocked or overwhelmed. Without it, water on a parapeted roof can rise until it overloads the structure or overtops flashings.\n\n## Forms\n\n- **Overflow scuppers** through the parapet, with their inlet set above the roof surface.\n- **Overflow drains** beside the primary drains, with a raised dam or standpipe so they only take water once it reaches a set depth, piped separately from the primary system.\n- **Lowered parapet sections or edge openings** on some roofs.\n\n## Code basis\n\nIn North America, the building and plumbing codes require secondary drainage on roofs where parapets or other construction would otherwise trap water. Structural design for rain loads assumes the primary drains are blocked and accounts for the depth of water needed to reach and flow through the secondary system; for roofs with slopes below 1/4 in per 12 in, the IBC requires a ponding-instability analysis using that blocked-drain assumption.\n\nIn the UK, BS 6229:2025 requires emergency overflows on roofs with only one outlet and on all blue roofs, sized to match the full capacity of a blocked outlet, and recommends additional overflow routes for internally drained roofs where possible.\n\n## Design points\n\n- overflow inlets must sit below the top of flashings and upstands\n- discharge should be visible, so that flow from an overflow alerts the owner to a blocked primary drain\n- pipes from overflow drains should discharge separately from primary pipes\n- overflows must be kept clear in maintenance\n\n## Relationship to blue roofs\n\nBlue roofs deliberately hold water using flow-restricting outlets, so overflows are a key safety feature in their design.","key_facts":[{"label":"Purpose","value":"Second drainage path if primary drains block"},{"label":"UK requirement (BS 6229:2025)","value":"Single-outlet roofs and all blue roofs"},{"label":"US structural basis","value":"Rain load assumes primary drains blocked"}],"regions":["Global","North America","Europe"],"aliases":["secondary drainage","emergency overflow","overflow drain","overflow scupper"],"related":["roof-drain","scupper","blue-roof","ponding-water","parapet"],"company":null,"sources":[{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"},{"title":"Tech Today: roof slope and positive drainage (M. Graham, March 2005)","url":"https://professionalroofing.net/articles/article/615","publisher":"Professional Roofing / NRCA"},{"title":"Blue roof","url":"https://www.designingbuildings.co.uk/wiki/Blue_roof","publisher":"Designing Buildings Wiki"}],"country":null},{"slug":"owens-corning","title":"Owens Corning","category":"manufacturers","type":"company","summary":"Owens Corning is a Toledo, Ohio-based maker of roofing, insulation and glass-fibre composites, formed in 1938 by Owens-Illinois and Corning Glass Works.","body":"Owens Corning is a publicly listed US building-materials company headquartered in Toledo, Ohio. It began in 1935 as a joint venture between the glassmakers Owens-Illinois and Corning Glass Works to develop glass fibre, and became a separate company in 1938. Its business lines include roofing and asphalt, insulation, and glass-fibre composites.\n\n## History\n\nThe company went public on the New York Stock Exchange in 1952 and has appeared on the Fortune 500 since the list began in 1955. Its move into roofing was linked to its glass-fibre know-how: after acquiring Frye Roofing in 1977, it began producing glass-fibre mats to replace the paper (organic felt) mats then common in roofing. Glass-fibre mat later became the standard reinforcement for asphalt shingles in North America.\n\nAsbestos-related claims led Owens Corning to file for Chapter 11 bankruptcy protection in 2000. Its shares were removed from the NYSE in 2002, and the company re-listed in 2006 under the ticker OC. In 2007 it formed a reinforcements joint venture with Saint-Gobain. In May 2024 it completed the purchase of Masonite International, a door manufacturer, for about USD 3.9 billion, broadening its residential building-products range.\n\n## Roofing products\n\nOwens Corning's roofing business makes asphalt shingles for steep-slope homes along with underlayments, ventilation, ridge caps and other components marketed as a roofing system. It also supplies asphalt used in roofing. In 2009 it started a programme to recycle torn-off asphalt shingles, for example into paving material.\n\n## Brand\n\nThe company is widely recognised in North America for using the Pink Panther character in its marketing, an arrangement dating from around 1980.","key_facts":[{"label":"Founded","value":"1938 (joint venture formed 1935)"},{"label":"Headquarters","value":"Toledo, Ohio, US"},{"label":"Listing","value":"NYSE: OC"},{"label":"Roofing products","value":"Asphalt shingles, underlayment, ventilation"}],"regions":["North America","Global"],"aliases":["Owens-Corning","OC"],"related":["asphalt-shingle","roofing-underlayment","roof-ventilation","certainteed","gaf"],"company":{"founded":"1938","headquarters":"Toledo, Ohio, United States","website":"https://www.owenscorning.com","known_for":["Asphalt shingles","Glass-fibre insulation","Glass-fibre composites"]},"sources":[{"title":"Owens Corning","url":"https://en.wikipedia.org/wiki/Owens_Corning","publisher":"Wikipedia"},{"title":"Owens Corning: A Toledo mainstay for 75 years","url":"https://www.toledoblade.com/business/2013/10/27/As-OC-turns-75-impact-can-be-seen-everywhere.print","publisher":"The Blade"}],"country":null},{"slug":"pagoda-roof","title":"Pagoda Roof","category":"roof-forms","type":"article","summary":"A pagoda roof is the stacked series of projecting eaves on a tiered tower, typically an odd number of tiers, found across East, Southeast and South Asia.","body":"A pagoda is a tiered tower with multiple eaves, developed from the stupa, a domed Buddhist monument that originated in ancient India. The \"pagoda roof\" refers to its characteristic sequence of projecting roofs, one at each storey, which diminish in size toward the top and are crowned by a finial. Most pagodas have between three and thirteen tiers, almost always an odd number; the 18th-century pagoda at Kew Gardens in London is a notable exception.\n\n## Regional traditions\n\n- **China:** pagodas were built in timber, brick and stone, with overhanging eaves on each tier. The wooden pagoda of Fogong Temple in Ying County, Shanxi, built in 1056, is the oldest standing fully wooden pagoda in China.\n- **Japan:** wooden pagodas, typically three- or five-storeyed, are a feature of Buddhist temples. The pagoda at Hōryū-ji, built in the 7th century, is among the oldest wooden buildings in the world.\n- **Korea:** stone and wooden pagodas, such as the octagonal nine-storey pagoda at Woljeongsa.\n- **Nepal:** multi-tiered temples of the Kathmandu Valley derive from Newar architecture, which differs from Chinese and Japanese styles.\n\n## Structure and roofing\n\nTimber pagodas carry their deep eaves on dougong, wooden bracket sets that lock together, and many have a central column. The complex joints provide friction damping and sliding, which help these tall timber structures survive earthquakes. Wooden pagodas are, however, vulnerable to fire, rot and insects, which is why most surviving ancient pagodas are brick or stone.\n\nThe roofs themselves are covered with fired clay tiles, wooden shingles, bark or copper sheet, with ornamental ridge and eave-end tiles. Upturned eave corners are a common decorative feature in Chinese-influenced styles.\n\n## Influence\n\nPagoda forms influenced 18th-century European chinoiserie garden buildings and, later, modern buildings that borrow tiered eaves for shading and visual effect.","key_facts":[{"label":"Origin","value":"Stupa, ancient India"},{"label":"Typical tiers","value":"3 to 13, usually odd"},{"label":"Oldest all-wood (China)","value":"Fogong Temple pagoda, 1056"},{"label":"Hōryū-ji pagoda","value":"7th century"}],"regions":["East Asia","South Asia","Southeast Asia"],"aliases":["tiered roof","pagoda","multi-eaved roof"],"related":["irimoya","dome","conical-roof"],"company":null,"sources":[{"title":"Pagoda","url":"https://en.wikipedia.org/wiki/Pagoda","publisher":"Wikipedia"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"}],"country":null},{"category":"world-roofing","type":"article","company":null,"slug":"palapa","title":"Palapa","summary":"Open-sided shelter or house roofed with dried palm leaves, common in coastal and rural Mexico and Central America and on beaches and resorts.","body":"A palapa is an open-sided structure roofed with thatch of dried palm leaves. In Mexico the word covers both simple beach shelters and the palm-thatched roofs of rural houses, restaurants and resort buildings. Similar structures in Nicaragua are called *ranchos*.\n\n## Name and origin\n\nThe word is Spanish. One account traces it to Tagalog, where it originally meant the stalk of a palm leaf, and links the palapa to the Philippine *bahay kubo* (nipa hut), building methods that may have reached New Spain with the Manila galleons alongside the coconut palm. Dictionaries such as the American Heritage Dictionary instead describe the word as American Spanish. Related palm-roofed houses include the Taíno *bohío* of the Greater Antilles and the *chickee* of the Seminole in Florida.\n\n## Use\n\nPalapas are valued in hot climates because the thick, ventilated palm roof gives deep shade while letting hot air escape. They are very common on Mexican beaches and in Central America. In Mexico palm-leaf thatch remains a locally available, low-cost roof for rural houses, especially in the south and on the coasts, and is widely used on tourist buildings. In Yucatán, the oval Maya house (*xa'anil naj*) has a steep thatched roof over a rounded plan, a shape associated with withstanding hurricane winds.\n\n## Census\n\nMexico's 2020 census no longer reports palm roofs separately: palm or straw roofs are grouped with cardboard sheet, earth roofs and other materials in an \"other\" category that together covered 1.8% of occupied dwellings.\n\n## Construction and maintenance\n\nAs with other palm thatch, the roof is a frame of poles or timber covered with layers of dried leaves, which decay and must be renewed over time.\n## Sources and gaps\n\nDetailed figures on lifespan and pitch were not found in published sources (see palm-thatch and thatching-process).","key_facts":[{"label":"Covering","value":"Dried palm leaves"},{"label":"Region","value":"Mexico, Central America"},{"label":"Related types","value":"Bohío, chickee, bahay kubo"},{"label":"Census share (Mexico 2020)","value":"In 'other' roof materials, 1.8% combined"}],"regions":["Latin America","North America"],"aliases":["Palapa roof","Rancho (Nicaragua)","Palm-thatched hut"],"related":["palm-thatch","thatch","thatching-process","bohio","roofing-in-mexico","roofing-in-the-caribbean"],"sources":[{"title":"Palapa (structure)","url":"https://en.wikipedia.org/wiki/Palapa_(structure)","publisher":"Wikipedia"},{"title":"Architecture of Mexico","url":"https://en.wikipedia.org/wiki/Architecture_of_Mexico","publisher":"Wikipedia"},{"title":"Censo de Población y Vivienda 2020: Resultados complementarios","url":"https://inegi.org.mx/contenidos/programas/ccpv/2020/doc/Censo2020_Resultados_complementarios_EUM.pdf","publisher":"INEGI"}],"country":null},{"slug":"palauan-bai","title":"Palauan Bai","category":"world-roofing","type":"article","summary":"Palau’s traditional men’s meeting house, with a tall decorated gable and steep thatched roof, built without nails on a stone platform.","body":"The *bai* is the traditional men's meeting house of Palau. Larger and grander than ordinary houses, it served community functions as the civic and spiritual centre of a village. Its steep roof and tall front gable, painted with scenes from Palauan legends, make it one of the most distinctive roof forms in Micronesia.\n\n## Form and materials\n\nPalauan houses were elongated A-frame structures, and bai followed a similar shape at a larger scale. Oral history collected by the Pacific Worlds project records that bai were built without nails, tied together with rope made from coconut husk fibre. The traditional thatch was pandanus (*búuk*); thatch of nipa palm (*tóechel*) came into use later, and palm fronds (*melóuch*) changed roofing again. Bai stand on raised stone platforms, often at the meeting point of stone pathways.\n\n## Airai Bai\n\nThe Airai Bai (Bai ra Irrai) on Babeldaob is the best-known surviving example and has been described as the last traditional building of its kind in Palau. Built around 1890 on a platform that had carried earlier bai, it measures 20.7 by 6.1 m (68 by 20 ft) and reaches a peak height of about 12 m (40 ft). Its facade and interior beams are decorated with depictions of Palauan legends. It underwent a major restoration in the 1970s and was listed on the US National Register of Historic Places on 20 September 1976, when Palau was part of the US-administered Trust Territory.\n\n## The Berlin bai\n\nIn 1907 a bai was built for the Ethnological Museum in Berlin under the direction of doctor and ethnologist Augustin Krämer, and it was first shown to the public in 1908. Although built at reduced scale, it resembles other Palauan meeting houses. About sixty years later a floor and roof truss were added. The building is now displayed at the Humboldt Forum, and in summer 2022 a team from Palau led by Patrick Tellei gave it a new roof, an example of source communities maintaining traditional roofing skills on objects held abroad.\n\n## Today\n\nMost Palauan homes now have metal or concrete roofs: in the 2012 mini-census, 16.6% of housing units had concrete roofs and the rest metal, wood or other materials. Bai remain important symbols of Palauan identity and are maintained or rebuilt with community labour.\n\n## Related forms\n\nComparable Pacific meeting houses include the Yapese *faluw*, the Kiribati [maneaba](/maneaba), the Sepik [haus tambaran](/haus-tambaran) and the Māori [wharenui](/wharenui).","key_facts":[{"label":"Country","value":"Palau"},{"label":"Thatch","value":"Pandanus (búuk); later nipa palm (tóechel)"},{"label":"Fixing","value":"Coconut-husk fibre rope; no nails"},{"label":"Airai Bai","value":"C. 1890; 20.7 x 6.1 m, about 12 m high"},{"label":"Heritage listing","value":"US National Register of Historic Places, 1976 (Airai)"}],"regions":["Oceania"],"aliases":["Bai","Palauan meeting house","Airai Bai","Bai ra Irrai"],"related":["roofing-in-palau","roofing-in-micronesia","maneaba","haus-tambaran","wharenui","palm-thatch","thatch"],"company":null,"sources":[{"title":"Airai Bai","url":"https://en.wikipedia.org/wiki/Airai_Bai","publisher":"Wikipedia"},{"title":"Airai: Native Palau","url":"https://www.pacificworlds.com/palau/native/native2.cfm","publisher":"Pacific Worlds"},{"title":"More than a roof over one’s head","url":"https://humboldtforum.org/en/buildings-from-oceania","publisher":"Humboldt Forum"},{"title":"Palau 2012 Census, States, Housing","url":"https://www.pacificweb.org/palau-2012-censusstateshousing/","publisher":"PacificWeb"}],"country":null},{"regions":["Europe"],"company":null,"slug":"palloza","title":"Palloza","category":"world-roofing","type":"term","summary":"A palloza is a round or oval stone house with a conical rye-straw thatched roof, traditional in the Ancares mountains of north-west Spain.","aliases":["pallaza","pallouza","casa de teito","teito"],"body":"A **palloza** is a traditional dwelling of the Serra dos Ancares in north-west Spain, with low stone walls on a circular or oval plan and a conical thatched roof, usually of rye straw. Pallozas survive in the Ancares area of Galicia, in western Asturias (including the Fornela and Ibias valleys) and in the El Bierzo district of León.\n\n## Form and roof\n\nPallozas are typically 10-20 m (33-66 ft) across and were built to withstand severe winters at altitudes of around 1,200 m (3,900 ft). The thatched roof may end in a peak or have a short ridge. There is no chimney: smoke from the kitchen fire escapes through the thatch. Inside, the house was divided between the family and their animals, each with its own entrance, and contained a bread oven and workshops. Only the eldest couple had a bedroom; the rest of the family slept in the hayloft under the roof.\n\n## Origins\n\nThe round, thatched house type is prehistoric. Pallozas resemble the circular buildings of the pre-Roman Castro culture and other Atlantic Iron Age cultures, including round houses in Britain, but they are much larger and, unlike castro houses, also sheltered animals and stores.\n\n## Names\n\nThe word *palloza* comes from the Galician *pallaza*, referring to the straw roof, a term first recorded at the end of the 19th century and later used by ethnographers such as Fritz Krüger. Local names include *casa de teito* or *cabana de teitu*, from *teito*, \"thatch\". The Portuguese *palhoça* is a related word for a small thatched cabin.\n\n## Decline and protection\n\nPallozas were lived in until the second half of the 20th century, when new materials arrived and the houses came to be seen as symbols of poverty. Their ethnographic value was recognised towards the end of the century. In Piornedo (Lugo), a group of 14 pallozas is protected as a *Bien de Interés Cultural*, and one has been an ethnographic museum since the 1970s. Pallozas at Campo del Agua in El Bierzo were largely destroyed by fire in the 1980s; those at Cantejeira were restored with an original structure over 300 years old. New pallozas are now built mainly as holiday homes, sometimes outside their traditional area.","key_facts":[{"label":"Roof","value":"Conical rye-straw thatch"},{"label":"Diameter","value":"10-20 m (33-66 ft)"},{"label":"Region","value":"Ancares (Galicia, León, Asturias)"},{"label":"Protected group","value":"Piornedo, 14 pallozas (BIC)"}],"related":["roofing-in-spain","thatch","roofing-in-portugal","roofing-in-ireland"],"sources":[{"title":"Palloza","url":"https://en.wikipedia.org/wiki/Palloza","publisher":"Wikipedia"},{"title":"Palloza","url":"https://es.wikipedia.org/wiki/Palloza","publisher":"Wikipedia (Spanish)"}],"country":null},{"slug":"palm-thatch","title":"Palm and Grass Thatch","type":"term","summary":"Thatch made from palm fronds, leaves or tropical grasses, used for traditional and resort buildings across tropical Africa, Asia, the Pacific and the Americas.","body":"Palm and grass thatch covers a wide family of roofs made from the leaves of palms and from tropical and savanna grasses. They are the traditional roofing of many hot and humid regions and are still widely used for houses, shelters and resort buildings.\n\n## Materials and regional names\n\n- **Makuti** (East Africa): coconut palm fronds woven or folded around sticks and tied to the roof frame in overlapping rows.\n- **Nipa** (South-east Asia): leaves of the nipa palm, used on the traditional Filipino *bahay kubo*.\n- **Alang-alang** (South-east Asia, Pacific): a tall grass used for thatch in the region.\n- **Pili grass** (Hawaii): used with ti leaves and lauhala on traditional *hale* shelters.\n- **Savanna grasses** (sub-Saharan Africa): bundled grass thatch on round houses and granaries, for example in Ethiopia and southern Africa.\n\n## Characteristics\n\nLike all thatch, palm and grass roofs depend on a steep pitch so rain runs off the surface. They are light, can be built with local materials and labour, and insulate well against heat. The open weave of some palm thatch also allows hot air to escape, helping to ventilate the space below.\n\n## Durability\n\nPalm and grass thatch generally lasts less time than European water reed. Life depends greatly on climate, pitch, insects and fire. Roofs in humid tropical climates are vulnerable to rot and to termites and other insects, and need regular patching and periodic replacement.\n\n## Fire\n\nDry palm and grass are highly flammable. Fire-retardant treatments are available, and fire precautions similar to those for European thatch (keeping chimneys, flues and open flames away from the roof) apply.\n","key_facts":[{"label":"Examples","value":"Makuti (coconut palm), nipa, alang-alang, pili grass"},{"label":"Main regions","value":"Tropical Africa, Asia, Pacific, Latin America"},{"label":"Key risks","value":"Rot, insects, fire"}],"regions":["Africa","Southeast Asia","Oceania","South Asia"],"aliases":["makuti","nipa thatch","alang-alang","grass thatch","palm leaf roof"],"related":["thatch","bamboo-roofing","water-reed-thatch"],"sources":[{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Bamboo construction","url":"https://en.wikipedia.org/wiki/Bamboo_construction","publisher":"Wikipedia"},{"title":"Roof","url":"https://en.wikipedia.org/wiki/Roof","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"pamiri-house","title":"Pamiri House (Chid)","category":"world-roofing","type":"term","summary":"The Pamiri house, or chid, of Tajikistan's Badakhshan region has a flat earth roof on five pillars, lit by a stepped square skylight called the chorkhona.","body":"The **Pamiri house**, called *chid* in the Pamiri languages, is the traditional dwelling of the Pamiri peoples of the Badakhshan region in the Pamir mountains of eastern Tajikistan, a high mountain area along the border with Afghanistan. Seen from outside it is a modest flat-roofed box of stone and mud. Inside, its roof structure is the heart of the house: five carved pillars carry the beams, and the only daylight enters through a stepped timber skylight, the **chorkhona**, at the centre of the ceiling.\n\n## Roof structure\n\nThe chid has a single large main room. Five wooden pillars stand in it, and two main beams cross over them; these are followed by groups of smaller intermediary beams, usually thirteen, with the number adjusted to the size of the house. Over these lies the flat roof, which is also a working surface where families dry hay, apricots and mulberries, and dung cakes for fuel.\n\nWalls are usually of stone set in mud, finished with plaster. The pillars were traditionally of juniper, a tree held sacred in the region, but suitable junipers have become scarce and are no longer practical for new houses.\n\n## The chorkhona skylight\n\nThe *chorkhona*, meaning \"four houses\", is built up from four square timber frames, each set above the last, rising to an opening in the roof. It is the main source of light and air in the room, and the sun's first rays strike the top frame. In local interpretation the four squares stand for earth, water, air and fire, with fire at the top.\n\n## Symbolism\n\nAlmost every structural element carries meaning in the Ismaili tradition of the Pamiris. The five pillars are named after Muhammad, Ali, Fatima, Hassan and Hussein, and each marks a place for particular household activities, from the cradle to wedding blessings and mourning. The two main beams are said to represent universal reason (*akli kul*) and the universal soul (*nafsi kul*), and different counts of the beams are linked to Ismaili history. Raised platforms around the walls, about 50 cm (20 in) and 70 cm (28 in) high, divide the room into levels for different uses.\n\n## Local terms\n\n- *chid*: house\n- *chorkhona*: \"four houses\", the stepped skylight\n- *chalak*: earthen floor level\n- *loshnukh*: first raised platform, about 50 cm (20 in) high\n- *barnekh*: upper platform used for sleeping and eating, about 70 cm (28 in) high","key_facts":[{"label":"Region","value":"Badakhshan, Pamir mountains, Tajikistan"},{"label":"Roof","value":"Flat roof on timber beams and five pillars"},{"label":"Skylight","value":"Chorkhona, four stepped concentric squares"},{"label":"Walls","value":"Stone with mud or plaster"},{"label":"Roof use","value":"Drying hay, apricots, mulberries and dung fuel"}],"regions":["Central Asia"],"aliases":["chid","Pamiri chid","chorkhona","Pamir house"],"related":["flat-roof","mud-roof","skylight","roofing-in-tajikistan","roofing-in-afghanistan","dome"],"company":null,"sources":[{"title":"The Pamiri House","url":"https://pamirs.org/about/the-pamiri-house","publisher":"Pamirs.org"},{"title":"Chid: cosmogony of the Pamiri house","url":"https://ext.maat.pt/longforms/chid-cosmogony-pamiri-house","publisher":"MAAT - Museum of Art, Architecture and Technology"}],"country":null},{"slug":"pantheon-dome","title":"Pantheon Dome","category":"history","type":"place","summary":"The concrete dome of the Pantheon in Rome, completed around 126 CE, still the largest unreinforced concrete dome in the world at 43.3 m (142 ft).","body":"The **Pantheon** in Rome is the best-preserved major building of ancient Rome, and its dome is one of the most important roofs in history. Built of unreinforced concrete, it has stood for nearly 1,900 years and remains the largest dome of its kind.\n\n## Date\n\nThe present building was completed under Emperor **Hadrian** and probably dedicated around 126 CE. Sources give slightly different construction ranges: about 113-125 CE, with work possibly begun under Trajan, or 118-128 CE in Britannica. An earlier temple on the site was begun by Agrippa in 27 BCE; it was destroyed by fire, and the present rotunda and dome are a complete rebuilding.\n\n## The dome\n\n- Interior diameter: about 43.3 m (142 ft), equal to 150 Roman feet. The height from floor to the top of the dome is the same, so the interior would contain a perfect sphere.\n- The **oculus**, an open circle at the top, is about 9.1 m (30 ft) across and is the only source of daylight.\n- The shell is about 6.4 m (21 ft) thick at its base, thinning to about 1.2 m (3.9 ft) around the oculus.\n- The inner surface has five rings of 28 sunken **coffers**, which reduce weight.\n\n## How it stands\n\nRoman builders graded the concrete by height. The lowest, thickest part uses heavy travertine aggregate, the middle uses broken terracotta tile, and the top uses light tufa and pumice. The oculus removes weight where it would cause the most stress. Unlike most surviving ancient domes, the Pantheon needs no tie rods, chains or later reinforcement.\n\n## The roof covering\n\nThe dome's exterior was once covered with bronze tiles, described in some sources as gilded; it was not a copper roof. In July **663** the Byzantine emperor **Constans II** visited Rome, stripped the tiles and sent them to Constantinople. The roof stayed uncovered for nearly a century until **Pope Gregory III** (731-741) had it lined with lead sheets.\n\n## Survival\n\nThe building was consecrated as a church, St Mary and the Martyrs, on 13 May 609, and continuous use helped preserve it. It remained a reference for later dome builders; the oculus at the top of St Paul's Cathedral in London, for example, was inspired by it.","key_facts":[{"label":"Completed","value":"About 126 CE (Hadrian)"},{"label":"Dome diameter","value":"About 43.3 m (142 ft)"},{"label":"Oculus","value":"About 9.1 m (30 ft)"},{"label":"Bronze tiles removed","value":"663 by Constans II"},{"label":"Relined with lead","value":"Under Pope Gregory III (731-741)"}],"regions":["Europe"],"aliases":["Pantheon Rome dome","Roman Pantheon"],"related":["florence-cathedral-dome","st-pauls-cathedral-dome","hagia-sophia-dome","medieval-lead-roofs","dome"],"company":null,"sources":[{"title":"Pantheon, Rome","url":"https://en.wikipedia.org/wiki/Pantheon,_Rome","publisher":"Wikipedia"},{"title":"St Paul's Cathedral","url":"https://en.wikipedia.org/wiki/St_Paul%27s_Cathedral","publisher":"Wikipedia"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Pantheon (building, Rome, Italy)","url":"https://www.britannica.com/topic/Pantheon-building-Rome-Italy","publisher":"Encyclopaedia Britannica"}],"country":null},{"slug":"pantile","title":"Pantile","type":"term","summary":"A single-lap clay roof tile with an S-shaped profile that combines the functions of pan and cover in one piece.","body":"A pantile is a fired clay roof tile with an S-shaped cross-section. One side of the tile forms a hollow channel (the pan) and the other a rounded ridge (the cover) that overlaps the channel of the next tile. Combining the two parts in a single unit means fewer tiles, fewer joints and a lighter roof than two-piece curved tiling.\n\n## Laying\n\nPantiles are single-lap tiles: each course overlaps only the course immediately below it, whereas flat plain tiles usually lap two courses. As a result a pantile roof is much lighter than a plain-tiled one and can be laid at a lower pitch. Traditional pantiles were hung on battens by a nib on the back; modern versions are often also nailed or clipped. In older work the gaps under the tiles were sometimes \"torched\" with lime mortar from inside to reduce draughts and wind-blown snow.\n\n## History in Britain\n\nPantiles were first imported into eastern England and Scotland from the Netherlands in the early 17th century. They became characteristic of the east coast and are found in Norfolk, East Yorkshire, County Durham, Perthshire, Angus, Lothian and Fife. They are rare in western England and western Scotland, apart from around Bristol and Bridgwater in Somerset, where local tile-making industries developed.\n\n## Variants\n\n- **Scandia** tiles, used in Scandinavia, are a pantile variant with a subdued S-curve.\n- **Spanish S-tiles** are extruded tiles in the same family, with a deeper curve.\n- **Interlocking pantiles**, both clay and concrete, add side grooves for better weather resistance at lower pitches.\n\n## Not to be confused with\n\n\"The Pantiles\" in Royal Tunbridge Wells, England, is a paved walk named after square clay paving tiles shaped in a pan; it has nothing to do with roofing pantiles.\n","key_facts":[{"label":"Profile","value":"S-shaped, one-piece pan and cover"},{"label":"Lap","value":"Single lap"},{"label":"Introduced to Britain","value":"Early 17th century, from the Netherlands"}],"regions":["Europe"],"aliases":["pan tile","Dutch pantile","S-tile (UK usage)"],"related":["clay-roof-tile","spanish-tile","interlocking-clay-tile","plain-tile","concrete-roof-tile"],"sources":[{"title":"Pantile","url":"https://en.wikipedia.org/wiki/Pantile","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"parapet","title":"Parapet (Roof)","category":"low-slope-systems","type":"term","summary":"The part of an exterior wall that rises above the roof edge, providing fall protection, fire separation and a termination for the roof membrane.","body":"A parapet is a barrier that continues a wall upward at the edge of a roof, terrace or balcony. The word comes from the Italian parapetto, meaning \"chest guard\". Parapets originated as defensive walls but are now standard on many low-slope roofs.\n\n## Functions\n\n- **Fall protection:** acts as a guard at the roof edge.\n- **Fire:** fire walls often extend above the roof as parapets of equal fire resistance to limit fire spread, as required by building codes.\n- **Wind:** parapets modify wind flow over the roof, influencing uplift at corners and edges.\n- **Concealment:** hides rooftop equipment.\n- **Drainage:** contains water on the roof, which is why roofs with parapets need drains or scuppers and overflow drainage.\n\n## Roofing at parapets\n\nThe membrane turns up the inside face of the parapet as a base flashing. UK guidance generally calls for waterproofing to extend at least 150 mm (6 in) above the finished roof surface. Above that, a counterflashing, reglet or termination bar protects the top edge, or the membrane continues up and over the parapet under the coping. Cants or angle fillets are sometimes used at the junction with bituminous membranes.\n\n## Problems\n\nParapets are frequent sources of leaks: water can enter through cracked masonry, mortar joints, failed copings or unsealed laps and run down inside the wall to appear far from its entry point. Parapet walls are exposed on both faces and suffer freeze-thaw damage, so many designs include through-wall flashings, cavity trays and robust copings.\n\n## Related elements\n\nThe top of a parapet is protected by a coping. Overflow scuppers are often set through parapets.","key_facts":[{"label":"Etymology","value":"Italian parapetto, 'chest guard'"},{"label":"Typical UK upstand","value":"At least 150 mm (6 in) above finished roof"},{"label":"Key functions","value":"Fall protection, fire separation, wind, concealment"}],"regions":["Global"],"aliases":["parapet wall","roof parapet"],"related":["coping","scupper","overflow-drainage","flat-roof"],"company":null,"sources":[{"title":"Parapet","url":"https://en.wikipedia.org/wiki/Parapet","publisher":"Wikipedia"},{"title":"Top tips to help you get the most out of your flat roof","url":"https://www.sigroofing.co.uk/?p=12082","publisher":"SIG Roofing"},{"title":"BS 6229:2018 and flat roofing systems","url":"https://ikogroup.co.uk/?p=820","publisher":"IKO"}],"country":null},{"slug":"penrhyn-quarry","title":"Penrhyn Quarry","category":"history","type":"place","summary":"A slate quarry near Bethesda, Gwynedd, which at the end of the 19th century was the largest slate quarry in the world and is still worked.","body":"**Penrhyn Quarry** lies near Bethesda in Gwynedd, north-west Wales. For much of the 19th century it was the largest slate quarry in the world, and it remains the largest in Britain.\n\n## Origins\n\nSlate had been dug in the area since at least 1413. The modern quarry was developed in the 1770s by **Richard Pennant**, later Baron Penrhyn, who took direct control of slate working on his estate in 1782. By 1792 it employed about 500 men and produced about 15,000 tons of slate a year.\n\n## Scale\n\nBy the end of the 19th century nearly 3,000 quarrymen worked there. The main pit is nearly 1.6 km (1 mile) long and about 370 m (1,200 ft) deep, worked in a series of stepped terraces called galleries. Larger quarries have since been opened in China, Spain and the United States.\n\n## The Great Strike\n\nRelations between the Penrhyn family and the workforce were often bitter. A dispute that began on 22 November 1900 became a three-year strike or lock-out, often described as the longest dispute in British industrial history. Workers returned in November 1903 on terms set by Lord Penrhyn. Historians see the dispute as a turning point in the decline of Welsh slate.\n\n## Ownership since 1963\n\n- Alfred McAlpine owned the quarry from 1963 to 2007.\n- It was bought in 2007 by Kevin Lagan and renamed Welsh Slate Ltd.\n- Breedon Group acquired the Lagan Group in 2018.\n\nAbout 200 people work there today. Part of the disused site hosts a zip-line attraction.\n\n## Heritage\n\nPenrhyn forms part of the landscape recognised in 2021 as the Slate Landscape of Northwest Wales World Heritage Site. Its slates remain in demand for conservation work on historic roofs, where matching original material matters.","key_facts":[{"label":"Location","value":"Near Bethesda, Gwynedd, Wales"},{"label":"Developed","value":"1770s; expanded from 1782"},{"label":"Main pit","value":"About 1.6 km (1 mile) long, 370 m (1,200 ft) deep"},{"label":"Peak workforce","value":"Nearly 3,000 (late 19th century)"}],"regions":["Europe"],"aliases":["Penrhyn slate quarry","Bethesda quarry"],"related":["welsh-slate-industry","penrhyn-strike","dinorwic-quarry","slate-landscape-of-northwest-wales"],"company":null,"sources":[{"title":"Penrhyn Quarry","url":"https://en.wikipedia.org/wiki/Penrhyn_Quarry","publisher":"Wikipedia"},{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"}],"country":null},{"slug":"penrhyn-strike","title":"Penrhyn Strike (1900-1903)","category":"history","type":"event","summary":"A three-year strike and lock-out at Penrhyn slate quarry in Wales, often called the longest dispute in British industrial history.","body":"The **Penrhyn strike**, also known as the Great Strike of Penrhyn, was a dispute between the quarrymen of Penrhyn slate quarry near Bethesda, north-west Wales, and the quarry owner, Lord Penrhyn. It began on **22 November 1900** and lasted three years, ending in **November 1903**. It is often described as the longest dispute in British industrial history.\n\n## Background\n\nAt the end of the 19th century Penrhyn was the largest slate quarry in the world, employing nearly 3,000 men. Welsh slate output had peaked in 1898, but the industry was exposed to falling prices and competition. This is described as the second strike at the quarry, indicating earlier conflict between owner and workforce.\n\n## The dispute\n\nThe conflict is described in some sources as a strike and in others as a lock-out, reflecting disagreement over which side began it. Its three-year length meant prolonged loss of earnings for quarrying families in Bethesda and the surrounding area.\n\n## Outcome\n\nThe workers returned in November 1903 on terms set by Lord Penrhyn.\n\n## Effect on roofing\n\nThe dispute disrupted supply of Welsh roofing slate just as builders had growing alternatives, including clay tiles, imported slate and, soon after, cement-based and asphalt products. Historians see it as marking the beginning of the industry's long decline. After 1903 a wider depression brought pay cuts and job losses, and eight Ffestiniog quarries closed between 1908 and 1913.\n\n## Remembrance\n\nThe strike remains an important event in Welsh labour history and is interpreted as part of the Slate Landscape of Northwest Wales World Heritage Site.","key_facts":[{"label":"Began","value":"22 November 1900"},{"label":"Ended","value":"November 1903"},{"label":"Location","value":"Penrhyn Quarry, Bethesda, Wales"},{"label":"Workforce affected","value":"Nearly 3,000 quarrymen"}],"regions":["Europe"],"aliases":["Great Strike of Penrhyn","Penrhyn lock-out","Penrhyn dispute"],"related":["penrhyn-quarry","welsh-slate-industry","slate-landscape-of-northwest-wales"],"company":null,"sources":[{"title":"Penrhyn Quarry","url":"https://en.wikipedia.org/wiki/Penrhyn_Quarry","publisher":"Wikipedia"},{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"}],"country":null},{"slug":"petersen-pac-clad","title":"Petersen (PAC-CLAD)","category":"manufacturers","type":"company","summary":"Petersen is a US maker of architectural metal roofing and wall panels sold as PAC-CLAD, founded in Chicago in 1965 and owned by Carlisle since 2019.","body":"Petersen, long known as Petersen Aluminum, is a US manufacturer of architectural metal roofing, wall panels and coil sold under the PAC-CLAD brand. It was started in February 1965 by Maurice \"Maury\" Petersen, who rented a small Chicago office to act as a distributor for aluminium mills. Carlisle Companies acquired Petersen and the PAC-CLAD brand in 2019 as part of Carlisle Construction Materials.\n\n## History\n\n- **1965**: Maury Petersen founds the company in Chicago; he leads it until 1987.\n- **1972**: The business moves to Schiller Park, Illinois, to house its own aluminium anodising line.\n- **1987**: His son Mike Petersen becomes president and chief executive.\n- **1994**: A new headquarters opens in Elk Grove Village, Illinois.\n- **2019**: Carlisle acquires Petersen.\n- **2024**: Carlisle groups Petersen with four other companies under Carlisle Architectural Metals.\n\n## Manufacturing\n\nPetersen lists manufacturing locations in Elk Grove Village, Illinois; Baltimore, Maryland; Tyler, Texas; Acworth, Georgia; and Phoenix, Arizona, with distribution centres in Denver, Levittown (Pennsylvania), Manchester (New Hampshire) and Tampa.\n\n## Products\n\n- Standing seam and other metal roofing systems in steel and aluminium.\n- Metal wall panels and siding, including exposed-fastener, composite (aluminium composite material) and tile-style systems.\n- Insulated metal panels.\n- Soffit, fascia, coping, gutters and downspouts.\n- Perforated aluminium, column covers, coil and flat sheet for fabricators.\n- Snow retention (ColorGard) and roof and wall insulation.\n\nThe company also sells roll-forming machines, seamers and touch-up paint to contractors who fabricate panels themselves. Panels are produced in steel and aluminium in a range of painted finishes.","key_facts":[{"label":"Founded","value":"February 1965, Chicago"},{"label":"Founder","value":"Maurice Petersen"},{"label":"Headquarters","value":"Elk Grove Village, Illinois, US"},{"label":"Parent","value":"Carlisle Companies (since 2019)"}],"regions":["North America"],"aliases":["PAC-CLAD","Petersen Aluminum","Petersen Aluminum Corporation"],"related":["standing-seam-metal-roof","metal-roofing","carlisle-companies","snow-guards"],"company":{"founded":"1965","headquarters":"Elk Grove Village, Illinois, United States","website":"https://www.pac-clad.com","parent":"Carlisle Companies","known_for":["PAC-CLAD metal roof and wall panels","Standing seam roofing","Coil and flat sheet"]},"sources":[{"title":"About Petersen","url":"https://www.pac-clad.com/about/","publisher":"Petersen"},{"title":"PAC-CLAD","url":"https://www.pac-clad.com/","publisher":"Petersen"}],"country":null},{"slug":"pib-roofing-membrane","title":"PIB Roofing Membrane","category":"low-slope-systems","type":"term","summary":"Single-ply membrane made from polyisobutylene, usually fleece-backed with a welding edge, long used in Germany and compatible with bitumen.","body":"PIB (polyisobutylene) roofing membranes are synthetic single-ply sheets based on polyisobutylene, a rubbery polymer of isobutene. PIB is one of the oldest polymeric roofing materials still in use and is associated especially with Germany and central Europe.\n\n## History\n\nPIB roofing membranes have been made in Germany for many decades; one manufacturer reports single-ply products on the market since the 1930s and a reference roof installed in 1956 that remains watertight. One German manufacturer has supplied the UK market since the mid-1970s, and a trade report put PIB at about a third of that company's market segment.\n\n## Construction\n\nTypical PIB sheets are laminated to a synthetic fleece on the underside, which protects the membrane from the substrate, keeps it dimensionally stable and provides a bonding surface for adhesives. Products commonly have a prefabricated welding edge along one side, and seams are joined by hot-air welding. Sheets are commonly about 1.5 m (59 in) wide.\n\n## Properties\n\n- **Bitumen compatibility:** unlike EPDM and many PVC sheets, PIB can be laid directly onto existing bituminous roofs without a separation layer, which suits refurbishment.\n- **Flexibility:** usable across a wide temperature range.\n- **Composition:** a trade report states that only about a quarter of one manufacturer's material comes from oil-derived sources, the rest being mineral.\n- **Approvals:** products are tested for hail resistance (EN 13583) and root resistance (FLL), allowing use under green roofs.\n\n## Installation\n\nThe fleece backing allows PIB sheets to be bonded to substrates with adhesive, and the bitumen compatibility makes them a common choice for overlaying old bituminous roofs. Manufacturers' system instructions govern attachment and detailing.","key_facts":[{"label":"Polymer","value":"Polyisobutylene"},{"label":"Oldest reported roof","value":"1956, Germany"},{"label":"Typical backing","value":"Synthetic fleece"},{"label":"Bitumen compatible","value":"Yes, without separation layer"},{"label":"Typical width","value":"About 1.5 m (59 in)"}],"regions":["Europe"],"aliases":["polyisobutylene membrane","PIB sheet","Rhepanol"],"related":["single-ply-roofing","fully-adhered-roof-system","green-roof","hot-air-welding"],"company":null,"sources":[{"title":"Rhepanol hfk brochure","url":"https://produktinfo.blauer-engel.de/uploads/pdf_uploads/25837_DOS_FDT_Broschuere_Rhepanol-hfk_A4_ENG_WEB_en.pdf","publisher":"FDT FlachDach Technologie / Blauer Engel"},{"title":"Keeping out water since 1873","url":"https://www.building.co.uk/focus/keeping-out-water-since-1873/3075040.article","publisher":"Building"},{"title":"Polyisobutylene","url":"https://en.wikipedia.org/wiki/Polyisobutylene","publisher":"Wikipedia"}],"country":null},{"slug":"piode","title":"Piode (Stone Roof Slabs)","category":"world-roofing","type":"term","summary":"Piode are hand-split stone slabs, usually gneiss, used as heavy traditional roofs in Ticino and neighbouring Alpine valleys of Switzerland and Italy.","body":"**Piode** (singular *pioda*) is the Italian and Ticinese term for flat stone slabs used to roof buildings in the southern Alps. Stone-slab roofs of this kind cover rural houses and farm buildings in many valleys in the Swiss canton of Ticino, such as the Maggia valley, and of neighbouring parts of Italy. They are heavy, very durable and strongly tied to local geology and landscape.\n\n## Material\n\nIn Ticino the characteristic roofing stone is **gneiss**, split by hand (*a spacco*) into slabs of traditional shapes and sizes. Craftsmen who can hand-cut gneiss into thin slabs have become rare. Limestone slabs are traditional only in the Mendrisiotto in the far south of the canton.\n\n## Construction\n\nGerman-language building references describe Ticino stone slabs laid almost horizontally on a cross-batten structure, giving a roof that is very stable and durable but costly to build. Switzerland traditionally used much natural stone on roofs, especially in Valais and Graubünden as well as Ticino.\n\n## Protection and subsidies\n\nTicino supports traditional roofs on rural buildings (*rustici*) through cantonal subsidies. These were introduced in the 1970s, abolished in 2003 to save money and reintroduced in 2012 alongside the cantonal plan for rural buildings (the PUC-PEIP \"Piano dei rustici\"). In December 2016 the cantonal parliament approved a credit of CHF 3.6 million, of which CHF 2.5 million was for traditional roofs. Under the directive of April 2017:\n\n- **Piode roofs** receive CHF 200 per m² of roof actually built, measured along the slope.\n- Only local gneiss split by hand qualifies; machine-worked slabs, non-local shapes and other stones such as quartzite are excluded.\n- **Coppi** (traditional curved clay tiles) receive 25% of the extra cost over a standard tile roof, for conservative restorations only.\n- Eligible buildings include those in listed localities, groups where at least two-thirds of roofs are already traditional, and buildings in protected landscapes whose original roof was piode.\n\nThe directive also notes that corrugated metal and grey concrete tiles are not part of traditional rural architecture.\n\n## Related traditions\n\nStone-slab roofs are part of a wider European family that includes French **lauzes** and English **stone slates**. Like them, piode roofs are threatened mainly by cost, the scarcity of skilled craftsmen and the availability of suitable stone, and survive largely through heritage policy.\n\n## Sources and gaps\n\nTypical slab thicknesses and roof weights per square metre: published information is limited.","key_facts":[{"label":"Region","value":"Ticino, Switzerland, and neighbouring Alpine valleys"},{"label":"Stone","value":"Hand-split gneiss (limestone in the Mendrisiotto)"},{"label":"Subsidy","value":"CHF 200 per m² (Ticino, 2017 directive)"},{"label":"Subsidy history","value":"Introduced 1970s, abolished 2003, reintroduced 2012"}],"regions":["Europe"],"aliases":["pioda","tetti in piode","Ticino stone roof"],"related":["lauze","stone-slate","roofing-in-switzerland","roofing-in-italy","schindel"],"company":null,"sources":[{"title":"Direttiva contributi tetti materiale tradizionale","url":"https://m4.ti.ch/fileadmin/DT/temi/puc_paesaggi_edifici_impianti_protetti/tetti_piode/Direttiva_contributi_tetti_materiale_tradizionale.pdf","publisher":"Repubblica e Cantone Ticino"},{"title":"Historische Dachdeckungen","url":"https://www.baunetzwissen.de/altbau/fachwissen/dach-deckungen/historische-dachdeckungen-2949105","publisher":"Baunetz Wissen"},{"title":"A valley's future lies in the Stone Age","url":"https://www.swissinfo.ch/eng/a-valley-s-future-lies-in-the-stone-age/1020788","publisher":"Swissinfo"}],"country":null},{"slug":"pipe-boot","title":"Pipe Boot (Vent Pipe Flashing)","category":"components","type":"term","summary":"A pipe boot is a flashing collar that seals a plumbing vent or other round pipe where it passes through the roof covering.","body":"A pipe boot, also called a vent boot, pipe flashing or (in the UK) a pipe collar or lead slate, seals the opening around a round penetration such as a plumbing vent stack, flue or conduit. It consists of a flat flange that integrates with the roof covering and a raised collar or cone that wraps the pipe.\n\n## Types\n\n- **Rubber or EPDM boot on a metal or plastic flange:** the most common type on North American asphalt roofs; the rubber gasket grips the pipe.\n- **All-metal (lead, copper or aluminium) flashings:** a lead flange with a lead sleeve dressed over the top of the pipe, traditional in Britain and on long-life roofs.\n- **Adjustable or split boots:** used for retrofits where the pipe cannot be removed, or on metal roofs where the flange must follow ribs.\n- **Storm collars and roof jacks:** used with metal flues, which must also keep code clearances to combustibles.\n\n## Installation principle\n\nThe flange is shingled into the roof: the lower part of the flange sits on top of the course below, while the courses above and at the sides cover the upper part. Water running down the slope is therefore carried over the flange. Exposed nail heads are sealed if the manufacturer requires.\n\n## Common failures\n\nThe rubber collars of many boots crack with age and UV exposure, typically well before the surrounding roof wears out, and are a common source of leaks on older roofs. Inspection and replacement of cracked collars is routine maintenance. Other problems include boots sized for the wrong pipe diameter, flanges installed on top of the upslope shingles, and squirrel or bird damage to soft lead sleeves.\n\n## Metal roofs\n\nOn profiled metal roofs, pipe flashings are usually flexible silicone or EPDM boots with a pliable base sealed and screwed to the panel, placed to avoid blocking water flow between ribs.","key_facts":[{"label":"Also called","value":"Vent boot, pipe collar, pipe flashing"},{"label":"Common failure","value":"Cracked rubber collar"},{"label":"Flange layout","value":"Lower part over shingles, upper part under"}],"regions":["Global"],"aliases":["vent boot","pipe flashing","pipe collar","plumbing boot","roof jack"],"related":["roof-flashing","roofing-fasteners"],"company":null,"sources":[{"title":"Chimneys & Crickets, Skylights, Pipes, Flues, Exhaust Vents & Solar","url":"https://open-exam-prep.com/study-guides/mi-roofing-contractor/flashings-penetrations/chimney-crickets-skylights-penetrations","publisher":"Open Exam Prep"},{"title":"Flashing (weatherproofing)","url":"https://en.wikipedia.org/wiki/Flashing_(weatherproofing)","publisher":"Wikipedia"}],"country":null},{"slug":"pit-house","title":"Pit House","category":"history","type":"article","summary":"A dwelling built over a pit dug into the ground, with a roof springing from at or near ground level; found worldwide from the Palaeolithic to the 20th century.","body":"A pit house is a dwelling whose floor is dug into the ground, so that much of the wall height is provided by the earth itself and the roof begins at or close to ground level. Archaeologists also call it a sunken-featured building, or a Grubenhaus or grubhouse after the German term. Pit houses are among the most widespread house types in history because they save building material, keep a steady temperature and resist wind.\n\n## How the roof works\n\nThe pit gives a ready-made lower wall. Above it, posts set in the floor or around the edge carry a frame of beams and rafters, which is covered with whatever was locally available: thatch, bark, brush, hides, turf or a thick layer of earth. Common details include:\n\n- a central smoke hole, which in some designs doubled as the entrance by ladder;\n- eaves brought down to the edge of the pit, giving a low, bunker-like profile;\n- two to six main posts, sometimes none, depending on span.\n\nUsually only the hollow and the post holes survive, so the roof form must be inferred.\n\n## Around the world\n\n- **Ukraine:** shelters at Mezhyrich, with a mammoth-bone base about 3.7-4.3 m (12-14 ft) across and probably hide covers, are among the oldest proposed examples.\n- **Japan:** tateana dwellings have been found from Palaeolithic sites in Hokkaido and Kyushu through the Jomon period. Burned examples at the Goshono site suggest some had earth-covered roofs rather than thatch.\n- **Korea:** umjip pit dwellings were used from the Neolithic until the Three Kingdoms period.\n- **China:** Neolithic pit houses are known along the Yellow River, including Banpo of the Yangshao culture, where floors lay about 1 m (3 ft) below ground. Dugout dwellings (diyinzi or diwozi) were still built in the north into the 20th century, for example at the Daqing and Karamay oil fields.\n- **North America:** on the inland Plateau of the Pacific Northwest, people wintered in round pit houses near rivers such as the Columbia and Fraser, with frames covered by thatch and earth and diameters from a few metres to over 20 m (66 ft). In the Southwest, pit houses are associated with the Ancestral Pueblo, Hohokam, Mogollon and Fremont cultures. The Plains earth lodge is a related, larger form.\n- **Europe:** sunken-featured buildings were common in northern Europe between the 5th and 12th centuries CE. Examples at West Stow, England, measure about 3.7-4.4 m (12-14.5 ft) by 2.7-3.5 m (9-11.5 ft) and 0.6-1 m (2-3 ft) deep, with a gabled roof on posts at each end. Whether some had a suspended timber floor over the pit is debated.\n\n## Strengths and weaknesses\n\nEarth around and over the dwelling evens out daily and seasonal temperature swings, which suits cold winters and hot summers. The main weaknesses are damp and drainage: a pit collects water, so siting on well-drained ground and keeping the roof edge sound were essential.","key_facts":[{"label":"Other names","value":"Sunken-featured building, Grubenhaus, dugout"},{"label":"Typical roof","value":"Post-and-rafter frame with thatch, bark, turf or earth"},{"label":"Earliest examples","value":"Upper Palaeolithic (e.g. Mezhyrich, Ukraine)"},{"label":"Late use","value":"Northern China and North America into the 19th-20th centuries"}],"regions":["Global"],"aliases":["pit dwelling","pithouse","sunken-featured building","Grubenhaus","dugout"],"related":["jomon-pit-dwellings","banpo-houses","earth-lodge","mezhyrich-mammoth-bone-dwellings","sod-roof","prehistory-of-roofing"],"company":null,"sources":[{"title":"Pit-house","url":"https://en.wikipedia.org/wiki/Pit-house","publisher":"Wikipedia"},{"title":"Goshono Site","url":"https://www.mlit.go.jp/tagengo-db/en/R2-00507.html","publisher":"Japan Tourism Agency multilingual commentary database"},{"title":"Banpo","url":"https://en.wikipedia.org/wiki/Banpo","publisher":"Wikipedia"}],"country":null},{"slug":"pitch-gauge","title":"Pitch Gauge and Roofing Calculator","category":"tools-equipment","type":"term","summary":"Tools and methods for measuring roof slope, expressed as rise per run or degrees, and for converting roof dimensions into material quantities.","body":"Roof slope affects which materials can be used, how they must be installed, and how much material is needed. A **pitch gauge** (also called a roof pitch finder or slope gauge) measures the slope of a roof surface or rafter, and a **roofing calculator**, whether a chart, a construction calculator or software, converts slope and plan dimensions into areas and material quantities.\n\n## How slope is expressed\n\n- **Rise per run**: in North America, slope is usually stated as inches of rise per 12 inches of horizontal run, written as 4:12 or 4-in-12. Metric practice may give millimetres of rise per metre of run, or a ratio such as 1:3.\n- **Degrees** from horizontal are common in Europe, Australia and many other regions.\n- **Percent** (rise divided by run, times 100) is used in some contexts, especially for low slopes.\n\nStrictly, some carpentry sources distinguish \"pitch\" (rise over total span) from \"slope\" (rise over run), but in everyday roofing the terms are often used interchangeably. As a worked example, a 4:12 slope is about 18.4 degrees and a 12:12 slope is 45 degrees. Building codes set minimum slopes for many coverings, so an accurate reading matters.\n\n## Measuring tools\n\n- **Mechanical pitch gauges** with a bubble level and pivoting arm, placed on the roof or a rafter, read slope directly.\n- **Digital inclinometers and angle finders** give readings in degrees or as a ratio.\n- **Framing (steel) squares and levels**: holding a level horizontally and measuring the drop over 12 in (or a set metric run) gives rise per run.\n- **Smartphone apps, drones and aerial measurement services** estimate slope and area from images.\n\n## Calculating quantities\n\nPlan (horizontal) area is multiplied by a slope factor to find actual roof area; steeper roofs have more surface area than their footprint. In North America, materials are commonly sold by the **square**, equal to 100 sq ft (about 9.3 m²) of roof coverage. Allowances are added for waste at hips, valleys and cuts, plus ridge and starter pieces. Manufacturer coverage figures for each product, including laps and exposure, govern the final quantities.","key_facts":[{"label":"Common North American notation","value":"Inches of rise per 12 in of run (e.g. 4:12)"},{"label":"Worked example","value":"4:12 is about 18.4 degrees"},{"label":"Roofing square","value":"100 sq ft (about 9.3 m2)"}],"regions":["Global"],"aliases":["roof pitch gauge","slope gauge","pitch finder","roofing calculator"],"related":["roof-pitch","roofing-square","drone-roof-inspection","chalk-line","low-slope-roof"],"company":null,"sources":[{"title":"Roof pitch","url":"https://en.wikipedia.org/wiki/Roof_pitch","publisher":"Wikipedia"},{"title":"Square (unit)","url":"https://en.wikipedia.org/wiki/Square_(unit)","publisher":"Wikipedia"},{"title":"Inclinometer","url":"https://en.wikipedia.org/wiki/Inclinometer","publisher":"Wikipedia"}],"country":null},{"slug":"plain-tile","title":"Plain Tile","type":"term","summary":"A small, flat roof tile, traditionally clay, hung on battens in double-lap courses so that every point of the roof is covered by at least two tiles.","body":"A plain tile is a small, flat or slightly cambered roof tile hung from battens by nibs on its back and laid in overlapping courses, much like slate. It is the traditional tile of much of southern and central England and has close relatives across northern Europe, including the German beaver-tail (Biberschwanz).\n\n## How plain tiling works\n\nPlain tiles are **double-lap**: each course overlaps not just the course below but also part of the one below that. The vertical joints between tiles are offset (\"broken\") from course to course, so that water running through a joint lands on the middle of a tile beneath. Because so much of each tile is hidden by laps, plain tiling uses many more tiles per square metre than single-lap interlocking tiles or pantiles, and the finished roof is heavier.\n\n## Shape and fixing\n\n- Tiles are usually given a slight **camber** (curve) along their length so the tail sits tightly on the tile below and resists wind lift.\n- **Nibs** on the back hook over the battens; many tiles also have nail holes, and building codes in exposed areas require a proportion of tiles to be nailed.\n- Special pieces cover the eaves, verges, valleys and hips, including **tile-and-a-half** units used at verges to maintain the bond, and bonnet or arris hip tiles.\n- Clay plain tiles come in a range of colours from the local clay; concrete plain tiles imitate them.\n\n## Ornamental tiling\n\nPlain tiles can be cut with rounded, pointed or scalloped tails and mixed with standard tiles to create decorative bands, a feature of Victorian and Arts and Crafts houses. The same principle is used on tile-hung walls, where plain tiles are fixed to vertical battens.\n\n## Comparison with pantiles\n\nPantiles are single-lap and much lighter than plain tiles, which is why they can be used on lower pitches. Plain tiles need comparatively steep pitches because water relies entirely on the overlap and slope to drain.\n\n## Conservation\n\nOn historic buildings, heritage guidance favours reusing sound old tiles and matching new tiles to the original clay colour, size and camber, rather than mixing materials.\n","key_facts":[{"label":"Lap","value":"Double lap"},{"label":"Fixing","value":"Nibs on battens, plus nails"},{"label":"Relatives","value":"Beaver-tail (Biberschwanz), tile hanging"}],"regions":["Europe"],"aliases":["plain clay tile","peg tile","double-lap tile"],"related":["clay-roof-tile","beaver-tail-tile","pantile","concrete-roof-tile"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Pantile","url":"https://en.wikipedia.org/wiki/Pantile","publisher":"Wikipedia"},{"title":"Biberschwanzziegel","url":"https://de.wikipedia.org/wiki/Biberschwanzziegel","publisher":"Wikipedia (German)"}],"category":"materials","company":null,"country":null},{"category":"world-roofing","type":"article","company":null,"slug":"plank-house","title":"Plank House","summary":"Large rectangular house of the Pacific Northwest coast with walls and a gable or shed roof of split western red cedar planks, built for thousands of years.","body":"The plank house is the traditional large dwelling of the Indigenous peoples of the Pacific Northwest coast of North America, from northern California through Oregon, Washington and British Columbia to south-east Alaska. It is a post-and-beam building clad on its walls and roof with wide planks split from cedar, often housing several families.\n\n## Roof forms\n\nTwo main forms are described:\n\n- **Gable roof**: paired ridgepoles carry roof planks sloping both ways, over vertical plank walls; some houses had an interior pit reached by steps. Chinookan houses on the lower Columbia River were gabled, with doors usually in the gable end.\n- **Shed roof**: a single-pitch roof, described by James Cook on Vancouver Island and around Puget Sound; these were among the largest houses of the region. Accounts suggest the pitch was set according to the direction of the rain, regionally from the south.\n\n## Planks\n\nWestern red cedar, with its straight grain and natural weather resistance, was the preferred wood in south-western Canada, Washington, Oregon and northern California; further north in Alaska, spruce was more often used. Planks were split from logs or even from standing trees with wedges and finished with an adze. Simon Fraser, descending the Fraser River in 1808, noted planks 3-4 in (7.6-10 cm) thick.\n\nRoof and wall planks were tied to the frame with cedar withes or cordage rather than nailed, so a household could move them between frames in summer and winter villages and leave the frames standing. Planks were sometimes sunk in ponds, probably to kill vermin and keep them from drying and splitting.\n\n## Size and lifespan\n\nLower Columbia houses ranged from about 30 ft to more than 400 ft (9-120 m) long and were commonly 15-30 ft (4.6-9 m) wide. The house at the Meier site near Scappoose, Oregon, measured about 55 by 90 ft (17 by 27 m); one at Cathlapotle, Washington, was 33 by 185 ft (10 by 56 m). A house could remain in use for 400 years or more, but roof planks needed replacing every few years and posts about once a decade; maintaining the Meier house over its life is estimated to have taken 700-1,400 trees. Fraser also described a house with walls 11 ft (3.4 m) high under a slanting roof.\n\n## Age\n\nBasic plank-house features on the lower Columbia are at least 2,000 years old, with the oldest houses there dated to about 2,200-2,500 years ago. The Paul Mason site at Kitselas Canyon, British Columbia, is about 3,000 years old, a rectangular building at the Maurer site dates to 2830-1920 BCE, and a rectangular structure in northern British Columbia about 7,000 years old is, according to the Oregon Encyclopedia, the oldest known on the coast.\n\n## Peoples\n\nPlank houses were built by many nations, including the Coast Salish, Quinault, Chinookan peoples, Kwakwaka'wakw and Tlingit.","key_facts":[{"label":"Region","value":"Pacific Northwest coast, N. California to Alaska"},{"label":"Material","value":"Split western red cedar planks (spruce in Alaska)"},{"label":"Roof forms","value":"Gable or shed"},{"label":"Fixing","value":"Lashed with cedar withes; planks movable"},{"label":"Roof plank renewal","value":"Every few years"}],"regions":["North America"],"aliases":["Cedar plank house","Big house","Plankhouse"],"related":["roofing-in-canada","roofing-in-the-united-states","longhouse-roof","wood-shake"],"sources":[{"title":"Plank house","url":"https://en.wikipedia.org/wiki/Plank_house","publisher":"Wikipedia"},{"title":"Chinookan Plankhouses","url":"https://www.oregonencyclopedia.org/articles/chinookan_plank_houses/","publisher":"Oregon Encyclopedia"},{"title":"Simon Fraser","url":"https://www.thecanadianencyclopedia.ca/en/article/simon-fraser","publisher":"The Canadian Encyclopedia"}],"country":null},{"slug":"plumbing-vent-flashing","title":"Plumbing Vent Flashing","category":"installation","type":"term","summary":"A plumbing vent flashing (pipe boot) is a flanged sleeve that seals a vent pipe through the roof and is woven into the courses around it.","body":"**Plumbing vent flashing**, also known as a **pipe boot**, **pipe jack** or **vent collar**, seals the hole where a drain-waste-vent pipe or similar round penetration passes through the roof. It is usually a flat flange with a raised sleeve or rubber collar that fits tightly around the pipe. Materials include lead, aluminium, galvanized steel with an EPDM collar, and all-plastic or rubber designs.\n\n## Installation on a shingle roof\n\nCanadian guidance describes:\n\n1. Flash every pipe and projection through the roof with a flange extending at least 150 mm (6 in) onto the roof and nailed securely.\n2. Weave the flange into the shingles: the lower part lies over the course below, and the upper part is covered by the course above.\n3. Align the bottom edge of the first shingle covering the flange with the bottom of the pipe so water cannot run under the flashing.\n4. Where a shingle cutout or sealant line falls level with the flange edge, add a piece of shingle or cement beneath to block a leak path.\n5. Cut the shingles cleanly around the sleeve, leaving about 12.7 mm (1/2 in) of clearance so granules and debris wash away.\n6. Use only the nails needed and seal any exposed heads with compatible sealant.\n\n## Lead and soft-metal boots\n\nLead boots are dressed by hand to the roof profile, and their tops are turned down into the pipe to form a cap. They suit uneven coverings such as tile and slate.\n\n## Service life and inspection\n\nRubber collars on combination boots weather and crack with sun exposure and often fail before the main roof covering. Roof inspection checklists list deteriorating caulking and separated flanges at penetrations as common problem areas. On membrane roofs, pipes are sealed with prefabricated or field-formed membrane boots and clamps rather than nailed flanges.","key_facts":[{"label":"Minimum flange onto roof (Canada)","value":"150 mm (6 in)"},{"label":"Clearance around sleeve","value":"About 12.7 mm (1/2 in)"},{"label":"Common materials","value":"Lead, aluminium, steel with EPDM collar"}],"regions":["Global"],"aliases":["pipe boot","pipe jack","vent pipe flashing","roof jack"],"related":["roof-flashing","step-flashing-installation","roof-inspection-procedure"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.4.4 Vent Pipes","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-4-vent-pipes/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 13.1.2 Potential Problem Areas","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/canadian-roofing-reference-manual-chapter-13-troubleshooting-and-repairs/13-1-identify-cause-of-problem/13-1-2-potential-problem-areas/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"pmma-roofing","title":"PMMA Liquid Roofing","category":"low-slope-systems","type":"term","summary":"Fast-curing two-part polymethyl methacrylate resin, reinforced with polyester fleece, used for flat roofs, flashing details, balconies and walkways.","body":"PMMA (polymethyl methacrylate) liquid roofing is a cold-applied, solvent-free, two-component resin system. A peroxide catalyst is mixed in just before use, triggering rapid polymerisation on the roof. The resin is applied over a primed substrate, a needle-punched polyester fleece is embedded while it is wet, and more resin saturates the fleece to form a seamless, reinforced membrane.\n\n## Curing\n\nThe defining feature of PMMA is speed. Typical systems cure in about 30-40 minutes and remain fast even at temperatures near 0 C (32 F). Product data for one system lists it as rainproof after about 30 minutes, walkable after about 35 minutes and fully hardened after about 6 hours, allowing a small roof or a detail to be completed in a day.\n\n## Typical properties\n\nOne reinforced PMMA roofing system lists a thickness of about 2.3 mm (90 mil) with fleece, minimum elongation of 30%, and the ability to bridge cracks of about 2 mm (0.08 in). Reflective white top coats are available.\n\n## Uses\n\n- flashing details on single-ply, bitumen and other roofs, including penetrations, upstands and drains\n- small or hard-to-access flat roofs and gutters\n- balconies, terraces, walkways, stairwells and parking decks, often with an integrated wearing surface\n- inverted and buried roofs, where it can be covered by paving, tiles or growing media\n\n## Considerations\n\nPMMA bonds to a wide range of substrates when correctly primed. Installers must mix the catalyst accurately and work within the short usable life of each mix, which one product lists as about 20 minutes.","key_facts":[{"label":"Chemistry","value":"Two-component PMMA, peroxide-catalysed"},{"label":"Typical cure","value":"About 30-40 minutes, even near 0 C (32 F)"},{"label":"Reinforcement","value":"Polyester fleece"},{"label":"Typical thickness","value":"About 2.3 mm (90 mil) reinforced"}],"regions":["Europe","North America","Global"],"aliases":["PMMA","polymethyl methacrylate membrane","acrylic resin waterproofing"],"related":["liquid-applied-roofing","cold-applied-roofing","parapet","roof-drain"],"company":null,"sources":[{"title":"Why the need for PMMA","url":"https://rcimag.co.uk/sika-roofing-hub/why-the-need-for-pmma","publisher":"RCI Magazine / Sika"},{"title":"Kemperol AC","url":"https://www.kemper-system.com/US/eng/products/kemperol-ac/","publisher":"Kemper System"},{"title":"Liquid Roofing and Waterproofing Association","url":"https://www.lrwa.org.uk/","publisher":"LRWA"}],"country":null},{"slug":"polycarbonate-roofing-sheet","title":"Polycarbonate Roofing Sheet","type":"term","summary":"A tough, transparent or translucent plastic sheet used for rooflights, conservatories, patio covers and greenhouses; sold as corrugated or multiwall panels.","body":"A polycarbonate roofing sheet is a panel of polycarbonate plastic used where a roof needs to let in daylight. It is widely used for rooflights in industrial roofs, carports, verandas, patio and pergola covers, conservatories and greenhouses. Common forms are **corrugated** single-wall sheets that match the profile of metal or bitumen sheets, and **multiwall** (twin-wall, triple-wall) sheets with internal ribs that trap air for insulation.\n\n## Material\n\nPolycarbonate was first commercialised in 1958 by Bayer (Makrolon) and in 1960 by General Electric (Lexan), following parallel discoveries in 1953. It is an amorphous thermoplastic with very high transparency, transmitting visible light better than many types of glass.\n\n## Key properties\n\n- **Impact strength**: very tough, with an Izod impact strength of about 600-850 J/m. It can deform considerably without shattering, which is why it is used where hail or breakage is a concern. One corrugated product is marketed as \"virtually unbreakable\" against hail and debris.\n- **Scratch resistance**: low; many sheets have a hard coating.\n- **UV**: standard polycarbonate yellows and becomes brittle in sunlight, so roofing sheets need a UV-protective co-extruded layer on the outer face. The protected side must face up.\n- **Thermal movement**: a linear expansion coefficient of about 65-70 x 10⁻⁶ per K so fixings need oversized holes and the sheet needs room to move.\n- **Temperature range**: working limits of about -40 °C to 115-130 °C (-40 °F to 240-265 °F).\n- **Weight**: light; one 1 mm (0.04 in) corrugated product weighs about 1.5 kg/m² (0.3 lb/ft²).\n- **Fire**: one corrugated polycarbonate sheet is rated B-s1, d0 for reaction to fire under the European system.\n\n## Care\n\nCleaning should use mild soap or alcohol for grease. Ammonia, acetone, alkaline cleaners and bleach can damage polycarbonate and should be avoided.\n\n## Compared with GRP sheets\n\nGlass-reinforced plastic (GRP, \"fibreglass\") rooflight sheets, made from polyester resin reinforced with glass fibres, are an older alternative. Glass-fibre reinforced plastics date from the late 1930s and 1940s, when Owens Corning's glass fibre and early polyester resins were developed. The two materials behave differently in impact, weathering and fire, so the manufacturer's data for the specific sheet should be checked.\n\n## Safety\n\nPlastic rooflights can be fragile, especially as they age. Falls through rooflights are a serious hazard, and roofs with rooflights should be treated as fragile unless proven otherwise.\n","key_facts":[{"label":"Forms","value":"Corrugated single-wall; multiwall"},{"label":"Impact strength","value":"Izod about 600-850 J/m"},{"label":"Thermal expansion","value":"About 65-70 x 10⁻⁶/K"},{"label":"First commercial production","value":"1958 (Bayer), 1960 (GE)"}],"regions":["Global"],"aliases":["polycarbonate sheet","PC roofing","multiwall polycarbonate","twinwall sheet","clear roofing sheet","GRP rooflight sheet","fibreglass roofing sheet"],"related":["skylight","corrugated-bitumen-sheet","corrugated-fibre-cement-sheet","fragile-roof"],"sources":[{"title":"Polycarbonate","url":"https://en.wikipedia.org/wiki/Polycarbonate","publisher":"Wikipedia"},{"title":"ONDUCLAIR PC","url":"https://uk.onduline.com/en/diy/products/lighting-opaque-plastics/onduclair-pc","publisher":"Onduline UK"},{"title":"Fibre-reinforced plastic","url":"https://en.wikipedia.org/wiki/Fibre-reinforced_plastic","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"polyglass","title":"Polyglass","category":"manufacturers","type":"company","summary":"Polyglass is an Italian-origin maker of modified-bitumen membranes and underlayments, owned by Mapei since 2008, with US headquarters in Deerfield Beach, Florida.","body":"Polyglass is a manufacturer of modified-bitumen roofing membranes, self-adhered underlayments, roof coatings and waterproofing. The company began in Italy, where its first plant was built in 1972 at Ponte di Piave, north of Venice. The Italian adhesives and building-chemicals group Mapei acquired Polyglass in 2008. Its US subsidiary, Polyglass U.S.A., has been headquartered in Deerfield Beach, Florida since 2010.\n\n## Parent company\n\nMapei was founded in Milan in 1937 by Rodolfo Squinzi and is controlled by the Squinzi family. It makes adhesives, sealants and chemical products for construction, and Polyglass's US range also includes Mapei-branded products such as Mapeplan and Mapethene.\n\n## US manufacturing\n\nPolyglass U.S.A. lists six US manufacturing facilities: two in Fernley, Nevada, and one each in Hazleton, Pennsylvania; Winter Haven, Florida; Waco, Texas; and Phoenix, Arizona.\n\n## Products\n\n- **Modified-bitumen membranes**: APP (atactic polypropylene) and SBS (styrene-butadiene-styrene) sheets, including self-adhered and fire-resistant versions, base sheets and felts.\n- **Underlayments**: the Polystick line of self-adhered underlayments for steep-slope roofs.\n- **Single-ply PVC** membranes and adhesives.\n- **Coatings**: elastomeric and asphaltic roof coatings and PMMA liquid systems.\n- **Waterproofing**, air and vapour barriers, insulation, cover boards, edge metal, fasteners and sealants.\n\nThe company serves both low-slope commercial and steep-slope residential markets, a combination common among modified-bitumen manufacturers because self-adhered bitumen underlayments share technology with commercial membranes.\n\n## APP and SBS\n\nAPP-modified membranes are usually torch-applied or heat-welded and are relatively stiff, while SBS-modified membranes stay flexible at low temperatures and can be set in hot asphalt, cold adhesive or supplied as self-adhered sheets.","key_facts":[{"label":"First plant","value":"1972, Ponte di Piave, Italy"},{"label":"Parent","value":"Mapei (since 2008)"},{"label":"US headquarters","value":"Deerfield Beach, Florida"},{"label":"US plants","value":"6"}],"regions":["North America","Europe"],"aliases":["Polyglass U.S.A.","Polyglass USA"],"related":["modified-bitumen-roofing","app-modified-bitumen","sbs-modified-bitumen","ice-and-water-shield","pvc-roofing"],"company":{"founded":"1972","headquarters":"Deerfield Beach, Florida, United States","website":"https://www.polyglass.us","parent":"Mapei","known_for":["APP and SBS modified-bitumen membranes","Polystick self-adhered underlayments"]},"sources":[{"title":"About Polyglass","url":"https://www.polyglass.us/about-us/","publisher":"Polyglass U.S.A."},{"title":"Polyglass","url":"https://www.polyglass.us/","publisher":"Polyglass U.S.A."},{"title":"Mapei","url":"https://en.wikipedia.org/wiki/Mapei","publisher":"Wikipedia"}],"country":null},{"slug":"polyiso-insulation","title":"Polyiso (Polyisocyanurate) Roof Insulation","category":"low-slope-systems","type":"term","summary":"Rigid thermoset foam board with facers, the most common low-slope roof insulation in North America, valued for high thermal resistance per thickness.","body":"Polyisocyanurate, called polyiso, PIR or ISO, is a rigid thermoset foam closely related to polyurethane but made with a higher proportion of MDI and a polyester polyol. The MDI molecules link into isocyanurate rings, giving a stiffer and more thermally stable structure than polyurethane. For roofing it is made as boards laminated between facers of coated glass-fibre mat, paper or foil.\n\n## Thermal performance\n\nPolyiso has one of the lowest thermal conductivities of common roof insulations, about 0.023 W/(m.K) for typical products. Its North American trade association notes that R-value per inch increases with board thickness. Because it is a gas-blown foam, its thermal resistance changes over time and with temperature, so North American codes use long-term thermal resistance (LTTR) values for it.\n\n## Uses\n\n- primary insulation under single-ply, modified bitumen and BUR membranes\n- tapered boards to create slope\n- high-density (HD) polyiso cover boards over softer insulation\n- insulated metal sandwich panels for roofs and walls\n\n## Fire\n\nIsocyanurate bonds break down at higher temperatures than urethane bonds, and polyiso performs well in North American foam-plastic fire tests such as ASTM E84 and NFPA 285 when used in listed assemblies. Some researchers caution that small-scale tests do not represent all fire hazards, and studies have found PIR combustion produces significant toxic gases including hydrogen cyanide. In the UK the material was examined in the Grenfell Tower inquiry for its use in façade systems.\n\n## Considerations\n\nPolyiso should be kept dry; wet boards lose insulating value and facers can delaminate, reducing wind resistance of adhered membranes. Boards are typically mechanically fastened or adhered and staggered in multiple layers to limit joint heat loss.","key_facts":[{"label":"Conductivity","value":"About 0.023 W/(m.K)"},{"label":"Facers","value":"Coated glass-fibre, paper, foil"},{"label":"North American rating","value":"LTTR"},{"label":"Common forms","value":"Flat and tapered boards, HD cover board"}],"regions":["North America","Europe","Global"],"aliases":["polyiso","PIR","polyisocyanurate","ISO board"],"related":["roof-insulation","cover-board","tapered-insulation","eps-insulation","xps-insulation"],"company":null,"sources":[{"title":"Polyisocyanurate","url":"https://en.wikipedia.org/wiki/Polyisocyanurate","publisher":"Wikipedia"},{"title":"Polyiso insulation","url":"https://www.polyiso.org/","publisher":"Polyisocyanurate Insulation Manufacturers Association"}],"country":null},{"slug":"ponding-water","title":"Ponding Water","category":"low-slope-systems","type":"article","summary":"Water that stays on a low-slope roof after rain, commonly defined as water remaining 48 hours after the rain stops.","body":"Ponding water is rainwater or meltwater that collects in low areas of a roof and fails to drain. In North American practice ponding is usually defined as water still present 48 hours after rainfall ends under drying conditions. Short-lived puddles that evaporate quickly are generally not considered ponding.\n\n## Causes\n\n- too little slope or fall in the original design\n- deck deflection, which creates a dip that holds water and then deflects further under the added weight\n- construction tolerances, uneven decks and backfalls\n- compressed or dented insulation under traffic or equipment loads\n- drains set too high, too few outlets, or outlets blocked by leaves, dirt and algae\n- interrupted falls behind rooflights, plant bases and upstands\n- membrane laps running against the direction of flow\n\n## Effects\n\nPonding speeds up membrane ageing and surface erosion, encourages plant and fungal growth, and lets more water enter if the membrane is punctured. It adds dead load: 25 mm (1 in) of water over 20 m2 (215 sq ft) weighs about 500 kg (1,100 lb). Water left on a roof can freeze, creating slip hazards and stressing some membranes. On inverted roofs it also reduces thermal performance. In severe cases the cycle of deflection and accumulation, called ponding instability, can lead to structural failure, which is why US codes require a structural check for roofs designed with slopes below 1/4 in per 12 in.\n\n## Prevention and correction\n\n- design adequate slope (see positive drainage)\n- use tapered insulation, crickets and saddles\n- add drains or overflow outlets where surveys show low spots\n- recess outlets into sumps\n- keep drains and gutters clear through routine inspections, typically in spring and autumn\n\n## Product ratings\n\nMany coatings and some membranes are not warranted for ponding water. Acrylic coating manufacturers commonly exclude it, while some silicone and polyurethane coatings include it. Specifiers check product literature when ponding cannot be eliminated.","key_facts":[{"label":"Common definition","value":"Water remaining 48 hours after rain"},{"label":"Load example","value":"25 mm water on 20 m2 is about 500 kg (1 in on 215 sq ft, 1,100 lb)"},{"label":"Key risk","value":"Ponding instability and progressive deflection"}],"regions":["Global"],"aliases":["ponding","standing water","roof ponding","standing water on roof"],"related":["positive-drainage","tapered-insulation","roof-drain","cricket-roofing","acrylic-roof-coating","silicone-roof-coating","roof-drainage-design","blue-roof","snow-load","low-slope-roof","scupper","alligatoring"],"company":null,"sources":[{"title":"Rules for long-lasting BUR systems (H. H. Pierce, Interface, Oct 2006)","url":"https://iibec.org/wp-content/uploads/2006-10-Pierce.pdf","publisher":"IIBEC"},{"title":"Tech Today: roof slope and positive drainage (M. Graham, March 2005)","url":"https://professionalroofing.net/articles/article/615","publisher":"Professional Roofing / NRCA"},{"title":"How to avoid ponding on flat roofs","url":"https://www.specifiedby.com/soprema-uk/news/how-to-avoid-ponding-on-flat-roofs","publisher":"Soprema UK via SpecifiedBy"},{"title":"Quality alert: flat and inverted roofs","url":"https://wa-uks-constructionqualitypathway-pr.azurewebsites.net/media/lsfeckuo/quality-alert-flat-and-inverted-roofs.pdf","publisher":"Construction Quality Pathway"},{"title":"Roof coating","url":"https://en.wikipedia.org/wiki/Roof_coating","publisher":"Wikipedia"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"},{"title":"2021 International Plumbing Code, Chapter 11 Storm Drainage","url":"https://codes.iccsafe.org/content/IPC2021P1/chapter-11-storm-drainage","publisher":"International Code Council"},{"title":"Ponding Water Basics","url":"https://asphaltroofing.org/ponding-water-basics/","publisher":"Asphalt Roofing Manufacturers Association"},{"title":"The Effects of Ponding Water","url":"https://asphaltroofing.org/the-effects-of-ponding-water/","publisher":"Asphalt Roofing Manufacturers Association"},{"title":"Ponding","url":"https://en.wikipedia.org/wiki/Ponding","publisher":"Wikipedia"},{"title":"Still water runs deep","url":"https://www.professionalroofing.net/articles/article/2109","publisher":"Professional Roofing"}],"country":null},{"slug":"portable-roll-former","title":"Portable Roll Former","category":"tools-equipment","type":"term","summary":"A trailer- or truck-mounted machine that forms metal roofing panels from flat coil on the job site, allowing long continuous panels.","body":"A portable roll former is a machine that shapes flat metal coil into roofing or wall panels at or near the building site. The coil passes through a series of roller stations, each of which progressively bends the metal until it reaches the final profile, and a shear cuts the panel to length. Portable machines are usually mounted on a trailer or truck, or are compact enough to be set up on the ground or even on the roof.\n\n## Why form on site\n\n- **Long panels**: panels can be produced in continuous lengths from eave to ridge, limited mainly by handling and thermal movement, which avoids end laps that would be needed with shorter shipped panels.\n- **Logistics**: coil is easier to transport than long finished panels, and panels can be cut exactly to measured lengths.\n- **Lead times**: contractors can produce panels as needed rather than waiting for factory orders.\n\n## Profiles\n\nMost portable machines produce standing seam profiles, often several from one machine with interchangeable roller sets, such as snap-lock, nail-strip (fastener flange) and mechanical-lock seams. Some also form gutters or wall panels. Each profile requires its own tooling and setup.\n\n## Materials\n\nMachines are rated for specific material types, thicknesses and widths of coil. Suppliers list compatibility with metallic-coated steels such as galvanised and aluminium-zinc coatings, prepainted steel, aluminium and, on some machines, copper, zinc or stainless steel.\n\n## Considerations\n\n- **Quality control**: the roller settings, coil quality and operator skill all affect panel straightness, seam fit and the visibility of oil canning.\n- **Warranties**: some panel and paint warranties apply only to panels formed on approved equipment or by certified operators, and coil suppliers may have their own requirements.\n- **Training and maintenance**: rollers must be kept clean and aligned, and setup for each profile must follow the machine manufacturer's instructions.\n- **Site requirements**: power, level ground, coil handling equipment and space to support long panels as they leave the machine.\n\nIndustry associations such as the Metal Construction Association publish educational material on portable roll-forming equipment.","key_facts":[{"label":"Function","value":"Forms coil into panels on site"},{"label":"Common profiles","value":"Snap-lock, nail-strip, mechanical-lock standing seam"},{"label":"Main benefit","value":"Long continuous panels cut to length"}],"regions":["Global"],"aliases":["rollformer","portable panel machine","on-site roll forming"],"related":["standing-seam-metal-roof","power-seamer","oil-canning","sheet-metal-brake","metal-roofing"],"company":null,"sources":[{"title":"Roll former portable producing three standing seam profiles","url":"https://www.kloecknermetals.com/the-kloeckner-advantage/equipment/roll-former-portable-producing-three-standing-seam-profiles/","publisher":"Kloeckner Metals"},{"title":"Portable roll former equipment","url":"https://metalconstruction.org/view/download.php/online-education/education-materials/other-educational-files/portable-roll-former-equipment","publisher":"Metal Construction Association"},{"title":"What is a Schlebach mini roll former and how does it work","url":"https://www.stortz.com/what-is-a-schlebach-mini-roll-former-how-does-it-work/","publisher":"John Stortz & Son"}],"country":null},{"slug":"positive-drainage","title":"Positive Drainage and Roof Falls","category":"low-slope-systems","type":"article","summary":"The design principle that a low-slope roof must have enough built-in slope (fall) to shed water within a set time, allowing for deflection and tolerances.","body":"Positive drainage is the condition in which a low-slope roof drains completely after rain instead of holding water. The slope that achieves it is called the \"fall\" in British usage and the \"slope\" or \"pitch\" in North America. Because low-slope roofs are almost level, small errors in the deck or insulation can create hollows, so drainage has to be designed deliberately.\n\n## North American approach\n\nThe NRCA Roofing Manual recommends that every roof be designed for positive drainage, defined as enough slope, after allowing for deck deflection under all loads, for the roof to drain within 48 hours after rainfall under conditions that allow drying. This is a performance requirement rather than a fixed number.\n\nThe International Building Code is prescriptive: most membrane roofs need a design slope of at least 1/4 in per 12 in (2%), and coal-tar built-up roofs at least 1/8 in per 12 in (1%). For reroofing, the IBC exempts roofs that already provide positive drainage. Roofs designed below 1/4:12 generally need a structural analysis under IBC Section 1611.2 to show they will not deflect progressively under ponded water. NRCA reported that in its problem-roof database more than two-thirds of the projects had slopes below 1/4:12.\n\n## UK and European approach\n\nBS 6229 requires a minimum finished fall of 1:80 (about 0.7 degrees, or 1.25%) on most flat roofs. For many years designers used a design fall of 1:40 to achieve 1:80 on site. The 2025 edition replaced this rule with design falls based on structural analysis and survey data; it cites 1:60 as a common starting point, requires 1:40 where deflection exceeds 17 mm over 1 m, and treats backfalls as unacceptable. Zero-fall roofs are accepted only for specific third-party certified systems.\n\n## Ways to create slope\n\n- sloping the structure (beams, purlins or joists set at different heights)\n- firring strips on timber decks\n- screeds on concrete slabs\n- tapered insulation\n- crickets and saddles to divert water around obstructions and between drains\n\n## Related drainage elements\n\nPositive drainage also depends on enough outlets in the right places. Guidance commonly calls for at least two outlets or an overflow on every roof so one blockage does not flood it, and for outlets to be recessed or set in sumps so lap build-ups do not trap water.","key_facts":[{"label":"NRCA criterion","value":"Drains within 48 hours after rain"},{"label":"IBC minimum slope","value":"1/4:12 (2%)"},{"label":"UK minimum finished fall","value":"1:80 (about 0.7 degrees)"},{"label":"BS 6229:2025 typical design fall","value":"1:60; 1:40 where deflection exceeds 17 mm per 1 m"}],"regions":["Global","North America","Europe"],"aliases":["roof fall","roof slope","drainage fall","design fall","finished fall"],"related":["ponding-water","tapered-insulation","cricket-roofing","roof-drain","overflow-drainage","low-slope-roof"],"company":null,"sources":[{"title":"Tech Today: roof slope and positive drainage (M. Graham, March 2005)","url":"https://professionalroofing.net/articles/article/615","publisher":"Professional Roofing / NRCA"},{"title":"Minn. R. 1305.1507 - Requirements for Roof Coverings (IBC Section 1507 amendments)","url":"https://www.law.cornell.edu/regulations/minnesota/Minn-R-1305-1507","publisher":"Cornell Law School LII"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"},{"title":"Falls and drainage","url":"https://www.bauder.co.uk/roof-systems/refurbishment-projects/solving-the-challenge/improving-drainage-falls","publisher":"Bauder"},{"title":"What is the minimum drainage falls for a single ply flat roof?","url":"https://ikogroup.co.uk/?p=829","publisher":"IKO"}],"country":null},{"slug":"pre-weathered-zinc","title":"Pre-Weathered Zinc","category":"materials","type":"article","summary":"Pre-weathered zinc is titanium-zinc sheet given a factory surface treatment so it looks like naturally weathered grey zinc from the day it is installed.","body":"Natural (bright-rolled) zinc is shiny when new and takes years to develop its characteristic grey patina. Pre-weathered zinc, also called pre-patinated zinc, is factory treated so that its surface already resembles that weathered finish. It is used where architects want a uniform matte appearance immediately, for instance on facades, prominent roofs and repairs next to old zinc.\n\n## How it is made\n\nManufacturers start with standard mill-finish titanium-zinc and run it through a controlled chemical surface treatment line. One producer describes its process as phosphating. Different treatments produce lighter blue-grey or darker graphite-grey finishes. Factory-applied transparent tinted coatings in blue, red or green tones are a related option; these typically last up to about 30 years before reverting towards natural grey.\n\n## Properties\n\n- The metal is zinc throughout, so cut and drilled edges weather to match without needing touch-up paint.\n- The finish is UV stable and not prone to rust streaking.\n- Installation, folding and soldering methods are broadly the same as for natural zinc, although surface treatments may affect soldering preparation.\n- The same design rules apply: ventilation or underside protection against condensation, allowance for thermal movement, and care when folding in cold weather.\n\n## Weathering over time\n\nPre-weathering does not stop the natural patina from forming. Over years the treated surface blends into the normal zinc hydroxy-carbonate layer, which is self-healing when scratched.\n\n## Where it is used\n\nPre-weathered finishes are popular for renovation and infill work in historic European streets, where new zinc must sit next to roofs that are decades old, and on facades where uneven early weathering of bright zinc would be conspicuous. Natural zinc normally needs about 2 to 5 years outdoors to reach a similar grey, faster in polluted air.","key_facts":[{"label":"Base material","value":"Titanium-zinc (EN 988 alloy)"},{"label":"Treatment","value":"Factory chemical surface treatment (e.g. phosphating)"},{"label":"Typical finishes","value":"Blue-grey and dark graphite-grey"}],"regions":["Europe","Global"],"aliases":["pre-patinated zinc","prepatina zinc","pre-weathered titanium zinc"],"related":["zinc-roofing","standing-seam-metal-roof","ventilation-under-metal-roofs"],"company":null,"sources":[{"title":"Pre-weathered zinc: durable and truly maintenance free","url":"https://www.nedzink.com/en/pre-weathered-zinc-durable-and-truly-maintenance-free/","publisher":"NedZink"},{"title":"Essential Zinc: Building for the Future","url":"https://continuingeducation.bnpmedia.com/courses/umicore-building-products-usa-inc/essential-zinc-building-for-the-future/2/","publisher":"Continuing Education Center (BNP Media) / Umicore Building Products"}],"country":null},{"slug":"prehistoric-shelters-and-early-thatch","title":"Prehistoric Shelters and Early Thatch","category":"history","type":"article","summary":"What archaeology can and cannot say about the first roofs: brushwood huts, mammoth-bone dwellings and the likely Neolithic origin of straw thatch.","body":"The first roofs were almost certainly made of plant material, hides or bone, none of which survive well. What archaeologists find are traces: rings of charcoal, post holes, stone arrangements and piles of large bones. From these they reconstruct the shapes of shelters, but the exact roof covering is usually a matter of informed guesswork.\n\n## Earliest evidence\n\n**Terra Amata (Nice, France).** Excavated by Henry de Lumley in 1966, this beach site was interpreted as a camp of huts made of skins over poles, around central hearths, dated to roughly 380,000 years ago. The interpretation is disputed. Archaeologist Paola Villa argued the stone arrangements could have formed naturally and that the layers were mixed, making both the huts and the dating uncertain.\n\n**Ohalo II (Sea of Galilee, Israel).** Around 23,000 years old, the site preserves six oval charcoal rings, each about 2.7-4.9 m (9-16 ft) long, left by huts of branches and brushwood. They are often described as the world's oldest known brush dwellings, and the site also gives some of the earliest evidence for plant bedding.\n\n**Mezhyrich (Ukraine).** About 15,000 years ago, people built four huts from a total of 149 mammoth bones. A farmer found the first bone in 1965 while enlarging his cellar. How the frames were covered is not recorded in the evidence.\n\n## Origins of thatch\n\nResearchers think Late Palaeolithic shelters in Europe may have used reed, heather or rushes, but there is no direct archaeological proof. Straw thatch probably began in the Neolithic, once people grew cereal crops and had straw as a by-product. In Europe, direct physical evidence of thatch survives only from the early medieval period.\n\n## Why so little survives\n\nPlant roofs decay within decades unless burned, waterlogged or frozen. Even burning usually destroys the structure. As a result the long history of thatch, turf and bark roofing is reconstructed mainly from later traditional buildings, written records and ethnography rather than from surviving prehistoric roofs.\n\n## Legacy\n\nVegetable roofing never disappeared. Thatch, palm leaf, grass and turf roofs remain in use across Africa, Asia, the Pacific and northern Europe, and their techniques are a living link to the earliest shelters.","key_facts":[{"label":"Ohalo II huts","value":"About 23,000 years old; 2.7-4.9 m (9-16 ft) long"},{"label":"Mezhyrich huts","value":"About 15,000 years old; 149 mammoth bones"},{"label":"Straw thatch origin","value":"Probably Neolithic (no direct early evidence)"}],"regions":["Global","Europe","Middle East"],"aliases":["early roofs","prehistoric huts"],"related":["history-of-roofing","history-of-thatch-in-britain","scandinavian-sod-roofs","thatch"],"company":null,"sources":[{"title":"Ohalo II","url":"https://en.wikipedia.org/wiki/Ohalo_II","publisher":"Wikipedia"},{"title":"Mezhyrich","url":"https://en.wikipedia.org/wiki/Mezhyrich","publisher":"Wikipedia"},{"title":"Terra Amata (archaeological site)","url":"https://en.wikipedia.org/wiki/Terra_Amata_(archaeological_site)","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"}],"country":null},{"slug":"prehistory-of-roofing","title":"Prehistory of Roofing","category":"history","type":"article","summary":"How archaeologists reconstruct the earliest roofs and shelters, from Lower Palaeolithic woodworking to Neolithic longhouses and Bronze Age roundhouses.","body":"The prehistory of roofing covers the long period before written records, when people sheltered under branches, hides, bark, turf and thatch. Almost none of these materials survive. Archaeologists work instead from post holes, rings of stones or charcoal, collapsed debris and, very occasionally, timber preserved by water or fire. Most statements about prehistoric roofs are therefore reconstructions, and many are debated.\n\nThe broad pattern is clear even where details are not. Early shelters were light and temporary; with settled life and farming came heavier, longer-lasting houses whose roofs had to carry thatch, turf or earth for decades.\n\n## Lower and Middle Palaeolithic\n\n- **Kalambo Falls, Zambia:** two logs joined crosswise by a deliberately cut notch, dated by luminescence to at least 476,000 years ago and published in *Nature* in 2023. They are not a roof, but they are the earliest known structural woodworking, the skill on which every timber roof depends.\n- **Terra Amata, Nice, France:** interpreted by Henry de Lumley in 1966 as a camp of pole-and-hide huts about 400,000 years old. Paola Villa and others argued the stone arrangements and layers may be natural or mixed.\n- **Lazaret cave, Nice:** a line of large stones has been read as packing for the poles of a skin tent pitched against the cave wall, in layers of marine isotope stage 6 (186,000-127,000 years ago).\n\nEvidence for built shelter before about 50,000 years ago is slim, and light structures may leave no clear trace.\n\n## Upper Palaeolithic and Epipalaeolithic\n\n- **Ohalo II, Israel:** six oval brush-hut floors about 23,000 years old, preserved under the Sea of Galilee.\n- **Mezhyrich, Ukraine:** shelters framed and weighted with mammoth bone; a 2025 study dated the largest to about 18,300-17,800 years ago. The covering is thought to have been hides or birch bark.\n\n## Early villages and the Neolithic\n\n- **Natufian Levant:** round, semi-sunken stone-footed houses at Ain Mallaha, with posts carrying roofs probably of brushwood or hides.\n- **Pit houses:** dwellings sunk into the ground with a roof springing from near ground level, found from Japan's Jomon period and China's Yangshao culture (Banpo) to North America and early medieval Europe.\n- **Lepenski Vir, Serbia:** trapezoidal houses with stone-reinforced floor edges; the roof form is unknown and at least seven reconstructions have been proposed.\n- **Hemudu, China:** stilt houses about 7,000 years old with mortise-and-tenon timber joints.\n- **Linear Pottery (LBK) longhouses, central Europe:** timber houses up to 45 m (148 ft) long, with thatched roofs carried on three internal rows of posts.\n- **Orkney, Scotland:** sandstone roof slabs at the Ness of Brodgar are the first firm evidence of a Neolithic roof there.\n\n## Bronze and Iron Ages\n\nIn Britain and Ireland the roundhouse with a conical roof was standard from the Bronze Age into the Iron Age. Experiments at Butser Ancient Farm found a pitch of about 45 degrees worked well. At Must Farm, Cambridgeshire, roundhouses on stilts burned and fell into a river about 850 BCE, preserving rafters, turf and clay roof layers. Crannogs, artificial islands in lakes, carried similar houses in Scotland and Ireland.\n\n## What archaeology can and cannot show\n\nPost-hole plans show where the main supports stood and therefore the likely span, but not the pitch, ridge height or covering. Charred or waterlogged sites, such as Ohalo II and Must Farm, are rare windows onto actual roof materials. Experimental reconstructions test what is structurally possible and how long materials last; they do not prove what was built. Ethnographic comparison with recent thatch, bark, turf and earth roofs fills further gaps, with the risk that modern habits are projected onto the past.","key_facts":[{"label":"Earliest structural wood","value":"Kalambo Falls, at least 476,000 years ago"},{"label":"Oldest well-preserved brush huts","value":"Ohalo II, about 23,000 years ago"},{"label":"Earliest Orkney roof evidence","value":"Sandstone slabs, Ness of Brodgar (found 2010)"},{"label":"Main evidence types","value":"Post holes, charred or waterlogged timber, collapsed roof debris"}],"regions":["Global"],"aliases":["prehistoric roofing","earliest roofs","Stone Age roofs"],"related":["prehistoric-shelters-and-early-thatch","history-of-roofing","kalambo-falls-wooden-structure","terra-amata","ohalo-ii","mezhyrich-mammoth-bone-dwellings","pit-house","linear-pottery-longhouse","bronze-age-roundhouse","must-farm","thatch"],"company":null,"sources":[{"title":"Evidence for the earliest structural use of wood at least 476,000 years ago (report)","url":"https://www.sci.news/archaeology/wooden-structure-kalambo-falls-zambia-12283.html","publisher":"Sci.News"},{"title":"Grotte du Lazaret","url":"https://en.wikipedia.org/wiki/Grotte_du_Lazaret","publisher":"Wikipedia"},{"title":"Terra Amata (archaeological site)","url":"https://en.wikipedia.org/wiki/Terra_Amata_(archaeological_site)","publisher":"Wikipedia"},{"title":"18,000 years ago, ice age humans built dwellings out of mammoth bones in Ukraine","url":"https://livescience.com/archaeology/18-000-years-ago-ice-age-humans-built-dwellings-out-of-mammoth-bones-in-ukraine","publisher":"Live Science"},{"title":"Neolithic roof tiles","url":"https://www.nessofbrodgar.co.uk/neolithic-roof-tiles/","publisher":"Ness of Brodgar Excavation"},{"title":"Roundhouse (dwelling)","url":"https://en.wikipedia.org/wiki/Roundhouse_(dwelling)","publisher":"Wikipedia"}],"country":null},{"slug":"professional-roofing-magazine","title":"Professional Roofing","type":"organization","summary":"Professional Roofing is the monthly magazine of the U.S. National Roofing Contractors Association, covering roofing technology, business and regulation.","body":"*Professional Roofing* is a monthly magazine published by the National Roofing Contractors Association (NRCA) in the United States. It is NRCA's official publication and is available in print and online at professionalroofing.net, with a free subscription option for the magazine and its e-newsletter.\n\n## Content\n\nThe magazine aims to provide timely and objective information to roofing professionals. Regular sections include:\n\n- **News + Views** – industry news and opinion;\n- **Research + Tech** – technical articles on roof systems, materials and research;\n- **Rules + Regs** – coverage of building codes, safety rules and legislation;\n- departments such as Close-up, New Ideas, Briefings and Details.\n\nTopics range across roofing trends, business management, insurance, safety, new products and NRCA's own resources. Issues often feature specific roof systems and projects. For example, the October 2026 issue covered green roofs, metal roofing, a roofing project for the National Medal of Honor Museum and quality control on commercial low-slope roofs.\n\n## Audience\n\nReaders include roofing contractors, especially owners and managers of commercial and residential roofing firms, as well as consultants, architects, manufacturers and distributors. Because it is published by NRCA, the magazine reflects the association's technical positions and advocacy priorities, and it often reports on NRCA's manuals, training and government relations.\n\n## Related publications\n\nOther North American roofing trade titles include *Roofing Contractor* (published by BNP Media), *Western Roofing*, *Florida Roofing* (from the Florida Roofing and Sheet Metal Contractors Association) and journals of building enclosure consultants. In the UK, titles include *Roofing Today*. Many national roofing associations around the world publish their own member magazines, such as the German trade journal *DDH – Das Dachdecker-Handwerk*.","key_facts":[{"label":"Publisher","value":"National Roofing Contractors Association (NRCA)"},{"label":"Frequency","value":"Monthly"},{"label":"Country","value":"United States"},{"label":"Website","value":"professionalroofing.net"}],"regions":["North America"],"aliases":["Professional Roofing magazine"],"related":["nrca","roofing-contractor-magazine","roofing-today"],"company":{"website":"https://www.professionalroofing.net","parent":"National Roofing Contractors Association","known_for":["NRCA's official monthly publication"]},"sources":[{"title":"Professional Roofing","url":"https://www.professionalroofing.net/","publisher":"NRCA"},{"title":"National Roofing Contractors Association","url":"https://en.wikipedia.org/wiki/National_Roofing_Contractors_Association","publisher":"Wikipedia"}],"category":"organizations","country":null},{"slug":"protected-membrane-roof","title":"Protected Membrane Roof (Inverted Roof)","category":"low-slope-systems","type":"article","summary":"A low-slope roof in which the insulation is placed above the waterproofing, protecting it, and is held down by ballast or paving.","body":"A protected membrane roof (PMR), also called an inverted roof, upside-down roof or IRMA (insulated roof membrane assembly), reverses the usual order of layers. The waterproofing membrane sits directly on the deck, and moisture-resistant insulation boards, usually extruded polystyrene (XPS), are laid loose on top of it. Gravel, paving slabs or a green-roof build-up holds the insulation down against wind and flotation.\n\n## Why invert the roof\n\n- The membrane is shielded from UV light, extreme temperature swings, freeze-thaw cycles and foot traffic.\n- The membrane stays near the building's interior temperature, reducing thermal stress.\n- The top surface can be used as a terrace, podium, car park or green roof.\n\nIn the UK, BS 6229 treats inverted roofs as a subtype of warm roof construction.\n\n## Typical build-up\n\n1. Structural deck, usually reinforced concrete\n2. Waterproofing: hot-melt rubberised bitumen, liquid-applied membrane, modified bitumen or single-ply\n3. Optional protection layer\n4. XPS insulation boards\n5. Water flow reducing layer (WFRL) or filter fabric\n6. Ballast, paving or green-roof layers\n\n## Design considerations\n\nBecause rainwater runs beneath and between the boards, the insulation is partly wet and cold water flowing under it carries heat away. UK practice therefore adds a correction to insulation thickness: BS 6229:2025 calls for at least 2.5% extra where declared and design values are the same, and greater corrections for blue roofs. A WFRL with laps of about 300 mm (12 in) reduces this cooling. The roof must drain at two levels, over the WFRL and at membrane level, and decks must be built to falls without backfalls or hollows. Ballast must be heavy enough to stop boards floating. Condensation can occasionally form under the boards when the membrane is colder than the dew point.\n\n## Repair\n\nLeak location is harder than on an exposed roof, because ballast and insulation must be lifted. Electronic leak detection is often used at handover on concrete decks.","key_facts":[{"label":"Insulation position","value":"Above the membrane"},{"label":"Usual insulation","value":"Extruded polystyrene (XPS)"},{"label":"UK rainwater correction (BS 6229:2025)","value":"At least 2.5% extra thickness"},{"label":"WFRL lap","value":"About 300 mm (12 in)"}],"regions":["Global","Europe","North America"],"aliases":["inverted roof","upside-down roof","IRMA","PMR","insulated roof membrane assembly"],"related":["xps-insulation","ballasted-roof-system","hot-melt-rubberized-asphalt","green-roof","blue-roof","warm-roof"],"company":null,"sources":[{"title":"Inverted roof","url":"https://www.designingbuildings.co.uk/wiki/Inverted_roof","publisher":"Designing Buildings Wiki"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"},{"title":"Quality alert: flat and inverted roofs","url":"https://wa-uks-constructionqualitypathway-pr.azurewebsites.net/media/lsfeckuo/quality-alert-flat-and-inverted-roofs.pdf","publisher":"Construction Quality Pathway"},{"title":"Major Projects: Zero falls flat roof policy","url":"https://labcwarranty.co.uk/blog/major-projects-zero-falls-flat-roof-policy/?hsLang=en","publisher":"LABC Warranty"},{"title":"Warm roof","url":"https://www.designingbuildings.co.uk/wiki/Warm_roof","publisher":"Designing Buildings Wiki"}],"country":null},{"slug":"purlin","title":"Purlin","category":"components","type":"term","summary":"A purlin is a horizontal roof member running along the length of a roof, parallel to the ridge, that supports rafters or roof sheeting between main frames.","body":"A purlin is a horizontal beam that runs lengthwise along a roof, parallel to the ridge and eaves. It spans between principal rafters, trusses, gable walls or steel frames and supports either the common rafters above it or, in metal buildings, the roof sheeting directly. Purlins reduce the unsupported length of rafters and allow wider buildings to be roofed with smaller members.\n\n## In traditional timber roofs\n\nIn a historic \"double roof\", heavy principal rafters carry principal (side) purlins, and these purlins in turn carry lighter common rafters. Carpentry historians distinguish how the purlin meets the principal rafter:\n\n- **Through purlins** pass over the backs of the principals.\n- **Butt purlins** are tenoned into the sides of the principals.\n- **Clasped purlins** are held between a collar and the principal rafter.\n\nLarge old barns in North America often use purlin plates carried on posts, which support rafters at mid-span. A distinctive \"common purlin\" system, in which purlins are notched into principal rafters and carry vertical roof boards, is mainly associated with early New England.\n\nIn British vernacular roofs, wind braces were often fitted between principal rafters and purlins to stiffen the roof lengthwise.\n\n## In steel and metal buildings\n\nIn portal-frame and pre-engineered metal buildings, purlins are usually cold-formed steel sections in C, Z or U profiles, running parallel to the eaves between the main rafters. Z purlins can nest together for shipping and are often lapped over supports so they act as a continuous beam. Profiled metal roof sheets are fastened directly to them.\n\n## Terminology\n\nHistoric spellings include purline and perling. The word should not be confused with battens, which are smaller strips fixed across rafters to carry tiles or slates.","key_facts":[{"label":"Orientation","value":"Parallel to ridge"},{"label":"Steel profiles","value":"C, Z, U sections"},{"label":"Timber joints","value":"Through, butt, clasped"}],"regions":["Global"],"aliases":["purline","side purlin","principal purlin"],"related":["rafter","roof-truss","roof-battens","ridge-board"],"company":null,"sources":[{"title":"Purlin","url":"https://en.wikipedia.org/wiki/Purlin","publisher":"Wikipedia"},{"title":"Roof glossary","url":"https://www.mkheritage.org.uk/wdahs/Thornton/docs/roofglossary.html","publisher":"Milton Keynes Heritage Association"}],"country":null},{"slug":"pvc-roofing","title":"PVC Roofing","category":"low-slope-systems","type":"article","summary":"Polyvinyl chloride single-ply membrane made flexible with plasticisers and joined by hot-air welding; the first single-ply type standardised in the US.","body":"PVC (polyvinyl chloride) roofing is a thermoplastic single-ply membrane. Rigid PVC resin is made flexible with plasticisers and compounded with UV inhibitors, heat stabilisers, biocides and pigments, then formed into sheets, usually with polyester scrim or glass-fibre reinforcement. Seams are fused with hot air.\n\n## History\n\nThe first PVC roofs were installed in Europe in the early 1960s; vinyl membranes were developed in Germany and Switzerland and reached North America in the 1970s. ASTM D4434, the US standard for PVC sheet roofing, was published in 1985, making vinyl the first single-ply product with its own ASTM designation. The standard requires PVC resin to make up more than 50% of the polymer content.\n\n## Properties\n\n- **Weldability:** heat-welded seams are homogeneous and strong; hot-air equipment softens both surfaces and a roller presses them together.\n- **Fire:** vinyl is inherently self-extinguishing and performs well in fire testing.\n- **Chemicals:** formulations resist ponded rainwater and common rooftop contaminants such as bird droppings and acid rain, and can be adjusted for greater chemical resistance.\n- **Reflectivity:** white PVC typically reflects 80% or more of sunlight when new.\n\nTypical thicknesses range from about 0.9 mm (0.036 in) to 3 mm (0.120 in).\n\n## Plasticiser loss\n\nThe main long-term concern is migration and evaporation of low-molecular-weight plasticisers, which can make older sheets shrink and stiffen. One approach is to blend in KEE, a high-molecular-weight polymer that does not migrate.\n\n## Recycling\n\nFactory trimmings are recycled into new membrane and into products such as walkway pads.\n\n## Thickness and reinforcement\n\nThicker sheets give more puncture resistance and a greater wear layer. Reinforced sheets suit mechanically attached systems, while fleece-backed sheets are used for adhered and recover applications.","key_facts":[{"label":"First installed","value":"Europe, early 1960s"},{"label":"North America","value":"From the 1970s"},{"label":"US standard","value":"ASTM D4434 (1985)"},{"label":"Thickness range","value":"0.9-3 mm (0.036-0.120 in)"},{"label":"Seaming","value":"Hot-air welding"}],"regions":["Global","Europe","North America"],"aliases":["vinyl roofing","PVC membrane","polyvinyl chloride roofing"],"related":["single-ply-roofing","kee-roofing-membrane","tpo-roofing","hot-air-welding","roof-walkway-pad"],"company":null,"sources":[{"title":"The ABCs of PVC Roof Membranes","url":"https://usa.sika.com/dms/getdocument.get/88a0c83a-9151-4100-84d6-dccadfebd4aa/the-abcs-of-pvc-roof-membranes.pdf","publisher":"Sika USA"},{"title":"Sustaining a KEE standard for roofing membranes","url":"https://www.constructioncanada.net/sustaining-a-kee-standard-for-roofing-membranes/","publisher":"Construction Canada"},{"title":"Cool roof","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"}],"country":null},{"slug":"pvdf-coating","title":"PVDF Coatings (Kynar 500, Hylar 5000)","category":"components","type":"article","summary":"PVDF coatings are factory-applied fluoropolymer paints for metal roofing, prized for long-term colour and gloss retention under strong sunlight.","body":"PVDF (polyvinylidene fluoride) is a fluoropolymer used as the resin in premium coil-applied paints for architectural metal. In roofing these finishes are widely specified for standing seam panels, metal shingles, flashings and wall cladding, on steel, aluminium-zinc coated steel and aluminium substrates. They are known for strong resistance to ultraviolet light, chalking and fading.\n\n## Brands\n\nThe best-known resin brands are Kynar 500 (Arkema) and Hylar 5000 (Solvay). Resin producers license paint makers to formulate finished coatings; Arkema describes Kynar 500, introduced in 1965, as the original high-performance finish for architectural metal. In North American specifications, finishes are often described as \"70% PVDF\": coating suppliers state that PVDF finishes are most durable when PVDF makes up about 70% of the resin content, and that 50% and 30% formulations fall well short of the AAMA 2605 performance standard. Because the resin brand names a single ingredient rather than a finished coating, the rest of the formulation also affects performance.\n\n## Properties\n\n- Very good gloss and colour retention; PVDF paints are used on landmark buildings such as the Petronas Towers in Malaysia and Taipei 101 in Taiwan.\n- Good chemical and pollution resistance.\n\n## Use in practice\n\nPVDF finishes are widely specified in coastal and high-UV regions because they tolerate salt atmospheres and acid rain. They are applied on continuous coil coating lines over a pretreatment and primer, and baked. Field-applied PVDF products exist for restoration.\n\n## Comparison\n\nCompared with standard polyester and silicone-modified polyester (SMP) paints, PVDF generally costs more but holds colour longer. Plastisol finishes are much thicker and more abrasion resistant but are less common on roofs outside Europe.","key_facts":[{"label":"Resin","value":"Polyvinylidene fluoride (fluoropolymer)"},{"label":"Major resin brands","value":"Kynar 500 (Arkema), Hylar 5000 (Solvay)"},{"label":"Kynar 500 introduced","value":"1965"},{"label":"Main benefit","value":"Long-term colour and gloss retention"}],"regions":["Global"],"aliases":["PVDF","PVF2","Kynar 500","Hylar 5000","fluoropolymer paint","70% PVDF"],"related":["metal-roof-paint-systems","coil-coating","aluminum-roofing","cool-metal-roofing"],"company":null,"sources":[{"title":"Kynar 500 PVDF resin-based coatings","url":"https://kynar500.arkema.com/en/","publisher":"Arkema"},{"title":"Polyvinylidene fluoride","url":"https://en.wikipedia.org/wiki/Polyvinylidene_fluoride","publisher":"Wikipedia"},{"title":"Coil coating","url":"https://en.wikipedia.org/wiki/Coil_coating","publisher":"Wikipedia"},{"title":"PVDF Fact Sheet","url":"https://metalcoatings.brand.akzonobel.com/m/569077e88f104437/original/PVDF-Fact-Sheet-FINAL.pdf","publisher":"AkzoNobel"},{"title":"What Is PVDF Coating? The 70% PVDF Finish Explained","url":"https://www.interlockroofing.com/glossary/pvdf-coating/","publisher":"Interlock Roofing"}],"country":null},{"slug":"pyatthat","title":"Pyatthat","category":"world-roofing","type":"term","summary":"The multi-tiered spired roof of Burmese palaces, monasteries and pagodas, built in odd numbers of tiers, with nine reserved for the king.","body":"The *pyatthat* (Burmese: ပြာသာဒ်) is the multi-tiered roof of traditional Burmese royal and religious architecture. Its name derives from the Sanskrit *prasada*. A pyatthat is built as a series of gabled, rectangular roofs stacked one above another, diminishing toward the top, so that the whole forms an exaggerated stepped pyramid finished with a spire.\n\n## Tiers\n\nA pyatthat has an odd number of tiers, normally three to seven, with nine reserved for the king. Each tier is a *boun* (from Pali *bhumi*). Named forms include:\n\n- *yahma* - three tiers\n- *thooba* - five tiers\n- *thooyahma* - seven tiers\n\n## Components\n\n- **Roofs:** successive gabled roofs, each smaller than the one below.\n- **Lebaw:** a box-like stage between each pair of roofs.\n- **Spire:** a wooden finial, called *taing bu* or *kun bu* depending on its shape, similar to the umbrella finial (*hti*) on pagodas.\n- **Edges and corners:** tier edges carry gilded sheet-metal decoration, and corner ornaments called *du yin* play a role similar to the Thai *chofa*.\n\n## Use and meaning\n\nPyatthat crown monasteries (*kyaung*), palace buildings and pagodas, and are placed over Buddha images, royal thrones and city gates. In pre-colonial Burma the form represented Tavatimsa, a Buddhist heaven. The nine-tiered pyatthat over the main throne in the royal audience hall stood for Mount Meru, with the lower tiers representing the realms of gods and humans. The gates of royal capitals were also crowned with pyatthat.\n\nSumptuary rules limited pyatthat to royal and religious buildings and tied the number of tiers to rank: only the sovereign could have nine tiers, and rulers of important tributary states (*sawbwa*) could have seven.\n\n## History and examples\n\nThe form appears early in Burmese architecture. The Ananda Temple at Bagan, begun about 1090 and completed in 1105, has one of the earliest uses of the pyatthat; the Gawdawpalin Temple is another Bagan-period example. Later examples include:\n\n- **Mandalay Palace** (1857-1859), over its throne rooms and entrances;\n- **King Mindon's tomb**, Mandalay;\n- **Shwe In Bin Monastery** (1895), Mandalay;\n- **Yangon City Hall** (1926-1936), a colonial-era building with pyatthat roofs.\n\n## Related forms\n\nThe pyatthat belongs to the wider family of tiered sacred roofs of South and Southeast Asia, alongside the Thai temple roof, the Balinese *meru* and the East Asian pagoda roof.","key_facts":[{"label":"Tiers","value":"Odd numbers, usually 3-7; 9 for the king"},{"label":"Name origin","value":"Sanskrit prasada"},{"label":"Early example","value":"Ananda Temple, Bagan (c. 1090-1105)"},{"label":"Corner ornament","value":"Du yin (compare Thai chofa)"}],"regions":["Southeast Asia"],"aliases":["pyathat","Burmese tiered roof","prasat roof"],"related":["roofing-in-myanmar","thai-temple-roof","pagoda-roof"],"company":null,"sources":[{"title":"Pyatthat","url":"https://en.wikipedia.org/wiki/Pyatthat","publisher":"Wikipedia"},{"title":"Architecture of Myanmar","url":"https://en.wikipedia.org/wiki/Architecture_of_Myanmar","publisher":"Wikipedia"},{"title":"Ananda Temple","url":"https://en.wikipedia.org/wiki/Ananda_Temple","publisher":"Wikipedia"}],"country":null},{"slug":"pyramid-roof","title":"Pyramid, Pavilion and Tented Roofs","category":"roof-forms","type":"term","summary":"A pyramid roof is a hip roof on a square plan whose faces meet at one point; pavilion and tented roofs are low- and steep-pitched versions on regular polygons.","body":"A pyramid roof (or pyramid hip roof) is a hip roof built over a square plan, so that all four triangular faces rise to meet at a single apex with no ridge. It is the simplest roof for a square building, and is common on cottages, garden buildings, gazebos, towers and outbuildings.\n\n## Related forms\n\n- **Pavilion roof:** a low-pitched roof hipped equally on all sides over a square or regular polygonal plan, with sides rising to a peak. Often used on pavilions, summerhouses and bandstands.\n- **Tented roof:** a polygonal hipped roof with steeply pitched slopes rising to a peak, like a tent.\n- **Helm roof:** a pyramidal form with gables on each face, often found on church towers.\n- **Spire:** a very tall, slender pyramid or cone topping a tower.\n\nA notable example of a pyramid roof is The Round House in Finchingfield, Essex, England, where a chimney rises through the apex.\n\n## Advantages\n\n- Like other hip roofs, pyramid roofs are self-bracing and perform well in high winds.\n- All four sides have eaves, sheltering every wall.\n- Simple, symmetrical framing with four hip rafters meeting at a central point or king post.\n\n## Considerations\n\n- There is no ridge for continuous ridge ventilation, so roof-space ventilation needs alternatives such as a vented apex cap, hip vents or individual vents.\n- The apex, where four hips meet, needs a purpose-made cap or finial.\n- The roof volume is limited and steep pitches are required for significant attic space.","key_facts":[{"label":"Plan","value":"Square (pyramid) or regular polygon"},{"label":"Ridge","value":"None, faces meet at apex"},{"label":"Steep version","value":"Tented roof"}],"regions":["Global"],"aliases":["pyramid hip roof","pavilion roof","tented roof","tent roof","helm roof"],"related":["hip-roof","conical-roof","roof-hip","gable-roof"],"company":null,"sources":[{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"},{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"},{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"}],"country":null},{"category":"world-roofing","type":"article","company":null,"slug":"qarmaq","title":"Qarmaq","summary":"Inuit transitional-season house with low walls of snow, stone or sod, a whalebone frame and a roof of skins or canvas, used into the 1950s.","body":"A qarmaq (Inuktitut; plural *qarmat*) is a single-room family dwelling used by the Inuit and their Thule predecessors between the seasons of tent and snow house. Among the Central Inuit of northern Canada the word describes a hybrid of tent and igloo or of tent and sod house; in Greenland (Kalaallisut) it refers to the dwelling's wall.\n\n## Construction\n\n- **Walls**: low walls of snow blocks in winter, or of stone or sod in other seasons.\n- **Frame**: usually animal bone, preferably whalebone, because timber was scarce in the Arctic.\n- **Roof**: skins prepared for roofing and siding, later replaced by canvas, stretched over the frame.\n- **Insulation**: tundra moss packed into crevices; after snowfall, snow blocks could be set around the outside for extra protection.\n- **Interior**: a slightly raised sleeping platform padded with caribou skin, heated only by the flame of a *qulliq*, a stone oil lamp.\n\nBuilding was shared: men gathered boulders, assembled the frame and later cut snow blocks, while women and children gathered moss and prepared skins. Women also repaired the outer covering when weather or animals such as wolves and foxes damaged it. Sites were chosen with attention to local ground and weather.\n\n## Seasonal use\n\nQarmat were built in autumn and spring. Summer tents, easy to move, gave way to sod qarmat in autumn. In winter people also lived in snow houses, especially while travelling, but qarmat were preferred where possible. The snow house itself (*iglu*, or *igluvijaq* in some dialects) was mainly a Central Arctic and Qaanaaq-area form; other Inuit chiefly used snow to insulate houses of whalebone and hide.\n\n## History\n\nThe Thule people used qarmat, mainly in the cold season, and Inuit continued to use them up to the 1950s.\n\n## Significance for roofing\n\nThe qarmaq shows how a roof can be made where there is no timber: a bone frame, a waterproof skin membrane and packed insulation, a combination that parallels the layered logic of modern roof assemblies.","key_facts":[{"label":"Region","value":"Canadian Arctic; Greenland"},{"label":"Frame","value":"Whalebone or other bone"},{"label":"Roof","value":"Skins, later canvas, with moss insulation"},{"label":"Season","value":"Autumn and spring"},{"label":"In use until","value":"1950s"}],"regions":["Arctic","North America"],"aliases":["Qarmat","Karmak","Inuit sod house"],"related":["roofing-in-canada","sod-roof","scandinavian-sod-roofs"],"sources":[{"title":"Qarmaq","url":"https://en.wikipedia.org/wiki/Qarmaq","publisher":"Wikipedia"},{"title":"Igloo","url":"https://en.wikipedia.org/wiki/Igloo","publisher":"Wikipedia"}],"country":null},{"slug":"queen-post-truss","title":"Queen Post Truss","category":"components","type":"term","summary":"A queen post truss is a roof frame with two vertical posts set either side of centre on the tie beam, linked at the top by a straining beam.","body":"A queen post truss is a timber roof frame in which two vertical posts, the queen posts, stand on the tie beam at equal distances either side of the centre. Their tops are joined by a horizontal straining beam (or collar), and the sloping principal rafters run from the wall plates past the heads of the posts toward the apex. The arrangement leaves an open rectangular space in the middle of the truss.\n\n## How it differs from a king post truss\n\nA king post truss has one central post; the queen post version replaces it with two. The posts typically support purlins, and the straining beam keeps the post heads apart. Because the middle section relies partly on bending in the horizontal member, the basic queen post truss is generally suited to modest spans, though historic builders used it for larger roofs than a simple king post could cover.\n\nThe open centre made queen post roofs useful where attic space or headroom was wanted, and the form appears widely in British and North American timber buildings, barns and churches.\n\n## Historic terminology\n\nIn British historic building records, a queen post is described as working like a crown post but set in pairs, spaced equally away from the centre. Heritage thesauri record \"queen post truss\" as a distinct roof type for classification of historic buildings.\n\n## Modern use\n\nQueen post forms survive in modern timber framing, exposed trusses in great rooms and porches, and some prefabricated trusses. Like all trusses, they should not have members cut or removed without engineering advice.","key_facts":[{"label":"Posts","value":"Two, symmetric about centre"},{"label":"Top member","value":"Straining beam or collar"},{"label":"Advantage","value":"Open central space"}],"regions":["Global","Europe","North America"],"aliases":["queenpost truss","queen-post roof"],"related":["king-post-truss","roof-truss","purlin","collar-tie"],"company":null,"sources":[{"title":"Queen post","url":"https://treeterms.co.uk/definitions/queen-post/","publisher":"Tree Terms"},{"title":"Thesaurus Term: QUEEN POST TRUSS","url":"https://her.aberdeenshire.gov.uk/ThesaurusTerm/138141","publisher":"Aberdeenshire Council HER"},{"title":"Truss","url":"https://en.wikipedia.org/wiki/Truss","publisher":"Wikipedia"},{"title":"Roof glossary","url":"https://www.mkheritage.org.uk/wdahs/Thornton/docs/roofglossary.html","publisher":"Milton Keynes Heritage Association"}],"country":null},{"slug":"queenslander","title":"Queenslander","type":"article","summary":"Timber house type of Queensland, Australia, raised on stumps with verandahs and a corrugated iron roof, built from the 1840s.","body":"The Queenslander is a style of detached house that developed in Queensland, Australia, from the 1840s and is still built in modified form. It is a timber house raised on stumps, wrapped by verandahs and covered by a steeply pitched corrugated iron roof. Its \"tin and timber\" character defines older suburbs of Brisbane and many regional towns.\n\n## Roof\n\nCorrugated steel (commonly called corrugated iron) is the most characteristic roof covering. It suits the climate because it handles heavy subtropical rain well, is light enough for timber framing, and can be refixed or reused after cyclone damage. Roofs were traditionally steeply pitched and often gabled, with separate, lower roofs over the verandahs.\n\nVentilation was built into the roof and ceilings. Fanlights over doors, decorative ceiling roses and aligned doors and windows encouraged airflow, and rotating roof ventilators (\"whirlybirds\") were added to draw hot air from the roof space. Analysis has found that these passive measures work best only in certain northern conditions and that some Queenslanders can be hotter inside than expected.\n\n## Raised floors and verandahs\n\nHouses stand on stumps, originally timber, whose height varies with the slope of the site. Raising the floor helps with flooding, termites and uneven ground and allows air beneath the house. Verandahs run partly or fully around the house and serve as living space; many were later enclosed to add rooms.\n\n## Development\n\nTimber became the dominant building material in Queensland after 1900. Kit homes \"ready to erect\" appeared around 1915, and standardised designs spread in the 1920s and 1930s. The style fell out of favour after the Second World War, when brick veneer houses became more common.\n\n## Context\n\nCorrugated galvanised iron, patented in Britain in 1829, became common in Australia from the 1840s and remains a widespread roofing material in the country, including in cities. The Queenslander is its best-known domestic expression.\n\n## Heritage\n\nMany older houses have been demolished, especially in inner Brisbane, prompting local councils to introduce character and conservation controls. Some houses are lifted and relocated rather than demolished.","key_facts":[{"label":"Region","value":"Queensland, Australia"},{"label":"Period","value":"From the 1840s"},{"label":"Roof covering","value":"Corrugated iron (steel)"},{"label":"Structure","value":"Timber, raised on stumps"},{"label":"Climate","value":"Subtropical, high rainfall"}],"regions":["Oceania"],"aliases":["Queenslander house","Tin and timber house"],"related":["roofing-in-australia","corrugated-iron"],"sources":[{"title":"Queenslander (architecture)","url":"https://en.wikipedia.org/wiki/Queenslander_(architecture)","publisher":"Wikipedia"},{"title":"Corrugated galvanised iron","url":"https://en.wikipedia.org/wiki/Corrugated_galvanised_iron","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"quincha","title":"Quincha","category":"world-roofing","type":"term","summary":"Earthquake-resistant building system of timber frames filled with cane and mud, used in Peru and Ecuador, often carrying light earth-covered roofs.","body":"*Quincha* (also *quinche*) is a building technique of the Pacific coast of South America in which a timber frame of posts and beams is filled with cane or reed woven together and plastered with mud. It is closely related to the *bahareque* or wattle-and-daub construction of Central America and Colombia. Because it is light and flexible, quincha has a reputation for good behaviour in earthquakes.\n\n## Lima\n\nIn Lima, colonial houses were at first built of adobe or fired brick, often two storeys high. After strong earthquakes in the 16th and 17th centuries, the viceroy, the Conde de la Monclova, ordered in 1699 that upper floors be rebuilt in the lighter quincha system. As a result, many historic buildings in the centre of Lima have an adobe ground floor carrying quincha upper storeys, and quincha remained in use after independence because of its good performance in earthquakes. The Historic Centre of Lima was inscribed on the UNESCO World Heritage List in 1988.\n\n## Roofs and floors\n\nA paper by Daniel Torrealva and Erika Vicente of the Pontifical Catholic University of Peru, presented at the 15th World Conference on Earthquake Engineering in 2012, describes the roofs of these buildings: timber rafters are nailed to the top beams of the quincha walls, boards are laid over the rafters, and a layer of soil goes on top. Earth-covered, nearly flat roofs of this kind suit Lima's dry coastal climate. Peru's 2017 census still records \"cane or reed matting with a mud or cement layer\" (*caña o estera con torta de barro o cemento*) as the main roof of 3.4% of occupied dwellings.\n\nThe same authors tested twelve full-scale quincha walls modelled on the three-storey Hotel Comercio in Lima under cyclic horizontal loading. The walls reached large drifts without collapse, and the authors concluded that their seismic behaviour was excellent.\n\n## Ecuador\n\nOn the coast of Ecuador, cane (*caña guadúa*) and mud plaster, called *quinche* or quincha, has been used since pre-Columbian times. Research at the Universidad Laica Eloy Alfaro de Manabí documents houses on stilts, *montubio* rural houses of cane and quinche, and timber, cane and quinche mansions in Guayaquil (18th century) and Portoviejo (19th century).","key_facts":[{"label":"Construction","value":"Timber frame filled with cane and mud plaster"},{"label":"Main region","value":"Coastal Peru and Ecuador"},{"label":"Lima decree","value":"1699, upper floors to be rebuilt in quincha"},{"label":"Typical roof","value":"Rafters, boards and a layer of soil"},{"label":"Census category (Peru 2017)","value":"Cane or matting with mud: 3.4% of roofs"}],"regions":["Latin America"],"aliases":["quinche","caña y barro","bahareque (related)"],"related":["roofing-in-peru","roofing-in-ecuador","flat-roof","mud-roof"],"company":null,"sources":[{"title":"Experimental evaluation of seismic behavior of quincha walls from the Historical Centre of Lima - Peru (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_3170.pdf","publisher":"15th World Conference on Earthquake Engineering"},{"title":"En el país existen más de diez millones de viviendas particulares censadas","url":"https://m.inei.gob.pe/prensa/noticias/en-el-pais-existen-mas-de-diez-millones-de-viviendas-particulares-censadas-10893/","publisher":"INEI Perú"},{"title":"Propuestas constructivas sostenibles: la caña guadúa y los BTC de terro-cemento","url":"https://grupotierra.uva.es/aecid/publicaciones/2013/6d.pdf","publisher":"Grupo TIERRA, Universidad de Valladolid / ULEAM"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"}],"country":null},{"slug":"rafter","title":"Rafter","category":"components","type":"term","summary":"A rafter is a sloping structural member that runs from the ridge or hip down to the wall plate and carries the roof deck and covering.","body":"A rafter is one of the inclined timbers (or steel or engineered-wood members) that form the sloping planes of a pitched roof. Each rafter runs from the top of the roof, at a ridge or hip, down to the wall plate at the eaves, and together the rafters carry the sheathing or battens, the roof covering, and loads such as snow and wind. A matched pair of rafters meeting at the top is traditionally called a couple.\n\nRafters are cut and installed on site, which distinguishes a \"stick-framed\" or \"cut\" roof from one built with factory-made trusses. In houses they are usually softwood.\n\n## Types of rafter\n\n- **Common rafter:** the ordinary, full-length rafter repeated along the roof. In historic \"double\" roofs it is lighter than the principal rafters that carry the purlins.\n- **Principal rafter:** a heavier rafter, usually part of a truss, that supports purlins, which in turn support common rafters.\n- **Hip rafter:** runs diagonally at the external corner where two roof slopes meet in a hip.\n- **Valley rafter:** runs diagonally along an internal corner where two slopes meet in a valley.\n- **Jack rafter:** a shortened rafter that ends on a hip or valley rafter, or is cut short by an opening such as a dormer.\n\n## Thrust and restraint\n\nA pair of rafters loaded from above tends to push the tops of the walls outward. In the simplest historic roofs a tie beam across the bottom of the rafters resists that spread; in modern houses ceiling joists or rafter ties usually do the same job. A collar higher up can stiffen the pair. Where neither is present, a structural ridge beam must carry the upper ends of the rafters instead.\n\n## Historical and regional notes\n\nThe earliest surviving European roofs use common rafters on a tie beam, an assembly known as a closed couple. A short extra piece at the foot of a rafter, used to create a kick in the eaves or change the pitch, is called a sprocket in British usage (coyau in French). Part of a cruck frame that acts as a rafter is called a cruck blade.\n\nHistorically, many rafters tapered toward the top, a practice period writers argued saved timber.","key_facts":[{"label":"Runs between","value":"Ridge or hip and wall plate"},{"label":"Pair name","value":"Couple"},{"label":"Variants","value":"Common, principal, hip, valley, jack"}],"regions":["Global"],"aliases":["roof rafter","common rafter"],"related":["roof-truss","purlin","ridge-board","collar-tie","roof-hip","roof-valley"],"company":null,"sources":[{"title":"Rafter","url":"https://en.wikipedia.org/wiki/Rafter","publisher":"Wikipedia"},{"title":"Roof glossary","url":"https://www.mkheritage.org.uk/wdahs/Thornton/docs/roofglossary.html","publisher":"Milton Keynes Heritage Association"},{"title":"Collar beam","url":"https://en.wikipedia.org/wiki/Collar_beam","publisher":"Wikipedia"}],"country":null},{"slug":"rain-chain","title":"Rain Chain","category":"components","type":"term","summary":"A rain chain is a chain or series of linked cups hung from a gutter outlet that guides rainwater to the ground as a decorative alternative to a downspout.","body":"A rain chain is a length of chain, or a string of open-bottomed cups, hung from a gutter outlet in place of a closed downspout. Rainwater clings to and runs down the chain or drops from cup to cup, turning runoff into a visible and audible water feature. The water is typically received by a basin, gravel bed, drain or storage container at the base.\n\n## Origin\n\nRain chains are long established in Japan, where they are called kusari-doi (also romanised kusari-toi), meaning chain gutter. They are a familiar feature on Japanese temples and houses. Scandinavian vernacular architecture used a comparable idea, a simple stick or pole guiding water from the roof. Modernist architects in the 20th century also used chains to contrast with concrete or stone facades.\n\n## Types\n\n- **Link chains:** a series of open links, sometimes of shaped or decorative form; water clings to the chain as it runs down.\n- **Cup chains:** a series of small cups, each with a hole in its base, chained together so water fills and overflows from one to the next. Cup chains usually handle more water with less splashing than plain links.\n\nCopper, brass, aluminium and steel are common materials; copper weathers to a brown and eventually green patina.\n\n## Practical considerations\n\n- Rain chains handle less flow and splash more than a closed downspout, so they suit smaller roofs, sheltered locations or as one of several outlets.\n- The bottom of the chain is usually anchored to prevent swinging in the wind.\n- In cold climates, ice can build up on the chain, adding weight to the gutter; fixing points should be strong enough.\n- Ground at the base should drain away from the foundation.","key_facts":[{"label":"Japanese name","value":"Kusari-doi (chain gutter)"},{"label":"Types","value":"Link chains, cup chains"},{"label":"Common metals","value":"Copper, brass, aluminium, steel"}],"regions":["East Asia","Global"],"aliases":["kusari-doi","kusari-toi","rain chains"],"related":["downspout","rain-gutter"],"company":null,"sources":[{"title":"Rain chain","url":"https://en.wikipedia.org/wiki/Rain_chain","publisher":"Wikipedia"},{"title":"Rain gutter","url":"https://en.wikipedia.org/wiki/Rain_gutter","publisher":"Wikipedia"}],"country":null},{"slug":"rain-gutter","title":"Rain Gutter","category":"components","type":"article","summary":"A rain gutter is a channel fixed along the eaves that collects water running off the roof and carries it to downspouts, protecting walls and foundations.","body":"A rain gutter is an open channel fixed along the lower edge of a roof to collect runoff and carry it to downspouts (downpipes), which take the water to the ground, a drain or a storage tank. Gutters protect walls, windows and foundations from saturation, reduce erosion around the building, and allow rainwater harvesting.\n\n## Regional names\n\nGutters go by many names: eavestrough in Canada, guttering in Britain, spouting in New Zealand, rhone or rone in Scotland and eaves-shoot in Ireland.\n\n## Profiles\n\n- **K-style (ogee or fascia style):** a flat back and decorative curved front that resembles crown moulding; the dominant residential profile in North America. The ogee was also the standard Victorian gutter in Britain.\n- **Half-round:** a semicircular trough, traditional in Europe and on older or heritage buildings, usually hung on brackets.\n- **Box gutter:** a rectangular gutter, either fixed to the fascia or built into the roof structure behind a parapet or between roof slopes, as in M-shaped roofs. Concealed box gutters need a waterproof lining and generous overflow provisions because a blockage can send water into the building.\n- **Square-line and other profiles** are also used.\n\n## Materials\n\nMaterials have included cast iron, asbestos cement, wood, copper, zinc, galvanised and stainless steel, aluminium and uPVC. In North America, seamless aluminium gutters roll-formed on site to the length of the run are common, avoiding joints.\n\n## Sizing and fall\n\nGutter size depends on roof area and local rainfall intensity. One rule of thumb cited for residential work is a 100 mm (4 in) gutter with a single 68 mm downpipe for about 56 m² (600 sq ft) of roof; codes and manufacturers provide detailed tables. Gutters are laid with a slight fall toward outlets; one British guideline gives a minimum of 1 in 360.\n\n## History\n\nThe Romans brought rainwater systems to Britain; the technology was later lost and reintroduced by the Normans.\n\n## Maintenance\n\nLeaves and debris are the main cause of overflow. Gutter guards, regular cleaning, and adequate fixings to resist snow and ice loads all extend service life.","key_facts":[{"label":"Canadian term","value":"Eavestrough"},{"label":"Main profiles","value":"K-style, half-round, box"},{"label":"Rule of thumb","value":"100 mm gutter per about 56 m² (600 sq ft) roof"},{"label":"Minimum fall (UK guide)","value":"1 in 360"}],"regions":["Global"],"aliases":["gutter","eavestrough","guttering","spouting","rhone"],"related":["downspout","rain-chain","fascia","eaves","drip-edge"],"company":null,"sources":[{"title":"Rain gutter","url":"https://en.wikipedia.org/wiki/Rain_gutter","publisher":"Wikipedia"},{"title":"Eaves","url":"https://en.wikipedia.org/wiki/Eaves","publisher":"Wikipedia"}],"country":null},{"slug":"rainwater-harvesting-roofs","title":"Rainwater Harvesting from Roofs","type":"article","summary":"Collecting rain that falls on a roof for storage and reuse, and how the roof material affects the quality of the collected water.","body":"Rainwater harvesting from roofs means collecting the water that runs off a roof, usually through gutters and downspouts, and storing it in tanks or cisterns for later use. It is practised worldwide, from rural households that depend on it for drinking water to urban buildings that use it for irrigation and toilet flushing.\n\n## How much water a roof yields\n\nIn theory, 1 mm of rain on 1 m² of roof yields about 1 litre. The Texas Water Development Board's rainwater manual gives the equivalent of about 0.62 US gallons per square foot of roof per inch of rain, and notes that installers typically assume 75-90 percent collection efficiency to account for splash, evaporation and first-flush diversion.\n\n## Roof material suitability\n\nThe roof surface is the first stage of water treatment, so its material matters, especially where water will be used for drinking. The Texas manual's guidance includes:\n\n- **Metal:** recommended; plain galvanized roofing or metal with epoxy or latex paint is suitable for potable systems, and Galvalume is commonly used. Copper flashings can discolour fixtures.\n- **Clay and concrete tile:** usable for potable or non-potable systems but porous, losing roughly 10 percent of water; a suitable sealant or paint helps prevent bacterial growth.\n- **Slate:** ideal for potable use if no toxic sealant is applied, though cost often rules it out.\n- **Asphalt or composite shingles:** not advised for potable systems because compounds can leach into the water; acceptable for irrigation.\n- **Wood shingles and shakes:** usually suitable only for irrigation because of leaching.\n\nCoatings, sealants, moss treatments and lead flashings can also affect water quality.\n\n## First flush and filtration\n\nThe first rain after a dry spell carries the most dust, bird droppings, leaves and other contaminants. First-flush diverters discard this water. One rule of thumb in the Texas manual is to divert at least about 38 litres per 93 m² (10 US gallons per 1,000 sq ft) of roof. Gutter screens, prefilters and drawing water from a floating outlet improve quality. Water for drinking needs treatment, such as filtration and disinfection.\n\n## Where it is promoted or required\n\nTamil Nadu in India made rooftop rainwater harvesting compulsory for buildings in 2001, and Mumbai required it for large new buildings from 2002. Bermuda requires it for new construction, it is widespread in rural New Zealand and Australia, roughly 40 percent of Thailand's rural population relies on it, and Santa Fe, New Mexico requires it for new dwellings.\n\n## Maintenance\n\nGutters and screens need regular cleaning, tanks should be sealed against mosquitoes and light, and roofs should be kept free of overhanging branches.","key_facts":[{"label":"Yield","value":"About 1 L per m² per mm of rain (0.62 US gal per ft² per inch)"},{"label":"Collection efficiency","value":"Typically 75-90%"},{"label":"Best potable surfaces","value":"Metal, slate, sealed tile"},{"label":"First-flush rule of thumb","value":"About 10 US gal per 1,000 ft² of roof"}],"regions":["Global","South Asia","Oceania","Southeast Asia","Africa","North America"],"aliases":["roof rainwater collection","rainwater catchment","roof catchment"],"related":["roof-drainage-design","blue-roof","metal-roofing","rain-gutter"],"sources":[{"title":"The Texas Manual on Rainwater Harvesting, Third Edition","url":"https://www.twdb.texas.gov/publications/brochures/conservation/doc/RainwaterHarvestingManual_3rdedition.pdf","publisher":"Texas Water Development Board"},{"title":"Rainwater harvesting","url":"https://en.wikipedia.org/wiki/Rainwater_harvesting","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roof-rake","title":"Rake and Verge","category":"components","type":"term","summary":"The rake (US) or verge (UK) is the sloping edge of a roof at a gable end, running from the eaves up to the ridge.","body":"The rake is the inclined edge of a pitched roof where it passes over a gable end wall, running from the eaves corner up to the ridge. In British, Irish and Australian usage the same edge is called the verge. Each simple gable roof has two rakes (or verges), one on each side of each gable.\n\n## Rake versus eave\n\nEaves are the horizontal lower edges of the roof, where water runs off. Rakes are sloping, so water does not flow over them; instead the main risks are wind uplift, which is often highest at roof edges and corners, and wind-driven rain being blown sideways under the covering.\n\n## Detailing in North America\n\n- A rake overhang is created by projecting the roof sheathing and framing past the gable wall, often using lookouts or a ladder-framed fly rafter.\n- The exposed edge is trimmed with a rake board or fascia, and in decorative work a bargeboard.\n- Drip edge is required at rakes on asphalt shingle roofs under the IRC; at the rake it is installed over the underlayment.\n- Starter shingles or adhesive along the rake help resist wind uplift.\n\n## Detailing in the UK (verges)\n\n- Traditional verges are bedded in mortar on an undercloak of slate or fibre-cement strip, with the tiles or slates overhanging the gable wall slightly.\n- Modern practice has moved toward mechanically fixed dry verge systems, plastic or metal caps clipped to the batten ends, because mortar-bedded verges are prone to cracking and wind damage.\n- Bargeboards are used where the roof oversails the gable.\n\n## Terminology notes\n\n\"Rake\" can also describe the pitch of the edge itself, and \"raking\" is used for any inclined line in a building. The board along a verge in older houses is called the verge board or bargeboard.","key_facts":[{"label":"US term","value":"Rake"},{"label":"UK/AU term","value":"Verge"},{"label":"Main risk","value":"Wind uplift and wind-driven rain"}],"regions":["Global"],"aliases":["rake edge","verge","gable edge","roof verge"],"related":["eaves","bargeboard","drip-edge","fascia","gable-roof"],"company":null,"sources":[{"title":"Eaves","url":"https://en.wikipedia.org/wiki/Eaves","publisher":"Wikipedia"},{"title":"Roof drip edge code (IRC 2021 R905.2.8.5)","url":"https://www.jaspector.com/codes/irc-2021/ch09-roof-assemblies/roof-drip-edge-code/","publisher":"Jaspector"},{"title":"All About Roof Flashing","url":"https://www.greenbuildingadvisor.com/article/all-about-roof-flashing","publisher":"Green Building Advisor"}],"country":null},{"slug":"ramesseum-granary-vaults","title":"Ramesseum Granary Vaults","category":"history","type":"place","summary":"Mud-brick barrel-vaulted storerooms at the Ramesseum in Luxor, built under Ramesses II in the 13th century BC; among Egypt's oldest standing true arches.","body":"The storerooms of the Ramesseum, the mortuary temple of Pharaoh Ramesses II on the west bank of the Nile opposite Luxor, are a rare survival of ancient Egyptian mud-brick vaulting. Built in the 13th century BC, they show that Egyptian builders could roof long, narrow rooms with true arches of sun-dried brick, without stone and with very little timber.\n\n## Layout\n\nThe storerooms and granaries wrap around the temple on three sides, arranged in three groups. The oldest group lies behind the temple. In that group each storeroom is about 32 m (105 ft) long, 3.7 m (12.1 ft) wide and 3.5 m (11.5 ft) high, with lower walls about 1.5 m (4.9 ft) thick.\n\n## Construction\n\nEach room is roofed with a barrel vault. The vault springs from about 2.5 m (8.2 ft) above the floor and is built of four rings (courses) of mud bricks measuring about 40 x 20 x 12-14 cm (15.7 x 7.9 x 4.7-5.5 in). The bricks are ordinary rectangular bricks rather than wedge-shaped voussoirs, so the arch depends on its mortar joints. Arches of this kind are prone to collapse, which is why few survive. The Ramesseum examples, dated to about 1300 BC, are cited as the oldest such arch still standing in Egypt.\n\n## Significance\n\nThe vaults are an early, well-dated example of a roofing method that continued along the Nile for more than three thousand years. Mud-brick vaults built without centring remained the standard roof of Nubian villages into the 20th century, and the Egyptian architect Hassan Fathy revived them in the 1940s (see Nubian vault). The Ramesseum vaults show that the basic idea of roofing with earth alone, where timber is scarce, was already mature in the New Kingdom.\n\n## Conservation\n\nMud brick survives at the Ramesseum mainly because of the dry climate of Upper Egypt. Conservation studies of Egypt's adobe barrel vaults treat these storerooms as a key case for understanding how such structures behave and fail over time.","key_facts":[{"label":"Date","value":"13th century BC (reign of Ramesses II), c. 1300 BC"},{"label":"Location","value":"West bank of the Nile, opposite Luxor"},{"label":"Room size (oldest group)","value":"About 32 x 3.7 m (105 x 12.1 ft), 3.5 m (11.5 ft) high"},{"label":"Vault","value":"Four courses of 40 x 20 x 12-14 cm mud bricks"}],"regions":["Africa","Middle East"],"aliases":["Ramesseum storerooms","Ramesseum vaults","Ramesseum granaries"],"related":["roofing-in-egypt","nubian-vault","barrel-vault-roof","mud-roof","history-of-roofing","hassan-fathy"],"company":null,"sources":[{"title":"Ramesseum","url":"https://en.wikipedia.org/wiki/Ramesseum","publisher":"Wikipedia"},{"title":"The adobe barrel vaulted structures in Ancient Egypt: a study of two case studies for conservation purposes","url":"https://grissh.gr/article/58affcd8557441a75300002d","publisher":"Mediterranean Archaeology and Archaeometry"},{"title":"Ancient Egyptian architecture","url":"https://en.wikipedia.org/wiki/Ancient_Egyptian_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"rammed-earth","title":"Rammed Earth","category":"materials","type":"article","summary":"Walls made by compacting damp earth in layers inside formwork; durable when protected by large roof overhangs and a dry base.","body":"Rammed earth (French pisé de terre, Chinese hangtu) is a building technique in which damp subsoil, a mix of sand, gravel, clay and silt, sometimes with a stabiliser, is compacted in layers inside temporary formwork to form solid walls. It is a walling rather than a roofing material, but rammed earth buildings depend heavily on their roofs for protection, and the roof structure must be designed to sit on and be fixed to earth walls.\n\n## Construction\n\n- **Layers:** loose mix is placed 10-25 cm (4-10 in) deep and compacted to about half its volume; UK guidance cites finished lifts of 100-150 mm (4-6 in).\n- **Formwork:** historically timber planks tied with rope; today plywood, steel or both. Walls are strong enough to strip quickly after compaction.\n- **Thickness:** non-load-bearing walls can be as thin as 150 mm (6 in) and load-bearing walls up to about 600 mm (24 in). UK guidance gives 300 mm (12 in) as a minimum for lateral stability.\n- **Stabilised rammed earth:** adding cement gives strengths of about 5-18 MPa (700-3,000 psi), and higher in some Australian practice, at the cost of lower permeability and the carbon emissions of cement.\n\n## History\n\nRammed earth was in use in the Fertile Crescent by the 9th-7th millennium BCE, and by the Yangshao and Longshan cultures of China by about 5000 BCE. By 2000 BCE it was common in China for walls and foundations. It was widespread in parts of Europe, especially France, Spain and Germany, and was popularised in the United States in the early 19th century.\n\n## Roofs on rammed earth buildings\n\nRammed earth decays when exposed to water, so the roof is its main defence:\n\n- **Overhangs:** large roof overhangs at eaves and verges reduce wetting of the wall faces.\n- **Bond beams:** a continuous beam of timber or reinforced concrete on top of the wall spreads roof loads and gives a fixing for rafters or joists. New Mexico's Earthen Building Materials Code, for example, specifies that a concrete bond beam be tied into the uncured wall with No. 4 reinforcing bars at no more than 24 in (610 mm) centres, and that a timber bond beam be fixed with 1/2 in (13 mm) hooked anchor bolts rammed at least 18 in (457 mm) into the wall.\n- **Roof types:** earth walls carry both flat earth roofs in dry regions and pitched tiled roofs, as on the rammed-earth tulou of Fujian, China.\n\n## Performance\n\nLike brick and concrete, rammed earth has high thermal mass: heat takes about 12 hours to pass through a 35 cm (14 in) wall, moderating day-night temperature swings. In cold climates insulation can be built into the wall. Fire resistance of around 30 minutes is readily achieved, provided the wall stays dry and stable. Flood-prone sites are generally unsuitable.","key_facts":[{"label":"Other names","value":"Pise de terre, hangtu, pise"},{"label":"Lift depth","value":"Placed 10-25 cm (4-10 in), compacted to about half"},{"label":"Wall thickness","value":"150-600 mm (6-24 in)"},{"label":"Earliest use","value":"Fertile Crescent, 9th-7th millennium BCE"},{"label":"Key roof detail","value":"Large overhangs and a bond beam"}],"regions":["Global"],"aliases":["pise","pise de terre","hangtu","stabilised rammed earth"],"related":["mud-roof","fujian-tulou-roofs","eaves","djenne-earthen-architecture"],"company":null,"sources":[{"title":"Rammed earth","url":"https://en.wikipedia.org/wiki/Rammed_earth","publisher":"Wikipedia"},{"title":"Technical update: bricks and rammed earth","url":"https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/labcw-tech-update-bricks-rammed-earth.pdf","publisher":"LABC Warranty"},{"title":"14.7.4.16 NMAC Attachments and Connections (New Mexico Earthen Building Materials Code)","url":"https://regulations.justia.com/states/new-mexico/title-14/chapter-7/part-4/section-14-7-4-16","publisher":"Justia / State of New Mexico"}],"country":null},{"slug":"raupo-houses-ordinance","title":"Raupo Houses Ordinance","category":"history","type":"standard","summary":"New Zealand’s first building law (1842), which taxed raupō and thatched buildings in towns to reduce fire risk.","body":"The Raupo Houses Ordinance, sometimes called the Raupo Houses Act, was made on 3 March 1842 and is regarded as New Zealand's first building legislation. It targeted the fire risk of houses built from *raupō* (bulrush) and other plant materials, which were cheap and quick to build, resembled traditional Māori housing, and burned easily.\n\n## What it did\n\nThe ordinance allowed the governor to proclaim it in any town, or part of a town, where it was needed to reduce fire risk. Where it applied, it imposed an annual tax of £20 on buildings made wholly or partly of raupō, nīkau, toetoe, wīwī, kākaho, straw or thatch, and a fine of £100 for building such a house after the ordinance took effect.\n\n## Where it applied\n\n- **Auckland**: proclaimed in May 1842.\n- **Wellington**: on 9 November 1842 a fire that began in a thatched raupō bakehouse spread in a north-west wind and destroyed about 57 buildings, including all of Kumutoto Pā. The town council asked for the ordinance, which took effect on 30 March 1843.\n- **Dunedin and Port Chalmers** (February 1850), **Lyttelton** (1850), **Christchurch** (1852) and **New Plymouth** (1857). In New Plymouth a gale destroyed many thatched houses before the ordinance took effect, and in 1858 a new Thatch and Straw Building Ordinance reduced the fine to £20.\n\nRaupō dwellings in the Wellington pā at Pipitea and Te Aro were not taxed, and Kawau Pā in New Plymouth was initially exempt.\n\n## Effect on roofing\n\nThe ordinance was not aimed at Māori, and most Māori housing lay outside its reach. Raupō remained common for some time: an 1849 census of the Auckland area found it made up almost a third of European housing, with Howick having 180 raupō houses and 50 weatherboard houses. From the late 1850s the share fell as sawn timber, brick and stone became more available, and by 1878 only 0.55% of non-Māori dwellings nationwide were raupō. In the same period, timber shakes and shingles and then corrugated iron took over as the main roof coverings. The ordinance was repealed in 1878 under the Repeals Act.\n\n## Significance\n\nThe law is an early example of fire-driven roofing regulation, comparable to earlier restrictions on thatch in European towns and to the later outlawing of timber shingles in New Zealand towns.","key_facts":[{"label":"Made","value":"3 March 1842"},{"label":"Country","value":"New Zealand"},{"label":"Tax","value":"£20 a year on raupō or thatched buildings"},{"label":"Fine","value":"£100 for new construction"},{"label":"Repealed","value":"1878"}],"regions":["Oceania"],"aliases":["Raupo Houses Act","Raupō Houses Ordinance 1842"],"related":["roofing-in-new-zealand","thatch","wood-shingle","corrugated-iron","wharenui","history-of-thatch-in-britain"],"company":null,"sources":[{"title":"Raupo Houses Ordinance","url":"https://en.wikipedia.org/wiki/Raupo_Houses_Ordinance","publisher":"Wikipedia"},{"title":"Building materials - Māori and early settler materials","url":"https://teara.govt.nz/en/building-materials/page-1","publisher":"Te Ara - The Encyclopedia of New Zealand"},{"title":"Architecture of New Zealand","url":"https://en.wikipedia.org/wiki/Architecture_of_New_Zealand","publisher":"Wikipedia"}],"country":null},{"slug":"ravinala-thatch","title":"Ravinala Thatch","category":"world-roofing","type":"term","summary":"Roofing of Madagascar's east coast made from the fronds of the traveller's palm (ravinala), whose flattened trunks also supply boards for floors and roofs.","body":"Ravinala thatch is the traditional roof covering of eastern Madagascar, made from the large fronds of the traveller's palm (*Ravenala madagascariensis*, Malagasy *ravinala*). The plant is so useful for building that on the east coast both the roof and much of the house can come from it: the fronds give thatch, and the trunks are pounded flat into planks for floors and roofs.\n\n## Houses\n\nEast coast houses are typically low, rectangular and raised on stilts, with a steep peaked gable roof and slightly overhanging eaves that throw rain clear of the foundations. The largest are found in the south-east among the Antemoro, Tanala and Antefasy, reaching about 5.5 m (18 ft) long, 2.7 m (9 ft) wide and 4.6 m (15 ft) high; elsewhere on the coast they average about 3 m by 2.4 m by 2.7 m (10 by 8 by 9 ft).\n\n## Other plant roofs in Madagascar\n\n- **Raffia palm** replaces ravinala in the north.\n- **Palms** are used in the west around Mahajanga.\n- **Rushes** are used in the south-west around Toliara.\n- **Reeds** are used near rivers, and grasses are used almost everywhere.\n- **Rice straw** thatched houses in Antananarivo until fired clay roof tiles, introduced by Jean Laborde in 1831, began to replace it.\n\n## Current use\n\nIn the unweighted 2018 Multiple Indicator Cluster Survey sample, thatch or palm leaf, grass bundles and palm, bamboo or *zozoro* together made up over three-fifths of recorded roofs, more than metal sheet. Plant roofs therefore remain the majority roof covering in Madagascar.","key_facts":[{"label":"Plant","value":"Traveller's palm (Ravenala madagascariensis)"},{"label":"Region","value":"East coast of Madagascar"},{"label":"Uses","value":"Fronds for thatch, flattened trunks for boards"},{"label":"Northern substitute","value":"Raffia palm"}],"regions":["Africa"],"aliases":["traveller's palm thatch","ravenala roof","traveler's palm roof"],"related":["roofing-in-madagascar","palm-thatch","thatch","tandrotrano"],"company":null,"sources":[{"title":"Architecture of Madagascar","url":"https://en.wikipedia.org/wiki/Architecture_of_Madagascar","publisher":"Wikipedia"},{"title":"MICS 2018 Madagascar: Materiau principal du toit (HC5)","url":"https://microdata.worldbank.org/catalog/4163/variable/F4/V1123?name=HC5","publisher":"World Bank Microdata Library"}],"country":null},{"slug":"red-rust","title":"Red Rust on Metal Roofs","category":"problems-maintenance","type":"term","summary":"Iron oxide corrosion on steel roofing that appears once the protective zinc or zinc-aluminium coating has been used up or damaged.","body":"Red rust is the familiar reddish-brown iron oxide that forms when steel corrodes. On metal roofs it signals that the steel base metal itself is now exposed to moisture and oxygen. Most steel roofing is protected by a metallic coating, usually zinc (galvanised) or an aluminium-zinc alloy, often with paint on top. That coating corrodes slowly and sacrificially to protect the steel; red rust appears where the coating has worn away, been scratched through, or been consumed.\n\nRed rust is not a concern on aluminium, copper or zinc roofing, which do not contain iron, though those metals have their own corrosion behaviour.\n\n## Where it starts\n\n- **Cut edges and drilled holes**, where the coating is thinnest or absent.\n- **Scratches** from installation, foot traffic or debris.\n- **Areas that stay wet**: panel laps, low spots, behind debris, under snow guards or in valleys.\n- **Fastener heads** on exposed-fastener systems, especially with incompatible or uncoated screws.\n- **Swarf** (metal filings) left on the roof after cutting, which rusts and stains the finish.\n- **Contact with incompatible materials** such as copper runoff, treated timber or wet cementitious products.\n- **Aggressive environments**: coastal salt spray, industrial pollution, or animal housing.\n\n## Why it matters\n\nLight surface rust at a scratch is mainly cosmetic but spreads under paint over time. Advanced corrosion thins the steel, enlarges fastener holes and eventually perforates the panel, causing leaks and loss of strength.\n\n## Treatment and prevention\n\nEarly rust is generally cleaned back to sound metal, treated with a compatible primer and recoated. Rusted fasteners can be replaced with oversized or properly coated screws. Widespread rust-through usually means panel replacement or a full roof restoration system assessed by a specialist. Prevention includes sweeping off filings after cutting, using fasteners and flashings compatible with the panel coating, keeping roofs free of debris, and choosing coatings and metals suited to the local corrosion environment.","key_facts":[{"label":"Chemistry","value":"Iron oxide formed on exposed steel"},{"label":"Starting points","value":"Cut edges, scratches, laps, fasteners, filings"},{"label":"Not applicable to","value":"Aluminium, copper and zinc roofs"}],"regions":["Global"],"aliases":["rust","metal roof corrosion","steel roof rust"],"related":["white-rust","galvanized-steel-roofing","galvalume","metal-roofing","fastener-back-out","galvanic-corrosion"],"company":null,"sources":[{"title":"Red Rust vs White Rust","url":"https://www.conklinmetal.com/blog/red-rust-vs-white-rust/","publisher":"Conklin Metal Industries"},{"title":"White rust prevention and treatment","url":"https://www.steel.org.au/getattachment/074d4981-2f9d-42d6-b772-e07e8186edac/White-rust-prevention-and-treatment_INGALSM3.pdf","publisher":"Australian Steel Institute"},{"title":"Wet Storage Stain vs. White Rust","url":"https://galvanizeit.org/knowledgebase/article/wet-storage-stain-vs.-white-rust","publisher":"American Galvanizers Association"}],"country":null},{"slug":"redland","title":"Redland","category":"manufacturers","type":"company","summary":"Redland is a British roof tile brand founded in 1919 as the Redhill Tile Company; it is now BMI Redland, part of Standard Industries' BMI Group.","body":"Redland is a British maker of concrete and clay roof tiles and pitched-roof systems. It was founded in 1919 as the Redhill Tile Company, a producer of concrete roof tiles in Surrey, England, and was renamed Redland Tiles in 1946. Today the business trades as BMI Redland, part of BMI Group, and Redland is the oldest brand in that group.\n\n## Growth of Redland plc\n\nRedland expanded internationally after the Second World War. In the early 1950s it moved into South Africa, Australia and Malaysia, and took a stake in the German tile maker Braas in 1954, which later became a majority holding. It listed on the London Stock Exchange in 1955. In 1969 it acquired a significant shareholding in Monier Ltd of Australia. In 1990 its US subsidiary bought the roof tile maker Duratile, and in 1991 it bought Marley's US roof tile subsidiary for GBP 6.6 million. Redland plc was headquartered in Reigate, Surrey.\n\n## Ownership changes\n\n- **1996**: Redland and Braas combine their roof tile operations.\n- **1997**: The French group Lafarge acquires Redland for about GBP 1.8 billion and forms Lafarge Roofing.\n- **2007-2008**: Lafarge divests its roofing division to PAI Partners; it becomes the Monier Group, and the UK business trades as Monier Redland Limited, based in Crawley, West Sussex.\n- **2013-2014**: The wider group becomes Braas Monier Building Group and lists in Frankfurt.\n- **2017**: Standard Industries acquires Braas Monier; the UK business becomes BMI Redland.\n\n## Products\n\nRedland's range centres on concrete and clay roof tiles and related pitched-roof components for the UK and Irish markets, where tiled pitched roofs are the most common roof form on houses.","key_facts":[{"label":"Founded","value":"1919, as Redhill Tile Company"},{"label":"Renamed","value":"Redland Tiles, 1946"},{"label":"Current name","value":"BMI Redland"},{"label":"Parent","value":"BMI Group / Standard Industries"}],"regions":["Europe"],"aliases":["BMI Redland","Redland Tiles","Redhill Tile Company","Monier Redland"],"related":["bmi-group","braas","concrete-roof-tile","marley"],"company":{"founded":"1919","website":"https://www.bmigroup.com/uk/","parent":"BMI Group","known_for":["Concrete roof tiles","Pitched-roof systems in the UK"]},"sources":[{"title":"Redland plc","url":"https://en.wikipedia.org/wiki/Redland_plc","publisher":"Wikipedia"},{"title":"Braas Monier","url":"https://en.wikipedia.org/wiki/Braas_Monier","publisher":"Wikipedia"},{"title":"BMI Redland pitched roofing","url":"https://www.bmigroup.com/uk/redland-pitched/","publisher":"BMI Group"}],"country":null},{"slug":"reinforced-bitumen-membrane","title":"Reinforced Bitumen Membrane (RBM)","category":"low-slope-systems","type":"term","summary":"The UK and European term for factory-made bitumen roofing sheets with polyester or glass reinforcement, laid in multi-layer systems on flat roofs.","body":"Reinforced bitumen membrane, abbreviated RBM and often still called \"felt\" or \"torch-on felt\", is the British and European name for bituminous roofing sheets consisting of a reinforcing carrier coated with bitumen. Modern RBMs are mostly polymer-modified with SBS or APP, the same technologies known in North America as modified bitumen.\n\n## Evolution\n\nTraditional British built-up felt roofs used oxidised bitumen sheets with organic or glass-fibre bases, laid in three layers in hot bitumen and often finished with mineral chippings. Flat roofs of this era earned a reputation for short lives in some cases. Today most sheets are polymer-modified on polyester or composite carriers, which are tougher and more flexible.\n\n## Typical system\n\nAn RBM roof is usually a two- or three-layer warm-roof build-up:\n\n1. vapour control layer on the deck\n2. insulation, often tapered\n3. underlay or base sheet, sometimes partially bonded to allow vapour to disperse\n4. cap sheet with a mineral or slate-granule finish for UV protection\n\nManufacturers supply complete systems combining underlays, insulation and cap sheets.\n\n## Application methods\n\n- **Torch-on:** heating the underside with propane torches; the most common method in the UK\n- **Pour and roll:** rolling the sheet into hot bitumen\n- **Self-adhesive and cold-adhered** systems, chosen where hot works are restricted\n\n## Design\n\nRBM systems in the UK are designed to BS 6229, with a minimum finished fall of 1:80, upstands of at least 150 mm (6 in), and falls created by structure, firrings or tapered insulation. Bauder and other manufacturers note that tapered insulation works with RBM, single-ply and liquid systems alike.","key_facts":[{"label":"Region","value":"UK and Europe"},{"label":"Common polymers","value":"SBS and APP"},{"label":"Typical system","value":"Underlay plus mineral-surfaced cap sheet"},{"label":"UK design code","value":"BS 6229"}],"regions":["Europe"],"aliases":["RBM","torch-on felt","felt roof","built-up felt","bituminous membrane"],"related":["modified-bitumen-roofing","torch-applied-roofing","built-up-roofing","flat-roof","sbs-modified-bitumen"],"company":null,"sources":[{"title":"BS 6229:2018 and flat roofing systems","url":"https://ikogroup.co.uk/?p=820","publisher":"IKO"},{"title":"What is the minimum drainage falls for a single ply flat roof?","url":"https://ikogroup.co.uk/?p=829","publisher":"IKO"},{"title":"Falls and drainage","url":"https://www.bauder.co.uk/roof-systems/refurbishment-projects/solving-the-challenge/improving-drainage-falls","publisher":"Bauder"},{"title":"Who Put the Modified in Modified Bitumens?","url":"https://buildings.com/feature/article/10187932/who-put-the-modified-in-modified-bitumens","publisher":"Buildings"}],"country":null},{"slug":"rheinzink","title":"Rheinzink","category":"manufacturers","type":"company","summary":"Rheinzink is a German producer of titanium zinc for roofing, facades and rainwater systems, founded in 1966 in Datteln and part of the Grillo Group.","body":"Rheinzink GmbH & Co. KG is a German manufacturer of titanium zinc sheet and coil and of roofing, facade and roof-drainage products made from it. The company was founded in 1966 at the instigation of Herbert Grillo, with Stolberger Zink and Vereinigte Deutsche Metallwerke as early shareholders. It is headquartered in Datteln, in North Rhine-Westphalia, and is a member of the Grillo Group. About 500 people work for the company worldwide.\n\n## History\n\nIn the 1960s Herbert Grillo concluded that the rolled zinc then available was not good enough for high-quality roofing and roof drainage, and that a new production technology was needed. He found a combined smelting, casting and rolling system in the United States and assembled shareholders to build a plant. Rheinzink became the first European building-zinc maker to replace traditional pack rolling with a continuous casting-and-rolling line. From 1978 the company concentrated exclusively on building zinc and began industrial production of finished products and systematic brand building. In 1988 it introduced pre-weathered surfaces, followed by a second generation of pre-weathering technology in 2007. A reception building at its headquarters designed by Daniel Libeskind opened in 2009.\n\n## Material\n\nTitanium zinc is zinc alloyed with small amounts of copper and titanium, which improve strength and reduce thermal creep. Exposed to air, zinc develops a protective patina of zinc carbonate. Pre-weathered finishes such as Rheinzink's prePATINA give a uniform grey appearance from installation rather than waiting for natural patination.\n\n## Products\n\n- Standing seam and other roofing systems, plus a roof-integrated solar system.\n- Facade systems: seamed cladding, panels and cassettes.\n- Roof drainage: half-round and box gutters, internal gutters and downpipes.\n- Coils and sheets for fabricators, in finishes including prePATINA, CLASSIC (bright rolled), GRANUM and PRISMO coloured surfaces.\n\nThe company has expanded into markets including India.","key_facts":[{"label":"Founded","value":"1966"},{"label":"Headquarters","value":"Datteln, Germany"},{"label":"Owner","value":"Grillo Group"},{"label":"Material","value":"Titanium zinc"},{"label":"Employees","value":"About 500"}],"regions":["Europe","Global"],"aliases":["RHEINZINK","Rheinzink GmbH & Co. KG"],"related":["zinc-roofing","standing-seam-metal-roof","copper-patina","rain-gutter"],"company":{"founded":"1966","headquarters":"Datteln, Germany","website":"https://www.rheinzink.com","parent":"Grillo Group","known_for":["Titanium zinc sheet","Pre-weathered zinc","Zinc roof drainage"]},"sources":[{"title":"Rheinzink","url":"https://de.wikipedia.org/wiki/Rheinzink","publisher":"Wikipedia (German)"},{"title":"History","url":"https://www.rheinzink.com/company/history/","publisher":"Rheinzink"},{"title":"Rheinzink","url":"https://www.rheinzink.com/","publisher":"Rheinzink"}],"country":null},{"slug":"ridge-board","title":"Ridge Board and Ridge Beam","category":"components","type":"term","summary":"A ridge board is a non-structural board at the roof apex that rafters bear against; a ridge beam is a structural beam that carries the rafters' upper ends.","body":"The ridge is the highest horizontal line of a pitched roof, where two slopes meet. In framing, the timber running along that line goes by several names, and the distinction between a ridge board and a ridge beam matters structurally.\n\n## Ridge board\n\nA ridge board (in Britain often called a ridge piece or ridge plate) is a relatively light board set on edge at the apex. Opposing rafters are nailed against it, which makes the roof easier to assemble and keeps rafters aligned. A ridge board does not hold the rafters up on its own. The roof stays stable because something else stops the rafters from spreading, usually ceiling joists, rafter ties or a tie beam at the bottom, which together with the rafters form a triangle.\n\n## Ridge beam\n\nA ridge beam is a structural member, sized by calculation, that carries the upper ends of the rafters and is itself supported by posts or walls at its ends and sometimes at intermediate points. It is used where there are no ties across the bottom of the rafters, for example with vaulted or cathedral ceilings. Because the beam supports the rafters vertically, they do not push the walls outward in the same way.\n\n## Historic framing\n\nIn medieval and later timber roofs, the king post was traditionally the vertical timber that rose from the tie beam to carry the ridge. Many old roofs had no ridge member at all, with rafter pairs simply joined at the apex.\n\n## Weatherproofing at the ridge\n\nThe structural ridge is covered on the outside by ridge capping: ridge tiles bedded or mechanically fixed in tile and slate roofs, ridge cap shingles on asphalt roofs, or a formed metal ridge cap on metal roofs. Ridges are also a common location for exhaust ventilation.","key_facts":[{"label":"Ridge board","value":"Alignment only, not load-bearing"},{"label":"Ridge beam","value":"Structural, carries rafters"},{"label":"UK names","value":"Ridge piece, ridge plate"}],"regions":["Global"],"aliases":["ridge piece","ridge plate","ridge beam","ridge pole"],"related":["rafter","roof-ridge","collar-tie","king-post-truss","ridge-vent"],"company":null,"sources":[{"title":"Roof glossary","url":"https://www.mkheritage.org.uk/wdahs/Thornton/docs/roofglossary.html","publisher":"Milton Keynes Heritage Association"},{"title":"Rafter","url":"https://en.wikipedia.org/wiki/Rafter","publisher":"Wikipedia"},{"title":"Collar beam","url":"https://en.wikipedia.org/wiki/Collar_beam","publisher":"Wikipedia"}],"country":null},{"slug":"ridge-cap-installation","title":"Ridge Cap Installation","category":"installation","type":"article","summary":"Ridge cap installation covers the peak and hips of a roof with overlapping cap pieces, laid away from the prevailing wind and blind-nailed.","body":"**Ridge caps** (and **hip caps**) are the pieces that cover the joint at the top of a roof and along its external hips. They bridge the gap between the two slopes and shed water down each side. Asphalt shingle roofs use purpose-made cap shingles or 3-tab shingles cut into pieces. Tile and slate roofs use ridge tiles, hip tiles or metal or lead rolls, often over a dry-fix or mortar bed.\n\n## Asphalt shingle method\n\nCanadian guidance describes the following sequence:\n\n1. Snap a chalk line along each hip or ridge so caps lie straight.\n2. Start hips at the eaves and work upward. Start ridges at the end away from the prevailing wind so the laps face downwind.\n3. Bend each cap so it projects equally on both sides.\n4. Lap each cap over the previous one at the exposure the manufacturer specifies, usually equal to the field exposure.\n5. Blind-nail about 50 mm (2 in) above the sealant strip so the next cap covers the nails.\n6. Use longer nails than in the field: 32 mm (1 1/4 in) on new roofs and 38 mm (1 1/2 in) on re-roofs.\n\nWhere cap shingles are cut from 3-tab shingles, each shingle gives three caps. In cold weather the shingles can crack when bent, so they are warmed before use or bent after one side is nailed.\n\n## Ridge vents\n\nWhere a ridge vent is installed, the deck is cut back on each side of the ridge and the vent is fastened over the opening. The caps are then nailed through the vent with longer nails as the vent manufacturer specifies.\n\n## Tile and slate ridges\n\nIn the UK, BS 5534 requires ridge and hip tiles to be mechanically fixed whether or not mortar is used, and BS 8612 covers dry-fix ridge and hip systems. Mortar bedding remains traditional in many countries but is no longer relied on as the only fixing in the UK. Wood shingle ridges are made from pairs of overlapping boards or shingles, with joints alternated so that the ridge stays watertight as it ages.","key_facts":[{"label":"Laying direction (ridge)","value":"Away from prevailing wind"},{"label":"Nail length, new roof (Canada)","value":"32 mm (1 1/4 in)"},{"label":"Nail length, re-roof (Canada)","value":"38 mm (1 1/2 in)"}],"regions":["Global"],"aliases":["hip and ridge","ridge capping","hip cap installation"],"related":["roof-ridge","roof-hip","dry-fix-ridge-system","ridge-vent","shingle-nailing-pattern"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.4.5 Ridges","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-5-ridges/","publisher":"Canadian Roofing Contractors Association"},{"title":"What are the fixing requirements of BS 5534?","url":"https://www.marley.co.uk/blog/what-are-the-fixing-requirements-of-bs-5534","publisher":"Marley"},{"title":"Canadian Roofing Reference Manual: 9.2.7 Installation of Wood Shingles","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-2-wood-shakes-and-wood-shingles/9-2-7-installation-of-wood-shingles/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"ridge-repointing","title":"Ridge Repointing and Rebedding","category":"problems-maintenance","type":"article","summary":"Renewal of the mortar that beds and seals ridge and hip tiles; in the UK, current standards also require mechanical fixing of these tiles.","body":"On many tiled and slated roofs, the ridge and hip tiles are bedded in sand-cement mortar along the apex and hips, with mortar also pointing the joints between them. Over time this mortar cracks, shrinks away from the tiles and erodes. Loose ridge tiles can then rock, let rain in, or blow off in strong winds. Repointing (renewing the visible mortar) and rebedding (lifting the tiles and relaying them on fresh mortar) are common maintenance tasks, particularly in the UK, Ireland, Australia and New Zealand.\n\n## Why mortar fails\n\n- Thermal movement and roof movement crack rigid mortar.\n- Weak or poorly mixed mortar and laying in unsuitable weather; one UK manufacturer notes mortar needs dry conditions and temperatures roughly between 5 °C and 25 °C (41-77 °F).\n- Frost and wind-driven rain erode joints.\n- Mortar shrinks and loses adhesion to smooth tile surfaces.\n\nManufacturers have warned that mortar can begin to fail within the first few years after completion.\n\n## Repointing versus rebedding\n\nRepointing alone only helps when the bedding beneath is still sound and the tiles are firmly attached. When tiles are loose or the bedding has crumbled, the tiles are removed, the old mortar cleaned off, and the tiles relaid on new bedding.\n\n## UK standards and dry-fix systems\n\nIn the UK, the 2014 revision of BS 5534 stated that mortar's tensile strength cannot be relied upon alone to secure ridge and hip tiles, so bedded tiles also need mechanical fixings. A 2018 amendment linked dry-fix systems to BS 8612, the test standard for dry-fixed ridge, hip and verge products. Dry-fix systems use clips, screws and ventilated rolls instead of mortar and reduce routine maintenance. For heritage buildings where a traditional mortar appearance must be kept, mortar bedding may still be used, outside the scope of BS 5534, with suitably specified mixes.\n\n## Practical notes\n\nRidge work is at height on an exposed part of the roof and normally requires scaffolding or edge protection. Matching original tiles is important on older buildings.","key_facts":[{"label":"Repointing","value":"Renewing visible mortar joints only"},{"label":"Rebedding","value":"Lifting and relaying tiles on fresh mortar"},{"label":"UK requirement","value":"Mechanical fixing of ridge and hip tiles (BS 5534)"}],"regions":["Europe","Oceania","Global"],"aliases":["ridge rebedding","ridge pointing","hip repointing"],"related":["roof-ridge","tile-slippage","clay-roof-tile","concrete-roof-tile","bs-5534"],"company":null,"sources":[{"title":"Should I use mortar or dry fix for my ridge and hip tiles","url":"https://marley.co.uk/blog/should-i-use-mortar-or-dry-fix-for-my-ridge-and-hip-tiles","publisher":"Marley"},{"title":"How to repoint ridge tiles","url":"https://www.jjroofingsupplies.co.uk/good-roofing-guide/how-to-guides/how-to-repoint-ridge-tiles","publisher":"JJ Roofing Supplies"},{"title":"How to fix ridge tiles to a roof","url":"https://cm.marley.co.uk/blog/how-to-fix-ridge-tiles-to-a-roof","publisher":"Marley"}],"country":null},{"slug":"ridge-vent","title":"Ridge Vent","category":"components","type":"term","summary":"A ridge vent is a continuous exhaust vent along the ridge of a pitched roof that lets warm, moist air escape from the attic through a slot in the deck.","body":"A ridge vent is an exhaust vent installed along the full length, or most of the length, of a roof ridge. The roof deck is cut back on each side of the ridge to form a continuous slot, and a vented cap is fixed over it. The cap is then covered with ridge shingles, ridge tiles or a metal ridge cap so the vent is nearly invisible from the ground.\n\n## How it works\n\nWarm air rises to the top of the roof space by stack effect, and wind blowing across the ridge creates suction that helps draw air out. Paired with continuous intake at the eaves, a ridge vent produces an even flow of air under the whole deck. Because it sits at the highest point, it is well placed to meet the US code option that allows the total vent area to be reduced from 1/150 to 1/300 of the attic area when 40% to 50% of the ventilation is located within 3 ft (914 mm) of the ridge, with the balance at the eaves.\n\n## Types\n\n- **Shingle-over ridge vents:** rigid plastic or rolled fibrous mat products covered with cap shingles, common on asphalt roofs in North America.\n- **Externally baffled vents:** designed so wind passing over the ridge accelerates past the opening, increasing suction and resisting rain and snow entry.\n- **Metal ridge vents:** formed metal caps with perforated closures for metal roofs.\n- **Dry ridge vent systems:** in the UK, ventilated dry ridge systems fix ridge tiles mechanically while providing high-level ventilation, typically rated as an equivalent continuous slot (for example 5 mm).\n\n## Considerations\n\n- Ridge vents need adequate intake; without eave vents, they can draw air from the house.\n- Hip roofs have short ridges, so ridge vents alone may not provide enough exhaust; alternatives include hip vents or individual roof vents.\n- Mixing a ridge vent with gable louvres or powered fans can short-circuit the airflow.\n- Net free vent area ratings, given per linear foot or metre, are used to size the installation.","key_facts":[{"label":"Position","value":"Continuous along the ridge"},{"label":"Requires","value":"Balanced intake at the eaves"},{"label":"Rating","value":"Net free vent area per length"}],"regions":["Global"],"aliases":["continuous ridge vent","ridge ventilation","dry ridge vent"],"related":["roof-ventilation","roof-ridge","soffit","cold-roof"],"company":null,"sources":[{"title":"IRC R806 Roof Ventilation (code change proposal)","url":"https://iccsafe.org/wp-content/uploads/bcac/IRC-R806.pdf","publisher":"International Code Council"},{"title":"Attic-Ventilation Strategies","url":"https://finehomebuilding.com/project-guides/roofing/attic-ventilation-strategies","publisher":"Fine Homebuilding"},{"title":"Batten space ventilation for pitched roofs","url":"https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/LABCW%20Batten%20space%20ventilation%20for%20pitched%20roofs%20V2.pdf","publisher":"LABC Warranty"}],"country":null},{"slug":"rock-hewn-churches-of-lalibela","title":"Rock-Hewn Churches of Lalibela","category":"world-roofing","type":"place","summary":"Eleven medieval churches carved from basalt in Lalibela, Ethiopia; their rock roofs have been covered since 2008 by temporary EU-funded shelters.","body":"The Rock-Hewn Churches of Lalibela in northern Ethiopia are eleven churches carved directly out of the ground. Since each building is cut downward from the bedrock, its roof is simply the original rock surface, which raises unusual problems of weathering and water protection. Since 2008, several of the churches have been covered by large temporary shelters.\n\n## Origins\n\nTradition credits King Gebre Meskel Lalibela of the Zagwe dynasty (reigned c. 1181-1221) with the project, which is said to have taken 24 years, and local tradition dates the founding of Lalibela to 1137. Scholars think the churches more likely developed through several phases of construction and alteration.\n\n## How they were made\n\nBuilders excavated scoriaceous basalt with hammers and chisels, working from the top down. Of the eleven churches, four are free-standing monoliths and seven share a wall with the surrounding rock. They form a northern group of five, a southern group of five, and the separate church of Biete Giorgis.\n\n## Roofs and shelters\n\nBecause the churches are carved rather than built, their tops have no separate waterproof covering. The site was inscribed on the World Heritage List in 1978. In 2008, four temporary shelters funded by the European Union were erected over five of the churches, intended to protect them until a long-term solution was chosen. The shelters have remained far longer than planned, and they are now considered a danger in themselves, including a risk of collapse under their own weight. Ethiopia's heritage authority (ARCCH) has said they must be removed, but no definitive plan for removal, or for protecting the churches afterwards, had been agreed.\n\n## Significance\n\nAt Lalibela the roof is part of the monument itself, so conservators must protect a rock surface rather than renew a separate covering, without hiding the rock or overloading the site.","key_facts":[{"label":"Number of churches","value":"11"},{"label":"Rock","value":"Scoriaceous basalt"},{"label":"Attributed to","value":"King Lalibela (r. c. 1181-1221)"},{"label":"World Heritage","value":"Inscribed 1978"},{"label":"Protective shelters","value":"4 EU-funded shelters over 5 churches, 2008"}],"regions":["Africa"],"aliases":["Lalibela churches","Lalibela shelters","Lalibela rock churches"],"related":["roofing-in-ethiopia","hidmo","tukul"],"company":null,"sources":[{"title":"Rock-Hewn Churches, Lalibela","url":"https://en.wikipedia.org/wiki/Rock-Hewn_Churches,_Lalibela","publisher":"Wikipedia"},{"title":"State of Conservation: Rock-Hewn Churches, Lalibela","url":"https://whc.unesco.org/en/soc/3988","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"roll-roofing","title":"Roll Roofing","type":"term","summary":"Asphalt-saturated felt or mat supplied in rolls and surfaced with mineral granules, used as an economical exposed roof covering on low-slope and utility roofs.","body":"Roll roofing is a bitumen roofing product made from the same basic materials as asphalt shingles, a felt or glass-fibre mat saturated and coated with asphalt and surfaced with mineral granules, but supplied as continuous rolls rather than cut shingles. It is designed to be left exposed to the weather and is one of the cheapest roof coverings available.\n\n## Uses\n\nRoll roofing is typically used on sheds, garages, porches, farm buildings and other structures where appearance and long life are less important than cost. It is also used in valleys and as an underlayer in some built-up systems. In the United Kingdom and Ireland, the similar product is commonly called **shed felt** or mineral felt.\n\n## Slope\n\nIn US model codes, mineral-surfaced roll roofing can be used on slopes as low as 1:12 (about 4.8°), lower than the 2:12 minimum for asphalt shingles. On these shallow slopes the laps are sealed with cement or adhesive.\n\n## Variants\n\n- **Nail-down roll roofing**: laid in overlapping courses and fastened with roofing nails, with laps sealed using lap cement.\n- **Self-adhesive rolls**: with a release film over the adhesive.\n- **Torch-on rolls**: modified-bitumen products melted into place with a gas torch; these are usually classed as low-slope membranes rather than simple roll roofing.\n\n## Limitations\n\nBecause it is a single thin layer with lapped seams, roll roofing generally has a shorter service life than shingles or multi-ply membranes. Heat and ultraviolet light age the asphalt, and the long seams are vulnerable to wind and to thermal movement. It is not generally used on homes where appearance matters.\n\n## Relationship to roofing felt\n\nPlain roofing felt (for example, US \"#15\" and \"#30\" felts under ASTM D226) is a similar asphalt-saturated sheet but without a granule surface; it is meant as an underlayment, not as an exposed finish.\n","key_facts":[{"label":"Composition","value":"Asphalt-saturated mat with granule surface"},{"label":"Minimum slope (US model code)","value":"1:12 (about 4.8°)"},{"label":"UK/Ireland term","value":"Shed felt, mineral felt"}],"regions":["North America","Europe"],"aliases":["rolled roofing","mineral-surfaced roll roofing","MSR","shed felt"],"related":["asphalt-shingle","roofing-felt","modified-bitumen-roofing","built-up-roofing","roofing-underlayment"],"sources":[{"title":"Roofing felt","url":"https://en.wikipedia.org/wiki/Roofing_felt","publisher":"Wikipedia"},{"title":"Asphalt Shingle Types (3-Tab vs. Laminated Architectural), ASTM Classifications & Thermal Behavior","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-types-astm-thermal","publisher":"Open Exam Prep"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"regions":["Europe"],"company":null,"slug":"roman-brick-and-tile-stamps","title":"Roman Brick and Tile Stamps","category":"history","type":"article","summary":"Marks pressed into Roman bricks and roof tiles before firing, naming makers, owners, legions or consuls; archaeologists use them to date buildings.","aliases":["brick stamps","tile stamps","bolli laterizi","legionary tile stamps"],"body":"Roman brick and tile makers often pressed a stamp into the wet clay before firing. These **brick stamps** (Italian *bolli laterizi*) are now one of the most useful tools for dating Roman buildings, including their roofs, because bricks and tiles came from the same yards and broken fragments of the two are often hard to tell apart.\n\n## Origins and content\n\nStamping began around the middle of the 1st century BC. Early stamps were made with a hardwood or metal die and usually gave only a person's name, sometimes with the name of the brickyard. As fired brick became the main building material of the early Empire, more producers entered the trade and stamps became more detailed. From AD 110 they began to include the names of the consuls of the year, which allows a stamped brick to be dated to a single year.\n\nA full stamp could record:\n\n- the **owner** of the estate (*dominus*);\n- the **supervisor** of the yard (*officinator*);\n- the **brickyard** itself;\n- the **consuls** in office.\n\n## Production\n\nMost brick and tile came from yards on large estates owned by wealthy families with access to good clay. The workforce had three tiers: owners, supervisors and the workers who made the bricks, usually slaves. Output was regulated, and over time the business became an imperial monopoly. A brickyard belonging to Domitia Calvilla, mother of Emperor Marcus Aurelius, has been found at Bomarzo, north of Rome.\n\n## Military stamps\n\nAcross the provinces, army units ran their own kilns, including mobile ones, and stamped tiles and bricks with the legion's mark. A 1993 excavation in Merseyside, England, recovered more than 300 kg (660 lb) of tile and kiln remains, including tiles stamped by Legio XX Valeria Victrix. Such finds show where the army was operating as well as when.\n\n## Roofs and the tile industry\n\nThe standard Roman roof combined flat *tegulae* with curved *imbrices*, and these were produced in enormous numbers alongside bricks. Stamps on roof tiles therefore date not only walls but also roofing phases and repairs. Broken tiles were also recycled by crushing them into mortar.\n\n## Use in archaeology\n\nOnce treated as curiosities, stamps are now carefully recorded. Combined with architectural evidence, they provide a reliable method of dating Roman construction and show changing patterns of demand for building materials.","key_facts":[{"label":"Earliest stamps","value":"Mid-1st century BC"},{"label":"Consular dating","value":"From AD 110"},{"label":"Information recorded","value":"Owner, supervisor, yard, consuls; or legion"},{"label":"Main use today","value":"Dating Roman buildings"}],"related":["imbrex-and-tegula","roofing-in-italy","ancient-greek-roof-tiles","pantheon-dome","clay-roof-tile","terracotta"],"sources":[{"title":"Roman brick","url":"https://en.wikipedia.org/wiki/Roman_brick","publisher":"Wikipedia"},{"title":"Imbrex and tegula","url":"https://en.wikipedia.org/wiki/Imbrex_and_tegula","publisher":"Wikipedia"}],"country":null},{"slug":"rondavel","title":"Rondavel","type":"article","summary":"Round Southern African house with a conical thatched roof on a cylindrical wall, found in South Africa, Lesotho, Eswatini and Botswana.","body":"A *rondavel* (from Afrikaans *rondawel*) is a round house with a cylindrical wall and a conical roof, a form sometimes described as \"cone on cylinder\". It is found across Southern Africa, including South Africa, Lesotho (where it is also called *mokhoro*), Eswatini and Botswana. Rondavels are used as homes, as farm outbuildings and increasingly as holiday cottages and lodge rooms.\n\n## Walls\n\nWalls are traditionally built of stone or mud, bonded with a mortar of sand, soil or both mixed with cow dung. Floors are often finished with a dung mixture that dries to a hard, smooth surface. Modern rondavels may use concrete foundations and cement block or brick walls.\n\n## The conical roof\n\nThe roof is a self-supporting cone:\n\n- Main members are poles cut from tree limbs.\n- **Principals** run radially from the apex down to the top of the wall.\n- **Circular purlins** ring the cone at intervals and support the principals and thatch.\n\nBecause a cone braces itself, large rondavels can be built without internal posts or struts, leaving the floor completely open.\n\nThe roof is thatched with grass. The thatch is sewn to the poles with grass rope, one band at a time, starting at the eaves and working up to the apex so that each course overlaps the one below. A capping at the peak closes the cone.\n\n## Climate performance\n\nA thick thatch roof over heavy walls moderates temperature, keeping interiors cooler during hot days and retaining warmth on cold highveld or mountain nights. The steep cone sheds summer thunderstorm rain. The round form presents no flat face to the wind.\n\n## Modern versions\n\nMany rondavels now have corrugated iron or other sheet-metal roofs in place of thatch, which are quicker to install but hotter and noisier in rain. Others keep thatch for its appearance and thermal comfort, particularly in tourism. Running water and electricity are now common.\n\n## Related forms\n\nRound, thatched houses are found throughout sub-Saharan Africa under many local names; the rondavel is the best-known Southern African version in English.","key_facts":[{"label":"Region","value":"South Africa, Lesotho, Eswatini, Botswana"},{"label":"Form","value":"Conical roof on cylindrical wall"},{"label":"Roof structure","value":"Radial principals and circular purlins"},{"label":"Traditional covering","value":"Grass thatch sewn with grass rope"},{"label":"Lesotho name","value":"Mokhoro"}],"regions":["Africa"],"aliases":["Rondawel","Mokhoro","Cone-on-cylinder hut"],"related":["roofing-in-southern-africa","thatch","conical-roof","cape-dutch-thatch"],"sources":[{"title":"Rondavel","url":"https://en.wikipedia.org/wiki/Rondavel","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roof-age-estimation","title":"Roof Age Estimation","category":"problems-maintenance","type":"article","summary":"Methods for working out how old a roof is, using records, permits, product markings and physical condition.","body":"Knowing a roof's age helps owners plan maintenance and replacement, and it is often requested by insurers, lenders and buyers. Because few homes have complete records, age is usually established from a combination of documents and physical evidence.\n\n## Records\n\n- **Building permits**: many municipalities record reroofing permits, which can be searched by address.\n- **Previous owners, sellers' disclosures and home inspection reports** from earlier sales.\n- **Contractor invoices and warranty registrations**; manufacturer warranty registrations record installation dates.\n- **Insurance records** and claim histories.\n- **Aerial and street-level imagery** from mapping services, which can show when a roof's colour or material changed.\n\n## Product evidence\n\n- **Manufacturer markings**: some shingle wrappers, underlayment labels or tile backs carry date or batch codes; leftover materials in garages or attics can help.\n- **Product identification**: discontinued shingle styles, tile profiles or panel types can narrow the date range; specialist services identify shingle products from samples.\n- **Construction clues**: the type of underlayment, nails, flashing and vents can suggest an era.\n\n## Physical condition\n\nInspectors estimate age from wear, but this is the least precise method because climate, slope orientation, ventilation, colour and product quality all affect weathering. For asphalt shingles, indicators include granule loss, curling, cracking and loss of flexibility. For wood, weathering colour, splitting and erosion. For metal, coating chalking, fading and corrosion. For slate and tile, the age of the roof covering may be far greater than the age of its fixings, battens and flashings.\n\n## Limits\n\nPhysical estimates should be expressed as a range and with caveats. Insurers in some regions require roofs over a certain age to be inspected or rated differently, so documentation can matter financially. A roof's remaining life depends on condition, not only age; a well-maintained older roof may outperform a neglected newer one.","key_facts":[{"label":"Best evidence","value":"Permits, invoices, warranty registrations"},{"label":"Supporting evidence","value":"Product codes, imagery, construction clues"},{"label":"Least precise","value":"Estimating from physical wear alone"}],"regions":["Global"],"aliases":["how old is my roof","roof age"],"related":["repair-vs-replace","roof-insurance-claims","granule-loss","shingle-curling","roof-maintenance-checklist"],"company":null,"sources":[{"title":"How old is my roof?","url":"https://www.acg.aaa.com/connect/blogs/6c/home/how-old-is-my-roof","publisher":"AAA"},{"title":"How to Find Out Who Installed My Roof and Why It's Important","url":"https://angi.com/articles/how-to-find-out-who-installed-my-roof.htm","publisher":"Angi"},{"title":"Determine the Age of a Roof for Insurance Purposes","url":"https://bridgelegal.org/determine-age-roof-insurance-purposes/","publisher":"Bridge Legal"}],"country":null},{"slug":"roof-algae","title":"Roof Algae (Black Streaks)","category":"problems-maintenance","type":"article","summary":"Dark streaks on roofs, especially asphalt shingles, caused by airborne cyanobacteria commonly identified as Gloeocapsa magma.","body":"The dark brown or black streaks that run down many light-coloured roofs are usually a growth of cyanobacteria (blue-green algae), most often identified as *Gloeocapsa magma*. The streaks are common on asphalt shingles in warm, humid regions, but they appear in many climates and also on tile and other surfaces.\n\n## How it grows\n\nSpores are carried by wind and by birds and small animals from roof to roof, which is why streaking often spreads through a neighbourhood. The organism thrives on surfaces that are warmed by sun and dampened by rain or dew, and it is often reported to feed on the limestone filler used in many asphalt shingles. As it grows it produces a dark protective pigment against ultraviolet light; the visible streaks are largely accumulated layers of this dark material and dead cells. Streaks usually start on the slopes that stay damp longest and follow the path of runoff.\n\n## Effects\n\nThe main effect is appearance. Some sources note that the dark layer absorbs more heat, and that long-term growth may contribute to surface wear. Algae is different from moss and lichen, which are thicker growths that hold more moisture and can lift roof units.\n\n## Cleaning\n\nThe usual recommendation from shingle manufacturers' associations is a low-pressure application of a diluted sodium hypochlorite (bleach) solution, followed by rinsing, rather than pressure washing. Plants below should be protected and the roof surface kept safe to walk on. Commercial cleaners and professional soft washing are alternatives (see roof cleaning).\n\n## Prevention\n\n- **Algae-resistant shingles**, sold in many markets, contain a proportion of granules treated with copper compounds that slowly release ions which inhibit growth. The copper industry reports protection periods of up to about 30 years depending on the product.\n- **Copper or zinc strips** near the ridge release metal ions with rain.\n- **Reducing shade and moisture** by trimming trees helps the roof dry faster.\n\nAlgae streaks are generally not covered as damage by insurance, and algae-resistance warranties vary by manufacturer and region.","key_facts":[{"label":"Organism","value":"Cyanobacteria, commonly Gloeocapsa magma"},{"label":"Spread","value":"Airborne spores, birds and animals"},{"label":"Prevention","value":"Copper-treated granules, metal strips, less shade"}],"regions":["Global"],"aliases":["Gloeocapsa magma","black streaks on roof","roof stains"],"related":["roof-cleaning","zinc-and-copper-strips","roof-moss","lichen-on-roofs","asphalt-shingle"],"company":null,"sources":[{"title":"Copper Ions Keep Roofs Clean","url":"https://copper.org/publications/newsletters/discover/2007/spring/article1.php","publisher":"Copper Development Association"},{"title":"Black Roof Stains","url":"https://www.askthebuilder.com/black-roof-streaks/","publisher":"Ask the Builder"},{"title":"Algae on the Roof: A Growing Problem","url":"https://roofingcontractor.com/articles/85105-algae-on-the-roof-a-growing-problem","publisher":"Roofing Contractor"},{"title":"Algae Discoloration of Shingles (CASMA)","url":"https://InspectAPedia.com/roof/Algae-Discoloration-of-Shingles-CASMA.pdf","publisher":"InspectAPedia"}],"country":null},{"slug":"roof-battens","title":"Roof Battens and Counter-Battens","category":"components","type":"term","summary":"Roof battens are strips fixed across rafters to hang tiles, slates or sheets; counter-battens run up the slope beneath them to make a drainage gap.","body":"Roof battens (also called roofing lath, tiling battens or slate battens) are narrow strips, usually sawn softwood but sometimes metal, fixed horizontally across rafters, trusses or a deck. They provide the fixing points for tiles, slates, shingles or metal sheets. Their spacing, known in the UK as the gauge, is set by the length and headlap of the roof covering.\n\nCounter-battens are battens laid vertically, running up the slope along the line of the rafters on top of the underlay or deck. The horizontal tiling battens are then fixed on top of them, producing a grid.\n\n## Why counter-battens are used\n\n- They lift the tiling battens off the underlay so that any water reaching the underlay can drain freely down to the eaves instead of collecting behind battens.\n- They create a continuous ventilated space between underlay and covering, which UK guidance requires in some combinations of low-resistance underlay and air-tight coverings.\n- They allow tiles to be fixed over a continuous deck or rigid insulation in warm roofs.\n\n## Regional practice\n\nBattens are standard under tile and slate roofs in the UK, Ireland, Europe, Australia and New Zealand. In the UK, BS 5534 is the code of practice for slating and tiling and covers batten specification and fixing. North American roofs more often use a solid deck, although battens (sometimes called strapping or furring) are used for some tile, slate, stone-coated steel and metal roofs, and counter-batten systems are used to create ventilated \"cold\" roofs. In batten-seam metal roofing, battens form the raised seams between pans.\n\n## Durability\n\nTimber battens are usually treated against decay. Because battens carry the whole covering and resist wind uplift through their fixings, undersized or poorly fixed battens are a common cause of roof failure in storms. Batten size and fixing requirements depend on rafter spacing, covering weight and exposure, and are set by the relevant standard.","key_facts":[{"label":"UK spacing term","value":"Gauge"},{"label":"UK code of practice","value":"BS 5534"},{"label":"Counter-batten direction","value":"Up the slope, along rafters"}],"regions":["Global"],"aliases":["batten","tiling batten","roofing lath","counter-batten","counterbatten","strapping"],"related":["roofing-underlayment","vapour-permeable-underlay","skip-sheathing","purlin","warm-roof"],"company":null,"sources":[{"title":"Batten","url":"https://en.wikipedia.org/wiki/Batten","publisher":"Wikipedia"},{"title":"Batten space ventilation for pitched roofs","url":"https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/LABCW%20Batten%20space%20ventilation%20for%20pitched%20roofs%20V2.pdf","publisher":"LABC Warranty"},{"title":"The use of vapour permeable underlays in compliance with BS 5534","url":"https://rcimag.co.uk/sandtoft-blog/the-use-of-vapour-permeable-underlays-in-compliance-with-bs-5534","publisher":"Roofing Cladding & Insulation (RCI) magazine"}],"country":null},{"slug":"roof-blistering","title":"Roof Blistering","category":"problems-maintenance","type":"term","summary":"Raised bubbles in asphalt shingles or low-slope membranes caused by trapped gas, moisture or volatiles expanding under heat.","body":"Blistering is the formation of raised, often rounded bumps in a roof covering. It occurs in two quite different settings: on the surface of asphalt shingles, and within or under multi-ply and single-ply low-slope membranes. In both, the cause is a pocket of gas or moisture that expands when the roof heats in the sun.\n\n## Asphalt shingle blisters\n\nOn shingles, blisters appear as small bubbles in the coating asphalt. When the thin cap breaks away, it leaves a pit or pockmark that exposes dark asphalt or even the mat. Inspectors distinguish these from hail hits because blister pits have lost their granules along with the cap, while hail typically leaves a bruise or fracture with granules partly in place.\n\nOlder shingles sometimes blistered because of mixing errors or moisture in the materials. Today, blisters usually develop within the first year as volatile compounds escape from the asphalt of a roof that runs too hot, frequently because of poor attic ventilation. Small, scattered blisters are mostly cosmetic. Widespread, large blisters can shorten shingle life by speeding granule loss.\n\n## Membrane blisters\n\nOn built-up roofing (BUR), modified bitumen and some adhered single-ply systems, blisters are areas where plies or the membrane have separated from each other or from the substrate. They often start from voids left during application, moisture trapped in insulation or between plies, or poor adhesion. Daily heating and cooling pumps air in and out, so blisters can grow. If a blister is broken by foot traffic or cracks with age, water can enter the assembly.\n\n## Assessment and repair\n\nFor shingles, the decision rests on how much of the roof is affected; isolated blisters may be ignored, extensive blistering may justify earlier replacement and a ventilation review. For membranes, small, stable blisters are often monitored rather than opened. Larger or broken ones are typically cut out, dried and patched according to the membrane manufacturer's procedures. Persistent blistering can point to wet insulation, which a moisture survey can confirm.","key_facts":[{"label":"Shingle blister cause today","value":"Volatiles escaping from overheated new shingles"},{"label":"Membrane blister cause","value":"Voids, trapped moisture or poor adhesion between plies"},{"label":"Typical shingle timing","value":"Within the first year after installation"}],"regions":["Global"],"aliases":["blisters","shingle blistering","membrane blistering"],"related":["asphalt-shingle","granule-loss","built-up-roofing","modified-bitumen-roofing","roof-ventilation","roof-moisture-survey"],"company":null,"sources":[{"title":"Mastering Roof Inspections: Asphalt Composition Shingles, Part 35","url":"https://nachi.org/asphalt-comp-shingles-part35-89.htm","publisher":"InterNACHI"},{"title":"Asphalt Roof Blister Cause","url":"https://InspectAPedia.com/roof/Asphalt_Roof_Blister_Cause.php","publisher":"InspectAPedia"},{"title":"Common Problems With Built-Up Roof Systems","url":"https://facilitiesnet.com/roofing/article.aspx?id=15980","publisher":"Facilitiesnet"}],"country":null},{"slug":"roof-brackets","title":"Roof Brackets","category":"installation","type":"term","summary":"Roof brackets (roof jacks) are metal supports nailed to a pitched roof that hold a plank as a foothold and material shelf for roofers.","body":"**Roof brackets**, also called **roof jacks** or **toe-board brackets**, are steel or timber supports fastened to a sloping roof so that a horizontal plank can be laid across them. The plank gives roofers a stable foothold and a place to set bundles and tools on a steep slope. Brackets are a work-positioning aid; on their own they do not satisfy fall protection rules in most jurisdictions.\n\n## Types\n\nCanadian roofing guidance describes two common timber types: the **flat jack**, which takes a 38 x 89 mm (1 1/2 x 3 1/2 in) board set on edge and suits an average house roof up to 1:1 (12:12) pitch, and the **solid jack**, which takes a 38 x 189 mm (1 1/2 x 7 1/2 in) board set perpendicular to the roof. Manufactured adjustable steel brackets allow the plank angle to be set level on different pitches.\n\n## Installation\n\n- Nail the bracket where a later shingle course will cover the nails, in the same positions as shingle nails.\n- Use long nails and drive them into rafters or solid framing where possible.\n- Use straight-grained planks, and add an intermediate bracket on boards longer than 3 m (10 ft).\n- Do not overload a plank, and allow for the weight of shingle bundles stored on it.\n\n## Removal\n\nWhen the roof is finished, the brackets are removed by lifting the covering shingle tabs and knocking the brackets free of their nails, then driving the nails flush so the finished roof lies smooth.\n\n## Safety context\n\nUS OSHA guidance states that slide guards cannot by themselves replace conventional fall protection and may be used only within a written fall protection plan where conventional methods are infeasible. Canadian guidance notes that some solid-jack arrangements may not meet provincial occupational safety requirements. Brackets are therefore used alongside harness systems, scaffolding at the eaves or other approved fall protection.","key_facts":[{"label":"Flat jack plank (Canada)","value":"38 x 89 mm (1 1/2 x 3 1/2 in) on edge"},{"label":"Solid jack plank (Canada)","value":"38 x 189 mm (1 1/2 x 7 1/2 in)"},{"label":"Extra bracket needed","value":"Boards over 3 m (10 ft)"}],"regions":["North America","Global"],"aliases":["roof jacks","toe board brackets","roof jack brackets","slide guards"],"related":["roofing-fall-protection","ladder-safety","personal-fall-arrest-system"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 1.7.4 Roof Brackets and Roof Jacks","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-1-safety/1-7-ladders-scaffolds-roof-jacks/1-7-4-roof-brackets-and-roof-jacks-for-steep-roofs/","publisher":"Canadian Roofing Contractors Association"},{"title":"Fall Protection in Residential Construction: Frequently Asked Questions","url":"https://www.osha.gov/residential-fall-protection/faq","publisher":"U.S. Occupational Safety and Health Administration"}],"country":null},{"slug":"roof-cleaning","title":"Roof Cleaning Methods","category":"problems-maintenance","type":"article","summary":"Ways of removing algae, moss, lichen and dirt from roofs, chiefly low-pressure soft washing, manual removal and pressure washing.","body":"Roof cleaning removes biological growth (algae, moss, lichen, mould) and dirt from roof surfaces. It is done mainly for appearance and to stop moss and debris from holding water and lifting roof units. The method matters: some approaches clean effectively at low risk, while others can shorten the roof's life or affect manufacturer warranties.\n\n## Soft washing\n\nSoft washing applies a cleaning solution at low pressure, typically with a pump sprayer, and relies on chemistry rather than force. The most common active ingredient is sodium hypochlorite (chlorine bleach), sometimes with surfactants; oxygen-based cleaners such as sodium percarbonate are alternatives. The solution kills algae and other organisms; residue and dead growth wash off with rain or a gentle rinse. Asphalt shingle industry guidance has recommended a diluted bleach solution, with one widely quoted recommendation being equal parts household-strength bleach and water, applied without pressure washing.\n\nPrecautions include wetting and protecting plants below, managing runoff away from drains and waterways, protecting metal gutters and fixtures from corrosion, and following product labels and local regulations.\n\n## Manual removal\n\nThick moss is often brushed or scraped off by hand, working downslope to avoid lifting shingles or tiles, sometimes after a pre-treatment that loosens it. This is slow and requires safe roof access.\n\n## Pressure washing\n\nHigh-pressure washing removes growth quickly but carries well-documented risks:\n\n- stripping protective granules from asphalt shingles;\n- eroding the surface of concrete tiles and wood shakes;\n- breaking brittle tiles and slates;\n- forcing water up under laps and into the roof;\n- creating slippery, dangerous working conditions.\n\nThe Asphalt Roofing Manufacturers Association discourages pressure washers and mechanical cleaning tools on asphalt shingles, and many tile and shingle manufacturers caution against them. Some tile roofs are pressure-cleaned and then recoated as part of a restoration, which is a different process with its own specifications.\n\n## After cleaning\n\nZinc or copper strips, algae-resistant shingles and trimming trees slow regrowth. Cleaning is not a substitute for repairs: inspect the roof once it is clean, since growth can hide cracked or slipped units.","key_facts":[{"label":"Preferred for shingles","value":"Low-pressure soft wash with diluted bleach"},{"label":"Main risk of pressure washing","value":"Granule loss and water forced under laps"},{"label":"Regrowth control","value":"Zinc or copper strips, less shade"}],"regions":["Global"],"aliases":["soft washing","roof washing","roof moss cleaning"],"related":["roof-algae","roof-moss","lichen-on-roofs","zinc-and-copper-strips","granule-loss"],"company":null,"sources":[{"title":"Roof cleaning","url":"https://en.wikipedia.org/wiki/Roof_cleaning","publisher":"Wikipedia"},{"title":"How to Clean Roof Shingles Properly","url":"https://bobvila.com/articles/how-to-clean-roof-shingles","publisher":"Bob Vila"},{"title":"Algae Discoloration of Shingles (CASMA)","url":"https://InspectAPedia.com/roof/Algae-Discoloration-of-Shingles-CASMA.pdf","publisher":"InspectAPedia"},{"title":"On-roof moss removal","url":"https://depts.washington.edu/hortlib/pal/on-roof-moss-removal/","publisher":"University of Washington Elisabeth C. Miller Library"}],"country":null},{"slug":"roof-coating","title":"Roof Coating and Restoration","category":"low-slope-systems","type":"article","summary":"A fluid-applied layer, such as acrylic, silicone or polyurethane, applied over a sound existing roof to waterproof it, reflect sunlight and extend its service life.","body":"A roof coating is a liquid applied in one or more coats over a roof surface, where it dries or cures into a thin, monolithic, fully adhered film. On low-slope roofs coatings are used both as the protective top layer of systems such as spray polyurethane foam, and as a \"restoration\" treatment that renews an ageing membrane or metal roof without tearing it off.\n\n## Purposes\n\n- waterproofing and sealing minor defects on a structurally sound roof\n- protecting the substrate from UV, heat, rain and hail\n- creating a reflective cool roof that lowers surface temperature and cooling loads\n- providing a wearing surface, sometimes with embedded granules\n\nCoatings are not normally traffic-bearing; trafficked balconies and decks use dedicated deck-coating systems.\n\n## Main types\n\n- **Acrylic:** water-based, economical, highly reflective; not usually warranted for ponding water.\n- **Silicone:** high-solids, very UV-stable, tolerant of ponding in many products; dirt pick-up and recoat adhesion need attention.\n- **Polyurethane:** tough and abrasion-resistant, aromatic and aliphatic grades.\n- **Polyurea, butyl, SBS/styrene-butadiene, PVDF.**\n- **Asphalt and coal-tar based coatings** for bituminous roofs.\n\n## Thickness\n\nDry film thickness ranges from about 0.075 mm (3 mils) to over 1 mm (40 mils). On SPF roofs typical coatings are 0.5-1.0 mm (20-40 mils).\n\n## Restoration process\n\nA typical restoration includes a roof survey (often with moisture scanning to find wet insulation), removal of wet areas, cleaning, repairs to seams and flashings, primer where needed, reinforcing fabric at details, and coating applied to a specified thickness. Properly maintained coatings need periodic recoating; on SPF roofs this is usually every 10-20 years.\n\n## Limitations\n\nCoatings cannot fix a roof with saturated insulation or structural problems. Coating asphalt shingles and some built-up roofs needs caution because of trapped moisture. Light-coloured coatings show dirt and biological growth more readily in warm, humid climates.","key_facts":[{"label":"Dry film thickness","value":"About 0.075-1 mm (3-40 mils)"},{"label":"Common types","value":"Acrylic, silicone, polyurethane, polyurea"},{"label":"Typical uses","value":"Restoration, cool roofs, SPF protection"},{"label":"Not suited to","value":"Roofs with wet insulation or structural defects"}],"regions":["Global"],"aliases":["roof restoration","fluid-applied coating","elastomeric roof coating","cool roof coating"],"related":["acrylic-roof-coating","silicone-roof-coating","spray-polyurethane-foam-roofing","liquid-applied-roofing","cool-roof","ponding-water"],"company":null,"sources":[{"title":"Roof coating","url":"https://en.wikipedia.org/wiki/Roof_coating","publisher":"Wikipedia"},{"title":"Cool Roofs","url":"https://www.energy.gov/energysaver/cool-roofs","publisher":"U.S. Department of Energy"},{"title":"RICOWI Roof Guide: Spray Foam","url":"https://ibhs.org/guidance/ricowi-roof-guide-spray-foam/","publisher":"IBHS / RICOWI"},{"title":"Cool roof","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"}],"country":null},{"slug":"roof-coating-application","title":"Roof Coating Application","category":"installation","type":"article","summary":"Roof coating application cleans, repairs and primes an existing roof, then sprays or rolls on a liquid membrane such as acrylic, silicone or polyurethane.","body":"A **roof coating** is a fluid-applied layer that cures into a continuous, elastic film over an existing roof or new substrate. Coatings are used to protect spray foam, extend the life of ageing low-slope roofs, reflect sunlight (cool roofs) and seal metal roofs. Common chemistries include **acrylic**, **silicone**, **polyurethane**, **polyurea**, **butyl**, **styrene-butadiene** and bitumen-based coatings.\n\n## Suitability\n\nNot every roof is a candidate. The existing system must be mostly dry and structurally sound, since coating over wet insulation traps moisture. Some coatings are not rated for ponding water; acrylics generally are not, while some silicone and polyurethane coatings are warranted for it by their manufacturers. Coating asphalt shingles and certain built-up roofs is generally discouraged, because the coating can trap moisture or may not be compatible.\n\n## Typical sequence\n\n1. **Survey.** Check for wet areas (often with infrared or moisture meters), blisters, open seams and failed flashings.\n2. **Clean.** Pressure-wash to remove dirt, chalking and biological growth, and allow to dry.\n3. **Repair.** Replace wet insulation, reseal seams, reset fasteners on metal roofs and treat rust.\n4. **Prime** where required for adhesion or to block bleed-through from bitumen.\n5. **Reinforce details.** Apply fabric-reinforced coating or seam sealers at seams, flashings, drains and penetrations.\n6. **Apply the field coats** by airless spray, roller or brush, in one or more coats to the specified thickness.\n7. **Check thickness.** Wet film thickness is measured during application, and dry film thickness after curing.\n\n## Thickness\n\nCoatings range from about 0.075 mm (3 mils) to more than 1 mm (40 mils) dry film thickness, depending on the product and the warranty term sought. Thickness, not the number of gallons applied, determines performance.\n\n## Weather limits\n\nEach product has limits for air and surface temperature, humidity, dew point and time before rain. Water-based acrylics are sensitive to cold and rain during cure; solvent-based and moisture-cure products have their own restrictions. Manufacturers' data sheets set these limits.\n\n## Maintenance\n\nCoatings are renewable: many systems are designed to be cleaned and recoated at intervals to restore thickness and reflectivity.","key_facts":[{"label":"Common types","value":"Acrylic, silicone, polyurethane, polyurea"},{"label":"Dry film thickness range","value":"About 0.075 mm (3 mils) to over 1 mm (40 mils)"},{"label":"Methods","value":"Airless spray, roller, brush"}],"regions":["Global"],"aliases":["roof coating installation","liquid-applied roofing","fluid-applied membrane","cool roof coating application"],"related":["spray-polyurethane-foam-application","cool-roof","low-slope-roof","roof-coating"],"company":null,"sources":[{"title":"Roof coating","url":"https://en.wikipedia.org/wiki/Roof_coating","publisher":"Wikipedia"},{"title":"Canadian Roofing Reference Manual: 13.1.2 Potential Problem Areas","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/canadian-roofing-reference-manual-chapter-13-troubleshooting-and-repairs/13-1-identify-cause-of-problem/13-1-2-potential-problem-areas/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"roof-coatings-manufacturers-association","title":"Roof Coatings Manufacturers Association (RCMA)","summary":"RCMA is a U.S. trade association for manufacturers of roof coatings and their suppliers, providing technical and regulatory information.","body":"The Roof Coatings Manufacturers Association (RCMA) is a trade association in the United States representing manufacturers of roof coatings and their suppliers, with contractor members as well. It lists an address in Ontario, New York, and its website is roofcoatings.org.\n\n## What roof coatings are\n\nRoof coatings are liquid-applied materials that form a protective layer on an existing or new roof. Main types include:\n\n- **acrylic** coatings, water-based and often white for reflectivity;\n- **silicone** coatings, which resist ponding water and weathering;\n- **polyurethane** and **polyurea** coatings;\n- **asphalt and bitumen-based** coatings, including aluminium-pigmented products;\n- **SEBS** and other rubber-based products.\n\nCoatings are used to restore and extend the life of low-slope roofs such as metal, modified bitumen, built-up and single-ply roofs, and to create reflective \"cool roof\" surfaces.\n\n## Activities\n\n- **Technical affairs.** RCMA committees work on technical issues such as test methods, product standards and application guidance.\n- **Government affairs.** The association tracks regulations affecting coatings, especially limits on volatile organic compounds (VOCs), which vary by state and air district. It publishes VOC maps for its members and the public.\n- **Education.** It runs a virtual training program on roof coatings.\n- **Events and awards.** RCMA holds a spring meeting, promotes an International Roof Coatings Day and presents a Project of the Year award.\n- **Communications** through news and technical resources.\n\n## Context\n\nReflective coatings are often listed with the Cool Roof Rating Council, which measures solar reflectance and thermal emittance. Building energy codes in hot climates may require reflective roof surfaces, which has increased the use of coatings. Coatings are not suitable for every roof: wet insulation, failed seams or severe deterioration usually need repair or replacement before coating. Outside North America, liquid-applied roofing is represented by groups such as the UK's Liquid Roofing and Waterproofing Association.","key_facts":[{"label":"Country","value":"United States"},{"label":"Members","value":"Coating manufacturers, suppliers and contractors"},{"label":"Address","value":"Ontario, New York"},{"label":"Known for","value":"VOC regulation tracking; International Roof Coatings Day"}],"regions":["North America"],"aliases":["RCMA"],"related":["roof-coating","cool-roof-rating-council","liquid-roofing-and-waterproofing-association","silicone-roof-coating"],"company":{"headquarters":"Ontario, New York, USA","website":"https://www.roofcoatings.org","known_for":["Roof coatings technical and regulatory information"]},"sources":[{"title":"About RCMA","url":"https://www.roofcoatings.org/about","publisher":"Roof Coatings Manufacturers Association"},{"title":"About the CRRC","url":"https://coolroofs.org/about","publisher":"Cool Roof Rating Council"}],"category":"organizations","type":"organization","country":null},{"slug":"roof-deck","title":"Roof Deck (Low-Slope)","category":"low-slope-systems","type":"article","summary":"The structural surface that supports a low-slope roof assembly, commonly steel, concrete, wood, poured gypsum or cementitious wood fibre.","body":"The roof deck is the structural layer that spans between beams, joists or purlins and carries the roofing assembly, snow, rain and equipment loads. It is the only structural component of a typical low-slope roof; everything above it, from vapour retarder to membrane, is non-structural. Deck type affects how insulation and membranes can be attached, fire ratings, drainage and condensation control.\n\n## Steel deck\n\nCold-formed corrugated steel decking is the most common deck for commercial low-slope roofs in North America. Insulation and membranes are mechanically fastened into the steel ribs or adhered over a board. Steel decks are light and quick to erect but flexible, so deflection must be considered in drainage design. The US Steel Deck Institute, formed in 1939, publishes design and manufacturing standards.\n\n## Concrete deck\n\nCast-in-place or precast concrete slabs are heavy, stiff and non-combustible. They are standard for inverted roofs, podiums, green and blue roofs and multi-storey residential buildings. In the UK, zero-fall inverted roofs under one warranty provider's policy are accepted only on in-situ reinforced concrete or rib-deck. Falls are often formed with screeds. New concrete releases moisture, so vapour control and drying time matter.\n\n## Wood deck\n\nPlywood, OSB or solid timber boards on joists or glulam beams are typical on houses, extensions and smaller buildings. In the UK, falls are often formed with firring strips. Timber decks must be kept dry; BS 6229:2025 advises avoiding cross-laminated timber (CLT) roof decks where possible and sets conditions, including a minimum finished fall of 1:40, where they are used.\n\n## Poured gypsum deck\n\nGypsum concrete poured over formboards on bulb-tee sub-purlins was used on many North American roofs in the twentieth century. It is lightweight and fire-resistant but sensitive to prolonged wetting, and fastener pull-out must be tested in reroofing.\n\n## Cementitious wood fibre deck\n\nPanels of wood wool or wood fibre bound with cement or magnesite have been made in Europe since the early twentieth century and were widely produced by 1930. They serve as roof deck, insulation and acoustic ceiling in one, and are common on schools, gymnasiums and pools. Fasteners and adhesives must be specifically approved for them.","key_facts":[{"label":"Most common commercial deck (N. America)","value":"Steel"},{"label":"Steel Deck Institute formed","value":"1939"},{"label":"Usual inverted/green roof deck","value":"Concrete"},{"label":"BS 6229:2025 CLT minimum fall","value":"1:40"}],"regions":["Global"],"aliases":["roof decking","structural deck","steel roof deck","concrete roof deck"],"related":["vapor-retarder","mechanically-attached-roof-system","positive-drainage","protected-membrane-roof"],"company":null,"sources":[{"title":"Built-Up Roofing (BUR): What It Is, Types, Issues & More","url":"https://roofonline.com/built-up-roofing-introduction/","publisher":"RoofOnline"},{"title":"Steel Deck Institute","url":"https://www.sdi.org/","publisher":"Steel Deck Institute"},{"title":"Flat roof","url":"https://www.designingbuildings.co.uk/wiki/Flat_roof","publisher":"Designing Buildings Wiki"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"},{"title":"Major Projects: Zero falls flat roof policy","url":"https://labcwarranty.co.uk/blog/major-projects-zero-falls-flat-roof-policy/?hsLang=en","publisher":"LABC Warranty"},{"title":"Wood wool","url":"https://en.wikipedia.org/wiki/Wood_wool","publisher":"Wikipedia"}],"country":null},{"slug":"roof-deck-inspection-and-replacement","title":"Roof Deck Inspection and Replacement","category":"installation","type":"article","summary":"Deck inspection is the check of the structural roof surface for rot, deflection, gaps and fastening before new roofing is installed; damaged sections are replaced.","body":"The **roof deck** is the structural surface that the roofing system is fastened to. It may be timber boards, plywood, oriented strand board (OSB), profiled steel or concrete. Because the roof covering can only perform as well as the surface beneath it, the deck is inspected before any new roofing is installed, and damaged areas are repaired or replaced.\n\nCanadian guidance says the deck should be visually inspected before roofing starts, deficiencies recorded and reported, and work held until they are corrected. Structural adequacy is a matter for a professional engineer, but roofers are expected to flag weak areas.\n\n## What is checked\n\n- **Moisture and rot.** The deck must be clean and thoroughly dry. Soft, stained or rotted boards and delaminated panels are replaced.\n- **Deflection.** Sagging, bounce or unusual movement can indicate undersized or damaged framing.\n- **Fastening.** Panels should be fastened at their edges and over supports. US Building America guidance for retrofits recommends re-nailing the deck to current requirements during a tear-off.\n- **Gaps and knotholes.** For board decks, the Canadian Roofing Reference Manual sets a maximum gap of 6 mm (1/4 in); larger gaps or knotholes are covered with sheet metal.\n- **Openings and curbs.** Openings should be framed so they do not deflect, and curbs should be in place before roofing.\n\n## Deck types\n\n| Deck | Key checks (Canadian guidance) |\n|---|---|\n| Plywood | Approved grade; typically at least 15.9 mm (5/8 in) for most low-slope uses; all edges supported |\n| Board | At least 19 mm (3/4 in) thick, no wider than 150 mm (6 in), fastened on both edges |\n| Steel | Fastened or welded to supports, flutes clean and dry, no concentrated loads |\n| Concrete | Smooth, dry surface; precast joints grouted; level differences treated |\n\n## Replacement\n\nDuring a tear-off, damaged sheathing is cut back to the nearest supports and replaced with panels of matching thickness so the new roof lies flat. Some programmes for high-wind regions also recommend sealing deck seams with tape or a self-adhered membrane before underlayment is laid. On homes with spaced board decks under old wood shakes, solid sheathing is often added before asphalt or metal roofing is installed.\n\nSome building departments do not judge whether sheathing is structurally sound; Bloomington, Minnesota, for example, leaves that decision to the contractor, engineer or homeowner.","key_facts":[{"label":"Maximum board gap (Canada)","value":"6 mm (1/4 in)"},{"label":"Minimum plywood, most low-slope uses (Canada)","value":"15.9 mm (5/8 in)"},{"label":"Deck condition required","value":"Clean, continuous, thoroughly dry"}],"regions":["Global"],"aliases":["sheathing replacement","decking inspection","roof sheathing"],"related":["roof-replacement-process","tear-off-vs-overlay","underlayment-installation","roof-deck"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 3.1.3 Inspection of Roof Deck","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-3-roofing-preparation/3-1-roof-deck-preparation/3-1-3-inspection-of-roof-deck/","publisher":"Canadian Roofing Contractors Association"},{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"},{"title":"Reroofing","url":"https://www.bloomingtonmn.gov/sites/default/files/2023-08/Reroofing.pdf","publisher":"City of Bloomington, Minnesota"}],"country":null},{"slug":"roof-drain","title":"Roof Drain (Internal Drain)","category":"low-slope-systems","type":"term","summary":"An outlet set into the field of a low-slope roof that collects rainwater and carries it down through pipes inside the building.","body":"A roof drain, called a rainwater outlet in the UK, is a fitting installed in the roof surface, usually at a low point, that collects water and conducts it into a leader or downpipe running through the building. Internal drains let large roofs drain without needing every slope to reach the perimeter.\n\n## Components\n\n- **Drain body or bowl** set into or onto the deck\n- **Clamping ring or flange** that grips the membrane, or a spigot outlet welded or bonded to it\n- **Strainer or dome** that keeps out gravel and leaves\n- **Sump** formed in the insulation or deck so the outlet sits below the surrounding roof surface\n\n## Placement and number\n\nDrains go at the lowest points of the roof, after allowing for deflection: on steel and timber decks the low point is often at mid-span, not at columns. UK guidance recommends at least two outlets on even small roofs, or an outlet plus overflow, so a single blockage cannot flood the roof. Outlets are recessed or set in sumps to avoid ponding caused by membrane laps building up around them. BS 6229:2025 limits sumps to about 0.72 m2 (7.8 sq ft) per outlet, between 400 mm and 1,200 mm (16-47 in) across, and internal gutters linking outlets should be at least 500 mm (20 in) wide.\n\n## Sizing\n\nDrain and pipe sizes depend on rainfall intensity and the roof area served. In the UK and Europe calculations follow BS EN 12056-3; in the US they follow the plumbing code. Siphonic systems, which run pipes full to create suction, are used on very large roofs.\n\n## Maintenance\n\nBlocked drains are a leading cause of ponding and of structural overload. Strainers should be cleared during routine inspections, typically in spring and autumn and after storms.","key_facts":[{"label":"UK term","value":"Rainwater outlet"},{"label":"Recommended minimum (UK)","value":"Two outlets, or outlet plus overflow"},{"label":"BS 6229:2025 sump limit","value":"About 0.72 m2 per outlet"},{"label":"Sizing standard (UK/EU)","value":"BS EN 12056-3"}],"regions":["Global"],"aliases":["rainwater outlet","internal drain","roof outlet","primary drain"],"related":["overflow-drainage","scupper","positive-drainage","tapered-insulation","ponding-water"],"company":null,"sources":[{"title":"Falls and drainage","url":"https://www.bauder.co.uk/roof-systems/refurbishment-projects/solving-the-challenge/improving-drainage-falls","publisher":"Bauder"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"},{"title":"Major Projects: Zero falls flat roof policy","url":"https://labcwarranty.co.uk/blog/major-projects-zero-falls-flat-roof-policy/?hsLang=en","publisher":"LABC Warranty"},{"title":"How to avoid ponding on flat roofs","url":"https://www.specifiedby.com/soprema-uk/news/how-to-avoid-ponding-on-flat-roofs","publisher":"Soprema UK via SpecifiedBy"}],"country":null},{"slug":"roof-drainage-design","title":"Roof Drainage Design","type":"article","summary":"Planning slopes, gutters, drains, scuppers and overflows so that a roof sheds rain quickly, including during intense storms.","body":"Roof drainage design is the planning of slopes and outlets so that rainwater leaves a roof quickly and safely. Good drainage protects the roof covering, limits leaks, prevents overloading and directs water away from walls and foundations. It becomes more critical as heavy downpours grow more intense in many regions.\n\n## How much water a roof collects\n\nEvery millimetre of rain on one square metre of roof produces about one litre of water. In imperial units, about 0.62 US gallons fall on each square foot of roof per inch of rain. A 200 m² (about 2,150 sq ft) roof receiving 50 mm (2 in) of rain therefore sheds roughly 10,000 litres (about 2,650 US gallons).\n\n## Steep-slope roofs\n\nPitched roofs shed water by gravity into gutters along the eaves and then into downspouts (downpipes). Design considers:\n\n- gutter size and fall toward outlets;\n- number and size of downspouts relative to the roof area served;\n- valleys, which concentrate flow and need wider flashings;\n- overflow paths so that blocked gutters spill outward, not into walls or soffits.\n\n## Low-slope roofs\n\nFlat roofs are never truly flat. Commercial membranes usually sit at slopes of about 1 to 3 degrees, created by structural slope or tapered insulation. Water is removed by:\n\n- **Internal roof drains** connected to piping inside the building;\n- **Scuppers** through parapets at the roof edge;\n- **Gutters** at open edges;\n- **Crickets and saddles** that divert water around curbs and toward outlets.\n\nPlumbing codes such as Chapter 11 of the International Plumbing Code in the United States size drains and leaders using design rainfall intensity maps and require secondary (emergency overflow) drains or scuppers where parapets could trap water if primary drains block. Other countries use their own national drainage standards and rainfall data.\n\n## Why redundancy matters\n\nLeaves, gravel and debris can clog outlets. Water that cannot escape builds up, adding dead load the structure may not be designed to carry and driving water into small defects. Secondary drainage set slightly above the primary level gives water an escape route.\n\n## Maintenance\n\nInspecting and cleaning gutters, drains and strainers, especially after autumn leaf fall and before storm seasons, is one of the most effective roof maintenance tasks.","key_facts":[{"label":"Volume rule","value":"1 mm of rain on 1 m² = about 1 litre"},{"label":"Imperial equivalent","value":"About 0.62 US gal per sq ft per inch of rain"},{"label":"Typical low-slope membrane slope","value":"About 1-3 degrees"},{"label":"Key safety feature","value":"Secondary (overflow) drains or scuppers"}],"regions":["Global"],"aliases":["roof drainage","storm drainage","rainwater drainage"],"related":["ponding-water","rain-gutter","scupper","rainwater-harvesting-roofs","blue-roof","climate-change-and-roofing"],"sources":[{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"},{"title":"The Texas Manual on Rainwater Harvesting, Third Edition","url":"https://www.twdb.texas.gov/publications/brochures/conservation/doc/RainwaterHarvestingManual_3rdedition.pdf","publisher":"Texas Water Development Board"},{"title":"2021 International Plumbing Code, Chapter 11 Storm Drainage","url":"https://codes.iccsafe.org/content/IPC2021P1/chapter-11-storm-drainage","publisher":"International Code Council"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roof-flashing","title":"Roof Flashing","category":"components","type":"article","summary":"Roof flashing is thin sheet metal or membrane installed at joints, edges and penetrations to direct water away from places where the roof covering is interrupted.","body":"Flashing is a thin, impervious material, usually sheet metal, installed wherever the roof covering meets something else: a wall, a chimney, a skylight, a vent pipe, another roof plane or the roof edge. Roof coverings shed water well across open slopes, but joints and interruptions are where most leaks begin, and flashing bridges those gaps by lapping water outward and downward in the same way shingles or tiles do.\n\n## Materials\n\nTraditional and modern flashing materials include lead, copper, zinc, aluminium, galvanised and coated steel, and stainless steel, along with flexible products such as rubberised asphalt, butyl and other membranes. Before manufactured sheet flashing, builders relied on careful shingle placement, mortar fillets and chimneys built at the ridge; lead flashing details appear in builders' handbooks by 1832.\n\nUS residential code generally requires metal flashing to be corrosion-resistant and at least 0.019 in (0.48 mm) thick, roughly 26-gauge galvanised steel.\n\n## Main types\n\n- **Step flashing (soakers):** individual pieces interleaved with each course at a roof-to-sidewall junction.\n- **Counter-flashing (cap or cover flashing):** fixed into or onto the wall to cover the top of base or step flashing.\n- **Apron (headwall) flashing:** a continuous piece where the top of a roof slope meets a wall, or across the lower face of a chimney.\n- **Valley flashing:** lines the internal angle where two slopes meet.\n- **Drip edge:** formed metal at eaves and rakes.\n- **Kickout flashing:** diverts water away from the wall at the bottom of a roof-wall junction.\n- **Pipe boots:** collars around vent pipes and other round penetrations.\n- **Reglet:** a groove cut into masonry to receive the top edge of a flashing.\n\n## Compatibility\n\nDissimilar metals can corrode each other. Copper and lead should not touch, or drain onto, aluminium, zinc or coated steel. Aluminium and zinc are attacked by contact with treated timber and by wet mortar. In coastal areas, salt spray speeds corrosion, so more resistant metals are commonly specified.","key_facts":[{"label":"US minimum metal thickness","value":"0.019 in (0.48 mm)"},{"label":"Common metals","value":"Lead, copper, zinc, aluminium, steel"},{"label":"Lead flashing in handbooks","value":"By 1832"}],"regions":["Global"],"aliases":["flashing","flashings","roof flashings"],"related":["step-flashing","counter-flashing","apron-flashing","chimney-flashing","kickout-flashing","pipe-boot","drip-edge","roof-valley","lead-soakers"],"company":null,"sources":[{"title":"Flashing (weatherproofing)","url":"https://en.wikipedia.org/wiki/Flashing_(weatherproofing)","publisher":"Wikipedia"},{"title":"Step and Kick-Out Flashing at Roof-Wall Intersections","url":"https://basc.pnnl.gov/resource-guides/step-and-kick-out-flashing-roof-wall-intersections","publisher":"Building America Solution Center (PNNL / US DOE)"},{"title":"Chimneys & Crickets, Skylights, Pipes, Flues, Exhaust Vents & Solar","url":"https://open-exam-prep.com/study-guides/mi-roofing-contractor/flashings-penetrations/chimney-crickets-skylights-penetrations","publisher":"Open Exam Prep"}],"country":null},{"slug":"storm-damage-inspection","title":"Roof Inspection After Storms","category":"problems-maintenance","type":"article","summary":"How to check a roof safely after wind, hail or heavy rain, document damage, and arrange temporary protection and professional assessment.","body":"After a severe storm, a quick, safe check of the roof helps limit further damage and supports any insurance claim. The priority is personal safety: storms can leave downed power lines, unstable trees, and roofs that are wet, damaged or covered in debris. Most guidance advises homeowners not to climb onto a roof after a storm, but to inspect from the ground and the attic and leave rooftop work to professionals.\n\n## From the ground\n\n- Look for missing, lifted or creased shingles; slipped or broken tiles and slates; displaced ridge caps; and peeled-back metal edges.\n- Check for fallen branches on the roof and damaged chimneys, antennas or solar arrays.\n- Look at gutters, downpipes, vents, air-conditioning units and outdoor fixtures for dents, which can indicate hail size and direction.\n- Note debris such as granules, pieces of roofing or flashing on the ground.\n- Use binoculars or a camera zoom; a drone flown legally can help.\n\n## Inside\n\n- Check ceilings and walls for new stains or drips.\n- Inspect the attic with a torch for wet sheathing, light showing through, and damp insulation.\n- Protect belongings from active leaks and turn off electricity to wet areas if safe.\n\n## Documenting\n\nTake dated photographs and videos of all damage, outside and inside, before cleaning up. Keep receipts for emergency repairs and temporary protection. Contact the insurer promptly, as policies usually require timely notice and reasonable steps to prevent further damage.\n\n## Temporary protection\n\nEmergency tarping or boarding can stop water entry until permanent repairs are made. In the United States, federally declared disasters may activate the US Army Corps of Engineers' Operation Blue Roof programme for eligible homes.\n\n## Choosing help\n\nAfter major events, unsolicited contractors often canvass affected areas. Consumer and extension guidance commonly advises checking licensing and insurance, getting written estimates, avoiding large upfront payments, and being wary of anyone offering to waive deductibles. An independent inspection, separate from the contractor doing the work, can help distinguish storm damage from pre-existing wear.","key_facts":[{"label":"Safety rule","value":"Inspect from ground and attic; avoid climbing damaged roofs"},{"label":"Evidence","value":"Dated photos before clean-up"},{"label":"Watch for","value":"Unlicensed door-to-door contractors"}],"regions":["Global"],"aliases":["post-storm roof inspection","storm damage check","hurricane roof inspection"],"related":["wind-damage","hail-damage","emergency-roof-tarping","roof-insurance-claims","drone-roof-inspection"],"company":null,"sources":[{"title":"Post-storm damage control","url":"https://certainteed.ca/inspiration/how-tos/post-storm-damage-control","publisher":"CertainTeed"},{"title":"Is It Hail Damage?","url":"https://ibhs.org/is-it-hail-damage/","publisher":"Insurance Institute for Business & Home Safety"},{"title":"Call insurance adjuster to determine hail damage","url":"https://extension.missouri.edu/news/call-insurance-adjuster-to-determine-hail-damage","publisher":"University of Missouri Extension"},{"title":"Best practices to assess roof damage in hurricane-prone states","url":"https://www.rooferscoffeeshop.com/post/best-practices-to-assess-roof-damage-in-hurricane-prone-states","publisher":"RoofersCoffeeShop"}],"country":null},{"slug":"roof-inspection-procedure","title":"Roof Inspection Procedure","category":"installation","type":"article","summary":"A roof inspection is a systematic check of the covering, flashings, penetrations, drainage, deck and attic to find damage, defects and leak sources.","body":"A **roof inspection** is a structured examination of a roof to record its condition, find defects and identify the causes of leaks. Inspections are carried out by roofers before quoting, by home inspectors during property sales, by insurers after storms and by building owners as routine maintenance. The scope and access methods differ: a general home inspection may be done from the ground or eaves, while a roofing contractor or consultant usually walks the roof where it is safe.\n\n## Scope of a home inspection\n\nThe InterNACHI Standards of Practice, widely used in North America, require an inspector to inspect roof coverings, gutters and downspouts, vents, flashings, skylights, chimneys and other penetrations and the general roof structure from accessible openings. Inspectors must describe the roof covering type and report observed signs of active leaks. They are not required to walk on the roof, predict remaining service life, perform water tests or confirm that coverings were properly fastened.\n\n## Typical procedure\n\n1. **Plan and set up safely.** Review history and previous repairs, check weather and arrange fall protection and ladder access.\n2. **Ground and perimeter.** Look at roof lines for sagging, check gutters, downspouts and fascia, and view slopes with binoculars or a drone.\n3. **Roof surface.** Check the covering for missing, cracked, curled or slipped units, granule loss, blisters, splits, open seams, ponding and loose fasteners.\n4. **Flashings and penetrations.** Examine valleys, step and apron flashings, chimneys, skylights, vent boots and edge metal.\n5. **Drainage.** Confirm gutters, scuppers, drains and downspouts are clear and correctly sloped.\n6. **Attic or interior.** Look for stains, daylight, damp insulation, mould, frost and ventilation problems.\n7. **Record.** Photograph and mark defects, then summarise findings and recommendations.\n\n## Common problem areas\n\nCanadian guidance lists the following as frequent problem areas: separated or deteriorating flashings at penetrations; blisters, fishmouths, ridges and alligator cracking on bituminous membranes; scouring of ballast or granules; splits at gravel stops; popped fasteners and poor seams on single-ply membranes (checked with a seam probe); poorly installed valleys and roof jacks; blocked eavestroughs; condensation stains; and backed-out fasteners on shingle and exposed-fastener metal roofs.\n\n## Frequency\n\nCanadian guidance recommends repairing potential problems as soon as they are found and setting up a preventive maintenance schedule. Inspections after major storms, and before buying a property or renewing insurance, are also common practice.","key_facts":[{"label":"Home inspection standard","value":"InterNACHI Standards of Practice (roof section)"},{"label":"Walking roof required (InterNACHI)","value":"No"},{"label":"Key areas","value":"Flashings, penetrations, valleys, drainage, attic"}],"regions":["Global"],"aliases":["roof survey","roof condition assessment","roof check"],"related":["seam-probing","roofing-fall-protection","plumbing-vent-flashing"],"company":null,"sources":[{"title":"InterNACHI Home Inspection Standards of Practice","url":"https://www.nachi.org/sop.htm","publisher":"InterNACHI"},{"title":"Canadian Roofing Reference Manual: 13.1.2 Potential Problem Areas","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/canadian-roofing-reference-manual-chapter-13-troubleshooting-and-repairs/13-1-identify-cause-of-problem/13-1-2-potential-problem-areas/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"roof-insurance-depreciation","title":"Roof Insurance and Depreciation","type":"article","summary":"How property insurers value roofs by age and condition, including actual cash value versus replacement cost settlements.","body":"Property insurance is one of the main ways homeowners pay for roof damage from hail, wind and other perils. How a roof claim is paid depends heavily on the policy's valuation method and on the roof's age and condition.\n\n## Replacement cost versus actual cash value\n\n- **Replacement cost value (RCV):** the current cost to replace the damaged roof with a new one of like kind and quality.\n- **Actual cash value (ACV):** replacement cost minus depreciation. Depreciation reflects how much of the item's useful life has been used.\n\nFor example, if a roof expected to last 20 years is 10 years old, an ACV settlement may pay roughly half the replacement cost, before the deductible. Policies can apply different valuation methods to different parts of a property.\n\n## Roof payment schedules\n\nIn some US markets, especially those with frequent hail, insurers have introduced roof payment schedules or roof-only ACV endorsements. These reduce the payout for roof damage according to a table based on roof age and material, even when the rest of the house is insured at replacement cost. Owners of older roofs may therefore receive much less than the cost of a new roof.\n\n## Age-based underwriting\n\nInsurers may decline to write new policies, require inspections, or charge more for older roofs, because aged roofing is more vulnerable to wind and hail and more likely to leak. Florida's property insurance reforms, including SB 2-A signed on December 16, 2022, addressed several aspects of residential property claims; owners should consult current state rules on how roof age can be used.\n\n## Cosmetic damage\n\nSome policies, particularly in hail-prone states, exclude or limit cosmetic damage, such as dents to metal roofing that do not affect function. Inspectors and adjusters distinguish functional damage (which shortens service life or allows leaks) from cosmetic damage.\n\n## Why it matters\n\nHail claims are a large share of US property losses; one large insurer reported paying more than $5.6 billion in hail claims in 2025. As a result, roof age, material and impact rating increasingly affect insurance availability and price.\n\n## What owners can do\n\n- Read the policy's roof valuation terms, deductibles (including separate wind or hail deductibles) and cosmetic damage exclusions.\n- Keep records of roof installation date, materials and permits.\n- Document roof condition with photographs.\n- Ask about discounts for impact-rated or FORTIFIED roofs where available.","key_facts":[{"label":"RCV","value":"Cost to replace with new"},{"label":"ACV","value":"Replacement cost minus depreciation"},{"label":"Common hail-market tool","value":"Roof payment schedules by age and material"}],"regions":["North America"],"aliases":["roof depreciation","ACV roof coverage","roof payment schedule","roof age insurance"],"related":["roof-insurance-discounts","hail-damage","fortified-roof","impact-resistance-rating"],"sources":[{"title":"Actual cash value","url":"https://en.wikipedia.org/wiki/Actual_cash_value","publisher":"Wikipedia"},{"title":"Facts + Statistics: Hail","url":"https://www.iii.org/fact-statistic/facts-statistics-hail","publisher":"Insurance Information Institute"},{"title":"SB 2-A (2022A): Property Insurance","url":"https://www.flsenate.gov/Session/Bill/2022A/2A","publisher":"The Florida Senate"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roof-insurance-claims","title":"Roof Insurance Claims","category":"problems-maintenance","type":"article","summary":"A neutral overview of how property insurance claims for roof damage generally work, including coverage types, depreciation and documentation.","body":"Roof damage from sudden events such as windstorms, hail, falling trees or fire is often covered by property insurance, while wear, age, neglect and poor installation usually are not. Policy terms vary widely by insurer, country and region, so the policy wording and the insurer's guidance always take precedence over general descriptions.\n\n## Coverage types\n\nIn North America, two settlement bases are common:\n\n- **Replacement cost value (RCV)** pays to repair or replace damaged property without deducting depreciation, after the deductible.\n- **Actual cash value (ACV)** deducts depreciation, which reflects the roof's age and condition, so payments on older roofs can be much lower.\n\nThe US National Association of Insurance Commissioners gives an example in which the same damage results in a far smaller ACV payment than an RCV payment because of depreciation. Some policies apply ACV to roofs above a certain age, use a payment schedule tied to roof age, or settle in stages, paying the depreciation portion after the work is complete.\n\n## Deductibles and exclusions\n\nPolicies may carry separate deductibles for wind, hurricane or hail, sometimes set as a percentage of the insured value. Some coastal policies exclude wind or hail altogether, requiring separate coverage. Cosmetic damage, such as dents on metal that do not affect function, may be excluded under some policies.\n\n## Typical process\n\n1. **Make the property safe** and take reasonable steps to prevent further damage, such as tarping.\n2. **Document**: dated photos and video of the roof, interior damage and collateral damage such as dented gutters.\n3. **Notify the insurer promptly**; many policies set time limits.\n4. **Inspection** by an adjuster, sometimes with a roofer or engineer present.\n5. **Estimate and settlement** based on the policy terms.\n6. **Repairs**, sometimes followed by additional payments for code-required upgrades if the policy includes that coverage.\n\n## Disputes and caution\n\nDisagreements over cause (storm damage versus wear) are common. Options may include providing further evidence, independent inspections, appraisal provisions in the policy, or complaints to the insurance regulator. Consumer groups advise caution with contractors who offer to cover deductibles or ask owners to sign over claim rights.","key_facts":[{"label":"RCV","value":"Repair or replacement without depreciation"},{"label":"ACV","value":"Payment reduced by depreciation"},{"label":"Commonly excluded","value":"Wear, age, neglect, poor installation"}],"regions":["Global","North America"],"aliases":["roof insurance claim","hail claim","wind claim"],"related":["storm-damage-inspection","hail-damage","wind-damage","emergency-roof-tarping","roof-age-estimation"],"company":null,"sources":[{"title":"Rebuilding after a storm? Know the difference between replacement cost and actual cash value","url":"https://content.naic.org/article/rebuilding-after-storm-know-difference-between-replacement-cost-and-actual-cash-value-when-it-comes","publisher":"National Association of Insurance Commissioners"},{"title":"Roof insurance: ACV versus replacement cost","url":"https://uphelp.org/roof-insurance-acv-versus-replacement-cost/","publisher":"United Policyholders"},{"title":"How to file a home insurance claim for roof damage","url":"https://www.policygenius.com/homeowners-insurance/roof-damage-insurance-claim/","publisher":"Policygenius"}],"country":null},{"slug":"roof-insurance-discounts","title":"Roof Insurance Discounts","type":"article","summary":"Premium credits some insurers give for roofs built to resist wind or hail, such as FORTIFIED designations, wind mitigation features and Class 4 coverings.","body":"Roof insurance discounts are reductions in property insurance premiums offered for roofs and roof features that reduce expected losses. They are most common in US states exposed to hurricanes and hail, where roof damage drives a large share of claims.\n\n## Types of discounts\n\n- **Wind mitigation credits.** In Florida, wind mitigation inspections record features such as roof covering type and code compliance, roof deck attachment, roof-to-wall connection type (toenail, clip, single wrap, double wrap), roof shape (hip versus gable), secondary water resistance and opening protection. Insurers use these reports to apply premium credits for qualifying features.\n- **FORTIFIED designations.** In Alabama, homes with a FORTIFIED designation from the Insurance Institute for Business & Home Safety receive a discount on the wind portion of their homeowner's premium from admitted insurers; surplus lines carriers are not required to do so.\n- **Impact-resistant roofing.** In some hail-prone states, insurers offer discounts for coverings rated UL 2218 Class 4 (or FM 4473 Class 4 for tile).\n- **New roof credits.** Some insurers price policies by roof age, effectively rewarding newer roofs.\n\n## Grants\n\nSome states pair discounts with grants. The Strengthen Alabama Homes program has offered grants paying 100 percent of mitigation costs up to $10,000 for homes that reach the FORTIFIED Roof standard.\n\n## How to qualify\n\nDiscounts usually require documentation:\n\n- a wind mitigation inspection report by a qualified inspector;\n- a FORTIFIED certificate issued after third-party evaluation;\n- product labels, invoices or permits showing an impact-rated product.\n\n## Considerations\n\n- Discount amounts and rules vary by state, insurer and policy, and may change.\n- Class 4 discounts may come with cosmetic damage exclusions for the same roof.\n- Lab ratings describe new products; real-world performance depends on installation and aging.\n\n## Why insurers offer them\n\nStudies of storm damage, such as investigations after Hurricanes Andrew (1992) through Michael (2018), show that stronger roof attachment, sealed decks and improved edges reduce losses. Discounts aim to reflect that lower risk and encourage owners to invest in mitigation.","key_facts":[{"label":"Florida","value":"Wind mitigation credits based on inspection"},{"label":"Alabama","value":"FORTIFIED discount on wind premium (admitted insurers)"},{"label":"Strengthen Alabama Homes grant","value":"Up to $10,000"},{"label":"Hail markets","value":"Discounts for Class 4 impact-rated coverings"}],"regions":["North America"],"aliases":["wind mitigation discount","FORTIFIED discount","Class 4 insurance discount","hail-resistant roof discount"],"related":["fortified-roof","roof-insurance-depreciation","impact-resistance-rating","roof-to-wall-connection","sealed-roof-deck"],"sources":[{"title":"Strengthen Alabama Homes","url":"https://strengthenalabamahomes.com/","publisher":"Alabama Department of Insurance"},{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/?p=2512","publisher":"Insurance Institute for Business & Home Safety (FORTIFIED Home)"},{"title":"Hurricane Mitigation Techniques, Proposed IBHS Language","url":"https://www.floridabuilding.org/fbc/thecode/Hurri_Mit_Techniq_compar_1207_ibhs.htm","publisher":"Florida Building Commission"},{"title":"Roof Hail Impact Resistance","url":"https://roofobservations.com/roof-hail-impact-resistance/","publisher":"Roof Observations"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roof-jacks","title":"Roof Jacks and Toe Boards","category":"tools-equipment","type":"term","summary":"Metal brackets nailed to a pitched roof to hold planks that give roofers footing and catch materials; toe boards are the planks or cleats they support.","body":"Roof jacks, also called roof brackets or staging brackets, are steel brackets fastened through the roof sheathing into the framing to support a horizontal plank. The plank, often called a toe board, gives roofers a level place to stand, stops materials and tools from sliding off, and provides a work platform on steep roofs. Simpler toe boards may be timber battens nailed directly to the roof.\n\n## Types\n\n- **Fixed-angle brackets** set the plank at a single angle.\n- **Adjustable brackets** can be set to level the plank on different slopes.\n- **Brackets with integral guardrail posts** support a temporary guardrail as well as a plank.\n\n## Installation practice\n\nGuidance in trade publications includes:\n\n- Fastening through the sheathing into rafters or trusses with suitable nails, such as 8d or 16d common nails, rather than short roofing nails, which can pull out or have heads that pop off.\n- Using the widest plank the bracket accepts; a 2 x 10 (about 38 x 235 mm) plank is preferred over narrower boards where it fits.\n- Planking that can support its own weight and at least four times the intended load, with limited deflection (one guideline is no more than 1/60 of the span).\n- Setting brackets about 6 to 12 in (150 to 300 mm) from plank ends so stepping on an overhang cannot tip the plank, and overlapping planks over a bracket on long runs.\n- Placing brackets so they are covered by the next course of shingles, then removing them by driving the bracket up off the nails and sealing or driving the nails flush.\n\n## Not fall protection on their own\n\nRoof jacks and toe boards help with footing and material control, but they are not fall protection in themselves. In the United States, OSHA requires fall protection for residential roofing work 6 ft (1.8 m) or more above a lower level, typically a personal fall arrest system tied to an anchor rated at 5,000 lb (about 22 kN) per worker, or guardrails or safety nets. OSHA interpretations address when roof brackets and slide guards may be part of a compliant system. Other countries set their own height thresholds and rules, often favouring scaffolding with edge protection on domestic roofs.","key_facts":[{"label":"Fastening","value":"8d or 16d common nails into framing, not roofing nails"},{"label":"Preferred plank","value":"2 x 10 where the bracket fits"},{"label":"Fall protection","value":"Still required; brackets alone are not enough"}],"regions":["Global","North America"],"aliases":["roof brackets","staging brackets","toe board","slide guard"],"related":["personal-fall-arrest-system","ladder-standoff","roofing-hoist","roofing-shovel"],"company":null,"sources":[{"title":"Roof Jack Safety","url":"https://www.jlconline.com/how-to/roofing/roof-jack-safety_o/","publisher":"Journal of Light Construction"},{"title":"Standard interpretation: roof brackets and slide guards","url":"https://osha.gov/laws-regs/standardinterpretations/2000-02-23","publisher":"OSHA"},{"title":"Fixed Roof Bracket","url":"https://guardianfall.com/product/fixed-roof-bracket/2502","publisher":"Guardian Fall Protection"},{"title":"Reducing Falls While Installing Tile Roofs","url":"https://www.osha.gov/sites/default/files/publications/reducing-falls-installing-tile-roofs-factsheet.pdf","publisher":"OSHA"}],"country":null},{"slug":"roof-leak-detection","title":"Roof Leak Detection","category":"problems-maintenance","type":"article","summary":"The process of tracing where water actually enters a roof, which is often some distance from where it appears inside the building.","body":"Roof leak detection is the work of finding the true entry point of water into a roof assembly. It is rarely as simple as looking above the ceiling stain: water can enter at a flashing, run along the top of the deck, a rafter or a sheet of underlayment, and drip out several metres away. A good diagnosis saves money because it targets the repair at the cause rather than at the symptom.\n\nMost leaks on pitched roofs start at interruptions in the covering rather than in the open field of shingles, tiles or panels. Penetrations, walls, chimneys, skylights, valleys and the roof edge are the usual suspects.\n\n## Where to look first\n\n- **Flashings** at chimneys, sidewalls, headwalls and dormers, including step flashing and counterflashing.\n- **Penetrations** such as plumbing vent boots, exhaust caps, satellite or solar mounts and skylight curbs.\n- **Valleys**, where large volumes of water concentrate and debris collects.\n- **Eaves**, where ice dams in cold climates can push water back under the covering.\n- **Damaged or missing units**: lifted or torn shingles, cracked tiles, slipped slates, backed-out screws on metal.\n- **Low-slope areas**: open seams, blisters, splits and ponding near drains.\n\n## Working from the inside\n\nIn an accessible attic, inspectors look for water stains, dark or wet sheathing, rusty nail tips and mould on the underside of the deck, then trace any trail uphill to its highest wet point. A torch in daylight can reveal pinholes of light through the deck. Stains that appear only in very cold weather may be condensation or frost melt rather than a roof leak, which needs a different fix (see attic condensation).\n\n## Water testing\n\nWhen visual checks fail, a controlled hose test is common: one person runs water on a small, low area of the roof while another watches inside, then the test moves slowly upslope one zone at a time. Testing from the bottom up avoids wetting areas that have not yet been checked. Professional investigators also use moisture meters, infrared cameras and, on low-slope membranes, electronic leak detection.\n\n## Safety and limits\n\nWet roofs are slippery, and steep or high roofs need fall protection. Homeowners can usually do the attic part safely; roof-top testing is often better left to a roofer or a roof consultant. Temporary measures such as a tarp can limit damage until the source is confirmed.","key_facts":[{"label":"Most common entry points","value":"Flashings, penetrations, valleys, roof edges"},{"label":"Typical test method","value":"Zone-by-zone hose test, working upslope"},{"label":"Advanced methods","value":"Moisture meters, infrared, electronic leak detection"}],"regions":["Global"],"aliases":["finding a roof leak","leak investigation","leak tracing"],"related":["flashing-failure","electronic-leak-detection","infrared-roof-thermography","attic-condensation","ice-dam","emergency-roof-tarping"],"company":null,"sources":[{"title":"Roof Leak Cause Determination","url":"https://www.nrcia.org/roof-leak-cause-determination/","publisher":"National Roof Certification and Inspection Association"},{"title":"How to Find a Roof Leak","url":"https://www.bobvila.com/articles/how-to-find-a-roof-leak.md","publisher":"Bob Vila"},{"title":"Troubleshooting Roof Leaks: Problems & Solutions","url":"https://www.jlconline.com/how-to/roofing/troubleshooting-roof-leaks-problems-solutions_o/?o=3","publisher":"Journal of Light Construction"}],"country":null},{"slug":"roof-life-cycle-cost","title":"Roof Life-Cycle Cost","type":"article","summary":"The total cost of owning a roof over a set period, including installation, maintenance, repairs, energy effects, replacement and disposal.","body":"Life-cycle cost analysis (LCCA) is an economic method for identifying the most cost-effective option over the whole life of an asset rather than at the point of purchase. Applied to roofs, it compares the total cost of ownership of different roof systems over the same study period, often several decades.\n\n## What is included\n\nA roof life-cycle cost typically considers:\n\n- **Initial cost:** materials, labour, design, permits, and any structural work.\n- **Maintenance:** inspections, cleaning, minor repairs, recoating.\n- **Repairs and partial replacements**, such as flashings and sealants.\n- **Replacement cost**, when a roof reaches the end of its service life within the study period.\n- **Energy effects**, for example lower cooling costs from a cool roof or reduced heat flow through a green roof.\n- **Other operating effects**, such as stormwater fees in cities that charge them.\n- **Disposal costs** at tear-off, and any salvage or scrap value.\n- **Residual value** of a roof that still has useful life at the end of the study period.\n\nFuture costs are discounted to present value so options can be compared fairly.\n\n## Why service life dominates\n\nBecause roofs are replaced periodically, a cheaper roof with a short life may cost more over 50 years than a more expensive roof that lasts the entire period. Published life expectancy estimates vary widely, from about 20 years for basic asphalt shingles to 60-150 years for slate in InterNACHI's chart, so the assumed service life strongly influences results.\n\n## Example: green roofs\n\nA US General Services Administration analysis of green roofs estimated about 40 years of membrane life versus 17 years for a conventional roof and calculated a payback of about 6.2 years nationally (with a 5.2 percent internal rate of return) based on 50-year average annual savings, after including avoided stormwater costs, energy savings and maintenance of roughly $0.14 per square foot per year.\n\n## Limits\n\n- Results depend heavily on assumptions about service life, discount rate, energy prices and maintenance quality.\n- Hazard exposure (hail, wind, wildfire) can shorten actual life and change outcomes.\n- Non-monetary factors, such as appearance, weight, embodied carbon and resilience, are often assessed alongside cost.\n\n## Uses\n\nBuilding owners, governments and facility managers use LCCA to choose between roof systems, to justify reflective or vegetated roofs, and to plan capital budgets. Green building programs increasingly pair it with life cycle assessment of environmental impacts.","key_facts":[{"label":"Method","value":"Life-cycle cost analysis with discounting to present value"},{"label":"Biggest driver","value":"Assumed service life"},{"label":"GSA green roof payback","value":"About 6.2 years nationally"}],"regions":["Global"],"aliases":["roof LCC","life-cycle costing","total cost of ownership roofing"],"related":["roof-lifespan-comparison","embodied-carbon-roofing","cool-roof","green-roof"],"sources":[{"title":"Life-cycle cost analysis","url":"https://en.wikipedia.org/wiki/Life-cycle_cost_analysis","publisher":"Wikipedia"},{"title":"The Benefits and Challenges of Green Roofs on Public and Commercial Buildings","url":"https://www.gsa.gov/system/files/The_Benefits_and_Challenges_of_Green_Roofs_on_Public_and_Commercial_Buildings.pdf","publisher":"US General Services Administration"},{"title":"InterNACHI's Standard Estimated Life Expectancy Chart for Homes","url":"https://www.nachi.org/life-expectancy.htm","publisher":"InterNACHI"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roof-lifespan-comparison","title":"Roof Lifespan Comparison","type":"article","summary":"Typical service lives of common roofing materials, from asphalt shingles and membranes to tile, slate and metal, and what shortens or extends them.","body":"How long a roof lasts depends on the material, the quality of installation, the climate, maintenance, ventilation and exposure to storms. Published figures are estimates, not promises, and different sources give different ranges. The figures below come from InterNACHI's estimated life expectancy chart for homes unless stated otherwise; InterNACHI cautions that they are guidelines only and notes that hot climates drastically reduce asphalt shingle life.\n\n## Estimated life expectancy (InterNACHI)\n\n| Material | Estimated life (years) |\n|---|---|\n| Asphalt shingles, 3-tab | 20 |\n| Asphalt shingles, architectural | 30 |\n| Wood | 25 |\n| Fibre cement | 25 |\n| Simulated (synthetic) slate | 10-35 |\n| Clay or concrete tile | 100+ |\n| Slate | 60-150 |\n| Metal | 40-80 |\n| Copper | 70+ |\n| Built-up roofing (BUR) | 30 |\n| Modified bitumen | 20 |\n| EPDM | 15-25 |\n| TPO | 7-20 |\n| Green (vegetated) roof | 5-40 |\n| Aluminium coating | 3-7 |\n\n## Other published estimates\n\n- Commonly cited figures are 15-18 years for three-tab asphalt shingles and 24-30 years for dimensional shingles, about 25 years overall for a typical asphalt shingle roof.\n- A US General Services Administration review estimated about 40 years for a green roof membrane versus about 17 years for a conventional low-slope roof, because vegetation protects the waterproofing.\n\n## What shortens roof life\n\n- High heat and UV exposure, especially for asphalt and polymers;\n- Poor attic ventilation and air leakage, which overheat or wet the deck;\n- Hail, high winds and wildfire exposure;\n- Freeze-thaw cycles for porous materials;\n- Coastal salt for some metals and fasteners;\n- Ponding water on low-slope roofs;\n- Poor installation, especially fastening and flashing errors.\n\n## What extends it\n\nRegular inspection, keeping gutters and drains clear, prompt repair of flashings and sealants, recoating where appropriate, and protecting membranes from foot traffic all help roofs reach or exceed typical estimates.\n\n## Lifespan versus component life\n\nThe covering may outlast other parts of the roof. Tile and slate can last a century, but underlayments, battens, flashings and fasteners often need renewal sooner. Lifespan comparisons should therefore consider the whole roof system.","key_facts":[{"label":"Asphalt 3-tab (InterNACHI)","value":"About 20 years"},{"label":"Architectural asphalt (InterNACHI)","value":"About 30 years"},{"label":"Metal (InterNACHI)","value":"40-80 years"},{"label":"Slate (InterNACHI)","value":"60-150 years"},{"label":"Clay/concrete tile (InterNACHI)","value":"100+ years"}],"regions":["Global","North America"],"aliases":["roof life expectancy","how long roofs last","roof service life"],"related":["roof-life-cycle-cost","embodied-carbon-roofing","roofing-waste","uv-degradation-roofing","hail-damage","green-roof"],"sources":[{"title":"InterNACHI's Standard Estimated Life Expectancy Chart for Homes","url":"https://www.nachi.org/life-expectancy.htm","publisher":"InterNACHI"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"The Benefits and Challenges of Green Roofs on Public and Commercial Buildings","url":"https://www.gsa.gov/system/files/The_Benefits_and_Challenges_of_Green_Roofs_on_Public_and_Commercial_Buildings.pdf","publisher":"US General Services Administration"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roof-maintenance-checklist","title":"Roof Maintenance Checklist by Season","category":"problems-maintenance","type":"article","summary":"A season-by-season list of routine roof checks and upkeep tasks for homes and low-slope buildings, plus inspections after major storms.","body":"Routine maintenance catches small problems, such as a blocked gutter or a cracked boot, before they cause leaks and rot. Industry bodies in North America, including the National Roofing Contractors Association (NRCA), commonly recommend inspecting roofs at least twice a year, typically in spring and autumn, and after major storms. Seasons below follow a temperate Northern Hemisphere pattern; adjust for local climate, wet and dry seasons, or cyclone and monsoon periods.\n\nMuch of this can be done from the ground with binoculars and from inside the attic. Work on the roof itself should only be done with safe access and fall protection, or by a professional.\n\n## Spring\n\n- Look for winter damage: lifted, cracked or missing shingles, tiles or slates; displaced ridge pieces.\n- Check flashings at chimneys, walls, skylights and vents.\n- Clear gutters and downpipes; check that outlets drain freely.\n- Inspect the attic for stains, damp insulation, frost marks or mould.\n- On low-slope roofs, clear drains and scuppers and check for ponding, blisters and open seams.\n\n## Summer\n\n- Note any moss, algae or lichen and plan treatment.\n- Trim overhanging branches.\n- Check sealants and pipe boots, which degrade in sun.\n- Confirm attic ventilation is not blocked.\n- Schedule any repairs while the weather is dry.\n\n## Autumn\n\n- Clear leaves from gutters, valleys and roof surfaces, possibly more than once.\n- Check that downpipe extensions carry water away from foundations.\n- Inspect for animal entry points before winter.\n- Check chimney caps and spark arrestors.\n- In snowy regions, confirm ice-barrier details and attic air sealing.\n\n## Winter\n\n- Watch for ice dams and icicles at eaves.\n- Use a roof rake from the ground to remove heavy snow on low eaves if needed.\n- Check the attic after cold snaps for frost and drips.\n- Avoid walking on frozen roofs.\n\n## After storms\n\nLook for debris, missing pieces and dented metal from the ground, document damage with photographs, and arrange an inspection. Keep records of all inspections and repairs, which help with warranty and insurance questions.","key_facts":[{"label":"Common recommendation","value":"Inspect at least twice a year and after storms"},{"label":"Safe methods","value":"Binoculars from the ground, attic checks"},{"label":"Key tasks","value":"Gutters, flashings, attic, drains, vegetation"}],"regions":["Global"],"aliases":["roof maintenance schedule","seasonal roof checklist","roof inspection schedule"],"related":["storm-damage-inspection","gutter-problems","ice-dam","roof-moss","roof-age-estimation","drone-roof-inspection"],"company":null,"sources":[{"title":"A new resource for consumers","url":"https://professionalroofing.net/articles/article/4787","publisher":"Professional Roofing (NRCA)"},{"title":"7 tips for spring roof maintenance","url":"https://www.rooferscoffeeshop.com/post/7-tips-for-spring-roof-maintenance","publisher":"RoofersCoffeeShop"},{"title":"A guide to checking your roof","url":"https://ishn.com/articles/99082-a-guide-to-checking-your-roof","publisher":"ISHN"}],"country":null},{"slug":"roof-measurement-and-estimating","title":"Roof Measurement and Estimating","category":"installation","type":"article","summary":"Roof estimating converts plan dimensions into true roof area using pitch multipliers, expresses it in squares or square metres and adds waste allowances.","body":"**Roof estimating** is the process of measuring a roof and calculating the materials and labour needed to cover it. Because a pitched roof is larger than the floor area beneath it, measurements taken from plans or the ground must be adjusted for slope. Estimators then add allowances for waste, starter and ridge materials, flashings and accessories.\n\n## Units\n\nIn the United States and Canada roofing is priced and ordered by the **square**, equal to 100 sq ft (about 9.3 m²) of roof surface. Most other countries, including the UK, Europe and Australia, use square metres. Shingles are packaged in bundles, and the number of bundles per square is printed on each product's packaging.\n\n## Measuring\n\n- **On the roof.** Measure each plane along the eave and up the slope, multiply to get its area and add the planes together.\n- **From plans or the ground.** Measure the horizontal (plan) area including overhangs, then multiply by a pitch multiplier.\n- **Aerial and drone measurement.** Satellite or drone imagery with software can produce full roof reports, widely used for quotes and insurance claims.\n\n## Pitch multipliers\n\nThe multiplier converts plan area to sloped area and equals the square root of 1 + (rise/run)². Examples:\n\n| Pitch | Multiplier | Angle |\n|---|---|---|\n| 4:12 | 1.054 | 18.4 degrees |\n| 6:12 | 1.118 | 26.6 degrees |\n| 8:12 | 1.202 | 33.7 degrees |\n| 12:12 | 1.414 | 45.0 degrees |\n\nA 150 m² (1615 sq ft) plan area at 6:12 therefore has a roof area of about 168 m² (about 18 squares).\n\n## Waste and extras\n\nEstimators add a **waste factor** for cutting at hips, valleys, dormers and edges. Simple gable roofs need the least; cut-up roofs with many hips and valleys need more. Canadian guidance for wood shakes and shingles suggests a 5 to 10 percent allowance, plus extra material for valleys. Separate quantities are calculated for starter strips (eave and rake length), ridge and hip caps (linear length), underlayment, ice barrier, drip edge, flashing and fasteners.\n\n## Labour factors\n\nSteep pitches, height, access, number of layers to remove and weather all affect labour time and cost.","key_facts":[{"label":"Roofing square","value":"100 sq ft (about 9.3 m²)"},{"label":"Pitch multiplier formula","value":"Square root of 1 + (rise/run)²"},{"label":"Multiplier at 6:12","value":"1.118"}],"regions":["Global"],"aliases":["roof estimating","roof takeoff","roof area calculation"],"related":["roof-pitch-calculation","roofing-square","waste-factor","roof-replacement-process"],"company":null,"sources":[{"title":"Square (unit)","url":"https://en.wikipedia.org/wiki/Square_(unit)","publisher":"Wikipedia"},{"title":"Roof pitch","url":"https://en.wikipedia.org/wiki/Roof_pitch","publisher":"Wikipedia"},{"title":"Canadian Roofing Reference Manual: 9.2.1 Estimating Materials","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-2-wood-shakes-and-wood-shingles/9-2-1-estimating-materials/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"roof-moisture-survey","title":"Roof Moisture Survey","category":"tools-equipment","type":"article","summary":"A systematic test of a low-slope roof to locate wet insulation, using infrared, nuclear or impedance scanning verified by core samples.","body":"A roof moisture survey locates and maps wet insulation and substrate in a low-slope roof assembly. Water that enters through a leak can spread through insulation well beyond the visible leak and remain for years, reducing thermal performance, rotting decks and degrading adhesives. Surveys help owners decide whether to repair, recover or replace a roof, because many codes and manufacturers do not permit recovering over wet materials.\n\n## Methods\n\n- **Infrared thermography** detects temperature differences at the roof surface, typically after sunset when wet areas retain heat longer than dry ones. ASTM C1153 covers infrared imaging of roofs for wet insulation. It is fast over large areas but depends on suitable weather and roof construction. (See infrared roof thermography.)\n- **Nuclear moisture surveys** use a gauge containing a radioactive source that emits fast neutrons. Hydrogen atoms in water slow the neutrons, and the gauge counts the slowed neutrons that return. Readings are taken on a grid, commonly spaced about 5 to 10 ft (1.5 to 3 m) apart, under ANSI/SPRI/IIBEC NT-1. Operators must be licensed for the radioactive source.\n- **Impedance (capacitance) scanning** passes a low-frequency electrical signal into the roof and measures changes caused by moisture. Readings are taken on a grid or continuously, and ASTM D7954 covers the method. Results are comparative and depend on calibration to the roof being surveyed.\n- **Core cuts** remove samples of the roof assembly for inspection and gravimetric testing (weighing wet, drying, and weighing again). Moisture content is calculated from the difference between wet and dry weight relative to the dry weight.\n\n## Why cores matter\n\nInfrared, nuclear and impedance readings are relative indicators, not direct measurements of moisture content. Technical guidance in the industry stresses that anomalies must be verified with cores, and that moisture is often uneven through the thickness of the insulation, so samples should be checked at the top, middle and bottom. Without verification, surveys can produce false positives that lead to unnecessary removal of sound materials.\n\n## Reporting\n\nA survey report usually includes a roof plan marking wet areas, core locations and results, photographs, and recommendations. Repeating surveys over time helps track deterioration and plan budgets.","key_facts":[{"label":"Non-destructive methods","value":"Infrared, nuclear, impedance"},{"label":"Verification","value":"Core cuts with gravimetric analysis"},{"label":"Standards","value":"ASTM C1153, ASTM D7954, ANSI/SPRI/IIBEC NT-1"}],"regions":["Global"],"aliases":["moisture survey","wet insulation survey","nuclear roof survey","impedance survey"],"related":["infrared-roof-thermography","moisture-meter","electronic-leak-detection","roof-leak-detection","repair-vs-replace"],"company":null,"sources":[{"title":"Surveying roof moisture","url":"https://professionalroofing.net/articles/article/5681","publisher":"Professional Roofing"},{"title":"Roof moisture surveys: an effective tool for the industry","url":"https://iibec.org/publication-post/roof-moisture-surveys-an-effective-tool-for-the-industry/","publisher":"IIBEC"},{"title":"How wet is wet?","url":"https://professionalroofing.net/articles/article/5297","publisher":"Professional Roofing"}],"country":null},{"slug":"roof-moss","title":"Roof Moss","category":"problems-maintenance","type":"article","summary":"Moss growth on shaded, damp roofs that holds water, lifts shingles and tiles, and blocks drainage if left to build up.","body":"Moss is a common growth on roofs in cool, damp climates such as the Pacific Northwest of North America, the British Isles, northern Europe and New Zealand. It favours shaded slopes, north-facing slopes in the Northern Hemisphere, areas under trees, and rough surfaces that hold moisture, including asphalt shingles, wood shakes, concrete and clay tiles, and slate.\n\n## Why it matters\n\nMoss acts like a sponge. It keeps the roof surface wet for long periods, which can speed decay of wood shakes and the weathering of shingles and porous tiles. Thick cushions of moss can grow under the lower edges of shingles and tiles, lifting them and allowing wind-driven rain to enter. Dislodged clumps wash into gutters and downpipes and block them. In freezing climates, water held in moss can freeze and damage porous surfaces.\n\n## Removal\n\n- **Physical removal.** Brushing or gently scraping moss off by hand, working downslope so units are not lifted, is described by environmental groups as the most environmentally sound approach, though it can be hard work and needs safe access.\n- **Chemical treatments.** Products based on zinc sulfate, potassium salts of fatty acids and other ingredients are sold as moss killers. Some zinc products are toxic to aquatic life, and runoff should be kept away from ponds, streams and vegetation. Local rules on roof runoff may apply.\n- **Avoid pressure washing.** High-pressure water can strip granules from shingles, damage tiles and force water under laps.\n\nDead moss often loosens over time and can then be brushed off more easily.\n\n## Prevention\n\n- Trim overhanging branches to let in sun and air.\n- Keep the roof and gutters free of debris.\n- Fit zinc or copper strips near the ridge, whose runoff discourages regrowth (see zinc and copper strips).\n- Choose materials suited to the climate when reroofing.\n\nWorking on a wet, mossy roof is dangerous; fall protection or professional help is often advisable.","key_facts":[{"label":"Favoured conditions","value":"Shade, damp climate, rough surfaces"},{"label":"Main risks","value":"Moisture retention, lifted units, clogged gutters"},{"label":"Preferred removal","value":"Gentle physical removal; avoid pressure washing"}],"regions":["Global","North America","Europe","Oceania"],"aliases":["moss on roof","roof moss removal"],"related":["zinc-and-copper-strips","roof-cleaning","roof-algae","lichen-on-roofs","gutter-problems"],"company":null,"sources":[{"title":"On-roof moss removal","url":"https://depts.washington.edu/hortlib/pal/on-roof-moss-removal/","publisher":"University of Washington Elisabeth C. Miller Library"},{"title":"Chemical Moss Control for Roofs, Decks, and Sidewalks","url":"https://bryophytes.science.oregonstate.edu/page24.htm","publisher":"Oregon State University"},{"title":"How to Remove Roof Moss","url":"https://www.thisoldhouse.com/roofing/how-to-remove-roof-moss","publisher":"This Old House"}],"country":null},{"slug":"roof-pitch","title":"Roof Pitch and Slope","category":"components","type":"article","summary":"Roof pitch describes how steep a roof is, expressed as rise over run (such as 6:12 or 6/12), as an angle in degrees, or as a percentage.","body":"Roof pitch is the measure of a roof's steepness. It controls which roof coverings can be used, how quickly water and snow shed, how much attic space there is, and how a roof looks. Different regions and trades express it in different ways.\n\n## Ways of expressing pitch\n\n- **Rise per run (North America):** the vertical rise in inches for every 12 in of horizontal run, written as 4:12, 4/12 or \"4 in 12\". A 12:12 roof rises 12 in for every 12 in of run.\n- **Degrees (UK, Europe, Australia, much of the world):** the angle between the roof surface and horizontal, such as 22.5° or 35°. Tile and slate manufacturers in these markets specify minimum pitches in degrees.\n- **Ratio (Canada and elsewhere):** the National Building Code of Canada describes slopes as ratios such as 1 in 3 (equivalent to 4:12).\n- **Percentage:** rise divided by run times 100. A 4:12 roof is about 33%; 12:12 is 100%. Often used for low-slope roofs and drainage falls.\n- **Mm per metre:** rise per metre of run.\n\n## Conversions\n\nDegrees can be found from rise and run as the arctangent of rise/run. For example:\n\n- 3:12 is about 14.0°\n- 4:12 is about 18.4°\n- 6:12 is about 26.6°\n- 8:12 is about 33.7°\n- 12:12 is 45°\n\n## Pitch versus slope\n\nStrictly, carpenters distinguish pitch (total rise divided by total span, so a 6:12 roof is a \"1/4 pitch\") from slope (rise over run, where run is half the span). In everyday use the two words are used interchangeably, and framing squares are marked in slope even when called pitch.\n\n## Why pitch matters\n\n- **Low-slope and steep-slope roofs:** in North America roofs below about 3:12 are commonly called low-slope and need membrane systems; Canada's NBC treats slopes under 1 in 3 as low slope.\n- **Covering limits:** each material has a minimum pitch set by codes and manufacturers. Asphalt shingles, for example, have a code minimum slope in the US, with extra underlayment required toward the low end of their range.\n- **Snow, wind and access:** steeper roofs shed snow better but are more difficult and dangerous to work on.","key_facts":[{"label":"US/Canada notation","value":"Rise:12, e.g. 6:12"},{"label":"Common elsewhere","value":"Degrees"},{"label":"4:12 equals","value":"About 18.4° or 33%"},{"label":"12:12 equals","value":"45° or 100%"}],"regions":["Global"],"aliases":["roof slope","pitch","rise over run","roof angle"],"related":["roofing-square","flat-roof","gable-roof","rafter"],"company":null,"sources":[{"title":"Roof pitch","url":"https://en.wikipedia.org/wiki/Roof_pitch","publisher":"Wikipedia"},{"title":"Ontario Building Code 9.26.5 Required Eave Protection (unofficial reproduction)","url":"https://www.buildingcode.online/1940.html","publisher":"buildingcode.online"}],"country":null},{"slug":"roof-pitch-calculation","title":"Roof Pitch Calculation","category":"installation","type":"article","summary":"Roof pitch is calculated as vertical rise over horizontal run, expressed as x:12, a ratio, a percentage or an angle in degrees.","body":"**Roof pitch** (or **slope**) describes how steep a roof is. It controls which roof coverings may be used, how much underlayment is required, how water and snow drain and how safe the roof is to walk on. In North America it is usually given as inches of **rise** per 12 inches of horizontal **run**, written 6:12 or \"6 in 12\". Elsewhere it is more often given in degrees, and low-slope roofs are frequently described as a ratio or percentage (for example 1:50 or 2 percent).\n\n## Pitch versus slope\n\nStrictly, **slope** is rise over run, while **pitch** is rise over the full span (twice the run). A roof with a 6:12 slope therefore has a pitch of 1/4. In everyday trade use the two words are used interchangeably, and \"pitch\" usually means the rise-per-12 figure.\n\n## How to measure\n\n- **With a level.** Place a 12 in (or 1 m) level horizontally against the roof or rafter, and measure vertically from the end of the level to the roof surface. That measurement is the rise per 12 in (or per metre).\n- **From rafter dimensions.** Divide the rise from wall plate to ridge by the run from wall plate to centre.\n- **With an angle finder or app.** Read the angle directly and convert.\n\n## Conversions\n\n- Angle = arctan(rise / run).\n- Percentage = rise / run x 100.\n\n| x:12 | Degrees | Percent |\n|---|---|---|\n| 2:12 | 9.5 | 16.7 |\n| 3:12 | 14.0 | 25.0 |\n| 4:12 | 18.4 | 33.3 |\n| 6:12 | 26.6 | 50.0 |\n| 8:12 | 33.7 | 66.7 |\n| 12:12 | 45.0 | 100.0 |\n\n## Why it matters\n\n- **Covering limits.** In the IRC, asphalt shingles need at least 2:12, with doubled underlayment up to 4:12. Many metal systems are designed for 3:12 (1:4) and steeper.\n- **Low slope definitions.** The National Building Code of Canada treats slopes below 1 in 3 (4:12) as low slope. OSHA treats roofs of 4:12 or less as low-slope for fall protection.\n- **Safety.** Australian guidance treats roofs over 35 degrees as unsuitable to stand on even with edge protection.\n- **Estimating.** Pitch determines the multiplier used to convert plan area into roof area.","key_facts":[{"label":"North American notation","value":"Rise per 12 in of run (e.g. 6:12)"},{"label":"Conversion to angle","value":"arctan(rise/run)"},{"label":"6:12 equals","value":"26.6 degrees, 50%"}],"regions":["Global"],"aliases":["roof slope","calculating roof pitch","pitch to degrees"],"related":["roof-measurement-and-estimating","low-slope-roof","roofing-fall-protection"],"company":null,"sources":[{"title":"Roof pitch","url":"https://en.wikipedia.org/wiki/Roof_pitch","publisher":"Wikipedia"},{"title":"Reroofing","url":"https://www.bloomingtonmn.gov/sites/default/files/2023-08/Reroofing.pdf","publisher":"City of Bloomington, Minnesota"},{"title":"Fall Protection in Residential Construction: Frequently Asked Questions","url":"https://www.osha.gov/residential-fall-protection/faq","publisher":"U.S. Occupational Safety and Health Administration"},{"title":"Work Health and Safety (Preventing Falls in Housing Construction) Code of Practice 2015","url":"https://legislation.gov.au/F2016L00411/asmade/2016-03-30/text/original/epub/OEBPS/document_1/document_1.html","publisher":"Federal Register of Legislation (Australia)"},{"title":"Canadian Roofing Reference Manual: 10.8 Metal Roofing Application","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-10-metal-roofing/10-8-application/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"repair-vs-replace","title":"Roof Repair vs Replacement","category":"problems-maintenance","type":"article","summary":"The factors owners and roofers weigh when deciding whether to fix part of a roof or replace the whole covering.","body":"Deciding between repair and replacement is one of the most common roofing questions. There is no single rule; the answer depends on the condition of the whole roof, not just the damaged area, and on cost, building plans and local regulations.\n\n## When repair often makes sense\n\n- Damage is limited to a small area, such as a few missing shingles, a cracked tile or a failed pipe boot.\n- The rest of the roof is in good condition with substantial life remaining.\n- Matching materials are available.\n- The problem is a detail (flashing, sealant, a single valley) rather than the covering itself.\n\n## When replacement often makes sense\n\n- The covering is near the end of its expected service life, with widespread curling, granule loss, cracking, slipped slates or corrosion.\n- Leaks are recurring in multiple locations.\n- The deck is sagging, soft or rotten over large areas.\n- Storm damage affects a large share of the roof.\n- Matching replacement materials cannot be found, which leaves a patchwork appearance.\n- The building is being renovated, insulated or fitted with solar, and doing the roof first avoids later removal.\n\n## Overlays and multiple layers\n\nSome jurisdictions allow a new layer of shingles over one existing layer, but building codes such as the International Residential Code in the United States do not permit a recover where the existing roof already has two or more applications of roof covering, is water-soaked or deteriorated, or is covered with slate, clay, cement or asbestos-cement tile (IRC R908.3.1.1 in the 2018 edition). Overlays hide deck problems, add weight, and can affect manufacturer warranties. Insurance and repair-estimating guidance notes that multiple layers can complicate repairs and claims.\n\n## Other considerations\n\n- **Cost over time**: repeated repairs on an old roof can add up to more than a replacement.\n- **Warranties**: manufacturer and workmanship warranties may depend on approved installation methods.\n- **Energy and ventilation**: replacement is a chance to improve attic ventilation, insulation and underlayment.\n- **Heritage rules**: listed or conserved buildings may require like-for-like repair rather than replacement.\n- **Inspection**: an impartial assessment, including the attic and deck, gives a clearer basis than the visible surface alone.","key_facts":[{"label":"Repair suits","value":"Localised damage on an otherwise sound roof"},{"label":"Replacement suits","value":"Ageing, widespread wear, deck damage, recurring leaks"},{"label":"Overlay limit (US IRC)","value":"Generally not over two existing layers"}],"regions":["Global"],"aliases":["repair or replace roof","reroof decision","roof replacement decision"],"related":["roof-age-estimation","tear-off-vs-overlay","sagging-roof-deck","shingle-curling","granule-loss","roof-insurance-claims"],"company":null,"sources":[{"title":"Understanding residential roof repairs: how do I know if my roof needs to be replaced?","url":"https://www.gaf.com/es-us/blog/your-home/understanding-residential-roof-repairs-how-do-i-know-if-my-roof-needs-to-be-replaced-734dcc7e-9074-4ef7-8ad4-e5297f93a8da","publisher":"GAF"},{"title":"Roof Repair vs. Replacement: Factors to Consider","url":"https://becn.com/beaconbits/roof-repair-vs-replacement-factors-to-consider","publisher":"Beacon"},{"title":"Repair considerations for roofs with more than one layer","url":"https://www.nearmap.com/repairlogic/repair-considerations-for-roofs-with-more-than-one-layer","publisher":"Nearmap"},{"title":"Reroofing (2018 IRC R908)","url":"https://gillettewy.gov/files/assets/public/v/1/development-services/documents/reroofing-2018.pdf","publisher":"City of Gillette, Wyoming"}],"country":null},{"slug":"roof-replacement-process","title":"Roof Replacement Process","category":"installation","type":"article","summary":"The roof replacement process is the sequence of work used to remove an old roof covering and install a new one, from planning and permits to final inspection.","body":"A roof replacement, often called a re-roof, removes or covers the existing roof covering and installs a new one. The broad sequence is similar worldwide, although the materials, codes and trade terms differ by country. On a typical pitched house roof the work moves from the bottom of the roof (the eaves) towards the top (the ridge), so that each layer sheds water over the one below.\n\nThe steps below describe a common steep-slope (pitched) replacement. Low-slope membrane roofs follow a different but parallel sequence of deck preparation, insulation, membrane and flashings.\n\n## Planning and approvals\n\nWork starts with an inspection of the existing roof, measurement of the area, selection of the new covering and a check of local rules. Many authorities require a permit for re-roofing, and some set limits on how many layers may remain on a roof. A written contract and the manufacturer's installation instructions define what will be done.\n\n## Typical sequence on a pitched roof\n\n1. **Site protection.** Set up fall protection, ladder access, debris chutes or bins and protection for gardens, walls and gutters.\n2. **Tear-off.** Remove the old covering, underlayment and worn flashings down to the deck, unless the code and conditions allow an overlay.\n3. **Deck inspection and repair.** Replace rotten or delaminated sheathing and re-nail the deck where needed. Building America guidance for existing homes recommends checking that the roof plane is flat, because sagging can point to structural problems.\n4. **Eave and edge details.** Install ice barrier where required by climate, drip edge and any deck-seam sealing.\n5. **Underlayment.** Lay underlayment over the rest of the deck, lapped so water runs over each lap.\n6. **Flashings and valleys.** Line valleys and prepare step, apron and penetration flashings so they can be woven into the new courses.\n7. **Starter course and field.** Install the starter course at the eaves and rakes, then lay the main courses at the specified exposure and nailing pattern.\n8. **Ridge and hips.** Cap hips and ridges and install any ridge ventilation.\n9. **Clean-up and inspection.** Remove nails and debris, then arrange the final inspection where a permit applies.\n\n## Regional differences\n\nIn North America, decks are usually plywood or OSB sheathing and shingles are nailed through to the deck. In the UK and much of Europe, tiles and slates are commonly hung on timber battens over a breathable underlay, and fixing is specified under national standards such as BS 5534. In Australia and New Zealand, metal sheet roofing is widespread and is fixed to purlins or battens.\n\n## Daily weather protection\n\nA roof under replacement is vulnerable to rain. Roofers normally strip only as much as can be made watertight the same day and use temporary membranes or night seals at the end of each shift, a practice the Canadian Roofing Reference Manual identifies as essential.","key_facts":[{"label":"Work direction","value":"Eaves to ridge"},{"label":"Typical first step","value":"Inspection, measurement and permit check"},{"label":"End-of-day practice","value":"Temporary weather protection or night seal"}],"regions":["Global"],"aliases":["re-roof","reroofing","roof replacement"],"related":["tear-off-vs-overlay","roof-deck-inspection-and-replacement","underlayment-installation","starter-course","roofing-permits-and-inspections","hiring-a-roofer"],"company":null,"sources":[{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"},{"title":"Canadian Roofing Reference Manual: 3.3.7 Cold Weather Material Application","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-3-roofing-preparation/3-3-cold-weather-conditions/3-3-7-material-application/","publisher":"Canadian Roofing Contractors Association"},{"title":"Can you put new shingles over old shingles under IRC 2021?","url":"https://www.jaspector.com/codes/irc-2021/ch09-roof-assemblies/reroofing-code-existing-shingles/","publisher":"Jaspector"},{"title":"Canadian Roofing Reference Manual: 9.1.2 Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-1-asphalt-shingles/9-1-2-installation/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"roof-ridge","title":"Roof Ridge","category":"components","type":"term","summary":"The ridge is the horizontal line at the top of a pitched roof where two sloping planes meet; it is capped with ridge tiles, cap shingles or metal.","body":"The ridge is the highest horizontal edge of a pitched roof, formed where two slopes rise to meet. Every gable, hip or similar roof has at least one ridge; complex roofs may have several at different heights. The term covers both the external line of the roof and, loosely, the framing member beneath it.\n\n## Structure\n\nBeneath the ridge, opposing rafters meet against a ridge board or ridge beam, or the top chords of trusses meet at the apex. Historic roofs might have a ridge piece carried by a king post, or no ridge timber at all.\n\n## Covering the ridge\n\nBecause the roof covering cannot simply be lapped over the apex, the ridge is finished with a separate cap:\n\n- **Ridge tiles:** half-round, angled or decorative tiles used on clay, concrete and slate roofs. Traditionally bedded in mortar; modern UK practice increasingly uses dry-fix ridge systems in which the tiles are mechanically fixed.\n- **Ridge cap shingles:** cut or purpose-made shingles bent over the ridge and nailed, each lapping the next, on asphalt shingle roofs.\n- **Metal ridge caps:** formed sheet metal over metal roofs, sealed with closures that match the panel profile.\n- **Thatch ridges:** a separate layer of thatch, often decoratively patterned, on thatched roofs.\n\n## Ventilation at the ridge\n\nThe ridge is the natural outlet for warm, moist air rising in a roof space, so it is a preferred location for exhaust vents. Continuous ridge vents cut a slot along the deck and cover it with a vented cap. US code allows a reduced total vent area where between 40% and 50% of the ventilation is placed in the upper part of the roof, within 3 ft (914 mm) of the ridge, with the rest at the eaves. UK cold roof guidance often calls for high-level ventilation equivalent to a 5 mm continuous slot at the ridge.\n\n## Terminology\n\nThe ends of a ridge meet gables or hips. In Britain, the decorative pieces at ridge ends are finials or ridge ends.","key_facts":[{"label":"Location","value":"Highest horizontal line of a pitched roof"},{"label":"Coverings","value":"Ridge tiles, cap shingles, metal caps"},{"label":"US upper vent zone","value":"Within 3 ft (914 mm) of ridge"}],"regions":["Global"],"aliases":["ridge","ridge line","roof apex"],"related":["ridge-board","ridge-vent","roof-hip","gable-roof","roof-ventilation"],"company":null,"sources":[{"title":"Roof glossary","url":"https://www.mkheritage.org.uk/wdahs/Thornton/docs/roofglossary.html","publisher":"Milton Keynes Heritage Association"},{"title":"IRC R806 Roof Ventilation (code change proposal)","url":"https://iccsafe.org/wp-content/uploads/bcac/IRC-R806.pdf","publisher":"International Code Council"},{"title":"Batten space ventilation for pitched roofs","url":"https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/LABCW%20Batten%20space%20ventilation%20for%20pitched%20roofs%20V2.pdf","publisher":"LABC Warranty"}],"country":null},{"slug":"wood-rot","title":"Roof Rot (Fascia, Soffit and Deck)","category":"problems-maintenance","type":"article","summary":"Fungal decay of roof timbers such as fascia boards, soffits, sheathing and rafter ends, caused by long-term wetting.","body":"Roof rot is decay of the wooden parts of a roof by wood-destroying fungi. It needs wood that stays wet, typically above about 20 percent moisture content for extended periods, so it is almost always a symptom of a water problem rather than a problem in itself. The most commonly affected parts are the **fascia** (the board along the eave that gutters attach to), **soffits**, **rafter tails**, the **roof deck or sheathing**, and timber around chimneys, skylights and valleys.\n\n## Common causes\n\n- **Missing or poorly fitted drip edge**, letting water wick behind gutters into the fascia.\n- **Overflowing or clogged gutters**, or gutters pitched the wrong way, that spill water onto the fascia.\n- **Ice dams** that push water under the roofing at the eaves.\n- **Flashing failures** at walls, chimneys and penetrations.\n- **Damaged or worn roofing** letting rain reach the deck.\n- **Attic condensation** soaking the underside of sheathing.\n- **Unprimed cut ends** and paint failure on exposed trim.\n\n## Signs\n\nPeeling paint, soft or spongy wood, dark staining, gaps where gutters have pulled away, and, on the roof, soft spots underfoot. In the attic, dark, damp or crumbling sheathing and rusted nails point to deck rot. A screwdriver or awl that sinks easily into the wood confirms decay.\n\n## Repair\n\nRotten fascia and soffit sections are cut out and replaced, often with primed or naturally durable timber, or clad with metal or PVC trim. Deck rot is repaired by replacing affected sheathing, usually during reroofing, and sistering or replacing decayed rafter ends. Repairs only last if the moisture source is fixed: a correctly installed drip edge, cleaned and correctly pitched gutters, sound flashings and a controlled attic environment. Some regions also see insect damage alongside rot; termites and carpenter ants favour damp wood.","key_facts":[{"label":"Common locations","value":"Fascia, soffit, rafter tails, sheathing"},{"label":"Root cause","value":"Persistent wetting of timber"},{"label":"Prevention","value":"Drip edge, working gutters, sound flashings, dry attic"}],"regions":["Global"],"aliases":["fascia rot","rotted roof deck","soffit rot","sheathing rot"],"related":["fascia","soffit","drip-edge","gutter-problems","ice-dam","attic-condensation","sagging-roof-deck"],"company":null,"sources":[{"title":"Roof Edge Trim, Soffits and Fascia Rotting? Here's What to Do","url":"https://www.gaf.com/en-us/blog/your-home/roof-edge-trim-soffits-and-fascia-rotting-heres-what-to-do-ae23e582-307f-408e-b32c-40109c90e7de","publisher":"GAF"},{"title":"Fascia board treatment to prevent rot","url":"https://www.greenbuildingadvisor.com/question/fascia-board-treatment-to-prevent-rot","publisher":"GreenBuildingAdvisor"},{"title":"Roof Fascia: Everything You Need To Know","url":"https://homegeniusexteriors.com/genius-blog/roof-fascia/","publisher":"HomeGenius Exteriors"}],"country":null},{"slug":"roof-sheathing","title":"Roof Sheathing (Roof Deck)","category":"components","type":"article","summary":"Roof sheathing, or decking, is the layer of panels or boards fixed over rafters or trusses that forms the surface the underlayment and roof covering are attached to.","body":"Roof sheathing, also called roof decking or the roof deck, is the continuous or spaced layer fixed across rafters or trusses. It stiffens the roof frame, spreads loads to the framing, and provides the nailing surface for underlayment and the roof covering. In many codes the deck also acts as a structural diaphragm that helps the building resist wind and earthquake forces.\n\n## Common materials\n\n- **Plywood:** cross-laminated wood veneers glued into panels.\n- **Oriented strand board (OSB):** wood strands bonded with resin in oriented layers; widely used in North American house construction.\n- **Composite panels:** combine veneers with reconstituted wood layers.\n- **Solid boards (plank decking):** the traditional deck, still found on older houses and used under some heritage roofs.\n- **Tongue-and-groove decking:** thick boards or panels spanning widely spaced beams, often left exposed on the ceiling.\n\nIn North America, structural panels carry an APA (or similar) stamp with a span rating: the first number gives the maximum recommended spacing of roof supports, the second the maximum floor span.\n\n## Installation points\n\n- **Gaps:** APA recommends leaving about 1/8 in (3 mm) between panel edges and ends so panels can expand with moisture without buckling.\n- **Edge support:** panel edge clips (often called H-clips), blocking, or tongue-and-groove edges support unsupported edges between rafters.\n- **Fastening:** an InterNACHI guide notes common schedules of 6 in (150 mm) at panel edges and 12 in (300 mm) at intermediate supports, with closer spacing near ridges, eaves and gable ends in very high wind zones. Local codes govern.\n- **Thickness:** an InterNACHI table gives 5/8 in (16 mm) as a minimum for 24 in (610 mm) support spacing.\n\n## Regional terms\n\nIn Scotland and parts of northern Europe, boards fixed over rafters beneath slates are called sarking or sarking boards; \"sarking\" is also used loosely for underlay. In Australia and New Zealand, \"sarking\" usually means a reflective or breathable foil membrane rather than boards.\n\n## Related decks\n\nSome roof coverings, such as wood shakes and some tiles, are traditionally laid on spaced boards or battens instead of a solid deck.","key_facts":[{"label":"Common panels","value":"Plywood, OSB"},{"label":"APA recommended gap","value":"1/8 in (3 mm)"},{"label":"Edge support","value":"Panel clips, blocking, T&G"}],"regions":["Global"],"aliases":["roof decking","roof deck","sarking boards","sheathing"],"related":["skip-sheathing","roofing-underlayment","roof-battens","rafter","roof-truss"],"company":null,"sources":[{"title":"Builder Tips: Prevent Buckling with Proper Spacing (M300)","url":"https://www.apawood.org/buildertips/pages/M300.html","publisher":"APA - The Engineered Wood Association"},{"title":"Inspecting Roof Panel Sheathing","url":"https://nachi.org/inspect-roof-sheathing.htm","publisher":"InterNACHI"}],"country":null},{"slug":"tile-cutting","title":"Roof Tile Cutting Tools","category":"tools-equipment","type":"article","summary":"Tools for cutting clay and concrete roof tiles, chiefly angle grinders and saws with diamond blades, plus manual cutters that limit silica dust.","body":"Clay and concrete roof tiles must be cut at valleys, hips, verges, abutments and around penetrations. The most common tool is an **angle grinder** or a larger disc cutter fitted with a **diamond blade** rated for masonry or roof tile. Bench saws, wet saws and manual striking or nibbling cutters are also used.\n\n## Angle grinders and disc cutters\n\nDiamond blades grind through tile rather than shearing it. Roofers mark the cut, support the tile firmly (often on the roof on a cutting stand or on the ground on a bench), and cut from the top or the back depending on the profile and finish. Typical safety features include a blade guard, a side handle for two-handed control, and correctly rated blades for the tool's speed.\n\n## Silica dust\n\nCutting concrete and clay tiles releases respirable crystalline silica. Long-term exposure can cause silicosis, an incurable lung disease, as well as other serious illnesses. Workplace regulators in many countries set exposure limits and require controls. Common controls are:\n\n- **Wet cutting** with a water feed at the blade.\n- **On-tool dust extraction** using a shroud connected to a suitable vacuum.\n- **Respiratory protection** appropriate to the task and duration.\n- **Cutting away from other workers** and cleaning up with vacuums rather than dry sweeping.\n\nIn the United States, OSHA's respirable crystalline silica standard for construction sets out specified control methods (its Table 1) for tasks including handheld power saws and grinders. Workplace exposure limits for respirable crystalline silica also apply in other jurisdictions, including the UK, Australia and the European Union.\n\n## Manual cutters\n\nLever-action and striking cutters break or nibble tiles without a spinning blade. Manufacturers of these tools promote them as producing far less airborne dust and noise, though cut quality and the range of profiles they can handle vary.\n\n## Other hazards\n\nSpinning blades can kick back, shatter if damaged, or throw fragments. Eye and face protection, hearing protection, gloves and stable footing are standard. Cutting on a pitched roof adds the risk of losing balance, so many crews cut on the ground or on scaffolds where possible.","key_facts":[{"label":"Main power tool","value":"Angle grinder or disc cutter with diamond blade"},{"label":"Key health hazard","value":"Respirable crystalline silica dust"},{"label":"Dust controls","value":"Wet cutting, extraction, respirators"}],"regions":["Global"],"aliases":["tile cutter","cutting roof tiles","angle grinder"],"related":["clay-roof-tile","concrete-roof-tile","tile-slippage","slate-cutter","ridge-repointing"],"company":null,"sources":[{"title":"Meet the roof tile cutter that is eliminating silica dust production","url":"https://rooferscoffeeshop.com/post/meet-the-roof-tile-cutter-that-is-eliminating-silica-dust-production","publisher":"RoofersCoffeeShop"},{"title":"How to Cut Concrete Roof Tiles","url":"https://www.ehow.com/how_5992665_cut-concrete-roof-tiles.html","publisher":"eHow"},{"title":"DT 310 UT Extra diamond cutting blades for angle grinders","url":"https://www.klingspor.de/en/products/diamond-cutting-blades/dt-310-ut-extra","publisher":"Klingspor"},{"title":"Silica, Crystalline - Construction","url":"https://www.osha.gov/silica-crystalline/construction","publisher":"Occupational Safety and Health Administration"}],"country":null},{"slug":"roof-truss","title":"Roof Truss","category":"components","type":"term","summary":"A roof truss is a prefabricated or site-built triangulated frame that spans between walls to support a roof, replacing individual rafters and joists.","body":"A roof truss is a rigid frame of members arranged in triangles that spans from one supporting wall to another and carries the roof. Because a triangle cannot change shape once the lengths of its sides are fixed, a triangulated frame can span a long distance using relatively light members, with loads carried mainly as tension and compression along each member.\n\nIn most modern houses in North America, the UK, Australia and New Zealand, roofs are framed with factory-made timber trusses whose joints are connected with toothed metal connector plates (often called gang-nail or nail plates). These metal-plate-connected wood trusses are delivered to site and lifted onto the walls, a method that is faster than cutting rafters by hand.\n\n## Parts of a truss\n\n- **Top chords:** the sloping members that form the roof planes, doing the job of rafters.\n- **Bottom chord:** the horizontal tie that resists outward spread and usually carries the ceiling.\n- **Webs:** the internal diagonal and vertical members that complete the triangulation.\n- **Heel:** where top and bottom chords meet over the wall. A raised-heel (energy-heel) truss lifts the top chord to leave room for full-depth insulation at the eaves.\n\n## Common configurations\n\n- **King post truss:** a central vertical member from apex to tie; one of the simplest forms.\n- **Queen post truss:** two verticals with a horizontal member between them, suited to modest spans.\n- **Fink (W) truss:** a common house truss with webs arranged in a W pattern.\n- **Attic, scissor and mono trusses:** variants that create living space, vaulted ceilings or single-slope roofs.\n\nHistoric timber trusses, such as king-post, queen-post, crown-post and hammerbeam roofs, were framed with carpentry joints and pegs rather than metal plates.\n\n## Practical notes\n\nTrusses are engineered as a system, so cutting or removing webs or chords, for example during a loft conversion, can compromise the whole roof and generally needs an engineer's design. Bracing between trusses is part of the design and keeps them upright and stable against wind.","key_facts":[{"label":"Principle","value":"Triangulation"},{"label":"Main parts","value":"Top chords, bottom chord, webs"},{"label":"Modern joints","value":"Toothed metal connector plates"}],"regions":["Global"],"aliases":["truss","trussed rafter","roof trusses"],"related":["rafter","king-post-truss","queen-post-truss","hammerbeam-roof","purlin"],"company":null,"sources":[{"title":"Truss","url":"https://en.wikipedia.org/wiki/Truss","publisher":"Wikipedia"},{"title":"Timber roof truss","url":"https://en.wikipedia.org/wiki/Timber_roof_truss","publisher":"Wikipedia"},{"title":"Attic-Ventilation Strategies","url":"https://finehomebuilding.com/project-guides/roofing/attic-ventilation-strategies","publisher":"Fine Homebuilding"}],"country":null},{"slug":"roof-valley","title":"Roof Valley","category":"components","type":"article","summary":"A roof valley is the internal angle where two sloping roof planes meet, forming a channel that collects and carries water down to the eaves.","body":"A valley is the inward-facing junction where two roof slopes meet, the opposite of a hip. Because water from both planes converges there, a valley carries more water than any other part of the roof, and it is also where snow, ice and leaves accumulate. Valleys are therefore detailed carefully and usually given extra underlayment, such as a strip of self-adhered membrane along their full length.\n\n## Valley types on shingle roofs\n\n- **Open valley:** a continuous metal or membrane valley liner is left exposed, and the roof covering on each side is cut back to leave a visible channel. Open metal valleys are durable and handle heavy flow and debris well.\n- **Closed-cut valley:** shingles from one slope (usually the lower-pitched or smaller one) are run across the valley and up the other side; shingles from the second slope then overlap them and are cut in a straight line a short distance from the valley centreline.\n- **Woven valley:** shingles from both slopes are interlaced across the valley, course by course. It is used mainly with three-tab shingles and is generally not recommended for thick laminated shingles.\n\n## Valleys on tile, slate and metal roofs\n\n- **Open valleys** with lead, metal or GRP (glass-reinforced plastic) liners are common under tiles in the UK and Europe, sometimes with dry valley systems.\n- **Laced, swept and mitred valleys** are traditional British slate and plain-tile techniques in which tiles or slates are cut and shaped to turn the corner without exposed metal; a mitred valley uses concealed soakers.\n- **Metal roofs** use formed valley pans with the panels terminated over a closure.\n\n## Framing\n\nIn stick-framed roofs a valley rafter runs diagonally along the junction, with jack rafters from each slope landing on it. In truss roofs, one roof is often framed on top of the other's sheathing using a \"California fill\" or valley set.\n\n## Common problems\n\nDebris build-up, nails driven too close to the centreline, undersized or corroded metal, and shingles cut too short are typical causes of valley leaks.","key_facts":[{"label":"Opposite of","value":"Hip"},{"label":"Shingle valley types","value":"Open, closed-cut, woven"},{"label":"UK traditional","value":"Laced, swept, mitred valleys"}],"regions":["Global"],"aliases":["valley","open valley","closed-cut valley","woven valley","California valley"],"related":["roof-hip","roof-flashing","ice-and-water-shield","rafter","chimney-cricket"],"company":null,"sources":[{"title":"Flashing (weatherproofing)","url":"https://en.wikipedia.org/wiki/Flashing_(weatherproofing)","publisher":"Wikipedia"},{"title":"Chimneys & Crickets, Skylights, Pipes, Flues, Exhaust Vents & Solar","url":"https://open-exam-prep.com/study-guides/mi-roofing-contractor/flashings-penetrations/chimney-crickets-skylights-penetrations","publisher":"Open Exam Prep"},{"title":"Rafter","url":"https://en.wikipedia.org/wiki/Rafter","publisher":"Wikipedia"}],"country":null},{"slug":"roof-ventilation","title":"Roof Ventilation","category":"components","type":"article","summary":"Roof ventilation is the controlled flow of outside air through an attic or roof space, usually in at the eaves and out near the ridge, to remove moisture and heat.","body":"Roof ventilation moves outside air through the space between the insulation and the roof covering. In a vented attic or cold roof, its main jobs are to carry away moisture that leaks or diffuses up from the house, reducing condensation and decay, and, in cold climates, to keep the roof deck cold enough to limit snow melt and ice dams. It also lowers attic temperatures in hot weather, although insulation and air sealing usually have a bigger effect on cooling loads.\n\n## Intake and exhaust\n\nMost systems work on natural stack and wind effects: cooler air enters low, at the eaves, and warmer air leaves high, near the ridge.\n\n- **Intake vents:** perforated or slotted soffits, continuous strip vents, over-fascia vents (common in the UK) and drip-edge or roof-edge intake vents.\n- **Exhaust vents:** continuous ridge vents, individual static roof vents (box or louvre vents), gable-end louvres, wind-driven turbine vents, and powered attic ventilators.\n- **Baffles and eaves trays** keep insulation from blocking the air path at the eaves.\n\n## Balanced ventilation and code ratios (US)\n\nInternational Residential Code section R806.2 sets a minimum net free ventilating area of 1/150 of the vented space. This can be reduced to 1/300 where, among other options, 40% to 50% of the required area is provided by upper vents located no more than 3 ft (914 mm) below the ridge, with the rest at the eaves. At eave vents, a clear space of at least 1 in (25 mm) must be kept between insulation and sheathing. Vent products are rated by net free vent area so their capacity can be compared.\n\nMixing exhaust types on one roof (for example, a ridge vent alongside gable louvres or a powered fan) is widely discouraged because one outlet can draw air through another instead of through the eaves, short-circuiting the flow. Powered attic fans can also depressurise the attic and pull conditioned air from the house through ceiling leaks.\n\n## UK and European practice\n\nIn the UK, BS 5250 governs moisture control and ventilation. Cold roofs with high-resistance underlays need loft ventilation; with low-resistance (vapour-permeable) underlays and air-tight coverings, the batten space itself may need ventilating, with guidance citing openings equivalent to a 25 mm slot at the eaves and 5 mm at the ridge.\n\n## Unvented alternatives\n\nWarm roofs and unvented (conditioned) attics place insulation at the roof plane and do not rely on ventilation of the roof space; these are allowed under specific conditions.","key_facts":[{"label":"US minimum (IRC R806.2)","value":"1/150 of vented space, or 1/300 with conditions"},{"label":"Upper vents (for 1/300)","value":"40-50% within 3 ft (914 mm) of ridge"},{"label":"Insulation clearance at vents","value":"1 in (25 mm)"},{"label":"UK standard","value":"BS 5250"}],"regions":["Global"],"aliases":["attic ventilation","loft ventilation","roof vents","balanced ventilation"],"related":["ridge-vent","soffit","cold-roof","warm-roof","gable-roof","ice-dam"],"company":null,"sources":[{"title":"IRC R806 Roof Ventilation (code change proposal)","url":"https://iccsafe.org/wp-content/uploads/bcac/IRC-R806.pdf","publisher":"International Code Council"},{"title":"Attic-Ventilation Strategies","url":"https://finehomebuilding.com/project-guides/roofing/attic-ventilation-strategies","publisher":"Fine Homebuilding"},{"title":"Batten space ventilation for pitched roofs","url":"https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/LABCW%20Batten%20space%20ventilation%20for%20pitched%20roofs%20V2.pdf","publisher":"LABC Warranty"}],"country":null},{"slug":"roof-walkway-pad","title":"Roof Walkway Pad","category":"low-slope-systems","type":"term","summary":"A protective pad or roll laid on a low-slope roof membrane to create a traffic path and prevent wear and puncture from foot traffic.","body":"Roof walkway pads are sacrificial layers placed on top of a roof membrane along routes that people use, such as paths from roof hatches and access doors to HVAC units, drains and other equipment that needs regular service. They spread foot loads and take the abrasion that would otherwise wear or puncture the membrane.\n\n## Materials\n\n- **Thermoplastic walkway rolls or pads** (PVC, TPO) that are hot-air welded to matching membranes; some are made partly from recycled membrane trimmings.\n- **Rubber pads** adhered to EPDM roofs with compatible tape or adhesive.\n- **Granule-surfaced modified bitumen** walkway boards or cap-sheet strips for bituminous roofs.\n- **Concrete or composite pavers** on pedestals or protection mats, common on ballasted, inverted and green roofs.\n- **Coating walkway systems** with embedded aggregate on coated and spray-foam roofs.\n\n## Design and installation\n\nWalkways are usually laid out to give a continuous route, often in a contrasting colour such as grey or yellow on a white membrane so that walkers can follow it. Pads are typically spaced with small gaps for drainage, and must not block flow to drains. Many membrane manufacturers require walkways for warranty coverage in high-traffic areas.\n\n## Why they matter\n\nFoot traffic, dropped tools, sharp debris and equipment servicing are leading causes of punctures and wear on single-ply and coated roofs. Walkway pads are a low-cost way to reduce that damage. They are also used as a safety measure to keep people on defined, slip-resistant paths away from roof edges.\n\n## Recycled content\n\nPVC membrane manufacturers note that production trimmings can be reprocessed into rooftop walkway products, giving waste material a second use on the roof.","key_facts":[{"label":"Purpose","value":"Protect membrane along traffic routes"},{"label":"Common materials","value":"Welded PVC/TPO, rubber, mod-bit, pavers"},{"label":"Typical location","value":"Hatch to equipment routes"}],"regions":["Global"],"aliases":["walkway pad","roof walkway","traffic pad","walkpad"],"related":["single-ply-roofing","pvc-roofing","tpo-roofing","epdm-roofing","silicone-roof-coating"],"company":null,"sources":[{"title":"The ABCs of PVC Roof Membranes","url":"https://usa.sika.com/dms/getdocument.get/88a0c83a-9151-4100-84d6-dccadfebd4aa/the-abcs-of-pvc-roof-membranes.pdf","publisher":"Sika USA"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"}],"country":null},{"slug":"roof-wind-pressure-zones","title":"Roof Wind Pressure Zones","type":"term","summary":"Areas of a roof (field, edge, corner) assigned different wind design pressures because suction is strongest near edges and corners.","body":"Roof wind pressure zones are the areas into which design standards divide a roof to account for the fact that wind suction is not uniform. When wind separates from the sharp edge of a building, it forms swirling vortices that create very strong suction along the edges and especially at the corners. The middle of the roof, called the field, sees much lower pressures.\n\n## Typical zones\n\nIn the US standard ASCE 7 (Minimum Design Loads for Buildings and Other Structures), components and cladding on roofs are assigned to numbered zones:\n\n- **Field (Zone 1, and Zone 1' on some low-slope roofs):** the interior area with the lowest pressures.\n- **Edge or perimeter (Zone 2):** a strip along eaves, rakes and ridges.\n- **Corner (Zone 3):** the areas where two edges meet, with the highest pressures.\n\nZone widths are calculated from the building's dimensions and mean roof height. Hip and gable roofs have their own zone layouts and coefficients that depend on slope.\n\n## Changes in ASCE 7-16\n\nThe 2016 edition of ASCE 7 revised the roof zones significantly. For flat roofs, corner zones became L-shaped with widths based on roof height, and an extra edge zone was added; gable and hip roofs also gained additional zones. The largest negative pressure coefficients increased on most zones, in some cases roughly doubling design pressures, although lower mapped wind speeds in parts of the Midwest and West Coast and new elevation and exposure adjustments partly offset the increase. Later editions (ASCE 7-22) continued to refine the method.\n\n## Practical effects\n\nBecause corner and edge pressures are higher, roof systems often need:\n\n- closer fastener spacing or extra fasteners in perimeter and corner zones;\n- additional adhesive or attachment for low-slope membranes and insulation;\n- stronger edge metal, coping and gutters;\n- higher-rated tile or panel clips near edges.\n\nOther national standards, such as Eurocode 1 in Europe and AS/NZS 1170.2 in Australia and New Zealand, follow the same principle with their own zone layouts and terminology.\n\n## Field evidence\n\nDamage surveys after hurricanes and tornadoes consistently show roof coverings and decks failing first at corners, eaves, rakes, hips and ridges, confirming the zone approach.","key_facts":[{"label":"Highest pressure zone","value":"Corners (ASCE 7 Zone 3)"},{"label":"Lowest pressure zone","value":"Field (Zones 1 and 1')"},{"label":"Major revision","value":"ASCE 7-16 changed zone shapes and raised many coefficients"},{"label":"Other standards","value":"Eurocode 1, AS/NZS 1170.2 (own zone layouts)"}],"regions":["Global","North America","Europe","Oceania"],"aliases":["roof wind zones","corner zone","perimeter zone","field zone","components and cladding zones"],"related":["wind-uplift","hurricane-roof-damage","tornado-roof-damage","solar-roof-mounting"],"sources":[{"title":"Determining Components and Cladding Roof Design Pressures","url":"https://structuremag.org/?p=13322","publisher":"STRUCTURE magazine"},{"title":"ASCE 7 and roof wind design (SPRI technical bulletin 2022.2)","url":"https://www.spri.org/wp-content/uploads/2022/10/2022.2-ASCE-7.pdf","publisher":"SPRI"},{"title":"Tornado Outbreak of 2011 Mitigation Assessment Team Report, Chapter 4 (FEMA P-908)","url":"https://webarchive.library.unt.edu/web/20161127152300/https://www.fema.gov/media-library-data/20130726-1827-25045-9156/tornado_mat_chapter4_508.pdf","publisher":"FEMA (archived by UNT Libraries)"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roof-to-wall-connection","title":"Roof-to-Wall Connection","type":"term","summary":"The joint that fastens rafters or trusses to the top of the walls; a key link in the load path that keeps a roof on in high winds.","body":"The roof-to-wall connection is where roof framing (rafters or trusses) bears on and is fastened to the top plate of the walls. In ordinary weather it mostly carries the roof's weight downward. In a hurricane or tornado, the direction reverses: wind suction and internal pressure try to lift the roof, and this connection must hold it down and pass the force into the walls and on to the foundation.\n\n## Why it matters\n\nEngineers describe the goal as a continuous load path: deck fastened to framing, framing fastened to walls, walls fastened to floors and foundation. A roof is only as strong as the weakest link in that chain. FEMA's Mitigation Assessment Team, reporting on the April 2011 tornado outbreak (including Tuscaloosa, Alabama) and the May 2011 Joplin, Missouri tornado, found that the roof-to-wall connection was the weak link most often responsible for losing the whole roof structure.\n\n## Connection types\n\n- **Toenailing.** Nails driven at an angle through the rafter or truss into the top plate. This was common in older wood-frame houses and offers limited uplift resistance.\n- **Metal connectors.** Hurricane ties, clips and straps made of galvanized or stainless steel, nailed to both the framing member and the wall. They resist uplift and also sliding and racking.\n- **Engineered connections.** In masonry walls, straps are embedded in concrete bond beams; in some codes, connectors are sized for site-specific design loads.\n\n## Installation details that affect strength\n\nFEMA's 2011 tornado report found metal connectors outperformed toenail-only connections, but only when installed according to the manufacturer's instructions. Using the wrong nails sharply reduced capacity: the report cited roughly 96 lb (about 43 kg) of withdrawal capacity for a 6d box nail versus 217 lb (about 98 kg) for a 10d common nail. Placing connectors only on every second or third rafter, a historical practice, was often inadequate. Over-notched rafter seats also contributed to failures.\n\n## Retrofitting\n\nExisting homes can be upgraded by adding connectors from the outside, often while the roof covering is off during replacement, or from inside the attic where access allows. Research by Home Innovation Research Labs and guidance in trade publications describe retrofit straps and approaches for different wall types. In Florida, wind mitigation inspections record the type of roof-to-wall attachment because it affects insurance premiums.\n\n## Regional practice\n\nHigh-wind regions, including Florida, the Gulf Coast, coastal Australia (cyclone regions) and parts of the Caribbean, generally require tied-down roof framing. Wider adoption elsewhere has been encouraged after tornado investigations showed that coastal-style details also help inland.","key_facts":[{"label":"Role","value":"Transfers roof uplift into walls and foundation"},{"label":"Common weak detail","value":"Toenail-only attachment"},{"label":"6d box nail withdrawal (FEMA 2011)","value":"About 96 lb (43 kg)"},{"label":"10d common nail withdrawal (FEMA 2011)","value":"About 217 lb (98 kg)"}],"regions":["Global","North America","Oceania","Latin America"],"aliases":["roof-to-wall attachment","rafter-to-wall connection","truss-to-wall connection","continuous load path"],"related":["hurricane-tie","hurricane-roof-damage","tornado-roof-damage","wind-uplift","fortified-roof"],"sources":[{"title":"Tornado Outbreak of 2011 Mitigation Assessment Team Report, Chapter 4 (FEMA P-908)","url":"https://webarchive.library.unt.edu/web/20161127152300/https://www.fema.gov/media-library-data/20130726-1827-25045-9156/tornado_mat_chapter4_508.pdf","publisher":"FEMA (archived by UNT Libraries)"},{"title":"Retrofit Improvements: Roof-to-Wall Connection","url":"https://www.homeinnovation.com/-/media/Files/Reports/Retrofit-Improvements-Roof-to-Wall-Connection.pdf","publisher":"Home Innovation Research Labs"},{"title":"Strengthening Roof-to-Wall Connections","url":"https://www.jlconline.com/coastal-contractor/strengthening-roof-to-wall-connections.aspx","publisher":"JLC (Journal of Light Construction)"},{"title":"Hurricane tie","url":"https://en.wikipedia.org/wiki/Hurricane_tie","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roofing-apprenticeship","title":"Roofing Apprenticeship","category":"organizations","type":"article","summary":"Structured training that combines paid work with classroom instruction to qualify roofers; length, content and certification differ widely by country.","body":"A roofing apprenticeship is a period of structured training in which a trainee works for a roofing employer while also receiving technical instruction, usually ending in an assessment and a recognised qualification. Many roofers worldwide still learn informally on the job, but most industrialised countries offer a formal route. Programmes differ in length, in whether roofing is one trade or several, and in how far certification is required to work.\n\n## Germany\n\nIn Germany the Dachdecker (roofer) trade is governed by the Dachdeckerausbildungsverordnung (DachAusbV) of 28 April 2016, which took effect on 1 August 2016 and replaced the 1998 regulation.\n\n- **Length:** three years.\n- **Structure:** in-company training supported by vocational school, plus 15 weeks at inter-company training centres.\n- **Specialisations:** roof covering (Dachdeckungstechnik), waterproofing (Abdichtungstechnik), exterior wall cladding, energy technology on roofs and walls, and thatched roofing (Reetdachtechnik).\n- **Exams:** an interim examination by the end of the second year and a journeyman's examination (Gesellenprüfung) at the end. The largest part of the final exam is a practical task of up to 14 hours, worth 60% of the result.\n\n## England\n\nEngland's Roofer apprenticeship standard (ST0270) is a Level 2 qualification with a typical duration of 18 to 24 months and a funding cap of £11,000. All apprentices complete a common core and then one of three options:\n\n- **Roof Slater and Tiler**, for slate and tile coverings;\n- **Waterproof Membranes Installer**, for flat roofs and pitched roofs over 10 degrees;\n- **Roof Sheeter and Cladder**, for metal sheet roofing and wall cladding on commercial buildings.\n\nThe apprenticeship ends with an independent end-point assessment.\n\n## Canada\n\nRoofer is a Red Seal trade, which allows certified tradespeople to work across provinces. The Red Seal occupational standard recommends training in three levels totalling 5,400 hours of on-the-job and in-school training, and the interprovincial exam has 125 questions. Low-slope roofing carries the largest weight (31%) in the exam. The trade is called Roofer in 12 provinces and territories and Roofer, Damp and Waterproofer in British Columbia. The scope covers membrane roofing and steep-slope materials such as shingles, slate, shakes, tile and sheet metal, as well as waterproofing and damp-proofing.\n\n## United States\n\nThe US Bureau of Labor Statistics notes that most roofers learn on the job, while some enter through apprenticeships that combine a set number of hours of paid work with technical instruction. Many registered programmes are run by local joint apprenticeship committees linked to the United Union of Roofers, Waterproofers and Allied Workers. Most employers require safety training that meets OSHA guidelines. Roofers held about 166,900 jobs in 2025.\n\n## Common themes\n\nAcross countries, apprenticeships share several elements: safe work at height, reading drawings and measuring, material quantities, and practical skill in at least one roofing system. Specialist heritage trades, such as thatching and leadwork, often have separate training paths through craft bodies.","key_facts":[{"label":"Germany","value":"Dachdecker, 3 years (DachAusbV 2016)"},{"label":"England","value":"Roofer ST0270, Level 2, 18-24 months"},{"label":"Canada","value":"Red Seal Roofer, 5,400 hours in 3 levels"},{"label":"United States","value":"Mostly on-the-job; local registered apprenticeships"}],"regions":["Global","Europe","North America"],"aliases":["roofer apprenticeship","roofing training","Dachdecker Ausbildung","roofer qualification"],"related":["citb","lead-sheet-training-academy","national-society-of-master-thatchers","fragile-roof","thatching-advisory-services"],"company":null,"sources":[{"title":"Verordnung über die Berufsausbildung zum Dachdecker und zur Dachdeckerin (DachAusbV)","url":"https://www.gesetze-im-internet.de/dachausbv/BJNR099400016.html","publisher":"German Federal Ministry of Justice"},{"title":"Roofer (ST0270)","url":"https://skillsengland.education.gov.uk/apprenticeships/st0270-v1-1","publisher":"Skills England"},{"title":"Red Seal Occupational Standard - Roofer","url":"https://www.red-seal.ca/eng/trades/roof/2022-overview.shtml","publisher":"Red Seal Program"},{"title":"Roofers: Occupational Outlook Handbook","url":"https://www.bls.gov/ooh/construction-and-extraction/roofers.htm","publisher":"US Bureau of Labor Statistics"}],"country":null},{"slug":"roofing-asphalt","title":"Roofing Asphalt (BUR Asphalt Types)","category":"low-slope-systems","type":"term","summary":"Oxidised asphalt graded by softening point (ASTM D312 Types I-IV) for mopping built-up and modified bitumen roofs at different slopes.","body":"Roofing asphalt is the hot-applied bitumen used to laminate the plies of built-up roofs and to mop down some modified bitumen sheets. In North America it is specified by ASTM D312, which divides mopping asphalt into four types by softening point and by how much the material tends to flow on a slope.\n\n## ASTM D312 types\n\n- **Type I (dead level):** softening point about 57 to 66 C (135 to 151 F); for slopes of about 1/2 in per 12 in or less.\n- **Type II (flat):** moderate flow resistance; about 1/2 to 1 1/2 in per 12 in. It is now hard to find in many markets.\n- **Type III (steep):** relatively resistant to flow; about 1 to 3 in per 12 in.\n- **Type IV (special steep):** softening point about 99 to 107 C (210 to 225 F); about 2 to 6 in per 12 in, and suitable for flashings.\n\nTypes III and IV make up most hot roofing asphalt sold, about 95% by one industry estimate.\n\n## Application\n\nAsphalt is heated in a kettle or tanker and applied at its equiviscous temperature (EVT), the temperature at which it has the right viscosity: about 125 centipoise for hand mopping and 75 centipoise for mechanical spreaders. Overheating makes it brittle; underheating applies too much material, which can create a slip plane. A typical rate is about 25 lb per 100 sq ft per ply (about 1.2 kg/m2).\n\n## Other binders\n\nOther standards cover oxidised asphalt (ASTM D7654) and SEBS polymer-modified asphalt (ASTM D6152). Wax-modified and polymer-modified low-fuming asphalts were developed from the 1980s onward to cut application temperatures and fumes; some form a skin on the kettle that traps fumes.\n\n## Health\n\nUS NIOSH identified roofing asphalt fumes as a potential occupational carcinogen in 2000 and published work-practice guidance in 2003 and 2007. In 2011 IARC classified occupational exposure to oxidised bitumen during roofing as probably carcinogenic to humans.","key_facts":[{"label":"Standard","value":"ASTM D312 (Types I-IV)"},{"label":"Most used","value":"Types III and IV"},{"label":"EVT targets","value":"125 cP mop; 75 cP mechanical spreader"},{"label":"Typical mopping rate","value":"About 1.2 kg/m2 per ply (25 lb per square)"}],"regions":["North America"],"aliases":["mopping asphalt","BURA","built-up roofing asphalt","hot asphalt"],"related":["built-up-roofing","coal-tar-pitch-roofing","modified-bitumen-roofing"],"company":null,"sources":[{"title":"The evolution of built-up roofing asphalt","url":"https://www.asphaltmagazine.com/buraevolution/","publisher":"Asphalt Magazine"},{"title":"Low-slope roofing systems: built-up roofs and modified bitumen","url":"https://buildingenclosureonline.com/articles/82366-low-slope-roofing-systems-built-up-roofs-and-modified-bitumen","publisher":"Building Enclosure"},{"title":"Rules for long-lasting BUR systems (H. H. Pierce, Interface, Oct 2006)","url":"https://iibec.org/wp-content/uploads/2006-10-Pierce.pdf","publisher":"IIBEC"},{"title":"BUR performance (Janicki and Trumbore, Interface, Aug 2003)","url":"https://iibec.org/wp-content/uploads/2003-08-Janicki-Trumbore.pdf","publisher":"IIBEC"}],"country":null},{"slug":"roofing-association-of-new-zealand","title":"Roofing Association of New Zealand (RANZ)","summary":"RANZ is New Zealand's national roofing trade association, whose vetted members follow a Code of Practice for workmanship, compliance and conduct.","body":"The Roofing Association of New Zealand (RANZ) is the national trade association for roofing businesses in New Zealand. It runs a nationwide network of member companies and lists a postal address in North Harbour, Auckland. Its website is ranz.co.nz.\n\n## Membership\n\nRANZ members are vetted against entry criteria and must follow the association's Code of Practice, which sets standards for workmanship, compliance with regulations and professional conduct. The association states that all members meet industry standards for quality, safety and professionalism. Its website offers a member search for property owners looking for roofers.\n\n## Activities\n\n- **Training and skills.** RANZ supports training and career pathways for roofers, including apprenticeships.\n- **Technical support.** It provides guidance to members on compliance with the New Zealand Building Code and on good roofing practice.\n- **Advocacy.** It represents roofing businesses in discussions with government and other industry bodies.\n\n## New Zealand roofing context\n\nNew Zealand's most common roof covering is profiled metal, typically coated steel, used on both houses and commercial buildings. Other materials include pressed metal tiles, concrete and clay tiles, membranes and asphalt shingles. The climate ranges from subtropical in the north to alpine in the south, with high winds, heavy rain and coastal salt exposure in many areas, so corrosion and weathertightness are major concerns.\n\nKey technical documents include the New Zealand Building Code clause E2 (External Moisture) and its Acceptable Solution E2/AS1, and the NZ Metal Roof and Wall Cladding Code of Practice published by the New Zealand Metal Roofing Manufacturers association.\n\n## Licensing\n\nIn New Zealand, certain building work on homes, including roofing, is classed as restricted building work and must be carried out or supervised by a Licensed Building Practitioner (LBP). The LBP scheme has a roofing licence with classes for membrane, metal tile, profiled metal, shingles, torch-on and liquid roofing. RANZ membership is separate and voluntary.\n\n## Related bodies\n\nBRANZ, the Building Research Association of New Zealand, provides independent research and guidance used by roofers and designers.","key_facts":[{"label":"Country","value":"New Zealand"},{"label":"Membership","value":"Vetted roofing businesses following a Code of Practice"},{"label":"Address","value":"North Harbour, Auckland"},{"label":"Website","value":"ranz.co.nz"}],"regions":["Oceania"],"aliases":["RANZ"],"related":["new-zealand-metal-roofing-manufacturers","branz","how-to-find-a-licensed-roofer"],"company":{"website":"https://www.ranz.co.nz","known_for":["Roofing Code of Practice for members"]},"sources":[{"title":"Roofing Association of New Zealand","url":"https://www.ranz.co.nz/","publisher":"RANZ"},{"title":"Roofing licence classes","url":"https://www.lbp.govt.nz/about-lbp/licence-classes/roofing/","publisher":"Licensed Building Practitioners (MBIE)"}],"category":"organizations","type":"organization","country":null},{"slug":"roofing-contractor-magazine","title":"Roofing Contractor (magazine)","summary":"Roofing Contractor is a U.S. trade magazine for roofing businesses, published by BNP Media and known for its annual Top 100 Roofing Contractors list.","body":"*Roofing Contractor* is a trade magazine for the roofing industry in the United States, published by BNP Media. It appears in print and online at roofingcontractor.com and is issued monthly. It is the official show publication of the International Roofing Expo.\n\n## Content\n\nThe magazine covers the business and technical sides of roofing for both residential and commercial contractors. Its content includes:\n\n- news on companies, associations, codes and regulations;\n- technical articles on roof systems, installation and safety;\n- business management, sales, marketing and workforce topics;\n- product coverage and case studies of roofing projects.\n\nOver the years it has published many articles on association programs, such as the Roofing Contractors Association of Texas voluntary licence, and on recovery efforts after hurricanes.\n\n## Recurring features\n\n- **Top 100 Roofing Contractors.** An annual ranking of large U.S. roofing contractors by revenue, which is widely cited in the industry. The 2026 list was published in the magazine.\n- **Roofing Contractor of the Year** recognition.\n- **Young Guns**, recognising younger leaders in the industry.\n- **State of the Industry** reports based on surveys of contractors.\n\n## Other activities\n\nBNP Media's roofing brand also runs the Best of Success conference for roofing business owners, as well as podcasts, webinars and videos.\n\n## Related publications\n\nIn the United States, the National Roofing Contractors Association publishes *Professional Roofing*. Regional titles serve particular areas, such as *Western Roofing* and *Florida Roofing*. In other countries, roofing contractors rely on titles such as *Roofing Today* in the UK and national association journals in Europe and Australasia.","key_facts":[{"label":"Publisher","value":"BNP Media"},{"label":"Frequency","value":"Monthly"},{"label":"Known for","value":"Annual Top 100 Roofing Contractors list"},{"label":"Show role","value":"Official publication of the International Roofing Expo"}],"regions":["North America"],"aliases":["Roofing Contractor"],"related":["professional-roofing-magazine","international-roofing-expo","roofing-today"],"company":{"website":"https://www.roofingcontractor.com","parent":"BNP Media","known_for":["Top 100 Roofing Contractors list","Best of Success conference"]},"sources":[{"title":"Roofing Contractor home page","url":"https://www.roofingcontractor.com/","publisher":"BNP Media"},{"title":"International Roofing Expo home page","url":"https://theroofingexpo.com/en/home.html","publisher":"Informa Markets"}],"category":"organizations","type":"organization","country":null},{"slug":"roofing-contractors-association-of-british-columbia","title":"Roofing Contractors Association of British Columbia (RCABC)","summary":"RCABC is the roofing contractors' association for British Columbia, Canada, established in 1958 and known for its RoofStar Guarantee program and Roofing Practices Manual.","body":"The Roofing Contractors Association of British Columbia (RCABC) is a provincial trade association for roofing contractors in British Columbia, Canada. It traces its start to 1958 and operates the website rcabc.org.\n\nRCABC members are roofing contractors working on commercial, institutional and residential buildings in the province, along with suppliers, manufacturers and inspection firms. The association is affiliated with the Canadian Roofing Contractors Association (CRCA) and the U.S.-based National Roofing Contractors Association (NRCA).\n\n## RoofStar Guarantee\n\nRCABC is best known for the **RoofStar Guarantee** program (the program's proper name), a third-party warranty program for roofs installed by RCABC member contractors. The association dates its first roofing industry warranty to 1960. Coverage applies to both workmanship and materials, and an independent observer meeting RCABC qualifications monitors the installation and carries out follow-up performance reviews. In late 2024 RCABC launched an additional program for green (vegetated) roofs.\n\nBecause RoofStar Guarantee coverage can only be issued for work by member contractors, building owners and architects in British Columbia often specify it in contract documents for commercial projects.\n\n## Technical and training work\n\n- **Roofing Practices Manual (RPM).** RCABC publishes the RPM, a set of technical standards and details for roof systems accepted under its program. It is widely used in the province by designers and inspectors.\n- **Training Centre.** The association operates a training centre for roofing apprentices and workers, which it describes as the first educational facility in North America designed for and dedicated to training the entire roofing industry.\n- **Inspector network.** RCABC lists accredited independent inspection firms that review projects registered under the program.\n\n## Context\n\nBritish Columbia's coastal climate brings long periods of rain, and its interior has snow loads and freeze-thaw cycles. These conditions shape the association's emphasis on low-slope waterproofing, inspection and maintenance guidance. Homeowners looking for a roofer in the province can use RCABC's member directory, though provincial business licensing and municipal permits remain separate requirements.","key_facts":[{"label":"Established","value":"1958"},{"label":"Region","value":"British Columbia, Canada"},{"label":"Known for","value":"RoofStar Guarantee program; Roofing Practices Manual"},{"label":"Affiliations","value":"CRCA, NRCA"}],"regions":["North America"],"aliases":["RCABC","Roofing Contractors Association of BC","RoofStar","RoofStar Guarantee"],"related":["canadian-roofing-contractors-association","nrca","how-to-find-a-licensed-roofer","green-roof"],"company":{"founded":"1958","website":"https://www.rcabc.org","known_for":["RoofStar Guarantee program","Roofing Practices Manual","Roofing training centre"]},"sources":[{"title":"About RCABC","url":"https://www.rcabc.org/about/about-rcabc/","publisher":"RCABC"},{"title":"RCABC launches new green roofing program","url":"https://www.rcabc.org/rcabc-launches-new-green-roofing-program/","publisher":"RCABC"},{"title":"RoofStar Guarantee","url":"https://www.rcabc.org/roofstar-guarantee/","publisher":"RCABC"}],"category":"organizations","type":"organization","country":null},{"slug":"roofing-contractors-association-of-texas","title":"Roofing Contractors Association of Texas (RCAT)","summary":"RCAT is a Texas trade association for roofing contractors, active since 1975, which runs a voluntary roofing contractor licence program.","body":"The Roofing Contractors Association of Texas (RCAT) is a statewide trade association for roofing contractors and related businesses in Texas, United States. It describes itself as supporting Texas roofing since 1975 and lists a mailing address in Fort Worth.\n\n## Voluntary licensing\n\nTexas does not require roofing contractors to hold a state licence. Because of this gap, RCAT created its own voluntary credential. After more than two decades of lobbying the state for mandatory licensing, the association rebranded its earlier \"RCAT Certification\" as the \"RCAT Roofing License\" in 2017. The program does not carry the force of law, but it gives property owners a way to identify contractors who have met set requirements.\n\nUnder the program as described in 2017, applicants:\n\n- choose a commercial, residential or combined licence and pass a matching exam, plus a required business and safety exam;\n- carry general liability and workers' compensation insurance;\n- for commercial work, show they can provide a performance bond;\n- pass a background check and sign a notarised statement covering felony convictions, abandoned roofing contracts and bankruptcy;\n- complete 10 hours of roofing-related continuing education to keep the licence.\n\n## Events\n\nRCAT organises the Texas Roofing Conference, which it describes as the largest roofing event in the state.\n\n## Context\n\nTexas is exposed to hail, high winds, hurricanes on the Gulf Coast and extreme heat. After major storms, out-of-state and unqualified contractors often arrive to seek repair work, a pattern sometimes called \"storm chasing\". RCAT's voluntary licence and its participation in recovery efforts, such as after Hurricane Harvey in 2017, are aimed partly at helping owners avoid scams. Homeowners in Texas should still check local permit rules, insurance and references, since a state licence does not exist for roofing.","key_facts":[{"label":"Active since","value":"1975"},{"label":"State","value":"Texas, USA"},{"label":"Known for","value":"Voluntary RCAT Roofing License"},{"label":"Event","value":"Texas Roofing Conference"}],"regions":["North America"],"aliases":["RCAT"],"related":["nrca","how-to-find-a-licensed-roofer","hail-damage"],"company":{"founded":"1975","website":"https://www.rcat.net","known_for":["RCAT Roofing License (voluntary)","Texas Roofing Conference"]},"sources":[{"title":"RCAT home page","url":"https://www.rcat.net/","publisher":"Roofing Contractors Association of Texas"},{"title":"The Roofing Contractors Association of Texas creates a licensing program to help prevent scams","url":"https://www.roofingcontractor.com/articles/92243-the-roofing-contractors-association-of-texas-creates-a-licensing-program-to-help-prevent-scams","publisher":"Roofing Contractor"},{"title":"Texas roofing contractors, industry associations assist with Hurricane Harvey recovery efforts","url":"https://www.roofingcontractor.com/articles/92437-texas-roofing-contractors-industry-associations-assist-with-hurricane-harvey-recovery-efforts","publisher":"Roofing Contractor"}],"category":"organizations","type":"organization","country":null},{"slug":"roofing-fall-protection","title":"Roofing Fall Protection","category":"installation","type":"article","summary":"Roofing fall protection is the set of legal duties and equipment, such as guardrails, nets, harness systems and warning lines, that prevent roofers falling.","body":"Falls from roofs are one of the leading causes of death in construction. The UK Health and Safety Executive reports that almost one in five construction deaths involve roof work. Every major jurisdiction regulates fall protection for roofers, although thresholds and accepted methods differ.\n\n## United States (OSHA)\n\nUnder 29 CFR 1926.501, construction workers on surfaces with an unprotected side or edge **6 feet (1.8 m)** or more above a lower level must be protected by guardrails, safety nets or personal fall arrest systems.\n\n- **Low-slope roofs** (4:12 or less): roofing work may also be protected by a **warning line system combined with a safety monitoring system**, or by a safety monitor alone on roofs **50 ft (15.25 m)** or less wide.\n- **Steep roofs:** guardrails with toeboards, safety nets or personal fall arrest systems.\n- **Residential construction:** conventional systems are required unless the employer can show they are infeasible or create a greater hazard, in which case a written, site-specific **fall protection plan** prepared by a qualified person may be used. OSHA guidance says slide guards cannot be used alone as a substitute for conventional fall protection.\n\n## Canada\n\nProvincial regulations apply. Canadian roofing industry guidance covers guardrails, travel restraint, fall arrest and anchor systems, and notes that a fall arrest system must keep the peak arrest force at or below 8 kN.\n\n## United Kingdom\n\nThe **Work at Height Regulations 2005** require employers to avoid work at height where reasonably practicable, then to prevent falls, then to minimise the distance and consequences of any fall. HSE guidance calls for edge protection at eaves, double guardrails and toeboards on flat roofs, and treating every roof as fragile until a competent person confirms otherwise.\n\n## Australia\n\nModel WHS codes of practice set a hierarchy from eliminating the hazard through passive fall prevention (guardrails, catch platforms), travel restraint and fall arrest, down to ladders and administrative controls.\n\n## Common equipment\n\nGuardrail and parapet systems, scaffolding at eaves, roof brackets with planks, safety nets, warning lines, harnesses with lanyards or self-retracting lifelines, and permanent or temporary roof anchors. Fall arrest systems also require a rescue plan, since a person suspended in a harness needs prompt rescue.","key_facts":[{"label":"US trigger height","value":"6 ft (1.8 m)"},{"label":"US low-slope definition","value":"4:12 or less"},{"label":"Safety monitor alone (US)","value":"Roofs 50 ft (15.25 m) wide or less"},{"label":"UK share of construction deaths","value":"Almost 1 in 5 involve roof work"}],"regions":["Global"],"aliases":["fall protection for roofers","roof safety","roofing safety"],"related":["warning-line-system","personal-fall-arrest-system","work-at-height-regulations-2005","australian-whs-roof-work","ladder-safety","roof-brackets"],"company":null,"sources":[{"title":"1926.501 Duty to have fall protection","url":"https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.501","publisher":"U.S. Occupational Safety and Health Administration"},{"title":"Fall Protection in Residential Construction: Frequently Asked Questions","url":"https://www.osha.gov/residential-fall-protection/faq","publisher":"U.S. Occupational Safety and Health Administration"},{"title":"Roof work","url":"https://hse.gov.uk/construction/safetytopics/roofwork.htm","publisher":"Health and Safety Executive (UK)"},{"title":"The Work at Height Regulations 2005, regulation 6","url":"https://www.legislation.gov.uk/uksi/2005/735/regulation/6","publisher":"legislation.gov.uk"},{"title":"Canadian Roofing Reference Manual: 1.6.3 Fall Arrest Systems","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-1-safety/1-6-fall-protection/1-6-3-fall-arrest-systems/","publisher":"Canadian Roofing Contractors Association"},{"title":"Work Health and Safety (Preventing Falls in Housing Construction) Code of Practice 2015","url":"https://legislation.gov.au/F2016L00411/asmade/2016-03-30/text/original/epub/OEBPS/document_1/document_1.html","publisher":"Federal Register of Legislation (Australia)"}],"country":null},{"slug":"roofing-fasteners","title":"Roofing Fasteners (Nails and Screws)","category":"components","type":"article","summary":"Roofing fasteners are the nails, screws and clips that secure decks, underlayments and roof coverings, chosen for holding power and corrosion resistance.","body":"Fasteners hold every layer of a roof in place, and in storms they are often the weak link. Roofing uses a range of nails, screws and clips selected for the substrate, the covering, wind exposure and corrosion conditions.\n\n## Roofing nails\n\n- **Roofing (clout) nails:** short nails with broad flat heads that hold asphalt shingles, felt and similar sheet products without tearing through.\n- **Ring-shank (annular ring) nails:** shanks with a series of ridges that grip the wood fibres and resist withdrawal much better than smooth shanks. They are widely specified for sheathing, battens and coverings in high-wind areas.\n- **Coatings and metals:** galvanised steel (hot-dip galvanising gives high corrosion resistance) is common; copper nails are used with slate and copper flashing; stainless steel is used in coastal and long-life roofs.\n- **Sizing:** in the US, nail length is denoted by penny size with a \"d\" suffix; for example, 6d is about 2 in (51 mm). Sheathing panels are commonly fixed with 8d nails.\n\n## Screws and specialty fasteners\n\n- **Self-drilling or wood-gripping screws with sealing washers** fix exposed-fastener metal roofing panels; the bonded washer, typically EPDM rubber, seals the hole. Over-tightening can crush the washer, while under-tightening leaves gaps.\n- **Spring-head (umbrella-head) nails** with rubber gaskets and ring shanks are a traditional fixing for corrugated metal sheets.\n- **Clips:** concealed clips fix standing-seam metal panels while allowing thermal movement.\n- **Tile clips, hooks and storm clips:** used in tile and slate roofing; UK BS 5534 sets fixing requirements that depend on wind exposure.\n- **Plates and screws:** used to fix insulation and membranes on low-slope roofs.\n\n## Good practice\n\n- Follow the roof covering manufacturer's nailing pattern; wind ratings depend on it.\n- Drive nails flush, not overdriven or angled.\n- Use fasteners compatible with flashing metals and with preservative-treated timber to avoid corrosion.","key_facts":[{"label":"Withdrawal-resistant nail","value":"Ring-shank (annular)"},{"label":"Metal panel seal","value":"Screw with EPDM washer"},{"label":"US 6d nail","value":"About 2 in (51 mm)"}],"regions":["Global"],"aliases":["roofing nails","ring-shank nails","roofing screws","metal roofing screws"],"related":["roof-sheathing","roof-battens","roof-flashing","pipe-boot"],"company":null,"sources":[{"title":"Nail (fastener)","url":"https://en.wikipedia.org/wiki/Nail_(fastener)","publisher":"Wikipedia"},{"title":"Inspecting Roof Panel Sheathing","url":"https://nachi.org/inspect-roof-sheathing.htm","publisher":"InterNACHI"},{"title":"The use of vapour permeable underlays in compliance with BS 5534","url":"https://rcimag.co.uk/sandtoft-blog/the-use-of-vapour-permeable-underlays-in-compliance-with-bs-5534","publisher":"Roofing Cladding & Insulation (RCI) magazine"}],"country":null},{"slug":"roofing-fatality-statistics","title":"Roofing Fatality Statistics","type":"article","summary":"Data showing roofing as one of the deadliest occupations in the United States, with falls causing most deaths.","body":"Roofing is consistently one of the most dangerous occupations measured by fatal injury rates. Work at height on sloped and often wet or hot surfaces, near unprotected edges, skylights and openings, exposes roofers to serious fall hazards.\n\n## United States data\n\nThe US Bureau of Labor Statistics (BLS) Census of Fatal Occupational Injuries reports both the number of deaths and the rate per 100,000 full-time equivalent workers.\n\n- **2024:** roofers had a fatal injury rate of 48.7 per 100,000 full-time equivalent workers, with 104 deaths. This was the third-highest rate among the occupations BLS highlighted, behind logging workers (110.4) and fishing and hunting workers (88.8). The rate for all workers was 3.3.\n- **2023:** according to Roofing Contractor's analysis of BLS data, the roofing industry had a rate of 51.8 per 100,000 with 134 deaths, and roofers as an occupation recorded 113 deaths. Roofing ranked as the third-deadliest civilian occupation, down from second in 2022.\n\n## Falls\n\nFalls, slips and trips account for most roofing deaths. In 2023, falls caused 82 percent of roofing industry deaths (110 of 134) and 84 percent of deaths among roofers as an occupation (95 of 113).\n\n## Other hazards\n\n- Heat stress, especially in summer and on dark roofs;\n- Electrocution from overhead power lines and equipment;\n- Burns from hot asphalt and torches;\n- Struck-by injuries from falling materials and equipment;\n- Musculoskeletal strain from lifting and kneeling.\n\n## Prevention\n\nCommon controls include guardrails, personal fall arrest systems with secure anchors, safety nets, warning lines on low-slope roofs, skylight screens, ladder safety, training, heat illness programs, and planning work to keep people away from edges. In the United States, OSHA regulations set fall protection requirements for construction, and many other countries have equivalent work-at-height rules.\n\n## Interpreting the figures\n\nYear-to-year changes can reflect both safety performance and changes in employment levels and data methods. Occupation counts (roofers) and industry counts (all workers in roofing contractors' businesses) differ, so it is important to cite which measure and year are being used.","key_facts":[{"label":"Roofer fatal injury rate (2024, BLS)","value":"48.7 per 100,000 FTE"},{"label":"Roofer deaths (2024)","value":"104"},{"label":"All-worker rate (2024)","value":"3.3 per 100,000 FTE"},{"label":"Share from falls (2023, industry)","value":"82%"}],"regions":["North America"],"aliases":["roofer deaths","roofing safety statistics","roofing injury rate"],"related":["roofing-workforce","roofing-fall-protection","roofing-market-size"],"sources":[{"title":"Rate and number of fatal work injuries in selected occupations","url":"https://www.bls.gov/charts/census-of-fatal-occupational-injuries/rate-and-number-of-fatal-work-injuries-in-selected-occupations.htm","publisher":"US Bureau of Labor Statistics"},{"title":"Roofing Remains a Top 3 Deadliest Occupation in the U.S.","url":"https://www.roofingcontractor.com/articles/100253-roofing-remains-a-top-3-deadliest-occupation-in-the-us","publisher":"Roofing Contractor"},{"title":"Construction industry fatalities rose in 2023","url":"https://nrca.net/RoofingNews/construction-industry-fatalities-rose-in-2023.1-9-2025.12515/Details/Story","publisher":"National Roofing Contractors Association"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roofing-felt","title":"Roofing Felt (#15 and #30)","category":"components","type":"term","summary":"Roofing felt is a bitumen-saturated base sheet used as underlayment; in North America it is sold as #15 and #30 grades under ASTM D226.","body":"Roofing felt is a sheet of organic or inorganic base material saturated with bitumen (asphalt or, historically, coal-tar pitch). It has been used for well over a century as an underlayment beneath shingles, tiles and slates, and as plies in built-up flat roofs. It is also known as tar paper, felt paper or, in Britain, sarking felt.\n\n## Grades\n\nIn North America the familiar names are **#15** and **#30** felt. The numbers come from the weight of the original organic felts: about 15 lb or 30 lb per 100 sq ft (roughly 0.7 or 1.5 kg/m²). Modern bases are lighter, so the products no longer weigh what their names suggest, but the names remain in use.\n\n- **ASTM D226** (asphalt-saturated organic felt used in roofing and waterproofing) covers Type I (#15) and Type II (#30), perforated or non-perforated.\n- **ASTM D4869** covers asphalt-saturated organic felt underlayment for steep-slope roofing in four types, from #8 to #26. Its 2003 revision added a shower test for liquid water and limits on wrinkling.\n\n## Base materials\n\nEarly felts were made from recycled rag fibre, hessian or cellulose. Organic bases had fallen to about 5% of the market by 1987. Fibreglass bases were developed in the 1950s; asbestos bases were used earlier and later banned.\n\n## Use and limits\n\nHeavier felt is generally used under longer-lived coverings and on lower slopes; for example, double layers of #30 under slate or tile versus a single #15 under shingles on a steep roof. Felt can wrinkle when wet, tears more easily than synthetics, and is degraded by prolonged heat and UV exposure, so it should be covered promptly. In many markets synthetic underlayments have largely replaced it on new steep-slope roofs, though felt is still widely sold.","key_facts":[{"label":"Grades","value":"#15 (Type I), #30 (Type II)"},{"label":"Standards","value":"ASTM D226, ASTM D4869"},{"label":"Fibreglass base developed","value":"1950s"}],"regions":["North America","Global"],"aliases":["tar paper","felt paper","sarking felt","#15 felt","#30 felt"],"related":["roofing-underlayment","ice-and-water-shield","roof-sheathing"],"company":null,"sources":[{"title":"Roofing felt","url":"https://en.wikipedia.org/wiki/Roofing_felt","publisher":"Wikipedia"},{"title":"Drip Edge and the IRC","url":"https://www.jlconline.com/how-to/framing/drip-edge-and-the-irc_o/","publisher":"JLC"}],"country":null},{"slug":"roofing-granules","title":"Roofing Granules","type":"term","summary":"Crushed, often ceramic-coated mineral particles embedded in the top surface of asphalt shingles and roll roofing to block UV light and add colour.","body":"Roofing granules are small particles of crushed rock, usually coated with a fired ceramic colour layer, that are pressed into the hot asphalt surface of shingles and mineral-surfaced roll roofing. They form the visible weathering surface of the product.\n\n## Purpose\n\n- **UV protection**: asphalt degrades quickly in sunlight. Granules shade the asphalt and are the main defence against ultraviolet ageing.\n- **Colour**: the ceramic coating gives the roof its colour and blend. Lighter colours reflect more heat, which is useful in hot, sunny climates; darker colours absorb heat.\n- **Fire resistance**: the mineral layer helps the shingle resist burning brands.\n- **Special functions**: some granules are coated with copper or zinc compounds to resist algae, and \"cool roof\" granules use pigments that reflect near-infrared radiation.\n\n## Materials\n\nGranule materials include slate, schist, quartz, vitrified brick, stone and ceramic. The underside of a shingle uses a finer, non-coloured surfacing such as sand, talc or mica to stop shingles sticking together in the bundle.\n\n## Granule loss\n\nSome granule loss is normal, especially when a roof is new and loose surplus granules wash into the gutters. Ongoing or heavy loss, however, is a sign of ageing: once the asphalt is exposed, it oxidises and cracks faster. Hail can knock granules off in round patches, which is one of the signs adjusters look for after a storm. Pressure washing a shingle roof can strip granules and is generally discouraged by manufacturers.\n\n## Inspection tip\n\nGranules collecting in gutters or at downspout outlets, bare dark patches on shingles, or exposed fibreglass mat all indicate that the roof surface is wearing out.\n","key_facts":[{"label":"Typical materials","value":"Crushed rock (e.g. slate, schist, quartz) with ceramic coating"},{"label":"Main role","value":"Protect asphalt from UV; add colour"},{"label":"Special types","value":"Algae-resistant (copper/zinc), cool-roof reflective"}],"regions":["Global"],"aliases":["shingle granules","mineral granules","ceramic granules"],"related":["asphalt-shingle","algae-resistant-shingle","roll-roofing","cool-roof"],"sources":[{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Algae resistant granules","url":"https://www.malarkeyroofing.com/features/algae-resistant-granules/","publisher":"Malarkey Roofing Products"}],"category":"materials","company":null,"country":null},{"slug":"personal-fall-arrest-system","title":"Roofing Harness and Anchors (Personal Fall Arrest)","category":"tools-equipment","type":"article","summary":"A full-body harness, connector and roof anchor system that stops a roofer's fall; required in many countries for work at height.","body":"Falls are a leading cause of death and serious injury in construction, and roofers are especially exposed. A personal fall arrest system (PFAS) is designed to stop a worker who falls before they hit the ground or a lower level, and to limit the forces on the body. It is one of several fall protection options alongside guardrails, scaffolding with edge protection, and safety nets.\n\n## Components\n\n- **Anchorage**: a secure point on the structure. On pitched roofs, temporary roof anchors are commonly screwed or nailed through the sheathing into rafters or trusses; permanent anchors are installed on some buildings for future maintenance. OSHA guidance states that anchors must not be attached to sheathing alone.\n- **Full-body harness**: distributes arrest forces across the thighs, pelvis, chest and shoulders. Body belts are not permitted for fall arrest under US rules because they can cause serious injury in a fall.\n- **Connector**: a shock-absorbing lanyard, a self-retracting lifeline, or a rope grab running on a vertical lifeline. Rope-grab systems are common on residential roofs because they let the worker move along the slope.\n\n## US requirements (example)\n\nUnder OSHA's construction rules (29 CFR 1926 Subpart M), fall protection is required for residential roofing work at 6 ft (1.8 m) or more above a lower level. Anchors used for personal fall arrest must support at least 5,000 lb (about 22 kN) per attached worker, or be designed with a safety factor of at least two under the supervision of a qualified person. Employers must train workers, and written fall protection plans are permitted only where conventional protection is shown to be infeasible.\n\nOther countries apply different thresholds and hierarchies. Many European and Australian rules emphasise eliminating the risk or using collective measures such as scaffolding and edge protection before relying on personal equipment.\n\n## Good practice\n\n- Install anchors as close to the ridge as practical and before accessing the roof edge.\n- Minimise free-fall distance and check clearance below so the worker does not strike the ground.\n- Inspect harnesses and connectors before each use and remove any that have arrested a fall.\n- Plan for **rescue**, since suspension in a harness can quickly become dangerous.\n- Remove or cover temporary anchors as specified by the manufacturer when work is complete.","key_facts":[{"label":"US height trigger (residential roofing)","value":"6 ft (1.8 m)"},{"label":"US anchor strength","value":"5,000 lb (about 22 kN) per worker or safety factor of 2"},{"label":"Not permitted for fall arrest (US)","value":"Body belts"}],"regions":["Global","North America"],"aliases":["fall arrest system","roof anchor","safety harness","PFAS","fall arrest harness","roofing harness"],"related":["roof-jacks","ladder-standoff","roofing-hoist","roofing-nailer","roofing-fall-protection","warning-line-system","australian-whs-roof-work"],"company":null,"sources":[{"title":"Reducing Falls While Installing Tile Roofs","url":"https://www.osha.gov/sites/default/files/publications/reducing-falls-installing-tile-roofs-factsheet.pdf","publisher":"OSHA"},{"title":"PFAS Safety: Personal Fall Arrest Systems for Residential Construction Contractors","url":"https://www.mass.gov/doc/pfas-safety-personal-fall-arrest-systems-for-residential-construction-contractors/download","publisher":"Commonwealth of Massachusetts"},{"title":"Falls from roof: roof anchors","url":"https://designforconstructionsafety.org/wp-content/uploads/2017/10/falls_from_roof_roof-anchors_rev5.pdf","publisher":"Design for Construction Safety"},{"title":"Roof Jack Safety","url":"https://www.jlconline.com/how-to/roofing/roof-jack-safety_o/","publisher":"Journal of Light Construction"},{"title":"Canadian Roofing Reference Manual: 1.6.3 Fall Arrest Systems","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-1-safety/1-6-fall-protection/1-6-3-fall-arrest-systems/","publisher":"Canadian Roofing Contractors Association"},{"title":"Work Health and Safety (Preventing Falls in Housing Construction) Code of Practice 2015","url":"https://legislation.gov.au/F2016L00411/asmade/2016-03-30/text/original/epub/OEBPS/document_1/document_1.html","publisher":"Federal Register of Legislation (Australia)"},{"title":"1926.501 Duty to have fall protection","url":"https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.501","publisher":"U.S. Occupational Safety and Health Administration"},{"title":"Fall Protection in Residential Construction: Frequently Asked Questions","url":"https://www.osha.gov/residential-fall-protection/faq","publisher":"U.S. Occupational Safety and Health Administration"}],"country":null},{"slug":"roofing-hatchet","title":"Roofing Hatchet (Shingling Hatchet)","category":"tools-equipment","type":"term","summary":"A hammer-hatchet used for hand-nailing and trimming shingles and shakes, often with an adjustable gauge for setting exposure.","body":"A roofing hatchet, also called a shingling or shingler's hatchet, combines a hammer face with a sharp hatchet blade on a single head. It developed for wood shingle and shake roofing, where the roofer nails, splits and trims each piece by hand, and it remains in use for wood roofing, asphalt shingle repairs, hand nailing near edges and details, and general roofing tasks.\n\n## Features\n\n- **Hammer face**, often milled (waffled) or smooth, sometimes with a magnetic nail holder or starter so a nail can be set one-handed.\n- **Blade** for splitting and trimming wood shingles and shakes, and for cutting or scoring other materials.\n- **Exposure gauge**: many models carry adjustable pins or a sliding gauge on the blade. Holding the gauge against the butt of the course below sets the exposure of the next course without measuring each piece, which keeps courses straight and consistent.\n- **Replaceable blade or gauge** on some patterns.\n- **Handles** of wood, fibreglass or steel, with weights commonly in the range of a medium framing hammer.\n\n## Use\n\nWhen laying wood shingles or shakes, the roofer places each piece, checks exposure with the gauge, drives the nails and trims edges at valleys, hips and rakes with the blade. On asphalt shingles, hatchets are used for hand nailing in areas where a nailer is awkward, for removing and replacing damaged pieces, and for cutting at walls and penetrations, although utility knives with hook blades are more common for cutting asphalt products.\n\n## Related tools\n\n- **Roofing hammer**: a hammer without a blade, sometimes with a magnetic head and gauge.\n- **Slater's hammer**: a different tool, with a pick for punching holes in slate and a cutting edge for trimming it.\n- **Roofing nailer**: a pneumatic or cordless alternative for high-volume nailing.\n\n## Safety\n\nThe sharp blade means the hatchet should be carried in a holster and handled away from the body. Eye protection is advisable when striking nails.","key_facts":[{"label":"Heads","value":"Hammer face plus hatchet blade"},{"label":"Key feature","value":"Adjustable exposure gauge"},{"label":"Main uses","value":"Wood shingles and shakes, repairs, hand nailing"}],"regions":["North America","Global"],"aliases":["shingling hatchet","shingler's hatchet","roofer's hatchet"],"related":["wood-shingle","wood-shake","roofing-nailer","slaters-hammer","hook-blade-utility-knife"],"company":null,"sources":[{"title":"How to Use a Roofer's Hatchet","url":"https://www.hunker.com/12569450/how-to-use-a-roofers-hatchet","publisher":"Hunker"},{"title":"Estwing 29 Oz. Steel Shingling Hatchet with Steel Handle and Replaceable Blade/Gauge","url":"https://www.doitbest.com/product/354360/estwing-29-oz-steel-shingling-hatchet-with-steel-handle-and-replaceable-blade-gauge-354360/","publisher":"Do it Best"},{"title":"Vaughan SH Shingling Hatchet","url":"https://www.bigrocksupply.com/Vaughan-SH-Shingling-Hatchet.aspx","publisher":"Big Rock Supply"}],"country":null},{"slug":"roofing-hoist","title":"Roofing Hoists and Conveyors","category":"tools-equipment","type":"article","summary":"Powered lifts, ladder hoists, conveyors and cranes that move shingles, tiles and other roofing materials from the ground to the roof.","body":"Roofing materials are heavy and awkward: bundles of shingles, stacks of tiles, rolls of membrane, insulation boards and metal panels all need to reach the roof. Carrying them up a ladder by hand is slow and is a common cause of strains and falls. Material-handling equipment moves loads mechanically and reduces manual lifting.\n\n## Common types\n\n- **Ladder (platform) hoists**: a powered platform that runs up a dedicated ladder or rail set against the building. Petrol (gasoline) or electric motors drive a cable; product listings show load ratings of a few hundred pounds, for example 200 to 400 lb (about 90 to 180 kg), and rail lengths around 27 to 28 ft (about 8 to 8.5 m). The platform often tilts at the top so loads slide onto the roof.\n- **Conveyors**: inclined belt conveyors, often truck- or trailer-mounted, that carry bundles and tiles onto the roof continuously. Common for tile roofing and large residential jobs.\n- **Boom trucks and supplier delivery cranes**: many roofing suppliers deliver materials directly onto the roof with a truck-mounted boom or conveyor (\"rooftop delivery\").\n- **Cranes and telehandlers** on commercial jobs for insulation pallets, rooftop units and heavy materials.\n- **Hand-operated gin wheels and electric hoists** on scaffolds, widely used in Europe for lifting smaller loads.\n\n## Safe use\n\nIndustry guidance on loading roofs typically covers:\n\n- Following the manufacturer's rated load and setup instructions, including ladder angle and footing for ladder hoists.\n- Keeping people clear of the area beneath the hoist and load path.\n- Spreading loads on the roof to avoid overloading the structure, keeping materials away from edges, and securing them against sliding and wind.\n- Distributing heavy materials such as tile over the framing rather than stacking them in one place.\n- Checking for overhead power lines, a frequent hazard when hoisting or using boom equipment.\n- Using fall protection for workers at the receiving point near the roof edge.\n\n## Regulation\n\nIn many countries, lifting equipment is covered by workplace safety regulations that require inspection and competent operators, and cranes are subject to separate certification rules. Supplier rooftop delivery shifts some of this responsibility to the supplier's trained operators.","key_facts":[{"label":"Ladder hoist capacity (examples)","value":"About 200-400 lb (90-180 kg)"},{"label":"Rail length (examples)","value":"About 27-28 ft (8-8.5 m)"},{"label":"Key hazards","value":"Overloaded roofs, falling loads, power lines"}],"regions":["Global"],"aliases":["ladder hoist","shingle hoist","roofing conveyor","material hoist"],"related":["ladder-standoff","personal-fall-arrest-system","roof-jacks","sagging-roof-deck"],"company":null,"sources":[{"title":"Follow Proper Safety Standards and Procedures When Loading Materials on the Roof","url":"https://roofingmagazine.com/follow-proper-safety-standards-and-procedures-when-loading-materials-on-the-roof/","publisher":"Roofing Magazine"},{"title":"Hoisting a Roofing Safety Standard","url":"https://floridaroof.com/Hoisting-a-Roofing-Safety-Standard-1-21690.html","publisher":"Florida Roofing Magazine"},{"title":"TP250, 250lb, 28' Platform Hoist","url":"https://www.arcat.com/product/tp250-250lb-28-platform-hoist-194349","publisher":"ARCAT"},{"title":"Safety Hoist HD400H 400lb Ladder Platform Hoist 28ft","url":"https://bigrocksupply.com/store/p/9500-Safety-Hoist-HD400H-Honda-Engine-400lb-Ladder-Platform-Hoist-28ft.aspx","publisher":"Big Rock Supply"}],"country":null},{"slug":"roofing-in-afghanistan","title":"Roofing in Afghanistan","category":"world-roofing","type":"place","country":{"name":"Afghanistan","iso2":"AF"},"summary":"Afghan houses are traditionally roofed either flat, with timber beams, mats and mud, or with mud-brick domes (gunbad), as in the villages around Herat.","body":"Afghanistan is a mountainous, landlocked country of cold winters, hot, dry summers and frequent earthquakes. Its traditional houses are built of earth, with two main kinds of roof: the **flat mud roof** carried on timber beams, found across most of the country, and the **mud-brick dome**, or *gunbad*, which dominates the villages of the western plains around Herat. In Kabul, newer concrete houses now stand beside these older forms.\n\n## Climate and hazards\n\nMuch of the country is arid, and earth is the most widely used traditional building material. Winters are harsh, especially in the highlands, and earthen roofs need regular repair to survive snow and rain. Earthquakes are frequent: Afghanistan's traditional builders developed techniques such as walls of bricks laid diagonally to improve performance, and in early October 2023 a series of four strong earthquakes destroyed many earthen houses in Herat province.\n\n## Roofing history\n\nEarth construction in the region has a very long history. In the Herat area, the skills of building mud-brick domical vaults are said to go back about 2,300 years. Elsewhere, the flat timber-and-mud roof is the usual traditional house roof. In Kabul, newer concrete houses contrast with traditional timber-framed buildings such as those of the Murad Khani quarter of the old city, whose traditional building methods are documented by the Turquoise Mountain organisation.\n\n## Traditional and vernacular roofs\n\n**Flat timber-and-mud roof.** Timber beams span the walls and form the base of the roof. On these, builders lay woven willow branches (in Kabul often brought from Zabul) or bamboo (from Jalalabad and Mazar-e Sharif), then a layer of mud (*ghoragel*). On a single-storey building the top is finished with mud plaster; otherwise the walls of the next storey rise from it. Carved timber panels may be fixed under the beams as a ceiling, catching dust that falls through from the roof. Because of the harsh climate, these roofs need maintenance twice a year, before and after winter.\n\n**Gunbad (mud-brick dome).** Around Herat, rural houses are roofed with domical vaults (*gunbad*) or jack arches of sun-dried mud brick, finished with mud plaster (*kah-gel*). The domes use special adobe blocks thinner than ordinary bricks and are built using at least six recognised techniques, the most common being *chahar swarak*. Thick \"load walls\" carried up to about one-third of the dome's height resist its outward thrust. An opening at the top of the dome, also called *badgir*, ventilates and cools the room. Walls are of cob (*pakhsa*) or adobe (*khasht-e-kham*), sometimes with stone.\n\nAfter the 2023 earthquakes, many Herat families again chose domes for new building because the materials and skills are cheap and widely available. A UNDP-supported retrofit tested on a damaged house involved tying the walls together with wire-mesh bands, filling cracks with gypsum or clay-gypsum mortar, fixing wire mesh to both faces of the dome, linked by 4 mm (0.16 in) galvanised wires through the joints, and rebuilding the load wall and plaster.\n\n## Roofing today\n\nDomes remain the usual roof of rural houses around Herat, and concrete construction has spread in Kabul.\n\n## Notable roofs\n\n- **Herat domed villages**: clustered mud-brick gunbad houses around shared courtyards.\n- **Murad Khani, Kabul**: old-city quarter of traditional timber-framed buildings.\n\n## Local roofing terms\n\n- *gunbad* (Dari): dome or domical vault\n- *ghoragel*: mud applied to a flat roof\n- *kah-gel*: mud plaster\n- *pakhsa*: cob wall\n- *khasht-e-kham*: adobe (sun-dried brick)\n- *badgir*: ventilation opening at the top of a dome\n- *senj*: brick infill set diagonally within a timber frame\n- *chahar swarak*: the commonest dome-building technique around Herat\n\n## Sources and gaps\n\nNational housing statistics and information on building regulation, modern roofing materials and domestic roofing manufacturers in Afghanistan: published information is limited.","key_facts":[{"label":"Traditional flat roof","value":"Timber beams, willow or bamboo layer, mud (ghoragel)"},{"label":"Traditional dome","value":"Mud-brick domical vault (gunbad), Herat region"},{"label":"Maintenance","value":"Mud roofs renewed twice a year, before and after winter"},{"label":"Climate driver","value":"Cold winters, hot dry summers, earthquakes"},{"label":"Recent disaster","value":"Herat earthquakes, October 2023"}],"regions":["South Asia","Middle East"],"aliases":["Afghan roofing","roofs of Afghanistan","gunbad"],"related":["mud-roof","flat-roof","dome","nubian-vault","badgir","middle-eastern-domes","earthquake-roofing","roofing-in-iran","roofing-in-pakistan","roofing-in-tajikistan","roofing-in-turkmenistan","roofing-in-uzbekistan","pamiri-house"],"company":null,"sources":[{"title":"Traditional Afghan Architecture","url":"https://artsandculture.google.com/story/traditional-afghan-architecture-turquoise-mountain/fAXBUyulvJH3Kw?hl=en","publisher":"Turquoise Mountain / Google Arts & Culture"},{"title":"Domes of Identity: When Earthquake Challenges Herat's Earthen Traditions","url":"https://architecture.live/retrofitting-homes-herat-people-in-centre-undp/","publisher":"Architecture Live"}]},{"slug":"roofing-in-albania","title":"Roofing in Albania","category":"world-roofing","type":"place","country":{"name":"Albania","iso2":"AL"},"regions":["Europe"],"company":null,"summary":"How Albania roofs its buildings: the stone-slab roofs of Gjirokastër, tiered houses of Berat, kulla towers of the north, and post-communist concrete.","aliases":["Albanian roofing","Çatitë në Shqipëri"],"body":"Albania's most famous roofs are the grey stone roofs of Gjirokastër, the \"City of Stone\", whose Ottoman-era houses are covered with flat dressed stones. Together with Berat, a town of tiered houses on steep slopes, it forms a UNESCO World Heritage site. In the north, fortified stone tower houses (*kulla*) are characteristic.\n\n## Climate and hazards\n\nThe coast is Mediterranean and the interior mountainous, with harsh winters. Albania is highly seismic. On 26 November 2019 a magnitude 6.4 earthquake struck north-western Albania, killing 51 people; in early 2020 the government reported more than 11,000 buildings destroyed and 83,000 damaged. Much of the damage was blamed on building-code violations and substandard construction dating from the early post-communist period. In Berat, houses rebuilt after an 1851 earthquake kept stone lower floors with timber upper floors.\n\n## Roofing history\n\nBerat's castle has origins in the 4th century BC, though it is mostly 13th century, as are many of the Byzantine churches in its citadel. Fortified towers in Gjirokastër date to the 13th century, before Ottoman rule; the Ottoman period in Berat began in 1417. Most of Gjirokastër's existing buildings date from the 17th and 18th centuries, and Berat's vernacular houses mainly from the late 18th and 19th centuries. The first northern kullas were built in the 17th century in the Dukagjini region.\n\n## Traditional and vernacular roofs\n\n- **Gjirokastër house:** a tall stone block of up to five storeys, thought to derive from the fortified country houses of southern Albania. The lower storey holds a cistern and stable, the upper storeys a guest room and family rooms. Roofs are covered with flat dressed stones; a similar roofing style is found in the Pelion district of Greece. UNESCO notes that many Gjirokastër houses date from the 17th century, with more elaborate examples from the early 19th century, often with richly painted interiors.\n- **Berat house:** tiered houses climbing the slopes, designed to use daylight.\n- **Kulla:** stone towers of three or four storeys with small windows and loopholes, mainly in the north, with southern examples in Berat, Gjirokastër, Himarë and Këlcyrë. In Theth, \"locked towers\" (*kulla ngujimi*) served as refuges during blood feuds.\n\n## Roofing today\n\nMany Gjirokastër houses are being reconstructed, but others are decaying from lack of investment, abandonment or inappropriate renovation, partly because local craftsmen are often excluded from projects.\n\n## Codes, standards and regulation\n\nAfter the 2019 earthquake Albania drafted a law imposing prison terms of 7-15 years on investors, supervisors and architects who violate construction rules.\n\n## Notable roofs\n\n- **Gjirokastër** (UNESCO since 2005, nominated 1988): more than 500 houses protected as cultural monuments; the 1757 mosque dominates the bazaar.\n- **Berat**, added to the same UNESCO property as an extension.\n- **Lake Ohrid** shore, added to the Ohrid UNESCO property in 2019.\n\n## Local roofing terms\n\n- *kullë* / *kulla* - tower house\n- *kulla ngujimi* - \"locked tower\"\n- *frëngji* - narrow wall openings\n\n## Sources and gaps\n\nData on modern roofing materials, current building codes, information on domestic roofing manufacturers, and the source and laying methods of the stone used on Gjirokastër roofs were not found in published sources.","key_facts":[{"label":"Signature roof","value":"Flat dressed stone roofs, Gjirokastër"},{"label":"Heritage","value":"Historic Centres of Berat and Gjirokastra (UNESCO)"},{"label":"Seismic hazard","value":"High (2019, Mw 6.4)"},{"label":"Vernacular towers","value":"Kulla, from the 17th century in the north"}],"related":["gjirokaster-stone-roofs","kulla-tower-house","stone-slate","roofing-in-greece","roofing-in-kosovo","roofing-in-montenegro","roofing-in-north-macedonia"],"sources":[{"title":"Historic Centres of Berat and Gjirokastra","url":"https://whc.unesco.org/en/list/569","publisher":"UNESCO World Heritage Centre"},{"title":"Gjirokastër","url":"https://en.wikipedia.org/wiki/Gjirokast%C3%ABr","publisher":"Wikipedia"},{"title":"Tower houses in the Balkans","url":"https://en.wikipedia.org/wiki/Tower_houses_in_the_Balkans","publisher":"Wikipedia"},{"title":"2019 Albania earthquake","url":"https://en.wikipedia.org/wiki/2019_Albania_earthquake","publisher":"Wikipedia"},{"title":"Natural and Cultural Heritage of the Ohrid region","url":"https://whc.unesco.org/en/list/99","publisher":"UNESCO World Heritage Centre"}]},{"slug":"roofing-in-algeria","title":"Roofing in Algeria","category":"world-roofing","type":"place","country":{"name":"Algeria","iso2":"DZ"},"summary":"Algeria's best-documented roofing heritage is that of the Saharan ksour, above all the five fortified towns of the M'zab Valley, a World Heritage site.","body":"Algeria is Africa's largest country, stretching from a Mediterranean coast and the Atlas ranges to the deep Sahara. Its best-documented traditional roofs are those of the Saharan ksour (fortified villages), above all the five towns of the M'zab Valley, whose tightly packed houses around a central mosque are a celebrated example of desert urbanism.\n\n## Climate and hazards\n\nThe north has a Mediterranean climate with winter rain; most of the country is hot desert, where heat and sand are the main roof loads. Northern Algeria is seismically active, which matters for heavy masonry and concrete roofs.\n\n## Roofing history\n\nThe M'zab Valley was settled by the Ibadites in the 10th century. Its five ksour, El Atteuf (the oldest), Bounoura, Melika, Ghardaïa and Beni Isguen, were founded between 1012 and 1350; Berriane and El Guerrara were added later, making seven settlements. Houses were built to a standard size and type, arranged in concentric rings around the mosque, an arrangement intended to support egalitarian community life while protecting family privacy. UNESCO notes that the valley has kept much of its way of life and its building techniques since the 11th century, using local materials.\n\n## Traditional and vernacular roofs\n\n- **M'zab houses**: houses of local materials, of standard size and type, closely packed in rings around the mosque.\n- **Saharan ksour**: across the Algerian Sahara, ksour of earth and stone with flat roofs on timber or palm joists are the traditional form (see Roofing in North Africa).\n- **Domes and vaults**: masonry domes appear on religious and funerary buildings (see Middle Eastern domes).\n\n## Roofing today\n\nReinforced concrete flat roofs dominate new construction across North Africa (see Roofing in North Africa).\n\n## Notable roofs\n\n- **M'zab Valley**: five fortified towns, inscribed on the World Heritage List in 1982.\n\n## Local roofing terms\n\n- **ksar** (plural *ksour*): fortified village.\n\n## Sources and gaps\n\nSpecific seismic code details: published information is limited. No household survey or census table on roof materials for Algeria was found in published sources. No national roofing code was found. No information on domestic roofing manufacturers was found in published sources.\n\nDetailed descriptions of M'zab roof construction (materials, layers, rooftop use), the earth architecture of the Gourara and Touat oases, Kabyle tiled roofs in the north, colonial-era building, and modern roof materials were not found in published sources.","key_facts":[{"label":"Landmark","value":"M'zab Valley (World Heritage, 1982)"},{"label":"M'zab towns founded","value":"1012-1350"},{"label":"Traditional settlement","value":"Ksour (fortified villages)"},{"label":"Climate driver","value":"Desert heat; seismic north"}],"regions":["Africa","Middle East"],"aliases":["Algerian roofing","roofing in Algeria"],"related":["roofing-in-north-africa","flat-roof","mud-roof","middle-eastern-domes","roofing-in-morocco","roofing-in-tunisia","roofing-in-libya","roofing-in-mauritania"],"company":null,"sources":[{"title":"M'Zab Valley","url":"https://whc.unesco.org/en/list/188/","publisher":"UNESCO World Heritage Centre"},{"title":"M'zab","url":"https://en.wikipedia.org/wiki/M%27zab","publisher":"Wikipedia"}]},{"slug":"roofing-in-andorra","title":"Roofing in Andorra","category":"world-roofing","type":"place","country":{"name":"Andorra","iso2":"AD"},"summary":"Andorran roofing: natural stone-slate roofs on Pyrenean rural buildings and bordes, now required by government construction criteria.","body":"Andorra is a small, mountainous principality in the eastern Pyrenees between France and Spain. Its traditional rural buildings, including the mountain barns called *bordes*, are roofed with natural stone slate (*llosa*), which the government now makes compulsory on rural buildings.\n\n## Climate and hazards\n\nAndorra's high valleys have cold, snowy winters, and roofs must carry snow and shed meltwater.\n\n## Roofing history\n\nAndorra has many churches from the Romanesque period, many dating from the 12th century, and the Romanesque style lasted longer there than elsewhere in Europe because of the country's isolation in the Pyrenees. Sant Joan de Caselles at Canillo, built in the 11th-12th centuries with a Lombard-style square bell tower, has a wooden roof structure; its apse roof was affected by restoration work in 1934-1935. Santa Coloma, near Andorra la Vella, is often described as the oldest church in the country. Secular buildings survive from the 15th and 16th centuries, including the Casa de la Vall, the former parliament house, built in the late 16th century. The sanctuary of Meritxell was partly destroyed by fire in 1972.\n\n## Traditional and vernacular roofs\n\n- **Stone-slate roofs** of natural *llosa* on rural houses and farm buildings.\n- **Bordes**, traditional mountain buildings used to store grain and house livestock; some have been converted into restaurants.\n- **Vaulted stone huts** in the high pastures. In the Madriu-Perafita-Claror valley, a UNESCO-listed cultural landscape covering 4,247 ha (about 10,500 acres), a little over 9% of the country, small shepherds' huts have vaulted stone roofs, alongside ruined summer dwellings, stables and cheese dairies.\n\n## Roofing today\n\nContemporary architectural styles have been used in more recent buildings. On rural land, however, regulation keeps the traditional roofscape: natural slate remains the required covering.\n\n## Codes, standards and regulation\n\nConstruction criteria issued by the Govern d'Andorra for rural buildings (an annex to a regulation, dated 2013) set strict roof rules. Buildings rehabilitated under criteria of the cultural heritage ministry are excluded. The rules include:\n\n- natural stone slate (*llosa natural*) is mandatory as the external roof covering, with traditional vegetation accepted only as an exception;\n- new buildings must have a roof with two slopes, while rehabilitations may keep their existing form;\n- shiny, exposed metals are prohibited on roofs, and gutters must be of brass, zinc or copper and integrated into the facade;\n- chimneys and flues must be clad in the same stone as the facades, and grouping them is recommended;\n- roof windows may not project above the roof plane, and technical equipment must stay within the roof volume;\n- new buildings must collect rainwater.\n\n## Notable roofs\n\n- **Sant Joan de Caselles**, Canillo (11th-12th century).\n- **Santa Coloma**, often described as the oldest church in Andorra.\n- **Casa de la Vall**, Andorra la Vella (late 16th century).\n- **Madriu-Perafita-Claror valley**, with vaulted stone huts.\n\n## Local roofing terms\n\n- *Llosa*: stone slate (Catalan).\n- *Borda*: mountain barn or farm building.\n- *Coberta*: roof.\n\n## Sources and gaps\n\nRoof-load guidance, statistics on roof materials, details of traditional slating technique, the source of slate used today and information on domestic roofing manufacturers for Andorra were not found in published sources.","key_facts":[{"label":"Traditional material","value":"Natural stone slate (llosa)"},{"label":"Rural roof rule","value":"Natural slate mandatory; two-slope roofs for new buildings (2013 criteria)"},{"label":"Gutters (rural)","value":"Brass, zinc or copper"},{"label":"UNESCO landscape","value":"Madriu-Perafita-Claror valley, 4,247 ha"}],"regions":["Europe"],"aliases":["Andorran roofing"],"related":["natural-slate","stone-slate","roofing-in-spain","roofing-in-france","lauze"],"company":null,"sources":[{"title":"Annex 1: Criteris constructius","url":"https://govern.ad/documents/d/guest/rural_annex1_criterisconstructius","publisher":"Govern d'Andorra"},{"title":"Madriu-Perafita-Claror Valley","url":"https://whc.unesco.org/en/list/1160","publisher":"UNESCO World Heritage Centre"},{"title":"Architecture of Andorra","url":"https://en.wikipedia.org/wiki/Architecture_of_Andorra","publisher":"Wikipedia"},{"title":"Sant Joan de Caselles","url":"https://en.wikipedia.org/wiki/Sant_Joan_de_Caselles","publisher":"Wikipedia"},{"title":"The traditional bordes","url":"https://visitandorra.com/it/attivita/the-traditional-bordes","publisher":"Visit Andorra"}]},{"slug":"roofing-in-angola","title":"Roofing in Angola","category":"world-roofing","type":"place","country":{"name":"Angola","iso2":"AO"},"summary":"Angolan homes are roofed with zinc sheet, fibre cement, tile, concrete slab or grass thatch; Mbanza Kongo preserves Kongo and Portuguese building.","body":"Angola stretches from the humid north and Atlantic coast to the dry south-west bordering Namibia. Its roofs combine African traditions of thatch with Portuguese-introduced stone building, and the national census now records zinc sheet, fibre cement, tile, concrete slab and grass as the main roof materials.\n\n## Climate and hazards\n\nClimates range from tropical in the north to arid in the south-west.\n\n## Roofing history\n\nMbanza Kongo, in the north, was the political and spiritual capital of the Kingdom of Kongo, active from the 14th to the 19th century. Its pre-existing town was built with local materials; after the Portuguese arrived in the 15th century they added stone buildings constructed by European methods, including churches, convents, a Jesuit college and military and civil buildings. The cathedral, later known as Kulumbimbi, is dated to 1491 and was raised to a cathedral in 1596; by the 1620s the city had about twelve churches. The city was sacked in civil wars after the battle of Mbwila in 1665, abandoned in 1678, and restored as capital by Pedro IV in 1705-1709. Its remains were inscribed on the World Heritage List in 2017.\n\n## Traditional and vernacular roofs\n\n- **Himba homesteads** in the far south (across the Kunene River from Namibia): houses of mopane wood plastered with red clay and cow manure, arranged around a sacred fire and livestock kraal.\n- **Grass thatch** (*capim*) on rural houses, recorded as a census category.\n\n## Roofing today\n\nThe 2014 General Population and Housing Census asked whether a dwelling's roof was mainly of concrete slab (*placa de betao*), tile (*telha*), fibre cement (*lusalite/fibrocimento*), zinc (*zinco*), grass (*capim*) or other. Angola's 2016 national report for Habitat III notes the growth of peripheral *musseques* around Luanda.\n\n## Codes, standards and regulation\n\nLand use and urban planning are governed by the Territorial and Urban Planning Law (Lei 3/04) and the Land Law (Lei 9/04); Lei 3/07 on housing promotion formally recognises directed self-build (*autoconstrucao dirigida*). At Mbanza Kongo, a provincial decree of August 2013 regulates building permits in the protected area.\n\n## Notable roofs\n\n- **Mbanza Kongo** (UNESCO 2017): ruins of Kulumbimbi cathedral and the royal precinct.\n\n## Local roofing terms\n\n- *zinco* (Portuguese): zinc-coated roof sheet.\n- *capim*: grass thatch.\n- *telha*: roof tile.\n- *lusalite*: fibre-cement sheet (from a brand name).\n- *placa de betao*: concrete slab roof.\n\n## Sources and gaps\n\nSpecific roof hazards: published information is limited. No national roofing standard was identified. No information on domestic roofing manufacturers was found in published sources.\n\nCensus roof shares, colonial tile-making and Portuguese-era roof forms in Luanda and Benguela, and Ovimbundu or Kongo thatching techniques: published information is limited.","key_facts":[{"label":"Census roof categories","value":"Concrete slab, tile, fibre cement, zinc, grass (2014)"},{"label":"Traditional materials","value":"Grass thatch, timber, earth, clay and dung plaster"},{"label":"Landmark","value":"Mbanza Kongo (UNESCO 2017)"}],"regions":["Africa"],"aliases":["Angolan roofing"],"related":["corrugated-iron","corrugated-fibre-cement-sheet","clay-roof-tile","thatch","flat-roof","roofing-in-namibia","roofing-in-zambia","roofing-in-the-democratic-republic-of-the-congo","roofing-in-the-republic-of-the-congo","roofing-in-southern-africa"],"company":null,"sources":[{"title":"Mbanza Kongo, Vestiges of the Capital of the former Kingdom of Kongo","url":"https://whc.unesco.org/en/list/1511/","publisher":"UNESCO World Heritage Centre"},{"title":"M'banza-Kongo","url":"https://en.wikipedia.org/wiki/M%27banza-Kongo","publisher":"Wikipedia"},{"title":"Angola Censo 2014: O tecto da habitacao e principalmente de... (ROOF)","url":"https://catalog.ihsn.org/catalog/7038/variable/F1/V113?name=ROOF","publisher":"IHSN Survey Catalog / INE Angola"},{"title":"Relatorio Nacional de Angola para Habitat III (2016)","url":"https://dw.angonet.org/wp-content/uploads/relatorio_nacional_de_angola_para_habitat_iii_final_-_marco_2016_1_0.pdf","publisher":"Government of Angola (via Angonet)"},{"title":"Himba people","url":"https://en.wikipedia.org/wiki/Himba_people","publisher":"Wikipedia"}]},{"slug":"roofing-in-antigua-and-barbuda","title":"Roofing in Antigua and Barbuda","category":"world-roofing","type":"place","country":{"name":"Antigua and Barbuda","iso2":"AG"},"summary":"Antiguan and Barbudan roofing: timber and concrete houses with metal-sheet roofs under a mandatory OECS-based code; Hurricane Irma stripped Barbuda's roofs in 2017.","body":"Antigua and Barbuda are low limestone islands in the Leeward Islands, directly exposed to Atlantic hurricanes. The country was among the first in the Eastern Caribbean to make an OECS-based building code mandatory.\n\n## Climate and hazards\n\nHurricane Irma struck Barbuda on 6 September 2017 as a Category 5 storm. A preliminary survey found over 40% of buildings in Codrington, the main town, severely damaged and only about 5% untouched. Roofs in general collapsed or were torn away, and corrugated iron roofing was bent and ripped off; most concrete buildings kept their walls, while timber structures collapsed. The whole island, up to about 2,000 people, was evacuated.\n\n## Roofing history\n\nThroughout the Eastern Caribbean, older timber houses typically have steep hip or gable roofs clad first in wooden shingles and later in corrugated iron. Hip roofs, sloping on all four sides, are self-bracing and lack tall gable ends that catch the wind, and slopes of about 35 degrees or more are often preferred in hurricane regions because shallower roofs are more prone to uplift.\n\n## Roofing today\n\nThe Irma experience showed the contrast between concrete-walled houses and lightweight timber houses with sheet roofs.\n\n## Codes, standards and regulation\n\nThe Organisation of Eastern Caribbean States (OECS) developed model building codes and guidelines for small buildings with support from UNCHS and UNDP, based on the Caribbean Uniform Building Code (CUBiC). The USAID-funded, OAS-executed Caribbean Disaster Mitigation Project helped Antigua and Barbuda, Dominica, Grenada and Saint Lucia prepare national codes from these models, and published construction diagrams covering hip and gable roof framing, rafter-to-ring-beam and wall-plate connections and hurricane straps for houses under 3,000 ft² (279 m²). A revised OECS Building Code was issued in June 2015, reviewed that year for Grenada, Saint Vincent and the Grenadines, Saint Lucia and Montserrat, and drew on the codes of Jamaica and the Cayman Islands. National consultations on administering it were held across the sub-region in 2017 under the EU-funded iLand Resilience project. Antigua and Barbuda's national code was submitted to government in summer 1995 and made mandatory for all buildings through regulations under the Development Control Ordinance.\n\n## Sources and gaps\n\nPublished accounts of island-specific historic roofing: published information is limited.\n\nRoofing history, material statistics and current code edition: published information is limited.","key_facts":[{"label":"Building code","value":"OECS-based, mandatory under the Development Control Ordinance (1995)"},{"label":"Recent hazard","value":"Hurricane Irma, Cat 5, 6 Sept 2017 (Barbuda)"}],"regions":["Latin America","North America"],"aliases":["Antigua roofing","Barbuda roofing"],"related":["roofing-in-the-caribbean","hip-roof","corrugated-iron","hurricane-roof-damage","hurricane-tie","chattel-house","roofing-in-saint-kitts-and-nevis","roofing-in-dominica"],"company":null,"sources":[{"title":"Barbuda begins difficult road to recovery after Hurricane Irma","url":"https://www.thenewhumanitarian.org/news/2017/09/18/barbuda-begins-difficult-road-recovery-after-hurricane-irma","publisher":"The New Humanitarian"},{"title":"Building codes in the Caribbean (CDMP bulletin)","url":"https://oas.org/cdmp/bulletin/codes.htm","publisher":"Organization of American States, Caribbean Disaster Mitigation Project"},{"title":"OECS Building Guidelines: construction diagrams","url":"https://oas.org/pgdm/document/codedraw/intro.htm","publisher":"Organization of American States"},{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"}]},{"slug":"roofing-in-argentina","title":"Roofing in Argentina","category":"world-roofing","type":"place","country":{"name":"Argentina","iso2":"AR"},"summary":"Argentine roofing: Andean grass thatch, Jesuit mission clay tile, the corrugated-iron houses of La Boca, and hand-split shingles in Patagonia.","body":"Argentina runs from the subtropical north-east and the Andean north-west to the cold, windy south of Patagonia and Tierra del Fuego. Its roofs include grass thatch in the Andes, clay tile in the Jesuit missions and colonial towns, the corrugated sheet metal (*chapa*) that became the signature of the Buenos Aires port district of La Boca, and hand-split timber shingles in Patagonia. For an overview of the Southern Cone, see Roofing in Argentina and Chile.\n\n## Climate and hazards\n\n- **Earthquakes** in the Andean west, addressed by the national seismic code.\n- **Strong winds** in Patagonia and on the pampas.\n- **Snow** in the Andes and the far south, and **heavy rain** in the north-east.\n\n## Roofing history\n\n**Andean.** In the north-west, Andean houses were roofed with grass thatch. The bunchgrass *ichu* (*Jarava ichu*, Peruvian feathergrass) grows in Argentina as in the rest of the Andes.\n\n**Jesuit missions.** In Misiones province, the Jesuit missions among the Guaraní made fired clay tiles in their own workshops from the 17th century, replacing earlier straw roofs, partly as protection against fire. Tiles from San Ignacio Miní measure about 46 to 55 cm (18 to 22 in) long, 19 to 22 cm (7.5 to 8.7 in) wide and about 1 cm (0.4 in) thick. A 2016 study of the church of Santa Ana found 67 fragments of decorated tiles with a crescent-moon border, which covered much of the church roof. When the explorer Juan Bautista Ambrosetti visited Santa Ana in 1894 its roofs had collapsed. The Jesuit Missions of the Guaranis in Argentina and Brazil were inscribed by UNESCO in 1983.\n\n**La Boca and the immigrant city.** By 1880 La Boca, at the mouth of the Riachuelo in Buenos Aires, was a busy port district dominated by Genoese immigrants. The architect Fernanda Cragnolini describes houses said to have been built from shipyard leftovers and painted in strong colours, mainly red and green. Timber-framed houses were clad in smooth or corrugated sheet metal with zinc flashings, under low-pitched roofs with zinc gutters and downpipes running down the façade. Many were multi-family tenements (*conventillos*), often three storeys high, with rooms opening onto galleries. Houses stood on hardwood piles bolted to tie beams about a metre (3 ft) or more above ground. Fire was a constant risk.\n\n**Patagonia.** In the south, hand-split wooden shingles (*tejuelas*) were used to clad roofs and walls, a tradition shared with Chile and found in Argentine border areas of Río Negro, Chubut, Santa Cruz and Tierra del Fuego.\n\n## Traditional and vernacular roofs\n\n- **Ichu thatch** in the Andean north-west (see Andean ichu thatch).\n- **Teja** roofs of the missions and colonial towns (see Jesuit mission roof tiles).\n- **Casa de chapa**: timber-framed house clad and roofed in corrugated metal, as in La Boca.\n- **Tejuela** shingle cladding in Patagonia.\n\n## Roofing today\n\nMetal sheet (*chapa*), concrete slabs with waterproof membranes, and clay or concrete tile are all common.\n\n## Codes, standards and regulation\n\nA 2012 comparative review listed CIRSOC 103 (2005) as Argentina's seismic design regulation.\n\n## Notable roofs\n\n- **Jesuit Missions of the Guaranis** (UNESCO 1983), including San Ignacio Miní and Santa Ana.\n- **La Boca**, Buenos Aires: brightly painted corrugated-metal houses and conventillos.\n\n## Local roofing terms\n\n- *Chapa* (or *chapa acanalada*): corrugated metal sheet.\n- *Teja*: clay tile.\n- *Tejuela*: hand-split wooden shingle.\n- *Conventillo*: multi-family tenement.\n- *Paja brava*: ichu grass.","key_facts":[{"label":"Traditional materials","value":"Ichu thatch, clay tile, corrugated metal, wooden shingles"},{"label":"Mission tile size","value":"46-55 cm long (San Ignacio Miní)"},{"label":"Iconic district","value":"La Boca, Buenos Aires (chapa houses)"},{"label":"Seismic code (2012 review)","value":"CIRSOC 103 (2005)"},{"label":"Heritage","value":"Jesuit Missions of the Guaranis, UNESCO 1983"}],"regions":["Latin America"],"aliases":["Argentine roofing","techos en Argentina"],"related":["roofing-in-argentina-and-chile","corrugated-iron","jesuit-mission-roof-tiles","tejuela","andean-ichu-thatch","clay-roof-tile","roofing-in-chile","roofing-in-uruguay","roofing-in-paraguay","roofing-in-bolivia","roofing-in-brazil"],"company":null,"sources":[{"title":"La República de la Boca","url":"https://www.pagina12.com.ar/2001/suple/M2/01-02/01-02-03/nota2.htm","publisher":"Página/12 (M2)"},{"title":"Arqueología en las Misiones Jesuitas de Guaraníes: las tejas decoradas de la iglesia de Santa Ana","url":"https://cau.iaa.fadu.uba.ar/wp-content/uploads/2019/03/Roca_Tejas-decoradas_SantaAna.pdf","publisher":"Instituto de Arte Americano, FADU-UBA"},{"title":"Tejuela artesanal (Conserva 20, 2015)","url":"https://www.cncr.gob.cl/sites/www.cncr.gob.cl/files/2023-01/Tejuela%20Artesanal.pdf","publisher":"Centro Nacional de Conservación y Restauración (Chile)"},{"title":"Jarava ichu","url":"https://en.wikipedia.org/wiki/Jarava_ichu","publisher":"Wikipedia"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-argentina-and-chile","title":"Roofing in Argentina and Chile","type":"place","summary":"Overview of Southern Cone roofing: Andean grass thatch, colonial clay tile, Chiloé's wooden shingles, metal sheet in the south, all with seismic design in Chile.","body":"Argentina and Chile stretch from the Andean altiplano and Atacama desert to the cold, wet forests of Patagonia and Tierra del Fuego. Roofing changes with that range: grass thatch in the high Andes, clay tile in the Mediterranean-climate centre, timber shingles in the rainy south and sheet metal across much of the region today.\n\n## Andean traditions\n\nIn Inca-influenced building of the Andes, roofs were usually made of grass or reeds laid on wooden or cane poles and tied with ropes. The coarse bunchgrass of the altiplano, known as *ichu* (Quechua for \"straw\"), grows in both Peru and Bolivia and neighbouring Andean areas. Communal grass-rope work survives in traditions such as the annual rebuilding of the Q'eswachaka rope bridge in Peru, recognised by the Peruvian government as cultural heritage in 2009.\n\n## Central valleys\n\nIn central Chile and the Argentine interior, colonial houses were built mainly of earth and straw, typically adobe walls with timber roofs covered in curved clay tiles in the Spanish tradition. Many of these buildings suffered badly in earthquakes.\n\n## Chiloé and the rainy south\n\nThe Chiloé archipelago in southern Chile is known for its wooden churches, built under a Jesuit mission tradition that began in 1608 and continued by Franciscans in the 18th and 19th centuries. Their builders drew on boat-building techniques, and the churches are clad in large numbers of wooden shingles that cope with the humid, rainy ocean climate. Sixteen of them are inscribed by UNESCO as the Churches of Chiloé. In March 2002 a storm brought down the tower of the church at Chonchi, and a national conservation programme has run since 2003.\n\n## Sheet metal and modern roofs\n\nCorrugated and profiled metal sheet is widespread on houses, farm buildings and industrial buildings in both countries, and is especially characteristic of southern towns and port cities. Modern urban buildings use reinforced concrete with membranes, while suburban houses use clay or concrete tiles, metal sheet and asphalt shingles.\n\n## Seismic design\n\nChile is one of the most seismically active countries in the world, and its building rules are among the most demanding: buildings are expected not to collapse even in a very large earthquake. Lightweight roof systems and well-anchored structures are favoured.","key_facts":[{"label":"Andean roofs","value":"Grass (ichu) and reed thatch"},{"label":"Colonial roofs","value":"Curved clay tile on adobe"},{"label":"Chiloé churches","value":"Wooden, shingle-clad; 16 UNESCO-listed"},{"label":"Key hazard","value":"Earthquakes (Chile)"}],"regions":["Latin America"],"aliases":["Chilean roofing","Argentine roofing","Southern Cone roofing"],"related":["andean-ichu-thatch","wood-shingle","roofing-in-brazil","spanish-mediterranean-terracotta-roof"],"sources":[{"title":"Architecture of Chile","url":"https://en.wikipedia.org/wiki/Architecture_of_Chile","publisher":"Wikipedia"},{"title":"Churches of Chiloé","url":"https://whc.unesco.org/en/list/971","publisher":"UNESCO World Heritage Centre"},{"title":"Jarava ichu","url":"https://en.wikipedia.org/wiki/Jarava_ichu","publisher":"Wikipedia"},{"title":"Q'eswachaka","url":"https://en.wikipedia.org/wiki/Q%27eswachaka","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-armenia","title":"Roofing in Armenia","category":"world-roofing","type":"place","country":{"name":"Armenia","iso2":"AM"},"regions":["Europe","Middle East"],"company":null,"summary":"Armenian roofing: stone churches with conical tuff domes and tuff-shingle roofs, and corbelled timber glkhatun roofs in old houses.","aliases":["Armenian roofing","Roofs of Armenia","glkhatun","hazarashen"],"body":"Armenia is known above all for its stone churches, roofed in stone from vault to covering, and for the corbelled timber lantern roofs (*glkhatun* or *hazarashen*) of its traditional houses. Both answer the same conditions: a mountainous, earthquake-prone country with plentiful volcanic stone.\n\n## Climate and hazards\n\nArmenia is a high, mountainous, continental country with cold winters. The region is earthquake-prone, and Armenian buildings tend to be low-slung and thick-walled in response.\n\n## Roofing history\n\n**Urartu.** Urartian temples of the first millennium BC had massive stone lower walls, small square interiors and upper storeys of mud brick that have not survived, so their roofs are unknown.\n\n**Hellenistic.** The Temple of Garni, of the 1st century AD, is in a fully Hellenistic style.\n\n**Early Christian.** After Armenia's conversion to Christianity in 301, the first churches were built between the 4th and 7th centuries, mostly as simple basilicas. By the 5th century the central cupola cone was widely used, and by the 7th century centrally planned churches had appeared; Zvartnots Cathedral dates from the 7th century.\n\n**Medieval.** Medieval churches typically carry a conical or semi-conical, radially segmented dome on an (often octagonal) drum above stone vaults. The pointed dome form is often said to echo Mount Ararat. Roofs meet at the base of the drum in both basilicas and centrally planned churches.\n\n## Traditional and vernacular roofs\n\n- **Stone church roofs:** almost entirely of volcanic tuff or basalt, with stone vaulted ceilings and an outer roof of finely cut tuff \"shingles\".\n- **Glkhatun / hazarashen:** the Armenian name for the corbelled timber lantern roof also found in Georgia (*darbazi*), Turkey and Azerbaijan, in which stepped courses of logs rise to a central light and smoke opening. See darbazi.\n\n## Notable roofs\n\n- **Etchmiadzin Cathedral:** the mother church, dated in its current form from 483/4 with work into 1868.\n- **Zvartnots Cathedral** (7th century): early centrally planned church, now ruined.\n- **Garni Temple** (1st century AD): Hellenistic temple.\n- Medieval monasteries with conical tuff domes.\n\n## Local roofing terms\n\n- *glkhatun* / *hazarashen* - corbelled timber lantern roof of traditional houses\n\n## Sources and gaps\n\nDetailed climate data for roofing, data on current roofing materials in Armenian housing and information on modern roofing, codes and industry: published information is limited.","key_facts":[{"label":"Church roofs","value":"Conical tuff domes on drums; tuff shingles"},{"label":"House roof","value":"Glkhatun / hazarashen corbelled log roof"},{"label":"Main materials","value":"Volcanic tuff and basalt"},{"label":"Seismic response","value":"Low, thick-walled buildings"}],"related":["darbazi","roofing-in-georgia","roofing-in-azerbaijan","roofing-in-turkey","roofing-in-iran","dome","stone-slate","earthquake-roofing"],"sources":[{"title":"Armenian architecture","url":"https://en.wikipedia.org/wiki/Armenian_architecture","publisher":"Wikipedia"},{"title":"Darbazi","url":"https://en.wikipedia.org/wiki/Darbazi","publisher":"Wikipedia"}]},{"slug":"roofing-in-australia","title":"Roofing in Australia","category":"world-roofing","type":"place","country":{"name":"Australia","iso2":"AU"},"summary":"Australian roofing: Aboriginal bark and stone-walled shelters, colonial bark and shingles, then corrugated iron, tiles and coated steel under the NCC.","body":"Australia's roofs today are dominated by two families of material: sheet steel, descended from the corrugated iron that arrived in the colonial period, and tiles of terracotta or concrete. Behind them lies a much longer history of Aboriginal shelters roofed with bark, branches, grass and, in parts of south-west Victoria, earth or reeds over stone walls. The country's climates range from tropical cyclone regions in the north to temperate southern cities, and heat, bushfire and hail are recurring hazards for any roof.\n\n## Climate and hazards\n\nNorthern coasts lie in the tropical cyclone belt, so roofs there need tested fixings and continuous tie-down from sheeting to foundations. Across much of the south and east, bushfire is the defining hazard: the February 2009 Victorian bushfires destroyed more than 2,000 houses, and construction in bushfire-prone areas must now follow AS 3959 according to the site's [Bushfire Attack Level](/bushfire-attack-level). The 2019-20 Black Summer fires also burned through heritage landscapes such as Budj Bim. Hail is a major cause of insurance claims in eastern cities, and strong summer heat drives interest in light-coloured and well-ventilated roofs.\n\n## Roofing history\n\n**Aboriginal shelters.** Shelters known by many names, including humpy, gunyah, wurley, mia-mia and wiltija, were built from bark, branches, leaves and grass, often as lean-tos braced against a tree. Researcher Paul Memmott has found that many Aboriginal huts were dome structures, and designs varied with climate and family size; in the rainforest near Cairns, domed villages were occupied for up to a year through the wet season. On the Dampier Archipelago in Western Australia, circular stone house foundations have been dated to about 9,000 years ago.\n\n**Budj Bim.** In Gunditjmara country in south-west Victoria, Europeans recorded beehive-shaped domed houses with basalt walls in 1840, often in groups of 20 to 30. Remnants of at least 146 stone houses are known at Budj Bim. Accounts differ on the roofing: one source describes reed roofs, another domes of earth or sod over walls more than 1 m (3 ft) high. The surrounding eel aquaculture system, dated to at least 6,500 years, was inscribed on the UNESCO World Heritage List in 2019. See [Budj Bim stone houses](/budj-bim-stone-houses).\n\n**Early colonial roofs (from 1788).** Settlers learned from Aboriginal people which trees gave good roofing bark and how to keep it flat by soaking it in salt water or smoking it. Stringybark and box sheets were laid over sapling rafters and tied with kurrajong-bark cord, and bark roofs usually had no gutters because their edges were ragged. Thatch of cumbungi rushes or blady grass was used where available, and straw once crops were grown. For more permanent houses, shingles were split with a froe, most commonly from box, from stringybark in Victoria, and from she-oak (*Casuarina*) and other species elsewhere. British-sized slates and imported felts were used on better buildings.\n\n**Iron and tiles.** Corrugated galvanised iron became common from the 1840s, was often laid straight over old shingles, and remains part of the national identity; galvanised iron gutters became common in the 1850s. Marseille-pattern terracotta tiles were imported by 1886, and large-scale local production by the Wunderlich company began in 1916. Terracotta and concrete tiles became the standard roof of 20th-century suburban brick-veneer houses. Asbestos-cement sheet (\"fibro\") was used extensively, with James Hardie dominating production until the mid-1980s; it is now banned, and some states prohibit pressure-washing old fibro roofs. The first coil of prepainted [Colorbond steel](/colorbond-steel) came off the line at Port Kembla in 1966.\n\n## Traditional and vernacular roofs\n\n- **Bark and slab huts** of the colonial frontier (about 1790-1920), roofed with bark, thatch or shingles and later with iron.\n- **The [Queenslander](/queenslander)**, a timber house on stumps with verandahs and a steep corrugated iron roof, developed from the 1840s.\n- **Aboriginal domed and lean-to shelters** (see [gunyah](/gunyah)), whose forms and names varied across hundreds of language groups.\n\n## Roofing today\n\nCoated steel sheet and terracotta or concrete tile remain the main coverings. Australians still say \"corrugated iron\" although the sheet is steel, now usually with a zinc-aluminium coating sold under names such as Zincalume. Green and cool roofs have been promoted since 2008 in Melbourne, where early examples include Freshwater Place (2002) and Council House 2 (2006).\n\n## Codes, standards and regulation\n\nThe [National Construction Code](/national-construction-code-australia), published by the Australian Building Codes Board, sets nationwide requirements and calls up Australian Standards such as AS/NZS 1170.2 (wind actions), AS 1562.1 (sheet roof and wall cladding), AS 2050 (installation of roof tiles) and AS 3959 (bushfire-prone areas). Licensing of roofers and roof plumbers is handled by each state and territory. Falls are controlled under harmonised work health and safety laws (see [Australian WHS roof work](/australian-whs-roof-work)).\n\n## Industry\n\nBlueScope makes Colorbond and Zincalume steel, with its paint line at Port Kembla, New South Wales. Wunderlich was the pioneer of local tile manufacture. Master Builders Australia, a federation of eight state and territory associations, represents builders and many roofing contractors.\n\n## Notable roofs\n\n- **Sydney Opera House** (opened 1973; World Heritage 2007): Jørn Utzon's shells are built from 2,194 precast concrete sections and clad with 1,056,006 glossy-white and matte-cream tiles, 120 mm (4.7 in) square, made by Höganäs of Sweden and fixed in prefabricated panels.\n- **Budj Bim Cultural Landscape** (World Heritage 2019), with its stone house remains.\n\n## Local roofing terms\n\n- **Corro / custom orb**: classic corrugated profile.\n- **Fibro**: asbestos-cement (now fibre-cement) sheet.\n- **Humpy, gunyah, wurley, mia-mia, wiltija**: Aboriginal shelter names from different languages.\n\n## Sources and gaps\n\nReliable national statistics on roof-material shares were not found; the ABS census does not appear to publish them.","key_facts":[{"label":"Dominant materials today","value":"Coated steel sheet; terracotta and concrete tile"},{"label":"Traditional materials","value":"Bark, branches, grass; stone walls with reed or earth domes (Budj Bim)"},{"label":"Colonial roofs","value":"Bark sheets, thatch, split shingles; corrugated iron from the 1840s"},{"label":"Local tile production","value":"Wunderlich, from 1916"},{"label":"Climate drivers","value":"Cyclones, bushfire, hail, heat"},{"label":"Building code","value":"National Construction Code (ABCB)"}],"regions":["Oceania"],"aliases":["Australian roofing","Roofing in Aboriginal Australia"],"related":["queenslander","corrugated-iron","spread-of-corrugated-iron","colorbond-steel","bushfire-attack-level","national-construction-code-australia","gunyah","budj-bim-stone-houses","clay-roof-tile","concrete-roof-tile","wood-shingle","asbestos-cement-roofing","australian-whs-roof-work","master-builders-australia","roofing-in-new-zealand","roofing-in-papua-new-guinea","wildfire-roofing","hail-damage"],"company":null,"sources":[{"title":"Humpy","url":"https://en.wikipedia.org/wiki/Humpy","publisher":"Wikipedia"},{"title":"Aboriginal houses","url":"https://www.creativespirits.info/aboriginalculture/land/aboriginal-houses","publisher":"Creative Spirits"},{"title":"Revealed by fire","url":"https://inside.australiangeographic.com.au/articles/revealed-by-fire","publisher":"Australian Geographic"},{"title":"Miles Lewis Heritage Building Collection: Roofing","url":"https://acahuch.msd.unimelb.edu.au/miles-lewis-heritage-building-collection/roofing2","publisher":"University of Melbourne (ACAHUCH)"},{"title":"Slab hut","url":"https://en.wikipedia.org/wiki/Slab_hut","publisher":"Wikipedia"},{"title":"Corrugated galvanised iron","url":"https://en.wikipedia.org/wiki/Corrugated_galvanised_iron","publisher":"Wikipedia"},{"title":"Queenslander (architecture)","url":"https://en.wikipedia.org/wiki/Queenslander_(architecture)","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Asbestos cement","url":"https://en.wikipedia.org/wiki/Asbestos_cement","publisher":"Wikipedia"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"},{"title":"History of COLORBOND steel","url":"https://steel.com.au/resources/articles/history-colorbond-steel","publisher":"BlueScope"},{"title":"Sydney Opera House","url":"https://en.wikipedia.org/wiki/Sydney_Opera_House","publisher":"Wikipedia"},{"title":"National Construction Code","url":"https://ncc.abcb.gov.au/","publisher":"Australian Building Codes Board"},{"title":"2009 Victorian bushfires","url":"https://en.wikipedia.org/wiki/2009_Victorian_bushfires","publisher":"Wikipedia"},{"title":"About us","url":"https://www.masterbuilders.com.au/about-us/","publisher":"Master Builders Australia"}]},{"slug":"roofing-in-austria","title":"Roofing in Austria","category":"world-roofing","type":"place","country":{"name":"Austria","iso2":"AT"},"summary":"Austrian roofing: clay and concrete tiles, Alpine wooden shingles and sheet metal for heavy snow, regulated by nine state building codes and ÖNORM B 3419.","body":"Austria is a largely Alpine country, and much of its roofing is shaped by snow, wind and mountain building traditions. Clay tiles, including the flat beaver-tail, and concrete tiles cover most houses in the valleys and lowlands of the east; split wooden shingles remain part of the mountain landscape; and the sheet-metal trade of the *Spengler* has long been closely linked to roofing. Austria is also home to two of Europe's best-known roof tile businesses, Wienerberger and Bramac.\n\n## Climate and hazards\n\nAlpine regions receive heavy snow, and steep roofs, strong roof structures and secure fixing are needed against snow load and storms, while the eastern lowlands around Vienna and in Burgenland have a drier, more continental climate. The Austrian roofing standard ÖNORM B 3419 sets permitted roof pitches for each covering material and includes wind-load fastening calculations, reflecting how strongly climate drives detailing.\n\n## Roofing history\n\nThe flat clay beaver-tail tile (*Biberschwanz*), which probably originated in the 14th century around Nuremberg, spread across southern Germany and the countries to its south and east, replacing earlier curved monk-and-nun tiles. It is laid in the overlapping double or crown patterns typical of southern Germany and Austria. In mountain areas, split wooden shingles (*Schindeln*) of spruce and larch roofed farmhouses, huts and chapels, and shingle facades and roofs are still typical of villages such as Lech in Vorarlberg.\n\nVienna's brick and tile industry began on an industrial scale in 1819, when Alois Miesbach started making bricks from clay deposits in the Wienerberg district south of the city; the firm became Wienerberger and has been listed on the Vienna Stock Exchange since 1869. In 1966 Rudolf Braas and the Austrian firm Hofman & Maculan founded Bramac at Pöchlarn in Lower Austria to make concrete roof tiles, the name combining \"Bra\" and \"Mac\".\n\nThe most famous Austrian roof, that of St Stephen's Cathedral in Vienna, was destroyed by fire in April 1945 and rebuilt after the war on a steel structure, under a pattern of some 230,000 glazed tiles.\n\n## Traditional and vernacular roofs\n\n- **Beaver-tail tiles**, often in double or crown lay, on town houses and farmhouses.\n- **Wooden shingles**, split rather than sawn, on Alpine houses, chapels and huts, and as wall cladding.\n- **Sheet metal**, worked by the Spengler, including copper, which is widespread on Central European roofs and weathers green to dark brown.\n- **Glazed tiles** in decorative patterns on major churches, of which St Stephen's is the outstanding example.\n\n## Roofing today\n\nClay and concrete tiles from manufacturers such as Wienerberger and Bramac are widely used on Austrian houses, and wooden shingles remain in use on heritage and mountain buildings. Flat roofs on commercial and apartment buildings use bituminous and synthetic membranes.\n\n## Codes, standards and regulation\n\nBuilding law in Austria is a matter for the nine federal states (*Bundesländer*), so there are nine different building codes. Since 2008, technical building rules have been progressively harmonised through the **OIB guidelines** (*OIB-Richtlinien*) 1 to 6 of the Austrian Institute of Construction Engineering, covering topics such as fire protection, safety in use and energy saving. The states have declared them binding in their building technology regulations, while allowing departures where an equivalent level of protection is shown; a seventh guideline on sustainable building is in development.\n\nFor roof coverings, **ÖNORM B 3419**, *Design and construction of roofings and wall coverings* (edition of 1 April 2018, current as of 2026), sets permitted pitches for each material, suitable substrates and wind-load fastening, with a simplified wind method for single- and double-shell roofs. It excludes metal roofing and non-ventilated coverings, and contract rules are in ÖNORM B 2219.\n\nRoofers (*Dachdecker*) train through a three-year apprenticeship. A double apprenticeship (*Doppellehre*) combining roofing with the Spengler trade takes four years.\n\n## Industry\n\nWienerberger, headquartered in Vienna, describes itself as the world's largest brick producer and is a major European roof tile maker; it bought the Austrian clay tile maker Tondach Gleinstätten in 2014. Bramac, headquartered in Pöchlarn, has a second plant at Gaspoltshofen in Upper Austria (1973) and expanded into Central and Eastern Europe from 1984; by 2010 it had about 900 employees and had produced more than 3.83 billion tiles. Wienerberger held half of Bramac from 1969 until 2011, when Monier, now part of BMI Group, became sole owner.\n\n## Notable roofs\n\n- **St Stephen's Cathedral, Vienna**: a roof 111 m (364 ft) long rising 38 m (125 ft) above the floor, covered with about 230,000 glazed tiles showing the double-headed eagle and the arms of Vienna and Austria.\n- **Lech**, Vorarlberg, known for its shingled facades and roofs.\n\n## Local roofing terms\n\n- *Dachdecker*: roofer.\n- *Spengler*: sheet-metal worker.\n- *Schindel*: wooden shingle.\n- *Biberschwanz*: beaver-tail tile.\n\n## Sources and gaps\n\nNational data on roof materials and on Austrian vernacular roof types by region: published information is limited.","key_facts":[{"label":"Common materials today","value":"Clay and concrete tiles"},{"label":"Traditional materials","value":"Beaver-tail tile, wooden shingles, sheet metal"},{"label":"Climate driver","value":"Alpine snow and wind"},{"label":"Building codes","value":"Nine state codes, harmonised by OIB-Richtlinien 1-6"},{"label":"Roofing standard","value":"ÖNORM B 3419 (2018)"},{"label":"Landmark roof","value":"St Stephen's Cathedral, about 230,000 glazed tiles"}],"regions":["Europe"],"aliases":["Austrian roofing","Dachdeckung in Österreich"],"related":["beaver-tail-tile","schindel","glazed-roof-tile","st-stephens-cathedral-roof","onorm-b-3419","wienerberger","bmi-group","concrete-roof-tile","roofing-in-germany","roofing-in-switzerland","roofing-in-liechtenstein"],"company":null,"sources":[{"title":"Baurecht und Bauordnungen","url":"https://www.oesterreich.gv.at/de/themen/bauen_und_wohnen/bauen/Seite.2260200","publisher":"oesterreich.gv.at"},{"title":"ÖNORM B 3419:2018-04-01","url":"https://www.austrian-standards.at/en/shop/onorm-b-3419-2018-04-01~p2371153","publisher":"Austrian Standards International"},{"title":"St. Stephen's Cathedral, Vienna","url":"https://en.wikipedia.org/wiki/St._Stephen%27s_Cathedral,_Vienna","publisher":"Wikipedia"},{"title":"Bramac","url":"https://de.wikipedia.org/wiki/Bramac","publisher":"Wikipedia (German)"},{"title":"Wienerberger","url":"https://en.wikipedia.org/wiki/Wienerberger","publisher":"Wikipedia"},{"title":"Dachdecker","url":"https://de.wikipedia.org/wiki/Dachdecker","publisher":"Wikipedia (German)"},{"title":"Biberschwanzziegel","url":"https://de.wikipedia.org/wiki/Biberschwanzziegel","publisher":"Wikipedia (German)"},{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Creaton","url":"https://de.wikipedia.org/wiki/Creaton","publisher":"Wikipedia (German)"}]},{"slug":"roofing-in-azerbaijan","title":"Roofing in Azerbaijan","category":"world-roofing","type":"place","country":{"name":"Azerbaijan","iso2":"AZ"},"regions":["Europe","Middle East"],"company":null,"summary":"Azerbaijani roofing: windy Absheron flat roofs with asphalt coverings, corbelled karadam lantern roofs, and modern concrete.","aliases":["Azerbaijani roofing","Roofs of Azerbaijan","karadam"],"body":"Azerbaijan, on the western shore of the Caspian Sea, shares the South Caucasus tradition of corbelled timber lantern roofs (called *karadam* here) and has a distinctive flat-roofed house type on the Absheron peninsula around Baku.\n\n## Climate and hazards\n\nThe Absheron peninsula has a dry subtropical climate with hot, dry summers and frequent strong winds. Absheron also has rich deposits of limestone, the traditional building stone. Wind is a direct roofing concern: on the flat roofs of Absheron summer houses, coverings had to resist being lifted by gusts.\n\n## Roofing history\n\n**Corbelled roofs.** The corbelled timber roof with a central light and smoke opening, known as the *darbazi* in Georgia and *glkhatun* in Armenia, is called *karadam* in Azerbaijan. See darbazi.\n\n**Absheron bağ evləri.** After Azerbaijan joined the Soviet Union in 1922, land on the Absheron peninsula was leased for summer garden houses (*bağ evləri*). These were small white houses with verandas and flat roofs, and the roofs were covered with asphalt so the wind could not tear them away.\n\n**Modern.** Baku's low-rise housing is the subject of recent research arguing that current design often ignores the climate and terrain that shaped traditional Absheron building.\n\n## Traditional and vernacular roofs\n\n- **Karadam:** corbelled log lantern roof.\n- **Flat Absheron roofs:** on limestone houses, with asphalt-type coverings against wind.\n\n## Notable roofs\n\nThe Walled City of Baku with the Shirvanshah's Palace and Maiden Tower, and the Historic Centre of Sheki with the Khan's Palace, are UNESCO World Heritage sites.\n\n## Local roofing terms\n\n- *karadam* - corbelled timber lantern roof\n- *bağ evi* (plural *bağ evləri*) - Absheron garden house\n\n## Sources and gaps\n\nData on current roofing materials, national building codes for roofs, information on domestic roofing manufacturers and descriptions of roof construction at the Baku and Sheki World Heritage sites were not found in published sources. Traditional use of local natural bitumen (*kir*) on Absheron roofs is mentioned in general accounts, but detailed descriptions: published information is limited.","key_facts":[{"label":"Climate driver","value":"Dry summers and strong winds (Absheron)"},{"label":"Traditional stone","value":"Limestone"},{"label":"Absheron house roof","value":"Flat, asphalt-covered against wind"},{"label":"Corbelled roof name","value":"Karadam"}],"related":["darbazi","roofing-in-georgia","roofing-in-armenia","roofing-in-iran","roofing-in-russia","flat-roof","wind-uplift"],"sources":[{"title":"Absheron's Bağ Evi: Looking for a Lost Cottage","url":"https://www.balcanicaucaso.org/en/cp_article/absherons-bag-evi-looking-for-a-lost-cottage/","publisher":"OBC Transeuropa / Chai Khana"},{"title":"Influence of Climatic Factors of Absheron Peninsula on Architectural and Planning Features of Low-Rise Development of Baku (Aliyev, 2020)","url":"https://marhi.ru/eng/AMIT/2020/2kvart20/15_aliyev/index.php","publisher":"Architecture and Modern Information Technologies (MARHI)"},{"title":"Darbazi","url":"https://en.wikipedia.org/wiki/Darbazi","publisher":"Wikipedia"}]},{"slug":"roofing-in-bahrain","title":"Roofing in Bahrain","category":"world-roofing","type":"place","country":{"name":"Bahrain","iso2":"BH"},"regions":["Middle East"],"company":null,"summary":"Bahraini roofing: timber-and-plaster merchant houses of the Muharraq pearling towns with flat roofs on imported poles, and modern concrete.","aliases":["Bahraini roofing","Roofs of Bahrain"],"body":"Bahrain's historic architecture is closely tied to pearling, the island economy that lasted from at least the 2nd century AD to the 1930s. The merchant houses, shops and storehouses of Muharraq that served the trade are now protected as a UNESCO World Heritage site.\n\n## Climate and hazards\n\nBahrain shares the hot, humid Gulf coastal climate.\n\n## Roofing history\n\n**Pearling era.** Pearling peaked at the end of the 19th and start of the 20th centuries and collapsed in the 1930s, when Japanese cultured pearls arrived. The pearling buildings of Muharraq are noted by UNESCO for timber and plaster built to a high standard of craftsmanship using local materials and techniques.\n\n**Regional practice.** Traditional Gulf houses of the period were roofed with imported mangrove poles carrying mats and an earth covering (see chandal-roof), a method documented in neighbouring Qatar and Kuwait.\n\n**Modern.** Reinforced concrete is standard in new building, as across the Gulf.\n\n## Traditional and vernacular roofs\n\n- **Flat roofs on imported poles:** see chandal-roof.\n- **Palm-frond houses:** see barasti.\n\n## Codes, standards and regulation\n\nUNESCO cites Decree Law No. 11 of 1995 as the legal basis for protecting Bahrain's pearling sites, which were designated national monuments on 10 January 2010.\n\n## Notable roofs\n\n- **Pearling, Testimony of an Island Economy** (UNESCO): 17 buildings in Muharraq (merchants' houses, shops, storehouses and a mosque), three offshore oyster beds, part of the seashore and Qal'at Bu Mahir fort.\n\n## Sources and gaps\n\nDetailed climate data for roofing, Bahrain-specific descriptions of roof construction, data on current roofing materials, information on modern materials, codes and industry, and Bahrain-specific roofing terms were not found in published sources; see chandal-roof for Gulf terms.","key_facts":[{"label":"Heritage buildings","value":"Pearling-era houses of Muharraq"},{"label":"Main traditional materials","value":"Timber and plaster (UNESCO)"},{"label":"Pearling collapse","value":"1930s"},{"label":"Modern","value":"Flat reinforced concrete"}],"related":["chandal-roof","barasti","flat-roof","roofing-in-qatar","roofing-in-saudi-arabia","roofing-in-kuwait","roofing-in-the-middle-east-and-gulf"],"sources":[{"title":"Pearling, Testimony of an Island Economy","url":"https://whc.unesco.org/en/list/1364","publisher":"UNESCO World Heritage Centre"},{"title":"Architecture of Qatar","url":"https://en.wikipedia.org/wiki/Architecture_of_Qatar","publisher":"Wikipedia"},{"title":"Architecture of Kuwait","url":"https://en.wikipedia.org/wiki/Architecture_of_Kuwait","publisher":"Wikipedia"}]},{"slug":"roofing-in-bangladesh","title":"Roofing in Bangladesh","category":"world-roofing","type":"place","country":{"name":"Bangladesh","iso2":"BD"},"summary":"About three-quarters of Bangladeshi homes have corrugated tin (CI sheet) roofs; the curved thatched hut roof of the delta inspired the bangla roof.","body":"Bangladesh occupies most of the delta of the Ganges, Brahmaputra and Meghna rivers, one of the wettest and most flood-prone inhabited regions on earth. For centuries its houses were roofed with thatch on bamboo frames, bent into a curve that later gave the world the *bangla* roof. Today the country is a land of corrugated metal: about three-quarters of households live under tin (corrugated iron, or \"CI sheet\") roofs.\n\n## Climate and hazards\n\nThe country is low-lying, hot and humid, with heavy monsoon rain. River and flash floods are frequent, and the coastal belt along the Bay of Bengal is exposed to tropical cyclones and storm surges. A roof here must shed intense rain, resist wind uplift during cyclones and be light enough for houses built on mud plinths or bamboo frames. Bangladesh also lies close to active seismic zones; the 1897 earthquake, for instance, destroyed the towers of the Kantanagar temple in Dinajpur.\n\n## Roofing history\n\nThe alluvial soil of the delta provides clay but almost no building stone. Traditional dwellings were of earth, bamboo and timber, roofed with straw, reed, grass or palm leaf. Their curved ridges and drooping eaves helped rain run off quickly.\n\nIn the medieval period, mosques were built of burnt brick. The Historic Mosque City of Bagerhat, founded in the 15th century by the general Ulugh Khan Jahan and inscribed by UNESCO as a World Heritage Site, includes the Shait Gumbad Mosque, one of the largest mosques of its kind, built of baked brick.\n\nFrom about the 16th century, builders in Bengal translated the curved thatched hut roof into brick and terracotta for temples and mosques. These forms, the *do-chala*, *char-chala* and *at-chala*, are known together as Bengal or bangla roofs, and they were taken up by Mughal and Rajput builders across northern India. Temples in the *ratna* style added towers above a curved-cornice roof.\n\nIn the colonial and modern periods, corrugated galvanised iron sheet replaced thatch on most rural houses, while flat reinforced concrete slabs became standard in cities.\n\n## Traditional and vernacular roofs\n\n- **Chala roofs**: thatched hut roofs with two (*do-chala*) or four (*char-chala*) curved slopes on a bamboo frame, the model for the masonry bangla roof.\n- **Jhupri**: the simplest shelters, with walls and roofs of straw, bamboo, palm leaves or polythene, still used by 0.57% of households in 2023.\n- **Kutcha houses**: earth, bamboo and mat houses, now usually roofed with tin.\n- **Terracotta temples**: brick temples with curved chala roofs or ratna towers, decorated with carved terracotta panels.\n\n## Roofing today\n\nThe Bangladesh Bureau of Statistics' *Socio-Economic and Demographic Survey 2023* found that about **74% of households have tin (CI sheet) roofs** and about **25% have cement (concrete) roofs**. More than half of households (55.85%) live in kutcha, or non-brick, houses made largely of earth, bamboo and mats, rising to about 70% of rural houses and more than 77% in Mymensingh division; in Dhaka division the share was about 38%. Cement or concrete walls were reported for 49.84% of houses.\n\nCorrugated sheet roofs are cheap and light but conduct heat readily into the rooms below.\n\n## Codes, standards and regulation\n\nThe **Bangladesh National Building Code (BNBC)** was first prepared in 1993, without legal force, and gained a legal basis through a gazette in 2006. The revised **BNBC 2020** was published in the official gazette on 11 February 2021. It provides for a **Bangladesh Building Regulatory Authority** of five members to implement the code and act against violations, though about two years after the gazette the authority had still not been formed.\n\n## Notable roofs\n\n- **Shait Gumbad Mosque, Bagerhat** (15th century): large multi-domed brick mosque in a UNESCO World Heritage city.\n- **Kantanagar Temple, Dinajpur** (1704-1752): nine-towered (*navaratna*) terracotta temple whose towers fell in 1897.\n- **Gunjanth Siva Temple, Jessore** (1740): an *at-chala* temple with two tiers of curved roofs.\n- **Gobinda Temple, Puthia** (first half of the 19th century): a five-towered (*pancharatna*) temple.\n\n## Local roofing terms\n\n- *chala* (Bengali): roof slope\n- *do-chala*: two-sloped curved roof; *jor-bangla*, a pair of joined do-chala roofs\n- *char-chala*: four-sloped curved roof\n- *at-chala*: eight-sloped, two-tier curved roof\n- *ratna*: tower or pinnacle on a temple roof\n- *jhupri*: makeshift hut of straw, bamboo, palm leaf or polythene\n- *kutcha*: non-permanent house of earth, bamboo or mat\n\n## Sources and gaps\n\nThe roof figures are as reported in the press from the BBS survey. Data on roofing manufacturers and on cyclone-resistant roof standards: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Tin (CI sheet), about 74% of households (SEDS 2023)"},{"label":"Cement roofs","value":"About 25% of households (SEDS 2023)"},{"label":"Kutcha (non-brick) houses","value":"55.85% of households (SEDS 2023)"},{"label":"Traditional materials","value":"Thatch, bamboo, reed, burnt brick, terracotta"},{"label":"Climate driver","value":"Monsoon rain, floods, tropical cyclones"},{"label":"Building code","value":"Bangladesh National Building Code 2020 (gazetted 2021)"}],"regions":["South Asia"],"aliases":["Bangladeshi roofing","roofs of Bangladesh"],"related":["bangla-roof","corrugated-iron","thatch","bamboo-roofing","palm-thatch","flat-roof","terracotta","roofing-in-india","roofing-in-myanmar","hurricane-roof-damage"],"company":null,"sources":[{"title":"More than 50% of country's households are non-brick: Survey","url":"https://www.tbsnews.net/node/881461","publisher":"The Business Standard (citing BBS SEDS 2023)"},{"title":"Updated National Building Code comes into effect","url":"https://www.tbsnews.net/node/207469","publisher":"The Business Standard"},{"title":"Temple Architecture","url":"https://en.banglapedia.org/index.php/Temple_Architecture","publisher":"Banglapedia, Asiatic Society of Bangladesh"},{"title":"Bengal roofs","url":"https://en.wikipedia.org/wiki/Bengal_roofs","publisher":"Wikipedia"},{"title":"Historic Mosque City of Bagerhat","url":"https://whc.unesco.org/en/list/321/","publisher":"UNESCO World Heritage Centre"},{"title":"Revised Building Code: No dedicated body yet to enforce","url":"https://www.thedailystar.net/news/bangladesh/news/revised-building-code-no-dedicated-body-yet-enforce-3253936","publisher":"The Daily Star"}]},{"slug":"roofing-in-barbados","title":"Roofing in Barbados","category":"world-roofing","type":"place","country":{"name":"Barbados","iso2":"BB"},"summary":"Barbadian roofing: the movable timber chattel house with its steep hip or gable roof, corrugated iron and concrete, under a 1993 national building code.","body":"Barbados is a coral-limestone island at the eastern edge of the Caribbean. Its best-known roof belongs to the chattel house, a small movable timber house that has become a national symbol, while most modern houses are concrete block.\n\n## Climate and hazards\n\nBarbados lies at the southern edge of the main Atlantic hurricane track and is struck less often than islands further north, but tropical storms and strong trade winds still shape building practice, along with heavy tropical rain and salt air.\n\n## Roofing history\n\nAfter emancipation, the Located Labourers Act of 1840 allowed formerly enslaved people to build on marginal plantation land for rent, but landowners could evict them at short notice. Houses therefore had to be movable: timber chattel houses were set on loose coral-stone blocks so they could be taken apart and carried to a new site, first by ox cart and later by truck. Their roofs evolved from hipped roofs and steep double-pitched gables toward flatter, low-slope roofs, and corrugated iron became a common covering. Families extended houses by adding units behind the first, each with its own roof, giving rows of parallel roof ridges (see chattel-house).\n\n## Traditional and vernacular roofs\n\n- **Chattel house**: two-room timber house with a steep hip or gable roof, often of corrugated iron, on coral-stone blocks.\n- **Extended chattel house**: successive units under parallel roofs.\n\nThroughout the Eastern Caribbean, older timber houses typically have steep hip or gable roofs clad first in wooden shingles and later in corrugated iron. Hip roofs, sloping on all four sides, are self-bracing and lack tall gable ends that catch the wind, and slopes of about 35 degrees or more are often preferred in hurricane regions because shallower roofs are more prone to uplift.\n\n## Roofing today\n\nConcrete-block houses have become the norm and chattel houses have declined, although restored examples are used as homes and shops.\n\n## Codes, standards and regulation\n\nBarbados published a National Building Code in 1993, but it was not mandated by law. In 1998 the government began updating it and set up a Building Code Advisory Committee, and the Caribbean Disaster Mitigation Project advised on a legal and administrative basis for a national Building Authority.\n\n## Notable roofs\n\nRestored chattel houses, used as shops and homes, are the island's most characteristic roofs.\n\n## Local roofing terms\n\n- *Chattel house*: movable timber house, legally personal property rather than real estate.\n\n## Sources and gaps\n\nRoof material statistics and the current legal status of the building code: published information is limited.","key_facts":[{"label":"Vernacular roof","value":"Steep hip or gable chattel-house roof"},{"label":"Building code","value":"National Building Code (1993), not mandated by law at the time"},{"label":"Common covering (historic)","value":"Corrugated iron"}],"regions":["Latin America","North America"],"aliases":["Barbadian roofing","Bajan roofing"],"related":["roofing-in-the-caribbean","hip-roof","corrugated-iron","hurricane-roof-damage","hurricane-tie","chattel-house","roofing-in-trinidad-and-tobago","roofing-in-saint-lucia"],"company":null,"sources":[{"title":"Chattel house","url":"https://en.wikipedia.org/wiki/Chattel_house","publisher":"Wikipedia"},{"title":"Architecture of Barbados","url":"https://en.wikipedia.org/wiki/Architecture_of_Barbados","publisher":"Wikipedia"},{"title":"Building codes in the Caribbean (CDMP bulletin)","url":"https://oas.org/cdmp/bulletin/codes.htm","publisher":"Organization of American States, Caribbean Disaster Mitigation Project"},{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"}]},{"slug":"roofing-in-belarus","title":"Roofing in Belarus","category":"world-roofing","type":"place","country":{"name":"Belarus","iso2":"BY"},"summary":"Belarusian roofing: thatched gable roofs on log village houses, preserved at the Strochitsy open-air museum, Mir Castle's towers, and Soviet-era asbestos-cement sheet.","body":"Belarus is a largely flat, forested country whose traditional village house was a log building with a thatched, two-pitched roof.\n\n## Climate and hazards\n\nBelarus has a moderately continental climate with cold, snowy winters and warm summers. Snow load and moisture are the main concerns for roofs; fire was the historic danger in thatched villages.\n\n## Roofing history\n\nIn the late 19th and early 20th centuries, the typical Belarusian peasant house was a log building of two parts, a heated living room and an unheated entrance porch, under a two-pitched thatched roof. Floors were of earth or clay, and a large stove heated the house. Entire houses and farmsteads of this kind, together with churches, a school, a windmill and other buildings brought from different regions, are preserved at the Belarusian State Museum of Folk Architecture and Rural Life near Strochytsa, outside Minsk.\n\nThe Mir Castle Complex, begun at the end of the 15th century in the Gothic style and later extended in Renaissance and Baroque styles, is one of the country's best-known historic buildings. It suffered severe damage in the Napoleonic period and was restored at the end of the 19th century.\n\nIn the Soviet period, corrugated asbestos-cement sheet (*shifer*) became a common rural roof across the Soviet republics, whose chrysotile-cement industry was among the most developed in the world. See shifer.\n\n## Traditional and vernacular roofs\n\n- **Log house with thatched gable roof**, with a cold porch and a heated living room.\n\n## Notable roofs\n\n- **Mir Castle Complex** (UNESCO World Heritage Site).\n- **Belarusian State Museum of Folk Architecture and Rural Life**, Strochytsa.\n\n## Sources and gaps\n\nInformation on Belarusian roofing practice, statistics, codes and domestic roofing manufacturers: published information is limited.","key_facts":[{"label":"Traditional roof","value":"Two-pitched thatched roof on log house"},{"label":"Open-air museum","value":"Strochytsa, near Minsk"},{"label":"UNESCO site","value":"Mir Castle Complex"}],"regions":["Europe"],"aliases":["Belarusian roofing","roofs in Belarus"],"related":["thatch","shifer","roofing-in-russia","roofing-in-ukraine","roofing-in-poland","roofing-in-lithuania","asbestos-cement-roofing"],"company":null,"sources":[{"title":"Belarusians. Late 19th – early 20th century","url":"https://ethnomuseum.ru/en/expositions/exhibitions/belarusians","publisher":"Russian Museum of Ethnography"},{"title":"Strochytsa","url":"https://en.wikipedia.org/wiki/Strochytsa","publisher":"Wikipedia"},{"title":"Mir Castle Complex","url":"https://whc.unesco.org/en/list/625","publisher":"UNESCO World Heritage Centre"},{"title":"Construction with Slate – Quick Solution to the Country's Housing Problems","url":"https://vestnik-pp.samgtu.ru/0585-430X/article/view/635982","publisher":"Stroitel'nye Materialy (journal)"}]},{"slug":"roofing-in-belgium","title":"Roofing in Belgium","category":"world-roofing","type":"place","country":{"name":"Belgium","iso2":"BE"},"summary":"Belgian roofing: ceramic tiles in the lowlands, Ardennes slate in the south, reed thatch in Flanders, and a historic role in zinc and fibre-cement.","body":"Belgium is a small, densely built country with a mild, wet and windy North Sea climate. Ceramic roof tiles dominate the lowland north and centre, natural slate is the traditional roof of the Ardennes in the south-east, and reed thatch survives on farmhouses in Flanders and the Kempen. Belgium also played an outsized role in two roofing industries: rolled zinc, through the Vieille-Montagne company near Liège, and fibre cement, through the group that owns the Eternit name.\n\n## Climate and hazards\n\nFrequent rain and strong westerly winds make wind uplift and driving rain the main loads on pitched roofs, while in the higher Ardennes snow and frost add to the demands on slate and its fixings. In low-lying Flanders, stormwater from flat roofs is a growing planning concern, as in the neighbouring Netherlands.\n\n## Roofing history\n\nThe schists and phyllites of the Belgian Ardennes have been worked since prehistory, but Roman and Gallo-Roman slate was used mostly for flooring and tombs rather than roofs. Documentary evidence for roofing slate starts in the Middle Ages: in 1156 the abbey of Saint-Trond (Sint-Truiden) was reportedly roofed with slates from Fumay on the French Meuse; the monks of Orval were confirmed as owners of a slate quarry at Herbeumont in 1269; and slate working at Vielsalm is documented from 1481.\n\nArdennes slate production grew through the 19th century. In 1840, 480 workers in the province of Luxembourg produced about 17 million slates; by 1876 the province produced about 41 million slates with 1,108 workers, and in 1877 it had 51 open-air and 116 underground workings. Production then declined. Vielsalm's last output came in 1972, and Martelange, the last Belgian slate site, closed at the end of the 1980s.\n\nBelgium was also the cradle of the European rolled-zinc industry. In 1806 the industrialist Jean-Jacques Dony was granted the right to work the zinc deposit at La Vieille Montagne near Liège, and the Société des Mines et Fonderies de Zinc de la Vieille-Montagne, founded in 1837, became a leading producer of building zinc, used on the roofs of 19th-century Paris and elsewhere.\n\n## Traditional and vernacular roofs\n\n- **Slate** (*ardoise*, Dutch *leisteen*) on houses, farms and churches of the Ardennes and the Semois valley.\n- **Ceramic tiles** (*dakpannen*, *tuiles*) across Flanders, Brabant and Hainaut, including glazed and smoked (blue-grey) finishes.\n- **Reed thatch** (*riet*) on farmhouses in Flanders and the Kempen.\n\n## Roofing today\n\nCeramic and concrete tiles are the usual coverings on new pitched-roof houses, with natural slate, much of it imported, and fibre-cement slates also common. Flat roofs on terraced housing, apartments and commercial buildings use bituminous, EPDM and other synthetic membranes, and green and blue roofs are promoted in cities for stormwater retention.\n\n## Codes, standards and regulation\n\nBuilding regulation in Belgium is largely a regional matter for Flanders, Wallonia and the Brussels-Capital Region, while European EN standards govern roofing products. Technical guidance for contractors comes from **Buildwise**, formerly the Belgian Building Research Institute (BBRI), a private research centre founded in 1959 at the initiative of the national federation of building contractors under the 1947 \"De Groote\" decree-law. Its statutory members are Belgium's more than 120,000 construction companies.\n\n## Industry\n\nThe Belgian group Etex owns the Eternit trademark for fibre-cement roofing sheets and slates, a material based on the asbestos-cement process patented by Ludwig Hatschek in 1900. The rolled-zinc business of Vieille-Montagne continues today under the VMZinc brand, part of Umicore.\n\n## Notable roofs\n\nBelgium's roofing heritage is best seen in its slate country: the former quarries and slate-roofed villages of Herbeumont, Bertrix and Vielsalm in the Ardennes, several of which are now interpreted as industrial heritage sites.\n\n## Local roofing terms\n\n- *Ardoise* / *leisteen*: slate.\n- *Dakpan* / *tuile*: roof tile.\n- *Riet* / *chaume*: thatch.\n- *Coticule*: a fine whetstone from the Vielsalm area, a by-product of the slate belt, used for sharpening razors.\n\n## Sources and gaps\n\nNational statistics on roof coverings, numbers of thatched roofs and data on Belgium's tile industry: published information is limited.","key_facts":[{"label":"Climate driver","value":"Wind and rain, North Sea maritime"},{"label":"Traditional materials","value":"Ardennes slate, ceramic tiles, reed thatch"},{"label":"Ardennes slate peak","value":"1877: 51 open-air and 116 underground workings"},{"label":"Last slate site closed","value":"Martelange, end of the 1980s"},{"label":"Building regulation","value":"Regional (Flanders, Wallonia, Brussels)"},{"label":"Construction research body","value":"Buildwise (formerly BBRI), founded 1959"}],"regions":["Europe"],"aliases":["Belgian roofing","Dakbedekking in België","Toitures en Belgique"],"related":["ardennes-slate","roofing-in-the-netherlands","roofing-in-the-netherlands-and-belgium","roofing-in-france","roofing-in-luxembourg","zinc-roofs-of-paris","zinc-roofing","eternit","fibre-cement-slate","dutch-and-danish-reed-thatch","buildwise"],"company":null,"sources":[{"title":"L'extraction des ardoises en suivant le fil historique","url":"https://gsb.naturalsciences.be/wp-content/uploads/2026/03/2-1-Lextraction-des-ardoises-en-suivant-le-fil-historique.pdf","publisher":"Geological Survey of Belgium"},{"title":"Vieille Montagne","url":"https://en.wikipedia.org/wiki/Vieille_Montagne","publisher":"Wikipedia"},{"title":"Buildwise is there for you","url":"https://www.buildwise.be/en/","publisher":"Buildwise"},{"title":"Eternit","url":"https://en.wikipedia.org/wiki/Eternit","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Ludwig Hatschek","url":"https://en.wikipedia.org/wiki/Ludwig_Hatschek","publisher":"Wikipedia"}]},{"slug":"roofing-in-belize","title":"Roofing in Belize","category":"world-roofing","type":"place","country":{"name":"Belize","iso2":"BZ"},"summary":"Belizean roofing: Maya pole-and-thatch houses of bay leaf and cohune palm, Garifuna thatch, and timber and metal roofs shaped by hurricanes.","body":"Belize, on the Caribbean coast of Central America, has a hot, humid climate, a low-lying coast and a long history of hurricane damage. Its roofing traditions combine Maya pole-and-thatch building, the thatched houses of Garifuna coastal villages, and the timber buildings of the British colonial period, most now roofed in corrugated metal or concrete.\n\n## Climate and hazards\n\n- **Hurricanes.** Hurricane Hattie in 1961 killed 307 people in what was then British Honduras. The governor estimated that 70% of the buildings in Belize City were damaged; most of the city's wooden buildings were destroyed and the storm tore the roofs off many others. The disaster led the government to build a new inland capital, Belmopan, completed in 1970.\n- **Heavy rain and humidity**, which shorten the life of thatch and timber.\n- **Storm surge and flooding** on the low coast.\n\n## Roofing history\n\n**Maya period.** Belize was part of the Classic Maya heartland. Archaeologists Heather McKillop and E. Cory Sills, writing about the waterlogged Paynes Creek salt works in southern Belize, describe pole-and-thatch buildings as probably the dominant construction of the prehistoric Maya area. At the site of Ek Way Nal, 68 of 140 identified building posts were of palmetto palm (*Acoelorraphe wrightii*), with others of mangrove, buttonwood, Santa María (*Calophyllum brasiliense*) and rosewood; canoes probably carried posts and palm thatch to the salt works.\n\n**Garifuna settlement.** The Garifuna, about a quarter of whom were deported to the island of Roatán in 1797, later settled along the Central American coast. A larger migration to Belize in the early 19th century is marked each year on Garifuna Settlement Day, 19 November; Dangriga is the centre of Belize's Garifuna community.\n\n**Colonial and modern.** Belize City was built largely of timber before Hattie destroyed most of its wooden buildings. Reinforced concrete and corrugated metal sheet are now common for houses and public buildings.\n\n## Traditional and vernacular roofs\n\n- **Maya thatch** (see Maya thatched house). In Toledo District, two palms are used. Bay leaf palm, a slow-growing understorey palm found only in well-forested areas, gives a durable roof but may take up to ten years to produce usable leaves and is becoming scarce. Cohune palm, common on disturbed land, is cheaper but less durable. Cutters need permission from the village and the Forest Department. Cohune fronds are split along the midrib and bundled in threes to fives; bay leaf fans are folded into a broom shape and woven onto the frame.\n- **Garifuna houses**: wooden or wattle-and-daub houses with thatched roofs, the wooden ones raised several feet on posts.\n- **Raised timber houses** on posts in towns, with metal roofs.\n\n## Roofing today\n\nCorrugated metal sheet and concrete slabs are the common roofs of modern housing, with thatch surviving in Maya villages and widely used on tourist cabañas and beach shelters (see palapa).\n\n## Notable roofs\n\n- **Maya sites** such as Paynes Creek, where submerged wooden posts of thatched buildings survive.\n\n## Local roofing terms\n\n- *Bay leaf* and *cohune*: the two main thatch palms.\n- *Naj*: house in Mopan Maya.","key_facts":[{"label":"Traditional materials","value":"Bay leaf and cohune palm thatch"},{"label":"Climate driver","value":"Hurricanes (Hattie, 1961)"},{"label":"Hattie damage","value":"About 70% of Belize City buildings damaged"},{"label":"Archaeological evidence","value":"Paynes Creek submerged posts"}],"regions":["Latin America"],"aliases":["Belizean roofing"],"related":["maya-thatched-house","palm-thatch","palapa","corrugated-iron","roofing-in-guatemala","roofing-in-mexico","roofing-in-honduras"],"company":null,"sources":[{"title":"Hurricane Hattie","url":"https://en.wikipedia.org/wiki/Hurricane_Hattie","publisher":"Wikipedia"},{"title":"Building with thatch","url":"https://ambergriscaye.com/pages/mayan/building-with-thatch.html","publisher":"Ambergris Caye (The Lodge at Big Falls)"},{"title":"Focusing on individual wooden buildings ... at the Paynes Creek Salt Works (Research Reports in Belizean Archaeology 18)","url":"https://par.nsf.gov//servlets/purl/10526553","publisher":"NSF Public Access Repository"},{"title":"Garifuna","url":"https://www.everyculture.com/wc/Afghanistan-to-Bosnia-Herzegovina/Garifuna.html","publisher":"EveryCulture"},{"title":"naj (Mopan and Yucatec Maya)","url":"https://kaweah.freedombox.rocks/kiwix/wiktionary_en_all_maxi_2023-04/naj","publisher":"Wiktionary (mirror)"}]},{"slug":"roofing-in-benin","title":"Roofing in Benin","type":"place","country":{"name":"Benin","iso2":"BJ"},"summary":"Most Beninese homes are roofed with metal sheet (tôle); heritage roofs include the straw and metal roofs of the Abomey palaces and the takienta of the north.","body":"Benin stretches from lagoons and a humid coast on the Gulf of Guinea to the savanna and Atakora hills of the north. Its traditional roofs were thatch of straw, grass or palm over earth walls, with the earthen tower-houses of the Batammariba in the north-west. Today the great majority of homes are roofed with corrugated metal sheet, known in French as *tôle*.\n\n## Climate and hazards\n\nThe south has two rainy seasons and high humidity; the north has a single rainy season and harmattan dust. Fire and wind are serious risks for thatched roofs: the Royal Palaces of Abomey were damaged by a tornado on 15 March 1984 and by a bushfire on 21 January 2009 that destroyed many buildings.\n\n## Roofing history\n\nThe kingdom of Dahomey, founded in 1625, built its capital at Abomey, where twelve successive kings added palaces until 1900. The palaces were built of laterite earth, water, timber and straw, with walls averaging about 0.5 m (20 in) thick, and have roofs of straw and sheet metal. In 1892-1894 King Béhanzin ordered the city and palaces burned during the French conquest.\n\nIn the north-west, the Batammariba settled the Koutammakou area, shared with Togo, in the 17th or 18th century.\n\n## Traditional and vernacular roofs\n\n- **Palace roofs at Abomey**: straw thatch over earth walls and timber of palm, bamboo, iroko or mahogany (see Royal Palaces of Abomey).\n- **Takienta of the Atakora**: earthen tower-houses with livestock below and granaries on the roof terrace; about 1,400 are still inhabited on the Beninese side (see Batammariba takienta).\n- **Thatch**: straw, grass and palm-leaf thatch remains on a minority of rural homes.\n\n## Roofing today\n\nIn the unweighted 2014 Multiple Indicator Cluster Survey sample (about 14,100 households), roofs were recorded as:\n\n| Main roof material | Share of sampled households |\n|---|---|\n| Metal sheet (*tôles*) | 81.3% |\n| Thatch, palm leaf or straw | 7.8% |\n| Cement | 5.3% |\n| Tiles | 2.6% |\n| Palm or bamboo | 0.7% |\n| Grass | 0.4% |\n| Wood planks | 0.4% |\n\nTiles and concrete together account for under a tenth of homes in the survey sample.\n\n## Codes, standards and regulation\n\nHeritage roofs are protected through World Heritage management; at Abomey, a buffer zone has been protected by urban-planning rules since 2006, and Law No. 2007-20 adds legal protection for cultural heritage.\n\n## Notable roofs\n\n- **Royal Palaces of Abomey**: ten palaces on 47 ha (116 acres), World Heritage site since 1985, on the List in Danger from 1985 to 2007.\n- **Koutammakou** (Beninese extension, 2023): Batammariba tower-houses.\n\n## Local roofing terms\n\n- **tôle** (French): metal roof sheet.\n- **paille** (French): straw thatch.\n\n## Sources and gaps\n\nSurvey figures are unweighted sample counts. Detailed information on southern vernacular house types (for example lagoon stilt villages), codes and industry: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal sheet (tôle), 81.3% (MICS 2014 file, unweighted)"},{"label":"Traditional materials","value":"Straw and palm thatch, earth, timber"},{"label":"Climate driver","value":"Tropical rain, wind storms, fire risk to thatch"},{"label":"Landmark","value":"Royal Palaces of Abomey (UNESCO 1985)"}],"regions":["Africa"],"aliases":["Beninese roofing","roofing in Benin"],"related":["roofing-in-west-africa","royal-palaces-of-abomey","batammariba-takienta","corrugated-iron","thatch","palm-thatch","roofing-in-togo","roofing-in-nigeria","roofing-in-niger"],"sources":[{"title":"MICS 2014 Bénin: matériau principal du toit (HC4)","url":"https://microdata.worldbank.org/catalog/3422/variable/F4/V458?name=HC4","publisher":"World Bank Microdata Library"},{"title":"Royal Palaces of Abomey","url":"https://whc.unesco.org/en/list/323/","publisher":"UNESCO World Heritage Centre"},{"title":"Royal Palaces of Abomey","url":"https://en.wikipedia.org/wiki/Royal_Palaces_of_Abomey","publisher":"Wikipedia"},{"title":"Koutammakou, the Land of the Batammariba","url":"https://whc.unesco.org/en/list/1140/","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-bhutan","title":"Roofing in Bhutan","category":"world-roofing","type":"place","country":{"name":"Bhutan","iso2":"BT"},"summary":"Bhutan's traditional roofs are low-pitched pine-shingle roofs held by stones over open lofts; most dzongs now have iron roofs, and sloping roofs are law.","body":"Bhutan is a small Himalayan kingdom whose roofs are unusually tightly bound up with national identity. The traditional roof is a broad, low-pitched roof of **loose pine shingles held down by stones**, lifted on timber above the walls so that an open, airy loft is left beneath it. Corrugated iron has replaced the shingles on almost all dzongs and on many other buildings, but the shape of the roof is protected by law: since 1998 every building in the country must have a sloping roof.\n\n## Climate and hazards\n\nBhutan rises from subtropical foothills on the Indian border to high Himalayan peaks. The monsoon brings heavy summer rain, valleys are swept by strong winter winds, and the country lies in the seismically active eastern Himalaya. Its dense forests have long supplied abundant timber, and Bhutanese building is correspondingly timber-centred, which also makes it vulnerable to fire and decay.\n\n## Roofing history\n\nBhutan's great fortress-monasteries, the **dzongs**, reached their peak of development in the 17th century, and large manor houses appeared from the late 19th century. Both used the same roofing principle as farmhouses: a timber roof frame of hardwood and bamboo, joined without nails, open at the eaves and covered with timber shingles weighted with stones. Buddhist temples (*lhakhang*) were often crowned with gilded copper roofs.\n\nIn modern times corrugated galvanised iron sheet has replaced timber shingles, so that almost all dzong roofs are now metal. Trongsa (Tongsa) Dzong retains one of the few surviving shingle roofs, which was being restored in 2006-07. In more recent years metal shingles have become popular for their durability.\n\n## Traditional and vernacular roofs\n\nThe **Bhutanese shingle roof** has these main features:\n\n- **Covering**: loose pine shingles laid on the frame and held in place by laths with stones placed on them at regular intervals, a design able to survive severe winter winds.\n- **Frame**: hardwood and bamboo, assembled without nails or iron, with a decorated timber cornice and no rain gutters.\n- **Open loft**: a large ventilated gap between the top of the walls and the roof, used for storing and drying chillies and animal skins and insulated with bamboo mats and hay. The raised roof gives the \"flying roof\" appearance typical of Bhutanese houses.\n\nA preserved example is the mid-18th-century farmhouse that houses the Folk Heritage Museum in Thimphu.\n\n## Roofing today\n\nCorrugated galvanised iron now covers almost all dzong roofs, and metal shingles are increasingly used.\n\n## Codes, standards and regulation\n\nA **royal decree of 1998** requires all buildings to have sloping roofs, together with multi-coloured timber fronts and small arched windows. The traditional code of conduct and design known as **Driglam Namzha** sets out rules for dzongs and ordinary buildings. Traditional construction does not use nails or iron bars.\n\n## Notable roofs\n\n- **Trongsa Dzong**: one of the few dzongs still with a shingle roof.\n- **Folk Heritage Museum, Thimphu**: a mid-18th-century farmhouse with a stone-weighted pine-shingle roof.\n- **Lhakhangs** (temples) with gilded copper roofs.\n\n## Local roofing terms\n\n- *dzong*: fortress-monastery\n- *lhakhang*: temple\n- *Driglam Namzha*: traditional code of etiquette and building\n\n## Sources and gaps\n\nInformation on modern roofing materials, statistics, building codes and domestic roofing manufacturers in Bhutan: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Corrugated galvanised iron (almost all dzongs); metal shingles increasing"},{"label":"Traditional materials","value":"Pine shingles weighted with stones, timber, bamboo"},{"label":"Regulation","value":"1998 royal decree requires sloping roofs"},{"label":"Design rules","value":"Driglam Namzha traditional code"},{"label":"Climate driver","value":"Monsoon rain, mountain winds, earthquakes"},{"label":"Surviving shingle dzong roof","value":"Trongsa Dzong (restored 2006-07)"}],"regions":["South Asia"],"aliases":["Bhutanese roofing","roofs of Bhutan"],"related":["bhutanese-shingle-roof","wood-shingle","corrugated-iron","metal-shingles","copper-roofing","roofing-in-nepal","roofing-in-india","roofing-in-china","pagoda-roof"],"company":null,"sources":[{"title":"Architecture of Bhutan","url":"https://en.wikipedia.org/wiki/Architecture_of_Bhutan","publisher":"Wikipedia"},{"title":"Dzong architecture","url":"https://en.wikipedia.org/wiki/Dzong_architecture","publisher":"Wikipedia"},{"title":"The Pride of Bhutanese Architecture","url":"https://folkheritagemuseum.org.bt/?p=129","publisher":"Folk Heritage Museum, Thimphu"},{"title":"Wood Work - Shingzo","url":"https://globalinch.org/craft/wood-work-shingzo/","publisher":"Global InCH"}]},{"slug":"roofing-in-bolivia","title":"Roofing in Bolivia","category":"world-roofing","type":"place","country":{"name":"Bolivia","iso2":"BO"},"summary":"Bolivian roofing: Andean grass thatch and clay tile, tiled Jesuit churches of Chiquitos, and metal sheet (calamina) on about half of homes (2015 survey).","body":"Bolivia covers the high Andean altiplano, deep valleys and broad tropical lowlands. Its roofs include grass thatch on the altiplano, clay tile in colonial towns and on the Jesuit mission churches of the lowlands, and corrugated metal sheet, which now covers about half of all homes.\n\n## Climate and hazards\n\n- **Altiplano**: high altitude, cold nights, strong sun and a summer rainy season.\n- **Lowlands** of Santa Cruz and the Beni: heavy tropical rain, which the Chiquitos mission builders met with wide porches and low eaves.\n- **Earthquakes**, addressed by the national seismic standard.\n\n## Roofing history\n\n**Andean.** Andean houses were traditionally of adobe or stone with roofs of grass thatch. The bunchgrass *ichu* (*Jarava ichu*), known in Spanish as *paja brava*, is a common grass of the altiplano. The ancient city of Tiwanaku, near Lake Titicaca, was inscribed by UNESCO in 2000.\n\n**Colonial.** The colonial cities of Potosí (UNESCO 1987) and Sucre (UNESCO 1991) preserve Spanish colonial buildings.\n\n**Jesuit missions.** In the eastern lowlands, Jesuits founded missions among the Chiquitos peoples in the 18th century. Their churches have a distinctive structure: a wooden skeleton of columns fixed in the ground carries the tile-covered roof, which was built first, while the adobe walls carry no load. Wide porches and low eaves protect the walls from rain, and roof and floor tiles were made in local tile works. The churches are about 16 to 20 m (52 to 66 ft) wide, 50 to 60 m (164 to 197 ft) long and 10 to 14 m (33 to 46 ft) high. The Swiss Jesuit Martin Schmid designed San Xavier (1749 to 1752), San Rafael (1747 to 1749) and Concepción (1752 to 1756). Restoration began in 1972 under the architect Hans Roth, and six churches were inscribed by UNESCO in 1990: San Xavier, San Rafael de Velasco, San José de Chiquitos, Concepción, San Miguel de Velasco and Santa Ana de Velasco.\n\n**Modern.** Corrugated metal sheet (*calamina*) has largely replaced thatch, and reinforced concrete slabs are used in cities.\n\n## Traditional and vernacular roofs\n\n- **Ichu thatch** on adobe houses of the altiplano (see Andean ichu thatch).\n- **Mission-style roofs** of clay tile on timber columns, with deep galleries, in Chiquitos.\n- **Roofs of straw, cane, palm or mud**, still recorded as a category in household surveys.\n\n## Roofing today\n\nThe National Statistics Institute's 2015 Household Survey (*Encuesta de Hogares*) asked about the material most used in roofs. Weighted results, as published in INE's microdata catalogue, were:\n\n- Metal sheet (*calamina o plancha*): 52.5%\n- Tile of cement, clay or fibre-cement (*teja*): 31.6%\n- Reinforced concrete slab (*losa de hormigón armado*): 9.3%\n- Straw, cane, palm or mud: 6.4%\n- Other: 0.2%\n\nThe 2024 census reported that the share of homes rated high-quality on a combined housing index rose from 39.3% in 2001 to 66.9% in 2024.\n\n## Codes, standards and regulation\n\nA 2012 comparative review listed Bolivia's NBDS standard of 2006 as its seismic code.\n\n## Notable roofs\n\n- **Jesuit Missions of the Chiquitos** (UNESCO 1990): tiled roofs on timber column frames.\n\n## Local roofing terms\n\n- *Calamina*: corrugated metal sheet.\n- *Teja*: tile (clay, cement or fibre-cement).\n- *Losa*: concrete slab.\n- *Paja brava*: ichu grass.","key_facts":[{"label":"Dominant material today","value":"Metal sheet (calamina), 52.5% (2015 survey)"},{"label":"Second material","value":"Tile, 31.6%"},{"label":"Traditional materials","value":"Ichu thatch, clay tile"},{"label":"Seismic code (2012 review)","value":"NBDS 2006"},{"label":"Heritage roofs","value":"Chiquitos mission churches (UNESCO 1990)"}],"regions":["Latin America"],"aliases":["Bolivian roofing"],"related":["andean-ichu-thatch","jesuit-mission-roof-tiles","clay-roof-tile","corrugated-iron","uros-totora-houses","roofing-in-peru","roofing-in-brazil","roofing-in-paraguay","roofing-in-argentina","roofing-in-chile"],"company":null,"sources":[{"title":"Encuesta de Hogares 2015: material más utilizado en los techos (s1a_09)","url":"https://anda4.ine.gob.bo/ANDA4_3/index.php/catalog/497/variable/V1618?pdf=1","publisher":"Instituto Nacional de Estadística de Bolivia"},{"title":"Datos Bolivia Censo 2024","url":"https://abyayala.tv.bo/wp-content/uploads/2025/08/Datos-Bolivia_Censo2024.pdf","publisher":"Abya Yala TV (INE Censo 2024 data)"},{"title":"Jesuit Missions of the Chiquitos","url":"https://en.wikipedia.org/wiki/Jesuit_Missions_of_the_Chiquitos","publisher":"Wikipedia"},{"title":"Jarava ichu","url":"https://en.wikipedia.org/wiki/Jarava_ichu","publisher":"Wikipedia"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-bosnia-and-herzegovina","title":"Roofing in Bosnia and Herzegovina","category":"world-roofing","type":"place","country":{"name":"Bosnia and Herzegovina","iso2":"BA"},"regions":["Europe"],"company":null,"summary":"How Bosnia and Herzegovina roofs its buildings: steep timber roofs on Ottoman-era houses, shingle and stone-slab tower roofs, and domed mosques.","aliases":["Bosnian roofing","Roofing in Bosnia","Krovovi u Bosni i Hercegovini"],"body":"Bosnia and Herzegovina's roofs reflect a mountainous, forested country shaped by four centuries of Ottoman rule and a later Austro-Hungarian period. Traditional houses combined stone, earth and timber under timber roofs, while mosques of the Ottoman period introduced domes and semi-domes to the skyline of towns such as Sarajevo.\n\n## Climate and hazards\n\nMuch of the country is mountainous, with cold, snowy winters inland and a warmer Mediterranean influence in Herzegovina. The country is seismic, and as part of Yugoslavia it came under the first Yugoslav seismic building code, drafted in 1964.\n\n## Roofing history\n\nOttoman rule brought the domed mosque. Early Ottoman domes were usually covered with terracotta tiles, but by the 16th century domes were generally covered with lead. The Gazi Husrev-beg Mosque in Sarajevo (1530-1531), a multi-domed mosque of the early classical Ottoman style, has nine domes; its main dome, on pendentives, is 13 m (43 ft) in outer diameter and 26 m (85 ft) high, and a semi-dome covers the qibla side. The Ferhadija Mosque in Banja Luka (1579) was destroyed in 1993. During the Siege of Sarajevo the mosque was deliberately shelled and badly damaged; reconstruction of the Gazi Husrev-beg Mosque began in 1996.\n\nIn the 20th century, architects reinterpreted the traditional house. Reuf Kadić's House Kopčić (1939) combines modern design with traditional eaves and a hipped roof.\n\n## Traditional and vernacular roofs\n\n- **Traditional house:** stone foundations, a ground floor of clay, unfired brick and timber ties, an upper floor of timber frame, and a roof that is almost always of timber.\n- **Tower houses (*odžak*, *kula*):** fortified stone towers whose roofs were tented (pyramidal) and covered in wooden shingles or limestone slabs.\n- **Mosques:** domes and semi-domes on pendentives, with porticoes covered by small domes.\n\n## Notable roofs\n\n- Gazi Husrev-beg Mosque, Sarajevo (1530-1531): nine domes\n- Ferhadija Mosque, Banja Luka (1579; destroyed 1993)\n- House Kopčić, Reuf Kadić (1939)\n\n## Local roofing terms\n\n- *odžak*, *kula* - tower house\n\n## Sources and gaps\n\nClimate data specific to roofing, detailed accounts of medieval and pre-Ottoman roofing, of vernacular roofs, wooden shingles (*šindra*) and Herzegovinian stone roofs, data on current roofing materials, current national regulations and information on domestic roofing manufacturers were not found in published sources.","key_facts":[{"label":"Traditional house roof","value":"Almost always timber"},{"label":"Tower roofs","value":"Tented, wood shingle or limestone slab"},{"label":"Landmark domes","value":"Gazi Husrev-beg Mosque (1530-1531), nine domes"},{"label":"Ottoman dome covering","value":"Lead, generally by the 16th century"}],"related":["ottoman-domes-in-the-balkans","kulla-tower-house","wood-shingle","dome","stone-slate","roofing-in-croatia","roofing-in-serbia","roofing-in-montenegro","roofing-in-turkey"],"sources":[{"title":"Architecture of Bosnia and Herzegovina","url":"https://en.wikipedia.org/wiki/Architecture_of_Bosnia_and_Herzegovina","publisher":"Wikipedia"},{"title":"Tower houses in the Balkans","url":"https://en.wikipedia.org/wiki/Tower_houses_in_the_Balkans","publisher":"Wikipedia"},{"title":"Gazi Husrev-beg Mosque","url":"https://en.wikipedia.org/wiki/Gazi_Husrev-beg_Mosque","publisher":"Wikipedia"},{"title":"Ottoman architecture","url":"https://en.wikipedia.org/wiki/Ottoman_architecture","publisher":"Wikipedia"},{"title":"1963 Skopje earthquake","url":"https://en.wikipedia.org/wiki/1963_Skopje_earthquake","publisher":"Wikipedia"},{"title":"Ferhat Pasha Mosque (Banja Luka)","url":"https://en.wikipedia.org/wiki/Ferhat_Pasha_Mosque_(Banja_Luka)","publisher":"Wikipedia"}]},{"slug":"roofing-in-botswana","title":"Roofing in Botswana","category":"world-roofing","type":"place","country":{"name":"Botswana","iso2":"BW"},"summary":"Botswana's Tswana houses have conical thatched roofs on clay-plastered walls with verandahs; modern homes use iron sheet, asbestos and concrete tiles.","body":"Botswana is a dry, largely flat country dominated by the Kalahari. Its traditional houses belong to the Tswana building tradition: houses with clay-plastered walls, a conical thatched roof and often a verandah carried on posts. Modern housing uses sheet metal, asbestos-cement and concrete tiles.\n\n## Climate and hazards\n\nThe climate is semi-arid with hot summers, when most rain falls in storms.\n\n## Roofing history\n\nCensus questionnaires since at least 1991 have recorded the roof material of each dwelling under concrete, slabs, blocks or tiles; asbestos; iron, zinc or tin; thatch; and other, showing that these were already the main materials by the late 20th century.\n\n## Traditional and vernacular roofs\n\nThe architectural historian Franco Frescura recorded a detailed Setswana building vocabulary:\n\n- **Roof**: *moteko* is the thatched roof covering, *setlhowa* the apex of a conical roof, *maribele* the eaves overhang, *tlhomeso* a timber rafter and *palelo* a batten.\n- **Structure**: *mophako* is a roof timber spanning between verandah posts and acting as a ring beam; *lomapo* a dowel at a beam end that seats it on the ring beam; *pinagare* a centre post carrying the thatcher's weight, normally cut away after the roof is finished but kept in many larger houses.\n- **Walls and verandah**: *lobota* is the perimeter wall, plastered with clay and dung (*gobatega*); *mokatako* a small raised verandah or verandah seat; *lotwana* a post supporting the verandah or eaves.\n\nThese terms are Setswana and apply across the Tswana-speaking area of Botswana and South Africa.\n\n## Roofing today\n\nCensus categories (iron, zinc or tin; asbestos; concrete tiles; thatch) indicate the range of materials in use.\n\n## Local roofing terms\n\n- *moteko*: thatched roof covering.\n- *setlhowa*: apex of a conical roof.\n- *maribele*: eaves.\n- *pinagare*: temporary centre post used in thatching.\n- *gobatega*: clay and dung wall plaster.\n\n## Sources and gaps\n\nDetailed archaeological evidence for early roofs: published information is limited. No roof-specific heritage listings were identified.\n\nRecent census roof shares (2011, 2022), Kalahari San shelter forms and information on Botswana building regulations and manufacturers: published information is limited.","key_facts":[{"label":"Traditional form","value":"Round mud-walled house with conical thatch and verandah"},{"label":"Traditional materials","value":"Grass thatch, poles, clay and dung plaster"},{"label":"Census roof categories","value":"Concrete/tiles, asbestos, iron/zinc/tin, thatch (1991)"},{"label":"Climate driver","value":"Semi-arid, summer storms"}],"regions":["Africa"],"aliases":["Tswana roofing","Botswanan roofing"],"related":["rondavel","thatch","conical-roof","corrugated-iron","asbestos-cement-roofing","concrete-roof-tile","roofing-in-southern-africa","roofing-in-south-africa","roofing-in-namibia","roofing-in-zimbabwe","roofing-in-zambia"],"company":null,"sources":[{"title":"Glossary - Tswana terms","url":"https://francofrescura.sahistory.org.za/glossary/glossary-tswana-terms/","publisher":"Franco Frescura / South African History Online"},{"title":"Glossary - M","url":"https://francofrescura.sahistory.org.za/glossary/glossary-m/","publisher":"Franco Frescura / South African History Online"},{"title":"Botswana 1991 Population and Housing Census (IPUMS subset): Material used for construction of the roof","url":"https://microdata.worldbank.org/catalog/6825/variable/BW1991A_ROOF","publisher":"World Bank Microdata Library"}]},{"slug":"roofing-in-brazil","title":"Roofing in Brazil","category":"world-roofing","type":"place","country":{"name":"Brazil","iso2":"BR"},"summary":"Brazilian roofing: Indigenous thatch, Portuguese colonial telha, fibre-cement and concrete laje; 81.9% of homes had tile or sheet roofs in 2019 (PNAD).","body":"Brazil's roofing reflects Indigenous building traditions, a Portuguese colonial heritage of curved clay tiles, a mostly tropical and subtropical climate with heavy seasonal rain, and a vast stock of self-built urban housing. Today most homes are covered by tiles or roofing sheets (*telhas*), often over a concrete slab (*laje*). Brazil mined chrysotile asbestos and used it in fibre-cement roofing until its Supreme Court banned it in 2017.\n\n## Climate and hazards\n\n- **Heavy tropical rain and intense sun** over most of the country, favouring generous overhangs, adequate pitch for tile roofs and ventilated roof spaces.\n- **Seismic design** is covered by the standard NBR 15421 (2006).\n\n## Roofing history\n\n**Indigenous.** Indigenous peoples lived in thatched houses (*ocas*), which the first colonists imitated. In the far north the Yanomami still build *shabonos*, rings of palm-thatched lean-to roofs around an open plaza, and Tukanoan peoples of the northwest Amazon build *malocas*, communal longhouses roofed with palm thatch.\n\n**Colonial (1500 to 1822).** The earliest colonial houses had straw roofs (*sapé*), like Indigenous dwellings, and clay tiles were first used on wealthier buildings before spreading. Walls of rammed earth (*taipa de pilão*) or wattle and daub (*pau a pique*) were protected from rain by wide eaves (*beirais*), whose rafter ends were often carved. Gable roofs were common in towns and hipped roofs on larger buildings; some town houses (*sobrados*) in Recife, Salvador and São Luís had gently curved roofs with upturned tiles at the corners. The standard tile was the curved *telha colonial* or *capa-canal*, laid in alternating rows of channels and covers.\n\n**Jesuit missions.** In the south, the Guaraní missions made their own clay tiles from the 17th century and replaced straw roofs with tile, partly as protection against fire. The Jesuit Missions of the Guaranis in Brazil and Argentina were inscribed by UNESCO in 1983.\n\n**Industrial era.** Flatter ceramic tiles of the French (Marseille) pattern, developed in France in the 19th century and exported widely, came into common use alongside the curved colonial tile. Fibre-cement sheet, made in Brazil by Eternit since 1940, became a common low-cost roof for houses, especially in lower-income urban areas, and for farm and industrial buildings, along with corrugated and trapezoidal steel sheet.\n\n**Asbestos ban.** On 29 November 2017 the Federal Supreme Court (STF), by 7 votes to 2 in cases ADI 3406 and ADI 3470, declared unconstitutional Article 2 of Federal Law 9.055/1995, which had permitted the extraction, manufacture, sale and distribution of chrysotile asbestos. The ruling has binding effect nationwide. Asbestos mining at Minaçu, Goiás, by Eternit's subsidiary SAMA continued for export under a 2019 state law until a court in Uruaçu, acting on a request by federal prosecutors, ordered it suspended in August 2021. Eternit, which filed for judicial recovery in March 2018, now makes asbestos-free fibre-cement and in 2019 launched fibre-cement solar tiles rated at 142 Wp each.\n\n## Traditional and vernacular roofs\n\n- **Telha colonial (capa-canal)**: curved clay tiles in the Portuguese tradition.\n- **Telha francesa (Marseille)**: flatter ceramic tile of French pattern.\n- **Sapé**: grass thatch of early colonial and rural houses.\n- **Oca**, **maloca** and **shabono**: Indigenous thatched houses.\n\n## Roofing today\n\nIBGE's Continuous National Household Sample Survey (PNAD Contínua) for 2019 reported the predominant roof covering of Brazilian homes as:\n\n- Tiles or sheets without a concrete slab (*telha sem laje de concreto*): 49.8% (36.0 million homes)\n- Tiles or sheets over a concrete slab (*telha com laje de concreto*): 32.1% (23.2 million)\n- Concrete slab only (*somente laje de concreto*): 15.5% (11.2 million)\n- Other materials: 2.6% (1.9 million)\n\nThe *laje* is standard in multi-storey buildings and very common in self-built houses, where a flat slab allows later upward extension; many houses combine a slab ceiling with a tiled pitched roof above.\n\n## Codes, standards and regulation\n\nTechnical standards are issued by ABNT (Associação Brasileira de Normas Técnicas) as NBR standards; the seismic design standard is NBR 15421 (2006). Asbestos is banned under the 2017 STF ruling.\n\n## Industry\n\n- **Eternit S.A.**: fibre-cement roofing sheets and accessories, concrete roof tiles, and solar roof tiles; active since 1940.\n- **Slate**: Brazil is reported to be the world's second-largest slate producer after Spain, with most output from around Papagaios in Minas Gerais; much is used for flooring and cladding, and not all meets European CE-marking requirements for roofing (see Brazilian slate).\n\n## Notable roofs\n\n- **Ouro Preto** (UNESCO 1980), **Olinda** (1982) and **Salvador** (1985): colonial towns; Salvador's sobrados include the Arcebispos House, built 1707 to 1715.\n- **Jesuit Missions of the Guaranis** (UNESCO 1983), shared with Argentina.\n- **Brasília** (UNESCO 1987).\n\n## Local roofing terms\n\n- *Telhado*: roof; *telha*: tile or roofing sheet.\n- *Capa-canal*: cover-and-channel curved tile.\n- *Laje*: concrete slab.\n- *Beiral*: eave.\n- *Fibrocimento*: fibre-cement.\n- *Sapé*: grass thatch.","key_facts":[{"label":"Tile or sheet without slab","value":"49.8% of homes (PNAD 2019)"},{"label":"Tile or sheet over slab","value":"32.1%"},{"label":"Slab only","value":"15.5%"},{"label":"Traditional covering","value":"Telha colonial (capa-canal) clay tile"},{"label":"Asbestos","value":"Banned by STF, 29 November 2017"},{"label":"Slate production","value":"Major producer (Papagaios, MG)"}],"regions":["Latin America"],"aliases":["Brazilian roofing","Telhados no Brasil"],"related":["roofing-in-portugal","clay-roof-tile","spanish-tile","eternit","asbestos-cement-roofing","history-of-asbestos-cement-roofing","brazilian-slate","maloca","shabono","jesuit-mission-roof-tiles","roofing-in-paraguay","roofing-in-argentina","roofing-in-uruguay","roofing-in-bolivia","roofing-in-peru","roofing-in-colombia","roofing-in-venezuela","roofing-in-guyana","roofing-in-suriname","fibre-cement-slate","natural-slate","interlocking-clay-tile"],"company":null,"sources":[{"title":"PNAD Contínua: Características gerais dos domicílios e dos moradores 2019","url":"https://biblioteca.ibge.gov.br/visualizacao/livros/liv101707_informativo.pdf","publisher":"IBGE"},{"title":"STF proíbe amianto em todo o país","url":"https://www.migalhas.com.br/quentes/270171/stf-proibe-amianto-em-todo-o-pais","publisher":"Migalhas"},{"title":"Colonial architecture of Brazil","url":"https://en.wikipedia.org/wiki/Colonial_architecture_of_Brazil","publisher":"Wikipedia"},{"title":"Do amianto à energia solar: Eternit leva telha que gera eletricidade para a favela","url":"https://istoedinheiro.com.br/do-amianto-a-energia-solar-eternit-leva-telha-que-gera-eletricidade-para-a-favela","publisher":"IstoÉ Dinheiro"},{"title":"Eternit paralisa mina de amianto em Goiás após ordem judicial","url":"https://www.bloomberglinea.com.br/2021/08/20/eternit-paralisa-mina-de-amianto-em-goias-apos-ordem-judicial/","publisher":"Bloomberg Línea"},{"title":"Eternit","url":"https://www.eternit.com.br/","publisher":"Eternit S.A. (Brazil)"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Asbestos cement","url":"https://en.wikipedia.org/wiki/Asbestos_cement","publisher":"Wikipedia"},{"title":"Arqueología en las Misiones Jesuitas de Guaraníes: las tejas decoradas de la iglesia de Santa Ana","url":"https://cau.iaa.fadu.uba.ar/wp-content/uploads/2019/03/Roca_Tejas-decoradas_SantaAna.pdf","publisher":"Instituto de Arte Americano, FADU-UBA"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"},{"title":"Shabono","url":"https://en.wikipedia.org/wiki/Shabono","publisher":"Wikipedia"},{"title":"Maloca","url":"https://en.wikipedia.org/wiki/Maloca","publisher":"Wikipedia"},{"title":"Eternit pede recuperação judicial e cai na bolsa","url":"https://exame.com/mercados/eternit-pede-recuperacao-judicial-e-cai-na-bolsa/","publisher":"Exame"}]},{"slug":"roofing-in-brunei","title":"Roofing in Brunei","category":"world-roofing","type":"place","country":{"name":"Brunei","iso2":"BN"},"summary":"Roofing in Brunei, from the palm-leaf and timber roofs of the Kampong Ayer stilt village to the glass-mosaic dome of the Omar Ali Saifuddien Mosque.","body":"Brunei Darussalam is a small sultanate on the north coast of Borneo. Its roofing heritage centres on Kampong Ayer, a centuries-old stilt village over the Brunei River whose houses were roofed with palm leaves and timber, and on the gilded domes of its 20th-century mosques.\n\n## Climate and hazards\n\nBrunei is equatorial, hot and humid, with heavy rainfall throughout the year. The coastal and riverine setting adds damp and storm exposure. Fire is a long-standing hazard in timber settlements.\n\n## Roofing history\n\nKampong Ayer, beside the capital Bandar Seri Begawan, is thought to have been settled from around the 8th century and was the main settlement of the Bruneian sultanate by the reign of Sultan Muhammad Shah (1363-1402). The Italian chronicler Antonio Pigafetta, who visited in 1521 with the Magellan expedition, described a town built entirely over salt water, with about 25,000 hearths. The Dutch visitor Olivier van Noort, in 1600-1601, noted that noble houses were light enough to be moved across the river during storms.\n\nEarly houses used nibung palm and hardwoods such as bulian, with roofs of palm leaves, bulian wood or nipa (*apong*) leaves to shed rain. Walls of nipa shoots gave way to timber planks by the early 20th century.\n\nUnder the British Residency, residents were encouraged to move onto land, and later public housing schemes offered more uniform houses, so the water village has shrunk: from about 28,000 people in 1981 to 8,902 in 2021.\n\n## Traditional and vernacular roofs\n\nKampong Ayer houses are built on stilts in the style of Malay houses, up to two storeys. Recorded traditional types include:\n\n- *rumah belah bumbung* - a house with a split (gabled) roof, built by commoners in the 19th century;\n- *rumah tungkup*;\n- *rumah potong limas* - with a cut hipped (*limas*) roof;\n- *rumah loteng* - an upper-class house with an upper storey;\n- *rumah berlanggar*.\n\nThe palm-leaf thatch common to Brunei, Malaysia, Indonesia and Singapore is known as attap (Malay *atap*, \"roof\").\n\n## Roofing today\n\nFires in Kampong Ayer remain common, attributed mainly to faulty wiring and the flammability of timber buildings.\n\n## Notable roofs\n\n- **Omar Ali Saifuddien Mosque**, Bandar Seri Begawan (built 1954-1958): its main dome, about 52 m (171 ft) high, is covered in a mosaic of more than three million pieces of Venetian glass; it was originally gilded with gold leaf, which flaked as the structure expanded and contracted.\n- **Kampong Ayer**: the stilt village's roofscape over the Brunei River.\n\n## Local roofing terms\n\n- *atap* - roof; palm thatch\n- *bumbung* - roof; *belah bumbung* - split (gable) roof\n- *limas* - hipped roof\n- *apong* - nipa palm (Brunei Malay)\n\n## Sources and gaps\n\nNational census data on roof materials, modern materials data, building codes and industry information: published information is limited.","key_facts":[{"label":"Traditional materials","value":"Nipa (apong) leaves, palm leaves, bulian wood"},{"label":"Historic settlement","value":"Kampong Ayer stilt village (Pigafetta, 1521: about 25,000 hearths)"},{"label":"Kampong Ayer population","value":"8,902 (2021)"},{"label":"Landmark roof","value":"Omar Ali Saifuddien Mosque dome, about 52 m (171 ft), 1958"}],"regions":["Southeast Asia"],"aliases":["Bruneian roofing","Brunei Darussalam roofing"],"related":["roofing-in-southeast-asia","attap-roof","palm-thatch","roofing-in-malaysia","roofing-in-indonesia","dome"],"company":null,"sources":[{"title":"Kampong Ayer","url":"https://en.wikipedia.org/wiki/Kampong_Ayer","publisher":"Wikipedia"},{"title":"Attap dwelling","url":"https://en.wikipedia.org/wiki/Attap_dwelling","publisher":"Wikipedia"},{"title":"Omar Ali Saifuddien Mosque","url":"https://en.wikipedia.org/wiki/Omar_Ali_Saifuddien_Mosque","publisher":"Wikipedia"}]},{"slug":"roofing-in-bulgaria","title":"Roofing in Bulgaria","category":"world-roofing","type":"place","country":{"name":"Bulgaria","iso2":"BG"},"summary":"Bulgarian roofing: low-pitched tiled roofs with deep eaves on Revival-period houses, heavy stone-slab (tikli) roofs in the Rhodopes and Balkan villages.","body":"Bulgaria's best-known traditional roofs belong to the houses of the National Revival period, from the end of the 18th century to the end of the 19th, when towns such as Plovdiv, Koprivshtitsa, Melnik and Samokov grew rich on trade. These houses have low-pitched roofs with wide, deep eaves, covered either with clay tiles or, in mountain villages, with heavy slabs of local stone.\n\n## Climate and hazards\n\nBulgaria has hot summers and cold winters, with heavy snow in the Balkan Mountains (Stara Planina) and the Rhodopes. Deep eaves protect walls from sun, rain and snow. Mountain houses are also exposed to fire and to the effects of depopulation and neglect.\n\n## Roofing history\n\nThe Revival period, which ended with Bulgaria's liberation from Ottoman rule in 1878, produced a distinctive house type, comparable to Ottoman houses in Istanbul, Edirne and Safranbolu. Upper floors were often wider than lower ones, so the roofs of houses on opposite sides of a narrow street can almost touch.\n\nA study of houses in Kotel in the Balkan Mountains describes roofs of three, and sometimes two or four, slopes carried on trusses spanning 10-12 m (33-39 ft), with a ridge rise of 1.5-1.7 m (4.9-5.6 ft) giving a pitch of about 20-25°. Corners were resolved with curved rafters, and the coverings were ceramic tiles bedded in clay, sometimes in a double layer whose weight can make tiles slip. Much of central Kotel burned in 1894; the Kozichkovi houses there, dated by inscriptions to 1880, were restored in 1969 but are now abandoned.\n\n## Traditional and vernacular roofs\n\n- **Tikli (stone slabs):** in the Rhodopes, traditional houses were roofed with flat stones instead of tiles. In the western Rhodope village of Dolen, about 350 traditional houses are covered with *tikli*, and in Staro Stefanovo in the central Balkan foothills, houses with heavy stone walls also have stone-slab roofs.\n- **Tiled Revival roofs:** clay tiles over timber trusses with large, low eaves, as in Plovdiv, Koprivshtitsa and Kotel.\n\n## Roofing today\n\nMany historic mountain houses are threatened by abandonment: when tile roofs fail, rain rots the boards and timber frames, and interventions with concrete and brick can cause new problems. Traditional carpentry skills are declining; one study recorded a master carpenter in his nineties with few commissions or apprentices.\n\n## Codes, standards and regulation\n\nAs an EU member, Bulgaria applies European product standards and the Eurocodes, including Eurocode 1, Part 1-3 for snow loads.\n\n## Notable roofs\n\n- **Old Plovdiv** and **Koprivshtitsa**, with Revival houses.\n- **Dolen**, Rhodopes, with stone-slab roofs on about 350 houses, and **Staro Stefanovo**, an architectural reserve with 95 buildings of monument quality.\n- **Zheravna**, a protected historic village of Revival houses.\n\n## Local roofing terms\n\n- *tikli* (тикли) - stone roofing slabs\n\n## Sources and gaps\n\nDetails of national regulations for roofs, market data and information on domestic roofing manufacturers: published information is limited.","key_facts":[{"label":"Traditional coverings","value":"Clay tile; stone slabs (tikli) in mountains"},{"label":"Revival roof pitch","value":"About 20-25° (Kotel study)"},{"label":"Stone-roof village","value":"Dolen, about 350 houses"},{"label":"Revival period","value":"Late 18th century to 1878"}],"regions":["Europe"],"aliases":["Bulgarian roofing","roofs in Bulgaria"],"related":["stone-slate","clay-roof-tile","zagori-stone-roofs","gjirokaster-stone-roofs","roofing-in-greece","roofing-in-romania","roofing-in-north-macedonia","roofing-in-serbia"],"company":null,"sources":[{"title":"Bulgarian National Revival Houses: Current State, Risks, and Opportunities (L. Alcaide De Wandeleer)","url":"https://www.traditionalarchitecturejournal.com/index.php/home/article/view/771","publisher":"Journal of Traditional Building, Architecture and Urbanism"},{"title":"8 Fascinating Facts About Bulgarian Revival Architecture","url":"https://theculturetrip.com/europe/bulgaria/articles/8-fascinating-facts-about-bulgarian-revival-architecture","publisher":"Culture Trip"},{"title":"The architectural sanctuaries in Bulgaria and their amazing properties","url":"https://ues.bg/en/blog/architecture-and-construction/155-the-architectural-sanctuaries-in-bulgaria-and-their-amazing-properties","publisher":"UES"},{"title":"Architecture of Residential Buildings in Bulgaria from the Revival Period (R. Raycheva)","url":"https://aup-journals.rtu.lv/aup/article/view/aup.2012.003","publisher":"Architecture and Urban Planning (Riga Technical University)"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"}]},{"slug":"roofing-in-burkina-faso","title":"Roofing in Burkina Faso","type":"place","country":{"name":"Burkina Faso","iso2":"BF"},"summary":"Burkina Faso combines Sahelian earth roofs and Kassena painted houses with metal sheet, plus influential low-tech roofs such as Gando and Nubian vaults.","body":"Burkina Faso, a landlocked country in the Sudano-Sahelian belt, has a strong tradition of earth building and has become an international reference for low-cost, climate-responsive roofs. Its villages still include earth-walled compounds with flat or thatched roofs, while most households now live under what national surveys classify as \"permanent\" roofing, chiefly metal sheet.\n\n## Climate and hazards\n\nThe north is Sahelian and dry; the south-west is wetter savanna. A single rainy season brings intense storms that erode earth roofs, followed by a long, hot dry season with harmattan dust. Metal-sheet roofs, now the norm, make interiors very hot, which has driven architectural experiments with double and ventilated roofs.\n\n## Roofing history\n\nEarth construction in the region is ancient and continuous. The Royal Court of Tiébélé, seat of the Kassena king (*Pè*) in the south of the country, was founded in the 16th century; its adobe buildings, painted exclusively by women, were added to the UNESCO World Heritage List in 2024.\n\n## Traditional and vernacular roofs\n\n- **Flat earth roofs**: timber joists covered with sticks or mats and compacted earth, as across the Sahel (see Sahelian earthen roofs).\n- **Kassena houses** (Tiébélé, Nahouri Province): adobe buildings whose painted decoration is the work of women.\n\n## Roofing today\n\nBurkina Faso's Harmonised Survey on Household Living Conditions (EHCVM) for 2021-2022, run by the national statistics institute INSD, records whether a household's roof is made of \"permanent materials\" (*matériaux définitifs*). In the cross-section survey sample, 91.5% of about 7,200 households answered yes (unweighted counts).\n\nThe Afrobarometer surveys, which interview about 1,200 adults, give more detail (unweighted sample counts):\n\n| Roof of respondent's home | 2015 | 2017 |\n|---|---|---|\n| Metal, aluminium, tin or zinc | 66.8% | 68.0% |\n| Thatch or grass | 24.7% | 15.3% |\n| Tiles | 0.5% | 7.9% |\n| Multiple materials | 5.4% | 3.3% |\n| Plastic sheets | 0.0% | 2.6% |\n| Concrete | 1.3% | 0.7% |\n\nThe Afrobarometer questionnaire has no separate category for earth roofs, so flat earth roofs are not identified in these figures.\n\nBurkina Faso is also the home of two widely studied responses to the heat and cost of metal roofs:\n\n- **The Gando primary school** (2001), by Diébédo Francis Kéré: a corrugated metal roof raised on light steel trusses above a ceiling of compressed earth blocks, so that air flows through the gap and the earth mass moderates indoor temperature. It received the Aga Khan Award for Architecture in 2004 (see Gando Primary School).\n- **Nubian vaults**: since 2000 the association La Voûte Nubienne, whose early work concentrated on Burkina Faso, Mali and Senegal, has trained masons to build timber-free earth-brick vaults.\n\n## Industry\n\nThe Gando school was built with compressed earth blocks made by villagers trained by LOCOMAT, a government agency promoting local building materials.\n\n## Notable roofs\n\n- **Gando primary school** (2000-2001): raised, ventilated metal roof over an earth-block ceiling.\n- **Royal Court of Tiébélé**: painted Kassena adobe architecture, World Heritage site since 2024.\n\n## Local roofing terms\n\n- **banco**: wet earth used for bricks and plaster.\n- **matériaux définitifs** (French, survey usage): \"permanent materials\", the survey category for durable roof materials.\n\n## Sources and gaps\n\nNo national roofing-specific code was identified in published sources. No information on domestic roofing-sheet manufacturers was found in published sources.\n\nSurvey figures are unweighted sample counts, and the Afrobarometer categories do not separate earth roofs. ","key_facts":[{"label":"Dominant material today","value":"Metal sheet, 68.0% (Afrobarometer 2017 file)"},{"label":"Permanent roofs","value":"91.5% of households (EHCVM 2021-22 file, unweighted)"},{"label":"Traditional materials","value":"Earth (banco) on timber"},{"label":"Climate driver","value":"Heat, intense seasonal storms, harmattan dust"},{"label":"Influential modern roof","value":"Gando school double roof (2001)"},{"label":"Heritage","value":"Royal Court of Tiébélé (UNESCO 2024)"}],"regions":["Africa"],"aliases":["Burkinabè roofing","roofing in Burkina Faso"],"related":["roofing-in-west-africa","gando-primary-school","nubian-vault","sahelian-earthen-roofs","corrugated-iron","thatch","roofing-in-mali","roofing-in-niger","roofing-in-ghana","roofing-in-cote-divoire"],"sources":[{"title":"EHCVM 2021-2022 Burkina Faso: toit en matériaux définitifs","url":"https://microdata.worldbank.org/catalog/6277/variable/F49/V2057?name=toit","publisher":"World Bank Microdata Library / INSD"},{"title":"Afrobarometer Survey 2015, Round 6, Burkina Faso: roof of respondent's home","url":"https://catalog.ihsn.org/catalog/8901/variable/F2/V643?name=Q105","publisher":"IHSN / Afrobarometer"},{"title":"Afrobarometer Survey 2017, Round 7, Burkina Faso: roof of respondent's home","url":"https://catalog.ihsn.org/catalog/9611/variable/F1/V320?name=Q105","publisher":"IHSN / Afrobarometer"},{"title":"Primary School at Gando","url":"https://archnet.org/sites/4363","publisher":"Archnet / Aga Khan Award for Architecture"},{"title":"Royal Court of Tiébélé","url":"https://en.wikipedia.org/wiki/Royal_Court_of_Ti%C3%A9b%C3%A9l%C3%A9","publisher":"Wikipedia"},{"title":"Nubian vault","url":"https://en.wikipedia.org/wiki/Nubian_vault","publisher":"Wikipedia"},{"title":"La Voûte Nubienne","url":"https://www.lavoutenubienne.org/","publisher":"Association La Voûte Nubienne"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-burundi","title":"Roofing in Burundi","category":"world-roofing","type":"place","country":{"name":"Burundi","iso2":"BI"},"summary":"Burundi's traditional roof is the domed straw thatch of the round rugo house, built on a frame of bent poles; recent national roofing data are scarce.","body":"Burundi is a small, hilly and densely settled country on the north-east shore of Lake Tanganyika. Its traditional house, the *rugo*, was a round, dome-shaped building made entirely of plant materials: a frame of poles bent into a dome, bound with rings of reed and papyrus and covered with thick straw thatch. The finest examples, the royal huts (*ingoro*), reached about 10 m (33 ft) across. The rugo of the Mugamba highlands is on Burundi's tentative list for World Heritage status.\n\n## Climate and hazards\n\nThe climate is tropical but tempered by altitude, with distinct rainy and dry seasons. Moisture is the main enemy of traditional straw roofs; traditional houses were sited mid-slope, with doors oriented with regard to the prevailing easterly winds, and roofs were sloped to shed rain.\n\n## Roofing history\n\nTraditional building knowledge is documented mainly through the rugo of the Mugamba region and reconstructions in museums. Building was a communal task: a household head called on relatives, friends and neighbours, typically 20 to 30 people, who worked in two teams on the roof and the exterior. Materials were collected across the rainy season, often from forests, and building took place in the dry season.\n\nThe measurements recorded in the 2018 study include a reconstructed hut displayed in a museum, and the rugo is treated today as a heritage form.\n\n## Traditional and vernacular roofs\n\n**The rugo.** A typical house had a floor area of 20 to 28 m² (215 to 300 sq ft) and an average height of about 3 m (10 ft). Its radius reflected status: about 2.5 m (8 ft) for a young household, about 3 m for a large or wealthy family, and up to 5 m (16 ft) for chiefs. Diameter was set out with a body measure (*intambwe*): a man lying on the ground with his arm outstretched.\n\nConstruction, as recorded in a 2018 study of Burundian traditional architecture:\n\n1. Some 45 to 60 piles about 2 m (6.6 ft) high were set 30 to 40 cm (12 to 16 in) apart, dug 50 to 60 cm deep.\n2. Between 120 and 200 bent poles about 4 m (13 ft) long formed the dome, tied with horizontal rings of reed core wrapped in papyrus.\n3. Inside, 8 to 13 pillars with carved, hoof-shaped ends supported the dome, and a spiral coil (*umutente*), about 200 m long, was built into the roof.\n4. The outer poles were folded together at about 3 m to close the dome (*guheta*).\n5. Walls were woven of split bamboo, the hut was thatched with straw, and a door frame, lintels and a roof topknot finished the work.\n\nThe inner face of the roof (*igisenge*) was lined with palm reed or papyrus. Damaged straw had to be replaced regularly, by one account twice a year, and old straw was reused as fertiliser.\n\n**The royal hut (*ingoro*)** measured about 10 m (33 ft) in outside diameter and 4 m (13 ft) high, with thatch about 90 cm (3 ft) thick; a papyrus mat once covered its thatch.\n\n**The compound.** The rugo complex was enclosed by a bamboo fence and divided into a front courtyard (*urugo*) used as a livestock park and a rear courtyard (*ikigo*), with smaller dwellings for family members.\n\n## Roofing today\n\nBurundi's 2016-17 Demographic and Health Survey (EDSB-III) recorded the main roof material of each household, using categories from thatch and palm leaf through metal, calamine and cement fibre, ceramic tiles and cement.\n\n## Notable roofs\n\n- **Traditional rugo of Mugamba**: added to Burundi's UNESCO tentative list on 9 May 2007.\n- **Museum reconstruction of a traditional hut**, documented in the 2018 study.\n\n## Local roofing terms\n\n- *rugo* (Kirundi): house or housing complex.\n- *ingoro*: the king's hut.\n- *igisenge*: the inner part of the roof.\n- *umutente*: spiral coil inside the dome.\n- *guheta*: folding the poles together to form the dome.\n- *intambwe*: body-based unit of measure.\n\n## Sources and gaps\n\nResults of the EDSB-III roof-material question: published information is limited.\n\nNational roofing statistics for Burundi were not found, so the present-day mix of metal sheet, tile and thatch is not quantified. The grass species used for straw thatch were not named in the sources. Building codes, standards and industry: published information is limited.","key_facts":[{"label":"Traditional roof","value":"Domed straw thatch on bent poles (rugo)"},{"label":"Royal hut","value":"About 10 m (33 ft) across, 4 m (13 ft) high, thatch about 90 cm (3 ft) thick"},{"label":"Typical house","value":"20-28 m² (215-300 sq ft), about 3 m (10 ft) high"},{"label":"Heritage","value":"Mugamba rugo on UNESCO tentative list (2007)"},{"label":"Climate driver","value":"High rainfall; moisture decays straw"}],"regions":["Africa"],"aliases":["Burundian roofing","roofs in Burundi"],"related":["mugamba-rugo","roofing-in-rwanda","roofing-in-tanzania","roofing-in-the-democratic-republic-of-the-congo","thatch","corrugated-iron","clay-roof-tile","nyakatsi","roofing-in-east-africa"],"sources":[{"title":"Ecological Traditional Architecture Research in Burundi","url":"https://www.scitepress.org/Papers/2018/75634/75634.pdf","publisher":"SCITEPRESS"},{"title":"Mugamba natural region","url":"https://en.wikipedia.org/wiki/Mugamba_natural_region","publisher":"Wikipedia"},{"title":"Le rugo traditionnel du Mugamba","url":"https://www.worldheritagesite.org/tentative/id/5142","publisher":"WorldHeritageSite.org"},{"title":"Burundi DHS 2016-2017: Main roof material (hv215)","url":"https://catalog.ihsn.org/catalog/7403/variable/F3/V99?name=hv215","publisher":"IHSN Survey Catalog"}],"company":null},{"slug":"roofing-in-cabo-verde","title":"Roofing in Cabo Verde","type":"place","country":{"name":"Cabo Verde","iso2":"CV"},"summary":"Cabo Verde is roofed overwhelmingly with flat concrete slabs; its traditional funco round house with palm thatch survives only in a few villages.","body":"Cabo Verde, a volcanic archipelago in the Atlantic off Senegal, has a roofing profile unlike the West African mainland. Almost all homes are roofed with concrete, while the traditional thatched round house, the *funco*, survives only in a few villages and museums.\n\n## Climate and hazards\n\nThe islands are arid to semi-arid, with a short, irregular rainy season and recurrent drought; drought slowed building in the early 20th century. Wind, salt air and, on Fogo, volcanic eruptions are the main hazards. Eruptions in 1995 and 2014-15 destroyed much of the village of Chã das Caldeiras inside the Fogo crater.\n\n## Roofing history\n\nCidade Velha (formerly Ribeira Grande), on Santiago, was described by UNESCO as the first European colonial town built in the tropics. It was a major Portuguese port of call in the 16th and 17th centuries and a hub of the Atlantic slave trade; its church dates from 1495. In colonial towns, wealthier families lived in two-storey *sobrados*. Neoclassical buildings, especially in Mindelo, followed from 1822 into the early 20th century. The Pedra de Lume lighthouse on Sal (1853) has a tiled roof.\n\nAfter independence in 1975, flat-roofed buildings became the norm, similar to modern construction on the African mainland.\n\n## Traditional and vernacular roofs\n\n- **Funco**: a circular house of stone (or, on Fogo, lava brick) with a conical roof thatched with palm fronds or straw, found mainly on Fogo, Santiago and Maio (see Funco). In colonial times it was mainly the house of poorer, Black rural families.\n- **Sobrado**: two-storey colonial town house, concentrated for example in São Filipe on Fogo.\n\n## Roofing today\n\nIn the 2014 Afrobarometer survey of Cabo Verde, interviewers recorded:\n\n| Main roof material | Share of respondents (2014) |\n|---|---|\n| Concrete | 88.9% |\n| Tiles | 5.8% |\n| Asbestos | 1.3% |\n| Multiple materials | 1.2% |\n| Metal, tin or zinc | 1.1% |\n| Thatch or grass | 0.4% |\n\nAfrobarometer surveys interview about 1,200 adults per country; these figures are unweighted counts in the survey sample. The near-absence of metal sheet sets Cabo Verde apart from every mainland country in the region.\n\n## Notable roofs\n\n- **Cidade Velha, Historic Centre of Ribeira Grande**: early colonial town with churches, a royal fortress and the 16th-century pillory, a World Heritage site.\n- **Funco at the Museu Municipal de São Filipe**, Fogo.\n- **Chã das Caldeiras**, Fogo: lava-built round houses rebuilt after successive eruptions, with new huts from early 2016.\n\n## Local roofing terms\n\n- **funco**: traditional round thatched house.\n- **sobrado** (Portuguese): two-storey colonial town house.\n- **laje** (Portuguese): concrete slab.\n- **telha** (Portuguese): roof tile.\n\n## Sources and gaps\n\nNo national roofing code was identified. No information on domestic roofing manufacturers was found in published sources.\n\nSurvey shares are unweighted; national census housing tables (INE Cabo Verde) on roof material are not well documented in published sources.","key_facts":[{"label":"Dominant material today","value":"Concrete, 88.9% (Afrobarometer 2014 file)"},{"label":"Traditional roof","value":"Palm-frond or straw thatch on the round funco"},{"label":"Climate driver","value":"Aridity, trade winds, salt air, volcanic hazard (Fogo)"},{"label":"Landmark","value":"Cidade Velha (described by UNESCO as the first European colonial town built in the tropics)"}],"regions":["Africa"],"aliases":["Cape Verde roofing","roofing in Cape Verde","Cape Verdean roofing"],"related":["roofing-in-west-africa","funco","flat-roof","palm-thatch","roofing-in-portugal","roofing-in-guinea-bissau","roofing-in-senegal"],"sources":[{"title":"Afrobarometer Survey 2014, Round 6, Cabo Verde: roof of respondent's home","url":"https://catalog.ihsn.org/catalog/8905/variable/F1/V306?name=Q105","publisher":"IHSN / Afrobarometer"},{"title":"Cidade Velha, Historic Centre of Ribeira Grande","url":"https://whc.unesco.org/en/list/1310/","publisher":"UNESCO World Heritage Centre"},{"title":"Funco (architecture)","url":"https://en.wikipedia.org/wiki/Funco_(architecture)","publisher":"Wikipedia"},{"title":"Architecture of Cape Verde","url":"https://en.wikipedia.org/wiki/Architecture_of_Cape_Verde","publisher":"Wikipedia"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-cambodia","title":"Roofing in Cambodia","category":"world-roofing","type":"place","country":{"name":"Cambodia","iso2":"KH"},"summary":"Roofing in Cambodia, from the corbelled stone and brick temples of Angkor to timber pagodas and a housing stock now roofed mostly with metal sheet and clay tile.","body":"Cambodia's roofing story spans the stone and brick temples of the Angkorian empire, the timber halls and houses that once stood around them, and a modern housing stock in which galvanised metal sheet and clay tile have almost entirely replaced thatch within a generation.\n\n## Climate and hazards\n\nCambodia has a tropical monsoon climate with a long, very wet rainy season, high heat and humidity, and widespread seasonal flooding around the Mekong and the Tonle Sap lake. Roofs must shed heavy rain fast and shade walls; houses in flood areas are raised on posts.\n\n## Roofing history\n\n**Angkorian temples (9th-15th centuries).** The earliest Angkorian temples, such as the towers of Preah Ko, Lolei and Bakong (dedicated 881), were built mainly of brick. Ta Keo in the 10th century was the first temple built almost entirely of sandstone, which came from the Kulen hills; laterite was used for foundations and hidden structure.\n\nKhmer builders never used the true arch. Rooms, passages and galleries were spanned with lintels or with corbelling, in which each course of stone projects slightly beyond the one below until the two sides meet. Corbelling limited the width of stone-roofed spaces, and corbelled roofs tend to collapse once a building is neglected; preventing this remains a conservation challenge at Angkor. Builders sometimes avoided the problem by topping stone walls with a light timber roof.\n\nArt historians divide the period into styles, including Kulen (825-875), Preah Ko (877-886), Bakheng (889-923), Angkor Wat (1080-1175) and Bayon (1181-1243).\n\n**Timber and tile.** Palaces and ordinary buildings were made of wood and have not survived. A 13th-century Chinese account describes palace buildings crowned with lead-tiled roofs. Bas-reliefs at the Bayon and Banteay Chhmar show timber buildings with triangular gables and double-tiered roofs. Late 12th-century \"halls of dancers\" at Ta Prohm, Preah Khan and other temples originally had perishable roofs, of which only the stone walls remain.\n\n**Post-Angkor.** As Theravada Buddhism spread, timber architecture became the norm for temples. The steep gabled and multi-tiered roofs seen in the Bayon reliefs are still used on Khmer palaces and pagodas, for example Wat Botum in Phnom Penh.\n\n## Traditional and vernacular roofs\n\nThe rural Khmer house has a timber frame raised on posts and a steep gabled roof, traditionally thatched, with deep overhangs that keep rain off the walls. Pagoda and palace roofs are typically double-tiered and steeply gabled, a form already shown in the Angkorian reliefs of the Bayon. Carved gable boards on Khmer buildings belong to a wider regional family that includes Thai, Lao and Malay houses.\n\n## Roofing today\n\nCambodia's Socio-Economic Survey (CSES) tracks roof materials of occupied dwellings. Between 2004 and 2013 the share with \"hard\" roofs rose from 71.3% to 93.5%, while thatch fell from 21.4% to 6.1%. In 2013 the national breakdown was:\n\n- Galvanised iron or aluminium: 53.7%\n- Clay tiles: 26.0%\n- Fibre cement: 9.3%\n- Concrete: 4.3%\n- Thatch: 6.1%\n\nConcrete roofs are concentrated in Phnom Penh (32.2% of dwellings in 2013, against 0.2% in rural areas), reflecting flat-roofed shophouses and apartment buildings. In rural areas tile (28.8%) and metal (53.5%) dominate, and thatch remained on 7.7% of rural dwellings in 2013.\n\n## Industry\n\nClay tile production and roll-forming of metal sheet are both established, but no manufacturer or association data was found.\n\n## Notable roofs\n\n- **Angkor** (UNESCO World Heritage): stone corbel-vaulted galleries and towers, notably Angkor Wat and the Bayon.\n- **Royal Palace and pagodas of Phnom Penh**: multi-tiered tiled roofs descended from the forms shown in Angkorian reliefs.\n\n## Sources and gaps\n\nBuilding-code and industry information and a glossary of Khmer roofing terms: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Galvanised iron or aluminium, 53.7% of dwellings (CSES 2013)"},{"label":"Clay tile share","value":"26.0% (2013)"},{"label":"Thatch share","value":"21.4% (2004) to 6.1% (2013)"},{"label":"Ancient technique","value":"Corbelled stone and brick vaults at Angkor (no true arch)"},{"label":"Climate driver","value":"Monsoon rain and seasonal flooding"}],"regions":["Southeast Asia"],"aliases":["Khmer roofing","Cambodian roofing"],"related":["roofing-in-southeast-asia","khmer-corbel-vault","corrugated-iron","clay-roof-tile","thatch","palm-thatch","corrugated-fibre-cement-sheet","roofing-in-thailand","roofing-in-laos","roofing-in-vietnam","thai-temple-roof"],"company":null,"sources":[{"title":"Khmer architecture","url":"https://en.wikipedia.org/wiki/Khmer_architecture","publisher":"Wikipedia"},{"title":"CSES housing: occupied dwellings by kind of roof materials and geographical domain, 2004 and 2007-2013","url":"https://nis.gov.kh/nis/CSES/Data/CSES_2013/CSES_Housing_files/sheet001.htm","publisher":"National Institute of Statistics, Cambodia"}]},{"slug":"roofing-in-cameroon","title":"Roofing in Cameroon","category":"world-roofing","type":"place","country":{"name":"Cameroon","iso2":"CM"},"summary":"Cameroon's roofs range from Musgum earthen domes and Bamileke conical thatch to Baka leaf huts; corrugated iron has replaced many older forms.","body":"Cameroon stretches from the Lake Chad basin in the north, through savanna and the volcanic Western Highlands, to equatorial rainforest and a humid Atlantic coast. Its traditional roofs are among the most varied in Africa: the tall, self-supporting earthen domes of the Musgum on the Logone floodplain, the clay compounds of the Kotoko towns, the high conical thatched roofs of the Bamileke chiefdoms in the West Region, and the leaf domes (*móngulu*) of Baka forest camps in the south-east. Across the country, concrete bricks and corrugated iron have replaced many older housing forms.\n\n## Climate and hazards\n\nThe south and coast are hot, wet and humid for most of the year, which favours steep, fast-draining roofs and rots organic materials. The Western Highlands are cooler and rainy. The north is semi-arid, with a single short rainy season, intense sun and seasonal floods; Musgum domes had a small top opening that could serve as an escape hatch in floods. Termites and fire threaten thatch everywhere.\n\n## Roofing history\n\nThe deepest documented roofing traditions are those of the north and the Grassfields. At Bandjoun, the chiefdom's great hut is attributed by tradition to King Notouom I about four centuries ago and has been restored regularly since; its oldest central pillars have survived three fires. In the far north, Kotoko city-states such as Logone-Birni built in clay by accretion, adding new enclosures around older ones and sharing walls between related households. The Musgum built their earthen domes, tall shells of compressed mud, until cement and metal sheet made them seem outdated in the 20th century; very few are now built, though renewed interest has led to some new construction.\n\nIn the 20th century cement and corrugated iron came into use, and even heritage buildings changed: the great hut at Bandjoun lost its original thatch to corrugated iron, though its interior remains intact.\n\n## Traditional and vernacular roofs\n\n- **Musgum *tolek*** (Far North Region): a conical or beehive dome of sun-dried mud, nearly 9 m (30 ft) tall, built in coils without formwork, with raised ribs that serve as footholds and drain rain. See Musgum tolek.\n- **Bamileke and Grassfields house** (West and North-West regions): a square or rectangular building with walls of prefabricated panels, traditionally of raffia palm frond spines or bamboo bound with fibre, under a high conical thatched roof. In chiefdoms the conical roofs carry symbolic meaning, and the number of peaks on a notable's roof reflects rank. See Bamileke conical roof.\n- **Kotoko clay compounds** (Logone-Birni and other towns): clay houses and enclosures built around one another; at the early Kotoko town of Houlouf, houses were rectangular mud-brick buildings with flat roofs set in walled compounds.\n- **Baka *móngulu*** (south-eastern rainforest): a hemispherical frame of thin branches covered with large Marantaceae leaves, built mainly by women. See Mongulu.\n\n## Roofing today\n\nCameroon's 2018 Demographic and Health Survey (EDS) records the main roof material of each household in categories from thatch and palm leaf, rustic mats, palm or bamboo and wood planks to metal, calamine or cement fibre, ceramic tiles and cement. Across the country, concrete bricks and corrugated iron roofs have replaced many older housing forms. In the rainforest and Grassfields, earth-plastered timber-frame houses (*poto-poto*) and rectangular mud-brick houses are typically roofed with palm thatch or corrugated iron; in the north, round mud houses are traditionally crowned with thatch. Wealthier urban households build concrete houses, while the poorest live in mud houses under thatch or iron sheet.\n\n## Notable roofs\n\n- **Bandjoun chiefdom great hut** (West Region): about 17 m (56 ft) high, with carved pillars, bamboo facades woven with plant fibre and an attic granary under a conical roof now covered in corrugated iron.\n- **Musgum domes at Pouss and nearby villages** (Far North Region).\n\n## Local roofing terms\n\n- *tolek* (Munjuk, the Musgum language): the domed earthen house; in French *case obus* (\"shell house\").\n- *móngulu* (Baka): leaf-domed forest hut.\n- *poto-poto*: earth-plastered timber-frame (wattle-and-daub) house.\n\n## Sources and gaps\n\nHousehold roofing shares from the 2018 DHS and census were not found, so the present-day mix of materials is not quantified. The construction of Kotoko flat roofs (beams and earth layers): published information is limited. National codes, standards and manufacturers were not identified. The spelling *teleuk* sometimes used for the Musgum house: published information is limited.","key_facts":[{"label":"Traditional roofs","value":"Musgum earthen domes, Bamileke conical thatch, Baka leaf domes"},{"label":"Common materials today","value":"Corrugated iron, concrete, palm thatch (no national shares obtained)"},{"label":"Landmark roof","value":"Bandjoun great hut, about 17 m (56 ft)"},{"label":"Climate driver","value":"Equatorial rain in south, semi-arid north with floods"}],"regions":["Africa"],"aliases":["Cameroonian roofing","roofs in Cameroon"],"related":["musgum-tolek","bamileke-conical-roof","mongulu","thatch","corrugated-iron","mud-roof","hausa-earth-vaults-and-domes","sahelian-earthen-roofs","roofing-in-nigeria","roofing-in-chad","roofing-in-the-central-african-republic","roofing-in-gabon","roofing-in-equatorial-guinea","roofing-in-the-republic-of-the-congo","roofing-in-west-africa"],"sources":[{"title":"Musgum mud hut","url":"https://en.wikipedia.org/wiki/Musgum_mud_hut","publisher":"Wikipedia"},{"title":"Bandjoun","url":"https://en.wikipedia.org/wiki/Bandjoun","publisher":"Wikipedia"},{"title":"Traditional Bamileke Architecture in Western Cameroon: The Building as an Expression of Intention","url":"https://macrothink.org/journal/index.php/ijch/article/view/24045","publisher":"International Journal of Culture and History"},{"title":"Pygmy camp with leaf and bark huts","url":"https://pygmies.org/baka/camps.php","publisher":"pygmies.org"},{"title":"Fractals in African Architecture: Kotoko","url":"https://gauss.math.yale.edu/fractals/Panorama/Architecture/AfricanArch/Kotoko.html","publisher":"Yale University"},{"title":"Cameroon DHS 2018: Main roof material (hv215)","url":"https://microdata.worldbank.org/catalog/3717/variable/F3/V99?name=hv215","publisher":"World Bank Microdata Library"},{"title":"African architecture: Geographic influences","url":"https://www.britannica.com/art/African-architecture/Geographic-influences","publisher":"Encyclopaedia Britannica"},{"title":"A political history of the Kotoko city states (ca. 1000-1900)","url":"https://www.africanhistoryextra.com/p/a-political-history-of-the-kotoko","publisher":"African History Extra"},{"title":"Culture of Cameroon","url":"https://www.everyculture.com/Bo-Co/Cameroon.html","publisher":"Countries and Their Cultures (everyculture.com)"},{"title":"Architectural designs that adapt to environment: Mousgoum dwellings, Pouss, Cameroon","url":"https://radio-future-africa.org/adaptive-architecture-mousgoum-dwellings-pouss-cameroon/","publisher":"Radio Future Africa"}],"company":null},{"slug":"roofing-in-canada","title":"Roofing in Canada","category":"world-roofing","type":"place","country":{"name":"Canada","iso2":"CA"},"summary":"Canadian roofing: Inuit snow and sod houses, bark longhouses, cedar plank houses and Norse turf; today asphalt shingles and metal under the National Building Code.","body":"Canadian roofing is defined by cold. Most of the country has long winters, deep snow and repeated freeze-thaw, and the coasts add wind-driven rain and salt. The country's roof history includes highly specialised cold-climate shelters, from the Inuit snow house to the cedar plank houses of the Pacific coast, and the earliest known European buildings in the Americas.\n\n## Climate and hazards\n\n- **Snow load**: the National Building Code of Canada gives ground snow and rain loads for communities across the country.\n- **Ice dams**: heat escaping from a house melts roof snow that refreezes at the cold eaves; insulation, a ventilated cold roof space and an eave membrane are the standard defences.\n- **Wind-driven rain** on the British Columbia coast and in Atlantic Canada, where hurricanes and post-tropical storms occasionally arrive.\n- **Permafrost and extreme cold** in the North, affecting foundations and roof assemblies.\n\n## Roofing history\n\n**Inuit and Thule shelters.** In the Central Arctic and the Qaanaaq area of Greenland, the snow house (*iglu*, more precisely *igluvijaq*) was built of wind-packed snow blocks laid in a catenary dome that needs no support during construction. Most other Inuit used snow mainly to insulate dwellings of whalebone and hide. In the transitional seasons, Thule people and their Inuit descendants built the *qarmaq*, with low walls of snow, stone or sod, a whalebone frame and a roof of skins or, later, canvas, packed with moss; it remained in use into the 1950s (see qarmaq).\n\n**Eastern Woodlands.** Huron-Wendat, Haudenosaunee, Petun and Neutral communities in Southern Ontario lived in longhouses into about the 18th century. Bent poles lashed to wall posts made a rounded roof sheathed in bark, cedar for the Wendat and elm for the Haudenosaunee, with roof vents over hearths spaced 6-13 m (20-43 ft) apart. A house at the Moyer site in Southern Ontario measured 93 m (305 ft) long (see longhouse-roof).\n\n**Pacific coast.** From coastal British Columbia to Alaska, Coast Salish, Kwakwaka'wakw and other nations built rectangular houses of split red cedar planks under gabled or shed roofs; the Paul Mason site at Kitselas Canyon, British Columbia, is about 3,000 years old. Simon Fraser recorded a house in 1808 with plank walls 11 ft (3.4 m) high (see plank-house).\n\n**Norse turf.** At L'Anse aux Meadows, Newfoundland, an 11th-century Norse site of eight buildings had timber frames covered with turf cut from the nearby peat bog (see scandinavian-sod-roofs for the Norse tradition).\n\n**New France and after.** Settlers in New France used wooden shingles (*bardeaux*) and later sheet metal. Quebec builders developed a characteristic flat-lock tinplate roof, *tôle à la canadienne*, in which small sheets are folded together and nailed at an angle; early sheets were flattened from containers and later imported from England. The batten-seam *tôle à baguettes*, probably introduced around 1800, became common in the 19th century, with tinplate on the oldest roofs, galvanised sheet after about 1850 and copper on prestigious buildings. Slate is scarce in Quebec but was used on some 19th-century churches. Prairie settlers in the 19th and early 20th centuries built sod houses, including the Mennonite *semlin*.\n\n## Traditional and vernacular roofs\n\n- **Iglu** and **qarmaq** (Inuktitut).\n- **Bark longhouse** of the Haudenosaunee and Wendat.\n- **Cedar plank house** of the Pacific Northwest.\n- **Norse turf house** at L'Anse aux Meadows.\n- **Québécois sheet-metal roofs**, *tôle à la canadienne* and *tôle à baguettes*, on houses, churches and spires.\n- **Cedar shingles and shakes** in British Columbia and the Maritimes.\n\n## Roofing today\n\nAs in the United States, asphalt shingles are the most common covering on houses. Organic-felt shingles left the Canadian market when the last producer, Building Products of Canada, stopped making them in 2011; current products are glass-mat based. Metal roofing in standing seam panels and stamped profiles is widely used in Quebec, Atlantic Canada and rural and northern areas, partly because it sheds snow. Flat and low-slope roofs on commercial and multi-unit buildings use modified bitumen, built-up roofing and single-ply membranes, often in protected or inverted assemblies with insulation above the membrane.\n\n## Codes, standards and regulation\n\nThe National Building Code of Canada is a model code published by the National Research Council of Canada for the Canadian Commission on Building and Fire Codes, normally on a five-year cycle. It has no force until adopted: some provinces adopt it directly, while Alberta, British Columbia and Ontario publish their own codes based on it, and Vancouver has its own building by-law. Houses and small buildings of up to three storeys and 600 m² (about 6,460 ft²) fall under Part 9, a prescriptive section written for builders. Toronto adopted a by-law in 2009 requiring green roofs on new residential buildings of six storeys or more and, later, on industrial buildings.\n\n## Industry\n\nCanada has domestic producers of asphalt shingles, metal roofing and wood shakes and shingles, and provincial roofing contractor associations. Western red cedar shakes and shingles are a traditional British Columbia export.\n\n## Notable roofs\n\n- **L'Anse aux Meadows**, Newfoundland: reconstructed Norse turf-roofed buildings at a UNESCO World Heritage Site.\n- **Mother House of the Grey Nuns**, Montreal: copper spires and bell tower, restored over 17 months from 1997.\n- **St. George's Anglican Church**, Montreal (1869-1870): green and red slate laid in geometric patterns.\n- **Sainte-Marie among the Hurons**, Midland, Ontario: a reconstruction of a c. 1640 mission with bark-covered longhouses.\n\n## Local roofing terms\n\n- *Iglu* / *igluvijaq* (Inuktitut): house / snow house.\n- *Qarmaq* (pl. *qarmat*, Inuktitut): sod, stone or snow-walled house with a skin roof.\n- *Bardeau* (French): wooden shingle.\n- *Tôle à la canadienne* (French): Quebec flat-lock sheet-metal roof.\n- *Tôle à baguettes* (French): batten-seam sheet-metal roof.\n## Sources and gaps\n\nNo Canadian census data on roof material were found in published sources.","key_facts":[{"label":"Model code","value":"National Building Code of Canada (NRC)"},{"label":"Houses","value":"Part 9: up to 3 storeys, 600 m² (6,460 ft²)"},{"label":"Common coverings","value":"Asphalt shingles, metal, cedar, membranes"},{"label":"Key hazard","value":"Snow load and ice dams"},{"label":"Earliest European roofs","value":"Norse turf, L'Anse aux Meadows, 11th century"},{"label":"Traditional Quebec roof","value":"Tôle à la canadienne (flat-lock sheet metal)"}],"regions":["North America","Arctic"],"aliases":["Canadian roofing"],"related":["national-building-code-of-canada","asphalt-shingle","metal-roofing","wood-shake","wood-shingle","sod-roof","qarmaq","longhouse-roof","plank-house","roofing-in-the-united-states","scandinavian-sod-roofs","ice-dam","snow-load"],"company":null,"sources":[{"title":"National Building Code of Canada","url":"https://en.wikipedia.org/wiki/National_Building_Code_of_Canada","publisher":"Wikipedia"},{"title":"Ice dam (roof)","url":"https://en.wikipedia.org/wiki/Ice_dam_(roof)","publisher":"Wikipedia"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"},{"title":"Igloo","url":"https://en.wikipedia.org/wiki/Igloo","publisher":"Wikipedia"},{"title":"Qarmaq","url":"https://en.wikipedia.org/wiki/Qarmaq","publisher":"Wikipedia"},{"title":"Longhouse","url":"https://www.thecanadianencyclopedia.ca/en/article/longhouse","publisher":"The Canadian Encyclopedia"},{"title":"Plank house","url":"https://en.wikipedia.org/wiki/Plank_house","publisher":"Wikipedia"},{"title":"L'Anse aux Meadows National Historic Site","url":"https://whc.unesco.org/en/list/4/","publisher":"UNESCO World Heritage Centre"},{"title":"Roofing","url":"https://www.patrimoine-religieux.qc.ca/en/roofing/","publisher":"Conseil du patrimoine religieux du Québec"},{"title":"Sod house","url":"https://en.wikipedia.org/wiki/Sod_house","publisher":"Wikipedia"},{"title":"Simon Fraser","url":"https://www.thecanadianencyclopedia.ca/en/article/simon-fraser","publisher":"The Canadian Encyclopedia"}]},{"slug":"roofing-in-chad","title":"Roofing in Chad","category":"world-roofing","type":"place","country":{"name":"Chad","iso2":"TD"},"summary":"Chad's roofs range from flat earth roofs of Kotoko walled towns and thatched round huts in the south to nomads' tents; iron and concrete are spreading fast.","body":"Chad spans the Sahara in the north, the dry Sahel in the centre and wetter savanna in the south, with Lake Chad and the Logone and Chari rivers in the south-west. Its building traditions follow that gradient: tents and light shelters among the nomadic groups of the sparsely settled north, clay buildings in Sahelian towns such as Abéché, the walled clay cities of the Kotoko on the Logone-Chari plain, and round, thatched houses in the villages of the farming south. Corrugated iron and concrete construction is now spreading rapidly.\n\n## Climate and hazards\n\nRainfall rises sharply from north to south, with a single rainy season. In the Sahel and north, the main stresses on roofs are intense sun, extreme heat and wind-blown dust; the south receives more rain. Organic roofs face termites and fire throughout.\n\n## Roofing history\n\n**Kotoko city-states.** From about 1000 CE, Kotoko towns grew up on the plains south of Lake Chad, a region now divided between Chad and Cameroon. At the early town of Houlouf, which grew between about 1000 and 1400 CE, an earthen rampart enclosed some 16 ha (40 acres) of rectangular mud-brick houses with flat roofs, arranged in walled compounds within named city quarters and around a large palace. Later towns had palaces, as at Gulfey and Logone-Birni, and mosques, as at Kousseri; their clay buildings grew by accretion, with new enclosures built against older ones.\n\n**Round to square.** A 1971 study of the strip of land between the Logone and Chari rivers south of the capital (then Fort-Lamy, founded by the French in 1900, now N'Djamena) documented the replacement of round traditional dwellings by rectangular houses and examined the motives behind the change.\n\n**Modern period.** Old capitals keep few historic buildings beyond some palaces and mosques. N'Djamena was heavily damaged in the war of 1980-1982 and has since grown rapidly, with services and infrastructure lagging. Across the country, iron-and-concrete buildings increasingly stand beside traditional mud houses.\n\n## Traditional and vernacular roofs\n\n- **Flat earth roofs** on rectangular mud-brick houses in Kotoko towns and other Sahelian settlements (see Sahelian earthen roofs).\n- **Round traditional dwellings** of the Logone-Chari plain and the farming south, documented in 1971 as being replaced by rectangular houses; a historical photograph records a communal house in Chad with a newly thatched roof. The Sara, the main farming people of the south, live mainly between Lake Iro and the Logone river.\n- **Earthen domes**: across the border in Cameroon's Far North, the Musgum built tall earthen domes (see Musgum tolek).\n- **Tents and shelters** of nomadic groups in the north.\n\n## Roofing today\n\nTraditional house styles remain in the countryside, but corrugated-iron and concrete buildings have rapidly expanded, especially in towns.\n\n## Notable roofs\n\n- **Abéché**: a town noted for clay buildings, monuments and narrow winding streets.\n- **Kotoko palaces and mosques** of the Logone-Chari plain, such as those at Gulfey and Kousseri.\n\n## Sources and gaps\n\nNo information on domestic roofing manufacturers was found in published sources.\n\nNational census or DHS roofing shares: published information is limited. The construction of Kotoko and Sahelian flat roofs (timber or palm beams, mats and earth layers), Sara thatching techniques and Chadian building regulations are not documented in published sources. The precise border location of individual Kotoko towns is not stated in published sources.","key_facts":[{"label":"Traditional roofs","value":"Flat earth roofs (Kotoko, Sahel), thatch (south), tents (north)"},{"label":"Early flat roofs","value":"Houlouf mud-brick houses, c. 1000-1400 CE"},{"label":"Trend","value":"Rapid spread of corrugated iron and concrete"},{"label":"Climate driver","value":"Desert heat in north, single rainy season in south"}],"regions":["Africa"],"aliases":["Chadian roofing","roofs in Chad"],"related":["sahelian-earthen-roofs","flat-roof","mud-roof","musgum-tolek","thatch","corrugated-iron","roofing-in-cameroon","roofing-in-niger","roofing-in-nigeria","roofing-in-the-central-african-republic","roofing-in-sudan","roofing-in-libya"],"sources":[{"title":"Culture of Chad","url":"https://www.everyculture.com/Bo-Co/Chad.html","publisher":"Countries and Their Cultures (everyculture.com)"},{"title":"A political history of the Kotoko city states (ca. 1000-1900)","url":"https://www.africanhistoryextra.com/p/a-political-history-of-the-kotoko","publisher":"African History Extra"},{"title":"Les transformations de l'habitation traditionnelle au Tchad : du cercle au carré","url":"https://signal.sciencespo-lyon.fr/article/908316","publisher":"Les Cahiers d'Outre-Mer (Seignobos, 1971), via Sciences Po Lyon"},{"title":"Fractals in African Architecture: Kotoko","url":"https://gauss.math.yale.edu/fractals/Panorama/Architecture/AfricanArch/Kotoko.html","publisher":"Yale University"},{"title":"Sara - Orientation","url":"https://www.everyculture.com/Africa-Middle-East/Sara-Orientation.html","publisher":"everyculture.com"},{"title":"Communal house with newly thatched roof, Chad","url":"https://lbry-web-007.amnh.org/digital/index.php/items/show/2942","publisher":"American Museum of Natural History Library"}],"company":null},{"slug":"roofing-in-chile","title":"Roofing in Chile","category":"world-roofing","type":"place","country":{"name":"Chile","iso2":"CL"},"summary":"Chilean roofing: Andean thatch, Mapuche ruka, Chiloé's shingled churches, Valparaíso's zinc; metal and fibre-cement sheets cover 68% of homes (2024).","body":"Chile stretches from the Atacama desert to the rain forests and fjords of Patagonia, and it is one of the most seismically active countries in the world. Its roofing traditions include Andean grass thatch in the north, Mapuche thatched houses and colonial clay tile in the centre, the shingle-clad wooden churches of Chiloé in the south, and the corrugated zinc of the port of Valparaíso. Today most homes are roofed with metal or fibre-cement sheets.\n\n## Climate and hazards\n\n- **Earthquakes.** A major earthquake in 2010 damaged buildings in Valparaíso, and seismic design governs national building rules.\n- **Very wet, windy south**: in March 2002 a storm brought down the tower of Chonchi church on Chiloé.\n- **Dry north** and a Mediterranean-climate centre with winter rain.\n- **Fire**: a fire in 2007 damaged buildings in Valparaíso.\n\n## Roofing history\n\n**Andean and Indigenous.** In the far north, Andean houses were roofed with grass thatch of *ichu*. In the south-centre, the Mapuche built *rukas*, round, oval or rectangular houses with a strong frame of oak (*roble*) and roofs, sometimes walls too, of bundled straw or rushes. A ruka had no windows and a single main door facing east; the central hearth was kept burning and its smoke blackened the walls.\n\n**Colonial.** In central Chile, colonial houses were built mainly of earth and straw, typically adobe walls with timber roofs covered in curved clay tiles in the Spanish tradition. Many suffered badly in earthquakes.\n\n**Chiloé.** Jesuits arrived in the Chiloé archipelago in 1608 and ran a travelling \"circular mission\"; about 70 churches were built under it, and by the end of the 19th century more than 100, of which about 60 survive. Their builders used local timber with joinery influenced by boat-building and clad the churches in hand-split wooden shingles (*tejuelas*). Sixteen churches were inscribed by UNESCO in 2000.\n\n**Valparaíso.** The port reached its peak between the 1880s and 1914, before the Panama Canal opened, and its hillside quarters were built with a wide variety of techniques. A documented house on calle Sierra, for example, has a frame of Oregon pine on stone footings and a roof of corrugated zinc sheet, with sheet-metal cladding on its north façade. The historic quarter was inscribed by UNESCO in 2003.\n\n**Mining towns.** The saltpetre works of Humberstone and Santa Laura (UNESCO 2005) and the copper-mining town of Sewell (UNESCO 2006) preserve industrial-era buildings in the desert and the Andes.\n\n## Traditional and vernacular roofs\n\n- **Ruka**: Mapuche thatched house (see ruka).\n- **Tejuela**: hand-split shingles of alerce, Guaitecas cypress, mountain cypress, mañío, coigüe and other native woods, used on roofs and walls in Chiloé and Aysén. In Aysén, shingled buildings date from about 1930 to 1995, and the trade is now close to extinction.\n- **Teja on adobe**: central valley colonial and rural houses.\n- **Ichu thatch**: Andean north.\n\n## Roofing today\n\nIn the 2024 census, INE reported that the predominant roof material of 68% of dwellings was metal or fibre-cement sheet (*planchas metálicas y de fibrocemento*), up from 66.4% in 2017. Roofs of acceptable material quality were found in 99.7% of dwellings, compared with 99% in 2002. Masonry (*albañilería*) was the most common exterior wall material, at 43%.\n\n## Codes, standards and regulation\n\nChile's seismic design standard is NCh433; a 2012 comparative review listed NCh433.Of2009 with its 2010 modification as then in force. Heritage buildings, including the Chiloé churches, are protected as National Monuments under Law 17.288 of 1970.\n\n## Notable roofs\n\n- **Churches of Chiloé** (UNESCO 2000): sixteen shingle-clad timber churches.\n- **Historic Quarter of Valparaíso** (UNESCO 2003).\n- **Humberstone and Santa Laura Saltpeter Works** (UNESCO 2005) and **Sewell Mining Town** (UNESCO 2006).\n\n## Local roofing terms\n\n- *Planchas metálicas* or *zinc*: metal roofing sheets.\n- *Fibrocemento*: fibre-cement sheet.\n- *Tejuela*: hand-split wooden shingle.\n- *Teja*: clay tile.\n- *Ruka*: Mapuche house.\n- *Minga*: communal work, used to build and maintain houses and churches on Chiloé.","key_facts":[{"label":"Dominant material today","value":"Metal or fibre-cement sheet, 68% (2024 census)"},{"label":"Traditional materials","value":"Clay tile, wooden shingles (tejuelas), straw thatch"},{"label":"Climate driver","value":"Earthquakes; wind and rain in the south"},{"label":"Seismic standard","value":"NCh433"},{"label":"Heritage roofs","value":"Churches of Chiloé, UNESCO 2000"}],"regions":["Latin America"],"aliases":["Chilean roofing","techos en Chile"],"related":["roofing-in-argentina-and-chile","churches-of-chiloe","tejuela","ruka","andean-ichu-thatch","wood-shingle","corrugated-iron","asbestos-cement-roofing","clay-roof-tile","roofing-in-argentina","roofing-in-peru","roofing-in-bolivia"],"company":null,"sources":[{"title":"Censo 2024: el 61,1% de los hogares residen en una vivienda propia","url":"https://www.ine.gob.cl/sala-de-prensa/prensa/general/noticia/2025/05/30/censo-2024-el-61-1-de-los-hogares-residen-en-una-vivienda-propia-y-el-26-2-en-una-vivienda-arrendada","publisher":"INE Chile"},{"title":"Churches of Chiloé","url":"https://whc.unesco.org/en/list/971","publisher":"UNESCO World Heritage Centre"},{"title":"Churches of Chiloé","url":"https://en.wikipedia.org/wiki/Churches_of_Chilo%C3%A9","publisher":"Wikipedia"},{"title":"Tejuela artesanal (Conserva 20, 2015)","url":"https://www.cncr.gob.cl/sites/www.cncr.gob.cl/files/2023-01/Tejuela%20Artesanal.pdf","publisher":"Centro Nacional de Conservación y Restauración (Chile)"},{"title":"Ruka (house type)","url":"https://en.wikipedia.org/wiki/Ruka_(house_type)","publisher":"Wikipedia"},{"title":"Patrón de asentamiento - Mapuche","url":"https://chileprecolombino.cl/?p=215","publisher":"Museo Chileno de Arte Precolombino"},{"title":"Historic Quarter of the Seaport City of Valparaíso","url":"https://whc.unesco.org/en/list/959","publisher":"UNESCO World Heritage Centre"},{"title":"Vivienda de calle Sierra número 14","url":"https://patrimonio.uv.cl/handle/123456789/929","publisher":"Universidad de Valparaíso, Patrimonio"},{"title":"Architecture of Chile","url":"https://en.wikipedia.org/wiki/Architecture_of_Chile","publisher":"Wikipedia"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-china","title":"Roofing in China","category":"world-roofing","type":"place","country":{"name":"China","iso2":"CN"},"summary":"Chinese roofing from the earliest known composite tiled roofs (c. 2400-2200 BCE) through ranked imperial tile roofs to concrete and steel today.","body":"China has one of the longest continuous roofing traditions in the world. Its classical architecture is a timber architecture in which the roof, heavy, tiled and often curved, is the most expressive element, and for more than two thousand years the form, colour and ornament of a roof signalled the rank of the building beneath it. Today most new buildings are reinforced concrete with flat, membrane-waterproofed roofs, and industrial buildings use large areas of profiled steel.\n\n## Climate and hazards\n\nChina spans climates from the cold, dry north and the high Tibetan Plateau to the humid subtropical south. Roofs must shed heavy monsoon rain across the south and east, carry snow in the north and north-east, and resist typhoon winds on the south-east coast. Much of the country is seismically active: the Tang-period Great Buddha Hall of Nanchan Temple in Shanxi was damaged by an earthquake in 1966, and the flexibility of traditional bracketed timber frames is widely credited with helping old halls survive earthquakes. Fire was a constant urban danger, which shaped tile roofs, firewalls and even roof ornaments believed to ward off fire.\n\n## Roofing history\n\n**Neolithic and Bronze Age.** According to a 2023 study, the oldest known composite tiled roofs come from Qiaocun, on the edge of the Loess Plateau in north-west China. Excavations recovered several thousand pieces of fired clay tile, radiocarbon dated to about 2400-2200 BCE, in the early Longshan period. A 2023 study reconstructed how semi-cylindrical cover tiles and trapezoidal pan tiles were combined on a roof, the same pan-and-cover principle that Chinese roofs still use. Tile making developed substantially in central Shaanxi during the Western Zhou dynasty (1046-771 BCE), and the technology later spread to Korea, Japan, the Russian Far East and South-East Asia.\n\n**Bracketing and the imperial roof.** Interlocking timber bracket sets (*dougong*) emerged in early forms under the Western Zhou and were widely used by the Spring and Autumn period (770-476 BCE). They reached their greatest structural complexity under the Tang and Song, carrying deep eaves out beyond the columns. China's oldest preserved timber building, the Great Buddha Hall of Nanchan Temple (782), has a hip-and-gable roof on bracket sets; the East Hall of Foguang Temple (857), a hall of seven by four bays measuring 34 by 17.7 m (110 by 58 ft), has a hipped roof and was identified by Liang Sicheng and Lin Huiyin's survey team in 1937.\n\n**Glazed tiles and standardisation.** Glazed roof tiles were in use by the Tang dynasty. In 1103 the Song court published the *Yingzao Fashi*, a 34-chapter building manual compiled by Li Jie, which set an eight-rank system for timber member sizes, gave rules for tiling and the mixing of glazes and mortars, and standardised ridge ornaments. Song tiling practice overlapped plain tiles by about 40 per cent; by the Qing dynasty the standard overlap had risen to about 70 per cent, so a cracked tile would no longer leak.\n\n**Ming and Qing.** Under the Ming (1368-1644) and Qing (1644-1911) yellow glaze became reserved for the emperor, and the Forbidden City in Beijing, built in 1406-1420, became the supreme example of a ranked roofscape. After the Song, bracket sets became smaller, more numerous and more decorative.\n\n**Modern era.** In the 20th century reinforced concrete, flat roofs and later steel and membrane systems replaced tiled timber roofs in most new building, while traditional roofs survive on temples, heritage districts and rural houses.\n\n## Traditional and vernacular roofs\n\n- **Hierarchy of forms.** Hip roofs, sloping on four sides, were reserved for the emperor, in single- or double-eaved forms; the Hall of Supreme Harmony has a double-eaved hip roof. The hip-and-gable roof (*xieshan*) ranked next and became the classic form across East Asia. Gabled roofs were the everyday form, and single-slope roofs the cheapest.\n- **Sweeping roofs** that rise at the corners were usually reserved for temples, palaces and wealthy households.\n- **Siheyuan** courtyard houses of Beijing and the north have grey-tiled gabled roofs around a central yard.\n- **Fujian tulou**, the large earthen clan houses of south-west Fujian, carry continuous tiled roofs with eaves about 2 m (6.5 ft) deep to protect rammed-earth walls from rain.\n- **Firewalls** such as the horse-head walls (*matouqiang*) of the south rise above roofs to stop embers spreading.\n- **Southern Fujian (Hokkien)** temples and mansions use upswept swallowtail ridges, a style also typical of Taiwan.\n- **Ridge ornaments.** Ridge-end beasts (*chiwen*), descended from the earlier bird-tail *chiwei* of the Han period, were believed to protect against fire. Imperial hip ridges carry lines of glazed figures whose number reflected rank.\n\n## Roofing today\n\nMost urban buildings are reinforced concrete with flat roofs waterproofed by modified-bitumen or polymer membranes and coatings, often with protective layers or tiles above. Industrial and commercial buildings use profiled steel sheet and metal panel roofs. Tiled pitched roofs remain common on rural houses and on buildings in historic styles.\n\n## Codes, standards and regulation\n\nRoofing is governed by national GB standards issued by the Ministry of Housing and Urban-Rural Development. GB 50345-2012, *Technical Code for Roof Engineering*, in force since 1 October 2012, covers membrane and coating flat roofs, tiled pitched roofs, metal panel roofs and planted roofs. GB 55030-2022 is a mandatory general code for building waterproofing.\n\n## Industry\n\nChina is a very large producer and user of roofing materials, from clay and concrete tiles to bitumen membranes and coated steel coil.\n\n## Notable roofs\n\n- **Forbidden City, Beijing** (1406-1420; UNESCO World Heritage, 1987) - yellow-glazed roofs ranked by form and ridge figures.\n- **Foguang Temple East Hall** (857) and **Nanchan Temple Great Buddha Hall** (782), Shanxi - the oldest surviving timber roofs in China; Foguang is part of the Mount Wutai World Heritage site (2009).\n- **Temple of Heaven, Beijing** - blue-glazed roofs symbolising the sky.\n- **Fujian tulou** (UNESCO, 2008) - 46 earthen buildings with wide-eaved ring and square roofs.\n\n## Local roofing terms\n\n- *dougong* (斗拱) - bracket set of blocks and arms\n- *xieshan* (歇山) - hip-and-gable roof\n- *liuli wa* (琉璃瓦) - glazed roof tile\n- *chiwen* (蚩吻) / *chiwei* (鸱尾) - ridge-end ornament\n- *matouqiang* - horse-head firewall\n\n## Sources and gaps\n\nNational statistics on roofing materials and manufacturer data: published information is limited.","key_facts":[{"label":"Earliest tiled roofs","value":"Qiaocun, c. 2400-2200 BCE"},{"label":"Traditional structure","value":"Timber frame with dougong brackets"},{"label":"Building manual","value":"Yingzao Fashi (1103), 34 chapters"},{"label":"Oldest timber roof","value":"Nanchan Temple Great Buddha Hall, 782"},{"label":"Imperial roof","value":"Hip roof, yellow glazed tiles"},{"label":"Building code","value":"GB 50345-2012; GB 55030-2022"}],"regions":["East Asia"],"aliases":["Chinese roofing","roofing in mainland China"],"related":["earliest-fired-clay-roof-tiles","chinese-glazed-roof-tiles","forbidden-city-roofs","chinese-imperial-roof-figures","siheyuan-roof","fujian-tulou-roofs","dougong","yingzao-fashi","chiwen","swallowtail-roof","irimoya","pagoda-roof","china-roofing-codes","clay-roof-tile","glazed-roof-tile","flat-roof","modified-bitumen-roofing","roofing-in-hong-kong","roofing-in-taiwan","roofing-in-mongolia","roofing-in-north-korea","roofing-in-japan","hanok-roof"],"company":null,"sources":[{"title":"Chinese architecture","url":"https://en.wikipedia.org/wiki/Chinese_architecture","publisher":"Wikipedia"},{"title":"Reconstructing the earliest composite-tiled roofs (Qiaocun)","url":"https://www.nature.com/articles/s41598-023-35299-x","publisher":"Scientific Reports"},{"title":"Researchers reconstruct earliest composite-tiled roofs","url":"https://phys.org/news/2023-07-reconstruct-earliest-composite-tiled-roofs.html","publisher":"Phys.org"},{"title":"Yingzao Fashi","url":"https://en.wikipedia.org/wiki/Yingzao_Fashi","publisher":"Wikipedia"},{"title":"Dougong","url":"https://en.wikipedia.org/wiki/Dougong","publisher":"Wikipedia"},{"title":"Nanchan Temple","url":"https://en.wikipedia.org/wiki/Nanchan_Temple","publisher":"Wikipedia"},{"title":"Foguang Temple","url":"https://en.wikipedia.org/wiki/Foguang_Temple","publisher":"Wikipedia"},{"title":"Chinese glazed roof tile","url":"https://en.wikipedia.org/wiki/Chinese_glazed_roof_tile","publisher":"Wikipedia"},{"title":"Chiwen","url":"https://en.wikipedia.org/wiki/Chiwen","publisher":"Wikipedia"},{"title":"GB 50345-2012 Technical code for roof engineering","url":"https://www.chinesestandard.net/PDF.aspx/GB50345-2012","publisher":"Chinese Standard"},{"title":"GB 55030-2022 General code for building waterproofing","url":"https://www.chinesestandard.net/PDF.aspx/GB55030-2022","publisher":"Chinese Standard"},{"title":"Imperial Palaces of the Ming and Qing Dynasties in Beijing and Shenyang","url":"https://whc.unesco.org/en/list/439","publisher":"UNESCO World Heritage Centre"},{"title":"Fujian Tulou","url":"https://whc.unesco.org/en/list/1113","publisher":"UNESCO World Heritage Centre"},{"title":"Irimoya","url":"https://en.wikipedia.org/wiki/Irimoya","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Fujian tulou","url":"https://en.wikipedia.org/wiki/Fujian_tulou","publisher":"Wikipedia"}]},{"slug":"roofing-in-colombia","title":"Roofing in Colombia","category":"world-roofing","type":"place","country":{"name":"Colombia","iso2":"CO"},"summary":"Colombian roofing: Amazonian palm-thatched malocas, colonial clay tile in Cartagena, bahareque coffee-region houses, and fibre-cement 'eternit' and zinc today.","body":"Colombia has Caribbean and Pacific coasts, three Andean ranges and a large share of the Amazon basin, so its roofs vary from palm-thatched communal houses in the rainforest to clay tile in the colonial cities and coffee towns and fibre-cement and metal sheet in modern housing. The brand name *eternit* is used as a generic word for fibre-cement sheet.\n\n## Climate and hazards\n\n- **Earthquakes**, the main structural concern of the national building regulations.\n- **Very heavy rain** on the Pacific coast and in the Amazon.\n- **Heat and humidity** on the Caribbean coast.\n\n## Roofing history\n\n**Indigenous.** In the northwest Amazon, Eastern Tukanoan peoples such as the Barasana, Makuna, Tanimuka and Desana built *malocas*, large communal houses shared by several related families, each with its own hearth. Their roofs are thatched with palm leaves. A 2020 study with five Indigenous communities near Leticia described one of the most prized thatches of the Colombian Amazon: leaves of the palm *Lepidocaryum tenue* braided along split stems of *Socratea exorrhiza*. Thatching a house of 48 m² (517 sq ft) needed the palms of roughly 1 ha (2.5 acres) of forest.\n\n**Colonial.** Spanish towns were built with masonry, adobe and clay tile roofs. At Cartagena, the Caribbean port whose fortifications were begun in 1586 and extended in the 18th century, the San Pedro district has palaces in the Andalusian style, and the San Diego and Getsemaní quarters housed merchants, craftsmen and artisans. Cartagena was inscribed by UNESCO in 1984 and the river port of Santa Cruz de Mompox in 1995.\n\n**19th-century coffee frontier.** Settlers from Antioquia moving south into the central Andes in the 19th century developed a building tradition based on *bahareque*, a flexible system of timber or bamboo frames with earth and cane infill. UNESCO's description of the Coffee Cultural Landscape notes that more than half of the walls there are still built this way, covered with a layer of bamboo, with clay tile roofs and sliding roofs adapted for drying coffee.\n\n**20th century.** Fibre-cement corrugated sheet and corrugated zinc spread widely. Colombia's 1973 census already listed \"zinc or synthetic ('eternit') tile\" as a roof category alongside concrete slab, clay tile, and straw, grass or palm.\n\n## Traditional and vernacular roofs\n\n- **Maloca**: Amazonian communal house with palm thatch (see maloca).\n- **Bahareque house** of the coffee region with clay tile roof; some have sliding roof sections for drying coffee beans.\n- **Teja de barro** on adobe and masonry in colonial towns.\n\n## Roofing today\n\nFibre-cement sheet, metal sheet, clay tile and concrete slabs are all widely used.\n\n## Codes, standards and regulation\n\nThe national seismic building regulation is NSR-10 (2010), listed as in force in a 2012 comparative review of Latin American codes.\n\n## Notable roofs\n\n- **Cartagena** (UNESCO 1984): colonial houses with balconies and Andalusian-style palaces within extensive fortifications.\n- **Santa Cruz de Mompox** (UNESCO 1995).\n- **Coffee Cultural Landscape of Colombia** (UNESCO 2011): bahareque houses with clay tile and sliding drying roofs.\n\n## Local roofing terms\n\n- *Teja de barro*: clay tile.\n- *Eternit*: generic term for fibre-cement roofing sheet.\n- *Zinc*: corrugated metal sheet.\n- *Bahareque*: timber or bamboo frame with earth infill.\n- *Losa*: concrete slab.\n- *Maloca*: Amazonian communal house.","key_facts":[{"label":"Traditional materials","value":"Palm thatch, clay tile"},{"label":"Generic term for fibre-cement","value":"Eternit"},{"label":"Building code","value":"NSR-10 (2010)"},{"label":"Climate driver","value":"Earthquakes, heavy rain"},{"label":"Heritage","value":"Cartagena (UNESCO 1984)"}],"regions":["Latin America"],"aliases":["Colombian roofing","techos en Colombia"],"related":["maloca","palm-thatch","clay-roof-tile","spanish-tile","eternit","asbestos-cement-roofing","corrugated-iron","roofing-in-venezuela","roofing-in-ecuador","roofing-in-panama","roofing-in-peru","roofing-in-brazil"],"company":null,"sources":[{"title":"Maloca","url":"https://en.wikipedia.org/wiki/Maloca","publisher":"Wikipedia"},{"title":"Del mito de la invisibilidad femenina a la complementariedad (Amazonia colombiana)","url":"https://core.ac.uk/download/427651266.pdf","publisher":"Universidad Nacional de Colombia, Sede Amazonía"},{"title":"Management of Lepidocaryum tenue and Socratea exorrhiza, two Amazonian palms used for thatching","url":"https://www.ethnobotanyjournal.org/index.php/era/article/view/1583","publisher":"Ethnobotany Research and Applications"},{"title":"Port, Fortresses and Group of Monuments, Cartagena","url":"https://whc.unesco.org/en/list/285","publisher":"UNESCO World Heritage Centre"},{"title":"Coffee Cultural Landscape of Colombia","url":"https://whc.unesco.org/en/list/1121","publisher":"UNESCO World Heritage Centre"},{"title":"Colombia 1973 census (IPUMS): roof material","url":"https://microdata.worldbank.org/catalog/487/variable/CO1973A_ROOF","publisher":"World Bank Microdata Library / DANE"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"}]},{"slug":"roofing-in-comoros","title":"Roofing in Comoros","category":"world-roofing","type":"place","country":{"name":"Comoros","iso2":"KM"},"summary":"Roofing in the Comoros is poorly documented; the islands' historic Swahili stone medinas, inscribed by UNESCO in 2026, are the best-recorded buildings.","body":"The Comoros is a volcanic archipelago between Madagascar and Mozambique, with Grande Comore (Ngazidja), Anjouan (Ndzuani) and Moheli (Mwali). Its historic towns belong to the Swahili building tradition of the East African coast, with stone palaces, mosques and fortifications.\n\n## Climate and hazards\n\nThe islands lie in the cyclone-prone south-west Indian Ocean.\n\n## Roofing history\n\nThe historic medinas of the Comoros date from the 12th to the 16th centuries and represent a distinct local form of Swahili civilisation, with royal palaces, religious buildings, fortifications and public squares along narrow streets. The sultanates that built them governed from about the 14th to the 19th century. Moroni, on Grande Comore, has a medina with an old Friday Mosque. At Iconi, only old walls of local stone remain of the old palace, and at Ntsoudjini the town wall survives in good condition though its gates are gone.\n\nThe medinas were placed on the national Tentative List in 2007 and were inscribed on the World Heritage List in 2026, at the 48th session of the World Heritage Committee in Busan, as The Medinas of the Historic Sultanates of the Comoros, under criteria (iii) and (iv). It is the country's first World Heritage property, a serial site of six historic cities on Ngazidja (Grande Comore) and Ndzuwani (Anjouan), among them the medinas of Moroni, Itsandra and Iconi.\n\n## Traditional and vernacular roofs\n\nThe stone architecture of the medinas follows Swahili practice; see Roofing in East Africa for the related coral-stone and palm-thatch traditions of the coast.\n\n## Notable roofs\n\n- **The Medinas of the Historic Sultanates of the Comoros** (UNESCO 2026): six historic cities on Ngazidja and Ndzuwani, including Moroni, Itsandra and Iconi.\n- **Ujumbe palace**, Anjouan: a sultan's palace that has been the subject of restoration work.\n\n## Sources and gaps\n\nEveryday roofs is very limited. Published information on specific roof hazard data: published information is limited. Descriptions of Comorian vernacular roofs were not found in published sources. No national roofing standard was identified. No information on roofing manufacturers was found in published sources. No Shikomori roofing terms were found.\n\nRoof materials of Comorian houses (stone, palm or metal), census or survey data, building rules and the names of all six inscribed cities: published information is limited.","key_facts":[{"label":"Heritage","value":"Medinas of the historic Sultanates (UNESCO 2026)"},{"label":"Building tradition","value":"Swahili stone architecture"}],"regions":["Africa"],"aliases":["Comorian roofing"],"related":["roofing-in-east-africa","palm-thatch","flat-roof","roofing-in-madagascar","roofing-in-mozambique","roofing-in-tanzania","roofing-in-seychelles","roofing-in-mauritius"],"company":null,"sources":[{"title":"Les medinas des Sultanats historiques des Comores","url":"https://www.worldheritagesite.org/tentative/id/5109","publisher":"WorldHeritageSite.org"},{"title":"Six Comoros medinas earn UNESCO heritage status","url":"https://africa.com/top-10-news/six-comoros-medinas-earn-unesco-heritage-status","publisher":"Africa.com"},{"title":"Restoring of the Sultan Palace Ujumbe","url":"https://www.aliph-foundation.org/en/projects/restoring-of-the-sultan-palace-ujumbe","publisher":"ALIPH Foundation"},{"title":"Decision 48 COM 8B.13: The Medinas of the Historic Sultanates of the Comoros","url":"https://whc.unesco.org/en/decisions/9166","publisher":"UNESCO World Heritage Centre"},{"title":"Six ancient medinas in Comoros join UNESCO's World Heritage list","url":"https://www.africanews.com/2026/07/25/six-ancient-medinas-in-comoros-join-unescos-world-heritage-list/","publisher":"Africanews"}]},{"slug":"roofing-in-costa-rica","title":"Roofing in Costa Rica","category":"world-roofing","type":"place","country":{"name":"Costa Rica","iso2":"CR"},"summary":"Costa Rican roofing: metal sheet on lightweight frames dominates under a seismic code first written after the 1972-73 earthquakes and revised in 2025.","body":"Costa Rica's houses are dominated by light roofs of metal sheet on timber or steel framing, a choice that suits its tropical rains and its high earthquake risk. The country is known in Latin America for its seismic code, first drafted in the 1970s and revised regularly since.\n\n## Climate and hazards\n\n- **Earthquakes.** Costa Rica has a high earthquake risk. The Managua earthquake of 1972 in neighbouring Nicaragua and the Arenal earthquake of 1973 prompted the country to write its first seismic code.\n- **Wind.** The 2025 edition of the seismic code considered strong-wind loads on structures for the first time.\n- **Heavy tropical rain**, especially on the Caribbean slope, and high humidity.\n\n## Roofing history\n\nThe pre-Columbian chiefdom settlements of the Diquís delta, known for their stone spheres, were inscribed by UNESCO in 2014. Colonial houses in the Central Valley were built of adobe and *bahareque* with clay tile roofs. Metal sheet on light timber or steel framing has since become the usual roof.\n\n## Traditional and vernacular roofs\n\n- **Teja on adobe or bahareque**: colonial Central Valley houses.\n- **Natural-fibre roofs** of bamboo, cane or *chonta* palm, still recorded as a separate category in household surveys.\n\n## Roofing today\n\nINEC's National Household Survey (ENAHO) classifies roofs as metal or zinc sheet (*lámina de metal o zinc*), fibre-cement, *entrepiso* (a floor slab above), natural fibres (bamboo, cane, *chonta*), waste materials and other.\n\n## Codes, standards and regulation\n\nThe *Código Sísmico de Costa Rica* is drafted and updated by the Colegio Federado de Ingenieros y de Arquitectos (CFIA), which has that role under law. After a first edition in the 1970s, it was revised in 1986, 2002, 2010 and 2014 (CSCR-2010/14), and renewed again in 2025. The code is organised around seismic hazard and structural vulnerability, and each edition adds new materials and building methods. The 2025 edition expanded hazard information for the central Pacific region and, for the first time, addressed strong-wind hazard.\n\n## Local roofing terms\n\n- *Lámina de zinc* or simply *zinc*: corrugated metal roofing.\n- *Fibrocemento*: fibre-cement sheet.\n- *Entrepiso*: an upper floor or slab serving as the roof of the storey below.\n- *Chonta*: a palm used for natural-fibre roofs.","key_facts":[{"label":"Climate drivers","value":"Earthquakes, heavy rain, wind"},{"label":"Building code","value":"Código Sísmico de Costa Rica (CFIA)"},{"label":"Code editions","value":"1970s, 1986, 2002, 2010, 2014, 2025"}],"regions":["Latin America"],"aliases":["Costa Rican roofing"],"related":["corrugated-iron","clay-roof-tile","roofing-in-nicaragua","roofing-in-panama"],"company":null,"sources":[{"title":"¿Qué dice el Código Sísmico que protege a Costa Rica de tragedias como la de Venezuela?","url":"https://crhoy.com/nacionales/que-dice-el-codigo-sismico-que-protege-a-costa-rica-de-tragedias-como-la-de-venezuela","publisher":"CR Hoy"},{"title":"Código Sísmico de Costa Rica 2010, revisión 2014 (CSCR-2010/14)","url":"https://iisee.kenken.go.jp/worldlist/12_CostaRica/CSCR2010-R14.pdf","publisher":"CFIA (copy hosted by IISEE)"},{"title":"Costa Rica ENAHO 2015: Material del techo de la vivienda","url":"https://catalog.ihsn.org/catalog/7036/variable/F2/V572?name=V4","publisher":"IHSN Survey Catalog / INEC Costa Rica"},{"title":"List of World Heritage Sites in Central America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_Central_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-cote-divoire","title":"Roofing in Côte d'Ivoire","type":"place","country":{"name":"Côte d'Ivoire","iso2":"CI"},"summary":"Côte d'Ivoire roofs are overwhelmingly metal sheet (tôle) over concrete-block houses; its earthen Sudanese-style mosques are its main heritage roofs.","body":"Côte d'Ivoire runs from a humid lagoon coast and rainforest in the south to savanna in the north. Traditional buildings used earth, timber and thatch; today the country is roofed almost entirely in metal sheet, and concrete is the standard building material in Abidjan and other cities. Its best-known historic roofs belong to the earthen Sudanese-style mosques of the north.\n\n## Climate and hazards\n\nThe south is hot and very humid, with two rainy seasons; the north has a single rainy season and harmattan dust. Floods and landslides killed 45 people in the country between May 2017 and June 2018. The heat of concrete-and-metal buildings drives heavy use of air conditioning; an estimate reported by the French outlet Reporterre puts about 55% of energy use in Côte d'Ivoire and neighbouring countries into cooling homes.\n\n## Roofing history\n\nThe Sudano-Sahelian building style that originated around Djenné spread south into what is now northern Côte d'Ivoire, mainly from the 15th century. Several hundred earthen mosques in this style existed at the start of the 20th century; about twenty survive, most built between the 17th and 19th centuries. The Great Mosque of Kong was destroyed by Samory Touré in 1897 and rebuilt by its community.\n\nOn the coast, Grand-Bassam was developed as a colonial town from the 1880s to the 1950s, with houses built around galleries, verandas and gardens designed for the tropical climate, alongside the vernacular houses of the N'zima fishing village.\n\n## Traditional and vernacular roofs\n\n- **Sudanese-style mosques**: earth (cob and adobe) walls with projecting timber frameworks, buttresses topped with pottery or ostrich eggs, and truncated-pyramid minarets. The southern examples have lower, sturdier buttresses suited to a wetter climate.\n- **Thatch**: grass and palm-leaf thatch on rural houses, now a small minority.\n- **Earth villages**: Ivorian architects cite village earth houses as models of climate-suited building.\n\n## Roofing today\n\nIn the 2014 Afrobarometer survey of Côte d'Ivoire, interviewers recorded:\n\n| Main roof material | Share of respondents (2014) |\n|---|---|\n| Metal, tin or zinc | 88.2% |\n| Thatch or grass | 5.8% |\n| Tiles | 2.0% |\n| Concrete | 1.5% |\n\nAfrobarometer surveys interview about 1,200 adults per country; these figures are unweighted counts in the survey sample. The 2016 Multiple Indicator Cluster Survey classifies roofs in categories including thatch/palm leaf, grass, mat, wood, *métal/tôle*, tiles and cement.\n\nConcrete, modelled on European building, is the dominant construction system, and the Ministry of Housing has stated that about 80% of construction materials used in the country are imported. Firms such as the Ivorian practice Koffi & Diabaté have promoted \"bio-architecture\" using local materials, earth walls and natural ventilation as an alternative.\n\n## Codes, standards and regulation\n\nThe eight Sudanese-style mosques were placed on the National Cultural Heritage List by Decree No. 2020-121 of 29 January 2020, and each has a local management committee supervised by the Office Ivoirien du Patrimoine Culturel (OIPC).\n\n## Notable roofs\n\n- **Sudanese style mosques in northern Côte d'Ivoire**: eight mosques at Tengréla, Kouto, Sorobango, Samatiguila, Nambira, Kong (two mosques) and Kaouara, a World Heritage site.\n- **Historic Town of Grand-Bassam**: colonial gallery and veranda houses and the N'zima village, a World Heritage site.\n\n## Local roofing terms\n\n- **tôle** (French): metal roof sheet.\n- **dalle** (French): concrete roof slab.\n\n## Sources and gaps\n\nSurvey shares are unweighted. Published sources on the many regional vernacular traditions (for example Senufo, Baoulé and Lobi houses), on regulation and on industry: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal sheet, 88.2% (Afrobarometer 2014 file)"},{"label":"Construction system","value":"Concrete; about 80% of materials imported (Ministry of Housing)"},{"label":"Traditional materials","value":"Earth, timber, thatch"},{"label":"Climate driver","value":"Humid tropical rain, flooding, heat"},{"label":"Heritage roofs","value":"Sudanese-style earthen mosques"}],"regions":["Africa"],"aliases":["Ivorian roofing","roofing in Ivory Coast","roofing in Cote d'Ivoire"],"related":["roofing-in-west-africa","sahelian-earthen-roofs","djenne-earthen-architecture","corrugated-iron","thatch","flat-roof","roofing-in-ghana","roofing-in-liberia","roofing-in-guinea","roofing-in-mali","roofing-in-burkina-faso"],"sources":[{"title":"Afrobarometer Survey 2014, Round 6, Côte d'Ivoire: roof of respondent's home","url":"https://catalog.ihsn.org/catalog/8906/variable/F2/V653?name=Q105","publisher":"IHSN / Afrobarometer"},{"title":"MICS 2016 Côte d'Ivoire: matériau principal du toit (HC4)","url":"https://microdata.worldbank.org/catalog/3423/variable/F2/V149?name=HC4","publisher":"World Bank Microdata Library"},{"title":"Sudanese style mosques in northern Côte d'Ivoire","url":"https://whc.unesco.org/en/list/1648/","publisher":"UNESCO World Heritage Centre"},{"title":"Historic Town of Grand-Bassam","url":"https://whc.unesco.org/en/list/1322/","publisher":"UNESCO World Heritage Centre"},{"title":"En Côte d'Ivoire, la bio-architecture, solution face au tout béton","url":"https://reporterre.net/En-Cote-d-Ivoire-la-bio-architecture-solution-face-au-tout-beton","publisher":"Reporterre"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-croatia","title":"Roofing in Croatia","category":"world-roofing","type":"place","country":{"name":"Croatia","iso2":"HR"},"regions":["Europe"],"company":null,"summary":"How Croatia roofs its buildings: stone-slab roofs and dry-stone bunje on the Dalmatian coast, clay tile inland, and the all-stone vault of Šibenik Cathedral.","aliases":["Croatian roofing","Krovovi u Hrvatskoj"],"body":"Croatia's long Adriatic coast and islands developed a stone roofing tradition: houses roofed with thin limestone slabs and field shelters built entirely of dry stone. Inland, in the Pannonian north, building traditions are closer to those of central Europe. The country also holds one of Europe's most unusual roofs, the stone vault and dome of Šibenik Cathedral.\n\n## Climate and hazards\n\nCoastal roofs face hot summers and strong winds such as the *bura* (bora) and *jugo*; shepherds on Dugi Otok built special stone shelters for these winds. Croatia is seismic. On 22 March 2020 a magnitude 5.3-5.5 earthquake struck Zagreb, damaging 26,197 buildings, of which 1,900 became unusable; part of the Croatian Parliament's roof collapsed and one spire of Zagreb Cathedral broke off. A further magnitude 6.4 earthquake struck near Petrinja in December 2020.\n\n## Roofing history\n\nRoman Dalmatia had domed buildings: Diocletian's Palace at Split, built around AD 300, includes domes, mausoleums and vaulted cellars. The 6th-century Euphrasian Basilica at Poreč is one of the few surviving early Byzantine basilicas in western Europe. From the 11th century, Romanesque churches in the coastal cities were usually three-aisled stone basilicas with timber roofs; the Franciscan church in Pula (1285) has a timber rib-vaulted ceiling.\n\nThe Cathedral of St James in Šibenik (1431-1535) is built entirely of stone, from the wall footings through the vaults to the dome, using construction techniques UNESCO describes as unique; its architects included Juraj Dalmatinac (Georgius Mathei Dalmaticus) and Nikola Firentinac (Niccolò di Giovanni Fiorentino), and it was consecrated in 1555. Zagreb Cathedral received a Baroque roof in the 18th century, and its 19th-century neo-Gothic restoration added glazed roof tiles.\n\nIn the 20th century, Croatia was part of Yugoslavia, whose first seismic building code was drafted in 1964 after the Skopje earthquake.\n\n## Traditional and vernacular roofs\n\n- **Stone-slab roofs (*kamene ploče*):** on Dugi Otok, early houses were of dry-laid stone with roofs of natural stone slabs that needed little shaping. In Bol, on Brač, houses were roofed with thin slabs quarried at a site called Petrore on the neighbouring island of Hvar and brought over by donkey and boat; the slabs were lighter than wall stone. Modern roof tiles ended their use there, and few examples survive, but interest in stone roofs is reviving.\n- **Bunje:** small dry-stone shelters roofed with slabs, some round, used for shelter from rain.\n- **Kućeri:** double-walled dry-stone shelters on hills, built with the entrance away from the wind.\n\n## Codes, standards and regulation\n\nAs an EU member, Croatia applies the Eurocodes.\n\n## Notable roofs\n\n- Cathedral of St James, Šibenik (UNESCO): all-stone vaults and dome\n- Diocletian's Palace, Split\n- Zagreb Cathedral roof with glazed tiles\n- Stone-slab houses of Bol and Dugi Otok\n\n## Local roofing terms\n\n- *kamene ploče* - stone slabs\n- *bunja* (pl. *bunje*) - dry-stone hut roofed with slabs\n- *kućer* (pl. *kućeri*) - wind shelter of dry stone\n- *petrade* - old Brač word for quarries\n- *konoba* - cellar or ground-floor store under a house\n## Sources and gaps\n\nData on current roofing materials, national regulations and manufacturer information: published information is limited.","key_facts":[{"label":"Coastal tradition","value":"Limestone slab roofs; dry-stone bunje"},{"label":"Landmark roof","value":"Šibenik Cathedral, all-stone vault and dome (1431-1535)"},{"label":"Seismic hazard","value":"Zagreb 2020 (M5.3-5.5) and Petrinja 2020 (M6.4)"},{"label":"Structural design","value":"Eurocodes (EU member)"}],"related":["dalmatian-stone-slab-roof","stone-slate","trulli-of-alberobello","clay-roof-tile","roofing-in-slovenia","roofing-in-bosnia-and-herzegovina","roofing-in-italy","roofing-in-montenegro","roofing-in-hungary"],"sources":[{"title":"Construction","url":"https://pp-telascica.hr/construction/?lang=en","publisher":"Telašćica Nature Park"},{"title":"From which stone was Bol on the island of Brač built?","url":"https://www.croatiaweek.com/?p=113553","publisher":"Croatia Week"},{"title":"The Cathedral of St James in Šibenik","url":"https://whc.unesco.org/en/list/963","publisher":"UNESCO World Heritage Centre"},{"title":"Architecture of Croatia","url":"https://en.wikipedia.org/wiki/Architecture_of_Croatia","publisher":"Wikipedia"},{"title":"2020 Zagreb earthquake","url":"https://en.wikipedia.org/wiki/2020_Zagreb_earthquake","publisher":"Wikipedia"},{"title":"1963 Skopje earthquake","url":"https://en.wikipedia.org/wiki/1963_Skopje_earthquake","publisher":"Wikipedia"},{"title":"EN Eurocodes","url":"https://eurocodes.jrc.ec.europa.eu/","publisher":"European Commission Joint Research Centre"}]},{"slug":"roofing-in-cuba","title":"Roofing in Cuba","category":"world-roofing","type":"place","country":{"name":"Cuba","iso2":"CU"},"summary":"Cuban roofing: the palm-thatched Taíno bohío, colonial tile, and today a near even split between concrete roofs and light sheet roofs, repeatedly tested by hurricanes.","body":"Cuba is the largest island in the Caribbean, with a housing stock of about 3.8 million dwellings shaped by Taíno palm-thatch building, Spanish colonial masonry and, since 1959, state housing programmes using precast concrete and sheet roofing. Hurricanes are the main threat to roofs.\n\n## Climate and hazards\n\nCuba has a hot, humid tropical climate with a wet season and frequent hurricanes. Government figures on weather damage show how exposed roofs are: across hurricanes up to and including Irma, the Ministry of Construction (MICONS) recorded 17,789 dwellings that lost their whole roof and 90,024 that lost part of it. Irma alone accounted for 14,964 total and 73,443 partial roof losses, and Sandy for 1,192 total and 13,473 partial losses. Overall, 209,861 dwellings were affected by weather events in the period covered, including 60,975 total collapses.\n\n## Roofing history\n\n**Taíno.** Before the Spanish conquest, the Taíno lived in villages (*yucayeques*) of large thatched houses built of wooden poles, woven straw and palm leaves. Ordinary family houses (*bohíos*) were described as large circular buildings around a central plaza; the chief's house (*caney*) was rectangular. Cuban accounts describe early bohíos as round with conical roofs, later giving way to rectangular plans under gabled roofs, with walls of reeds and palm leaves tied with vines and roofs of woven royal palm fronds (see bohio).\n\n**Colonial era.** The rectangular bohío influenced rural colonial building, and the type remained common in the countryside into the late 19th century.\n\n**After 1959.** MICONS states that before 1959 there were about 200,000 bohíos and huts (*chozas*) in Cuba and that there are now 115,000 fewer. Housing programmes since then relied heavily on precast concrete; Spiroll hollow-core slab capacity of 334.6 km per year is used mainly for roofs and intermediate floors.\n\n## Traditional and vernacular roofs\n\n- **Bohío**: palm-thatched rural house, still most concentrated in eastern Cuba, especially around Baracoa, where it has been revived because it is cheap to build and suits a humid, cyclone-prone island.\n- **Caney**: the larger rectangular Taíno house of the chief; the word is also used for large thatched shelters.\n\n## Roofing today\n\nUpdated census figures to June 2017 counted 3,824,861 dwellings. MICONS classes 1,956,329 (51%) as Typology I, its most durable category, and 1,868,532 (49%) as Typologies II-V, which have light roofs (*cubiertas ligeras*). In 2017, 61% of dwellings were rated in good condition and 39% regular or poor. MICONS projected 10-year demand for about 11.7 million m² (126 million ft²) of zinc (galvanised) roofing sheet and 4.7 million m² (50 million ft²) of asbestos-cement roofing sheet.\n\n## Codes, standards and regulation\n\nHousing construction policy is set by the Ministry of Construction (MICONS).\n\n## Industry\n\nRoofing materials are largely produced or imported through state enterprises; the MICONS housing policy includes investment in fibre-cement and waterproofing production.\n\n## Local roofing terms\n\n- *Bohío*: thatched rural house. *Caney*: large rectangular thatched house.\n- *Cubierta ligera*: light roof (sheet metal or fibre-cement).\n- *Techos totales / parciales*: MICONS damage categories for total and partial roof loss.\n\n## Sources and gaps\n\nNo breakdown of roofs by individual material from the 2012 census was found in published sources. Building code details and individual heritage roofs: published information is limited.","key_facts":[{"label":"Dwellings","value":"3,824,861 (June 2017)"},{"label":"Light-roofed dwellings","value":"49% (Typologies II-V)"},{"label":"Traditional roof","value":"Palm-thatched bohío"},{"label":"Climate driver","value":"Hurricanes"},{"label":"Irma roof losses","value":"14,964 total, 73,443 partial"}],"regions":["Latin America","North America"],"aliases":["Cuban roofing"],"related":["bohio","palm-thatch","thatch","corrugated-iron","corrugated-fibre-cement-sheet","flat-roof","clay-roof-tile","roofing-in-the-caribbean","hurricane-roof-damage","roofing-in-the-dominican-republic","roofing-in-mexico"],"company":null,"sources":[{"title":"Política de la Vivienda en Cuba","url":"https://oncubanews.com/wp-content/uploads/2023/03/Micons_-Politica-de-la-Vivienda-1.pdf","publisher":"Ministerio de la Construcción de Cuba (MICONS), via OnCuba News"},{"title":"Taíno","url":"https://en.wikipedia.org/wiki/Ta%C3%ADno","publisher":"Wikipedia"},{"title":"The Taíno dwelling (la vivienda taína)","url":"https://en.absolutviajes.com/cuba/la-vivienda-taina/","publisher":"Absolut Viajes"}]},{"slug":"roofing-in-cyprus","title":"Roofing in Cyprus","category":"world-roofing","type":"place","country":{"name":"Cyprus","iso2":"CY"},"regions":["Europe"],"company":null,"summary":"How Cyprus roofs its buildings: Neolithic flat roofs, earth-on-reed roofs in the lowlands, pitched tiled roofs in the Troodos mountains, and modern concrete.","aliases":["Cypriot roofing","Roofs of Cyprus"],"body":"Cyprus has one of the longest documented roofing records in the Mediterranean, beginning with Neolithic flat-roofed round houses. Traditional practice divides roughly between flatter roofs on the plains and coast and steeper pitched roofs in the Troodos mountains, where some of the island's best-known historic roofs shelter Byzantine painted churches.\n\n## Climate and hazards\n\nThe island has hot, dry summers and mild, wetter winters, with snow in the Troodos mountains. Traditional builders used pitched roofs in the mountains to shed snow and flatter roofs on the plains and near the sea. Studies of the coastal town of Kyrenia found that dense old quarters were warmer than the countryside at night but cooler by day, because buildings shade one another in narrow streets.\n\n## Roofing history\n\n**Neolithic.** At Choirokoitia, a UNESCO World Heritage site occupied from the 7th millennium BC, excavations revealed circular houses of mudbrick and stone with flat roofs, grouped around small courtyards. Archaeologists reconstruct such roofs as wooden beams covered with branches, reeds and brushwood, sealed with a layer of clay against rain.\n\n**Byzantine and medieval.** The Troodos mountains hold a group of small Byzantine churches and monasteries with exceptional wall paintings from the 11th century onward. Their architecture is distinctive: steep-pitched wooden roofs covered with flat hooked tiles, which in some cases form a second roof over masonry domes and vaults. Among them is St Nicholas of the Roof (Agios Nikolaos tis Stegis).\n\n**Venetian and Ottoman.** Venetian rule (1489-1571) and Ottoman rule (1571-1878) influenced town houses. Ottoman-period houses often had an *iliakos*, a covered veranda overlooking the courtyard, and urban roofs were carried on cypress beams.\n\n## Traditional and vernacular roofs\n\n- **Flat roofs:** flatter roofs were usual on the plains and near the coast. The basic build-up reconstructed for early Cypriot houses, timber beams covered with branches, reeds or brushwood under a layer of clay, is the classic Mediterranean earth roof.\n- **Mountain pitched roofs:** steeper timber roofs with tile coverings in the Troodos villages, where houses are built of volcanic stone in brown, grey and ochre tones (Kakopetria, Kalopanayiotis), while Lefkara and Omodos use white limestone.\n- **Protective church roofs:** steep timber roofs with flat hooked tiles over Byzantine domes, as on the Painted Churches of Troodos.\n\n## Codes, standards and regulation\n\nAs an EU member, Cyprus applies the Eurocodes for structural design.\n\n## Notable roofs\n\n- **Choirokoitia** (UNESCO): Neolithic flat-roofed round houses.\n- **Painted Churches in the Troodos Region** (UNESCO): ten churches with steep timber and tile roofs, including St Nicholas of the Roof and Panagia Phorbiotissa of Nikitari.\n\n## Local roofing terms\n\n- *iliakos* - covered veranda of a traditional house\n- *tis Stegis* - \"of the roof\", in the name of St Nicholas of the Roof\n\n## Sources and gaps\n\nData on current roofing materials, census figures, national regulations, information on Cypriot roofing manufacturers and detailed technical descriptions of Cypriot earth roofs and modern practice were not found in published sources.","key_facts":[{"label":"Earliest roofs","value":"Neolithic flat roofs, Choirokoitia"},{"label":"Lowland tradition","value":"Flat earth-on-reed roofs"},{"label":"Mountain tradition","value":"Steep timber roofs with flat hooked tiles"},{"label":"Structural design","value":"Eurocodes (EU member)"}],"related":["troodos-painted-church-roofs","flat-roof","mud-roof","clay-roof-tile","roofing-in-greece","roofing-in-turkey","roofing-in-lebanon","roofing-in-malta"],"sources":[{"title":"Choirokoitia","url":"https://whc.unesco.org/en/list/848","publisher":"UNESCO World Heritage Centre"},{"title":"Painted Churches in the Troodos Region","url":"https://whc.unesco.org/en/list/351","publisher":"UNESCO World Heritage Centre"},{"title":"The traditional architecture of Cyprus and its features","url":"https://dom.com.cy/en/live/blogs/the-traditional-architecture-of-cyprus-and-its-features/","publisher":"DOM Cyprus"},{"title":"Sustainability of Traditional, Historical Roofs in the Mediterranean (Sustainability, 2023)","url":"https://www.mdpi.com/2071-1050/15/17/12723","publisher":"MDPI Sustainability"},{"title":"EN Eurocodes","url":"https://eurocodes.jrc.ec.europa.eu/","publisher":"European Commission Joint Research Centre"}]},{"slug":"roofing-in-czechia","title":"Roofing in Czechia","category":"world-roofing","type":"place","country":{"name":"Czechia","iso2":"CZ"},"summary":"Czech roofing: steep clay beaver-tail (bobrovka) roofs, Moravian-Silesian slate, Baroque village gables and slate roofs in Prague.","body":"Czech roofs are mostly steep, pitched roofs of fired clay. The flat beaver-tail tile (*bobrovka*) has been one of the most common coverings in the Czech lands for centuries and is still required in many heritage zones, while slate from the Moravian-Silesian uplands roofed many important buildings in Prague and Vienna. Wooden shingles were once common on rural log houses and were gradually replaced by tile, largely because of fire risk.\n\n## Climate and hazards\n\nCzechia has a temperate continental climate with cold, snowy winters, especially in the mountain ranges along its borders, and warm summers with thunderstorms. Snow loads, frost and wind-driven rain are the main design concerns; structural design follows the Eurocodes, with snow covered by Eurocode 1, Part 1-3. Fire historically drove the change from shingle and thatch to tile.\n\n## Roofing history\n\nThe Czech lands have a long carpentry tradition; the historic roof structures of Cheb in western Bohemia are promoted locally as a regional phenomenon and documented in a dedicated project. On log cabins and rural houses, clay beaver-tail tiles gradually replaced flammable wooden shingles, and they became one of the most common roofs in the Czech lands, used on gable, hipped, pyramidal and mono-pitch roofs and on churches.\n\nRoofing slate was quarried in the Moravian-Silesian Region, where deposits around Vítkov and Budišov nad Budišovkou in the Opava district are described as the largest deposits of high-quality splittable slate in Central Europe. Slate mining boomed under the Austro-Hungarian Empire, and slate from the region covered the roofs of major buildings in Vienna and Prague, including the National Theatre. Most mines later closed because of high costs and difficult technology, and slate is now mostly imported, chiefly for restoring historic buildings, although plans to reopen mines were announced in the 2020s.\n\n## Traditional and vernacular roofs\n\n- **Bobrovka (beaver-tail tile):** a flat, rounded-end clay tile, named for its resemblance to the scaly tail of a beaver. The traditional Czech size is about 17.5-18 by 38 cm (6.9-7.1 by 15 in), and each tile weighs about 1.75 kg (3.9 lb). A double-lapped roof weighs about 60 kg/m² (12 lb/ft²), making it one of the heaviest common coverings. Because the tiles have no side grooves or ribs that lock them together, they can follow curves, valleys and dormers. They need a pitch of at least 30°, and double laying needs at least 40°.\n- **Laying patterns:** single laying (*loučové*), which needs a separate waterproof layer beneath; double \"crown\" laying (*korunové*) on battens about 29-33 cm (11-13 in) apart; and double \"scale\" laying (*šupinové*) on battens about 14.5-16.5 cm (5.7-6.5 in) apart. A double-laid roof uses about 36 unglazed tiles per square metre.\n- **Finishes:** unglazed (*režná*) tiles weather to a patina; engobed tiles have a matt clay coating; glazed tiles are the most durable and the most expensive.\n- **South Bohemian Folk Baroque:** in villages such as Holašovice, 18th- and 19th-century farmhouses face the green with richly decorated, multicoloured gables, and smaller buildings such as the forge have simple gable roofs.\n\n## Roofing today\n\nBeaver-tail tiles remain common and are often required by the authorities in conservation areas. Concrete versions of the beaver-tail are also made.\n\n## Codes, standards and regulation\n\nThe main Czech standard for roof design is ČSN 73 1901, *Navrhování střech* (\"Design of roofs\"), first published in this form in 1999, with newer parts issued since.\n\n## Industry\n\nCzechia has domestic clay and concrete tile production and a historic slate industry in the Moravian-Silesian Region, where Budišov nad Budišovkou has a slate museum.\n\n## Notable roofs\n\n- **National Theatre**, Prague, roofed with Moravian-Silesian slate.\n- **Holašovice**, a UNESCO-listed village of 23 farmsteads around a green, in South Bohemian Folk Baroque style.\n- **Historic roof trusses of Cheb**, studied as a regional phenomenon.\n\n## Local roofing terms\n\n- *bobrovka* - beaver-tail tile\n- *korunové krytí* - double \"crown\" laying\n- *šupinové krytí* - double \"scale\" laying\n- *loučové krytí* - single laying\n\n## Sources and gaps\n\nMarket shares for Czech roofing materials and information on specific manufacturers: published information is limited.","key_facts":[{"label":"Traditional covering","value":"Clay beaver-tail tile (bobrovka)"},{"label":"Beaver-tail size","value":"About 17.5-18 x 38 cm (7 x 15 in)"},{"label":"Minimum pitch","value":"30° (40° for double laying)"},{"label":"Slate region","value":"Moravian-Silesian Region (Opava district)"},{"label":"Roof design standard","value":"ČSN 73 1901"}],"regions":["Europe"],"aliases":["Czech roofing","roofing in the Czech Republic","roofs in Czechia"],"related":["clay-roof-tile","natural-slate","wood-shingle","concrete-roof-tile","roofing-in-slovakia","roofing-in-germany","roofing-in-austria","roofing-in-poland","german-roofing-slate","onion-dome"],"company":null,"sources":[{"title":"Vybíráte si novou střešní krytinu? A co tradiční bobrovky?","url":"https://www.ceskestavby.cz/clanky/vybirate-si-novou-stresni-krytinu-a-co-tradicni-bobrovky-27147.html","publisher":"České stavby"},{"title":"Former slate mines set to re-open in Moravia Silesia","url":"https://english.radio.cz/node/8722470","publisher":"Radio Prague International"},{"title":"Černý důl (roofing slate locality)","url":"https://lokality.geology.cz/2400?la=en","publisher":"Czech Geological Survey"},{"title":"Holašovice Historic Village","url":"https://whc.unesco.org/en/list/861","publisher":"UNESCO World Heritage Centre"},{"title":"ČSN 73 1901 Navrhování střech – Základní ustanovení","url":"https://www.tzb-info.cz/normy/csn-73-1901-1999-01","publisher":"TZB-info"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"},{"title":"Historic roof structures – a Cheb phenomenon","url":"https://visitcheb.cz/en/historical-roof-structures","publisher":"Visit Cheb"}]},{"slug":"roofing-in-denmark","title":"Roofing in Denmark","category":"world-roofing","type":"place","country":{"name":"Denmark","iso2":"DK"},"summary":"Danish roofing: reed thatch, Læsø seaweed roofs, red clay tiles and copper spires, and today a stock dominated by fibre-cement, tile and flat built-up roofs.","body":"Denmark is low-lying, maritime and without native building stone, so its roofs have been made of plant material, fired clay and, in the 20th century, fibre-cement sheet. Thatched roofs of water reed and straw were the ordinary covering of farmhouses for centuries and more than 50,000 thatched buildings still stand, while the island of Læsø developed a distinctive roof of dried eelgrass. Statistics Denmark records roof materials for every building in the country, making Denmark one of the few nations with a full register of its roofs.\n\n## Climate and hazards\n\nRoofs face wind-driven rain, salt air and storms from the North Sea and Kattegat, with frequent freeze-thaw in winter. Fire has been the classic hazard for thatch, and asbestos in older fibre-cement roofs is a current concern.\n\n## Roofing history\n\nDanish roofs were built mainly of plant materials for thousands of years. At Hedeby, the Viking-age trading town near today's Danish-German border, houses of the late 8th century had oak frames and probably thatched roofs. Thatch remained the normal rural roof through the medieval and early modern periods, on half-timbered farmhouses and vicarages such as Kølstrup near Kerteminde on Funen. Liselund on Møn, built in the 1790s, is unusual as a neoclassical house with a thatched roof.\n\nOn Læsø, salt boiling in the 17th century stripped the island of trees. Reed was hard to bring to the island and straw was needed as fodder, so islanders roofed their houses with eelgrass gathered from the shore. Surviving seaweed roofs date back to the 1650s.\n\nFrom the 19th century, houses in towns such as Skagen were whitewashed or painted yellow and roofed with red clay tiles. After the Second World War, functionalist houses and public buildings often had flat roofs. Corrugated and flat fibre-cement sheets, many of them containing asbestos, became one of the most common roof coverings on houses, farm buildings and garages.\n\n## Traditional and vernacular roofs\n\n- **Stråtag (thatch):** reed or straw laid in thick courses on steep roofs, typically finished at the ridge with turf, heather or wooden ridge pieces. See Dutch and Danish reed thatch.\n- **Seaweed roof:** the eelgrass roofs of Læsø, laid directly on the roof beams by teams of 40-50 or more people and built up to 1.5 m (4.9 ft) thick. See Læsø seaweed roof.\n- **Tile roofs:** red clay tiles on town houses, typical of places such as Skagen from the 19th century.\n\n## Roofing today\n\nStatistics Denmark's register of buildings gave this breakdown of roofed area on 1 January 2026, out of 628.8 million m² (6.77 billion ft²) on 4.95 million buildings:\n\n- Other roofing materials: 35.7%\n- Fibre cement that may contain asbestos: 31.8% (200 million m², falling by 2.5% in a year)\n- Tile: 13.4%\n- Built-up flat roofs: 10.4%\n- Asbestos-free fibre cement: 8.5%\n- Green roofs: 0.2%\n\nThe same register counted 52,509 thatched buildings, a number that has fallen by an average of 335 a year over 15 years. Region of Southern Denmark has the most, with 33% of the total. Flat roofs are mostly covered with bituminous membranes.\n\n## Codes, standards and regulation\n\nConstruction is governed by the Danish Building Regulations, as of 2026 BR18 (Bygningsreglementet 2018), which cover structural safety, fire, moisture and energy performance.\n\n## Industry\n\nThe bituminous membrane brand Icopal originated in Denmark and is now part of BMI Group. See Icopal. The Nordic membrane group Nordic Waterproofing also operates Danish brands. See Nordic Waterproofing.\n\n## Notable roofs\n\n- **Læsø seaweed houses**, part of a salt-production cultural landscape on Denmark's UNESCO Tentative List since 2023.\n- **Liselund**, Møn, a thatched neoclassical country house of the 1790s.\n- **Skagen**, known for its yellow houses with red-tiled roofs.\n\n## Local roofing terms\n\n- *stråtag* - thatched roof\n- *tang* - seaweed (eelgrass)\n- *tørvetag* - turf roof\n\n## Sources and gaps\n\nStatistics Denmark does not break down its \"other materials\" category, which covers more than a third of roofed area.","key_facts":[{"label":"Largest identified material (by area)","value":"Fibre cement, 31.8% possibly asbestos-containing (2026)"},{"label":"Tile share of roof area","value":"13.4% (2026)"},{"label":"Thatched buildings","value":"52,509 (2026)"},{"label":"Building code","value":"BR18"},{"label":"Distinctive roof","value":"Læsø seaweed (eelgrass) roofs"}],"regions":["Europe"],"aliases":["Danish roofing","roofs in Denmark"],"related":["dutch-and-danish-reed-thatch","laeso-seaweed-roof","water-reed-thatch","thatch","clay-roof-tile","fibre-cement-slate","asbestos-cement-roofing","icopal","nordic-waterproofing","roofing-in-scandinavia","roofing-in-germany","roofing-in-sweden"],"company":null,"sources":[{"title":"Flere asbestfrie tage i 2025","url":"https://www.dst.dk/nyt/53885","publisher":"Statistics Denmark (Danmarks Statistik)"},{"title":"Architecture of Denmark","url":"https://en.wikipedia.org/wiki/Architecture_of_Denmark","publisher":"Wikipedia"},{"title":"Seaweed roofs on Læsø","url":"https://en.wikipedia.org/wiki/Seaweed_roofs_on_L%C3%A6s%C3%B8","publisher":"Wikipedia"},{"title":"Seaweed houses on Læsø – Kaline's House","url":"https://realdaniabyogbyg.org/projects/seaweed-houses-on-laeso-kaline-s-house","publisher":"Realdania By & Byg"},{"title":"Building Regulations 2018 (BR18)","url":"https://www.iea.org/policies/2511","publisher":"International Energy Agency"}]},{"slug":"roofing-in-djibouti","title":"Roofing in Djibouti","category":"world-roofing","type":"place","country":{"name":"Djibouti","iso2":"DJ"},"summary":"Djibouti's traditional shelters are portable Afar and Somali huts of branches and woven mats; towns use stone, coral and masonry with white-painted walls.","body":"Djibouti is a small, hot and arid country on the Gulf of Aden, home mainly to Afar people in the north and Issa Somali people in the south, with overlap in central areas including Djibouti City. Both groups historically lived as pastoral nomads, and their traditional houses are light, portable shelters whose roof and walls are a single woven skin.\n\n## Climate and hazards\n\nDjibouti is hot and dry for most of the year. Strong winds are a design concern: the curved, low profile of traditional huts reduces wind resistance.\n\n## Roofing history and traditional roofs\n\n- **Afar *danas***: round huts of bent acacia branches covered with mats woven from palm leaves or grass. Research on Afar architecture in neighbouring Ethiopia describes these flexible shelters of twigs and woven mats as designed to be moved by camel.\n- **Somali *aqal***: a dome-shaped hut with a collapsible frame of sticks covered with mats (see Aqal).\n- **Permanent buildings**: settlements and mosques used coral stone, mud brick or locally quarried limestone.\n\nIn the colonial period, buildings in Djibouti City adopted Mediterranean and Moorish-inspired styles adapted to the climate, with arcades, verandas and courtyards, thick masonry walls, tall ceilings and white paint to reduce heat absorption.\n\nAs Afar communities settle, many build permanent houses with wooden frames plastered with clay, a technique described as unsustainable in an arid region where trees are scarce.\n\n## Local roofing terms\n\n- **danas** (Afar): round hut of branches and mats.\n- **aqal** (Somali): dome-shaped portable hut.\n\n## Sources and gaps\n\nNo household survey or census table on roof materials for Djibouti was found in published sources. No information on domestic roofing manufacturers was found.\n\nPublished sources are limited. The Afar term *daboyta*, sometimes given for the Afar hut: published information is limited. Roof construction of colonial buildings, modern housing materials and building regulation were not documented in published sources.","key_facts":[{"label":"Traditional shelters","value":"Afar danas, Somali aqal"},{"label":"Traditional materials","value":"Acacia branches, palm-leaf or grass mats"},{"label":"Permanent materials","value":"Coral stone, mud brick, limestone"},{"label":"Climate driver","value":"Extreme heat, wind"}],"regions":["Africa","Middle East"],"aliases":["Djiboutian roofing","roofing in Djibouti"],"related":["aqal","roofing-in-somalia","roofing-in-ethiopia","roofing-in-eritrea","dome","flat-roof"],"company":null,"sources":[{"title":"The Traditional Architecture of Djibouti","url":"https://www.arabamerica.com/the-traditional-architecture-of-djibouti","publisher":"Arab America"},{"title":"Research on traditional Afar architecture and construction of a hostel building (AfarEARTH)","url":"https://baugeschichte.tuwien.ac.at/website/afarearth/","publisher":"TU Wien, Research Unit of History of Architecture"},{"title":"The Somali aqal","url":"https://www.paukwa.or.ke/?p=14652","publisher":"Paukwa"}]},{"slug":"roofing-in-dominica","title":"Roofing in Dominica","category":"world-roofing","type":"place","country":{"name":"Dominica","iso2":"DM"},"summary":"Dominican (Commonwealth) roofing: Hurricane Maria in 2017 damaged 98% of roofs, prompting stronger housing standards with thicker rafters and purlins.","body":"Dominica, a steep volcanic island between Guadeloupe and Martinique, lost almost all of its roofs when Hurricane Maria passed over it in 2017. Its recovery became a regional test case for building back roofs to a higher standard.\n\n## Climate and hazards\n\nHurricane Maria made landfall on 18 September 2017 as a Category 5 storm with winds above 277 km/h (172 mph). The Post-Disaster Needs Assessment put damage at US$930.9 million and losses at US$380.2 million, together equal to 226% of 2016 GDP. Housing was the worst-hit sector, with 38% of all damage, and about 90% of the housing stock was damaged. A shelter-sector review reported that over 90% of buildings and 98% of roofs were damaged; the building damage assessment recorded 23,488 damaged houses, of which 5,961 were completely destroyed. Dominica also faces earthquakes, volcanic hazards and flooding.\n\n## Roofing history\n\nThroughout the Eastern Caribbean, older timber houses typically have steep hip or gable roofs clad first in wooden shingles and later in corrugated iron. Hip roofs, sloping on all four sides, are self-bracing and lack tall gable ends that catch the wind, and slopes of about 35 degrees or more are often preferred in hurricane regions because shallower roofs are more prone to uplift.\n\n## Roofing today\n\nAfter Maria, roof repair programmes used corrugated roofing sheet, galvanised ridge capping, treated timber and metal straps, ties and angle brackets. One programme repaired 670 roofs averaging 35 m² (377 ft²) at an average cost of US$3,700 (US$2,550 materials, US$1,150 labour), and trained 180 people in basic carpentry and Build Back Safer techniques. Underestimated structural damage, code requirements and material shortages raised costs, and many houses needed structural strengthening before they could carry a code-compliant roof.\n\n## Codes, standards and regulation\n\nThe Organisation of Eastern Caribbean States (OECS) developed model building codes and guidelines for small buildings with support from UNCHS and UNDP, based on the Caribbean Uniform Building Code (CUBiC). The USAID-funded, OAS-executed Caribbean Disaster Mitigation Project helped Antigua and Barbuda, Dominica, Grenada and Saint Lucia prepare national codes from these models, and published construction diagrams covering hip and gable roof framing, rafter-to-ring-beam and wall-plate connections and hurricane straps for houses under 3,000 ft² (279 m²). A revised OECS Building Code was issued in June 2015, reviewed that year for Grenada, Saint Vincent and the Grenadines, Saint Lucia and Montserrat, and drew on the codes of Jamaica and the Cayman Islands. National consultations on administering it were held across the sub-region in 2017 under the EU-funded iLand Resilience project. Dominica's draft national code was awaiting legislation under the Development Planning Act in the late 1990s. After Maria, a revision of the Dominica Housing Standards was completed on 15 January 2018, chiefly increasing purlin and rafter sizes, and published as the Guide to Dominica Housing Standards 2018.\n\n## Sources and gaps\n\nPublished accounts of island-specific historic and Kalinago roofing: published information is limited.\n\nPre-Maria roofing history, Kalinago building and material statistics: published information is limited.","key_facts":[{"label":"Hurricane Maria","value":"Cat 5, 18 Sept 2017; 98% of roofs damaged"},{"label":"Damage and losses","value":"226% of 2016 GDP"},{"label":"Housing standards","value":"Guide to Dominica Housing Standards 2018"},{"label":"Typical repair","value":"Corrugated sheet on treated timber with straps and ties"}],"regions":["Latin America","North America"],"aliases":["Roofing in the Commonwealth of Dominica"],"related":["roofing-in-the-caribbean","hip-roof","corrugated-iron","hurricane-roof-damage","hurricane-tie","chattel-house","roofing-in-saint-lucia","roofing-in-antigua-and-barbuda","roofing-in-puerto-rico"],"company":null,"sources":[{"title":"Dominica: Post-Disaster Needs Assessment following Hurricane Maria","url":"https://www.gfdrr.org/en/publication/dominica-post-disaster-needs-assessment-following-hurricane-maria","publisher":"GFDRR / Government of the Commonwealth of Dominica"},{"title":"Dominica 2017-2018: Hurricane Maria (Shelter Projects case study A.11)","url":"https://shelterprojects.org/shelterprojects2017-2018/SP17-18_A11-Dominica-2017-2018.pdf","publisher":"Global Shelter Cluster, Shelter Projects"},{"title":"Guide to Dominica Housing Standards 2018","url":"https://www.physicalplanning.gov.dm/land-use-and-development/documents/142-guide-to-dominica-housing-standards-2018","publisher":"Physical Planning Division, Government of Dominica"},{"title":"Building codes in the Caribbean (CDMP bulletin)","url":"https://oas.org/cdmp/bulletin/codes.htm","publisher":"Organization of American States, Caribbean Disaster Mitigation Project"},{"title":"OECS Building Code (June 2015)","url":"https://oecs.int/en/our-work/knowledge/library/sustainable-energy/oecs-building-codes/oecs-building-code-1-5","publisher":"Organisation of Eastern Caribbean States"}]},{"slug":"roofing-in-east-africa","title":"Roofing in East Africa","type":"place","summary":"Overview of roofing in Kenya, Tanzania, Uganda, Rwanda and Ethiopia: grass thatch traditions largely replaced by corrugated iron sheets (mabati).","body":"Across East Africa, from the Kenyan coast to the highlands of Ethiopia and the Great Lakes, the roof that dominates towns and villages is the corrugated metal sheet, known throughout the Swahili-speaking region as *mabati*. It has largely replaced the grass and leaf thatch that covered most rural houses within living memory.\n\n## Traditional roofs\n\nTraditional houses across the region were usually round or rectangular, with walls of poles, mud and wattle, and conical or pitched roofs of grass or palm thatch. Round houses with conical thatched roofs, structurally similar to the Southern African rondavel, with radial rafters meeting at an apex, were widespread. On the Swahili coast, coral-stone houses had flat roofs on mangrove-pole joists, and rural coastal houses used *makuti* thatch of coconut palm leaves. Pastoralist communities such as the Maasai built low houses of branches and mud with flat or gently curved roofs plastered in mud and dung.\n\n## Mabati\n\nCorrugated galvanised iron, patented in Britain in 1829, spread through East Africa in the colonial era and after independence. It is light, quick to fix and easy to transport, and it allows rainwater harvesting. It is widely used in informal settlements and has become a marker of a \"modern\" house in rural areas. Regional manufacturers now roll galvanised and zinc-aluminium-coated steel, in corrugated, box-profile and tile-effect forms, often pre-painted.\n\nDrawbacks are well known: thin sheets make houses very hot by day and cold at night, rain on metal is loud, and corrosion is a problem near the coast or where rainfall is acidic.\n\n## Other modern roofs\n\nReinforced concrete flat roofs are common on urban apartments and commercial buildings. Clay and concrete tiles, and stone-coated steel tiles, are used on middle- and higher-income houses.\n\n## Climate\n\nMuch of East Africa lies near the equator but at altitude, with two rainy seasons and strong sun. Good overhangs, insulation or ceilings beneath metal sheets, and secure fixing against storm winds are key design concerns.","key_facts":[{"label":"Dominant covering","value":"Corrugated iron sheet (mabati)"},{"label":"Traditional coverings","value":"Grass and palm thatch, mud"},{"label":"Coastal tradition","value":"Makuti palm thatch, coral-stone flat roofs"},{"label":"Main issues","value":"Heat, noise, corrosion"}],"regions":["Africa"],"aliases":["Mabati","Kenyan roofing","Tanzanian roofing","Ugandan roofing"],"related":["corrugated-iron","rondavel","roofing-in-southern-africa","thatch","rainwater-harvesting-roofs"],"sources":[{"title":"Corrugated galvanised iron","url":"https://en.wikipedia.org/wiki/Corrugated_galvanised_iron","publisher":"Wikipedia"},{"title":"Rondavel","url":"https://en.wikipedia.org/wiki/Rondavel","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-ecuador","title":"Roofing in Ecuador","category":"world-roofing","type":"place","country":{"name":"Ecuador","iso2":"EC"},"summary":"Ecuadorian roofing: colonial tile over earthen walls in Quito and Cuenca, cane-and-mud quincha houses on the coast, and metal and fibre-cement today.","body":"Ecuador's roofs reflect three very different regions: the Andean highlands, where colonial cities such as Quito and Cuenca were built of earth with clay tile roofs; the hot, wet Pacific coast, with a long tradition of bamboo (*caña guadúa*) houses on stilts; and the Amazon lowlands. The whole country is exposed to strong earthquakes.\n\n## Climate and hazards\n\n- **Earthquakes** throughout the country. UNESCO notes that Quito has been affected by numerous earthquakes, including one in 1917, while keeping its historic centre largely intact.\n- **Volcanic ash** from Andean volcanoes.\n- **Heavy rain and flooding** on the coast, favouring houses raised on piles.\n\n## Roofing history\n\n**Pre-Columbian and coastal.** Research at the Universidad Laica Eloy Alfaro de Manabí traces houses of *caña guadúa* bamboo and earth plaster, called *quinche* or quincha, through every period of Ecuadorian history from pre-Columbian times to the present. Documented types include houses on stilts (*palafitos*), houses on piles with a ground floor for work, the rural *montubio* house of cane and quinche, and the three-volume rural house of Manabí. Jorge Juan and Antonio de Ulloa described the coastal vernacular house in 1748.\n\n**Colonial highlands.** The Spanish founded Quito in 1534 on the ruins of an Inca city, at an altitude of about 2,850 m (9,350 ft). UNESCO records that its houses were usually built of earthen bricks covered with stucco, using stone, lime, mud and wood. Quito was among the first places inscribed on the World Heritage List, in 1978, and the historic centre of Cuenca followed in 1999.\n\n**18th to 20th centuries.** Timber, cane and quinche mansions were built in Guayaquil in the 18th century and Portoviejo in the 19th, and the port of Manta had timber and cane houses in the early 20th century. Concrete, metal sheet and fibre-cement spread through the 20th century.\n\n## Traditional and vernacular roofs\n\n- **Clay tile on adobe** in highland towns such as Quito and Cuenca.\n- **Caña guadúa houses** of the coast, raised on piles.\n\n## Roofing today\n\nThe 2022 census counted 5,062,218 occupied dwellings, and a 2025 analysis of its results classed 46.2% as in housing deficit because of poor-quality floors, walls or roofs.\n\n## Codes, standards and regulation\n\nA 2012 comparative review listed Ecuador's INEN-5 code of 2001 as its seismic design standard.\n\n## Notable roofs\n\n- **City of Quito** (UNESCO 1978).\n- **Historic Centre of Santa Ana de los Ríos de Cuenca** (UNESCO 1999).\n\n## Local roofing terms\n\n- *Teja*: clay tile.\n- *Caña guadúa*: giant bamboo used for frames and walls.\n- *Quinche*: cane and mud wall infill.\n- *Caña picada* or *esterilla*: flattened split bamboo panels.","key_facts":[{"label":"Highland tradition","value":"Clay tile on earthen walls"},{"label":"Coastal tradition","value":"Caña guadúa and quinche houses on piles"},{"label":"Seismic code (2012 review)","value":"INEN-5 (2001)"},{"label":"Heritage","value":"Quito, UNESCO 1978"}],"regions":["Latin America"],"aliases":["Ecuadorian roofing"],"related":["quincha","clay-roof-tile","spanish-tile","corrugated-iron","asbestos-cement-roofing","roofing-in-colombia","roofing-in-peru"],"company":null,"sources":[{"title":"City of Quito","url":"https://whc.unesco.org/en/list/2","publisher":"UNESCO World Heritage Centre"},{"title":"Propuestas constructivas sostenibles: la caña guadúa y los BTC de terro-cemento","url":"https://grupotierra.uva.es/aecid/publicaciones/2013/6d.pdf","publisher":"Grupo TIERRA, Universidad de Valladolid / ULEAM"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"},{"title":"Deterioradas y al borde de la demolición: así está casi la mitad de viviendas en Ecuador","url":"https://www.primicias.ec/revistagestion/analisis/vivienda-casa-demolicion-problemas-deficit-habitacional-ecuador-103446/","publisher":"Primicias"}]},{"slug":"roofing-in-egypt","title":"Roofing in Egypt","category":"world-roofing","type":"place","country":{"name":"Egypt","iso2":"EG"},"summary":"Egypt's roofs run from stone-slab temple roofs and some of the oldest standing mud-brick vaults to Nubian domes, Siwa salt-mud houses and today's concrete.","body":"Egypt has one of the longest continuous records of roof building in the world. Pharaonic builders roofed temples with massive stone slabs and stores with mud-brick barrel vaults, ordinary houses were built of Nile mud with usable flat roofs, and Nubian masons along the southern Nile kept a tradition of timber-free earth vaults and domes alive into the 20th century. Today the great majority of Egyptian households live under reinforced concrete.\n\n## Climate and hazards\n\nAlmost all of Egypt is hot desert and rain is rare in most of the country, which has allowed flat roofs of earth and masonry to dominate. The dry climate is the main reason so many ancient mud-brick buildings, including the workmen's village of Deir el-Medina and the town of Kahun, survive at all. The main roof loads are heat and sun; the scarcity of good timber has shaped roof structure throughout Egyptian history.\n\n## Roofing history\n\n**Ancient Egypt.** Monumental buildings used post-and-lintel construction: their roofs were flat and made of huge stone blocks carried on the outer walls and on closely spaced columns. This is why temple halls are forests of columns. The Great Hypostyle Hall at Karnak has about 134 columns in 16 rows, the 12 central columns about 21 m (69 ft) tall, all supporting a stone roof. The arch was developed during the Fourth Dynasty (c. 2613-2494 BC), but monumental buildings continued to rely on stone lintels.\n\n**Mud-brick vaults.** The storerooms around the Ramesseum, the mortuary temple of Ramesses II on the west bank at Luxor (13th century BC), are long mud-brick barrel vaults. They are true arches held by mortar alone, and the Ramesseum preserves what is cited as the oldest such arch still standing in Egypt (see Ramesseum granary vaults).\n\n**Houses.** At Deir el-Medina, the village of the royal tomb builders (occupied from the reign of Thutmose I, c. 1506-1493 BC, to about 1110-1080 BC), about 68 houses of mud brick on stone foundations each had a staircase leading up to the roof. Windows were set high in the walls to keep out the glare of the sun.\n\n**Islamic and later periods.** Domes and vaults of brick and stone continued in mosques, tombs and baths (see Middle Eastern domes). In the Western Desert, the fortified town of Shali in Siwa Oasis, dated to about 1203 AD, was built of *kershef*, a mixture of salt rock and mud, with ceilings of palm wood (see Kershef).\n\n**20th century.** The architect Hassan Fathy (1900-1989) revived the Nubian vault and dome in mud brick. His village of New Gourna near Luxor, built between 1946 and 1952 to rehouse the community of Old Gourna living above the Theban tombs, made earth roofs a subject of international debate (see Hassan Fathy and New Gourna). Over the same century, reinforced concrete became the standard roof for new housing.\n\n## Traditional and vernacular roofs\n\n- **Flat roofs with stair access**: as at Deir el-Medina, where every house had a staircase to the roof; in oases such as Siwa, ceilings were of palm wood.\n- **Nubian vaults and domes**: mud-brick barrel vaults built without formwork, from the southern Nile valley (see Nubian vault).\n- **Kershef roofs of Siwa**: salt-mud walls with palm-trunk roofs; Siwan builders soaked palm wood in salt-lake water to remove the sap that attracts insects.\n- **Stone and brick domes**: in mosques, mausoleums and bathhouses.\n\n## Roofing today\n\nEgypt's national statistics agency, CAPMAS, asks households about the main roof material in its Household Income, Expenditure and Consumption Survey, using the categories reinforced concrete, metal, wood, rustic mats, straw or palm fronds, carton, and none. Published weighted figures from the Harmonized Survey of Young People in Egypt (2014) household data give a picture of the mix:\n\n| Main roof material | Weighted share |\n|---|---|\n| Reinforced concrete | 82.5% |\n| Wood | 9.9% |\n| Straw | 5.9% |\n| Mud | 0.9% |\n| Tiles or wooden planks | 0.5% |\n| Galvanized steel | 0.4% |\n\nFlat reinforced concrete slabs therefore cover roughly four in five households. Wood, straw and mud together still account for about one household in six in this survey.\n\n## Codes, standards and regulation\n\nIn New Gourna, UNESCO has identified out-of-scale reinforced-concrete buildings and lack of maintenance as threats to Fathy's earth vaults.\n\n## Notable roofs\n\n- **Hypostyle halls of Karnak and Luxor**: stone-slab roofs carried on columns.\n- **Ramesseum storerooms**: mud-brick barrel vaults of the 13th century BC.\n- **Deir el-Medina**: ancient village houses with roof access stairs.\n- **Shali, Siwa**: kershef fortress, restored in a project completed in 2020.\n- **New Gourna**: Hassan Fathy's mud-brick vaults and domes, subject of a UNESCO safeguarding project launched in 2009.\n\n## Local roofing terms\n\n- **kershef** (karshef): salt-rock and mud building material of Siwa.\n\n## Sources and gaps\n\nNo national roofing code was found in published sources. No information on domestic roofing manufacturers was found.\n\nAncient roof details come largely from encyclopedic summaries of the archaeology. The roof-material shares are from a youth survey sample as published on a data portal; a full census table on roofs from CAPMAS are not well documented in published sources.","key_facts":[{"label":"Dominant material today","value":"Reinforced concrete (82.5% of households, 2014 survey, weighted)"},{"label":"Traditional materials","value":"Stone slabs, mud brick, palm wood, kershef"},{"label":"Early standing mud-brick vaults","value":"Ramesseum storerooms, 13th century BC"},{"label":"Climate driver","value":"Extreme heat and aridity; scarce timber"},{"label":"Modern earth revival","value":"Hassan Fathy, New Gourna (1946-1952)"}],"regions":["Africa","Middle East"],"aliases":["Egyptian roofing","roofs of Egypt"],"related":["roofing-in-north-africa","nubian-vault","ramesseum-granary-vaults","hassan-fathy","new-gourna","kershef","middle-eastern-domes","flat-roof","mud-roof","roofing-in-sudan","roofing-in-libya","barrel-vault-roof","dome"],"company":null,"sources":[{"title":"Ancient Egyptian architecture","url":"https://en.wikipedia.org/wiki/Ancient_Egyptian_architecture","publisher":"Wikipedia"},{"title":"Ramesseum","url":"https://en.wikipedia.org/wiki/Ramesseum","publisher":"Wikipedia"},{"title":"Deir el-Medina","url":"https://en.wikipedia.org/wiki/Deir_el-Medina","publisher":"Wikipedia"},{"title":"Shali Village in Siwa Oasis","url":"https://iwh.icesco.org/shali-village-in-siwa-oasis/","publisher":"ICESCO Islamic World Heritage"},{"title":"Restoration and Revival of the Shali Fortress","url":"https://next.archnet.org/sites/21598","publisher":"Archnet"},{"title":"Safeguarding Project of Hassan Fathy's New Gourna Village","url":"https://whc.unesco.org/en/activities/637","publisher":"UNESCO World Heritage Centre"},{"title":"Hassan Fathy","url":"https://en.wikipedia.org/wiki/Hassan_Fathy","publisher":"Wikipedia"},{"title":"Harmonized Survey of Young People in Egypt 2014: roof material (roof_mt)","url":"https://www.erfdataportal.com/index.php/catalog/153/variable/V14754","publisher":"Economic Research Forum / CAPMAS"},{"title":"Household Income, Expenditure and Consumption Survey 2017: roof material (Q8)","url":"https://catalog.ihsn.org/catalog/10346/variable/F1/V109?name=Q8","publisher":"CAPMAS via IHSN Survey Catalog"}]},{"slug":"roofing-in-el-salvador","title":"Roofing in El Salvador","category":"world-roofing","type":"place","country":{"name":"El Salvador","iso2":"SV"},"summary":"Salvadoran roofing: Joya de Cerén's ash-buried thatch of about 600 CE, bahareque and tile houses, and metal and concrete roofs in a quake-prone land.","body":"El Salvador is a small, volcanic country on the Pacific coast of Central America. It holds unusually well-preserved ancient house roofs, at the buried village of Joya de Cerén, and a long tradition of earthen houses built to cope with frequent earthquakes.\n\n## Climate and hazards\n\n- **Earthquakes.** On 13 January 2001 a magnitude 7.7 earthquake killed at least 944 people in El Salvador, and 108,261 houses collapsed; a second earthquake one month later killed a further 315. Landslides in Santa Tecla and Comasagua caused most of the deaths in La Libertad department.\n- **Volcanic eruptions.** An earlier eruption of the Ilopango caldera, usually dated to the 5th or 6th century CE, had blanketed much of central El Salvador in ash, and a later eruption of the Loma Caldera vent around 600 CE buried Joya de Cerén.\n- **Hurricanes and tropical storms.** Hurricane Mitch in 1998 killed 240 people and damaged more than 10,000 houses.\n\n## Roofing history\n\n**Ancient.** At Joya de Cerén, a Maya farming village, volcanic ash preserved houses, storehouses, a kitchen, a sweat bath and communal buildings. Household buildings had walls of wattle and daub (*bajareque*) and adobe columns, and public buildings used rammed earth. Excavators found thick thatched roofs carried on timber poles that rose from the walls, with eaves projecting well beyond the walls. The site was inscribed by UNESCO in 1993.\n\n**Colonial and later.** Spanish colonial towns used adobe and *bahareque* walls with clay tile roofs.\n\n**Modern.** Metal sheet, fibre-cement sheet and reinforced concrete became the main roofing materials in the 20th century. The 2001 earthquakes destroyed large numbers of older houses.\n\n## Traditional and vernacular roofs\n\n- **Bahareque**: a frame of poles or cane with woven sticks plastered with mud, carrying a thatch or tile roof; UNESCO notes its good earthquake resistance at Cerén.\n- **Teja** roofs on adobe and bahareque houses in older towns.\n- **Thatch** in rural areas, now rare.\n\n## Roofing today\n\nMetal sheet and fibre-cement sheet are common on houses, and concrete slabs on urban buildings.\n\n## Codes, standards and regulation\n\nA 2012 comparative review listed El Salvador's *Norma Técnica para Diseño por Sismo* (NTDS) of 1997 as the seismic design code then in force.\n\n## Notable roofs\n\n- **Joya de Cerén** (UNESCO 1993): some of the most complete evidence of ancient Mesoamerican thatched roofs, preserved under volcanic ash.\n\n## Local roofing terms\n\n- *Bajareque* or *bahareque*: wattle-and-daub construction.\n- *Teja*: clay tile.\n- *Lámina*: metal sheet.\n- *Tabanco*: a raised pole platform or loft inside a house, recorded at Cerén.","key_facts":[{"label":"Climate drivers","value":"Earthquakes, volcanoes, hurricanes"},{"label":"2001 earthquake","value":"108,261 houses collapsed"},{"label":"Ancient roofs","value":"Thatch at Joya de Cerén, about 600 CE"},{"label":"Traditional walls","value":"Bahareque, adobe"},{"label":"Seismic code (2012 review)","value":"NTDS 1997"}],"regions":["Latin America"],"aliases":["Salvadoran roofing"],"related":["joya-de-ceren","maya-thatched-house","thatch","clay-roof-tile","roofing-in-guatemala","roofing-in-honduras"],"company":null,"sources":[{"title":"Joya de Cerén Archaeological Site","url":"https://whc.unesco.org/en/list/675","publisher":"UNESCO World Heritage Centre"},{"title":"Joya de Cerén","url":"https://en.wikipedia.org/wiki/Joya_de_Cer%C3%A9n","publisher":"Wikipedia"},{"title":"Household archaeology at Cerén, El Salvador (Ancient Mesoamerica 1, 1990)","url":"https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A458CD7DAF7B5CC22BD9E6A81E8C2270/S0956536100000092a.pdf/household_archaeology_at_ceren_el_salvador.pdf","publisher":"Cambridge University Press"},{"title":"January 2001 El Salvador earthquake","url":"https://en.wikipedia.org/wiki/January_2001_El_Salvador_earthquake","publisher":"Wikipedia"},{"title":"Hurricane Mitch","url":"https://en.wikipedia.org/wiki/Hurricane_Mitch","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"},{"title":"List of World Heritage Sites in Central America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_Central_America","publisher":"Wikipedia"}]},{"slug":"roofing-in-equatorial-guinea","title":"Roofing in Equatorial Guinea","category":"world-roofing","type":"place","country":{"name":"Equatorial Guinea","iso2":"GQ"},"summary":"Equatorial Guinea combines Spanish colonial buildings in Malabo and Bata with Fang villages centred on the abaá, a communal 'house of the word'.","body":"Equatorial Guinea consists of the mainland region of Río Muni, between Cameroon and Gabon, and the islands of Bioko (with the capital, Malabo) and Annobón in the Gulf of Guinea. It is a humid, rainy equatorial country. Its towns show strong Spanish colonial influence, while the Fang villages of the mainland are organised around the *abaá*, a communal house at the heart of the settlement. Little has been published specifically on the country's roofs.\n\n## Climate and hazards\n\nThe climate is equatorial, hot and very humid, with heavy rainfall. Roofs must shed intense rain and resist rot and corrosion; the coastal and island setting brings salt air.\n\n## Roofing history\n\nMany buildings in Bata on the mainland are in Spanish colonial style, though not always well maintained, and Malabo's architecture also shows Spanish influence. Malabo combines shantytowns and upper-class neighbourhoods, often close together.\n\nIn Fang towns, the *abaá* is the communal building. In the past, an abaá stood at each end of the settlement and served as a guard house; today it is usually built in the centre. It is built and maintained communally, and is used for official, religious and social purposes: men meet there to take decisions for the community, and it is also used for cooking and celebrations. A carved sacred column (*àbòm-àbàà*) once stood at its centre, and a hollow-log drum (*'nkúú*) was used to raise alarms and send messages. Other peoples of the country have equivalent buildings: *mwebe* (Ndowé), *mpa* (Bisío), *riebapuá* or *wedja bohôté* (Bubi) and *vidyil* (Fá d'Ambó).\n\n## Traditional and vernacular roofs\n\n- **Abaá**: the Fang communal house, its name meaning \"house of the word\".\n\n## Notable roofs\n\n- **Spanish colonial buildings** of Malabo and Bata.\n\n## Local roofing terms\n\n- *abaá* (Fang): communal \"house of the word\".\n- *mwebe* (Ndowé), *mpa* (Bisío), *riebapuá* (Bubi): equivalent community houses.\n\n## Sources and gaps\n\n**Village houses**: the construction and roofing materials of traditional Fang and Bubi houses were not documented in published sources. No national roof-material figures were found in published sources.\n\nSources on Equatorial Guinea's roofs are very limited. Roofing materials (for example palm thatch, timber shingles or metal sheet), census data, colonial-era roofing practice, codes and industry: published information is limited.","key_facts":[{"label":"Community building","value":"Abaá (Fang communal house)"},{"label":"Urban heritage","value":"Spanish colonial buildings in Malabo and Bata"},{"label":"Climate driver","value":"Equatorial rain and humidity"}],"regions":["Africa"],"aliases":["Equatoguinean roofing","roofs in Equatorial Guinea"],"related":["roofing-in-gabon","roofing-in-cameroon","roofing-in-sao-tome-and-principe","palm-thatch","corrugated-iron"],"sources":[{"title":"Abaá","url":"https://en.wikipedia.org/wiki/Aba%C3%A1","publisher":"Wikipedia"},{"title":"Culture of Equatorial Guinea","url":"https://www.everyculture.com/Cr-Ga/Equatorial-Guinea.html","publisher":"Countries and Their Cultures (everyculture.com)"}],"company":null},{"slug":"roofing-in-eritrea","title":"Roofing in Eritrea","category":"world-roofing","type":"place","country":{"name":"Eritrea","iso2":"ER"},"summary":"Eritrea's roofs range from flat soil-roofed hidmo stone houses and agudo round huts to the modernist concrete of Asmara, a World Heritage city since 2017.","body":"Eritrea runs from the Red Sea coast up to highlands where the capital, Asmara, stands at over 2,000 m (6,560 ft). Its rural houses traditionally had either flat soil roofs, on the stone hidmo, or conical thatch, on the round agudo. Asmara is a World Heritage city for its early 20th-century modernist architecture, which includes the cantilevered concrete wings of the Fiat Tagliero service station.\n\n## Climate and hazards\n\nThe highlands have a rainy season, while the coastal lowlands are hot and dry. A traditional soil roof needs a great deal of timber, and gathering wood is one of the biggest tasks in building a hidmo.\n\n## Roofing history\n\n**Traditional houses.** The hidmo, a rectangular house of hewn stone and mud, is found in the highlands and parts of the eastern escarpment. Its roof is made by laying beams on the walls and on interior timber posts, covering them with rods and branches, and spreading soil on top (see Hidmo). Round huts with thatched conical roofs are called *agudo* (see Tukul).\n\n**Asmara.** Asmara began as an Italian military outpost in the 1890s. Planning phases ran from 1893 to 1941, and a large construction programme followed after 1935. The resulting city combines eclectic and rationalist architecture on a grid adapted to the hilly site. UNESCO notes that, although modern materials and techniques were used, the buildings relied heavily on local methods, materials, skills and labour. Asmara was inscribed on the World Heritage List in July 2017.\n\nA widely known roof in the city is the Fiat Tagliero service station of 1938, designed by the Italian engineer Giuseppe Pettazzi. Its two reinforced-concrete cantilevered wings each reach about 15 m (49 ft). Local authorities reportedly demanded supporting pillars; according to the story, Pettazzi refused, and the wings have stood unsupported ever since.\n\n## Traditional and vernacular roofs\n\n- **Hidmo**: flat soil roof on branches, beams and interior posts.\n- **Agudo**: round hut with conical thatch.\n\n## Notable roofs\n\n- **Fiat Tagliero, Asmara** (1938): cantilevered concrete wings of about 15 m.\n- **Asmara's cinemas and public buildings**: the Impero, Roma, Odeon, Capitol and Hamasien cinemas and the post office on Segeneyti Street are among the listed modernist buildings.\n\n## Local roofing terms\n\n- **hidmo**: stone house with flat soil roof.\n- **agudo**: round thatched hut.\n- **dembe**: roofed animal shelter of the hidmo.\n\n## Sources and gaps\n\nNo national building or roofing code was found in published sources. No information on domestic roofing manufacturers was found.\n\nThe coral-stone and Ottoman-era buildings of Massawa, ancient sites such as Qohaito and Adulis, and modern roof-material statistics: published information is limited.","key_facts":[{"label":"Traditional forms","value":"Hidmo (flat soil roof), agudo (conical thatch)"},{"label":"Landmark","value":"Asmara: A Modernist African City (World Heritage, 2017)"},{"label":"Notable roof","value":"Fiat Tagliero (1938), 15 m cantilevered concrete wings"},{"label":"Climate driver","value":"Highland rains; extreme coastal heat"}],"regions":["Africa"],"aliases":["Eritrean roofing","roofing in Eritrea"],"related":["hidmo","tukul","flat-roof","thatch","roofing-in-ethiopia","roofing-in-sudan","roofing-in-djibouti"],"company":null,"sources":[{"title":"Asmara: A Modernist African City","url":"https://whc.unesco.org/en/list/1550/","publisher":"UNESCO World Heritage Centre"},{"title":"Fiat Tagliero Building","url":"https://en.wikipedia.org/wiki/Fiat_Tagliero_Building","publisher":"Wikipedia"},{"title":"Hidmo: A traditional house in Eritrean highlands","url":"https://www.africa-press.net/eritrea/?p=2883","publisher":"Africa-Press"},{"title":"African round hut","url":"https://en.wikipedia.org/wiki/African_round_hut","publisher":"Wikipedia"}]},{"slug":"roofing-in-estonia","title":"Roofing in Estonia","category":"world-roofing","type":"place","country":{"name":"Estonia","iso2":"EE"},"summary":"Estonian roofing: the tall thatched roof of the barn-dwelling (rehielamu), of reed or rye straw, over chimneyless log farmhouses, and modern steel and membrane roofs.","body":"Estonia's most distinctive traditional roof belongs to the *rehielamu*, the barn-dwelling that combined a threshing barn and a farmhouse under one roof. These long, chimneyless log buildings carried a massive thatched roof of reed or rye straw that could make up two thirds of the building's height. Few remain in use, and examples are preserved at the Estonian Open Air Museum. Modern Estonian buildings use the industrial coverings common across the Baltic and Nordic region.\n\n## Climate and hazards\n\nEstonia has a cool, humid climate with long winters, snow cover and frequent freeze-thaw cycles, and a windy Baltic coastline with many islands. Snow load and moisture are the main concerns for roofs; fire was the historic danger for thatched, chimneyless farmhouses.\n\n## Roofing history\n\nEstonian vernacular building grew from an agrarian tradition that scholars trace back about 4,000 years. Its most characteristic product, the barn-dwelling, placed the threshing barn and the family's living space under a single roof. By the 19th century, the typical farmhouse was a long, chimneyless log building with a high thatched roof.\n\nThe renewal of traditional roof ridges at the open-air museum is the subject of conservation research, such as a study of the ridge of the Ritsu barn-dwelling.\n\n## Traditional and vernacular roofs\n\n- **Rehielamu (barn-dwelling):** log walls about one third of the building's height under a thatched roof making up the other two thirds.\n- **Thatch materials:** reed or rye straw.\n- **Hip roofs:** old farm buildings typically had large hipped roofs, often at least twice as high as the visible wall, with eaves projecting well beyond the walls to shed rain and snow. A pitch of 45° or steeper was considered best for reed.\n- **Straw as fodder:** in inland regions, roof straw could be recycled as animal feed when fodder ran short in long winters.\n\n## Roofing today\n\nIn 2018 Estonia's National Heritage Board began offering support for restoring historic farm architecture.\n\n## Codes, standards and regulation\n\nAs an EU member, Estonia applies European product standards and the Eurocodes, including Eurocode 1, Part 1-3 for snow loads.\n\n## Notable roofs\n\n- **Estonian Open Air Museum**, with relocated barn-dwellings such as the Ritsu farmhouse.\n\n## Local roofing terms\n\n- *rehielamu* - barn-dwelling farmhouse\n- *rehemaja* - threshing-barn house\n\n## Sources and gaps\n\nCurrent Estonian roofing statistics, codes and information on manufacturers: published information is limited.","key_facts":[{"label":"Traditional roof","value":"Thatch of reed or rye straw"},{"label":"Building type","value":"Rehielamu (barn-dwelling)"},{"label":"Roof proportion","value":"About two thirds of building height (19th century)"}],"regions":["Europe"],"aliases":["Estonian roofing","roofs in Estonia"],"related":["thatch","water-reed-thatch","long-straw-thatch","roofing-in-latvia","roofing-in-finland","roofing-in-russia","metal-roofing"],"company":null,"sources":[{"title":"Estonian vernacular architecture","url":"https://en.wikipedia.org/wiki/Estonian_vernacular_architecture","publisher":"Wikipedia"},{"title":"Ritsu rehemaja katuseharja uuendamise planeerimisest Eesti Vabaõhumuuseumis","url":"https://ojs.utlib.ee/index.php/SV/article/view/26194","publisher":"University of Tartu (journal)"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"},{"title":"Estonian farmstead – a compass pointing to both the past and the future (M. Maruste)","url":"https://vana.ajakirimaja.ee/en/madli-maruste-estonian-farmstead-a-compass-pointing-to-both-the-past-and-the-future/","publisher":"Ajakirjade Kirjastus"}]},{"slug":"roofing-in-eswatini","title":"Roofing in Eswatini","category":"world-roofing","type":"place","country":{"name":"Eswatini","iso2":"SZ"},"summary":"Eswatini homes are overwhelmingly roofed with corrugated metal sheet; grass thatch survives on a small share of homes, including round thatched huts.","body":"Eswatini (formerly Swaziland) is a small, landlocked kingdom between South Africa and Mozambique. Round houses with conical grass-thatched roofs (rondavels) are among its traditional dwellings, and reeds remain culturally important, as in the annual Umhlanga reed dance. In modern housing, metal sheet roofs dominate.\n\n## Climate and hazards\n\nThe country spans highveld, middleveld and lowveld zones with summer rainfall and thunderstorms. Lightning and fire are the usual risks for thatched roofs in the region (see SANS 10407 thatched roof construction for South African practice).\n\n## Roofing history\n\nBorder Cave, just across the border in South Africa's Lebombo Mountains, contains grass bedding about 200,000 years old, among the oldest evidence of people preparing sleeping places under a rock shelter. By the 2014 household survey, metal sheet covered most homes.\n\n## Traditional and vernacular roofs\n\n- **Rondavel**: round house with a conical thatched roof, also found in Eswatini.\n\n## Roofing today\n\nIn the unweighted 2014 Multiple Indicator Cluster Survey sample (4,864 households with a recorded roof):\n\n| Main roof material (HC4) | Share of sampled households |\n|---|---|\n| Metal / tin (corrugated iron) | 86.0% |\n| Thatch / palm leaf | 7.3% |\n| Asbestos | 3.5% |\n| Ceramic tiles | 2.1% |\n| Cement / concrete | 0.7% |\n| Calamine / cement fibre and other | 0.4% |\n\nWalls in the same sample were mostly cement (67.7%) and cement blocks (10.2%), with sticks and mud on about 10%.\n\n## Notable roofs\n\n- **Ludzidzini Royal Village**: residence of the Queen Mother and venue of the annual Umhlanga (reed dance) ceremony.\n\n## Sources and gaps\n\nNo national roofing standard was identified. No information on domestic roofing manufacturers was found in published sources. No siSwati roofing terms were found.\n\nSurvey shares are unweighted sample counts. Documentation of Swazi beehive huts and thatching techniques, construction of royal-village huts and the 2017 census housing tables: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal sheet, 86.0% (MICS 2014 file, unweighted)"},{"label":"Traditional materials","value":"Grass thatch, saplings"},{"label":"Traditional form","value":"Beehive hut, rondavel"},{"label":"Climate driver","value":"Summer rainfall and thunderstorms"}],"regions":["Africa"],"aliases":["Swazi roofing","Swaziland roofing"],"related":["zulu-beehive-hut","rondavel","thatch","corrugated-iron","border-cave","roofing-in-southern-africa","roofing-in-south-africa","roofing-in-mozambique"],"company":null,"sources":[{"title":"Eswatini MICS 2014: Main material of roof (HC4)","url":"https://microdata.worldbank.org/catalog/3406/variable/F3/V364?name=HC4","publisher":"World Bank Microdata Library"},{"title":"Eswatini MICS 2014: Main material of exterior wall (HC5)","url":"https://microdata.worldbank.org/catalog/3406/variable/F3/V365?name=HC5","publisher":"World Bank Microdata Library"},{"title":"Ludzidzini Royal Village","url":"https://en.wikipedia.org/wiki/Ludzidzini_Royal_Village","publisher":"Wikipedia"},{"title":"Border Cave","url":"https://en.wikipedia.org/wiki/Border_Cave","publisher":"Wikipedia"}]},{"slug":"roofing-in-ethiopia","title":"Roofing in Ethiopia","category":"world-roofing","type":"place","country":{"name":"Ethiopia","iso2":"ET"},"summary":"Ethiopia's roofs range from Lalibela's rock-hewn churches and Tigray's soil-roofed hidmo to thatched tukuls; corrugated iron now rivals thatch.","body":"Ethiopia's highland civilisation has one of Africa's longest building records, from the stone architecture of Aksum and the rock-cut churches of Lalibela to the castles of Gondar. Ordinary houses traditionally had either thatched conical roofs, as on the round tukul, or flat roofs of earth on timber, as on the stone hidmo of Tigray. Corrugated iron has since spread widely, and in a 2011-2012 rural survey sample it covered almost as many homes as thatch.\n\n## Climate and hazards\n\nMuch of Ethiopia is high plateau with a main rainy season, cool nights and strong sun; the Afar and Somali lowlands are hot and dry. Roofs must shed seasonal heavy rain in the highlands. Timber scarcity has long shaped roof design: in the Ïnderta area of Tigray, wood was so scarce that using more of it raised a house's prestige.\n\n## Roofing history\n\n**Aksum.** The ruins of Aksum date from the 1st to the 13th centuries AD. Its tallest standing stele, over 23 m (75 ft) high, is carved to represent a nine-storey building, and a fallen stele of about 33 m (108 ft) may be the largest monolithic stele ever attempted. Ruins of 6th- and 7th-century palaces also survive.\n\n**Lalibela.** Tradition credits King Gebre Meskel Lalibela of the Zagwe dynasty (reigned c. 1181-1221) with the eleven churches of Lalibela, carved downward from scoriaceous basalt. Because each church is cut from the rock, its \"roof\" is the original rock surface. In 2008, temporary protective shelters funded by the European Union were placed over five of the churches (see Rock-Hewn Churches of Lalibela).\n\n**Gondar.** The fortress-city of Fasil Ghebbi was founded by Emperor Fasilides in the 17th century and built of brown basalt with wine-coloured tuff ornament. Its architecture blends Portuguese, Indian and Arab influences with later Baroque elements introduced by Jesuit missionaries; one account names an Indian architect, Abdal Kerim. Dawit's Hall was without a roof as of 2002.\n\n**Harar.** The walled town of Harar Jugol in the east, whose walls were built between the 13th and 16th centuries, has 82 mosques and 102 shrines. After 1887, Indian merchants added rectangular two-storey houses with wooden verandas.\n\n**20th century.** By 1984, Ethiopia's census used the categories corrugated iron, concrete or cement, wood and mud, thatch, reed or bamboo, and asbestos for urban households.\n\n## Traditional and vernacular roofs\n\n- **Tukul**: round house with walls of mud and poles and a conical thatched roof (see Tukul). The name *godjo* is also recorded.\n- **Hidmo**: rectangular stone house of Tigray and Eritrea with masonry walls, wooden ceilings and a flat soil roof; thick walls and roof keep indoor conditions stable (see Hidmo).\n- **Afar shelters**: portable huts of twigs and woven mats, moved by camel; settled Afar increasingly build wooden frames plastered with clay.\n- **Rock-cut roofs**: the churches of Lalibela and other rock-hewn churches.\n\n## Roofing today\n\nThe Ethiopian Rural Socioeconomic Survey 2011-2012 recorded the main roof material of about 3,900 rural and small-town households. Unweighted shares of sampled households (not official estimates) were:\n\n| Main roof material | Share of sampled households |\n|---|---|\n| Thatch | 45.2% |\n| Corrugated iron sheet | 42.5% |\n| Wood and mud | 6.5% |\n| Reed / bamboo | 2.2% |\n| Others | 1.8% |\n| Plastic canvas | 1.4% |\n| Concrete / cement | 0.5% |\n\nIn towns, corrugated iron is close to universal. In an urban job-seekers' impact-evaluation survey (2016-2020), corrugated iron sheet was recorded for 94.4% of 827 respondents' dwellings (unweighted). The Demographic and Health Survey (2016) also records roof material, with corrugated iron classed as a \"finished\" roof and thatch or mud as \"natural\".\n\n## Codes, standards and regulation\n\nBuilding regulation is set at federal level by the Ethiopian Building Proclamation No. 624/2009, with technical requirements published as Ethiopian Building Code Standards (EBCS) documents.\n\n## Notable roofs\n\n- **Rock-Hewn Churches of Lalibela**: World Heritage since 1978; EU-funded shelters since 2008.\n- **Fasil Ghebbi, Gondar**: 17th-century stone castles, World Heritage since 1979.\n- **Aksum**: stelae representing multi-storey buildings.\n- **Harar Jugol**: walled Islamic town with traditional Harari houses.\n\n## Local roofing terms\n\n- **tukul**: round thatched house.\n- **hidmo** (Tigrinya): flat-roofed stone house.\n- **chikka**: wood frame plastered with clay (Afar region usage).\n\n## Sources and gaps\n\nDetails of roofing provisions: published information is limited. No information on domestic roofing manufacturers was found in published sources.\n\nSurvey percentages are unweighted sample counts, mainly rural. National weighted roof shares from the 2007 census or DHS reports: published information is limited. Thatching traditions of southern Ethiopia (such as the Sidama and Dorze) were not found in published sources.","key_facts":[{"label":"Rural roofs (2011-12 survey sample, unweighted)","value":"Thatch 45.2%, corrugated iron 42.5%"},{"label":"Traditional forms","value":"Tukul (thatch), hidmo (flat soil roof), rock-cut churches"},{"label":"Building law","value":"Ethiopian Building Proclamation No. 624/2009"},{"label":"Landmark","value":"Rock-Hewn Churches of Lalibela (World Heritage, 1978)"}],"regions":["Africa"],"aliases":["Ethiopian roofing","roofing in Ethiopia"],"related":["tukul","hidmo","rock-hewn-churches-of-lalibela","corrugated-iron","thatch","conical-roof","flat-roof","mud-roof","roofing-in-east-africa","roofing-in-eritrea","roofing-in-somalia","roofing-in-djibouti","roofing-in-south-sudan","roofing-in-sudan"],"company":null,"sources":[{"title":"Ethiopian Rural Socioeconomic Survey 2011-2012: roof material of main dwelling (hh_s9q06)","url":"https://microdata.fao.org/index.php/catalog/1318/variable/V1868","publisher":"FAO Microdata Catalogue / Central Statistical Agency"},{"title":"Ethiopia Demographic and Health Survey 2016: main roof material (hv215)","url":"https://catalog.ihsn.org/catalog/7199/variable/F3/V99?name=hv215","publisher":"IHSN Survey Catalog"},{"title":"Ethiopia 1984 Population and Housing Census (IPUMS subset): roof material","url":"https://microdata.worldbank.org/catalog/2745/variable/ET1984A_ROOF","publisher":"World Bank Microdata Library"},{"title":"Rock-Hewn Churches, Lalibela","url":"https://en.wikipedia.org/wiki/Rock-Hewn_Churches,_Lalibela","publisher":"Wikipedia"},{"title":"Aksum","url":"https://whc.unesco.org/en/list/15/","publisher":"UNESCO World Heritage Centre"},{"title":"Fasil Ghebbi","url":"https://en.wikipedia.org/wiki/Fasil_Ghebbi","publisher":"Wikipedia"},{"title":"Harar Jugol, the Fortified Historic Town","url":"https://whc.unesco.org/en/list/1189/","publisher":"UNESCO World Heritage Centre"},{"title":"Fundamentals of Hïdmo in Ïnderta: A Traditional House Type in Tigray Region, Ethiopia","url":"https://www.jstage.jst.go.jp/article/niloethiopian/2019/24/2019_17/_article/-char/en","publisher":"Nilo-Ethiopian Studies (J-STAGE)"},{"title":"Research on traditional Afar architecture and construction of a hostel building (AfarEARTH)","url":"https://baugeschichte.tuwien.ac.at/website/afarearth/","publisher":"TU Wien, Research Unit of History of Architecture"},{"title":"Ethiopian Building Proclamation No. 624/2009","url":"https://www.metaappz.com/References/ethiopian_laws/federal/pr_624_2009/en/pdf","publisher":"Ethiopian federal laws reference"},{"title":"African round hut","url":"https://en.wikipedia.org/wiki/African_round_hut","publisher":"Wikipedia"}]},{"slug":"roofing-in-fiji","title":"Roofing in Fiji","category":"world-roofing","type":"place","country":{"name":"Fiji","iso2":"FJ"},"summary":"Fijian roofing: steep thatched bure and vale on raised bases, now almost entirely metal sheet, tested by Cyclone Winston in 2016.","body":"Fiji's traditional buildings were the *vale* (family house) and the *bure* (men's house), timber-framed and thatched, with components stacked and tied with rope. Today almost every household lives under a metal roof. The 2016 landfall of Tropical Cyclone Winston, the strongest storm then recorded in the Southern Hemisphere, made roof fixing and the cyclone performance of traditional houses central topics in Fijian building.\n\n## Climate and hazards\n\nFiji lies in the South Pacific cyclone belt and has a hot, humid maritime climate with heavy seasonal rain. Tropical Cyclone Winston, a Category 5 storm, made landfall on 20 February 2016, killed 44 people and caused severe damage to housing, agriculture and public buildings. Damage assessors reported widespread construction shortcuts such as incorrect strapping and flimsy foundations. Salt air near the coast shortens the life of metal sheet and fasteners.\n\n## Roofing history\n\nBefore European contact, Fijian houses were built from whatever local materials were available, with components stacked, tied with rope, or both. Ethnic Fijians distinguished two main house types: the vale, where families lived and cooked around hearth pits, and the bure, a men's house where initiated men of the clan met, ate and slept. Both were dark and smoky, without windows and usually with one low door. Earth floors were covered with grass or fern leaves and then with pandanus or coconut-leaf mats.\n\nAs elsewhere in the Pacific, corrugated iron spread with colonial trade, mission building and later aid programmes (see [spread of corrugated iron](/spread-of-corrugated-iron)). By the 21st century thatch had almost disappeared from household roofs, though traditional houses survive in villages such as Navala, and the word bure has been taken up by tourism to mean a detached resort bungalow.\n\n## Traditional and vernacular roofs\n\nThe [Fijian bure](/fijian-bure) is a widely known form. A study by Massey University researchers in the *International Journal of Disaster Risk Reduction* found that traditional bure share several features recommended internationally for cyclone resistance: relatively short walls, few wall openings, an elevated rock base and a steep hipped roof with small eaves. After Winston, residents of Navala said their traditional houses performed better than contemporary ones and that most damage came from debris blown off modern houses. The researchers noted that some villages appear to have lost traditional building knowledge.\n\n## Roofing today\n\nIn the 2021 Multiple Indicator Cluster Survey, 96.5% of household records listed metal, tin or corrugated iron as the main roof material; cement was 1.4% and wood planks about 1%, while thatch, palm or coconut leaf accounted for about 0.1%. These are unweighted case counts from the survey sample. The 2017 census counted 191,910 private households.\n\n## Codes, standards and regulation\n\nThe National Building Code of Fiji dates from 1990 and operates under the Public Health Act 1935 and the Public Health (National Building Code) Regulations 2004, with building permits regulated by a 2017 Act. A revision of the code with assistance from the Asian Development Bank began in 2023.\n\n## Notable roofs\n\nThatched village houses at Navala are among the best-known surviving examples of traditional Fijian roofing.\n\n## Local roofing terms\n\n- **Bure**: men's house; now also a tourist bungalow.\n- **Vale**: family dwelling house.\n- **Icili**: an older Fijian term the source suggests is more traditionally correct for a resort-style cabin.\n\n## Sources and gaps\n\nNo information on domestic roofing manufacturers was found in published sources.\n\n","key_facts":[{"label":"Dominant material today","value":"Metal/corrugated iron (96.5% of MICS 2021 household records)"},{"label":"Traditional materials","value":"Timber frame, thatch, rope lashing, raised rock base"},{"label":"Traditional houses","value":"Vale (family house), bure (men’s house)"},{"label":"Climate driver","value":"Tropical cyclones (TC Winston, 20 February 2016)"},{"label":"Building code","value":"National Building Code (1990), revision begun 2023"}],"regions":["Oceania"],"aliases":["Fijian roofing"],"related":["fijian-bure","corrugated-iron","spread-of-corrugated-iron","thatch","palm-thatch","hurricane-tie","wind-uplift","roofing-in-the-pacific-islands","roofing-in-tonga","roofing-in-samoa","roofing-in-vanuatu"],"company":null,"sources":[{"title":"Bure (Fiji)","url":"https://en.wikipedia.org/wiki/Bure_(Fiji)","publisher":"Wikipedia"},{"title":"Traditional knowledge key to building cyclone-resistant homes in Fiji","url":"https://www.scimex.org/newsfeed/traditional-knowledge-key-to-building-cyclone-resistant-homes-in-fiji","publisher":"Scimex"},{"title":"Fiji: Post-Disaster Needs Assessment - Tropical Cyclone Winston, February 2016","url":"https://www.gfdrr.org/en/publication/fiji-post-disaster-needs-assessment-tropical-cyclone-winston-february-2016","publisher":"GFDRR / World Bank"},{"title":"Half of Fiji houses will have to be rebuilt","url":"https://www.rnz.co.nz/international/pacific-news/298062/half-of-fiji-houses-will-have-to-be-rebuilt","publisher":"RNZ"},{"title":"Fiji MICS 2021, main material of roof (HC5)","url":"https://microdata.worldbank.org/catalog/5955/variable/V151","publisher":"World Bank Microdata Library"},{"title":"Fiji 2017 Population and Housing Census","url":"https://psro.dataforall.org/sites/default/files/2024-10/Fiji%202017%20Population%20and%20Housing%20Census.pdf","publisher":"Fiji Bureau of Statistics"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-finland","title":"Roofing in Finland","category":"world-roofing","type":"place","country":{"name":"Finland","iso2":"FI"},"summary":"Finnish roofing: birch-bark pole roofs, tarred shingles on wooden churches, Iron Age tar-making, and today's steel sheet roofs built for snow and frost.","body":"Finland's building tradition is one of log construction in a boreal forest, and its roofs followed suit: birch bark weighed down with poles, boards, turf and, later, tarred wooden shingles. Tar from Finnish pine forests was a major export for centuries. In the 20th century functionalist architects introduced flat roofs, and today profiled and seamed steel sheet is a very common covering on Finnish houses.\n\n## Climate and hazards\n\nRoofs must carry heavy snow for long winters, especially in the east and north, and survive frost and freeze-thaw. Fire repeatedly destroyed wooden towns: on average a Finnish wooden town burned every 30-40 years, and Oulu suffered fires in 1822 and 1824. After the great fire of Turku in 1827, Turku Cathedral was largely rebuilt in brick.\n\n## Roofing history\n\nCorner-timbered log construction has been common across the northern boreal zone since prehistoric times. The simplest Finnish building was the *kota*, a conical or tent-like dwelling covered with fabric, peat, moss or timber and still used by the Sámi in Lapland. The basic rectangular log building had a low-pitched saddle-back roof.\n\nTar was first produced in the Nordic countries during the Iron Age and was used above all to seal wooden boats. Large-scale tar production began in Finland in the early 17th century, when the country was part of Sweden, and by the late 17th century tar was the third most valuable export of the Swedish realm. Using tar on roof shingles is a later application of the same product.\n\nUntil the early 19th century the traditional Finnish roof was the *malkakatto*: wooden slats covered with several layers of birch bark, held down by long timber poles weighted with boulders, all left unpainted. Wooden shingles are a comparatively recent import, arriving in the early 19th century. Wooden churches of the 17th and 18th centuries, such as the Lapp Church at Sodankylä (about 1689) and Petäjävesi (1763-1765), show the steep saddle-back roofs of the period.\n\nFunctionalism brought the flat roof. Alvar Aalto's Paimio Sanatorium (completed 1933) used flat roofs with reinforced concrete and strip windows, and a 1931 co-operative office in Rauma had a roof terrace. After the Second World War, standard-design wooden houses for veterans (*rintamamiestalo*) were built in large numbers, and over 500 wooden houses of this type were delivered to the Soviet Union as war reparations between 1944 and 1948.\n\n## Traditional and vernacular roofs\n\n- **Malkakatto:** birch-bark roof weighted with poles and stones. See birch-bark roofing.\n- **Turf roofs:** used on log buildings across Finland and the Scandinavian peninsula, following the distribution of log construction.\n- **Shingle roofs:** thin wooden shingles, introduced in the early 19th century and today often coated with tar.\n- **Sauna and riihi:** early smoke saunas had no chimney; rocks were heated by burning wood for 6-8 hours and the smoke let out through a hatch. The threshing-drying barn (*riihi*) was another smoke-filled log building of the farm.\n\n## Roofing today\n\nSteel sheet in tile-profile and standing-seam forms is a very common roof on Finnish detached houses; at the 2023 Loviisa housing fair, almost all the exhibition houses had steel roofs. Concrete and clay tiles, bitumen felt and bitumen shingles are also used, and apartment and commercial buildings mostly have flat or low-slope membrane roofs.\n\n## Codes, standards and regulation\n\nBuilding requirements have been set by the Ministry of the Environment in the National Building Code of Finland (*Suomen rakentamismääräyskokoelma*), with structural loads including snow following the Eurocodes (Eurocode 1, Part 1-3 for snow).\n\n## Industry\n\n- **Ruukki**, the roofing and construction brand of Rautaruukki, founded by the Finnish state in 1960 and owned by SSAB since 2014, is a major producer of steel roofing in Finland and abroad. See Ruukki.\n- The Nordic membrane group Nordic Waterproofing operates in Finland. See Nordic Waterproofing.\n\n## Notable roofs\n\n- **Petäjävesi Old Church** (1763-1765), built by master builder Jaakko Leppänen, a UNESCO World Heritage Site with a steep roof recalling the Gothic tradition and a 13 m (43 ft) wooden vault inside.\n- **Kärsämäki Shingle Church** (1999-2004), designed by Anssi Lassila using 18th-century timber techniques and a shingle-clad exterior.\n- **Paimio Sanatorium** (1933), an early functionalist flat-roofed building.\n\n## Local roofing terms\n\n- *malkakatto* - birch-bark roof held down by poles\n- *kota* - Sámi/Finnish hut covered with fabric, peat, moss or timber\n- *riihi* - threshing-drying barn\n- *rintamamiestalo* - post-war veterans' house\n\n## Sources and gaps\n\nMarket shares for Finnish roofing materials were not found in official statistics; the observation on steel roofs at the 2023 Loviisa housing fair comes from a manufacturer's report.","key_facts":[{"label":"Traditional roof","value":"Malkakatto: birch bark held by poles"},{"label":"Shingles","value":"Arrived early 19th century, often tarred"},{"label":"Common modern covering","value":"Steel sheet"},{"label":"Building code","value":"National Building Code of Finland"},{"label":"UNESCO roof","value":"Petäjävesi Old Church (1763-1765)"}],"regions":["Europe","Arctic"],"aliases":["Finnish roofing","roofs in Finland"],"related":["birch-bark-roofing","scandinavian-sod-roofs","wood-shingle","metal-roofing","ruukki","nordic-waterproofing","flat-roof","roofing-in-sweden","roofing-in-russia","roofing-in-estonia","roofing-in-scandinavia"],"company":null,"sources":[{"title":"Architecture of Finland","url":"https://en.wikipedia.org/wiki/Architecture_of_Finland","publisher":"Wikipedia"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"},{"title":"Pine tar","url":"https://en.wikipedia.org/wiki/Pine_tar","publisher":"Wikipedia"},{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"},{"title":"Petäjävesi Old Church","url":"https://whc.unesco.org/en/list/584","publisher":"UNESCO World Heritage Centre"},{"title":"National Building Code of Finland 2012","url":"https://www.iea.org/policies/2512","publisher":"International Energy Agency"},{"title":"Almost half of the houses at Loviisa housing fair have Ruukki's modern steel roof","url":"https://www.ruukki.com/roofing/news/16-07-2023-almost-half-of-the-houses-at-loviisa-housing-fair-have-ruukki's-modern-steel-roof","publisher":"Ruukki"},{"title":"Paimio Sanatorium","url":"https://en.wikipedia.org/wiki/Paimio_Sanatorium","publisher":"Wikipedia"}]},{"slug":"roofing-in-france","title":"Roofing in France","category":"world-roofing","type":"place","country":{"name":"France","iso2":"FR"},"summary":"French roofing: interlocking and flat clay tiles, southern canal tiles, slate, Paris zinc and mountain lauzes, governed by NF DTU rules and ten-year liability.","body":"France has some of the most regionally varied roofing in Europe. Travelling across the country you see slate in Anjou, Brittany and the Ardennes, small flat clay tiles in Burgundy and the Paris basin, interlocking clay tiles almost everywhere, low-pitched curved canal tiles in the south, thick stone lauzes in the Cévennes and Causses, and the grey zinc roofs of Paris. Roofing work is framed by the NF DTU technical rules and by a strict ten-year liability and insurance regime.\n\n## Climate and hazards\n\nFrance spans an Atlantic west with frequent rain and wind, a continental east with colder winters, Alpine and Pyrenean mountains with heavy snow, and a dry, hot Mediterranean south. These differences are built into the rules: the NF DTU documents for pitched roofs set minimum pitches according to climatic zone, site exposure and rafter length, so the same tile can need a steeper pitch in Brittany than in Provence. The low-pitched canal tile suits the south's light rainfall, while mountain roofs carry heavy stone or slate that holds snow.\n\n## Roofing history\n\nIn Gallo-Roman times, slate from the Ardennes was used mostly for flooring rather than roofs. In the Middle Ages slate from the Ardennes travelled far: in 1156 the abbey of Saint-Trond in present-day Belgium was reportedly roofed with slate from Fumay on the French Meuse. Prestige buildings were covered in sheet lead; the 13th-century oak roof structure of Notre-Dame de Paris, known as \"the forest\", carried more than 400 tonnes of lead on roof and spire.\n\nThe mansard roof, named after the architect François Mansart, first appeared around 1550 at the Louvre. A 1783 rule limiting Paris buildings to 20 m (66 ft) at the cornice made rooms inside steep roofs valuable, and under the Second Empire (1852-1870) the rebuilding of Paris by Baron Haussmann spread zinc-and-slate mansards along the new boulevards.\n\nFrance was central to the industrial clay tile. The Gilardoni brothers of Altkirch in Alsace patented a practical interlocking tile in 1841, and their factories ran until 1974. The Marseille pattern followed in the 1860s and was exported across the French colonies and beyond.\n\n## Traditional and vernacular roofs\n\n- ***Tuiles plates*** (flat tiles), small double-lap tiles of Burgundy, the Île-de-France and other northern regions.\n- ***Tuiles canal*** or ***tuiles romanes***, curved tiles on low-pitched roofs around the Mediterranean and in the south-west.\n- **Ardoise** (slate), traditional in Anjou and the Loire valley, the Ardennes, Brittany and Savoie. French slating uses a small range of rectangular formats, about 10-15 in total and usually two or three in any region, split about 2.5-4 mm (0.1-0.16 in) thick.\n- **Lauzes**, stone slabs of schist or limestone in the Cévennes, the Causses and other upland areas. On the limestone Causses, where timber was scarce, lauzes were often laid directly on stone vaults.\n- **Thatch** (*chaume*), which survives in parts of Normandy and the Brière marshes.\n- **Zinc**, typical of Paris; about 80% of Paris rooftops are covered in zinc.\n\n## Roofing today\n\nInterlocking clay tiles are the most common covering on French houses, with concrete tiles, flat clay tiles and canal tiles used according to region. France is described as the largest consumer of natural roofing slate and the largest buyer of Spanish slate, as domestic quarrying has declined. Zinc and copper standing seam are common on contemporary architecture. Flat roofs on commercial and apartment buildings use bitumen and synthetic membranes, and a 2015 law requires roofs of new buildings in commercial zones to be partly covered with plants or solar panels.\n\n## Codes, standards and regulation\n\nRoofing work follows the NF DTU (*documents techniques unifiés*) series, whose secretariat is held by the Centre Scientifique et Technique du Bâtiment (CSTB). The DTU 40 series covers pitched coverings: for example DTU 40.11 natural slate, 40.21 interlocking clay tiles, 40.23 flat clay tiles, 40.24 concrete tiles and 40.41 zinc. Products outside the DTUs are usually assessed through a CSTB *Avis Technique*. Under the 1978 Spinetta law, reflected in Article 1792 of the Civil Code, builders are liable for ten years for serious defects (the *garantie décennale*), must carry liability insurance, and owners must hold *dommages-ouvrage* insurance.\n\n## Industry\n\nTerreal, whose oldest predecessor dates from 1855, is a leading French clay tile maker and has belonged to the Austrian group Wienerberger since 2024. The rolled-zinc trade grew from the Belgian Vieille-Montagne company, founded in 1837, whose building zinc continues under the VMZinc brand. In 2024 the skills of Parisian roofers and ornamentalists were added to UNESCO's Representative List of the Intangible Cultural Heritage of Humanity.\n\n## Notable roofs\n\n- **Notre-Dame de Paris**, whose oak-and-lead roof and spire burned on 15 April 2019 and were rebuilt in oak and lead; the cathedral reopened on 7 December 2024.\n- **The roofs of Paris**, the zinc and slate Haussmann roofscape, proposed for World Heritage listing since 2014.\n- **The Causses and the Cévennes**, inscribed on the UNESCO World Heritage List on 28 June 2011 as an evolving cultural landscape; lauze roofs are a defining feature of its farms and villages.\n\n## Local roofing terms\n\n- *Couvreur*: roofer; *zingueur*: zinc worker.\n- *Tuile mécanique*: interlocking tile; *tuile plate*: flat tile; *tuile canal*: curved tile.\n- *Lauzier*: lauze roofer.\n- *Pureau*: the exposed part of a slate, tile or lauze.\n- *Noue*: valley; *faîtage*: ridge; *arêtier*: hip.\n- *Brisis* and *terrasson*: the steep lower and shallow upper slopes of a mansard.\n- *Volige* or *douelle*: boarding under slates or lauzes.\n\n## Sources and gaps\n\nNational statistics on the share of each roof covering in French housing: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Interlocking clay tile (tuile mécanique)"},{"label":"Traditional materials","value":"Flat and canal clay tiles, slate, lauze, thatch, zinc"},{"label":"Interlocking tile patent","value":"Gilardoni brothers, Altkirch, 1841"},{"label":"Building rules","value":"NF DTU series (DTU 40 for pitched roofs)"},{"label":"Liability","value":"Ten-year garantie décennale (Spinetta law, 1978)"},{"label":"Paris rooftops in zinc","value":"About 80%"}],"regions":["Europe"],"aliases":["French roofing","Toitures en France","Couverture en France"],"related":["dtu-40-series","garantie-decennale","zinc-roofs-of-paris","couvreur-zingueur","lauze","interlocking-clay-tile","spanish-tile","natural-slate","mansard-roof-history","notre-dame-de-paris-roof-fire","french-green-roof-law","terreal","ardennes-slate","roofing-in-belgium","roofing-in-spain","roofing-in-switzerland","zinc-roofing"],"company":null,"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Document technique unifié","url":"https://fr.wikipedia.org/wiki/Document_technique_unifi%C3%A9","publisher":"Wikipédia"},{"title":"Verriers, forains, couvreurs : trois pratiques du patrimoine immatériel à l'honneur","url":"https://www.culture.gouv.fr/actualites/verriers-forains-couvreurs-trois-pratiques-du-patrimoine-immateriel-a-l-honneur","publisher":"Ministère de la Culture"},{"title":"French construction law: make sure you are insured","url":"https://larevue.squirepattonboggs.com/french-construction-law-make-sure-you-are-insured_a1800.html","publisher":"Squire Patton Boggs"},{"title":"Expo Lauze","url":"https://www.lozere.gouv.fr/index.php/contenu/telechargement/9273/57500/file/Expo_Lauze.pdf","publisher":"Préfecture de la Lozère"},{"title":"Dachschiefer","url":"https://de.wikipedia.org/wiki/Dachschiefer","publisher":"Wikipedia (German)"},{"title":"Altdeutsche Deckung","url":"https://de.wikipedia.org/wiki/Altdeutsche_Deckung","publisher":"Wikipedia (German)"},{"title":"Notre-Dame fire","url":"https://en.wikipedia.org/wiki/Notre-Dame_fire","publisher":"Wikipedia"},{"title":"Mansard roof","url":"https://en.wikipedia.org/wiki/Mansard_roof","publisher":"Wikipedia"},{"title":"L'extraction des ardoises en suivant le fil historique","url":"https://gsb.naturalsciences.be/wp-content/uploads/2026/03/2-1-Lextraction-des-ardoises-en-suivant-le-fil-historique.pdf","publisher":"Geological Survey of Belgium"},{"title":"Terreal","url":"https://fr.wikipedia.org/wiki/Terreal","publisher":"Wikipédia"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"}]},{"slug":"roofing-in-gabon","title":"Roofing in Gabon","category":"world-roofing","type":"place","country":{"name":"Gabon","iso2":"GA"},"summary":"Gabon's cheapest village houses are mud under palm fronds; brick and cinder-block houses take corrugated metal roofs, and Baka camps use leaf domes.","body":"Gabon is a heavily forested equatorial country on the Atlantic coast, with its capital at Libreville. Rural building has traditionally been light and impermanent. The most economical village houses are made of mud and covered with palm fronds; others are built of wood, bark or brick, and brick houses are usually plastered with cement and roofed with corrugated metal. Cement and concrete block are associated with wealth and with government buildings.\n\n## Climate and hazards\n\nGabon has a hot, humid equatorial climate with heavy rainfall and a short dry season. Roofs must shed frequent downpours, and organic materials decay rapidly; metal roofs gain heat in the strong sun and corrode in the salty air of the coast.\n\n## Roofing history\n\nBaka forest people build dome-shaped leaf huts (*móngulu*) in forest camps. Village architecture traditionally centred on family houses, separate kitchen huts and men's meeting houses. Cement is regarded as a sign of wealth and is used for government buildings, while mud, bark and palm fronds remain in use for cheaper homes.\n\n## Traditional and vernacular roofs\n\n- **Mud house with palm-frond roof**: the most economical rural dwelling.\n- **Wood and bark houses** in forest villages.\n- **Kitchen hut (*cuisine*)**: a separate building for each wife, built by men, lined with bamboo beds.\n- **Men's meeting house (*corps de garde*)**: an open structure with walls only waist-high, open to the roof, with benches around a central fire.\n- **Móngulu**: Baka leaf dome (see Mongulu).\n\n## Roofing today\n\nBrick houses are often coated with cement and roofed with corrugated metal, and wealthier families build with cinder (concrete) blocks. In Libreville, buildings designed by Gabonese architects are considered distinguishable from those by foreign architects.\n\n## Local roofing terms\n\n- *corps de garde* (French, local usage): open-sided men's meeting house.\n- *cuisine* (French, local usage): kitchen hut.\n\n## Sources and gaps\n\nPublished histories of Gabonese roofing are scarce. No national roof-material figures were found in published sources. No individually documented landmark roofs were identified.\n\n Fang house construction and roofing, national survey data, codes and industry are not documented in published sources.","key_facts":[{"label":"Cheapest rural house","value":"Mud walls, palm-frond roof"},{"label":"Permanent houses","value":"Brick or cinder block with corrugated metal roofs"},{"label":"Forest tradition","value":"Baka móngulu leaf domes"},{"label":"Climate driver","value":"Equatorial rain and humidity"}],"regions":["Africa"],"aliases":["Gabonese roofing","roofs in Gabon"],"related":["palm-thatch","mongulu","corrugated-iron","thatch","roofing-in-equatorial-guinea","roofing-in-cameroon","roofing-in-the-republic-of-the-congo","roofing-in-sao-tome-and-principe"],"sources":[{"title":"Culture of Gabon","url":"https://www.everyculture.com/Cr-Ga/Gabon.html","publisher":"Countries and Their Cultures (everyculture.com)"},{"title":"Pygmy camp with leaf and bark huts","url":"https://pygmies.org/baka/camps.php","publisher":"pygmies.org"}],"company":null},{"slug":"roofing-in-georgia","title":"Roofing in Georgia","category":"world-roofing","type":"place","country":{"name":"Georgia","iso2":"GE"},"regions":["Europe","Middle East"],"company":null,"summary":"Georgian roofing: corbelled timber darbazi roofs, conical church domes on tall drums, and the stone tower houses of Svaneti.","aliases":["Georgian roofing","Roofs of Georgia (country)","Sakartvelo roofing"],"body":"Georgia, in the South Caucasus between the Black Sea and the Caspian, has two roofing traditions that stand out internationally: the *darbazi* house with its stepped, corbelled timber roof, and the medieval church with a conical dome raised on a tall drum. In the high Caucasus, Svaneti's stone tower houses add a third distinctive form.\n\n## Climate and hazards\n\nGeorgia runs from the humid Black Sea lowlands in the west to drier, continental Kakheti in the east and the snowy Greater Caucasus in the north. Mountain villages such as those of Upper Svaneti sit on slopes beneath snow-covered peaks, so roofs there must carry snow. The region is earthquake-prone.\n\n## Roofing history\n\n**Classical antiquity.** The Roman writer Vitruvius, in the 1st century BC, described a dwelling of Colchis (western Georgia) made of stacked timber, often cited as the ancient prototype of the darbazi.\n\n**Early churches.** Most Georgian churches before the 9th century were basilicas. Tsromi church dates to the 7th century.\n\n**Cross-dome churches.** From the 9th century Georgian builders developed the cross-dome church, with a conical dome raised high on a drum (tholobate) over a rectangular or cross-shaped plan. Pillars were introduced to carry the drum. In the 11th century windows were added to domes and walls to light the frescoes; drums typically had twelve windows, and from St Saba's Church onward sixteen (eight real, eight blind). Domes became heavier-looking in the 13th century and drums stumpier in the 14th, as at Gergeti Trinity, Zarzma and Chulevi. Svetitskhoveli and Samtavro (11th century) and Ikorta (12th century) are dated examples.\n\n**Vernacular continuity.** The darbazi continued to be built into the 20th century.\n\n## Traditional and vernacular roofs\n\n- **Darbazi:** a house whose main room is covered by a *gvirgvini*, a stepped pyramidal vault of hewn logs and beams that narrows to a central opening serving as both window and smoke outlet. It rests on pillars, with a central *deda-bodzi* (\"mother pillar\") bearing much of the load. Common in Kartli, Kakheti and Samtskhe-Javakheti. See darbazi.\n- **Svan tower houses:** in Upper Svaneti, defensive towers of three to five floors taper toward the top as their walls thin, attached to two-storey houses whose ground floor sheltered people and animals. Chazhashi village alone preserves more than 200 medieval tower houses, churches and castles.\n- **Church roofs:** conical domes on drums over cross-shaped roofs.\n\n## Notable roofs\n\n- **Upper Svaneti** (UNESCO): tower houses of Ushguli-Chazhashi.\n- **Svetitskhoveli Cathedral**, Mtskheta (11th century): cross-dome church.\n- **Gergeti Trinity Church** (14th century): stumpy-drummed dome in a high mountain setting.\n- **Darbazi houses** of Kartli and Kakheti.\n\n## Local roofing terms\n\n- *darbazi* - house type with a corbelled timber lantern roof (from Persian *darvāze*, \"gate\")\n- *gvirgvini* - the stepped corbelled log vault\n- *deda-bodzi* - \"mother pillar\", the central timber post\n\n## Sources and gaps\n\nDetailed climate data for roofing, data on current roofing materials in Georgian housing, information on modern roofing practice, codes and industry, and descriptions of the roof coverings of Svan towers and churches were not found in published sources.","key_facts":[{"label":"Vernacular roof","value":"Darbazi corbelled log roof (gvirgvini)"},{"label":"Church form","value":"Conical dome on tall drum (from 9th century)"},{"label":"Mountain type","value":"Svan defensive tower houses"},{"label":"Ancient record","value":"Vitruvius on Colchian log houses (1st century BC)"}],"related":["darbazi","roofing-in-armenia","roofing-in-azerbaijan","roofing-in-turkey","roofing-in-russia","dome","earthquake-roofing"],"sources":[{"title":"Darbazi","url":"https://en.wikipedia.org/wiki/Darbazi","publisher":"Wikipedia"},{"title":"Architecture of Georgia (country)","url":"https://en.wikipedia.org/wiki/Architecture_of_Georgia_(country)","publisher":"Wikipedia"},{"title":"Upper Svaneti","url":"https://whc.unesco.org/en/list/709","publisher":"UNESCO World Heritage Centre"}]},{"slug":"roofing-in-germany","title":"Roofing in Germany","category":"world-roofing","type":"place","country":{"name":"Germany","iso2":"DE"},"summary":"German roofing: Biberschwanz and interlocking clay tiles, concrete tiles, Mosel slate, northern reed thatch, green roofs and a regulated roofers' craft.","body":"Germany has a large, highly organised roofing trade with a strong craft tradition. Steep pitched roofs covered in clay or concrete tiles dominate housing; slate is traditional in the central uplands between the Rhine and the Mosel and in Thuringia; reed thatch survives on the North Sea and Baltic coasts; and wooden shingles remain part of the Black Forest and Alpine landscape. Germany also pioneered the modern green roof and is home to some of Europe's largest tile and zinc manufacturers.\n\n## Climate and hazards\n\nGermany's temperate climate becomes more maritime in the north-west and more continental and snowy towards the south and east, with heavy snow loads in the Alps and higher uplands. Snow and wind loads are calculated using the Eurocodes with German national annexes. Fire shaped historic roofing: soft coverings of straw, reed and wood gave way in towns to tile, slate and metal, and the great Hamburg fire of 1842 created a large market for imported Welsh slate during rebuilding. In cities, stormwater from sealed roofs drove the spread of green roofs from the 1970s.\n\n## Roofing history\n\nThatch and reed are among the oldest roof coverings in the region; the Viking-age trading town of Hedeby in what is now Schleswig-Holstein very likely had thatched roofs, and in the Middle Ages hipped roofs of straw bundles sealed with clay were common. In forested regions wooden roofs were used from the earliest settlement, the oldest form being the *Legschindeldach*, loose boards held down with poles and stones.\n\nRoman builders roofed buildings on the Rhine and Mosel with slate laid to fixed rules, and the two-part curved *Mönch und Nonne* (\"monk and nun\") tiles continued Roman practice into the Middle Ages. The flat *Biberschwanz* (beaver-tail) tile probably originated in the 14th century around Nuremberg, where medieval examples survive on the city wall and castle. The slate-roofing craft reached a high point in the Middle Ages.\n\nIndustrialisation brought new products. Adolph Kroher developed concrete roof tiles in the 1840s after a visit to Grassau in Bavaria. Wilhelm Ludowici developed an interlocking clay tile in 1881 that became a model for interlocking tiles in many countries. In 1954 Braas introduced the *Frankfurter Pfanne*, which became the most widely laid concrete tile in Germany. Rheinzink was founded in 1966 to make titanium-zinc sheet for roofing and drainage.\n\nLightweight green roof systems were developed in Germany in the 1960s, and the FLL (Landscape Research, Development and Construction Society), founded in 1975, produced guidelines that are used worldwide; it issued the 2018 edition of its Green Roof Guideline.\n\n## Traditional and vernacular roofs\n\n- **Biberschwanz tiles**, laid in crown lay (*Kronendeckung*, two tiles per batten), double lay (*Doppeldeckung*) or single lay with wooden splints (*Spließdeckung*). The standard German format is 36.5 by 15.5 cm (about 14.4 by 6.1 in). They are typical of southern and eastern Germany, rare in the west and common in Mecklenburg.\n- **Slate** (*Schiefer*), traditional between the Mosel and the Rhine, in the Hunsrück, Eifel, Sauerland and Thuringia. The *Altdeutsche Deckung*, with graded stones laid in rising courses, is regarded as the most demanding German slating method.\n- **Reed thatch** (*Reetdach*), mainly in northern Germany, where it is still built today.\n- **Wooden shingles** (*Schindeln*) of spruce and larch in Alpine areas and of oak or beech in central Germany.\n- **Lead and copper** on churches and public buildings; few historic lead roofs survive.\n\n## Roofing today\n\nClay and concrete tiles are the dominant coverings on pitched roofs, laid over battens with a secondary underlay. German slating uses a far wider range of shapes than other countries, around 250 formats, typically split 4-6 mm (about 0.16-0.24 in) thick. Flat roofs use bituminous and synthetic membranes. Reference sources estimate that about 10% of German roofs have been greened and that roughly 10 million m² (about 108 million ft²) of new green roofs are built each year, about three-quarters of them extensive. Requirements for green roofs are set locally, and many cities have adopted them since the early 2000s.\n\n## Codes, standards and regulation\n\nRoofing work follows the technical rules of the German roofers' federation ZVDH (the *Fachregeln*), together with DIN and EN standards such as DIN 4108 for thermal and moisture protection. The ZVDH rules are widely treated as the recognised rules of good practice and are used in contracts and by expert witnesses. Roofer (*Dachdecker*) is a regulated craft: training takes three years in the dual system of workplace and vocational school, with specialisation in the third year in roof covering, waterproofing, wall cladding, energy technology or thatching, and the master craftsman qualification (*Meister*) is the basis for running an independent roofing business.\n\n## Industry\n\nThe ZVDH, founded in 1949 and based in Cologne, represents about 6,700 member companies with combined turnover of roughly EUR 10 billion (2024). In 2013 about 54,371 people worked as roofers in employment subject to social insurance, and in 2017 there were 6,651 roofing apprentices. Manufacturers include Braas (part of BMI Group), the clay tile maker Creaton (Wertingen, Bavaria, since 2024 part of Wienerberger) and Rheinzink (Datteln). In 2008-2009 the Federal Cartel Office fined Creaton and other tile manufacturers a combined EUR 188 million for price-fixing. Roofing is showcased at trade fairs such as DACH+HOLZ International and BAU in Munich.\n\n## Notable roofs\n\n- **Munich Olympic Park**, whose cable-net roof of acrylic glass by Behnisch & Partner with Frei Otto was completed in 1972.\n- **Nuremberg and Bamberg**, whose old towns are known for steep Biberschwanz roofscapes.\n- **Fell Exhibition Slate Mine** near Trier, presenting the Mosel slate industry.\n\n## Local roofing terms\n\n- *Dachdecker*: roofer; *Leyendecker*: slate roofer in the central uplands.\n- *Biberschwanz*: beaver-tail tile; *Mönch und Nonne*: monk-and-nun tiles.\n- *Dachpfanne*: pantile or interlocking tile.\n- *Reetdach*: reed-thatched roof.\n- *Schindel*: wooden shingle.\n- *Gebinde*: a course of slates.\n\n## Sources and gaps\n\nNational housing statistics on roof coverings: published information is limited.","key_facts":[{"label":"Dominant materials today","value":"Clay and concrete tiles"},{"label":"Traditional materials","value":"Biberschwanz tile, slate, reed thatch, wooden shingles"},{"label":"Interlocking clay tile","value":"Ludowici, 1881"},{"label":"Concrete tile origin","value":"Adolph Kroher, 1840s"},{"label":"Trade rules","value":"ZVDH Fachregeln with DIN/EN standards"},{"label":"Green roofs","value":"About 10% of roofs; about 10 million m² new per year"}],"regions":["Europe"],"aliases":["German roofing","Dachdeckung in Deutschland"],"related":["beaver-tail-tile","altdeutsche-deckung","german-roofing-slate","zvdh","zvdh-fachregeln","green-roofs-in-germany","dutch-and-danish-reed-thatch","schindel","concrete-roof-tile","interlocking-clay-tile","braas","creaton","rheinzink","munich-olympic-stadium-roof","roofing-in-austria","roofing-in-switzerland","roofing-in-the-netherlands","green-roof","natural-slate"],"company":null,"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Historische Dachdeckungen","url":"https://www.baunetzwissen.de/altbau/fachwissen/dach-deckungen/historische-dachdeckungen-2949105","publisher":"Baunetz Wissen"},{"title":"Biberschwanzziegel","url":"https://de.wikipedia.org/wiki/Biberschwanzziegel","publisher":"Wikipedia (German)"},{"title":"Dachschiefer","url":"https://de.wikipedia.org/wiki/Dachschiefer","publisher":"Wikipedia (German)"},{"title":"Altdeutsche Deckung","url":"https://de.wikipedia.org/wiki/Altdeutsche_Deckung","publisher":"Wikipedia (German)"},{"title":"Dachdecker","url":"https://de.wikipedia.org/wiki/Dachdecker","publisher":"Wikipedia (German)"},{"title":"Zentralverband des Deutschen Dachdeckerhandwerks","url":"https://de.wikipedia.org/wiki/Zentralverband_des_Deutschen_Dachdeckerhandwerks","publisher":"Wikipedia (German)"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"},{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"},{"title":"Creaton","url":"https://de.wikipedia.org/wiki/Creaton","publisher":"Wikipedia (German)"},{"title":"Braas Monier","url":"https://en.wikipedia.org/wiki/Braas_Monier","publisher":"Wikipedia"},{"title":"Dachbegrünungsrichtlinien","url":"https://www.baunetzwissen.de/flachdach/fachwissen/richtlinien-verordnungen/dachbegruenungsrichtlinien-221785","publisher":"Baunetz Wissen"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"}]},{"slug":"roofing-in-ghana","title":"Roofing in Ghana","type":"place","country":{"name":"Ghana","iso2":"GH"},"summary":"Ghana's roofs are overwhelmingly metal sheet today, replacing palm and grass thatch; the 2021 census also records asbestos, concrete and earth roofs.","body":"Ghana stretches from a humid Atlantic coast and forest belt in the south to dry savanna in the north. Traditional roofs followed that gradient, with steep palm-frond and grass thatch over earth or wattle-and-daub walls in the forest zone, and earth or thatch in the savanna. In the 21st century the country is roofed almost entirely in metal sheet: in the public sample of the 2021 Population and Housing Census, more than four in five people lived in buildings with metal-sheet roofs.\n\n## Climate and hazards\n\nThe south has two rainy seasons and high humidity, which rot organic roofing and encourage mould and termites. The north has one rainy season, a long dry season and the dusty harmattan wind. Heat gain through thin metal roofs is a comfort issue across the country, and coastal buildings face salt-laden air that shortens the life of uncoated steel.\n\n## Roofing history\n\nThe best-documented historic roofs are those of the Asante kingdom, centred on Kumasi, which flourished in the 18th and 19th centuries. Drawings made by Thomas Bowdich in 1817 record its architecture. The surviving Asante shrine houses were originally covered with steeply pitched palm-frond thatch over walls of timber, bamboo and earth. In 12 of the 13 buildings UNESCO recorded, the thatch was later replaced with lighter, shallower corrugated iron, a small-scale picture of the shift that took place across the country during the colonial period and after independence in 1957.\n\n## Traditional and vernacular roofs\n\n- **Asante shrine houses**: rooms around courtyards on raised plinths, with steep palm-frond thatch and earth walls decorated with bas-reliefs (see Asante traditional buildings).\n- **Thatch**: in the 2021 census sample, about 3% of people still lived under thatch, palm-leaf or raffia roofs, and a small share under bamboo.\n- **Earth roofs**: about 1.5% lived under mud or earth roofs.\n\n## Roofing today\n\nThe 2021 census asked for the main material used for the roof. In the census's 10% public microdata file (about 3 million person records, unweighted), the distribution was:\n\n| Main roof material | Share of persons |\n|---|---|\n| Metal sheet | 82.8% |\n| Slate/asbestos | 8.2% |\n| Thatch/palm leaves or raffia | 3.2% |\n| Cement/concrete | 3.1% |\n| Mud/mud bricks/earth | 1.5% |\n| Wood | 0.6% |\n| Roofing tiles | 0.4% |\n| Bamboo | 0.2% |\n\nThese are counts of people in the sample file rather than official weighted tables of dwellings. The 2017-18 Multiple Indicator Cluster Survey gives a similar picture at household level: in its file of about 13,200 households, 80.4% had metal, tin or corrugated iron roofs, 7.0% slate/asbestos, 4.4% thatch, palm leaf or raffia, 1.9% roofing shingles, 1.3% cement and 1.1% earth (unweighted counts). The second-largest category, \"slate/asbestos\", covers sheet roofing other than metal, while roofing tiles of any kind remain rare.\n\n## Codes, standards and regulation\n\nGhana's first comprehensive building code, the Ghana Building Code (GS 1207:2018), was launched in 2018. It was prepared by a 22-member technical team drawn from the Ministry of Works and Housing, the Ministry of Trade and Industry, the Ghana Institution of Engineers, the surveyors' and architects' institutes, the CSIR Building and Road Research Institute and the Ghana Standards Authority. It has 38 sections covering planning, design and construction of residential and non-residential buildings. The Ghana Standards Authority publishes and sells the code, and copies were distributed to metropolitan, municipal and district assemblies.\n\n## Industry\n\nGhana has local roll-forming and roofing-sheet businesses, and the cement industry publicly endorsed the 2018 building code.\n\n## Notable roofs\n\n- **Asante Traditional Buildings** near Kumasi, on the UNESCO World Heritage List since 1980: rare surviving examples of the Asante thatched shrine house, most now under corrugated iron.\n\n## Local roofing terms\n\n- **metal sheet**: the census term for corrugated or profiled metal roofing.\n- **raffia**: raffia-palm leaves, recorded as a thatch material in the census.\n\n## Sources and gaps\n\nDetails of individual roofing manufacturers: published information is limited.\n\nThese census figures come from the public 10% sample file and are unweighted; Ghana Statistical Service housing reports would give official dwelling-level shares. ","key_facts":[{"label":"Dominant material today","value":"Metal sheet (82.8% of persons, 2021 census sample)"},{"label":"Second material","value":"Slate/asbestos, 8.2% (2021 census sample)"},{"label":"Traditional materials","value":"Palm-frond and grass thatch, earth"},{"label":"Climate driver","value":"Heavy tropical rain (south), heat, harmattan (north)"},{"label":"Building code","value":"Ghana Building Code GS 1207:2018"}],"regions":["Africa"],"aliases":["Ghanaian roofing","roofing in Ghana"],"related":["roofing-in-west-africa","asante-traditional-buildings","corrugated-iron","corrugated-fibre-cement-sheet","palm-thatch","thatch","roofing-in-togo","roofing-in-cote-divoire","roofing-in-burkina-faso"],"sources":[{"title":"2021 Population and Housing Census: main material used for the roof (NEWH03)","url":"https://microdata.statsghana.gov.gh/index.php/catalog/110/variable/V643","publisher":"Ghana Statistical Service"},{"title":"MICS 2017-2018 Ghana: main material of roof (HC5)","url":"https://microdata.worldbank.org/catalog/4156/variable/F5/V1000?name=HC5","publisher":"World Bank Microdata Library / Ghana Statistical Service"},{"title":"Asante Traditional Buildings","url":"https://whc.unesco.org/en/list/35/","publisher":"UNESCO World Heritage Centre"},{"title":"Asante Traditional Buildings","url":"https://en.wikipedia.org/wiki/Asante_Traditional_Buildings","publisher":"Wikipedia"},{"title":"Ghana launches its first ever building code","url":"https://www.theconstructionindex.co.uk/news/view/ghana-launches-its-first-ever-building-code","publisher":"The Construction Index"},{"title":"GSA presents copies of Ghana Building Code book to MMDAs in 3 northern regions","url":"https://www.graphic.com.gh/news/general-news/gsa-presents-copies-of-ghana-building-code-book-to-mmdas-in-3-northern-regions.html","publisher":"Graphic Online"},{"title":"Coming soon: Ghana's Building Code GS 1207:2018","url":"https://www.gsa.gov.gh/2018/10/coming-soon-ghanas-building-code-gs-12072018/","publisher":"Ghana Standards Authority"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-greece","title":"Roofing in Greece","category":"world-roofing","type":"place","country":{"name":"Greece","iso2":"GR"},"regions":["Europe"],"company":null,"summary":"How Greece roofs its buildings: the birthplace of the European clay tile, with Minoan flat roofs, Byzantine domes, Cycladic terraces and stone roofs in Epirus.","aliases":["Greek roofing","Roofs of Greece"],"body":"Greece has a strong claim to be the birthplace of the European roof tile. Flat clay tiles were already in use in the Early Bronze Age, and the first fully interlocking tile roofs in the Western world appeared at Corinth in the 7th century BC. Since then the country has produced Byzantine domes, whitewashed Cycladic terraces and the heavy stone roofs of the northern mountains.\n\n## Climate and hazards\n\nGreek roofs face hot, dry summers almost everywhere, strong winds in the Aegean, and heavy winter snow in mountainous Epirus, where stone roofs need continual upkeep. Greece is also highly seismic. The 1956 Amorgos earthquake, moment magnitude 7.7, heavily damaged Santorini and destroyed part of Oia.\n\n## Roofing history\n\n**Bronze Age.** Flat, rectangular ceramic tiles without interlocking parts covered \"corridor houses\" on the mainland around 2650-2200 BC. On Crete, Minoan buildings, whose first palaces date from about 1925-1875 BC, generally had flat roofs on timber beams, carried in larger buildings on tapering columns of cypress. Flat roofs and courtyards collected rainwater for cisterns. The Mycenaean civilisation (about 1600-1100 BC) built corbelled stone *tholos* tombs, such as the Treasury of Atreus at Mycenae.\n\n**Archaic and Classical.** Between about 700 and 650 BC fired clay tiles replaced thatch on temples near Corinth. The tiling of the Old Temple at Corinth, called the Protocorinthian system, is the earliest interlocking tiled roof yet identified, and within about fifty years tiles had spread across Greece, western Asia Minor and Italy. From around 620 BC marble tiles appeared on prestigious buildings, including the Temple of Zeus at Olympia and the Parthenon. Rows of decorated antefixes closed the eaves, and lion-head spouts drained the gutters. Greek temples were otherwise post-and-lintel buildings; arches, vaults and domes were rarely used.\n\n**Byzantine.** The cross-in-square church with a dome on a drum became dominant from the 9th century. Greek examples include Hosios Loukas (about 1000), the Nea Moni of Chios (mid-11th century) and the church of Daphni Monastery (11th-12th centuries). Byzantine domes and vaults were covered externally with lead or regional tiles.\n\n**Ottoman and modern.** Many of the stone villages of Zagori, in Epirus, grew into larger mansions during the 18th and 19th centuries. Modern Greek houses are mostly reinforced concrete, with flat or tiled pitched roofs.\n\n## Traditional and vernacular roofs\n\n- **Mainland and Ionian roofs:** hipped or gabled roofs of curved clay tiles.\n- **Epirus and Zagori:** roofs of limestone or sandstone slabs, held without cement by the weight of the slabs above, over strong timber structures. Even courtyard gates have small stone roofs, and churches typically have timber roofs covered with slate. A similar stone roofing style is found in Pelion.\n- **Cyclades:** whitewashed cubic houses with flat roofs, suited to a dry, windy climate with little timber. Lime wash on walls and roofs also helps keep collected rainwater clean, and churches are typically domed.\n- **Santorini:** cave houses (*yposkafa*) carved into the caldera edge, insulated by the surrounding pumice.\n\n## Roofing today\n\nReinforced concrete frames with either flat roofs or tiled pitched roofs dominate new building.\n\n## Codes, standards and regulation\n\nAs an EU member, Greece applies the Eurocodes for structural design, including the parts for actions on structures and earthquake resistance.\n\n## Notable roofs\n\n- Marble-tiled roofs of the Parthenon and Temple of Zeus at Olympia (Classical)\n- Corbelled tholos tombs of Mycenae (UNESCO)\n- Byzantine domes of Hosios Loukas, Nea Moni and Daphni\n- Stone villages of Zagori, a UNESCO cultural landscape since September 2023 (46 villages, the Zagorochoria)\n- Domed churches of Oia, Santorini\n\n## Local roofing terms\n\n- *yposkafa* - cave houses of Santorini\n- *Zagorochoria* - the 46 villages of Zagori\n- *mesochori* - central village square, typically by the main church\n## Sources and gaps\n\nNational statistics on roof materials, details of Greek building regulations for roofs and information on Greek roof-tile and roofing manufacturers: published information is limited.","key_facts":[{"label":"First interlocking tiles","value":"Corinth, c. 700-650 BC (Protocorinthian)"},{"label":"Marble tiles","value":"From c. 620 BC"},{"label":"Mountain roofs","value":"Limestone or sandstone slabs (Zagori, Pelion)"},{"label":"Cycladic roofs","value":"Whitewashed flat roofs, domed churches"},{"label":"Seismic hazard","value":"High (e.g. 1956 Amorgos, Mw 7.7)"}],"related":["ancient-greek-roof-tiles","earliest-fired-clay-roof-tiles","imbrex-and-tegula","cycladic-flat-roof","stone-slate","dome","hagia-sophia-dome","roofing-in-italy","roofing-in-cyprus","roofing-in-albania","roofing-in-turkey","roofing-in-north-macedonia","middle-eastern-domes"],"sources":[{"title":"Architecture of Greece","url":"https://en.wikipedia.org/wiki/Architecture_of_Greece","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Oia, Greece","url":"https://en.wikipedia.org/wiki/Oia,_Greece","publisher":"Wikipedia"},{"title":"Research Spotlight: Roof Tile Manufacturing Techniques","url":"https://www.ascsa.edu.gr/news/newsDetails/sapirstein-dissertation","publisher":"American School of Classical Studies at Athens"},{"title":"Minoan architecture","url":"https://en.wikipedia.org/wiki/Minoan_architecture","publisher":"Wikipedia"},{"title":"Archaeological Sites of Mycenae and Tiryns","url":"https://whc.unesco.org/en/list/941","publisher":"UNESCO World Heritage Centre"},{"title":"Byzantine architecture","url":"https://en.wikipedia.org/wiki/Byzantine_architecture","publisher":"Wikipedia"},{"title":"Zagori","url":"https://en.wikipedia.org/wiki/Zagori","publisher":"Wikipedia"},{"title":"Gjirokastër","url":"https://en.wikipedia.org/wiki/Gjirokast%C3%ABr","publisher":"Wikipedia"},{"title":"EN Eurocodes","url":"https://eurocodes.jrc.ec.europa.eu/","publisher":"European Commission Joint Research Centre"},{"title":"1956 Amorgos earthquake","url":"https://en.wikipedia.org/wiki/1956_Amorgos_earthquake","publisher":"Wikipedia"},{"title":"Daphni Monastery","url":"https://en.wikipedia.org/wiki/Daphni_Monastery","publisher":"Wikipedia"}]},{"slug":"roofing-in-greenland","title":"Roofing in Greenland","category":"world-roofing","type":"place","country":{"name":"Greenland","iso2":"GL"},"summary":"Greenlandic roofing: Inuit winter houses of stone, turf and whalebone, Norse stone-and-turf farms, imported Danish timber houses and today's prefabricated buildings.","body":"Greenland has almost no trees, so for most of its history roofs were made of whatever the land and sea provided: stone, turf, driftwood and whalebone. Norse settlers from Iceland added stone and turf farms in the south from the 10th century, and the colonial period of the 18th and 19th centuries brought imported timber buildings. Since the 1950s, housing has been dominated by serially built timber houses, concrete blocks and prefabricated buildings shipped in from abroad.\n\n## Climate and hazards\n\nRoofs face extreme cold, long periods of snow cover, strong winds that drift snow, and a short building season. Almost all materials must be imported by sea. In some areas buildings are raised above permafrost.\n\n## Roofing history\n\nGreenland's archaeological record covers about 4,200 years. The UNESCO-listed landscape of Aasivissuit-Nipisat preserves remains of Paleo-Inuit (Saqqaq and Dorset) and Inuit (Thule) cultures, including large communal winter houses.\n\nThe Thule people, ancestors of today's Inuit, spread across the Arctic from Alaska to Greenland around 1000 CE. Their winter house was built partly into the ground, typically oval and about 3-9 m (10-30 ft) across, dug up to 1 m (3 ft) deep, with a sloping tunnel entrance that trapped cold air. The roof was its most distinctive feature: in the central and eastern Arctic it was usually framed with whale bones and covered with materials such as sod, stone and baleen. In Greenland, winter houses were built mainly of rock and turf, with driftwood and whale ribs and jaws supporting the roof, and many were dug into a hillside. Windows were made of stretched seal gut. Turf huts were still in use in parts of Greenland in the 1940s.\n\nNorse farmers from Iceland arrived in the 10th century and farmed in the south until the 15th century, in what is now the UNESCO-listed farming landscape of Kujataa. Their buildings had walls of large stones insulated on the outside with turf, with wooden floors and linings; a stable at Igaliku was 70 m (230 ft) long. Hvalsey Church, about 16 by 8 m (52 by 26 ft) with walls about 1.5 m (5 ft) thick, was probably roofed with timber covered with turf. A wedding there in September 1408 is the last written record of the Greenland Norse.\n\nIn the 18th and 19th centuries, colonial buildings were log and plank houses built in Scandinavia, dismantled and re-erected in Greenland. The Bethel Church in Sisimiut was made in Denmark and finished in 1775 by a Greenlandic carpenter. Colonial buildings were colour-coded by use, for example red for churches, schools and trade buildings and yellow for hospitals. During the Second World War, numbers were painted on roofs to help US pilots find settlements.\n\n## Traditional and vernacular roofs\n\n- **Inuit winter house:** stone and turf walls with a roof frame of driftwood or whale bone covered with turf.\n- **Norse farmhouse:** stone walls with outer turf insulation and a timber roof under turf.\n- **Colonial log house:** imported Scandinavian timber, assembled locally.\n\n## Roofing today\n\nA housing benefit scheme began in 1953, followed by serially built one- and two-family timber houses in all coastal towns, often painted in bright colours. Large concrete blocks were also built: Blok P in Nuuk, completed in 1965-1966, was 231 m (758 ft) long, housed about 1% of Greenland's population and was demolished in 2012. Later housing, such as the Nuussuaq district of Nuuk in the 1980s and newer apartments in Qinngorput, was designed to suit Arctic living better. Typical houses today are timber-framed or prefabricated, with pitched roofs of coated steel sheet or bituminous roofing, while large buildings use membranes. Nuuk Center (2012) is described as the largest building in Greenland.\n\n## Industry\n\nRoofing materials are imported, mainly through Denmark.\n\n## Notable roofs\n\n- **Hvalsey Church**, a Norse stone church in the Kujataa World Heritage area.\n- **Aasivissuit-Nipisat**, a UNESCO World Heritage landscape with remains of Inuit winter houses.\n- **Katuaq** cultural centre in Nuuk (1997), by Schmidt, Hammer & Lassen.\n- **Ilulissat Icefjord Centre** (2021), designed by Dorte Mandrup.\n\n## Sources and gaps\n\nInformation on Greenland's building code, on the share of roofing materials and on domestic roofing manufacturers: published information is limited. The roof described for Hvalsey Church is a scholarly reconstruction rather than a surviving feature.","key_facts":[{"label":"Traditional materials","value":"Stone, turf, driftwood, whalebone"},{"label":"Norse period","value":"10th-15th centuries"},{"label":"Colonial houses","value":"Imported Scandinavian timber, from the 18th century"},{"label":"Climate driver","value":"Extreme cold, snow and wind"}],"regions":["Arctic"],"aliases":["Greenlandic roofing","roofs in Greenland","Kalaallit Nunaat roofing"],"related":["roofing-in-the-arctic","roofing-in-iceland","roofing-in-denmark","sod-roof","icelandic-turf-house","snow-load","metal-roofing"],"company":null,"sources":[{"title":"Architecture in Greenland","url":"https://visitgreenland.com/activities/architecture/","publisher":"Visit Greenland"},{"title":"Thule Winter House","url":"https://thecanadianencyclopedia.ca/en/article/thule-winter-house","publisher":"The Canadian Encyclopedia"},{"title":"Hvalsey Church","url":"https://en.wikipedia.org/wiki/Hvalsey_Church","publisher":"Wikipedia"},{"title":"Aasivissuit – Nipisat. Inuit Hunting Ground between Ice and Sea","url":"https://whc.unesco.org/en/list/1557","publisher":"UNESCO World Heritage Centre"},{"title":"Kujataa Greenland: Norse and Inuit Farming at the Edge of the Ice Cap","url":"https://whc.unesco.org/en/list/1536","publisher":"UNESCO World Heritage Centre"}]},{"slug":"roofing-in-grenada","title":"Roofing in Grenada","category":"world-roofing","type":"place","country":{"name":"Grenada","iso2":"GD"},"summary":"Grenadian roofing: timber and concrete houses with metal-sheet hip roofs under an OECS-based code; Hurricane Beryl in 2024 destroyed or damaged most buildings on Carriacou.","body":"Grenada comprises the main island and the smaller islands of Carriacou and Petite Martinique. Its roofs have been repeatedly tested by hurricanes, including Hurricane Beryl in 2024.\n\n## Climate and hazards\n\nHurricane Beryl made landfall on Carriacou on 2 July 2024 as a Category 4 hurricane. Prime Minister Dickon Mitchell described almost complete destruction of homes and buildings on the island, and Carriacou and Petite Martinique suffered the worst damage in the country; the roof of a hospital was damaged, forcing patients to move to a lower floor. The OECS code also notes earthquake and flood exposure in the region.\n\n## Roofing history\n\nThroughout the Eastern Caribbean, older timber houses typically have steep hip or gable roofs clad first in wooden shingles and later in corrugated iron. Hip roofs, sloping on all four sides, are self-bracing and lack tall gable ends that catch the wind, and slopes of about 35 degrees or more are often preferred in hurricane regions because shallower roofs are more prone to uplift.\n\n## Roofing today\n\nReconstruction after Beryl has focused on roofs and their fixings.\n\n## Codes, standards and regulation\n\nThe Organisation of Eastern Caribbean States (OECS) developed model building codes and guidelines for small buildings with support from UNCHS and UNDP, based on the Caribbean Uniform Building Code (CUBiC). The USAID-funded, OAS-executed Caribbean Disaster Mitigation Project helped Antigua and Barbuda, Dominica, Grenada and Saint Lucia prepare national codes from these models, and published construction diagrams covering hip and gable roof framing, rafter-to-ring-beam and wall-plate connections and hurricane straps for houses under 3,000 ft² (279 m²). A revised OECS Building Code was issued in June 2015, reviewed that year for Grenada, Saint Vincent and the Grenadines, Saint Lucia and Montserrat, and drew on the codes of Jamaica and the Cayman Islands. National consultations on administering it were held across the sub-region in 2017 under the EU-funded iLand Resilience project. A draft Grenada code was published on the CDMP website, and the 2015 OECS revision was prepared for Grenada among others.\n\n## Sources and gaps\n\nPublished accounts of island-specific historic roofing: published information is limited. National roof-material statistics were not found in published sources.\n\nRoofing history, materials data, Beryl roof-loss totals and the legal status of the code: published information is limited.","key_facts":[{"label":"Building code","value":"OECS-based national code (2015 OECS revision)"},{"label":"Recent hazard","value":"Hurricane Beryl, Cat 4, 2 July 2024 (Carriacou)"}],"regions":["Latin America","North America"],"aliases":["Grenadian roofing"],"related":["roofing-in-the-caribbean","hip-roof","corrugated-iron","hurricane-roof-damage","hurricane-tie","chattel-house","roofing-in-saint-vincent-and-the-grenadines","roofing-in-trinidad-and-tobago"],"company":null,"sources":[{"title":"Hurricane Beryl leaves damage strewn across southeast Caribbean islands","url":"https://cbsnews.com/news/hurricane-beryl-damage-southeastern-caribbean-islands","publisher":"CBS News"},{"title":"OECS Building Code (June 2015)","url":"https://oecs.int/en/our-work/knowledge/library/sustainable-energy/oecs-building-codes/oecs-building-code-1-5","publisher":"Organisation of Eastern Caribbean States"},{"title":"Building codes in the Caribbean (CDMP bulletin)","url":"https://oas.org/cdmp/bulletin/codes.htm","publisher":"Organization of American States, Caribbean Disaster Mitigation Project"},{"title":"OECS Building Guidelines: construction diagrams","url":"https://oas.org/pgdm/document/codedraw/intro.htm","publisher":"Organization of American States"},{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"}]},{"slug":"roofing-in-guatemala","title":"Roofing in Guatemala","category":"world-roofing","type":"place","country":{"name":"Guatemala","iso2":"GT"},"summary":"Guatemalan roofing: Maya thatch and stone vaults, colonial tile in Antigua, and today metal sheet on 68.1% of homes (2018 census).","body":"Guatemala's roofs range from the palm-thatched houses of the Maya lowlands and the stone temples of Tikal to the tiled colonial city of Antigua and the corrugated metal sheet that now covers most homes. The country combines a hot, wet Caribbean lowland and Petén forest with cool volcanic highlands, and it is exposed to frequent earthquakes and volcanic eruptions.\n\n## Climate and hazards\n\n- **Earthquakes and volcanoes.** The old capital, Santiago de Guatemala (now Antigua Guatemala), was largely destroyed by the Santa Marta earthquakes of 1773, after which the capital was moved to the site of present-day Guatemala City. UNESCO notes that Antigua's massive buildings and low bell towers were designed to withstand earthquakes.\n- **Hurricanes and tropical storms.** Hurricane Mitch in 1998 killed 268 people in Guatemala, destroyed about 6,000 houses and damaged 20,000.\n- **Heavy rain** in the wet season, especially on the Caribbean slope and in Petén, favours steep roofs and generous eaves.\n\n## Roofing history\n\n**Maya period.** Most ancient Maya people lived in houses of poles and wattle under palm or grass thatch, while temples and palaces were built in stone. Maya builders roofed masonry rooms with the corbel vault, in which stone courses step inward until they meet; the vault is often said to imitate the steep thatched hut, and it needed thick walls for a narrow room. Tikal, in Petén, was inscribed by UNESCO in 1979 and the stone-carving centre of Quiriguá in 1981.\n\n**Colonial period.** Spanish settlers introduced fired clay roof tile (*teja*), timber roof frames and masonry vaults. Antigua, laid out on a grid in 1543, preserves 17th- and 18th-century buildings in a regional Baroque style (*barroco antigueño*), with heavy walls and stucco ornament. It was inscribed by UNESCO in 1979.\n\n**Modern period.** In the 20th century corrugated metal sheet (*lámina*) spread across rural and urban housing, and reinforced concrete slabs became standard for multi-storey and better-off urban houses.\n\n## Traditional and vernacular roofs\n\n- **Maya thatched house**: pole-and-thatch dwellings, still found in Petén and the Verapaces. FLAAR, a foundation documenting Maya ethnobotany, identifies *guano* palm (*Sabal mayarum*) as the main thatch palm of the Tikal and Lake Yaxhá area, corozo or cohune palm as the usual thatch of Q'eqchi' houses, and *junco* (*Carludovica palmata*) in Alta Verapaz. Grasses are also used.\n- **Teja** roofs on adobe houses in colonial towns and highland villages.\n- **Tejamanil**: split wooden shingles, recorded as a separate roof category in national household surveys.\n- **Garifuna houses** on the Caribbean coast: wooden or wattle-and-daub houses with thatched roofs, the wooden ones raised on posts.\n\n## Roofing today\n\nThe 2018 national census (XII Population and VII Housing Census, INE) reported the main roof material of homes as:\n\n- Metal sheet (*lámina metálica*): 68.1%\n- Concrete (*concreto*): 23.0%\n- Clay tile (*teja*): 5.5%\n- Asbestos-cement and other: 1.7%\n- Straw, palm or similar: 1.7%\n\nThe same census found that 64.7% of homes had brick, block or concrete walls, 15.3% adobe and 12.1% timber. Concrete slabs are concentrated in towns and cities, while metal sheet is the usual roof elsewhere.\n\n## Codes, standards and regulation\n\nSeismic design standards are issued by the Asociación Guatemalteca de Ingeniería Estructural y Sísmica (AGIES) as its NSE standards. A 2012 comparative review of Latin American building codes listed the AGIES NSE of 2010 as Guatemala's seismic code in force at that time.\n\n## Notable roofs\n\n- **Tikal** (UNESCO 1979): Maya temples with corbel-vaulted sanctuaries and roof combs.\n- **Antigua Guatemala** (UNESCO 1979): colonial churches, convents and houses with heavy masonry and tile roofs.\n- **Quiriguá** (UNESCO 1981).\n\n## Local roofing terms\n\n- *Lámina*: corrugated metal roofing sheet.\n- *Teja*: clay roof tile.\n- *Losa* or *terraza*: concrete slab roof.\n- *Guano*: thatch palm of Petén.\n- *Tejamanil*: split wooden shingles.\n- *Naj*: house (Mopan and Yucatec Maya).","key_facts":[{"label":"Dominant material today","value":"Metal sheet, 68.1% of homes (2018)"},{"label":"Second material","value":"Concrete slab, 23.0%"},{"label":"Traditional materials","value":"Palm and grass thatch, clay tile"},{"label":"Climate drivers","value":"Earthquakes, hurricanes, heavy rain"},{"label":"Seismic standard","value":"AGIES NSE"}],"regions":["Latin America"],"aliases":["Guatemalan roofing","techos en Guatemala"],"related":["maya-thatched-house","palm-thatch","clay-roof-tile","spanish-tile","corrugated-iron","asbestos-cement-roofing","roofing-in-mexico","roofing-in-belize","roofing-in-honduras","roofing-in-el-salvador"],"company":null,"sources":[{"title":"Datos del censo presentan dura realidad para los guatemaltecos","url":"https://lahora.gt/?p=284086","publisher":"La Hora"},{"title":"Unos tres millones de personas viven en casas fabricadas con adobe","url":"https://www.prensalibre.com/?p=18800908","publisher":"Prensa Libre"},{"title":"Guatemala ENCOVI 2000: material techo","url":"https://microdata.worldbank.org/index.php/catalog/586/variable/F8/V843","publisher":"World Bank Microdata Library / INE Guatemala"},{"title":"Antigua Guatemala","url":"https://whc.unesco.org/en/list/65","publisher":"UNESCO World Heritage Centre"},{"title":"List of World Heritage Sites in Central America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_Central_America","publisher":"Wikipedia"},{"title":"What is used to thatch houses of the Mayan people?","url":"https://www.maya-archaeology.org/maya-architecture-houses-buildings-temples-palaces-pyramid-structure/guano-huano-junco-palm-thatch-mayan-house-architecture-qeqchi-kekchi-kala-alta-verapaz.php","publisher":"FLAAR (maya-archaeology.org)"},{"title":"Maya architecture","url":"https://en.wikipedia.org/wiki/Maya_architecture","publisher":"Wikipedia"},{"title":"Hurricane Mitch","url":"https://en.wikipedia.org/wiki/Hurricane_Mitch","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"},{"title":"Garifuna","url":"https://www.everyculture.com/wc/Afghanistan-to-Bosnia-Herzegovina/Garifuna.html","publisher":"EveryCulture"}]},{"slug":"roofing-in-guinea","title":"Roofing in Guinea","type":"place","country":{"name":"Guinea","iso2":"GN"},"summary":"Guinea is mostly roofed with metal sheet, but nearly a quarter of homes kept thatch in 2013; Fouta Djallon is known for heavy conical thatched roofs.","body":"Guinea stretches from a rainy Atlantic coast through the Fouta Djallon highlands, source of the Niger, Senegal and Gambia rivers, to savanna in the north-east and forest in the south-east. It has one of the strongest surviving thatch traditions on the West African coast, epitomised by the steep conical roofs of the Fulbe (Peul) houses and mosques of the Fouta Djallon. Metal sheet is now the most common roof.\n\n## Climate and hazards\n\nGuinea is among the wetter countries of West Africa. The Fouta Djallon receives roughly 1,500-2,500 mm (60-100 in) of rain a year, most of it between June and September. Roofs must protect unbaked earth walls from these rains, which is why traditional roofs are thick and widely overhanging.\n\n## Roofing history\n\nA Fulbe Islamic state was established in the Fouta Djallon in the early 18th century, and its architecture combined round thatched houses with square mosques under great thatched roofs. French colonial writers documented the region's buildings from 1906 onward. The Friday Mosque of Dinguiraye, associated with the 19th-century leader El Hadj Umar Tall, is often cited as the largest example of the type. Metal sheet spread through the 20th century but, as of the 2010s, had not entirely displaced thatch.\n\n## Traditional and vernacular roofs\n\n- **Fulbe round house**: a circular earth-walled room under a regular conical thatched roof. Long rafters meet over the centre and continue past the walls to a ring of outer posts, creating a veranda. The underside of the thatch is left exposed and may be decorated with rings of bound thatch (see Fouta Djallon thatched architecture).\n- **Fouta Djallon mosque**: a square earthen prayer hall with an earthen ceiling, covered by a huge conical or dome-like thatched roof carried partly on an inverted \"umbrella\" of poles above a central pillar.\n\n## Roofing today\n\nThe 2013 Afrobarometer survey of Guinea recorded:\n\n| Main roof material | Share of respondents (2013) |\n|---|---|\n| Metal, tin or zinc | 72.9% |\n| Thatch or grass | 23.6% |\n| Plastic sheets | 1.9% |\n| Tiles | 1.3% |\n| Shingles | 0.3% |\n\nAfrobarometer surveys interview about 1,200 adults per country; these figures are unweighted counts in the survey sample. The 2016 Multiple Indicator Cluster Survey classifies roofs in categories including thatch/palm leaf, grass, *tôle/métal*, zinc/fibre cement, tiles and concrete/cement.\n\n## Codes, standards and regulation\n\nA *case de couronnement* (coronation house) of the Almamy rulers of Fouta Djallon is on Guinea's tentative list for World Heritage nomination.\n\n## Notable roofs\n\n- **Friday Mosque of Dinguiraye**: square earthen hall under a great thatched roof.\n- **Coronation house of the Almamy of Fouta Djallon**: on Guinea's World Heritage tentative list.\n\n## Local roofing terms\n\n- **tôle** (French): metal roof sheet.\n- **paille** (French): straw thatch.\n- **hatumere** (Fulfulde, from Arabic *khatim*, \"seal\"): Islamic geometric design that some scholars link to the plan of the Dinguiraye mosque.\n\n## Sources and gaps\n\nSurvey shares are unweighted. Published sources on coastal and forest-region vernacular roofs, regulation and industry: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal sheet, 72.9% (Afrobarometer 2013 file)"},{"label":"Thatch","value":"23.6% of respondents (2013)"},{"label":"Traditional roof","value":"Heavy conical thatch with veranda eaves (Fouta Djallon)"},{"label":"Climate driver","value":"Very heavy rainy season"},{"label":"Landmark","value":"Friday Mosque of Dinguiraye"}],"regions":["Africa"],"aliases":["Guinean roofing","roofing in Guinea Conakry"],"related":["roofing-in-west-africa","fouta-djallon-thatched-architecture","thatch","conical-roof","corrugated-iron","roofing-in-senegal","roofing-in-mali","roofing-in-sierra-leone","roofing-in-liberia","roofing-in-guinea-bissau","roofing-in-cote-divoire"],"sources":[{"title":"Afrobarometer Survey 2013, Round 5, Guinea: roof of respondent's home","url":"https://catalog.ihsn.org/catalog/8887/variable/F2/V604?name=Q105","publisher":"IHSN / Afrobarometer"},{"title":"MICS 2016 Guinée: matériau principal du toit (HC4)","url":"https://microdata.worldbank.org/catalog/3483/variable/F2/V148?name=HC4","publisher":"World Bank Microdata Library"},{"title":"Localizing Fulbe Architecture","url":"https://condor.depaul.edu/mdelance/images/Pdfs/DeLancey%20-%20Localizing%20Fulbe%20Architecture.pdf","publisher":"Mark D. DeLancey, DePaul University"},{"title":"La case de couronnement des Almamy du Fouta Djallon","url":"https://whc.unesco.org/en/tentativelists/6820/","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-guinea-bissau","title":"Roofing in Guinea-Bissau","type":"place","country":{"name":"Guinea-Bissau","iso2":"GW"},"summary":"Guinea-Bissau's homes are mostly roofed with zinc or metal sheet, but about a fifth are still thatched with straw, one of the highest shares in the region.","body":"Guinea-Bissau, a small, low-lying country of estuaries, mangroves and the Bijagós archipelago, has a higher share of thatched roofs than most of its neighbours in recent household surveys. Most homes are now roofed with corrugated zinc or metal sheet, but straw thatch is still found on about one household in five.\n\n## Climate and hazards\n\nThe climate is tropical, with a heavy rainy season and a dry season. Low-lying coastal and island areas are exposed to humidity and salt air, which shorten the life of untreated metal and organic roofing alike.\n\n## Roofing history\n\nGuinea-Bissau was a Portuguese colony until its independence was recognised in 1974. The round thatched house of Cabo Verde, the *funco*, is reported to have counterparts in Guinea-Bissau, reflecting the close historical ties between the mainland and the islands.\n\n## Traditional and vernacular roofs\n\n- **Straw thatch** (*palha*): the main traditional roof, still common in rural areas.\n- **Palm-leaf roofs**: survey categories include roofs of *folha de cibe*, the leaf of the cibe (Borassus) palm, and other palm or bamboo leaves.\n\n## Roofing today\n\nIn the unweighted 2018-19 Multiple Indicator Cluster Survey sample (about 7,400 households):\n\n| Main roof material | Share of sampled households |\n|---|---|\n| Zinc or fibre cement | 69.4% |\n| Thatch (*palhas*) | 20.1% |\n| Metal or aluminium | 7.3% |\n| Tiles (*telhas*) | 0.7% |\n| Cibe leaf | 0.3% |\n| Cement | 0.3% |\n\nTaken together, metal-type sheets (zinc, fibre cement, metal and aluminium) cover about three-quarters of homes, while concrete and tile roofs are rare.\n\n## Local roofing terms\n\n- **zinco** (Portuguese/Kriol): metal roof sheet.\n- **palha** (Portuguese): straw thatch.\n- **folha de cibe**: cibe-palm leaf used for roofing.\n- **telha** (Portuguese): roof tile.\n\n## Sources and gaps\n\nPublished research on Bissau-Guinean roofing is scarce. Detailed documentary evidence on the development of roofs in the country: published information is limited.\n\nSurvey figures are unweighted sample counts. No accessible sources were found on the vernacular architecture of the Bijagós islands or on building regulation and industry.","key_facts":[{"label":"Dominant material today","value":"Zinc/fibre cement sheet, 69.4% (MICS 2018-19 file)"},{"label":"Thatch","value":"20.1% of households (MICS 2018-19 file)"},{"label":"Traditional materials","value":"Straw thatch, cibe-palm leaf"},{"label":"Climate driver","value":"Heavy tropical rain, humidity, salt air"}],"regions":["Africa"],"aliases":["Bissau-Guinean roofing","roofing in Guinea Bissau"],"related":["roofing-in-west-africa","funco","thatch","palm-thatch","corrugated-iron","roofing-in-senegal","roofing-in-guinea","roofing-in-cabo-verde","roofing-in-portugal"],"sources":[{"title":"MICS 2018-2019 Guinea-Bissau: material predominante na cobertura (HC5)","url":"https://microdata.worldbank.org/catalog/4157/variable/F5/V843?name=HC5","publisher":"World Bank Microdata Library"},{"title":"Funco (architecture)","url":"https://en.wikipedia.org/wiki/Funco_(architecture)","publisher":"Wikipedia"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-guyana","title":"Roofing in Guyana","category":"world-roofing","type":"place","country":{"name":"Guyana","iso2":"GY"},"summary":"Guyanese roofing: timber houses raised above floods with shingle or metal roofs, palm thatch inland, and St George's, a giant wooden cathedral.","body":"Guyana, on the north-east coast of South America, is a country of timber building. Most of its people live on a narrow coastal plain that lies below sea level and is protected by Dutch-era sea walls and drainage, so houses have long been raised on posts above flood level. Roofs were of palm thatch and wooden shingles, later largely replaced by corrugated metal.\n\n## Climate and hazards\n\n- **Flooding** on the low coastal plain, protected by sea defences and drainage canals.\n- **Heavy tropical rain and high humidity**, which favour raised floors and wide verandahs.\n- **Fire** in dense timber towns.\n- **Low seismicity**: a 2012 review of Latin American building codes excluded Guyana as a low-seismicity country.\n\n## Roofing history\n\nThe architect Rory Westmaas, in an essay first published in 1970 and reprinted by *Stabroek News* in 2010, traced Guyanese building from its plantation origins. Early dwellings of enslaved people had roofs of palm leaves or shingles on laths, and walls were lathed to take wallaba shingles. Timber was the main building material because it was abundant and enslaved craftsmen were skilled in working it. Early ranges had simple double-pitched roofs, with porch roofs projecting from the main roof.\n\nThe Dutch laid out drainage, sluices and dams and planned Georgetown on a grid. French influence brought early fire-safety and planning rules, and town regulations prohibited thatched roofs of troolie, ite palm or coconut leaves. Under British rule (1803 to 1966), Georgian and Victorian styles were reinterpreted in timber, with verandahs for shade and houses oriented to catch the north-east breeze. Kitchens were often detached because of the fire risk of dry timber. Floors were raised above flood level; the space underneath sheltered animals and was later extended for servants and family retainers.\n\n## Traditional and vernacular roofs\n\n- **Wallaba shingles**: split shingles of wallaba wood, used on roofs and walls.\n- **Palm thatch** of troolie, ite or coconut leaves.\n- **Raised timber house** with double-pitched roof and verandahs.\n\n## Roofing today\n\nCorrugated metal sheet is widely used on houses today, with concrete in some newer buildings.\n\n## Industry\n\nLocal hardwoods such as greenheart, mora and wallaba have long been used in building.\n\n## Notable roofs\n\n- **St George's Cathedral**, Georgetown: an Anglican cathedral built from 1889 to 1894 in Gothic style, designed by Sir Arthur Blomfield, almost entirely of timber on low masonry foundations. It rises about 43.5 m (143 ft), and the *Architects' Journal* described it in 1985 as the largest wooden church building in the world. Guyana placed it on its UNESCO Tentative List in 1995.\n\n## Local roofing terms\n\n- *Wallaba*: hardwood used for shingles.\n- *Troolie*: palm leaf used for thatch.","key_facts":[{"label":"Traditional materials","value":"Wallaba shingles, palm thatch (troolie, ite)"},{"label":"Main building material","value":"Timber"},{"label":"Climate driver","value":"Flooding, heavy rain"},{"label":"Landmark","value":"St George's Cathedral (timber, 43.5 m)"}],"regions":["Latin America"],"aliases":["Guyanese roofing"],"related":["wood-shingle","palm-thatch","corrugated-iron","roofing-in-suriname","roofing-in-venezuela","roofing-in-brazil","roofing-in-trinidad-and-tobago"],"company":null,"sources":[{"title":"Architecture...Building under our sun","url":"https://stabroeknews.com/2010/04/29/guyana-review/architecture-building-under-our-sun","publisher":"Stabroek News"},{"title":"St. George's Anglican Cathedral (Tentative List)","url":"https://whc.unesco.org/en/tentativelists/272","publisher":"UNESCO World Heritage Centre"},{"title":"St. George's Cathedral, Georgetown","url":"https://en.wikipedia.org/wiki/St._George%27s_Cathedral,_Georgetown","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-haiti","title":"Roofing in Haiti","category":"world-roofing","type":"place","country":{"name":"Haiti","iso2":"HT"},"summary":"Haitian roofing: Taíno thatch, timber gingerbread houses of 1885-1925, then heavy concrete slabs whose failures in the 2010 earthquake reshaped rebuilding.","body":"Haiti occupies the western third of Hispaniola. Its roofs face hurricanes, heavy tropical rain and earthquakes, and the January 2010 earthquake made the weight of roofs a national issue.\n\n## Climate and hazards\n\n- **Earthquakes**: on 12 January 2010 a magnitude 7.0 earthquake struck about 25 km (16 mi) west-southwest of Port-au-Prince. One engineering review lists about 230,000 deaths and 250,000 residences collapsed or damaged.\n- **Hurricanes and tropical storms**, with heavy rain and flooding.\n- **Termites and rot**, which weaken timber roofs and frames.\n\n## Roofing history\n\n**Taíno.** Hispaniola had some of the largest Taíno villages in the Caribbean, with thatched houses of poles, woven straw and palm leaves around central plazas (see bohio).\n\n**Gingerbread era.** Between 1885 and 1925, Port-au-Prince's wealthier districts were built up with timber and masonry houses known as gingerbread houses, adapting French styles to the climate. Their roofs are steep, often steeper than 1:1 (45°), framed in wood with mortise-and-tenon joints and wooden pegs; tall turret roofs draw hot air up out of the rooms. Almost all now carry corrugated steel over spaced (skip) sheathing, but a few keep original thin slate (see haitian-gingerbread-house).\n\n**Concrete.** In 1925, after several destructive fires, Port-au-Prince banned wood construction. Concrete and concrete block became normal for new buildings and additions. Many houses were then roofed with reinforced concrete slabs, sometimes with concrete joists and hollow block infill, carried on lightly reinforced columns as small as about 150 mm (6 in). The combination of heavy roofs and weak lateral strength proved deadly in 2010.\n\n**After 2010.** The 2010 field assessment of about 200 gingerbread houses found that timber-framed and *colombage* (timber frame with masonry infill) buildings performed best; under 5% collapsed completely, against an estimated 40% of modern conventional buildings. Relief agencies distributed tarpaulins and tents for nearly 860,000 people, and the American Red Cross alone funded nearly 6,000 transitional shelters. Training programmes taught builders to fix light metal roofing sheets in place of heavy slabs.\n\n## Traditional and vernacular roofs\n\n- **Gingerbread house** (*kay gingerbread*): steep hipped and turreted roofs, now mostly corrugated steel.\n- **Tôle**: corrugated metal sheet, the common light roof.\n\n## Roofing today\n\nConcrete slab roofs remain common in towns, while corrugated metal sheet is the main light roof.\n\n## Codes, standards and regulation\n\nBefore 2010, observers noted a lack of planning and of enforceable building codes. Post-earthquake guidance has favoured light, well-fastened roofs and better connections.\n\n## Notable roofs\n\n- **Gingerbread District**, Port-au-Prince: about 2 mi² (5 km²) of 19th- and early 20th-century houses in Bois Verna, Pacot and Turgeau, surveyed by the World Monuments Fund and ICOMOS in 2010.\n- **Le Manoir**: turrets roofed with decorative pressed-metal shingles.\n\n## Local roofing terms\n\n- *Tôle* (French/Kreyòl): sheet metal roofing.\n- *Colombage* (French): timber framing with masonry infill.\n- *Kay* (Kreyòl): house.\n\n## Sources and gaps\n\nNo information on domestic roofing manufacturers was found in published sources.\n\nCensus roof-material data and code details: published information is limited.","key_facts":[{"label":"Heritage roof type","value":"Steep-roofed gingerbread houses (1885-1925)"},{"label":"Common roofs today","value":"Concrete slab; corrugated metal sheet"},{"label":"Key hazards","value":"Earthquakes, hurricanes"},{"label":"2010 earthquake","value":"Mw 7.0, 12 January 2010"},{"label":"Wood ban","value":"Port-au-Prince, 1925"}],"regions":["Latin America","North America"],"aliases":["Haitian roofing"],"related":["haitian-gingerbread-house","bohio","corrugated-iron","flat-roof","natural-slate","roofing-in-the-dominican-republic","roofing-in-the-caribbean","hurricane-roof-damage","tin-roof"],"company":null,"sources":[{"title":"Gingerbread houses of Haiti: earthquake assessment","url":"https://hazards.colorado.edu/archive/workshop/2010/speakers/pubs/hammer_gingerbread.pdf","publisher":"Natural Hazards Center, University of Colorado (Martin Hammer)"},{"title":"Haiti's Gingerbread Houses Focus of Preservation Efforts","url":"https://architecturalrecord.com/articles/2229-haiti-s-gingerbread-houses-focus-of-preservation-efforts","publisher":"Architectural Record"},{"title":"Gingerbread Houses","url":"https://visithaiti.com/art-culture/gingerbread-houses/","publisher":"Visit Haiti"},{"title":"Urban earthquake damage: the 2010 Haiti earthquake (WCEE 2012 paper 0328)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_0328.pdf","publisher":"15th World Conference on Earthquake Engineering"},{"title":"Improving Housing in Haiti","url":"https://www.redcross.org/content/dam/redcross/atg/PDFs/Improving_Housing_in_Haiti.pdf","publisher":"American Red Cross"},{"title":"Taíno","url":"https://en.wikipedia.org/wiki/Ta%C3%ADno","publisher":"Wikipedia"}]},{"slug":"roofing-in-honduras","title":"Roofing in Honduras","category":"world-roofing","type":"place","country":{"name":"Honduras","iso2":"HN"},"summary":"Honduran roofing: Maya stone and thatch at Copán, Garifuna thatched houses on the Caribbean coast, colonial tile, and modern metal sheet.","body":"Honduras spans the Caribbean coast, mountainous interior and a short Pacific shoreline. Its roofing history runs from the Maya city of Copán through Spanish colonial tile to the metal sheet and concrete of modern housing, with Garifuna and Indigenous thatch surviving on the Caribbean side. Hurricanes and floods have repeatedly destroyed large parts of the housing stock.\n\n## Climate and hazards\n\n- **Hurricanes and floods.** In Hurricane Mitch in 1998 about 7,000 people died in Honduras, an estimated 35,000 houses were destroyed and 50,000 damaged, and up to 1.5 million people were left homeless.\n- **Earthquakes**.\n- **Tropical heat and heavy rain**, favouring steep, ventilated roofs and wide eaves.\n\n## Roofing history\n\n**Maya period.** Copán, in western Honduras, was a major Classic Maya city. UNESCO dates the founding of its royal dynasty to 427 CE, its flourishing to about 300 to 900 CE and its abandonment to the early 10th century. Its Acropolis rises about 30 m (100 ft) through successive rebuildings, and its Hieroglyphic Stairway carries more than 1,800 glyphs. As elsewhere in the Maya world, temples and palaces were stone, with corbel vaults, while ordinary houses were of poles and thatch. Copán was inscribed by UNESCO in 1980.\n\n**Colonial period.** Spanish colonial towns were built with adobe walls and clay tile (*teja*) roofs.\n\n**Garifuna.** In 1797 about a quarter of the Garifuna were deported to the island of Roatán, off the Honduran coast; from there they settled the Caribbean coastal lowlands of Honduras and neighbouring countries. Their villages traditionally had wooden or wattle-and-daub houses with thatched roofs.\n\n**Modern period.** Metal sheet, fibre-cement sheet and concrete slabs replaced most tile and thatch in the 20th century.\n\n## Traditional and vernacular roofs\n\n- **Maya pole-and-thatch house** in the west (see Maya thatched house).\n- **Garifuna house**: wattle-and-daub or wooden walls, thatched roof; wooden houses raised on posts.\n- **Teja on adobe**: the colonial and rural highland house.\n\n## Roofing today\n\nMetal sheet is widely used on rural and urban houses, and reinforced concrete on urban buildings.\n\n## Codes, standards and regulation\n\nA 2012 comparative review of Latin American seismic codes listed the 2010 code of the Colegio de Ingenieros Civiles de Honduras (CICH) as the country's seismic design code in force at that time.\n\n## Notable roofs\n\n- **Copán** (UNESCO 1980): Maya temples and palaces built of local volcanic tuff, with the Acropolis and Hieroglyphic Stairway.\n\n## Local roofing terms\n\n- *Lámina*: metal roofing sheet.\n- *Teja*: clay roof tile.","key_facts":[{"label":"Climate driver","value":"Hurricanes and floods (Mitch, 1998)"},{"label":"Mitch housing losses","value":"About 35,000 houses destroyed, 50,000 damaged"},{"label":"Traditional materials","value":"Thatch, clay tile"},{"label":"Seismic code (2012 review)","value":"CICH 2010"},{"label":"Heritage","value":"Copán, UNESCO 1980"}],"regions":["Latin America"],"aliases":["Honduran roofing"],"related":["maya-thatched-house","palm-thatch","clay-roof-tile","corrugated-iron","roofing-in-guatemala","roofing-in-el-salvador","roofing-in-nicaragua","roofing-in-belize"],"company":null,"sources":[{"title":"Maya Site of Copan","url":"https://whc.unesco.org/en/list/129","publisher":"UNESCO World Heritage Centre"},{"title":"List of World Heritage Sites in Central America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_Central_America","publisher":"Wikipedia"},{"title":"Hurricane Mitch","url":"https://en.wikipedia.org/wiki/Hurricane_Mitch","publisher":"Wikipedia"},{"title":"Garifuna","url":"https://www.everyculture.com/wc/Afghanistan-to-Bosnia-Herzegovina/Garifuna.html","publisher":"EveryCulture"},{"title":"Maya architecture","url":"https://en.wikipedia.org/wiki/Maya_architecture","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-hong-kong","title":"Roofing in Hong Kong","category":"world-roofing","type":"place","country":{"name":"Hong Kong","iso2":"HK"},"summary":"Hong Kong roofing: tiled roofs of walled villages and early tenements, replaced by flat concrete roofs on dense high-rises designed for typhoon winds.","body":"Hong Kong is one of the most densely built places on earth, and almost all of its people live and work under flat reinforced-concrete roofs on multi-storey buildings. Pitched clay-tile roofs survive mainly in the walled villages and temples of the New Territories and on a few early urban buildings. Typhoon winds, intense rain and the pressure of space have shaped roofs more than any architectural style.\n\n## Climate and hazards\n\nThe city has a humid subtropical climate with a wet summer monsoon and frequent tropical cyclones. The Hong Kong Observatory has issued warnings since 1884 and has used a numbered signal system since 1917, revised to ten signals in 1931. The highest, the No. 10 Hurricane Signal, warns of sustained winds of 118 km/h (73 mph) or more, with gusts that may exceed 220 km/h (137 mph). By the end of 2025 it had been hoisted only 19 times since 1946, six of them since 2010, including Typhoon Hato (2017) and Typhoon Mangkhut (2018). Wind loads on roofs, parapets, rooftop plant and temporary structures are therefore a central design concern.\n\n## Roofing history\n\n**Villages.** Before the colonial era, roofs in the area were those of southern Chinese villages: timber-framed pitched roofs covered with clay pan-and-cover tiles. About 70-80 walled villages survive, most in the New Territories, built by Punti and Hakka clans as defence against pirates during the Ming and Qing dynasties. Kat Hing Wai in Yuen Long was founded by the Tang clan in the 17th century; Tsang Tai Uk in Sha Tin, a Hakka stronghold of granite, grey brick and solid timber, was begun in 1847 and took about 20 years to build.\n\n**Tong lau.** From the late 19th century until the 1960s, the typical urban building was the *tong lau*, a narrow shophouse tenement of two to four storeys at first. Early tong lau had timber and tile roofs. After an outbreak of bubonic plague, regulations of 1903 required light wells and larger windows and replaced tiled roofs with flat concrete roofs. From the 1920s reinforced concrete became the main structural material, and post-war tong lau often had flat roof terraces that owners later built over to gain living space. Height controls were relaxed in 1955 to cope with migration from the mainland, and after further rule changes came fully into force in 1966 no more tong lau were built.\n\n**High-rise era.** Since the 1960s, public and private housing has been dominated by high-rise towers with flat concrete roofs carrying water tanks, lift machinery, plant and, in some cases, rooftop structures added without permission.\n\n## Traditional and vernacular roofs\n\n- **Village houses and ancestral halls** - gabled, grey clay-tile roofs on brick or granite walls, with decorated ridges on halls and temples.\n- **Tong lau** - early timber-and-tile roofs, later flat concrete roof terraces.\n- **Temples** - southern Chinese ridge decoration with ceramic figures; ridge figures also help weigh down roof tiles.\n\n## Roofing today\n\nNearly all buildings have flat reinforced-concrete roofs waterproofed with membranes or liquid coatings, usually with screeds, tiles or insulation above and heavy rooftop equipment. Unauthorised rooftop structures have long been a safety issue: the Buildings Department's ten-year removal programme, run from 2001, prioritised illegal rooftop structures on single-staircase buildings, and a revised policy from 1 April 2011 extended enforcement to unauthorised works on rooftops and podiums regardless of risk level.\n\n## Codes, standards and regulation\n\nBuilding work is controlled under the **Buildings Ordinance (Cap. 123)** and its regulations, including the Building (Minor Works) Regulation, administered by the Building Authority through the **Buildings Department**, formed in 1993 as successor to the Buildings Ordinance Office. Wind loads are set by the **Code of Practice on Wind Effects in Hong Kong 2019**, which replaced the 2004 code after a 12-month transition from 30 September 2019 and added, among other things, guidance on wind loads on temporary structures and on sheltering by surrounding buildings.\n\n## Notable roofs\n\n- **Tsang Tai Uk, Sha Tin** (begun 1847) - one of the best-preserved Hakka walled villages.\n- **Kat Hing Wai, Yuen Long** (17th century) - walled Punti village, though most houses inside have been rebuilt.\n- **Surviving tong lau** in older districts, showing the shift from tile to flat concrete roofs.\n\n## Local roofing terms\n\n- *tong lau* (唐樓) - \"Chinese building\", shophouse tenement\n- *wai* (圍) - walled village\n\n## Sources and gaps\n\nRoof-material statistics, industry data and detailed historical roof surveys: published information is limited.","key_facts":[{"label":"Climate driver","value":"Typhoons; No. 10 signal hoisted 19 times, 1946-2025"},{"label":"Dominant roof today","value":"Flat reinforced concrete"},{"label":"Traditional roof","value":"Clay pan-and-cover tile, pitched"},{"label":"Building law","value":"Buildings Ordinance (Cap. 123)"},{"label":"Wind code","value":"Code of Practice on Wind Effects 2019"}],"regions":["East Asia"],"aliases":["Hong Kong roofing"],"related":["roofing-in-china","roofing-in-taiwan","flat-roof","clay-roof-tile","wind-uplift","roof-wind-pressure-zones","liquid-applied-roofing","chinese-imperial-roof-figures"],"company":null,"sources":[{"title":"Hong Kong tropical cyclone warning signals","url":"https://en.wikipedia.org/wiki/Hong_Kong_tropical_cyclone_warning_signals","publisher":"Wikipedia"},{"title":"Walled villages of Hong Kong","url":"https://en.wikipedia.org/wiki/Walled_villages_of_Hong_Kong","publisher":"Wikipedia"},{"title":"Tong lau","url":"https://en.wikipedia.org/wiki/Tong_lau","publisher":"Wikipedia"},{"title":"Buildings Department","url":"https://en.wikipedia.org/wiki/Buildings_Department","publisher":"Wikipedia"},{"title":"Circular letter: Code of Practice on Wind Effects in Hong Kong 2019","url":"https://www.bd.gov.hk/doc/en/resources/codes-and-references/practice-notes-and-circular-letters/circular/CL_WC2019e.pdf","publisher":"Buildings Department, Hong Kong"},{"title":"Revised enforcement policy against unauthorised building works","url":"https://www.bd.gov.hk/doc/en/resources/codes-and-references/notices-and-reports/notices/rubw_policy.pdf","publisher":"Buildings Department, Hong Kong"},{"title":"Chinese architecture","url":"https://en.wikipedia.org/wiki/Chinese_architecture","publisher":"Wikipedia"}]},{"slug":"roofing-in-hungary","title":"Roofing in Hungary","category":"world-roofing","type":"place","country":{"name":"Hungary","iso2":"HU"},"summary":"Hungarian roofing: straw and reed thatch on purlin-and-rafter roofs, shingles in the hills, Palóc villages like Hollókő, and Zsolnay glazed ceramic roofs.","body":"Hungary's folk roofs were built mainly from the products of farming and wetland: straw thatch (*zsúp*) across most of the country and reed in marshy regions such as the Great Plain and the Bodrogköz. Shingles were used on timber buildings in the uplands, and some northern villages used local slate. In the 19th century, Hungary also developed a distinctive decorative roofing tradition of glazed ceramic tiles, made famous by the Zsolnay factory of Pécs.\n\n## Climate and hazards\n\nHungary lies in the Carpathian Basin, with hot summers, cold winters and modest snowfall. The main historic hazard for roofs was fire, which led authorities to restrict thatch and wooden building. In Hollókő, a decree of 1783 banned wooden construction, yet the village kept burning until a last major fire in 1909.\n\n## Roofing history\n\nHungarian ethnographers trace the purlin-type roof, in which a ridge beam (*szelemen*) under the gables carries the roof's weight without pushing outward on the walls, to the New Stone Age. It was used mainly on wattle and earth buildings, and its oldest form rests on forked posts (*ágas*) at each end. The rafter-type roof (*szarufa*), with inverted-V rafters resting on a wall beam and tied by a collar called the *kakasülő* (\"rooster's perch\"), spread from west to east and became common in Transylvania and Upper Hungary; corner rafters at the ends produced hipped roofs. The chair-leg roof (*széklábas*), demanding greater carpentry skill, was a newer and less common peasant form.\n\nBrick tile, factory slate and sheet metal (*tin*) are recent coverings that replaced traditional ones in many villages, a change pushed by fire risk and official bans on thatch.\n\nFrom 1853 the Zsolnay factory in Pécs developed ornamental ceramics. Its frost-resistant pyrogranite, in production by 1886, and the iridescent eosin glaze introduced in 1893 were used on prominent buildings in Budapest, including Matthias Church, the Museum of Applied Arts, the Central Market Hall and the Hungarian Parliament Building; the frost resistance of pyrogranite made it suitable for roof tiles.\n\n## Traditional and vernacular roofs\n\n- **Zsúp (straw thatch):** the most widely used folk covering. Flail-threshed straw was preferred in some areas, treading-threshed straw in others, and pea straw (east of the Tisza) or buckwheat straw (in Transdanubia) was used as a base layer. A steep roof needed 15-20 cartloads of straw. Thatch was laid by spreading (*teregetés*) or by knotting. Smoke from chimneyless houses hardened the straw, and a well-packed roof could last a century with occasional repairs.\n- **Reed thatch:** used in wet regions such as the Great Plain, Transdanubia and the Bodrogköz, laid in stepped rows, with ridges finished with a reed fringe or two nailed boards.\n- **Shingles:** split shingles nailed to battens on timber buildings; in Székelyland, metre-long beech planks were laid overlapping.\n- **Slate:** used in some Palóc villages close to slate sources.\n\n## Roofing today\n\nReed thatch is still built on some new houses, including architect-designed holiday homes.\n\n## Codes, standards and regulation\n\nAs an EU member, Hungary applies European product standards and the Eurocodes for structural design, including Eurocode 1, Part 1-3 for snow loads.\n\n## Industry\n\nThe Zsolnay manufactory in Pécs, founded in 1853, is the country's best-known producer of architectural ceramics.\n\n## Notable roofs\n\n- **Hollókő**, a UNESCO-listed Palóc village in Nógrád County, about 100 km (60 mi) north-east of Budapest, rebuilt after 1909 with half-timbered houses on stone bases, overhanging porch roofs and a church with a shingled tower.\n- **Matthias Church** and the **Museum of Applied Arts**, Budapest, with Zsolnay ceramics.\n\n## Local roofing terms\n\n- *héj* - roof\n- *zsúp* - straw thatch\n- *szelemen* - ridge purlin\n- *ágas* - forked post\n- *szarufa* - rafter\n- *kakasülő* - collar tie (\"rooster's perch\")\n- *esővető* - eaves or porch\n- *teregetés* - spreading method of thatching\n\n## Sources and gaps\n\nCurrent material shares, details of the national building code for roofs and information on other domestic roofing manufacturers: published information is limited. The Zsolnay sources name buildings where its ceramics appear but do not confirm a tiled roof on every one.","key_facts":[{"label":"Traditional covering","value":"Straw thatch (zsúp); reed in wetlands"},{"label":"Oldest roof structure","value":"Purlin (szelemen) on forked posts"},{"label":"Decorative tradition","value":"Zsolnay pyrogranite and eosin ceramics (from 1886, 1893)"},{"label":"UNESCO village","value":"Hollókő"}],"regions":["Europe"],"aliases":["Hungarian roofing","roofs in Hungary","nádtető"],"related":["thatch","water-reed-thatch","long-straw-thatch","wood-shingle","clay-roof-tile","roofing-in-slovakia","roofing-in-romania","roofing-in-austria"],"company":null,"sources":[{"title":"Roof Structure and Roofing (Hungarian Ethnography)","url":"https://vmek.oszk.hu/02700/02790/html/42.html","publisher":"Hungarian Electronic Library (MEK)"},{"title":"Old Village of Hollókő and its Surroundings","url":"https://whc.unesco.org/en/list/401","publisher":"UNESCO World Heritage Centre"},{"title":"Zsolnay","url":"https://en.wikipedia.org/wiki/Zsolnay","publisher":"Wikipedia"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"},{"title":"RAPA Architects' thatch roof, cantilevered holiday home in Hungary","url":"https://www.dezeen.com/2023/11/06/rapa-thatch-stone-summer-house-hungary/amp/","publisher":"Dezeen"}]},{"slug":"roofing-in-iceland","title":"Roofing in Iceland","category":"world-roofing","type":"place","country":{"name":"Iceland","iso2":"IS"},"summary":"Icelandic roofing: a thousand years of turf over driftwood frames, then painted corrugated iron and concrete, built for wind, rain, freeze-thaw and earthquakes.","body":"Iceland's roofing history is unusually compact: turf for about a thousand years, then corrugated iron, then reinforced concrete. Each shift reflected the island's scarcity of timber, its harsh North Atlantic weather and its earthquakes. Turf buildings survive in museums and on a few farms, and the turf house tradition is on Iceland's UNESCO Tentative List.\n\n## Climate and hazards\n\nIceland combines strong winds, frequent rain, repeated freeze-thaw and, in the north, snow. Roof design has to prioritise secure fixing against wind uplift, robust flashings and corrosion-resistant coatings in salty air. The island is seismically active, which is one reason reinforced concrete replaced turf and timber. Widespread geothermal heating keeps many buildings warm all winter, so insulation and ventilation of roof spaces matter for preventing condensation and snowmelt problems.\n\n## Roofing history\n\nThe vernacular tradition dates from the settlement of Iceland in the 9th century. The first houses were longhouses with a double-pitched roof running along the building, carried on freestanding interior posts and covered with turf. Native birch was the main framing wood, because oak did not grow on the island, and driftwood and imported timber were precious. From the Middle Ages to the 19th century the dominant form was the passage farmhouse, in which several turf-roofed rooms were linked by a central corridor. From around 1800 the gabled farm (*burstabær*) developed, with a row of timber gable fronts facing the yard and turf roofs behind.\n\nIn the late 19th and early 20th centuries, timber houses clad in corrugated galvanised iron (patented in Britain in 1829) spread through towns and farms; the material was light, easy to ship and could be fixed by semi-skilled builders. Iron also crept into turf buildings: at Núpsstaður, slates or corrugated iron lie beneath the turf, and some roofs use iron alone. Concrete became a main building material in the 1920s. A house at Sveinatunga in Borgarfjörður with cast-in-place concrete walls, built in 1895, is regarded as the first of its kind.\n\n## Traditional and vernacular roofs\n\nTurf (*torf*) was cut from mineral-rich marshland in several standard shapes, named *strengur*, *torfa*, *klömbruhnaus* and *snidda*. The roof covering was turf laid over a timber structure, sometimes with additional layers beneath:\n\n- At Keldur, slate roofs are covered with turf.\n- At Þverá, dwarf birch is packed beneath the turf.\n- At Tyrfingsstaðir, roofs are of driftwood and turf.\n- At Bustarfell, tar paper has been used on some rear gables.\n\nTurf roofs needed constant upkeep: walls and roofs settled, absorbed water and had to be rebuilt every few decades. See Icelandic turf house.\n\n## Roofing today\n\nMost Icelandic buildings are of reinforced concrete. Pitched roofs on houses are commonly covered with corrugated or profiled metal sheet, and brightly painted corrugated roofs remain characteristic of Reykjavík and smaller towns. Larger buildings with flat and low-slope roofs use membranes.\n\n## Codes, standards and regulation\n\nBuilding requirements are set by the Building Regulation No. 112/2012 (*Byggingarreglugerð*), which has been amended several times since 2012.\n\n## Industry\n\nMost roofing materials are imported.\n\n## Notable roofs\n\nThe UNESCO Tentative List entry \"The Turf House Tradition\", submitted by the National Museum of Iceland in 2011, lists 14 sites, including:\n\n- **Glaumbær**, Skagafjörður (mid-18th century to about 1880)\n- **Laufás**, Eyjafjörður (mostly 1840-1877)\n- **Víðimýrarkirkja**, a turf church built in 1834 on a site first recorded in 1318\n- **Hofskirkja**, Öræfi, a turf church built in 1883-1885 on a site first recorded in 1343\n- **Keldur**, Rangárvellir, with wooden features from the 17th century\n- **Árbær**, Reykjavík, where three roofs are turf and three are corrugated iron\n\n## Local roofing terms\n\n- *torfbær* - turf farmhouse\n- *torfþak* - turf roof\n- *burstabær* - gabled turf farmhouse\n- *strengur*, *torfa*, *klömbruhnaus*, *snidda* - shapes of cut turf\n\n## Sources and gaps\n\nCurrent market data on roof materials and information on domestic roofing manufacturers: published information is limited.","key_facts":[{"label":"Traditional roof","value":"Turf over a timber frame"},{"label":"Later covering","value":"Corrugated iron"},{"label":"Modern structure","value":"Reinforced concrete (from the 1920s)"},{"label":"First concrete house","value":"Sveinatunga, 1895"},{"label":"Building regulation","value":"No. 112/2012"}],"regions":["Europe","Arctic"],"aliases":["Icelandic roofing","roofs in Iceland"],"related":["icelandic-turf-house","torvtak","sod-roof","corrugated-iron","roofing-in-scandinavia","roofing-in-the-arctic","roofing-in-greenland","roofing-in-norway","birch-bark-roofing"],"company":null,"sources":[{"title":"The Turf House Tradition (Tentative List)","url":"https://whc.unesco.org/en/tentativelists/5589","publisher":"UNESCO World Heritage Centre"},{"title":"Icelandic turf house","url":"https://en.wikipedia.org/wiki/Icelandic_turf_house","publisher":"Wikipedia"},{"title":"The homes that built Iceland","url":"https://www.west.is/en/moya/news/the-homes-that-built-iceland-1","publisher":"West Iceland"},{"title":"Corrugated galvanised iron","url":"https://en.wikipedia.org/wiki/Corrugated_galvanised_iron","publisher":"Wikipedia"},{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"},{"title":"Byggingarreglugerð nr. 112/2012","url":"https://island.is/reglugerdir/nr/0112-2012/d/2018-07-06","publisher":"Government of Iceland (island.is)"}]},{"slug":"roofing-in-india","title":"Roofing in India","category":"world-roofing","type":"place","country":{"name":"India","iso2":"IN"},"summary":"Indian roofing runs from rock-cut chaitya vaults and Mughal domes to Mangalore tiles; today concrete slabs, tiles, metal sheets and thatch cover most homes.","body":"India has one of the longest continuous roofing histories in the world and one of the most varied. Its roofs range from the rock-cut imitations of timber vaults in Buddhist cave halls, through the curved roofs of Bengal, the domes and pavilions of Mughal and Rajput palaces and the long tiled roofs of Kerala, to the slate roofs of the Himalaya. Today most new building uses flat reinforced concrete slabs, but tiles, metal and fibre-cement sheets and thatch still cover tens of millions of homes.\n\n## Climate and hazards\n\nThe south-west monsoon brings months of intense rain to the west coast, the north-east and the Himalayan foothills, so roofs there are typically steep with deep eaves. The north-west and the Deccan interior are hot and dry for much of the year, which favours flat roofs that can be used as terraces. The east coast is exposed to tropical cyclones from the Bay of Bengal. The Himalayan states face heavy snow and are seismically very active, and large parts of northern and north-eastern India are at high earthquake risk, which makes the weight and anchorage of roofs a structural issue.\n\n## Roofing history\n\n**Indus civilisation.** The cities of the Indus or Harappan civilisation, in present-day Pakistan and north-west India, flourished from about 2500 to 1900 BCE in their mature phase. Houses were one or two storeys high, built of standardised fired or mud brick, sometimes with timber superstructures, around courtyards. The surviving ruins do not preserve the roofs themselves, so their construction: published information is limited.\n\n**Early tiles and timber.** Excavations at Alamgirpur in Uttar Pradesh have produced early evidence of fired roof tiles on the subcontinent. Most early public roofs were of timber and thatch, which have perished; they are known from the rock-cut Buddhist halls of western India, whose carvers copied them in stone (see *chaitya vault*). The Barabar Caves of the 3rd century BCE are the earliest comparable spaces. At Bhaja (2nd century BCE) and Karla (about 50-70 CE) real wooden ribs line barrel vaults cut in rock; the Great Chaitya at Karla is about 45 m (148 ft) long and up to 14 m (46 ft) high.\n\n**Temples and palaces.** Hindu and Jain temples were roofed in stone, and some were finished in metal: the Nataraja Temple at Chidambaram in Tamil Nadu is roofed with 21,600 gold-covered tiles. In Bengal, where stone was scarce, temple builders from about the 16th century reproduced the curved thatched roofs of village huts in brick and terracotta (see *bangla roof*). The Mughals built great masonry domes, most famously the Taj Mahal at Agra (built 1632-1648), a white-marble tomb over brick-in-lime masonry with a large, double-storeyed domed central chamber. Rajput and Mughal builders crowned roofs with *chhatris*, small domed pavilions on pillars, and from about 1635 adopted the Bengal curved roof in palaces such as the Khas Mahal at Agra.\n\n**Colonial and industrial era.** On 4 December 1865 the Basel Mission began industrial production of clay roof tiles that hook into one another in Mangalore, the first such factory in India. The **Mangalore tile** spread along the west coast, replacing much palm thatch in Kerala during the British period, and was exported widely; about 75 factories existed by 1994, though many have since closed because of clay shortages. Corrugated galvanised iron and, in the 20th century, asbestos-cement sheet spread across the country for houses, sheds and factories. In Kashmir, for example, imported corrugated iron replaced the old earth-and-birch-bark roofs.\n\n**Modern.** Reinforced cement concrete (RCC) slab roofs now dominate urban construction and are increasingly common in villages, where flat roofs also allow a later upper storey.\n\n## Traditional and vernacular roofs\n\n- **Kerala sloping roof**: steep timber roofs with deep eaves, originally thatched with palm leaf and later tiled. The *nalukettu* house groups four halls around an open courtyard (*nadumuttam*), with sloping tiled roofs shedding the monsoon; carpentry followed the *Thachu Shastra*, the traditional science of carpentry.\n- **Bangla roof**: the curved *do-chala*, *char-chala* and *at-chala* roofs of Bengal, first in thatch and later in brick.\n- **Kath-kuni**: the timber-and-stone houses and temples of Himachal Pradesh, roofed with heavy local slate or wooden shingles over a deodar frame.\n- **Burza pash**: the Kashmiri roof of planks, birch bark and about 75-100 mm (3-4 in) of earth, which flowered with tulips and irises in spring.\n- **Flat earth and lime roofs**: in the hot, dry north-west, flat roofs and roof terraces used for sleeping and drying.\n- **Thatch and bamboo**: grass, palm-leaf and bamboo roofs across rural India, especially in the east and north-east.\n\n## Roofing today\n\nThe 2011 Census recorded the predominant roof material of 246.7 million households (excluding institutional households):\n\n| Roof material | Share of households |\n|---|---|\n| Concrete | 29.0% |\n| Tiles (hand-made 14.5%, machine-made 9.3%) | 23.8% |\n| G.I., metal, asbestos sheets | 15.9% |\n| Grass, thatch, bamboo, wood, mud etc. | 15.0% |\n| Stone or slate | 8.6% |\n| Burnt brick | 6.6% |\n| Plastic or polythene | 0.6% |\n| Other | 0.4% |\n\nConcrete slabs are typically waterproofed with lime terracing, brickbat coba, bituminous membranes or liquid coatings. Coated steel sheets and fibre-cement sheets are standard on industrial and farm buildings.\n\n## Codes, standards and regulation\n\nThe **National Building Code of India**, published by the Bureau of Indian Standards (BIS), is the model national code; its 2016 edition (NBC 2016) superseded the 2005 edition. It is adopted through state and municipal building bye-laws. Roof-related provisions are spread across its parts on fire safety, materials, structural design (including wind loads), plumbing and sustainability, and BIS publishes Indian Standards for roofing products such as coated steel sheet, tiles and fibre-cement sheets.\n\n## Industry\n\nIndia has a large roofing manufacturing sector, including the remaining Mangalore-pattern tile works on the west coast, fibre-cement producers such as Everest Industries (founded in 1934 as Asbestos Cement Ltd) and coated-steel makers such as Tata Steel Colors.\n\n## Notable roofs\n\n- **Great Chaitya, Karla** (about 50-70 CE): rock-cut barrel vault with ancient wooden ribs.\n- **Nataraja Temple, Chidambaram**: roof of 21,600 gold-covered tiles.\n- **Taj Mahal, Agra** (1632-1648): the best-known Mughal dome, a UNESCO World Heritage Site.\n- **Chhatris of Rajasthan**, such as the cenotaphs of Bada Bagh in Jaisalmer and Gaitore in Jaipur.\n- **Madin Saheb shrine, Srinagar**: one of the last flowering birch-bark roofs.\n\n## Local roofing terms\n\n- *chala* (Bengali): roof slope; *do-chala*, two-sloped roof\n- *chhatri* (Hindi): \"umbrella\", a domed pavilion\n- *nadumuttam* (Malayalam): open central courtyard of a nalukettu\n- *burza* (Kashmiri): birch bark\n- *kath-kuni* (Himachali): timber-and-stone construction\n\n## Sources and gaps\n\nAs of 2026 the 2011 Census is the most recent with published data on roof materials. Direct evidence for how Indus-period roofs were built: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Concrete slab, 29.0% of households (Census 2011)"},{"label":"Other main coverings","value":"Tiles 23.8%; GI, metal or asbestos sheet 15.9%; grass, thatch, bamboo, wood or mud 15.0%"},{"label":"Traditional materials","value":"Thatch, clay tile, slate, timber shingle, earth, stone"},{"label":"Climate driver","value":"Monsoon rain, heat, Himalayan snow, earthquakes"},{"label":"Building code","value":"National Building Code of India 2016 (BIS)"},{"label":"Industrial tile","value":"Mangalore tile, made from 1865"}],"regions":["South Asia"],"aliases":["Indian roofing","roofs of India"],"related":["mangalore-tile","kerala-sloping-roof","national-building-code-of-india","everest-industries","tata-steel-colors","asbestos-cement-roofing","corrugated-iron","flat-roof","palm-thatch","bamboo-roofing","chaitya-vault","chhatri","bangla-roof","kath-kuni","burza-pash-roof","dome","onion-dome","roofing-in-pakistan","roofing-in-nepal","roofing-in-bangladesh","roofing-in-sri-lanka","fibre-cement-slate"],"company":null,"sources":[{"title":"National Health Profile 2018: households by predominant material of roof (Census 2011)","url":"https://cbhidghs.mohfw.gov.in/Ebook/National%20Health%20Profile-2018%20(e-Book)/files/assets/basic-html/page-84.html","publisher":"Central Bureau of Health Intelligence, Government of India"},{"title":"Mangalore tiles","url":"https://en.wikipedia.org/wiki/Mangalore_tiles","publisher":"Wikipedia"},{"title":"Architecture of Kerala","url":"https://en.wikipedia.org/wiki/Architecture_of_Kerala","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Karla Caves","url":"https://en.wikipedia.org/wiki/Karla_Caves","publisher":"Wikipedia"},{"title":"Chaitya","url":"https://en.wikipedia.org/wiki/Chaitya","publisher":"Wikipedia"},{"title":"Taj Mahal","url":"https://whc.unesco.org/en/list/252/","publisher":"UNESCO World Heritage Centre"},{"title":"Bengal roofs","url":"https://en.wikipedia.org/wiki/Bengal_roofs","publisher":"Wikipedia"},{"title":"Chhatri","url":"https://en.wikipedia.org/wiki/Chhatri","publisher":"Wikipedia"},{"title":"Kath kuni architecture","url":"https://en.wikipedia.org/wiki/Kath_kuni_architecture","publisher":"Wikipedia"},{"title":"Burza Pash: The rooftops that exploded with colours","url":"https://www.greaterkashmir.com/todays-paper/burza-pash-the-rooftops-that-exploded-with-colours","publisher":"Greater Kashmir"},{"title":"Nalukettu","url":"https://en.wikipedia.org/wiki/Nalukettu","publisher":"Wikipedia"},{"title":"National Building Code","url":"https://www.bis.gov.in/standards/technical-department/national-building-code/","publisher":"Bureau of Indian Standards"},{"title":"Harappan architecture","url":"https://en.wikipedia.org/wiki/Harappan_architecture","publisher":"Wikipedia"}]},{"slug":"roofing-in-indonesia","title":"Roofing in Indonesia","category":"world-roofing","type":"place","country":{"name":"Indonesia","iso2":"ID"},"summary":"Roofing in Indonesia, from horned, saddle and towering vernacular roofs of ijuk, bamboo and thatch to clay tile, now on about 56% of houses.","body":"Indonesia, an archipelago of thousands of islands and hundreds of ethnic groups, has some of the most varied traditional roofs in the world. In many of its vernacular houses the roof is the dominant element, rising in saddle, horned or towering forms far above walls and floor. Today clay tile covers more than half of Indonesian homes, with zinc-coated steel, asbestos-cement and concrete making up most of the rest.\n\n## Climate and hazards\n\nThe country is equatorial, hot and humid, with heavy rain for much of the year. It lies on the Pacific Ring of Fire, so earthquakes and volcanic eruptions (with ashfall loading on roofs) are major hazards. Highland interiors are cooler. Traditional responses include steep roofs that shed rain fast, large overhanging eaves that keep walls dry and shaded, and houses raised on piles.\n\n## Roofing history\n\nEarly Austronesian communal longhouses, built of timber on stilts, had steeply sloping roofs and heavy gables; the Batak and Toraja house forms are seen as descendants of this tradition. Javanese temples and later royal architecture introduced stacked roofs: the Great Mosque of Demak, built in 1474, has a multi-tiered roof, and Bali's tiered *meru* shrine roofs derive from Majapahit-era forms.\n\nIn the colonial era, Dutch-period programmes that replaced traditional homes introduced brick houses with corrugated iron roofs. Mid-18th-century \"Indies style\" buildings borrowed Javanese *joglo* and *limasan* roof structures, and early 20th-century colonial architects used high-pitched roofs with Javanese ridge details. The Islamic dome did not appear on Indonesian mosques until the 19th century; earlier mosques, such as Demak, used tiered roofs.\n\nAfter independence, traditional roof forms became symbols of regional identity. In the 1980s, government buildings in Padang were given large concrete Minangkabau-style roofs, and universities and airports adopted joglo and meru motifs.\n\n## Traditional and vernacular roofs\n\n- **Minangkabau *rumah gadang* (West Sumatra):** multiple upswept *gonjong* gables, traditionally thatched in black sugar-palm fibre (*ijuk*).\n- **Batak Toba *jabu* (North Sumatra):** a huge saddleback roof with sharply projecting gables, carried on longitudinal beams without internal trusses; Karo houses have tiered hip roofs up to 15 m (49 ft) high, thatched and bound with ijuk.\n- **Toraja *tongkonan* (South Sulawesi):** boat-shaped saddle roofs of layered split bamboo.\n- **Javanese houses:** not raised on piles; roofs are ranked by status from the simple *kampung* to the *limasan* and the steep, two-peaked *joglo* reserved for nobility.\n- **Balinese compounds:** thatched pavilions (*bale*) and temple shrines with roofs of ijuk, coconut or rumbia leaves, or hardwood shingles (*sirap*).\n- **Nias *omo sebua*:** chiefs' houses with towering roofs on ironwood pillars.\n- **Sumba:** thatched \"high-hat\" roofs; **Papua (Dani):** thatched dome-roofed *honai* huts; **South Kalimantan:** steep *bubungan tinggi* roofs of Banjar houses.\n\n## Roofing today\n\nStatistics Indonesia (BPS) data show that 55.86% of Indonesian houses have clay tile (*genteng*) roofs. Tile is strongly concentrated on Java and Bali: DI Yogyakarta (94.38%), East Java (91.56%), Central Java (86.35%), Lampung (84.93%), West Java (82.01%), Banten (78.05%) and Bali (77.91%) all exceed the national average, while DKI Jakarta (38.01%) is well below it. Asbestos-cement roofs covered 9.34% of households nationally in the 2026 National Socio-Economic Survey (Susenas), rising above half in Bangka Belitung (56.70%) and Jakarta (54.59%). Zinc-coated steel sheet (*seng*) makes up much of the remainder and is widespread on rural houses.\n\n## Codes, standards and regulation\n\nIn its housing statistics, BPS treats roof durability as one of four components of decent housing (*rumah layak huni*). Concrete, clay tile, zinc sheet and wooden shingle roofs meet the criterion; asbestos does not. In 2026, 87.5% of households met the building-durability criterion. In February 2026 President Prabowo Subianto called for all Indonesian houses to use clay tile roofs, a proposal known as *gentengisasi*, citing heat and rust problems with zinc roofs; the Ministry of Housing and Settlement Areas said it was studying how to implement it.\n\n## Industry\n\nClay tile is produced largely by small and medium enterprises; Jatiwangi in Majalengka, West Java, is a well-known tile-making centre.\n\n## Notable roofs\n\n- **Pagaruyung Palace, West Sumatra:** a three-storey rumah gadang.\n- **Great Mosque of Demak (1474):** an early multi-tiered mosque roof.\n- **Grand Pendopo of the Mangkunegaran Palace, Surakarta:** a very large joglo roof.\n- **Tana Toraja villages:** rows of tongkonan.\n\n## Local roofing terms\n\n- *atap* - roof; *genteng* / *genting* - clay tile; *seng* - zinc-coated steel sheet; *asbes* - asbestos-cement sheet\n- *ijuk* - black sugar-palm fibre thatch; *rumbia* - sago palm leaf thatch; *sirap* - wooden shingles; *alang-alang* - grass thatch\n- *gonjong* - horned Minangkabau gable; *joglo*, *limasan*, *kampung* - Javanese roof types; *tumpang sari* - stepped beam ceiling of the joglo\n\n## Sources and gaps\n\nNational shares for zinc and concrete roofs and the SNI standards for roofing products: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Clay tile (genteng), 55.86% of houses (BPS)"},{"label":"Asbestos-cement roofs","value":"9.34% of households (Susenas 2026)"},{"label":"Highest tile share","value":"DI Yogyakarta, 94.38%"},{"label":"Traditional materials","value":"Ijuk, alang-alang, rumbia, split bamboo, sirap"},{"label":"Climate driver","value":"Heavy tropical rain, earthquakes, volcanic ash"}],"regions":["Southeast Asia"],"aliases":["Indonesian roofing","atap rumah Indonesia"],"related":["roofing-in-southeast-asia","rumah-gadang","gonjong-roof","tongkonan","batak-toba-house","joglo","ijuk-thatch","clay-roof-tile","palm-thatch","bamboo-roofing","corrugated-iron","corrugated-fibre-cement-sheet","asbestos-cement-roofing","roofing-in-malaysia","roofing-in-timor-leste","roofing-in-the-philippines"],"company":null,"sources":[{"title":"Ini Dia 10 Provinsi dengan Persentase Rumah Genting Tertinggi","url":"https://goodstats.id/article/ini-dia-10-provinsi-dengan-persentase-rumah-genting-tertinggi-5B3q0","publisher":"GoodStats (citing BPS)"},{"title":"Atap Asbes Bikin Rumah Tak Masuk Kriteria Layak Huni BPS","url":"https://katadata.co.id/berita/nasional/6a7dd41fcfee1/atap-asbes-bikin-rumah-tak-masuk-kriteria-layak-huni-bps","publisher":"Katadata"},{"title":"Maruarar buka suara soal gentengisasi","url":"https://www.cnbcindonesia.com/news/20260206103550-4-708745/maruarar-buka-suara-soal-gentengisasi-bakal-lakukan-ini","publisher":"CNBC Indonesia"},{"title":"Indonesian architecture","url":"https://en.wikipedia.org/wiki/Indonesian_architecture","publisher":"Wikipedia"},{"title":"Batak architecture","url":"https://en.wikipedia.org/wiki/Batak_architecture","publisher":"Wikipedia"},{"title":"Joglo","url":"https://en.wikipedia.org/wiki/Joglo","publisher":"Wikipedia"},{"title":"Balinese architecture","url":"https://en.wikipedia.org/wiki/Balinese_architecture","publisher":"Wikipedia"}]},{"slug":"roofing-in-iran","title":"Roofing in Iran","category":"world-roofing","type":"place","country":{"name":"Iran","iso2":"IR"},"regions":["Middle East"],"company":null,"summary":"Iranian roofing: mud-brick and brick vaults and domes, windcatchers and ice houses on the plateau, pitched roofs on the wet Caspian coast.","aliases":["Persian roofing","Iranian roofing","Roofs of Iran"],"body":"Iran has one of the richest masonry roofing traditions in the world. On the arid Iranian plateau, where timber was always scarce, builders roofed spaces with vaults and domes of mud brick and baked brick, and developed rooftop windcatchers and domed ice houses to manage heat without power. The humid Caspian provinces, by contrast, have a tradition of pitched roofs.\n\n## Climate and hazards\n\n- **Plateau and deserts:** hot, dry summers, cold nights and low rainfall across the central plateau and the Dasht-e Kavir and Dasht-e Lut deserts. Clear, dry winter nights allow heat to radiate to the sky, which made ice-making possible.\n- **North-west:** cold winters, which discouraged open courtyards in some buildings.\n- **Caspian coast:** heavy rain and humidity, hence pitched roofs.\n- **Earthquakes:** seismic risk is high. Heavy earth roofs on older buildings, and poorly connected timber roof beams on rural masonry houses, are known vulnerabilities.\n\n## Roofing history\n\n**Ancient earth building.** Moulding and sun-drying mud into bricks has been practised in Iran since ancient times and never fully abandoned. Records of *yakhchāl* ice houses go back to about 400 BC.\n\n**Sasanian.** The Sasanian Empire built the first large-scale domes in Iran, together with massive barrel-vaulted halls; the great brick vault of Taq Kasra at Ctesiphon, in present-day Iraq, is the best-known survivor (see taq-kasra).\n\n**Islamic era.** Builders developed tall and complex domes, including double-shell domes in which a tall outer dome is separated from a lower inner one; the Shah Mosque in Isfahan has about 14 m (46 ft) between its two shells. The Dome of Soltaniyeh, about 50 m (164 ft) tall and 25 m (82 ft) across, is one of the largest masonry domes ever built. Squinches and *muqarnas* handle the transition from square rooms to round domes, and Persian domes are known for exterior cladding in coloured glazed tile.\n\n**Modern.** Most new buildings are reinforced concrete or steel frame with flat roofs waterproofed with bituminous membranes, often finished with tiles or insulation.\n\n## Traditional and vernacular roofs\n\n- **Earth vaults and domes:** in desert cities such as Yazd, a UNESCO World Heritage site, earth is used for walls and roofs, and roofs are formed as vaults and domes.\n- **Badgir (windcatcher):** towers that catch the prevailing wind and vent warm air. Yazd's windcatchers are typically four- or eight-sided, and the tallest Iranian examples reach about 34 m (112 ft). See badgir.\n- **Yakhchāl:** a tall domed ice house, built of water-resistant *sarooj* mortar (sand, clay, lime, ash, goat hair and egg white) with walls at least 2 m (6.5 ft) thick at the base, over storage of up to about 5,000 m³ (180,000 cu ft). The Kerman yakhchāl is about 18 m (59 ft) high. See yakhchal.\n- **Ab anbar:** domed water cisterns, often ventilated by windcatchers, still common in the countryside.\n- **Caspian pitched roofs:** steeper roofs suited to heavy rain.\n- **Rural confined masonry:** in many rural single-family houses, timber roof beams sit on concrete tie beams over brick walls; the World Housing Encyclopedia identifies weak beam-to-tie-beam connections as a seismic deficiency and recommends anchoring the beams.\n\n## Roofing today\n\nReinforced concrete and steel frames with flat, membrane-waterproofed roofs are standard in cities.\n\n## Codes, standards and regulation\n\nSeismic design is governed by the Iranian Code of Practice for Seismic Resistant Design of Buildings, Standard No. 2800 (an English version of the third edition, dated 2007, is published through Japan's IISEE world list of seismic codes).\n\n## Notable roofs\n\n- **Dome of Soltaniyeh:** about 50 m (164 ft) tall.\n- **Shah Mosque, Isfahan:** double-shell dome.\n- **Historic City of Yazd** (UNESCO): earthen vaults, domes and windcatchers.\n- **Kerman yakhchāl:** well-preserved conical ice house.\n\n## Local roofing terms\n\n- *badgir* - windcatcher\n- *yakhchāl* - \"ice pit\", domed ice house\n- *ab anbar* - domed water cistern\n- *sarooj* - traditional water-resistant mortar\n- *muqarnas* - stalactite-like vaulting used in dome transitions\n\n## Sources and gaps\n\nFigures on current roofing materials, national regulations beyond Standard 2800 and information on the roofing industry: published information is limited.","key_facts":[{"label":"Traditional roofs","value":"Mud-brick and brick vaults and domes"},{"label":"Cooling","value":"Badgir windcatchers; yakhchāl ice houses"},{"label":"Dome of Soltaniyeh","value":"About 50 m (164 ft) tall"},{"label":"Seismic code","value":"Standard No. 2800"},{"label":"Modern roofs","value":"Flat concrete with bituminous membranes"}],"related":["badgir","yakhchal","taq-kasra","middle-eastern-domes","dome","barrel-vault-roof","mud-roof","flat-roof","modified-bitumen-roofing","earthquake-roofing","roofing-in-iraq","roofing-in-turkey","roofing-in-azerbaijan","roofing-in-armenia","roofing-in-the-middle-east-and-gulf"],"sources":[{"title":"Iranian architecture","url":"https://en.wikipedia.org/wiki/Iranian_architecture","publisher":"Wikipedia"},{"title":"Windcatcher","url":"https://en.wikipedia.org/wiki/Windcatcher","publisher":"Wikipedia"},{"title":"Historic City of Yazd","url":"https://whc.unesco.org/en/list/1544","publisher":"UNESCO World Heritage Centre"},{"title":"Yakhchāl","url":"https://en.wikipedia.org/wiki/Yakhch%C4%81l","publisher":"Wikipedia"},{"title":"Iranian Code of Practice for Seismic Resistant Design of Buildings, Standard No. 2800, 3rd edition (English)","url":"https://iisee.kenken.go.jp/worldlist/26_Iran/Iran%20National%20Seismic%20Code_2007_3rd%20Version_English.pdf","publisher":"IISEE / Building and Housing Research Center (Iran)"},{"title":"Confined brick masonry building with concrete tie columns and beams (Iran), Report 27","url":"https://world-housing.net/wp-content/uploads/WHEReports/wh100060.pdf","publisher":"World Housing Encyclopedia (EERI/IAEE)"}]},{"slug":"roofing-in-iraq","title":"Roofing in Iraq","category":"world-roofing","type":"place","country":{"name":"Iraq","iso2":"IQ"},"regions":["Middle East"],"company":null,"summary":"Iraqi roofing: reed mudhif halls of the southern marshes, Mesopotamian mud brick, the Sasanian vault of Taq Kasra and modern flat concrete roofs.","aliases":["Iraqi roofing","Mesopotamian roofing","Roofs of Iraq"],"body":"Iraq, the heart of ancient Mesopotamia, has some of the longest roofing traditions on record. Reed arches have roofed buildings in its southern marshes for at least 5,000 years, mud brick was the basic material of the Sumerian cities, and the Sasanian brick vault at Ctesiphon is one of the great roofs of antiquity.\n\n## Climate and hazards\n\nMost of Iraq has very hot, dry summers and low rainfall, with the Tigris-Euphrates delta forming a vast wetland in the south. Mud-built remains are especially vulnerable to erosion, and floods have damaged major monuments: a flood in 1888 demolished most of the Taq Kasra palace.\n\n## Roofing history\n\n**Sumerian cities.** Uruk, Ur and Eridu grew on the edges of the southern freshwater marshes between the 4th and 3rd millennia BC. Mud was the main building material, used for temples and ziggurats.\n\n**Reed architecture.** A carved image of a reed guest house (*mudhif*) from Uruk, about 3300 BC, is held by the British Museum, showing the form has been built for at least 5,000 years.\n\n**Babylon.** The legendary Hanging Gardens of Babylon are the region's most famous, and most debated, \"roof garden\" (see hanging-gardens-of-babylon).\n\n**Sasanian.** The Taq Kasra at Ctesiphon, built sometime between the 3rd and 6th centuries AD, has a brick vault about 37 m (121 ft) high and 26 m (85 ft) across, built without timber centring by laying bricks at an angle against the rear wall with fast-setting mortar. Part of it collapsed on 7 March 2019. See taq-kasra.\n\n**Modern.** As elsewhere in the region, new buildings mostly have flat reinforced concrete roofs (see roofing-in-the-middle-east-and-gulf).\n\n## Traditional and vernacular roofs\n\n- **Mudhif:** a tunnel-shaped hall of bundled reed arches covered with woven reed mats, used as a sheikh's guest house; it is rebuilt about every ten years. Family reed houses include the *raba* (with entrances at both ends) and the single-room *bayt*. See mudhif.\n- **Mud brick:** flat earth roofs and vaults on mud-brick walls across the plains.\n- **Brick vaults:** vaults built without centring, a technique with a long history in a timber-poor land.\n\n## Roofing today\n\nAs across the region, flat reinforced concrete roofs are standard in towns.\n\n## Codes, standards and regulation\n\nAntiquities and Heritage Law No. 55 of 2002 protects the ancient cities of Uruk, Ur and Eridu.\n\n## Notable roofs\n\n- **The Ahwar of Southern Iraq** (UNESCO): marshes where reed mudhifs are still built, together with Uruk, Ur and Tell Eridu.\n- **Taq Kasra**, Ctesiphon: the great Sasanian brick vault.\n\n## Local roofing terms\n\n- *mudhif* (*al-muḍīf*) - reed guest house\n- *sarifa* - general term for reed structures\n- *raba* - family reed house with doors at both ends\n- *bayt* - single-room reed house\n- *ihdri* - the reed most used in marsh building\n\n## The marsh draining\n\nThe marsh communities (Ahwari or Marsh Arabs) numbered about half a million in the 1980s. From about 1993 the marshes were drained by the government; after 2003 residents broke the dykes and reed building resumed in reflooded areas.\n\n## Sources and gaps\n\nDetailed climate data and information on modern Iraqi roofing practice, census data, codes and industry: published information is limited.","key_facts":[{"label":"Oldest roof form","value":"Reed mudhif, at least 5,000 years"},{"label":"Ancient material","value":"Mud brick"},{"label":"Landmark vault","value":"Taq Kasra, c. 37 m (121 ft) high"},{"label":"Heritage law","value":"Antiquities and Heritage Law No. 55 of 2002"}],"related":["mudhif","taq-kasra","hanging-gardens-of-babylon","mud-roof","flat-roof","water-reed-thatch","barrel-vault-roof","roofing-in-iran","roofing-in-syria","roofing-in-kuwait","roofing-in-saudi-arabia","roofing-in-jordan","roofing-in-turkey","roofing-in-the-middle-east-and-gulf"],"sources":[{"title":"The Ahwar of Southern Iraq: Refuge of Biodiversity and the Relict Landscape of the Mesopotamian Cities","url":"https://whc.unesco.org/en/list/1481","publisher":"UNESCO World Heritage Centre"},{"title":"Mudhif","url":"https://en.wikipedia.org/wiki/Mudhif","publisher":"Wikipedia"},{"title":"Taq Kasra","url":"https://en.wikipedia.org/wiki/Taq_Kasra","publisher":"Wikipedia"}]},{"slug":"roofing-in-ireland","title":"Roofing in Ireland","category":"world-roofing","type":"place","country":{"name":"Ireland","iso2":"IE"},"summary":"Irish roofing: a thatch tradition replaced by slate and later concrete tile and fibre-cement slate, all built to resist Atlantic wind and rain.","body":"Ireland has a mild, very wet Atlantic climate with frequent strong winds, especially in the west. Roofs are almost always pitched, and resistance to wind-driven rain and storm uplift is the main design concern. The traditional roof of the countryside was thatch; slate took over in towns and on larger farmhouses in the 19th century, and concrete tiles and fibre-cement slates are now the usual coverings on new houses.\n\n## Climate and hazards\n\nStorms crossing from the Atlantic make secure fixing of slates, tiles, ridges and verges the key detail. In exposed western districts, traditional thatched roofs were tied down with ropes weighted by stones or fixed to pegs in the walls. Modern practice follows British fixing methods: the UK code of practice BS 5534, which no longer accepts mortar alone for fixing ridges and verges, is widely used as a reference in Ireland. Wind loads are calculated to the Eurocodes with Irish national parameters.\n\n## Roofing history\n\nStraw was among the commonest materials of traditional Irish building, and the whitewashed thatched cottage belongs to a very old vernacular tradition. Slate was imported from Wales: a small export trade in Welsh slate to Ireland existed by the late 16th century, and in 1713 fourteen shipments carried 415,000 slates to Dublin. North Wales later exported skilled quarrymen as well as slate. Irish quarries also produced roofing slate; slate from Valentia Island in County Kerry was supplied for the Houses of Parliament in London, and the quarry reopened in 1998.\n\nThrough the 19th and 20th centuries thatch declined sharply as slate, then corrugated iron and concrete tiles became cheaper and easier to obtain. Surviving thatched cottages are now mostly heritage properties or holiday homes.\n\n## Traditional and vernacular roofs\n\nThe traditional cottage was a long, narrow, single-storey building with thick stone or mud walls and a roof of timber couples (rafters) carrying thatch. Common thatching materials were oat, wheat or rye straw and, near rivers and lakes, water reed. Thatch was often laid over a base layer of sods and needs a steep pitch, generally about 45-55 degrees. Villages such as Kilmore Quay in County Wexford still have groups of thatched houses. Heritage grant schemes have been used to help owners re-thatch traditional cottages.\n\n## Roofing today\n\nNatural slate, much of it imported from Spain, fibre-cement slates and interlocking concrete tiles are the common coverings on new Irish houses. Clay tiles are less traditional in Ireland than in England. Flat roofs on extensions and commercial buildings use bituminous and single-ply membranes, often with insulation above the deck.\n\n## Codes, standards and regulation\n\nIn the Republic of Ireland, roof construction is controlled by the Building Regulations and their Technical Guidance Documents. Northern Ireland, part of the United Kingdom, has its own Building Regulations. Irish Standards (I.S.) and European EN product standards apply to roofing products, and British Standards such as BS 5534 are commonly referred to for slating and tiling practice.\n\n## Industry\n\nTile and slate supply is dominated by international groups: BMI Group markets Redland roof tiles in the UK and Ireland. Valentia slate is one of the few domestic roofing stones still quarried.\n\n## Notable roofs\n\nIreland's notable roofs are mainly vernacular: the surviving thatched cottages of the south-east and west, and the slate roofs of Georgian Dublin and market towns.\n\n## Sources and gaps\n\nNational data on roof coverings, on the number of surviving thatched buildings and on Irish-language roofing terms: published information is limited.","key_facts":[{"label":"Climate driver","value":"Atlantic wind and driving rain"},{"label":"Dominant materials today","value":"Natural slate, fibre-cement slate, concrete tile"},{"label":"Traditional material","value":"Straw and water-reed thatch"},{"label":"Building code","value":"Building Regulations and Technical Guidance Documents (Republic); separate NI regulations"},{"label":"Welsh slate to Dublin, 1713","value":"415,000 slates in 14 shipments"}],"regions":["Europe"],"aliases":["Irish roofing"],"related":["irish-thatch","roofing-in-the-united-kingdom","natural-slate","welsh-slate-industry","fibre-cement-slate","concrete-roof-tile","bs-5534","spanish-slate"],"company":null,"sources":[{"title":"Architecture of Ireland","url":"https://en.wikipedia.org/wiki/Architecture_of_Ireland","publisher":"Wikipedia"},{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"},{"title":"Valentia Island","url":"https://en.wikipedia.org/wiki/Valentia_Island","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Slate industry","url":"https://en.wikipedia.org/wiki/Slate_industry","publisher":"Wikipedia"},{"title":"The Slate Landscape of Northwest Wales","url":"https://whc.unesco.org/en/list/1633","publisher":"UNESCO World Heritage Centre"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"}]},{"slug":"roofing-in-israel","title":"Roofing in Israel","category":"world-roofing","type":"place","country":{"name":"Israel","iso2":"IL"},"regions":["Middle East"],"company":null,"summary":"Israeli roofing: flat concrete roofs crowned with solar water heaters, mandatory since 1980, and the Modernist flat roofs of the White City.","aliases":["Israeli roofing","Roofs of Israel","dud shemesh"],"body":"The defining Israeli roof is flat, concrete and crowded with equipment, above all the solar water heater (*dud shemesh*, \"sun boiler\"), which the country made mandatory on most new homes in 1980. Israel is widely cited as the first country to pass a solar building law, and over 90% of homes now heat water with the sun.\n\n## Climate and hazards\n\nIsrael has a hot, sunny climate with dry summers and a short winter rainy season, ranging from the Mediterranean coast to the Negev desert. Strong sunshine makes solar water heating effective.\n\n## Roofing history\n\n**Pre-Pottery Neolithic.** Ancient Jericho (Tell es-Sultan), in the West Bank, has deposits going back to about 10,500 BC (see roofing-in-palestine). Round, semi-subterranean houses of the period had stone foundations and mud-brick upper walls; how they were roofed are not well documented in published sources.\n\n**Modern Movement.** Tel Aviv's White City, built from the early 1930s to the 1950s on a master plan by Patrick Geddes (1925-27), is a UNESCO-listed ensemble of about 1,000 historic buildings by European-trained architects of the Modern Movement, adapted to local climatic conditions. Flat roofs are part of this architecture; many buildings have since gained rooftop additions, which conservation rules now control.\n\n**Solar water heaters.** During a fuel shortage in the early 1950s, engineer Levi Yissar founded NerYah (1953), the first commercial solar water-heater manufacturer. By 1967 about 5% of households used solar water heating. After the 1970s oil crisis, Harry Zvi Tabor developed the prototype of the heater now on most roofs, and in 1980 the Knesset required solar water heaters on new homes.\n\n## Traditional and vernacular roofs\n\nTraditional Levantine flat earth roofs and stone vaults belong to the shared heritage of the region (see roofing-in-palestine, roofing-in-jordan and roofing-in-lebanon).\n\n## Roofing today\n\n- **Flat concrete roofs** dominate housing and commercial buildings, carrying solar water heaters, water tanks and plant.\n- **Solar water heaters** are on over 90% of homes; the Ministry of National Infrastructures estimates they save about 2 million barrels (320,000 m³) of oil a year. About 445,730 m² of glazed collectors were in place in 2013.\n- **Rooftop photovoltaics:** cumulative PV capacity rose from 0.9 MW in 2004 to 4,750 MW in 2022, and from 2023 all new commercial buildings must install rooftop PV.\n\n## Codes, standards and regulation\n\n- **Solar water heater obligation (1980):** applies to new buildings under 27 m (89 ft), roughly 8-9 floors, except industrial and trade buildings and hospitals. Extended in 2012 to taller residential buildings, which must supply the top seven floors. Minimum tanks are 60 L (16 US gal) for one-room flats, 120 L (32 US gal) for two or three rooms and 150 L (40 US gal) for larger flats. Without solar provision, a construction permit is not granted.\n- **Rooftop PV for new commercial buildings:** required from 2023.\n\n## Industry\n\nNerYah (founded 1953) was the first commercial solar water-heater maker. Between 2010 and 2014 about 88% of annual solar water-heater installations replaced existing systems.\n\n## Notable roofs\n\n- **White City of Tel Aviv** (UNESCO): Modern Movement flat-roofed buildings.\n\n## Local roofing terms\n\n- *dud shemesh* - solar water heater (\"sun boiler\")\n\n## Sources and gaps\n\nData on other roof hazards, such as seismic and rain loads, and information on traditional roof construction, seismic and roofing codes and roofing manufacturers: published information is limited.","key_facts":[{"label":"Dominant roof","value":"Flat reinforced concrete"},{"label":"Solar water heater law","value":"1980, widely cited as the first in the world"},{"label":"Homes with solar water heating","value":"Over 90%"},{"label":"Rooftop PV rule","value":"New commercial buildings from 2023"},{"label":"Heritage ensemble","value":"White City of Tel Aviv (UNESCO)"}],"related":["rooftop-solar-water-heater","rooftop-solar-pv","flat-roof","solar-roof-mounting","roofing-in-palestine","roofing-in-jordan","roofing-in-lebanon","roofing-in-syria","roofing-in-cyprus"],"sources":[{"title":"Solar power in Israel","url":"https://en.wikipedia.org/wiki/Solar_power_in_Israel","publisher":"Wikipedia"},{"title":"Israel: Front runner in Solar Building Code with Strong Impact on Market","url":"https://solarthermalworld.org/news/israel-front-runner-solar-building-code-strong-impact-market/","publisher":"solarthermalworld.org"},{"title":"White City of Tel-Aviv – the Modern Movement","url":"https://whc.unesco.org/en/list/1096","publisher":"UNESCO World Heritage Centre"},{"title":"Pre-Pottery Neolithic A","url":"https://en.wikipedia.org/wiki/Pre-Pottery_Neolithic_A","publisher":"Wikipedia"}]},{"slug":"roofing-in-italy","title":"Roofing in Italy","category":"world-roofing","type":"place","country":{"name":"Italy","iso2":"IT"},"regions":["Europe"],"company":null,"summary":"How Italy roofs its buildings: coppi and Roman-style tile roofs, stone slabs in the Alps and Puglia, flat terraces in the south, and many landmark domes.","aliases":["Italian roofing","Tetti in Italia","Coperture in Italia"],"body":"Italy has one of the longest continuous histories of tiled roofs anywhere. Clay tiles arrived from Greece in the 7th-6th centuries BC, the Etruscans developed richly decorated terracotta roofs, and Rome turned tile making into an industry whose stamped products still help archaeologists date buildings. The country also holds several of the most important domes ever built.\n\n## Climate and hazards\n\nRoofs range from Alpine conditions, with heavy snow, to hot, dry summers in the south and on the islands, where flat roofs and masonry vaults were favoured. Much of Italy is seismic. Heavy roofs and poorly tied timber structures have contributed to earthquake damage, and retrofit practice concentrates on tying roof structures to walls, lightening roofs and strengthening connections. Since 2008 Italy's technical standards have made seismic verification mandatory nationwide. Flooding in regions such as Umbria and Puglia has also been cited as a climate-driven risk to traditional buildings.\n\n## Roofing history\n\n**Etruscans and Greeks.** Fired clay tiles spread from Greece into southern and central Italy within about fifty years of their first use near Corinth around 700-650 BC. Early Villanovan hut urns show houses with sloping roofs, crossed ridge timbers and a smoke hole, and ordinary dwellings were of timber and thatch. Monumental Etruscan temples, from around 600 BC, had timber roofs whose edges were covered in brightly painted terracotta, with antefixes and rows of statues along the ridge; the Apollo of Veii belonged to such a group. Sites such as Poggio Civitate and Acquarossa had tiled roofs and architectural terracottas by the 6th century BC.\n\n**Rome.** The Romans made pan-and-cover tiling (*tegula* and *imbrex*) standard across the empire. From around the mid-1st century BC brick and tile makers stamped their products, at first with a name, later with the owner, the yard supervisor and, from AD 110, the consuls of the year. Production centred on clay-rich estates, such as a brickyard of Domitia Calvilla, mother of Marcus Aurelius, at Bomarzo, and eventually became an imperial monopoly. The Pantheon's concrete dome, completed under Hadrian, is generally described as the largest unreinforced concrete dome in the world.\n\n**Byzantine and medieval.** San Vitale in Ravenna (547) and St Mark's in Venice show Byzantine domed building, whose domes were covered externally with lead or tiles.\n\n**Renaissance and Baroque.** Brunelleschi's dome of Florence Cathedral (1420-1436) was built without full centring, and St Peter's dome in Rome, designed by Michelangelo, was completed in 1590.\n\n## Traditional and vernacular roofs\n\n- **Coppi:** curved tiles about 45-50 cm (18-20 in) long and 13-20 cm (5-8 in) wide, needing about 28-30 per m² and weighing about 60-66 kg/m² (12-14 lb/ft²), normally at a pitch of at least 30%. Laid as alternating channels (*canali*) and covers (*coperte*), or, mainly in central Italy, over flat *embrici* in the *alla romana* or *alla fiorentina* manner used almost exclusively in Tuscany. Regional variants include the *coppo veneto* and *coppo piemontese*.\n- **Alpine stone roofs:** heavy slabs of gneiss or schist (*piode*, *lose*) on massive timber structures in the Aosta Valley, Piedmont and Lombardy.\n- **Trulli:** dry-stone houses of Puglia with corbelled stone domes and outer cones of limestone slabs (*chianche*); the oldest surviving examples date from the mid-14th century.\n- **Flat roofs and vaults:** common in Sicily, Campania and the south, where they also collect rainwater.\n\n## Roofing today\n\nInterlocking clay and concrete tiles are widely used on new houses, and S-shaped single-piece tiles that combine channel and cover lay faster than coppi. These are generally not permitted in historic centres, where repairs normally use traditional coppi, often reclaimed.\n\n## Codes, standards and regulation\n\nStructural design follows the *Norme tecniche per le costruzioni* (NTC); the Ministerial Decree of 17 January 2018, in force from 22 March 2018, replaced the 2008 edition. The NTC uses the limit-state method based on the Eurocodes and includes chapters on snow and wind actions and on seismic design, with a strong focus on upgrading existing buildings. Earlier design rules date back to Royal Decree 2229/1939 and Law 1086/1971.\n\n## Industry\n\nItaly produces clay coppi both by traditional moulding and by industrial extrusion, with coloured, glazed and artificially aged versions.\n\n## Notable roofs\n\n- Pantheon dome, Rome\n- Florence Cathedral dome\n- St Peter's dome (Vatican City)\n- Trulli of Alberobello (UNESCO)\n- Byzantine domes of Ravenna and St Mark's, Venice\n\n## Local roofing terms\n\n- *tetto* - roof; *copertura* - roof covering\n- *coppo* / *coppi* - curved tile(s); *canale* - channel tile; *coperta* - cover tile\n- *embrice*, *tegola* - flat pan tile\n- *piode*, *lose* - Alpine stone slabs\n- *chianche*, *chiancarelle* - limestone slabs of trullo cones\n- *tetto alla toscana* - Tuscan roof of coppi and embrici\n## Sources and gaps\n\nCensus figures on roof materials and information on individual manufacturers: published information is limited.","key_facts":[{"label":"Traditional tiles","value":"Coppi; coppi and embrici (tegole)"},{"label":"Tile arrival","value":"From Greece, c. 7th-6th century BC"},{"label":"Coppo size","value":"About 45-50 cm long, 28-30 per m²"},{"label":"Building code","value":"NTC 2018 (DM 17 January 2018)"},{"label":"Seismic hazard","value":"High; seismic checks mandatory nationwide since 2008"}],"related":["coppo-tile","imbrex-and-tegula","etruscan-terracotta-roofs","roman-brick-and-tile-stamps","pantheon-dome","florence-cathedral-dome","st-peters-basilica-dome","trulli-of-alberobello","stone-slate","clay-roof-tile","roofing-in-greece","roofing-in-san-marino","roofing-in-vatican-city","roofing-in-slovenia","roofing-in-france","spanish-mediterranean-terracotta-roof"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"The Trulli of Alberobello","url":"https://whc.unesco.org/en/list/787","publisher":"UNESCO World Heritage Centre"},{"title":"Coppo","url":"https://it.wikipedia.org/wiki/Coppo","publisher":"Wikipedia (Italian)"},{"title":"Etruscan architecture","url":"https://en.wikipedia.org/wiki/Etruscan_architecture","publisher":"Wikipedia"},{"title":"Roman brick","url":"https://en.wikipedia.org/wiki/Roman_brick","publisher":"Wikipedia"},{"title":"Imbrex and tegula","url":"https://en.wikipedia.org/wiki/Imbrex_and_tegula","publisher":"Wikipedia"},{"title":"Byzantine architecture","url":"https://en.wikipedia.org/wiki/Byzantine_architecture","publisher":"Wikipedia"},{"title":"Norme tecniche per le costruzioni","url":"https://it.wikipedia.org/wiki/Norme_tecniche_per_le_costruzioni","publisher":"Wikipedia (Italian)"},{"title":"St. Peter's Basilica","url":"https://en.wikipedia.org/wiki/St._Peter%27s_Basilica","publisher":"Wikipedia"},{"title":"Sustainability of Traditional, Historical Roofs in the Mediterranean (Sustainability, 2023)","url":"https://www.mdpi.com/2071-1050/15/17/12723","publisher":"MDPI Sustainability"}]},{"slug":"roofing-in-jamaica","title":"Roofing in Jamaica","category":"world-roofing","type":"place","country":{"name":"Jamaica","iso2":"JM"},"summary":"Jamaican roofing: Taíno thatch, Georgian timber and zinc, and modern concrete; a 2018 Building Act adopted the International Building Code.","body":"Jamaica's roofs are shaped by hurricanes, earthquakes and heavy rain. The country moved its building regulation to an International Building Code base in 2019, six years before Hurricane Melissa tore roofs from buildings across the south-west.\n\n## Climate and hazards\n\n- **Hurricanes**: Hurricane Melissa made landfall in south-western Jamaica on 28 October 2025 as a Category 5 storm with winds of about 295 km/h (185 mph), the strongest to strike the island in 174 years of records. Officials reported roofs flying off buildings, and St. Elizabeth parish was largely flooded.\n- **Earthquakes**, which the national code must also address.\n- **Heavy rain and landslides** in the mountainous interior.\n\n## Roofing history\n\n**Taíno.** Jamaica was settled by the Taíno, who built thatched houses of poles, woven straw and palm leaves in villages around central plazas (see bohio).\n\n## Roofing today\n\nRegional guidance for hurricane islands favours hip roofs and strapped rafter connections (see roofing-in-the-caribbean).\n\n## Codes, standards and regulation\n\nThe Building Act of 2018 came into operation on 15 January 2019, repealing the Kingston and St. Andrew Building Act and the Parish Councils Building Act. It prescribes the International Building Code, together with documents declared as standards by the Bureau of Standards Jamaica, as the National Building Code of Jamaica. The Bureau advises the minister on how far the international codes apply to Jamaica and recommends accreditation standards for materials and methods.\n\n## Notable roofs\n\nNo individually roofs are listed.\n\n## Local roofing terms\n\n- *Hurricane strap*: steel strap tying rafters to walls (see hurricane-tie).\n\n## Sources and gaps\n\nDetailed accounts of colonial and later roofing history: published information is limited. No information on domestic roofing manufacturers was found in published sources.\n\nRoof material shares, vernacular and colonial roof history, and Melissa damage totals: published information is limited.","key_facts":[{"label":"Building code","value":"National Building Code of Jamaica (IBC base), in force 15 Jan 2019"},{"label":"Climate driver","value":"Hurricanes (Melissa, Cat 5, 2025)"}],"regions":["Latin America","North America"],"aliases":["Jamaican roofing"],"related":["international-building-code","hurricane-tie","hip-roof","corrugated-iron","flat-roof","hurricane-roof-damage","roofing-in-cuba","roofing-in-the-caribbean"],"company":null,"sources":[{"title":"Building for the Future: The New Building Act and National Building Code","url":"https://dunncox.com/articles/building-for-the-future-the-new-building-act-and-national-building-code/","publisher":"DunnCox"},{"title":"Category 5 Hurricane Melissa makes landfall in Jamaica","url":"https://www.africanews.com/2025/10/29/category-5-hurricane-melissa-makes-landfall-in-jamaica","publisher":"Africanews"},{"title":"Taíno","url":"https://en.wikipedia.org/wiki/Ta%C3%ADno","publisher":"Wikipedia"}]},{"slug":"roofing-in-japan","title":"Roofing in Japan","category":"world-roofing","type":"place","country":{"name":"Japan","iso2":"JP"},"summary":"Japanese roofing: kayabuki thatch, cypress-bark and shingle temple roofs and kawara clay tile, now joined by lighter metal and slate for earthquakes.","body":"In traditional Japanese architecture the roof is the dominant element, often making up about half of a building's visible mass. Deep, gently curved eaves project well beyond the walls, shading verandas and giving interiors their characteristically soft light. Japan developed an unusually wide range of roof coverings, from grass thatch and cypress bark to thin wooden shingles and fired clay tile, and the skills to make and maintain them are recognised by UNESCO as intangible cultural heritage.\n\n## Climate and hazards\n\nJapan has heavy summer rain, a typhoon season, deep snow on the Sea of Japan side and in the mountains, and frequent earthquakes. Steep thatched roofs such as those of Shirakawa-go are designed to shed snow; deep eaves protect timber walls from rain; and widely reported tile damage in earthquakes and typhoons has driven both lighter roof coverings and mechanical fixing of tiles. Dense timber towns made fire a constant danger, which pushed cities toward tiled, non-combustible roofs.\n\n## Roofing history\n\n**Prehistory.** Pit dwellings of the prehistoric periods were roofed with grass, and thatch remained the roof of ordinary rural houses into the 20th century.\n\n**Shrines.** The Ise Grand Shrine preserves one of the oldest Japanese roof forms, *shinmei-zukuri*, with a thatched reed roof, *chigi* finials and *katsuogi* billets on the ridge. Its buildings are rebuilt every 20 years in the Shikinen Sengū; the first ceremonial rebuilding took place in 692 under Empress Jitō, and the present buildings date from 2013, the 62nd rebuilding.\n\n**Arrival of tile.** Fired clay tiles came with Buddhism. In 588 the Korean kingdom of Baekje sent craftsmen, including four tile makers, to build Asuka-dera, the first full Buddhist temple in Japan. The Kondō of Hōryū-ji has a tiled hip-and-gable (*irimoya*) roof, and its 7th-century pagoda is among the oldest wooden buildings in the world. The tile technology itself descends from the tile tradition that developed in China under the Western Zhou and later spread to Korea and Japan.\n\n**Heian and medieval periods.** Heian-period aristocrats roofed their mansions with layered cypress bark (*hiwadabuki*) rather than tile, and builders developed the \"hidden roof\" (*noyane*), a separate structure above the visible ceiling that allowed a steeper outer pitch and better drainage. Temples such as Kinkaku-ji and Ginkaku-ji use roofs of very thin split-wood shingles fixed with bamboo nails. In Kyoto in the late Heian and Muromachi periods, town roofs were clad in thin shingles held down with stones.\n\n**Edo period.** Distinctive farmhouse (*minka*) styles, including *gasshō-zukuri*, matured. Urban townhouses (*machiya*) and storehouses (*dozo*) moved from thatch and shingle to clay tile for fire protection, and the *udatsu*, a wall projecting above the roofline, served as a firebreak and status symbol.\n\n**Modern era.** In the 20th century most thatched houses were re-roofed, and clay tile was joined by metal sheet and later fibre-cement and coated-steel products.\n\n## Traditional and vernacular roofs\n\n- **Kayabuki** - grass thatch, usually miscanthus (*susuki*) or reed; farmhouses (*nōka*) were mostly hipped (*yosemune*) and thatched.\n- **Gasshō-zukuri** - very steep \"praying hands\" thatched roofs of Shirakawa-go and Gokayama, with attic floors used for silkworm rearing.\n- **Hiwadabuki** - layered hinoki cypress bark, on shrines, palaces and temples.\n- **Kokerabuki** - thin wooden shingles of cypress fixed with bamboo nails.\n- **Kawarabuki** - clay tile; the traditional pan-and-cover form is *hongawarabuki*. Ridges carry *onigawara* (ogre tiles) or *shachi* fish ornaments, and eaves end in circular tiles.\n- **Roof shapes** - *kirizuma* (gable), *yosemune* (hip), *irimoya* (hip-and-gable) and *hōgyō* (pyramidal).\n\n## Roofing today\n\nClay *kawara* remains common on detached houses, but lighter coverings have gained ground: coated steel and zinc-aluminium-coated sheet, and fibre-cement slates. Lighter roofs reduce seismic forces on timber frames, and modern tile practice fixes tiles with screws, wires or clips rather than bedding them in clay. Apartment and commercial buildings mostly have flat concrete roofs with membranes.\n\n## Codes, standards and regulation\n\nThe **Building Standards Act** (Act No. 201 of 24 May 1950) sets national minimum standards for building sites, structure, equipment and use. Its Article 22 lets authorities designate areas where roofs must be covered with non-combustible materials to stop fire spreading between buildings; Yokohama, for example, applies the designation across the whole city. Stricter roof rules apply in fire-prevention districts.\n\n## Industry\n\nKawara production is concentrated in traditional centres such as Sanshū (Aichi) and Sekishū (Shimane).\n\n## Notable roofs\n\n- **Ise Grand Shrine** - thatched *shinmei-zukuri* roofs rebuilt every 20 years.\n- **Hōryū-ji**, Nara - tiled Kondō and 7th-century pagoda.\n- **Historic Villages of Shirakawa-go and Gokayama** (UNESCO, 1995) - *gasshō-zukuri* thatch.\n- **Kinkaku-ji and Ginkaku-ji**, Kyoto - thin wooden shingle roofs.\n\n## Local roofing terms\n\n- *yane* (屋根) - roof\n- *kawara* (瓦) - roof tile; *onigawara* - ogre ridge tile\n- *kayabuki* (茅葺) - thatch\n- *hiwadabuki* (檜皮葺) - cypress-bark roofing\n- *kokerabuki* (柿葺) - thin-shingle roofing\n- *noki* (軒) - eaves\n\n## Sources and gaps\n\nMarket data, roof-material statistics and further manufacturer data for Japan: published information is limited.","key_facts":[{"label":"Traditional coverings","value":"Kawara tile, cypress bark, wood shingle, thatch"},{"label":"Tile introduced","value":"588, with Baekje craftsmen"},{"label":"Roof types","value":"Irimoya, kirizuma, yosemune, hōgyō"},{"label":"Key hazards","value":"Earthquakes, typhoons, snow, fire"},{"label":"Building code","value":"Building Standards Act (1950)"},{"label":"UNESCO heritage","value":"Wooden architecture skills (2020); Shirakawa-go (1995)"}],"regions":["East Asia"],"aliases":["Japanese roofing"],"related":["japanese-kawara-tile","history-of-japanese-kawara","asuka-dera","gassho-zukuri","irimoya","pagoda-roof","hiwadabuki","kokerabuki","kayabuki","dougong","chiwen","thatch","wood-shingle","clay-roof-tile","earthquake-roofing","roofing-in-china","roofing-in-south-korea","hanok-roof"],"company":null,"sources":[{"title":"Japanese architecture","url":"https://en.wikipedia.org/wiki/Japanese_architecture","publisher":"Wikipedia"},{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Minka","url":"https://en.wikipedia.org/wiki/Minka","publisher":"Wikipedia"},{"title":"Ise Grand Shrine","url":"https://en.wikipedia.org/wiki/Ise_Grand_Shrine","publisher":"Wikipedia"},{"title":"Shirakawa-go","url":"https://en.wikipedia.org/wiki/Shirakawa-go","publisher":"Wikipedia"},{"title":"Historic Villages of Shirakawa-go and Gokayama","url":"https://whc.unesco.org/en/list/734","publisher":"UNESCO World Heritage Centre"},{"title":"UNESCO Intangible Cultural Heritage of Humanity in Japan","url":"https://www.nippon.com/en/features/h00347/","publisher":"Nippon.com"},{"title":"Kawara (tile)","url":"https://www.japanesewiki.com/culture/Kawara%20(tile).html","publisher":"Japanese Wiki Corpus"},{"title":"Asuka-dera","url":"https://en.wikipedia.org/wiki/Asuka-dera","publisher":"Wikipedia"},{"title":"Onigawara","url":"https://en.wikipedia.org/wiki/Onigawara","publisher":"Wikipedia"},{"title":"Building Standards Act (Act No. 201 of 1950)","url":"https://www.japaneselawtranslation.go.jp/en/laws/view/4024/en","publisher":"Japanese Law Translation, Ministry of Justice"},{"title":"Article 22 designated areas (Building Standard Law)","url":"https://en.city.yokohama.lg.jp/business/bunyabetsu/kenchiku/tetsuduki/kuiki/22.html","publisher":"City of Yokohama"},{"title":"Researchers reconstruct earliest composite-tiled roofs","url":"https://phys.org/news/2023-07-reconstruct-earliest-composite-tiled-roofs.html","publisher":"Phys.org"},{"title":"Pagoda","url":"https://en.wikipedia.org/wiki/Pagoda","publisher":"Wikipedia"}]},{"slug":"roofing-in-jordan","title":"Roofing in Jordan","category":"world-roofing","type":"place","country":{"name":"Jordan","iso2":"JO"},"regions":["Middle East"],"company":null,"summary":"Jordanian roofing: basalt slab roofs on corbels and arches at Umm el-Jimal, the rock-cut city of Petra, and modern flat concrete roofs.","aliases":["Jordanian roofing","Roofs of Jordan"],"body":"Jordan's roofing history is written largely in stone. In the north, the basalt town of Umm el-Jimal preserves late antique buildings roofed with long stone slabs on corbels and arches; in the south, the Nabataean city of Petra is \"half-built, half-carved\" into sandstone cliffs, so many of its spaces are roofed by living rock.\n\n## Climate and hazards\n\nJordan is largely arid, with hot, dry summers and limited winter rain. Wind and rain steadily erode Petra's sandstone monuments, and flash floods down Wadi Musa through the Siq are a risk if the Nabataean water-diversion system is not maintained. Earthquakes are a historic hazard: a major quake in 747 AD destroyed Umm el-Jimal.\n\n## Roofing history\n\n**Nabataean Petra.** The Nabataean civilisation flourished from about the 4th century BC to the 1st century AD. At Petra, tombs and halls such as the Khasneh, the Urn Tomb, the Palace Tomb and the Deir were carved directly into rock, while freestanding buildings such as the Qasr al-Bint temple, baths, a theatre and later Byzantine churches were built in masonry. A carved chamber needs no roof covering in the usual sense: the rock above is the roof, though it still weathers.\n\n**Late antique Hauran.** In the basalt region of northern Jordan, builders roofed houses, churches and barracks with thin basalt slabs laid on projecting corbels, often two or three rows deep, or on transverse arches of dry-laid blocks. The Julianos Church at Umm el-Jimal dates to 345 AD, and the town had about 15 churches in late antiquity. Lightweight volcanic scoria was used for vaults. See hauran-basalt-corbelled-roofs.\n\n**Modern.** Flat reinforced concrete roofs are standard in new construction, as across the region.\n\n## Traditional and vernacular roofs\n\n- **Basalt corbel-and-slab roofs:** Hauran region (Umm el-Jimal).\n- **Arch-and-slab roofs:** wider rooms spanned by stone arches carrying slabs.\n- **Rock-cut chambers:** Petra and other Nabataean sites.\n\n## Notable roofs\n\n- **Petra** (UNESCO): rock-cut tombs and temples; freestanding Qasr al-Bint temple.\n- **Umm el-Jimal**: late antique basalt town with corbelled stone roofs, since added to the UNESCO World Heritage List, as reported by the Emirates News Agency.\n\n## Sources and gaps\n\nData on current roofing materials, local roofing terms and information on modern roofing materials, codes and industry in Jordan: published information is limited.","key_facts":[{"label":"Ancient stone roofs","value":"Basalt slabs on corbels and arches"},{"label":"Rock-cut architecture","value":"Petra (Nabataean)"},{"label":"Umm el-Jimal destroyed","value":"Earthquake, 747 AD"},{"label":"Modern","value":"Flat concrete"}],"related":["hauran-basalt-corbelled-roofs","flat-roof","roofing-in-syria","roofing-in-saudi-arabia","roofing-in-israel","roofing-in-palestine","roofing-in-iraq"],"sources":[{"title":"Petra","url":"https://whc.unesco.org/en/list/326","publisher":"UNESCO World Heritage Centre"},{"title":"Engineering the reconstruction of Hawrān's Ecclesiae during late antiquity: case of Julianos church in Umm el-Jimal, Jordan (Al Rabady and Rababeh, 2022)","url":"https://www.nature.com/articles/s40494-022-00727-0","publisher":"npj Heritage Science"},{"title":"Jordan's 'Umm al-Jimal' added to UNESCO heritage list","url":"https://www.wam.ae/en/article/141gmc8-jordan’s-umm-al-jimal-added-unesco-heritage-list","publisher":"WAM (Emirates News Agency)"}]},{"slug":"roofing-in-kazakhstan","title":"Roofing in Kazakhstan","category":"world-roofing","type":"place","country":{"name":"Kazakhstan","iso2":"KZ"},"summary":"Kazakh roofing runs from the felt-domed yurt and its shangyrak crown, a national emblem, to Timurid brick domes and Soviet-era flat-roofed apartment blocks.","body":"Kazakhstan, the largest country in Central Asia, spans steppe, desert and the high mountains of the Tien Shan and Altai. For most of its history its characteristic roof was portable: the domed felt roof of the Kazakh yurt, *kiyiz üy* (\"felt house\"), closed at the top by a wooden crown ring, the **shangyrak**. The shangyrak remains so strongly tied to home and family that it sits at the centre of the national emblem. Permanent architecture includes the great Timurid brick dome at Turkistan, while 20th-century towns were built largely with Soviet apartment blocks.\n\n## Climate and hazards\n\nThe climate is strongly continental, with very cold, windy winters and hot summers; snow and wind are the main loads on roofs over most of the country. The south-east, around Almaty, lies in an earthquake zone along the northern Tien Shan, and seismic design has been central to building regulation since the Soviet period.\n\n## Roofing history\n\nYurt-type dwellings have been used on the steppe for millennia; the earliest written description of yurt-like tents is traced to Herodotus' account of the Scythians, who lived across the Black Sea and Central Asian steppe from about 600 BCE. The Kazakh yurt has a folding lattice wall (*kerege*), bent roof poles (*uyk*) and the shangyrak at the top, all covered with felt made from the wool of the herders' own sheep. In old Kazakh communities the yurt itself might be repaired or rebuilt many times, but the shangyrak was kept and passed from father to son, its smoke stains a sign of the family's age.\n\nThe outstanding permanent roof is that of the **Mausoleum of Khoja Ahmed Yasawi** in Turkistan, begun in 1389 for Timur and left unfinished at his death in 1405. Its main hall is covered by a brick dome 18.2 m (59.7 ft) in diameter, described as the largest surviving brick dome in Central Asia, and the tomb chamber has a double dome whose outer shell, rising to about 28 m (92 ft), is covered with green glazed hexagonal tiles.\n\nDuring the Soviet period, towns and new cities were built with masonry and prefabricated concrete apartment blocks of standard series used across the USSR, including the five-storey *khrushchyovka* types built from about 1956 into the 1970s and their taller successors of the 1970s and 1980s.\n\n## Traditional and vernacular roofs\n\n- **Kiyiz üy (yurt)**: felt over a timber frame of kerege wall, uyk poles and shangyrak crown. Men make the frame; women make the felt coverings and interior decoration.\n\n## Roofing today\n\nYurt-making remains a living craft: in 2014 UNESCO inscribed the knowledge and skills of making Kazakh and Kyrgyz yurts on its Representative List of the Intangible Cultural Heritage of Humanity.\n\n## Codes, standards and regulation\n\nAfter independence Kazakhstan issued its own seismic construction code (\"Construction in Seismic Regions\") in 1998, revised in 2001 and 2006. The current code, **SP RK 2.03-30-2017** *Construction in seismic zones*, introduced in 2017, combines general requirements from the Eurocodes with earlier national rules. The code is published by the construction research institute KazNIISA.\n\n## Notable roofs\n\n- **Mausoleum of Khoja Ahmed Yasawi, Turkistan** (1389-1405): UNESCO World Heritage Site (2003), with an 18.2 m (59.7 ft) brick dome and glazed tiled outer dome.\n- **Shangyrak**: central motif of the state emblem adopted on 4 June 1992.\n\n## Local roofing terms\n\n- *kiyiz üy* (Kazakh): felt house, yurt\n- *shangyrak* / *shanyrak* (Kazakh): yurt crown ring\n- *uyk* (Kazakh): roof pole of a yurt\n- *kerege* (Kazakh): lattice wall of a yurt\n\n## Sources and gaps\n\nHousing-census roof data, details of the roofing industry and descriptions of modern private houses: published information is limited.","key_facts":[{"label":"Traditional roof","value":"Felt-covered yurt (kiyiz uy) with shangyrak crown"},{"label":"National symbol","value":"Shangyrak on the state emblem (1992)"},{"label":"Landmark dome","value":"Khoja Ahmed Yasawi mausoleum, 18.2 m (59.7 ft) brick dome"},{"label":"Climate driver","value":"Continental extremes, snow, wind, earthquakes in the south-east"},{"label":"Seismic code","value":"SP RK 2.03-30-2017, Construction in seismic zones"}],"regions":["Central Asia"],"aliases":["Kazakh roofing","roofs of Kazakhstan"],"related":["tunduk-and-shangyrak","ger-roof","dome","middle-eastern-domes","flat-roof","snow-load","earthquake-roofing","roofing-in-kyrgyzstan","roofing-in-uzbekistan","roofing-in-russia","roofing-in-china","roofing-in-mongolia"],"company":null,"sources":[{"title":"Yurt","url":"https://en.wikipedia.org/wiki/Yurt","publisher":"Wikipedia"},{"title":"Emblem of Kazakhstan","url":"https://en.wikipedia.org/wiki/Emblem_of_Kazakhstan","publisher":"Wikipedia"},{"title":"Traditional knowledge and skills in making Kyrgyz and Kazakh yurts (Turkic nomadic dwellings)","url":"https://ich.unesco.org/en/RL/traditional-knowledge-and-skills-in-making-kyrgyz-and-kazakh-yurts-turkic-nomadic-dwellings-00998","publisher":"UNESCO Intangible Cultural Heritage"},{"title":"Mausoleum of Khoja Ahmed Yasawi","url":"https://whc.unesco.org/en/list/1103/","publisher":"UNESCO World Heritage Centre"},{"title":"Mausoleum of Khoja Ahmed Yasawi","url":"https://en.wikipedia.org/wiki/Mausoleum_of_Khoja_Ahmed_Yasawi","publisher":"Wikipedia"},{"title":"Design regulations (Central Asia exposure model)","url":"https://docs.openquake.org/global_risk_model/central_asia/exposure/design_regulations.html","publisher":"Global Earthquake Model Foundation"},{"title":"SP RK 2.03-30-2017 Construction in seismic zones","url":"https://kazniisa.kz/wp-content/uploads/2023/04/СП-РК-2.03-30-2017-Строительство-в-сейсмических-зонах-изм86-1.pdf","publisher":"KazNIISA"},{"title":"Khrushchyovka","url":"https://en.wikipedia.org/wiki/Khrushchyovka","publisher":"Wikipedia"}]},{"slug":"roofing-in-kenya","title":"Roofing in Kenya","category":"world-roofing","type":"place","country":{"name":"Kenya","iso2":"KE"},"summary":"Kenya is roofed mainly in iron sheets (mabati): 80% of households in the 2019 census, replacing grass, papyrus, dung and palm-leaf makuti roofs.","body":"Kenya runs from a hot, humid Indian Ocean coast through dry rangelands to cool, rainy highlands around Mount Kenya and the Lake Victoria basin. Its traditional roofs reflected that range: grass and papyrus thatch on round houses inland, cattle-dung plaster on the low houses of pastoralists such as the Maasai, palm-leaf *makuti* and coral-stone roofs on the Swahili coast. Today the country is roofed overwhelmingly in corrugated metal sheet, known in Swahili as *mabati*. In the 2019 Kenya Population and Housing Census, about four in five conventional households lived under iron-sheet roofs.\n\n## Climate and hazards\n\nMuch of the country lies on or near the equator at altitude, with two rainy seasons in many areas and strong sun all year. Roofs must shed heavy tropical downpours, resist storm winds, and cope with high daytime heat gain under thin metal. The coast adds high humidity and salt-laden air, which speeds corrosion of steel and rots organic materials. In the arid north and east, rainfall is low and erratic, and roofs are also valued as rainwater-catchment surfaces.\n\n## Roofing history\n\nAmong the oldest standing roofs in the country are those of the Swahili coast, where trading towns built in stone from the late first millennium onward. At Shanga in the Lamu archipelago, stone building began in the early to mid-10th century. At Gedi, a town founded in the 12th century and rebuilt in the 15th and 16th, mosque roofs were carried on timber beams resting on square stone pillars. Lamu Old Town has been continuously inhabited for more than 700 years and is built of coral stone and mangrove timber, a combination of coral, lime and mangrove poles that UNESCO cites as typical of Swahili building.\n\nInland, houses were built of poles, mud and grass and were renewed regularly, so few old examples survive. Corrugated iron arrived in the colonial period and spread steadily after independence in 1963 as a sign of a permanent, modern house. By 2019 grass and twigs covered only about 5% of households.\n\n## Traditional and vernacular roofs\n\n- **Swahili coral-stone house** (Lamu, Mombasa, the northern coast): walls of uncoursed coral blocks in lime mortar; roofs and upper floors of thick coral laid over timber joists about 30 cm (12 in) apart. Because mangrove poles limit the span, rooms are often only about 3 m (10 ft) wide. A small thatched shelter over the rooftop or courtyard cooking area (*kidara cha meko*) kept smoke away from fine lime plaster. Lime was made by burning coral.\n- **Makuti**: thatch of sun-dried coconut palm leaves, widely used along the East African coast on houses, outbuildings and, increasingly, beach hotels, where it is treated as a mark of local character and prestige.\n- **Maasai enkaji**: a low, loaf-shaped house of poles and woven sticks, built and maintained by women, with a roof layered in grass and cow dung or a dung and mud mix that is re-plastered against wet-season wear. See Maasai enkaji.\n- **Lake basin houses**: around Lake Victoria, Luo builders used papyrus leaves for thatch.\n\n## Roofing today\n\nThe 2019 census recorded the dominant roofing material of each household's main dwelling unit (KNBS Volume IV, Table 2.12, published by county and sub-county). Nationally:\n\n| Dominant roofing material | Share of conventional households |\n|---|---|\n| Iron sheets | 80.3% |\n| Concrete and cement | 8.2% |\n| Grass and twigs | 5.1% |\n| All other materials combined | about 6.4% |\n\nConcrete roofs are typical of urban apartment blocks and commercial buildings. Middle- and upper-income houses use clay and concrete tiles and stone-coated or tile-profile steel. On the coast, makuti remains in use on resorts and some homes. Among the Maasai, timber-framed roofs covered with metal sheets are replacing dung roofs, though the fenced homestead layout survives.\n\n## Codes, standards and regulation\n\nKenya's **National Building Code 2024** was published on 1 March 2024 as Legal Notice No. 47 and formally launched by the National Construction Authority (NCA) on 17 July 2024. It repealed the Local Government (Adoptive By-Laws) (Building) Order of 1968, which had served as the building code for 56 years. The NCA announced a one-year adjustment period with training for the industry, and it operates mobile materials-testing laboratories to support quality checks on construction materials.\n\n## Industry\n\nKenya has a large domestic sheet-rolling industry. A major producer is Mabati Rolling Mills, part of Safal Group, which traces its history to 1962 and makes metallic-coated steel, roofing sheets and tiles and light steel trusses. Smaller roll-forming businesses and hardware dealers supply sheets of varying gauge and coating mass, which buyers compare because both govern corrosion life.\n\n## Notable roofs\n\n- **Lamu Old Town** (UNESCO World Heritage): coral-stone houses with coral roofs on mangrove joists.\n- **Gedi ruins**: stone mosques and houses of a 12th to 16th century Swahili town.\n- **Makuti-roofed beach hotels** on the Kenyan coast, which keep palm-leaf thatch in use at large scale.\n\n## Local roofing terms\n\n- *mabati* (Swahili): metal roofing sheets.\n- *makuti* (Swahili): coconut palm-leaf thatch.\n- *kidara cha meko* (Swahili): thatched cooking shelter in a Lamu house.\n- *enkaji* (Maa): a Maasai house; *enkang* or *ekang*: the fenced family homestead.\n\n## Sources and gaps\n\nCensus shares are the national figures from the 2019 census as reported by Africa Check from KNBS tables. Shares for individual minor materials (tiles, makuti, asbestos and others) were not given separately. No account of the history of \"mabati women's groups\" (self-help groups that saved to buy roofing sheets) was found in published sources. ","key_facts":[{"label":"Dominant material today","value":"Iron sheets, 80.3% of households (2019 census)"},{"label":"Other roofs","value":"Concrete/cement 8.2%, grass and twigs 5.1%"},{"label":"Traditional materials","value":"Grass, papyrus, makuti palm thatch, cow dung, coral stone"},{"label":"Building code","value":"National Building Code 2024 (Legal Notice No. 47)"},{"label":"Climate driver","value":"Tropical rains, strong sun, coastal salt air"}],"regions":["Africa"],"aliases":["Kenyan roofing","mabati Kenya","roofs in Kenya"],"related":["roofing-in-east-africa","mabati-rolling-mills","corrugated-iron","makuti-thatch","maasai-enkaji","swahili-coral-stone-house","palm-thatch","thatch","roofing-in-tanzania","roofing-in-uganda","rainwater-harvesting-roofs","concrete-roof-tile"],"sources":[{"title":"What share of Kenyan households use iron sheets as roofing material?","url":"https://africacheck.org/infofinder/explore-facts/what-share-kenyan-households-use-iron-sheets-roofing-material","publisher":"Africa Check"},{"title":"Table 2.12: Households by Dominant Roofing Material of Main Dwelling Unit, Residence, County and Sub-County","url":"https://census.ke/dataset/table-2-12-hholds-by-dominant-roofing-material-of-main-dwelling-unit-residence-county-and-sub-county/resource/c0b7d652-61ec-46a8-9d6f-8f3138436bb5","publisher":"Kenya National Bureau of Statistics"},{"title":"Lamu Old Town","url":"https://whc.unesco.org/en/list/1055","publisher":"UNESCO World Heritage Centre"},{"title":"Vernacular Housing of Lamu (Swahili Housing)","url":"https://www.archnet.org/sites/6076","publisher":"Archnet"},{"title":"Swahili architecture","url":"https://en.wikipedia.org/wiki/Swahili_architecture","publisher":"Wikipedia"},{"title":"Launch of the National Building Code 2024","url":"https://www.nca.go.ke/whole-story/BULDINGCODE","publisher":"National Construction Authority"},{"title":"Through the Maasai built landscapes","url":"https://artsandculture.google.com/story/ngWxTk735YTJIw","publisher":"Google Arts & Culture"},{"title":"African architecture: Geographic influences","url":"https://www.britannica.com/art/African-architecture/Geographic-influences","publisher":"Encyclopaedia Britannica"},{"title":"Makuti thatching","url":"https://en.wikipedia.org/wiki/Makuti_thatching","publisher":"Wikipedia"},{"title":"Why makuti roof is a lasting feature in Coast hotel design","url":"https://www.standardmedia.co.ke/article/2001380550/why-makuti-roof-is-a-lasting-feature-in-coast-hotel-design","publisher":"The Standard"}],"company":null},{"slug":"roofing-in-kiribati","title":"Roofing in Kiribati","category":"world-roofing","type":"place","country":{"name":"Kiribati","iso2":"KI"},"summary":"Kiribati roofing: pandanus-thatched maneaba meeting houses and homes on coral atolls; thatch still covers over half of household roofs.","body":"Kiribati is a nation of low coral atolls where the dominant traditional building is the *maneaba* (also *mwaneaba*), a huge thatched meeting house at the centre of every community. Unusually for the Pacific today, thatch of pandanus leaves still covered more than half of household roofs in a 2018 national survey, though metal is spreading, especially on South Tarawa.\n\n## Climate and hazards\n\nThe atolls are hot and humid, and as on other Pacific atolls, roofs are important catchments for rainwater. Traditional building drew on the coconut palm, pandanus and coral.\n\n## Roofing history\n\nThe traditional maneaba rests on coral slabs and has a vast roof of coconut wood, tied with coconut-fibre string and thatched with pandanus leaves. According to a study by Kerry Whincup, it contains no nails, screws or glue: wooden pins, fitted joints and coconut-husk string (*te kora*) hold it together, with specified lashings for each joint. Husks are soaked under lagoon sand for about three months before the fibre is dried and rolled by hand; men build and repair, while women make the string. The ridge pole (*te taubuki*) is hauled into place at about 12-13 m (39-43 ft).\n\nImported materials changed this tradition. On South Tarawa nearly all meeting houses now use imported materials. Whincup reports that iron roofs heat up quickly and drown out speech in rain, but they need less upkeep and are often seen as a status symbol, at the cost of fewer opportunities to pass on building skills.\n\n## Traditional and vernacular roofs\n\n- **[Maneaba](/maneaba)**: community meeting house and the basis of village and island governance; the national parliament is named the Maneaba ni Maungatabu. Three traditional styles, Tabontebike, Tabiang and Maungatabu, differ in proportions and beam layout.\n- **Pandanus thatch** (*te rau*) lashed to slats on diagonal roof beams.\n\n## Roofing today\n\nIn the 2018-19 Multiple Indicator Cluster Survey, 55.5% of household records listed thatch or palm leaf as the main roof material and 36.3% metal, tin or aluminium; about 6% had no recorded answer. These are unweighted case counts from the survey sample.\n\n## Codes, standards and regulation\n\nBuilding is regulated under the Kiribati Building Act 2006. A national building code dates from 1990; a final draft update was completed in 2012 and was reported to be under review in a regional review of Pacific building codes.\n\n## Notable roofs\n\n- **Atanikarawa maneaba**, Tabiteuea North, about 40 by 20 m (130 by 65 ft).\n- **Catholic maneaba at Koinawa**, Abaiang, about 60 by 17 m (200 by 55 ft).\n- **Eita maneaba**, an exception on South Tarawa built of traditional materials.\n\n## Local roofing terms\n\n- **Maneaba / mwaneaba**: meeting house.\n- **Te rau**: pandanus thatch. **Te kora**: coconut-husk string.\n- **Te taubuki**: ridge pole. **Oka**: diagonal roof beams.\n- **Boti**: hereditary seating places along the posts.\n\n## Sources and gaps\n\nNo domestic roofing manufacturers were identified.\n\nCensus tables of roof material (2010, 2015, 2020): published information is limited.","key_facts":[{"label":"Dominant material today","value":"Thatch/palm leaf (55.5%) ahead of metal (36.3%), MICS 2018-19"},{"label":"Traditional materials","value":"Pandanus thatch, coconut timber, coconut-husk string, coral"},{"label":"Key building","value":"Maneaba (meeting house)"},{"label":"Climate drivers","value":"Heat, low atolls, scarce fresh water"},{"label":"Building law","value":"Kiribati Building Act 2006"}],"regions":["Oceania"],"aliases":["I-Kiribati roofing","Gilbert Islands roofing"],"related":["maneaba","palm-thatch","thatch","rainwater-harvesting-roofs","roofing-in-tuvalu","roofing-in-the-marshall-islands","roofing-in-nauru","roofing-in-the-pacific-islands"],"company":null,"sources":[{"title":"Maneaba","url":"https://en.wikipedia.org/wiki/Maneaba","publisher":"Wikipedia"},{"title":"Whincup, The Kiribati maneaba (Shima vol. 4 no. 1)","url":"https://www.shimajournal.org/issues/v4n1/k.-Whincup-Shima-v4n1-113-130.pdf","publisher":"Shima: The International Journal of Research into Island Cultures"},{"title":"Kiribati MICS 2018-19, main material of roof (HC5)","url":"https://catalog.ihsn.org/catalog/10024/variable/F4/V904?name=HC5","publisher":"IHSN Survey Catalog"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-kosovo","title":"Roofing in Kosovo","category":"world-roofing","type":"place","country":{"name":"Kosovo","iso2":"XK"},"regions":["Europe"],"company":null,"summary":"Roofing in Kosovo: thick-walled stone kulla tower houses of the Dukagjini region and domed medieval Serbian Orthodox monasteries such as Visoki Dečani.","aliases":["Kosovar roofing"],"body":"Kosovo's best-documented historic buildings are the fortified stone tower houses known as *kulla* and the medieval Orthodox monasteries and churches, including the UNESCO-listed Visoki Dečani.\n\n## Climate and hazards\n\nKosovo has a continental climate, with cold winters and hot summers. The thick stone walls of traditional kullas insulated against these extremes, keeping interiors cool in summer and warm in winter. As part of Yugoslavia, Kosovo came under the first Yugoslav seismic code of 1964.\n\n## Roofing history\n\n**Medieval monasteries.** Visoki Dečani was begun in 1327 under King Stefan Dečanski and established by about 1335. Its main architect was the Franciscan Vito of Kotor, and the church blends Serbo-Byzantine traditions with Romanesque influence, with outer walls of alternating white and pink marble. It became a World Heritage site on 2 July 2004 and was placed on the List of World Heritage in Danger in 2006. Byzantine-tradition domes were typically covered with lead or regional tiles.\n\n**Tower houses.** Most surviving kullas in Kosovo date from the 18th or 19th century, and building continued into the early 20th century, especially in the Dukagjini region.\n\n## Traditional and vernacular roofs\n\n**The kulla** is a two- or three-storey stone tower, square or rectangular, built from local stone, sometimes with decorative timber on the upper floors. Walls could be up to 1 m (3.3 ft) thick at ground level, thinning toward the roof, and narrow openings called *frëngji* served as light, ventilation and loopholes. The ground floor housed storage and livestock, and the upper floors living and guest rooms. Women and children lived in an adjoining annex, the *çardak*. Examples include Jashar Pasha's Tower in Gjakova, Haxhi Zeka's Tower in Peja and the Mazrekaj Tower in Junik.\n\n## Notable roofs\n\n- Visoki Dečani Monastery (UNESCO, 1327-1335)\n- Kullas of Junik, Gjakova and Peja\n\n## Local roofing terms\n\n- *kulla* - tower house (from Arabic *qalʿa*, fort, via Persian and Turkish)\n- *frëngji* - narrow wall openings\n- *çardak* - annex\n\n## Sources and gaps\n\nDescriptions of the roof coverings of Kosovar kullas, vernacular houses and modern buildings, data on current roofing materials, current regulations and information on domestic roofing manufacturers were not found in published sources.","key_facts":[{"label":"Vernacular type","value":"Kulla stone tower house (18th-early 20th c.)"},{"label":"Wall thickness","value":"Up to 1 m (3.3 ft) at ground level"},{"label":"Landmark","value":"Visoki Dečani (1327-1335), UNESCO"}],"related":["kulla-tower-house","dome","roofing-in-albania","roofing-in-serbia","roofing-in-north-macedonia","roofing-in-montenegro"],"sources":[{"title":"Tower houses in the Balkans","url":"https://en.wikipedia.org/wiki/Tower_houses_in_the_Balkans","publisher":"Wikipedia"},{"title":"Visoki Dečani","url":"https://en.wikipedia.org/wiki/Visoki_De%C4%8Dani","publisher":"Wikipedia"},{"title":"Byzantine architecture","url":"https://en.wikipedia.org/wiki/Byzantine_architecture","publisher":"Wikipedia"},{"title":"1963 Skopje earthquake","url":"https://en.wikipedia.org/wiki/1963_Skopje_earthquake","publisher":"Wikipedia"}]},{"slug":"roofing-in-kuwait","title":"Roofing in Kuwait","category":"world-roofing","type":"place","country":{"name":"Kuwait","iso2":"KW"},"regions":["Middle East"],"company":null,"summary":"Kuwaiti roofing: courtyard houses of sea stone and mud roofed with East African mangrove poles, windcatchers, and modern concrete landmarks.","aliases":["Kuwaiti roofing","Roofs of Kuwait"],"body":"Kuwait town, founded in the early 18th century, was built of sea stone, rubble and mud brick, with roofs of mangrove poles imported from East Africa. Oil-era planning from the 1950s swept most of the old town away, and Kuwait is now known for modern landmarks such as the Kuwait Towers and Jørn Utzon's National Assembly.\n\n## Climate and hazards\n\nKuwait has extreme summer heat, which made windcatchers close to a necessity in traditional houses, and some houses installed them.\n\n## Roofing history\n\n**Old Kuwait.** Wood was scarce, so mangrove poles imported from East Africa were used for roofs, along with a few select woods from India. Walls were of stone from the sea, rubble stone with thick mud plaster, and mud brick. Houses were built around central courtyards; wealthier families had several. Early surviving mosques include Alkhamis Mosque (1772-73) and Abd AlRazzag Mosque (1797). Najdi architecture from central Arabia also influenced Kuwaiti building.\n\n**Planning era.** The first master plan was commissioned in 1952, and the old city wall was demolished as it was carried out.\n\n**Modern landmarks.** The National Assembly building, designed by Jørn Utzon in 1972, was completed in 1982. The Kuwait Towers, built in 1971-1976 and opened to the public in 1979, combine water towers with tall conical spires above spherical tanks; in 1980 the Kuwait Water Towers system, including the Kuwait Towers, received the Aga Khan Award for Architecture.\n\n## Traditional and vernacular roofs\n\n- **Flat roofs on mangrove poles:** imported poles carrying mats and earth (see chandal-roof).\n- **Windcatchers:** in some traditional houses.\n\n## Roofing today\n\nFlat reinforced concrete roofs are standard.\n\n## Notable roofs\n\n- **Kuwait Towers** (opened 1979): conical spires over spherical tanks.\n- **National Assembly** (designed 1972, completed 1982): by Jørn Utzon.\n\n## Local roofing terms\n\nSee chandal-roof for Gulf terms.\n\n## Sources and gaps\n\nDetailed climate data for roofing, data on roofing material shares and information on modern roofing materials, codes and industry in Kuwait: published information is limited.","key_facts":[{"label":"Traditional roof beams","value":"Mangrove poles from East Africa"},{"label":"Traditional walls","value":"Sea stone, rubble with mud plaster, mud brick"},{"label":"Founded","value":"Early 18th century"},{"label":"Modern landmark","value":"Kuwait Towers (opened 1979)"}],"related":["chandal-roof","najdi-mud-roofs","badgir","flat-roof","roofing-in-saudi-arabia","roofing-in-iraq","roofing-in-bahrain","roofing-in-qatar","roofing-in-the-middle-east-and-gulf"],"sources":[{"title":"Architecture of Kuwait","url":"https://en.wikipedia.org/wiki/Architecture_of_Kuwait","publisher":"Wikipedia"},{"title":"Najdi architecture","url":"https://en.wikipedia.org/wiki/Najdi_architecture","publisher":"Wikipedia"},{"title":"Kuwait National Assembly Building","url":"https://en.wikipedia.org/wiki/Kuwait_National_Assembly_Building","publisher":"Wikipedia"},{"title":"Kuwait Towers","url":"https://en.wikipedia.org/wiki/Kuwait_Towers","publisher":"Wikipedia"}]},{"slug":"roofing-in-kyrgyzstan","title":"Roofing in Kyrgyzstan","category":"world-roofing","type":"place","country":{"name":"Kyrgyzstan","iso2":"KG"},"summary":"Kyrgyzstan's emblematic roof is the felt yurt with its tunduk crown, shown on the national flag; most houses are earth or brick with timber roofs.","body":"Kyrgyzstan is a mountain country dominated by the Tien Shan range. Its best-known roof is that of the felt **yurt**, whose wooden crown ring, the **tunduk**, is so central to Kyrgyz identity that it forms the centre of the national flag. Permanent houses in villages and towns are mostly built of clay or brick with timber roofs, and the country's high earthquake risk shapes how they should be built.\n\n## Climate and hazards\n\nWinters are long and cold, with heavy snow in the mountains, and summers in the valleys are hot and dry. The whole country is seismically active. Roofs must carry snow and, in an earthquake, act together with the walls; traditional earth houses perform poorly where this connection is weak.\n\n## Roofing history\n\nNomadic herders of the Kyrgyz and their predecessors lived in felt yurts for centuries; the earliest written description of yurt-like dwellings, by Herodotus, concerns the Scythians of the Central Asian and Black Sea steppe. The Kyrgyz yurt has a lattice wall, bent roof poles and the tunduk crown at the top, covered with felt from the herders' own sheep. Men make the wooden frame and its leather, bone and metal fittings; women make the felt coverings and the decorated interior textiles. In 2014 UNESCO recognised the knowledge and skills of making Kyrgyz and Kazakh yurts as Intangible Cultural Heritage of Humanity.\n\nIn the Soviet period, building followed all-Union codes, including seismic design codes from the 1960s (SNiP II-A.12-62 and SNiP II-A.12-69).\n\n## Traditional and vernacular roofs\n\n- **Yurt**: felt-covered timber frame with tunduk crown.\n- **Clay-walled house**: according to the World Housing Encyclopedia, houses with clay walls on stone foundations and timber roofs are found in all regions of the country, in rural and some urban areas. They are classed as highly vulnerable to earthquakes, partly because the roof beams are not joined into a rigid horizontal diaphragm and the walls are not anchored to the roof with metal straps.\n\n## Codes, standards and regulation\n\nKyrgyzstan has continuously updated its seismic codes since independence in 1991. The current code is **SN KR 20-02:2018**, *Earthquake engineering. Seismic design code*.\n\n## Notable roofs\n\n- **Tunduk on the national flag**: adopted on 3 March 1992 and redesigned with effect from 26 December 2023, showing the yurt crown seen from inside, within a sun of 40 rays.\n\n## Local roofing terms\n\n- *tunduk* / *tyndyk* (Kyrgyz): crown ring of the yurt\n\n## Sources and gaps\n\nInformation on modern roofing materials, statistics and industry in Kyrgyzstan: published information is limited.","key_facts":[{"label":"Traditional roof","value":"Felt yurt with tunduk crown ring"},{"label":"National symbol","value":"Tunduk on the flag (1992; redesigned 2023)"},{"label":"Common rural house","value":"Clay walls with timber roof"},{"label":"Climate driver","value":"Mountain cold, snow, earthquakes"},{"label":"Seismic code","value":"SN KR 20-02:2018"}],"regions":["Central Asia"],"aliases":["Kyrgyz roofing","roofs of Kyrgyzstan"],"related":["tunduk-and-shangyrak","ger-roof","wood-shingle","earthquake-roofing","snow-load","roofing-in-kazakhstan","roofing-in-tajikistan","roofing-in-uzbekistan","roofing-in-china"],"company":null,"sources":[{"title":"Flag of Kyrgyzstan","url":"https://en.wikipedia.org/wiki/Flag_of_Kyrgyzstan","publisher":"Wikipedia"},{"title":"Yurt","url":"https://en.wikipedia.org/wiki/Yurt","publisher":"Wikipedia"},{"title":"Traditional knowledge and skills in making Kyrgyz and Kazakh yurts (Turkic nomadic dwellings)","url":"https://ich.unesco.org/en/RL/traditional-knowledge-and-skills-in-making-kyrgyz-and-kazakh-yurts-turkic-nomadic-dwellings-00998","publisher":"UNESCO Intangible Cultural Heritage"},{"title":"Houses with mud walls and thatch roofs, Kyrgyzstan (Report 42)","url":"https://wheki-dev.globalquakemodel.org/reports/report_42","publisher":"World Housing Encyclopedia / Global Earthquake Model"},{"title":"Design regulations (Central Asia exposure model)","url":"https://docs.openquake.org/global_risk_model/central_asia/exposure/design_regulations.html","publisher":"Global Earthquake Model Foundation"}]},{"slug":"roofing-in-laos","title":"Roofing in Laos","category":"world-roofing","type":"place","country":{"name":"Laos","iso2":"LA"},"summary":"Roofing in Laos, known for the sweeping tiered temple roofs of Luang Prabang, with bamboo and timber stilt houses and colonial brick buildings.","body":"Laos is a landlocked, largely mountainous country along the Mekong. Its best-known roofs are the sweeping, multi-tiered roofs of Buddhist temples, above all in Luang Prabang, a UNESCO World Heritage town.\n\n## Climate and hazards\n\nLaos has a tropical monsoon climate with a pronounced wet season, heavy rain in the mountains and flooding along the Mekong and its tributaries. Steep roofs with deep overhangs and houses raised on posts are the traditional responses.\n\n## Roofing history\n\nLuang Prabang was the capital of the Lan Xang kingdom from the 14th to the 16th century. Its temples are richly decorated with carving, painting and gilding. Wat Xieng Thong, built in 1559-1560 under King Setthathirath, is one of the most complex: the roofs of its main hall (*sim*) cascade down in overlapping tiers, and small gilded ornaments run along the ridge.\n\nFrench rule began in 1893. In Luang Prabang this produced one- and two-storey brick houses with balconies and timber detailing along the main street and the Mekong, and a technique of plaited bamboo panels coated with wattle and daub. UNESCO's description of the town stresses the fusion of Lao timber architecture with 19th- and 20th-century European colonial building. In 1928, King Sisavangvong secured French help with the cost of restoring Wat Xieng Thong, and in 2012-2013 damaged roof tiles there were repaired as part of a wider restoration.\n\n## Traditional and vernacular roofs\n\n- **Temple roofs:** the *sim* of a Lao temple has stacked roofs; at Wat Xieng Thong they sweep down in an elaborate cascade. The *dok so fa*, a row of small gilded pagoda-like ornaments along the centre of the ridge, indicates the temple's relative importance by the number and elaboration of its elements.\n- **Houses:** traditional Lao houses are timber and bamboo, raised on posts, and sources describe the use of bamboo thatching for the roof.\n\n## Codes, standards and regulation\n\nHeritage controls are better documented than general building codes. Luang Prabang is protected under national heritage legislation, including Law No. 08/NA on national heritage (2005); a 12,500 ha (about 30,900 acre) buffer zone was approved in 2012.\n\n## Notable roofs\n\n- **Wat Xieng Thong, Luang Prabang** (1559-1560): the classic Luang Prabang-style tiered roof.\n- **Town of Luang Prabang** (UNESCO World Heritage): wats, timber houses and colonial brick buildings together.\n\n## Local roofing terms\n\n- *sim* - ordination hall of a Lao temple\n- *dok so fa* - ridge ornament of small gilded pagodas\n\n## Sources and gaps\n\nCensus data, building codes, industry information and other data on modern Lao roofing: published information is limited.","key_facts":[{"label":"Iconic roof","value":"Tiered sim roof of Wat Xieng Thong (1559-1560)"},{"label":"Ridge ornament","value":"Dok so fa"},{"label":"Traditional materials","value":"Timber, bamboo, bamboo thatch, clay tile"},{"label":"Heritage site","value":"Town of Luang Prabang (UNESCO)"}],"regions":["Southeast Asia"],"aliases":["Lao roofing","Laotian roofing"],"related":["roofing-in-southeast-asia","thai-temple-roof","pyatthat","bamboo-roofing","clay-roof-tile","roofing-in-thailand","roofing-in-cambodia","roofing-in-vietnam","roofing-in-myanmar"],"company":null,"sources":[{"title":"Town of Luang Prabang","url":"https://whc.unesco.org/en/list/479/","publisher":"UNESCO World Heritage Centre"},{"title":"Wat Xieng Thong","url":"https://en.wikipedia.org/wiki/Wat_Xieng_Thong","publisher":"Wikipedia"},{"title":"Architecture of Laos","url":"https://en.wikipedia.org/wiki/Architecture_of_Laos","publisher":"Wikipedia"}]},{"slug":"roofing-in-latvia","title":"Roofing in Latvia","category":"world-roofing","type":"place","country":{"name":"Latvia","iso2":"LV"},"summary":"Latvian roofing: steep gabled thatched roofs of rye straw and reed on farmsteads, a gable form echoed in Riga's Art Nouveau, and a small revival of thatch.","body":"The steep gabled roof is the defining form of Latvian vernacular architecture. Rural farmsteads were thatched, traditionally with rye straw, and the gabled silhouette later influenced the national Art Nouveau architecture of the late 19th and early 20th centuries. Thatching survives as a specialist craft, partly serving export demand from Scandinavia.\n\n## Climate and hazards\n\nLatvia has a cool, humid climate with snowy winters and frequent freeze-thaw, and a long Baltic coastline. Snow, wind and moisture are the main concerns for roofs; fire is a particular concern for thatch.\n\n## Roofing history\n\nThe German conquest of the 13th century pushed vernacular building out of Latvia's towns, leaving it as a rural tradition. Villagers built log houses with gabled roofs covered with thatch. From the 19th century, rural houses sometimes added urban details such as neoclassical or historicist features. In Latgale in the east, Old Believers who arrived in the 18th century built wooden houses in a Russian manner. During the National Awakening, architects drew on the gabled vernacular roof in Latvian Art Nouveau.\n\n## Traditional and vernacular roofs\n\n- **Thatched farmstead roof:** a steep gable roof of straw. According to a working Latvian thatcher, the ancestors used only naturally grown straw, and long, strong stalks of old rye varieties resist breaking.\n- **Reed:** today reed for thatching is also cut from the ice of frozen lakes in winter.\n\n## Roofing today\n\nThatch is a niche product. One Latvian producer interviewed in 2023 grew rye straw in the Gulbene region, cut reed in winter, and reported strong demand, mainly from Denmark and Sweden; he put the life of a thatched roof at about 20-35 years and used fibreglass fabric beneath the thatch as a fire barrier. Contemporary architects have also used thatch on new holiday homes.\n\n## Codes, standards and regulation\n\nAs an EU member, Latvia applies European product standards and the Eurocodes, including Eurocode 1, Part 1-3 for snow loads.\n\n## Industry\n\nApart from small thatching businesses, information on domestic roofing manufacturers: published information is limited.\n\n## Notable roofs\n\n- **Latvian Art Nouveau buildings**, whose architects drew on the vernacular gable roof during the National Awakening.\n\n## Local roofing terms\n\n- *jumts* - roof\n\n## Sources and gaps\n\nRoofing statistics, building-code details and information on manufacturers: published information is limited.","key_facts":[{"label":"Traditional roof","value":"Steep gabled thatch (rye straw, reed)"},{"label":"Thatch lifespan (thatcher's estimate)","value":"About 20-35 years"},{"label":"Influence","value":"Vernacular gable echoed in Latvian Art Nouveau"}],"regions":["Europe"],"aliases":["Latvian roofing","roofs in Latvia"],"related":["thatch","long-straw-thatch","water-reed-thatch","roofing-in-estonia","roofing-in-lithuania","roofing-in-sweden","roofing-in-denmark","ruukki"],"company":null,"sources":[{"title":"Vernacular architecture","url":"https://www.onlatvia.com/vernacular-architecture-1538","publisher":"OnLatvia"},{"title":"Master thatcher keeping ancient craft alive in the 21st century","url":"https://eng.lsm.lv/article/society/environment/20.08.2023-master-thatcher-keeping-ancient-craft-alive-in-the-21st-century.a520783/","publisher":"LSM (Latvian Public Broadcasting)"},{"title":"BPROM by OAD: thatch holiday home in Latvia","url":"https://www.dezeen.com/2026/04/01/thatch-holiday-home-latvia-oad-bprom/","publisher":"Dezeen"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"}]},{"slug":"roofing-in-lebanon","title":"Roofing in Lebanon","category":"world-roofing","type":"place","country":{"name":"Lebanon","iso2":"LB"},"regions":["Middle East"],"company":null,"summary":"Lebanese roofing: the pyramidal red Marseille-tile roof of the 19th-century central hall house, and the flat concrete roofs that replaced it.","aliases":["Lebanese roofing","Roofs of Lebanon","Lebanese red tile roof"],"body":"Lebanon's best-known roof is the pyramidal red-tile roof of the central hall house, the archetypal 19th-century home of the country's middle class, with its triple-arched facade. Since the 20th century, most of these tiled roofs have been replaced by, or surrounded by, flat concrete roofs.\n\n## Climate and hazards\n\nLebanon has a Mediterranean coast with wet winters and dry summers, rising steeply to mountains that receive winter snow.\n\n## Roofing history\n\n**Pre-tile houses.** Older village houses had flat earthen roofs of timber, reed mats and clay, or stone vaults and domes in the mountains; the sloped red-tile roof came later.\n\n**Ottoman era.** The central hall house appeared in the second half of the 19th century, associated with Ottoman-era modernisation and a growing middle class. Its rooms are arranged around a large central hall, lit by the triple arch.\n\n**Imported tiles.** These houses were roofed with red Marseille (interlocking) tiles on timber frames. The pyramidal roof is built as one block with the house and has no windows or chimney stacks; it is sometimes jokingly called the *tarboush* (fez) of the house.\n\n**Ceilings.** Ceilings rest on wooden or metal beams. In wealthier homes the ceiling is plaster on a wooden lattice, known as *baghdadi*, fixed to the beams and decorated with baroque motifs.\n\n**Modern.** Many tile roofs and their wooden frames were later replaced with flat concrete roofs.\n\n## Traditional and vernacular roofs\n\n- **Central hall house:** stone-built, often coated in ochre tones, with a pyramidal red Marseille-tile roof.\n- **Flat earthen roofs:** before the sloped red-tile roof, older Lebanese houses had flat roofs of timber, reed mats and clay (see flat-roof and mud-roof).\n- **Stone vaults and domes:** in mountain areas, stone barrel vaults or domes were used instead, to stand up to snow and rain.\n\n## Roofing today\n\nFlat reinforced concrete roofs are now the norm.\n\n## Notable roofs\n\n- Red-tiled central hall houses in Beirut and mountain towns.\n\n## Local roofing terms\n\n- *tarboush* - \"fez\", a nickname for the pyramidal tile roof\n- *baghdadi* - plaster-on-lath ceiling\n\n## Sources and gaps\n\nDetailed climate and hazard data for roofing, the dates when Marseille tiles began to be imported, the build-up and maintenance of earlier earth roofs, census data on main roofing material and information on modern practice, codes and industry were not found in published sources.","key_facts":[{"label":"Iconic roof","value":"Pyramidal red Marseille-tile roof"},{"label":"House type","value":"Central hall (triple-arch) house, 19th century"},{"label":"Ceiling","value":"Baghdadi plaster on timber lath"},{"label":"Pre-tile roofs","value":"Flat timber, reed-mat and clay roofs; stone vaults in mountains"},{"label":"Modern","value":"Flat concrete"}],"related":["interlocking-clay-tile","clay-roof-tile","hip-roof","pyramid-roof","flat-roof","roofing-in-syria","roofing-in-israel","roofing-in-cyprus","roofing-in-france"],"sources":[{"title":"The Triple Arches: Lebanon’s Architectural Legacy","url":"https://www.hotelibanais.com/travel/traditional-lebanese-house/","publisher":"Hotel Libanais"},{"title":"Traditional Mediterranean Architecture: The Lebanese house (typology sheet, EU MEDA programme)","url":"https://safita.neocities.org/files/documents/architecture2.pdf","publisher":"EU MEDA programme (hosted copy)"},{"title":"Old Lebanese house","url":"https://lebanonuntravelled.com/old-lebanese-house/","publisher":"Lebanon Untravelled"}]},{"slug":"roofing-in-lesotho","title":"Roofing in Lesotho","category":"world-roofing","type":"place","country":{"name":"Lesotho","iso2":"LS"},"summary":"Most Lesotho homes have corrugated metal roofs, while thatched round houses (mokhoro) still make up over a quarter of households in survey data.","body":"Lesotho is a mountain kingdom where cold winters and summer thunderstorms shape the house. The traditional Basotho house is the round *mokhoro*, with stone or mud walls and a conical grass-thatched roof; the rectangular house with a corrugated metal roof has largely overtaken it.\n\n## Climate and hazards\n\nHighland winters are cold and summers bring thunderstorms. A thick thatch over heavy walls moderates indoor temperature, and the steep cone sheds summer rain (see Rondavel).\n\n## Roofing history\n\nMany round houses in the region now have corrugated iron or other sheet-metal roofs in place of thatch, which are quicker to fix but hotter and noisier in rain.\n\n## Traditional and vernacular roofs\n\n- **Mokhoro** (Basotho round house): a cylindrical wall of stone or mud, bonded with mortar of sand, soil and cow dung, under a conical roof of radial poles and ring purlins thatched with grass sewn on in bands from the eaves up. Floors are finished with a dung mixture. This is the Lesotho form of the rondavel.\n- **Rectangular houses**: stone or block walls with corrugated metal or thatched pitched roofs.\n\n## Roofing today\n\nIn the unweighted 2018 Multiple Indicator Cluster Survey sample (8,847 households with a recorded roof):\n\n| Main roof material (HC5) | Share of sampled households |\n|---|---|\n| Metal / corrugated (zinc sheets) | 68.5% |\n| Thatch / palm leaf | 27.5% |\n| Ceramic / clay tiles | 3.0% |\n| Other (asbestos, cement, wood, shingles, no roof) | 1.0% |\n\n## Local roofing terms\n\n- *mokhoro* (Sesotho): round, conical-roofed house; the Lesotho rondavel.\n\n## Sources and gaps\n\nDetailed archaeological or documentary evidence specific to Lesotho's roofs: published information is limited. No national roofing standard was identified. No information on domestic roofing manufacturers was found in published sources. No roof-specific heritage listings were identified.\n\nSurvey shares are unweighted counts in the MICS sample. Sesotho thatching vocabulary, data from the 2016 census and documentation of Basotho thatching grasses: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal sheet, 68.5% (MICS 2018 file, unweighted)"},{"label":"Thatch share","value":"27.5% of households (MICS 2018 file, unweighted)"},{"label":"Traditional form","value":"Mokhoro (round house with conical thatch)"},{"label":"Climate driver","value":"Cold highland winters, summer thunderstorms"}],"regions":["Africa"],"aliases":["Basotho roofing","Lesotho roofing"],"related":["rondavel","thatch","conical-roof","corrugated-iron","roofing-in-southern-africa","roofing-in-south-africa"],"company":null,"sources":[{"title":"Lesotho MICS 2018: Main material of roof (HC5)","url":"https://microdata.worldbank.org/catalog/4162/variable/F4/V1210?name=HC5","publisher":"World Bank Microdata Library"},{"title":"Rondavel","url":"https://en.wikipedia.org/wiki/Rondavel","publisher":"Wikipedia"}]},{"slug":"roofing-in-liberia","title":"Roofing in Liberia","type":"place","country":{"name":"Liberia","iso2":"LR"},"summary":"Liberia's homes are mainly roofed with zinc (corrugated metal sheet), which has steadily replaced the thatch of rural villages.","body":"Liberia, on the rain-soaked Atlantic coast between Sierra Leone and Côte d'Ivoire, has a roofing story typical of the West African forest belt: thatched houses in villages, gradually replaced by corrugated metal sheet, known locally as \"zinc\".\n\n## Climate and hazards\n\nThe climate is hot and humid, with a long, very wet rainy season. Thatch and timber are exposed to rot and insects, and roofs must shed heavy rain quickly.\n\n## Roofing history\n\nAmong the Kpelle, Liberia's largest ethnic group, the traditional house was a one-room round hut of wattle-and-daub with a conical thatched roof. Square houses with three rooms and an open porch are now the more common form, alongside rectangular two-room houses with very wide porches. Anthropological accounts note that zinc roofs gradually replaced thatch, especially where people had access to cash employment, and that the round thatched hut survives mainly in remote villages. Civil war from 1989 to 2003 displaced many rural communities and disrupted building traditions.\n\n## Traditional and vernacular roofs\n\n- **Round hut**: wattle-and-daub walls under a conical thatched roof.\n- **Square and rectangular houses**: thatched or zinc-roofed, with open porches.\n\n## Roofing today\n\nThe 2020 Afrobarometer survey of Liberia recorded:\n\n| Main roof material | Share of respondents (2020) |\n|---|---|\n| Metal, aluminium, tin or zinc | 82.9% |\n| Thatch or grass | 11.4% |\n| Tiles | 2.0% |\n| Concrete | 1.8% |\n| Asbestos | 0.9% |\n| Plastic sheets | 0.6% |\n\nAfrobarometer surveys interview about 1,200 adults per country; these figures are unweighted counts in the survey sample. The 2007 Core Welfare Indicators Questionnaire used the categories thatch/grass/straw, corrugated iron/zinc/tin, tarpaulin or plastic sheets, cement or concrete, roofing tiles and asbestos.\n\n## Local roofing terms\n\n- **zinc** (Liberian English): corrugated metal roof sheet.\n\n## Sources and gaps\n\nPublished research on Liberian roofing is limited.\n\nSurvey shares are unweighted. Published sources on Americo-Liberian settler houses in Monrovia and other coastal towns, on regulation and on industry: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Zinc (metal sheet), 82.9% (Afrobarometer 2020 file)"},{"label":"Thatch","value":"11.4% of respondents (2020)"},{"label":"Traditional roof","value":"Conical thatch on round wattle-and-daub huts"},{"label":"Climate driver","value":"Very heavy rainfall, humidity"}],"regions":["Africa"],"aliases":["Liberian roofing","roofing in Liberia"],"related":["roofing-in-west-africa","corrugated-iron","thatch","conical-roof","roofing-in-sierra-leone","roofing-in-guinea","roofing-in-cote-divoire","krio-board-house"],"sources":[{"title":"Afrobarometer Survey 2020, Round 8, Liberia: roof of respondent's home","url":"https://microdata.worldbank.org/catalog/5811/variable/V356","publisher":"World Bank Microdata Library / Afrobarometer"},{"title":"Kpelle - Settlements","url":"https://www.everyculture.com/Africa-Middle-East/Kpelle-Settlements.html","publisher":"Countries and Their Cultures"},{"title":"Core Welfare Indicators Questionnaire 2007, Liberia: material of the roof","url":"https://catalog.ihsn.org/catalog/1523/variable/F5/V196?name=g2","publisher":"IHSN"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-libya","title":"Roofing in Libya","category":"world-roofing","type":"place","country":{"name":"Libya","iso2":"LY"},"summary":"Libya's best-documented traditional roofs are in Ghadames, where mud-brick houses with palm-trunk structure carry rooftop terraces reserved for women.","body":"Libya is mostly Saharan desert with a narrow Mediterranean coastal strip. Its most thoroughly documented roofing tradition is that of the oasis town of Ghadames near the borders with Tunisia and Algeria, a UNESCO World Heritage site whose houses combine mud brick, palm timber and a remarkable system of rooftop terraces.\n\n## Climate and hazards\n\nAway from the coast, Libya is extremely hot and dry, and heat is the main load a roof must handle. Rain is infrequent but not harmless: UNESCO reports that heavy rains, together with fire, have recently damaged the old town of Ghadames, whose earth buildings depend on regular maintenance. Changes in water supply, humidity and temperature are listed as pressures on the site.\n\n## Roofing history\n\nGhadames was occupied by the indigenous Phazanii people from at least the late first millennium BC and has been a stop on trans-Saharan trade routes for at least 2,000 years. Its old town was built of mud brick on stone foundations, with palm trunks, woodwork and masonry, and limed walls. Building materials were routinely recycled.\n\nIn the 1970s the government built new housing outside the old town, and the old town was depopulated through the 1990s, leaving buildings at risk of collapse from lack of upkeep. Many families still return in summer because the old houses are cooler. The old town was inscribed as a World Heritage site in 1986 and has been on the List of World Heritage in Danger since 2016, together with Libya's four other World Heritage sites, because of conflict-related risk.\n\n## Traditional and vernacular roofs\n\n- **Ghadames houses**: usually two storeys, with stores on the ground floor, family rooms above, and open-air roof terraces reserved for women and used by children. Compact roofs have high parapets for privacy (see Old Town of Ghadames).\n- **Covered streets**: alleys roofed over by the houses form an almost underground network, lit by regular openings in the roof, called *tinawt* or *klava*.\n- **Flat earth roofs**: as across North Africa, flat roofs on timber or palm joists with layers of earth are the general traditional form in the oases (see Roofing in North Africa).\n\n## Roofing today\n\nReinforced concrete flat roofs are the norm in modern North African construction (see Roofing in North Africa).\n\n## Codes, standards and regulation\n\nGhadames is protected under Libyan Law No. 3/1994, and its management relies on a ten-year plan that addresses climate change and the safeguarding of traditional construction techniques.\n\n## Notable roofs\n\n- **Old Town of Ghadames**: mud-brick houses with women's roof terraces and roofed streets. Proactive maintenance of the water system began in 2008.\n\n## Local roofing terms\n\n- **tinawt / klava**: openings in the roofs of Ghadames's covered streets that admit light and air.\n\n## Sources and gaps\n\nRoofing elsewhere in the country, and on present-day materials: published information is limited. No household survey or census table of roof materials for Libya was found in published sources. Libya-specific shares of roof materials: published information is limited. No national building or roofing code was found in published sources. No information on domestic roofing manufacturers was found.\n\n Coastal vernacular roofs (for example in Tripoli's old city), the mountain villages of the Nafusa, colonial-era Italian building and modern roof materials were not found in published sources.","key_facts":[{"label":"Traditional materials","value":"Mud brick, palm trunks, lime"},{"label":"Landmark","value":"Old Town of Ghadames (World Heritage, 1986)"},{"label":"Distinctive feature","value":"Roof terraces reserved for women"},{"label":"Climate driver","value":"Extreme heat; occasional heavy rain"}],"regions":["Africa","Middle East"],"aliases":["Libyan roofing","roofing in Libya"],"related":["roofing-in-north-africa","old-town-of-ghadames","flat-roof","mud-roof","roofing-in-tunisia","roofing-in-algeria","roofing-in-egypt","kershef"],"company":null,"sources":[{"title":"Old Town of Ghadamès","url":"https://whc.unesco.org/en/list/362/","publisher":"UNESCO World Heritage Centre"},{"title":"Ghadames","url":"https://en.wikipedia.org/wiki/Ghadames","publisher":"Wikipedia"}]},{"slug":"roofing-in-liechtenstein","title":"Roofing in Liechtenstein","category":"world-roofing","type":"place","country":{"name":"Liechtenstein","iso2":"LI"},"summary":"Liechtenstein roofing: pitched roofs on old timber farmhouses of the Rhine valley and modern Alpine houses, regulated by the 2008 Building Act.","body":"Liechtenstein is a small Alpine principality between Switzerland and Austria, lying mostly in the Rhine valley with mountains to the east. Little has been published specifically about its roofing, but its listed buildings and its building law give a picture of a pitched-roof tradition closely related to that of eastern Switzerland and Vorarlberg.\n\n## Climate and hazards\n\nThe country spans the relatively mild Rhine valley floor and Alpine terrain with heavy winter snow at resorts such as Malbun. Liechtenstein's Building Act refers to the Swiss SIA standard when defining structures at risk.\n\n## Roofing history\n\nSome of the oldest buildings are timber farmhouses. A house in Vaduz's Mitteldorf has a core dendrochronologically dated to 1410, extended in the 16th century; today its two adjoining dwellings each have a separate pitched roof and correspond in appearance to the 19th-century village house type. It has been protected since 1989. The farmhouse museum at Schellenberg occupies a squared-timber house built in 1518, insulated with moss and lichen and assembled with wooden pegs and nails rather than iron; it has been moved three times (1687, 1793-1794 and 1992-1993), was listed in 1993 and opened as a museum in 1994.\n\n## Traditional and vernacular roofs\n\nTraditional village houses have pitched roofs over timber or masonry walls.\n\n## Roofing today\n\nModern houses in Liechtenstein include contemporary interpretations of Alpine buildings with pitched and flat roofs.\n\n## Codes, standards and regulation\n\nBuilding is governed by the **Building Act** (*Baugesetz*) of 11 December 2008, published in the national law gazette in 2009 (LGBl. 2009 No. 44). Its roof-related provisions include:\n\n- building height is measured to the top of the roof covering, or to the parapet or railing on flat roofs;\n- on mono-pitch roofs of at least 10% slope, and on steep roofs over 45 degrees, the ridge height counts as building height;\n- roof and attic storeys must be set back at 45 degrees at facade corners in certain cases;\n- for energy retrofits, a raised roof structure is excluded from the height calculation, and external insulation, including on the roof construction, may project up to 0.25 m (10 in) into setbacks;\n- changes to the building envelope, including roof windows, and the installation of solar and photovoltaic systems must be notified, while energy-generation systems above 3 kW need a permit;\n- projects affecting registered cultural property must be coordinated with the cultural heritage authority.\n\n## Notable roofs\n\n- **Farmhouse museum, Schellenberg**, a timber house of 1518.\n- **House 89/90/162, Mitteldorf, Vaduz**, with a core dated to 1410.\n\n## Sources and gaps\n\nRoof-load guidance, details of historic roof coverings (such as the balance between wooden shingles and clay tiles), information on the roofing trade and on domestic roofing manufacturers, and building statistics for Liechtenstein were not found in published sources.","key_facts":[{"label":"Building code","value":"Baugesetz of 11 December 2008 (LGBl. 2009 No. 44)"},{"label":"Height rule","value":"Measured to top of roof covering"},{"label":"Solar on buildings","value":"Notification required; systems over 3 kW need a permit"},{"label":"Oldest dated house core","value":"1410 (Vaduz)"}],"regions":["Europe"],"aliases":["Liechtenstein roofing"],"related":["roofing-in-switzerland","roofing-in-austria","schindel"],"company":null,"sources":[{"title":"Baugesetz (BauG)","url":"https://www.gesetze.li/konso/pdf/2009044000","publisher":"Liechtensteinische Landesverwaltung"},{"title":"House 89/90/162, Mitteldorf 1410","url":"https://www.vaduz.li/en/living-environment/living-building/listed-buildings/haus-8990162-mitteldorf-1410","publisher":"Gemeinde Vaduz"},{"title":"Liechtenstein Farmhouse Museum","url":"https://en.tourismus.li/map/poi/bauerliches-wohnmuseum-fd3e1b2b-aeab-48ba-9cf5-349141f0ff42.html","publisher":"Liechtenstein Marketing"}]},{"slug":"roofing-in-lithuania","title":"Roofing in Lithuania","category":"world-roofing","type":"place","country":{"name":"Lithuania","iso2":"LT"},"summary":"Lithuanian roofing: thatched farmsteads of five ethnographic regions, wooden fishermen's houses of the Curonian Spit, and modern steel and membrane roofs.","body":"Lithuania's rural roofing tradition is preserved in its ethnographic regions, Aukštaitija, Žemaitija (Samogitia), Dzūkija, Suvalkija and Lithuania Minor, each represented by farmsteads at the national open-air museum. On the Curonian Spit, a narrow dune peninsula shared with Russia's Kaliningrad region, wooden fishermen's houses form part of a UNESCO World Heritage landscape.\n\n## Climate and hazards\n\nLithuania has a cool, humid climate with snowy winters, freeze-thaw cycles and strong winds on the Baltic coast. On the Curonian Spit, drifting sand once buried whole villages after 16th- to 18th-century logging destabilised the dunes; stabilisation began around the turn of the 19th century.\n\n## Roofing history\n\nThe Curonian Spit, about 98 km (61 mi) long and 0.4-4 km wide, has been inhabited since prehistoric times, with trade villages of the 10th and 11th centuries and later fishermen's villages that became resorts. Its oldest wooden fishermen's houses are among the most vulnerable parts of the World Heritage site. The Nida Fisherman's Ethnographic Homestead, a wooden house built by local craftsmen in 1927 and restored in 1973 after ice damage, shows life on the spit in the late 19th and early 20th centuries. The writer Thomas Mann spent the summers of 1930-1932 in a thatched cottage he had built above the lagoon at Nida.\n\nInland, Lithuanian farmsteads from the 18th to the first half of the 20th century are preserved at the Open-Air Museum of Lithuania in Rumšiškės, which covers 195 ha (482 acres) and is described as the largest of its kind in Europe.\n\n## Traditional and vernacular roofs\n\n- **Curonian fishermen's houses:** wooden houses of the lagoon-shore villages.\n- **Thatched cottages:** such as the house built for Thomas Mann at Nida.\n\n## Codes, standards and regulation\n\nAs an EU member, Lithuania applies European product standards and the Eurocodes, including Eurocode 1, Part 1-3 for snow loads.\n\n## Notable roofs\n\n- **Curonian Spit** (UNESCO, 2000), with the fishermen's villages of Nida, Juodkrantė, Preila and Pervalka.\n- **Thomas Mann's summer house**, Nida, a thatched cottage of 1930.\n- **Open-Air Museum of Lithuania**, Rumšiškės.\n\n## Sources and gaps\n\nDetailed accounts of Lithuanian thatching techniques and of the roof coverings of the Curonian houses, statistics, codes and information on domestic roofing manufacturers were not found in published sources.","key_facts":[{"label":"Thatched example","value":"Thomas Mann house, Nida (1930)"},{"label":"UNESCO landscape","value":"Curonian Spit (2000)"},{"label":"Open-air museum","value":"Rumšiškės, 195 ha"}],"regions":["Europe"],"aliases":["Lithuanian roofing","roofs in Lithuania"],"related":["thatch","water-reed-thatch","roofing-in-latvia","roofing-in-poland","roofing-in-belarus","roofing-in-russia","ruukki"],"company":null,"sources":[{"title":"Curonian Spit","url":"https://whc.unesco.org/en/list/994","publisher":"UNESCO World Heritage Centre"},{"title":"Curonian Spit","url":"https://en.wikipedia.org/wiki/Curonian_Spit","publisher":"Wikipedia"},{"title":"Nida Fisherman's Ethnographic Homestead","url":"https://www.visitneringa.com/en/explore-neringa/museums/nida-fisherman-s-ethnographic-homestead-16289.html","publisher":"Visit Neringa"},{"title":"Rumšiškės Open-Air Museum of Lithuania","url":"https://lithuania.travel/en/why-lithuania/culture-and-heritage/culture-and-art/museums/open-air-museums/rumsiskes-open-air-museum-of-lithuania","publisher":"Lithuania Travel"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"}]},{"slug":"roofing-in-luxembourg","title":"Roofing in Luxembourg","category":"world-roofing","type":"place","country":{"name":"Luxembourg","iso2":"LU"},"summary":"Luxembourg roofing: slate from the Ardennes uplands, mined at Haut-Martelange until 1986, on houses, castles and churches across the Grand Duchy.","body":"Luxembourg is a small, landlocked country divided between the wooded Ardennes uplands (the Oesling) in the north and the lower Gutland to the south. Its traditional roofs are closely tied to the Ardennes slate belt, which runs across the border from Belgium, and for about two centuries the slate mines of Haut-Martelange were among the most important in Europe.\n\n## Climate and hazards\n\nLuxembourg has a temperate climate with rain spread through the year and colder, snowier winters on the Ardennes plateau.\n\n## Roofing history\n\nRoman villas at Echternach (from about AD 70), Mamer and Goeblange show that substantial masonry building began in the Roman period. Medieval castles such as Vianden, Bourscheid, Beaufort and Clervaux, and Romanesque and Gothic churches at Echternach, Diekirch and elsewhere, are the oldest surviving roofed buildings, though most have been re-roofed many times.\n\nUnderground slate mining began at Haut-Martelange, on the Belgian border, by the 18th century; one account dates the first mines to the end of the 17th century, while the site's museum dates them to the end of the 18th century. A railway link in 1890 allowed large-scale export, and the same year the Rother family of Frankfurt bought the mines and the village. By the end of the 19th century the works produced about 6 million roofing slates a year and around 1900 employed about 600 people. Pneumatic tools arrived from 1900 and a company power station was built around 1904. In the 19th century the mines were among Europe's main slate exporters and a significant part of Luxembourg's exports.\n\nSales stagnated from 1930 in the economic crisis, and after 1960 the industry declined because of new roofing materials and cheap imported slate. The last Luxembourg slate mine closed in 1986.\n\n## Traditional and vernacular roofs\n\nNatural slate is the characteristic roof of the Oesling and of historic buildings across the country.\n\n## Roofing today\n\nSlate now comes from abroad, as no domestic mines operate.\n\n## Codes, standards and regulation\n\nEuropean EN standards apply to roofing products.\n\n## Industry\n\nThe former Haut-Martelange slate works is now a museum. A friends' association formed in 1992 to reopen the mines to the public, the municipality of Rambrouch bought the village, industrial buildings and mines in 1993, and in 2018 the government invested EUR 7.1 million in a museum open daily, with underground visits to a depth of 42 m (138 ft). Since 2019 the Musée de l'Ardoise is run by an association of the state, the municipality and the friends' group.\n\n## Notable roofs\n\n- **City of Luxembourg** old quarters and fortifications, designated a UNESCO World Heritage Site in 1994.\n- **Vianden Castle**, an 11th-13th century castle built on a Gallo-Roman fort.\n- **Haut-Martelange**, the former slate village and mines.\n\n## Sources and gaps\n\nCensus data on roofing, roof-load guidance, details of local slating patterns and of tile traditions in the Gutland, roofing-specific building rules and local roofing terms were not found in published sources.","key_facts":[{"label":"Traditional material","value":"Ardennes slate"},{"label":"Slate output, late 19th century","value":"About 6 million slates a year (Haut-Martelange)"},{"label":"Workforce about 1900","value":"About 600"},{"label":"Last slate mine closed","value":"1986"},{"label":"UNESCO site","value":"City of Luxembourg (1994)"}],"regions":["Europe"],"aliases":["Luxembourgish roofing","Roofing in the Grand Duchy of Luxembourg"],"related":["ardennes-slate","natural-slate","roofing-in-belgium","roofing-in-france","roofing-in-germany"],"company":null,"sources":[{"title":"History","url":"https://www.ardoise.lu/historie?lang=en","publisher":"Musée de l'Ardoise, Haut-Martelange"},{"title":"Haut-Martelange","url":"https://en.wikipedia.org/wiki/Haut-Martelange","publisher":"Wikipedia"},{"title":"Architecture of Luxembourg","url":"https://en.wikipedia.org/wiki/Architecture_of_Luxembourg","publisher":"Wikipedia"},{"title":"L'extraction des ardoises en suivant le fil historique","url":"https://gsb.naturalsciences.be/wp-content/uploads/2026/03/2-1-Lextraction-des-ardoises-en-suivant-le-fil-historique.pdf","publisher":"Geological Survey of Belgium"}]},{"slug":"roofing-in-madagascar","title":"Roofing in Madagascar","category":"world-roofing","type":"place","country":{"name":"Madagascar","iso2":"MG"},"summary":"Madagascar roofs are mostly grass or palm thatch and metal sheet; the highlands add steep tiled brick houses and royal timber houses with roof horns.","body":"Madagascar's roofs reflect its varied climate and a strong set of customs about which materials belong to the living and which to the dead. Rectangular houses with steep, peaked gable roofs are the norm across the island, thatched with grass, reeds or palm leaves, while in the central highlands brick houses with clay tile roofs and verandas became common from the 19th century. Today metal sheet and plant thatch account for almost all roofs.\n\n## Climate and hazards\n\nTropical cyclones are the main roof hazard. In February 2012 Cyclone Giovanna tore off the wooden shingles of the royal house at Ambohimanga, exposing its interior to the weather. Coastal thatch traditionally has slightly overhanging eaves that throw rain clear of the foundations.\n\n## Roofing history\n\n**Royal highland building.** In the Merina tradition of the central highlands, houses of the living were built of wood and plant materials and tombs of stone. King Andrianampoinimerina (reigned 1787-1810) banned building in stone, brick or earth within Antananarivo. Aristocratic timber houses carried crossed gable timbers called *tandrotrano* (roof horns), whose length signalled rank.\n\n**Missionaries and new materials.** Louis Gros designed the Tranovola palace in the Rova of Antananarivo for Radama I in 1819. James Cameron demonstrated sun-dried bricks in 1826, and in 1831 Jean Laborde introduced fired brick roof tiles, which began to replace the rice-straw thatch then common in the capital. Laborde built the Queen's Palace in the Rova in 1839-1841. Restrictions on aristocratic use of stone and brick were relaxed in 1867 and abolished in 1869. Brick house-building based on London Missionary Society models spread under Ranavalona II (1868-1883), producing highland houses with shortened roof horns, carved verandas and, later, clay-tile roofs. French colonisation began in 1896. Fire destroyed buildings of the Rova in 1995.\n\n## Traditional and vernacular roofs\n\n- **East coast houses**: low houses on stilts thatched with traveller's palm (*ravinala*), whose trunks are also pounded flat into boards for floors and roofs. See Ravinala thatch.\n- **North**: raffia palm used in place of ravinala.\n- **West and south-west**: palms around Mahajanga, rushes around Toliara, reeds near rivers.\n- **Highland (Merina, Betsileo)**: houses built flush to the ground with steep gable roofs, often on a central pillar (*andry*); later the earthen and brick *trano gasy* (\"Malagasy house\") with verandas and tiled roofs.\n- **Zafimaniry**: large rectangular timber houses with peaked roofs and overhanging eaves.\n- **South-east**: zebu horns were sometimes fixed to the gable peak.\n\n## Roofing today\n\nIn the unweighted 2018 Multiple Indicator Cluster Survey sample (17,870 households with a recorded roof):\n\n| Main roof material (HC5) | Share of sampled households |\n|---|---|\n| Metal sheet / aluminium (*tole*) | 33.6% |\n| Grass bundles (*mottes d'herbes*) | 32.6% |\n| Thatch / palm leaf (*chaume / feuille de palme*) | 26.3% |\n| Palm / bamboo / *zozoro* | 4.0% |\n| Ceramic tiles | 0.8% |\n| Wood planks | 0.7% |\n| Cement | 0.4% |\n| Other or no roof | 1.6% |\n\nPlant-based roofs together exceed metal sheet in the sample, while tiles, once the mark of the highland brick house, now appear on fewer than 1% of recorded homes.\n\n## Codes, standards and regulation\n\nAmbohimanga has had legal protection since 1982-1983 and is managed by the Office of the Cultural Site of Ambohimanga (OSCAR).\n\n## Notable roofs\n\n- **Royal Hill of Ambohimanga** (UNESCO 2001): Andrianampoinimerina's rosewood house, whose peaked roof rests on a 10 m (33 ft) central rosewood pillar, once thatched and now shingled; sacred wooden tomb houses rebuilt in 2008. See Ambohimanga royal houses.\n- **Rova of Antananarivo**: royal palace complex given its final form in 1872, damaged by fire in 1995.\n\n## Local roofing terms\n\n- *tandrotrano*: roof horns formed by crossed gable timbers.\n- *andry*: central roof-bearing pillar.\n- *ravinala*: traveller's palm, used for thatch and boards.\n- *trano gasy*: \"Malagasy house\", the highland earthen or brick house.\n- *tole* (French): corrugated metal sheet.\n\n## Sources and gaps\n\nNo national building code or roofing standard was identified. No information on domestic roofing manufacturers was found in published sources.\n\nSurvey shares are unweighted sample counts. National census roof tables (RGPH 2018) and data on local tile production: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal sheet 33.6%; grass and palm thatch together over 60% (MICS 2018 file, unweighted)"},{"label":"Traditional materials","value":"Ravinala, raffia, grass, reeds, rice straw, rosewood"},{"label":"Climate driver","value":"Tropical cyclones"},{"label":"Landmark","value":"Royal Hill of Ambohimanga (UNESCO 2001)"},{"label":"Clay tiles introduced","value":"1831 (Jean Laborde)"}],"regions":["Africa"],"aliases":["Malagasy roofing"],"related":["ravinala-thatch","tandrotrano","ambohimanga-royal-houses","palm-thatch","thatch","clay-roof-tile","corrugated-iron","roofing-in-mauritius","roofing-in-comoros","roofing-in-mozambique","roofing-in-seychelles"],"company":null,"sources":[{"title":"Architecture of Madagascar","url":"https://en.wikipedia.org/wiki/Architecture_of_Madagascar","publisher":"Wikipedia"},{"title":"Ambohimanga","url":"https://en.wikipedia.org/wiki/Ambohimanga","publisher":"Wikipedia"},{"title":"Royal Hill of Ambohimanga","url":"https://whc.unesco.org/en/list/950/","publisher":"UNESCO World Heritage Centre"},{"title":"MICS 2018 Madagascar: Materiau principal du toit (HC5)","url":"https://microdata.worldbank.org/catalog/4163/variable/F4/V1123?name=HC5","publisher":"World Bank Microdata Library"}]},{"slug":"roofing-in-malawi","title":"Roofing in Malawi","category":"world-roofing","type":"place","country":{"name":"Malawi","iso2":"MW"},"summary":"Malawi is split between iron-sheet and grass-thatch roofs: in recent survey data metal sheet covers just over half of households and thatch most of the rest.","body":"Malawi is a narrow, mainly rural country along Lake Malawi. Its roofs show one of the clearest thatch-to-metal transitions in the region: in the 2019-20 Multiple Indicator Cluster Survey, iron sheets and grass thatch together account for over 98% of recorded roofs, with metal only slightly ahead.\n\n## Climate and hazards\n\nRain falls mainly in a single wet season.\n\n## Roofing history\n\nHousehold surveys since the 1990s record roof material for every household, and 2019-20 survey data show the country close to an even split between thatch and iron sheet.\n\n## Traditional and vernacular roofs\n\n- **Grass-thatched houses**: still the roof on over 40% of households in recent survey data, making Malawi one of the countries in the region where thatch remains closest to metal sheet in share. For comparison, thatch made up about 27.5% of households in Lesotho's 2018 MICS file and about 19.6% in Zimbabwe's 2019 MICS file (unweighted).\n\n## Roofing today\n\nIn the unweighted 2019-20 Multiple Indicator Cluster Survey sample (25,419 households with a recorded roof):\n\n| Main roof material (HC5) | Share of sampled households |\n|---|---|\n| Iron sheets / metal / tin | 54.6% |\n| Thatch / palm leaf | 43.9% |\n| Cement | 0.6% |\n| Wood planks, mats, tiles, shingles, other | 0.7% |\n| No roof | 0.2% |\n\n## Local roofing terms\n\nThe international survey category names used in Malawi are iron sheets, thatch or palm leaf, cement, wood planks and rustic mat.\n\n## Sources and gaps\n\nSpecific roof hazard data: published information is limited. Detailed archaeological evidence for early roofs was not found in published sources. No national roofing standard was identified. No information on domestic roofing manufacturers was found in published sources. No roof-specific heritage listings were identified. No Chichewa roofing terms were found in published sources.\n\nSurvey shares are unweighted counts in the MICS sample. Published 2018 census housing tables, Chewa and Ngoni building traditions and information on burnt-brick and iron-sheet supply: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Iron sheet, 54.6% (MICS 2019-20 file, unweighted)"},{"label":"Thatch share","value":"43.9% of households (MICS 2019-20 file, unweighted)"},{"label":"Traditional materials","value":"Grass thatch, poles, earth"}],"regions":["Africa"],"aliases":["Malawian roofing"],"related":["thatch","corrugated-iron","palm-thatch","roofing-in-east-africa","roofing-in-southern-africa","roofing-in-zambia","roofing-in-mozambique","roofing-in-tanzania"],"company":null,"sources":[{"title":"Malawi MICS 2019-20: Main material of roof (HC5)","url":"https://microdata.worldbank.org/catalog/4286/variable/F1/V149?name=HC5","publisher":"World Bank Microdata Library"},{"title":"Malawi DHS 1992 (IPUMS subset): Main material of roof (H_ROOF)","url":"https://microdata.worldbank.org/index.php/catalog/3161/variable/H/H_ROOF","publisher":"World Bank Microdata Library"}]},{"slug":"roofing-in-malaysia","title":"Roofing in Malaysia","category":"world-roofing","type":"place","country":{"name":"Malaysia","iso2":"MY"},"summary":"Roofing in Malaysia, from steep atap-thatched Malay houses with long, five-ridged and limas roofs to modern tile and metal under the Uniform Building By-Laws 1984.","body":"Malaysia spans the Malay Peninsula and the northern part of Borneo (Sabah and Sarawak). Its traditional Malay houses are timber buildings raised on posts under steep, well-ventilated roofs, originally thatched with palm-leaf *atap*.\n\n## Climate and hazards\n\nThe country is equatorial, hot and humid all year, with heavy rain and two monsoon seasons; the east coast of the peninsula receives intense northeast-monsoon rain and flooding. Roofs must shed heavy rain quickly, shade walls and let hot air escape.\n\n## Roofing history\n\nThe Malay word *atap* means \"roof\", and it also became the name for the palm-leaf thatch that covered traditional houses across what are now Malaysia, Brunei, Indonesia and Singapore. The thatch is associated with the nipa palm (*Nypa fruticans*), whose leaves were used for roofs and walls. Until the 19th century even significant public buildings such as temples were built in this way.\n\nMalay roofs belong to a wider regional family. Gabled roofs are the basic form; pyramidal and crossed-corner roofs (*limas*) mark higher-status buildings; and on the east coast of the peninsula, carved gable-end boards resemble those of Thailand and Cambodia.\n\n## Traditional and vernacular roofs\n\nThe Malay house (*rumah Melayu*) takes many regional forms, often named after the roof:\n\n- **Rumah Bumbung Panjang** (\"long-roof house\"): a long gabled roof, found in Kedah, Perlis, Perak, Selangor, Johor and Pahang.\n- **Rumah Perabung Lima** (\"five-ridged house\"): in Kelantan and Terengganu.\n- **Rumah Limas**: crossed-corner or pyramidal roofs, used for palaces and government buildings and also found in Terengganu and Melaka.\n- **Rumah Melaka**: the Melaka and Johor house type.\n- **Rumah Kutai**: an old Perak and northern Selangor type.\n- **Rumah Gajah Menyusu**: a Penang type.\n- **Rumah Lipat Kajang**: a roof with crossed edges forming an \"x\" pinnacle at each corner.\n\nRoof ornaments include crossed \"x\"-shaped pinnacles at the gable ends and carved gable boards. The gabled form provides shade, rain protection and ventilation in the hot, humid climate.\n\n## Codes, standards and regulation\n\nIn Peninsular Malaysia, building control rests on the Street, Drainage and Building Act 1974 (Act 133), which applies to West Malaysia and consolidates the law on streets, drainage and building in local authority areas. Detailed building rules are set out in the Uniform Building By-Laws 1984 (G.N. 5178/84), enforced by local authorities; consolidated editions are kept current (one is dated 10 January 2024). Because the Act applies only to West Malaysia, Sabah and Sarawak are outside its scope.\n\n## Notable roofs\n\nTraditional palaces and timber houses in Negeri Sembilan, Kelantan, Terengganu and Melaka preserve the regional roof forms.\n\n## Local roofing terms\n\n- *atap* - roof; also palm-leaf thatch (English \"attap\")\n- *bumbung* - roof\n- *bumbung panjang* - long gabled roof\n- *perabung* - ridge; *perabung lima* - five-ridged roof\n- *limas* - hipped or crossed-corner roof\n\n## Sources and gaps\n\nCensus data on roof materials and industry information: published information is limited.","key_facts":[{"label":"Traditional material","value":"Atap (nipa palm leaf thatch)"},{"label":"Traditional roof types","value":"Bumbung panjang, perabung lima, limas"},{"label":"Building law","value":"Street, Drainage and Building Act 1974 (Act 133); Uniform Building By-Laws 1984"},{"label":"Climate driver","value":"Equatorial heat, monsoon rain, east-coast floods"}],"regions":["Southeast Asia"],"aliases":["Malaysian roofing","rumah Melayu roofs"],"related":["roofing-in-southeast-asia","attap-roof","palm-thatch","rumah-gadang","traditional-thai-house","clay-roof-tile","concrete-roof-tile","metal-roofing","roofing-in-singapore","roofing-in-brunei","roofing-in-indonesia","roofing-in-thailand"],"company":null,"sources":[{"title":"Malay houses","url":"https://en.wikipedia.org/wiki/Malay_houses","publisher":"Wikipedia"},{"title":"Attap dwelling","url":"https://en.wikipedia.org/wiki/Attap_dwelling","publisher":"Wikipedia"},{"title":"Street, Drainage and Building Act 1974 (Act 133), Part I","url":"https://hba.org.my/laws/street/part1.htm","publisher":"National House Buyers Association (HBA), Malaysia"},{"title":"Uniform Building By-Laws 1984 [G.N. 5178/84] (as at 10 January 2024)","url":"https://psi.mbjb.gov.my/Home/Details/206737","publisher":"Majlis Bandaraya Johor Bahru library catalogue"}]},{"slug":"roofing-in-mali","title":"Roofing in Mali","type":"place","country":{"name":"Mali","iso2":"ML"},"summary":"Mali is a heartland of flat earth roofs on timber, from Djenné and Timbuktu to Dogon villages; metal sheet and concrete now dominate new building.","body":"Mali is the heartland of Sudano-Sahelian earth architecture. For more than a thousand years, houses, mosques and granaries along the Niger River and on the Bandiagara plateau have been roofed with earth laid over timber, or with tapering thatch on granaries. These roofs are still in use, but new houses in towns are increasingly built with cement blocks, metal sheet and concrete slabs.\n\n## Climate and hazards\n\nMost of Mali is Sahelian or Saharan: very hot, with a long dry season and a short rainy season. The rains are infrequent but can be violent, and they are the main enemy of earth roofs, eroding surfaces and gullying walls. UNESCO lists desertification, advancing sand, torrential rains and flooding among the threats to Mali's earthen heritage sites. Large daily temperature swings favour heavy, thermally massive roofs.\n\n## Roofing history\n\nSun-dried mud brick was already used at Jenné-Jeno, the ancient city near Djenné, in the second half of the first millennium AD. The Great Mosque of Djenné was first built between about 1200 and 1300, received additions in the 1830s and was completely rebuilt in 1906-1907. In Timbuktu, the Sankore mosque dates from the 14th century and Sidi Yahia from around 1400; Djingareyber, linked to the emperor Kankan Moussa (Mansa Musa), was rebuilt and enlarged in 1570-1583. In Gao, the Tomb of Askia was built in 1495 by Askia Mohamed of the Songhai Empire.\n\nDuring the colonial period and since independence in 1960, cement, fired brick, metal doors and metal-sheet roofs entered the building culture. UNESCO identifies these materials as pressures on the historic towns.\n\n## Traditional and vernacular roofs\n\n- **Flat earth roofs (Sudano-Sahelian):** Walls of sun-dried mud brick (*ferey*) and earth plaster (*banco*) carry timber joists, often palm, covered with sticks or mats and thick layers of earth. Mudbrick town houses are usually two storeys with flat roofs around a central courtyard and must be replastered at least every two years. See Sahelian earthen roofs and Djenné earthen architecture.\n- **Mosque roofs:** In Djenné's Great Mosque the earth roof on *rodier* palm timber is pierced by vents with removable fired-clay caps, and ceramic spouts throw rain clear of the walls. Projecting timbers (*toron*) act as permanent scaffolding for annual replastering.\n- **Dogon granaries:** Square earth granaries with thatched roofs tapering to a point, and the low branch-roofed *toguna* meeting shelter (see Dogon architecture).\n- **The Tomb of Askia:** a 17 m (56 ft) earth pyramid with two flat-roofed mosque buildings, an open assembly space and permanent scaffolding of *hasu* wood (*Maerua crassifolia*).\n\n## Roofing today\n\nMali is one of the few countries in the region where earth is still the most common roof. In the unweighted 2015 Multiple Indicator Cluster Survey sample (about 11,800 households), the leading categories were:\n\n| Main roof material | Share of sampled households |\n|---|---|\n| Banco (earth) on timber | 42.7% |\n| Metal sheet | 33.8% |\n| Cement | 10.8% |\n| Grass or straw | 4.5% |\n| Thatch or palm leaf | 2.2% |\n| Mat | 1.6% |\n| Tiles | 1.1% |\n\nEarth roofs remain in use in villages and historic towns such as Djenné, where nearly 2,000 traditional earth houses survive, while cement, fired brick and metal-sheet roofs spread in new building. The 2018 and 2023-24 Demographic and Health Surveys use similar categories, including earth clods (earth roofs) and metal.\n\nContemporary architects have looked for ways to cool metal and concrete buildings. The Falatow Jigiyaso orphanage in Bamako (2012) added a second roof above its blocks to cut heat, with concrete-block walls filled with *banco* earth. Since 2000 the association La Voûte Nubienne has trained masons in Mali to build earth-brick Nubian vaults that need no timber or metal.\n\n## Codes, standards and regulation\n\nHistoric towns are protected through UNESCO site management and national heritage listing; the Tomb of Askia, for example, was placed on Mali's national heritage list in 2003, and a 2002-2007 conservation plan was prepared with the earth-architecture research centre CRAterre-ENSAG.\n\n## Notable roofs\n\n- **Great Mosque of Djenné** (rebuilt 1906-1907): often described as the largest mud-brick building in the world, replastered each year in a community festival.\n- **Djingareyber, Sankore and Sidi Yahia mosques**, Timbuktu.\n- **Tomb of Askia**, Gao (1495).\n- **Dogon villages of the Bandiagara escarpment**: 289 villages with thatched granaries and toguna shelters.\n\n## Local roofing terms\n\n- **banco**: wet earth used for bricks and plaster.\n- **ferey**: sun-dried mud brick (Djenné).\n- **toron**: projecting timbers used as scaffolding.\n- **toguna**: Dogon men's shelter with a low branch roof.\n- **hasu**: *Maerua crassifolia* timber used for scaffolding at the Tomb of Askia.\n\n## Sources and gaps\n\nHeritage sites are well documented. Roof shares are unweighted MICS 2015 sample counts rather than official estimates; published information on codes and industry is limited.","key_facts":[{"label":"Traditional roof","value":"Flat earth roof on timber (banco)"},{"label":"Earliest evidence","value":"Mud brick at Jenné-Jeno, late 1st millennium AD"},{"label":"Most common roof (MICS 2015 file)","value":"Banco on timber, 42.7%; metal sheet 33.8%"},{"label":"Climate driver","value":"Heat, short violent rains, desertification"},{"label":"Landmark","value":"Great Mosque of Djenné (1906-1907)"}],"regions":["Africa"],"aliases":["Malian roofing","roofing in Mali"],"related":["roofing-in-west-africa","sahelian-earthen-roofs","djenne-earthen-architecture","dogon-architecture","nubian-vault","flat-roof","mud-roof","roofing-in-burkina-faso","roofing-in-niger","roofing-in-senegal","roofing-in-guinea"],"sources":[{"title":"Architecture of Mali","url":"https://en.wikipedia.org/wiki/Architecture_of_Mali","publisher":"Wikipedia"},{"title":"Timbuktu","url":"https://whc.unesco.org/en/list/119/","publisher":"UNESCO World Heritage Centre"},{"title":"Tomb of Askia","url":"https://whc.unesco.org/en/list/1139/","publisher":"UNESCO World Heritage Centre"},{"title":"Cliff of Bandiagara (Land of the Dogons)","url":"https://whc.unesco.org/en/list/516/","publisher":"UNESCO World Heritage Centre"},{"title":"Old Towns of Djenné","url":"https://whc.unesco.org/en/list/116","publisher":"UNESCO World Heritage Centre"},{"title":"Hausa urban architecture: construction and design in a cosmopolitan African society","url":"https://www.africanhistoryextra.com/p/hausa-urban-architecture-construction","publisher":"African History Extra"},{"title":"MICS 2015 Mali: matériau principal du toit (HC4)","url":"https://microdata.worldbank.org/catalog/3421/variable/F4/V479?name=HC4","publisher":"World Bank Microdata Library / INSTAT Mali"},{"title":"Mali DHS 2023-2024: main roof material (hv215)","url":"https://microdata.worldbank.org/catalog/8030/variable/F3/V109?name=hv215","publisher":"World Bank Microdata Library"},{"title":"La Voûte Nubienne","url":"https://www.lavoutenubienne.org/","publisher":"Association La Voûte Nubienne"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-malta","title":"Roofing in Malta","category":"world-roofing","type":"place","country":{"name":"Malta","iso2":"MT"},"regions":["Europe"],"company":null,"summary":"How Malta roofs its buildings: flat limestone-slab roofs sealed with lime and crushed-pottery deffun, corbelled giren huts, and modern concrete roofs.","aliases":["Maltese roofing","Maltese flat roof","deffun roof"],"body":"Malta's traditional roof is flat. For centuries Maltese builders spanned rooms with slabs of the islands' soft limestone and sealed them with layers of lime-based mortar, finished with *deffun*, a waterproof mix of lime and crushed pottery. The roof also served as a rain catchment for the cistern beneath every house. Research at the University of Malta has recently re-examined these roofs as naturally \"cool\" roofs.\n\n## Climate and hazards\n\nMalta has a hot, dry Mediterranean climate. In 2021 the highest temperature recorded was 41.5 °C (106.7 °F) in June, and national electricity demand peaked in August. Rain falls mostly in the cooler months, so roofs had to collect it efficiently. Traditional deffun roofs need yearly maintenance after the hot summer, before the first September rains.\n\n## Roofing history\n\nCorbelled stone huts called *giren* (singular *girna*) have been compared with the island's prehistoric megalithic temples, Sardinian nuraghi and the trulli of Puglia, but the resemblance may be superficial and most existing giren are thought to be relatively recent. A 1536 account by Jean Quintin may refer to them as \"African huts\".\n\nThe documented flat-roof tradition is strongly associated with the period of the Knights of St John (1530-1798), and University of Malta researchers describe traditional roofs as having been the norm for hundreds of years. Limestone slabs were first carried on stone arches and later on timber or iron beams. In more recent interventions, concrete slabs, screeds and bituminous membranes have replaced or covered the deffun on some old buildings, producing \"hybrid\" roofs, while new buildings use modern concrete roofs.\n\n## Traditional and vernacular roofs\n\n**The deffun roof** is built up, from the bottom, of:\n\n1. limestone slabs resting on stone arches, or later on timber or iron beams;\n2. a fill of limestone chippings mixed with stone dust and lime;\n3. a surface of *deffun*, hydrated lime mixed with crushed pottery, sprinkled with water, beaten and compacted (by hand in the past), then covered with straw to slow drying and help it cure.\n\nThe roof has a slight fall so that water drains quickly to the cistern. Because the mortar is porous, it absorbs moisture, including heavy summer dew, and evaporation from the surface cools it during the day.\n\n**The girna** is a round, or sometimes square or oval, hut of undressed dry stone, usually coralline limestone, with walls about 90 cm (3 ft) thick formed of two faces with a rubble core (*mazkan*). Its roof is corbelled: each course projects slightly inward until flat slabs can close the top, giving a dome-shaped ceiling. The roof was usually covered with gravel and *torba*, or sometimes a pebbly material called *ċagħqija*. Giren are most common in northern Malta, around Mellieħa, Manikata and Selmun, with over 30 in Majjistral Park; on Gozo they cluster in Upper Coralline Limestone areas such as Xagħra, Nadur and Qala.\n\n## Roofing today\n\nModern Maltese roofs are typically flat concrete construction, such as concrete planks finished with a waterproofing membrane. The University of Malta's EO4HBCS project (2020-2022), funded by the Malta Council for Science and Technology, compared traditional, hybrid and modern roofs using satellite imagery, drones and sensors, and found that the traditional roof gave the best balance between dispersing heat and insulating. The team is exploring guidelines to protect traditional roofs and a modern version for new buildings.\n\n## Codes, standards and regulation\n\nAs an EU member, Malta applies the Eurocodes for structural design.\n\n## Notable roofs\n\n- Traditional and hybrid roofs of Fort St Angelo, Birgu\n- Giren of Majjistral Park\n\n## Local roofing terms\n\n- *deffun* - lime and crushed-pottery waterproof surface\n- *torba* - covering layer used on girna roofs\n- *ċagħqija* - pebble-like roofing material\n- *girna* / *giren* - corbelled stone hut(s)\n- *mazkan* - rubble core of a double-faced wall\n## Sources and gaps\n\nSpecific Maltese roofing regulations and information on Maltese roofing manufacturers: published information is limited.","key_facts":[{"label":"Traditional roof","value":"Flat limestone slabs with lime fill and deffun surface"},{"label":"Waterproofing","value":"Deffun: lime mixed with crushed pottery"},{"label":"Vernacular hut","value":"Girna, corbelled dry stone"},{"label":"Maintenance","value":"Yearly, before the September rains"},{"label":"Climate driver","value":"Summer heat; rainwater harvesting"}],"related":["maltese-deffun-roof","flat-roof","cool-roof","trulli-of-alberobello","cycladic-flat-roof","roofing-in-italy","roofing-in-north-africa"],"sources":[{"title":"A first-ever research on the thermal properties of Malta's traditional roofs","url":"https://www.um.edu.mt/newspoint/news/2022/10/a-first-ever-research-on-the-thermal-properties-of-malta-s-traditional-roofs","publisher":"University of Malta"},{"title":"A New Approach to Studying Traditional Roof Behaviour in a Changing Climate: A Case Study from the Mediterranean Island of Malta (Heritage, 2021)","url":"https://www.mdpi.com/2571-9408/4/4/196","publisher":"MDPI Heritage"},{"title":"Sustainability of Traditional, Historical Roofs in the Mediterranean (Sustainability, 2023)","url":"https://www.mdpi.com/2071-1050/15/17/12723","publisher":"MDPI Sustainability"},{"title":"Girna","url":"https://en.wikipedia.org/wiki/Girna","publisher":"Wikipedia"},{"title":"EN Eurocodes","url":"https://eurocodes.jrc.ec.europa.eu/","publisher":"European Commission Joint Research Centre"}]},{"slug":"roofing-in-mauritania","title":"Roofing in Mauritania","category":"world-roofing","type":"place","country":{"name":"Mauritania","iso2":"MR"},"summary":"Mauritania's caravan towns of Chinguetti and Ouadane are built of dry stone with flat roofs timbered in palm wood; nomadic tents were long the main shelter.","body":"Mauritania lies across the western Sahara and the Sahel. Its historic caravan towns, Ouadane, Chinguetti, Tichitt and Oualata, are among the most distinctive stone-built settlements of the Sahara, with flat roofs carried on palm timber. They form a World Heritage site inscribed in 1996.\n\n## Climate and hazards\n\nMost of Mauritania is hot desert. The chief hazards for buildings are heat and moving sand: Chinguetti is seriously threatened by encroaching dunes, which mark its western edge, and several houses have been abandoned to the sand.\n\n## Roofing history\n\nThe four ksour were founded in the 11th and 12th centuries to serve caravans crossing the Sahara, and their urban fabric developed between the 12th and 16th centuries. UNESCO describes their architecture as an original and decorative stone architecture. Chinguetti is traditionally said to have been founded in 777 and was re-founded as a fortified trading centre in the 13th century. Its older quarters use reddish dry stone and mud brick, and its roofs are flat and timbered with palm wood. The Friday Mosque, a 13th-14th-century building of dry stone, has a square minaret topped by five ostrich-egg finials.\n\n## Traditional and vernacular roofs\n\n- **Flat stone-town roofs**: palm-wood beams spanning dry-stone or mud-brick walls, with flat roofs above, as in Chinguetti.\n- **Earth construction**: houses in a ksar are grouped buildings of stone and earth.\n\n## Notable roofs\n\n- **Chinguetti**: stone houses with palm-wood flat roofs and the Friday Mosque; the old quarter has five important manuscript libraries.\n- **Ouadane, Tichitt and Oualata**: the other three ksour of the World Heritage site.\n\n## Local roofing terms\n\n- **ksar** (plural *ksour*): fortified village.\n\n## Sources and gaps\n\nNo national roofing code was found in published sources. No information on domestic roofing manufacturers was found.\n\nPublished sources are limited. Published sources do not cover nomadic tents, the decorated earth houses of Oualata in detail, Nouakchott's modern housing, or roof-material statistics.","key_facts":[{"label":"Traditional materials","value":"Dry stone, mud brick, palm wood"},{"label":"Roof type","value":"Flat, timbered with palm wood"},{"label":"Landmark","value":"Ksour of Ouadane, Chinguetti, Tichitt and Oualata (World Heritage, 1996)"},{"label":"Climate driver","value":"Heat and sand encroachment"}],"regions":["Africa"],"aliases":["Mauritanian roofing","roofing in Mauritania"],"related":["roofing-in-north-africa","flat-roof","mud-roof","sahelian-earthen-roofs","roofing-in-morocco","roofing-in-algeria","roofing-in-mali","roofing-in-senegal"],"company":null,"sources":[{"title":"Ancient Ksour of Ouadane, Chinguetti, Tichitt and Oualata","url":"https://whc.unesco.org/en/list/750/","publisher":"UNESCO World Heritage Centre"},{"title":"Chinguetti","url":"https://en.wikipedia.org/wiki/Chinguetti","publisher":"Wikipedia"}]},{"slug":"roofing-in-mauritius","title":"Roofing in Mauritius","category":"world-roofing","type":"place","country":{"name":"Mauritius","iso2":"MU"},"summary":"Mauritius moved from thatch and iron-on-timber roofs to concrete after cyclones Alix and Carol destroyed nearly 40% of its housing in 1960.","body":"Mauritius is a volcanic island in the south-west Indian Ocean whose roofs have been shaped above all by tropical cyclones. Before 1960 most houses had thatched or corrugated iron roofs on timber frames; after two cyclones in 1960 destroyed nearly two-fifths of the housing stock, the island turned decisively to concrete.\n\n## Climate and hazards\n\nTropical cyclones generally occur between January and March, typically disrupting weather for about three days with heavy rain. Annual rainfall ranges from about 900 mm (35 in) on the coast to 1,500 mm (59 in) on the central plateau. Climate projections point to stronger cyclones.\n\n## Roofing history\n\nUnder the French governor Mahe de La Bourdonnais in the 18th century, numerous public buildings were erected, including part of Government House, the Chateau de Mon Plaisir and the Line Barracks. In 1955 the government built 1,000 workers' houses (*Cite Ouvriere*) in Port Louis suburbs, Quatre Bornes, Beau Bassin-Rose Hill and Curepipe.\n\nIn 1960 cyclones Alix and Carol destroyed nearly 40% of the housing stock. Most of the houses lost had thatched or corrugated iron roofs on timber frames, which could not resist high winds. The Central Housing Authority (CHA), set up in 1960, rehoused victims using prefabricated houses of asbestos panels with corrugated iron roofs on steel bracing, and houses with in-situ concrete walls and roofs. About 14,000 houses were built in 1961-1970. Cyclones in 1975 destroyed some 13,000 more houses, and Cyclone Claudette damaged 2,500 in 1979. Over 60 years the state contributed to about 92,250 houses, roughly 27% of the stock.\n\n## Traditional and vernacular roofs\n\n- **Thatched and iron-roofed timber houses**: the common pre-1960 house type.\n- **Creole houses**: timber houses of the colonial period.\n\n## Roofing today\n\nThe 2011 Housing Census asked for the principal roof material under four headings: concrete slab, iron or tin sheets, shingles, and other. In the Continuous Multi-Purpose Household Survey 2017 file, over 93% of households with a recorded roof fall in the first code, but category labels are not published on the microdata page, so national shares are not given.\n\n## Local roofing terms\n\n- *Cite* (French): state housing estate.\n\n## Sources and gaps\n\nDetailed descriptions of Mauritian Creole house roofs: published information is limited. No national roofing standard was identified. No information on domestic roofing manufacturers was found in published sources. No roof-specific heritage descriptions were found.\n\nLabelled census shares, details of Creole house roofs (for example shingles and steep hipped forms), sugar-estate houses and cyclone-shutter practice: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Concrete slab (census category; labelled shares not published)"},{"label":"Climate driver","value":"Tropical cyclones, January to March"},{"label":"Turning point","value":"Cyclones Alix and Carol, 1960: nearly 40% of housing destroyed"},{"label":"Census roof categories","value":"Concrete slab, iron or tin sheets, shingles, other (2011)"}],"regions":["Africa"],"aliases":["Mauritian roofing"],"related":["flat-roof","corrugated-iron","asbestos-cement-roofing","hurricane-roof-damage","roofing-in-seychelles","roofing-in-madagascar","roofing-in-comoros"],"company":null,"sources":[{"title":"Mauritian Housing: 1955 to the Present Day","url":"https://www.lemauricien.com/?p=183756","publisher":"Le Mauricien"},{"title":"Architecture of Mauritius","url":"https://en.wikipedia.org/wiki/Architecture_of_Mauritius","publisher":"Wikipedia"},{"title":"Mauritius 2011 Housing Census questionnaire","url":"https://unstats.un.org/unsd/Demographic/sources/census/quest/MUS2011enHs.pdf","publisher":"UN Statistics Division / Statistics Mauritius"}]},{"slug":"roofing-in-mexico","title":"Roofing in Mexico","category":"world-roofing","type":"place","country":{"name":"Mexico","iso2":"MX"},"summary":"Mexican roofing: Maya corbel vaults, palm thatch and colonial tile and brick vaults; today 78.6% of homes have concrete slab roofs (2020 census).","body":"Mexico combines several roofing traditions: Mesoamerican stone vaults and palm thatch, Spanish colonial clay tile, earth roofs and thin brick vaults, and, above all today, the reinforced concrete slab. Climates range from the dry north and temperate central highlands to the humid, hurricane-exposed Gulf, Caribbean and Pacific coasts.\n\n## Climate and hazards\n\n- **Earthquakes**, particularly in the centre and south, make roof weight and the connection of roof to walls critical.\n- **Hurricanes** on both coasts, including the Yucatán Peninsula.\n- **Heavy summer rain** in the south and the central highlands, and intense sun and heat in the north, where thermal mass and roof waterproofing matter.\n\n## Roofing history\n\n**Maya.** Maya builders roofed masonry rooms with the corbel vault, in which courses of stone step inward until they meet; it imitated the steep profile of the thatched hut but needed thick walls and gave little interior width. Temples often carried tall roof combs (*cresterías*), seen in double-walled form at Palenque and in flatter form in some Petén-style temples such as those at Tikal. Puuc-style buildings at Uxmal, Kabah, Sayil and Labná used concrete cores faced with cut stone for walls and vaults. Ordinary houses were built of perishable materials and roofed with thatch.\n\n**Colonial period.** Spanish builders brought fired clay tile (*teja*) and Mediterranean flat roofs of timber beams under earth (*terrado*). The thin brick vault known in Spain as the Catalan vault, laid in layers of flat bricks without formwork, reached New Spain and is still used for roofs and floors, where it is usually called *bóveda*. Talavera ceramic tiles decorate the domes and bell towers of many churches.\n\n**Modern period.** Reinforced concrete gradually replaced natural materials in most homes in the 20th century, and the flat slab (*losa*) became the typical roof of Mexican towns and cities. Corrugated metal and asbestos-cement sheet spread on informal housing, workshops and farm buildings, and sheet-metal roofs characterise some historic mining towns such as Cananea in Sonora.\n\n## Traditional and vernacular roofs\n\n- **Maya house** (*xa'anil naj* in Yucatán): oval in plan with a steep thatched roof, a form associated with resisting hurricane winds.\n- **Palapa**: an open-sided shelter with a roof of dried palm leaves, common on beaches and in rural areas (see palapa).\n- **Terrado**: flat earth roof on timber beams, a colonial and northern tradition counted separately in the census.\n- **Tejamanil**: hand-split wooden shingles, recorded by the census with wooden roofs.\n- **Teja** roofs in colonial towns; rounded ceramic tiles on riverside houses in the Nautla area of Veracruz.\n- **Anglo-Caribbean timber houses** with gabled roofs in Chetumal, Quintana Roo.\n\n## Roofing today\n\nINEGI's 2020 Population and Housing Census reported the roof material of occupied private dwellings as:\n\n- Concrete slab or joists with block infill (*losa de concreto o viguetas con bovedilla*): 78.6% (71.6% in 2010)\n- Metal sheet (*lámina metálica*): 12.5%\n- Asbestos sheet (*lámina de asbesto*): 3.7%\n- Wood or *tejamanil*: 2.0%\n- Clay tile (*teja*): 1.3%\n- Other, including cardboard sheet, *terrado*, palm or straw, fibre-cement sheet and scrap: 1.8%\n\nThe share of clay tile fell from 2.9% in 2010 to 1.3% in 2020, while asbestos sheet fell from 5.5% to 3.7%. INEGI's National Housing Survey (ENVI) 2020 found 44.2% of dwellings reporting damp or water leaks in foundations, walls or roofs, and 40.8% reporting cracks in roofs or walls. Flat slabs double as terraces, water-tank platforms and space for later extension, and are waterproofed with liquid-applied coatings (*impermeabilizantes*) or bituminous membranes.\n\n## Codes, standards and regulation\n\nBecause of Mexico's seismic and hurricane exposure, roof weight, anchorage and the connection of slab roofs to walls are central design concerns.\n\n## Industry\n\nMexico has large domestic cement, steel and roofing-sheet industries supplying the slab and sheet-metal markets.\n\n## Notable roofs\n\n- **Palenque**, Chiapas: corbel-vaulted temples with roof combs, a UNESCO World Heritage Site.\n- **Uxmal** and the Puuc sites of Yucatán: stone-faced concrete vaults.\n- **Colonial churches** with domes and bell towers faced in Talavera ceramic tile.\n\n## Local roofing terms\n\n- *Losa*: concrete slab roof.\n- *Vigueta y bovedilla*: precast joist and block-infill slab.\n- *Lámina*: sheet roofing (metal, asbestos-cement or cardboard).\n- *Teja*: clay roof tile. *Tejamanil*: split wooden shingle.\n- *Terrado*: earth roof on beams.\n- *Bóveda*: vault, especially the thin brick vault.\n- *Palapa*: palm-thatched shelter.\n- *Impermeabilizante*: roof waterproofing coating.\n\n## Sources and gaps\n\nPre-Hispanic Aztec roofing is poorly documented in published sources. Building regulations and roofing product standards: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Concrete slab, 78.6% of dwellings (2020)"},{"label":"Metal sheet roofs","value":"12.5% of dwellings (2020)"},{"label":"Traditional materials","value":"Palm thatch, clay tile, earth (terrado), brick vault"},{"label":"Ancient technique","value":"Maya corbel vault"},{"label":"Hazards","value":"Earthquakes, hurricanes"}],"regions":["Latin America","North America"],"aliases":["Mexican roofing","Roofing in México"],"related":["catalan-vault","flat-roof","palapa","palm-thatch","clay-roof-tile","corrugated-iron","corrugated-fibre-cement-sheet","roof-coating","roofing-in-the-united-states","roofing-in-the-caribbean","roofing-in-cuba","spanish-mediterranean-terracotta-roof"],"company":null,"sources":[{"title":"Architecture of Mexico","url":"https://en.wikipedia.org/wiki/Architecture_of_Mexico","publisher":"Wikipedia"},{"title":"Catalan vault","url":"https://en.wikipedia.org/wiki/Catalan_vault","publisher":"Wikipedia"},{"title":"Censo de Población y Vivienda 2020: Resultados complementarios","url":"https://inegi.org.mx/contenidos/programas/ccpv/2020/doc/Censo2020_Resultados_complementarios_EUM.pdf","publisher":"INEGI"},{"title":"Encuesta Nacional de Vivienda (ENVI) 2020: resultados nacionales","url":"https://coespo.qroo.gob.mx/wp-content/uploads/2025/03/ENVI_2020_NACIONAL.pdf","publisher":"INEGI (via COESPO Quintana Roo)"},{"title":"Maya architecture","url":"https://en.wikipedia.org/wiki/Maya_architecture","publisher":"Wikipedia"},{"title":"Palapa (structure)","url":"https://en.wikipedia.org/wiki/Palapa_(structure)","publisher":"Wikipedia"}]},{"slug":"roofing-in-micronesia","title":"Roofing in Micronesia","category":"world-roofing","type":"place","country":{"name":"Micronesia","iso2":"FM"},"summary":"Roofing in the Federated States of Micronesia: thatched faluw and houses, Nan Madol’s basalt city, and today mostly metal or concrete roofs.","body":"The Federated States of Micronesia (FSM) spans four states, Yap, Chuuk, Pohnpei and Kosrae, from high volcanic islands to small atolls. Traditional buildings used thatch of leaves on lashed timber frames, often on stone platforms, as in Yap's men's houses. Metal sheet now covers most homes, with concrete roofs a significant minority.\n\n## Climate and hazards\n\nFSM has a hot, wet tropical climate, so steep thatched roofs that shed rain quickly were the traditional answer.\n\n## Roofing history\n\n**Nan Madol.** Off the coast of Pohnpei, the ruined city of Nan Madol consists of about 92 artificial islets separated by tidal canals, built with massive columnar basalt laid in a header-and-stretcher pattern over coral fill. Megalithic construction began around AD 1180, and UNESCO dates most of the structures to 1200-1500 CE, when the site was the ceremonial centre of the Saudeleur dynasty. Nan Madol was inscribed as a World Heritage Site in 2016 and placed on the List of World Heritage in Danger because silting and mangroves threaten its walls.\n\n**Yap.** The Rull men's meeting house (*faluw*), listed on the US National Register of Historic Places in 1976, is a large rectangular building on a raised stone platform with a floor of treated betelnut palm trunks and a steep roof of tropical leaves tied with coconut fibre to bamboo supports.\n\n## Traditional and vernacular roofs\n\n- **Faluw** (Yap): men's house on a stone platform with a steep leaf-thatched roof.\n- **Thatched dwellings** on all four states, now a small minority.\n\n## Roofing today\n\nThe 2010 census recorded 16,767 living quarters: 71.4% had metal or tin roofs, 21.3% concrete, 5.5% thatch and 1.5% wood. Thatch was most common in Yap (355 of 2,311 units, about 15%) and concrete in Chuuk (1,699 of 7,024, about 24%). In Yap, the thatch share had fallen from about 22% in the 1994 census.\n\n## Codes, standards and regulation\n\nFSM has no national building code; the Pacific Region Infrastructure Facility has assisted with developing one since 2022.\n\n## Notable roofs\n\n- **Rull faluw**, Yap.\n- **Nan Madol**, Pohnpei (UNESCO, 2016), though its roofs are lost.\n\n## Local roofing terms\n\n- **Faluw** (Yapese): men's meeting house.\n\n## Sources and gaps\n\nInformation on typhoon damage to roofs: published information is limited. The roofs of buildings that stood within Nan Madol's walls are not described in published sources. No domestic roofing manufacturers were identified.\n\nFew sources describe traditional thatch species and techniques for Chuuk, Pohnpei and Kosrae.","key_facts":[{"label":"Dominant material today","value":"Metal/tin (71.4% of living quarters, 2010 census)"},{"label":"Concrete roofs","value":"21.3% (2010)"},{"label":"Traditional materials","value":"Leaf thatch, bamboo, coconut-fibre lashing, stone platforms"},{"label":"Heritage site","value":"Nan Madol, UNESCO World Heritage (2016)"},{"label":"Building code","value":"None national"}],"regions":["Oceania"],"aliases":["Roofing in the Federated States of Micronesia","FSM roofing"],"related":["palm-thatch","thatch","corrugated-iron","flat-roof","roofing-in-palau","roofing-in-the-marshall-islands","roofing-in-the-pacific-islands"],"company":null,"sources":[{"title":"FSM 2010 Census housing, Table H3 roof material by state","url":"https://www.pacificweb.org/DOCS/fsm/census/html/fsm2010housing_files/sheet002.htm","publisher":"PacificWeb / FSM Office of Statistics"},{"title":"Yap 1994 census, walls, roof and foundation","url":"https://pacificweb.org/library/fsm/states/yap/Yap1994H_files/sheet003.htm","publisher":"PacificWeb"},{"title":"Nan Madol: Ceremonial Centre of Eastern Micronesia","url":"https://whc.unesco.org/en/list/1503/","publisher":"UNESCO World Heritage Centre"},{"title":"Nan Madol","url":"https://en.wikipedia.org/wiki/Nan_Madol","publisher":"Wikipedia"},{"title":"Rull Men’s Meetinghouse","url":"https://en.wikipedia.org/wiki/Rull_Men%27s_Meetinghouse","publisher":"Wikipedia"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-moldova","title":"Roofing in Moldova","category":"world-roofing","type":"place","country":{"name":"Moldova","iso2":"MD"},"summary":"Moldovan roofing: four- and two-pitched roofs of reed over wattle-and-clay village houses, carved wooden gable 'spears', and Soviet-era asbestos-cement sheet.","body":"Moldova's traditional village house was a low building with wattle walls coated with clay, roofed with reed. Its roofs were usually four-pitched or two-pitched, and in the south carved wooden ornaments called \"spears\" crowned the gables.\n\n## Climate and hazards\n\nMoldova has a moderately continental climate with hot summers and cold winters. As in neighbouring Romania and Ukraine, snow, wind and summer storms are the main loads on roofs.\n\n## Roofing history\n\nLate 19th- and early 20th-century peasant houses, documented by the Russian Museum of Ethnography, were mostly built with wattle walls plastered with clay on both sides, though builders used limestone along the Dniester and Răut rivers, wood in the central Codri region and unfired mud bricks (*saman*) on the right bank of the Dniester. Most houses had four-pitched or two-pitched roofs covered with reed (or cane) or laths. A typical plan had a central entrance hall (*tinde*) between the living room and the best room (*casa mare*), with an earth bench or skirt (*prispa*) along the walls.\n\nIn southern Moldova, including the area around Comrat, builders placed a simple wooden cross on the gable while a house was under construction and, when it was finished, a local craftsman replaced it with an elaborate carved \"spear\". Designs carried meanings: two pigeons symbolised a harmonious marriage, and snake-like forms were said to ward off evil spirits. Experts estimate the tradition is 200-300 years old, but wooden houses were typically used for about three generations, so dating is difficult. The custom declined in the 1970s and 1980s, and some newer houses imitate the spears in sheet metal.\n\nDuring the Soviet period, corrugated asbestos-cement sheet (*shifer*) became a common roof across the former Soviet republics, including on rural houses. See shifer.\n\n## Traditional and vernacular roofs\n\n- **Reed roof:** four- or two-pitched roof of reed over wattle-and-clay walls.\n- **Gable spear:** carved wooden ornament on the gable, mainly in southern Moldova.\n\n## Roofing today\n\nModern houses use industrial materials, and newer homes in Western styles have displaced traditional forms.\n\n## Notable roofs\n\nTraditional houses with carved gable spears survive in villages of southern Moldova such as Avdarma and Ferapontievca.\n\n## Local roofing terms\n\n- *casa mare* - the best room of a traditional house\n- *tinde* - entrance hall\n- *prispa* - earth bench or skirt along the house walls\n\n## Sources and gaps\n\nNational statistics on roof materials and information on modern Moldovan roofing, building codes and industry: published information is limited. The account of Soviet-era asbestos-cement roofing is regional rather than specific to Moldova.","key_facts":[{"label":"Traditional covering","value":"Reed (cane) or laths"},{"label":"Traditional roof form","value":"Four-pitched or two-pitched"},{"label":"Gable ornament","value":"Carved wooden 'spears' (southern Moldova)"}],"regions":["Europe"],"aliases":["Moldovan roofing","roofs in Moldova"],"related":["thatch","water-reed-thatch","shifer","roofing-in-romania","roofing-in-ukraine","asbestos-cement-roofing"],"company":null,"sources":[{"title":"Moldovans. Late 19th – early 20th century","url":"https://ethnomuseum.ru/en/expositions/exhibitions/moldovans","publisher":"Russian Museum of Ethnography"},{"title":"The Lost Art Of Moldova's 'Rooftop Spears'","url":"https://www.rferl.org/a/moldova-rooftop-spears-house-architecture-tradition/32332545.html","publisher":"Radio Free Europe/Radio Liberty"},{"title":"Construction with Slate – Quick Solution to the Country's Housing Problems","url":"https://vestnik-pp.samgtu.ru/0585-430X/article/view/635982","publisher":"Stroitel'nye Materialy (journal)"}]},{"slug":"roofing-in-monaco","title":"Roofing in Monaco","category":"world-roofing","type":"place","country":{"name":"Monaco","iso2":"MC"},"summary":"Monaco roofing: terracotta tiles on older buildings, a dense high-rise skyline, and government promotion of green and solar roofs.","body":"Monaco is a small, densely built city-state on the Mediterranean coast. Its roofscape mixes older buildings, for which terracotta tiles are a traditional material, with a skyline of apartment towers. Little has been published about roofing in Monaco specifically; the main sources are general architectural works.\n\n## Climate and hazards\n\nMonaco has a Mediterranean climate with mild, wetter winters and hot, dry summers. Its steep coastal site and sea exposure mean roofs must deal with sun, salt air and occasional heavy rain rather than snow.\n\n## Roofing history\n\nThe Prince's Palace in the old town on the Rock dates its origins to 1191, during the Middle Ages, and has fortress-like towers and turrets. Monaco's best-known buildings belong to the Belle Époque (roughly 1871-1914), when Charles Garnier designed the Monte Carlo Casino and the Salle Garnier opera house, which opened in 1879. The Oceanographic Museum was inaugurated in 1910. In the 1970s, after a period of intensive development in Monte Carlo, Prince Rainier III banned high-rise construction; Prince Albert II later reversed this policy, and tall residential towers such as the 49-storey Odeon Tower have since been built.\n\n## Traditional and vernacular roofs\n\nMonégasque architecture uses local materials including granite, marble and terracotta tiles.\n\n## Roofing today\n\nMonte Carlo's buildings are known for terraces and balconies as well as decorative turrets. The government's energy-transition office has promoted green roofs: in March 2023 it ran a training programme with a green-roof association for up to 40 Monegasque building professionals, covering semi-intensive, intensive and mixed green roofs and photovoltaic green roofs, for both renovations and new buildings. The Mareterra eco-district, built on land reclaimed from the sea with seaside residences designed by Renzo Piano Building Workshop, was inaugurated on 4 December 2024 and was presented as a model of sustainable building.\n\n## Codes, standards and regulation\n\nMonaco has no heritage protection legislation, and construction has continued despite public objections.\n\n## Notable roofs\n\n- **Prince's Palace**, in the old town.\n- **Monte Carlo Casino** and the **Salle Garnier**, Belle Époque buildings by Charles Garnier.\n- **Oceanographic Museum** (1910).\n\n## Sources and gaps\n\nRoof-load guidance, details of traditional roof forms in the old town, building-code requirements, roof material statistics, local roofing terms and information on domestic roofing manufacturers for Monaco were not found in published sources. The official name of the energy-transition body is the Mission pour la Transition Énergétique.","key_facts":[{"label":"Climate driver","value":"Mediterranean sun, salt air, heavy rain"},{"label":"Traditional material","value":"Terracotta tiles"},{"label":"Heritage law","value":"No heritage protection legislation"},{"label":"Green roof training","value":"Mission pour la Transition Énergétique, March 2023"}],"regions":["Europe"],"aliases":["Monégasque roofing","Monaco roofs"],"related":["roofing-in-france","roofing-in-italy","green-roof","clay-roof-tile","flat-roof"],"company":null,"sources":[{"title":"Architecture of Monaco","url":"https://en.wikipedia.org/wiki/Architecture_of_Monaco","publisher":"Wikipedia"},{"title":"Programme Toitures végétalisées","url":"https://transition-energetique.gouv.mc/en/content/download/522509/5979595/file/Programme_Toitures_vegetalisees.pdf","publisher":"Mission pour la Transition Énergétique, Gouvernement Princier"},{"title":"A precedent for building on water: Mareterra eco-district completes in Monaco","url":"https://www.designboom.com/architecture/mareterra-ecodistrict-monaco-renzo-piano-valode-pistre-land-reclamation-12-05-2024/","publisher":"designboom"},{"title":"Mareterra: Monaco's groundbreaking six-hectare waterfront district to be inaugurated on 4th December","url":"https://monacolife.net/mareterra-monacos-groundbreaking-six-hectare-waterfront-district-to-be-inaugurated-on-4th-december","publisher":"Monaco Life"}]},{"slug":"roofing-in-mongolia","title":"Roofing in Mongolia","category":"world-roofing","type":"place","country":{"name":"Mongolia","iso2":"MN"},"summary":"Mongolian roofing centres on the felt-covered ger with its crown ring and radiating poles, alongside concrete and panel buildings in Ulaanbaatar.","body":"Mongolia's most characteristic roof is not fixed to a building at all: it is the domed, felt-covered roof of the *ger*, the portable round dwelling of Mongolian herders, known in Russian and English as the yurt. Gers remain the most common dwelling in the countryside and around Ulaanbaatar, while the capital's apartment blocks and public buildings use the flat roofs of masonry, concrete-frame and precast-panel construction.\n\n## Climate and hazards\n\nMongolia has a harsh continental climate with long, very cold winters, strong winds and a short summer, so a roof must above all keep out wind and conserve heat from the stove. Parts of the country are seismically active. The ger, a light structure held together in compression, has very low seismic vulnerability, whereas some precast-panel and modified masonry buildings in Ulaanbaatar are considered vulnerable to earthquakes.\n\n## Roofing history\n\nYurt-type dwellings have been used across the Central Asian steppe for at least 2,500 years; the earliest written description is usually traced to Herodotus' account of the tents of the Scythians. During the Mongol Empire of the 13th century the dwelling spread into parts of Europe and the Middle East. Over time the crown of the ger developed from the earlier *sarkhinag toono* to the Buddhist-style *khorlo toono*, shaped like a dharma wheel, and monasteries used decorated *uyangiin ger*.\n\nIn the 20th century, under socialist planning, Ulaanbaatar and other towns gained brick masonry, cast-in-place concrete and precast-panel apartment buildings. Since about 1990, migration from the countryside has expanded the city's **ger districts**, fenced plots holding gers and owner-built houses, some of which, such as the area around Gandan Monastery, have existed for more than a century.\n\n## Traditional and vernacular roofs\n\nThe ger roof is formed by straight roof poles (*uni*) that rise from the top of the lattice wall (*khana*) to a wooden crown ring (*toono*), which acts as a compression ring and is supported by one or more columns. The frame is covered with layers of felt, then canvas and in summer sun covers, with a thin undercover on the roof slopes and an outer cover on top. Ropes hold the frame together, and the weight of the covers, sometimes with a weight hung from the centre, keeps it in compression. The open crown admits light and lets out stove smoke.\n\n## Roofing today\n\nIn 2009 about 62 per cent of Ulaanbaatar's population lived in ger districts, although only about 43 per cent of ger-district residents lived in gers rather than houses. In rural areas around 65 per cent of households live in gers. Engineered buildings in the capital are mostly brick masonry, cast-in-place reinforced concrete frames and precast panels, along with steel and timber structures. Coal burned in simple stoves in ger districts is a major cause of winter air pollution.\n\n## Codes, standards and regulation\n\nBuilding regulation is the responsibility of the national government.\n\n## Notable roofs\n\n- **Uyangiin ger** - gers decorated in the style of Buddhist monasteries.\n\n## Local roofing terms\n\n- *ger* (гэр) - dwelling, home\n- *toono* (тооно) - crown ring\n- *uni* (унь) - roof poles\n- *khana* (хана) - lattice wall\n\n## Sources and gaps\n\nStatistics on roofing materials of fixed houses and information on fixed-house roofing, building codes and industry in Mongolia: published information is limited.","key_facts":[{"label":"Traditional roof","value":"Felt-covered ger roof with toono crown"},{"label":"Ger history","value":"Steppe tents used for 2,500+ years"},{"label":"Ulaanbaatar ger districts","value":"About 62% of population (2009)"},{"label":"Rural households in gers","value":"About 65%"},{"label":"Climate driver","value":"Extreme cold and wind"}],"regions":["East Asia"],"aliases":["Mongolian roofing"],"related":["ger-roof","roofing-in-china","roofing-in-russia","conical-roof","dome","earthquake-roofing"],"company":null,"sources":[{"title":"Yurt","url":"https://en.wikipedia.org/wiki/Yurt","publisher":"Wikipedia"},{"title":"Ger district","url":"https://en.wikipedia.org/wiki/Ger_district","publisher":"Wikipedia"},{"title":"Construction practices: Mongolia (North Asia exposure model)","url":"https://docs.openquake.org/global_risk_model/north_asia/exposure/construction_practices.html","publisher":"Global Earthquake Model Foundation (OpenQuake)"},{"title":"Yurt (encyclopedic entry)","url":"https://www.nationalgeographic.org/encyclopedia/yurt/","publisher":"National Geographic Society"}]},{"slug":"roofing-in-montenegro","title":"Roofing in Montenegro","category":"world-roofing","type":"place","country":{"name":"Montenegro","iso2":"ME"},"regions":["Europe"],"company":null,"summary":"How Montenegro roofs its buildings: karst stone houses with curved clay tiles, earlier straw, slate or stone slabs, and the Venetian towns of Kotor Bay.","aliases":["Montenegrin roofing","Krovovi u Crnoj Gori"],"body":"Montenegro is a small, mountainous Adriatic country where traditional houses were built almost entirely of local stone. Roofs varied with altitude and wealth, from straw and rough stone slabs to curved clay tiles, while the Bay of Kotor developed a Venetian-influenced coastal architecture.\n\n## Climate and hazards\n\nThe coast is Mediterranean, the karst interior is harsh, and the mountains have heavy winters. Rainwater was precious in the karst, and houses collected it in reservoirs (*bistijerne*). Montenegro is strongly seismic: the 1979 earthquake seriously damaged monuments in the Kotor region, including four Romanesque churches and the town walls. As part of Yugoslavia, Montenegro came under the first Yugoslav seismic building code of 1964.\n\n## Roofing history\n\nThe Bay of Kotor was a major Adriatic outpost of Venice, whose rule there began in the 15th century; Kotor's Cathedral of St Tryphon dates from 1166, replacing an 8th-century church. The Franciscan builder Vito of Kotor was the main architect of the Visoki Dečani monastery (1327-1335) in present-day Kosovo, showing the region's role in medieval Balkan building.\n\nInland, the birth house of the prince-bishop and poet Njegoš at Njeguši (where he was born in 1813), now a museum, represents the house of a well-to-do Montenegrin family. A French traveller described such houses as two-storey buildings of roughly cut stone covered with unprocessed stone slabs. The house was last rehabilitated in 1973, when the museum opened.\n\n## Traditional and vernacular roofs\n\n- **Karst stone house:** walls of roughly dressed stone in two faces, 50-80 cm (20-31 in) thick, with rubble packed between. Most houses had double-pitched roofs covered with half-round clay tiles (*ćiramida*), held at the edges by stones. In earlier times roofs could also be thatched with straw or covered with slate.\n- **Stone-slab roofs:** rough stone slabs, as described at Njeguši.\n- **Prizemljuše:** simple single-storey houses built by poorer families.\n- **Tower houses:** fortified stone towers occur in the north, for example the Ganić tower house in Rožaje.\n\n## Roofing today\n\nOld karst houses, often ruins, have recently been bought and renovated, frequently by foreign owners.\n\n## Codes, standards and regulation\n\nThe 2013 Law on the Protection of the Natural and Culturo-Historic Region of Kotor governs heritage work in the bay.\n\n## Notable roofs\n\n- Historic towns of the Bay of Kotor (UNESCO)\n- Njegoš's birth house, Njeguši\n\n## Local roofing terms\n\n- *ćiramida* - half-round clay roof tile\n- *bistijerna* - rainwater reservoir\n- *izba* - ground floor used for storage\n- *pojata* - separate building for cattle\n- *prizemljuša* - single-storey house\n\n## Sources and gaps\n\nData on current roofing materials, general building regulations, information on domestic roofing manufacturers and detailed technical descriptions of Montenegrin roofs were not found in published sources.","key_facts":[{"label":"Traditional walls","value":"Double-faced stone, 50-80 cm thick"},{"label":"Traditional roof","value":"Half-round clay tiles (ćiramida); earlier straw, slate or stone slabs"},{"label":"Seismic hazard","value":"High (1979 earthquake)"}],"related":["clay-roof-tile","stone-slate","thatch","kulla-tower-house","roofing-in-croatia","roofing-in-albania","roofing-in-serbia","roofing-in-kosovo","roofing-in-bosnia-and-herzegovina"],"sources":[{"title":"Njegoš's birth house (museum leaflet)","url":"https://en.narodnimuzej.me/wp-content/uploads/2020/09/Rodna-kuca-ENG.pdf","publisher":"National Museum of Montenegro"},{"title":"Old stone houses in Montenegro's karst region","url":"https://montenegro-for.me/2019/06/old-stone-houses-in-montenegros-karst-region/","publisher":"Montenegro For Me"},{"title":"Natural and Culturo-Historical Region of Kotor","url":"https://whc.unesco.org/en/list/125","publisher":"UNESCO World Heritage Centre"},{"title":"Visoki Dečani","url":"https://en.wikipedia.org/wiki/Visoki_De%C4%8Dani","publisher":"Wikipedia"},{"title":"Tower houses in the Balkans","url":"https://en.wikipedia.org/wiki/Tower_houses_in_the_Balkans","publisher":"Wikipedia"},{"title":"1963 Skopje earthquake","url":"https://en.wikipedia.org/wiki/1963_Skopje_earthquake","publisher":"Wikipedia"}]},{"slug":"roofing-in-morocco","title":"Roofing in Morocco","category":"world-roofing","type":"place","country":{"name":"Morocco","iso2":"MA"},"summary":"Morocco combines flat earth roofs of kasbahs and ksour, cedar ceilings, green-tiled pitched roofs on mosques, and flat roofs required in new districts from 1914.","body":"Morocco has two distinct roofing worlds. In the pre-Saharan valleys south of the Atlas, rammed-earth kasbahs and fortified villages (ksour) carry flat roofs of timber and earth. In the imperial cities, mosques, fountains and shrines are marked by pitched wooden roofs covered in green glazed tiles. Modern Morocco builds mainly in reinforced concrete with flat roofs, a pattern reinforced by colonial planning rules.\n\n## Climate and hazards\n\nThe climate ranges from Mediterranean on the coasts to cold winters in the Atlas and extreme heat in the pre-Saharan south. Earth buildings need constant maintenance against rain erosion. Morocco is also seismically active: the September 2023 earthquake caused cracks and partial collapses at the ksar of Aït Benhaddou, among many other buildings.\n\n## Roofing history\n\n**Medieval mosques.** Traditional Moroccan mosques have prayer halls with wooden ceilings and horseshoe arches. At the Qarawiyyin Mosque in Fez, founded in the 9th century and expanded in 1134-1143, plain timber ceilings in the central nave were replaced with *muqarnas* ceilings and ribbed domes. The Al-Hamra Mosque in Fez, usually dated to the 14th century (Marinid period), has pitched wooden roofs topped with green ceramic tiles, a style common to Moroccan mosques (see Moroccan green roof tiles).\n\n**Ceilings.** Many mosques and mausoleums have sloped wood-frame ceilings called *berchla*, often painted; a famous example is in the 16th-century Saadian Tombs in Marrakesh. Wood came mostly from Moroccan cedar, once widespread but now largely limited to the Middle Atlas. Large residences also used reed ceilings of woven reed stems painted red and black; the Kasbah Taourirt in Ouarzazate has both wood and reed ceilings.\n\n**Earth architecture.** Rammed earth (*tabia*, pisé) was one of the most common construction methods, used for city ramparts and kasbahs. Kasbahs built without lime can crumble within a couple of decades of abandonment. At Aït Benhaddou, fortified since the 11th century, the surviving buildings date from no earlier than the 17th century; taller buildings used rammed earth to the first floor and lighter adobe above to reduce wall loads.\n\n**Colonial regulation.** An urban planning decree of April 1914 required the roofs of all buildings in new districts to be flat, capped heights at four storeys and required 20% of planned areas to be courtyards or gardens.\n\n## Traditional and vernacular roofs\n\n- **Flat earth roofs**: timber or palm joists, reeds or palm fronds, and compacted earth on kasbahs and ksour (see Roofing in North Africa).\n- **Green-tiled pitched roofs**: on mosque prayer halls, minaret caps, fountains and shrines.\n- **Berchla**: sloped, painted timber ceilings.\n- **Domes**: pierced domes and vaults over hammams (from about the 14th century in Fez) and domed saints' tombs (*marabouts*).\n\n## Roofing today\n\nReinforced concrete frames with flat, waterproofed roofs are the norm in Moroccan towns (see Roofing in North Africa).\n\n## Codes, standards and regulation\n\nMorocco's paraseismic construction regulation, RPS2000, sets the seismic actions ordinary buildings must resist and minimum design and construction provisions. At Aït Benhaddou, attempts to introduce cement have so far failed, and the site's authenticity has been kept largely by avoiding new concrete.\n\n## Notable roofs\n\n- **Ksar of Aït Benhaddou**: earth buildings within high walls, a World Heritage site since 1987.\n- **Al-Hamra Mosque, Fez**: green-tiled pitched roofs.\n- **Nejjarine Fountain, Fez**: carved wood canopy with a short green-tiled roof (19th century).\n- **Saadian Tombs, Marrakesh**: ornate *berchla* ceiling.\n\n## Local roofing terms\n\n- **berchla** (bershla): sloped wood-frame ceiling.\n- **tabia**: rammed earth.\n- **ksar** (plural *ksour*): fortified village.\n\n## Sources and gaps\n\nNo information on domestic roofing manufacturers was found in published sources.\n\nDetails of flat earth roof layers in Moroccan kasbahs, the Arabic or Amazigh names for green roof tiles, modern roof-material shares, and post-2023 changes to building rules are not documented in published sources.","key_facts":[{"label":"Traditional materials","value":"Rammed earth, cedar, reed, green glazed tile"},{"label":"Colonial rule","value":"April 1914 decree required flat roofs in new districts"},{"label":"Seismic regulation","value":"RPS2000"},{"label":"Landmark","value":"Ksar of Aït Benhaddou (World Heritage, 1987)"}],"regions":["Africa","Middle East"],"aliases":["Moroccan roofing","roofing in Morocco"],"related":["roofing-in-north-africa","moroccan-green-roof-tiles","flat-roof","mud-roof","glazed-roof-tile","dome","roofing-in-algeria","roofing-in-mauritania","roofing-in-spain"],"company":null,"sources":[{"title":"Moroccan architecture","url":"https://en.wikipedia.org/wiki/Moroccan_architecture","publisher":"Wikipedia"},{"title":"Architecture of Fez","url":"https://en.wikipedia.org/wiki/Architecture_of_Fez","publisher":"Wikipedia"},{"title":"Al-Hamra Mosque","url":"https://en.wikipedia.org/wiki/Al-Hamra_Mosque","publisher":"Wikipedia"},{"title":"Al-Qarawiyyin Mosque","url":"https://en.wikipedia.org/wiki/Al-Qarawiyyin_Mosque","publisher":"Wikipedia"},{"title":"Ksar of Ait-Ben-Haddou","url":"https://whc.unesco.org/en/list/444/","publisher":"UNESCO World Heritage Centre"},{"title":"Aït Benhaddou","url":"https://en.wikipedia.org/wiki/A%C3%AFt_Benhaddou","publisher":"Wikipedia"},{"title":"Morocco: Règlement de construction parasismique (RPS2000)","url":"https://www.preventionweb.net/publication/morocco-reglement-de-construction-parasismique","publisher":"PreventionWeb (UNDRR)"}]},{"slug":"roofing-in-mozambique","title":"Roofing in Mozambique","category":"world-roofing","type":"place","country":{"name":"Mozambique","iso2":"MZ"},"summary":"Mozambique's roofs range from the palm-leaf macuti houses and stone town of Mozambique Island to today's corrugated iron and fibre-cement sheet.","body":"Mozambique's long Indian Ocean coast has given it two strong roofing traditions: the stone-and-lime buildings of Swahili and Portuguese coastal towns, and houses of poles, earth and palm-leaf thatch, known on Mozambique Island as *macuti*. Over the last seventy years, cement blocks and sheet roofs of corrugated iron or fibre cement have steadily replaced both.\n\n## Climate and hazards\n\nUN-Habitat's housing profile lists cyclones, heavy rains, floods, droughts, strong winds and earthquakes among the country's main risks. In 2013 alone disasters killed 117 people, displaced 172,000 and caused damage of about US$500 million, roughly 10% of the national budget. Most households protect their homes by improvised means.\n\n## Roofing history\n\nThe Portuguese established a port and naval base on Mozambique Island in 1507, and the island served as the seat of colonial government until 1898, when the capital moved to Lourenco Marques (now Maputo). The Chapel of Nossa Senhora de Baluarte, built in 1522, is often described as the oldest European building in the Southern Hemisphere, and Fort Sao Sebastiao dates from 1558 to 1620. The island's architecture combines Swahili, Arab and European influences and has kept a remarkable unity because the same building techniques, materials and decorative principles were used without interruption.\n\nSince the 1950s, and especially since the late 1970s, houses have increasingly been built of cement blocks with fibre-cement or corrugated iron roofs. After the 1976-1992 war, people moving to the island caused overcrowding, and scarce, expensive materials made maintenance difficult.\n\n## Traditional and vernacular roofs\n\n- **Macuti house**: a frame of mangrove poles (*siki*) and bamboo under a generous hipped roof carried on two main posts about 2.5 m (8 ft) high, covered with coconut palm leaves. Walls are a curtain of mangrove sticks (*laca laca*) filled with stones, earth and sand (*pau a pique*); a plant extract (*murrapa*, *Cissus integrifolia*) was added for strength and water resistance. See Macuti house.\n- **Stone town houses**: stone and lime buildings in the northern half of the island.\n- **Canico settlements**: reed-built housing of the colonial era on short-term leased land, designed to be dismantled.\n\n## Roofing today\n\nUN-Habitat reports that fewer than 2% of homes are built entirely with conventional materials such as masonry and zinc sheet, that most people build informally with local materials, and that up to 60% of construction materials are imported. On Mozambique Island, a 2011 ICOMOS study found that only about 35% of houses still had macuti or other leaves as roof covering, and that *macarasse* leaves had largely replaced coconut macuti because they were easier to obtain.\n\n## Codes, standards and regulation\n\nThe general regulation for urban buildings is the *Regulamento Geral das Edificacoes Urbanas* (REGEU). Construction licences under Decree 2/2004 may not exceed 10 years, and urban land is defined by the 2006 Urban Land Regulation. Most self-built housing does not go through formal licensing. On Mozambique Island, local by-laws have restricted urban change since 1878, and Law 10/88 of 1988 classifies buildings older than 1920 as national cultural heritage.\n\n## Industry\n\nUN-Habitat notes heavy dependence on imported materials.\n\n## Notable roofs\n\n- **Island of Mozambique** (UNESCO 1991): stone and lime town in the north, macuti town in the south. The island is about 3 km (1.9 mi) long and 200 to 500 m (660 to 1,640 ft) wide, with about 14,000 residents.\n\n## Local roofing terms\n\n- *macuti* (makuti): coconut palm-leaf roof covering.\n- *macarasse*: leaves now commonly used instead of macuti.\n- *siki*: mangrove poles used for the frame.\n- *chapa de zinco* (Portuguese): zinc or galvanised roofing sheet.\n\n## Sources and gaps\n\nNo information on domestic roofing manufacturers was found in published sources.\n\nNational census tables of roof material (2007 or 2017): published information is limited. Detail on inland vernacular forms (for example Makonde or Shona-speaking areas) was not found in published sources.","key_facts":[{"label":"Traditional materials","value":"Coconut palm leaf (macuti), mangrove poles, stone and lime"},{"label":"Climate driver","value":"Cyclones, floods, strong winds"},{"label":"Landmark","value":"Island of Mozambique (UNESCO 1991)"},{"label":"Building regulation","value":"REGEU (Regulamento Geral das Edificacoes Urbanas)"}],"regions":["Africa"],"aliases":["Mozambican roofing"],"related":["macuti-house","palm-thatch","corrugated-iron","corrugated-fibre-cement-sheet","roofing-in-southern-africa","roofing-in-east-africa","roofing-in-tanzania","roofing-in-malawi","roofing-in-zimbabwe","roofing-in-south-africa","roofing-in-madagascar"],"company":null,"sources":[{"title":"Island of Mozambique","url":"https://whc.unesco.org/en/list/599/","publisher":"UNESCO World Heritage Centre"},{"title":"Island of Mozambique","url":"https://en.wikipedia.org/wiki/Island_of_Mozambique","publisher":"Wikipedia"},{"title":"The Macuti House, Traditional Building Techniques and Sustainable Development in Ilha de Mocambique (ICOMOS 17th General Assembly, 2011)","url":"https://vbn.aau.dk/ws/portalfiles/portal/310575981/SOLLIEN_ARTICLE_PROCEEDINGS.pdf","publisher":"Silje Eroy Sollien / Aalborg University repository"},{"title":"Perfil do Sector da Habitacao de Mocambique","url":"https://unhabitat.org/sites/default/files/documents/2019-05/housing_profile_mozambique_pt.pdf","publisher":"UN-Habitat"}]},{"slug":"roofing-in-myanmar","title":"Roofing in Myanmar","category":"world-roofing","type":"place","country":{"name":"Myanmar","iso2":"MM"},"summary":"Roofing in Myanmar (Burma), from the brick vaults of Bagan and teak monasteries crowned by tiered pyatthat to dhani palm thatch and corrugated metal sheet.","body":"Myanmar (Burma) is known for its multi-tiered *pyatthat* roofs, which crown monasteries, palaces and city gates, and for the thousands of brick temples of Bagan. Ordinary housing has moved from palm-leaf thatch and bamboo toward corrugated metal sheet.\n\n## Climate and hazards\n\nMost of the country has a tropical monsoon climate with very heavy rain in the coastal and delta regions and a drier central zone around Bagan and Mandalay. The coast is exposed to tropical cyclones, and much of the country is seismically active. The 2016 national building code was developed with a focus on disaster-resilient construction.\n\n## Roofing history\n\n**Early stupas.** In the Pyu period (from about 200 BC to 100 CE onward), stupas, temples and pagodas were topped with finials and spires, often with a *hti*, an umbrella-shaped crowning ornament that is still used today.\n\n**Bagan.** By the mid-12th century, Bagan had more than 10,000 red-brick stupas and temples. Bagan builders used brick vaulted halls and tapered, rising roofs, and the region's dry climate has helped many survive. The Ananda Temple, begun about 1090 and completed in 1105, has brick-vaulted halls and one of the earliest uses of the tiered pyatthat, placed to signal a throne or sacred image inside.\n\n**Royal and monastic timber.** Later kingdoms built palaces and monasteries (*kyaung*) of teak. Mandalay Palace (1857-1859) had pyatthat roofs over its throne rooms, including the Great Audience Hall; only part of it survived a fire in 1945. Wooden monasteries of the Konbaung period, such as Shwe In Bin Monastery (1895), keep the full set of pyatthat-crowned pavilions prescribed by monastic tradition. Because the tropical climate requires frequent repair of timber and stucco, parts of Mandalay Palace have been rebuilt with concrete.\n\n**Colonial era.** Under British rule, Burmese motifs were used on public buildings; Yangon City Hall (1926-1936), designed by U Tin, carries traditional tiered pyatthat roofs.\n\n## Traditional and vernacular roofs\n\n- **Pyatthat:** a stack of gabled roofs in odd numbers of tiers, separated by box-like stages and topped by a spire. Before the colonial period its use was restricted to royal and religious buildings, and the number of tiers was tied to rank: only the king could have nine tiers. See the separate pyatthat entry.\n- **Houses:** the 2014 census recorded roofing in six main categories, of which the traditional ones were palm leaf (*dhani*, *theke* or *in* leaf), bamboo, wood and earth, alongside corrugated sheet and tile, brick or concrete. *Dhani* is the nipa palm, whose leaves are folded into thatch panels.\n\n## Roofing today\n\nThe 2014 Population and Housing Census included roofing material in its housing questions. Township data illustrate the pattern: in Pyinmana township, 82.3% of households had corrugated-sheet roofs and 15.0% had dhani, theke or in leaf roofs, with tile, brick or concrete at only 1.3%.\n\nThe Shwedagon Pagoda's gold covering is repaired or replaced every four or five years, and its crowning hti, donated by King Mindon in 1871, was replaced in 1999.\n\n## Codes, standards and regulation\n\nThe Myanmar National Building Code (MNBC) 2016 was developed by UN-Habitat in coordination with the Ministry of Construction and technical bodies including the Myanmar Engineering Society. It is issued in seven parts.\n\n## Notable roofs\n\n- **Bagan** (UNESCO World Heritage): brick temples such as Ananda and Gawdawpalin with tiered roofs.\n- **Mandalay Palace**: pyatthat over the throne halls.\n- **Shwe In Bin Monastery, Mandalay**: carved teak monastery with pyatthat pavilions.\n- **Yangon City Hall**: colonial-era civic building with pyatthat roofs.\n\n## Local roofing terms\n\n- *pyatthat* - multi-tiered roof (from Sanskrit *prasada*)\n- *boun* - a single tier of a pyatthat\n- *hti* - umbrella finial\n- *kyaung* - monastery\n- *dhani* - nipa palm thatch; *theke* - thatch grass\n\n## Sources and gaps\n\nNational census percentages for roof materials and industry data: published information is limited.","key_facts":[{"label":"Iconic form","value":"Pyatthat (odd-numbered tiered roof)"},{"label":"Traditional materials","value":"Dhani (nipa) and theke thatch, bamboo, teak"},{"label":"Census roof categories (2014)","value":"Dhani/theke/in leaf, bamboo, earth, wood, corrugated sheet, tile/brick/concrete"},{"label":"Building code","value":"Myanmar National Building Code 2016"},{"label":"Climate driver","value":"Monsoon rain, cyclones, earthquakes"}],"regions":["Southeast Asia"],"aliases":["Burmese roofing","Roofing in Burma"],"related":["roofing-in-southeast-asia","pyatthat","pagoda-roof","thai-temple-roof","palm-thatch","bamboo-roofing","corrugated-iron","roofing-in-thailand","roofing-in-india","roofing-in-china"],"company":null,"sources":[{"title":"Pyatthat","url":"https://en.wikipedia.org/wiki/Pyatthat","publisher":"Wikipedia"},{"title":"Architecture of Myanmar","url":"https://en.wikipedia.org/wiki/Architecture_of_Myanmar","publisher":"Wikipedia"},{"title":"Myanmar National Building Code (MNBC) 2016","url":"https://unhabitat.org/myanmar-national-building-code-mnbc-2016","publisher":"UN-Habitat"},{"title":"The 2014 Myanmar Population and Housing Census: Thematic Report on Housing Conditions and Household Amenities (Census Report Vol. 4-I)","url":"https://data.opendevelopmentmekong.net/dataset/7fe7dfbc-e72d-4b2b-97f5-5d409e4a8a05/resource/8c6b42d1-956a-4d0b-9a8d-3a32884f7913/download/reportthematicreportonhousingconditionshouseholdamenities-censusreport4-idopaug2017eng.pdf","publisher":"Department of Population, Myanmar / UNFPA"},{"title":"Census 2014 township profile: Pyinmana","url":"https://www.themimu.info/sites/themimu.info/files/documents/TspProfiles_Census_Pyinmana_2014_ENG.pdf","publisher":"Myanmar Information Management Unit"},{"title":"Ananda Temple","url":"https://en.wikipedia.org/wiki/Ananda_Temple","publisher":"Wikipedia"}]},{"slug":"roofing-in-namibia","title":"Roofing in Namibia","category":"world-roofing","type":"place","country":{"name":"Namibia","iso2":"NA"},"summary":"Most Namibian homes are roofed with corrugated iron, but grass thatch still covered about a quarter of households in the 2011 census sample.","body":"Namibia is a largely arid country whose roofs are dominated by corrugated iron sheet. Grass thatch remains important, covering about a quarter of households in the 2011 census sample, and Himba homesteads in the far north-west keep a building tradition of mopane timber plastered with clay and dung.\n\n## Climate and hazards\n\nThe country is largely arid to semi-arid, with most rain falling in summer storms. Mobility is part of the pastoral building tradition: Himba families may move their homes within a year depending on rainfall and access to water.\n\n## Roofing history\n\nCensus data show the recent pattern: in 2011 about three in five households had corrugated iron or zinc roofs and a quarter had grass thatch, and later survey reporting suggests metal has since gained further ground.\n\n## Traditional and vernacular roofs\n\n- **Himba homestead** (*onganda*): a circular hamlet of huts and work shelters around the sacred ancestral fire (*okuruwo*) and a livestock kraal, in the Kunene Region (formerly Kaokoland). Houses are built of mopane wood, plastered by women with red clay soil and cow manure.\n- **Thatched round huts**: the 2011 census records grass thatch on about a quarter of households, and walls of poles, sticks, grass or reeds on about 17%.\n- **Rondavel-type huts** with conical thatch occur across the region (see Rondavel).\n\n## Roofing today\n\nIn the unweighted 2011 Population and Housing Census public-use sample (93,647 households with a recorded roof), roofs are recorded as:\n\n| Main roof material (H6) | Share of sampled households |\n|---|---|\n| Corrugated iron sheet / zinc | 61.9% |\n| Thatch grass | 25.6% |\n| Asbestos sheet | 6.0% |\n| Wood covered with malthoid | 2.2% |\n| Tin | 0.8% |\n| Sticks with mud, clay or cow dung | 0.8% |\n| Brick tiles | 0.7% |\n| Concrete | 0.4% |\n| Slate | 0.3% |\n| Other | 1.2% |\n\nWalls in the same sample were mainly cement blocks, brick or stone (41.2%), corrugated iron or zinc (20.5%) and poles, sticks, grass or reeds (16.8%). A Namibia Statistics Agency report released in November 2022 put the share of households using corrugated iron sheets for roofing at 84.1%, suggesting a continued shift from thatch to metal; the report as published does not state the survey year for that figure.\n\n## Local roofing terms\n\n- *onganda* (Otjiherero): homestead.\n- *okuruwo* (Otjiherero): sacred ancestral fire at the centre of the homestead.\n- *malthoid*: bituminous felt laid over timber, a census roof category.\n\n## Sources and gaps\n\nDetailed archaeological or documentary evidence for early Namibian roofs: published information is limited. No national roofing standard was identified. No information on domestic roofing manufacturers was found in published sources. No roof-specific heritage listings were identified.\n\nCensus figures are unweighted counts in the public-use sample. Information on Owambo, Kavango and Caprivi (Zambezi) thatching practice, and on San grass shelters: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Corrugated iron/zinc, 61.9% (Census 2011 sample, unweighted)"},{"label":"Thatch share","value":"25.6% of households (Census 2011 sample, unweighted)"},{"label":"Traditional materials","value":"Grass thatch, mopane wood, clay and dung plaster"},{"label":"Climate driver","value":"Arid climate, summer storms"}],"regions":["Africa"],"aliases":["Namibian roofing"],"related":["corrugated-iron","thatch","rondavel","asbestos-cement-roofing","roofing-in-southern-africa","roofing-in-angola","roofing-in-botswana","roofing-in-south-africa","roofing-in-zambia"],"company":null,"sources":[{"title":"Namibia Population and Housing Census 2011: Roof (H6)","url":"https://microdata.nsanamibia.com/index.php/catalog/9/variable/F1/V11?name=H6","publisher":"Namibia Statistics Agency National Data Archive"},{"title":"Namibia Population and Housing Census 2011: Outer Walls (H5)","url":"https://microdata.nsanamibia.com/index.php/catalog/9/variable/F1/V10?name=H5","publisher":"Namibia Statistics Agency National Data Archive"},{"title":"The Brief (Namibia), 2 November 2022","url":"https://thebrief.com.na/?p=3890","publisher":"The Brief"},{"title":"Himba people","url":"https://en.wikipedia.org/wiki/Himba_people","publisher":"Wikipedia"}]},{"slug":"roofing-in-nauru","title":"Roofing in Nauru","category":"world-roofing","type":"place","country":{"name":"Nauru","iso2":"NR"},"summary":"Nauru roofing: a phosphate-era housing stock of metal roofs on concrete or board walls, with roof gutters feeding household water tanks.","body":"Nauru is a single raised coral island whose modern housing was shaped by the phosphate industry. Metal roofs cover more than nine in ten households, and roof guttering and tanks are a major household water source.\n\n## Climate and hazards\n\nThe island is hot and humid, and rainwater collected from roofs is an important household water source, as the census tables on tanks and downpipes show.\n\n## Roofing history\n\nSettlement is concentrated in districts on the narrow coastal belt around the island, with one village beside Buada Lagoon in the interior. Funded by phosphate royalties, the government once provided housing free, and some Nauruans used their own phosphate income to build larger homes; house styles now resemble those of Western metropolitan countries. The 2011 census still recorded asbestos as a roofing category, alongside tin or aluminium, plastic, concrete and thatch.\n\n## Roofing today\n\nThe 2021 census counted 2,021 households. By main roof material, 91.3% had metal, iron or aluminium; 5.8% concrete, cement or brick; 1.2% wood; 1.1% asbestos; and only three households traditional materials. Walls were mainly concrete or brick (54.8%), Masonite (16.0%) and wood (12.0%).\n\nWater storage is closely tied to roofs: 58.4% of households had plastic tanks, 18.6% concrete and 18.3% aluminium or galvanised iron, while 3.7% had no storage. Of 1,945 households asked about downpipes, 546 had none and 202 had downpipes disconnected from their tanks.\n\n## Codes, standards and regulation\n\nThe Building Control Act was passed in 2025, and a national building code was in draft at that time.\n\n## Sources and gaps\n\nInformation on pre-colonial Nauruan roofing: published information is limited. No domestic roofing manufacturers were identified.\n\nPre-colonial and early colonial building on Nauru, and any surviving asbestos-removal programmes: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal/iron/aluminium (91.3% of households, 2021 census)"},{"label":"Asbestos roofs","value":"1.1% of households (2021)"},{"label":"Rainwater","value":"58.4% plastic tanks; 546 households without downpipes"},{"label":"Building law","value":"Building Control Act 2025; code in draft"}],"regions":["Oceania"],"aliases":["Nauruan roofing"],"related":["corrugated-iron","asbestos-cement-roofing","rainwater-harvesting-roofs","coastal-corrosion","roofing-in-kiribati","roofing-in-the-marshall-islands","roofing-in-the-pacific-islands"],"company":null,"sources":[{"title":"Nauru 2021 Census household tables 1-51","url":"https://stats.gov.nr/download/49/2021/357/household-tables-1-51.pdf","publisher":"Nauru Bureau of Statistics"},{"title":"Nauru 2011 census, materials and condition of roofing (H8)","url":"https://microdata.pacificdata.org/index.php/catalog/26/variable/F2/V33?name=ROOF","publisher":"Pacific Data Hub (SPC)"},{"title":"Nauru - Settlements","url":"https://www.everyculture.com/Oceania/Nauru-Settlements.html","publisher":"Countries and Their Cultures"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-nepal","title":"Roofing in Nepal","category":"world-roofing","type":"place","country":{"name":"Nepal","iso2":"NP"},"summary":"Nepal is known for the tiered, tile-roofed Newar pagodas of the Kathmandu Valley; its houses use thatch, tile, slate, iron sheet and concrete.","body":"Nepal stretches from the hot, humid Terai plains on the Indian border to the highest mountains on earth. Its census recognises roofs of thatch and straw, galvanised iron, tile and slate, reinforced concrete, wood and mud, a range that reflects this variety of climate. The country's most celebrated contribution to roofing is the tiered **Newar pagoda roof** of the Kathmandu Valley.\n\n## Climate and hazards\n\nThe summer monsoon brings heavy rain to most of the country, while the high mountains have long, cold winters with snow. Nepal lies on the collision zone between the Indian and Eurasian plates and suffers frequent strong earthquakes. The 1934 Nepal-Bihar earthquake and the magnitude 7.8 Gorkha earthquake of 2015 both caused severe damage in the Kathmandu Valley, where many historic temples collapsed in 2015.\n\n## Roofing history\n\nAccording to UNESCO, the blending of Hindu and Buddhist art in the Kathmandu Valley goes back at least to the 5th century CE; Changu Narayan carries one of the valley's earliest inscriptions from that time. The roots of Newar architecture are traced to the Licchavi period (about 400-750 CE), and the Durbar Squares of Kathmandu, Patan and Bhaktapur were built up between the 12th and 18th centuries, with the greatest flowering roughly from 1500 to 1800 under the Malla kings. Nepalese craftsmen, including Arniko, carried the style beyond the valley.\n\nThe valley's temples and palaces were built of fired brick in mud mortar, with timber floors, windows and roof frames, and roofs of small overlapping terracotta tiles, some decorated or covered with gilded brass. In the modern period galvanised iron sheet and reinforced concrete were added to these traditional materials, and both appear as standard categories in the census.\n\n## Traditional and vernacular roofs\n\n- **Newar pagoda roof**: two or more diminishing tiled roofs on a brick shrine, each propped on carved timber struts. The Nyatapola Temple in Bhaktapur (1701-1702), with five roofs, is one of only two five-roofed temples in the valley.\n- **Jhingati tile roofs**: small terracotta tiles (*jhingati*) laid in overlapping courses on timber, used on Newar temples and houses.\n- **Tile and slate, thatch and straw, wood and mud roofs**: the traditional coverings recorded by the census in rural Nepal.\n\n## Roofing today\n\nThe national census asks about the roof of each house. In 2011 the categories were thatch/straw, galvanized iron, tile/slate, RCC (reinforced cement concrete), wood/planks, mud and other. The 2021 census published a table of households by type of roof (Table 4 of the household results).\n\n## Codes, standards and regulation\n\nNepal's **National Building Code (NBC)** is a series of documents. The seismic design code **NBC 105:2020**, approved by the Council of Ministers in 2020, replaced NBC 105:1994 and sets earthquake-resistant design requirements based on a seismic hazard assessment of the country, with values that vary by location. Before its revision, designers had for many years relied heavily on the Indian code. The Ministry of Urban Development is responsible for the code.\n\n## Notable roofs\n\n- **Kathmandu Valley World Heritage Site**: seven monument zones, including the Durbar Squares of Hanuman Dhoka (Kathmandu), Patan and Bhaktapur, Swayambhu, Bauddhanath, Pashupati and Changu Narayan.\n- **Nyatapola Temple, Bhaktapur**: five-roofed pagoda built for King Bhupatindra Malla, about 30 m (100 ft) high; it survived the 1934 and 2015 earthquakes.\n\n## Local roofing terms\n\n- *jhingati* (Newar): small terracotta roof tile\n- *tundal* (Newar): carved wooden bracket or strut\n\n## Sources and gaps\n\nNational census shares of roof materials and detailed accounts of mountain slate and stone roofs, the roofing industry and roofing standards: published information is limited.","key_facts":[{"label":"Census roof categories","value":"Thatch/straw, galvanized iron, tile/slate, RCC, wood/planks, mud"},{"label":"Traditional materials","value":"Terracotta tile (jhingati), slate, thatch, timber, earth"},{"label":"Climate driver","value":"Monsoon rain, Himalayan snow, earthquakes"},{"label":"Building code","value":"National Building Code; seismic NBC 105:2020"},{"label":"Landmark","value":"Kathmandu Valley World Heritage Site"},{"label":"Tallest pagoda","value":"Nyatapola, Bhaktapur (1702), five roofs"}],"regions":["South Asia"],"aliases":["Nepalese roofing","roofs of Nepal"],"related":["newar-pagoda-roof","pagoda-roof","clay-roof-tile","natural-slate","stone-slate","thatch","corrugated-iron","earthquake-roofing","kath-kuni","bhutanese-shingle-roof","roofing-in-india","roofing-in-bhutan","roofing-in-china"],"company":null,"sources":[{"title":"Kathmandu Valley","url":"https://whc.unesco.org/en/list/121/","publisher":"UNESCO World Heritage Centre"},{"title":"Newar architecture","url":"https://en.wikipedia.org/wiki/Newar_architecture","publisher":"Wikipedia"},{"title":"Nyatapola","url":"https://en.wikipedia.org/wiki/Nyatapola","publisher":"Wikipedia"},{"title":"National Population and Housing Census 2011: Type of roof of the house (H023)","url":"https://microdata.nsonepal.gov.np/index.php/catalog/54/variable/F2/V18?name=H023","publisher":"National Statistics Office, Nepal"},{"title":"National Population and Housing Census 2021: household data","url":"https://data.nsonepal.gov.np/dataset/national-population-and-housing-census-2021-household","publisher":"National Statistics Office, Nepal"},{"title":"Government updates National Building Code","url":"https://thehimalayantimes.com/kathmandu/government-updates-national-building-code","publisher":"The Himalayan Times"}]},{"slug":"roofing-in-new-zealand","title":"Roofing in New Zealand","category":"world-roofing","type":"place","country":{"name":"New Zealand","iso2":"NZ"},"summary":"New Zealand roofing: Māori lashed timber and thatch, colonial raupō, shakes and iron, then profiled steel, tiles and post-leaky-building rules.","body":"New Zealand is a country of light timber houses built for a temperate, often wet and windy climate and frequent earthquakes. Māori buildings were lashed timber frames thatched with plant materials; colonial settlers moved from raupō thatch and timber shakes to corrugated iron within a few decades; and pre-painted profiled steel is now the most common roof on new houses.\n\n## Climate and hazards\n\nRainfall is high in many regions and winds are strong, especially in places such as Wellington, so fixing schedules and flashings matter. Light roofs are favoured partly because they reduce earthquake forces. Coastal sites expose roofs to salt spray, making coating durability and fastener corrosion resistance important, and southern and alpine areas add snow load.\n\n## Roofing history\n\n**Māori building.** Before European contact Māori had no nails and wove or lashed their buildings together from forest and swamp materials. Timber was used for posts, ridge poles and outer walls, tree-fern slabs for walls, and roofs were thatched with rushes, bark or toetoe tied to battens, often of mānuka. In the *whare*, the roof and walls extended forward to form a porch, a form still seen in the [wharenui](/wharenui), whose ridge beam, rafters and bargeboards represent the body of an ancestor. Framing members were bound with lashings (*mīmiro*); after steel tools arrived, meeting houses grew larger from the 1840s and nails gradually entered the woodwork.\n\n**Raupō and early settler houses.** Early settler huts were thatched with raupō, toetoe, flax, fern or tōtara bark. Raupō houses were cheap, quick to build and close to Māori housing, but highly flammable. The [Raupo Houses Ordinance](/raupo-houses-ordinance) of 3 March 1842, New Zealand's first building legislation, allowed the governor to impose an annual £20 tax on thatched or raupō buildings in towns. After a fire starting in a raupō bakehouse destroyed about 57 buildings in Wellington in November 1842, the ordinance was applied there in 1843. Even so, an 1849 census of the Auckland area found raupō made up almost a third of European housing; by 1878 only 0.55% of non-Māori dwellings were raupō.\n\n**Shakes, shingles, iron and tile.** Many wooden houses were roofed with split shakes and later sawn shingles, and also with fern fronds, bark sheets, bitumen-coated fabric, canvas or long boards. From the mid-1800s until about 1915, roofs were typically pitched at 30-45 degrees, steeper in the south to shed snow. Iron nails were scarce and costly in the 1840s and 1850s, and cheaper nails from the 1860s changed construction. Wooden shingles were eventually outlawed in towns as a fire hazard and replaced by corrugated iron; slate became more common late in the 19th century, and Marseille-pattern clay tiles, imported from 1899, displaced slate between the 1890s and 1920s. Asbestos-cement sheet was widely used until the 1980s.\n\n**The leaky building crisis.** Many timber-framed homes built between 1988 and 2004 were not weathertight. Contributing factors included face-sealed claddings, untreated radiata pine framing permitted from 1995, and \"Mediterranean\" designs with flat or complex roofs, minimal eaves, parapets and balconies. A 2009 PwC estimate put repairs at about NZ$11.3 billion for 42,000 buildings. See [leaky homes crisis](/leaky-homes-crisis).\n\n## Traditional and vernacular roofs\n\n- **Wharenui** (meeting house): gabled, with a deep porch; *tāhuhu* (ridge beam) and *heke* (rafters) as backbone and ribs.\n- **Whare raupō**: houses thatched with raupō, used by Māori and early settlers.\n- **Colonial cottage**: steep gabled roof in shakes, shingles or iron.\n\n## Roofing today\n\nThe BRANZ New Dwellings Survey for 2022 found that sheet metal covered 64.6% of new houses, tiles (metal and concrete) 25.7% and other materials, mostly shingles and membranes, 9.7%. Common coverings include corrugated and trapezoidal pre-painted steel, [stone-coated steel](/stone-coated-steel) tiles, concrete and clay tiles, and butyl, EPDM, TPO or torch-on bitumen membranes on low-slope roofs.\n\n## Codes, standards and regulation\n\nRoofs must meet the New Zealand Building Code, notably Clause B1 (structure, referencing AS/NZS 1170 loadings) and [Clause E2 External Moisture](/nzbc-e2), whose Acceptable Solution E2/AS1 reached its fourth edition in July 2025. The leaky building crisis led to the Building Act 2004, a return to treated framing under NZS 3602:2003 and much stricter flashing and junction details. Roofing on homes is restricted building work: it must be done or supervised by a Licensed Building Practitioner, whose roofing licence has classes including profiled metal, metal tile, membrane, shingles, torch-on and liquid roofing.\n\n## Industry\n\nNew Zealand Metal Roofing Manufacturers (NZMRM) publishes the [NZ Metal Roof and Wall Cladding Code of Practice](/nz-metal-roof-code-of-practice) (v26.09, September 2026). The [Roofing Association of New Zealand](/roofing-association-of-new-zealand) represents contractors, and BRANZ carries out independent building research.\n\n## Notable roofs\n\nCarved meeting houses on marae across the country hold special significance in Māori culture; the New Zealand Māori Arts and Crafts Institute, established under a 1963 Act, has built or restored more than 40 marae.\n\n## Local roofing terms\n\n- **Tāhuhu**: ridge beam. **Heke**: rafters. **Maihi**: bargeboards.\n- **Raupō**: bulrush used for thatch and walls.\n- **Toetoe**: native grass used for thatch.\n\n## Sources and gaps\n\nThe national census does not publish roof materials; the BRANZ figures cover new houses only.","key_facts":[{"label":"Dominant material today","value":"Sheet metal on 64.6% of new houses (BRANZ, 2022)"},{"label":"Traditional materials","value":"Timber, rushes, bark, toetoe and raupō thatch, lashed without nails"},{"label":"First building law","value":"Raupo Houses Ordinance, 3 March 1842"},{"label":"Leaky building crisis","value":"Homes built 1988-2004; about NZ$11.3 billion (PwC, 2009)"},{"label":"Climate drivers","value":"Wind, rain, earthquakes, coastal salt"},{"label":"Building code","value":"New Zealand Building Code (B1, E2)"}],"regions":["Oceania"],"aliases":["NZ roofing","Aotearoa roofing"],"related":["wharenui","raupo-houses-ordinance","leaky-homes-crisis","nzbc-e2","nz-metal-roof-code-of-practice","new-zealand-metal-roofing-manufacturers","roofing-association-of-new-zealand","corrugated-iron","stone-coated-steel","clay-roof-tile","concrete-roof-tile","thatch","wood-shingle","coastal-corrosion","earthquake-roofing","roofing-in-australia","roofing-in-the-pacific-islands"],"company":null,"sources":[{"title":"Building materials - Māori and early settler materials","url":"https://teara.govt.nz/en/building-materials/page-1","publisher":"Te Ara - The Encyclopedia of New Zealand"},{"title":"Raupo Houses Ordinance","url":"https://en.wikipedia.org/wiki/Raupo_Houses_Ordinance","publisher":"Wikipedia"},{"title":"Slab hut","url":"https://en.wikipedia.org/wiki/Slab_hut","publisher":"Wikipedia"},{"title":"Architecture of New Zealand","url":"https://en.wikipedia.org/wiki/Architecture_of_New_Zealand","publisher":"Wikipedia"},{"title":"Wharenui","url":"https://en.wikipedia.org/wiki/Wharenui","publisher":"Wikipedia"},{"title":"Leaky homes crisis","url":"https://en.wikipedia.org/wiki/Leaky_homes_crisis","publisher":"Wikipedia"},{"title":"SR498 Physical characteristics of new houses 2022","url":"https://www.branz.co.nz/documents/5039/SR498_Physical_characteristics_of_new_houses_2022_FINAL.pdf","publisher":"BRANZ"},{"title":"E2 External moisture","url":"https://www.building.govt.nz/building-code-compliance/e-moisture/e2-external-moisture/","publisher":"Ministry of Business, Innovation and Employment"},{"title":"Roofing licence classes","url":"https://www.lbp.govt.nz/about-lbp/licence-classes/roofing/","publisher":"Licensed Building Practitioners (MBIE)"},{"title":"NZ Metal Roof and Wall Cladding Code of Practice","url":"https://www.metalroofing.org.nz/cop","publisher":"New Zealand Metal Roofing Manufacturers"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Asbestos cement","url":"https://en.wikipedia.org/wiki/Asbestos_cement","publisher":"Wikipedia"}]},{"slug":"roofing-in-nicaragua","title":"Roofing in Nicaragua","category":"world-roofing","type":"place","country":{"name":"Nicaragua","iso2":"NI"},"summary":"Nicaraguan roofing: colonial tile and the vaulted León Cathedral, Caribbean-coast thatch and timber, and metal sheet in a hurricane- and quake-prone country.","body":"Nicaragua lies between the Pacific volcanic chain, where most people live, and a wide, wet Caribbean lowland. Its roofs reflect Spanish colonial building in the Pacific cities, Indigenous and Afro-Caribbean timber and thatch on the Caribbean coast, and widespread use of metal sheet today. Earthquakes and hurricanes have repeatedly shaped how it builds.\n\n## Climate and hazards\n\n- **Earthquakes.** The 1972 earthquake that struck Managua prompted neighbouring Costa Rica to write its first seismic code.\n- **Hurricanes.** Hurricane Mitch in 1998 killed at least 3,800 people in Nicaragua, destroyed 23,900 houses and damaged 17,600.\n- **Heavy rain** on the Caribbean side and a long dry season on the Pacific side.\n\n## Roofing history\n\n**Colonial period.** The ruins of the first Spanish city of León, León Viejo, were inscribed by UNESCO in 2000. The new León and Granada were built with adobe and masonry walls and clay tile roofs. León Cathedral, built from 1747 to the early 19th century to a design by the Guatemalan architect Diego José de Porres Esquivel, has low, thick towers that UNESCO describes as a response to earthquakes. It was inscribed in 2011.\n\n**Caribbean coast.** Garifuna villages along the Caribbean coast traditionally had wooden or wattle-and-daub houses with thatched roofs, the wooden ones raised on posts.\n\n**Modern period.** Corrugated metal sheet, known as *zinc*, became the usual roof for houses.\n\n## Traditional and vernacular roofs\n\n- **Teja on adobe**, the colonial urban house.\n- **Thatch** on Indigenous and Garifuna houses of the Caribbean coast.\n- **Raised timber houses** with metal roofs on the Caribbean side.\n\n## Roofing today\n\nA household table by income quintile published by the Central Bank of Nicaragua with its 2006-2007 results shows about 89.8% of households with zinc roofs, 5.3% with Plycem or Nicalit fibre-cement sheets and 4.2% with clay or cement tiles; concrete slabs, waste materials and thatch made up the small remainder.\n\n## Codes, standards and regulation\n\nA 2012 comparative review listed the *Reglamento Nacional de la Construcción* of 2007 (RNC-07) as Nicaragua's seismic design code.\n\n## Notable roofs\n\n- **León Cathedral** (UNESCO 2011): a large colonial cathedral with an ornamented sanctuary vault and earthquake-resistant low towers.\n- **Ruins of León Viejo** (UNESCO 2000).\n\n## Local roofing terms\n\n- *Zinc*: common name for corrugated metal roofing.\n- *Plycem*, *Nicalit*: brand names used generically for fibre-cement sheets.\n- *Teja*: clay tile.","key_facts":[{"label":"Climate drivers","value":"Earthquakes, hurricanes"},{"label":"Mitch housing losses","value":"23,900 houses destroyed"},{"label":"Seismic code (2012 review)","value":"RNC-07"},{"label":"Heritage roof","value":"León Cathedral, UNESCO 2011"}],"regions":["Latin America"],"aliases":["Nicaraguan roofing"],"related":["clay-roof-tile","spanish-tile","corrugated-iron","palm-thatch","roofing-in-honduras","roofing-in-costa-rica"],"company":null,"sources":[{"title":"León Cathedral","url":"https://whc.unesco.org/en/list/1236","publisher":"UNESCO World Heritage Centre"},{"title":"List of World Heritage Sites in Central America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_Central_America","publisher":"Wikipedia"},{"title":"Cuadro I-3.2: hogares por material del techo, paredes y piso (resultados 2006-2007)","url":"https://bcn.gob.ni/sites/default/files/2006-2007/resultados/nacion/dts_n_vivienda/Cuadro%20I-3.2.pdf","publisher":"Banco Central de Nicaragua"},{"title":"Hurricane Mitch","url":"https://en.wikipedia.org/wiki/Hurricane_Mitch","publisher":"Wikipedia"},{"title":"¿Qué dice el Código Sísmico que protege a Costa Rica de tragedias como la de Venezuela?","url":"https://crhoy.com/nacionales/que-dice-el-codigo-sismico-que-protege-a-costa-rica-de-tragedias-como-la-de-venezuela","publisher":"CR Hoy"},{"title":"Garifuna","url":"https://www.everyculture.com/wc/Afghanistan-to-Bosnia-Herzegovina/Garifuna.html","publisher":"EveryCulture"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-niger","title":"Roofing in Niger","type":"place","country":{"name":"Niger","iso2":"NE"},"summary":"In Niger, flat earth roofs remain among the most common, alongside metal sheet and straw; Agadez is a landmark of Saharan mud-brick building.","body":"Niger is a largely desert and Sahelian country in which earth has always been the main roofing material. Flat roofs of earth on timber cover houses from the Hausa towns of the south to the Saharan city of Agadez, and household survey data show earth roofs still rival metal sheet as the most common roof in the country.\n\n## Climate and hazards\n\nNiger is very hot for most of the year. Rain falls in a short summer season, mostly in the south, and can come in violent storms that erode earth roofs and walls. Sand and dust are constant, and timber for roof joists is scarce. These conditions favour thick, thermally massive earth roofs that can be renewed with local materials.\n\n## Roofing history\n\nAgadez developed in the 15th and 16th centuries, when the Sultanate of Aïr was established, and became a major crossroads of the trans-Saharan caravan trade. Its historic centre, divided into 11 irregular quarters, preserves earthen houses and the Grand Mosque, whose 27 m (89 ft) minaret is often described as the tallest mud-brick structure in the world.\n\nIn the south, Niger shares the Hausa building tradition with northern Nigeria, in which master masons built flat roofs, arches, vaults and domes of earth over short lengths of deleb-palm timber (see Hausa earth vaults and domes). The Hikma complex in Niger is cited as a recent example of contemporary architecture drawing on Hausa forms.\n\n## Traditional and vernacular roofs\n\n- **Flat earth roofs**: timber or palm joists covered with sticks or mats and layers of earth, drained by spouts (see Sahelian earthen roofs).\n- **Hausa domes and vaults**: built without formwork and sealed with a traditional render.\n- **Straw and mat roofs**: lighter roofs of straw or woven mats, recorded as a significant category in national surveys.\n- **Nubian vaults**: since 2000 the association La Voûte Nubienne has promoted timber-free earth-brick vaults in the Sahel as an alternative to metal roofs and scarce timber.\n\n## Roofing today\n\nA national survey on employment and the informal sector carried out by Niger's National Institute of Statistics in 2012 asked households for their main roof material. Unweighted counts in the survey sample (about 30,000 households) were:\n\n| Main roof material | Share of sampled households |\n|---|---|\n| Earth/mud brick | 41.8% |\n| Metal sheet | 30.0% |\n| Straw/mats | 14.3% |\n| Wood | 8.3% |\n| Cement/concrete | 3.2% |\n| Tiles | 0.2% |\n| Animal skin | 0.2% |\n\nThese figures are not official weighted estimates, but they indicate that earth roofs remained the single largest category, with metal sheet second and concrete still rare.\n\n## Codes, standards and regulation\n\nAt Agadez, UNESCO notes that building-permit rules exist but need consistent, educational application, and that a conservation unit for the historic centre still needed staff and resources.\n\n## Notable roofs\n\n- **Historic centre of Agadez**: earth houses and the Grand Mosque with its 27 m mud-brick minaret. About 20,000 people live in the historic centre. UNESCO lists corrugated-iron roofs, breeze-block construction and cement plasters among the inappropriate alterations threatening the site.\n\n## Local roofing terms\n\n- **banco**: wet earth for bricks and plaster, used across the Sahel.\n- **azara** (Hausa): deleb-palm timber for roof joists and arches.\n\n## Sources and gaps\n\nRoof-material data come from one 2012 survey sample and are unweighted. Information on building regulation and industry: published information is limited.","key_facts":[{"label":"Most common roof (2012 survey sample)","value":"Earth/mud brick, 41.8%"},{"label":"Second","value":"Metal sheet, 30.0%"},{"label":"Traditional materials","value":"Earth on timber, straw, mats"},{"label":"Climate driver","value":"Extreme heat, short violent rains, sand"},{"label":"Landmark","value":"Agadez Grand Mosque minaret, 27 m"}],"regions":["Africa"],"aliases":["Nigerien roofing","roofing in Niger"],"related":["roofing-in-west-africa","sahelian-earthen-roofs","hausa-earth-vaults-and-domes","nubian-vault","mud-roof","flat-roof","roofing-in-nigeria","roofing-in-mali","roofing-in-burkina-faso"],"sources":[{"title":"Enquête Nationale sur l'Emploi et le Secteur Informel 2012: matériau principal du toit (H3)","url":"https://www.stat-niger.org/anado/index.php/catalog/121/variable/F5/V585?name=H3","publisher":"Institut National de la Statistique du Niger"},{"title":"Historic Centre of Agadez","url":"https://whc.unesco.org/en/list/1268/","publisher":"UNESCO World Heritage Centre"},{"title":"Hausa urban architecture: construction and design in a cosmopolitan African society","url":"https://www.africanhistoryextra.com/p/hausa-urban-architecture-construction","publisher":"African History Extra"},{"title":"Nubian vault","url":"https://en.wikipedia.org/wiki/Nubian_vault","publisher":"Wikipedia"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-nigeria","title":"Roofing in Nigeria","type":"place","country":{"name":"Nigeria","iso2":"NG"},"summary":"Nigerian roofing runs from Hausa earth domes and Yoruba and Igbo thatch to today's near-universal metal sheet, locally called 'zinc', and concrete slabs.","body":"Nigeria, Africa's most populous country, spans the full West African climate gradient, from the semi-arid Sahel in the far north to humid rainforest and mangrove coast in the south. Its traditional roofs reflect that range: flat and domed earth roofs in the Hausa north, and steep thatch over earth walls among the Yoruba, Igbo and other peoples of the south. Today most new roofs are corrugated or profiled metal sheet, almost universally called \"zinc\" in Nigerian English, together with reinforced concrete slabs (\"decking\") on multi-storey buildings.\n\n## Climate and hazards\n\nThe north has a long dry season, intense sun and dusty harmattan winds, with a short, heavy rainy season; earth roofs there must survive a few months of downpours each year. The south receives far more rain over a longer season, which favours steep pitches, wide overhangs and materials that resist rot and termites. Heat gain through thin metal roofs is a concern everywhere.\n\n## Roofing history\n\nEarth building in the region is ancient. Kano's city walls date from the 11th century and its Gidan Rumfa palace from the late 15th century. Yoruba architecture is traced back to roughly the 8th century; early buildings combined earth, timber, palm oil and straw, with roofs of thatched leaves over wood.\n\nIn the Hausa cities of Kano, Zaria and Katsina, guilds of master masons developed sophisticated earth roofs, arches and domes using short lengths of deleb-palm timber (see Hausa earth vaults and domes). The Friday mosque of Zaria, built in the late 1830s or early 1840s by the master builder Mallam Mikhaila, known as Babban Gwani, has a domed roof in six bays; the complex covers about 1,500 m² (16,000 sq ft). A dome in the Kano palace, Soron Inglia, was built as late as 1935.\n\nFrom the 19th century, Lagos was reshaped by returnees from Brazil, Cuba and Trinidad. Their \"Brazilian\" houses introduced masonry, stucco, arched openings and two-storey *sobrados*, with ventilation gaps between the tops of walls and the roof and small garrets at roof level. A brick and tile factory in Lagos helped make brick storey houses affordable. Mission houses used prefabricated timber imported from England.\n\nIn Yoruba areas, roofs that were once leaf thatch over wood later came to be covered with corrugated iron and aluminium, and the same shift to metal sheet took place across the country.\n\n## Traditional and vernacular roofs\n\n- **Hausa (north):** flat earth roofs on *azara* (deleb-palm) joists; cantilevered timber arches and vaults; and domes (*tulluwa*) built without formwork. Domes were sealed with *laso*, a traditional render that stays watertight for about five years, and drained by long eaves (*indororo*) and spouts.\n- **Yoruba (south-west):** rectangular earth-walled rooms around courtyards ringed by verandas. Raffia-palm leaves were the usual thatch near the Atlantic coast; in the drier north, wood was used in place of palm fronds. Some compounds had impluvium courtyards that collected rainwater.\n- **Igbo (south-east):** thatched buildings, some carried on large timber columns, with impluvium houses common in parts of Anambra. Thatch was treated against insects with cow dung and with the plant *nchu anwu* (literally \"mosquito repellent\").\n- **Sukur (Adamawa):** on the hilltop cultural landscape of Sukur, near the Cameroon border, mud-walled houses with thatched roofs are grouped within dry-stone walls. UNESCO notes that the thatched roofs need frequent maintenance and are vulnerable to changes in materials.\n\n## Roofing today\n\nMetal sheet is the default roof in most of the country. In the unweighted 2016-17 Multiple Indicator Cluster Survey (MICS) sample, run by the National Bureau of Statistics, about 34,000 households were recorded as follows:\n\n| Main roof material | Share of sampled households |\n|---|---|\n| Metal, tin, zinc or iron sheets | 78.4% |\n| Thatch, palm leaf or sod | 12.5% |\n| Cement | 1.6% |\n| Palm or bamboo | 1.6% |\n| Calamine or cement fibre | 1.4% |\n| Wood | 1.0% |\n| Roofing shingles | 0.8% |\n| Ceramic tiles | 0.3% |\n\nSurvey records show how the vocabulary works: in the 2018-19 Nigeria Living Standards Survey, households describing \"other\" roofs wrote answers such as \"zinc\", \"zinc sheets\" and \"corrugated iron\", and one described its roof as \"decking (future storey building)\", the common practice of casting a concrete slab that can later carry another floor. The national Demographic and Health Survey (2018) records roof material in categories including metal/zinc, calamine/cement fibre, ceramic tiles, cement and roofing shingles, alongside thatch/palm leaf and mud.\n\nThese are counts in the survey sample rather than official weighted estimates, but they show metal's dominance, with thatch still used by roughly one household in eight.\n\n## Codes, standards and regulation\n\nNigeria's National Building Code was approved by the federal cabinet on 2 August 2006, following a series of fatal building collapses; the housing minister of the time said it was intended to ensure safety, efficiency and quality in buildings.\n\n## Industry\n\nRoofing sheet is sold and roll-formed widely in Nigeria.\n\n## Notable roofs\n\n- **Zaria Friday Mosque** (late 1830s or early 1840s): domed earth roof on 16 piers.\n- **Kano palace (Gidan Rumfa)**: earth vaults and domes, including Soron Inglia (1935).\n- **Sukur Cultural Landscape**: thatched houses in a stone-walled hill settlement, a World Heritage site since 1999.\n- **Afro-Brazilian houses of Lagos**: 19th- and early 20th-century houses in districts such as Popo Aguda and Olowogbowo.\n\n## Local roofing terms\n\n- **zinc** (Nigerian English): corrugated or profiled metal roof sheet, whatever the actual metal.\n- **decking** (Nigerian English): a cast concrete roof slab.\n- **azara** (Hausa): deleb-palm timber used for roof joists and arches.\n- **tulluwa** (Hausa): dome.\n- **laso** (Hausa): traditional waterproof render for roofs.\n- **indororo** (Hausa): projecting roof eaves.\n- **zankwaye** (Hausa): roof pinnacles.\n- **Sarkin Magina** (Hausa): chief of the builders' guild.\n- **afin** (Yoruba): palace.\n\n## Sources and gaps\n\nDetails of individual Nigerian roofing manufacturers and trade associations: published information is limited.\n\nRoof-material shares are unweighted MICS sample counts; official weighted DHS or census tables are not well documented in published sources. As of 2026, the most recent full national census was that of 2006.","key_facts":[{"label":"Dominant material today","value":"Metal sheet (\"zinc\"), 78.4% of MICS 2016-17 households (unweighted)"},{"label":"Traditional materials","value":"Earth on palm timber (north); grass and palm thatch (south)"},{"label":"Climate driver","value":"Short intense rains (north); long wet season (south); heat"},{"label":"Building code","value":"National Building Code, approved 2006"},{"label":"Landmark","value":"Zaria Friday Mosque, c. 1840"}],"regions":["Africa"],"aliases":["Nigerian roofing","roofing in Nigeria"],"related":["roofing-in-west-africa","hausa-earth-vaults-and-domes","sahelian-earthen-roofs","corrugated-iron","thatch","palm-thatch","flat-roof","roofing-in-niger","roofing-in-benin","roofing-in-ghana","corrugated-fibre-cement-sheet"],"sources":[{"title":"Architecture of Nigeria","url":"https://en.wikipedia.org/wiki/Architecture_of_Nigeria","publisher":"Wikipedia"},{"title":"Yoruba architecture","url":"https://en.wikipedia.org/wiki/Yoruba_architecture","publisher":"Wikipedia"},{"title":"Hausa urban architecture: construction and design in a cosmopolitan African society","url":"https://www.africanhistoryextra.com/p/hausa-urban-architecture-construction","publisher":"African History Extra"},{"title":"Sukur Cultural Landscape","url":"https://whc.unesco.org/en/list/938/","publisher":"UNESCO World Heritage Centre"},{"title":"Nigeria acts to curtail building collapses","url":"https://mg.co.za/article/2006-08-03-nigeria-acts-to-curtail-building-collapses","publisher":"Mail & Guardian"},{"title":"Nigeria Living Standards Survey 2018-2019: other roofing material","url":"https://nigerianstat.gov.ng/nada/index.php/catalog/68/datafile/F78/V2707","publisher":"National Bureau of Statistics, Nigeria"},{"title":"MICS/NICS 2016-17: main material of roof (HC4)","url":"https://nigerianstat.gov.ng/nada/index.php/catalog/59/datafile/F11/V1311","publisher":"National Bureau of Statistics, Nigeria"},{"title":"Nigeria DHS 2018: main roof material (hv215)","url":"https://catalog.ihsn.org/catalog/8783/variable/F3/V99?name=hv215","publisher":"IHSN / National Population Commission"},{"title":"Friday Mosque at Zaria","url":"https://archnet.org/sites/4180","publisher":"Archnet"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-north-africa","title":"Roofing in North Africa","type":"place","summary":"Overview of roofing in Morocco, Algeria, Tunisia, Libya and Egypt: flat roof terraces, earth kasbahs, domes and vaults, cedar ceilings and concrete today.","body":"North Africa, the Maghreb and Egypt, is dominated by flat roofs. Low rainfall, strong sun and limited timber favoured flat masonry roofs, roof terraces, domes and vaults, a tradition continued today in reinforced concrete.\n\n## Flat roofs and terraces\n\nFlat roofs are characteristic of Egyptian and Arabian architecture, and in the medinas of the Maghreb houses are typically built around courtyards with flat roof terraces used for drying laundry, storage and sleeping in summer. In colonial Morocco, a 1914 building regulation required the roofs of all buildings in new districts to be flat.\n\n## Earth architecture\n\nIn the pre-Saharan valleys and oases, especially among Amazigh (Berber) communities, *kasbahs* and fortified villages (*ksour*) are typically made of rammed earth, with tall walls tapering toward the top. Their flat roofs are built of timber or palm-trunk joists, layers of reeds or palm fronds, and compacted earth, and need regular maintenance after rain.\n\n## Domes and vaults\n\nDomes and barrel vaults of mud brick, fired brick or stone roof houses, tombs and mosques in parts of the region, notably in southern Tunisia and in Egypt, where the mud-brick Nubian vault originated. The Egyptian architect Hassan Fathy revived the Nubian vault in the 1940s at New Gourna near Luxor.\n\n## Timber roofs and ceilings\n\nIn Morocco, many mosques and mausoleums have sloped wood-frame ceilings (*berchla*), and larger residences have carved and painted wood-panel or reed ceilings. Moroccan cedar was the main timber for ceilings and other elements above eye level, with palm wood occasionally used.\n\n## Today\n\nReinforced concrete frame buildings with flat roofs waterproofed by bituminous membranes or coatings are the norm. Roof terraces remain in everyday use, and rooftop water tanks and satellite dishes are common features of the urban roofscape.\n\n## Climate\n\nIntense sun and high roof temperatures, occasional torrential rain, and earthquakes in the Atlas and northern Algeria shape roof design.","key_facts":[{"label":"Dominant roof","value":"Flat roof terrace"},{"label":"Earth tradition","value":"Rammed-earth kasbahs and ksour"},{"label":"Moroccan regulation","value":"1914 rule requiring flat roofs"},{"label":"Main timber","value":"Moroccan cedar"}],"regions":["Africa","Middle East"],"aliases":["Maghreb roofing","Moroccan roofing","Egyptian roofing"],"related":["flat-roof","nubian-vault","middle-eastern-domes","roofing-in-the-middle-east-and-gulf","rammed-earth"],"sources":[{"title":"Architecture of Morocco","url":"https://en.wikipedia.org/wiki/Architecture_of_Morocco","publisher":"Wikipedia"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"},{"title":"Nubian vault","url":"https://en.wikipedia.org/wiki/Nubian_vault","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-north-korea","title":"Roofing in North Korea","category":"world-roofing","type":"place","country":{"name":"North Korea","iso2":"KP"},"summary":"North Korean roofing shares the Korean giwa tile and choga thatch tradition; modern Pyongyang mixes concrete flat roofs with monumental tiled roofs.","body":"North Korea shares the roofing heritage of the whole Korean peninsula: curved roofs of fired clay tiles (*giwa*) on palaces, temples and elite houses, and rice-straw thatch (*choga*) on ordinary houses. After the Korean War its capital was rebuilt on a monumental scale, and a distinctive state style emerged that places traditional tiled roofs on large modern buildings.\n\n## Climate and hazards\n\nThe north of the peninsula has a continental monsoon climate, with hot, wet summers and long, cold winters that are harsher than in the south, so roofs must handle both heavy summer rain and snow and frost.\n\n## Roofing history\n\n**Ancient.** Mumun-period pit houses on the peninsula had thatched roofs over wattle-and-daub walls. Tile technology, which developed in China under the Western Zhou, reached the peninsula with the Chinese commanderies after 108 BCE. The kingdom of **Goguryeo**, whose later capital was Pyongyang, used patterned roof tiles and ornate bracket systems on its palaces.\n\n**Goryeo.** The Goryeo dynasty (918-1392) ruled from Kaesong, now in North Korea. Its surviving monuments, including palace remains, the Namdae Gate, the Koryo Songgyungwan academy, the Sungyang Sowon school and royal tombs, form the UNESCO World Heritage site of Historic Monuments and Sites in Kaesong.\n\n**Joseon.** As elsewhere in Korea, tiled roofs were used by the upper classes and thatch by most rural households.\n\n**Modern.** Pyongyang was almost completely destroyed during the Korean War (1950-1953) and was rebuilt as a planned capital, with many large buildings added in the 1980s and 1990s.\n\n## Traditional and vernacular roofs\n\n- **Giwa** tiled roofs with curved eaves on palaces, temples and gates.\n- **Choga** rice-straw thatch on rural houses.\n\n## Roofing today\n\nOne strand of official architecture deliberately uses traditional tiled roof designs on modern buildings. Examples include the **Grand People's Study House** and the **People's Palace of Culture** in Pyongyang and the **International Friendship Exhibition Hall** at Myohyang-san. Other landmarks are modernist, such as the pyramid-shaped, 105-storey Ryugyong Hotel, whose construction was halted from 1992 to 2008 and which had still not opened by the mid-2020s.\n\n## Notable roofs\n\n- **Historic Monuments and Sites in Kaesong** (UNESCO) - Goryeo-period monuments.\n- **Grand People's Study House**, Pyongyang - monumental building with traditional tiled roofs.\n- **International Friendship Exhibition Hall**, Myohyang-san - tiled roofs in traditional style.\n\n## Local roofing terms\n\nThe Korean terms are shared with the south: *giwa* (tile), *choga* (thatch), *cheoma* (eaves).\n\n## Sources and gaps\n\nInformation on present-day housing and roofing practice, the roofing materials of ordinary housing and industrial buildings, building regulation, housing statistics and industry was not found in reliable published sources.","key_facts":[{"label":"Traditional coverings","value":"Giwa (clay tile), choga (thatch)"},{"label":"Historic capital","value":"Kaesong (Goryeo, 918-1392)"},{"label":"Modern state style","value":"Traditional tiled roofs on modern buildings"},{"label":"Data availability","value":"Very limited"}],"regions":["East Asia"],"aliases":["Roofing in the Democratic People's Republic of Korea","roofing in DPRK"],"related":["roofing-in-south-korea","korean-giwa-history","hanok-roof","choga","roofing-in-china","clay-roof-tile","thatch"],"company":null,"sources":[{"title":"Architecture of North Korea","url":"https://en.wikipedia.org/wiki/Architecture_of_North_Korea","publisher":"Wikipedia"},{"title":"Historic Monuments and Sites in Kaesong","url":"https://whc.unesco.org/en/list/1278","publisher":"UNESCO World Heritage Centre"},{"title":"Korean architecture","url":"https://en.wikipedia.org/wiki/Korean_architecture","publisher":"Wikipedia"},{"title":"Once Upon a Roof: Korean roof tiles","url":"https://asia.si.edu/once-upon-a-roof-gallery","publisher":"Smithsonian National Museum of Asian Art"},{"title":"Choga (architecture)","url":"https://en.wikipedia.org/wiki/Choga_(architecture)","publisher":"Wikipedia"}]},{"slug":"roofing-in-north-macedonia","title":"Roofing in North Macedonia","category":"world-roofing","type":"place","country":{"name":"North Macedonia","iso2":"MK"},"regions":["Europe"],"company":null,"summary":"Roofing in North Macedonia: Byzantine domed churches of Ohrid, Ottoman mosque domes in Skopje, and a building code shaped by the 1963 Skopje earthquake.","aliases":["Macedonian roofing","Roofing in Macedonia"],"body":"North Macedonia's historic roofs are those of Byzantine and medieval churches, especially around Lake Ohrid, and of the Ottoman mosques and town houses of Skopje, Bitola and Tetovo. Its modern building history was transformed by the 1963 Skopje earthquake.\n\n## Climate and hazards\n\nThe country is landlocked with a continental climate and mountain winters. Earthquakes are the critical roof hazard. On 26 July 1963 a magnitude 6.1 earthquake destroyed about 80% of Skopje and killed more than 1,070 people. A year later, international and national experts prepared the first Yugoslav code for construction in seismic regions (1964), and the Japanese architect Kenzo Tange won part of the 1965 competition to replan the city.\n\n## Roofing history\n\n**Late antique and Byzantine.** Early basilicas at Ohrid date from the 4th to early 6th centuries. The town was the capital of the First Bulgarian Empire between 990 and 1015, and most surviving churches were built by Byzantine and Bulgarian patrons, with the rest from the brief period of Serbian rule in the late Middle Ages. UNESCO dates the Church of St Sophia in Ohrid to the 11th century; it is cited as an example of the fashion for subsidiary domes on drums. A legend reported by the 17th-century traveller Evliya Çelebi held that Ohrid had 365 chapels.\n\n**Ottoman.** The Mustafa Pasha Mosque in Skopje (1492) has a square plan and a dome about 16 m (52 ft) across. By the 16th century Ottoman domes were generally covered with lead.\n\n**Modern.** Post-1963 reconstruction of Skopje produced an urban master plan in which Brutalism was prominent.\n\n## Traditional and vernacular roofs\n\nOhrid's 18th- and 19th-century houses are late Ottoman in style with local influences and stand on a very narrow street network; several houses are museums, including the Robevi family house.\n\n## Codes, standards and regulation\n\nThe 1964 Yugoslav seismic code was the starting point for modern seismic design.\n\n## Notable roofs\n\n- Churches of Ohrid, part of the UNESCO site Natural and Cultural Heritage of the Ohrid region (cultural listing 1980, extended to Albania in 2019)\n- Mustafa Pasha Mosque, Skopje (1492)\n\n## Sources and gaps\n\nDetailed descriptions of the roof coverings of historic buildings, information on vernacular roof materials, current roofing materials and modern practice, current national regulations and information on domestic roofing manufacturers were not found in published sources.","key_facts":[{"label":"Seismic hazard","value":"High (1963 Skopje earthquake, Mw 6.1)"},{"label":"Seismic code","value":"First Yugoslav seismic code, 1964"},{"label":"Landmark dome","value":"Mustafa Pasha Mosque, about 16 m (52 ft)"}],"related":["ottoman-domes-in-the-balkans","dome","roofing-in-albania","roofing-in-greece","roofing-in-serbia","roofing-in-kosovo","roofing-in-bulgaria"],"sources":[{"title":"1963 Skopje earthquake","url":"https://en.wikipedia.org/wiki/1963_Skopje_earthquake","publisher":"Wikipedia"},{"title":"Natural and Cultural Heritage of the Ohrid region","url":"https://whc.unesco.org/en/list/99","publisher":"UNESCO World Heritage Centre"},{"title":"Ohrid","url":"https://en.wikipedia.org/wiki/Ohrid","publisher":"Wikipedia"},{"title":"Architecture of North Macedonia","url":"https://en.wikipedia.org/wiki/Architecture_of_North_Macedonia","publisher":"Wikipedia"},{"title":"Byzantine architecture","url":"https://en.wikipedia.org/wiki/Byzantine_architecture","publisher":"Wikipedia"},{"title":"Ottoman architecture","url":"https://en.wikipedia.org/wiki/Ottoman_architecture","publisher":"Wikipedia"}]},{"slug":"roofing-in-norway","title":"Roofing in Norway","category":"world-roofing","type":"place","country":{"name":"Norway","iso2":"NO"},"summary":"Norwegian roofing: birch-bark and turf roofs, tarred stave-church shingles, phyllite slate and today's tile, steel and membranes, built for snow, rain and wind.","body":"Norway's roofs have been shaped by a long, wet coastline, cold inland winters and an abundance of timber and stone. For most of its history the ordinary Norwegian house was a log building roofed with layers of birch bark held down by turf, while churches carried steep, tarred wooden shingles. From the 19th century, clay tiles, local slate and later sheet metal replaced turf in most of the country, but the turf roof never disappeared and is still built on cabins today.\n\n## Climate and hazards\n\nRoofs must cope with heavy precipitation on the western coast, deep snow and frost inland and in the north, and strong winds along exposed shores. The long survival of medieval timber churches is credited to design that kept water off the structure: steep pitches that shed rain and snow, generous overhangs and wood-tar coatings. Turf roofs were designed to carry their own weight of roughly 250 kg/m² (about 51 lb/ft²), which could rise to 400-500 kg/m² (82-102 lb/ft²) with winter snow.\n\n## Roofing history\n\nThe oldest known dwellings were turf huts with a roughly circular plan in which roof and walls formed a single element of paired rafters meeting at a ridge, probably covered with hides over wooden poles. By about 1800 BC larger rectangular houses of about 70 m² (750 ft²) were being built at Gressbakken in the far north, though archaeologists are unsure whether their rafters rested on the stone-and-peat walls or on posts. Iron Age longhouses used rows of roof-bearing posts that divided the interior into three aisles.\n\nScandinavian roofs have probably been covered with birch bark and turf since prehistory. In the Viking Age and the Middle Ages most houses had turf roofs, while churches and buildings with steeper roofs were covered with boards, wooden shingles or lead. At least 250 wooden houses from before the Black Death (about 1350) survive, mostly log buildings, alongside the stave churches. Possibly more than 1,000 stave churches were built, mostly in the 12th and 13th centuries; about 150 still stood in the early 19th century, and 28 remain.\n\nStone and slate appeared on high-status buildings. A document by Bishop Arne from 1308 suggests that King Haakon's Hall in Bergen, built from the mid-13th century, was roofed with slate from Jondal in Hardanger, and evidence around Trondheim suggests slate was used as a building material from about 1100. In the late 17th century parts of Nidaros Cathedral in Trondheim received slate roofs from Klæbu, replacing wood and lead roofs lost in fires.\n\nFire shaped town building. After the fire of 1624, Christiania (now Oslo) was rebuilt as a fortified town under a building code that prohibited wooden houses. In the countryside turf stayed almost universal until the early 18th century and remained the most common roof on rural log houses until the late 19th century, when clay tiles, already used in towns and on manors, and corrugated iron spread outward. National Romanticism revived interest in turf just as it was disappearing.\n\nIn 1945, about 20,000 homes had been lost in northern Norway, 12,000 of them in Finnmark, and a competition that autumn sought prefabricated houses of up to 60 m² (650 ft²) for the rebuilding.\n\n## Traditional and vernacular roofs\n\n- **Torvtak (turf roof):** sod laid over birch bark on gently sloping roof boards. The bark is the waterproof layer; six layers were considered adequate and up to 16 have been recorded. Turf pieces about 30 cm (12 in) square and 7.5 cm (3 in) thick were laid to a total of about 15 cm (6 in). About 30 years was a normal life before relaying. See torvtak.\n- **Stave church roofs:** steep, stacked roofs of boards and wooden shingles, traditionally coated with wood tar. Urnes, built in the 12th and 13th centuries, has roof frames lined with boards and covered with shingles. See stave church roofs.\n- **Slate:** phyllite slate from quarries such as those around Klæbu and Stjørdal near Trondheim was widely used for local and regional roofing from the 19th century.\n\n## Roofing today\n\nTurf roofs are still widely used on new cabins, now laid over bitumen roofing felt and a dimpled drainage membrane rather than birch bark. Slate is still quarried: 2025 marked 150 years of production of Otta slate in Gudbrandsdalen, and a SINTEF study found older Otta slate roofs and façades still functional, noting that stone can far outlast the 60-year service life assumed in environmental product declarations. Housing form affects roof type: on 1 January 2008, 53.1% of Norway's 2,274,362 dwellings were in detached houses and 21.9% in multi-dwelling buildings.\n\n## Codes, standards and regulation\n\nBuilding work is regulated under the Planning and Building Act and the technical regulations known as TEK17 (byggteknisk forskrift), administered by the Norwegian Building Authority (Direktoratet for byggkvalitet, DiBK), which publishes English translations.\n\n## Industry\n\nNorway has a natural-stone roofing industry centred on phyllite slate, including Otta slate from the Pillarguri area south of Otta in Innlandet.\n\n## Notable roofs\n\n- **Urnes Stave Church**, Luster: a UNESCO World Heritage Site, built in the 12th and 13th centuries using parts of an 11th-century church.\n- **Borgund Stave Church**, Lærdal: the classic tiered shingle-roofed stave church.\n- **Røros**, a UNESCO-listed copper-mining town of about 2,000 wooden one- and two-storey houses, rebuilt after Swedish troops destroyed it in 1679.\n- **Nidaros Cathedral**, Trondheim, with its slate roofs.\n\n## Local roofing terms\n\n- *torvtak* - turf roof\n- *skifer* - slate\n\n## Sources and gaps\n\nA national census of roofing materials, current market shares of tile, steel and membranes, and data on other domestic roofing manufacturers: published information is limited.","key_facts":[{"label":"Traditional roof","value":"Birch bark and turf (torvtak)"},{"label":"Church roofs","value":"Tarred wooden shingles on stave churches"},{"label":"Surviving stave churches","value":"28"},{"label":"Turf roof load","value":"About 250 kg/m² (51 lb/ft²), up to 400-500 kg/m² with snow"},{"label":"Building regulations","value":"TEK17 (DiBK)"}],"regions":["Europe","Arctic"],"aliases":["Norwegian roofing","roofs in Norway"],"related":["torvtak","stave-church-roofs","scandinavian-sod-roofs","roofing-in-scandinavia","birch-bark-roofing","natural-slate","wood-shingle","sod-roof","roofing-in-sweden","roofing-in-the-arctic","snow-load"],"company":null,"sources":[{"title":"Architecture of Norway","url":"https://en.wikipedia.org/wiki/Architecture_of_Norway","publisher":"Wikipedia"},{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"},{"title":"Urnes Stave Church","url":"https://whc.unesco.org/en/list/58","publisher":"UNESCO World Heritage Centre"},{"title":"Røros Mining Town and the Circumference","url":"https://whc.unesco.org/en/list/55","publisher":"UNESCO World Heritage Centre"},{"title":"Making medieval stone architecture: the use of slate in Central Norway","url":"https://per-storemyr.net/2012/08/20/making-medieval-stone-architecture-the-use-of-slate-in-central-norway/","publisher":"Per Storemyr"},{"title":"The properties of slate make it a winner","url":"https://www.sintef.no/en/latest-news/2025/the-properties-of-slate-make-it-a-winner/","publisher":"SINTEF"},{"title":"Building Acts and Regulations (in English)","url":"https://dibk.no/regelverk/Building-Regulations-in-English/","publisher":"Norwegian Building Authority (DiBK)"},{"title":"Number of dwellings, by type of building and county, 1 January 2008","url":"https://www.ssb.no/a/en/static/boligstat_en/tab-2008-06-26-01-en.html","publisher":"Statistics Norway"}]},{"slug":"roofing-in-oman","title":"Roofing in Oman","category":"world-roofing","type":"place","country":{"name":"Oman","iso2":"OM"},"regions":["Middle East"],"company":null,"summary":"Omani roofing: mud-brick forts and villages with flat roofs on palm-log or teak beams, painted ceilings, sarooj, and modern concrete.","aliases":["Omani roofing","Roofs of Oman"],"body":"Oman's historic towns, forts and mountain villages are built of mud brick and stone with flat roofs carried on palm logs or imported timber. The undersides of these roofs, seen as ceilings, were often richly painted. Keeping earth roofs and wall tops intact through the rainy season has been the central conservation challenge at sites such as Bahla Fort.\n\n## Climate and hazards\n\nOman is hot and arid, with rain arriving in short, intense bursts. Earthen structures are vulnerable to rain and to poor site drainage: UNESCO notes that Bahla Fort was decaying rapidly after each rainy season before conservation began. Termites are a concern for roof timbers, which is why teak was favoured.\n\n## Roofing history\n\n**Medieval Bahla.** The Banu Nebhan made Bahla their capital from the 12th to the end of the 15th century. Bahla Fort has walls and towers of unbaked brick on stone foundations.\n\n**Painted ceilings.** Roofs of old Omani houses, mosques and castles were built from palm logs or from local or imported wood, including teak from India and East Africa. Ceiling logs were commonly painted dark brown or red with white patterns, flowers and animals, and sometimes carry the builder's name, the date of construction, poetry or Qur'anic verses. Jabreen Castle near Bahla, built in the late 17th century by Imam Bil'arab bin Sultan al-Yarubi, is known for its ceiling artwork.\n\n**Villages.** Harat Al Seebani in Al Hamra, about 250 km (155 miles) from Muscat, was built about 400 years ago, according to local accounts, of clay bricks and mountain stone; by 2018 it had crumbling roofs and cracked walls.\n\n**Modern.** New buildings are mostly reinforced concrete, as across the Gulf (see roofing-in-the-middle-east-and-gulf).\n\n## Traditional and vernacular roofs\n\n- **Flat earth roofs on timber:** palm-log or teak beams with an earth covering, as across the Gulf (see chandal-roof).\n- **Palm-frond shelters:** arish or barasti structures, part of the shared Gulf tradition (see barasti).\n- **Sarooj:** a cement-like material made by firing discs of soaked mud on stacks of date-palm trunks and crushing the result. It has been used for centuries in Omani and UAE oasis communities, notably for building aflaj (irrigation channels); at Nakhal it is still made and shipped around the Gulf for restoration work. Some sarooj over 25 years old still behaved much like Portland cement.\n\n## Roofing today\n\nFlat reinforced concrete roofs are standard in new construction.\n\n## Industry\n\nTraditional sarooj production continues at Nakhal.\n\n## Notable roofs\n\n- **Bahla Fort** (UNESCO): on the List of World Heritage in Danger from 1988 to 2004. Early-1990s repairs used unsuitable materials; from 1995 conservation used only earth-based materials, including new roofs, courtyard drainage and capping of ruined wall tops to stop collapse.\n- **Jabreen Castle:** late 17th century, painted ceilings.\n- **Bait Al Safah**, Al Hamra: a three-storey living museum of traditional life.\n\n## Local roofing terms\n\n- *sarooj* - fired and crushed mud binder used in aflaj and restoration\n- *falaj* (plural *aflaj*) - irrigation channel\n\n## Sources and gaps\n\nDetailed climate data, national data on roofing materials, information on modern roofing materials, manufacturers and Omani building codes, and accounts of the use of mangrove poles in Omani roofs were not found in published sources.","key_facts":[{"label":"Traditional structure","value":"Mud brick and stone; palm-log or teak roof beams"},{"label":"Decoration","value":"Painted ceiling logs"},{"label":"Traditional binder","value":"Sarooj"},{"label":"Bahla Fort danger listing","value":"1988-2004"},{"label":"Modern","value":"Flat concrete"}],"related":["chandal-roof","barasti","mud-roof","flat-roof","roofing-in-the-united-arab-emirates","roofing-in-yemen","roofing-in-saudi-arabia","roofing-in-iran","roofing-in-the-middle-east-and-gulf"],"sources":[{"title":"Bahla Fort","url":"https://whc.unesco.org/en/list/433","publisher":"UNESCO World Heritage Centre"},{"title":"Historical ceilings seek support","url":"https://www.omanobserver.om/ampArticle/57928","publisher":"Oman Observer"},{"title":"Sarooj Factory, Nakhal, Oman","url":"https://enhg.org/resources/uaeoman/Nakhal_sarooj/sarooj_factory_nakhal.htm","publisher":"Emirates Natural History Group"}]},{"slug":"roofing-in-pakistan","title":"Roofing in Pakistan","category":"world-roofing","type":"place","country":{"name":"Pakistan","iso2":"PK"},"summary":"Pakistani roofs are mostly flat: concrete slabs in cities, and roofs on steel girders, timber or bamboo in villages, in a country of high earthquake risk.","body":"Most roofs in Pakistan are flat. In cities they are mainly reinforced concrete slabs; in towns and villages they are commonly carried on steel girders or on timber and bamboo. The country's distinctive contributions to roofing history include some of the oldest planned cities in the world, in the Indus valley, and the windcatchers that once crowded the roofs of Hyderabad in Sindh.\n\n## Climate and hazards\n\nPakistan spans the hot, arid plains of Sindh and Punjab, where summer temperatures are among the highest in Asia, the monsoon-affected north-east, and the mountain ranges of the north and west with heavy winter snow. Earthquakes are a major hazard: the earthquake of 8 October 2005, of magnitude 7.6, killed more than 70,000 people. According to the World Bank, about two-thirds of the country's building stock is brick masonry and only 8% reinforced concrete, which makes buildings more vulnerable than in countries with similar seismic exposure.\n\n## Roofing history\n\nThe Indus civilisation's mature phase (about 2500-1900 BCE) produced cities such as **Mohenjo-daro** in Sindh, a UNESCO World Heritage Site built largely of brick in the 3rd millennium BCE, and Harappa in Punjab. Houses were of one or two storeys around courtyards, and many had stairs leading to upper courtyards or a second floor; how the roofs themselves were built is not preserved in the ruins.\n\nIn **Hyderabad**, rooftop windcatchers called *mangh* are said in some accounts to go back about 500 years; their decline is linked to the arrival of electricity in the 1920s. In the modern period steel joists (\"girders\" and \"T-irons\"), corrugated cement and iron sheets, and reinforced concrete came into wide use, as the census figures below show.\n\n## Traditional and vernacular roofs\n\n- **Timber and bamboo roofs**: flat roofs carried on timber or bamboo members, the commonest rural type in the census categories.\n- **Girder and T-iron roofs**: flat roofs carried on steel joists spanning between walls, recorded in the census as \"girder/T-iron\".\n- **Mangh windcatchers**: fixed, triangular wind scoops on the roofs of Hyderabad and southern Sindh, facing the south-west sea breeze and fitted with rope-operated shutters.\n\nThe flat earth roofs of neighbouring Afghanistan (see *Roofing in Afghanistan*) are closely related.\n\n## Roofing today\n\nThe 2017 Population and Housing Census tabulated the roof material of owned housing units. In Sindh, which includes Karachi, the shares were:\n\n| Roof material | All Sindh | Rural | Urban |\n|---|---|---|---|\n| Wood/bamboo | 35.7% | 57.0% | 9.6% |\n| Girder/T-iron | 33.0% | 33.1% | 32.8% |\n| RCC/RBC (reinforced concrete or brick) | 22.4% | 3.0% | 46.3% |\n| Cement or iron sheet | 6.9% | 4.3% | 10.1% |\n| Other | 2.1% | 2.7% | 1.3% |\n\nThe figures show the typical pattern: concrete slabs dominate in cities, while rural houses are roofed with timber, bamboo or steel joists under earth. Corrugated cement and iron sheets are widely used for sheds, workshops and low-cost housing.\n\n## Codes, standards and regulation\n\nThe national seismic code is the **Building Code of Pakistan (Seismic Provisions 2007)**, issued by the Ministry of Housing and Works; the Pakistan Engineering Council has since begun work on updating it. Enforcement is weak: local bylaws often do not follow the code.\n\n## Notable roofs\n\n- **Mohenjo-daro**: Bronze Age brick city, a UNESCO World Heritage Site.\n- **Old Hyderabad, Sindh**: known as *Manghan jo Shahar*, the \"city of windcatchers\".\n\n## Local roofing terms\n\n- *mangh* (Sindhi): rooftop windcatcher; also *badigar* in southern Sindh\n- *wado sufo* (Sindhi): main room ventilated by a mangh\n- *girder/T-iron*: census term for roofs on steel joists\n\n## Sources and gaps\n\nDetailed descriptions of how rural earth roofs in Pakistan are layered and maintained, national totals for roof materials and information on the domestic roofing industry were not found in published sources.","key_facts":[{"label":"Dominant material today","value":"Flat roofs of RCC slab, girder/T-iron, or timber/bamboo"},{"label":"Sindh roofs (2017 census)","value":"Wood/bamboo 35.7%, girder/T-iron 33.0%, RCC/RBC 22.4%"},{"label":"Traditional materials","value":"Mud brick, timber, bamboo, earth"},{"label":"Climate driver","value":"Extreme heat, monsoon floods, earthquakes"},{"label":"Building code","value":"Building Code of Pakistan (Seismic Provisions 2007)"},{"label":"Distinctive feature","value":"Mangh windcatchers of Hyderabad, Sindh"}],"regions":["South Asia"],"aliases":["Pakistani roofing","roofs of Pakistan"],"related":["flat-roof","mud-roof","mangh-windcatcher","badgir","earthquake-roofing","corrugated-iron","asbestos-cement-roofing","roofing-in-india","roofing-in-afghanistan","roofing-in-iran","burza-pash-roof","chhatri"],"company":null,"sources":[{"title":"Census 2017, Sindh, Table 39: owned housing units by material used in roofs","url":"https://www.pbs.gov.pk/sites/default/files/population/2017/tables/sindh/Table39p.pdf","publisher":"Pakistan Bureau of Statistics"},{"title":"Back to the Basics: Wind Catchers of Hyderabad","url":"https://www.thefridaytimes.com/2021/07/24/back-to-the-basics-wind-catchers-of-hyderabad/","publisher":"The Friday Times"},{"title":"Building seismic resilience in Pakistan: 15 years after the 2005 earthquake","url":"https://blogs.worldbank.org/en/endpovertyinsouthasia/building-seismic-resilience-pakistan-15-years-after-2005-earthquake","publisher":"World Bank"},{"title":"Seismic design code: Pakistan","url":"https://iisee.kenken.go.jp/net/seismic_design_code/pakistan/pakistan.htm","publisher":"International Institute of Seismology and Earthquake Engineering (IISEE)"},{"title":"Mohenjo-daro","url":"https://whc.unesco.org/en/list/138/","publisher":"UNESCO World Heritage Centre"},{"title":"Harappan architecture","url":"https://en.wikipedia.org/wiki/Harappan_architecture","publisher":"Wikipedia"}]},{"slug":"roofing-in-palau","title":"Roofing in Palau","category":"world-roofing","type":"place","country":{"name":"Palau","iso2":"PW"},"summary":"Palauan roofing: the steep, decorated bai meeting house thatched with pandanus or nipa palm, and modern metal and concrete roofs.","body":"Palau's signature roof belongs to the *bai*, the men's meeting house with a tall, steep gable decorated with painted legends. Traditional bai and houses were tied together with coconut-fibre rope and thatched with pandanus or nipa palm. Most homes today have metal roofs, and about one in six has a concrete roof.\n\n## Climate and hazards\n\nPalau has a hot, wet tropical climate, and the steep pitch of traditional roofs sheds heavy rain.\n\n## Roofing history\n\nPalauan houses were described by early observers as elongated A-frames, and bai followed a similar shape on a larger scale. According to oral history recorded by the Pacific Worlds project, bai were built without nails and tied with rope made from coconut husk fibre, and the traditional thatch was pandanus (*búuk*); nipa palm (*tóechel*) came into use later, and palm fronds (*melóuch*) changed roofing again.\n\nThe Airai Bai on Babeldaob, built around 1890 on a stone platform that had carried earlier bai, measures 20.7 by 6.1 m (68 by 20 ft) and rises to about 12 m (40 ft) at its peak. It was restored in the 1970s and listed on the US National Register of Historic Places in 1976. A bai built in 1907 for the Ethnological Museum in Berlin under ethnologist Augustin Krämer is now displayed at the Humboldt Forum; in summer 2022 a team from Palau led by Patrick Tellei gave it a new roof.\n\n## Traditional and vernacular roofs\n\n- **[Bai](/palauan-bai)**: men's meeting house with a decorated gable and steep thatched roof on a stone platform.\n- **Dwelling houses**: smaller, elongated A-frame houses.\n\n## Roofing today\n\nIn the 2012 mini-census, 818 of 4,926 housing units (16.6%) had concrete roofs and the remaining 83.4% metal, wood or other roofs. About 28% of units had concrete foundations and walls with metal or tile roofs, 28% concrete foundations with metal or wood walls and metal or tile roofs, and 27% stood on stilts with metal or wood walls.\n\n## Codes, standards and regulation\n\nPalau has no national building code and no clear building regulatory authority, according to a recent regional review.\n\n## Notable roofs\n\n- **Airai Bai** (c. 1890), Babeldaob, described as the last traditional bai of its kind.\n- **Palauan bai** at the Humboldt Forum, Berlin (1907, re-roofed 2022).\n\n## Local roofing terms\n\n- **Bai**: meeting house.\n- **Búuk**: pandanus thatch. **Tóechel**: nipa palm. **Melóuch**: palm fronds.\n\n## Sources and gaps\n\nInformation on storm damage to roofs: published information is limited. No domestic roofing manufacturers were identified.\n\nExact thatching methods and the timber species used for bai: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal (with wood/other, 83.4%); concrete 16.6% (2012 mini-census)"},{"label":"Traditional materials","value":"Pandanus (búuk), later nipa palm thatch; coconut-fibre rope"},{"label":"Signature roof","value":"Bai meeting house (Airai Bai, c. 1890)"},{"label":"Building code","value":"None national"}],"regions":["Oceania"],"aliases":["Palauan roofing","Belau roofing"],"related":["palauan-bai","palm-thatch","thatch","corrugated-iron","roofing-in-micronesia","roofing-in-the-philippines","roofing-in-the-pacific-islands"],"company":null,"sources":[{"title":"Airai Bai","url":"https://en.wikipedia.org/wiki/Airai_Bai","publisher":"Wikipedia"},{"title":"Airai: Native Palau","url":"https://www.pacificworlds.com/palau/native/native2.cfm","publisher":"Pacific Worlds"},{"title":"More than a roof over one’s head","url":"https://humboldtforum.org/en/buildings-from-oceania","publisher":"Humboldt Forum"},{"title":"Palau 2012 Census, States, Housing","url":"https://www.pacificweb.org/palau-2012-censusstateshousing/","publisher":"PacificWeb"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-palestine","title":"Roofing in Palestine","category":"world-roofing","type":"place","country":{"name":"Palestine","iso2":"PS"},"regions":["Middle East"],"company":null,"summary":"Palestinian roofing from Neolithic Jericho to the lead-covered timber roof of the Church of the Nativity and modern flat concrete roofs.","aliases":["Palestinian roofing","Roofs of Palestine"],"body":"Palestine contains Jericho, whose archaeological deposits reach back about 12,500 years, and the Church of the Nativity in Bethlehem, whose restored timber-and-lead roof is a well-documented recent heritage roof project.\n\n## Climate and hazards\n\nPalestine has hot, dry summers and a winter rainy season. The region is seismically active: steel connectors were added to the Nativity church's roof trusses for earthquake resistance.\n\n## Roofing history\n\n**Pre-Pottery Neolithic Jericho.** At Tell es-Sultan, archaeological deposits go back to about 10,500 BC and record 29 phases of occupation. By the 9th-8th millennium BC the settlement was a sizeable permanent community protected by a monumental wall with a ditch and a tower, built around 8000 BC. Houses of the Pre-Pottery Neolithic A period were round and semi-subterranean, with stone foundations and mud-brick upper walls; how they were roofed are not well documented in published sources.\n\n**Byzantine and later.** The Church of the Nativity in Bethlehem has a basilica roofed with timber trusses covered in lead sheet. The roof's last major repair before modern times was in 1480, in the Mamluk period.\n\n**Modern.** Flat reinforced concrete roofs, as across the Levant, are standard in new buildings.\n\n## Traditional and vernacular roofs\n\nStone vaults and flat earth roofs are part of the shared Levantine tradition (see flat-roof and mud-roof).\n\n## Notable roofs\n\n- **Church of the Nativity, Bethlehem** (UNESCO, inscribed 2012): placed on the danger list at inscription because of the building's poor state, with rain seeping in through the roof. Restoration began in 2013; the Italian firm Piacenti re-covered the roof with about 1,625 m² (17,500 sq ft) of new lead, replaced about 8% of the trusses with aged timber from Italy and added steel seismic connectors. The site was removed from the danger list in July 2019. See church-of-the-nativity-roof.\n- **Ancient Jericho/Tell es-Sultan** (UNESCO): Neolithic wall and tower.\n\n## Sources and gaps\n\nDetailed climate data, Palestine-specific descriptions of vernacular roof construction, census data on main roofing materials, Palestine-specific data on rooftop solar water heaters, local roofing terms and information on modern materials, codes and industry were not found in published sources.","key_facts":[{"label":"Oldest evidence","value":"Jericho deposits from c. 10,500 BC"},{"label":"Landmark roof","value":"Church of the Nativity, timber trusses and lead"},{"label":"Nativity re-roofing","value":"Begun 2013; c. 1,625 m² new lead"},{"label":"Modern","value":"Flat concrete"}],"related":["church-of-the-nativity-roof","lead-roofing","flat-roof","mud-roof","rooftop-solar-water-heater","roofing-in-israel","roofing-in-jordan","roofing-in-lebanon","prehistoric-shelters-and-early-thatch"],"sources":[{"title":"Ancient Jericho/Tell es-Sultan","url":"https://whc.unesco.org/en/list/1687","publisher":"UNESCO World Heritage Centre"},{"title":"Pre-Pottery Neolithic A","url":"https://en.wikipedia.org/wiki/Pre-Pottery_Neolithic_A","publisher":"Wikipedia"},{"title":"Restoration of Bethlehem's Church of the Nativity uncovers long hidden treasures","url":"https://www.arabnews.com/node/1992436/amp","publisher":"Arab News"},{"title":"Bethlehem church removed from World Heritage in Danger list","url":"https://news.un.org/en/story/2019/07/1041742","publisher":"UN News"}]},{"slug":"roofing-in-panama","title":"Roofing in Panama","category":"world-roofing","type":"place","country":{"name":"Panama","iso2":"PA"},"summary":"Panamanian roofing: colonial tile in the Casco Antiguo, palm and straw thatch in Indigenous comarcas, and metal sheet and concrete in modern homes.","body":"Panama joins Central and South America across a narrow, wet isthmus. Its roofs range from palm thatch in Indigenous territories to the tiled colonial quarter of Panama City and the high-rise concrete of the modern capital. Panama's census still counts palm, straw and *penca* (palm-leaf) roofs as a separate category.\n\n## Climate and hazards\n\n- **Heavy tropical rain** for most of the year, especially on the Caribbean side, with high humidity.\n- **Earthquakes**, mostly in the west and along the margins of the isthmus.\n- **Salt air** on both coasts, which affects metal roofing.\n\n## Roofing history\n\n**Pre-colonial and Indigenous.** Indigenous houses of timber and cane with thatched roofs continue in the comarcas (Indigenous territories), where the census still records palm and straw roofs.\n\n**Colonial.** The colonial Historic District (Casco Antiguo) was inscribed by UNESCO in 1997, and the listing was extended in 2003 to include the ruins of the first city, Panamá Viejo. The Caribbean forts of Portobelo and San Lorenzo were inscribed in 1980. Colonial buildings used masonry walls and clay tile roofs.\n\n**Modern.** Reinforced concrete dominates the modern capital.\n\n## Traditional and vernacular roofs\n\n- **Thatch of palm, straw or *penca*** in the comarcas and rural areas.\n- **Bohío**: a common Spanish Caribbean term for a rural thatched hut (see bohio).\n- **Clay tile** roofs in the Casco Antiguo and older provincial towns.\n\n## Roofing today\n\nThe 2023 census tabulated 1,201,809 occupied private dwellings by predominant roof material, using the categories metal (zinc, aluminium and others), clay tile, other tile, concrete slab, wood, palm/straw/*penca*, and other materials.\n\n## Codes, standards and regulation\n\nA 2012 comparative review listed the *Reglamento Estructural Panameño* of 2004 (REP-2004) as Panama's seismic design code.\n\n## Notable roofs\n\n- **Archaeological Site of Panamá Viejo and Historic District of Panamá** (UNESCO 1997, extended 2003).\n- **Portobelo and San Lorenzo** fortifications (UNESCO 1980).\n\n## Local roofing terms\n\n- *Zinc*: corrugated metal roofing.\n- *Penca*: palm-leaf thatch.\n- *Teja*: clay tile.\n- *Losa*: concrete slab.","key_facts":[{"label":"Occupied dwellings (2023 census)","value":"1,201,809"},{"label":"Traditional materials","value":"Palm, straw and penca thatch; clay tile"},{"label":"Seismic code (2012 review)","value":"REP-2004"},{"label":"Heritage","value":"Panamá Viejo and Historic District, UNESCO 1997 (extended 2003)"}],"regions":["Latin America"],"aliases":["Panamanian roofing"],"related":["bohio","palm-thatch","clay-roof-tile","corrugated-iron","roofing-in-costa-rica","roofing-in-colombia"],"company":null,"sources":[{"title":"Censos 2023, Cuadro 12: Viviendas particulares ocupadas por material predominante en el techo","url":"https://www.inec.gob.pa/archivos/P0289562520231215124114Cuadro%2012.pdf","publisher":"INEC Panamá"},{"title":"List of World Heritage Sites in Central America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_Central_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-papua-new-guinea","title":"Roofing in Papua New Guinea","category":"world-roofing","type":"place","country":{"name":"Papua New Guinea","iso2":"PG"},"summary":"PNG roofing: steep thatch of palm leaf, pandanus or grass on lashed frames, towering Sepik spirit houses, and a shift to metal sheet.","body":"Papua New Guinea has one of the world's most varied traditions of vernacular building, from stilt houses in coastal swamps to Highland houses and the towering ceremonial houses of the Sepik. Most traditional roofs are steep thatch of palm leaf, pandanus or grass on timber and bamboo frames lashed with vine or cane. Corrugated metal is now the most common roof on main dwellings, but thatch remains widespread.\n\n## Climate and hazards\n\nThe climate is tropical and wet, so steep roof pitches that shed heavy rain quickly are a constant feature. The country is seismically active; traditional joinery using mortise and tenon or vine lashing produces frames that can flex in earthquakes and strong winds. Coastal and swamp settlements are raised on posts against flooding.\n\n## Roofing history\n\nReliable dates for early roofing are scarce. What is documented comes largely from ethnography of the 20th century. In the Maprik area of East Sepik, anthropologists Anthony Forge and Donald Tuzin described ceremonial houses built on a triangular plan with no walls and no floor: heavy wall plates slope to the rear on posts sunk about 3 m (10 ft) into the ground, a massive ridge pole is raised at dawn on temporary supports, and a diaphragm of slender bamboo rafters then takes the load so that the ridge sags slightly, giving the house its hunched profile. Anthropologist Brigitta Hauser-Schäublin records that Abelam ceremonial houses reached heights of up to 30 m (about 100 ft) and were built by communal labour without nails, bound with vines and liana ropes.\n\nHaus tambaran have become less common as Christian fundamentalism has spread, and in 1984 the national Parliament House in Port Moresby, opened by Prince Charles on 8 August 1984, adopted the haus tambaran form for its entrance facade, a design also shown on the 50 kina note.\n\n## Traditional and vernacular roofs\n\n- **[Haus tambaran](/haus-tambaran)** (spirit house): Sepik men's ceremonial house with a tall, painted front gable and a ridge that slopes down toward the back, the roof often reaching the ground. The Abelam form (*korambo*) can be about 25 m (82 ft) tall and is thatched with sago palm fronds.\n- **Stilt houses** in coastal and swamp areas, with walls and roofs typically thatched with palm leaves or grass.\n- **Highland houses**, round or oval and partly sunk into the ground for insulation around a central hearth, and large, decorated Mendi men's houses.\n- **Marita**: pandanus-leaf thatch, sewn into roofing panels, described as the most common roofing in the lowlands.\n\n## Roofing today\n\nIn a World Bank high-frequency phone survey of 2020-21, 59.5% of responding households said the main roof of their dwelling was metal and 36% said thatch or palm leaf; wood, bamboo and other materials made up the rest. These are case counts from the survey sample rather than weighted national estimates. Metal roofs dominate towns, while thatch remains common in rural villages, where materials can be gathered and replaced locally.\n\n## Codes, standards and regulation\n\nPNG has no unified national building code. Building is regulated under the Building Act 1971 and building regulations based on Australian standards.\n\n## Notable roofs\n\n- **National Parliament House**, Port Moresby (1984), with a haus tambaran-style gable.\n- **Abelam ceremonial house gable** in the Naturhistorisches Museum Nürnberg, taken down around 1975 and re-erected in Germany; an Abelam cult house replica is also displayed at the Humboldt Forum in Berlin.\n- **Haus tambaran from Apangai**, Maprik District (1984), in the National Museum of Ethnology, Leiden.\n\n## Local roofing terms\n\n- **Haus tambaran** (Tok Pisin): spirit or ceremonial house.\n- **Marita** (Tok Pisin): pandanus-leaf roofing; *wokim marita*, to make roofing; *soim marita*, to sew roofing.\n- **Kunai**: grass used for roof thatch.\n\n## Sources and gaps\n\nNo well-documented date for the arrival of corrugated iron in what is now Papua New Guinea was found in published sources.\n\n Modern manufacturing and on cyclone performance: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal sheet (59.5% of households in a 2020-21 phone survey)"},{"label":"Traditional materials","value":"Sago palm, pandanus and palm-leaf thatch; kunai grass; bamboo; vine lashing"},{"label":"Signature roof","value":"Sepik haus tambaran, up to about 25-30 m tall"},{"label":"Climate drivers","value":"Heavy rain, earthquakes, flooding"},{"label":"Building code","value":"No unified code; Building Act 1971"}],"regions":["Oceania"],"aliases":["PNG roofing","Papua New Guinean roofing"],"related":["haus-tambaran","palm-thatch","sago-palm-thatch","thatch","corrugated-iron","roofing-in-the-solomon-islands","roofing-in-indonesia","roofing-in-australia","roofing-in-the-pacific-islands","earthquake-roofing"],"company":null,"sources":[{"title":"Traditional architecture of Papua New Guinea","url":"https://en.wikipedia.org/wiki/Traditional_architecture_of_Papua_New_Guinea","publisher":"Wikipedia"},{"title":"Haus Tambaran","url":"https://en.wikipedia.org/wiki/Haus_Tambaran","publisher":"Wikipedia"},{"title":"Constructing the Pacific Hut (Austin and Treadwell)","url":"https://interstices.ac.nz/index.php/Interstices/article/download/360/359","publisher":"Interstices"},{"title":"Abelam - Settlements","url":"https://www.everyculture.com/Oceania/Abelam-Settlements.html","publisher":"Countries and Their Cultures"},{"title":"Ceremonial houses of the Abelam, Papua New Guinea (Hauser-Schäublin, 2016)","url":"https://publications.goettingen-research-online.de/handle/2/93823","publisher":"University of Göttingen"},{"title":"Bamboo and Palm Leaf Cathedrals","url":"https://www.museum.de/en/audioguide/65/52/EN/0","publisher":"Naturhistorisches Museum Nürnberg (museum.de)"},{"title":"More than a roof over one’s head","url":"https://humboldtforum.org/en/buildings-from-oceania","publisher":"Humboldt Forum"},{"title":"National Parliament House, Port Moresby","url":"https://en.wikipedia.org/wiki/National_Parliament_House,_Port_Moresby","publisher":"Wikipedia"},{"title":"PNG High Frequency Phone Survey 2020-21, roof material (s9q18)","url":"https://microdata.fao.org/index.php/catalog/2005/variable/V566","publisher":"World Bank / FAO Microdata"},{"title":"Lumusa area village near Kakemale: cutting kunai grass for the roof","url":"https://asiapacific.anu.edu.au/pambu/catalogue/index.php/lumusa-area-village-near-kakemale-house-building-cutting-kunai-grass-for-the-roof-mawa-kale-wearing-the-hat/informationobject/reports","publisher":"Pacific Manuscripts Bureau, ANU"},{"title":"Making roofing (marita)","url":"https://mailman.anu.edu.au/pipermail/mihalic/2003-July/000446.html","publisher":"Mihalic Tok Pisin list, ANU"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-paraguay","title":"Roofing in Paraguay","category":"world-roofing","type":"place","country":{"name":"Paraguay","iso2":"PY"},"summary":"Paraguayan roofing: Guaraní straw roofs replaced by fired clay tile in the Jesuit missions of the 17th-18th centuries, a tradition still visible today.","body":"Paraguay is a landlocked country of subtropical plains, hot and humid in summer. Its best-documented roofing history is that of the Jesuit missions among the Guaraní, which turned from straw to locally made clay tile and left the great ruined churches of Trinidad and Jesús.\n\n## Climate and hazards\n\n- **Heat and humidity**, with heavy summer rain.\n- **Storms and occasional tornadoes**, which UNESCO identifies as the main weathering threat to the mission ruins.\n- **Low seismicity**: a 2012 review of Latin American building codes excluded Paraguay as a low-seismicity country.\n\n## Roofing history\n\n**Guaraní.** The Guaraní lived in small forest communities; groups of 2,000 to 3,000 people gathered around the missions, whose first buildings were roofed with straw.\n\n**Jesuit missions.** Jesuits reached the Guayrá region in 1588 and founded missions from 1609. Archaeological and documentary research on the mission tile workshops, summarised by María Victoria Roca in 2016, shows a shift from straw to tile: historians date the era of churches and Indigenous houses with tile roofs to about 1641 to 1695, tile was adopted partly to protect against fire after raids by slavers from São Paulo, and from 1714 instructions called for remaining straw roofs to be replaced. Between 1722 and 1726 it became the rule that each mission should have its own tile workshop. Clay was trampled by oxen, moulded, dried and fired in kilns holding about 4,000 tiles each. Tiles from San Ignacio Miní, just across the Paraná River in Argentina, measure about 46 to 55 cm (18 to 22 in) long.\n\nIndigenous housing at the missions was built as long arcaded blocks, each about 60 m (200 ft) square, on streets 16 to 18 m (52 to 59 ft) wide. The mission of La Santísima Trinidad de Paraná was founded in the early 18th century, and its stone church, built around 1745, had a dome; it is one of the largest of the mission churches. The church of Jesús de Tavarangue, planned at about 70 by 24 m (230 by 79 ft) with Mudéjar trefoil arches, was still unfinished when the Jesuits were expelled in 1768.\n\n## Traditional and vernacular roofs\n\n- **Teja** (clay tile) roofs on long houses with deep galleries, the type established in the missions.\n- **Straw thatch** on rural houses.\n\n## Notable roofs\n\n- **Jesuit Missions of La Santísima Trinidad de Paraná and Jesús de Tavarangue** (UNESCO 1993). The churches survive as ruins; restoration at Trinidad has continued since 1980.\n\n## Local roofing terms\n\n- *Teja*: clay tile.\n- *Tejería*: tile works.","key_facts":[{"label":"Historic shift","value":"Straw to clay tile in the Jesuit missions, 1640s onward"},{"label":"Tile kilns","value":"About 4,000 tiles per firing"},{"label":"Heritage","value":"Trinidad and Jesús missions, UNESCO 1993"},{"label":"Seismicity","value":"Low"}],"regions":["Latin America"],"aliases":["Paraguayan roofing"],"related":["jesuit-mission-roof-tiles","clay-roof-tile","spanish-tile","thatch","roofing-in-argentina","roofing-in-brazil","roofing-in-bolivia","roofing-in-uruguay"],"company":null,"sources":[{"title":"Jesuit Missions of La Santísima Trinidad de Paraná and Jesús de Tavarangue","url":"https://whc.unesco.org/en/list/648","publisher":"UNESCO World Heritage Centre"},{"title":"Jesuit Missions of La Santísima Trinidad de Paraná and Jesús de Tavarangue","url":"https://en.wikipedia.org/wiki/Jesuit_Missions_of_La_Sant%C3%ADsima_Trinidad_de_Paran%C3%A1_and_Jes%C3%BAs_de_Tavarangue","publisher":"Wikipedia"},{"title":"Arqueología en las Misiones Jesuitas de Guaraníes: las tejas decoradas de la iglesia de Santa Ana","url":"https://cau.iaa.fadu.uba.ar/wp-content/uploads/2019/03/Roca_Tejas-decoradas_SantaAna.pdf","publisher":"Instituto de Arte Americano, FADU-UBA"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-peru","title":"Roofing in Peru","category":"world-roofing","type":"place","country":{"name":"Peru","iso2":"PE"},"summary":"Peruvian roofing: Inca ichu thatch, Uros reed houses, Lima's quincha and earth roofs; today concrete covers 42.8% and metal or fibre-cement 39.2% (2017).","body":"Peru's roofing spans a wide range of conditions: a very dry coastal desert, the high Andes with cold nights and a summer rainy season, and the Amazon rainforest. Its traditions include the grass-thatched stone buildings of the Inca, the reed houses of Lake Titicaca, and the light cane-and-mud *quincha* construction of colonial Lima. Today most homes are roofed with reinforced concrete or with metal and fibre-cement sheet.\n\n## Climate and hazards\n\n- **Earthquakes** along the whole country. Strong earthquakes in the 16th and 17th centuries led Lima's authorities to require lighter upper storeys in 1699, and a 1950 earthquake damaged many historic buildings in Cusco.\n- **Dry coastal desert**, where flat roofs covered with earth or matting have long been practical.\n- **Andean rain and cold**, which call for steep roofs and good insulation, and **Amazonian heavy rain**.\n\n## Roofing history\n\n**Inca.** The Inca state, which flourished from about 1425 to 1532, built fitted-stone walls but roofed most buildings with grass or reed thatch on poles of wood or cane tied with rope. According to the World History Encyclopedia, the poles were secured to the walls by projecting stone pegs, some gable tops had stone rings for tying down the roof, and roofs in wetter areas were pitched at about 60 degrees. Large public halls (*kallanka*) faced onto plazas. The grass most associated with Andean thatch is *ichu* (*Jarava ichu*), whose name is Quechua for straw. Machu Picchu, founded around 1450, and the Inca capital of Cusco were both inscribed by UNESCO in 1983.\n\n**Grass rope.** Quechua communities still rebuild the Q'eswachaka bridge every year from twisted grass, braiding cords about 70 m (230 ft) long into six main cables. UNESCO inscribed the tradition as Intangible Cultural Heritage in 2013.\n\n**Colonial.** In Cusco, the Spanish kept the Inca street plan and built churches and palaces over Inca walls of cut granite and andesite. In Lima, after earthquakes destroyed many two-storey adobe and brick houses, the viceroy Conde de la Monclova ordered in 1699 that upper floors be rebuilt in *quincha*, a timber frame filled with woven cane and mud plaster. Roofs on these buildings had timber rafters nailed to the top beams of the walls, covered with boards and a layer of soil.\n\n**Modern.** In the 20th century corrugated metal sheet, known as *calamina*, and fibre-cement sheet replaced thatch and tile across much of the Andes, while reinforced concrete became the standard roof in cities.\n\n## Traditional and vernacular roofs\n\n- **Ichu thatch** on Andean houses (see Andean ichu thatch).\n- **Uros reed houses** on the floating islands of Lake Titicaca, with walls and roofs of totora reed mats (*kesanas*) on a frame of bamboo or wood.\n- **Quincha** upper storeys with earth-covered roofs in Lima and other coastal towns.\n- **Caña or estera with torta de barro**: cane or reed matting covered with a layer of mud or cement, a flat roof of the dry coast.\n- **Teja** (clay tile) roofs in Andean towns and colonial centres.\n\n## Roofing today\n\nThe 2017 national census (INEI) recorded the predominant roof material of 7,698,900 private dwellings with occupants present:\n\n- Reinforced concrete (*concreto armado*): 42.8%\n- Metal (*calamina*), fibre-cement or similar sheets: 39.2%\n- Clay tile (*tejas*): 7.8%\n- Cane or matting with a mud or cement layer: 3.4%\n- Straw, palm leaves or similar: 2.9%\n- Wood: 2.0%\n- Plywood, matting, reed or other: 1.9%\n\nThe same census found brick or cement block walls in 55.8% of dwellings and adobe or rammed earth (*tapia*) in 27.9%. Concrete roofs predominate in cities, where they allow further storeys to be added, while sheet roofs dominate in the Andes and the Amazon.\n\n## Codes, standards and regulation\n\nPeru's seismic design standard is Norma E.030; a 2012 comparative review of Latin American codes listed the 2003 edition as then in force.\n\n## Notable roofs\n\n- **Machu Picchu** and **Cusco** (UNESCO 1983): Inca gabled stonework that once carried thatch.\n- **Historic Centre of Lima** (UNESCO 1988): adobe ground floors with quincha upper storeys.\n- **Chan Chan Archaeological Zone** (UNESCO 1986).\n- **Q'eswachaka** grass bridge (UNESCO Intangible Cultural Heritage 2013).\n\n## Local roofing terms\n\n- *Calamina*: corrugated metal sheet.\n- *Teja*: clay tile.\n- *Torta de barro*: layer of mud spread on a cane or matting roof.\n- *Estera*: woven reed matting.\n- *Ichu*: Andean bunchgrass used for thatch.\n- *Kesana*: totora reed mat used by the Uros.\n- *Quincha*: cane-and-mud infill in a timber frame.","key_facts":[{"label":"Dominant material today","value":"Reinforced concrete, 42.8% (2017)"},{"label":"Second material","value":"Metal or fibre-cement sheet, 39.2%"},{"label":"Traditional materials","value":"Ichu thatch, totora reed, clay tile, quincha with earth"},{"label":"Climate driver","value":"Earthquakes"},{"label":"Seismic standard","value":"Norma E.030"}],"regions":["Latin America"],"aliases":["Peruvian roofing","techos en el Perú"],"related":["andean-ichu-thatch","uros-totora-houses","quincha","clay-roof-tile","spanish-tile","corrugated-iron","asbestos-cement-roofing","flat-roof","mud-roof","roofing-in-bolivia","roofing-in-ecuador","roofing-in-chile","roofing-in-argentina-and-chile"],"company":null,"sources":[{"title":"En el país existen más de diez millones de viviendas particulares censadas","url":"https://m.inei.gob.pe/prensa/noticias/en-el-pais-existen-mas-de-diez-millones-de-viviendas-particulares-censadas-10893/","publisher":"INEI Perú"},{"title":"Inca Architecture","url":"https://www.worldhistory.org/Inca_Architecture/","publisher":"World History Encyclopedia"},{"title":"Jarava ichu","url":"https://en.wikipedia.org/wiki/Jarava_ichu","publisher":"Wikipedia"},{"title":"Knowledge, skills and rituals related to the annual renewal of the Q'eswachaka bridge","url":"https://ich.unesco.org/en/RL/knowledge-skills-and-rituals-related-to-the-annual-renewal-of-the-qeswachaka-bridge-00594","publisher":"UNESCO Intangible Cultural Heritage"},{"title":"Experimental evaluation of seismic behavior of quincha walls from the Historical Centre of Lima - Peru (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_3170.pdf","publisher":"15th World Conference on Earthquake Engineering"},{"title":"Uros hand made reed floating islands: a proved ancient technique","url":"https://www.irbnet.de/daten/iconda/CIB21650.pdf","publisher":"CIB / IRB (ICONDA)"},{"title":"City of Cuzco","url":"https://whc.unesco.org/en/list/273","publisher":"UNESCO World Heritage Centre"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-poland","title":"Roofing in Poland","category":"world-roofing","type":"place","country":{"name":"Poland","iso2":"PL"},"summary":"Polish roofing: shingled wooden churches, Zakopane-style highland roofs, clay tile, asbestos sheets to remove by 2032, and a market led by metal roofing.","body":"Poland's roofing heritage is strongly linked to timber: steep shingle roofs on Gothic log churches in the south, tiered shingle domes on Eastern-rite tserkvas in the Carpathian borderlands, and the steep shingled roofs of the Zakopane style in the Tatras. In towns, clay tile prevailed, and in the 20th century corrugated asbestos-cement sheet spread over countryside buildings. Today metal roofing is the largest segment of the Polish market, and the country runs a national programme to remove asbestos products by 2032.\n\n## Climate and hazards\n\nPoland has a temperate climate transitional between maritime and continental, with snowy winters, especially in the Carpathians and Sudetes, and summer storms. Snow loads follow Eurocode 1, Part 1-3. Asbestos in old fibre-cement roofs is a long-term health and waste issue.\n\n## Roofing history\n\nAt Biskupin, a fortified settlement of the Lusatian culture, oak for about 102-106 log houses was felled between 747 and 722 BC; each house measured about 8 by 10 m (26 by 33 ft). The settlement has been reconstructed as an open-air museum, though the original roof coverings are not known.\n\nMedieval and early modern churches in southern Poland were built of horizontal logs with very steep shingle roofs. Six of them, at Binarowa, Blizne, Dębno, Haczów, Lipnica Murowana and Sękowa, form the UNESCO site of the Wooden Churches of Southern Małopolska. In the Carpathian borderlands, Orthodox and Greek Catholic communities built log tserkvas between the 16th and 19th centuries, clad in shingles that must be renewed every 20-30 years.\n\nIn the 1890s the painter and architect Stanisław Witkiewicz created the Zakopane style, based on the houses of Podhale highlander villages such as Chochołów. Its first villa, Koliba, was built in 1892, and its buildings have steep shingled roofs, with attics covered by separate roofs. Witkiewicz's chapel at Jaszczurówka (1904-1908) has a shingled gable roof and tall tower.\n\nIn the second half of the 20th century, corrugated asbestos-cement sheet was widely used on houses and farm buildings, and large post-war apartment blocks were built with flat roofs.\n\n## Traditional and vernacular roofs\n\n- **Wooden shingles:** split wooden shingles on churches, belfries, highland houses and farm buildings.\n- **Thatch:** straw and reed on rural houses until the 20th century.\n- **Clay tile:** in towns and on manors, including flat beaver-tail tiles.\n- **Zakopane style:** steep shingled roofs with separately roofed attics.\n\n## Roofing today\n\nA 2024 Spectis study covered in the trade press ranked the Polish roofing market by value as follows: metal roofing (including metal roof tiles, *blachodachówka*) first, bitumen roofing felts second, ceramic tiles third, cement and fibre-cement tiles fourth, synthetic membranes fifth and liquid membranes last. Metal roofing had gained share, mainly in single-family housing. The market was estimated at about PLN 7.7 billion in 2022 and about PLN 6.2 billion in 2023.\n\nThe national asbestos removal programme assumed that about 14.5 million tonnes of asbestos-containing products had to be removed. A 2022 audit by the Supreme Audit Office (NIK) found that less than 17% of inventoried products had been removed in the programme's first 12 years, and a 2010 regulation sets 31 December 2032 as the deadline for withdrawing them from use. See shifer.\n\n## Codes, standards and regulation\n\nConstruction is governed by the Building Law (*Prawo budowlane*) of 7 July 1994, published in the Journal of Laws (Dz.U. 1994, item 414) and amended many times. As an EU member, Poland applies European product standards and the Eurocodes.\n\n## Industry\n\nThe Polish market has many metal roofing producers: of 80 firms analysed in the 2024 Spectis study, 43 offered metal roofing, while ceramic tile production was concentrated in five firms and concrete tile in four.\n\n## Notable roofs\n\n- **Wooden Churches of Southern Małopolska** (UNESCO, 2003). See Wooden Churches of Southern Małopolska.\n- **Wooden Tserkvas of the Carpathian Region** (UNESCO, 2013), eight in Poland, including Kwiatoń, Powroźnik and Smolnik.\n- **Koliba villa** (1892) and **Jaszczurówka chapel** (1904-1908), Zakopane.\n\n## Local roofing terms\n\n- *blachodachówka* - metal roof tile (steel sheet pressed in a tile profile)\n- *papa* - roofing felt\n\n## Sources and gaps\n\nPolish census data on roof materials and information on individual companies were not found in published sources; the market ranking is by sales value, not roof area.","key_facts":[{"label":"Largest market segment","value":"Metal roofing (by value, 2024 study)"},{"label":"Heritage roofs","value":"Shingled wooden churches and tserkvas"},{"label":"Asbestos removal deadline","value":"31 December 2032"},{"label":"Building law","value":"Prawo budowlane (1994)"}],"regions":["Europe"],"aliases":["Polish roofing","roofs in Poland"],"related":["wooden-churches-of-southern-malopolska","wooden-tserkva-roofs","wood-shingle","shifer","metal-roofing","clay-roof-tile","roofing-in-poland-and-eastern-europe","roofing-in-czechia","roofing-in-slovakia","roofing-in-ukraine","roofing-in-germany","roofing-in-lithuania"],"company":null,"sources":[{"title":"Wooden Churches of Southern Małopolska","url":"https://whc.unesco.org/en/list/1053","publisher":"UNESCO World Heritage Centre"},{"title":"Wooden Tserkvas of the Carpathian Region in Poland and Ukraine","url":"https://whc.unesco.org/en/list/1424","publisher":"UNESCO World Heritage Centre"},{"title":"Villas in the Zakopane style, Zakopane","url":"https://visitmalopolska.pl/en/obiekt/-/poi/zakopane-wille-w-stylu-zakopianskim","publisher":"VisitMalopolska"},{"title":"Zakopane Style","url":"https://en.wikipedia.org/wiki/Zakopane_Style","publisher":"Wikipedia"},{"title":"Biskupin","url":"https://en.wikipedia.org/wiki/Biskupin","publisher":"Wikipedia"},{"title":"Rynek pokryć dachowych w Polsce. RAPORT","url":"https://inzynierbudownictwa.pl/rynek-pokryc-dachowych-w-polsce-raport/","publisher":"Inżynier Budownictwa"},{"title":"Masowe usuwanie szkodliwego azbestu potrwa dłużej niż zakładano?","url":"https://kb.pl/dachy/budowa-dachu/masowe-usuwanie-szkodliwego-azbestu-potrwa-dluzej-niz-zakladano-mamy-komentarz-eksperta/","publisher":"KB.pl"},{"title":"Ustawa z dnia 7 lipca 1994 r. – Prawo budowlane (Dz.U. 1994 poz. 414)","url":"https://eli.gov.pl/eli/DU/1994/414","publisher":"Dziennik Ustaw (ELI)"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"}]},{"slug":"roofing-in-poland-and-eastern-europe","title":"Roofing in Poland and Eastern Europe","type":"place","summary":"Overview of roofing in Poland and Eastern Europe: wooden shingle heritage, clay and concrete tile, metal sheet tiles and legacy asbestos-cement sheets.","body":"Eastern and central Europe stretches from the Baltic to the Black Sea and the Carpathians, with cold winters, warm summers and, in mountain areas, heavy snow. Roofing has moved from timber and thatch through clay tile and asbestos-cement sheet to today's market, in which steel sheet roofing in tile profiles is very widespread.\n\n## Timber heritage\n\nWooden shingles were the traditional roof of churches and many houses across the region. UNESCO recognises this heritage in the Wooden Churches of Southern Małopolska in Poland, six Gothic log churches with tall shingled roofs inscribed in 2003, and in the Wooden Tserkvas of the Carpathian Region in Poland and Ukraine, sixteen churches inscribed in 2013. Typical Polish and Slovak split shakes measure about 36 in (90 cm) long, 4-6 in (10-15 cm) wide and 1-1.25 in (2.5-3 cm) thick. Thatch of straw or reed was common on rural houses until the 20th century.\n\n## Clay and concrete tiles\n\nCeramic tiles, including the flat beaver-tail type shared with Germany and various interlocking designs, are traditional in towns. Concrete and ceramic tiles are widely used on new single-family houses.\n\n## Sheet metal\n\nCoated steel roofing sheet pressed to imitate tiles, often called metal tile or \"blachodachówka\" in Poland, is very common on houses throughout the region because it is light and quick to install. Trapezoidal and standing seam steel are used on agricultural and commercial buildings, and copper and zinc-titanium on historic and high-end buildings.\n\n## Asbestos-cement legacy\n\nCorrugated asbestos-cement sheets were widely used on houses and farm buildings in the second half of the 20th century. Asbestos-cement becomes brittle with age and can release dangerous fibres, and many countries in the region now run programmes to remove and replace these roofs.\n\n## Flat roofs\n\nLarge post-war apartment blocks have flat roofs, originally with bituminous felt, which are being renovated with modern membranes and insulation.\n\n## Standards\n\nEU member states use European EN product standards and Eurocode design rules with national annexes.","key_facts":[{"label":"Heritage roofs","value":"Wooden shingles on log churches"},{"label":"UNESCO sites","value":"Southern Małopolska (2003), Carpathian Tserkvas (2013)"},{"label":"Common modern covering","value":"Steel sheet in tile profile"},{"label":"Legacy problem","value":"Asbestos-cement sheets"}],"regions":["Europe"],"aliases":["Polish roofing","Eastern European roofing","Central European roofing"],"related":["wooden-churches-of-southern-malopolska","wood-shingle","roofing-in-russia","roofing-in-germany","asbestos-cement-roofing"],"sources":[{"title":"Wooden Churches of Southern Małopolska","url":"https://whc.unesco.org/en/list/1053","publisher":"UNESCO World Heritage Centre"},{"title":"Wooden Tserkvas of the Carpathian Region in Poland and Ukraine","url":"https://en.wikipedia.org/wiki/Wooden_Tserkvas_of_the_Carpathian_Region_in_Poland_and_Ukraine","publisher":"Wikipedia"},{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Asbestos cement","url":"https://en.wikipedia.org/wiki/Asbestos_cement","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-portugal","title":"Roofing in Portugal","category":"world-roofing","type":"place","country":{"name":"Portugal","iso2":"PT"},"regions":["Europe"],"company":null,"summary":"How Portugal roofs its buildings: low-pitched clay tile roofs almost everywhere, schist and slate in the interior, and flat terraces in the Algarve.","aliases":["Portuguese roofing","Telhados em Portugal","Coberturas em Portugal"],"body":"Portugal's towns are overwhelmingly roofed in fired clay tile, giving them a characteristic terracotta colour. The climate is wetter and more Atlantic in the north and Mediterranean in the south, which shapes roof pitch, eaves and the balance between pitched and flat roofs.\n\n## Climate and hazards\n\nRoofs in the north must shed frequent Atlantic rain, while the Algarve is dry enough for flat roof terraces. Portugal is also seismic: Portuguese rehabilitation guidance recalls the 1969 earthquake when discussing the exposure of chimneys and parapets on old roofs, both of which are vulnerable to shaking. As an EU member, Portugal applies the Eurocodes, including the parts for actions on structures and earthquake resistance.\n\n## Roofing history\n\nBefore Roman rule, the *castro* hillforts of the north-west had round houses with thatched roofs carried on a central wooden post. The Portuguese word *palhoça*, a small wooden cabin with a thatched roof, preserves this tradition in vocabulary. The Romans introduced fired clay tile to the Iberian Peninsula. Medieval churches commonly had timber roofs over their naves, while some Gothic towers were rib-vaulted.\n\nCurved pan-and-cover tiles stayed dominant for centuries. From the late 19th century flatter interlocking tiles, including the Marseille pattern, became common. Portuguese research on old roofs now identifies the *telha Lusa* and *telha Marselha*, together with the curved *telha canudo*, as the main tiles found on traditional Portuguese roofs. Portuguese tile roofing also travelled to Brazil, where the curved *telha colonial* is still common.\n\n## Traditional and vernacular roofs\n\n- **Telha canudo:** the curved channel-and-cover tile, typically 40-45 cm (16-18 in) long, 12-16 cm (4.7-6.3 in) wide and 1.8-2.0 kg, laid at about 27-35 tiles per m².\n- **Telha Lusa:** a larger tile, 40-48 cm (16-19 in) long and 23-30 cm (9-12 in) wide, laid at 10-15 per m²; described in Portuguese research as the most common traditional tile.\n- **Telha Marselha:** the flat interlocking Marseille tile, 40-45 cm (16-18 in) long and about 26 cm (10 in) wide, 11-12 per m².\n- **Beiral and beirado:** the eaves and the roof edge. A distinctive Portuguese detail uses several projecting rows of tiles at the eaves to throw rain clear of the walls; sometimes the eaves have a change of slope.\n- **Timber structures:** roofs are carried on *asnas* (trusses) and *madres* (purlins). A truss has a *linha* (tie beam), *pernas* (rafters), a *pendural* (king post) and *escoras* (struts); battens are *ripas* and the wall plate is the *frechal*. Most old buildings have two-slope roofs, with four slopes on large buildings.\n- **Schist villages:** in mountainous inland areas such as the Serra da Lousã, houses are built of schist and roofed with schist slabs; slate is traditional in parts of the north.\n- **Espigueiros:** raised granaries of northern Portugal, as at Soajo, comparable with Galician hórreos.\n- **Algarve:** whitewashed houses with flat terraces and ornamental chimneys reflect North African influence.\n\n## Roofing today\n\nNew houses typically use ceramic interlocking or curved tiles on timber or concrete structures with underlays and battens, while apartment blocks use waterproofed flat roofs. Rehabilitation of old roofs, especially in historic centres such as Coimbra's Baixa, is a major part of current work.\n\n## Codes, standards and regulation\n\nStructural design follows the Eurocodes, which are adopted across the EU and EFTA.\n\n## Notable roofs\n\n- **Algarve chimneys and terraces**, a distinctive regional roofscape.\n- **Schist villages** of the central interior.\n- **Espigueiros of Soajo**, granaries raised on stone legs with stone or tile roofs.\n\n## Local roofing terms\n\n- *telhado* - roof; *telha* - tile\n- *telha canudo* - curved channel/cover tile\n- *beiral* / *beirado* - eaves / roof edge\n- *asna* - roof truss; *madre* - purlin; *ripa* - batten\n- *caleira* - gutter\n- *espigueiro* - raised granary\n\n## Sources and gaps\n\nSpecific Portuguese regulations on roofs, roof-type census data and manufacturer information: published information is limited.","key_facts":[{"label":"Dominant covering","value":"Fired clay tile"},{"label":"Main traditional tiles","value":"Telha Lusa, telha Marselha, telha canudo"},{"label":"Upland villages","value":"Schist slab roofs"},{"label":"Southern roofs","value":"Flat terraces (Algarve)"},{"label":"Structural design","value":"Eurocodes (EU member)"}],"related":["roofing-in-spain","spanish-mediterranean-terracotta-roof","spanish-tile","interlocking-clay-tile","clay-roof-tile","imbrex-and-tegula","roofing-in-brazil","flat-roof","thatch"],"sources":[{"title":"Architecture of Portugal","url":"https://en.wikipedia.org/wiki/Architecture_of_Portugal","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Reabilitação de Coberturas Antigas (MSc dissertation, R. Barbas, 2015)","url":"https://estudogeral.sib.uc.pt/bitstream/10316/38574/1/Reabilitacao%20de%20coberturas%20antigas.pdf","publisher":"University of Coimbra"},{"title":"Hórreo","url":"https://en.wikipedia.org/wiki/H%C3%B3rreo","publisher":"Wikipedia"},{"title":"Palloza","url":"https://es.wikipedia.org/wiki/Palloza","publisher":"Wikipedia (Spanish)"},{"title":"EN Eurocodes","url":"https://eurocodes.jrc.ec.europa.eu/","publisher":"European Commission Joint Research Centre"}]},{"slug":"roofing-in-puerto-rico","title":"Roofing in Puerto Rico","category":"world-roofing","type":"place","country":{"name":"Puerto Rico","iso2":"PR"},"summary":"Puerto Rican roofing: concrete slabs and zinc sheet over a Taíno and Spanish past; after Hurricane Maria in 2017 nearly 60,000 homes received temporary blue roofs.","body":"Puerto Rico, a US territory, combines a Taíno and Spanish colonial building heritage with US model codes. Most houses are reinforced concrete, but many lighter timber-and-zinc houses, often built informally, were stripped of their roofs by Hurricane Maria in 2017.\n\n## Climate and hazards\n\n- **Hurricanes**: Maria made landfall on 20 September 2017 and left tens of thousands of homes open to the weather.\n- **Earthquakes**: the island is seismically active, and the 2018 codes adopted new seismic design category maps.\n- **Salt air**, which drives corrosion of fasteners, straps and exposed steel.\n\n## Roofing history\n\n**Taíno.** Taíno villages on Puerto Rico (*Borikén*) were among the largest in the Caribbean, with circular thatched family houses (*bohíos*) of poles, woven straw and palm leaves around a central plaza and rectangular chief's houses (*caney*) (see bohio).\n\n**20th century.** Informal construction remained widespread: at a 2018 legislative hearing, officials of the Office of Permit Management (OGPe) said that more than 75,000 informal structures did not meet construction codes.\n\n## Traditional and vernacular roofs\n\n- **Bohío**: palm-thatched rural house.\n\n## Roofing today\n\nHurricane Maria's damage fell heavily on lighter roofs, and the 2018 codes target the connections, fasteners and straps that hold them on.\n\n### Hurricane Maria and the blue roofs\n\nUnder FEMA's Operation Blue Roof, the US Army Corps of Engineers covered damaged roofs with plastic sheeting intended as a temporary repair lasting about 30 days. About 60,000 roofs were needed. Only 439 were installed in the first 30 days; about 30,000 had been completed by 30 December 2017, and the last of 59,469 was installed about six months after the storm. A contract for plastic sheeting was cancelled when the supplier failed to deliver, slowing the start. Months later, thousands of households were still waiting for permanent repairs, and blue tarps became a symbol of the slow recovery.\n\n## Codes, standards and regulation\n\nIn 2018 Puerto Rico replaced its 2011 code with the Puerto Rico Codes 2018, based on the 2018 International Code Council family with local amendments, including the Puerto Rico Building Code and Puerto Rico Residential Code. The update added new wind speed maps, including microzone maps that account for topographic speed-up, new seismic maps, corrosion-resistance requirements for exposed connections, fasteners and metal straps, and rules for rooftop photovoltaic panels (see international-building-code and international-residential-code).\n\n## Local roofing terms\n\n- *Techo de cemento* / *placa*: concrete slab roof.\n- *Techo de zinc*: corrugated metal roof.\n- *Toldo azul*: blue tarp.\n\n## Sources and gaps\n\nNo information on island roofing manufacturers was found in published sources.\n\nIsland-wide shares of roof materials, Spanish colonial roofing and individual heritage roofs: published information is limited.","key_facts":[{"label":"Blue roofs after Maria","value":"59,469 installed by USACE"},{"label":"Building code","value":"Puerto Rico Codes 2018 (2018 I-Codes base)"},{"label":"Climate driver","value":"Hurricanes; earthquakes"}],"regions":["Latin America","North America"],"aliases":["Puerto Rican roofing","Roofing in Borikén"],"related":["international-building-code","international-residential-code","hurricane-roof-damage","bohio","corrugated-iron","flat-roof","roof-coating","roofing-in-the-united-states","roofing-in-the-dominican-republic","roofing-in-the-caribbean"],"company":null,"sources":[{"title":"Corps installs last blue roof in Puerto Rico","url":"https://www.army.mil/article/202599/corps_installs_last_blue_roof_in_puerto_rico","publisher":"U.S. Army"},{"title":"After Maria, thousands on Puerto Rico waited months for a plastic roof","url":"https://www.pbs.org/wgbh/frontline/article/after-maria-thousands-on-puerto-rico-waited-months-for-a-plastic-roof","publisher":"PBS Frontline"},{"title":"Puerto Rico's new building codes are creating a more resilient island","url":"https://www.dewberry.com/news/blog/post/blog/2019/06/27/puerto-ricos-new-building-codes-are-creating-a-more-resilient-island","publisher":"Dewberry"},{"title":"Sobre 75 mil estructuras informales no cumplen con códigos de construcción en P.R.","url":"https://www.metro.pr/noticias/2018/08/22/sobre-75-mil-estructuras-informales-no-cumplen-con-codigos-de-construccion-en-p-r","publisher":"Metro Puerto Rico"},{"title":"Taíno","url":"https://en.wikipedia.org/wiki/Ta%C3%ADno","publisher":"Wikipedia"}]},{"slug":"roofing-in-qatar","title":"Roofing in Qatar","category":"world-roofing","type":"place","country":{"name":"Qatar","iso2":"QA"},"regions":["Middle East"],"company":null,"summary":"Qatari roofing: layered flat roofs of danshil mangrove poles, bamboo or palm mats and clay on coral and limestone walls; GSAS for new buildings.","aliases":["Qatari roofing","Roofs of Qatar"],"body":"Qatar's traditional houses, forts and mosques have flat roofs built in layers on imported mangrove poles, a method documented in detail for Qatar. Qatar also developed the Global Sustainability Assessment System (GSAS), a green building rating system used for its 2022 World Cup stadiums.\n\n## Climate and hazards\n\nQatar's desert climate made flat roofs predominant; traditional design concentrated on shade and ventilation, with wind towers in some towns. Clay roofs and mud bricks were vulnerable to rain and needed regular maintenance.\n\n## Roofing history\n\n**Traditional towns.** Walls were of rough stone bound with clay, later with gypsum mortar and plaster; coral slabs of about 70 x 50 x 7 cm (28 x 20 x 3 in) were used for walls, niches and lintels. Inland Qatar was influenced by the Najdi architecture of central Arabia.\n\n**Forts.** Al Zubara Fort, built in 1938, has traditional wooden ceilings and is part of the UNESCO-listed Al Zubarah site.\n\n**Modern.** Qatar's GSAS, originally named QSAS, was developed in 2007 by the Gulf Organisation for Research and Development (GORD) and is described by its developers as the first performance-based rating system in the Middle East and North Africa.\n\n## Traditional and vernacular roofs\n\n- **Layered flat roof:** *danshil* mangrove poles, imported from East Africa and valued for weather resistance, form the beams; above them are mangrove mats, split bamboo (*baszhil*, from India and East Africa) or palm mats, with palm fronds (*duun*) as an alternative; the whole is covered with clay. Dried palm trunks were also used but carry less load. See chandal-roof.\n- **Mosque galleries:** covered with thin danshil logs or heavier squared timber (*khashab al-murabaa*), often with bamboo or reed lattice ceilings.\n- **Majlis ceilings:** mangrove and palm, often painted with geometric patterns.\n- **Wind towers:** Al Wakrah has more historic wind towers than any other Qatari settlement.\n- **Barasti:** palm or reed shading (see barasti).\n\n## Roofing today\n\nFlat reinforced concrete roofs dominate.\n\n## Codes, standards and regulation\n\n- **GSAS:** an eight-category, lifecycle, performance-based system covering design, construction and operation; a fourth edition was announced in 2019. FIFA endorsed GSAS for Qatar's eight 2022 World Cup stadiums.\n\n## Notable roofs\n\n- **Al Zubarah Archaeological Site** (UNESCO), including Al Zubara Fort (1938) with wooden ceilings.\n- **Ar Rakiyat Fort:** restored in 2022 with a new wooden ceiling in traditional materials.\n- **Al Wakrah:** historic wind towers.\n\n## Local roofing terms\n\n- *danshil* - imported mangrove pole beam\n- *baszhil* - split bamboo laid over the beams\n- *duun* - palm fronds\n- *khashab al-murabaa* - heavier squared timber\n- *badjeer* - ventilation openings\n\n## Sources and gaps\n\nDetailed climate data, data on roofing material shares, information on modern roofing materials, Qatari construction specifications and industry, and details of whether GSAS certification is mandatory for particular building classes or sets roof-specific requirements were not found in published sources.","key_facts":[{"label":"Traditional roof","value":"Danshil poles, bamboo or palm mats, clay"},{"label":"Walls","value":"Coral slabs, limestone, gypsum plaster"},{"label":"Rating system","value":"GSAS (originally QSAS), 2007"},{"label":"Modern","value":"Flat reinforced concrete"}],"related":["chandal-roof","barasti","najdi-mud-roofs","badgir","flat-roof","roofing-in-bahrain","roofing-in-saudi-arabia","roofing-in-the-united-arab-emirates","roofing-in-kuwait","roofing-in-the-middle-east-and-gulf"],"sources":[{"title":"Architecture of Qatar","url":"https://en.wikipedia.org/wiki/Architecture_of_Qatar","publisher":"Wikipedia"},{"title":"Global Sustainability Assessment System","url":"https://en.wikipedia.org/wiki/Global_Sustainability_Assessment_System","publisher":"Wikipedia"},{"title":"Najdi architecture","url":"https://en.wikipedia.org/wiki/Najdi_architecture","publisher":"Wikipedia"}]},{"slug":"roofing-in-romania","title":"Roofing in Romania","category":"world-roofing","type":"place","country":{"name":"Romania","iso2":"RO"},"summary":"Romanian roofing: fir-shingle church spires of Maramureș, reed thatch in the Danube Delta, Saxon tiled roofs with Sibiu's 'eyes', and seismic and snow codes.","body":"Romania's roofs range from the needle-like shingled spires of the Maramureș wooden churches to thick reed thatch in the Danube Delta and the steep tiled roofs of the Transylvanian towns. The country is seismically active and has heavy snowfall in the Carpathians, both reflected in its national design codes.\n\n## Climate and hazards\n\nThe climate is temperate continental, with cold, snowy winters in the mountains and hot summers in the lowlands. Earthquakes are a major structural concern. Snow loads are assessed under code CR 1-1-3/2012, and seismic design under P100-1/2013.\n\n## Roofing history\n\nWooden roofing was dominant for centuries in the forested Carpathians. Builders made roof shingles of fir and fixed them to the laths with wooden pegs of yew. Regional traditions differ in detail: in Maramureș, Moldavia and Wallachia, shingle ends are rounded, while in Transylvania they are cut straight.\n\nIn Moldavia, the painted monasteries built from the second half of the 15th century into the 16th, now on the UNESCO World Heritage List, rely on broad wooden roofs. Voroneț Monastery, built in 1488, has wooden eaves about 2.7 m (9 ft) deep that have sheltered its exterior frescoes for centuries, and its shingles have gently rounded, fan-shaped edges.\n\nIn Maramureș, wooden churches were built from the 17th to the 19th century with massive roofs and tall, slim bell towers at the western end. Almost 100 still stand, about a third of the number two centuries ago. In Sibiu, small eyebrow dormers known as the \"eyes of Sibiu\" ventilate the attics; the earliest date from as early as the 15th century, most were built in the 19th century and a few in the 20th.\n\n## Traditional and vernacular roofs\n\n- **Șindrilă (wooden shingles):** fir shingles pegged with yew, used on churches, houses and farm buildings in the Carpathians. See Maramureș church roofs.\n- **Thatch:** straw and reed were traditional in Maramureș and the Danube Delta, laid 12-16 in (30-40 cm) thick for weatherproofing and insulation, as on houses in Jurilovca in Dobruja.\n- **Eyebrow dormers:** the trapezoid, rounded or elongated attic vents of Sibiu, an element of Baroque architecture.\n\n## Codes, standards and regulation\n\nRomania's design codes include CR 1-1-3/2012, *Cod de proiectare. Evaluarea acțiunii zăpezii asupra construcțiilor* (snow actions on buildings), and P100-1/2013, the code for earthquake-resistant design of buildings issued by the Ministry of Regional Development and Public Administration. As an EU member, Romania also applies the Eurocodes and European product standards.\n\n## Notable roofs\n\n- **Wooden Churches of Maramureș** (UNESCO, 1999): Bârsana, Budești, Desești, Ieud Hill, Plopiș, Poienile Izei, Rogoz and Șurdești. The church at Șurdești is reported to be about 72 m (236 ft) high, and a modern wooden church at Săpânța-Peri about 75 m (246 ft).\n- **Voroneț Monastery** (1488), with its deep wooden eaves.\n- **Sibiu**, with its eyebrow-dormer \"eyes\".\n\n## Local roofing terms\n\n- *șindrilă* - wooden shingle\n- *acoperiș* - roof\n\n## Sources and gaps\n\nMarket data on roofing materials and information on domestic roofing manufacturers: published information is limited. The heights given for the Șurdești and Săpânța-Peri churches come from a trade magazine and are approximate.","key_facts":[{"label":"Traditional covering","value":"Fir shingles (șindrilă), reed and straw thatch"},{"label":"Snow code","value":"CR 1-1-3/2012"},{"label":"Seismic code","value":"P100-1/2013"},{"label":"UNESCO roofs","value":"Wooden Churches of Maramureș (1999)"}],"regions":["Europe"],"aliases":["Romanian roofing","roofs in Romania"],"related":["maramures-church-roofs","wood-shingle","thatch","water-reed-thatch","clay-roof-tile","roofing-in-hungary","roofing-in-moldova","roofing-in-ukraine","roofing-in-bulgaria","wooden-tserkva-roofs"],"company":null,"sources":[{"title":"Wooden churches of Maramureș","url":"https://en.wikipedia.org/wiki/Wooden_churches_of_Maramure%C8%99","publisher":"Wikipedia"},{"title":"Roofing in Romania: Lessons From the Past","url":"https://roofingmagazine.com/roofing-in-romania-lessons-from-the-past/3/","publisher":"Roofing Magazine"},{"title":"Eyes of Sibiu","url":"https://en.wikipedia.org/wiki/Eyes_of_Sibiu","publisher":"Wikipedia"},{"title":"Regulations for Seismic Design – World List: Romania","url":"https://iisee.kenken.go.jp/worldlist/Web/45_Romania.htm","publisher":"International Institute of Seismology and Earthquake Engineering"},{"title":"CR 1-1-3-2012. Cod de proiectare. Evaluarea acțiunii zăpezii asupra construcțiilor","url":"https://www.agir.ro/carte/cr-1-1-3-2012-cod-de-proiectare-evaluarea-actiunii-zapezii-asupra-constructiilor-121665.html","publisher":"AGIR"}]},{"slug":"roofing-in-russia","title":"Roofing in Russia","category":"world-roofing","type":"place","country":{"name":"Russia","iso2":"RU"},"summary":"Russian roofing: timber tent roofs, onion domes clad in aspen shingles, painted sheet iron, Soviet asbestos slate and flat panel-block roofs, and today's metal tile.","body":"Russia's vast territory spans temperate forests, steppe, Siberian permafrost and Arctic coasts, and most of it has long, cold winters with substantial snow. Its roofing tradition grew from timber, producing the tent roof, the barrel roof and the onion dome, often clad in carved aspen shingles. In the 18th and 19th centuries painted sheet iron spread through towns, the Soviet period brought corrugated asbestos-cement \"slate\" (*shifer*) and the flat roofs of mass panel housing, and today steel roofing dominates new low-rise construction.\n\n## Climate and hazards\n\nHeavy snow loads, ice dams at eaves and falling icicles are recurring hazards, and clearing snow from roofs is a routine winter job in many cities. Freeze-thaw cycles and, in the north and east, permafrost add to the demands on roofs and foundations. The national roofing code applies to all of Russia's climatic zones.\n\n## Roofing history\n\nEarly written evidence is sparse, but the early 10th-century writer Ibn Rusta described pitched roofs covered with earth. Birch bark has been used as a waterproofing material since ancient times. Roof coverings ranged over the centuries from wooden boards and shingles to thatch, which was characteristic of the southern regions and gradually spread north, and later iron.\n\nRussian wooden builders developed expressive roof forms for churches. Tent roofs could reach about 18 m (60 ft) and were often crowned with onion domes and crosses; St Nicholas at Lyavla, from the 1580s, is regarded as the oldest surviving tented wooden church. The form was also built in brick, as at the Church of the Ascension at Kolomenskoye (1532). Barrel (*bochka*) and cube-shaped roofs appeared mainly on churches and wealthy houses, decorated with carvings and ploughshare shingles. In the medieval city of Pskov, builders favoured flat roofs covered with planks. In the 17th and 18th centuries church roofs were sometimes painted, often red below and green above.\n\nOnion domes appear on Russian buildings from as early as the 13th century and were most popular in the 17th and 18th centuries; in Russia they are typically timber or metal frames clad in sheet iron, tiles or wooden shingles. Older roofs were built without nails, using concealed timber joints, but nails spread in the 19th century, when iron roofs also became popular. Painted, folded-seam sheet iron became a familiar sight on town houses and manor houses, often in green or red.\n\nAsbestos-cement manufacture began in Russia in 1908 at Bryansk. The chrysotile-cement industry developed most intensively in Russia and the former Soviet republics because of their large asbestos reserves; the chrysotile mine at Asbest in the Urals is often described as the world's largest. Corrugated asbestos-cement sheets became the standard roof for rural houses, dachas and farm buildings.\n\nFrom 1956 to the 1970s, the Soviet Union built prefabricated four- and five-storey apartment blocks, the *khrushchyovka*, mostly of large concrete panels; a few series, such as the brick 1-447, had pitched roofs. Many such blocks are now being replaced: Moscow's 2017 renewal programme targeted 5,171 dilapidated blocks built in 1957-1968.\n\n## Traditional and vernacular roofs\n\n- **Tent roof (*shatyor*):** a tall, steep pyramid over a church's central space.\n- **Barrel roof (*bochka*):** a curved, pointed roof over church volumes and side chapels.\n- **Lemekh:** carved aspen shingles used on domes, barrels and tent roofs. See aspen ploughshare shingles.\n- **Plank and board roofs** on houses and on flatter roof planes, and **thatch** in the south.\n\n## Roofing today\n\nThe market research group Techart estimated that Russia's low-rise housing sector used 261.0 million m² (2.8 billion ft²) of pitched-roofing materials in 2024. Metal roofing made up about 67% of consumption, and metal tile about 76% of metal roofing sales. Bitumen shingles rose from about 11% to 16.5% of the market over four years, and corrugated bitumen sheet from 6% to 8% between 2020 and 2024. Consumption of asbestos-cement slate fell by about 28% over 2020-2024 and is now bought mostly for repairs. Natural tile accounts for only about 0.2% of the market. An earlier Techart study found that more than 85% of Russia's pitched roofs were over 20 years old. Flat roofs on apartment and commercial buildings use bituminous and polymer membranes.\n\n## Codes, standards and regulation\n\nRoof design is governed by the Set of Rules SP 17.13330 \"Roofs\", an updated edition of SNiP II-26-76, issued by the Ministry of Construction. Amendment No. 2 to SP 17.13330.2017 took effect on 30 June 2021, clarifying requirements for roofing materials, metal components, corrugated sheet, seamed metal roofs and drainage.\n\n## Industry\n\nThe chrysotile and asbestos-cement industry, centred historically on Asbest and on plants such as Bryansk, remains active. The roofing market is dominated by steel roofing producers; corrugated bitumen sheet production is almost entirely by one brand, Ondulin, which accounts for 99% of Russian output of that product.\n\n## Notable roofs\n\n- **Kizhi Pogost**, Karelia (UNESCO, 1990): the 22-domed Church of the Transfiguration, built after 1713-1714, and the nine-domed Church of the Intercession (1764).\n- **St Basil's Cathedral**, Moscow, with its onion domes.\n- **Church of the Ascension**, Kolomenskoye (1532), an early masonry tent roof.\n- **St Nicholas Church**, Lyavla (1580s), regarded as the oldest surviving wooden tent-roofed church.\n\n## Local roofing terms\n\n- *shatyor* - tent roof\n- *bochka* - barrel roof\n- *lemekh* - ploughshare shingle\n- *shifer* - corrugated asbestos-cement sheet\n- *metallocherepitsa* - metal tile\n- *kokoshnik* - decorative arched gable stepping up to the drums\n\n## Sources and gaps\n\nThe statistics refer to pitched roofs on low-rise housing; a national census of roof materials are not well documented in published sources.","key_facts":[{"label":"Dominant material today","value":"Metal roofing, about 67% of low-rise pitched roofing (2024)"},{"label":"Traditional forms","value":"Tent roof, barrel roof, onion dome"},{"label":"Asbestos-cement production","value":"Began 1908 in Bryansk"},{"label":"Roof code","value":"SP 17.13330 \"Roofs\""},{"label":"Key load","value":"Snow"}],"regions":["Europe","Arctic"],"aliases":["Russian roofing","roofs in Russia"],"related":["onion-dome","aspen-ploughshare-shingles","shifer","birch-bark-roofing","pyramid-roof","metal-roofing","asbestos-cement-roofing","flat-roof","roofing-in-ukraine","roofing-in-belarus","roofing-in-finland","roofing-in-the-arctic","snow-load","roofing-in-poland-and-eastern-europe"],"company":null,"sources":[{"title":"Architecture of Russia","url":"https://en.wikipedia.org/wiki/Architecture_of_Russia","publisher":"Wikipedia"},{"title":"Russian wooden architecture","url":"https://en.wikipedia.org/wiki/Russian_wooden_architecture","publisher":"Wikipedia"},{"title":"Onion dome","url":"https://en.wikipedia.org/wiki/Onion_dome","publisher":"Wikipedia"},{"title":"Kizhi Pogost","url":"https://en.wikipedia.org/wiki/Kizhi_Pogost","publisher":"Wikipedia"},{"title":"Khrushchyovka","url":"https://en.wikipedia.org/wiki/Khrushchyovka","publisher":"Wikipedia"},{"title":"New technologies and materials are taken into account in the updated Set of Rules 17 \"Roofs\"","url":"https://minstroy.tatarstan.ru/eng/index.htm/news/1978887.htm","publisher":"Ministry of Construction of the Republic of Tatarstan"},{"title":"Roofing materials market (Строительные материалы, оборудование, технологии XXI века, No. 4, 2025)","url":"https://www.techart.ru/files/publications/roofing-materials_pub-2025.pdf","publisher":"Techart marketing group"},{"title":"Russian Roofing Materials Market 2013-2018","url":"https://research.techart.ru/industry/construction/projects/7535/","publisher":"Techart"},{"title":"Construction with Slate – Quick Solution to the Country's Housing Problems","url":"https://vestnik-pp.samgtu.ru/0585-430X/article/view/635982","publisher":"Stroitel'nye Materialy (journal)"},{"title":"Shifer volnovoi: kak pravilno vybrat shifer","url":"https://strgid.ru/en/shifer-volnovoi-kak-pravilno-vybrat-shifer-poleznye-sovety","publisher":"Strgid"},{"title":"Asbest","url":"https://en.wikipedia.org/wiki/Asbest","publisher":"Wikipedia"},{"title":"Church of the Ascension, Kolomenskoye","url":"https://whc.unesco.org/en/list/634","publisher":"UNESCO World Heritage Centre"}]},{"slug":"roofing-in-rwanda","title":"Roofing in Rwanda","category":"world-roofing","type":"place","country":{"name":"Rwanda","iso2":"RW"},"summary":"Rwanda's roofs are iron sheets and locally made clay tiles; grass-thatched nyakatsi houses were removed nationwide in a 2009-2011 government campaign.","body":"Rwanda is a small, densely populated country of steep hills in the African Great Lakes region. For centuries its houses, from farmers' homes to the royal residence, were round, beehive-shaped dwellings of poles and grass thatch. That tradition was ended deliberately: between late 2009 and 2011 the government's campaign against thatched houses (*nyakatsi*) replaced the remaining grass roofs with metal sheets. Today Rwanda is unusual in East Africa for the large share of homes roofed with locally made tiles alongside corrugated iron.\n\n## Climate and hazards\n\nAltitude gives Rwanda a mild climate, but rainfall is high and falls in two main seasons, often in intense thunderstorms with strong winds. Wind uplift of poorly fixed roof sheets, heavy rain and lightning are the main hazards for roofs, and the government has issued ministerial instructions on construction methods to prevent disasters caused by thunderstorms, rain and windstorms.\n\n## Roofing history\n\nThe traditional Rwandan house was a round dwelling under a dome or beehive of grass thatch. A prominent example is the royal residence: the King's Palace Museum at Nyanza includes a reconstruction, in traditional materials, of the 19th-century royal palace as a beehive-shaped thatched dwelling, alongside the palace complex built in 1930-1933 on Rukari hill for the monarchy, which was abolished by referendum in 1961. The capital's ordinary huts were built by the same methods as the royal house.\n\nCorrugated iron spread during the colonial and post-independence periods. By the 2000s, the government treated grass thatch as a mark of poverty and a fire and health risk, leading to the Bye Bye Nyakatsi campaign.\n\n## Traditional and vernacular roofs\n\n- **Nyakatsi**: the grass-thatched house. At the start of the national campaign in December 2009, about 120,000 families still lived in such houses. See Nyakatsi.\n- **Royal beehive palace**: the reconstructed palace at Nyanza is formed of thatched huts with a single beehive-shaped roof.\n- **Adobe and tile houses**: walls of sun-dried adobe block (*rukarakara*) are widely used, and about a quarter of 2022 census sample records were under locally made tiles.\n\n## Roofing today\n\nThe public microdata file of the 2022 Population and Housing Census records the main material of the roof for about 1.31 million records. Unweighted shares of records in that file are:\n\n| Main roof material | Share of records (unweighted) |\n|---|---|\n| Iron sheets | 73.6% |\n| Local tiles | 26.0% |\n| Industrial tiles | 0.2% |\n| Concrete, asbestos, grass and other | under 0.2% combined |\n\nThese are counts in the sample file, not official weighted estimates of households. They show that grass roofs had practically disappeared by 2022, and that roughly a quarter of records were under locally made tiles.\n\n## Codes, standards and regulation\n\nBuilding design and construction are governed by the **Rwanda Building Code** (2019 edition), supplemented by a **Green Building Minimum Compliance System** (2019). Ministerial instructions published through the national Building Permit Management Information System set construction measures against storm, rain and wind damage. The Rwanda Standards Board publishes national standards.\n\n## Industry\n\nThe census distinguishes locally made tiles from industrial tiles, and local tiles were far more common in the 2022 sample. Regional groups including Safal Group list Rwanda among their operating countries.\n\n## Notable roofs\n\n- **King's Palace Museum, Nyanza**: reconstructed royal beehive thatched palace next to the 1930s royal residence on Rukari hill, administered since 2020 by the Rwanda Cultural Heritage Academy.\n\n## Local roofing terms\n\n- *nyakatsi* (Kinyarwanda): a grass-thatched house.\n- *rukarakara* (Kinyarwanda): sun-dried adobe block.\n- *umuganda*: community work day, used to build replacement houses during the anti-thatch campaign.\n\n## Sources and gaps\n\nCensus figures are unweighted record counts from the 2022 public-use sample in the NISR microdata catalogue; an official census table on roofing material are not well documented in published sources. Names and capacities of Rwandan clay-tile and sheet producers are not documented in published sources.","key_facts":[{"label":"Dominant material today","value":"Iron sheets (73.6% of 2022 census sample records, unweighted)"},{"label":"Clay tiles","value":"Local tiles 26.0% of sample records (unweighted)"},{"label":"Traditional roof","value":"Beehive grass thatch (nyakatsi)"},{"label":"Thatch-removal campaign","value":"Bye Bye Nyakatsi, from December 2009"},{"label":"Building code","value":"Rwanda Building Code (2019)"}],"regions":["Africa"],"aliases":["Rwandan roofing","roofs in Rwanda"],"related":["nyakatsi","roofing-in-east-africa","clay-roof-tile","corrugated-iron","thatch","roofing-in-burundi","roofing-in-uganda","roofing-in-tanzania","roofing-in-the-democratic-republic-of-the-congo","mud-roof"],"sources":[{"title":"Rwanda Population and Housing Census 2022: main material used for the roof (h05)","url":"https://microdatabk.statistics.gov.rw/catalog/109/variable/F2/V310?name=h05","publisher":"National Institute of Statistics of Rwanda"},{"title":"King's Palace Museum Rukari","url":"https://en.wikipedia.org/wiki/King%27s_Palace_Museum_Rukari","publisher":"Wikipedia"},{"title":"King's Palace","url":"https://www.visitrwanda.com/interests/kings-palace/","publisher":"Visit Rwanda"},{"title":"Rwanda: 'Bye Bye Nyakatsi' campaign","url":"https://www.ipsnews.net/?p=46195","publisher":"Inter Press Service"},{"title":"Rwanda building code 2019","url":"https://rise.esmap.org/data/files/library/rwanda/Energy Efficiency/Rwanda_building code_2019.pdf","publisher":"ESMAP RISE library"},{"title":"Rwanda Green Building Minimum Compliance System","url":"https://gggi.org/report/rwanda-green-building-minimum-compliance-system/","publisher":"Global Green Growth Institute"},{"title":"Ministerial instructions determining construction modalities of preventing disaster caused by thunderstorms, rain and windstorms","url":"https://www.bpmis.gov.rw/asset_uplds/files/MINISTERIAL%20INSTRUCTIONS%20DETERMINING%20CONSTRUCTION%20MODALITIES%20OF%20PREVENTING%20DISASTER%20CAUSED%20BY%20THUNDERSTORMS%2C%20RAIN%20AND%20WINDSTORMS.pdf","publisher":"Building Permit Management Information System, Rwanda"},{"title":"Best Practice in Adobe Block (Rukarakara) Construction in Rwanda","url":"https://massdesigngroup.org/sites/default/files/file/2022/Best%20Practice%20in%20Adobe%20Block%20%28Rukarakara%29%20Construction%20in%20Rwanda.pdf","publisher":"MASS Design Group"},{"title":"1961 Rwandan monarchy referendum","url":"https://en.wikipedia.org/wiki/1961_Rwandan_monarchy_referendum","publisher":"Wikipedia"}],"company":null},{"slug":"roofing-in-saint-kitts-and-nevis","title":"Roofing in Saint Kitts and Nevis","category":"world-roofing","type":"place","country":{"name":"Saint Kitts and Nevis","iso2":"KN"},"summary":"Kittitian and Nevisian roofing: timber and concrete houses with hip roofs and metal sheet, regulated through the OECS Building Code adapted for the federation.","body":"Saint Kitts and Nevis is a two-island federation in the Leeward Islands. Its building regulation follows the regional OECS model, and roof design is driven by hurricanes.\n\n## Climate and hazards\n\nAs elsewhere in the Eastern Caribbean, hurricanes are the main threat to roofs, with earthquake, volcanic and flood hazards also noted in the OECS code.\n\n## Roofing history\n\nThroughout the Eastern Caribbean, older timber houses typically have steep hip or gable roofs clad first in wooden shingles and later in corrugated iron. Hip roofs, sloping on all four sides, are self-bracing and lack tall gable ends that catch the wind, and slopes of about 35 degrees or more are often preferred in hurricane regions because shallower roofs are more prone to uplift.\n\n## Codes, standards and regulation\n\nThe Organisation of Eastern Caribbean States (OECS) developed model building codes and guidelines for small buildings with support from UNCHS and UNDP, based on the Caribbean Uniform Building Code (CUBiC). The USAID-funded, OAS-executed Caribbean Disaster Mitigation Project helped Antigua and Barbuda, Dominica, Grenada and Saint Lucia prepare national codes from these models, and published construction diagrams covering hip and gable roof framing, rafter-to-ring-beam and wall-plate connections and hurricane straps for houses under 3,000 ft² (279 m²). A revised OECS Building Code was issued in June 2015, reviewed that year for Grenada, Saint Vincent and the Grenadines, Saint Lucia and Montserrat, and drew on the codes of Jamaica and the Cayman Islands. National consultations on administering it were held across the sub-region in 2017 under the EU-funded iLand Resilience project. A stakeholder consultation in Saint Kitts in March 2017 worked on tailoring the code's administrative section to the federation.\n\n## Sources and gaps\n\nPublished accounts of island-specific historic roofing: published information is limited.\n\nRoofing history, material statistics and heritage roofs: published information is limited.","key_facts":[{"label":"Building code","value":"OECS Building Code, localised (consultation 2017)"},{"label":"Climate driver","value":"Hurricanes"}],"regions":["Latin America","North America"],"aliases":["St Kitts roofing","Roofing in St. Kitts and Nevis"],"related":["roofing-in-the-caribbean","hip-roof","corrugated-iron","hurricane-roof-damage","hurricane-tie","chattel-house","roofing-in-antigua-and-barbuda"],"company":null,"sources":[{"title":"Stakeholder consultation on the OECS Building Code","url":"https://sknis.gov.kn/?p=17935","publisher":"SKNIS (St. Kitts and Nevis Information Service)"},{"title":"National Consultation on Revised OECS Building Code Next Week","url":"https://discovermni.com/2017/11/15/national-consultation-on-revised-oecs-building-code-next-week/","publisher":"Discover Montserrat"},{"title":"OECS Building Guidelines: construction diagrams","url":"https://oas.org/pgdm/document/codedraw/intro.htm","publisher":"Organization of American States"},{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"}]},{"slug":"roofing-in-saint-lucia","title":"Roofing in Saint Lucia","category":"world-roofing","type":"place","country":{"name":"Saint Lucia","iso2":"LC"},"summary":"Saint Lucian roofing: steep hip and gable roofs on timber houses, corrugated metal sheet, and building regulation based on the OECS model code.","body":"Saint Lucia is a mountainous volcanic island in the Windward Islands. Like its neighbours it builds for hurricanes, heavy rain and earthquakes, and its building code derives from the Eastern Caribbean model codes.\n\n## Climate and hazards\n\nThe OECS code's preface notes that the Eastern Caribbean islands are frequently hit by hurricanes, that some face earthquake risk and two have volcanic hazards, and that many low-income homes sit in gullies and flood plains exposed to flooding in heavy rain.\n\n## Roofing history\n\nThroughout the Eastern Caribbean, older timber houses typically have steep hip or gable roofs clad first in wooden shingles and later in corrugated iron. Hip roofs, sloping on all four sides, are self-bracing and lack tall gable ends that catch the wind, and slopes of about 35 degrees or more are often preferred in hurricane regions because shallower roofs are more prone to uplift.\n\n## Roofing today\n\nLight metal-sheet roofs on timber framing remain common across the OECS states, with hurricane straps tying rafters to ring beams recommended in regional guidance.\n\n## Codes, standards and regulation\n\nThe Organisation of Eastern Caribbean States (OECS) developed model building codes and guidelines for small buildings with support from UNCHS and UNDP, based on the Caribbean Uniform Building Code (CUBiC). The USAID-funded, OAS-executed Caribbean Disaster Mitigation Project helped Antigua and Barbuda, Dominica, Grenada and Saint Lucia prepare national codes from these models, and published construction diagrams covering hip and gable roof framing, rafter-to-ring-beam and wall-plate connections and hurricane straps for houses under 3,000 ft² (279 m²). A revised OECS Building Code was issued in June 2015, reviewed that year for Grenada, Saint Vincent and the Grenadines, Saint Lucia and Montserrat, and drew on the codes of Jamaica and the Cayman Islands. National consultations on administering it were held across the sub-region in 2017 under the EU-funded iLand Resilience project. Saint Lucia was adapting the OECS code to its own procedures with CDMP help, and the 2015 revision was prepared for Saint Lucia among others.\n\n## Sources and gaps\n\nPublished accounts of historic and Indigenous roofing specific to Saint Lucia: published information is limited. National roof-material statistics were not found in published sources.\n\nIsland-specific roofing history, materials data and the current legal status of the code: published information is limited.","key_facts":[{"label":"Building code","value":"OECS Building Code (2015 revision)"},{"label":"Recommended roof form","value":"Hip roof, about 35° or steeper"},{"label":"Hazards","value":"Hurricanes, earthquakes, volcanic, flooding"}],"regions":["Latin America","North America"],"aliases":["St Lucia roofing","Roofing in St. Lucia"],"related":["roofing-in-the-caribbean","hip-roof","corrugated-iron","hurricane-roof-damage","hurricane-tie","chattel-house","roofing-in-saint-vincent-and-the-grenadines","roofing-in-dominica","roofing-in-barbados"],"company":null,"sources":[{"title":"OECS Building Code (June 2015)","url":"https://oecs.int/en/our-work/knowledge/library/sustainable-energy/oecs-building-codes/oecs-building-code-1-5","publisher":"Organisation of Eastern Caribbean States"},{"title":"Building codes in the Caribbean (CDMP bulletin)","url":"https://oas.org/cdmp/bulletin/codes.htm","publisher":"Organization of American States, Caribbean Disaster Mitigation Project"},{"title":"OECS Building Guidelines: construction diagrams","url":"https://oas.org/pgdm/document/codedraw/intro.htm","publisher":"Organization of American States"},{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"}]},{"slug":"roofing-in-saint-vincent-and-the-grenadines","title":"Roofing in Saint Vincent and the Grenadines","category":"world-roofing","type":"place","country":{"name":"Saint Vincent and the Grenadines","iso2":"VC"},"summary":"Vincentian roofing: metal-sheet hip roofs on timber and concrete houses under the OECS code; Hurricane Beryl in 2024 damaged about 90% of homes on Union Island.","body":"Saint Vincent and the Grenadines combines the volcanic main island of Saint Vincent with a chain of small, low Grenadine islands. Roofs must cope with hurricanes and heavy rain.\n\n## Climate and hazards\n\nOn 2 July 2024 Hurricane Beryl passed through the southern Grenadines. Prime Minister Ralph Gonsalves said roughly nine in ten homes on Union Island were badly damaged or destroyed, and expected similar devastation on Mayreau and Canouan. The OECS code notes that two Eastern Caribbean islands carry volcanic hazards.\n\n## Roofing history\n\nThroughout the Eastern Caribbean, older timber houses typically have steep hip or gable roofs clad first in wooden shingles and later in corrugated iron. Hip roofs, sloping on all four sides, are self-bracing and lack tall gable ends that catch the wind, and slopes of about 35 degrees or more are often preferred in hurricane regions because shallower roofs are more prone to uplift.\n\n## Codes, standards and regulation\n\nThe Organisation of Eastern Caribbean States (OECS) developed model building codes and guidelines for small buildings with support from UNCHS and UNDP, based on the Caribbean Uniform Building Code (CUBiC). The USAID-funded, OAS-executed Caribbean Disaster Mitigation Project helped Antigua and Barbuda, Dominica, Grenada and Saint Lucia prepare national codes from these models, and published construction diagrams covering hip and gable roof framing, rafter-to-ring-beam and wall-plate connections and hurricane straps for houses under 3,000 ft² (279 m²). A revised OECS Building Code was issued in June 2015, reviewed that year for Grenada, Saint Vincent and the Grenadines, Saint Lucia and Montserrat, and drew on the codes of Jamaica and the Cayman Islands. National consultations on administering it were held across the sub-region in 2017 under the EU-funded iLand Resilience project. National consultations on the revised code were held in Saint Vincent in November 2017.\n\n## Sources and gaps\n\nPublished accounts of island-specific historic roofing: published information is limited.\n\nRoofing history, material statistics and the legal status of the code: published information is limited.","key_facts":[{"label":"Building code","value":"OECS Building Code (2015 revision)"},{"label":"Recent hazard","value":"Hurricane Beryl, 2024: ~90% of Union Island homes damaged"}],"regions":["Latin America","North America"],"aliases":["St Vincent roofing","Vincentian roofing"],"related":["roofing-in-the-caribbean","hip-roof","corrugated-iron","hurricane-roof-damage","hurricane-tie","chattel-house","roofing-in-grenada","roofing-in-saint-lucia"],"company":null,"sources":[{"title":"Hurricane Beryl leaves damage strewn across southeast Caribbean islands","url":"https://cbsnews.com/news/hurricane-beryl-damage-southeastern-caribbean-islands","publisher":"CBS News"},{"title":"OECS Building Code (June 2015)","url":"https://oecs.int/en/our-work/knowledge/library/sustainable-energy/oecs-building-codes/oecs-building-code-1-5","publisher":"Organisation of Eastern Caribbean States"},{"title":"National Consultation on Revised OECS Building Code Next Week","url":"https://discovermni.com/2017/11/15/national-consultation-on-revised-oecs-building-code-next-week/","publisher":"Discover Montserrat"},{"title":"OECS Building Guidelines: construction diagrams","url":"https://oas.org/pgdm/document/codedraw/intro.htm","publisher":"Organization of American States"}]},{"slug":"roofing-in-samoa","title":"Roofing in Samoa","category":"world-roofing","type":"place","country":{"name":"Samoa","iso2":"WS"},"summary":"Samoan roofing: the open-sided fale with a domed thatched roof lashed with sennit, now largely roofed with corrugated iron.","body":"Samoa's roofing tradition is built around the *fale*, an open-sided house whose high domed roof rests on timber posts. The frame was lashed without metal fasteners using *ʻafa* (coconut-fibre sennit), and thatched with sugarcane leaves or coconut fronds. Corrugated iron is now the majority roof, but thatch remained on about a fifth of buildings recorded in the 2011 census.\n\n## Climate and hazards\n\nSamoa has a hot, humid tropical climate with heavy rain and lies in the South Pacific cyclone belt. The open fale suits the heat, letting breezes pass beneath a roof that sheds rain and gives shade. Metal roofs are hotter and noisier and corrode quickly near the sea.\n\n## Roofing history\n\nThe classic fale is round or oval with no walls. Before contact with Europeans no metal fasteners were used: the frame was lashed with ʻafa, plaited from dried coconut husk fibre, and an ordinary fale used 30,000-50,000 ft (roughly 9-15 km) of it, traditionally prepared by older men or chiefs (*matai*). Construction was led by master builders, the *tufuga fau fale*, who belonged to an old guild and were engaged through negotiation and customary exchange. Women made the thatch, overlapping it from the eaves upward in a double layer that lasted about seven years.\n\nCorrugated iron later spread widely. Many fale are now rectangular rather than round, and many small beach fale and village cookhouses (*umukuka*) have iron roofs.\n\n## Traditional and vernacular roofs\n\n- **[Fale](/samoan-fale)**: open-sided house with a domed roof on posts.\n- **Fale tele** (\"big house\"): the main, usually round, meeting house of a family compound, used for councils, ceremonies, funerals and the bestowal of chiefly titles.\n- **Pola**: woven coconut-frond blinds hung from the roof frame and lowered against sun, wind or rain.\n\n## Roofing today\n\nIn the 2011 Population and Housing Census data file, 67.6% of buildings with a recorded roof material had corrugated iron, 21.1% thatch, 10.7% a combination of iron and thatch, and 0.4% tarpaulin. These are case counts from the census file rather than published summary tables.\n\n## Codes, standards and regulation\n\nSamoa's national building code dates from 1990 and was updated in 2017; building is regulated under the Ministry of Works Act 2002.\n\n## Notable roofs\n\nThe fale tele of village and family compounds are the principal traditional roofs.\n\n## Local roofing terms\n\n- **Fale**: house. **Fale tele**: big (meeting) house.\n- **ʻAfa**: coconut-fibre sennit.\n- **Tufuga fau fale**: master house builder.\n- **Pola**: coconut-frond blinds. **Umukuka**: cookhouse.\n\n## Sources and gaps\n\nNo information on domestic roofing manufacturers was found in published sources. No individually documented landmark roof was found.\n\nRoof-material results from the 2016 and 2021 censuses: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Corrugated iron (67.6% of 2011 census records)"},{"label":"Traditional materials","value":"Sugarcane-leaf or coconut-frond thatch; ʻafa sennit lashing"},{"label":"Thatch share","value":"21.1% thatch, 10.7% iron and thatch (2011)"},{"label":"Climate driver","value":"Tropical cyclones, heavy rain"},{"label":"Building code","value":"National building code (1990, updated 2017)"}],"regions":["Oceania"],"aliases":["Samoan roofing"],"related":["samoan-fale","palm-thatch","thatch","corrugated-iron","roofing-in-the-pacific-islands","roofing-in-tonga","roofing-in-fiji"],"company":null,"sources":[{"title":"Architecture of Samoa","url":"https://en.wikipedia.org/wiki/Architecture_of_Samoa","publisher":"Wikipedia"},{"title":"Fale","url":"https://en.wikipedia.org/wiki/Fale","publisher":"Wikipedia"},{"title":"Samoa Population and Housing Census 2011, roof materials (H5)","url":"https://microdata.sbs.gov.ws/index.php/catalog/15/variable/V288","publisher":"Samoa Bureau of Statistics"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-san-marino","title":"Roofing in San Marino","category":"world-roofing","type":"place","country":{"name":"San Marino","iso2":"SM"},"regions":["Europe"],"company":null,"summary":"Roofing in San Marino, a hilltop microstate on Mount Titano whose stone fortifications and historic centre are a UNESCO World Heritage site.","aliases":["Sammarinese roofing"],"body":"San Marino is a small republic surrounded by Italy, built on and around Mount Titano. Its roofing tradition is essentially that of the neighbouring regions of central Italy, and very little has been published on Sammarinese roofs specifically.\n\n## Climate and hazards\n\nThe historic centre sits high on Mount Titano, so roofs are more exposed to wind and winter cold than those in the surrounding lowlands.\n\n## Roofing history\n\nAccording to UNESCO, the historic centre dates from the foundation of the republic as a city-state in the 13th century. Its surviving buildings include fortification towers, walls, gates and bastions, 14th- and 16th-century convents, the 18th-century Titano Theatre, and the 19th-century neo-classical basilica and Palazzo Pubblico. The defensive walls and much of the centre were extensively restored and partly rebuilt from the late 19th century into the early 20th century, under the direction of Gino Zani; UNESCO treats this restoration as part of the site's history. Roofs on the towers and civic buildings therefore reflect both medieval forms and this later reconstruction.\n\n## Traditional and vernacular roofs\n\nIn the surrounding parts of central Italy the traditional covering is curved clay coppi, often laid over flat embrici, on timber structures.\n\n## Roofing today\n\nSan Marino is not an EU member, so EU adoption of the Eurocodes does not apply automatically.\n\n## Codes, standards and regulation\n\nNo source on San Marino's building regulations was located.\n\n## Notable roofs\n\n- The fortification towers and walls of Mount Titano\n- The 19th-century Basilica and Palazzo Pubblico\n\n## Sources and gaps\n\nClimate and seismic data for roofing, roofing studies specific to San Marino, and information on modern roofing materials, building codes and industry: published information is limited.","key_facts":[{"label":"Heritage site","value":"San Marino Historic Centre and Mount Titano (UNESCO)"},{"label":"Origins of centre","value":"13th century"},{"label":"Major restoration","value":"Late 19th-early 20th century (Gino Zani)"}],"related":["roofing-in-italy","coppo-tile","clay-roof-tile","roofing-in-vatican-city"],"sources":[{"title":"San Marino Historic Centre and Mount Titano","url":"https://whc.unesco.org/en/list/1245","publisher":"UNESCO World Heritage Centre"},{"title":"Coppo","url":"https://it.wikipedia.org/wiki/Coppo","publisher":"Wikipedia (Italian)"}]},{"slug":"roofing-in-sao-tome-and-principe","title":"Roofing in São Tomé and Príncipe","category":"world-roofing","type":"place","country":{"name":"São Tomé and Príncipe","iso2":"ST"},"summary":"São Tomé and Príncipe's built heritage is dominated by about 200 colonial cocoa and coffee roças; six were inscribed as World Heritage in 2026.","body":"São Tomé and Príncipe is a small island nation of about 200,000 people in the Gulf of Guinea, independent from Portugal since 1975. Its architectural landscape is shaped above all by the *roças*, the plantation estates that made the islands a major producer of coffee and cocoa in the colonial era. About two hundred roça sites, main and secondary, are counted, and in 2026 six of them were inscribed on the UNESCO World Heritage List as The Roças of Sao Tome and Principe: Colonial Agricultural System and Forced Migration, under criterion (iv).\n\n## Climate and hazards\n\nThe islands are volcanic, mountainous and equatorial, with heavy rainfall, high humidity and constant warmth. Roofs must shed intense rain and resist decay and corrosion; the coastal setting adds salt air.\n\n## Roofing history\n\nThe islands were reached by Portuguese navigators in 1470. A sugar economy developed in the 15th and 16th centuries but its mills had failed by the end of the 16th century. In the late 19th and early 20th centuries, coffee and cocoa drove a new wave of plantation building. After slavery was abolished in 1875, new health and sanitation rules shaped how roças were built, and estates with more than a thousand workers were required to have a hospital. The estates relied on forced labour and migration, with thousands of workers brought to the islands under harsh conditions.\n\n## Traditional and vernacular roofs\n\nThe roça is a complete settlement rather than a single building. Typical components are:\n\n- **Administration house**, the residence of the estate managers.\n- **Hospital**, compulsory on large estates.\n- **Sanzalas**, the workers' quarters (called *senzalas* in Brazil).\n- **Terreiro**, the open central yard used for drying cocoa beans, daily roll call, paying workers and festivities.\n- **Driers (*secadores*)**, warehouses, workshops, sawmills, soap and palm-oil works, bakeries and stables.\n- **Social buildings** such as schools, nurseries, chapels and bandstands.\n\nRoças are laid out in three main patterns: around a yard (*roça terreiro*, the most common), along an axis (*roça avenida*), or as a street network resembling a small town (*roça cidade*).\n\n## Roofing today\n\nMany roça buildings are in fragile condition, and their preservation is a national heritage priority.\n\n## Notable roofs\n\n- **The Roças of Sao Tome and Principe: Colonial Agricultural System and Forced Migration** (UNESCO World Heritage, 2026), a serial property of six plantations: Monte Café, Água Izé, Diogo Vaz, São João, Sundy and Belo Monte.\n\n## Local roofing terms\n\n- *roça* (Portuguese): plantation estate.\n- *terreiro*: central yard of a roça.\n- *sanzala*: workers' housing on a roça.\n\n## Sources and gaps\n\nNo national roof-material figures were found in published sources.\n\nThe roofing materials and structures of roça buildings (for example clay tiles, timber or metal sheet) and of ordinary island houses were not described in published sources, nor were census data, codes or industry.","key_facts":[{"label":"Built heritage","value":"About 200 colonial plantation estates (roças)"},{"label":"World Heritage","value":"The Roças of Sao Tome and Principe: Colonial Agricultural System and Forced Migration (2026)"},{"label":"Plantation boom","value":"Coffee and cocoa, late 19th-early 20th century"},{"label":"Climate driver","value":"Equatorial rain and humidity"}],"regions":["Africa"],"aliases":["São Tomé roofing","Sao Tome and Principe roofing","roças"],"related":["roofing-in-gabon","roofing-in-equatorial-guinea","roofing-in-angola","roofing-in-cabo-verde","clay-roof-tile","corrugated-iron"],"sources":[{"title":"São Tomé and Príncipe's historic plantations added to UNESCO World Heritage List","url":"https://africanews.com/2026/07/28/sao-tome-and-principes-historic-plantations-added-to-unesco-world-heritage-list","publisher":"Africanews"},{"title":"The fields (roças) of São Tomé and Príncipe: a Lusophone heritage","url":"https://www.estudoprevio.net/the-fields-roc%cc%a7as-of-sa%cc%83o-tome-and-principe-a-lusophone-heritage/?lang=en","publisher":"Estudo Prévio (Duarte Pape, 2016)"},{"title":"São Tomé-et-Principe: le défi majeur de préservation des roças, vestiges fragiles du passé colonial","url":"https://afrique.le360.ma/afrique-centrale/sao-tome-et-principe/sao-tome-et-principe-le-defi-majeur-de-preservation-des-rocas-vestiges-fragiles-du-passe-colonial_WB665QOYP5CDXMXDDLJ7ADXSS4/","publisher":"Le360 Afrique"},{"title":"The Roças of Sao Tome and Principe: Colonial Agricultural System and Forced Migration","url":"https://whc.unesco.org/en/list/1750/","publisher":"UNESCO World Heritage Centre"}],"company":null},{"slug":"roofing-in-saudi-arabia","title":"Roofing in Saudi Arabia","category":"world-roofing","type":"place","country":{"name":"Saudi Arabia","iso2":"SA"},"regions":["Middle East"],"company":null,"summary":"Saudi roofing: Najdi mud-brick flat roofs on tamarisk beams, coral-stone tower houses of Jeddah, rock-cut Hegra and today’s insulated concrete roofs.","aliases":["Saudi roofing","Roofs of Saudi Arabia","Najdi roofs"],"body":"Saudi Arabia covers most of the Arabian Peninsula and has three very different historic roofing traditions: the mud-brick flat roofs of Najd in the centre, the coral-stone tower houses of the Red Sea coast, and the rock-cut Nabataean tombs of the north-west. Modern buildings are dominated by flat reinforced concrete roofs, now subject to energy-conservation rules in the Saudi Building Code.\n\n## Climate and hazards\n\nThe interior has extreme summer heat and very little rain, while the Red Sea coast around Jeddah is hot and humid. The national energy code divides the country into three climate zones, each with maximum heat-transfer values for the building envelope, including roofs. Mud roofs and walls are vulnerable to the rare but heavy rains.\n\n## Roofing history\n\n**Nabataean Hegra.** At Hegra (al-Hijr, Madâ'in Sâlih), the largest conserved Nabataean site south of Petra, 111 monumental tombs, 94 with decorated facades, were cut directly into sandstone between about the 1st century BC and the 1st century AD. As at Petra, the carved rock forms the roof of each chamber.\n\n**Najdi architecture.** The Najdi style flourished in central Arabia and is best represented by At-Turaif in ad-Diriyah, a UNESCO World Heritage site founded in the 15th century on the edge of the Diriyah oasis, where adobe was used even for major palace complexes. Roofs and doors were of tamarisk wood; walls were thick mud brick finished with mud plaster. See najdi-mud-roofs.\n\n**Red Sea tower houses.** In Historic Jeddah, the mercantile elite built tall tower houses in the late 19th century, a development linked to the opening of the Suez Canal in 1869. They have large carved wooden *roshan* bay windows and internal ventilation devices suited to the humid climate; lower houses use coral stone, a tradition shared along the Red Sea coast.\n\n## Traditional and vernacular roofs\n\n- **Najdi flat roof:** tamarisk timbers carrying earth, behind crenellated parapets (*shurfat*); bands of incised inverted triangles below the parapet help shed rainwater, and small openings (*furjat*) ventilate rooms.\n- **Coral-stone houses:** Red Sea coast, including Jeddah.\n- **Rock-cut chambers:** Hegra.\n\n## Roofing today\n\nFlat reinforced concrete roofs with waterproofing and insulation are standard.\n\n## Codes, standards and regulation\n\n- **Saudi Building Code (SBC):** a national code family; its 2018 edition is distributed by the International Code Council.\n- **SBC 602, Energy Conservation Requirements (low-rise residential, 2016):** sets maximum overall heat-transfer coefficients (U-values) for building envelopes in three climate zones. A 2019 study found that external insulation (polyurethane, 45-65 mm or about 1.8-2.6 in thick) could cut simulated annual energy use by about two-thirds, with payback in roughly 3-4 years, but noted the code still needed enforcement.\n\n## Notable roofs\n\n- **At-Turaif, ad-Diriyah** (UNESCO): Najdi mud-brick palaces and houses.\n- **Historic Jeddah** (UNESCO): coral-stone and roshan tower houses.\n- **Hegra** (UNESCO): Nabataean rock-cut tombs.\n- **Riyadh:** Najdi buildings including Masmak Fortress and Murabba Palace.\n\n## Local roofing terms\n\n- *shurfat* - crenellated parapets of Najdi buildings\n- *furjat* / *luhuj* - small ventilation openings\n- *roshan* - projecting wooden window bay (Jeddah)\n\n## Sources and gaps\n\nDetailed climate data, national data on roofing materials, roof-specific code provisions and information on manufacturers: published information is limited.","key_facts":[{"label":"Central vernacular","value":"Najdi mud brick with tamarisk roofs"},{"label":"Coastal vernacular","value":"Coral-stone tower houses (Jeddah)"},{"label":"Ancient","value":"Rock-cut Nabataean tombs, Hegra"},{"label":"Energy code","value":"SBC 602 (2016), three climate zones"},{"label":"Modern","value":"Flat insulated concrete"}],"related":["najdi-mud-roofs","chandal-roof","flat-roof","mud-roof","parapet","cool-roof","protected-membrane-roof","roofing-in-yemen","roofing-in-jordan","roofing-in-kuwait","roofing-in-qatar","roofing-in-the-united-arab-emirates","roofing-in-the-middle-east-and-gulf"],"sources":[{"title":"At-Turaif District in ad-Dir'iyah","url":"https://whc.unesco.org/en/list/1329","publisher":"UNESCO World Heritage Centre"},{"title":"Najdi architecture","url":"https://en.wikipedia.org/wiki/Najdi_architecture","publisher":"Wikipedia"},{"title":"Historic Jeddah, the Gate to Makkah","url":"https://whc.unesco.org/en/list/1361","publisher":"UNESCO World Heritage Centre"},{"title":"Hegra Archaeological Site (al-Hijr / Madâʾin Sâlih)","url":"https://whc.unesco.org/en/list/1293","publisher":"UNESCO World Heritage Centre"},{"title":"Residential Buildings Thermal Performance to Comply With the Energy Conservation Code of Saudi Arabia (AlFaraidy and Azzam, 2019)","url":"https://etasr.com/index.php/ETASR/article/view/2536","publisher":"Engineering, Technology & Applied Science Research"},{"title":"2018 Saudi Building Code (table of contents)","url":"https://shop.iccsafe.org/media/wysiwyg/material/4807S18SBC-TOC.pdf","publisher":"International Code Council"}]},{"slug":"roofing-in-scandinavia","title":"Roofing in Scandinavia","type":"place","summary":"Overview of roofing in Norway, Sweden, Denmark and Finland: turf and timber traditions, clay and concrete tiles, sheet metal and designs for snow.","body":"The Nordic countries share long, cold winters, heavy snow in many areas and wet, windy coasts. Roofing traditions grew from abundant timber and turf, and modern practice combines tiles, sheet metal and membranes engineered for snow loads and freeze-thaw.\n\n## Traditions\n\n- **Norway and Sweden** - rural houses were roofed for centuries with birch bark and turf (*torvtak*), which was almost universal until the early 18th century. Churches and high-status buildings used steeper roofs of boards, wooden shingles or lead, as seen on Norway's surviving stave churches.\n- **Denmark** - thatch was common on half-timbered rural houses, and red clay tiles with whitewashed walls became typical of coastal towns such as Skagen from the 19th century.\n- **Finland** - timber shingle and board roofs, and later sheet metal, dominate the vernacular, with turf on some older farm buildings.\n\n## Tiles\n\nThe Scandinavian clay tile is a variant of the pantile with a softer S-shape. Clay and concrete tiles are common on houses in Denmark and southern Sweden.\n\n## Sheet metal\n\nPainted and coated steel sheet, in corrugated, trapezoidal, standing seam and tile-profile forms, is very widely used across Norway, Sweden and Finland, because it is light, sheds snow and suits timber construction. Kronborg Castle in Denmark received a copper roof in 1585.\n\n## Turf and green roofs\n\nTurf roofs remain common on new cabins and holiday homes in Norway, now built over bituminous or synthetic membranes with drainage layers instead of birch bark. Modern green roofs are also widespread in cities; Sweden's Augustenborg area in Malmö opened a botanical roof garden in 1999.\n\n## Snow and safety\n\nRoof design across the region is governed by Eurocode-based snow load rules with national annexes. Snow guards, heated gutters on some buildings and attention to ice dams at eaves are common. Removing snow from flat and low-slope roofs is a regular winter task in heavy-snow areas.","key_facts":[{"label":"Traditional roofs","value":"Turf (torvtak), timber shingles, thatch"},{"label":"Common modern coverings","value":"Steel sheet, clay and concrete tile"},{"label":"Regional tile","value":"Scandinavian pantile variant"},{"label":"Key load","value":"Snow"}],"regions":["Europe","Arctic"],"aliases":["Nordic roofing","Norwegian roofing","Swedish roofing","Danish roofing","Finnish roofing"],"related":["torvtak","stave-church-roofs","dutch-and-danish-reed-thatch","roofing-in-iceland","snow-load"],"sources":[{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"},{"title":"Architecture of Denmark","url":"https://en.wikipedia.org/wiki/Architecture_of_Denmark","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-senegal","title":"Roofing in Senegal","type":"place","country":{"name":"Senegal","iso2":"SN"},"summary":"Senegal mixes metal sheet, concrete slabs and thatch more evenly than its neighbours; Dakar is mostly concrete, while Casamance has thatched impluvium houses.","body":"Senegal, at the western tip of Africa, has one of the most varied roofing patterns in West Africa. Concrete slab roofs dominate Dakar and other cities, metal and asbestos-cement sheet are common in towns, and thatch is still widespread in rural areas. In the humid south, the Diola of Casamance built some of the region's most distinctive thatched houses.\n\n## Climate and hazards\n\nMost of Senegal is Sahelian, with a single short rainy season and a long dry season with harmattan winds. The south, especially Casamance, is much wetter and more forested. The Atlantic coast brings salt air, and low-lying Saint-Louis has suffered from flooding. Heat gain through metal roofs is a widespread comfort issue.\n\n## Roofing history\n\nSaint-Louis, founded as a French trading settlement in the 17th century, became the capital of Senegal from 1872 to 1957 and of French West Africa until 1902. Its colonial architecture is known for balconied houses, gallery houses and rare Portuguese-style low houses (*maisons basses*).\n\n## Traditional and vernacular roofs\n\n- **Diola impluvium house** (*case à impluvium*), Casamance: a round earth house whose thatched roof slopes both outward and inward, draining rain through a central opening into a basin. Only a handful survive (see Diola impluvium house).\n- **Multi-storey earth houses** (*cases à étages*) at Mlomp, Casamance: clay walls with palm-wood floors under straw roofs.\n- **Thatch**: grass or straw thatch was still recorded on about one home in six in national surveys of 2013-2018.\n- **Nubian vaults**: since 2000 the association La Voûte Nubienne has trained masons in Senegal, among other Sahel countries, to build timber-free earth-brick vaults.\n\n## Roofing today\n\nThe 2018 Afrobarometer survey recorded the following roof materials among its Senegalese respondents:\n\n| Main roof material | Share of respondents (2018) |\n|---|---|\n| Metal, aluminium, tin or zinc | 32.2% |\n| Concrete | 28.7% |\n| Thatch or grass | 17.3% |\n| Asbestos | 12.1% |\n| Tiles | 5.3% |\n| Multiple materials | 1.3% |\n\nAfrobarometer surveys interview about 1,200 adults per country; these figures are unweighted counts in the survey sample. Earlier rounds in 2013 and 2014 gave similar shares for metal (39% and 37%) and thatch (17% in both).\n\nDakar is dominated by concrete. In the unweighted 2015-16 urban Dakar Multiple Indicator Cluster Survey sample (about 4,900 households), 69.7% of roofs were cement, 20.2% tiles or slate and 8.3% zinc or fibre cement; thatch was almost absent.\n\n## Codes, standards and regulation\n\nSaint-Louis is managed under a Safeguarding and Valorisation Plan created in 2006, with an implementing decree of 2008.\n\n## Notable roofs\n\n- **Island of Saint-Louis**: colonial balconied and gallery houses, a World Heritage site.\n- **Impluvium houses of Casamance**, including examples at Enampore, Mlomp and Oussouye.\n\n## Local roofing terms\n\n- **case à impluvium** (French): impluvium house.\n- **case à étages** (French): multi-storey earth house.\n- **dalle** (French): concrete roof slab.\n- **tôle** (French): metal roof sheet.\n\n## Sources and gaps\n\nSurvey shares are unweighted; ANSD census tables on roof material (2013 census) are not well documented in published sources. Sahelian vernacular house types in northern Senegal, codes and industry: published information is limited.","key_facts":[{"label":"Leading materials (Afrobarometer 2018)","value":"Metal 32.2%, concrete 28.7%, thatch 17.3%, asbestos 12.1%"},{"label":"Dakar","value":"Cement roofs 69.7% (MICS 2015-16 file)"},{"label":"Traditional materials","value":"Thatch, earth, palm wood"},{"label":"Climate driver","value":"Short Sahelian rainy season; wetter Casamance; heat"},{"label":"Heritage roof type","value":"Diola impluvium house"}],"regions":["Africa"],"aliases":["Senegalese roofing","roofing in Senegal"],"related":["roofing-in-west-africa","diola-impluvium-house","nubian-vault","sahelian-earthen-roofs","corrugated-iron","corrugated-fibre-cement-sheet","thatch","flat-roof","roofing-in-the-gambia","roofing-in-mali","roofing-in-guinea-bissau"],"sources":[{"title":"Afrobarometer Survey 2018, Round 7, Senegal: roof of respondent's home","url":"https://catalog.ihsn.org/catalog/9778/variable/F1/V326?name=Q105","publisher":"IHSN / Afrobarometer"},{"title":"Afrobarometer Survey 2014, Round 6, Senegal: roof of respondent's home","url":"https://datacatalog.ihsn.org/catalog/8948/variable/F2/V651?name=Q105","publisher":"IHSN / Afrobarometer"},{"title":"Afrobarometer Survey 2013, Round 5, Senegal: roof of respondent's home","url":"https://catalog.ihsn.org/catalog/8892/variable/F2/V612?name=Q105","publisher":"IHSN / Afrobarometer"},{"title":"MICS 2015-2016 Urban Dakar: matériau principal du toit (HC4)","url":"https://microdata.worldbank.org/catalog/3485/variable/F17/V2445?name=HC4","publisher":"World Bank Microdata Library / ANSD"},{"title":"Island of Saint-Louis","url":"https://whc.unesco.org/en/list/956/","publisher":"UNESCO World Heritage Centre"},{"title":"House of the impluvium, multi-storey house and architectural forms in Casamance","url":"https://www.archiweb.cz/en/n/domaci/dum-impluvium-poschodovy-dum-a-architektonicke-formy-v-nbspcasamance","publisher":"Archiweb"},{"title":"Jola Impluvium House","url":"https://dennisrhollowayarchitect.com/JolaImpluvium.html","publisher":"Dennis R. Holloway, Architect"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-serbia","title":"Roofing in Serbia","category":"world-roofing","type":"place","country":{"name":"Serbia","iso2":"RS"},"regions":["Europe"],"company":null,"summary":"How Serbia roofs its buildings: domed medieval churches, high-hipped log houses with straw or shingle roofs, tiled bondruk houses and modern tile and metal.","aliases":["Serbian roofing","Krovovi u Srbiji"],"body":"Serbia's roofing tradition combines Byzantine-influenced church domes, timber vernacular houses of the forested west, tiled timber-frame houses of the central lowlands and the farmsteads of the Pannonian plain in Vojvodina. The high, four-sided hipped roof (*četvorovodni krov*) recurs on both the log and the timber-frame rural house.\n\n## Climate and hazards\n\nSerbia has a continental climate, with cold, snowy winters and hot summers, and the central Balkans are seismic. After the 1963 Skopje earthquake, Yugoslavia drafted its first code for construction in seismic regions in 1964, which applied in Serbia.\n\n## Roofing history\n\n**Medieval churches.** Serbian medieval architecture is grouped into schools. Raška churches (roughly the 1160s to the late 13th century) have a single dome on a drum; many were later altered, often in their drum-and-dome roofs. Serbo-Byzantine (Vardar) churches of the 13th-14th centuries use a cross-in-square plan with one or five domes. The Morava school ran from the 1370s to 1459. Byzantine-tradition domes were generally covered with lead or regional tiles.\n\n**Ottoman period.** Two-storey manor houses (*konak*) were built in the Turkish manner. The Despot Stefan Tower in Belgrade (about 1405) and the Nenadović Tower in Valjevo (1813) are examples of Balkan tower houses.\n\n**Modern.** After the 1900 Paris Exposition a Serbo-Byzantine Revival developed; its landmarks include the church at Oplenac (commissioned 1909) and the Church of Saint Sava in Belgrade, inspired by Hagia Sophia and described as the largest Neo-Byzantine project of the 20th century. In Vojvodina, Secession buildings in Subotica and Novi Sad show central European influence.\n\n## Traditional and vernacular roofs\n\n- **Brvnara (log house):** found in forested, mountainous western Serbia such as Zlatibor and Tara, from the 14th to 19th centuries. A large pyramidal, high-hipped roof sits on a low log cube and was covered with straw or wooden shingles.\n- **Bondruka (timber-frame house):** the most common rural house south of the Danube, with mud-and-reed infill walls and a four-sided hipped roof of slightly curved clay tiles.\n- **Wooden churches:** 18th-19th-century timber churches roofed with large wooden shingles, such as Dub (1792), Takovo (1795) and Rača (1826).\n- **Salaš:** Vojvodina farmsteads built of local mud, brick, wood and reed.\n\n## Notable roofs\n\n- Domed churches of the Raška, Serbo-Byzantine and Morava schools\n- Wooden churches of Dub, Takovo and Rača\n- Church of Saint Sava, Belgrade\n\n## Local roofing terms\n\n- *četvorovodni krov* - four-sided (hipped) roof\n- *brvnara* - log house\n- *bondruka* - timber-frame house with mud-and-reed infill\n- *izba* - cellar or ground-floor store\n- *salaš* - farmstead of the Pannonian plain\n- *konak* - Ottoman-style manor house\n## Sources and gaps\n\nRoof-specific climate data, data on current roofing materials, current national regulations and manufacturer information: published information is limited.","key_facts":[{"label":"Traditional roof form","value":"Four-sided hipped roof"},{"label":"Log house roof","value":"Straw or wooden shingle (brvnara)"},{"label":"Lowland house roof","value":"Slightly curved clay tile (bondruka)"},{"label":"Church tradition","value":"Raška, Serbo-Byzantine and Morava schools"}],"related":["hip-roof","wood-shingle","thatch","clay-roof-tile","dome","hagia-sophia-dome","kulla-tower-house","roofing-in-bosnia-and-herzegovina","roofing-in-kosovo","roofing-in-north-macedonia","roofing-in-hungary","roofing-in-romania"],"sources":[{"title":"Architecture of Serbia","url":"https://en.wikipedia.org/wiki/Architecture_of_Serbia","publisher":"Wikipedia"},{"title":"Byzantine architecture","url":"https://en.wikipedia.org/wiki/Byzantine_architecture","publisher":"Wikipedia"},{"title":"Tower houses in the Balkans","url":"https://en.wikipedia.org/wiki/Tower_houses_in_the_Balkans","publisher":"Wikipedia"},{"title":"1963 Skopje earthquake","url":"https://en.wikipedia.org/wiki/1963_Skopje_earthquake","publisher":"Wikipedia"}]},{"slug":"roofing-in-seychelles","title":"Roofing in Seychelles","category":"world-roofing","type":"place","country":{"name":"Seychelles","iso2":"SC"},"summary":"Seychelles Creole houses have high-pitched roofs, first of pandanus thatch and, after 1902 in Victoria, corrugated iron, over timber frames and verandahs.","body":"The Seychelles is an archipelago of granite and coral islands in the western Indian Ocean. Its signature building is the timber Creole house with a high-pitched roof, large verandah and raised stone foundations. The earliest roofs were thatched with pandanus leaves; corrugated iron replaced them in the early 20th century, and since the 1970s concrete construction has largely displaced the Creole house.\n\n## Climate and hazards\n\nHigh-pitched roofs and large openings provided natural ventilation and light in the hot, humid climate. Heavy rain also brings landslides: on 12 October 1862 a landslide in Victoria washed away many thatched houses.\n\n## Roofing history\n\nAccording to the historian Tony Mathiot, the first traditional Creole structures were designed and built by some of about 70 French Jacobins exiled to Mahe for allegedly plotting against Napoleon; the deportees arrived in 1801. Creole dwellings developed in the early 19th century, attributed to French settlers from Ile Bourbon (Reunion). Early roofs were thatched with pandanus leaves. The Building Ordinance of 2 August 1902 restricted thatch in Victoria, after which builders there used corrugated iron sheets; thatch was out of fashion by about 1910, though it remained in use in suburbs and districts. Many Creole houses were still lived in during the 1960s, but most were demolished after independence, and virtually no new traditional Creole buildings have been built since the 1970s. About 95% of such buildings are estimated to have been lost.\n\n## Traditional and vernacular roofs\n\n- **Creole house**: timber frame of hardwoods such as *capucin*, *bois rouge*, *albizzia* and *takamaka*, with hand-hewn casuarina beams joined by mortise and tenon, a *capucin* ridge pole and rafters of *bodamyen*. The pitched roof, of thatch and later corrugated iron, could have small vertical windows in projecting gables, and a loft or garret was standard. A verandah with raffia blinds was also standard, and the house rests on masonry plinths or stone piles. Kitchens were separate outbuildings. See Seychellois Creole house.\n- **Plantation houses**: larger houses with living rooms opening through up to ten pairs of double doors and windows.\n\n## Roofing today\n\nConcrete and modern construction dominate new building. Coral lime is no longer used, partly to protect reefs.\n\n## Codes, standards and regulation\n\nThe Building Ordinance passed on 2 August 1902 restricted thatch in Victoria.\n\n## Notable roofs\n\n- **Kenwyn House**, Victoria (built 1855 for Dr James Brooks; renovated 2003): a declared National Monument.\n- **Grann Kaz**, L'Union Estate, La Digue (last quarter of the 19th century; restored in the late 1970s).\n- **Kaz Zanana**, Victoria: a restored Creole town house.\n\n## Local roofing terms\n\n- *bodamyen*: timber used for rafters.\n- *madriye*: planks.\n\n## Sources and gaps\n\nNo information on domestic roofing manufacturers was found in published sources.\n\nCensus roof-material shares, the date when corrugated iron first reached the islands and current building regulations: published information is limited.","key_facts":[{"label":"Traditional form","value":"Timber Creole house with high-pitched roof and verandah"},{"label":"Early roofing","value":"Pandanus-leaf thatch"},{"label":"Key regulation","value":"Building Ordinance 1902 (thatch restricted in Victoria)"},{"label":"Heritage loss","value":"About 95% of traditional Creole buildings gone"}],"regions":["Africa"],"aliases":["Seychellois roofing"],"related":["seychellois-creole-house","corrugated-iron","palm-thatch","thatch","roofing-in-mauritius","roofing-in-madagascar","roofing-in-comoros"],"company":null,"sources":[{"title":"The traditional Creole architecture - An aspect of the Seychelles heritage in need of preservation","url":"https://www.seychellesnewsagency.com/public/articles/1652/The+traditional+Creole+architecture+-+An+aspect+of+the+Seychelles+heritage+in+need+of+preservation","publisher":"Seychelles News Agency"},{"title":"Those charming Creole houses of auld lang syne","url":"https://www.nation.sc/archive/243055/those-charming-creole-houses-of-auld-lang-syne","publisher":"Seychelles Nation"},{"title":"Seychelles: the island of exiles","url":"https://kreolmagazine.com/culture/history-and-culture/seychelles-the-island-of-exiles/","publisher":"Kreol Magazine"}]},{"slug":"roofing-in-sierra-leone","title":"Roofing in Sierra Leone","type":"place","country":{"name":"Sierra Leone","iso2":"SL"},"summary":"Most Sierra Leone homes have corrugated metal ('zinc') roofs; thatch survives in rural areas and Freetown's timber Krio board houses are a threatened heritage.","body":"Sierra Leone lies on the wet Atlantic coast of West Africa, and its roofs must above all shed heavy rain. Rural houses were traditionally thatched over earth or wattle walls, while Freetown developed a distinctive timber architecture brought by settlers from North America. Today corrugated metal sheet, locally called \"zinc\", covers more than four in five homes.\n\n## Climate and hazards\n\nThe climate is tropical and monsoonal, with a long and very wet rainy season and a shorter dry season brought by the harmattan. Persistent damp encourages rot and insect attack in timber and thatch, and many older roofs are patched with metal sheets to keep out the rain.\n\n## Roofing history\n\nFreetown was settled from 1792 by Black Loyalists who had fought for the British in the American Revolutionary War and been evacuated to Nova Scotia, followed by Jamaican Maroons and Africans freed from slave ships. Their descendants, the Krio, built timber \"board houses\" that researchers link to cabin-like houses of the American eastern seaboard. In the early 20th century British officials moved to Hill Station above the city, building large timber houses on metal stilts set in concrete piles.\n\nOver the 20th century stone and concrete houses became more fashionable in Freetown, and metal sheet became the usual roof across the country. In the 1991-2002 civil war, hundreds of wooden Krio houses were burned.\n\n## Traditional and vernacular roofs\n\n- **Thatch**: grass or palm-leaf thatch is the traditional rural roof and is still recorded on about one household in seven.\n- **Krio board house** (*bod os*): two-storey timber houses, sometimes with a garret, now often patched with metal sheet (see Krio board house).\n\n## Roofing today\n\nIn the unweighted 2017 Multiple Indicator Cluster Survey sample (about 15,300 households):\n\n| Main roof material | Share of sampled households |\n|---|---|\n| Metal, tin or corrugated iron sheets (\"zinc\") | 83.8% |\n| Thatch or palm leaf | 13.5% |\n| Palm or bamboo | 1.1% |\n| Cement | 0.8% |\n\nA 2010 community-level agricultural survey asked how many rooftops in each community were zinc: in 43.1% of about 900 communities \"most\" were and in 15.8% \"all\" were, while 4.7% had none.\n\nThe 2015 Population and Housing Census classified roofs as concrete, asbestos, zinc, thatch, tarpaulin, tiles or other.\n\n## Notable roofs\n\n- **Krio board houses of Freetown**, in neighbourhoods such as Kroo Town, Congo Town, King Tom, Fourah Bay and Murray Town; the Sierra Leone National Museum has called for their urgent conservation.\n- **Hill Station** colonial timber houses on stilts.\n\n## Local roofing terms\n\n- **zinc** (Krio and Sierra Leonean English): corrugated metal roof sheet.\n- **bod os** (Krio): board house, the traditional timber house of Freetown.\n\n## Sources and gaps\n\nSurvey figures are unweighted counts. Detailed published sources on rural thatching techniques, regulation and industry: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Corrugated metal (\"zinc\"), 83.8% (MICS 2017 file)"},{"label":"Thatch","value":"13.5% of households (MICS 2017 file)"},{"label":"Traditional materials","value":"Grass and palm thatch; timber (Freetown)"},{"label":"Climate driver","value":"Very heavy monsoon rainfall"},{"label":"Heritage type","value":"Krio board house"}],"regions":["Africa"],"aliases":["Sierra Leonean roofing","roofing in Sierra Leone"],"related":["roofing-in-west-africa","krio-board-house","corrugated-iron","thatch","palm-thatch","roofing-in-liberia","roofing-in-guinea"],"sources":[{"title":"MICS 2017 Sierra Leone: main material of roof (HC5)","url":"https://microdata.worldbank.org/catalog/3210/variable/F5/V1009?name=HC5","publisher":"World Bank Microdata Library / Statistics Sierra Leone"},{"title":"Agriculture Household Tracking Survey 2010: zinc rooftops in community","url":"https://microdata.statistics.sl/index.php/catalog/10/variable/V1473","publisher":"Statistics Sierra Leone"},{"title":"2015 Population and Housing Census, IPUMS subset: roof material","url":"https://microdata.worldbank.org/catalog/7783/variable/SL2015A_ROOF","publisher":"World Bank Microdata Library / IPUMS"},{"title":"Colonial-era wooden buildings decay in Sierra Leone","url":"https://www.nbcnews.com/news/world/colonial-era-wooden-buildings-decay-sierra-leone-flna751400","publisher":"NBC News / Reuters"},{"title":"Once influential, slave descendants in Sierra Leone face a less certain future","url":"https://csmonitor.com/World/Africa/2015/0908/Once-influential-slave-descendants-in-Sierra-Leone-face-a-less-certain-future","publisher":"Christian Science Monitor"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-singapore","title":"Roofing in Singapore","category":"world-roofing","type":"place","country":{"name":"Singapore","iso2":"SG"},"summary":"Roofing in Singapore, from attap and zinc kampong roofs to the flat concrete roofs of HDB blocks, now widely fitted with solar panels and greenery.","body":"Singapore is a small, dense tropical city-state that transformed its housing within two decades, from timber kampong houses roofed with palm-leaf attap or zinc sheet to high-rise public housing blocks with flat concrete roofs. Many of those roofs now carry solar panels under a national programme, alongside extensive rooftop greenery.\n\n## Climate and hazards\n\nSingapore is equatorial: hot, humid and rainy all year, with heavy convective storms and periodic droughts. It is not in a typhoon or major earthquake zone. The main roof concerns are rain shedding and drainage, heat gain and, historically, fire.\n\n## Roofing history\n\n**Kampong houses.** Late 19th- and early 20th-century kampong (village) houses had tall, pitched, gabled roofs covered in attap, made from palm fronds, over raised floors that helped with airflow, flash floods and damp ground. Attap insulated well but became dry and brittle in heat waves and droughts.\n\n**Fire and zinc.** From the 1950s many attap roofs were replaced with zinc sheeting. Urban squatter settlements, which grew from about 127,000 people in 1947 to 246,000 in the mid-1950s, were densely packed with attap- or zinc-roofed huts. Major fires struck Kampong Bugis (1951), Geylang (1953), Kampong Tiong Bahru (1955 and 1959) and Kampong Koo Chye (1958). On 25 May 1961, the Bukit Ho Swee fire destroyed 19 ha (47 acres) of homes and left more than 16,000 people homeless.\n\n**Public housing.** The Housing and Development Board (HDB) was formed on 1 February 1960, taking over from the Singapore Improvement Trust. After the Bukit Ho Swee fire the government promised to rehouse the victims in HDB flats, and a new estate was built on the site by February 1962. Public housing and urban renewal from the 1960s caused a sharp decline in attap- and zinc-roofed houses: they made up 34% of homes in 1970 and 10.8% at the 1980 census, mostly in outlying areas.\n\n## Traditional and vernacular roofs\n\n- **Attap house:** timber kampong house with a steep gabled attap roof (see the attap roof entry).\n- **Zinc-roofed house:** the 1950s-1970s successor, with corrugated zinc sheet replacing thatch.\n\n## Roofing today\n\nA large share of Singapore's population lives in HDB blocks, whose flat reinforced-concrete roofs are used for water tanks, services, greenery and solar panels.\n\n**Rooftop solar.** HDB began installing solar panels on blocks in the 2010s and launched the SolarNova programme with the Economic Development Board in 2014. By December 2019 about 2,060 HDB blocks had solar panels, with about 2,500 more in progress. In 2019 HDB raised its target to 540 MWp by 2030 (from 220 MWp, already exceeded), as part of a national goal of at least 2 GWp, enough to generate about 648 GWh a year.\n\n**Rooftop greenery.** National incentives support green roofs on new and existing buildings (see Singapore skyrise greenery).\n\n**Design heritage.** The natural cross-ventilation of the attap house inspired contemporary designs such as Newton Suites by WOHA Architects.\n\n## Codes, standards and regulation\n\nRooftop greenery is promoted by the National Parks Board and the Urban Redevelopment Authority.\n\n## Notable roofs\n\n- HDB estates with continuous rooftop solar arrays.\n- Rooftop gardens under the skyrise greenery programmes.\n\n## Local roofing terms\n\n- *attap* (Malay *atap*) - palm-leaf thatch; also \"roof\"\n- *kampong* - village\n- *zinc roof* - local term for corrugated galvanised steel sheet\n\n## Sources and gaps\n\nA summary of the national building control law as it applies to roofs, details of shophouse roofing and industry data: published information is limited.","key_facts":[{"label":"Attap/zinc-roofed homes","value":"34% (1970) to 10.8% (1980 census)"},{"label":"HDB founded","value":"1 February 1960"},{"label":"HDB blocks with solar","value":"About 2,060 (December 2019)"},{"label":"HDB solar target","value":"540 MWp by 2030"},{"label":"Formative event","value":"Bukit Ho Swee fire, 25 May 1961"}],"regions":["Southeast Asia"],"aliases":["Singapore roofing","HDB roofs"],"related":["roofing-in-southeast-asia","singapore-skyrise-greenery","attap-roof","palm-thatch","corrugated-iron","flat-roof","green-roof","roofing-in-malaysia","roofing-in-indonesia"],"company":null,"sources":[{"title":"Post-WWII fire hazards in Singapore's kampongs","url":"https://www.nus.edu.sg/nuslibraries/dsprojects/heatinurbanasia/03-cities/post-wwii-fire-hazards-in-singapores-kampongs/","publisher":"NUS Libraries and Asia Research Institute"},{"title":"Attap dwelling","url":"https://en.wikipedia.org/wiki/Attap_dwelling","publisher":"Wikipedia"},{"title":"'Kampong' house","url":"https://www.roots.gov.sg/Collection-Landing/listing/1077823","publisher":"National Heritage Board, Singapore (Roots.sg)"},{"title":"Housing and Development Board","url":"https://en.wikipedia.org/wiki/Housing_and_Development_Board","publisher":"Wikipedia"},{"title":"HDB raises solar target for 2030 to 540MWp","url":"https://www.propertyguru.com.sg/property-management-news/2019/12/185330/hdb-raises-solar-target-for-2030-to-540mwp","publisher":"PropertyGuru"}]},{"slug":"roofing-in-slovakia","title":"Roofing in Slovakia","category":"world-roofing","type":"place","country":{"name":"Slovakia","iso2":"SK"},"summary":"Slovak roofing: hand-split spruce and larch shingles on log villages such as Vlkolínec, Carpathian wooden churches, and the STN 73 1901 roof standard.","body":"Slovakia is a mountainous, forested country in the western Carpathians, and its traditional roofs were overwhelmingly of wood. Log houses in mountain villages were covered with hand-split wooden shingles, as were the wooden churches of the east, eight of which are on the UNESCO World Heritage List.\n\n## Climate and hazards\n\nSlovakia has cold, snowy winters in the Tatras and other ranges and warmer conditions in the Danube lowlands. Snow load, frost and wind-driven rain are the main concerns, and fire was historically the main threat to timber villages: a row of houses at Vlkolínec destroyed by fire in the Second World War was never rebuilt.\n\n## Roofing history\n\nVlkolínec, near Ružomberok, illustrates the long continuity of Slovak timber building. The settlement's roots go back to the 10th century, it was first recorded in the late 14th century, and by 1469 it had five streets. Most of its surviving buildings date from the late 19th century: log houses on narrow lots, with stone foundations and clay-covered walls painted white or blue, and stables, barns and outbuildings behind. A bell tower was built in 1770. The village was declared a reservation of folk architecture in 1977.\n\nWooden shingles were common because timber was readily available and shingles were practical: the roofs were light, insulated well and were easy to repair, since damaged pieces could be replaced one at a time. Shingle roofs have since largely been replaced by modern coverings, but they are still used on historic buildings, in open-air museums and in conservation areas.\n\nIn the east, wooden churches of several denominations were built between the 16th and 18th centuries. The eight churches inscribed by UNESCO as the Wooden Churches of the Slovak part of the Carpathian Mountain Area include two Roman Catholic, three Protestant and three described by UNESCO as Greek Orthodox; the Protestant churches reflect a period of religious tolerance in Upper Hungary during the 17th-century anti-Habsburg uprisings.\n\n## Traditional and vernacular roofs\n\n- **Drevený šindeľ (wooden shingle):** mostly spruce or larch, split by hand along the grain so that the wood's fibres stay intact and resist moisture and warping. With proper care, shingles could last several decades, weathering to a grey patina.\n- **Log-house roofs:** shingle roofs over log houses, as preserved at Vlkolínec.\n- **Church roofs:** timber roofs and towers on the wooden churches of the Carpathians. See wooden tserkva roofs.\n\n## Roofing today\n\nShingle roofs survive mainly in heritage settings.\n\n## Codes, standards and regulation\n\nThe Slovak roof design standard is STN 73 1901, published by the Slovak Office of Standards, Metrology and Testing; it carries the same number as the Czech roof design standard ČSN 73 1901. As an EU member, Slovakia applies the Eurocodes, including Eurocode 1, Part 1-3 for snow loads.\n\n## Notable roofs\n\n- **Vlkolínec** (UNESCO World Heritage Site), with about 45 log buildings forming a remarkably intact settlement.\n- **Wooden Churches of the Slovak part of the Carpathian Mountain Area** (UNESCO), eight churches of the 16th-18th centuries.\n\n## Local roofing terms\n\n- *drevený šindeľ* - wooden shingle\n\n## Sources and gaps\n\nCurrent market data and information on named manufacturers: published information is limited.","key_facts":[{"label":"Traditional covering","value":"Hand-split spruce or larch shingles"},{"label":"Roof design standard","value":"STN 73 1901"},{"label":"UNESCO village","value":"Vlkolínec"},{"label":"UNESCO churches","value":"8 wooden churches, 16th-18th centuries"}],"regions":["Europe"],"aliases":["Slovak roofing","roofs in Slovakia"],"related":["wood-shingle","wooden-tserkva-roofs","roofing-in-czechia","roofing-in-poland","roofing-in-hungary","roofing-in-ukraine","clay-roof-tile","wooden-churches-of-southern-malopolska"],"company":null,"sources":[{"title":"Vlkolínec","url":"https://whc.unesco.org/en/list/622","publisher":"UNESCO World Heritage Centre"},{"title":"Vlkolínec's wooden shingles: a traditional material with timeless value","url":"https://www.visitliptov.sk/en/?p=728125","publisher":"Visit Liptov"},{"title":"Wooden Churches of the Slovak part of the Carpathian Mountain Area","url":"https://whc.unesco.org/en/list/1273","publisher":"UNESCO World Heritage Centre"},{"title":"STN 73 1901","url":"https://normy.normoff.gov.sk/norma/98592/?lang=en","publisher":"Slovak Office of Standards, Metrology and Testing"},{"title":"ČSN 73 1901 Navrhování střech – Základní ustanovení","url":"https://www.tzb-info.cz/normy/csn-73-1901-1999-01","publisher":"TZB-info"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"}]},{"slug":"roofing-in-slovenia","title":"Roofing in Slovenia","category":"world-roofing","type":"place","country":{"name":"Slovenia","iso2":"SI"},"regions":["Europe"],"company":null,"summary":"How Slovenia roofs its buildings, from straw- and shingle-roofed kozolec hayracks and Alpine herders' huts to modern tiled and metal roofs.","aliases":["Slovenian roofing","Strehe v Sloveniji"],"body":"Slovenia sits where the Alps, the Pannonian plain and the Mediterranean Karst meet, and its roofs reflect all three. The country's best-known roofed structure is not a house but the *kozolec*, a freestanding hayrack that Slovenes regard as a symbol of national identity. High in the Kamnik Alps, herders' huts with shingled roofs reaching almost to the ground are another distinctive tradition.\n\n## Climate and hazards\n\nRoofs in the Alpine north and west must carry winter snow, while the lowlands have a continental climate and the Karst and coast are milder and Mediterranean. As an EU member, it applies the Eurocodes, which cover snow, wind and earthquake actions on structures.\n\n## Roofing history\n\nTraditional rural buildings were roofed with organic materials. The kozolec illustrates the sequence: its roofs were originally straw, later wood, and more recently metal tiles. The oldest kozolec preserved at the open-air museum in Šentrupert dates from 1795.\n\nIn the 20th century the architect Jože Plečnik drew on vernacular forms; in 1939 shepherds and dairymaids on Velika Planina built the Chapel of Our Lady of the Snows to his design, modelled on the local herders' huts. The chapel and about 100 wooden dwellings on the plateau were burned during the Second World War; a new chapel was built in 1988.\n\n## Traditional and vernacular roofs\n\n**Kozolec (hayrack).** A permanent timber rack, usually artistically made, used to dry hay, fodder and maize. It is found throughout Slovenia except Prekmurje, eastern Styria and the Slovenian Littoral, and similar structures exist in Friuli, southern Carinthia and East Tyrol. About 80% of all such hayracks are in Slovenia, and more than 30 types can be distinguished. Simple single racks (*enojni stegnjeni kozolec*) may have only a small roof or a catslide roof (*s plaščem*), while the roofed double hayrack (*toplar*, from the Austrian German *Doppler*, \"double structure\") joins two racks under one roof; variants add an extension (*toplar z repom*) or a shed (*kozolec s hišo*).\n\n**Herders' huts of Velika Planina.** Mostly single-room timber huts with oval roofs of wooden shingles extending nearly to the ground, which shelter livestock under the eaves.\n\n## Codes, standards and regulation\n\nSlovenia applies the Eurocodes for structural design.\n\n## Notable roofs\n\n- **Dežela kozolcev (Land of Hayracks), Šentrupert:** built 2010-2013 and opened in 2013, described as the first open-air museum of its kind, with 17 hayracks among 19 drying structures. Over 650 hayracks have been counted in the surrounding Mirna Valley. About 250 are registered with the Slovenian Ethnographic Museum.\n- **Simončič Hayrack:** the largest in Slovenia.\n- **Velika Planina:** herders' settlement and Plečnik-designed chapel.\n\nA joint bid by three countries to place hayracks on the UNESCO list has been reported by the Slovenian Press Agency.\n\n## Local roofing terms\n\n- *kozolec* - hayrack; colloquially *kozuc*; *stog* in Upper Carniola\n- *toplar* (*doplar*) - roofed double hayrack\n- *kozolec s plaščem* - hayrack with catslide roof\n- *kozolec s hišo* - roofed double hayrack with shed\n- *Velika Planina* - \"big pasture\"\n## Sources and gaps\n\nDetailed descriptions of Karst stone-slab roofs and of Alpine shingle-making techniques, data on current roofing materials, national regulations and information on Slovenian roofing manufacturers were not found in published sources.","key_facts":[{"label":"Iconic structure","value":"Kozolec (hayrack)"},{"label":"Hayrack roofing","value":"Straw, then wood, more recently metal tiles"},{"label":"Alpine huts","value":"Shingled oval roofs nearly to the ground (Velika Planina)"},{"label":"Structural design","value":"Eurocodes (EU member)"}],"related":["kozolec","wood-shingle","thatch","roofing-in-italy","roofing-in-austria","roofing-in-croatia","roofing-in-hungary"],"sources":[{"title":"Kozolec","url":"https://en.wikipedia.org/wiki/Kozolec","publisher":"Wikipedia"},{"title":"Past, Present and Future of Hay-making Structures in Europe (Sustainability, 2019)","url":"https://www.mdpi.com/2071-1050/11/20/5581","publisher":"MDPI Sustainability"},{"title":"Three countries seek to get hayracks onto UNESCO list","url":"https://english.sta.si/2364484/three-countries-seek-to-get-hayracks-onto-unesco-list","publisher":"Slovenian Press Agency (STA)"},{"title":"Velika Planina","url":"https://en.wikipedia.org/wiki/Velika_Planina","publisher":"Wikipedia"},{"title":"EN Eurocodes","url":"https://eurocodes.jrc.ec.europa.eu/","publisher":"European Commission Joint Research Centre"}]},{"slug":"roofing-in-somalia","title":"Roofing in Somalia","category":"world-roofing","type":"place","country":{"name":"Somalia","iso2":"SO"},"summary":"Somalia's roofs range from the nomadic aqal, a dome of saplings and woven mats, to medieval stone and coral-stone towns such as Mogadishu's Hamar Weyne.","body":"Somalia has two old roofing traditions. Pastoral nomads live in the aqal, a portable dome hut whose woven mats form both roof and walls. Along the coast and in the north, stone towns grew from the medieval period, with coral-stone, lime-washed buildings in Mogadishu and stone houses with flat roofs in ruined towns of the interior.\n\n## Climate and hazards\n\nSomalia is mostly hot and arid or semi-arid. The aqal is tied down so that strong winds cannot lift it, and its lowest mat can be removed in hot weather for ventilation.\n\n## Roofing history\n\n**Early stone towns.** At the ruined medieval towns of Amud and Abasa, 15th-century stone houses were entered from the roof, which was very likely flat and reached by steps that have since disappeared. After the arrival of Islam, building shifted from dry stone toward coral stone, sun-dried brick and limestone.\n\n**Mogadishu.** The old districts of Hamar Weyne and Shangani were built as close-packed whitewashed buildings of two to four storeys, finished with lime plaster and built partly of coral stone; old houses had wooden roof beams. Masjid Jaama'a, one of Mogadishu's oldest mosques, is dated to 1238 AD. The Fakr ad-Din Mosque of 1269, of marble and coral stone, uses composite beams with two main columns to carry its roof.\n\n**Colonial period.** Italian colonial rule added classical-style buildings in Mogadishu such as Villa Somalia and the Governor's Palace.\n\n## Traditional and vernacular roofs\n\n- **Aqal**: dome of bent saplings tied to central poles and covered with woven mats (see Aqal).\n- **Stone and coral houses**: roofs on timber beams in Mogadishu; the 15th-century stone houses of Amud were probably flat-roofed.\n\n## Roofing today\n\nIn Mogadishu's old town, one local author criticises later tile cladding on old walls for changing their whitewashed appearance.\n\n## Notable roofs\n\n- **Hamar Weyne, Mogadishu**: old coral-stone and lime district with mosques dating to the 13th century.\n- **Fakr ad-Din Mosque** (1269): early example of a composite-beam roof.\n\n## Local roofing terms\n\n- **aqal**: portable dome hut.\n- **udub**: central poles of the aqal.\n- **heego**: ring of saplings forming the aqal's dome.\n\n## Sources and gaps\n\nNo national building or roofing code was found in published sources. No information on domestic roofing manufacturers was found.\n\nDetails of coral-stone roof construction (for example the use of mangrove poles, as on the wider Swahili coast) are not documented for Somalia in published sources, nor were modern roof-material shares.","key_facts":[{"label":"Traditional dwelling","value":"Aqal (portable dome hut of saplings and mats)"},{"label":"Historic urban materials","value":"Coral stone, limestone, lime plaster"},{"label":"Early Mogadishu mosque","value":"Masjid Jaama'a, 1238 AD"},{"label":"Climate driver","value":"Heat, aridity, strong winds"}],"regions":["Africa"],"aliases":["Somali roofing","roofing in Somalia"],"related":["aqal","flat-roof","dome","roofing-in-djibouti","roofing-in-ethiopia","roofing-in-east-africa"],"company":null,"sources":[{"title":"The Somali aqal","url":"https://www.paukwa.or.ke/?p=14652","publisher":"Paukwa"},{"title":"Somali architecture","url":"https://en.wikipedia.org/wiki/Somali_architecture","publisher":"Wikipedia"},{"title":"The old town of Mogadishu (Hamar Weyne)","url":"https://www.liutprand.it/Hamarweyne eng.pdf","publisher":"Nurudiin Haji Shikei (Liutprand)"}]},{"slug":"roofing-in-south-africa","title":"Roofing in South Africa","category":"world-roofing","type":"place","country":{"name":"South Africa","iso2":"ZA"},"summary":"South African homes are mostly roofed in corrugated metal and tile, with a regulated thatching trade (SANS 10407) and shelter evidence back to Border Cave.","body":"South Africa has one of the most varied roofing landscapes in Africa. Corrugated iron and zinc sheet covers most homes, concrete and clay tiles dominate suburbs, and asbestos-cement sheets remain on many older houses. At the same time the country keeps a large, regulated thatching trade, which serves heritage homesteads, lodges and new houses, and is one of the few in Africa with a dedicated national thatch standard.\n\n## Climate and hazards\n\nClimates range from the winter-rainfall Western Cape to the summer-thunderstorm interior plateau and the humid KwaZulu-Natal coast. Lightning is a specific concern for roofs, particularly thatch: the Thatchers Association of South Africa (TASA) guide requires lightning protection where the ground flash density mapped under SANS 10313 exceeds 7 flashes per square kilometre per year, or 3 where wire sways could act as conductors. Fire spread between thatched buildings is the other main hazard addressed by regulation.\n\n## Roofing history\n\n**Stone Age.** Border Cave, a rock shelter in the Lebombo Mountains of KwaZulu-Natal near the Eswatini border, holds some of the oldest known evidence of people deliberately preparing places to rest. Layers dated about 227,000 to 179,000 years ago contain beds of grass (mainly Panicoideae), with sedges and leaves, laid near the back of the shelter; 48 bedding layers were identified, many with ash and charcoal showing repeated burning. The site shows people using a natural rock overhang as their roof long before any built shelter survives (see Border Cave).\n\n**Iron Age kingdoms.** Mapungubwe, at the confluence of the Limpopo and Shashe rivers, was the centre of a kingdom between about 900 and 1300 CE, with three successive capitals and palace sites set apart from commoners' settlements. It was inscribed on the World Heritage List in 2003 (decision 27 COM 8C.30) for a core area of nearly 30,000 ha (74,000 acres). Later Bantu-speaking societies built round, thatched houses; Zulu homesteads used hemispherical grass-thatched dwellings, while Sotho, Tswana and Ndebele groups developed cone-on-cylinder houses with mud walls and conical thatch.\n\n**Colonial period.** From the 17th century, Dutch settlers in the Cape built long whitewashed houses under steep thatch with plastered gables, the Cape Dutch style. In the 19th and 20th centuries corrugated galvanised iron spread across farms, mining towns and townships.\n\n**Modern era.** Factory-made concrete tiles, profiled steel sheeting and asbestos-cement sheets became standard in the 20th century. Today, profiled sheets such as IBR (inverted box rib) and corrugated sheet are the common covering for low-cost housing, farm buildings and industrial roofs.\n\n## Traditional and vernacular roofs\n\n- **Zulu hemispherical dwelling** (*indlu*): a frame of sapling arches (*izintingo*) covered in grass thatch in two layers, an inner insulating layer (*umfuguzelo*) and an outer layer (*umxhebulo*), tied down by ropes gathered into a top-knot (*isiqongo*). See Zulu beehive hut.\n- **Rondavel**: cylindrical wall with a conical thatched roof of radial poles and ring purlins, widespread on the interior plateau.\n- **Southern Ndebele homestead**: grass huts until the early 18th century, then mud-walled houses whose walls were painted; Ndebele terms include *amakapa* (roof), *apokorwana* (eaves overhang) and *isidlogorwana* (apex capping).\n- **Tswana and Pedi houses**: thatched conical roofs (Tswana *moteko*) over mud-plastered walls, often with a verandah carried on posts.\n- **Cape Dutch homestead**: steep thatch, often of Cape thatching reed, over H-shaped plans.\n\n## Roofing today\n\nIn the unweighted 2011 Census 10% sample file (about 1.19 million household records), the roof material is recorded as:\n\n| Roof material (H02A_ROOF) | Share of records |\n|---|---|\n| Corrugated iron/zinc | 55.8% |\n| Tile | 20.3% |\n| Asbestos | 10.8% |\n| Thatch/grass | 6.9% |\n| Cement block/concrete | 2.8% |\n| Wood | 1.0% |\n| Plastic, cardboard, wattle and daub, other | 2.2% |\n\nProfiled steel sheet is made in South Africa in galvanised (Z150 to Z275), aluminium-zinc (AZ150) and pre-painted finishes. A typical IBR profile covers 686 mm (27 in) per sheet in thicknesses from 0.40 to 0.80 mm (0.016 to 0.031 in), with a minimum pitch of 5 degrees for roof slopes under 30 m (98 ft) long and 7.5 degrees for longer slopes.\n\n## Codes, standards and regulation\n\nBuilding work falls under the National Building Regulations, whose deemed-to-satisfy rules are published as SANS 10400. Part L covers roofs: roof coverings, waterproofing of pitched roofs and drainage of flat roofs, with flat roofs typically laid to a fall of about 1:50. Part T covers fire protection. Under clause 4.12.2 of SANS 10400-T, thatched buildings with a roof area over 300 m² (3,230 sq ft), or closer than 4.5 m (14.8 ft) to a boundary, need additional fire-retardant measures. Thatch construction is specified in **SANS 10407** (edition 2, 2015); see SANS 10407 thatched roof construction.\n\n## Industry\n\nThe Thatchers Association of South Africa publishes a construction guide and represents thatchers. Thatching materials include common and fine thatching grass (*Hyparrhenia hirta*, *H. filipendula*) and Cape thatching reed (*Thamnochortus*, Afrikaans *dekriet*). Steel roll-formers produce IBR and corrugated profiles; Clotan Steel is one documented producer of IBR sheet.\n\n## Notable roofs\n\n- **Mapungubwe Cultural Landscape** (UNESCO 2003).\n- **Border Cave**: rock-shelter \"roof\" of some of the oldest known grass bedding.\n- **Cape Dutch homesteads** such as Groot Constantia, rebuilt after the 1925 fire.\n\n## Local roofing terms\n\n- *dekriet* (Afrikaans): Cape thatching reed.\n- *indlu* (isiZulu): dwelling; *inca* / *utshani*: grass; *isiqongo*: thatch top-knot.\n- *moteko* (Setswana): thatched roof covering; *setlhowa*: apex of a conical roof; *maribele*: eaves.\n- *amakapa* (isiNdebele): roof.\n- IBR: inverted box rib steel sheet.\n\n## Sources and gaps\n\nCensus shares are unweighted counts of records in the 10% sample file, not official population estimates. Published Census 2022 roof tables, figures for roofs in RDP (state-subsidised) housing and national production data for tiles and sheeting: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Corrugated iron/zinc, 55.8% (Census 2011 10% sample, unweighted)"},{"label":"Traditional materials","value":"Grass thatch, Cape thatching reed, mud walls"},{"label":"Building code","value":"National Building Regulations; SANS 10400-L (roofs), SANS 10400-T (fire)"},{"label":"Thatch standard","value":"SANS 10407 (2015)"},{"label":"Oldest shelter evidence","value":"Grass bedding at Border Cave, c. 200,000 years ago"}],"regions":["Africa"],"aliases":["South African roofing","roofing in South Africa"],"related":["roofing-in-southern-africa","cape-dutch-thatch","rondavel","zulu-beehive-hut","ndebele-house-painting","sans-10407-thatched-roof-construction","ibr-roof-sheeting","border-cave","corrugated-iron","asbestos-cement-roofing","concrete-roof-tile","clay-roof-tile","thatch","metal-roofs-and-lightning","roofing-in-lesotho","roofing-in-eswatini","roofing-in-namibia","roofing-in-botswana","roofing-in-zimbabwe","roofing-in-mozambique"],"company":null,"sources":[{"title":"South African Census 2011, 10% Sample: Construction material - Roof (H02A_ROOF)","url":"https://www.datafirst.uct.ac.za/dataportal/index.php/catalog/485/variable/V77","publisher":"DataFirst, University of Cape Town / Statistics South Africa"},{"title":"A Guide to Thatch Construction in South Africa (2016, Edition 1)","url":"https://www.vetiver.org/wp-content/uploads/2021/10/GUIDE-TO-THATCH-CONSTRUCTION-IN-SOUTH-AFRICA1.pdf","publisher":"Thatchers Association of South Africa"},{"title":"Roofs - Part L","url":"https://sans10400.org.za/roofs","publisher":"SANS 10400 (sans10400.org.za)"},{"title":"IBR sheeting technical data","url":"https://www.specifile.co.za/wp-content/uploads/2019/04/IBR.pdf","publisher":"Clotan Steel (via Specifile)"},{"title":"Border Cave","url":"https://en.wikipedia.org/wiki/Border_Cave","publisher":"Wikipedia"},{"title":"Mapungubwe Cultural Landscape","url":"https://whc.unesco.org/en/list/1099/","publisher":"UNESCO World Heritage Centre"},{"title":"Glossary - Zulu terms","url":"https://francofrescura.sahistory.org.za/glossary/glossary-zulu-terms/","publisher":"Franco Frescura / South African History Online"},{"title":"Glossary - Tswana terms","url":"https://francofrescura.sahistory.org.za/glossary/glossary-tswana-terms/","publisher":"Franco Frescura / South African History Online"},{"title":"Glossary - South Ndebele terms","url":"https://francofrescura.sahistory.org.za/glossary/glossary-south-ndebele-terms/","publisher":"Franco Frescura / South African History Online"},{"title":"Ndebele house painting","url":"https://en.wikipedia.org/wiki/Ndebele_house_painting","publisher":"Wikipedia"},{"title":"Decision 27 COM 8C.30: Mapungubwe Cultural Landscape (South Africa)","url":"https://whc.unesco.org/en/decisions/725","publisher":"UNESCO World Heritage Centre"}]},{"slug":"roofing-in-south-korea","title":"Roofing in South Korea","category":"world-roofing","type":"place","country":{"name":"South Korea","iso2":"KR"},"summary":"South Korean roofing: giwa clay tiles and choga rice-straw thatch, replaced from the 1970s by slate and concrete, with flat roofs on today's apartment towers.","body":"South Korea's traditional roofs belong to the *hanok*, the Korean house, which was roofed either with fired clay tiles (*giwa*) or with rice-straw thatch (*choga*). In the space of a few decades in the later 20th century the countryside was re-roofed with cement-based slate and tile, and the cities were rebuilt as high-rise apartment districts with flat concrete roofs. The legacy of asbestos-cement slate is now a public-health programme.\n\n## Climate and hazards\n\nThe peninsula has hot, humid summers with a monsoon rainy season and occasional typhoons, and cold, dry winters. Traditional roofs were tuned to this: the depth of the curved eaves (*cheoma*) blocks the high summer sun but lets low winter sun into the rooms, and thatch was renewed before the summer monsoon. On windy Jeju Island, thatched houses (*chojip*) were built low to withstand strong winds.\n\n## Roofing history\n\n**Prehistory.** Pit dwellings of the Mumun period had thatched roofs over wattle-and-daub walls; Chinese records describe early Korean houses with a grass-and-clay superstructure on a timber frame. Choga houses evolved from these Neolithic and Bronze Age dwellings, and rice-straw thatch is linked to the spread of rice cultivation by the Three Kingdoms period.\n\n**Tile.** Fired roof tiles derive from the Chinese tile tradition that developed under the Western Zhou and later spread to Korea. Tiles were used on official buildings in the Chinese commanderies on the peninsula after 108 BCE, and became established with Buddhism in the 4th century. Goguryeo palaces in Pyongyang used patterned tiles with ornate bracket systems; Baekje produced lotus-pattern roof-end tiles and in 588 sent tile makers to Japan; Silla tiles survive in large numbers from Gyeongju. Under Goryeo, celadon-glazed tiles were used on some elite buildings. Large halls carried their roofs on bracket sets, from simple Goguryeo brackets to the multi-bracket systems that developed from mid-Goryeo to early Joseon, and ridge ends carried owl-tail tiles called *chimi*.\n\n**Joseon to modern.** Tiled houses (*giwa-jip*) belonged mainly to the upper and middle classes, while choga was the dwelling of working people from prehistory to the mid-20th century. Choga began to decline in the 1960s with rapid industrialisation. The New Village Movement (*Saemaul Undong*), launched on 22 April 1970, spread orange-tiled houses through the countryside in place of thatched choga, and by the 1980s thatch had largely given way to cement and slate roofs. Many of these slates were asbestos-cement, containing about 10-15 per cent asbestos, and were widely used for roofs and ceilings from the 1970s.\n\n## Traditional and vernacular roofs\n\n- **Giwa-jip** - tiled hanok with heavy, gently curved roofs that turn up at the corners; roof-end tiles carry stamped motifs.\n- **Choga-jip** - rice-straw thatch, sometimes wheat straw or grass, renewed every one to three years as a community task.\n- **Roof forms** - the hip-and-gable *paljak* roof (*paljakjibung*) was the most common form for important Joseon buildings.\n- **Jeju chojip** - low thatched houses behind dry-stone walls (*chukdam*) that let strong winds pass through.\n\n## Roofing today\n\nApartment and commercial buildings, which house most of the population, have flat reinforced-concrete roofs waterproofed with membranes or liquid coatings, often with rooftop plant and increasingly solar panels and green roofs. Detached houses use asphalt shingles, coated steel sheet, or clay and concrete tiles. Since 2011 local governments have run subsidised **slate removal** programmes; Gwangju alone had removed or supported removal of 4,462 slate buildings by 2025, with grants for removal and, for low-income households, re-roofing.\n\n## Codes, standards and regulation\n\nBuilding work is governed by the **Building Act** and its Enforcement Decree. The decree treats work on roof trusses as a test of \"alteration\" and \"substantial repair\", with a specific exception for the rafters of hanok, reflecting government support for traditional construction.\n\n## Notable roofs\n\n- **Bukchon Hanok Village**, Seoul - designated a folk landscape area in 1976 and a hanok conservation zone in 1983.\n- **Jeonju Hanok Village** - more than 800 tiled hanok.\n- **Hahoe Folk Village** (UNESCO, with Yangdong) - tiled and thatched houses, some over 600 years old.\n- **Nakan Eupseong**, Suncheon - about 300 thatched houses re-thatched each year after the rice harvest.\n\n## Local roofing terms\n\n- *jibung* (지붕) - roof\n- *giwa* (기와) - roof tile\n- *choga* (초가) - thatched house, \"grass house\"\n- *cheoma* (처마) - eaves\n- *chimi* (치미) - owl-tail ridge-end tile\n- *paljakjibung* (팔작지붕) - hip-and-gable roof\n\n## Sources and gaps\n\nNational statistics on roof materials, the number of asbestos slate buildings remaining and industry data: published information is limited.","key_facts":[{"label":"Traditional coverings","value":"Giwa (clay tile), choga (rice straw)"},{"label":"Tile established","value":"4th century, with Buddhism"},{"label":"Thatch replaced","value":"From 1970 Saemaul Undong; largely gone by 1980s"},{"label":"Dominant modern roof","value":"Flat concrete (apartments)"},{"label":"Legacy issue","value":"Asbestos-cement slate, removal subsidies since 2011"},{"label":"Building law","value":"Building Act and Enforcement Decree"}],"regions":["East Asia"],"aliases":["Korean roofing","roofing in Korea"],"related":["hanok-roof","korean-giwa-history","choga","korean-asbestos-slate-roofs","irimoya","chiwen","dougong","asbestos-cement-roofing","clay-roof-tile","thatch","roofing-in-north-korea","roofing-in-japan","roofing-in-china"],"company":null,"sources":[{"title":"Hanok","url":"https://en.wikipedia.org/wiki/Hanok","publisher":"Wikipedia"},{"title":"Korean architecture","url":"https://en.wikipedia.org/wiki/Korean_architecture","publisher":"Wikipedia"},{"title":"Choga (architecture)","url":"https://en.wikipedia.org/wiki/Choga_(architecture)","publisher":"Wikipedia"},{"title":"Saemaul Undong","url":"https://en.wikipedia.org/wiki/Saemaul_Undong","publisher":"Wikipedia"},{"title":"Once Upon a Roof: Korean roof tiles","url":"https://asia.si.edu/once-upon-a-roof-gallery","publisher":"Smithsonian National Museum of Asian Art"},{"title":"Gwangju City urges removal of carcinogenic asbestos slate","url":"https://www.asiae.co.kr/en/article/2025032410080700119","publisher":"Asia Economy"},{"title":"Suncheon City to continue thatched roof repair at Nakan Eupseong","url":"https://www.asiae.co.kr/en/article/2025090416590339296","publisher":"Asia Economy"},{"title":"Enforcement Decree of the Building Act","url":"https://elaw.klri.re.kr/kor_service/lawViewMultiContent.do?hseq=69117","publisher":"Korea Legislation Research Institute"},{"title":"Bukchon Hanok Village","url":"https://en.wikipedia.org/wiki/Bukchon_Hanok_Village","publisher":"Wikipedia"},{"title":"Irimoya","url":"https://en.wikipedia.org/wiki/Irimoya","publisher":"Wikipedia"},{"title":"Researchers reconstruct earliest composite-tiled roofs","url":"https://phys.org/news/2023-07-reconstruct-earliest-composite-tiled-roofs.html","publisher":"Phys.org"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"}]},{"slug":"roofing-in-south-sudan","title":"Roofing in South Sudan","category":"world-roofing","type":"place","country":{"name":"South Sudan","iso2":"SS"},"summary":"In South Sudan most households live in round tukul huts with conical grass-thatch roofs; metal sheet covered only about 3% of homes in a 2010 survey sample.","body":"South Sudan, independent since 2011, is a country of savanna, forest and the vast Sudd wetland. Its characteristic dwelling is the tukul, a round hut of mud and poles under a conical thatched roof, and household survey data show that thatch remains by far the most common roof.\n\n## Climate and hazards\n\nThe climate is tropical with a long rainy season. In the south, heavy rains make sloping grass roofs necessary, and mud walls erode quickly: a new mud hut is said to last about one to two years, depending on rainfall and erosion.\n\n## Roofing history\n\nEarly 20th-century photographs give a documentary record. Between 1927 and 1930 the anthropologist E. E. Evans-Pritchard photographed Zande builders at Yambio in Western Equatoria working thatch of *bingba* grass (*Imperata cylindrica*) onto the framework of a hut roof that had been laid on the ground.\n\n## Traditional and vernacular roofs\n\n- **Tukul**: round hut built of mud, grass, millet stalks and wooden poles, with a thatched conical roof (see Tukul).\n- **Moru tukuls**: in Moru communities, walls are built from mud with stones, grass and cow manure, and builders are noted for making grass roofs watertight. A family home is usually a group of several tukuls arranged around an open space, for parents, children and a kitchen.\n- **Sod and palm roofs**: recorded as separate categories in household surveys.\n\n## Roofing today\n\nThe second South Sudan Household Health Survey (2010, a MICS survey) recorded the main roof material for about 9,400 households. Unweighted shares of sampled households (not official estimates) were:\n\n| Main roof material | Share of sampled households |\n|---|---|\n| Thatch / palm leaf | 60.2% |\n| Wood | 9.9% |\n| Palm / bamboo | 6.6% |\n| Sod | 6.1% |\n| Wood planks | 4.2% |\n| Other | 3.9% |\n| Metal | 3.2% |\n| No roof | 2.9% |\n| Rustic mat | 1.4% |\n| Roofing shingles | 1.3% |\n\nCement and tile roofs were almost absent from the sample.\n\n## Local roofing terms\n\n- **tukul**: round thatched hut.\n- **bingba** (Zande): thatching grass, *Imperata cylindrica*.\n- **hotnhial**: name given for the round hut in South Sudan in one encyclopedic list (language not stated).\n\n## Sources and gaps\n\nLittle archaeological information on roofing was found in published sources. No national building or roofing code was found. No information on domestic roofing manufacturers was found in published sources. No landmark roofs were documented in published sources.\n\nSurvey percentages are unweighted counts from one 2010 survey sample and predate independence and later conflict and displacement. Roof traditions of the Dinka, Nuer, Shilluk and other peoples: published information is limited.","key_facts":[{"label":"Most common roof (2010 survey sample, unweighted)","value":"Thatch / palm leaf, 60.2%"},{"label":"Metal sheet (same file)","value":"3.2%"},{"label":"Traditional dwelling","value":"Tukul (round hut, conical thatch)"},{"label":"Thatching grass (Zande)","value":"Bingba, Imperata cylindrica"}],"regions":["Africa"],"aliases":["South Sudanese roofing","roofing in South Sudan"],"related":["tukul","thatch","conical-roof","rondavel","corrugated-iron","roofing-in-sudan","roofing-in-ethiopia","roofing-in-east-africa"],"company":null,"sources":[{"title":"South Sudan Household Health Survey 2010: main material of the roof (HC4)","url":"https://microdata.worldbank.org/catalog/2588/variable/F3/V355?name=HC4","publisher":"World Bank Microdata Library"},{"title":"Zande hut roof construction (1998.341.668.2)","url":"https://southernsudan.prm.ox.ac.uk/details/1998.341.668.2/index.html","publisher":"Pitt Rivers Museum, University of Oxford"},{"title":"Moru tukuls according to traditional architecture","url":"https://africanmission.org/blog/moru-tukuls-according-to-traditional-architecture/","publisher":"African Mission"},{"title":"Tukul","url":"https://www.britannica.com/topic/tukul","publisher":"Encyclopaedia Britannica"},{"title":"Architecture of Sudan","url":"https://en.wikipedia.org/wiki/Architecture_of_Sudan","publisher":"Wikipedia"},{"title":"African round hut","url":"https://en.wikipedia.org/wiki/African_round_hut","publisher":"Wikipedia"}]},{"slug":"roofing-in-southeast-asia","title":"Roofing in Southeast Asia","type":"place","summary":"Overview of roofing in Thailand, Vietnam, Indonesia, the Philippines and Malaysia: steep tropical roofs, clay tile, thatch and widespread metal sheet.","body":"Southeast Asia is tropical, with heavy monsoon rains, high humidity, intense sun and, in the Philippines and Vietnam especially, typhoons. Traditional roofs across the region are steep, with deep eaves and well-ventilated roof spaces, usually over timber or bamboo houses raised on stilts.\n\n## Traditional forms\n\n- **Indonesia** - roofs are central to cultural identity, from the horned *gonjong* of the Minangkabau *rumah gadang*, thatched in sugar-palm fibre, to the boat-shaped bamboo roofs of the Toraja *tongkonan*. Clay tile is now very common: about 90% of houses on Java use clay roof tiles, a practice that spread among commoners only in the late 19th century under Dutch colonial encouragement.\n- **Philippines** - the *bahay kubo* has a tall, steep roof of nipa, cogon or anahaw thatch, sometimes laid as halved bamboo (*kalaka*). Colonial-era *bahay na bato* used curved Spanish tiles and later galvanised iron.\n- **Thailand, Laos and Cambodia** - tapered flat clay tiles have been used since at least the 9th or 10th century, and traditional houses are raised on stilts, often to head height, in flood-prone river and canal settlements.\n- **Vietnam** - ancient stilt houses had roofs that curved up like a boat or down like a turtle shell, and imperial palaces used glazed tile roofs in white, blue, yellow and green, while ordinary northern houses were timber or thatched.\n\n## Modern roofing\n\nCorrugated and profiled steel sheet, often zinc-aluminium coated and pre-painted, is now the most widespread roofing across the region's towns and villages because it is cheap and fast to install. Concrete and clay tiles are common on suburban houses, and reinforced concrete flat roofs are standard on urban shophouses, tube houses and apartment blocks. Many traditional roofs, including those of rumah gadang and tongkonan, are now re-covered with corrugated metal.\n\n## Climate considerations\n\nKey design concerns are rapid rainwater shedding, generous overhangs, ventilation of hot roof spaces, insulation or reflective coatings under metal sheet to reduce heat and rain noise, and secure fixing against typhoon winds.","key_facts":[{"label":"Climate","value":"Tropical monsoon, typhoons in places"},{"label":"Java clay tile use","value":"About 90% of houses"},{"label":"Traditional coverings","value":"Thatch, bamboo, clay tile"},{"label":"Most widespread modern covering","value":"Coated steel sheet"}],"regions":["Southeast Asia"],"aliases":["ASEAN roofing","Thai roofing","Vietnamese roofing","Indonesian roofing","Philippine roofing","Malaysian roofing"],"related":["rumah-gadang","tongkonan","bahay-kubo","clay-roof-tile","metal-roofing"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Architecture of Vietnam","url":"https://en.wikipedia.org/wiki/Architecture_of_Vietnam","publisher":"Wikipedia"},{"title":"Architecture of Thailand","url":"https://en.wikipedia.org/wiki/Architecture_of_Thailand","publisher":"Wikipedia"},{"title":"Nipa hut","url":"https://en.wikipedia.org/wiki/Nipa_hut","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-southern-africa","title":"Roofing in Southern Africa","type":"place","summary":"Overview of Southern African roofing: thatched rondavels and Cape Dutch homes, widespread corrugated iron, and concrete and clay tiles in suburbs.","body":"Southern Africa, including South Africa, Namibia, Botswana, Zimbabwe, Lesotho and Eswatini, combines strong thatch traditions with heavy use of corrugated metal and, in cities, concrete and clay tiles. Climates range from the winter-rainfall Western Cape to summer-thunderstorm highveld and dry interiors.\n\n## Thatch traditions\n\n- **Rondavels** - round houses with conical thatched roofs, found in South Africa, Lesotho (*mokhoro*), Eswatini and Botswana. The cone is built of radial principals and circular purlins without internal posts, and grass thatch is sewn on in bands from the eaves upward.\n- **Cape Dutch** - homesteads of the Western Cape, from the 17th century, with H-shaped plans, steep thatched roofs and ornate plastered gables.\n\nSouth Africa remains a significant thatching country, with thatch used on lodges, homes and heritage buildings, and it also exports thatching reed to Europe. Fire is the main risk, illustrated by the 1925 fire that destroyed the Groot Constantia manor house near Cape Town.\n\n## Corrugated metal\n\nCorrugated iron, widely used since the colonial period, is the most common roof on rural houses, informal settlements and farm buildings, and many rondavels now have metal rather than thatch roofs. Modern versions use galvanised or zinc-aluminium-coated steel, often pre-painted, in corrugated, box-rib and standing seam profiles.\n\n## Tiles and concrete\n\nConcrete roof tiles and clay tiles are standard on suburban houses in South Africa, while reinforced concrete flat roofs with membranes are common on commercial and multi-storey buildings.\n\n## Standards\n\nSouth Africa's National Building Regulations and their supporting national standards govern roof structure, fire and energy efficiency, and specific rules apply to thatched roofs because of fire spread between buildings.\n\n## Hazards\n\nHail on the highveld, strong winds in coastal areas and lightning, especially relevant to thatch, are key roofing hazards.","key_facts":[{"label":"Thatch traditions","value":"Rondavel, Cape Dutch"},{"label":"Common rural covering","value":"Corrugated iron"},{"label":"Suburban covering","value":"Concrete and clay tile"},{"label":"Hazards","value":"Hail, lightning, fire, wind"}],"regions":["Africa"],"aliases":["South African roofing","Southern African roofing"],"related":["rondavel","cape-dutch-thatch","thatch","corrugated-iron","roofing-in-east-africa"],"sources":[{"title":"Rondavel","url":"https://en.wikipedia.org/wiki/Rondavel","publisher":"Wikipedia"},{"title":"Cape Dutch architecture","url":"https://en.wikipedia.org/wiki/Cape_Dutch_architecture","publisher":"Wikipedia"},{"title":"Groot Constantia","url":"https://en.wikipedia.org/wiki/Groot_Constantia","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-spain","title":"Roofing in Spain","category":"world-roofing","type":"place","country":{"name":"Spain","iso2":"ES"},"regions":["Europe"],"company":null,"summary":"How Spain roofs its buildings: curved clay teja árabe across the centre and south, natural slate in the rainy north-west, and flat azoteas in dry areas.","aliases":["Spanish roofing","Tejados en España","Cubiertas en España"],"body":"Spain's roofs follow its climate and geology. The rainy Atlantic north-west is the heartland of natural slate, the drier centre, east and south are roofed with curved clay tiles, and flat roof terraces are common in low-rainfall areas and on modern apartment blocks. Spanish tile and building traditions also travelled with Spanish settlement to the Americas and Asia.\n\n## Climate and hazards\n\nA Spanish roof may need to cope with Atlantic rain and wind in Galicia and Asturias, winter snow in the mountains, and long, hot, dry summers in the interior and the Mediterranean south and east. Traditional building answered these conditions directly: the thatched pallozas of the Ancares range sit at around 1,200 m (3,900 ft) and were built to withstand severe winters, while the flat *azotea* is typical of places with little rain. Structural actions such as snow, wind and earthquake loads are dealt with under the national building code and the Eurocodes (see below).\n\n## Roofing history\n\nThe oldest roof form traceable in the north-west is the round, thatched house. Ethnographers link the stone-walled, straw-roofed *palloza* to the circular buildings of the pre-Roman Castro culture and other Atlantic Iron Age peoples, although the palloza is larger and housed animals as well as people.\n\nFired clay tiles came with Roman rule. The curved tile now called *teja árabe* (\"Arab tile\") is, despite its name, of Roman origin; it is named after its very wide use in al-Andalus, the Muslim-ruled Iberian Peninsula. Glazed tiles were later used decoratively, for example in Aragonese Mudéjar work. Raised granaries (*hórreos*) are documented in the north from the 9th century, the oldest written use of the word dating from the year 800, and the oldest surviving examples from the 15th century.\n\nWith Spanish colonisation, tile roofing spread to the Americas and Asia. In California, clay tiles were first produced at Mission San Antonio de Padua in 1780, and colonial churches in Central America, such as Santa Lucía in Honduras, still carry Roman-style pan-and-cover roofs. In Catalonia and Valencia the thin brick \"Catalan vault\", laid in layers of flat bricks without formwork, became famous through Antoni Gaudí and Rafael Guastavino; the name was coined at an architectural congress in Madrid in 1904.\n\n## Traditional and vernacular roofs\n\n- **Teja árabe:** a single tapered half-cone of fired clay that can serve as channel (*canal*), cover (*cobija*), ridge (*cumbrera*) and valley or hip (*lima*). Rows of channels collect rain and the covers seal the joints.\n- **Teja a la segoviana:** a Castilian variant using only channel tiles bedded on clay, with no covers.\n- **Laying methods:** *teja vana* tiles rest loose on battens over rafters, which ventilates well but needs yearly maintenance after storms; *a la provenzal* adds triangular timber supports under the channels; the modern method sets tiles on a solid deck, with channels nailed or every sixth or seventh row of covers bedded in mortar.\n- **Slate:** in Galicia and neighbouring León, local slate is the traditional covering.\n- **Palloza:** circular or oval stone houses 10-20 m (33-66 ft) across with conical rye-straw thatch and no chimney, found in the Ancares, El Bierzo and western Asturias.\n- **Azotea:** a flat, accessible roof used for drying laundry, water tanks and, today, solar equipment.\n\n## Roofing today\n\nNew houses typically use clay or concrete interlocking tiles on pitched roofs, or flat roofs waterproofed with membranes. Slate remains common in the north-west.\n\n## Codes, standards and regulation\n\nThe *Código Técnico de la Edificación* (CTE) was approved by Royal Decree 314/2006 of 17 March. Its basic documents cover structural safety, fire safety, safety in use and accessibility, energy saving, noise protection and health and moisture (*salubridad*), which together govern roof structure, fire behaviour, insulation and waterproofing. A draft royal decree modifying the CTE, partly transposing EU Directive 2024/1275 on the energy performance of buildings, went to public consultation in late 2025. As an EU member, Spain also applies the Eurocodes for structural design.\n\n## Industry\n\nSpain is the world's largest producer and exporter of natural roofing slate and the source of about 90% of the natural slate used for roofing in Europe. Most comes from Galicia, where the larger producers are concentrated in Valdeorras (Ourense), with other workings at Quiroga, Ortigueira and Mondoñedo. The Palaeozoic deposits are more than 500 million years old, and good Spanish slate absorbs less than 0.4% water, which gives strong frost resistance. It is usually fixed with hooks rather than nails. The traditional tile works is a *tejar* or *tejería*.\n\n## Notable roofs\n\n- **Hórreo of Carnota (A Coruña):** one of the longest hórreos, about 35 m (115 ft).\n- **Pallozas of Piornedo (Lugo):** a group of 14 pallozas listed as a *Bien de Interés Cultural*; one has been an ethnographic museum since the 1970s.\n- **Catalan vaults:** the thin-tile vaults of Gaudí and Guastavino.\n\n## Local roofing terms\n\n- *tejado* - pitched tiled roof; *cubierta* - roof (general)\n- *teja árabe* / *teja curva* - curved clay tile\n- *canal* / *cobija* - channel tile / cover tile\n- *cumbrera* - ridge; *lima* - hip or valley\n- *azotea* - flat roof terrace\n- *teito* - thatch (Galician-Asturian), as in *casa de teito*\n- *hórreo*, *panera* - raised granaries with tiled, slate, thatched or slab roofs\n\n## Sources and gaps\n\nCensus data on roof materials and information on Spanish clay-tile manufacturers: published information is limited.","key_facts":[{"label":"Dominant traditional tile","value":"Curved clay teja árabe (Roman origin)"},{"label":"Slate","value":"About 90% of Europe's natural roofing slate; mainly Galicia"},{"label":"Vernacular thatch","value":"Palloza, rye-straw conical roof (Ancares)"},{"label":"Building code","value":"Código Técnico de la Edificación (RD 314/2006)"},{"label":"Flat roofs","value":"Azotea, in low-rainfall areas"}],"related":["spanish-mediterranean-terracotta-roof","spanish-slate","spanish-tile","mission-tile","imbrex-and-tegula","catalan-vault","palloza","natural-slate","clay-roof-tile","thatch","flat-roof","roofing-in-portugal","roofing-in-france","roofing-in-mexico"],"sources":[{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"},{"title":"Slate industry","url":"https://en.wikipedia.org/wiki/Slate_industry","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Catalan vault","url":"https://en.wikipedia.org/wiki/Catalan_vault","publisher":"Wikipedia"},{"title":"Teja","url":"https://es.wikipedia.org/wiki/Teja","publisher":"Wikipedia (Spanish)"},{"title":"Azotea","url":"https://es.wikipedia.org/wiki/Azotea","publisher":"Wikipedia (Spanish)"},{"title":"Palloza","url":"https://en.wikipedia.org/wiki/Palloza","publisher":"Wikipedia"},{"title":"Palloza","url":"https://es.wikipedia.org/wiki/Palloza","publisher":"Wikipedia (Spanish)"},{"title":"Hórreo","url":"https://en.wikipedia.org/wiki/H%C3%B3rreo","publisher":"Wikipedia"},{"title":"Código Técnico de la Edificación","url":"https://www.codigotecnico.org/","publisher":"Ministerio de Vivienda y Agenda Urbana (Spain)"},{"title":"EN Eurocodes","url":"https://eurocodes.jrc.ec.europa.eu/","publisher":"European Commission Joint Research Centre"}]},{"slug":"roofing-in-sri-lanka","title":"Roofing in Sri Lanka","category":"world-roofing","type":"place","country":{"name":"Sri Lanka","iso2":"LK"},"summary":"Most Sri Lankan homes have asbestos-cement sheet or clay tile roofs; older roofs range from the bronze-tiled Lovamahapaya to Kandyan tiled image houses.","body":"Sri Lanka, the tropical island off the southern tip of India, has a long and well-recorded building tradition centred on timber-framed, tiled or thatched pitched roofs with generous overhangs. Its ancient capital at Anuradhapura had a nine-storey monastic hall roofed in bronze tiles, and the Kandyan kingdom of the central hills developed distinctive tiled image houses. Today most homes are roofed with corrugated asbestos-cement sheet or clay tiles.\n\n## Climate and hazards\n\nThe island has a tropical climate with two monsoons: the south-west monsoon in the middle of the year and the north-east monsoon around the turn of the year, giving heavy rainfall, especially in the south-west and the central hills. Roofs must shed intense rain and resist strong winds. Sri Lanka also faces floods, landslides in the hill country, storms and cyclones, and the Indian Ocean tsunami of 2004 devastated much of its coast.\n\n## Roofing history\n\n**Anuradhapura period.** The Mahavihara monastery at Anuradhapura contained the **Lovamahapaya** (Lohaprasada, \"Brazen Palace\"), a nine-storey hall attributed to King Dutugemunu, standing on 1,600 stone pillars in 40 rows of 40, with a side about 120 m (400 ft) long. Its roof was covered with bronze tiles, which gave the building its name. It was destroyed in antiquity; a small modern building now stands on the site. Early rock-cut cave temples, such as those at Mihintale, had a carved drip ledge along the rock overhang to keep rainwater out of the cave.\n\n**Kandyan period.** In the hill kingdom of Kandy (16th to early 19th centuries), Buddhist image houses called **tampita vihara** were raised on stone pillars and roofed with two-pitched timber roofs covered with flat clay tiles; most surviving examples date from the 16th and 17th centuries. Village houses of the period, such as the courtyard house *hatara-endi-ge*, had timber roofs thatched with straw, and commoners' huts had overhanging thatched roofs over a front verandah (*pila*).\n\n**Colonial and modern.** Portuguese, Dutch and British rule over almost five centuries introduced European building types on the coast and in Colombo. In the 20th century the architect Geoffrey Bawa became known for combining traditional elements, including terracotta-tiled pitched roofs, with modernist design.\n\n## Traditional and vernacular roofs\n\n- **Tampita vihara**: image house on stone pillars with a two-pitched, flat-tile-covered timber roof.\n- **Hatara-endi-ge**: square courtyard house with blank outer walls and a straw-thatched timber roof.\n- **Wallauwe**: larger manor house of the rural elite, with several courtyards.\n- **Thatched huts**: overhanging thatched roofs on simple timber frames, an image of the village that began to vanish after the *Gam Udava* village programme of the 1980s.\n\n## Roofing today\n\nPreliminary results of the 2024 Census of Population and Housing show that **53.2% of housing units are roofed with asbestos sheets** and **33.7% with tiles**. Roofing varies by district: in Mannar 87.3% of roofs are tiled, the highest share in the country, while Polonnaruwa has the highest share of asbestos roofs at 75.5%. In Badulla 5.7% of units have roofs of non-durable materials.\n\n## Codes, standards and regulation\n\nAgencies involved in building regulation include the Ministry responsible for housing and construction, the **Urban Development Authority (UDA)**, the **National Building Research Organisation (NBRO)**, the **Construction Industry Development Authority (CIDA)** and local authorities such as the Colombo Municipal Council. A World Bank-supported assessment in 2019 recommended a new Sri Lanka building code adapted to local hazards, and reducing gaps and overlaps between existing laws and institutions.\n\n## Notable roofs\n\n- **Lovamahapaya, Anuradhapura**: ancient nine-storey hall famous for its bronze-tiled roof.\n- **Tampita viharas** of the Kandyan region (16th-17th centuries): tiled image houses on stone pillars.\n\n## Local roofing terms\n\n- *tampita vihara* (Sinhala): image house raised on pillars\n- *hatara-endi-ge* (Sinhala): courtyard house\n- *pila* (Sinhala): front verandah\n- *wallauwe* (Sinhala): manor house\n\n## Sources and gaps\n\nInformation on individual domestic roofing manufacturers and on hazard requirements for roofs was not found in published sources; the 2024 census figures are preliminary.","key_facts":[{"label":"Dominant material today","value":"Asbestos sheet, 53.2% of housing units (Census 2024, preliminary)"},{"label":"Clay tile roofs","value":"33.7% of housing units (Census 2024, preliminary)"},{"label":"Traditional materials","value":"Straw and palm thatch, flat clay tiles, timber"},{"label":"Climate driver","value":"Two monsoons, heavy rain, cyclones, tsunami"},{"label":"Regulators","value":"UDA, NBRO, CIDA; national building code in development"},{"label":"Ancient roof","value":"Lovamahapaya, roofed with bronze tiles"}],"regions":["South Asia"],"aliases":["Sri Lankan roofing","Ceylon roofing","roofs of Sri Lanka"],"related":["asbestos-cement-roofing","clay-roof-tile","palm-thatch","thatch","corrugated-fibre-cement-sheet","hip-roof","roofing-in-india","roofing-in-the-maldives","kerala-sloping-roof","mangalore-tile"],"company":null,"sources":[{"title":"Uptick in living conditions as houses and housing units on the rise, census reveals","url":"https://www.sundaytimes.lk/251109/news/uptick-in-living-conditions-as-houses-and-housing-units-on-the-rise-census-reveals-620511.html","publisher":"The Sunday Times (Sri Lanka)"},{"title":"From Tempita Vihara to Hatara Endi Ge: the gentle architecture of rural Lanka","url":"https://thearchitect.lk/2013/10/from-tempita-vihara-to-hatara-endi-ge-the-gentile-architecture-of-rural-lanka","publisher":"The Architect (Sri Lanka Institute of Architects)"},{"title":"Lovamahapaya","url":"https://en.wikipedia.org/wiki/Lovamahapaya","publisher":"Wikipedia"},{"title":"Architecture of Sri Lanka","url":"https://en.wikipedia.org/wiki/Architecture_of_Sri_Lanka","publisher":"Wikipedia"},{"title":"Building regulations for resilience in Sri Lanka and the Maldives","url":"https://www.worldbank.org/en/news/feature/2019/07/15/building-regulations-for-resilience-in-sri-lanka-and-the-maldives-drmhubtokyo","publisher":"World Bank"}]},{"slug":"roofing-in-sudan","title":"Roofing in Sudan","category":"world-roofing","type":"place","country":{"name":"Sudan","iso2":"SD"},"summary":"Sudan's roofs range from Nubian mud-brick vaults and flat clay roofs to thatched round huts; thatch, local earth roofs and metal sheet dominate today.","body":"Sudan spans the Nile valley of ancient Nubia, the Sahara in the north and savanna to the south and west. Its roofs reflect that range: the Nubian vault, one of Africa's oldest earth-roofing techniques, comes from the northern Nile; flat roofs of dried clay cover the box-houses of towns such as Omdurman; and thatched conical roofs top round huts further south. Survey data show thatch, local earth roofs and metal sheet as the main roof materials today.\n\n## Climate and hazards\n\nThe north is hot desert, where flat earth roofs work well. Rainfall increases southward, and heavy rains there make sloping grass roofs necessary. Heat, dust storms and seasonal downpours are the main roof loads.\n\n## Roofing history\n\n**Prehistory and Kush.** Round huts are recorded in the Butana Group settlements of eastern Sudan from around 4000 BC. The kingdom of Kush built very large mud-brick temples known as *deffufa*, and Kushite dwellings were of mud brick with wood and stone floors.\n\n**Medieval and Islamic periods.** Christian Nubian kingdoms (c. 500-1500 AD) built churches, monasteries and palaces, including Faras Cathedral. Under Turco-Egyptian rule (1821-1885), domed tombs (*qubba*) were built for Ottoman officials in Khartoum.\n\n**The box-house.** The traditional Sudanese box-house has a flat roof of dried clay, sun-dried mud, brick or cow-dung plaster (*zibala*), with timber used only for roofs, doors and windows. The box-house in Omdurman built under the Khalifa Abdallahi (1885-1898) is cited as the most complete surviving example.\n\n**Nubian vault.** In Nubia, along the Nile in southern Egypt and northern Sudan, masons built barrel vaults of sun-dried brick without formwork. The technique was revived in Egypt by Hassan Fathy in the 1940s and has been promoted in the Sahel since 2000 (see Nubian vault).\n\n**20th century.** In Khartoum, government buildings along Nile Street were built in European styles between 1900 and 1912. The Austrian architect Peter Muller, who worked in Khartoum until 1965, introduced free-standing roof shading in place of roof gardens.\n\n## Traditional and vernacular roofs\n\n- **Flat clay roofs** on box-houses (see Mud roof and Flat roof).\n- **Nubian vaults and domes** in the northern Nile valley.\n- **Conical thatched roofs** on round huts of dried mud, grass, stalks and poles, widespread in the south (see Tukul).\n- **Tents**: nomadic peoples such as the Beja and Baggara often live in tents.\n- **Qubba**: masonry domes over saints' and rulers' tombs.\n\n## Roofing today\n\nThe Sudan Multiple Indicator Cluster Survey 2014 recorded the main roof material for about 16,800 households. Unweighted shares of sampled households (not official estimates) were:\n\n| Main roof material | Share of sampled households |\n|---|---|\n| Thatch / palm leaf | 42.7% |\n| \"Local roof\" | 25.0% |\n| Metal | 20.7% |\n| Cement | 3.6% |\n| Other | 2.5% |\n| Rustic mat | 1.6% |\n| Wood | 1.4% |\n\nThe codebook does not define the \"local roof\" category, which accounts for a quarter of cases. Cement roofs were recorded for under 4% of cases.\n\n## Notable roofs\n\n- **Omdurman box-house** of the Khalifa's period (1885-1898): cited as the most complete example of the flat-roofed box-house.\n- **Turco-Egyptian qubba tombs**, Baladiya Street, Khartoum.\n- **Al-Nilin Mosque, Omdurman** (mid-1970s): a modern mosque with a distinctive dome.\n\n## Local roofing terms\n\n- **zibala**: cow-dung plaster used on roofs.\n- **qubba**: domed tomb.\n\n## Sources and gaps\n\nNo national roofing code was found in published sources. No information on domestic roofing manufacturers was found.\n\nSurvey percentages are unweighted counts from one survey sample. Construction details of Nubian village roofs in Sudan, and the effects of conflict since 2023 on housing: published information is limited.","key_facts":[{"label":"Most common roof (MICS 2014 file, unweighted)","value":"Thatch / palm leaf, 42.7%"},{"label":"Metal roofs (same file)","value":"20.7%"},{"label":"Traditional forms","value":"Flat clay roofs, Nubian vaults, thatched round huts"},{"label":"Climate driver","value":"Desert heat in the north; heavy rains in the south"}],"regions":["Africa","Middle East"],"aliases":["Sudanese roofing","roofing in Sudan"],"related":["nubian-vault","tukul","mud-roof","flat-roof","thatch","corrugated-iron","roofing-in-egypt","roofing-in-south-sudan","roofing-in-ethiopia","roofing-in-eritrea","hassan-fathy"],"company":null,"sources":[{"title":"Architecture of Sudan","url":"https://en.wikipedia.org/wiki/Architecture_of_Sudan","publisher":"Wikipedia"},{"title":"Sudan Multiple Indicator Cluster Survey 2014: main material of roof (HC4)","url":"https://microdata.worldbank.org/index.php/catalog/2656/variable/F4/V357?name=HC4","publisher":"World Bank Microdata Library"},{"title":"Tukul","url":"https://www.britannica.com/topic/tukul","publisher":"Encyclopaedia Britannica"}]},{"slug":"roofing-in-suriname","title":"Roofing in Suriname","category":"world-roofing","type":"place","country":{"name":"Suriname","iso2":"SR"},"summary":"Surinamese roofing: Paramaribo's UNESCO-listed timber houses with steep roofs, mostly of corrugated iron, rebuilt after the fires of 1821 and 1832.","body":"Suriname, the former Dutch colony on the north-east coast of South America, is best known architecturally for the historic inner city of Paramaribo, a Dutch colonial town built almost entirely of wood. Its steep-roofed timber houses on brick bases reflect Dutch building traditions adapted to a hot, wet tropical climate.\n\n## Climate and hazards\n\n- **Heavy tropical rain and humidity**, favouring steep roofs and raised floors.\n- **Fire**: UNESCO notes that Paramaribo's timber buildings are vulnerable to fire, and fires in 1821 and 1832 destroyed some 450 houses.\n- **Low coastal land** along rivers and the Atlantic.\n\n## Roofing history\n\nParamaribo was laid out from 1683. Fort Zeelandia dates from 1667, the Presidential Palace from 1730 (stone with a wooden upper floor), the Reformed Church from 1837 and the brick Ministry of Finance from 1841. The Roman Catholic cathedral of 1885 is a Gothic Revival building in wood.\n\nAfter the great fires of 1821 and 1832, much of the town was rebuilt by local craftsmen in timber. The ICOMOS evaluation prepared for the UNESCO nomination in 2002 describes the typical building as rectangular and symmetrical in plan, entirely of wood on a brick substructure, with steep roofs mostly of corrugated iron sheet. Walls are generally painted white, with brick elements in red and doors and shutters in dark green. More than 250 buildings are listed as of historic interest. Some timber buildings have been replaced with concrete.\n\n## Traditional and vernacular roofs\n\n- **Paramaribo timber house**: steep roof, now usually of corrugated iron, over a white-painted timber house on a brick base.\n\n## Roofing today\n\nCorrugated metal sheet is the dominant roof in the historic city.\n\n## Notable roofs\n\n- **Historic Inner City of Paramaribo** (UNESCO 2002): timber houses and public buildings with steep roofs.\n- **Roman Catholic cathedral**, Paramaribo (1885), a wooden Gothic Revival church.","key_facts":[{"label":"Historic city","value":"Paramaribo, UNESCO 2002"},{"label":"Typical roof","value":"Steep, mostly corrugated iron sheet"},{"label":"Walls","value":"Timber on brick substructure"},{"label":"Great fires","value":"1821 and 1832, about 450 houses"}],"regions":["Latin America"],"aliases":["Surinamese roofing"],"related":["corrugated-iron","wood-shingle","roofing-in-guyana","roofing-in-the-netherlands","roofing-in-brazil"],"company":null,"sources":[{"title":"Historic Inner City of Paramaribo","url":"https://whc.unesco.org/en/list/940","publisher":"UNESCO World Heritage Centre"},{"title":"ICOMOS evaluation: The Historic Inner City of Paramaribo (No 940rev), 2002","url":"https://whc.unesco.org/document/154638","publisher":"ICOMOS / UNESCO"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"}]},{"slug":"roofing-in-sweden","title":"Roofing in Sweden","category":"world-roofing","type":"place","country":{"name":"Sweden","iso2":"SE"},"summary":"Swedish roofing: turf and birch bark, tarred pine shingles on churches, Stockholm tar, and today's concrete tiles, steel sheet and felt, designed for snow.","body":"Sweden's roofing grew out of a timber culture. Rural log houses were roofed for centuries with birch bark and turf, churches and bell towers with split and tarred wooden shingles, and towns gradually adopted clay tile, copper and sheet metal. Since the 1960s, concrete roof tiles have become the most common covering on Swedish houses, with steel sheet and felt also widely used.\n\n## Climate and hazards\n\nSweden stretches from temperate Skåne in the south to sub-Arctic Lapland. Snow load, freeze-thaw and long wet seasons are the main concerns, and in the north snow lies on roofs for months. Fire has been the main hazard for timber buildings: UNESCO identifies fire as the greatest threat to the decorated timber farmhouses of Hälsingland.\n\n## Roofing history\n\nWood tar, essential to Nordic roofing, has a very long history in Sweden. Cone-shaped pits north of Uppsala show chemical traces of pine tar production, and radiocarbon dating places the oldest between 540 and 380 BC, possibly the oldest surviving tar production site known. Large-scale tar production began in Finland, then part of the Swedish realm, in the early 17th century, and by the late 17th century tar was Sweden's third most valuable export; in present-day Sweden large-scale production started around 1700. Swedish tar was sold internationally as \"Stockholm tar\". Production peaked around the mid-1850s.\n\nIn the Viking Age and the Middle Ages most Scandinavian houses had turf roofs over birch bark, while churches and steep roofs used boards, wooden shingles or lead. In the Middle Ages almost all Swedish buildings, urban and rural, were of timber. From the 12th century stone became the usual material for monasteries and churches, and brick followed for the Gothic cathedrals of Västerås, Strängnäs and Uppsala. About 1,500 of Sweden's roughly 4,000 churches date from the Middle Ages.\n\nTurf remained almost universal on rural roofs until the early 18th century. Tile, already common in towns and on manors, gradually replaced it during the 19th century, with corrugated iron adding further pressure. In 1965 the government announced the Million Programme, aiming to build a million dwellings in ten years, which produced large numbers of apartment blocks.\n\n## Traditional and vernacular roofs\n\n- **Torvtak:** turf over layered birch bark on log houses, shared with Norway and Finland. See Scandinavian sod roofs.\n- **Shingle roofs:** thin wooden shingles coated with wood tar on churches and other steep roofs, continuing the medieval practice of covering high-status buildings with boards, shingles or lead.\n- **Halland seaweed houses:** houses roofed with eelgrass, like those on Læsø in Denmark, once existed in Halland on the Swedish Kattegat coast; none remain.\n- **Hälsingland farmhouses:** large 18th- and 19th-century timber farmhouses with richly painted festive rooms. Their traditional roof coverings have been replaced with modern materials to protect the interiors, the one departure from traditional repair methods noted by UNESCO.\n\n## Roofing today\n\nConcrete roof tiles are generally described as Sweden's most popular roofing material. The double-barrel concrete pantile has been the most laid roof tile in Sweden since the 1960s, according to its leading producer. Profiled and seamed steel sheet, clay tile, bitumen roofing felt (*takpapp*) and shingles are also common. A 2025-2026 Swedish consumer guide gave typical service lives of 40-60 years for concrete tiles and steel sheet, 50-100 years or more for clay tiles and 15-30 years for felt. Large flat roofs on apartment, commercial and industrial buildings use bituminous and synthetic membranes.\n\n## Codes, standards and regulation\n\nThe national building agency Boverket issues Boverket's building regulations (BBR), which contain mandatory provisions and general recommendations for new buildings and alterations. Structural design, including snow loads, follows the Eurocodes; snow is covered by Eurocode 1, Part 1-3.\n\n## Industry\n\n- **Benders** (Benders Sverige AB) describes itself as the market leader in concrete roofing in Sweden and has made roof tiles for several decades.\n- **Nordic Waterproofing**, based in Helsingborg, supplies bituminous membranes, EPDM and green-roof systems across the Nordic region. See Nordic Waterproofing.\n- Swedish steel group SSAB owns the Finnish steel roofing supplier Ruukki. See Ruukki.\n\n## Notable roofs\n\n- **Decorated Farmhouses of Hälsingland**: seven timber farmhouses on the UNESCO World Heritage List.\n- Sweden's medieval parish churches, built first of timber and later of stone and brick.\n\n## Local roofing terms\n\n- *torvtak* - turf roof\n- *takpapp* - roofing felt\n- *Stockholmstjära* (\"Stockholm tar\") - the export name for Swedish pine tar\n\n## Sources and gaps\n\nSwedish census data on roof materials and dates for specific historic shingle roofs: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Concrete roof tiles"},{"label":"Traditional materials","value":"Turf over birch bark; tarred pine shingles"},{"label":"Oldest tar pits","value":"540-380 BC, north of Uppsala"},{"label":"Building regulations","value":"Boverket's building regulations (BBR)"}],"regions":["Europe","Arctic"],"aliases":["Swedish roofing","roofs in Sweden"],"related":["scandinavian-sod-roofs","torvtak","roofing-in-scandinavia","wood-shingle","concrete-roof-tile","birch-bark-roofing","laeso-seaweed-roof","nordic-waterproofing","ruukki","roofing-in-norway","roofing-in-finland","roofing-in-denmark"],"company":null,"sources":[{"title":"Pine tar","url":"https://en.wikipedia.org/wiki/Pine_tar","publisher":"Wikipedia"},{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"},{"title":"Architecture of Sweden","url":"https://en.wikipedia.org/wiki/Architecture_of_Sweden","publisher":"Wikipedia"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"},{"title":"Decorated Farmhouses of Hälsingland","url":"https://whc.unesco.org/en/list/1282","publisher":"UNESCO World Heritage Centre"},{"title":"Boverket's building regulations – mandatory provisions and general recommendations (BBR)","url":"https://boverket.se/en/start/laws-and-regulations/national-regulations/building-regulations","publisher":"Boverket"},{"title":"Guide till takmaterial","url":"https://offerta.se/guider/bygg-och-renovering/guide-till-takmaterial","publisher":"Offerta"},{"title":"Concrete tile shape","url":"https://benders.se/en-gb/benders/article-archive/2014/concrete-tile-shape/","publisher":"Benders"},{"title":"Seaweed roofs on Læsø","url":"https://en.wikipedia.org/wiki/Seaweed_roofs_on_L%C3%A6s%C3%B8","publisher":"Wikipedia"}]},{"slug":"roofing-in-switzerland","title":"Roofing in Switzerland","category":"world-roofing","type":"place","country":{"name":"Switzerland","iso2":"CH"},"summary":"Swiss roofing: deep-eaved chalet roofs, tiled farmhouses, stone-slab roofs in Ticino, Valais and Graubünden, and Basel's extensive green roofs.","body":"Switzerland packs very different roofing traditions into a small, mountainous country. Farmhouses of western Switzerland and the Jura have been tiled since the 16th century; Alpine chalets carry broad, gently pitched roofs with deep eaves; and the southern valleys of Ticino, together with parts of Valais and Graubünden, are known for heavy stone-slab roofs. In cities, Basel has become a world reference for green roofs.\n\n## Climate and hazards\n\nSnow is the dominant load in the Alps, while rain and wind matter more on the lower plateau. Fire was historically the great hazard for roofs of wood and straw: in western Switzerland, farmhouses that remained thatched until the 19th century lost their thatch once fire insurance spread. In southern Switzerland, heavy stone roofs are valued for their stability and durability.\n\n## Roofing history\n\nRomanesque churches such as Romainmôtier Priory, built around the end of the 10th century, are among the oldest roofed buildings, though their roofs have been renewed many times. In the Alpine foothills a farmhouse form with large protective eaves at the gable ends remained largely unchanged from the 12th to the 19th century, and gables in the Bernese Oberland were often richly decorated. In western Switzerland and the Jura, shallow shingle roofs were replaced by steeper tiled roofs from the 16th century.\n\nThe chalet, from a word for a herder's hut in the French-speaking Alps and Savoy, has a heavy, gently sloping roof with wide, well-supported eaves. The Grand Chalet at Rossinière, built in 1752-1756, is one of the largest. Chalet designs lent themselves to partial factory production, and companies shipped chalet kits across Europe. In Ticino, stone construction replaced earlier wooden buildings in most villages over the last two centuries, and stone-slab roofs (*piode*) became a defining feature of the valleys. In the Engadin, massive stone houses proved resistant to the village fires that destroyed many wooden buildings.\n\nConcern for traditional roofscapes grew in the 20th century: the Swiss Heritage Society was founded on 1 July 1905, heritage protection entered the Federal Constitution in 1962, and the Wakker Prize has rewarded towns for preservation since 1972.\n\n## Traditional and vernacular roofs\n\n- **Chalet roofs**, heavy and gently pitched with deep eaves, in the Alps and Pre-Alps.\n- **Clay tile roofs**, which replaced shallow shingle roofs on farmhouses of western Switzerland and the Jura from the 16th century.\n- **Stone-slab roofs**: Switzerland traditionally used a great deal of natural stone, especially in Valais and Graubünden. In Ticino, slabs were laid almost flat on cross-battens, a very stable and durable but expensive roof.\n- **Thatch**, formerly on farmhouses in the north-west and Jura.\n\n## Roofing today\n\nStone roofs are maintained with public support in protected landscapes: the canton of Ticino pays CHF 200 per m² of roof built in hand-split gneiss slabs on eligible rural buildings. Basel combined subsidies with a 2002 legal requirement that new and renovated flat roofs be greened, and by 2019 it had about 5.7 m² (61 ft²) of green roof per inhabitant, described by the European Climate-ADAPT platform as the largest in the world.\n\n## Codes, standards and regulation\n\nBuilding law is set mainly by the cantons and municipalities; cantonal rules, such as Ticino's subsidies for traditional roofs and Basel's green-roof requirement, shape roof materials in protected landscapes and in cities. Technical construction standards are published by the Swiss Society of Engineers and Architects (SIA), and EN product standards apply to roofing materials.\n\n## Industry\n\nInternational groups are active in the Swiss market; Braas (part of BMI Group) sells tiles in Switzerland, and the Swiss building-materials company Swisspor took over the Polish and Hungarian plants of the clay tile maker Creaton in 2024.\n\n## Notable roofs\n\n- **Old City of Berne**, a UNESCO World Heritage Site founded in the 12th century, where conservation of the appearance of facades and roofs began in the early 20th century.\n- **Grand Chalet, Rossinière** (1752-1756).\n- **Basel's green roofs**, a model for city green-roof policy.\n- **Stone-roofed villages of the Maggia valley**, Ticino.\n\n## Local roofing terms\n\n- *Schindel* (German): wooden shingle.\n- *Piode* (Italian, Ticino): stone roof slabs.\n- *Coppi* (Italian): curved clay tiles.\n- *Chalet* (French): originally a herder's hut.\n\n## Sources and gaps\n\nNational data on roof coverings and the titles of SIA roofing standards: published information is limited.","key_facts":[{"label":"Traditional materials","value":"Wooden shingles, clay tile, stone slabs (piode), thatch"},{"label":"Climate driver","value":"Alpine snow"},{"label":"Stone roof subsidy (Ticino)","value":"CHF 200 per m² of hand-split gneiss"},{"label":"Basel green roof","value":"About 5.7 m² per inhabitant (2019)"},{"label":"Regulation","value":"Cantonal and municipal building law"}],"regions":["Europe"],"aliases":["Swiss roofing","Dachdeckung in der Schweiz","Toitures en Suisse"],"related":["piode","schindel","stone-slate","basel-green-roof-policy","beaver-tail-tile","roofing-in-austria","roofing-in-germany","roofing-in-france","roofing-in-italy","roofing-in-liechtenstein"],"company":null,"sources":[{"title":"Architecture of Switzerland","url":"https://en.wikipedia.org/wiki/Architecture_of_Switzerland","publisher":"Wikipedia"},{"title":"Chalet","url":"https://en.wikipedia.org/wiki/Chalet","publisher":"Wikipedia"},{"title":"Historische Dachdeckungen","url":"https://www.baunetzwissen.de/altbau/fachwissen/dach-deckungen/historische-dachdeckungen-2949105","publisher":"Baunetz Wissen"},{"title":"Direttiva contributi tetti materiale tradizionale","url":"https://m4.ti.ch/fileadmin/DT/temi/puc_paesaggi_edifici_impianti_protetti/tetti_piode/Direttiva_contributi_tetti_materiale_tradizionale.pdf","publisher":"Repubblica e Cantone Ticino"},{"title":"Green roofs in Basel, Switzerland","url":"https://climate-adapt.eea.europa.eu/en/metadata/case-studies/green-roofs-in-basel-switzerland-combining-mitigation-and-adaptation-measures-1","publisher":"Climate-ADAPT (European Environment Agency)"},{"title":"Old City of Berne","url":"https://whc.unesco.org/en/list/267","publisher":"UNESCO World Heritage Centre"},{"title":"Engadinerhaus","url":"https://de.wikipedia.org/wiki/Engadinerhaus","publisher":"Wikipedia (German)"},{"title":"A valley's future lies in the Stone Age","url":"https://www.swissinfo.ch/eng/a-valley-s-future-lies-in-the-stone-age/1020788","publisher":"Swissinfo"}]},{"slug":"roofing-in-syria","title":"Roofing in Syria","category":"world-roofing","type":"place","country":{"name":"Syria","iso2":"SY"},"regions":["Middle East"],"company":null,"summary":"Syrian roofing: mud beehive domes of the north, basalt slab roofs of the Hauran, red-tiled central hall houses and modern flat concrete.","aliases":["Syrian roofing","Roofs of Syria"],"body":"Syria holds several very different roof traditions in a small area: conical mud domes in the villages of the north, basalt slabs carried on corbels and arches in the volcanic Hauran of the south, and red-tiled roofs on 19th-century central hall houses. Many of these buildings have been damaged or abandoned since the war that began in 2011.\n\n## Climate and hazards\n\nNorthern and eastern Syria have very hot, dry summers; Syria's beehive houses stay cool in desert heat and hold warmth in winter. The Hauran is a volcanic basalt landscape where timber was scarce. Earthquakes have shaped the region's buildings: a major earthquake in 747 AD destroyed Umm el-Jimal just across the Jordanian border.\n\n## Roofing history\n\n**Neolithic and ancient.** The Lebanese architect Fadlallah Dagher has suggested that the beehive building technique of northern Syria could date back to the Neolithic, about 8,000 years ago.\n\n**Roman and late antique Hauran.** Builders in the Hauran roofed buildings with long, thin basalt slabs laid on rows of projecting corbels or on transverse stone arches. Bosra's South Bath (2nd-3rd century AD) has a semidome under a flat basalt slab, and Bosra Cathedral was built in 512-513. See hauran-basalt-corbelled-roofs.\n\n**Ottoman era.** The central hall (\"Lebanese\") house appeared in the second half of the 19th century in Syria as well as Lebanon, roofed with red Marseille tiles on a wooden frame; ceilings were carried on timber or metal beams, sometimes with decorative plaster on lath (*baghdadi*).\n\n**Modern.** Flat concrete roofs often replaced the earlier tiled roofs and their wooden frames.\n\n## Traditional and vernacular roofs\n\n- **Beehive houses:** conical or domed houses of mud mixed with straw, built for thousands of years in northern Syria, for example at Umm Amuda Kabira in Aleppo province, which once had about 200 mud houses. They need regular upkeep; since the war many skilled builders have left, and abandoned houses are decaying. Similar houses survive across the border at Harran (see harran-beehive-houses).\n- **Basalt slab roofs:** in the Hauran, corbel-and-slab and arch-and-slab stone roofs.\n- **Central hall house:** pyramidal or hipped red Marseille-tile roofs over a timber frame.\n\n## Roofing today\n\nFlat concrete roofs replaced many traditional tile and earth roofs.\n\n## Notable roofs\n\n- **Bosra:** late antique basalt buildings with stone slab roofs.\n- **Beehive villages** of Aleppo and Hama provinces.\n\n## Local roofing terms\n\n- *baghdadi* - plaster ceiling on timber lath in a central hall house\n\n## Sources and gaps\n\nDetailed climate data, data on current roofing materials and information on modern roofing practice, codes and industry: published information is limited. The war has disrupted documentation.","key_facts":[{"label":"Northern vernacular","value":"Mud-and-straw beehive domes"},{"label":"Southern vernacular","value":"Basalt slabs on corbels and arches (Hauran)"},{"label":"19th-century houses","value":"Red Marseille tile on timber frames"},{"label":"Modern","value":"Flat concrete"}],"related":["harran-beehive-houses","hauran-basalt-corbelled-roofs","interlocking-clay-tile","mud-roof","flat-roof","dome","roofing-in-lebanon","roofing-in-jordan","roofing-in-turkey","roofing-in-iraq","roofing-in-israel"],"sources":[{"title":"Syria's ancient adobe houses threatened by war, displacement (AFP)","url":"https://www.arabnews.pk/node/2368921/middle-east","publisher":"Arab News"},{"title":"Engineering the reconstruction of Hawrān's Ecclesiae during late antiquity: case of Julianos church in Umm el-Jimal, Jordan (Al Rabady and Rababeh, 2022)","url":"https://www.nature.com/articles/s40494-022-00727-0","publisher":"npj Heritage Science"},{"title":"Traditional Mediterranean Architecture: The Lebanese house (typology sheet, EU MEDA programme)","url":"https://safita.neocities.org/files/documents/architecture2.pdf","publisher":"EU MEDA programme (hosted copy)"}]},{"slug":"roofing-in-taiwan","title":"Roofing in Taiwan","category":"world-roofing","type":"place","country":{"name":"Taiwan","iso2":"TW"},"summary":"Taiwanese roofing: Indigenous stone-slab and thatch houses, Hokkien swallowtail-ridge temples, then concrete roofs topped by countless steel rooftop additions.","body":"Taiwan's roofs record waves of settlement: Austronesian Indigenous houses of stone, wood, bamboo and thatch; Hokkien and Hakka houses and temples brought by settlers from Fujian and Guangdong; Japanese colonial building from 1895 to 1945; and post-war concrete cities. A distinctive feature of today's skyline is the light steel rooftop addition built on top of flat concrete roofs.\n\n## Climate and hazards\n\nTaiwan lies in the path of western Pacific typhoons and has a hot, humid climate with heavy summer rain. Wind is a recurring threat to lightweight roof cladding: during Typhoon Soudelor in August 2015, metal roof panels about 1 by 8 m (3 by 26 ft) were torn from the unfinished Taipei Dome. The island is also highly seismic, a factor in the shift from heavy tile to concrete and light steel.\n\n## Roofing history\n\n**Indigenous building.** Prehistoric shelters included caves, stilt houses and stone masonry, mainly of Austronesian origin. The Paiwan and Bunun built stone-walled houses with thatched roofs; Paiwan stone-slab houses used layered slate laid like the scales of the hundred-pacer snake, which the Paiwan revere. The Atayal and Saisiyat built in wood and bamboo, and the Tao of Orchid Island set their houses partly into the ground to resist typhoons.\n\n**Dutch and Spanish forts.** In the 17th century the Dutch built in red brick, including Fort Zeelandia (1624, now Anping Fort), and the Spanish built Fort Santo Domingo (1628).\n\n**Hokkien and Hakka tradition.** Minnan (southern Fujian) architecture was introduced during the Kingdom of Tungning in the later 17th century and flourished under Qing rule. Its hallmark is the **swallowtail ridge**, an upswept, forked ridge end that originated in the 16th century among wealthy Hoklo traders and is common on Taiwanese temples, mansions and ancestral halls. Ridges are encrusted with *cut-porcelain* figures made from fragments of coloured ceramic.\n\n**Japanese era (1895-1945).** Colonial architecture mixed Minnan, Japanese and Western influences and introduced reinforced concrete, seen in buildings such as the Tainan Railway Station (1936).\n\n**Post-war.** After 1945, government buildings often adopted Chinese classical forms with tiled hip and hip-and-gable roofs, such as the Dacheng Hall of the Taichung Confucius Temple, while housing and offices adopted reinforced concrete and the International Style.\n\n## Traditional and vernacular roofs\n\n- **Paiwan stone-slab houses** - layered slate building in the southern mountains.\n- **Bunun and Paiwan thatch** - thatched roofs over stone walls.\n- **Minnan houses** - clay-tiled roofs, with swallowtail ridges on wealthier mansions and ancestral halls.\n- **Temples** - curved ridges with swallowtails, dragons and cut-porcelain decoration; ridge-end beasts (*chiwen*) appear on buildings such as the Taiwan Confucian Temple and Fort Provintia in Tainan.\n\n## Roofing today\n\nMost buildings are reinforced concrete with flat roofs. Light gauge steel roof structures added to these roofs are widespread in both cities and the countryside, often built without permits and with little attention to detailing. Illegal rooftop additions, known as *dinglou jiagai* (頂樓加蓋), have been common since the Japanese era; Taipei has tightened enforcement and usually demolishes non-compliant additions.\n\n## Codes, standards and regulation\n\nConstruction is governed by the **Building Act** (建築法), with detailed technical rules in subsidiary regulations. Site safety during construction is also a legal duty under the Act, as shown in enforcement against the Taipei Dome developer after Typhoon Soudelor.\n\n## Notable roofs\n\n- **Beipu Citian Temple**, Hsinchu County - cut-porcelain ridge decoration.\n- **Fengtian Temple**, Chiayi - Minnan-style Mazu temple.\n- **Taichung Confucius Temple** - post-war hip-and-gable roof in classical style.\n- **Anping Fort (Fort Zeelandia)**, Tainan - 1624 Dutch fort.\n\n## Local roofing terms\n\n- *ìnn-bé-tsiah* (燕尾脊, Mandarin *yanwei ji*) - swallowtail ridge\n- *tsián-huî-tiau* (剪瓷雕) - cut-porcelain decoration\n- *dinglou jiagai* (頂樓加蓋) - rooftop addition\n\n## Sources and gaps\n\nRoofing-material statistics, detailed code provisions on roofs and industry data: published information is limited.","key_facts":[{"label":"Climate driver","value":"Typhoons and earthquakes"},{"label":"Dominant roof today","value":"Flat concrete, often with steel rooftop additions"},{"label":"Traditional materials","value":"Slate, thatch, bamboo, red clay tile"},{"label":"Distinctive feature","value":"Swallowtail ridge (yanwei ji)"},{"label":"Building law","value":"Building Act"}],"regions":["East Asia"],"aliases":["Taiwanese roofing"],"related":["swallowtail-roof","chiwen","roofing-in-china","roofing-in-japan","roofing-in-hong-kong","clay-roof-tile","stone-slate","thatch","flat-roof","corrugated-iron","wind-uplift"],"company":null,"sources":[{"title":"Architecture of Taiwan","url":"https://en.wikipedia.org/wiki/Architecture_of_Taiwan","publisher":"Wikipedia"},{"title":"Hokkien architecture","url":"https://en.wikipedia.org/wiki/Hokkien_architecture","publisher":"Wikipedia"},{"title":"Chiwen","url":"https://en.wikipedia.org/wiki/Chiwen","publisher":"Wikipedia"},{"title":"Illegal rooftop additions (dinglou jiagai) in Taiwan","url":"https://www.taiwannews.com.tw/en/news/4675723","publisher":"Taiwan News"},{"title":"A study on the illegal light gauge steel roof construction in Tainan","url":"https://openaccess.library.uitm.edu.my/Record/ndltd-TW-097NCKU5222017","publisher":"National Cheng Kung University (thesis record)"},{"title":"Typhoon Soudelor: Taipei Dome panels blown off","url":"https://www.taipeitimes.com/News/taiwan/archives/2015/08/09/2003624947","publisher":"Taipei Times"}]},{"slug":"roofing-in-tajikistan","title":"Roofing in Tajikistan","category":"world-roofing","type":"place","country":{"name":"Tajikistan","iso2":"TJ"},"summary":"Tajikistan's distinctive roof is the flat earth roof of the Pamiri house (chid), carried on five pillars and lit by a stepped skylight, the chorkhona.","body":"Tajikistan is the most mountainous country in Central Asia, with the Pamir range occupying its eastern half. Its best-documented vernacular roof is that of the **Pamiri house**, or *chid*, in the Badakhshan region: a flat earth roof on timber beams and five carved pillars, lit through a stepped square skylight, the **chorkhona**.\n\n## Climate and hazards\n\nThe high Pamirs have long, very cold winters and a dry climate; settlements such as the village of Hichigh in Badakhshan stand at around 3,700 m (12,250 ft). Earthquakes are a major hazard across the country.\n\n## Roofing history\n\nThe Pamiri house carries layers of symbolism that its inhabitants trace back more than 2,500 years, overlaid by the Ismaili Muslim tradition of the region. During the Soviet period, building in towns followed all-Union codes, including the seismic design codes SNiP II-A.12-62 and SNiP II-A.12-69, which introduced dynamic-theory design. After independence Tajikistan adopted its own anti-seismic construction code in 2007.\n\n## Traditional and vernacular roofs\n\n**Pamiri house (chid).** Walls are of stone with mud or plaster. Inside the single main room, five timber pillars support two main beams, over which lie groups of smaller beams, usually thirteen, and then the flat roof. The roof is a working surface, used to dry hay, apricots, mulberries and dung for fuel. The only daylight enters through the *chorkhona* (\"four houses\"), four square timber frames stacked one above the other up to the roof opening, said to represent earth, water, air and fire. The pillars were traditionally of juniper, which has become too scarce to use in new houses. Each of the five pillars is named after a member of the Prophet's family and marks a place for particular household activities.\n\n## Codes, standards and regulation\n\nTajikistan approved an **Anti-Seismic Construction Code** in 2007; a new edition, **SNiP RT 22-07-2018**, was adopted in 2019.\n\n## Notable roofs\n\n- **Pamiri houses of Badakhshan**, for example in the Bartang valley and at Hichigh.\n\n## Local roofing terms\n\n- *chid* (Pamiri): house\n- *chorkhona* (Pamiri): \"four houses\", the stepped skylight\n- *akli kul* and *nafsi kul*: names of the two main roof beams, meaning universal reason and universal soul\n\n## Sources and gaps\n\nInformation on roofing in the lowland west of the country, around Dushanbe and the Fergana valley, statistics on roof materials, modern materials and the roofing industry were not found in published sources.","key_facts":[{"label":"Traditional roof","value":"Flat roof of the Pamiri house on five pillars"},{"label":"Skylight","value":"Chorkhona, four stepped timber squares"},{"label":"Traditional materials","value":"Stone, mud, plaster, timber (juniper pillars)"},{"label":"Climate driver","value":"High-mountain cold, earthquakes"},{"label":"Seismic code","value":"SNiP RT 22-07-2018 (adopted 2019)"}],"regions":["Central Asia"],"aliases":["Tajik roofing","roofs of Tajikistan"],"related":["pamiri-house","flat-roof","mud-roof","skylight","earthquake-roofing","roofing-in-afghanistan","roofing-in-uzbekistan","roofing-in-kyrgyzstan","roofing-in-china"],"company":null,"sources":[{"title":"The Pamiri House","url":"https://pamirs.org/about/the-pamiri-house","publisher":"Pamirs.org"},{"title":"Chid: cosmogony of the Pamiri house","url":"https://ext.maat.pt/longforms/chid-cosmogony-pamiri-house","publisher":"MAAT - Museum of Art, Architecture and Technology"},{"title":"Design regulations (Central Asia exposure model)","url":"https://docs.openquake.org/global_risk_model/central_asia/exposure/design_regulations.html","publisher":"Global Earthquake Model Foundation"}]},{"slug":"roofing-in-tanzania","title":"Roofing in Tanzania","category":"world-roofing","type":"place","country":{"name":"Tanzania","iso2":"TZ"},"summary":"Tanzania is roofed mostly in iron sheets (85% of households in 2022), with grass or leaf thatch at 12%; its coast has medieval coral-stone domes and vaults.","body":"Tanzania combines a long Indian Ocean coast and the islands of Zanzibar with a high, largely dry interior plateau, the Rift Valley lakes and the mountains of the north. Its roofing history is unusually deep on the coast, where Swahili builders were roofing mosques with coral-stone vaults and domes in the 13th and 14th centuries, while inland houses used grass, leaves, earth and dung. By the 2022 census, about 85% of households lived under iron-sheet roofs.\n\n## Climate and hazards\n\nThe coast and islands are hot and humid with two rainy seasons; the central plateau is semi-arid with a single rainy season; the highlands are cooler and wetter. Roofs must deal with tropical downpours and strong sun everywhere, salt air and high humidity on the coast, and termites and fire risk for organic materials. Earthquakes also occur in the Rift system: according to one published account, an earthquake in 1331 brought down much of the Great Mosque of Kilwa.\n\n## Roofing history\n\n**The medieval coast.** At Kilwa Kisiwani, the Great Mosque probably originated in the 10th century; its northern prayer hall, built in the 12th century, was fully roofed on coral-stone and later timber pillars. Between 1294 and 1302 a southern extension was added to carry a semicircular vault, and in the early 14th century Sultan al-Hasan ibn Sulaiman added a large dome, reportedly the only one left standing after that earthquake. Builders used coral stone for walls and columns, lime plaster for floors and lime mortar on later walls. Kilwa Kisiwani and the nearby town of Songo Mnara (occupied from the 14th to 16th centuries) were inscribed together as a UNESCO World Heritage Site in 1981.\n\n**Zanzibar.** In Zanzibar, multi-storey stone buildings were made of coral rag and lime with mangrove poles and coconut palm material. Most of the architecture of Stone Town dates from the 19th century trade boom, when Omani, Indian and Persian merchant communities settled there.\n\n**The interior.** Inland, documented early buildings are few. The house at Kwihara near Tabora known as *Tembe la Livingstone*, built in 1857 of stone and mud in a coastal Swahili style, was used by David Livingstone and Henry Morton Stanley in 1871-72 and is now a national historic site.\n\n**Modern era.** Corrugated iron spread during the German and British colonial periods and after independence. At the 2022 census, 85.6% of households lived in houses with improved roofing materials.\n\n## Traditional and vernacular roofs\n\n- **Coral-stone roofs** on the coast and Zanzibar: coral and lime laid over mangrove-pole joists (see Swahili coral-stone house).\n- **Makuti**: sun-dried coconut palm-leaf thatch, widely used along the coast and on Zanzibar.\n- **Maasai house** in the north: low domed dwellings packed with leaves and plastered with cattle dung (see Maasai enkaji).\n- **Hadza shelters**: domed huts of branches that are thickly thatched in the cooler season.\n- **Barabaig huts**: some built with flat-roof frames inside thornbush enclosures.\n\n## Roofing today\n\nThe 2022 Population and Housing Census gives the main roofing material of households:\n\n| Main roofing material | Tanzania | Mainland | Zanzibar |\n|---|---|---|---|\n| Iron sheets | 84.8% | 84.6% | 92.5% |\n| Grass/leaves | 11.6% | 11.7% | 5.7% |\n| Mud and leaves | 2.4% | 2.5% | 0.2% |\n| Others | 1.2% | 1.1% | 1.6% |\n\nTaken together, organic and earth roofs (grass, leaves and mud) still covered about one household in seven nationally, but only about one in seventeen on Zanzibar.\n\n## Codes, standards and regulation\n\nIn Zanzibar's Stone Town, alterations to historic buildings are governed by the Stone Town Conservation and Development Act of 1994.\n\n## Industry\n\nRegional coated-steel groups, including Safal Group (parent of Kenya's Mabati Rolling Mills), list Tanzania among their operating countries.\n\n## Notable roofs\n\n- **Great Mosque of Kilwa** (Kilwa Kisiwani, UNESCO 1981): coral-stone vaults and a 14th-century dome.\n- **Stone Town of Zanzibar** (UNESCO 2000): about 1,709 coral-stone buildings, many in poor repair, with large verandas behind carved wooden balustrades.\n- **Tembe la Livingstone**, Kwihara: 19th-century stone-and-mud house, now a museum.\n\n## Local roofing terms\n\n- *mabati* (Swahili): metal roofing sheets.\n- *makuti* (Swahili): coconut palm-leaf thatch.\n- *tembe* (Swahili): used in the name of the Kwihara house, *Tembe la Livingstone*.\n\n## Sources and gaps\n\nThe census brief does not define its \"mud and leaves\" category or break down \"others\". The traditional flat earth-roofed *tembe* house of central Tanzania, often described in older literature: published information is limited. Tanzanian national building regulations and roofing standards were not identified.","key_facts":[{"label":"Dominant material today","value":"Iron sheets, 84.8% of households (2022 census)"},{"label":"Thatch","value":"Grass/leaves 11.6%; mud and leaves 2.4% (2022)"},{"label":"Traditional materials","value":"Grass, leaves, earth, dung, makuti palm thatch, coral stone and lime"},{"label":"Oldest roofs","value":"Great Mosque of Kilwa vaults (1294-1302) and dome (early 14th century)"},{"label":"Climate driver","value":"Tropical rains, humid salty coast, dry plateau"}],"regions":["Africa"],"aliases":["Tanzanian roofing","Zanzibar roofing","roofs in Tanzania"],"related":["roofing-in-east-africa","swahili-coral-stone-house","makuti-thatch","maasai-enkaji","corrugated-iron","mabati-rolling-mills","dome","roofing-in-kenya","roofing-in-uganda","roofing-in-rwanda","roofing-in-burundi","middle-eastern-domes"],"sources":[{"title":"Housing Condition, Household Amenities and Assets (2022 PHC)","url":"https://www.nbs.go.tz/uploads/statistics/documents/en-1764003000-Housing%20Condition,%20Household%20Amenities%20and%20Assets.pdf","publisher":"National Bureau of Statistics, Tanzania"},{"title":"Great Mosque of Kilwa","url":"https://en.wikipedia.org/wiki/Great_Mosque_of_Kilwa","publisher":"Wikipedia"},{"title":"Stone Town","url":"https://en.wikipedia.org/wiki/Stone_Town","publisher":"Wikipedia"},{"title":"Swahili architecture","url":"https://en.wikipedia.org/wiki/Swahili_architecture","publisher":"Wikipedia"},{"title":"Livingstone's Tembe","url":"https://wiki.riteme.site/wiki/Livingstone%27s_Tembe","publisher":"Wikipedia (mirror)"},{"title":"African architecture: Geographic influences","url":"https://www.britannica.com/art/African-architecture/Geographic-influences","publisher":"Encyclopaedia Britannica"},{"title":"Makuti thatching","url":"https://en.wikipedia.org/wiki/Makuti_thatching","publisher":"Wikipedia"},{"title":"Stone Town of Zanzibar","url":"https://whc.unesco.org/en/urban-heritage-atlas/stone-town","publisher":"UNESCO World Heritage Centre"}],"company":null},{"slug":"roofing-in-thailand","title":"Roofing in Thailand","category":"world-roofing","type":"place","country":{"name":"Thailand","iso2":"TH"},"summary":"Roofing in Thailand, from tiered temple roofs with chofa finials and naga bargeboards to regional stilt houses with tall gables, clay or wooden tiles and thatch.","body":"Thailand has one of the richest roof traditions in Asia. Its temples and palaces carry stacked, steep roofs with serpent bargeboards and bird-beak finials, and its traditional houses combine tall gables, deep eaves and raised floors with regional variations from the hills of the north to the Muslim south.\n\n## Climate and hazards\n\nThailand's tropical monsoon climate brings a long rainy season, intense heat and, in the river plains, seasonal flooding. The south faces frequent storms from both coasts. Traditional design responds with steep pitches to shed rain, long eaves for shade, light materials that release heat quickly, and floors raised above flood level.\n\n## Roofing history\n\nSources on Thai housing describe clear evidence of elevated houses from around the 13th century, the period in which the Sukhothai kingdom was founded (traditionally B.E. 1780, about 1237 CE). During the Ayutthaya period (1350-1767), European visitors recorded houses of common people raised about 3-4 ft (0.9-1.2 m) above ground, and the German traveller Engelbert Kaempfer described bamboo huts in 1690. Chinese-style buildings (*keng*) existed in Ayutthaya, but most were destroyed in the wars with Burma that ended the kingdom in 1767. The late Ayutthaya period also produced the concave \"sagging hull\" temple roofline, *yon thong samphao*.\n\nIn the Rattanakosin (Bangkok) period, King Rama III's reign brought strong Chinese influence, including temple halls with Chinese-style roofs without finials. Kings Rama IV to Rama VI built in Western and hybrid styles; the Chakri Maha Prasat at the Grand Palace, from Rama V's reign, pairs a European body with Thai tiered roofs. Victorian-influenced \"gingerbread\" houses with fretwork eaves appeared in the 1860s-1870s.\n\n## Traditional and vernacular roofs\n\n**Temple and palace roofs.** Ornamented tiered roofs are reserved for temples, palaces and important public buildings. Most have two or three tiers, and some royal temples have four. Their ornaments include the *chofa* finial, *lamyong* and *bai raka* bargeboards, and *hang hong* lower finials, all developed from the serpent (*naga*) and Garuda. See the separate entry on the Thai temple roof.\n\n**Houses (*ruean thai*).** Traditional houses stand on posts, typically about 2 m (6.5 ft) high, leaving a shaded underfloor space (*tai thun*). Regional roofs differ:\n\n- **Central:** high, steep gables, curved at the ridge, with long overhanging eaves; gable boards called *ngao*, *hang pla* and *panlom* finish the verges.\n- **North (Lanna):** lower, heavier roofs with long eaves, crossed-board *kalae* finials on the gable peak, and coverings of terracotta tiles or wooden tiles (*pan kled*).\n- **Northeast (Isan):** gentler slopes, often without eaves, sometimes with sunburst carving.\n- **Korat (Mon-influenced):** very acute gables, steeper than 50 degrees.\n- **South:** roofs built to withstand storms, including the five-ridged hipped *lima* or *panya* roof common in Pattani and the hip-and-gable *Manila* or *blanor* roof used by Muslim communities.\n\nTemporary houses were thatched with grass, bamboo or palm leaves. Permanent houses in the central and northern regions used terracotta tiles in several forms: half-cylindrical *kap kluay* (\"banana trunk\"), square, sharp-cornered *kled tao* (\"turtle shell\") and *hang yiao* (\"falcon tail\") with upturned corners. Some northern houses used clay tiles in a fish-scale pattern.\n\nJoinery traditions are named by construction method: *khrueang sab* for nail-free timber joinery and *khrueang phook* for tied bamboo.\n\n## Roofing today\n\nRooftop solar is growing: in May 2025 the Cabinet approved in principle a ministerial regulation under which rooftop solar panels weighing no more than 20 kg per square metre (about 4.1 lb/sq ft) need no prior building approval, because that load is not treated as a structural modification. Under the earlier rule, residential installations up to 160 m2 (about 1,720 sq ft) at that weight needed an inspection by a licensed civil engineer.\n\n## Codes, standards and regulation\n\nConstruction is governed by the Building Control Act B.E. 2522 (1979), with detailed requirements issued as ministerial regulations; the Ministry of Interior and the Building Control Committee oversee changes such as the 2025 solar rule.\n\n## Notable roofs\n\n- **Wat Phra Kaew and the Grand Palace, Bangkok**: multi-tiered roofs with full chofa and naga ornament; the ordination hall has a multiple-front roof.\n- **Chakri Maha Prasat**: Thai tiered roofs on a European-style hall.\n- **Wat Ratchaorasaram, Bangkok**: a Thai-Chinese ordination hall rebuilt under Rama III with a single-front roof and no chofa.\n\n## Local roofing terms\n\n- *chofa* - bird-beak ridge finial; *hang hong* - lower serpent-head finial\n- *lamyong*, *bai raka* - serpent-form bargeboard and its blade-like projections\n- *kalae* - crossed gable finial (north)\n- *ngao*, *panlom* - gable boards (central)\n- *pan kled* - wooden roof tiles\n- *kap kluay*, *kled tao*, *hang yiao* - clay tile types\n- *lima* / *panya* - hipped roof (south)\n\n## Sources and gaps\n\nCensus data on roof materials, roofing industry information and detailed code provisions for roofs: published information is limited.","key_facts":[{"label":"Traditional materials","value":"Grass, bamboo and palm thatch; terracotta tiles; wooden tiles (pan kled)"},{"label":"Temple roof tiers","value":"Usually 2-3; some royal temples 4"},{"label":"Climate driver","value":"Monsoon rain, heat, flooding, southern storms"},{"label":"Building code","value":"Building Control Act B.E. 2522 (1979)"},{"label":"Rooftop solar rule","value":"Panels up to 20 kg/m2 exempt from prior approval (approved in principle May 2025)"}],"regions":["Southeast Asia"],"aliases":["Thai roofing","Siamese roofing"],"related":["roofing-in-southeast-asia","thai-temple-roof","traditional-thai-house","pagoda-roof","clay-roof-tile","palm-thatch","bamboo-roofing","hip-roof","gable-roof","roofing-in-laos","roofing-in-cambodia","roofing-in-myanmar","roofing-in-malaysia"],"company":null,"sources":[{"title":"Thai temple art and architecture","url":"https://en.wikipedia.org/wiki/Thai_temple_art_and_architecture","publisher":"Wikipedia"},{"title":"Architecture of Thailand","url":"https://en.wikipedia.org/wiki/Architecture_of_Thailand","publisher":"Wikipedia"},{"title":"Traditional Thai house","url":"https://en.wikipedia.org/wiki/Traditional_Thai_house","publisher":"Wikipedia"},{"title":"Ruean Thai: Understanding Traditional Thai Houses","url":"https://thailandfoundation.or.th/?p=530402","publisher":"Thailand Foundation"},{"title":"Govt waives permit requirement for rooftop solar panels under 20 kg/m2","url":"https://www.nationthailand.com/news/policy/40049635","publisher":"The Nation (Thailand)"}]},{"slug":"roofing-in-the-arctic","title":"Roofing in the Arctic and Greenland","type":"place","summary":"Overview of roofing in Greenland and the Arctic: turf and timber traditions, metal and membrane roofs today, designed for snow, wind, cold and ice.","body":"Arctic regions, including Greenland, northern Scandinavia, Iceland, northern Russia, Alaska and northern Canada, impose some of the most demanding roofing conditions anywhere: extreme cold, long periods of snow cover, strong winds that drift snow, and short building seasons with materials shipped over long distances.\n\n## Traditional roofs\n\nIndigenous and early settler buildings used what the land provided. Turf, stone and driftwood or imported timber formed low, heavily insulated houses whose turf roofs blended into the ground, as in the turf houses of Iceland and the turf roofs of Norway, which weighed around 250 kg/m² (51 lb/ft²) and could reach 400-500 kg/m² (82-102 lb/ft²) with winter snow.\n\n## Modern settlements\n\nIn Greenland, Danish policy after 1953 brought a major expansion of housing and infrastructure on Danish models, moving people from small settlements into towns. Large concrete blocks such as Blok P in Nuuk, once home to nearly 1% of the population, were later judged unsuitable and Blok P was demolished in 2012. Typical Arctic houses today are timber-framed or prefabricated, raised above permafrost where necessary, with pitched roofs of coated steel sheet or bituminous roofing, while larger buildings use membranes.\n\n## Snow loads\n\nRoof design is governed by snow load. Codes convert mapped ground snow loads into roof loads, adjusting for exposure, thermal properties, roof shape, drifting and building importance; examples are ASCE 7 in the United States and Eurocode 1 Part 1-3 in Europe. Freshly settled snow has about 30% of the density of water, rising to about 50% by late spring, so a deep spring snowpack is far heavier than its depth suggests. Wind can build drifts several metres deep against parapets and roof steps.\n\n## Ice dams and condensation\n\nOn heated buildings with sloping roofs, heat escaping through the roof melts snow, and the meltwater refreezes at the cold eaves to form ice dams that can force water into the building. The remedies are high insulation levels, a ventilated \"cold roof\" kept below about -1 °C (30 °F), and waterproof membranes at the eaves. Airtight construction is also needed to stop warm, moist indoor air from condensing in cold roof spaces.\n\n## Practical concerns\n\nSnow guards to stop sliding snow, robust fixings against wind, materials that remain flexible at very low temperatures, and designs that can be built quickly in a short summer season are typical Arctic priorities.","key_facts":[{"label":"Main load","value":"Snow, including drifting"},{"label":"Snow density","value":"About 30% (fresh) to 50% (late spring) of water"},{"label":"Design codes","value":"ASCE 7, Eurocode 1 Part 1-3, national codes"},{"label":"Key risks","value":"Ice dams, condensation, wind"}],"regions":["Arctic","North America","Europe"],"aliases":["Arctic roofing","Greenland roofing","Cold-climate roofing","Arctic snow loads"],"related":["snow-load","ice-dam","roofing-in-iceland","roofing-in-canada","torvtak"],"sources":[{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"},{"title":"Ice dam (roof)","url":"https://en.wikipedia.org/wiki/Ice_dam_(roof)","publisher":"Wikipedia"},{"title":"Greenland","url":"https://en.wikipedia.org/wiki/Greenland","publisher":"Wikipedia"},{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-the-bahamas","title":"Roofing in the Bahamas","category":"world-roofing","type":"place","country":{"name":"Bahamas","iso2":"BS"},"summary":"Bahamian roofing: timber and shingle traditions under an early mandatory Caribbean building code, tested by Category 5 Hurricane Dorian in 2019.","body":"The Bahamas is a low-lying archipelago directly in the path of Atlantic hurricanes. It has been described by the catastrophe modeller AIR Worldwide as the first Commonwealth Caribbean country with a mandatory modern building code, yet Hurricane Dorian in 2019 showed how far real roofs could fall short of it.\n\n## Climate and hazards\n\n- **Hurricanes**: Dorian struck the Abaco Islands and Grand Bahama in early September 2019 with Category 5 winds that exceeded design levels, causing roof uplift, failure of roof ties and collapse of walls and roofs.\n- **Storm surge and flooding** on low islands.\n- **Termites and timber decay**, which weakened many destroyed buildings.\n- **Salt air** corrosion of fasteners and metal roofing.\n\n## Roofing history\n\nThe Lucayan Taíno who lived in the islands before European contact had the smallest Taíno villages in the Caribbean, with thatched houses of poles and palm leaves (see bohio).\n\n## Roofing today\n\nPost-Dorian reports concentrate on how roofs are tied down rather than on the covering, citing failed roof ties, uplift and aged or termite-damaged timber.\n\n## Codes, standards and regulation\n\n- The **Bahamas Building Code** was introduced in the early 1970s as a mandatory code.\n- A **1987** revision closely followed the South Florida Building Code.\n- The **2003** edition adopted ASCE 7 load methods, raised the design wind speed from 120 mph (193 km/h) to 150 mph (241 km/h) and made hurricane shutters mandatory on applicable new buildings.\n- Analysts noted that the code lacked detailed requirements for some roof elements such as ridges and overhangs.\n- A November 2019 government reconnaissance found a glaring absence of code compliance in many destroyed buildings on Abaco and Grand Bahama, and recommended limiting roof overhangs to 18 in (457 mm) unless the framing is engineered for greater uplift, and providing dormers or a vented gable as an emergency exit in flood-prone areas. A revised code was being finalised in 2021.\n\n## Notable roofs\n\nNo individually roofs are listed.\n\n## Sources and gaps\n\nPublished accounts of later colonial roofing: published information is limited. No information on domestic roofing manufacturers was found in published sources.\n\nPublished historic and vernacular roof details and material statistics are limited.","key_facts":[{"label":"Building code","value":"Bahamas Building Code (early 1970s; 1987; 2003)"},{"label":"Design wind speed (2003)","value":"150 mph (241 km/h)"},{"label":"Climate driver","value":"Hurricanes (Dorian, Cat 5, 2019)"}],"regions":["Latin America","North America"],"aliases":["Bahamian roofing"],"related":["hurricane-roof-damage","hip-roof","asphalt-shingle","metal-roofing","florida-product-approval","miami-dade-noa","roofing-in-the-caribbean","roofing-in-the-united-states","roofing-in-cuba"],"company":null,"sources":[{"title":"What Hurricane Dorian Taught Us about the Bahamas Building Code","url":"https://www.air-worldwide.com/Blog/What-Hurricane-Dorian-Taught-Us-about-the-Bahamas-Building-Code/","publisher":"AIR Worldwide"},{"title":"Glaring Dorian non-compliance drives building code","url":"https://tribune242.com/news/2021/dec/03/glaring-dorian-non-compliance-drives-building-code","publisher":"The Tribune (Nassau)"},{"title":"Taíno","url":"https://en.wikipedia.org/wiki/Ta%C3%ADno","publisher":"Wikipedia"}]},{"slug":"roofing-in-the-caribbean","title":"Roofing in the Caribbean","type":"place","summary":"Overview of Caribbean roofing: steep hip roofs, corrugated metal and concrete slabs, shaped above all by hurricane winds.","body":"Roofing across the Caribbean islands is shaped by tropical rain, salt air and, above all, hurricanes. A roof that stays attached in a major storm protects the rest of the house, and much regional building guidance focuses on roof shape, fastening and connection to walls.\n\n## Traditional houses\n\nHistoric Caribbean houses were mostly timber, raised on posts or blocks, with steep roofs. In Barbados, the movable *chattel house* stands on loose coral-stone blocks under a steep roof designed to deflect wind and rain, with reinforced shutters. Steep hip and gable roofs clad in wooden shingles, and later corrugated iron, are typical of older houses throughout the Eastern Caribbean.\n\n## Why hip roofs\n\nHip roofs, sloping on all four sides, are self-bracing and lack the tall, flat gable ends that catch wind. For hurricane regions, slopes of about 35 degrees or steeper are often preferred, because lower slopes are more prone to uplift. Hip roofs are therefore widely recommended in Caribbean building guidance.\n\n## Modern practice\n\nToday, common roof types include:\n\n- **Corrugated and trapezoidal metal sheet** on timber or steel purlins, the most widespread covering on houses.\n- **Reinforced concrete slabs**, increasingly used because they resist wind, though they need waterproofing and add weight.\n- **Asphalt shingles and clay or concrete tile** in some markets, particularly on higher-cost homes.\n\nFixing details matter more than covering type: closely spaced screws with washers, hurricane straps or clips tying rafters to wall plates, minimal overhangs on exposed sides, and secure ridge and edge flashings.\n\n## Codes\n\nMany islands have national building codes, often modelled on or referencing North American standards and wind maps. Florida's code, adopted statewide in 2002 after Hurricane Andrew, and its High-Velocity Hurricane Zone product testing (such as TAS 201-203 impact tests) are widely referenced in the region for product approval.\n\n## Rainwater\n\nOn many islands, roofs collect rainwater into cisterns, which affects the choice of covering and coatings.","key_facts":[{"label":"Main hazard","value":"Hurricanes"},{"label":"Preferred roof form","value":"Hip roof, about 35° or steeper"},{"label":"Common coverings","value":"Metal sheet, concrete slab, shingle, tile"},{"label":"Key details","value":"Hurricane straps, close fastening"}],"regions":["Latin America","North America"],"aliases":["Caribbean roofing","West Indies roofing"],"related":["chattel-house","hip-roof","roofing-in-the-united-states","rainwater-harvesting-roofs"],"sources":[{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"},{"title":"Chattel house","url":"https://en.wikipedia.org/wiki/Chattel_house","publisher":"Wikipedia"},{"title":"Architecture of Barbados","url":"https://en.wikipedia.org/wiki/Architecture_of_Barbados","publisher":"Wikipedia"},{"title":"Florida Building Code","url":"https://en.wikipedia.org/wiki/Florida_Building_Code","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-the-central-african-republic","title":"Roofing in the Central African Republic","category":"world-roofing","type":"place","country":{"name":"Central African Republic","iso2":"CF"},"summary":"Most Central African Republic homes are sun-dried brick under wild-grass or palm-frond thatch; cement-block houses with metal-sheet roofs mark wealth.","body":"The Central African Republic (CAR) is a landlocked country of savanna plateau in the north and tropical forest in the south-west, drained by the Ubangi river on which the capital, Bangui, stands. Its typical rural house has walls of sun-dried brick and a roof of thatch: wild grass in the savanna, palm fronds in the deep forest. Houses of cement block with metal-sheet roofs are associated with civil servants, merchants and institutions.\n\n## Climate and hazards\n\nThe climate is tropical, with a wet season of heavy rain and a hot dry season; in the dry season many people sleep outdoors. Thatched roofs must be renewed frequently because of termites. Demand for timber for building and firewood has contributed to deforestation around towns.\n\n## Roofing history\n\nLittle has been published on the long-term history of roofing in the CAR. During French colonial rule, mud-and-wattle construction was officially discouraged, though it never disappeared. Colonial-era buildings of cement block with metal roofs are still used by government departments and religious organisations.\n\n## Traditional and vernacular roofs\n\n- **Grass-thatched brick house**: sun-dried brick walls with a roof thatched in wild grass, the common rural dwelling. Floors are of pounded earth and the interior may be partitioned.\n- **Palm-frond roofs** in the forest zone, where fronds are laid over the roof frame.\n- **Mud-and-wattle houses**, still built despite colonial-era discouragement.\n- **Granaries**: basket-shaped granaries kept dry beneath thatched roofs are characteristic of Central Africa.\n\nVillages are generally open, without enclosures, except among Muslim communities and those who follow their customs.\n\n## Roofing today\n\nIn Bangui, permanent buildings of cement block with metal roofing stand alongside houses adapted to the climate, with sun-dried brick walls and grass or palm-frond roofs. Housing type depends mainly on wealth and partly on ethnic background, and few of these houses have electricity, piped water or road access.\n\n## Sources and gaps\n\nNo national figures on roof materials were found in published sources. No individually documented landmark roofs were identified.\n\nThe main source is a general cultural survey. National survey data (for example from MICS), historical studies of pre-colonial architecture, and information on codes and industry: published information is limited.","key_facts":[{"label":"Common rural roof","value":"Wild-grass thatch on sun-dried brick"},{"label":"Forest zone","value":"Palm-frond roofs"},{"label":"Urban and institutional","value":"Cement block with metal-sheet roofs"},{"label":"Main problem","value":"Termites force frequent thatch replacement"}],"regions":["Africa"],"aliases":["CAR roofing","Centrafrique roofing","roofs in the Central African Republic"],"related":["thatch","palm-thatch","corrugated-iron","mud-roof","mongulu","roofing-in-cameroon","roofing-in-chad","roofing-in-the-democratic-republic-of-the-congo","roofing-in-the-republic-of-the-congo","roofing-in-south-sudan","roofing-in-sudan"],"sources":[{"title":"Culture of Central African Republic","url":"https://www.everyculture.com/Bo-Co/Central-African-Republic.html","publisher":"Countries and Their Cultures (everyculture.com)"},{"title":"African architecture: Geographic influences","url":"https://www.britannica.com/art/African-architecture/Geographic-influences","publisher":"Encyclopaedia Britannica"}],"company":null},{"slug":"roofing-in-the-democratic-republic-of-the-congo","title":"Roofing in the Democratic Republic of the Congo","category":"world-roofing","type":"place","country":{"name":"Democratic Republic of the Congo","iso2":"CD"},"summary":"Most DRC households still live under thatch or palm leaf, with metal sheet on under a third (2017-18); Mangbetu royal halls were vast timber vaults.","body":"The Democratic Republic of the Congo (DRC) covers most of the Congo basin: equatorial rainforest at its centre, savanna to the north and south, and highlands along the eastern Rift. Unlike its East African neighbours, the DRC remains a country of plant-material roofs. In the 2017-18 Multiple Indicator Cluster Survey (MICS), about two-thirds of sampled households lived under thatch or palm leaf, and fewer than a third under metal sheet. Its history includes some of the largest timber and palm buildings recorded in Africa, the royal halls of the Mangbetu kingdom in the north-east.\n\n## Climate and hazards\n\nMuch of the country is hot and humid, with high rainfall spread through most of the year near the equator and distinct wet and dry seasons further north and south. Roofs must shed frequent heavy rain, resist rot and insects, and, under metal sheet, cope with intense heat gain: residents of western DRC describe metal-roofed houses as suffocatingly hot.\n\n## Roofing history\n\n**Mangbetu kingdom.** In the 19th century the Mangbetu of the north-east (today's Haut-Uele) built royal capitals entirely of wood. When the German botanist Georg Schweinfurth stayed at the capital of King Mbunza (reigned 1867-1873), Nangazizi, in 1870, he described a great public hall about 150 ft long, 50 ft wide and 50 ft high (about 46 x 15 x 15 m), with vaulted arches carried on rows of pillars made from straight tree trunks. Rafters and roofing were of palm leafstalks, and the floor was plastered with red clay polished smooth. A later hall built under King Okondo (reigned 1902-1915), photographed around 1909, used a gable roof instead of the arched vault but was otherwise similar. Historians treat parts of Schweinfurth's short account as embellished.\n\n**Kuba kingdom.** The Kuba kingdom, founded around 1625 under Shyaam a-Mbul a Ngoong between the Sankuru, Lulua and Kasai rivers, flourished until the late 19th century. Its houses near the capital, Mushenge, were photographed under construction in the 20th century.\n\n**Kongo.** The old Kongo kingdom straddled the lower Congo; its capital, Mbanza Kongo, lies in present-day Angola.\n\n**Forest peoples.** In the Ituri forest, Mbuti (Bambuti) shelters are framed with crossed sticks and covered with layered *mongongo* leaves, a light leaf dome related to the Baka *móngulu* of the western forests.\n\n## Traditional and vernacular roofs\n\n- **Thatch and palm leaf** on round and rectangular houses throughout the country; conical clay-and-thatch huts and rectangular wattle-and-daub houses with saddle (gable) roofs are both documented in historical photographs.\n- **Mangbetu hall**: vaulted or gabled timber hall with palm leafstalk rafters and roofing.\n- **Mongongo leaf dome** of the Ituri forest peoples (see Mongulu).\n- **Split-bamboo roofs** in Kongo Central (formerly Bas-Congo): bamboo poles are dried, split lengthwise and laid in nesting rows, one row hollow side up and the next hollow side down, tied with rope, in the same way as a tiled roof.\n\n## Roofing today\n\nThe 2017-18 MICS recorded the main roof material for 20,790 households in its public data file. Unweighted shares of sampled households were:\n\n| Main roof material | Share of household records (unweighted) |\n|---|---|\n| Thatch / palm leaf | 63.8% |\n| Grass | 5.1% |\n| Metal / aluminium / sheet (tôle) | 28.7% |\n| Tiles | 0.4% |\n| Palm / bamboo | 0.5% |\n| Cement | 0.2% |\n| Other and minor categories | about 1.3% |\n\nThese are counts of sampled households, not weighted national estimates, but they show how far the DRC differs from East Africa: natural roofs still outnumber metal by more than two to one.\n\nIn parts of Kongo Central, split-bamboo roofs had spread by 2011 as a cheaper and cooler alternative to metal sheeting, replacing leaky straw roofs; residents noted that they do not need a ceiling beneath them. Environmentalists have warned that rising demand could lead to over-cutting of bamboo, whose roots help hold soil.\n\n## Notable roofs\n\n- **Mangbetu royal halls** (19th-early 20th century, no longer standing): described as rivalling some of the largest wooden structures in the world.\n\n## Local roofing terms\n\n- *madiadi* (local word at Lemba, Kongo Central): bamboo.\n- *tôle* (French): metal roofing sheet.\n- *mongongo*: leaves used to cover Mbuti shelters.\n\n## Sources and gaps\n\nDetailed descriptions of Kuba roofs: published information is limited. No information on domestic roofing manufacturers was found in published sources.\n\nMICS shares are unweighted record counts shown in the World Bank Microdata Library and may differ from the survey's official weighted tables. Kuba house and roof construction, Nyanga architecture and national building regulations: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Thatch/palm leaf, 63.8% of MICS 2017-18 household records (unweighted)"},{"label":"Metal sheet","value":"28.7% of MICS 2017-18 household records (unweighted)"},{"label":"Historic landmark","value":"Mangbetu great hall, about 46 x 15 m (150 x 50 ft), 15 m (50 ft) high (1870 account)"},{"label":"Traditional materials","value":"Thatch, palm leaf and leafstalk, mongongo leaves, bamboo, timber"},{"label":"Climate driver","value":"Equatorial heat and heavy rainfall"}],"regions":["Africa"],"aliases":["DRC roofing","Congo-Kinshasa roofing","roofing in DR Congo"],"related":["palm-thatch","thatch","mongulu","corrugated-iron","roofing-in-the-republic-of-the-congo","roofing-in-the-central-african-republic","roofing-in-uganda","roofing-in-rwanda","roofing-in-burundi","roofing-in-tanzania","roofing-in-angola","roofing-in-zambia"],"sources":[{"title":"Congo, Dem. Rep. MICS 2017-2018: Matériau principal du toit (HC5)","url":"https://microdata.worldbank.org/catalog/4151/variable/F4/V907?name=HC5","publisher":"World Bank Microdata Library"},{"title":"Kingdoms at the forest's edge: a history of Mangbetu (ca. 1750-1895)","url":"https://www.africanhistoryextra.com/p/kingdoms-at-the-forests-edge-a-history","publisher":"African History Extra"},{"title":"Mangbetu people","url":"https://en.wikipedia.org/wiki/Mangbetu_people","publisher":"Wikipedia"},{"title":"Kuba Kingdom","url":"https://en.wikipedia.org/wiki/Kuba_Kingdom","publisher":"Wikipedia"},{"title":"The construction of a house, near Mushenge, Congo (Democratic Republic)","url":"https://si.edu/object/archives/components/sova-eepa-1973-001-ref7985","publisher":"Smithsonian Institution Archives"},{"title":"Rectangular wattle-and-daub houses with a saddle roof, Shabunda, Congo (Democratic Republic)","url":"https://www.si.edu/object/archives/components/sova-eepa-1973-001-ref8113","publisher":"Smithsonian Institution Archives"},{"title":"Conical huts of clay and thatch in a Yambuya village","url":"https://africacommons.net/artifacts/3000720/conical-huts-of-clay-and-thatch-in-a-yambuya-village","publisher":"Africa Commons"},{"title":"Democratic Republic of Congo: Cooler houses with bamboo roofs","url":"https://wire.farmradio.fm/farmer-stories/democratic-republic-of-congo-cooler-houses-with-bamboo-roofs-syfia-grands-lacs","publisher":"Farm Radio International (Syfia Grands Lacs)"},{"title":"African architecture: Geographic influences","url":"https://www.britannica.com/art/African-architecture/Geographic-influences","publisher":"Encyclopaedia Britannica"}],"company":null},{"slug":"roofing-in-the-dominican-republic","title":"Roofing in the Dominican Republic","category":"world-roofing","type":"place","country":{"name":"Dominican Republic","iso2":"DO"},"summary":"Dominican roofing: from the Taíno bohío to zinc and concrete; the 2022 census found 50.9% of homes with concrete roofs and 47.5% with zinc sheet.","body":"The Dominican Republic occupies the eastern two-thirds of Hispaniola. Its roofing is now split almost evenly between reinforced concrete and corrugated zinc (galvanised steel) sheet, with traditional palm materials surviving only in a few thousand homes.\n\n## Climate and hazards\n\nThe country has a hot, humid tropical climate with heavy seasonal rain and lies in the path of Atlantic hurricanes. Hispaniola is also seismically active. Roofs must resist wind uplift and, where they are heavy slabs, be properly tied to columns and walls.\n\n## Roofing history\n\n**Taíno.** The Taíno villages of Hispaniola were among the largest in the Caribbean. Family houses (*bohíos*) were large thatched buildings of wooden poles, woven straw and palm leaves set around a central plaza, and chiefs lived in rectangular houses (*caney*) of similar construction (see bohio).\n\n**Modern era.** Corrugated zinc sheet and reinforced concrete slabs have almost entirely replaced plant materials: by 2022 fewer than 4,000 dwellings still had palm roofs.\n\n## Traditional and vernacular roofs\n\n- **Bohío**: palm-thatched rural house.\n- **Cana** and **yagua**: traditional palm roof coverings still recorded separately in the census. *Cana* is thatch from the leaves of the palma cana (*Sabal domingensis*); *yagua* is the fibrous leaf sheath of the royal palm, used for the walls and roofs of bohíos.\n\n## Roofing today\n\nThe 10th National Population and Housing Census (2022), reported by the National Statistics Office (ONE), counted 3,694,060 occupied private dwellings, with roofs of:\n\n- Concrete: 1,881,428 (50.9%)\n- Zinc sheet: 1,755,486 (47.5%)\n- Asbestos-cement: 38,553 (1.0%)\n- *Cana*: 1,970 (0.1%)\n- *Yagua*: 1,656 (under 0.1%)\n- Other: 14,967 (0.4%)\n\nConcrete overtook zinc as the leading roof material by a narrow margin in 2022, while asbestos-cement and palm roofs have become marginal.\n\n## Local roofing terms\n\n- *Techo de zinc*: corrugated galvanised sheet roof.\n- *Techo de concreto* / *placa*: concrete slab roof.\n- *Cana*: palm-leaf thatch from the palma cana. *Yagua*: royal-palm leaf sheath.\n- *Bohío*: thatched house.\n\n## Sources and gaps\n\nNo information on domestic roofing manufacturers was found in published sources.\n\nBuilding code details, colonial roofing history and individual heritage roofs: published information is limited.","key_facts":[{"label":"Concrete roofs","value":"50.9% of dwellings (2022 census)"},{"label":"Zinc sheet roofs","value":"47.5% of dwellings (2022 census)"},{"label":"Traditional materials","value":"Palm thatch (cana, yagua)"},{"label":"Climate driver","value":"Hurricanes; earthquakes"}],"regions":["Latin America","North America"],"aliases":["Dominican roofing","Roofing in República Dominicana"],"related":["bohio","palm-thatch","corrugated-iron","flat-roof","corrugated-fibre-cement-sheet","roofing-in-haiti","roofing-in-cuba","roofing-in-puerto-rico","roofing-in-the-caribbean"],"company":null,"sources":[{"title":"¿De qué material se construyen los techos en República Dominicana?","url":"https://inmobiliario.do/de-que-material-se-construyen-los-techos-en-republica-dominicana/","publisher":"El Inmobiliario"},{"title":"Taíno","url":"https://en.wikipedia.org/wiki/Ta%C3%ADno","publisher":"Wikipedia"},{"title":"Sabal domingensis","url":"https://en.wikipedia.org/wiki/Sabal_domingensis","publisher":"Wikipedia"},{"title":"Yagua","url":"https://www.ecured.cu/Yagua","publisher":"EcuRed"}]},{"slug":"roofing-in-the-gambia","title":"Roofing in the Gambia","type":"place","country":{"name":"Gambia","iso2":"GM"},"summary":"In the Gambia about four in five homes are roofed with corrugated metal sheet, about one in ten with thatch, and a few with concrete.","body":"The Gambia, mainland Africa's smallest country, follows the Gambia River inland from the Atlantic and is surrounded by Senegal. Its roofs are dominated by corrugated metal sheet, with thatch still used on a minority of rural houses and concrete slabs on some urban buildings.\n\n## Climate and hazards\n\nThe climate is Sudano-Sahelian: a single rainy season of a few months followed by a long dry season with harmattan dust. Heat gain through metal roofs is a comfort issue. Along the river, buildings at historic sites suffer from erosion and flooding.\n\n## Roofing history\n\nThe river was a focus of European trade from the 15th century. Portugal acquired Kunta Kinteh (James) Island from local rulers by 1456 and began a fort there; the British later built Fort Bullen (1826) and the Six-Gun Battery (1816) at the river mouth. These sites, linked to the Atlantic slave trade, survive mostly as ruins.\n\n## Traditional and vernacular roofs\n\nThatch is the traditional rural roof, and household surveys still record it on about one home in ten. Neighbouring Casamance in Senegal is home to the Diola impluvium house, a thatched house that collects rainwater in a central basin.\n\n## Roofing today\n\nGambian household surveys since at least 2003 have classified roofs as thatch, corrugated iron, asbestos, cement/concrete or other. In the unweighted 2018 Multiple Indicator Cluster Survey sample (about 7,400 households):\n\n| Main roof material | Share of sampled households |\n|---|---|\n| Metal or tin sheet | 82.0% |\n| Thatch or palm leaf | 10.4% |\n| Cement | 2.3% |\n| Ceramic tiles | 0.2% |\n| Palm or bamboo | 0.2% |\n\n## Notable roofs\n\nThe Kunta Kinteh Island and Related Sites World Heritage property consists largely of ruins; the Maurel Frères building at Juffureh was restored in 1996 and the CFAO building at Albreda has also been restored.\n\n## Sources and gaps\n\nGambian roofing traditions: published information is limited. No roofs of particular heritage note were documented.\n\nSurvey figures are unweighted sample counts. Published sources on Gambian vernacular roof construction, regulation and industry: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal sheet, 82.0% (MICS 2018 file, unweighted)"},{"label":"Thatch","value":"10.4% of households (MICS 2018 file)"},{"label":"Survey categories","value":"Thatch, corrugated iron, asbestos, cement/concrete"},{"label":"Climate driver","value":"Single rainy season, harmattan, heat"}],"regions":["Africa"],"aliases":["Gambian roofing","roofing in Gambia"],"related":["roofing-in-west-africa","roofing-in-senegal","diola-impluvium-house","corrugated-iron","thatch","roofing-in-guinea-bissau"],"sources":[{"title":"MICS 2018 Gambia: main material of roof (HC5)","url":"https://microdata.worldbank.org/catalog/4154/variable/F5/V903?name=HC5","publisher":"World Bank Microdata Library / Gambia Bureau of Statistics"},{"title":"Integrated Household Survey 2003-2004: main roofing material","url":"https://catalog.ihsn.org/catalog/173/variable/F1/V22?name=roof","publisher":"IHSN / Gambia Bureau of Statistics"},{"title":"Poverty and Social Impact Analysis 2009: main roofing material","url":"https://catalog.ihsn.org/catalog/6064/variable/F2/V432?name=s7q8","publisher":"IHSN"},{"title":"Kunta Kinteh Island and Related Sites","url":"https://whc.unesco.org/en/list/761/","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-the-maldives","title":"Roofing in the Maldives","category":"world-roofing","type":"place","country":{"name":"Maldives","iso2":"MV"},"summary":"The coral stone mosques of the Maldives record a shift from coconut-palm thatch on timber roofs to clay tiles and then metal sheet.","body":"The Maldives is a chain of low coral atolls in the Indian Ocean, south-west of Sri Lanka. Its historic **coral stone mosques** were roofed with timber frames covered in coconut-palm thatch, and over the 20th century their roofs were re-covered with clay tiles, corrugated iron, aluminium and other metal sheet. These mosque roofs are the best-documented record of roofing in the country.\n\n## Climate and hazards\n\nThe climate is hot and humid all year, with monsoon rain. The Maldives is exposed to floods, tsunamis, storms and cyclones, and the low elevation of the islands makes flooding and storm surge a particular concern. Salt-laden sea air is hard on metal roof sheeting and fixings.\n\n## Roofing history\n\nThe surviving record of Maldivian roofing is concentrated in its mosques, built from the 17th to the 19th century. Their walls, platforms and sometimes columns were made of **coral stone**, cut from living *Porites* coral while still soft, then air-dried and assembled with tongue-and-groove joints. Roofs were of timber, mainly teak in the surviving examples, and were originally covered with coconut-palm thatch. Many have roofs in two or three tiers.\n\nThe roofs of these mosques record the changes in materials:\n\n- **Malé Friday Mosque** (*Hukuru Miskiy*, built 1658, minaret 1674): originally thatched; the roof was changed to corrugated iron between 1904 and 1912, rebuilt in teak in 1963 and later sheeted in aluminium. It has a three-tiered timber roof.\n- **Ihavandhoo Friday Mosque** (1701): a timber roof with no interior columns, whose thatch was replaced by clay tiles in the 1950s and by metal sheets in 2005.\n- **Meedhoo Friday Mosque** (about 1705): its coconut thatch was replaced with Indian clay tiles in the 1950s.\n- **Fenfushi Friday Mosque** (1692-1701), **Isdhoo Old Mosque** and **Malé Eid Mosque** (1815): two-tiered timber roofs now finished with modern metal roofing.\n\n## Traditional and vernacular roofs\n\nThe coral stone mosques show the highest-status form of Maldivian roofing: carved and lacquered timber ceilings and roof structures, originally thatched with coconut palm, over coral-stone walls.\n\n## Roofing today\n\nMost historic mosque roofs are now finished with modern metal roofing.\n\n## Codes, standards and regulation\n\nBuilding is regulated under the **Building Code of Maldives**, administered by the national ministry responsible for planning and infrastructure. A 2019 assessment supported by the World Bank found that the code needed supporting compliance documents and stronger disaster-risk provisions, together with better hazard data.\n\n## Notable roofs\n\n- **Coral Stone Mosques of Maldives**: six mosques submitted to UNESCO's Tentative List on 19 February 2013, at Ihavandhoo, Meedhoo, Malé (Friday Mosque and Eid Mosque), Fenfushi and Isdhoo.\n- **Malé Friday Mosque**: three-tiered timber roof over coral-stone walls with fine lacquer work.\n\n## Local roofing terms\n\n- *Hukuru Miskiy* (Dhivehi): Friday mosque\n\n## Sources and gaps\n\nDescriptions of traditional house roofs, as distinct from mosques, roof statistics and information on the roofing trade and domestic manufacturers: published information is limited.","key_facts":[{"label":"Traditional covering","value":"Coconut-palm thatch on timber frames"},{"label":"Later coverings","value":"Clay tiles (1950s), corrugated iron, aluminium and metal sheet"},{"label":"Heritage roofs","value":"Timber roofs of the coral stone mosques"},{"label":"UNESCO Tentative List","value":"Coral Stone Mosques of Maldives (2013)"},{"label":"Climate driver","value":"Tropical rain, storms, floods, tsunami"},{"label":"Building code","value":"Building Code of Maldives"}],"regions":["South Asia"],"aliases":["Maldivian roofing","roofs of the Maldives"],"related":["palm-thatch","attap-roof","clay-roof-tile","corrugated-iron","aluminum-roofing","coastal-corrosion","hip-roof","roofing-in-sri-lanka","roofing-in-india","kerala-sloping-roof"],"company":null,"sources":[{"title":"Coral Stone Mosques of Maldives","url":"https://whc.unesco.org/en/tentativelists/5812/","publisher":"UNESCO World Heritage Centre"},{"title":"Building regulations for resilience in Sri Lanka and the Maldives","url":"https://www.worldbank.org/en/news/feature/2019/07/15/building-regulations-for-resilience-in-sri-lanka-and-the-maldives-drmhubtokyo","publisher":"World Bank"}]},{"slug":"roofing-in-the-marshall-islands","title":"Roofing in the Marshall Islands","category":"world-roofing","type":"place","country":{"name":"Marshall Islands","iso2":"MH"},"summary":"Marshallese roofing: pandanus-thatched roofs on four posts with a rat-proof loft, largely replaced by galvanised and aluminium sheet.","body":"The traditional Marshallese house was essentially a roof: a pandanus-thatched gable on four posts, with a loft in the roof space and often no walls. Modern housing on the atolls uses galvanised iron, aluminium or concrete roofs. Detailed ethnographic records of traditional construction exist from around 1900 onward.\n\n## Climate and hazards\n\nThe Marshall Islands are low coral atolls with a hot, humid climate. Rainfall is higher in the south than in the drier northern atolls, which affected how long thatch lasted. Fresh water is limited, and roofs serve as rain catchments.\n\n## Roofing history\n\nScholars classify the Marshallese house as a transitional form between a ground-level house and a pile dwelling. Its roof sat on four main posts rising about 1.3-2 m (4-6.5 ft) above a floor of coral gravel covered with mats. Two roof plates and two cross-beams formed the base of the roof and the floor of a loft reached through a hatch; this loft, used for sleeping and for storing valuable mats, was called *im kidjerik* (\"rat house\") because its smooth posts kept rats out. King posts carried the ridge pole, and paired rafters passed beneath it.\n\nThatch units were made from brown, fallen pandanus leaves wrapped around a stick and tied with coconut-leaf ribs, laid from the eaves up to the ridge, which was capped with old mats or woven coconut fronds. A roof was said to stay watertight for one to two years, longer on the drier northern islands. Around 1900 newer houses had plank floors, and by the 1910s some posts stood on large stones; walls were increasingly added after European contact and the arrival of Christianity. Cooking houses were thatched with coconut leaves and had no loft.\n\n## Traditional and vernacular roofs\n\n- **Im / iem**: living house, with pandanus thatch and loft.\n- **Bellak**: cookhouse, coconut-thatched.\n- **Bui**: small raised hut for drying pandanus preserves.\n\n## Roofing today\n\nThe 2011 Census of Population and Housing recorded roof type in the categories galvanised/aluminium/tin, concrete, wood, fibreglass, thatch, and plastic or canvas tarpaulin. Imported metal sheet is the common modern roof.\n\n## Codes, standards and regulation\n\nBuilding is regulated under the Planning and Zoning Act 1987, with a code first issued in 1987 and updated in 2021.\n\n## Local roofing terms\n\n- **Im kidjerik**: loft, literally \"rat house\".\n- **Borwaj**: ridge pole. **Jur**: post. **Tur**: cross-beam.\n\n## Sources and gaps\n\nNo domestic roofing manufacturers were identified.\n\nCensus percentages for roof materials and sources on cyclone or storm-surge damage to roofs: published information is limited.","key_facts":[{"label":"Traditional materials","value":"Pandanus-leaf thatch, coconut-leaf ribs, timber posts"},{"label":"Thatch life","value":"About 1-2 years, longer in the drier north"},{"label":"Modern roofs","value":"Galvanised, aluminium or tin sheet; concrete"},{"label":"Building law","value":"Planning and Zoning Act 1987"}],"regions":["Oceania"],"aliases":["Marshallese roofing","RMI roofing"],"related":["palm-thatch","thatch","corrugated-iron","rainwater-harvesting-roofs","roofing-in-kiribati","roofing-in-micronesia","roofing-in-nauru","roofing-in-the-pacific-islands"],"company":null,"sources":[{"title":"Traditional and modern house construction on the Marshall Islands","url":"https://marshall.csu.edu.au/Marshalls/html/culture/Houses.html","publisher":"Charles Sturt University (Marshall Islands resource)"},{"title":"RMI Census of Population and Housing 2011, type of roof (MATERIAL_ROOF)","url":"https://datacatalog.ihsn.org/catalog/3170/variable/F2/V19?name=MATERIAL_ROOF","publisher":"IHSN Survey Catalog"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-the-middle-east-and-gulf","title":"Roofing in the Middle East and Gulf","type":"place","summary":"Overview of roofing in the Middle East and Gulf: flat masonry and concrete roofs, domes and windcatchers, with heat, sun and rare heavy rain as drivers.","body":"Across the Arabian Peninsula, the Levant, Mesopotamia and the Gulf, the defining roof is flat. Flat roofs are an ancient form, characteristic of Egyptian, Persian and Arabian architecture, and remain the norm for new buildings in the region today.\n\n## Why flat roofs dominate\n\nIn hot, dry regions with little rain, a roof does not need a steep pitch to shed water. Masonry and concrete roofs keep out solar heat thanks to their mass and are economical where timber is scarce. Flat roofs also provide valuable outdoor space: for sleeping on hot nights, drying crops and laundry, and, today, for water tanks, air-conditioning plant and solar panels.\n\n## Traditional construction\n\nTraditional flat roofs were made of timber poles or palm trunks spanning between thick walls, covered with layers of palm fronds, mats or reeds and then compacted earth or gypsum plaster. Spans were limited by the length of available timber, which in turn limited room widths. Where timber was even scarcer, rooms were roofed with masonry vaults and domes of mud brick, baked brick or stone.\n\n## Windcatchers\n\nTall ventilation towers, called *barjeel* in the Gulf and *badgir* in Iran, rise above flat roofs to catch breezes and vent hot air. In traditional Gulf merchant houses they were one of the main means of cooling before air conditioning. Windcatchers are seen as part of the shared architectural heritage of Iran, the Gulf and Egypt.\n\n## Modern practice\n\nReinforced concrete slabs with insulation and waterproofing are standard. Common waterproofing systems include bituminous and modified-bitumen membranes, single-ply membranes and liquid-applied coatings. High solar radiation and roof temperatures demand UV-stable materials, light or reflective surfaces and insulation, often placed above the waterproofing in inverted roof assemblies. Drainage falls are essential because ponding water accelerates deterioration; good practice aims to clear standing water within 48 hours.\n\n## Rain and dust\n\nAlthough rain is infrequent, intense storms can overwhelm poorly drained flat roofs. Dust and sand abrasion also shorten the life of exposed membranes and coatings.","key_facts":[{"label":"Dominant roof","value":"Flat masonry or concrete"},{"label":"Traditional structure","value":"Palm or timber beams with earth or gypsum"},{"label":"Cooling feature","value":"Windcatcher (barjeel / badgir)"},{"label":"Main drivers","value":"Heat, sun, scarce timber"}],"regions":["Middle East"],"aliases":["Gulf roofing","Arabian roofing","GCC roofing"],"related":["flat-roof","badgir","middle-eastern-domes","roofing-in-iran","cool-roof"],"sources":[{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"},{"title":"Windcatcher","url":"https://en.wikipedia.org/wiki/Windcatcher","publisher":"Wikipedia"},{"title":"Dome","url":"https://en.wikipedia.org/wiki/Dome","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-the-netherlands","title":"Roofing in the Netherlands","category":"world-roofing","type":"place","country":{"name":"Netherlands","iso2":"NL"},"summary":"Dutch roofing: ceramic pantiles and interlocking tiles, a thriving reed-thatch trade with strict fire rules, and flat roofs turning green and blue.","body":"The Netherlands is a flat, low-lying, densely populated country with a mild, wet and windy North Sea climate. Its traditional roofs are of two kinds: ceramic tiles, above all the S-shaped Dutch pantile (*Hollandse pan*), and water-reed thatch. Post-war housing and city buildings added large numbers of flat roofs, which are now being turned into green, blue and solar roofs.\n\n## Climate and hazards\n\nWind and rain are the main loads on Dutch roofs, and North Sea storms test the fixing of tiles and ridges. Because so much of the country lies low and water management is a national priority, holding back rainwater on roofs has become an important planning aim. Fire is the main regulatory concern for thatch, which is closely controlled in the national building decree.\n\n## Roofing history\n\nThatch was the ordinary roof of the North Sea lowlands for centuries. In towns, fire drove change: in the 16th century Holland required fireproof roofing materials in towns, which encouraged clay tiles and supported many small tile makers. Dutch tiles and slate moved both ways across the North Sea. Under Elizabeth I, quarries at Delabole in Cornwall shipped slate to the Netherlands, while from the early 17th century Dutch pantiles were exported to eastern England and Scotland. Dutch settlers also set up full-scale roof tile production in the upper Hudson valley of North America by 1650.\n\nAs tiles took over in towns, thatch became mainly a rural roof, used on farmhouses and barns. In the 20th century it changed status: once the roof of less well-off households, reed thatch is now often chosen for villas and even whole new neighbourhoods.\n\n## Traditional and vernacular roofs\n\n- **Hollandse pan**: a single-lap S-shaped clay pantile, traditionally orange-red, also made in glazed and smoked (blue-grey) finishes.\n- **Reed thatch** (*rieten dak*): water reed (*Phragmites australis*) laid in bundles on steep roofs of about 45-55 degrees, either stitched to battens (a *gebonden dak*) or screwed through to a closed deck (a *schroefdak*). Ridges are finished with clay ridge tiles, turf or, in modern work, metal or composite caps. One published Dutch detail specifies a reed layer 300 mm (12 in) thick.\n\n## Roofing today\n\nCeramic interlocking and pantile roofs are the norm on pitched-roof houses, with concrete tiles also used. Flat roofs on terraced housing, apartments and commercial buildings use bituminous, EPDM and other synthetic membranes, and Dutch cities increasingly promote green roofs and blue roofs (roofs that store rainwater temporarily). Thatch remains a living trade, but suitable reed is scarce, much of it is imported, and firms report a shortage of skilled thatchers.\n\n## Codes, standards and regulation\n\nBuilding work is governed nationally by the **Besluit bouwwerken leefomgeving** (Bbl, building decree). Article 4.47 requires the top surface of a roof to be \"not fire-dangerous\" when tested to the Dutch standard NEN 6063. Exceptions apply to buildings of up to 50 m² (about 540 ft²) of floor area, and to buildings without a raised habitable floor where the fire-dangerous roof parts are at least 15 m (49 ft) from the plot boundary. A thatched house closer than that to the boundary therefore needs an accepted fire-safe solution, such as an external fire-retardant coating (renewed about every five years), a roof sprinkler system, or a screwed thatch on a closed, fire-resistant deck accepted as an equivalent solution. European EN standards apply to roofing products.\n\n## Industry\n\nThe Vakfederatie Rietdekkers (Dutch thatchers' federation) publishes technical requirements and guidance for reed roofs, including joint guidance on fire-safe thatch details. Large international groups such as BMI (through its Monier brand) supply Dutch tile roofs.\n\n## Notable roofs\n\n- **House of the Five Senses** at the Efteling theme park in Kaatsheuvel, often described as having the largest thatched roof in the world.\n- The tiled roofscapes of historic Dutch towns, shaped by the 16th-century fire rules.\n\n## Local roofing terms\n\n- *Dakpan*: roof tile; *Hollandse pan*: Dutch pantile.\n- *Riet*: reed; *rietdekker*: thatcher.\n- *Gebonden dak*: stitched (bound) thatch; *schroefdak*: screwed thatch.\n- *Nok*: ridge.\n- *Gesmoord*: smoked (blue-grey) tile finish; *verglaasd*: glazed.\n\n## Sources and gaps\n\nHousing statistics on roof coverings and counts of thatched buildings: published information is limited.","key_facts":[{"label":"Classic tile","value":"Hollandse pan (Dutch pantile)"},{"label":"Traditional materials","value":"Clay pantiles, water-reed thatch"},{"label":"Fire rule (historic)","value":"Fireproof roofs required in Holland's towns, 16th century"},{"label":"Building code","value":"Besluit bouwwerken leefomgeving (Bbl)"},{"label":"Roof fire test","value":"NEN 6063 (Bbl Article 4.47)"},{"label":"Thatch pitch","value":"About 45-55°"}],"regions":["Europe"],"aliases":["Dutch roofing","Dakbedekking in Nederland"],"related":["pantile","dutch-and-danish-reed-thatch","water-reed-thatch","green-roof","roofing-in-the-netherlands-and-belgium","roofing-in-belgium","roofing-in-germany","roofing-in-the-united-kingdom","delabole-slate","bmi-group"],"company":null,"sources":[{"title":"Brandveilige rieten daken (Bbl)","url":"https://riet.com/uploads/brandvelige-rieten-daken-bbl.pdf","publisher":"Vakfederatie Rietdekkers"},{"title":"Populariteit rieten dak dwingt branche te innoveren","url":"https://www.riet.com/media/vfr/pdf/populariteit_rieten_dak_dwingt_branche_te_innoveren.pdf","publisher":"Vakfederatie Rietdekkers"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Pantile","url":"https://en.wikipedia.org/wiki/Pantile","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Delabole","url":"https://en.wikipedia.org/wiki/Delabole","publisher":"Wikipedia"}]},{"slug":"roofing-in-the-netherlands-and-belgium","title":"Roofing in the Netherlands and Belgium","type":"place","summary":"Overview of Low Countries roofing: ceramic pantiles and flat tiles, a living reed-thatch tradition and many flat roofs with membranes and greenery.","body":"The Netherlands and Belgium share a dense, low-lying landscape with a mild, wet and windy North Sea climate. Pitched roofs of ceramic tiles are the norm on traditional houses, while flat roofs are common on post-war housing and in cities.\n\n## Ceramic tiles\n\nThe Low Countries have long been centres of roof tile making. In the 16th century Holland required fireproof roofing materials in towns to reduce the spread of fire, which encouraged many small tile makers. The S-shaped pantile (*Hollandse pan*) is the classic Dutch roof tile and was exported to eastern England and Scotland from the early 17th century. Dutch settlers also established full-scale tile production in the upper Hudson Valley of North America by 1650. Today both regions produce and use large quantities of ceramic interlocking tiles, with glazed and smoked (blue-grey) finishes popular.\n\n## Reed thatch\n\nThatch with water reed remains a living tradition in the Netherlands, used on farmhouses, villas and some new public buildings, often at pitches of about 45-55 degrees. The House of the Five Senses at Kaatsheuvel is often described as having the largest thatched roof in the world. Belgium's Flanders and Kempen regions also retain thatched farmhouses.\n\n## Slate\n\nNatural slate is traditional in parts of Belgium, especially the Ardennes, which straddles the border with France and has its own slate quarrying history.\n\n## Flat roofs\n\nFlat roofs on terraced housing, apartments and commercial buildings use bituminous, EPDM and other synthetic membranes. Dutch and Belgian cities increasingly promote green and blue roofs to retain stormwater, a priority in such a low, wet landscape.\n\n## Standards\n\nProduct and performance standards follow European EN norms, with national building regulations in the Netherlands and regional regulations in Belgium.","key_facts":[{"label":"Classic tile","value":"Pantile (Hollandse pan)"},{"label":"Fire rule","value":"Fireproof roofs required in Holland in the 1500s"},{"label":"Thatch","value":"Water reed, still widely used"},{"label":"Climate","value":"Mild, wet, windy North Sea"}],"regions":["Europe"],"aliases":["Dutch roofing","Belgian roofing","Low Countries roofing"],"related":["pantile","dutch-and-danish-reed-thatch","green-roof","roofing-in-germany","roofing-in-the-united-kingdom"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Pantile","url":"https://en.wikipedia.org/wiki/Pantile","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-the-pacific-islands","title":"Roofing in the Pacific Islands","type":"place","summary":"Overview of Pacific Islands roofing: thatched timber buildings lashed with sennit, largely replaced by corrugated metal, built for cyclones.","body":"The islands of Polynesia, Melanesia and Micronesia share a tropical maritime climate with high rainfall, salt air and tropical cyclones. Traditional roofs used local timber, coconut fibre and leaf thatch; today corrugated metal sheet is the most common roof on houses and public buildings.\n\n## Traditional roofs\n\nThe Samoan *fale* is representative of western Polynesian building. It is round or oval with no walls, and its high domed roof is carried on timber posts. Before European contact no metal fasteners were used; the frame was lashed with *ʻafa*, a plaited coconut-husk sennit, and an ordinary fale used 30,000-50,000 ft (roughly 9-15 km) of it. Women made thatch from dried sugarcane leaves or coconut fronds, overlapped in a double layer, which lasted about seven years. Construction was led by master builders (*tufuga fau fale*).\n\nAcross the region, comparable buildings use pandanus, sago palm, coconut or grass thatch on timber or bamboo frames, often steeply pitched to shed rain quickly.\n\n## Change to metal\n\nCorrugated iron spread with colonial trade, mission building and later aid programmes. In Samoa today, many small beach fale and village cookhouses have iron roofs, and many houses are rectangular rather than round. Metal roofs are quick to build and collect clean rainwater, but they are hot and noisy and corrode quickly near the sea.\n\n## Cyclones\n\nCyclone resistance is the main structural concern. Recommended practice includes hip roofs rather than tall gables, short overhangs on exposed sides, heavier-gauge sheeting with closely spaced screws and washers, and strapping that ties roof framing to walls and foundations. After major cyclones, regional \"build back safer\" programmes have focused on these fixing details.\n\n## Water\n\nRoofs are a primary water source on many atolls and islands, feeding tanks and cisterns, so the roof material and its coatings matter for drinking-water quality.","key_facts":[{"label":"Traditional coverings","value":"Sugarcane, coconut, pandanus thatch"},{"label":"Traditional fixing","value":"Coconut-fibre sennit lashing"},{"label":"Modern covering","value":"Corrugated metal sheet"},{"label":"Main hazard","value":"Tropical cyclones"}],"regions":["Oceania"],"aliases":["Pacific roofing","Polynesian roofing","Melanesian roofing"],"related":["samoan-fale","wharenui","roofing-in-new-zealand","rainwater-harvesting-roofs"],"sources":[{"title":"Architecture of Samoa","url":"https://en.wikipedia.org/wiki/Architecture_of_Samoa","publisher":"Wikipedia"},{"title":"Fale","url":"https://en.wikipedia.org/wiki/Fale","publisher":"Wikipedia"},{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-the-philippines","title":"Roofing in the Philippines","category":"world-roofing","type":"place","country":{"name":"Philippines","iso2":"PH"},"summary":"Roofing in the Philippines runs from nipa and cogon thatch on stilt houses to colonial clay tile, and today about 86% of homes use galvanised iron or aluminium sheet.","body":"The Philippines is an archipelago of more than 7,000 islands with a hot, wet tropical climate. Its roofing history runs from steep thatched roofs on raised timber and bamboo houses, through the tile and stone houses of the Spanish colonial era, to a present in which galvanised iron and aluminium sheet covers the great majority of homes.\n\nBecause the country sits in a typhoon belt and on an active seismic zone, the main concerns for any Philippine roof are rapid shedding of heavy rain, resistance to wind uplift, light weight in earthquakes and, near the sea, corrosion from salt air.\n\n## Climate and hazards\n\nRoofs must cope with intense monsoon rain, high humidity and heat, typhoon winds, earthquakes and, locally, volcanic ashfall. Coastal installations face salt spray. These pressures explain the persistence of steep pitches, deep eaves and light roof structures in both traditional and modern building.\n\nWind uplift is the critical roof hazard. Typhoon Haiyan (Yolanda) in 2013 badly damaged heritage buildings across 14 provinces of the Visayas. Engineering studies of such buildings identify non-engineered roofs as the most vulnerable part of the envelope, and timber-framed roofs clad in galvanised iron sheet as highly susceptible. Two failure modes dominate: *pullout*, where uplift pulls screws or nails out of the purlins or rafters, and *pullover*, where the sheet tears around a fastener that stays in place. Post-event surveys link most economic loss in high winds to breaches of the building envelope.\n\n## Roofing history\n\nThe oldest surviving evidence of building in the country is landscape rather than architecture: according to UNESCO, the terracing technique used in the Ifugao rice terraces of northern Luzon has been practised for about 2,000 years, and these terraces are associated with villages of thatched houses and granaries.\n\nBefore Spanish colonisation, lowland houses (the forerunners of the *bahay kubo*) were roofed with nipa palm leaves or cogon grass. During the Spanish colonial period (1565-1898), a new urban house type emerged, the *bahay na bato* (\"stone house\"), with a masonry lower storey and a timber upper storey. Spanish plans for all-stone mansions were set back by a major Manila earthquake in 1645, and the twin dangers of fire and earthquake pushed builders to keep the light upper floor and other features of the native house.\n\nBahay na bato roofs were high-pitched, usually hipped, gabled, or a combination. Coverings included curved Spanish clay tiles (*teja de curva*), nipa, sago palm or cogon thatch, and, from the later 19th century, galvanised iron sheet. By the 2020 census, metal sheet had become the roof of the great majority of Philippine homes.\n\n## Traditional and vernacular roofs\n\n- **Bahay kubo (nipa hut).** A lowland house raised on posts, with a tall, steep thatched roof of nipa, cogon or anahaw leaves. A variant covering, *kalaka*, uses halved bamboo culms laid alternately face up and face down like clay tiles.\n- **Ifugao bale.** In the Cordillera, the Ifugao house stands on posts almost 2 m (6.5 ft) high and carries a thatched roof shaped like a pyramid, with a smoke outlet at its top. Each post has a thickened ledge near the top to stop rats climbing into the house. The living floor is small, usually 5-8 m2 (54-86 sq ft).\n- **Bahay na bato.** The colonial stone-and-timber house with a hipped (*cuatro aguas*) or gabled (*dos aguas*) roof. Hip roofs were favoured because they resist wind better and overhang all sides, shading walls and windows. Small shed roofs over windows are called *media agua*.\n\n## Roofing today\n\nThe 2020 Census of Population and Housing counted 28.50 million housing units, up from 21.29 million in 2010. Of occupied housing units in 2020, 85.9% had roofs of galvanised iron or aluminium, 4.7% had cogon, nipa or anahaw thatch, and 4.5% had concrete or clay tile. Outer walls were concrete, brick or stone in 60.4% of units, showing that a masonry house under a metal-sheet roof is now the typical Philippine dwelling.\n\nCorrugated and long-span profiled steel sheet, usually zinc- or zinc-aluminium-coated and often pre-painted, is used on houses, churches, schools, factories and warehouses. Reinforced concrete flat roofs are common on urban multi-storey buildings. Thatch survives mainly on rural houses, resort buildings and heritage structures.\n\n## Codes, standards and regulation\n\nThe National Building Code of the Philippines is Presidential Decree No. 1096, which took effect on 19 February 1977 and replaced Republic Act No. 6541 of 1972. It covers the design, construction, alteration, repair, use and demolition of public and private buildings, but traditional indigenous family dwellings are excluded from its general application. Revised Implementing Rules and Regulations were issued by the Department of Public Works and Highways (DPWH) in October 2004 and took effect on 1 May 2005.\n\nSection 301 of the code requires a building permit before a building is erected, altered, repaired or demolished. The DPWH Secretary administers the code, supported by the National Building Code Development Office, while local building officials issue permits and inspect work. Structural matters, including wind and earthquake loads on roofs, are handled through referral codes that the DPWH adopts, principally the National Structural Code of the Philippines (NSCP). Its 2015 edition bases wind-load calculations on the American standard ASCE 7-10. Design wind speeds vary by location and building risk category; for Category III structures, published examples include 250 km/h (about 155 mph) for Manila, 260 km/h (162 mph) for Cebu and 270 km/h (168 mph) for Bohol.\n\n## Industry\n\nThe roofing market is dominated by steel sheet, roll-formed locally from coated coil, alongside clay and concrete tile and fibre-cement products.\n\n## Notable roofs\n\n- **Rice Terraces of the Philippine Cordilleras** (UNESCO World Heritage): the Mayoyao cluster has terraces interspersed with traditional farmhouses (*bale*) and granaries (*alang*). The site was placed on the List of World Heritage in Danger in 2001 and removed from it in 2012.\n- Surviving bahay na bato in historic towns show tiled, galvanised iron and occasionally thatched roofs side by side.\n\n## Local roofing terms\n\n- *bale* - Ifugao house; *abong* - hut; *alang* - granary (Ifugao)\n- *cuatro aguas* - hip roof; *dos aguas* - gable roof (Spanish colonial)\n- *media agua* - small shed roof over a window\n- *teja de curva* - curved Spanish clay tile\n- *kalaka* - halved bamboo used as roof \"tiles\"\n- *nipa*, *cogon*, *anahaw* - palm leaf and grass thatch materials\n\n## Sources and gaps\n\nNational roofing trade association data, information on national roofing manufacturers and the full NSCP wind-zone map: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Galvanised iron/aluminium sheet (85.9% of occupied housing units, 2020 census)"},{"label":"Thatch share","value":"4.7% cogon, nipa or anahaw (2020)"},{"label":"Traditional materials","value":"Nipa, cogon and anahaw thatch; halved bamboo (kalaka); Spanish clay tile"},{"label":"Climate driver","value":"Typhoons, monsoon rain, earthquakes"},{"label":"Building code","value":"Presidential Decree No. 1096 (in force 19 February 1977)"},{"label":"Structural code","value":"NSCP 2015 (wind loads based on ASCE 7-10)"}],"regions":["Southeast Asia"],"aliases":["Philippine roofing","Filipino roofing","bubong"],"related":["roofing-in-southeast-asia","bahay-kubo","bahay-na-bato","ifugao-house","palm-thatch","bamboo-roofing","corrugated-iron","metal-roofing","clay-roof-tile","spanish-tile","hip-roof","roofing-in-indonesia","roofing-in-malaysia","roofing-in-vietnam"],"company":null,"sources":[{"title":"Housing units in PH reach 28.5 million in 2020 (PSA census results)","url":"https://realestatenews.ph/national/housing-units-in-ph-reach-285-million-in-2020","publisher":"Real Estate News PH"},{"title":"Bahay na bato","url":"https://en.wikipedia.org/wiki/Bahay_na_bato","publisher":"Wikipedia"},{"title":"National Building Code of the Philippines","url":"https://en.wikipedia.org/wiki/National_Building_Code_of_the_Philippines","publisher":"Wikipedia"},{"title":"House model (Balbale)","url":"https://philippinestudies.uk/mapping/items/show/14911","publisher":"Philippine Studies at SOAS (Mapping Philippine Material Culture)"},{"title":"Rice Terraces of the Philippine Cordilleras","url":"https://whc.unesco.org/en/list/722/","publisher":"UNESCO World Heritage Centre"},{"title":"WARP^2: Wind Assessment of Roofs to Pullout & Pullover for Priority Cultural Heritage Structures in the Philippines (ICASP13, 2019)","url":"https://discovery-pp.ucl.ac.uk/10082984/1/369.pdf","publisher":"University College London (Song, Galasso, Garciano)"},{"title":"NSCP 2015 wind load calculations","url":"https://skyciv.com/docs/load-generator/wind/nscp-2015-wind-load-calculations/","publisher":"SkyCiv"}]},{"slug":"roofing-in-the-republic-of-the-congo","title":"Roofing in the Republic of the Congo","category":"world-roofing","type":"place","country":{"name":"Republic of the Congo","iso2":"CG"},"summary":"In the Republic of the Congo, village houses are mostly mud brick with thatched or metal roofs, while urban houses in Brazzaville and Pointe-Noire are concrete.","body":"The Republic of the Congo (Congo-Brazzaville) lies on the west bank of the Congo and Ubangi rivers, with equatorial forest in the north, savanna plateaus in the centre and a short Atlantic coastline around Pointe-Noire. Most of its people live in the urban corridor from Brazzaville to Pointe-Noire, where houses are commonly built of concrete. In villages, houses are typically of mud brick with thatched or metal roofs.\n\n## Climate and hazards\n\nThe climate is equatorial and humid, with heavy rainfall and high temperatures for much of the year. Roofs must shed intense rain and resist rot, insects and mould; metal sheets bring heat gain, and on the coast salt air speeds corrosion.\n\n## Roofing history\n\nDetailed historical records of roofing are scarce. The lower Congo region was part of the cultural world of the old Kongo kingdom, whose capital, Mbanza Kongo, lies in present-day Angola. In the northern forests, Baka forest people build hemispherical leaf huts (*móngulu*) in their camps, a building tradition shared with forest peoples across Central Africa. Poles cut from the forest remain an important building material for houses across the Congo basin.\n\n## Traditional and vernacular roofs\n\n- **Mud-brick house with thatch**: the common village house, laid out along villages planned with one wide central dirt street crossed by smaller streets at right angles. Cooking and much social life take place at the front of the house.\n- **Móngulu**: dome-shaped leaf hut of the Baka (see Mongulu).\n- **Pole-framed houses**: forest poles are widely harvested for house frames in the Congo basin.\n\n## Roofing today\n\nIn villages, mud-brick houses are covered with either thatch or metal sheets; urban houses are made of concrete, often with a small garden. Nearly 90% of homes are owned by individuals or families.\n\n## Sources and gaps\n\nNo national roof-material figures were found in published sources. No individually documented landmark roofs were identified.\n\n National census or DHS roofing shares, historic architecture, codes and industry are not documented in published sources.","key_facts":[{"label":"Village houses","value":"Mud brick with thatched or metal roofs"},{"label":"Urban houses","value":"Concrete"},{"label":"Forest tradition","value":"Baka móngulu leaf domes"},{"label":"Climate driver","value":"Equatorial heat and heavy rain"}],"regions":["Africa"],"aliases":["Congo-Brazzaville roofing","roofs in the Republic of the Congo"],"related":["mongulu","thatch","corrugated-iron","palm-thatch","roofing-in-the-democratic-republic-of-the-congo","roofing-in-gabon","roofing-in-cameroon","roofing-in-the-central-african-republic","roofing-in-angola"],"sources":[{"title":"Culture of Republic of Congo","url":"https://www.everyculture.com/Bo-Co/Republic-of-Congo.html","publisher":"Countries and Their Cultures (everyculture.com)"},{"title":"Pygmy camp with leaf and bark huts","url":"https://pygmies.org/baka/camps.php","publisher":"pygmies.org"},{"title":"Socio-economics of Using Poles for Constructing Houses in the Congo Basin","url":"https://opendocs.ids.ac.uk/opendocs/handle/123456789/12916","publisher":"Institute of Development Studies OpenDocs"}],"company":null},{"slug":"roofing-in-the-solomon-islands","title":"Roofing in the Solomon Islands","category":"world-roofing","type":"place","country":{"name":"Solomon Islands","iso2":"SB"},"summary":"Solomon Islands roofing: sago-palm leaf thatch on timber frames, now mostly corrugated iron, with thatch still common in villages.","body":"Roofing in the Solomon Islands has long relied on the leaves of sago palms and other palms, sewn into thatch and laid on timber or bamboo frames. Corrugated iron has become the most common roof, but leaf roofs remain widespread in rural villages.\n\n## Climate and hazards\n\nThe islands have a hot, wet tropical climate with heavy rain and, like the rest of the region, are exposed to tropical cyclones. Steep thatch sheds rain quickly; metal roofs near the coast face salt corrosion.\n\n## Roofing history\n\nSago palms of the genus *Metroxylon*, including *Metroxylon salomonense*, grow across the Solomon Islands and Vanuatu. Botanist John Dowe's study of their traditional uses records that the palms are used throughout the region as house-building material: the leaves provide a durable thatch, and the leaf stalks (petioles) are used for supports and beams. Coconut and other palms are also used. Corrugated iron, as across the Pacific, spread with colonial trade and missions, and is now the majority roof.\n\n## Traditional and vernacular roofs\n\nTraditional houses use sewn sago-palm or other leaf thatch on frames of local timber and bamboo, lashed with vine or fibre. See [sago palm thatch](/sago-palm-thatch) and [palm thatch](/palm-thatch).\n\n## Roofing today\n\nIn the World Bank's 2020-21 high-frequency phone survey, 68.3% of responding households reported corrugated iron as the main roof of their dwelling, 3.4% other metal, 15.1% thatch or palm leaf, 5% roofing shingles, 2.4% wood planks and 1.3% palm or bamboo. These are unweighted case counts from the survey sample. The 2009 census used the categories wood; tin or corrugated iron; concrete; traditional material; and makeshift material.\n\n## Codes, standards and regulation\n\nA national building code was first published in 1990 and updated in 2022, and the National Building Standard Act was passed in 2025.\n\n## Sources and gaps\n\nPublished, detailed sources on Solomon Islands roofing are limited. No information on domestic roofing manufacturers was found in published sources.\n\nCensus reports with roof-material percentages (2009 and 2019) were not found; local-language roofing terms and notable roofs are not well documented in published sources.","key_facts":[{"label":"Dominant material today","value":"Corrugated iron (68.3% in a 2020-21 phone survey)"},{"label":"Traditional materials","value":"Sago palm (Metroxylon) leaf thatch, timber, bamboo"},{"label":"Thatch share","value":"15.1% thatch or palm leaf (2020-21 survey)"},{"label":"Climate drivers","value":"Heavy rain, tropical cyclones"},{"label":"Building law","value":"National Building Standard Act 2025"}],"regions":["Oceania"],"aliases":["Solomons roofing"],"related":["sago-palm-thatch","palm-thatch","thatch","corrugated-iron","roofing-in-papua-new-guinea","roofing-in-vanuatu","roofing-in-the-pacific-islands"],"company":null,"sources":[{"title":"Sago palms, Metroxylon (Arecaceae) in Vanuatu and the Solomon Islands: traditional and current uses (Dowe, 2002)","url":"https://researchonline.jcu.edu.au/14376/","publisher":"James Cook University"},{"title":"Solomon Islands High Frequency Phone Survey 2020, material for roof (s9q27)","url":"https://microdata.fao.org/index.php/catalog/2351/variable/V273","publisher":"World Bank / FAO Microdata"},{"title":"Solomon Islands Population and Housing Census 2009, main material for roof (H4)","url":"https://microdata.pacificdata.org/index.php/catalog/31/variable/F1/V6?name=H4","publisher":"Pacific Data Hub (SPC)"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-the-united-arab-emirates","title":"Roofing in the United Arab Emirates","category":"world-roofing","type":"place","country":{"name":"United Arab Emirates","iso2":"AE"},"regions":["Middle East"],"company":null,"summary":"UAE roofing: palm-frond arish houses, coral and mud-brick houses with windtowers, and modern concrete roofs under Estidama and Dubai green codes.","aliases":["UAE roofing","Emirati roofing","Roofing in the UAE","Roofs of the Emirates"],"body":"Within a single lifetime the United Arab Emirates went from palm-frond houses, mud-brick forts and coral-stone merchant houses to a skyline of modern towers. Today almost all buildings have flat reinforced concrete roofs, increasingly governed by green building rules in Abu Dhabi and Dubai.\n\n## Climate and hazards\n\nThe UAE has extremely hot summers and humid coasts. Traditional builders answered with shading, ventilation and windtowers; modern codes focus on insulation and energy use.\n\n## Roofing history\n\n**Prehistoric.** A house about 7,000 years old on Delma Island was built from palm trunks. Stone Age settlement in the territory dates from about 6000-3200 BC, and Al Ain, the first recorded large settlement, has Bronze Age (3200-1300 BC) buildings of cut and dressed stone. Qanat irrigation was introduced in the Iron Age (1300-300 BC).\n\n**Traditional towns.** Building materials came from the surroundings: coral, mud, stone, palm fronds and animal hair. Permanent inland houses were of mud brick strengthened with stones bonded by red clay and manure, finished with *guss*, a lime mixture of seashells, chalk and water. The Al Fahidi (Bastakiya) district of Dubai preserved 18th- and 19th-century houses with windtowers; it was largely demolished in the 1970s and 1980s and now consists of reconstructions.\n\n**Palm-frond houses.** Bedouin families used palm-frond *arish* shelters in summer. In the 1950s Dubai had up to 4,000 arish houses for about 12,000 people, and Liwa about 800. After oil was discovered in the late 1950s, concrete, glass and steel replaced them. See barasti.\n\n**Modern.** Dubai's town plan was commissioned in 1959 and the Dubai World Trade Centre tower completed in 1979. New buildings are reinforced concrete, sometimes styled to look like mud or coral.\n\n## Traditional and vernacular roofs\n\n- **Arish / barasti:** palm-frond walls and roofs, with frames reportedly of mangrove poles imported from East Africa.\n- **Flat roofs on poles:** coral-stone and mud houses roofed with imported poles, mats and earth (see chandal-roof).\n- **Barjeel (windtower):** vertical shafts of Iranian origin that catch breezes and draw air down into rooms. Nearly all reconstructed barjeels today are ornamental.\n- **Bait al sha'ar:** woven goat- or camel-hair tents of the Bedouin.\n\n## Roofing today\n\nFlat reinforced concrete roofs dominate housing and commercial building, with heat-resistant materials increasingly used.\n\n## Codes, standards and regulation\n\n- **Estidama Pearl Rating System (Abu Dhabi):** developed by the Abu Dhabi Urban Planning Council; since autumn 2010 all new developments must achieve at least one Pearl, and government buildings (and, per the federal portal, residential villas) two.\n- **Dubai green building regulations:** 79 specifications, mandatory for all developments.\n- **Federal green building standards:** approved by the UAE Cabinet in 2010 and applied first to government buildings from early 2011.\n\n## Industry\n\nThe arish revival is being studied by researchers such as Sandra Piesik.\n\n## Notable roofs\n\n- **Al Fahidi (Bastakiya), Dubai:** reconstructed windtower houses.\n- **Al Hisn Fort, Sharjah, and Hatta:** heritage reconstructions including arish.\n- **Al Ain:** Bronze Age stone buildings and tombs.\n\n## Local roofing terms\n\n- *arish* - palm-frond house or shelter\n- *barjeel* - windtower\n- *guss* - lime finish of seashells, chalk and water\n- *bait al sha'ar* - \"house of hair\", Bedouin tent\n\n## Sources and gaps\n\nDetailed climate data, data on roofing material shares, roof-specific requirements within the green building systems, and information on modern roofing materials and Emirati roofing manufacturers were not found in published sources.","key_facts":[{"label":"Traditional roofs","value":"Palm-frond arish; flat roofs on imported poles"},{"label":"Cooling","value":"Barjeel windtowers"},{"label":"Dubai arish houses, 1950s","value":"Up to 4,000"},{"label":"Abu Dhabi rating","value":"Estidama Pearl, 1 Pearl minimum since 2010"},{"label":"Modern","value":"Flat reinforced concrete"}],"related":["barasti","chandal-roof","badgir","flat-roof","cool-roof","protected-membrane-roof","roofing-in-oman","roofing-in-qatar","roofing-in-saudi-arabia","roofing-in-iran","roofing-in-the-middle-east-and-gulf"],"sources":[{"title":"Architecture of the United Arab Emirates","url":"https://en.wikipedia.org/wiki/Architecture_of_the_United_Arab_Emirates","publisher":"Wikipedia"},{"title":"Arish: the palm leaf's role in the past and future of sustainable architecture in the UAE","url":"https://www.thenationalnews.com/arts-culture/art/arish-the-palm-leaf-s-role-in-the-past-and-future-of-sustainable-architecture-in-the-uae-1.1051472","publisher":"The National"},{"title":"Pearl Rating System (Abu Dhabi)","url":"https://en.wikipedia.org/wiki/Pearl_Rating_System_(Abu_Dhabi)","publisher":"Wikipedia"},{"title":"Green building codes","url":"https://u.ae/en/information-and-services/environment-and-energy/the-green-economy-initiative/efforts-to-achieve-green-economy-/green-building-codes","publisher":"UAE Government portal (u.ae)"}]},{"slug":"roofing-in-the-united-kingdom","title":"Roofing in the United Kingdom","category":"world-roofing","type":"place","country":{"name":"United Kingdom","iso2":"GB"},"summary":"UK roofing: Welsh, Scottish and Cornish slate, clay and concrete tiles, stone slates and thatch, built for a wet, windy maritime climate.","body":"Most houses in the United Kingdom have pitched roofs designed for a mild but wet and windy maritime climate. Local geology has long decided what those roofs are made of: slate in Wales, Cornwall, the Lake District and Scotland, limestone and sandstone \"stone slates\" in the Cotswolds and Pennines, clay plain tiles and pantiles in the south and east, and thatch across rural England. Since the 20th century, interlocking concrete tiles have become the usual covering on new houses. Because so much of the housing stock is old, conserving traditional roofs is a large part of the UK roofing trade.\n\n## Climate and hazards\n\nWind is the main design load for most UK roofs. Driving rain and gusts at eaves, verges and ridges are why the national code of practice for slating and tiling, BS 5534, was revised in 2014 to require mechanical fixing rather than mortar alone, and to fix perimeter tiles twice. Structural wind and snow loads are calculated using the Eurocodes with UK National Annexes, as referenced in Part A of the Building Regulations. Fire is the special hazard for thatch: between 50 and 80 thatched roofs are lost to fire in the UK each year.\n\n## Roofing history\n\nRoman builders brought fired clay roof tiles to Britain after AD 43, and the Roman fort of Segontium at Caernarfon was roofed with local Welsh slate in the late second century. The Cilgwyn quarry in the Nantlle Valley is thought to date from the 12th century, and Delabole in Cornwall has been worked continuously since the 15th century. In medieval towns, fire drove regulation: after a major fire in 1212, London banned new thatched roofs, and the Great Fire of 1666 led to stricter rebuilding rules. Prestige buildings were covered in sheet lead; the roof of Westminster Hall carried about 176 tons of it.\n\nPantiles were imported from the Netherlands from the early 17th century and became typical of eastern coastal England and Scotland. Scottish slate from the Easdale islands roofed Castle Stalker in 1631, and by 1800 Easdale produced about 5 million slates a year. Industrial quarrying in north Wales began on a large scale at Penrhyn in 1782; by the late 19th century the region produced about a third of the world's roofing slates, and Welsh output peaked at over half a million tons in 1898. Canals and railways spread slate far from the quarries, and corrugated iron, patented in 1829, replaced thatch on many farm buildings.\n\nIn the 20th century, concrete roof tiles took over the new-build market. Redland, founded in 1919 as the Redhill Tile Company in Surrey, was one of the early producers. Scottish slate quarrying ended in 1965, and Welsh output fell steeply after the Second World War.\n\n## Traditional and vernacular roofs\n\n- **Thatch** survives on an estimated 60,000 UK properties. The three main English traditions are long straw, combed wheat reed and water reed (often called Norfolk reed). Some roofs in southern England retain base coats more than 500 years old.\n- **Stone slates** (geologically \"tilestones\") are split from limestone or sandstone and laid in diminishing courses, traditionally hung on oak pegs. Examples include Cotswold, Stonesfield, Collyweston and Horsham stone.\n- **Natural slate** from Wales, Cornwall, Cumbria and Scotland. Welsh slate was sold in named standard sizes; the largest, the Duchess, measures 24 by 12 in (610 by 305 mm).\n- **Clay plain tiles**, small double-lap tiles typical of southern and central England, also hung on walls as tile hanging.\n- **Pantiles**, S-shaped single-lap clay tiles of the east coast, from Norfolk and Yorkshire to Fife.\n\n## Roofing today\n\nConcrete interlocking tiles are the most common covering on new houses, with clay tiles and natural or fibre-cement slate also widely used. Most natural slate is now imported, chiefly from Spain, which supplies about 90% of Europe's natural roofing slate; in Scotland, the only genuine Scottish slate available is reclaimed. Flat roofs on extensions, garages and commercial buildings use built-up bitumen, modified bitumen, single-ply membranes and liquid-applied systems, and city planning policies increasingly ask for green roofs. Over 80% of the water reed used for UK thatching is imported.\n\n## Codes, standards and regulation\n\nIn England, building work must meet the Building Regulations, supported by statutory guidance in Approved Documents. Those most relevant to roofs are Part B (fire, including external fire performance of roof coverings), Part C (resistance to moisture) and Part L (energy, including insulation upgrades when a roof is re-covered). Wales, Scotland and Northern Ireland have their own regulations and guidance. The key product and workmanship standards are BS 5534:2014+A2:2018 for slating and tiling, BS 8612 for dry-fixed ridge, hip and verge systems, and BS 8000-6 for workmanship. Changing the roof material on a listed building normally requires listed building consent; Historic England, Historic Environment Scotland and Cadw publish technical guidance on traditional roofs.\n\n## Industry\n\nMajor UK pitched-roof manufacturers include BMI Redland (part of BMI Group) and Marley (part of Marshalls). The Austrian group Wienerberger bought the clay tile maker Keymer in 2014 and opened an electrically powered concrete tile plant at Sittingbourne, Kent, in 2025. Penrhyn Quarry in Wales, once the largest slate quarry in the world, is still worked, and Delabole has been worked into the 21st century. Plans to revive Scottish slate quarrying centre on Cullipool on Luing, where minerals planning consent was granted in 2024.\n\n## Notable roofs\n\n- **Slate Landscape of Northwest Wales**, inscribed as a UNESCO World Heritage Site in 2021.\n- **Westminster Hall**, London, whose medieval hammerbeam roof was covered in lead.\n- **St Paul's Cathedral**, whose dome by Christopher Wren is covered in lead over timber.\n- **Shakespeare's Globe**, London, rebuilt in 1997 with a water-reed thatch over a fire-protected roof, after the original theatre burned in 1613 when a stage cannon set its thatch alight.\n\n## Local roofing terms\n\n- *Delves*: shallow surface workings for stone slates.\n- *Torching*: lime mortar applied under slates or tiles to steady them.\n- *Liggers* and *spars*: hazel rods and pins used to secure thatch.\n- *Duchess*, *Countess*, *Lady*: traditional Welsh slate sizes.\n\n## Sources and gaps\n\nNational statistics on the share of each roof covering in the housing stock: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Concrete interlocking tile on new houses"},{"label":"Traditional materials","value":"Natural slate, stone slate, clay plain tile, pantile, thatch"},{"label":"Climate driver","value":"Wind and driving rain"},{"label":"Building code","value":"Building Regulations and Approved Documents (England); separate regimes in Wales, Scotland, NI"},{"label":"Slating and tiling standard","value":"BS 5534:2014+A2:2018"},{"label":"Thatched properties","value":"About 60,000 (2013 estimate)"}],"regions":["Europe"],"aliases":["British roofing","UK roofing","Roofing in Britain"],"related":["welsh-slate","welsh-slate-industry","scottish-slate","delabole-slate","english-thatch","history-of-thatch-in-britain","stone-slate","cotswold-stone-slate","pantile","plain-tile","concrete-roof-tile","bs-5534","uk-building-regulations","historic-england","roofing-in-ireland","roofing-in-france","natural-slate"],"company":null,"sources":[{"title":"The Slate Landscape of Northwest Wales","url":"https://whc.unesco.org/en/list/1633","publisher":"UNESCO World Heritage Centre"},{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Pantile","url":"https://en.wikipedia.org/wiki/Pantile","publisher":"Wikipedia"},{"title":"Sourcing Scottish slate in the 21st century","url":"https://www.designingbuildings.co.uk/wiki/Sourcing_Scottish_slate_in_the_21st_century","publisher":"Designing Buildings Wiki"},{"title":"Slate Industry","url":"https://easdalemuseum.org/slate-industry/","publisher":"Easdale Island Folk Museum"},{"title":"Delabole","url":"https://en.wikipedia.org/wiki/Delabole","publisher":"Wikipedia"},{"title":"Slate industry","url":"https://en.wikipedia.org/wiki/Slate_industry","publisher":"Wikipedia"},{"title":"Approved Documents","url":"https://www.gov.uk/government/collections/approved-documents","publisher":"GOV.UK"},{"title":"Stone slate roofing technical advice note","url":"https://cms.historicengland.org.uk/images-books/publications/stone-slate-roofing-technical-advice-note/stoneslate","publisher":"Historic England"},{"title":"Redland plc","url":"https://en.wikipedia.org/wiki/Redland_plc","publisher":"Wikipedia"},{"title":"Wienerberger","url":"https://en.wikipedia.org/wiki/Wienerberger","publisher":"Wikipedia"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"}]},{"slug":"roofing-in-the-united-states","title":"Roofing in the United States","category":"world-roofing","type":"place","country":{"name":"United States","iso2":"US"},"summary":"US roofing: from Pueblo earth roofs and bark longhouses to colonial shingles and slate; today asphalt shingles on houses and membranes on flat roofs, under ICC codes.","body":"The United States has one of the largest roofing markets in the world, spanning climates from hurricane coasts and hail-prone plains to snowy mountains and deserts. Its roofing history runs from Indigenous earth, bark, plank and hide roofs, through Spanish, English, Dutch and French colonial traditions, to the mass-produced asphalt shingle and single-ply membrane that dominate today.\n\nPractice is shaped by model building codes adopted state by state, by insurers, and by a contractor culture built around lightweight, quickly installed materials.\n\n## Climate and hazards\n\n- **Hurricanes** on the Gulf and Atlantic coasts, where roof uplift and water entry cause much of the damage (see hurricane-roof-damage).\n- **Hail** across the Great Plains and Texas, driving demand for impact-rated coverings.\n- **Snow and ice** in the northern states and mountains: snow loads, ventilation and eave protection against ice dams.\n- **Wildfire** in the West, where fire-rated roof assemblies are increasingly required.\n- **Heat and sun** in the South and Southwest, where reflective cool roofs are encouraged by energy codes.\n\n## Roofing history\n\n**Ancestral Puebloan roofs.** In the Southwest, Ancestral Puebloan builders between about 750 and 1300 CE roofed rooms with round timber beams (*vigas*) carrying smaller poles (*latillas*), finished with brush and a gently sloped layer of earth. Pueblo Bonito at Chaco Canyon, built between about 850 and 1150 CE, still shows vigas or the sockets they left. Taos Pueblo, a UNESCO World Heritage Site occupied since the late 13th or early 14th century, keeps its adobe in repair by regular replastering (see viga-and-latilla-roof).\n\n**Bark, plank, earth and hide.** In the Northeast, Haudenosaunee longhouses were framed with bent poles and sheathed in elm bark, with vents above the hearths (see longhouse-roof). On the Pacific Northwest coast, gabled and shed-roofed houses were covered with split cedar planks; a rectangular building at the Maurer site has been dated to between 2830 and 1920 BCE (see plank-house). On the Plains, Mandan, Hidatsa, Arikara and Pawnee villages built domed earth lodges from the early 1500s, with a timber frame, thatch, and thick sod over the top, while mobile Plains peoples used the hide-covered tipi with two adjustable smoke flaps.\n\n**Colonial roofs.** Early colonial houses in New England were framed heavily in the English way to carry slate or tile, but timber was plentiful and hand-split wood shingles soon became the normal covering: oak and white cedar in southern New England, eastern white pine further north. Slate was quarried in New England in the 1600s but rarely used until city fires after about 1800 led some towns to require it; quarrying then grew in Vermont, Maine and New York. Spanish colonial building introduced fired clay tile, a tradition still visible on roofs in the Southwest, Florida and California.\n\n**Industrial era.** Imported sheet lead was available in the 17th century and sheet copper from the late 18th, both expensive. Tin-plated and then terne-coated iron and steel sheet were in common use by the mid-19th century, mainly on low-slope roofs, and stamped metal shingles appeared late in the century. On the treeless Great Plains of the 19th and early 20th centuries, settlers built sod houses whose earth roofs leaked badly in rain.\n\n**Asphalt.** Asphalt-saturated felts arrived in the 1880s as roll roofing, then as individual shingles; by about 1915 three-tab strips were on sale, coloured to imitate wood or slate. By 1939 US production had reached about 11 million squares (see history-of-asphalt-shingles).\n\n## Traditional and vernacular roofs\n\n- **Viga-and-latilla flat roof** (Spanish *viga*, beam; *latilla*, lath), Southwest.\n- **Bark longhouse**, Northeast; **cedar plank house**, Pacific Northwest.\n- **Earth lodge** and **tipi**, Great Plains.\n- **Sod house** (\"soddy\"), Great Plains settlers.\n- **Wood shingle and shake** roofs of New England and later the Pacific Northwest, where western red cedar became the standard species and was shipped east by about 1900.\n- **Spanish clay tile** in the Southwest, Florida and California.\n- **Pueblo Revival** buildings of the 1920s and 1930s, which use vigas mainly as ornament.\n\n## Roofing today\n\nAsphalt shingles are the most common covering on American houses because of low first cost and simple installation. Two main types are sold: thin three-tab shingles and thicker laminated \"architectural\" shingles. Other residential coverings include metal (standing seam and stamped panels), concrete and clay tile in the Sunbelt, wood shakes in the West, and slate in older Northeastern housing.\n\nOn large low-slope roofs, built-up roofing, modified bitumen and single-ply membranes are used; TPO had become the most popular commercial low-slope covering by 2016, alongside EPDM and PVC. The National Roofing Contractors Association treats roofs of 3:12 (about 14°) or less as low-slope.\n\nThe US Census Bureau's American Housing Survey asks about roof condition rather than material. Its 2023 data, as analysed by trade press, counted nearly 6 million households reporting roof leaks, 3.5 million with missing roofing material, 1.9 million with sagging roofs and 1.5 million with holes.\n\n## Codes, standards and regulation\n\nMost states and cities adopt the International Residential Code and International Building Code, published by the International Code Council every three years since 2000, often with local amendments. Structural loads follow ASCE 7. Product standards are mainly ASTM and UL documents: ASTM D3462 for glass-mat asphalt shingles, ASTM D3161 and D7158 for wind resistance, and UL 2218 for impact resistance, where Class 4 is the highest rating.\n\nFlorida adopted a unified statewide code in 2002 after Hurricane Andrew (1992), with stricter High-Velocity Hurricane Zone rules in Miami-Dade and Broward counties (see miami-dade-noa and florida-product-approval). Voluntary programmes such as the IBHS FORTIFIED Roof go beyond code minimums. Roofing contractor licensing is set by individual states and varies widely.\n\n## Industry\n\nThe market is served by national shingle, membrane and metal manufacturers and by trade bodies including the National Roofing Contractors Association and the Cedar Shake and Shingle Bureau.\n\n## Notable roofs\n\n- **Taos Pueblo**, New Mexico: multi-storey adobe complexes with earth roofs, a UNESCO World Heritage Site.\n- **Pueblo Bonito**, Chaco Canyon: surviving viga sockets from the 9th-12th centuries.\n- **Palace of the Governors**, Santa Fe: a reconstructed building combining structural and ornamental vigas.\n\n## Local roofing terms\n\n- *Viga* / *latilla* (Spanish): beam / lath in Southwestern flat roofs.\n- *Portal* (Spanish): porch roofed with projecting vigas.\n- *Square*: 100 ft² (9.29 m²) of roof, the unit used in ordering and pricing.\n- *Soddy*: a sod house of the Plains.\n\n## Sources and gaps\n\nThe Census Bureau does not publish a national table of main roofing material for existing homes, so shares by material are not given.","key_facts":[{"label":"Dominant residential covering","value":"Asphalt shingles"},{"label":"Common commercial membranes","value":"TPO, EPDM, PVC, modified bitumen, BUR"},{"label":"Model codes","value":"IRC / IBC (ICC), ASCE 7 loads"},{"label":"Earliest surviving roof technique","value":"Ancestral Puebloan viga-and-latilla, c. 750-1300 CE"},{"label":"Roof problems (AHS 2023)","value":"~6 million households report leaks"},{"label":"Climate drivers","value":"Hurricanes, hail, snow, wildfire"}],"regions":["North America"],"aliases":["US roofing","American roofing","Roofing in the USA"],"related":["asphalt-shingle","history-of-asphalt-shingles","metal-roofing","international-residential-code","international-building-code","miami-dade-noa","florida-product-approval","hurricane-roof-damage","ibhs-fortified-roof","wood-shingle","wood-shake","viga-and-latilla-roof","longhouse-roof","plank-house","earth-lodge","sod-roof","flat-roof","roofing-in-canada","roofing-in-mexico","roofing-in-puerto-rico","cedar-shake-and-shingle-bureau","tpo-roofing"],"company":null,"sources":[{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"},{"title":"International Residential Code","url":"https://en.wikipedia.org/wiki/International_Residential_Code","publisher":"Wikipedia"},{"title":"Florida Building Code","url":"https://en.wikipedia.org/wiki/Florida_Building_Code","publisher":"Wikipedia"},{"title":"Roofing History","url":"https://www.historicnewengland.org/wp-content/uploads/2016/09/Roofing_History.pdf","publisher":"Historic New England"},{"title":"Worst roofs in America: data on leaks, holes and sagging","url":"https://www.roofingcontractor.com/articles/100645-worst-roofs-in-america-data-on-leaks-holes-and-sagging","publisher":"Roofing Contractor"},{"title":"Viga (architecture)","url":"https://en.wikipedia.org/wiki/Viga_(architecture)","publisher":"Wikipedia"},{"title":"Taos Pueblo","url":"https://whc.unesco.org/en/list/492/","publisher":"UNESCO World Heritage Centre"},{"title":"Longhouse","url":"https://www.thecanadianencyclopedia.ca/en/article/longhouse","publisher":"The Canadian Encyclopedia"},{"title":"Plank house","url":"https://en.wikipedia.org/wiki/Plank_house","publisher":"Wikipedia"},{"title":"Earth lodge","url":"https://en.wikipedia.org/wiki/Earth_lodge","publisher":"Wikipedia"},{"title":"Tipi","url":"https://en.wikipedia.org/wiki/Tipi","publisher":"Wikipedia"},{"title":"Sod house","url":"https://en.wikipedia.org/wiki/Sod_house","publisher":"Wikipedia"}]},{"slug":"roofing-in-timor-leste","title":"Roofing in Timor-Leste","category":"world-roofing","type":"place","country":{"name":"Timor-Leste","iso2":"TL"},"summary":"Roofing in Timor-Leste, from tall thatched sacred houses (uma lulik) to a housing stock where 81% of roofs were modern materials such as metal sheet by 2015.","body":"Timor-Leste occupies the eastern half of the island of Timor and the Oecusse exclave. Its traditional architecture is defined by tall thatched clan houses raised on posts, while most homes today have metal-sheet, tile or concrete roofs.\n\n## Climate and hazards\n\nThe country has a tropical climate with a pronounced wet season, mountainous terrain and coastal lowlands. Roofs must shed intense seasonal rain, cope with heat, and in exposed areas resist strong winds. Steep pitches on traditional houses reflect these conditions.\n\n## Roofing history\n\nLittle archaeological evidence for early roof construction has been published. Documentary and ethnographic sources describe a long tradition of clan origin houses with high thatched roofs, built of local hardwood, bamboo and palm materials.\n\nDuring the Indonesian occupation (1975-1999) many sacred clan houses were destroyed. Since independence in 2002 there has been a sustained \"return to custom\", including phased rebuilding of these houses as rural incomes have improved. Anthropological work on the Fataluku of the far east of the island describes a delayed re-emergence of their origin houses and recent innovations within traditional construction.\n\n## Traditional and vernacular roofs\n\nThe *uma lulik* (Tetum: *uma*, house; *lulik*, sacred) is the clan's sacred house, where heirlooms (*sasan lulik*) are kept. Typical features recorded in recent descriptions:\n\n- a raised platform, with the shaded space beneath used for gatherings;\n- a frame of hardwood and bamboo, with planks, tied with rope made from native palms rather than fixed with nails;\n- a high-pitched roof covered in natural thatch or coconut leaves.\n\nIn Lautem municipality, the Fuiloro community builds square houses up to about 9 m (30 ft) high.\n\n## Roofing today\n\nThe 2015 Population and Housing Census grouped roofs into \"modern\" (concrete, corrugated iron, tiles and asbestos) and \"traditional\" (palm leaves, thatch, grass). Nationally, 81.1% of houses had modern roofs in 2015, up from 68% in 2010. Modern roofs covered 96.5% of urban and 75.6% of rural houses; about one in four rural houses (24.4%) still had a traditional roof. Corrugated metal sheet is the most visible modern roofing in towns and villages.\n\n## Notable roofs\n\nRebuilt *uma lulik* in rural districts, including the tall houses of the Lautem area, are the country's best-known traditional roofs.\n\n## Local roofing terms\n\n- *uma lulik* - sacred (origin) house\n- *sasan lulik* - sacred heirlooms kept in the house\n\n## Sources and gaps\n\nDetailed breakdowns of roofing by individual material, descriptions of each regional house type, and codes and industry information: published information is limited.","key_facts":[{"label":"Modern roofs","value":"81.1% of houses (2015 census), up from 68% in 2010"},{"label":"Traditional roofs","value":"18.9% nationally; 24.4% in rural areas (2015)"},{"label":"Traditional materials","value":"Palm leaf, thatch, grass on hardwood and bamboo frames"},{"label":"Iconic building","value":"Uma lulik (sacred house)"}],"regions":["Southeast Asia"],"aliases":["East Timor roofing","Timorese roofing"],"related":["roofing-in-southeast-asia","uma-lulik","palm-thatch","thatch","corrugated-iron","roofing-in-indonesia","roofing-in-australia"],"company":null,"sources":[{"title":"2015 Census thematic report: Housing characteristics and amenities","url":"https://inetl-ip.gov.tl/wp-content/uploads/2023/05/2015-Housing-characterics-thematic-report_consolidated.pdf","publisher":"General Directorate of Statistics, Timor-Leste / UNFPA"},{"title":"Housing Characteristics & Amenities: Summary of the Thematic Report, Census 2015","url":"https://www.laohamutuk.org/DVD/DGS/Cens15/2015-Summary-of-the-Thematic-Report-on-Housing.pdf","publisher":"General Directorate of Statistics, Timor-Leste (via La'o Hamutuk)"},{"title":"Uma Lulik: the secret sacred houses of Timor-Leste","url":"https://seasia.co/2026/08/27/uma-lulik-the-secret-sacred-houses-of-timor-leste","publisher":"Seasia"},{"title":"Refashioning Fataluku origin houses (in Economic Diversity in Contemporary Timor-Leste, Leiden University Press, 2023)","url":"https://researchers.westernsydney.edu.au/en/publications/refashioning-fataluku-origin-houses/","publisher":"Western Sydney University"}]},{"slug":"roofing-in-togo","title":"Roofing in Togo","type":"place","country":{"name":"Togo","iso2":"TG"},"summary":"Togo's roofs are now mostly metal sheet, replacing the thatch still common in 2010; the Batammariba tower-houses of Koutammakou are its roofing landmark.","body":"Togo is a narrow country running inland from the Gulf of Guinea, from a humid coast through forested hills to savanna in the north. Its traditional roofs were thatch over earth walls in most regions and, in the far north, the earth terraces and granaries of the Batammariba tower-houses. Household surveys show a rapid shift to metal sheet during the 2010s.\n\n## Climate and hazards\n\nThe south has a humid tropical climate with two rainy seasons; the north has one rainy season and a long dry season with harmattan dust. Heavy rains damage earth and thatch buildings: in August 2018, storms caused enough damage in Koutammakou that UNESCO's Heritage Emergency Fund financed an assessment mission. Heat gain through thin metal roofs is a comfort issue.\n\n## Roofing history\n\nThe Batammariba (Tammari) peoples settled in the Koutammakou area of northern Togo and neighbouring Benin in the 17th or 18th century, bringing their tradition of earthen tower-houses. Elsewhere, roofs of grass and palm-leaf thatch were widespread; they were still recorded on almost a quarter of households surveyed in 2010.\n\n## Traditional and vernacular roofs\n\n- **Takienta (tower-house)**: a cluster of linked earth towers on a circular or elliptical plan, with livestock at ground level and granaries standing on the roof terrace. Earth, wood and straw are the main materials. About 1,716 are still inhabited on the Togolese side of Koutammakou (see Batammariba takienta).\n- **Thatch**: grass and palm-leaf thatch over earth or timber framing, still recorded on a minority of homes.\n\n## Roofing today\n\nTwo rounds of the Multiple Indicator Cluster Survey (MICS) show the change. Figures below are unweighted counts in the household survey samples:\n\n| Main roof material | MICS 2010 | MICS 2017 |\n|---|---|---|\n| Metal sheet (2010: \"zinc/fibre cement\"; 2017: \"metal/aluminium\") | 65.7% | 71.1% |\n| Thatch or palm leaf | 22.7% | 3.7% |\n| Grass | 1.9% | 4.7% |\n| Cement or concrete slab | 3.8% | 4.9% |\n| Fibre cement (2017 category \"calamine/fibre de ciment\") | - | 4.2% |\n| Ceramic tiles | 2.3% | 3.1% |\n| Shingles | 0.7% | 1.8% |\n\nCategory definitions changed between rounds, so the figures are not perfectly comparable. Even so, they show thatch and palm-leaf roofs falling from more than a fifth of households to under a tenth (including grass), with metal sheet and concrete taking their place.\n\n## Codes, standards and regulation\n\nThe houses of Koutammakou are protected as part of a World Heritage property, with management shared with Benin since the 2023 extension.\n\n## Notable roofs\n\n- **Koutammakou, the Land of the Batammariba**: earthen tower-houses with roof-terrace granaries, a World Heritage site since 2004. UNESCO notes that new detached houses with metal (\"tin\") roofs and the growing scarcity of wood and straw are among the pressures on the traditional houses.\n\n## Local roofing terms\n\n- **tôle** (French): metal roof sheet.\n- **dalle** (French): concrete roof slab.\n- **takienta / sikien** (Ditammari): tower-house / tower-houses.\n\n## Sources and gaps\n\nSurvey figures are unweighted sample counts. Information on southern Togolese vernacular roofs, codes and industry: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Metal sheet, 71.1% (MICS 2017 file, unweighted)"},{"label":"Thatch and palm leaf","value":"22.7% (2010) to 3.7% (2017)"},{"label":"Traditional materials","value":"Earth, grass and palm thatch, wood, straw"},{"label":"Climate driver","value":"Tropical rains, harmattan (north)"},{"label":"Landmark","value":"Koutammakou tower-houses (UNESCO 2004)"}],"regions":["Africa"],"aliases":["Togolese roofing","roofing in Togo"],"related":["roofing-in-west-africa","batammariba-takienta","corrugated-iron","thatch","palm-thatch","roofing-in-benin","roofing-in-ghana","roofing-in-burkina-faso"],"sources":[{"title":"MICS 2010 Togo: matériau principal du toit (HC4)","url":"https://microdata.worldbank.org/catalog/2002/variable/F3/V385?name=HC4","publisher":"World Bank Microdata Library"},{"title":"MICS 2017 Togo: main roof material (HC5)","url":"https://microdata.worldbank.org/catalog/4176/variable/F5/V1013?name=HC5","publisher":"World Bank Microdata Library"},{"title":"Koutammakou, the Land of the Batammariba","url":"https://whc.unesco.org/en/list/1140/","publisher":"UNESCO World Heritage Centre"},{"title":"Koutammakou","url":"https://en.wikipedia.org/wiki/Koutammakou","publisher":"Wikipedia"},{"title":"UNESCO's Heritage Emergency Fund supports Koutammakou (Togo) damage assessment","url":"https://whc.unesco.org/en/news/1932","publisher":"UNESCO World Heritage Centre"}],"company":null,"category":"world-roofing"},{"slug":"roofing-in-tonga","title":"Roofing in Tonga","category":"world-roofing","type":"place","country":{"name":"Tonga","iso2":"TO"},"summary":"Tongan roofing: lashed fale structures survive mainly in churches and halls; nearly all homes now have metal roofs, tested by Cyclone Gita.","body":"Tonga shares the western Polynesian tradition of the *fale*, a lashed timber building with a large thatched roof, but today almost all Tongan homes have metal roofs. The fale form and the craft of *lalava* (decorative lashing) live on mainly in churches, halls and tourism buildings. Tropical Cyclone Gita in 2018, the strongest to hit Tongatapu since 1982, destroyed or damaged thousands of houses.\n\n## Climate and hazards\n\nTonga lies in the South Pacific cyclone belt. Cyclone Gita passed over Tongatapu and ʻEua around 11 pm on 12 February 2018; it was the strongest cyclone to hit those islands since Cyclone Isaac in 1982. A government and World Bank assessment estimated its total effect at about US$164.1 million, or 37.8% of 2017 GDP. More than 800 houses were destroyed and about 4,000 damaged, and housing accounted for about 53% of all damage costs, the largest of any sector.\n\n## Roofing history\n\nTongan history is anchored by monumental stone architecture as well as timber building: the *langi* at Muʻa, large low stone pyramids associated with the Tuʻi Tonga, whose maritime power peaked around 1200-1500 AD, are prominent monumental stone structures. Methodist missionaries arrived in 1822 and the first chapel, built in 1826, was itself a fale. In the late 19th century the Royal Palace and the old Parliament building were prefabricated in New Zealand and shipped to Nukuʻalofa.\n\nArchitect and writer Bill McKay has observed that few fale are now used as dwellings in Tonga, possibly because the main island is a few degrees cooler than elsewhere in the region. The village of Kolovai shows the fale evolving with Western materials and methods.\n\n## Traditional and vernacular roofs\n\n- **Fale**: lashed timber house with a large roof, related to the [Samoan fale](/samoan-fale).\n- **Lalava**: Tongan decorative lashing, now seen in churches and resort-style buildings such as those on Fafa island.\n- The Pelehake Free Wesleyan Church (1986, architect George Moala) uses a customary lashed-pole structure.\n\n## Roofing today\n\nIn the 2019 Multiple Indicator Cluster Survey, 95.4% of household records listed metal or tin as the main roof material; cardboard (1.8%), wood planks (1.5%) and cement (0.6%) made up most of the rest, and thatch was almost absent. These are unweighted case counts from the survey sample.\n\n## Codes, standards and regulation\n\nBuilding is regulated under the Building Control and Standards Act 2002. The National Building Code was first issued in 2001 and updated in 2007; 2018 revisions remained in draft according to a regional review of Pacific building codes.\n\n## Notable roofs\n\n- **Pelehake Free Wesleyan Church** (1986), with a lashed-pole roof structure.\n- **Royal Palace**, Nukuʻalofa, a late-19th-century prefabricated timber building from New Zealand.\n\n## Local roofing terms\n\n- **Fale**: house. **Lalava**: decorative structural lashing.\n- **Langi**: royal stone tombs (not roofs, but key heritage structures).\n\n## Sources and gaps\n\nNo information on domestic roofing manufacturers was found in published sources.\n\nRoof-material tables from the 2016 and 2021 censuses were not found and published sources on traditional Tongan thatch materials are limited.","key_facts":[{"label":"Dominant material today","value":"Metal/tin (95.4% of MICS 2019 household records)"},{"label":"Traditional materials","value":"Timber frame, lalava sennit lashing, thatch"},{"label":"Climate driver","value":"Cyclones (TC Gita, 12 February 2018)"},{"label":"Gita impact","value":"Over 800 houses destroyed, about 4,000 damaged"},{"label":"Building law","value":"Building Control and Standards Act 2002; code 2007"}],"regions":["Oceania"],"aliases":["Tongan roofing"],"related":["samoan-fale","roofing-in-samoa","roofing-in-fiji","corrugated-iron","thatch","wind-uplift","hurricane-roof-damage","roofing-in-the-pacific-islands"],"company":null,"sources":[{"title":"A guide to the architecture of the Pacific: Kingdom of Tonga","url":"https://architecturenow.co.nz/articles/a-guide-to-the-architecture-of-the-pacific-kingdom-of-tonga/","publisher":"Architecture Now"},{"title":"Tonga MICS 2019, main material of roof (HC5)","url":"https://microdata.worldbank.org/catalog/4177/variable/F1/V153?name=HC5","publisher":"World Bank Microdata Library"},{"title":"Post-disaster rapid assessment: Tropical Cyclone Gita","url":"https://www.gfdrr.org/sites/default/files/publication/WB_Tonga_Report_FA07.pdf","publisher":"Government of Tonga / World Bank (GFDRR)"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-trinidad-and-tobago","title":"Roofing in Trinidad and Tobago","category":"world-roofing","type":"place","country":{"name":"Trinidad and Tobago","iso2":"TT"},"summary":"Trinidad and Tobago roofing: steep-gabled Victorian gingerbread houses with dormers, colonial slate and timber roofs, and modern sheet and concrete roofs.","body":"Trinidad and Tobago, the southernmost Caribbean state, has a colonial built heritage that includes steep-roofed Victorian houses, Gothic Revival churches and the early 20th-century mansions known as the Magnificent Seven in Port of Spain.\n\n## Climate and hazards\n\nThe islands have a hot, humid tropical climate with a pronounced wet season.\n\n## Roofing history\n\nBefore European colonisation the islands were inhabited by Indigenous peoples. In Port of Spain, the Cathedral of the Holy Trinity, completed in 1818 in the Gothic Revival style, has a hammerbeam roof of local timber. President's House is roofed in Welsh slate. Several of the Magnificent Seven mansions date from 1904, with Whitehall from 1907 and Hayes Court from 1910. Victorian-era houses have steep gables topped with finials, and the gingerbread houses popularised by George Brown have peaked roofs, dormers and galleries. In the city centre, verandahs on Frederick Street project over the pavement to shelter pedestrians.\n\n## Traditional and vernacular roofs\n\n- **Gingerbread house**: steep peaked roofs with dormers and fretwork, associated with George Brown.\n- **Victorian gabled house**: steep pitched gables with finials.\n\n## Notable roofs\n\n- **Cathedral of the Holy Trinity**, Port of Spain (1818): hammerbeam roof of local wood.\n- **President's House**, Port of Spain: Welsh slate roof.\n- **The Magnificent Seven**, Queen's Park Savannah: early 20th-century mansions.\n\n## Sources and gaps\n\nPresent-day roofing: published information is limited. Published sources on hurricane and seismic roof design for the country: published information is limited. National data on roof materials were not found in published sources.\n\nIndigenous roofing, present-day materials, codes and hazard design: published information is limited.","key_facts":[{"label":"Heritage roofs","value":"Steep gables, dormers, Welsh slate, hammerbeam timber"},{"label":"Landmark","value":"Cathedral of the Holy Trinity (1818)"}],"regions":["Latin America","North America"],"aliases":["Trinidadian roofing","Roofing in Trinidad"],"related":["roofing-in-the-caribbean","natural-slate","corrugated-iron","roofing-in-barbados","roofing-in-grenada","haitian-gingerbread-house"],"company":null,"sources":[{"title":"Trinidad's architecture & built heritage","url":"https://www.discovertnt.com/articles/trinidad/architecture-built-heritage/","publisher":"Discover Trinidad & Tobago"},{"title":"Hip roof","url":"https://en.wikipedia.org/wiki/Hip_roof","publisher":"Wikipedia"}]},{"slug":"roofing-in-tunisia","title":"Roofing in Tunisia","category":"world-roofing","type":"place","country":{"name":"Tunisia","iso2":"TN"},"summary":"Tunisia's roofs include early Islamic domes at Kairouan, fortified flat terraces on Djerba, and Matmata's pit houses, which have no roof at all.","body":"Tunisia's roofing traditions range from the domes and painted timber ceilings of the Great Mosque of Kairouan, among the oldest in the western Islamic world, to the fortified houses and mosques of Djerba and the underground pit dwellings of Matmata, where the earth itself is the roof.\n\n## Climate and hazards\n\nThe north has a Mediterranean climate with winter rain; the south is arid and borders the Sahara. Sudden heavy rain is the main hazard for earth and underground buildings. In 1969, rains lasting 22 days flooded the troglodyte houses of Matmata and caused many to collapse.\n\n## Roofing history\n\n**Kairouan.** The Great Mosque of Kairouan (Mosque of Uqba) was founded in 670 and rebuilt in its present form in 836 under the Aghlabid emir Ziyadat Allah I. Its dome over the mihrab, built around 836 on an octagonal drum, is regarded as one of the oldest and most remarkable domes in the western Islamic world. A second dome rises at the start of the central nave, and a ribbed dome stands over the middle of the south portico. The prayer hall has painted ceilings of planks, beams and brackets; the oldest boards date from the Aghlabid period (9th century), with later replacements from the Zirid, Hafsid and Muradid periods.\n\n**Djerba.** The island's settlement pattern developed from around the 9th century. Its family estates (*menzel*) contain a massive dwelling (*houch*) with no outward openings and angular corner towers. Mosques are short and squat, built for defence, with arrow slits and crenellated roof terraces; coastal mosques doubled as lookouts.\n\n**Matmata.** In the southern hills, Amazigh (Berber) families dug large pits into the ground and carved rooms into the pit walls, sometimes linking several pits by trench-like passages (see Matmata troglodyte houses). After the 1969 floods a surface village, New Matmata, was built with aid, but most residents rebuilt their underground homes.\n\n## Traditional and vernacular roofs\n\n- **Domes and vaults**: in mosques and other masonry buildings, from Kairouan southward (see Middle Eastern domes).\n- **Flat terraces**: crenellated, defensive roof terraces on Djerba's mosques.\n- **Troglodyte rooms**: rooms cut into the ground at Matmata, roofed by undisturbed earth.\n- **Painted timber ceilings**: plank-and-beam ceilings in major mosques.\n\n## Roofing today\n\nAcross North Africa, reinforced concrete flat roofs are the norm in new building (see Roofing in North Africa).\n\n## Codes, standards and regulation\n\nOn Djerba, UNESCO cites Tunisia's Heritage Code (1994) and Urban Planning Code (1994) among the legal protections for the island's traditional building pattern.\n\n## Notable roofs\n\n- **Great Mosque of Kairouan**: 9th-century mihrab dome and painted timber ceilings.\n- **Djerba**: fortified mosques and *houch* dwellings, a World Heritage site.\n- **Matmata**: pit dwellings; the Hotel Sidi Idriss, a traditional troglodyte building, was used as a filming location for *Star Wars* (filmed 1976, released 1977).\n\n## Local roofing terms\n\n- **menzel**: family estate on Djerba.\n- **houch**: massive closed dwelling within a menzel.\n\n## Sources and gaps\n\nNo national household survey or census table on roof materials for Tunisia was found in published sources. No information on domestic roofing manufacturers was found.\n\nInformation on modern roof materials, the vaulted houses of southern Tunisia, and Tunisia's building regulations: published information is limited.","key_facts":[{"label":"Early dome","value":"Kairouan mihrab dome, c. 836"},{"label":"Traditional forms","value":"Domes, flat terraces, troglodyte pits"},{"label":"Climate driver","value":"Winter rain in the north; aridity and flash floods in the south"},{"label":"Notable flood","value":"1969 rains (22 days) collapsed many Matmata pit houses"}],"regions":["Africa","Middle East"],"aliases":["Tunisian roofing","roofing in Tunisia"],"related":["roofing-in-north-africa","matmata-troglodyte-houses","middle-eastern-domes","dome","flat-roof","roofing-in-algeria","roofing-in-libya"],"company":null,"sources":[{"title":"Mosque of Uqba","url":"https://en.wikipedia.org/wiki/Mosque_of_Uqba","publisher":"Wikipedia"},{"title":"Djerba: Testimony to a settlement pattern in an island territory","url":"https://whc.unesco.org/en/list/1640/","publisher":"UNESCO World Heritage Centre"},{"title":"Matmata, Tunisia","url":"https://en.wikipedia.org/wiki/Matmata,_Tunisia","publisher":"Wikipedia"}]},{"slug":"roofing-in-turkey","title":"Roofing in Turkey","category":"world-roofing","type":"place","country":{"name":"Turkey","iso2":"TR"},"regions":["Europe","Middle East"],"company":null,"summary":"Turkish roofing from Neolithic roof-entry houses at Çatalhöyük to Ottoman lead domes, clay tile, flat earth roofs and modern concrete.","aliases":["Turkish roofing","Roofing in Türkiye","Çatı","Anatolian roofs"],"body":"Turkey bridges Europe and Asia and holds some of the oldest roofing evidence anywhere, from the Neolithic settlements of Anatolia to Byzantine and Ottoman domes. Its roofing climates range from the wet Black Sea coast to the Mediterranean and Aegean shores and the dry, cold-wintered plateau of central and eastern Anatolia, and much of the country is highly seismic.\n\n## Climate and hazards\n\n- **Black Sea coast:** the wettest region, where pitched roofs with wide eaves are traditional.\n- **Aegean and Mediterranean coasts:** hot, dry summers and wet winters; clay tile roofs predominate in older towns.\n- **Central and eastern Anatolia:** low rainfall, hot summers and cold winters, where flat earth roofs were the vernacular norm because timber was scarce.\n- **South-east (Harran plain):** extreme summer heat, answered with thick mud-brick domes.\n- **Earthquakes:** seismic risk is high across much of the country, so the weight of a roof and its connection to the structure matter. Heavy earth roofs and poorly tied roofs are known vulnerabilities.\n\n## Roofing history\n\n**Pre-Pottery Neolithic.** Göbekli Tepe, near Şanlıurfa, has monumental round-oval and rectangular enclosures with T-shaped limestone pillars up to 5.5 m (18 ft) tall, built by hunter-gatherers between about 9600 and 8200 BC. Whether the enclosures were roofed has been debated: a 2023 review in *Open Archaeology* notes that arguments first made in a 2011 critique, including that the buildings were roofed, have gained acceptance. Recent excavations have also found what appear to be domestic buildings.\n\n**Çatalhöyük.** On the Konya plain, the Neolithic town of Çatalhöyük (eastern mound about 7400-6200 BC, per UNESCO) had mud-brick houses packed together without streets. People walked across the flat roofs and entered houses through roof openings by ladder; the roof opening also let out smoke, and communal ovens were later built on the roofs. Up to 18 building levels accumulated as houses were rebuilt on their own rubble. See catalhoyuk-roofs.\n\n**Ancient tiles.** Fired clay roof tiles spread from mainland Greece to western Asia Minor within about fifty years of their first use near Corinth around 700-650 BC, making the Aegean coast of modern Turkey one of the earliest tiled regions in the world.\n\n**Assyrian-era domes.** Assyrian reliefs of the 7th century BC show domed buildings similar to the beehive houses still seen at Harran.\n\n**Byzantine and Ottoman domes.** The Hagia Sophia in Istanbul, completed in 537, set a model for domed roofs. Ottoman imperial mosques are built around a central dome supported by semi-domes; their domes are typically covered in lead sheet, giving them their grey colour, and topped with a finial.\n\n**Modern.** Reinforced concrete frame buildings now dominate, with either flat roofs or timber-framed pitched roofs.\n\n## Traditional and vernacular roofs\n\n- **West and north:** houses on the Aegean, Marmara and Black Sea coasts traditionally have hipped roofs of curved or interlocking clay tiles with wide eaves; the timber-framed Ottoman houses of Safranbolu are a well-known example.\n- **Central and eastern Anatolia:** flat roofs of compacted earth over timber poles, rolled after rain to keep them watertight.\n- **Kırlangıç kubbe (\"swallow dome\"):** a corbelled timber lantern roof, the Turkish relative of the Georgian darbazi and Armenian glkhatun.\n- **Harran kümbet:** conical mud-brick domes with walls 50-60 cm (20-24 in) thick and domes 20-30 cm (8-12 in) thick, vented at the top; 2,760 were counted in 2002. See harran-beehive-houses.\n\n## Roofing today\n\nNew buildings are mostly reinforced concrete, with flat roofs or timber-framed pitched roofs covered in clay tile, metal sheet or bituminous shingle. Turkey is also a significant source of water reed for thatching: much of the reed used on British thatched roofs is imported from Turkey and other countries.\n\n## Codes, standards and regulation\n\nSeismic design is governed by the Turkish Building Earthquake Code of 2018 (*Türkiye Bina Deprem Yönetmeliği*, TBDY 2018), which replaced the 2007 earthquake regulation.\n\n## Industry\n\nThe reed export trade supplies thatchers in north-western Europe.\n\n## Notable roofs\n\n- **Çatalhöyük** (UNESCO): Neolithic roof-entry houses; modern shelter roofs now protect the excavations.\n- **Göbekli Tepe** (UNESCO): debated roofed enclosures of the 10th-9th millennia BC.\n- **Hagia Sophia** (Istanbul, 537): see hagia-sophia-dome.\n- **Ottoman mosques:** lead-covered central domes with semi-domes.\n- **Harran:** beehive-domed houses on the Syrian border.\n- **Safranbolu:** Ottoman timber houses with tile roofs.\n\n## Local roofing terms\n\n- *çatı* - roof\n- *kümbet* - domed beehive house (Harran)\n- *kırlangıç kubbe* / *kırlangıç örtü* - corbelled \"swallow\" lantern roof\n\n## Sources and gaps\n\nNational data on current roofing materials, roofing manufacturers and roof-specific standards: published information is limited.","key_facts":[{"label":"Earliest roof evidence","value":"Neolithic flat roofs, Çatalhöyük (c. 7400 BC)"},{"label":"Monumental roofs","value":"Lead-covered domes"},{"label":"Coastal vernacular","value":"Hipped clay tile roofs"},{"label":"Inland vernacular","value":"Flat earth roofs; mud-brick domes at Harran"},{"label":"Seismic code","value":"Turkish Building Earthquake Code 2018"},{"label":"Thatch reed","value":"Exported to north-western Europe"}],"related":["catalhoyuk-roofs","harran-beehive-houses","darbazi","hagia-sophia-dome","middle-eastern-domes","ottoman-domes-in-the-balkans","flat-roof","mud-roof","clay-roof-tile","lead-roofing","water-reed-thatch","earthquake-roofing","roofing-in-greece","roofing-in-georgia","roofing-in-syria","roofing-in-iran","roofing-in-the-middle-east-and-gulf","dome","english-thatch"],"sources":[{"title":"Architecture of Turkey","url":"https://en.wikipedia.org/wiki/Architecture_of_Turkey","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Dome","url":"https://en.wikipedia.org/wiki/Dome","publisher":"Wikipedia"},{"title":"Neolithic Site of Çatalhöyük","url":"https://whc.unesco.org/en/list/1405","publisher":"UNESCO World Heritage Centre"},{"title":"Göbekli Tepe","url":"https://whc.unesco.org/en/list/1572","publisher":"UNESCO World Heritage Centre"},{"title":"Paradise Found or Common Sense Lost? Göbekli Tepe's Last Decade as a Pre-Farming Cult Centre (2023)","url":"https://doaj.org/article/b04f1cc64a90407dbda94032dd6f11c7","publisher":"Open Archaeology (via DOAJ)"},{"title":"Harran","url":"https://en.wikipedia.org/wiki/Harran","publisher":"Wikipedia"},{"title":"Comparison of the 2007 earthquake regulation with the 2018 earthquake regulation (thesis record)","url":"https://acikbilim.yok.gov.tr/handle/20.500.12812/595874","publisher":"YÖK Açık Bilim (Council of Higher Education, Turkey)"}]},{"slug":"roofing-in-turkmenistan","title":"Roofing in Turkmenistan","category":"world-roofing","type":"place","country":{"name":"Turkmenistan","iso2":"TM"},"summary":"Turkmenistan's roofing heritage centres on the brick domes of Merv and Kunya-Urgench; the 1948 Ashgabat earthquake reshaped modern construction.","body":"Turkmenistan is a largely desert country between the Caspian Sea and the Amu Darya river, bordering Iran and Afghanistan to the south. Its roofing heritage is earthen and brick: the domed mausoleums of the medieval cities of **Merv** and **Kunya-Urgench**, both UNESCO World Heritage Sites, are among the most important early domed buildings of Central Asia. Its modern history was shaped by the 1948 earthquake that levelled the capital, Ashgabat.\n\n## Climate and hazards\n\nMost of the country is occupied by the Karakum desert, with very hot summers, cold winters and little rain. The south, along the Kopet Dag mountains where Ashgabat lies, is highly seismic. The earthquake of 6 October 1948, of surface-wave magnitude 7.3 and maximum intensity X, killed between 10,000 and 110,000 people by different estimates. Almost all brick buildings in Ashgabat and nearby villages collapsed, concrete buildings were heavily damaged and the old adobe city was destroyed.\n\n## Roofing history\n\n**Merv**, in the Murghab river oasis, was one of the great cities of the Silk Road. Its city of Sultan Kala, walled in the 11th century, contains the **Mausoleum of Sultan Sanjar**, the ruler who reigned from 1118 to 1157; it is admired for its brickwork and carved stucco and retains mural paintings. The Merv oasis is also known for its *köshks*, fortified mud-brick manor houses.\n\n**Kunya-Urgench**, in the north, preserves monuments mainly of the 11th to 16th centuries, including a mosque, caravanserai gates, fortresses, mausoleums and a 60 m (197 ft) minaret. Its buildings are of unfired mud brick and fired brick, decorated with terracotta arabesques and brightly coloured glazed work. UNESCO notes that local masters developed the treatment of the inner surface of domes from cellular forms to *muqarnas*, or stalactite vaulting.\n\nAfter 1948 Ashgabat was rebuilt as a Soviet city. Across the USSR, seismic zoning maps were compiled from 1937 and updated in 1957, 1968 and 1978, and the codes SNiP II-A.12-62 and SNiP II-A.12-69 introduced seismic design based on dynamic theory.\n\n## Traditional and vernacular roofs\n\n- **Domed brick tombs and mosques**: single-chamber domed buildings and more complex domed compositions in mud and fired brick.\n- **Köshk**: fortified mud-brick houses of the Merv oasis.\n\n## Codes, standards and regulation\n\nAn assessment by the Global Earthquake Model Foundation found little official information on current building codes, but noted updated seismic zoning and new building codes adopted in 2021.\n\n## Notable roofs\n\n- **Mausoleum of Sultan Sanjar, Merv** (12th century).\n- **Domed mausoleums of Kunya-Urgench** (11th-16th centuries).\n\n## Sources and gaps\n\nDescriptions of traditional house roofs and of the Turkmen yurt, information on modern roofing, housing statistics and domestic roofing manufacturers: published information is limited.","key_facts":[{"label":"Traditional materials","value":"Mud brick and fired brick"},{"label":"Landmark roofs","value":"Domed mausoleums of Merv and Kunya-Urgench"},{"label":"Dome decoration","value":"Muqarnas and stalactite inner domes; glazed and terracotta ornament"},{"label":"Climate driver","value":"Desert heat, cold winters, earthquakes"},{"label":"Key event","value":"1948 Ashgabat earthquake, magnitude 7.3"}],"regions":["Central Asia"],"aliases":["Turkmen roofing","roofs of Turkmenistan"],"related":["dome","middle-eastern-domes","mud-roof","flat-roof","earthquake-roofing","roofing-in-uzbekistan","roofing-in-iran","roofing-in-afghanistan","roofing-in-kazakhstan","tunduk-and-shangyrak"],"company":null,"sources":[{"title":"State Historical and Cultural Park \"Ancient Merv\"","url":"https://whc.unesco.org/en/list/886/","publisher":"UNESCO World Heritage Centre"},{"title":"Kunya-Urgench","url":"https://whc.unesco.org/en/list/1199/","publisher":"UNESCO World Heritage Centre"},{"title":"1948 Ashgabat earthquake","url":"https://en.wikipedia.org/wiki/1948_Ashgabat_earthquake","publisher":"Wikipedia"},{"title":"Design regulations (Central Asia exposure model)","url":"https://docs.openquake.org/global_risk_model/central_asia/exposure/design_regulations.html","publisher":"Global Earthquake Model Foundation"}]},{"slug":"roofing-in-tuvalu","title":"Roofing in Tuvalu","category":"world-roofing","type":"place","country":{"name":"Tuvalu","iso2":"TV"},"summary":"Tuvalu roofing: atoll houses and maneapa meeting halls once thatched, now overwhelmingly corrugated iron with gutters feeding rainwater tanks.","body":"Tuvalu, a group of low atolls and reef islands, shares much of its building tradition with Kiribati, with which it formed the British colony of the Gilbert and Ellice Islands. Its community meeting house is called the *maneapa* or *ahiga*. Today corrugated iron covers almost every home, and the guttering that feeds rainwater tanks is as important as the roof itself.\n\n## Climate and hazards\n\nAs on other Pacific atolls, rain collected from roofs is an important water source, which is why household surveys record whether a roof has gutters.\n\n## Roofing history\n\nThe shared name of the meeting house reflects the common Gilbert and Ellice heritage with Kiribati, where the maneaba is a pandanus-thatched, coconut-timber building. By 2010, thatched roofs had become rare in Tuvalu (see below).\n\n## Traditional and vernacular roofs\n\n- **Maneapa / ahiga**: community meeting house, comparable to the Kiribati [maneaba](/maneaba).\n- **Thatched or traditional dwellings**: now a small minority.\n\n## Roofing today\n\nIn the 2010 Household Income and Expenditure Survey, 89.5% of household records listed corrugated iron with a gutter, 5% corrugated iron without a gutter, and 5.2% a thatched or traditional roof. These are unweighted case counts from the survey sample. The survey's separate categories for iron with and without gutters reflect the importance of roof catchment for drinking water.\n\n## Codes, standards and regulation\n\nBuilding is regulated under the Building Act (CAP 44.08). A national building code dates from 1990 and was updated in 2024.\n\n## Local roofing terms\n\n- **Maneapa / ahiga**: meeting house.\n\n## Sources and gaps\n\nSources specific to Tuvaluan roofing are scarce. No Tuvalu-specific history of roofing was found in published sources. No domestic roofing manufacturers were identified.\n\nNo detailed published study of Tuvaluan roof construction was found; its history is known mainly through the shared Gilbert and Ellice tradition. Census roof tables: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Corrugated iron (94.5% of HIES 2010 records, most with gutters)"},{"label":"Traditional materials","value":"Coconut timber, pandanus or palm thatch"},{"label":"Meeting house","value":"Maneapa or ahiga"},{"label":"Climate drivers","value":"Low atolls, storms, scarce fresh water"},{"label":"Building law","value":"Building Act (CAP 44.08)"}],"regions":["Oceania"],"aliases":["Tuvaluan roofing","Ellice Islands roofing"],"related":["maneaba","roofing-in-kiribati","corrugated-iron","rainwater-harvesting-roofs","palm-thatch","roofing-in-the-pacific-islands"],"company":null,"sources":[{"title":"Tuvalu HIES 2010, roof material (h0201a1)","url":"https://microdata.pacificdata.org/index.php/catalog/737/variable/V482","publisher":"Pacific Data Hub (SPC)"},{"title":"Maneaba","url":"https://en.wikipedia.org/wiki/Maneaba","publisher":"Wikipedia"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-uganda","title":"Roofing in Uganda","category":"world-roofing","type":"place","country":{"name":"Uganda","iso2":"UG"},"summary":"Uganda's roofs are mostly iron sheets (72% of households in 2014) but thatch still covered a quarter of homes; the Kasubi royal tombs are a great thatched dome.","body":"Uganda is a landlocked, largely high-plateau country around Lake Victoria and the upper Nile. Its building tradition is one of the richest in plant materials in Africa: the domed thatched houses of the Buganda kingdom, represented above all by the royal tombs at Kasubi in Kampala, were built entirely of poles, reeds and grass. Over the past few decades, corrugated iron has become the normal roof, but thatch still covered about a quarter of households at the 2014 census, much more than in neighbouring Kenya or Tanzania.\n\n## Climate and hazards\n\nMost of the country is tropical but moderated by altitude. Roofs must shed intense rain and survive thunderstorms and wind. Thatch in this humid climate needs constant upkeep and is vulnerable to fire, a risk demonstrated by the loss of the main Kasubi tomb building in 2010.\n\n## Roofing history\n\nThe best-documented historic roofs are those of the Kabakas (kings) of Buganda. The palace at Kasubi was built in 1882 by Muteesa I, the 35th Kabaka, replacing an 1820 palace of Ssuuna II; when Muteesa died in 1884 it became a royal burial ground. Its main building, the Muzibu Azaala Mpanga, was a circular, domed structure of wooden poles, reed wattle and daub under a thick grass thatch resting on rings of palm fronds. A renovation in 1938 introduced steel, concrete columns and brick, mostly hidden behind the traditional materials.\n\nTraditional Ganda craft organisation was clan-based. At Kasubi, thatching remained the work of the Ngeye clan, and bark cloth for the interior was made by the Ngo clan, specialisms that continued into the 21st-century rebuilding.\n\nCorrugated iron spread through the colonial period and after independence. Census data show the rise of permanent roofing materials (tiles, iron sheets, asbestos and concrete): about 40% of households in 1991, 56% in 2002 and 74% in 2014. In rural areas the share roughly doubled from 33% to 66%.\n\n## Traditional and vernacular roofs\n\n- **Ganda domed house**: a round building of poles and reeds with a grass covering on rings of palm fronds. The Muzibu Azaala Mpanga is a prominent example. See Muzibu Azaala Mpanga.\n- **Grass thatch on round and rectangular houses** across the country, still used by about a third of rural households in 2014.\n- **Interior finishes**: Ganda royal buildings used bark cloth hangings and floors covered in lemongrass and palm-leaf mats.\n\n## Roofing today\n\nThe National Population and Housing Census 2014 (UBOS housing monograph, Table 2.1) gives the roofing material of households:\n\n| Roofing material | Uganda | Urban | Rural |\n|---|---|---|---|\n| Iron sheets | 72.3% | 88.9% | 65.8% |\n| Thatch | 26.3% | 7.6% | 33.5% |\n| Tiles | 0.6% | 1.6% | 0.2% |\n| Asbestos | 0.5% | 1.1% | 0.3% |\n| Concrete | 0.3% | 0.7% | 0.1% |\n| Tin | 0.1% | 0.2% | 0.1% |\n\nClay tiles, concrete slabs and asbestos-cement sheets together served under 2% of households, and each was more common in towns than in the countryside.\n\n## Codes, standards and regulation\n\nBuilding is regulated under the **Building Control Act, 2013** (Act 10 of 2013), which set up the National Building Review Board, and under the Building Control Regulations 2020 used by authorities such as Kampala Capital City Authority. Press commentary in 2026 focused on weak enforcement of the Act, and a Building Control (Amendment) Bill was before Parliament in 2025.\n\n## Industry\n\nRegional steel-roofing groups such as Safal Group, parent of Kenya's Mabati Rolling Mills, list Uganda among their operating countries. Thatching skills persist within clans; at Kasubi, thatching is a hereditary role of the Ngeye clan.\n\n## Notable roofs\n\n- **Tombs of Buganda Kings at Kasubi** (UNESCO World Heritage, inscribed December 2001): the Muzibu Azaala Mpanga, about 7.5 m (25 ft) high and about 31 m (102 ft) round, destroyed by fire on 16 March 2010, rebuilt from 2014 and completed in 2023. See Muzibu Azaala Mpanga.\n\n## Local roofing terms\n\n- *Muzibu Azaala Mpanga* (Luganda): name of the main Kasubi tomb building.\n- *Kabaka* (Luganda): king of Buganda.\n\n## Sources and gaps\n\nThe 1991 and 2002 trend uses UBOS's figure for permanent roofing materials taken from the 2014 housing monograph; individual-material shares for those years are not well documented in published sources. Roofing clauses of Ugandan building regulations, and domestic sheet manufacturers, are not documented in published sources.","key_facts":[{"label":"Dominant material today","value":"Iron sheets, 72.3% of households (2014 census)"},{"label":"Thatch","value":"26.3% of households; 33.5% in rural areas (2014)"},{"label":"Traditional materials","value":"Grass thatch, reeds, poles, palm-frond rings"},{"label":"Landmark roof","value":"Muzibu Azaala Mpanga, Kasubi (UNESCO, 2001)"},{"label":"Building law","value":"Building Control Act, 2013"}],"regions":["Africa"],"aliases":["Ugandan roofing","roofs in Uganda"],"related":["roofing-in-east-africa","muzibu-azaala-mpanga","thatch","corrugated-iron","mabati-rolling-mills","roofing-in-kenya","roofing-in-tanzania","roofing-in-rwanda","roofing-in-the-democratic-republic-of-the-congo"],"sources":[{"title":"2019 Housing Monograph (NPHC 2014)","url":"https://www.ubos.org/wp-content/uploads/publications/09_2019Housing_Monograph_-_FINAL.pdf","publisher":"Uganda Bureau of Statistics"},{"title":"Kasubi Tombs","url":"https://en.wikipedia.org/wiki/Kasubi_Tombs","publisher":"Wikipedia"},{"title":"Tombs of Buganda Kings at Kasubi","url":"https://whc.unesco.org/en/list/1022","publisher":"UNESCO World Heritage Centre"},{"title":"Building Control Act, 2013","url":"https://ulii.org/en/akn/ug/act/2013/10/eng@2013-10-11","publisher":"ULII"},{"title":"The Buildings Control Regulations 2020","url":"https://www.kcca.go.ug/media/docs/The Buildings Control Regulations 2020 3.pdf","publisher":"Kampala Capital City Authority"},{"title":"Certificate of Financial Implications for Building Control (Amendment) Bill, 2025","url":"https://bills.parliament.ug/attachments/CFI for Building Control (Amendment Bill),2025.pdf","publisher":"Parliament of Uganda"},{"title":"Safal Group","url":"https://www.safalgroup.com/","publisher":"Safal Group"},{"title":"Uganda's Building Control Act: strong laws hampered by enforcement failures","url":"https://www.ugandaonline.net/news/2026-04-23--uganda-s-building-control-act-strong-laws-hampered-by-enforcement-failures--caccf6184c73/","publisher":"Daily Monitor (via Uganda Online)"}],"company":null},{"slug":"roofing-in-ukraine","title":"Roofing in Ukraine","category":"world-roofing","type":"place","country":{"name":"Ukraine","iso2":"UA"},"summary":"Ukrainian roofing: four-sloped straw and reed thatch on whitewashed khatas, shingle-clad wooden tserkvas in the Carpathians, Soviet shifer and post-war repair.","body":"Ukraine's traditional roofs reflect its landscapes: thatch of straw or reed over the whitewashed cottages (*khata*) of the steppe and forest-steppe, boards and wooden shingles in the forests and Carpathian mountains, and tiered, shingle-clad domes on the wooden churches of the west. In the 20th century, Soviet industry made corrugated asbestos-cement sheet (*shifer*) the common rural roof, and since 2022 the repair of war-damaged roofs has become one of the country's most urgent building tasks.\n\n## Climate and hazards\n\nUkraine has a temperate continental climate with cold, snowy winters and hot summers, milder on the Black Sea coast and snowier in the Carpathians. Since the full-scale Russian invasion of 2022, many buildings have been damaged by bombing, and asbestos in damaged shifer roofs is a health hazard when debris is cleared.\n\n## Roofing history\n\nThatch was the traditional covering of most Ukrainian houses. Roofs usually had four sloping sides carried on rafters, and the materials varied by region: bundles of straw or reed in the steppe and forest-steppe, roof poles and bunches of straw in Right-Bank Ukraine, sheaves on the Left Bank, and thin boards or shingles in forested and mountain areas. In Volhynia, roofs were thatched with rye straw; in Transcarpathia with straw or wooden shingles; and in Podolia and Poltava with straw, including broad straw roofs on farm buildings. Many houses in Chernihiv Polissia still had no chimneys in the early 20th century, letting smoke escape through holes in the roof. Tiles came into use later, and two-sloped roofs, which give a taller attic with a window, have become popular more recently.\n\nIn the Carpathians, Hutsul and Boyko homesteads had galleries with tall straw-covered roofs around the house front, and in the Hutsul *grazhda* the house and farm buildings share one roof, enclosed by a high fence with its own narrow roof. Orthodox and Greek Catholic communities built wooden churches (tserkvas) of horizontal logs from the 16th to the 19th centuries, with domes and roofs clad in wooden shingles. See wooden tserkva roofs.\n\nDuring the Soviet period, collectivisation in the 1930s and post-war rebuilding transformed villages, and corrugated asbestos-cement sheet became a common roof on rural houses and farm buildings.\n\n## Traditional and vernacular roofs\n\n- **Thatched khata:** four-sloped roof of straw or reed over whitewashed walls.\n- **Shingle and board roofs:** in Polissia's forests and the Carpathians.\n- **Tserkva roofs:** tiered, shingle-clad domes and pyramids of the Hutsul, Boyko, Lemko and Halych traditions.\n\n## Roofing today\n\nSlate containing chrysotile asbestos is still used for house roofs, fences and farm buildings. A draft law to prohibit asbestos products (No. 4142) passed its first reading.\n\n## Notable roofs\n\n- **Wooden Tserkvas of the Carpathian Region** (UNESCO, 2013), eight of them in Ukraine: Drohobych, Matkiv, Nyzhnii Verbizh, Potelych, Rohatyn, Uzhok, Yasinia and Zhovkva.\n\n## Local roofing terms\n\n- *khata* - traditional cottage\n- *grazhda* - enclosed Hutsul homestead with a roofed fence\n- *tserkva* - wooden church\n- *shifer* - corrugated asbestos-cement sheet\n\n## Sources and gaps\n\nNational statistics on roof materials and information on domestic roofing manufacturers: published information is limited. War damage to roofs and on current building norms: published information is limited.","key_facts":[{"label":"Traditional covering","value":"Straw or reed thatch; shingles in mountains"},{"label":"Traditional form","value":"Four-sloped roof"},{"label":"Soviet-era covering","value":"Asbestos-cement sheet (shifer)"},{"label":"UNESCO roofs","value":"Wooden Tserkvas of the Carpathian Region (2013)"}],"regions":["Europe"],"aliases":["Ukrainian roofing","roofs in Ukraine"],"related":["wooden-tserkva-roofs","shifer","thatch","wood-shingle","roofing-in-poland","roofing-in-russia","roofing-in-belarus","roofing-in-moldova","roofing-in-romania","asbestos-cement-roofing"],"company":null,"sources":[{"title":"Ukrainian khata","url":"https://en.wikipedia.org/wiki/Ukrainian_khata","publisher":"Wikipedia"},{"title":"Folk architecture","url":"https://www.encyclopediaofukraine.com/pages%5CF%5CO%5CFolkarchitecture.htm","publisher":"Internet Encyclopedia of Ukraine"},{"title":"Wooden Tserkvas of the Carpathian Region in Poland and Ukraine","url":"https://whc.unesco.org/en/list/1424","publisher":"UNESCO World Heritage Centre"},{"title":"Wooden Tserkvas of the Carpathian Region in Poland and Ukraine","url":"https://en.wikipedia.org/wiki/Wooden_Tserkvas_of_the_Carpathian_Region_in_Poland_and_Ukraine","publisher":"Wikipedia"},{"title":"Ukrainians were explained the main health threat from bombed buildings","url":"https://ecopolitic.com.ua/?p=25391","publisher":"EcoPolitic"}]},{"slug":"roofing-in-uruguay","title":"Roofing in Uruguay","category":"world-roofing","type":"place","country":{"name":"Uruguay","iso2":"UY"},"summary":"Uruguayan roofing: Portuguese-Spanish colonial tile in Colonia del Sacramento, and modern concrete, metal sheet and tile in a temperate, low-seismicity land.","body":"Uruguay has a temperate, humid climate and very little earthquake risk. Its best-known historic roofs are the tiled colonial houses of Colonia del Sacramento, where Portuguese and Spanish traditions meet.\n\n## Climate and hazards\n\n- **Rain and wind** typical of a temperate coastal climate.\n- **Low seismicity**: a 2012 review of Latin American building codes excluded Uruguay as a low-seismicity country.\n\n## Roofing history\n\n**Colonial.** Colonia del Sacramento was founded by the Portuguese in 1680 on the north shore of the Río de la Plata, opposite Buenos Aires, and UNESCO describes buildings that fuse the two traditions: mostly modest single-storey houses, with civil and religious buildings that combine long stone walls, timber roof structures and tiled roofs. The historic quarter was inscribed by UNESCO in 1995. In the Río de la Plata region, Spanish tiles generally have a parabolic profile and Portuguese tiles a semicircular one.\n\n**19th century.** Immigrant artisans arriving in the second half of the 19th century added their own building styles to Colonia and other towns.\n\n**Industrial era.** The Fray Bentos Cultural-Industrial Landscape, a former meat-processing complex, was inscribed by UNESCO in 2015.\n\n## Traditional and vernacular roofs\n\n- **Teja** roofs on single-storey colonial houses with stone walls.\n\n## Roofing today\n\nConcrete slabs, metal sheet and clay or concrete tile are all in use.\n\n## Notable roofs\n\n- **Historic Quarter of Colonia del Sacramento** (UNESCO 1995): stone houses with tiled roofs.\n- **Fray Bentos Cultural-Industrial Landscape** (UNESCO 2015).\n\n## Local roofing terms\n\n- *Teja*: clay tile.\n- *Chapa*: metal roofing sheet (Río de la Plata usage).","key_facts":[{"label":"Colonial roofs","value":"Clay tile on stone walls (Colonia del Sacramento)"},{"label":"Founded","value":"Colonia, by the Portuguese, 1680"},{"label":"Seismicity","value":"Low"},{"label":"Heritage","value":"Colonia del Sacramento, UNESCO 1995"}],"regions":["Latin America"],"aliases":["Uruguayan roofing"],"related":["clay-roof-tile","spanish-tile","corrugated-iron","roofing-in-argentina","roofing-in-brazil","roofing-in-portugal","roofing-in-spain"],"company":null,"sources":[{"title":"Historic Quarter of the City of Colonia del Sacramento","url":"https://whc.unesco.org/en/list/747","publisher":"UNESCO World Heritage Centre"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"},{"title":"Arqueología en las Misiones Jesuitas de Guaraníes: las tejas decoradas de la iglesia de Santa Ana","url":"https://cau.iaa.fadu.uba.ar/wp-content/uploads/2019/03/Roca_Tejas-decoradas_SantaAna.pdf","publisher":"Instituto de Arte Americano, FADU-UBA"}]},{"slug":"roofing-in-uzbekistan","title":"Roofing in Uzbekistan","category":"world-roofing","type":"place","country":{"name":"Uzbekistan","iso2":"UZ"},"summary":"Uzbekistan's Silk Road cities are known for brick domes and tiled cupolas; houses were mud-brick with painted timber ceilings; Tashkent was rebuilt after 1966.","body":"Uzbekistan lies at the heart of the old Silk Road, and its historic cities, Samarkand, Bukhara and Khiva, are famous for their brick domes, tiled cupolas and covered markets. Ordinary houses were built of mud brick around courtyards, with richly painted timber ceilings. After the 1966 earthquake, central Tashkent was rebuilt with large Soviet-era apartment complexes.\n\n## Climate and hazards\n\nThe climate is continental and dry, with hot summers and cold winters, and most of the population lives in irrigated oases and river valleys. Earthquakes are a serious hazard: the shallow earthquake of 26 April 1966, of magnitude about 5.2 with its epicentre in central Tashkent, destroyed between 78,000 and 95,000 homes, most of them traditional adobe houses in the dense central districts, and left an estimated 200,000-300,000 people homeless. Earthen buildings are also vulnerable to gradual deterioration, and termites damage timber structures.\n\n## Roofing history\n\nThe site of Afrasiab, the predecessor of Samarkand, was founded in the 7th century BCE. Building in mud brick and fired brick reached a high point under the Samanids and later the Timurids. In Bukhara, the **Ismail Samani mausoleum** of the 10th century is regarded by UNESCO as the best-surviving example of 10th-century architecture in the Muslim world, and the brick Kalyan (Poi-Kalyan) minaret dates from 1127. Samarkand's greatest development came in the 14th-15th centuries, when it was capital of Timur's realm; its Registan mosques and madrasahs were built in mud brick and covered with decorated ceramic tiles, and the period produced the Bibi-Khanum mosque and the Gur-Emir ensemble.\n\nBukhara's covered markets were built as domes over street crossings, such as *Taki Sarafon* (\"dome of the money-changers\") and *Taki Tilpak Furushon* (\"dome of the cap sellers\"). In Khiva's walled inner town, **Itchan Kala**, the Djuma (Friday) Mosque is a covered hall of about 55 by 46 m (180 by 150 ft), carried on 212 columns and lit by two octagonal lanterns in the roof.\n\nIn the Soviet period, after the 1966 earthquake, Tashkent was rebuilt with wide boulevards and large apartment complexes; about 100,000 new homes had been completed by 1970.\n\n## Traditional and vernacular roofs\n\n- **Courtyard houses**: one- or two-storey mud-brick houses around a central courtyard with a garden, with painted wooden ceilings and wall decoration.\n- **Aivan**: a covered portico or veranda on carved wooden posts, used for reception rooms in Khiva and elsewhere.\n- **Domes and vaults**: brick domes over mausoleums, mosques, madrasahs and market crossings, often clad in glazed tiles.\n- **Karakalpak yurt**: the felt yurt of the Karakalpak people of north-western Uzbekistan, included by UNESCO in 2025 in the listing of Turkic yurt-making skills.\n\n## Codes, standards and regulation\n\nUzbekistan's seismic code **KMK 2.01.02-96**, *Norms and regulations for construction in seismic zones*, was approved in 1996 and updated the seismic zoning maps and earthquake recurrence data inherited from the Soviet SNiP system.\n\n## Notable roofs\n\n- **Ismail Samani mausoleum, Bukhara** (10th century).\n- **Trading domes of Bukhara**, such as Taki Sarafon.\n- **Registan, Bibi-Khanum and Gur-Emir, Samarkand** (Timurid period).\n- **Djuma Mosque, Khiva**: covered hall on 212 columns with two roof lanterns.\n\nAll are parts of UNESCO World Heritage Sites (Historic Centre of Bukhara; Samarkand - Crossroad of Cultures; Itchan Kala).\n\n## Local roofing terms\n\n- *taki* (Tajik/Uzbek): dome over a market crossing\n- *aivan*: covered portico or veranda\n\n## Sources and gaps\n\nDescriptions of the construction of traditional flat roofs, statistics on modern roofing materials and information on the roofing industry: published information is limited.","key_facts":[{"label":"Traditional materials","value":"Mud brick, fired brick, timber, glazed tile"},{"label":"Landmark roofs","value":"Domes of Samarkand, Bukhara and Khiva"},{"label":"Oldest dated roof","value":"Ismail Samani mausoleum, Bukhara (10th century)"},{"label":"Climate driver","value":"Hot, dry summers, cold winters, earthquakes"},{"label":"Seismic code","value":"KMK 2.01.02-96, Norms for construction in seismic zones"},{"label":"Key event","value":"1966 Tashkent earthquake, 78,000-95,000 homes destroyed"}],"regions":["Central Asia"],"aliases":["Uzbek roofing","roofs of Uzbekistan"],"related":["dome","middle-eastern-domes","onion-dome","glazed-roof-tile","flat-roof","mud-roof","earthquake-roofing","tunduk-and-shangyrak","roofing-in-kazakhstan","roofing-in-turkmenistan","roofing-in-tajikistan","roofing-in-afghanistan","roofing-in-iran"],"company":null,"sources":[{"title":"Samarkand - Crossroad of Cultures","url":"https://whc.unesco.org/en/list/603/","publisher":"UNESCO World Heritage Centre"},{"title":"Historic Centre of Bukhara","url":"https://whc.unesco.org/en/list/602/","publisher":"UNESCO World Heritage Centre"},{"title":"Itchan Kala","url":"https://whc.unesco.org/en/list/543/","publisher":"UNESCO World Heritage Centre"},{"title":"1966 Tashkent earthquake","url":"https://en.wikipedia.org/wiki/1966_Tashkent_earthquake","publisher":"Wikipedia"},{"title":"Design regulations (Central Asia exposure model)","url":"https://docs.openquake.org/global_risk_model/central_asia/exposure/design_regulations.html","publisher":"Global Earthquake Model Foundation"},{"title":"Traditional knowledge and skills in making Kyrgyz and Kazakh yurts (Turkic nomadic dwellings)","url":"https://ich.unesco.org/en/RL/traditional-knowledge-and-skills-in-making-kyrgyz-and-kazakh-yurts-turkic-nomadic-dwellings-00998","publisher":"UNESCO Intangible Cultural Heritage"},{"title":"Kalyan Minaret","url":"https://en.wikipedia.org/wiki/Kalyan_Minaret","publisher":"Wikipedia"}]},{"slug":"roofing-in-vanuatu","title":"Roofing in Vanuatu","category":"world-roofing","type":"place","country":{"name":"Vanuatu","iso2":"VU"},"summary":"Vanuatu roofing: natangura sago-palm thatch and nakamal meeting houses alongside corrugated iron, both battered by Cyclone Pam in 2015.","body":"Vanuatu's roofs are split between imported corrugated iron and *natangura*, thatch made from the leaves of the sago palm. The *nakamal*, the meeting place of chiefs, is the country's key traditional building and is often described locally as a hurricane shelter. Tropical Cyclone Pam in March 2015 destroyed roofs across much of the country and prompted efforts to record and revive traditional building knowledge.\n\n## Climate and hazards\n\nVanuatu has a humid tropical climate and lies squarely in the South Pacific cyclone belt; it is also volcanically and seismically active. Category 5 Tropical Cyclone Pam struck on 13 March 2015 with sustained winds of up to 240 km/h (150 mph). In a REACH shelter assessment carried out in April and May 2015, the share of households reporting their roof completely destroyed ranged from 33% (Nguna/Pele) to 79% (Paama), and the share reporting any shelter damage ranged from 59% to 95%. Pam and a following El Niño drought also destroyed thatching materials and new plantings, causing shortages of local materials for rebuilding.\n\n## Roofing history\n\nThe sago palms of the genus *Metroxylon*, including *Metroxylon warburgii* and *M. salomonense*, have long been used throughout Vanuatu and the Solomon Islands for building: their leaves make a durable thatch and their leaf stalks serve as supports and beams. Corrugated iron spread later, and by 2010 iron and natangura roofs were roughly equal in number.\n\n## Traditional and vernacular roofs\n\n- **[Nakamal](/nakamal)**: traditional meeting house used by chiefs for governance, decision-making and teaching, and anecdotally designed to withstand cyclones.\n- **Natangura roofs**: sago-palm leaf thatch, the most common traditional covering (see [sago palm thatch](/sago-palm-thatch)).\n- **Coconut-leaf and wild-cane roofs** are also used.\n\nAfter Pam, UNESCO's Intangible Cultural Heritage Fund financed a 2015 project (US$23,908) to document six damaged nakamals before and after the cyclone, assess their structural condition, and assess the risk of losing the building skills held in each community.\n\n## Roofing today\n\nIn the 2010 Household Income and Expenditure Survey, 49.2% of household records listed an iron roof on the main house, 41.7% natangura, 4.5% coconut leaf, 3.4% wild cane and the rest other materials. These are unweighted case counts from the survey sample. Before Pam, the REACH assessment likewise found corrugated iron and natangura to be the most common roofs.\n\n## Codes, standards and regulation\n\nA national building code was first published in 1990; the Public Works Department issues the Vanuatu Building Code (2000 edition), and the National Building Code Act No. 36 of 2013 gives it legal force. A review of Pacific codes lists the latest update as 2025.\n\n## Notable roofs\n\nThe nakamals documented in the 2015 UNESCO project are notable recorded examples of traditional roofs.\n\n## Local roofing terms\n\n- **Natangura** (Bislama, also spelled natangora): sago-palm leaf thatch.\n- **Nakamal**: chiefs' meeting house; *kastom*, customary practice the nakamal houses.\n\n## Sources and gaps\n\nNo information on domestic roofing manufacturers was found in published sources.\n\nRoof-material results from the 2020 census: published information is limited.","key_facts":[{"label":"Dominant materials today","value":"Iron (49.2%) and natangura thatch (41.7%) in HIES 2010 records"},{"label":"Traditional materials","value":"Sago-palm (natangura), coconut leaf, wild cane"},{"label":"Key traditional building","value":"Nakamal (chiefs’ meeting house)"},{"label":"Climate driver","value":"Cyclones (TC Pam, 13 March 2015, up to 240 km/h)"},{"label":"Building code","value":"Vanuatu Building Code; National Building Code Act No. 36 of 2013"}],"regions":["Oceania"],"aliases":["Vanuatu roofing"],"related":["nakamal","sago-palm-thatch","palm-thatch","thatch","corrugated-iron","wind-uplift","roofing-in-the-solomon-islands","roofing-in-fiji","roofing-in-the-pacific-islands"],"company":null,"sources":[{"title":"Vanuatu HIES 2010, roof material (H4)","url":"https://catalog.ihsn.org/catalog/8492/variable/F2/V14?name=H4","publisher":"IHSN Survey Catalog"},{"title":"Shelter and settlements assessment key findings, May 2015","url":"https://repository.impact-initiatives.org/document/impact/738bacfa/reach_vut_factsheets_shelter_and_settlements_assessment_key_findings_may_2015_v2.pdf","publisher":"REACH / IMPACT Initiatives"},{"title":"Safeguarding indigenous vernacular architecture and building knowledge in Vanuatu","url":"https://ich.unesco.org/en/assistances/safeguarding-indigenous-vernacular-architecture-and-building-knowledge-in-vanuatu-01214","publisher":"UNESCO Intangible Cultural Heritage"},{"title":"Nakamals, an indigenous architecture form","url":"https://www.preventionweb.net/go/52980","publisher":"PreventionWeb"},{"title":"Sago palms, Metroxylon (Arecaceae) in Vanuatu and the Solomon Islands (Dowe, 2002)","url":"https://researchonline.jcu.edu.au/14376/","publisher":"James Cook University"},{"title":"Vanuatu Building Code 2000","url":"https://pwd.gov.vu/images/PWD_Documents/Technical_Documentation/Vanuatu_Building_Code_-_2000.pdf","publisher":"Public Works Department, Vanuatu"},{"title":"Status of building codes in the Pacific","url":"https://www.pln.com.au/single-post/status-of-building-codes-in-the-pacific","publisher":"Pacific Legal Network"}]},{"slug":"roofing-in-vatican-city","title":"Roofing in Vatican City","category":"world-roofing","type":"place","country":{"name":"Vatican City","iso2":"VA"},"regions":["Europe"],"company":null,"summary":"Roofing in Vatican City, the 44-hectare papal state whose skyline is dominated by the double-shelled masonry dome of St Peter's Basilica.","aliases":["Roofing in the Vatican","Holy See roofing"],"body":"Vatican City is the world's smallest independent state, covering about 44 hectares (109 acres) in the centre of Rome. The whole state is a UNESCO World Heritage site, and its roofing story is dominated by one structure: the dome of St Peter's Basilica, one of the largest masonry domes ever built.\n\n## Climate and hazards\n\nThe Vatican shares Rome's Mediterranean climate, with hot, dry summers and mild, wet winters. Its main roof-related hazards are ageing masonry and timber in historic buildings and the cracking of the great dome, which has needed iron reinforcement since the 18th century.\n\n## Roofing history\n\nAn earlier basilica founded by Constantine in the 4th century stood over the tomb of St Peter; its remains lie beneath the present church. The new basilica was begun on 18 April 1506, and the *Fabbrica di San Pietro*, the body that still maintains it, was founded the same year. The church was consecrated by Pope Urban VIII on 18 November 1626. Its builders included Bramante, Raphael, Michelangelo, Della Porta, Maderno and Bernini.\n\nThe Apostolic (Vatican) Palace grew from a structure built by Nicholas III in 1277-1280 and was enlarged from the 15th to the 17th centuries. Its chapels are famous for their ceilings rather than their roofs: Michelangelo painted the Sistine Chapel ceiling frescoes and the Last Judgement.\n\n## The dome of St Peter's\n\n- **Design:** Donato Bramante drew the first design in 1506; Michelangelo redesigned the dome from 1547.\n- **Completion:** Giacomo della Porta and Domenico Fontana completed the dome in 1590, the last year of the reign of Pope Sixtus V. Fontana finished the lantern under Pope Gregory XIV.\n- **Structure:** two shells of brick, the outer one strengthened by 16 stone ribs.\n- **Size:** about 136.57 m (448.1 ft) from the floor to the top of the external cross, with an internal diameter of about 41.47 m (136.1 ft), slightly smaller than the Pantheon and Florence Cathedral.\n- **Reinforcement:** after cracks appeared, four iron chains were installed between the two shells in the mid-18th century; as many as ten chains have been fitted at various times.\n\n## Traditional and vernacular roofs\n\nAs a city-state within Rome, the Vatican has no separate vernacular tradition; its older buildings follow Roman practice of timber roofs with clay tile coverings and masonry vaults.\n\n## Roofing today\n\nRoof work in the Vatican is primarily conservation of historic fabric, carried out under the Fabbrica di San Pietro for the basilica.\n\n## Codes, standards and regulation\n\nNo source on Vatican building regulation was located.\n\n## Industry\n\nThere is no roofing industry in Vatican City.\n\n## Notable roofs\n\n- Dome of St Peter's Basilica (1590)\n- Roofs and vaults of the Apostolic Palace and Sistine Chapel\n\n## Sources and gaps\n\nSeismic and climate data for Vatican roofs, data on materials and contractors, details of the external covering of St Peter's dome and of modern conservation methods were not found in published sources.","key_facts":[{"label":"Area","value":"About 44 ha (109 acres)"},{"label":"Landmark roof","value":"St Peter's dome, completed 1590"},{"label":"Dome height","value":"136.57 m (448.1 ft) to the cross"},{"label":"Internal diameter","value":"41.47 m (136.1 ft)"}],"related":["st-peters-basilica-dome","pantheon-dome","florence-cathedral-dome","dome","roofing-in-italy","roofing-in-san-marino"],"sources":[{"title":"Vatican City","url":"https://whc.unesco.org/en/list/286","publisher":"UNESCO World Heritage Centre"},{"title":"St. Peter's Basilica","url":"https://en.wikipedia.org/wiki/St._Peter%27s_Basilica","publisher":"Wikipedia"}]},{"slug":"roofing-in-venezuela","title":"Roofing in Venezuela","category":"world-roofing","type":"place","country":{"name":"Venezuela","iso2":"VE"},"summary":"Venezuelan roofing: Yanomami palm-thatched shabonos, earthen colonial Coro with Dutch Caribbean influence, and modern concrete and metal sheet.","body":"Venezuela stretches from the Caribbean coast and the Andes across the Llanos grasslands to the Guiana Highlands and the Amazon. Its roofing traditions range from the ring-shaped palm-thatched houses of the Yanomami to the earthen colonial town of Coro and the modernist concrete of Caracas.\n\n## Climate and hazards\n\n- **Earthquakes**, addressed by the national seismic code.\n- **Heavy rain** in the south and in the rainy season; unusual rains in 2004 and 2005 badly damaged the earthen buildings of Coro.\n- **Heat and humidity** in the lowlands.\n\n## Roofing history\n\n**Indigenous.** The Yanomami of the far south build *shabonos*, communal houses formed by a ring of lean-to roofs thatched with palm leaves around an open plaza. The Budapest University of Technology and Economics' Habitatio resource gives diameters of 15 to 60 m (50 to 200 ft) and notes that shabonos usually have to be rebuilt every one to two years because of insects, heavy rain and wind.\n\n**Colonial.** Coro, founded in 1527 near the Caribbean coast, preserves about 602 historic buildings of earth. UNESCO describes construction in *bahareque* (mud, timber and bamboo), adobe and *tapia* (rammed earth), techniques still in use, combining Spanish Mudéjar and Indigenous traditions. From the second half of the 17th century, Dutch architectural influence arrived via the nearby islands of Curaçao and Aruba. Coro and its port were inscribed by UNESCO in 1993 and placed on the List of World Heritage in Danger in 2005 after rain damage.\n\n**Modern.** The Ciudad Universitaria de Caracas, a modernist campus, was inscribed by UNESCO in 2000.\n\n## Traditional and vernacular roofs\n\n- **Shabono** (see shabono).\n- **Bahareque and adobe houses** with clay tile roofs in colonial towns.\n\n## Roofing today\n\nConcrete slabs, metal sheet, fibre-cement sheet and clay tile are all in use.\n\n## Codes, standards and regulation\n\nA 2012 comparative review listed COVENIN 1756 (2001) as Venezuela's seismic design standard.\n\n## Notable roofs\n\n- **Coro and its Port** (UNESCO 1993): earthen buildings with Dutch Caribbean influence.\n- **Ciudad Universitaria de Caracas** (UNESCO 2000).\n\n## Local roofing terms\n\n- *Bahareque*: mud, timber and bamboo construction.\n- *Tapia*: rammed earth.\n- *Teja*: clay tile.\n- *Shabono* (also *yano*): Yanomami communal house.","key_facts":[{"label":"Indigenous roof","value":"Yanomami shabono, palm thatch"},{"label":"Colonial construction","value":"Bahareque, adobe, tapia (Coro)"},{"label":"Seismic code (2012 review)","value":"COVENIN 1756 (2001)"},{"label":"Heritage","value":"Coro (UNESCO 1993)"}],"regions":["Latin America"],"aliases":["Venezuelan roofing"],"related":["shabono","palm-thatch","clay-roof-tile","roofing-in-colombia","roofing-in-guyana","roofing-in-brazil"],"company":null,"sources":[{"title":"Coro and its Port","url":"https://whc.unesco.org/en/list/658","publisher":"UNESCO World Heritage Centre"},{"title":"Shabono","url":"https://en.wikipedia.org/wiki/Shabono","publisher":"Wikipedia"},{"title":"Yanomami shabono","url":"https://habitatio.epitesz.bme.hu/en/portfolio/yanomami-shabono/","publisher":"Habitatio, Budapest University of Technology and Economics"},{"title":"List of World Heritage Sites in South America","url":"https://en.wikipedia.org/wiki/List_of_World_Heritage_Sites_in_South_America","publisher":"Wikipedia"},{"title":"Building codes and relative seismic vulnerability in Latin American countries (15WCEE)","url":"https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_4534.pdf","publisher":"15th World Conference on Earthquake Engineering"}]},{"slug":"roofing-in-vietnam","title":"Roofing in Vietnam","category":"world-roofing","type":"place","country":{"name":"Vietnam","iso2":"VN"},"summary":"Roofing in Vietnam, from Dong Son-era stilt houses and handmade yin-yang clay tiles to the glazed double roofs of Hue and modern concrete tube houses.","body":"Vietnam stretches from the cool, mountainous north to the hot Mekong Delta, and its roofs range accordingly: boat-shaped and turtle-shell roofs on ancient stilt houses, curved clay-tile roofs on temples and communal halls, glazed imperial roofs in Hue, and the flat concrete roofs of today's narrow urban \"tube houses\".\n\n## Climate and hazards\n\nThe north has a subtropical climate with a cool winter; the centre and south are tropical. The central coast is regularly struck by typhoons and floods, and the whole country receives intense monsoon rain. Roofs must shed heavy rain, resist wind, and in the north help keep houses warm in winter as well as cool in summer.\n\n## Roofing history\n\n**Ancient period.** Bronze drums of the Dong Son culture depict stilt houses (*nha san*) built of wood and bamboo. Two roof types are shown: one curving upward at the ends like a boat and one curving down like a turtle shell.\n\n**Dynastic era.** Under the Ly dynasty, palaces had roofs of white and blue glazed tiles, and curved tile roofs were decorated with leaf, dragon and phoenix ornaments. Terracotta dragons and roof ornaments survive from the Tran dynasty (1225-1400). Under the Le dynasty, wooden palaces had yellow and green glazed tile roofs, and from this period Chinese-style bracket sets (*dougong*) were rarely or never used.\n\n**Nguyen dynasty and Hue.** Hue became the capital of a unified Vietnam in 1802 and remained the seat of the Nguyen dynasty until 1945. The Imperial City was begun under Emperor Gia Long in 1804 and enlarged to its present scale in 1833. Its principal halls, including the Thai Hoa throne hall, were built in the *trung thiem diep oc* style, a double-roofed form in which two roofs are joined front to back over one building. Upper floors of palaces carried yellow and green glazed tiles. Ordinary northern houses in this period had timber or thatched roofs.\n\n**War and restoration.** Much of the Hue citadel was burned in a six-week battle in 1947, and during the 1968 Tet Offensive most of its buildings were lost; only about 10 of 160 remained as major sites. Restoration has proceeded in stages using traditional techniques and materials (for example Thai Binh Lau in 1990-1991 and the rebuilt Tay Khuyet Dai in 2012), and the Complex of Hue Monuments was inscribed on the UNESCO World Heritage List in 1993.\n\n**Colonial and modern.** Under French rule, cement came into wide use. After 1954, architects in the south adapted modernism to the local climate.\n\n## Traditional and vernacular roofs\n\n- **Nha san (stilt house):** timber and bamboo, raised on posts; the type is depicted on Dong Son bronze drums and is still built in rural and upland areas.\n- **Yin-yang tile roofs (*ngoi am duong*):** curved clay tiles laid alternately face up and face down. The Tay and Nung of Lang Son and Cao Bang provinces still make them by hand (see separate entry).\n- **Temple and communal-hall roofs:** steep, large-span roofs of red clay tile are a defining feature of Vietnamese temples. Vinh Long in the Mekong Delta has a long tile-making tradition.\n- **Nha ruong:** timber-framed houses of the central and southern regions.\n\n## Roofing today\n\nThe 2019 Population and Housing Census reported that 93.1% of households lived in well-built (permanent) or semi-permanent houses, with average living space of about 23.5 m2 (253 sq ft) per person. Reinforced-concrete flat roofs are common on urban tube houses and apartment blocks.\n\n## Industry\n\nHandmade clay tile production continues in craft villages such as Lung Ri in Cao Bang, recognised as a traditional craft village by the province in 2024. Vinh Long is known as a centre of red ceramics.\n\n## Notable roofs\n\n- **Complex of Hue Monuments** (UNESCO, 1993): Thai Hoa Palace and the Imperial City.\n- **Village communal houses (*dinh*)**: large, steep tiled roofs over timber frames.\n\n## Local roofing terms\n\n- *ngoi* - roof tile; *ngoi am duong* - yin-yang tile\n- *nha san* - stilt house\n- *dinh* - village communal house\n- *trung thiem diep oc* - double-roof hall form (Hue)\n\n## Sources and gaps\n\nCensus figures for roof materials, code references and industry data: published information is limited.","key_facts":[{"label":"Traditional materials","value":"Clay tile (incl. yin-yang tile), thatch, bamboo, timber"},{"label":"Imperial roofs","value":"Yellow and green glazed tile (Le and Nguyen dynasties)"},{"label":"Housing (2019 census)","value":"93.1% of households in permanent or semi-permanent houses"},{"label":"Climate driver","value":"Typhoons and floods (centre), monsoon rain, cool northern winters"},{"label":"Heritage site","value":"Complex of Hue Monuments (UNESCO, 1993)"}],"regions":["Southeast Asia"],"aliases":["Vietnamese roofing","Viet Nam roofing"],"related":["roofing-in-southeast-asia","vietnamese-yin-yang-tile","clay-roof-tile","glazed-roof-tile","chinese-glazed-roof-tiles","pantile","bamboo-roofing","thatch","flat-roof","roofing-in-china","roofing-in-laos","roofing-in-cambodia"],"company":null,"sources":[{"title":"Architecture of Vietnam","url":"https://en.wikipedia.org/wiki/Architecture_of_Vietnam","publisher":"Wikipedia"},{"title":"Imperial City of Huế","url":"https://en.wikipedia.org/wiki/Imperial_City_of_Hu%E1%BA%BF","publisher":"Wikipedia"},{"title":"Complex of Hué Monuments","url":"https://whc.unesco.org/en/list/678/","publisher":"UNESCO World Heritage Centre"},{"title":"Yin-yang tile of the Tay, Nung in Lang Son","url":"https://vov5.vov.gov.vn/colorful-vietnam-vietnams-54-ethnic-groups/yin-yang-tile-of-the-tay-nung-in-lang-son-1807089.vov5","publisher":"Voice of Vietnam (VOV5)"},{"title":"Centuries-old clay tile craft thrives in Vietnam's Lung Ri","url":"https://vietnamnet.vn/en/centuries-old-clay-tile-craft-thrives-in-vietnam-s-lung-ri-2406078.html","publisher":"VietNamNet"},{"title":"Tradition in Clay: Vietnam's Architectural Exploration with Traditional Tiles","url":"https://www.archdaily.com/1032189/tradition-in-clay-vietnams-architectural-exploration-with-traditional-tiles","publisher":"ArchDaily"},{"title":"Outcomes of 2019 National Census released","url":"https://en.baochinhphu.vn/outcomes-of-2019-national-census-released-11135626.htm","publisher":"Viet Nam Government Portal"}]},{"slug":"roofing-in-west-africa","title":"Roofing in West Africa","type":"place","summary":"Overview of West African roofing: Sahelian earth roofs and coastal thatch traditions, now mostly corrugated metal and concrete slabs.","body":"West Africa spans the arid Sahel, the savanna and the humid coastal forest belt, and its traditional roofs reflect that gradient: flat earth roofs in the dry north, thatched conical and pitched roofs in the savanna and forest zones. Today corrugated metal sheet and reinforced concrete dominate new construction.\n\n## Sahel: earth roofs\n\nIn the Sudano-Sahelian zone, from Mali and Burkina Faso to Niger and northern Nigeria, buildings are made of earth using the *banco* technique of sun-dried bricks and earth plaster. Roofs are flat or slightly domed, built of timber and mud; the eastern Hausa tradition uses more timber than the western one. The Great Mosque of Djenné in Mali, rebuilt in 1906-1907, has a mud-covered roof of *rodier* palm timber, with vents capped by removable fired-clay bowls and ceramic spouts that carry rainwater clear of the walls. Its walls and roof are replastered each year by the community.\n\n## Savanna and forest: thatch\n\nFurther south, round and rectangular houses traditionally carried conical or pitched roofs thatched with grass or palm leaves over timber or bamboo frames, steeply pitched to shed heavy rain.\n\n## The shift to metal\n\nCorrugated metal sheet is now the most common roof across the region, valued for low cost and speed but criticised for heat gain and dependence on imports. Long-span aluminium and coated steel sheets and stone-coated steel tiles are popular on new houses in coastal cities.\n\n## Earth alternatives\n\nSince 2000 the association La Voûte Nubienne has promoted the Nubian vault, an earth-brick vault built without formwork or timber, as a roofing alternative in the Sahel. It reports more than 8,500 buildings completed and more than 4,900 masons trained across seven countries.\n\n## Concrete\n\nReinforced concrete flat roofs and slabs are standard on urban multi-storey buildings and many houses, often built incrementally with rebar left exposed for future floors.\n\n## Climate\n\nHeavy rainy-season downpours, intense sun and harmattan dust all affect roof performance and maintenance.","key_facts":[{"label":"Sahel tradition","value":"Flat earth roofs (banco)"},{"label":"Southern tradition","value":"Grass and palm thatch"},{"label":"Dominant modern covering","value":"Corrugated metal sheet"},{"label":"Earth alternative","value":"Nubian vault (AVN)"}],"regions":["Africa"],"aliases":["West African roofing","Nigerian roofing","Ghanaian roofing","Sahel roofing"],"related":["sahelian-earthen-roofs","djenne-earthen-architecture","nubian-vault","corrugated-iron","thatch"],"sources":[{"title":"Sudano-Sahelian architecture","url":"https://en.wikipedia.org/wiki/Sudano-Sahelian_architecture","publisher":"Wikipedia"},{"title":"Great Mosque of Djenn%C3%A9","url":"https://en.wikipedia.org/wiki/Great_Mosque_of_Djenn%C3%A9","publisher":"Wikipedia"},{"title":"La Voûte Nubienne","url":"https://www.lavoutenubienne.org/","publisher":"Association La Voûte Nubienne"}],"company":null,"category":"world-roofing","country":null},{"slug":"roofing-in-yemen","title":"Roofing in Yemen","category":"world-roofing","type":"place","country":{"name":"Yemen","iso2":"YE"},"regions":["Middle East"],"company":null,"summary":"Yemeni roofing: flat-roofed earth tower houses of Sana’a and Shibam, kept watertight by constant re-mudding, now threatened by floods and war.","aliases":["Yemeni roofing","Roofs of Yemen","Yemeni tower houses"],"body":"Yemen's tower houses are among the tallest earth buildings in the world. In the Old City of Sana'a, more than 6,000 houses rise several storeys on stone ground floors, built of rammed earth and fired brick with flat roofs; in Shibam, in the Hadhramaut, about 500 mud-brick towers reach up to eleven storeys. Their roofs and wall heads survive only through constant maintenance.\n\n## Climate and hazards\n\nSana'a sits in the highlands, while Shibam lies in the hot, dry Hadhramaut valley. Rain is infrequent but damaging: wind, rain and heat erode mud brick, and flooding is the most serious threat to Shibam. A tropical storm in October 2008 flooded Shibam and weakened building foundations, and some buildings later collapsed. Armed conflict has also damaged both cities.\n\n## Roofing history\n\n**Ancient Sana'a.** Sana'a has been inhabited for more than 2,500 years, became a trade-route centre by the 1st century AD and a major centre of Islam in the 7th and 8th centuries. Its ancient clay city walls stand 9-14 m (30-46 ft) high.\n\n**Shibam.** The walled city dates from the 16th century, after a flood in 1532-33 destroyed an earlier settlement; Shibam had become the Hadhramaut capital after about AD 300. Many houses have been rebuilt several times.\n\n**Late 19th century.** Traders returning from Asia revitalised Shibam.\n\n**Modern.** Concrete has been replacing traditional materials, which UNESCO identifies as a threat to both cities' authenticity.\n\n## Traditional and vernacular roofs\n\n- **Sana'a tower houses:** five to eight storeys (UNESCO's figures vary by language), with stone ground floors and upper floors of rammed earth (pisé) and burnt brick, decorated with fired-brick patterns and white gypsum; topped with flat roofs. In the Jewish Quarter, houses were lower and the main social room was on the top floor.\n- **Shibam mud-brick towers:** 5-11 storeys, some over 30 m (98 ft), one or two rooms per floor; walls must be regularly renewed with fresh mud. See shibam-tower-houses.\n\n## Roofing today\n\nConcrete construction has spread in and around historic cities.\n\n## Codes, standards and regulation\n\nThe General Organization for the Preservation of Historic Cities in Yemen (GOPHCY) was established in 1990. Historic cities are protected under the Antiquities Law of 1997 and the Building Law of 2002. In Shibam, GOPHCY's rehabilitation programme, supported by GIZ since 2000, has documented 98% of traditional houses and rehabilitated more than 60% of private houses.\n\n## Notable roofs\n\n- **Old City of Sana'a** (UNESCO): over 6,000 tower houses.\n- **Old Walled City of Shibam** (UNESCO): about 500 mud-brick towers; on the List of World Heritage in Danger since 2015.\n\n## Sources and gaps\n\nNational data on roofing materials, roof-specific local terms, details of traditional roof build-ups (timber, earth and lime layers) on Yemeni towers, and information on modern materials, codes beyond heritage law and industry were not found in published sources.","key_facts":[{"label":"Iconic buildings","value":"Earth tower houses (Sana’a, Shibam)"},{"label":"Sana’a houses","value":"Over 6,000"},{"label":"Shibam towers","value":"About 500, up to 11 storeys"},{"label":"Main threats","value":"Flood, rain erosion, concrete replacement, conflict"},{"label":"Heritage body","value":"GOPHCY (1990)"}],"related":["shibam-tower-houses","mud-roof","flat-roof","rammed-earth","roofing-in-saudi-arabia","roofing-in-oman","djenne-earthen-architecture","roofing-in-the-middle-east-and-gulf"],"sources":[{"title":"Old City of Sana'a","url":"https://whc.unesco.org/en/list/385","publisher":"UNESCO World Heritage Centre"},{"title":"Old City of Sanaa","url":"https://en.wikipedia.org/wiki/Old_City_of_Sanaa","publisher":"Wikipedia"},{"title":"Old Walled City of Shibam","url":"https://whc.unesco.org/en/list/192","publisher":"UNESCO World Heritage Centre"},{"title":"Shibam","url":"https://en.wikipedia.org/wiki/Shibam","publisher":"Wikipedia"}]},{"slug":"roofing-in-zambia","title":"Roofing in Zambia","category":"world-roofing","type":"place","country":{"name":"Zambia","iso2":"ZM"},"summary":"Zambian roofs are mainly metal sheet and grass thatch; national surveys also record asbestos, cement-fibre sheet, mud tiles and 'harvey tiles'.","body":"Zambia is a landlocked plateau country. Its household surveys record roofs ranging from grass thatch and palm to metal sheet, cement fibre, asbestos, tiles and mud tiles, and the questionnaires reveal some distinctive local vocabulary, including \"harvey tiles\" and \"calamine\".\n\n## Climate and hazards\n\nRain falls in a single summer wet season. In the west, the Zambezi floods the Barotse (Bulozi) floodplain each year, displacing hundreds of people; the Lozi king (Litunga) moves each year at the start of the wet season, usually in February or March, from Lealui on the floodplain to Limulunga on higher ground in the Kuomboka ceremony.\n\n## Roofing history\n\nThe Lozi kingdom was founded in the 17th century on the Bulozi floodplain, where settlement has always had to adapt to the annual flood.\n\n## Traditional and vernacular roofs\n\n- **Thatched houses**: thatch and palm leaf remain a survey category in every Zambia DHS.\n- **Floodplain settlement**: Lozi seasonal movement between floodplain and higher ground (Kuomboka).\n\n## Roofing today\n\nThe Zambia Demographic and Health Surveys (2013-14, 2018 and 2024) record roofs under the following categories: thatch/palm leaf; rustic mat; palm/bamboo; wood planks; cardboard; metal/iron sheets; wood; calamine/cement fibre; ceramic tiles/harvey tiles; cement; roofing shingles; mud tiles; and, from 2018, asbestos as a separate code.\n\n## Local roofing terms\n\n- *harvey tiles*: Zambian survey term grouped with ceramic tiles.\n- *calamine*: survey term grouped with cement-fibre sheet.\n\n## Sources and gaps\n\nDetailed archaeological evidence for early roofs: published information is limited. Shares for these categories were not found in published sources. No national roofing standard was identified. No roof-specific heritage listings were identified.\n\nNo published national share of roof materials was found; the DHS microdata documentation lists categories only. Lozi and Bemba house forms, and information on Zambian sheet and tile manufacturing: published information is limited.","key_facts":[{"label":"Common materials","value":"Metal sheet, grass thatch, fibre-cement and asbestos sheet, tiles"},{"label":"Climate driver","value":"Summer wet season; Zambezi floods in the west"},{"label":"Survey categories","value":"Zambia DHS 2013-14, 2018, 2024 (hv215)"}],"regions":["Africa"],"aliases":["Zambian roofing"],"related":["thatch","corrugated-iron","asbestos-cement-roofing","corrugated-fibre-cement-sheet","concrete-roof-tile","roofing-in-malawi","roofing-in-zimbabwe","roofing-in-angola","roofing-in-the-democratic-republic-of-the-congo","roofing-in-tanzania","roofing-in-namibia","roofing-in-botswana","roofing-in-mozambique"],"company":null,"sources":[{"title":"Zambia DHS 2018: Main roof material (hv215)","url":"https://catalog.ihsn.org/catalog/8845/variable/F3/V99?name=hv215","publisher":"IHSN Survey Catalog"},{"title":"Zambia DHS 2024: Main roof material (hv215)","url":"https://catalog.ihsn.org/catalog/13510/variable/F3/V102?name=hv215","publisher":"IHSN Survey Catalog"},{"title":"Lozi people","url":"https://en.wikipedia.org/wiki/Lozi_people","publisher":"Wikipedia"}]},{"slug":"roofing-in-zimbabwe","title":"Roofing in Zimbabwe","category":"world-roofing","type":"place","country":{"name":"Zimbabwe","iso2":"ZW"},"summary":"Zimbabwe's roofs run from Great Zimbabwe's daga huts and thatch to modern asbestos-cement and iron sheet, which cover most homes in recent surveys.","body":"Zimbabwe takes its name from stone: the Shona word *zimbabwe* is usually translated as \"house of stone\", after the walled capital of Great Zimbabwe. Inside those walls, however, people lived in earthen (daga) huts, and the round house with mud walls and a conical thatched roof remained the rural norm for centuries. Today most homes are roofed with sheet materials, and Zimbabwe stands out in the region for the large share of asbestos-cement roofs.\n\n## Climate and hazards\n\nMost of the country is high plateau with a single summer rainy season, when heavy thunderstorms fall on roofs, followed by a long dry season. Granaries were traditionally raised to keep grain away from damp, insects and rodents, and roofs had to shed intense seasonal rain.\n\n## Roofing history\n\nFarming, iron-working communities of the Gokomere or Ziwa cultures occupied the area of Great Zimbabwe from around the 4th to 7th centuries CE but built no stone structures. Stone building at Great Zimbabwe began in the 11th century and continued for over 300 years; the city flourished between about 1100 and 1450, and the capital was abandoned around 1450. The site covers almost 800 ha (about 1,980 acres), of which the city itself occupies nearly 80 ha (about 200 acres).\n\nUNESCO describes the Great Enclosure, built of cut granite blocks in regular courses in the 14th century, as containing a series of daga-hut living quarters, with huts built within the enclosure walls. Daga bricks were made from granitic sand mixed with clay, and each family area typically had a kitchen, two living huts and a court. Most of the population lived outside the walls in mud houses on timber frames, while the ruling group built thicker daga houses, a change that advanced quickly in the 13th century. The Great Enclosure walls stand up to 11 m (36 ft) high and are built without mortar.\n\nEuropean influence introduced rectangular buildings with concrete walls and corrugated iron roofs.\n\n## Traditional and vernacular roofs\n\n- **Shona homestead**: circular huts around a courtyard, with a central kitchen hut and a separate, often decorated, sleeping hut. Walls are mud on a frame of sticks and roofs are conical grass thatch.\n- **Granaries**: built high off the ground to keep out damp, insects and rodents.\n- **Storage huts**: lighter structures of branches and sticks.\n\n## Roofing today\n\nIn the unweighted 2019 Multiple Indicator Cluster Survey (MICS) sample, 11,091 households recorded a roof material. Unweighted shares of those records are:\n\n| Main roof material (HC5) | Share of sampled households |\n|---|---|\n| Asbestos | 50.6% |\n| Metal / tin | 25.9% |\n| Thatch / palm leaf | 19.6% |\n| Ceramic tiles | 2.1% |\n| Cement | 0.7% |\n| Other (mat, wood, shingles, no roof) | 1.1% |\n\nAsbestos-cement sheet is therefore the most common recorded roof in the survey sample, ahead of metal sheet, while thatch remains significant on rural homesteads.\n\n## Codes, standards and regulation\n\nGreat Zimbabwe has been legally protected since 1893.\n\n## Notable roofs\n\n- **Great Zimbabwe National Monument** (UNESCO 1986): daga huts within dry-stone enclosures; the Conical Tower is 5.5 m (18 ft) in diameter and 9 m (30 ft) high.\n- **Reserve Bank of Zimbabwe** (opened 31 May 1996): a conical tower referencing Great Zimbabwe, with a conical roof to throw off rain.\n- **Kingdom Hotel**: a domed roof incorporating grass, with timber roof beams in a traditional idiom.\n\n## Local roofing terms\n\n- *daga*: earthen building material of sand and clay, used for bricks, floors and plaster.\n- *zimbabwe* (Shona): house of stone.\n\n## Sources and gaps\n\nNo national roofing standard was identified.\n\nMICS figures are unweighted sample counts. Detailed Shona or Ndebele thatching terminology, ZIMSTAT 2022 census roof tables and information on asbestos-cement manufacture in Zimbabwe: published information is limited.","key_facts":[{"label":"Dominant material today","value":"Asbestos-cement sheet, 50.6% (MICS 2019 file, unweighted)"},{"label":"Traditional materials","value":"Daga (sand and clay), grass thatch, poles"},{"label":"Climate driver","value":"Summer thunderstorm rain"},{"label":"Landmark","value":"Great Zimbabwe (UNESCO 1986)"}],"regions":["Africa"],"aliases":["Zimbabwean roofing"],"related":["great-zimbabwe","roofing-in-southern-africa","asbestos-cement-roofing","corrugated-iron","thatch","conical-roof","rondavel","roofing-in-south-africa","roofing-in-mozambique","roofing-in-zambia","roofing-in-botswana"],"company":null,"sources":[{"title":"Great Zimbabwe National Monument","url":"https://whc.unesco.org/en/list/364/","publisher":"UNESCO World Heritage Centre"},{"title":"Great Zimbabwe","url":"https://en.wikipedia.org/wiki/Great_Zimbabwe","publisher":"Wikipedia"},{"title":"Architecture of Zimbabwe","url":"https://en.wikipedia.org/wiki/Architecture_of_Zimbabwe","publisher":"Wikipedia"},{"title":"Zimbabwe MICS 2019: Main material of roof (HC5)","url":"https://microdata.worldbank.org/catalog/4180/variable/F4/V1037?name=HC5","publisher":"World Bank Microdata Library"}]},{"slug":"ricowi","title":"Roofing Industry Committee on Weather Issues (RICOWI)","summary":"RICOWI is a U.S. roofing industry group that sends investigation teams to study roof performance after major hail and windstorms.","body":"The Roofing Industry Committee on Weather Issues (RICOWI) is a non-profit organisation in the United States that brings roofing industry groups together to study how roofs perform in severe weather. Its website is ricowi.com.\n\n## Membership\n\nRICOWI is supported by sponsor member organisations from across the building and roofing industry. Its sponsor members include:\n\n- the Asphalt Roofing Manufacturers Association (ARMA);\n- the Cedar Shake & Shingle Bureau;\n- the Insurance Institute for Business & Home Safety (IBHS);\n- the International Institute of Building Enclosure Consultants (IIBEC);\n- the Metal Construction Association and the Metal Building Manufacturers Association;\n- the Single Ply Roofing Industry (SPRI);\n- the Tile Roofing Industry Alliance;\n- the Spray Polyurethane Foam Alliance;\n- National Women in Roofing, the Air Barrier Association of America and other groups.\n\nInsurers and manufacturers also support its programs.\n\n## Investigation programs\n\nRICOWI runs two field investigation programs:\n\n- **Wind Investigation Program.** After hurricanes and major windstorms, RICOWI organises teams of trained volunteers, often consultants, manufacturers' technical staff, researchers and contractors, to inspect damaged and undamaged roofs. They record how different roof systems, edges, flashings and attachments performed.\n- **Hail Investigation Program.** Similar teams study roofs after large hailstorms, documenting hail size and damage to different roof coverings.\n\nFindings are published as reports and white papers. For example, RICOWI has published work on the performance of low-slope roofs in Hurricane Ian (2022) and reported on Hurricane Idalia (2023).\n\n## Why it matters\n\nField data from real storms help show which installation practices and products resist wind and hail, and where failures start, such as at roof edges or due to poor fastening. These findings inform building codes, manufacturers' instructions and programs such as IBHS's FORTIFIED standard.\n\n## Events\n\nRICOWI holds seminars and meetings where investigation results are presented to the industry.\n\n## Related bodies\n\nComparable post-disaster investigations are also carried out by government agencies, insurers and research organisations in other countries, including building research institutes in Australia and New Zealand after cyclones and storms.","key_facts":[{"label":"Country","value":"United States"},{"label":"Programs","value":"Wind Investigation Program; Hail Investigation Program"},{"label":"Sponsor members","value":"15 industry organisations (2026)"},{"label":"Website","value":"ricowi.com"}],"regions":["North America"],"aliases":["RICOWI"],"related":["ibhs","hail-damage","wind-uplift","asphalt-roofing-manufacturers-association"],"company":{"website":"https://www.ricowi.com","known_for":["Post-storm roof performance investigations"]},"sources":[{"title":"RICOWI home page","url":"https://www.ricowi.com/","publisher":"RICOWI"},{"title":"About IBHS","url":"https://www.ibhs.org/about-ibhs/","publisher":"IBHS"}],"category":"organizations","type":"organization","country":null},{"slug":"roofing-kettle","title":"Roofing Kettle","category":"tools-equipment","type":"term","summary":"A fuel-fired tank that melts and heats asphalt or coal tar for hot-applied built-up roofing and other hot-mopped systems.","body":"A roofing kettle is a heated vessel used to melt solid asphalt (or, historically and in some markets, coal tar pitch) and keep it at the correct temperature for application. Kettles are central to hot-applied built-up roofing (BUR), where layers of felt are bonded with mopped or mechanically spread hot bitumen, and to some modified bitumen and waterproofing work.\n\n## Equipment\n\n- **Kettles or tankers**, typically trailer-mounted, heated by propane or other fuel burners, with capacities sized to the job.\n- **Thermometers and thermostatic controls** to monitor and limit temperature.\n- **Pumps and pipelines** to move hot bitumen to the roof, or **luggers** and buckets for hand transport.\n- **Lids and lid-closing mechanisms** to smother fires and reduce fumes.\n- **Mops and mechanical spreaders** for application.\n\n## Temperature control\n\nCorrect temperature is essential to roof performance and safety. Industry guidance uses the **equiviscous temperature (EVT)**, the temperature at which the bitumen reaches the viscosity suited to mopping or mechanical spreading, measured at the point of application. Guidance published through IIBEC includes:\n\n- Asphalt has a minimum flash point of 500 °F (260 °C) under ASTM D312.\n- Asphalt should not be heated above 550 °F (288 °C), nor within 25 °F (14 °C) of its flash point.\n- Asphalt should not be held between 500 °F and 550 °F for more than about four hours.\n- Kettles are typically run somewhat above EVT to allow for heat loss in transport.\n\nOverheating can lower the asphalt's softening point (\"drop-back\"), changing its properties.\n\n## Hazards\n\n- **Burns** from hot bitumen are a serious risk; workers wear long sleeves, gloves, boots and eye protection.\n- **Fire**: kettles must be attended, placed away from buildings and combustibles, with extinguishers nearby.\n- **Fumes**: US NIOSH has studied asphalt fume exposure among roofers; controls include keeping lids closed and avoiding excessive temperatures.\n- **Propane** cylinders and lines must be handled safely.\n\nMany jurisdictions regulate kettle placement, attendance and fuel storage through fire codes. The use of hot-applied systems has declined in some markets as cold-applied, self-adhered and single-ply systems have grown.","key_facts":[{"label":"Used for","value":"Hot-applied built-up roofing and mopped systems"},{"label":"Max asphalt temperature","value":"550 °F (288 °C)"},{"label":"Minimum flash point","value":"500 °F (260 °C), ASTM D312"}],"regions":["Global","North America"],"aliases":["tar kettle","asphalt kettle","bitumen boiler"],"related":["built-up-roofing","roofing-torch","modified-bitumen-roofing","alligatoring"],"company":null,"sources":[{"title":"EVT: Equiviscous Temperature in Built-Up Roofing","url":"https://iibec.org/publication-post/evt-equiviscous-temperature-in-built-up-roofing/","publisher":"IIBEC"},{"title":"Controlling kettle and maintaining the temperature of hot asphalt in cold weather commercial roof applications","url":"https://www.rooferscoffeeshop.com/post/controlling-kettle-and-maintaining-the-temperature-of-hot-asphalt-in-cold-weather-commercial-roof-applications","publisher":"RoofersCoffeeShop"},{"title":"Asphalt Fume Exposures During the Application of Hot Asphalt to Roofs (archived)","url":"https://webarchive.library.unt.edu/eot2008/20090114025144/http:/www.cdc.gov/niosh/docs/2003-112/2003-112p2.html","publisher":"NIOSH"}],"country":null},{"slug":"roofing-market-size","title":"Roofing Market Size and Statistics","type":"article","summary":"Estimates of the size and growth of the global roofing materials market, with the dates and limits of the figures.","body":"The roofing market covers the manufacture and sale of roof coverings and related materials, and in broader definitions the installation services that go with them. Its size is estimated mainly by private market research firms, whose figures vary according to how they define the market, which products and regions they include, and the year of the estimate.\n\n## Global market estimate\n\nGrand View Research, in a report published in June 2026, estimated the global roofing materials market at USD 138.7 billion in 2025 and projected it to reach USD 191.5 billion by 2033, a compound annual growth rate of 4.2 percent from 2026 to 2033. The same report found:\n\n- **Largest product segment:** concrete and clay tiles, with 30.5 percent of revenue in 2025.\n- **Largest region:** Asia Pacific, with 33.5 percent of revenue in 2025.\n\n## Why estimates differ\n\nOther research firms publish different totals because they may:\n\n- include or exclude installation labour;\n- include waterproofing, insulation, gutters or skylights;\n- value products at factory, wholesale or retail prices;\n- use different base years and currency conversions.\n\nFigures should therefore be compared only when definitions and years match.\n\n## Market drivers\n\n- **Replacement demand.** In mature markets, reroofing of existing buildings is a large share of demand because roofs wear out decades before the buildings they cover.\n- **New construction**, especially in growing urban regions of Asia, Africa and Latin America.\n- **Weather events**, which create surges of repair and replacement work after hail, hurricanes and storms.\n- **Energy and climate policy**, including cool roof requirements, green roof laws and rooftop solar.\n\n## Regional patterns\n\nMaterial preferences vary strongly by region. Asphalt shingles are among the most widely used roof covers in North America, while clay and concrete tile have long traditions across Europe and Asia; clay tiles cover about 90 percent of houses in Java, Indonesia, for example. Such regional patterns help explain why tile, rather than shingles, is the largest segment in global estimates.\n\n## Workforce\n\nIn the United States, the Bureau of Labor Statistics counted about 166,900 roofer jobs in 2025, with employment projected to grow 5 percent from 2025 to 2035.","key_facts":[{"label":"Global roofing materials market (2025)","value":"USD 138.7 billion (Grand View Research, 2026)"},{"label":"Forecast (2033)","value":"USD 191.5 billion, 4.2% CAGR"},{"label":"Largest segment (2025)","value":"Concrete and clay tiles, 30.5%"},{"label":"Largest region (2025)","value":"Asia Pacific, 33.5%"}],"regions":["Global"],"aliases":["roofing industry size","roofing market","roofing statistics"],"related":["roofing-workforce","roofing-fatality-statistics","asphalt-shingle","clay-roof-tile"],"sources":[{"title":"Roofing Materials Market Size, Share & Trends Analysis Report","url":"https://www.grandviewresearch.com/industry-analysis/roofing-materials-market","publisher":"Grand View Research"},{"title":"Occupational Outlook Handbook: Roofers","url":"https://www.bls.gov/ooh/construction-and-extraction/roofers.htm","publisher":"US Bureau of Labor Statistics"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roofing-nailer","title":"Roofing Nailer (Coil Nailer)","category":"tools-equipment","type":"term","summary":"A pneumatic or cordless nail gun fed by coils of short, wide-headed nails, used mainly to fasten asphalt shingles and underlayment.","body":"A roofing nailer is a power nailer designed for fastening asphalt shingles, underlayments and similar materials. Most are pneumatic, powered by compressed air from a portable compressor, though cordless models exist. They hold nails collated on a wire or plastic coil in a round magazine, which carries far more fasteners than a stick magazine and suits the rapid, repetitive nailing of shingling. Common models drive 15-degree coil roofing nails, and typical product specifications list nail lengths from 3/4 in to 1-3/4 in (about 19 to 44 mm).\n\n## Features\n\n- **Depth adjustment** to set how deeply the nail head is driven. Correct depth leaves the head flush with the shingle surface; overdriven nails cut into the shingle and underdriven nails stand proud, which can cause nail pops and affect wind resistance.\n- **Shingle guide** to help space nails or courses on some models.\n- **Lightweight frames and non-marring or carbide-tipped noses** for working on slopes.\n- **Trigger modes**: contact (bump) firing, which drives a nail each time the nose is pressed with the trigger held, and sequential firing, which requires the nose to be pressed before each trigger pull. The joint NIOSH and OSHA guide *Nail Gun Safety: A Guide for Construction Contractors* (2011) lists using full sequential trigger tools as its first prevention step, citing research that injury risk roughly doubles with contact triggers.\n\n## Correct use\n\nShingle manufacturers specify nail type, length, head size and the nailing zone on each shingle; following these instructions affects both performance and warranty coverage. Nails must penetrate the deck sufficiently, and nailing outside the specified zone is a common cause of blow-offs. Air pressure should be adjusted to the material and temperature, since cold shingles and hard decks change how far nails drive. Hand nailing with a roofing hammer or hatchet remains in use for detail work, repairs and some materials.\n\n## Safety\n\nNail guns cause many construction injuries, including puncture wounds and nails ricocheting off hard surfaces. Basic practice includes eye protection, keeping fingers off the trigger when moving, disconnecting the air supply before clearing jams, and managing the air hose so it does not become a trip hazard on the roof.","key_facts":[{"label":"Common collation","value":"15-degree wire or plastic coil"},{"label":"Typical nail range","value":"3/4-1-3/4 in (about 19-44 mm)"},{"label":"Power","value":"Pneumatic, some cordless"}],"regions":["Global"],"aliases":["coil roofing nailer","roofing nail gun","shingle nailer"],"related":["asphalt-shingle","nail-pops","roofing-hatchet","personal-fall-arrest-system","roofing-hoist"],"company":null,"sources":[{"title":"DeWalt DW45RN Pneumatic Roofing Nailer 3/4-1-3/4 in","url":"https://leestools.com/products/dewalt-dw45rn-pneu-roofing-nailer-3-4-1-3-4in","publisher":"Lee's Tools"},{"title":"Bostitch 15 Degree 1-3/4 In. Coil Roofing Nailer","url":"https://www.doitbest.com/product/347639/bostitch-15-degree-1-3-4-in-coil-roofing-nailer-347639","publisher":"Do it Best"},{"title":"Porter-Cable 15 Degree Pneumatic Coil Roofing Nailer","url":"https://acetool.com/products/porter-cable-15-degree-pneumatic-coil-roofing-nailer","publisher":"Acme Tools"},{"title":"Nail Gun Safety: A Guide for Construction Contractors","url":"https://stacks.cdc.gov/view/cdc/6013","publisher":"NIOSH and OSHA"}],"country":null},{"slug":"roofing-permits-and-inspections","title":"Roofing Permits and Inspections","category":"installation","type":"article","summary":"Many authorities require a permit for roof replacement and some for larger repairs, with inspections to confirm compliance with the building code.","body":"A **roofing permit** is official permission from a local building authority to carry out roof work. Permits allow the authority to check that the work meets the building code: for example, that the number of roof layers is within the limit, that ice barrier and underlayment rules are followed, that wind-rated products are used and that the structure can carry the new covering. Requirements vary greatly between and within countries.\n\n## United States and Canada\n\nPermits are issued by cities, counties or provinces under codes based on model codes such as the International Residential Code or the National Building Code of Canada. Two US examples show the range:\n\n- **Bloomington, Minnesota** requires a permit to re-roof a house and also for roofing repairs larger than 10 x 10 ft (one square). The permit can be obtained by the homeowner or by a state-licensed contractor.\n- **Norman, Oklahoma** does not require a permit for asphalt shingle roofing, but the work must still comply with all adopted codes, including the local one-layer recover limit, and roofing contractors must be registered with the state.\n\nInspections, where required, may be scheduled during the work (for example to view the deck after tear-off or the ice barrier) and at completion. Some building departments do not judge whether sheathing is structurally sound, leaving that decision to the contractor, an engineer or the owner.\n\n## United Kingdom and Europe\n\nIn the UK, replacing a roof covering like for like is often outside planning control, but building regulations can apply, particularly where a significant part of the roof is renewed, insulation must be upgraded or a heavier covering changes the loads on the structure. Listed buildings and conservation areas have additional consent rules. Elsewhere in Europe, rules are set nationally and locally.\n\n## Other regions\n\nAustralia and New Zealand regulate roofing through national building codes and state, territory or council approvals. Which re-roofing work needs approval, and which is exempt, is set by those codes and local authorities.\n\n## Who is responsible\n\nContracts should say who applies for the permit and pays the fee. Working without a required permit can lead to fines, problems when selling a property and complications with insurance claims.","key_facts":[{"label":"Bloomington, MN repair threshold","value":"Over 10 x 10 ft (one square)"},{"label":"Norman, OK shingle permit","value":"Not required; code compliance still required"},{"label":"Who can obtain (Bloomington)","value":"Homeowner or state-licensed contractor"}],"regions":["Global"],"aliases":["roof permit","re-roofing permit","building permit for roof"],"related":["tear-off-vs-overlay","hiring-a-roofer","roof-replacement-process"],"company":null,"sources":[{"title":"Reroofing","url":"https://www.bloomingtonmn.gov/sites/default/files/2023-08/Reroofing.pdf","publisher":"City of Bloomington, Minnesota"},{"title":"Roofing FAQs","url":"https://www.normanok.gov/sites/default/files/documents/2023-07/roofing_faqs.pdf","publisher":"City of Norman, Oklahoma"},{"title":"Can you put new shingles over old shingles under IRC 2021?","url":"https://www.jaspector.com/codes/irc-2021/ch09-roof-assemblies/reroofing-code-existing-shingles/","publisher":"Jaspector"}],"country":null},{"slug":"roofing-shovel","title":"Roofing Shovel (Tear-Off Tool)","category":"tools-equipment","type":"term","summary":"A long-handled spade with a notched or serrated blade and a fulcrum heel, used to strip old shingles and nails during tear-off.","body":"A roofing shovel, also called a tear-off shovel, shingle remover or roof ripper, is the main hand tool for stripping old shingles from a roof deck before reroofing. It resembles a garden spade but has a flat, wide blade with notches or teeth along the front edge and, on many models, a bent heel or fulcrum on the underside.\n\n## How it works\n\nThe roofer pushes the blade under the shingles, usually working upslope from the eave or downslope from the ridge depending on crew practice. The teeth or notches catch the shanks of the roofing nails, and the fulcrum heel acts as a pivot so that a downward push on the handle levers the shingles and nails up together. Removing nails with the shingles reduces the work of pulling them separately, though some always remain and must be pulled or driven flush before the new roof goes on.\n\n## Variants\n\n- **Long-handled shovels** for standing work on lower-slope roofs.\n- **Short D-handle shovels** for steeper slopes and tight areas.\n- **Serrated or smooth blades**: serrations grip nails and old felt; smooth blades suit some materials.\n- **Steel, aluminium or fibreglass handles**, balancing durability against weight and electrical conductivity.\n- **Powered tear-off machines** used on low-slope roofs to cut and lift membranes and gravel surfacing.\n\n## Related tear-off equipment\n\n- **Pry bars and flat bars** for flashing and details.\n- **Magnetic sweepers** to collect nails from the ground and driveway.\n- **Chutes and dumpsters**, or trailers placed close to the eave.\n- **Tarps** to protect landscaping, walls and windows.\n\n## Safety\n\nTear-off produces loose debris and slippery surfaces, especially on dusty or wet decks, and workers can lose footing when a section of shingles suddenly releases. Fall protection, roof brackets with planks, and good housekeeping are standard on pitched roofs. Old roofing materials may contain asbestos in some older buildings and regions, which requires testing and specialist handling under local regulations.","key_facts":[{"label":"Key features","value":"Notched blade and fulcrum heel"},{"label":"Removes","value":"Shingles and nails together"},{"label":"Companion tools","value":"Pry bars, magnetic sweeper, chutes"}],"regions":["Global","North America"],"aliases":["tear-off shovel","shingle remover","roof ripper","shingle stripper"],"related":["magnetic-sweeper","roof-jacks","personal-fall-arrest-system","asphalt-shingle","repair-vs-replace"],"company":null,"sources":[{"title":"61 in. Roofers Spade Shovel","url":"https://tiedown.com/roofing/roofing-tools/shingle-removal-tools/pid79/61-in-roofers-spade-shovel/","publisher":"Tie Down Engineering"},{"title":"Shingle remover tool, wood handle","url":"https://www.garant.com/en/products/shingle-remover-tool-wood-handle-80163","publisher":"Garant"},{"title":"US4203210A - Shingle stripper","url":"https://patents.google.com/patent/US4203210","publisher":"Google Patents"}],"country":null},{"slug":"roofing-square","title":"Roofing Square","category":"installation","type":"term","summary":"A roofing square is a North American unit of roof area equal to 100 square feet (about 9.3 m²), used for ordering and pricing roofing.","body":"A **square** is the standard unit of roof area in the United States and Canada. One square equals **100 square feet**, or about **9.3 square metres**, of finished roof surface. Shingles, metal panels, underlayment and labour are commonly priced and ordered per square, and roofers describe roof sizes in squares (for example, \"a 25-square roof\").\n\n## Coverage, not product area\n\nA square of roofing material is the amount needed to cover 100 sq ft of roof once installed with the intended overlaps. Because shingles, shakes and tiles overlap, the actual area of product in a square is greater than 100 sq ft. Asphalt shingles are packaged in bundles, and the number of bundles that make one square varies by product and is printed on the packaging.\n\nWaste from cutting is not included in the square, so estimators add a waste factor on top.\n\n## Converting measurements\n\n- Squares = roof area in square feet / 100.\n- Square metres = squares x 9.29 (approximately).\n- Plan (horizontal) area must first be converted to sloped area with a pitch multiplier.\n\nExample: a roof with 2,350 sq ft of surface is 23.5 squares, or about 218 m².\n\n## Other uses of the unit\n\nThe square is also used for siding and some other cladding products in North America. In Australia, the square was historically used for house floor areas and is still sometimes used in real estate in Victoria, but construction there now uses square metres. In most other countries, roofing is measured and sold in square metres.\n\n## Related unit in low-slope roofing\n\nApplication rates for bitumen and coatings in North America are often given per square, for example pounds of asphalt per square, alongside metric rates in kilograms per square metre.","key_facts":[{"label":"Size","value":"100 sq ft"},{"label":"Metric equivalent","value":"About 9.3 m²"},{"label":"Regions","value":"Mainly United States and Canada"}],"regions":["North America"],"aliases":["square","roofing square","sq","roof square"],"related":["roof-measurement-and-estimating","waste-factor","roof-pitch-calculation","roof-pitch","rafter"],"company":null,"sources":[{"title":"Square (unit)","url":"https://en.wikipedia.org/wiki/Square_(unit)","publisher":"Wikipedia"},{"title":"Canadian Roofing Reference Manual: 4.1.2 Application of Roofing Felts","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-4-built-up-roof-membranes/4-1-hot-applied-built-up/4-1-2-application-of-roofing-felts/","publisher":"Canadian Roofing Contractors Association"},{"title":"Roof pitch","url":"https://en.wikipedia.org/wiki/Roof_pitch","publisher":"Wikipedia"}],"country":null},{"slug":"roofing-today","title":"Roofing Today (magazine)","summary":"Roofing Today is a UK trade magazine and news site for roofing contractors and specifiers, published by Construction Media Publishing Ltd.","body":"*Roofing Today* is a trade magazine for the roofing industry in the United Kingdom, published by Construction Media Publishing Ltd. It is aimed at roofing contractors and specifiers. Alongside the print magazine, its website roofingtoday.co.uk publishes news, videos and job listings, and it sends weekly email bulletins.\n\n## Publication\n\nThe print magazine appears several times a year; issue 126 was dated September-October 2026, which points to a bimonthly schedule. The magazine covers the whole range of roofing work found in the UK:\n\n- pitched roofing with slate, clay and concrete tiles;\n- flat roofing, including single-ply membranes, built-up felt, mastic asphalt and liquid-applied systems;\n- metal roofing and leadwork;\n- roof windows, rooflights and ventilation;\n- safety, regulation and training.\n\n## Coverage\n\nCoverage includes news from UK roofing trade associations such as the National Federation of Roofing Contractors (NFRC), product launches, project case studies and reports on industry events. It has also reported on international roofing events, such as the congress of the International Federation for the Roofing Trade (IFD).\n\n## UK roofing context\n\nThe UK roofing industry is regulated through building regulations, health and safety law enforced by the Health and Safety Executive (HSE), and industry codes such as BS 5534 for slating and tiling and BS 6229 for flat roofs. Topics such as the Building Safety Act, fire performance of roof systems and the skills shortage are regular subjects for trade publications.\n\n## Related publications\n\nOther UK titles serving roofers include association journals and general construction magazines. In North America, the closest counterparts are *Roofing Contractor* and *Professional Roofing*.","key_facts":[{"label":"Publisher","value":"Construction Media Publishing Ltd"},{"label":"Country","value":"United Kingdom"},{"label":"Audience","value":"Roofing contractors and specifiers"},{"label":"Website","value":"roofingtoday.co.uk"}],"regions":["Europe"],"aliases":["Roofing Today magazine"],"related":["national-federation-of-roofing-contractors","roofing-contractor-magazine","professional-roofing-magazine"],"company":{"website":"https://roofingtoday.co.uk","parent":"Construction Media Publishing Ltd","known_for":["UK roofing trade news"]},"sources":[{"title":"Roofing Today","url":"https://roofingtoday.co.uk/","publisher":"Construction Media Publishing"},{"title":"International roofing community gathers for IFD Congress 2019","url":"https://roofingtoday.co.uk/international-roofing-community-gathers-for-ifd-congress-2019","publisher":"Roofing Today"}],"category":"organizations","type":"organization","country":null},{"slug":"roofing-torch","title":"Roofing Torch","category":"tools-equipment","type":"term","summary":"A propane-fuelled open-flame torch used to melt the bitumen on torch-applied modified bitumen membranes during installation.","body":"A roofing torch is a large open-flame burner, usually fuelled by propane (LPG) through a hose and regulator, used to install torch-applied modified bitumen membranes. The roofer heats the underside of the roll as it is unrolled, melting a thin layer of bitumen that bonds the sheet to the substrate or to the ply below and seals the laps. Torch-applied polymer-modified bitumen has been used in North America since the late 1970s and is common in Europe and other regions.\n\n## Equipment\n\n- **Torch head and wand**, with a long handle that keeps the flame at a working distance.\n- **Hose, regulator and cylinder**, with valves and fittings suited to the fuel.\n- **Pilot or ignition controls** on many models.\n- **Detail torches**, smaller units for flashings and laps.\n- **Multi-head torch carts** for large field areas.\n\n## Fire risk\n\nTorch use is a well-recognised cause of roof and building fires. Fires often start where the flame reaches hidden combustibles: at flashings, penetrations, wall junctions, in voids beneath decks, and in insulation or debris. Smouldering fires can break out hours after work has finished.\n\n## Safe practice\n\nIndustry programmes such as the CERTA (Certified Roofing Torch Applicator) training programme, run with the US National Roofing Contractors Association, set out practices that commonly include:\n\n- Training and certification of torch operators.\n- Not torching directly onto combustible substrates or into concealed spaces; using alternative methods such as self-adhered or cold-applied materials at risky details.\n- Fire extinguishers within easy reach of each torch.\n- A fire watch after torching stops. Ontario's fire code, for example, requires a two-hour fire watch; thermal imaging cameras have been proposed to help find hidden hot spots.\n- Proper storage and handling of propane cylinders, and turning off cylinders when not in use.\n\nIn 2019, NRCA stopped recommending torch-applied modified bitumen over combustible roof decks such as wood decks and wood panels, even with a thermal barrier, and suggested cold-adhesive alternatives; because CERTA follows the NRCA manual, the same exclusion applies within that programme. Local fire codes and insurers may impose further restrictions or bans on open-flame roofing.","key_facts":[{"label":"Fuel","value":"Propane (LPG)"},{"label":"Main use","value":"Torch-applied modified bitumen"},{"label":"Key safeguard","value":"Trained operators and post-work fire watch"}],"regions":["Global","North America","Europe"],"aliases":["torch","propane torch","torch-down torch"],"related":["modified-bitumen-roofing","torch-applied-roofing","roofing-kettle","built-up-roofing"],"company":null,"sources":[{"title":"New torch-safety guidelines","url":"https://professionalroofing.net/articles/article/4392","publisher":"Professional Roofing"},{"title":"Roofing torch program reduces fire hazards during modified bitumen application","url":"https://roofingmagazine.com/roofing-torch-program-reduces-fire-hazards-during-modified-bitumen-application/","publisher":"Roofing Magazine"},{"title":"Prevent Roof Fires During Torch-Down Projects","url":"https://roofingmagazine.com/prevent-roof-fires-during-torch-down-projects/","publisher":"Roofing Magazine"}],"country":null},{"slug":"roofing-underlayment","title":"Roofing Underlayment","category":"components","type":"article","summary":"Roofing underlayment is the water-resistant sheet laid over the roof deck or rafters beneath the roof covering, acting as a secondary barrier against water.","body":"Roofing underlayment (in Britain and Ireland usually called underlay, and in Australia often sarking) is a sheet material installed between the roof deck or rafters and the visible roof covering. Shingles, tiles, slates and metal panels are the primary weather barrier; the underlayment is the backup that sheds water driven past them by wind, ice dams or flashing failures, protects the deck during construction, and in some systems contributes to wind resistance.\n\n## Main types\n\n- **Asphalt-saturated felt:** the traditional product, sold in North America as #15 and #30 felt under ASTM D226 Types I and II, with lighter grades under ASTM D4869.\n- **Synthetic underlayment:** woven or spun-bonded polymer sheets that are lighter and more tear-resistant than felt. Products are typically evaluated against code acceptance criteria rather than a felt standard.\n- **Self-adhered membranes:** rubberised or polymer-modified bitumen sheets with a sticky back, used as ice barriers, in valleys and around penetrations, or as full-coverage underlayment.\n- **Vapour-permeable (breather) underlays:** common in the UK and Europe, these resist liquid water but let water vapour escape from the roof space.\n- **Vapour-impermeable underlays (HR):** traditional bitumen-based sheets that block vapour, used with a ventilated loft.\n\n## Installation basics\n\nUnderlayment is laid in horizontal courses starting at the eaves, with each upper course lapping over the one below so water runs outward. At the eaves of a North American shingle roof it goes over the drip edge; at the rakes the drip edge goes over it. On low-slope shingle roofs, codes call for additional laps or double coverage.\n\nIn the UK, underlay is usually draped over the rafters under battens. BS 5534 refers to a nominal 10 mm drape so that water can drain beneath the battens to the gutter.\n\n## Choosing a product\n\nSelection depends on the roof covering, pitch, climate and code. Roof covering manufacturers often specify compatible underlayments, and some coverings, notably metal in hot climates, may need high-temperature-rated products.","key_facts":[{"label":"UK term","value":"Underlay"},{"label":"Australian term","value":"Sarking"},{"label":"US felt standards","value":"ASTM D226, ASTM D4869"},{"label":"UK drape (BS 5534)","value":"Nominal 10 mm"}],"regions":["Global"],"aliases":["underlay","roof underlay","sarking membrane","synthetic underlayment"],"related":["roofing-felt","ice-and-water-shield","vapour-permeable-underlay","drip-edge","roof-sheathing"],"company":null,"sources":[{"title":"Roofing felt","url":"https://en.wikipedia.org/wiki/Roofing_felt","publisher":"Wikipedia"},{"title":"The use of vapour permeable underlays in compliance with BS 5534","url":"https://rcimag.co.uk/sandtoft-blog/the-use-of-vapour-permeable-underlays-in-compliance-with-bs-5534","publisher":"Roofing Cladding & Insulation (RCI) magazine"},{"title":"Roof drip edge code (IRC 2021 R905.2.8.5)","url":"https://www.jaspector.com/codes/irc-2021/ch09-roof-assemblies/roof-drip-edge-code/","publisher":"Jaspector"},{"title":"Batten space ventilation for pitched roofs","url":"https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/LABCW%20Batten%20space%20ventilation%20for%20pitched%20roofs%20V2.pdf","publisher":"LABC Warranty"}],"country":null},{"slug":"roofing-warranty-types","title":"Roofing Warranty Types","category":"installation","type":"article","summary":"Roofing warranties fall into two main groups: manufacturer warranties on materials or systems, and contractor workmanship warranties on installation.","body":"A **roofing warranty** is a written promise about the performance of roofing materials or work, with stated remedies if a covered problem occurs. Warranties differ widely in what they cover, for how long and under what conditions, so the written terms matter more than the headline length. Two main types exist, and many roofs have both.\n\n## Manufacturer warranties\n\n- **Material (product) warranty.** Covers defects in the manufacturer's product, such as premature failure due to manufacturing faults. It usually does not cover installation errors, storm damage beyond the product's rating, or damage from other trades.\n- **Enhanced or system warranty.** Offered when a set of the manufacturer's components is installed together, often by a contractor the manufacturer has credentialed. These may add some labour or workmanship coverage.\n- **Commercial membrane warranties.** For low-slope systems, manufacturers may issue warranties after an inspection of the completed roof, with coverage limits defined in the document.\n\nLong or \"lifetime\" material warranties are commonly **limited** and may be **prorated**, meaning the value of coverage decreases over time after an initial period. A lifetime warranty usually describes how long a claim may be made, not a statement that the product will last that long, and the definition of \"lifetime\" is set in the document itself, for example the period of ownership by the original purchaser.\n\n## Workmanship warranties\n\nA **workmanship warranty** is given by the roofing contractor and covers errors in installation, such as faulty flashing or nailing. Its value depends on the contractor remaining in business. Terms are set by the contractor and by local consumer law.\n\n## Common conditions\n\n- Installation according to the manufacturer's instructions, including nailing patterns.\n- Approved ventilation and compatible components; for example, some building departments note that shingles not approved for unvented attics may lose warranty coverage.\n- Registration within a set period and proof of purchase.\n- Maintenance and prompt reporting of problems.\n- **Transferability** rules for later owners, which often limit coverage or require notice.\n\n## Legal background\n\nStatutory and implied warranties may exist alongside written ones. In the United States, the Magnuson-Moss Warranty Act governs written consumer product warranties. Other countries have their own consumer protection laws.","key_facts":[{"label":"Main types","value":"Manufacturer (material or system) and contractor workmanship"},{"label":"Common features","value":"Limited, may be prorated, may be transferable"},{"label":"Key condition","value":"Installation per manufacturer instructions"}],"regions":["Global"],"aliases":["roof warranty","shingle warranty","workmanship warranty","manufacturer warranty"],"related":["hiring-a-roofer","shingle-nailing-pattern","roof-replacement-process"],"company":null,"sources":[{"title":"Warranty","url":"https://en.wikipedia.org/wiki/Warranty","publisher":"Wikipedia"},{"title":"TBR64 Proper Nailing for Laminated Shingles","url":"https://www.iko.com/na/document/tbr64-proper-nailing-for-laminated-shingles-product-bulletin","publisher":"IKO"},{"title":"Reroofing","url":"https://www.bloomingtonmn.gov/sites/default/files/2023-08/Reroofing.pdf","publisher":"City of Bloomington, Minnesota"},{"title":"CSSB Installation Tips","url":"https://www.cedarbureau.org/wp-content/uploads/2020/04/CSSB-installation-tips.pdf","publisher":"Cedar Shake and Shingle Bureau"}],"country":null},{"slug":"roofing-waste","title":"Roofing Waste and Landfill","type":"article","summary":"Waste generated by roof replacement and construction, its share of construction and demolition debris, and ways to reduce it.","body":"Roofing waste includes old coverings, underlayments, insulation, decking, flashings and fasteners removed during reroofing, plus offcuts and packaging from new installations. Because roofs are replaced several times over a building's life, roofing contributes a steady stream of construction and demolition (C&D) waste.\n\n## Scale\n\nThe US EPA estimated that about 600 million tons of C&D debris were generated in the United States in 2018, and just under 145 million tons went to landfill. Asphalt shingles are one of the materials the EPA tracks in this stream; a 2007 EPA-commissioned estimate put US asphalt shingle waste at about 11 million short tons per year, most of it landfilled.\n\n## Main roofing waste streams\n\n- **Asphalt shingles:** the largest residential stream in North America; recyclable into asphalt pavement where processors exist.\n- **Metal:** aluminium, steel, copper and zinc have scrap value and are usually recycled.\n- **Single-ply membranes:** thermoplastic PVC and TPO can be recycled through programs such as Europe's Roofcollect; EPDM is harder to recycle.\n- **Built-up roofing and modified bitumen:** bulky and often landfilled.\n- **Clay and concrete tile and slate:** durable and often salvaged for reuse or crushed as aggregate.\n- **Wood shakes and decking:** may be reused, chipped or used as fuel, depending on treatment.\n- **Insulation:** some rigid boards can be reused if dry and undamaged.\n\n## Reducing waste\n\n- **Choosing longer-lasting materials**, which means fewer replacements. Published life expectancy estimates range from about 20 years for basic asphalt shingles to 60-150 years for slate.\n- **Recovering rather than replacing**, for example by recoating or overlaying sound low-slope roofs where codes allow.\n- **Salvage and reuse** of tiles, slate and metal.\n- **Source separation on site**, keeping metals, shingles, wood and membranes apart to make recycling practical.\n- **Accurate ordering** and reuse of offcuts.\n\n## Hazardous materials\n\nOlder roofing products may contain asbestos (in some felts, shingles, cement sheets and mastics) or coal tar. These require testing and specialist handling and cannot be recycled with ordinary waste.\n\n## Policy\n\nLandfill fees and bans, construction waste diversion targets and green building credits encourage recycling. Local availability of processors largely determines what is recycled in practice.","key_facts":[{"label":"US C&D debris (2018)","value":"About 600 million tons"},{"label":"US C&D landfilled (2018)","value":"Just under 145 million tons"},{"label":"US shingle waste (2007 estimate)","value":"About 11 million short tons per year"}],"regions":["Global","North America","Europe"],"aliases":["roofing debris","roof tear-off waste","construction waste roofing"],"related":["asphalt-shingle-recycling","metal-roof-recycling","single-ply-membrane-recycling","roof-lifespan-comparison","embodied-carbon-roofing"],"sources":[{"title":"Sustainable Management of Construction and Demolition Materials","url":"https://www.epa.gov/smm/sustainable-management-construction-and-demolition-materials","publisher":"US Environmental Protection Agency"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"InterNACHI's Standard Estimated Life Expectancy Chart for Homes","url":"https://www.nachi.org/life-expectancy.htm","publisher":"InterNACHI"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"roofing-workforce","title":"Roofing Workforce","type":"article","summary":"The people who install and repair roofs, their numbers, pay and outlook, with US Bureau of Labor Statistics data.","body":"The roofing workforce includes roofers who install, repair and replace roofs, along with supervisors, estimators, sheet metal workers, and helpers. Roofing is labour-intensive and physically demanding.\n\n## United States figures\n\nAccording to the US Bureau of Labor Statistics (BLS) Occupational Outlook Handbook:\n\n- **Jobs:** about 166,900 roofer jobs in 2025.\n- **Pay:** a median annual wage of $55,440 (about $26.65 per hour) in May 2025, with the lowest 10 percent earning less than $37,460.\n- **Outlook:** employment projected to grow 5 percent from 2025 to 2035, faster than the average for all occupations, adding about 8,800 jobs, with roughly 12,000 openings per year on average as workers retire or change occupations.\n\n## Nature of the work\n\nBLS describes roofing as physically demanding because it involves climbing, bending, kneeling and heavy lifting. Roofers work outdoors in hot and cold weather, generally avoid working in rain and high wind, and may work overtime in busy summer months. Demand rises sharply after major storms.\n\n## Safety\n\nRoofing has one of the highest fatal injury rates of any occupation in the United States; in 2024 the BLS reported 48.7 deaths per 100,000 full-time equivalent roofers, compared with 3.3 for all workers. Falls cause most of these deaths.\n\n## Training\n\nRoutes into the trade vary by country, from on-the-job training to formal apprenticeships and vocational qualifications. Manufacturer training and product certification programs supplement these.\n\n## Workforce issues\n\nIssues commonly discussed in the trade include:\n\n- Recruiting and retaining workers;\n- Seasonal and weather-dependent work;\n- Safety and heat stress concerns;\n- Need for new skills related to solar installation, cool and green roofs, and energy-efficient roof assemblies.","key_facts":[{"label":"US roofer jobs (2025)","value":"About 166,900"},{"label":"US median pay (May 2025)","value":"$55,440 per year"},{"label":"Projected growth (2025-2035)","value":"5%"},{"label":"Fatal injury rate (2024)","value":"48.7 per 100,000 FTE"}],"regions":["North America","Global"],"aliases":["roofers","roofing labor","roofing trade"],"related":["roofing-fatality-statistics","roofing-market-size","roofing-fall-protection"],"sources":[{"title":"Occupational Outlook Handbook: Roofers","url":"https://www.bls.gov/ooh/construction-and-extraction/roofers.htm","publisher":"US Bureau of Labor Statistics"},{"title":"Rate and number of fatal work injuries in selected occupations","url":"https://www.bls.gov/charts/census-of-fatal-occupational-injuries/rate-and-number-of-fatal-work-injuries-in-selected-occupations.htm","publisher":"US Bureau of Labor Statistics"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"forbidden-city-roofs","title":"Roofs of the Forbidden City","category":"history","type":"place","summary":"The yellow-glazed tiled roofs of Beijing's imperial palace, built 1406-1420, whose colours, forms and ridge figures encode imperial rank.","body":"The Forbidden City in Beijing was the palace of the Ming and Qing emperors and is among the best-preserved groups of traditional timber buildings in the world. Its roofs, almost all covered in glazed yellow tiles, are its defining image.\n\n## History\n\nThe palace was built between 1406 and 1420 under the Ming emperor Zhu Di (the Yongle Emperor). It was the seat of imperial power until 1911, during which 14 Ming and 10 Qing emperors were enthroned. It was inscribed on the UNESCO World Heritage List in 1987. The complex covers about 72 ha (180 acres) and has 980 surviving buildings.\n\n## Roof colour\n\nYellow was the emperor's colour, so nearly every roof is yellow-glazed. There are notable exceptions:\n\n- The **Pavilion of Literary Profundity**, the imperial library, has black tiles; black was linked with water and so with protection against fire.\n- The **crown prince's residences** have green tiles, linked with wood and growth.\n\n## Roof forms\n\nRoof shape was also ranked. The palace includes double-eaved halls such as the Palace of Heavenly Purity and the Palace of Earthly Tranquility, the square Hall of Union with a pyramidal roof, and corner towers with intricate roofs of 72 ridges modelled on famous pavilions in Song dynasty paintings. The Hall of Supreme Harmony is the largest surviving wooden structure in China, about 30 m (98 ft) tall.\n\n## Ridge figures\n\nA procession of glazed figures runs along the hip ridges, led by a man riding a phoenix and ending with a dragon. Minor buildings have three or five. The Hall of Supreme Harmony is the only building in China permitted ten, including a unique tenth figure called the *hangshi*.\n\n## Fire and rebuilding\n\nTimber halls under heavy tile roofs were vulnerable to fire. UNESCO notes that the palace was almost entirely destroyed by fire in 1644 and restored under the Qing. Many halls have been rebuilt or repaired several times, so the roofs seen today represent centuries of maintenance by imperial and later craftsmen.","key_facts":[{"label":"Built","value":"1406-1420"},{"label":"Area","value":"About 72 ha (180 acres)"},{"label":"Surviving buildings","value":"980"},{"label":"UNESCO inscription","value":"1987"}],"regions":["East Asia"],"aliases":["Palace Museum roofs","Imperial Palace Beijing roofs"],"related":["chinese-glazed-roof-tiles","chinese-imperial-roof-figures","hip-roof"],"company":null,"sources":[{"title":"Forbidden City","url":"https://en.wikipedia.org/wiki/Forbidden_City","publisher":"Wikipedia"},{"title":"Imperial Palaces of the Ming and Qing Dynasties in Beijing and Shenyang","url":"https://whc.unesco.org/en/list/439","publisher":"UNESCO World Heritage Centre"},{"title":"Imperial roof decoration","url":"https://en.wikipedia.org/wiki/Imperial_roof_decoration","publisher":"Wikipedia"}],"country":null},{"regions":["Europe"],"company":null,"slug":"troodos-painted-church-roofs","title":"Roofs of the Troodos Painted Churches","category":"world-roofing","type":"place","summary":"Steep timber roofs with flat hooked tiles that cover the Byzantine painted churches of the Troodos mountains in Cyprus, a UNESCO World Heritage site.","aliases":["Painted Churches in the Troodos Region","St Nicholas of the Roof","Agios Nikolaos tis Stegis"],"body":"The Troodos mountains of Cyprus contain a group of small Byzantine churches and monasteries whose wall paintings, from the 11th century onward, are among the finest of their period. They are listed together by UNESCO as the **Painted Churches in the Troodos Region**. Architecturally, they are known for an unusual roof form: steep-pitched timber roofs covered with flat hooked tiles, which in some churches form a second, outer roof over Byzantine masonry domes and vaults.\n\n## The roofs\n\nThe steep timber roof suits a mountain area where traditional houses also have pitched roofs to shed snow, unlike the flatter roofs of the Cypriot plains and coast. Where it covers masonry domes, the outer timber roof serves as a second skin over the vaults beneath. UNESCO notes that the churches' architecture was shaped by Cyprus's geography, history and climate.\n\n## The churches\n\nUNESCO lists ten churches, nine in the Nicosia District and one in the Limassol District. They include:\n\n- **St Nicholas of the Roof** (*Agios Nikolaos tis Stegis*), with 11th-century and Comnenian-era paintings;\n- **Panagia Phorbiotissa** at Nikitari, with important 11th-century iconography;\n- **Panagia tou Arakou**, painted around the time Cyprus passed to Guy de Lusignan;\n- **Ayia Sotira** at Palaichori, with 16th-century paintings of the Cretan school.\n\nPaintings from the 13th, 14th and late 15th centuries survive in several churches, and the start of Venetian rule in 1489 brought Italo-Byzantine influence.\n\n## Protection\n\nThe site received enhanced protection status under the Hague Convention's Second Protocol in November 2010. Keeping the timber roofs and tile coverings sound is part of protecting the painted interiors beneath them.","key_facts":[{"label":"Roof type","value":"Steep timber roofs with flat hooked tiles"},{"label":"Number of churches","value":"Ten (UNESCO)"},{"label":"Paintings","value":"From the 11th century"}],"related":["roofing-in-cyprus","dome","clay-roof-tile","roofing-in-greece"],"sources":[{"title":"Painted Churches in the Troodos Region","url":"https://whc.unesco.org/en/list/351","publisher":"UNESCO World Heritage Centre"},{"title":"The traditional architecture of Cyprus and its features","url":"https://dom.com.cy/en/live/blogs/the-traditional-architecture-of-cyprus-and-its-features/","publisher":"DOM Cyprus"}],"country":null},{"slug":"rooftop-solar-pv","title":"Rooftop Solar PV","type":"article","summary":"Photovoltaic panels mounted on building roofs to generate electricity, and the roofing issues of load, attachment, waterproofing and roof life.","body":"Rooftop solar photovoltaic (PV) systems use panels (modules) mounted on a building's roof to convert sunlight into electricity. Roofs are attractive sites because they are already built, are often unshaded, and are close to where power is used. Rooftop PV ranges from a few panels on a house to large arrays covering warehouse roofs.\n\n## Roofing considerations\n\nInstalling PV turns a roof into a platform for equipment that will stay for decades, so the roof itself becomes part of the system's success.\n\n- **Roof age and condition.** PV modules are typically covered by manufacturer warranties of 20 to 25 years and often keep producing after that. Removing and reinstalling an array to replace a roof partway through its life adds cost, so the US Department of Energy notes that a roof replacement can be a good time to add solar.\n- **Structural capacity.** Panels and racking add weight, and some roofs designed only for their own weight need strengthening. Ballasted systems on flat roofs can add considerably more load than attached systems.\n- **Wind loads.** Arrays experience wind uplift and drag; design pressures depend on location on the roof, with edges and corners most demanding. ASCE 7-16 in the United States added specific provisions for rooftop arrays parallel to the roof.\n- **Waterproofing.** Each attachment point is a potential leak. Flashing details matched to the roof covering are critical.\n- **Fire access.** Many jurisdictions require pathways and setbacks so firefighters can reach and ventilate roofs.\n- **Snow and debris.** Arrays change how snow slides and where debris collects, which can affect gutters and drainage.\n\n## Performance over time\n\nNREL research found a median degradation rate of about 0.5 percent per year, so a typical panel produces roughly 90 percent of its first-year output after 20 years. Rates can be higher in hot climates and on rooftops, likely because of higher operating temperatures.\n\n## Mounting approaches\n\n- **Attached (penetrating) racks** on pitched roofs, bolted through flashed mounts into rafters or deck.\n- **Clamp mounts** on standing seam metal roofs that grip the seams without penetrating the panels.\n- **Ballasted racks** on flat roofs held down by weight.\n- **Building-integrated PV (BIPV)**, where solar tiles, shingles or laminates replace part of the roof covering.\n\n## Urban effects\n\nPanels shade the roof surface below. A simulation of London's 2018 heatwave found that rooftop solar could reduce average outdoor temperatures somewhat (about 0.5 °C), though less than cool roofs in the same study.\n\n## Policy\n\nSeveral jurisdictions encourage or require rooftop solar, sometimes as an alternative to green roofs; for example, a 2015 French law required new buildings in commercial zones to be partly covered with plants or solar panels.","key_facts":[{"label":"Typical module warranty","value":"20-25 years"},{"label":"Median degradation (NREL)","value":"About 0.5% per year"},{"label":"Output after 20 years","value":"Roughly 90% of year one"},{"label":"Main roof concerns","value":"Load, wind uplift, flashing, roof age"}],"regions":["Global"],"aliases":["rooftop solar","solar panels on roofs","roof-mounted PV"],"related":["solar-roof-mounting","building-integrated-photovoltaics","roof-wind-pressure-zones","french-green-roof-law","roof-lifespan-comparison"],"sources":[{"title":"Useful Life and Degradation of PV Panels (STAT FAQs Part 2)","url":"https://www.nrel.gov/state-local-tribal/blog/posts/stat-faqs-part2-lifetime-of-pv-panels.html","publisher":"National Renewable Energy Laboratory"},{"title":"Homeowner's Guide to Going Solar","url":"https://www.energy.gov/eere/solar/homeowners-guide-going-solar","publisher":"US Department of Energy"},{"title":"Photovoltaic mounting system","url":"https://en.wikipedia.org/wiki/Photovoltaic_mounting_system","publisher":"Wikipedia"},{"title":"ASCE 7-16 Wind for PV Parallel to Roof (SEAOC 2016 Convention presentation)","url":"https://www.seia.org/sites/default/files/Cain%20and%20Banks%20ASCE%207-16%20Wind%20for%20PV%20Parallel%20to%20Roof%20Presentation%20-%20SEAOC%202016%20Convention.pdf","publisher":"Solar Energy Industries Association"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"rooftop-solar-water-heater","title":"Rooftop Solar Water Heater","category":"climate-sustainability","type":"article","regions":["Middle East","Global"],"company":null,"summary":"A roof-mounted solar collector and tank that heats domestic water; Israel made them mandatory on most new buildings in 1980.","aliases":["solar water heater","dud shemesh","solar boiler","solar hot water system","thermosiphon solar heater"],"body":"A rooftop solar water heater uses a collector panel, usually set on a flat or pitched roof, to warm water that is stored in an insulated tank for household use. Many simple systems place the tank above the collector so heated water rises into it naturally (thermosiphon), which is why the familiar rooftop combination of panel and horizontal cylinder appears on so many flat roofs around the Mediterranean and Middle East. In Israel the system is called a *dud shemesh* (\"sun boiler\").\n\n## Israel: the 1980 solar building law\n\nIsrael's experience is well documented. During a fuel shortage in the early 1950s, when water heating was banned in daytime hours, engineer Levi Yissar built a prototype and in 1953 founded NerYah, the country's first commercial solar water-heater maker. By 1967 about one household in twenty heated water by sun, but cheap oil then slowed sales. After the 1970s oil crisis, Harry Zvi Tabor developed the prototype of the heater now found on most Israeli roofs.\n\nIn 1980 the Knesset required solar water heaters on new homes, widely cited as the first solar building obligation in the world. As summarised by solarthermalworld.org, the rule applies to new buildings under 27 m (89 ft), about 8-9 floors, other than industrial and trade buildings and hospitals; it was widened in 2012 so that taller new residential buildings must serve the top seven floors. Minimum tank sizes are 60 L (16 US gal) for a one-room flat, 120 L (32 US gal) for two or three rooms and 150 L (40 US gal) for larger flats. Over 90% of Israeli homes now use solar water heating, which the energy ministry estimates saves about 2 million barrels of oil a year.\n\n## Roofing considerations\n\n- **Load:** a full tank adds a concentrated load; frames must be fixed to the structure, not just the waterproofing.\n- **Penetrations and fixings:** frames and pipes cross the roof membrane, so flashings or raised plinths are needed to keep the waterproofing intact.\n- **Space:** on apartment blocks, many heaters compete for limited roof area, which is one reason Israel's original rule exempted tall towers.\n- **Maintenance access:** collectors and tanks need clear access routes for servicing and for re-roofing.\n\n## Beyond Israel\n\nPhotovoltaic panels increasingly share the same roofs: in 2023 Israel began requiring rooftop PV on all new commercial buildings, citing the lack of land for ground-mounted solar parks.\n## Sources and gaps\n\nComparable mandates and adoption figures for neighbouring countries: published information is limited.","key_facts":[{"label":"Israeli mandate","value":"1980 (extended 2012)"},{"label":"Height threshold","value":"27 m (89 ft) for the original rule"},{"label":"Israeli homes using solar water heating","value":"Over 90%"},{"label":"Minimum tank, 2-3 room flat","value":"120 L (32 US gal)"},{"label":"First Israeli manufacturer","value":"NerYah, 1953"}],"related":["roofing-in-israel","roofing-in-palestine","rooftop-solar-pv","solar-roof-mounting","flat-roof","roofing-in-jordan"],"sources":[{"title":"Solar power in Israel","url":"https://en.wikipedia.org/wiki/Solar_power_in_Israel","publisher":"Wikipedia"},{"title":"Israel: Front runner in Solar Building Code with Strong Impact on Market","url":"https://solarthermalworld.org/news/israel-front-runner-solar-building-code-strong-impact-market/","publisher":"solarthermalworld.org"}],"country":null},{"slug":"rosin-paper-slip-sheet","title":"Rosin Paper Slip Sheet","category":"components","type":"term","summary":"A rosin paper slip sheet is a layer of rosin-sized building paper laid under copper and other seamed metal roofs so the metal can slide over the underlayment.","body":"Seamed metal roofs, especially copper, are traditionally installed over an asphalt-saturated felt underlayment. On a hot roof, asphalt softens and can bond to the underside of the metal. Once bonded, the pans cannot expand and contract freely, which leads to buckling and fatigue cracking. A slip sheet of rosin-sized building paper laid over the felt prevents this bonding.\n\n## Specification\n\nCopper roofing guidance in the United States commonly calls for:\n\n- Asphalt-saturated felt of at least 30 lb per 100 sq ft (for example ASTM D226 Type II, No. 30), lapped and fixed.\n- Over it, rosin-sized building paper of at least 4 lb per 100 sq ft, lapped about 4 in (100 mm).\n- The slip sheet must fully separate the felt from the copper; wet slip sheet should be replaced before metal is laid.\n\n## Why rosin paper\n\nRosin-sized paper is inexpensive, smooth and does not stick to metal or asphalt at roof temperatures. It is used under copper, terne-coated stainless, zinc and other hand-seamed roofs, as well as under some flashings.\n\n## Modern variations\n\nUnderlayment products have diversified, and metal manufacturers' instructions should be followed for compatible layers. Zinc and lead roofs in Europe often use drainage mats or ventilated decks, mainly to control underside condensation.\n\n## Installation tips\n\nThe paper should be laid smooth, without wrinkles that would telegraph through soft metal such as copper. It is fastened only enough to hold it in place until the metal pans and cleats are installed, and work should be planned so that exposed paper is covered before rain. Because the paper is a separation layer, not a waterproofing layer, the felt or other underlayment beneath it remains the secondary water barrier.","key_facts":[{"label":"Typical weight","value":"Minimum 4 lb per 100 sq ft"},{"label":"Laid over","value":"30 lb asphalt-saturated felt"},{"label":"Purpose","value":"Prevent metal bonding to underlayment"}],"regions":["North America","Global"],"aliases":["slip sheet","rosin paper","red rosin paper","building paper slip sheet"],"related":["copper-roofing","thermal-movement-in-metal-roofs","ventilation-under-metal-roofs","flat-seam-roofing"],"company":null,"sources":[{"title":"8.1. Special Roofing Design and Installation Considerations","url":"https://copper.org/applications/architecture/arch_dhb/arch-details/roofing","publisher":"Copper Development Association"},{"title":"Section 07 61 16 Sheet Metal Roofing (VA master specification)","url":"https://www.wbdg.org/FFC/VA/VANCAS/VANCA076116.pdf","publisher":"Whole Building Design Guide / U.S. Department of Veterans Affairs"},{"title":"Section 07 61 13 Standing Seam Metal Roof (design requirements)","url":"https://designconstruct.cufo.columbia.edu/sites/designconstruct.cufo.columbia.edu/files/content/Design%20Requirements/TMP%20SECTION%2007%2061%2013%20-%20STANDING%20SEAM%20METAL%20ROOF.pdf","publisher":"Columbia University Facilities"}],"country":null},{"slug":"royal-palaces-of-abomey","title":"Royal Palaces of Abomey","type":"place","summary":"Earth-walled palaces of the Dahomey kings in Abomey, Benin, roofed with straw and sheet metal and decorated with painted bas-reliefs.","body":"The Royal Palaces of Abomey, in southern Benin, are the seat of the kingdom of Dahomey, whose twelve kings ruled from 1625 to 1900. The site covers 47 ha (about 116 acres) and contains ten palaces within a cob-walled enclosure, with King Akaba's palace standing separately. It was inscribed on the UNESCO World Heritage List in 1985.\n\n## Layout\n\nThe palaces were added successively, some side by side and some superimposed, following the order of succession. Each is arranged around three courtyards: an outer, an inner and a private court.\n\n## Materials\n\nUNESCO lists the traditional materials as laterite earth, water, wood and straw. Earth was used for foundations, floors and raised structures, and walls averaged about 0.5 m (20 in) thick, which kept rooms cool. Timbers included palm, bamboo, iroko and mahogany. The roofs were covered with straw and, in later periods, sheet metal.\n\n## Bas-reliefs\n\nThe palace walls carry polychrome bas-reliefs, modelled from termite-mound earth mixed with palm oil and coloured with plant and mineral pigments. In the absence of written records they served as a chronicle of military victories, myths and rituals. Many originals are now in the museum, with replicas on the walls.\n\n## Damage and loss\n\n- **Fire, 1890s.** King Béhanzin ordered the city and palaces burned in the face of French conquest (sources give 1892 or 1894).\n- **Tornado, 15 March 1984.** A tornado damaged the royal enclosure and museum buildings, including the portico of King Guézo and the king's tomb.\n- **Bushfire, 21 January 2009.** Many buildings were destroyed, including the tombs of Kings Agonglo and Guézo.\n\nRoofs are the most vulnerable part of such a complex: straw burns easily and lifts in high winds, and failed roofs quickly expose earth walls and reliefs to rain.\n\n## Conservation\n\nThe site was on the List of World Heritage in Danger from 1985 to 2007. A 1995 inventory supported by the World Heritage Centre mapped 184 components, more than half of which have since been restored to accepted standards. The Getty Conservation Institute has worked on the bas-reliefs since 1993. A buffer zone has been protected by urban-planning rules since 2006, and Benin's Law No. 2007-20 adds legal protection. The Abomey Historical Museum, founded in 1943, occupies the palaces of Guézo and Glèlè.","key_facts":[{"label":"Location","value":"Abomey, Benin"},{"label":"Period","value":"1625-1900 (twelve kings)"},{"label":"Area","value":"47 ha (116 acres)"},{"label":"Roofs","value":"Straw and sheet metal"},{"label":"Walls","value":"Earth, about 0.5 m (20 in) thick"},{"label":"UNESCO","value":"Inscribed 1985; in danger 1985-2007"}],"regions":["Africa"],"aliases":["Abomey palaces","Palais royaux d'Abomey","Dahomey royal palaces"],"related":["roofing-in-benin","thatch","corrugated-iron","roofing-in-west-africa"],"sources":[{"title":"Royal Palaces of Abomey","url":"https://whc.unesco.org/en/list/323/","publisher":"UNESCO World Heritage Centre"},{"title":"Royal Palaces of Abomey","url":"https://en.wikipedia.org/wiki/Royal_Palaces_of_Abomey","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"rubber-shingle","title":"Rubber Shingle","type":"term","summary":"A roofing shingle made largely from recycled rubber, often from vehicle tyres, moulded to look like slate or wood shake.","body":"A rubber shingle is a roofing unit made mainly from recycled rubber, commonly ground vehicle tyres, mixed with binders, fillers and pigments and moulded to look like slate or wood shakes. Some products use EPDM rubber or blends of rubber and plastic. They form part of the wider family of synthetic or composite roofing.\n\n## Characteristics\n\n- **Recycled content**: rubber shingles give a use to scrap tyres, which are a large waste stream. Manufacturers often market their recycled content as an environmental benefit.\n- **Durability**: shake-style rubber shingles are described as resistant to rot, curling and cracking, and as not absorbing moisture.\n- **Impact**: rubber's flexibility lets it absorb hail impacts, and many products are rated UL 2218 Class 4.\n- **Weight**: light compared with stone or tile, in the same general range as other synthetic slates, about 200-350 lb per square (10-17 kg/m²).\n\n## Concerns\n\n- **Fire**: rubber is combustible; fire ratings depend on the product and on underlayment, and buyers in wildfire-prone regions should check the assembly rating.\n- **Appearance**: colours can fade with UV exposure, and some products look less convincing close up than natural materials.\n- **Track record**: many products are relatively new, so long-term performance data are limited.\n\n## Installation\n\nRubber shingles are generally nailed to a solid deck with corrosion-resistant nails in the same way as synthetic slate, following the manufacturer's spacing to allow for thermal movement. Many can be cut with a utility knife.\n\n## Related products\n\nRubber is also used in flat sheet form as EPDM membranes for low-slope roofs; these are a different product from rubber shingles for pitched roofs.\n","key_facts":[{"label":"Main material","value":"Recycled rubber (often tyres), EPDM blends"},{"label":"Typical impact rating","value":"UL 2218 Class 4 (many products)"},{"label":"Weight","value":"About 200-350 lb per square (10-17 kg/m²)"}],"regions":["North America","Global"],"aliases":["recycled rubber shingle","rubber slate","rubber shake","tyre rubber roofing"],"related":["synthetic-slate","synthetic-shake","epdm-roofing","impact-resistant-shingle"],"sources":[{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Natural Slate & Synthetic Tile Roofing: Installation Fundamentals, Headlap & Fastening","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/metal-tile-slate-steep-slope-systems/slate-synthetic-tile-roofing","publisher":"Open Exam Prep"}],"category":"materials","company":null,"country":null},{"slug":"ruka","title":"Ruka (Mapuche House)","category":"world-roofing","type":"article","summary":"Traditional Mapuche house of Chile and Argentina: a timber frame thatched with straw or reeds, with one east-facing door and a central hearth.","body":"The *ruka* (also *ruca*) is the traditional house of the Mapuche people of south-central Chile and adjacent Argentina; *ruka* means \"house\" in Mapudungun. It is a single large room under a roof thatched with straw, reeds or rushes, and was the main dwelling of the extended family.\n\n## Form and size\n\nRukas were originally round with a conical roof, and later also oval, rectangular or square. The Museo Chileno de Arte Precolombino describes rectangular, circular and elliptical rukas of various sizes, most often with a strong frame of oak (*roble*, *Nothofagus*) timber. Wikipedia gives a typical floor area of about 120 to 240 m² (1,300 to 2,600 sq ft). Walls are of coligüe cane or timber poles reinforced with posts inside.\n\n## Roof\n\nThe roof, and sometimes the walls, are covered with bundles of straw or with rushes such as tule (*Schoenoplectus acutus*) and *junquillo*. The museum notes that this thick vegetable covering insulates against heat and cold and keeps out rain. Materials depend on what grows nearby.\n\n## Orientation and interior\n\nA ruka has no windows and a single main entrance facing east, towards the rising sun and the Puelmapu, the eastern lands associated with the deities; a small secondary door to the west is possible. At the centre is a hearth (*kütralwe*) that is kept burning for cooking, light and heat. Smoke darkens the walls over time, forming a protective layer. Beds line the walls and food and tools hang from the roof structure.\n\n## Communal building\n\nRukas were built collectively, in a work tradition called *rukatun* or *rukan*, and the completion was celebrated with food and dancing, including masked dances (*kollong*).\n\n## Today\n\nThe museum notes that traditional ruka building has largely fallen out of everyday use and that most Mapuche communities now live in Western-style houses, though their layout often recalls the ruka. The form has also inspired modern Mapuche housing, such as a 2011 project in La Pincoya, Huechuraba (Santiago), whose main doors face the rising sun and whose facades use a double skin of coligüe cane.","key_facts":[{"label":"People","value":"Mapuche"},{"label":"Countries","value":"Chile, Argentina"},{"label":"Roof","value":"Straw, reed or rush thatch"},{"label":"Frame","value":"Oak (roble) or other local timber"},{"label":"Entrance","value":"Single main door facing east"}],"regions":["Latin America"],"aliases":["ruca","Mapuche house"],"related":["thatch","roofing-in-chile","roofing-in-argentina","roofing-in-argentina-and-chile"],"company":null,"sources":[{"title":"Ruka (house type)","url":"https://en.wikipedia.org/wiki/Ruka_(house_type)","publisher":"Wikipedia"},{"title":"Patrón de asentamiento - Mapuche","url":"https://chileprecolombino.cl/?p=215","publisher":"Museo Chileno de Arte Precolombino"},{"title":"Viviendas mapuche en La Pincoya (Cristián Undurraga, 2011)","url":"https://revistas.unc.edu.ar/index.php/estructuras/article/download/43421/43393/169305","publisher":"Universidad Nacional de Córdoba"}],"country":null},{"slug":"rumah-gadang","title":"Rumah Gadang","type":"article","summary":"The traditional Minangkabau house of West Sumatra, Indonesia, known for its curved, horn-like gonjong roof peaks thatched with palm fibre.","body":"The *rumah gadang* (\"big house\") is the traditional family house of the Minangkabau people of West Sumatra, Indonesia. Its roof is the most famous part: a sweeping, saddle-shaped form whose gable ends rise into sharp points called *gonjong*, which are said to recall the horns of a water buffalo.\n\n## The gonjong roof\n\nThe roof has multiple tiered, upswept gables. It is built with truss and cross-beam construction from many small battens and rafters that together produce the curved profile. Unlike some neighbouring traditions, such as Batak Toba houses where the roof itself forms the living space, the Minangkabau roof sits on conventional walls.\n\nThe points are made of thatch bound with decorative metal and drawn up into spires. The buffalo-horn reading connects to a legend about a contest between two water buffaloes from which the Minangkabau name is thought to come; the upward peaks are also described as reaching toward God.\n\n## Ijuk thatch\n\nThe traditional covering is *ijuk*, the black fibre of the sugar palm, laid in bundles that follow the curves of the roof. It is regarded as one of the toughest thatching materials available and is said to last up to a century. Today many houses use corrugated iron instead of thatch, which keeps the silhouette but changes its texture and acoustics.\n\n## Society and the house\n\nMinangkabau society is matrilineal. The house belongs to the women who live in it and passes from mother to daughter, while the senior male relatives of the lineage (*ninik mamak*) are responsible for building and maintaining it. A rumah gadang is ideally accompanied by *rangkiang*, raised rice barns with the same horned roofs.\n\n## Landmark example\n\nThe Pagaruyung Palace (*Istano Basa*) is the largest and most elaborate example of the style. Unlike an ordinary rumah gadang, it is built on three levels. The gonjong roofline has become a widely recognised emblem of Minangkabau identity.","key_facts":[{"label":"People","value":"Minangkabau, West Sumatra, Indonesia"},{"label":"Roof form","value":"Curved multi-gabled roof with gonjong peaks"},{"label":"Traditional covering","value":"Ijuk (sugar palm fibre) thatch"},{"label":"Modern covering","value":"Often corrugated iron"},{"label":"Largest example","value":"Pagaruyung Palace (Istano Basa)"}],"regions":["Southeast Asia"],"aliases":["Rumah bagonjong","Minangkabau house","Gonjong roof"],"related":["tongkonan","roofing-in-southeast-asia","thatch","gable-roof"],"sources":[{"title":"Rumah gadang","url":"https://en.wikipedia.org/wiki/Rumah_gadang","publisher":"Wikipedia"},{"title":"Minangkabau architecture","url":"https://en.wikipedia.org/wiki/Minangkabau_architecture","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"ruukki","title":"Ruukki","category":"manufacturers","type":"company","summary":"Ruukki is the Finnish steel building-products brand of Rautaruukki, owned by Sweden's SSAB since 2014, supplying steel roofing across northern and eastern Europe.","body":"Ruukki is the marketing name of the Finnish company Rautaruukki Oyj, whose Ruukki Construction business supplies steel roofing, wall cladding and building components. Rautaruukki was founded by the Finnish government in 1960 to supply steel to the country's heavy industry. The state gradually reduced its shareholding after a partial privatisation in 1994. In 2014 the Swedish steelmaker SSAB acquired Rautaruukki for about EUR 1.1 billion, and Ruukki Construction is now a subsidiary of SSAB.\n\n## Parent company\n\nSSAB was formed on 1 January 1978 by the merger of three Swedish steelworks, Domnarvet, Norrbottens Jarnverk and Oxelosund, and is headquartered in Stockholm. It listed on the Stockholm Stock Exchange in 1989. The Rautaruukki purchase added about 2.6 million tonnes of annual steel capacity. SSAB is also known for its work on fossil-free steel made with hydrogen, delivering its first such steel in 2021.\n\n## Roofing products\n\nRuukki Construction is based in Helsinki and serves homeowners and roofing professionals. Its range includes steel roofing sheets and other roofing products for homeowners and professional roofers, along with building components for commercial construction. Steel roofing is a common choice for houses in Finland, Sweden, the Baltic states and much of eastern Europe.\n\n## Markets\n\nRuukki operates country websites in about 20 markets, including Finland, Sweden, Norway, the Baltic states, Poland, Czech Republic, Slovakia, Hungary, Romania, Bulgaria, Croatia, Germany, France, the Netherlands, the United Kingdom, Ukraine, Moldova, Kazakhstan and Azerbaijan. Steel roofing is widely used on houses in the Nordic and Baltic countries. Ruukki's footer address is Panuntie 11 in Helsinki.","key_facts":[{"label":"Rautaruukki founded","value":"1960 (Finnish state)"},{"label":"Base","value":"Helsinki, Finland"},{"label":"Parent","value":"SSAB (since 2014)"},{"label":"Products","value":"Steel roofing and building components"}],"regions":["Europe"],"aliases":["Rautaruukki","Ruukki Construction"],"related":["metal-roof-tiles","standing-seam-metal-roof"],"company":{"founded":"1960","headquarters":"Helsinki, Finland","website":"https://www.ruukki.com","parent":"SSAB","known_for":["Steel roofing sheets","Steel building components"]},"sources":[{"title":"Rautaruukki","url":"https://en.wikipedia.org/wiki/Rautaruukki","publisher":"Wikipedia"},{"title":"SSAB","url":"https://en.wikipedia.org/wiki/SSAB","publisher":"Wikipedia"},{"title":"Ruukki","url":"https://www.ruukki.com/","publisher":"Ruukki Construction"}],"country":null},{"slug":"sagging-roof-deck","title":"Sagging Roof Deck","category":"problems-maintenance","type":"article","summary":"A visible dip or wave in a roof plane caused by deflecting sheathing, rafters, trusses or ridge, from overload, decay or inadequate framing.","body":"A sagging roof deck is any noticeable downward deflection in the roof plane. It can range from slight dips between rafters, sometimes called a wavy or \"hungry horse\" look, to a pronounced swayback along the ridge. Some sag is a cosmetic sign of age; other cases indicate a structural problem that needs prompt attention.\n\n## Types and causes\n\n- **Sag between framing members.** Thin sheathing panels or boards spanning too far between rafters or trusses, or panels installed without the recommended edge clips or gaps, can deflect, especially when wet. Moisture from a damp attic weakens wood-based panels.\n- **Sagging rafters.** Undersized or over-spanned rafters, notching, missing collar ties or purlin supports, and long-term creep of timber under load cause the rafter line to dip.\n- **Ridge sag.** A ridge board or beam that is not properly supported, or rafters that push outward and spread the walls, causes the ridge to drop.\n- **Added weight.** Multiple layers of reroofing, heavy materials such as tile or slate on framing not designed for them, rooftop equipment, or heavy snow and ice.\n- **Decay.** Long-term leaks or condensation cause rot in sheathing, rafter ends, wall plates or the ridge.\n- **Truss damage** from cutting or altering engineered trusses during renovations.\n\n## Inspection\n\nFrom outside, sighting along the ridge and across slopes in low-angle light shows dips and waves. In the attic, the inspector looks for cracked or split rafters, sagging between supports, separation at the ridge, staining or soft wood, and walls that lean outward at the top. Probing with a screwdriver identifies rot. A level or string line measures deflection.\n\n## Remedies\n\nMinor sheathing dips are often corrected during reroofing by replacing damaged panels and adding blocking or clips. Rafter and ridge problems may need sistering new members alongside old ones, adding purlins, struts or collar ties, or installing a supported ridge beam. Any change to structural framing should be designed or checked by a qualified person and comply with local building codes. Stopping leaks and attic moisture problems is part of every lasting repair.","key_facts":[{"label":"Warning signs","value":"Swayback ridge, dips between rafters, outward-leaning walls"},{"label":"Common causes","value":"Over-spanning, added weight, decay, altered trusses"},{"label":"Typical repairs","value":"New sheathing, sistered rafters, purlins, ridge support"}],"regions":["Global"],"aliases":["sagging roof","roof deflection","swayback roof"],"related":["roof-deck","rafter","roof-truss","wood-rot","attic-condensation","repair-vs-replace"],"company":null,"sources":[{"title":"Roof rafter & decking sagging","url":"https://inspectapedia.com/structure/Sagging-Roof-Rafter-Repair.php","publisher":"InspectAPedia"},{"title":"Controlling Rafter Deflection: Knee Walls, Purlins and Collar Ties (as Braces)","url":"https://www.homeinspector.org/?p=13285","publisher":"ASHI Reporter"},{"title":"Why Your Roof Is Sagging, and What To Do About It","url":"https://norfolkdailynews.com/online_features/press_releases/roofs-for-life-bradentons-skilled-roofers/article_e5de231f-8022-50ca-ba55-86c876eade56.html","publisher":"Norfolk Daily News"}],"country":null},{"slug":"sago-palm-thatch","title":"Sago Palm Thatch","category":"materials","type":"term","summary":"Roof thatch made from sago palm (Metroxylon) leaves, used across Melanesia; called natangura in Vanuatu.","body":"Sago palm thatch is roofing made from the leaves of sago palms of the genus *Metroxylon*. It is one of the main traditional roof coverings of Melanesia, including Papua New Guinea, the Solomon Islands and Vanuatu, where it is known in Bislama as *natangura* (also spelled natangora).\n\n## Species and uses\n\nBotanist John Dowe's study of sago palms in Vanuatu and the Solomon Islands names *Metroxylon salomonense* and *M. warburgii* and records that the palms are used throughout the region as house-building material: the leaves provide a durable thatch, while the leaf stalks are used for supports and beams. In the Sepik region of Papua New Guinea, Abelam ceremonial houses (see [haus tambaran](/haus-tambaran)) are thatched with sago palm fronds.\n\n## In use today\n\nSago thatch remains common where palms grow near villages and imported sheet is costly to transport. In Vanuatu's 2010 Household Income and Expenditure Survey, 41.7% of household records listed natangura as the main roof of the main house, close to the 49.2% with iron roofs. After Cyclone Pam in March 2015, an assessment by REACH found corrugated iron and natangura to be the most common roof materials before the storm, and the cyclone and a following drought caused shortages of thatching material.\n\n## Characteristics\n\nLike other [palm thatch](/palm-thatch), sago thatch is light, cool and locally renewable, and is laid steeply to shed tropical rain. It needs periodic renewal, and its supply depends on palm stands that can be damaged by cyclones and drought.\n## Sources and gaps\n\nFigures for its service life in Melanesia: published information is limited.","key_facts":[{"label":"Plant","value":"Sago palm, Metroxylon spp."},{"label":"Regions","value":"Papua New Guinea, Solomon Islands, Vanuatu"},{"label":"Local name","value":"Natangura (Vanuatu)"},{"label":"Share in Vanuatu","value":"41.7% of HIES 2010 household records"}],"regions":["Oceania"],"aliases":["Natangura","Natangora","Sago thatch","Sago leaf roofing"],"related":["palm-thatch","thatch","roofing-in-vanuatu","roofing-in-the-solomon-islands","roofing-in-papua-new-guinea","nakamal","haus-tambaran","ijuk-thatch"],"company":null,"sources":[{"title":"Sago palms, Metroxylon (Arecaceae) in Vanuatu and the Solomon Islands (Dowe, 2002)","url":"https://researchonline.jcu.edu.au/14376/","publisher":"James Cook University"},{"title":"Vanuatu HIES 2010, roof material (H4)","url":"https://catalog.ihsn.org/catalog/8492/variable/F2/V14?name=H4","publisher":"IHSN Survey Catalog"},{"title":"Shelter and settlements assessment key findings, May 2015","url":"https://repository.impact-initiatives.org/document/impact/738bacfa/reach_vut_factsheets_shelter_and_settlements_assessment_key_findings_may_2015_v2.pdf","publisher":"REACH / IMPACT Initiatives"},{"title":"Abelam - Settlements","url":"https://www.everyculture.com/Oceania/Abelam-Settlements.html","publisher":"Countries and Their Cultures"}],"country":null},{"slug":"sahelian-earthen-roofs","title":"Sahelian Earthen Roofs","type":"article","summary":"Flat or slightly domed roofs of timber and mud used across the Sudano-Sahelian belt of West Africa, from Mali to northern Nigeria.","body":"Across the Sudano-Sahelian belt of West Africa, from Senegal and Mali through Burkina Faso and Niger to northern Nigeria, the traditional roof of town houses, granaries and mosques is made of earth laid on timber. These roofs are flat or slightly domed and are part of an architecture in which walls, roofs and decoration are all formed from mud.\n\n## Construction\n\nThe Sudano-Sahelian building technique is known as *banco*: wet earth, often mixed with organic material, is cast into rectangular sun-dried bricks or applied as plaster. For a roof:\n\n1. Timber members span between walls. The availability of wood shapes the design; the eastern Hausa style uses much more timber than the western style.\n2. Smaller sticks, mats or palm ribs are laid across them.\n3. Layers of earth are spread and compacted on top, sloped toward waterspouts.\n\nMosque prayer halls use rows of pillars or walls to carry flat or slightly domed roofs of wood and mud. The Great Mosque of Zaria in Nigeria uses shallow domes carried on parabolic arches.\n\n## Water and maintenance\n\nEarth roofs perform well in the long dry season but are vulnerable during the short, intense rainy season. Projecting spouts, often ceramic or timber, throw water away from walls. Wooden stakes (*toron*) built into walls in the western style serve as scaffolding for regular replastering, which is carried out with community help.\n\n## Comfort\n\nThick earth roofs and walls store heat during the day and release it at night, smoothing the large daily temperature swings of the Sahel.\n\n## Change\n\nCorrugated metal roofs have spread widely because they are fast to build and need little upkeep, but they are hot and depend on imported materials. Earth-only alternatives such as the Nubian vault, promoted in the region since 2000, aim to keep the thermal benefits of earth while avoiding scarce timber.\n\n## Heritage\n\nDjenné and Timbuktu in Mali and Agadez in Niger are major heritage centres of the tradition, each with earthen mosques and houses that still depend on routine maintenance to survive.","key_facts":[{"label":"Region","value":"Sudano-Sahelian West Africa"},{"label":"Technique","value":"Banco (wet earth, sun-dried bricks)"},{"label":"Roof form","value":"Flat or slightly domed, earth on timber"},{"label":"Maintenance","value":"Regular communal replastering"}],"regions":["Africa"],"aliases":["Banco roof","Mud roof","Sudano-Sahelian roof"],"related":["djenne-earthen-architecture","nubian-vault","roofing-in-west-africa","flat-roof","mud-roof"],"sources":[{"title":"Sudano-Sahelian architecture","url":"https://en.wikipedia.org/wiki/Sudano-Sahelian_architecture","publisher":"Wikipedia"},{"title":"Nubian vault","url":"https://en.wikipedia.org/wiki/Nubian_vault","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"saint-gobain","title":"Saint-Gobain","category":"manufacturers","type":"company","summary":"Saint-Gobain is a French building-materials group founded in 1665 whose roofing interests include CertainTeed and Building Products of Canada.","body":"Saint-Gobain is one of the world's largest building-materials companies, headquartered at La Defense near Paris. It was founded in 1665 as the Manufacture royale de glaces de miroirs, a royal mirror-glass works established under letters patent from the French minister Jean-Baptiste Colbert. It became a public limited company independent of the state in 1830 and was re-privatised in 1987.\n\n## Roofing activities\n\nSaint-Gobain does not trade under its own name as a roofing manufacturer, but owns roofing businesses through subsidiaries:\n\n- **CertainTeed**, founded in 1904 as the General Roofing Manufacturing Company and now a wholly owned Saint-Gobain subsidiary, is a major North American producer of asphalt shingles, as well as siding, insulation, gypsum and ceilings.\n- **Building Products of Canada (BP Canada)**, a producer of asphalt shingles, underlayments and low-slope membranes in Canada with more than a century of history, whose acquisition by Saint-Gobain has been completed.\n- Saint-Gobain's Construction Products segment includes an Exterior Products business area that manufactures roofing alongside other exterior products.\n\nThe group was previously linked to clay roof tiles through Terreal, formed as Saint-Gobain Terreal in 2002 and spun off the following year, and through CertainTeed's 1989 purchase of Ludowici.\n\n## Other businesses\n\nSaint-Gobain's construction-related brands include Isover (glass-wool insulation, founded 1937), Gyproc and Weber, and it acquired the UK plasterboard maker BPB in 2005 and the US construction-chemicals firm GCP Applied Technologies in 2021. In 2024 it agreed to acquire the Australian building-products company CSR. Saint-Gobain is listed on the Paris stock exchange. Its head office building, Les Miroirs, has served since 1981.","key_facts":[{"label":"Founded","value":"1665, Paris"},{"label":"Headquarters","value":"La Defense / Courbevoie, France"},{"label":"Roofing subsidiaries","value":"CertainTeed, Building Products of Canada"}],"regions":["Global","Europe","North America"],"aliases":["Compagnie de Saint-Gobain"],"related":["certainteed","terreal","ludowici","asphalt-shingle"],"company":{"founded":"1665","headquarters":"Courbevoie (La Defense), France","website":"https://www.saint-gobain.com","known_for":["Glass","Insulation (Isover)","Roofing via CertainTeed"]},"sources":[{"title":"Saint-Gobain","url":"https://en.wikipedia.org/wiki/Saint-Gobain","publisher":"Wikipedia"},{"title":"CertainTeed","url":"https://en.wikipedia.org/wiki/CertainTeed","publisher":"Wikipedia"},{"title":"BP Canada","url":"https://www.bpcan.com/","publisher":"Building Products of Canada"}],"country":null},{"slug":"saltbox-roof","title":"Saltbox and Catslide Roof","category":"roof-forms","type":"article","summary":"A saltbox roof is an asymmetric gable roof with one long slope reaching low at the back; a catslide is a roof that extends below the main eave line.","body":"A saltbox roof is a gable roof with unequal sides: a short slope on one side and a much longer slope on the other that sweeps down toward the ground. The classic saltbox house has two storeys at the front and one at the back, so the rear roof covers both the main house and a lower rear section. The name comes from the resemblance to a slant-lidded wooden box once used to store salt.\n\n## Saltbox houses\n\nThe saltbox is a traditional American colonial form associated with New England. Early examples were timber-framed and usually had a central chimney. The shape probably originated in Kent and East Anglia in England and arrived with early Puritan settlers. It developed as an inexpensive way to enlarge a house by adding a rear section under an extension of the main roof. Saltbox houses were most common in Massachusetts, the Connecticut River valley and Ohio's Western Reserve from about 1620 to the mid-1700s, and continued to be built until about 1820. Surviving examples include the Thomas Hawley House in Monroe, Connecticut (c. 1651) and the John Adams Birthplace in Quincy, Massachusetts (c. 1667-1670).\n\n## Catslide roofs\n\nA catslide is any roof that continues down below the level of the main eaves, typically over a rear or side outshot. The term came from 17th-century England, where it described such secondary roofs, and is still used in British building conservation. In the US it is used particularly for roofs in the Southeast from colonial times to about 1910, often covering a porch.\n\n## Practical notes\n\n- The long, low slope sheds snow and wind well and can face prevailing weather.\n- Where the pitch changes between the main roof and the extension, a \"break\" in slope needs care to drain and flash properly.\n- Long rafters or a change of framing may be needed to span the extended slope.\n- Modern saltbox designs use the long slope for solar panels and the tall front wall for windows.","key_facts":[{"label":"Shape","value":"Asymmetric gable, one long low side"},{"label":"Peak period (New England)","value":"c. 1620 to mid-1700s"},{"label":"Catslide origin","value":"17th-century England"}],"regions":["North America","Europe"],"aliases":["saltbox","salt box","catslide","catslide roof","outshot roof"],"related":["gable-roof","shed-roof","gambrel-roof"],"company":null,"sources":[{"title":"Saltbox","url":"https://en.wikipedia.org/wiki/Saltbox","publisher":"Wikipedia"},{"title":"List of roof shapes","url":"https://en.wikipedia.org/wiki/List_of_roof_shapes","publisher":"Wikipedia"}],"country":null},{"slug":"samoan-fale","title":"Samoan Fale","type":"article","summary":"Open-sided Samoan house with a domed roof on timber posts, traditionally thatched with sugarcane leaves and lashed with coconut-fibre sennit.","body":"The *fale* is the traditional building of Samoa and, more broadly, of western Polynesia. A classic fale is round or oval in plan, has no walls, and is covered by a high domed roof supported on a ring of timber posts. The design suits a hot, humid island climate: the roof sheds tropical rain and gives shade, while the open sides let breezes pass through.\n\n## Roof construction\n\nThe roof frame is built from timber members lashed together with *ʻafa*, a plaited cord (sennit) made from dried coconut husk fibre. Before contact with Europeans, Samoan building used no metal fasteners at all, so the whole structure depended on lashing. An ordinary fale can use 30,000-50,000 ft (roughly 9-15 km) of sennit, which was traditionally prepared by older men or chiefs (*matai*).\n\nOnce the frame is finished it is covered with thatch made by women. The usual material is dried sugarcane leaves, or coconut palm fronds where sugarcane is not available. Thatch panels overlap from the eaves upward to form a double layer, and a well-laid roof lasts about seven years before it needs replacing.\n\n## Builders\n\nConstruction was overseen by *tufuga fau fale*, master builders who acted as both architects and craftsmen. They belonged to an old guild, and hiring them involved negotiation and customary exchange. Assistants and members of the commissioning family cut timber and did the heavy work.\n\n## Types\n\nThe *fale tele* (\"big house\") is the main meeting house of a family complex. It is usually round and placed at the front of the compound, and it is used for council meetings, ceremonies, funerals and the bestowal of chiefly titles. Smaller fale serve as sleeping and living houses.\n\n## Screens and weather\n\nInstead of walls, woven coconut-frond blinds (*pola*) hang from the roof framework. They can be lowered section by section to block sun, wind, rain or view.\n\n## Modern changes\n\nMany fale today are rectangular rather than round, and many smaller fale and village cookhouses (*umukuka*) use corrugated iron instead of thatch. The basic form, an open plan under a dominant roof, remains common across Samoa.","key_facts":[{"label":"Region","value":"Samoa, western Polynesia"},{"label":"Thatch","value":"Dried sugarcane leaves or coconut fronds"},{"label":"Lashing","value":"ʻAfa (coconut-fibre sennit)"},{"label":"Thatch lifespan","value":"About 7 years"},{"label":"Master builders","value":"Tufuga fau fale"}],"regions":["Oceania"],"aliases":["Fale","Fale tele","Samoan house"],"related":["roofing-in-the-pacific-islands","thatch","wharenui","corrugated-iron"],"sources":[{"title":"Architecture of Samoa","url":"https://en.wikipedia.org/wiki/Architecture_of_Samoa","publisher":"Wikipedia"},{"title":"Fale","url":"https://en.wikipedia.org/wiki/Fale","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"sans-10407-thatched-roof-construction","title":"SANS 10407 Thatched Roof Construction","category":"standards-codes","type":"standard","summary":"South African national standard for thatched roof construction (edition 2, 2015), used with SANS 10400 Parts L and T for pitch, thickness, timbers and fire.","body":"SANS 10407 is the South African National Standard for the construction of thatched roofs. The edition cited in the 2016 industry guide is edition 2 of 2015. It sits alongside the National Building Regulations, published as SANS 10400, in particular Part L (roofs), Part T (fire protection) and Part V (chimneys). The Thatchers Association of South Africa (TASA) published *A Guide to Thatch Construction in South Africa* in 2016 to explain good practice; the guide states that it is not itself a specification.\n\n## Materials\n\nThe guide identifies these South African thatching materials:\n\n- Common thatching grass, *Hyparrhenia hirta*.\n- Fine thatching grass, *Hyparrhenia filipendula*.\n- Cape thatching reed, *Thamnochortus* species (Afrikaans *dekriet*).\n\nIt does not recommend *Chondropetalum tectorum* or *Phragmites australis*.\n\n## Key figures (TASA guide)\n\n| Item | Requirement |\n|---|---|\n| Minimum pitch | 45 degrees |\n| Finished thickness, grass | 175 mm (6.9 in), at least 70 mm (2.8 in) over the sway |\n| Finished thickness, reed | 180 mm (7.1 in), at least 80 mm (3.1 in) over the sway |\n| Rafter spacing | Not more than 900 mm (35 in) centres |\n| Truss spacing | Not more than 2.7 m (8.9 ft) |\n| Battens | At least 38 x 38 mm (1.5 x 1.5 in) |\n| Laths | At least 25 mm (1 in) top diameter |\n| Binding spacing | Not more than 110 mm (4.3 in) |\n| Sway wire | Galvanised, at least 3.15 mm (0.12 in) |\n| Chimney height above thatch | At least 1 m (3.3 ft) |\n\nValley liners must be at least 0.4 mm copper, 0.5 mm galvanised steel or 0.7 mm aluminium. A 50 mm (2 in) gap between laths and ceiling is recommended for ventilation. Below 45 degrees, thatch decays rapidly.\n\nThe SANS 10400 guidance site summarises Part L thatch rules as a 45 degree slope (35 degrees at dormers), 175 mm of fine grass or reed, 200 mm (7.9 in) of coarse grass and 300 mm (11.8 in) of water reed, and pole rafters of 100-125 mm (4-5 in) diameter for spans up to 4 m (13 ft).\n\n## Fire and lightning\n\nUnder clause 4.12.2 of SANS 10400-T, thatched buildings with a roof area over 300 m² (3,230 sq ft), or closer to a boundary than 4.5 m (14.8 ft), need additional fire-retardant systems; small free-standing thatched shelters (*lapas*) under 20 m² (215 sq ft) must be at least 1.0 m (3.3 ft) from any boundary. Lightning protection to at least protection level III (SANS 62305-3) is required where ground flash density under SANS 10313 exceeds 7, or 3 where wire sways could act as conductors, with masts at least 1,000 mm (39 in) clear of the thatch.","key_facts":[{"label":"Issuing body","value":"South African Bureau of Standards (SABS)"},{"label":"Edition","value":"Edition 2, 2015"},{"label":"Minimum pitch","value":"45 degrees"},{"label":"Grass thickness","value":"175 mm (6.9 in)"},{"label":"Related","value":"SANS 10400-L, -T, -V"}],"regions":["Africa"],"aliases":["SANS 10407","SANS 10407:2015"],"related":["roofing-in-south-africa","thatch","cape-dutch-thatch","rondavel","thatching-process","metal-roofs-and-lightning","thatch-maintenance"],"company":null,"sources":[{"title":"A Guide to Thatch Construction in South Africa (2016, Edition 1)","url":"https://www.vetiver.org/wp-content/uploads/2021/10/GUIDE-TO-THATCH-CONSTRUCTION-IN-SOUTH-AFRICA1.pdf","publisher":"Thatchers Association of South Africa"},{"title":"Roofs - Part L","url":"https://sans10400.org.za/roofs","publisher":"SANS 10400 (sans10400.org.za)"}],"country":null},{"slug":"sawtooth-roof","title":"Sawtooth Roof","category":"roof-forms","type":"article","summary":"A sawtooth roof is a series of parallel ridges, each with one steep, glazed face and one shallower solid face, giving a jagged profile and even daylight.","body":"A sawtooth roof is made up of a row of parallel ridges with two different pitches. The steeper (often vertical) side of each ridge is glazed, while the shallower side is solid and roofed. In profile the roof looks like the teeth of a saw. The design lets large, deep buildings be lit evenly by daylight from above.\n\n## Orientation\n\nThe glazed faces normally face away from the equator, that is, north in the northern hemisphere and south in the southern hemisphere. This admits steady, diffuse sky light while keeping direct sunlight, glare and solar heat off workers and machinery. In British usage the glazed faces are called north lights, and the roof is sometimes called a north-light roof.\n\n## History\n\nThe British engineer William Fairbairn may have designed early sawtooth roofs as early as 1827. The first documented example is the weaving shed at Titus Salt's Saltaire Mills near Bradford, founded in 1851. The form spread widely during the Industrial Revolution for textile mills and factories that needed good natural light over large, open floors. Its use declined as electric lighting became cheap and reliable.\n\n## Revival\n\nSince the late 20th century the sawtooth has returned in schools, offices, galleries, warehouses and houses because daylighting reduces the need for artificial lighting. The solid slopes can also carry solar panels angled toward the sun, combining daylight and generation.\n\n## Construction and maintenance\n\n- Each valley between teeth is a gutter, often a box gutter, which must be sized and maintained to avoid overflow into the building.\n- Snow and debris can collect in the valleys.\n- Glazing must be detailed against leaks and condensation, and older single-glazed north lights perform poorly thermally.\n- Steel or timber trusses, or portal frames, typically support the roof.","key_facts":[{"label":"Glazed faces","value":"Face away from equator (north in N. hemisphere)"},{"label":"First documented","value":"Saltaire Mills weaving shed, from 1851"},{"label":"UK term","value":"North-light roof"}],"regions":["Global"],"aliases":["north-light roof","north light","saw-tooth roof","factory roof"],"related":["skylight","rain-gutter","shed-roof","m-shaped-roof"],"company":null,"sources":[{"title":"Sawtooth roof","url":"https://en.wikipedia.org/wiki/Sawtooth_roof","publisher":"Wikipedia"},{"title":"Roof","url":"https://www.designingbuildings.co.uk/wiki/Roof","publisher":"Designing Buildings Wiki"}],"country":null},{"slug":"sbs-modified-bitumen","title":"SBS Modified Bitumen","category":"low-slope-systems","type":"term","summary":"Modified bitumen membrane made elastic with styrene-butadiene-styrene rubber, installed by torch, hot asphalt, cold adhesive or self-adhesion.","body":"SBS modified bitumen is roofing membrane made from asphalt blended with styrene-butadiene-styrene, a thermoplastic elastomer that gives the compound rubber-like stretch and recovery. It was developed in France and Germany in the 1960s with colder climates in mind, because it stays flexible at low temperatures.\n\n## Composition\n\nA typical SBS compound contains about 10-15% SBS polymer, asphalt, and limestone or similar mineral filler (around 15%), sometimes with oxidation inhibitors. It is blended hot, around 175-200 C (350-390 F), for several hours. In tests reported by industry, SBS bitumen with about 10% rubber could stretch to several times its length and recover. The compound is coated onto polyester, glass-fibre or combination reinforcement.\n\n## Installation\n\nSBS is the most versatile of the modified bitumens. It can be:\n\n- mopped into hot asphalt, like a built-up ply\n- torch-applied\n- set in cold adhesives (solvent-based or water-based)\n- supplied as self-adhered sheets\n\nThis flexibility lets contractors choose methods that avoid open flames, which is increasingly important to insurers and building owners.\n\n## Systems\n\nThe usual assembly is a two-ply system: a smooth or sanded base sheet and a granule-surfaced cap sheet. Three-ply systems and hybrid systems with built-up felts are also used. SBS sheets are widely used as flashing membranes on BUR roofs, where they handle movement better than felt strip-ins.\n\n## Surfaces\n\nCap sheets come with coloured or white mineral granules, foil faces or factory coatings. Reflective cap sheets can meet North American cool-roof requirements.\n\n## Comparison with APP\n\nSBS has better low-temperature flexibility and elasticity; APP is stiffer and more resistant to heat and UV and is almost always torched. Both originated in Europe and both are made worldwide.","key_facts":[{"label":"Polymer content","value":"About 10-15% SBS"},{"label":"Developed","value":"France and Germany, 1960s"},{"label":"Install methods","value":"Hot mop, torch, cold adhesive, self-adhered"},{"label":"Typical system","value":"Base sheet plus granulated cap sheet"}],"regions":["Global","Europe","North America"],"aliases":["SBS mod-bit","elastomeric bitumen","SBS membrane"],"related":["modified-bitumen-roofing","app-modified-bitumen","self-adhered-membrane","cold-applied-roofing","torch-applied-roofing"],"company":null,"sources":[{"title":"Low-slope roofing systems: built-up roofs and modified bitumen","url":"https://buildingenclosureonline.com/articles/82366-low-slope-roofing-systems-built-up-roofs-and-modified-bitumen","publisher":"Building Enclosure"},{"title":"Fit for Mod-Bit","url":"https://roofingcontractor.com/articles/95892-fit-for-mod-bit","publisher":"Roofing Contractor / ARMA"},{"title":"Who Put the Modified in Modified Bitumens?","url":"https://buildings.com/feature/article/10187932/who-put-the-modified-in-modified-bitumens","publisher":"Buildings"}],"country":null},{"slug":"scandinavian-sod-roofs","title":"Scandinavian Sod Roofs","category":"history","type":"article","summary":"Turf laid over layers of birch bark, the traditional roof of rural Norway and much of Scandinavia from prehistory until the 18th-19th centuries.","body":"A **sod roof**, or turf roof, is a roof covered with grass turf laid over a waterproof layer of birch bark on a timber deck. It is known in Norwegian and Swedish as *torvtak*, in Danish as *tørvetag* and in Icelandic as *torfþak*. For centuries it was the standard roof of rural log houses in Norway and large parts of Scandinavia.\n\n## How it works\n\nBirch bark, laid in overlapping layers, is the actual waterproof membrane; it is naturally resistant to rot and can last for generations. The turf above holds the bark in place, protects it from sunlight and wind, and adds insulation. Around 30 years was regarded as the normal life of a sod roof in most places before re-laying.\n\n## History\n\nScandinavian roofs have probably been covered with birch bark and sod since prehistory. In the Viking Age and Middle Ages most houses had sod roofs, while churches and buildings with steeper roofs used boards, wooden shingles or lead. In rural areas sod roofs remained almost universal until the early 18th century. Their distribution closely follows the log-building tradition of Finland and the Scandinavian peninsula.\n\n## Decline\n\nTile roofs, already common in towns and on manors, gradually replaced sod roofs in the countryside during the 19th century, except in remote inland areas. Corrugated iron and other industrial materials added to the pressure. Sources differ on timing: some date the main decline to the 18th century, others to the late 19th century.\n\n## Revival\n\nJust as the tradition was disappearing, the national romantic movement revived interest in vernacular building. Demand from mountain lodges and holiday cabins, open-air museums and preservation societies kept the skills alive. Turf roofs are still widely used on new cabins in Norway, and they have reappeared as an alternative to modern materials.\n\n## Elsewhere\n\nTurf roofs are also traditional on farm buildings in Iceland, and similar earth-covered roofs exist in other cold or treeless regions.","key_facts":[{"label":"Waterproof layer","value":"Birch bark"},{"label":"Normal life","value":"About 30 years"},{"label":"Dominant period","value":"Prehistory to 18th-19th century"},{"label":"Norwegian term","value":"Torvtak"}],"regions":["Europe","Arctic"],"aliases":["turf roof","torvtak","Norwegian grass roof","birch bark roof"],"related":["history-of-green-roofs","prehistoric-shelters-and-early-thatch","green-roof"],"company":null,"sources":[{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"}],"country":null},{"slug":"schindel","title":"Schindel (Alpine and Central European Wood Shingles)","type":"article","summary":"Hand-split wooden roof and wall shingles traditional in the Alps and Central Europe, made from spruce, pine or larch and still used on heritage buildings.","body":"*Schindel* is the German word for a wooden shingle. In the Alps and across Central Europe, split wooden shingles have roofed farmhouses, mountain huts, chapels and churches for centuries, and in many villages they also clad the walls. Similar traditions exist across Poland, Slovakia, the Carpathians, Scandinavia and the Baltic states.\n\n## Split, not sawn\n\nThe traditional shingle is split along the grain from a block of timber rather than sawn. Splitting keeps the wood fibres continuous and the surface smooth, so water runs off and the shingle dries quickly. For that reason split shakes are generally more durable than sawn shingles, particularly in wet climates.\n\n## Timber\n\nIn Central Europe and Scandinavia, shingles were most commonly made from Scots pine (*Pinus sylvestris*) and local spruce (*Picea*). Larch is also used in Alpine areas for its resin content and durability. In Latvia, aspen is the most popular shingle wood; aspen shingles also cover the domes of the wooden churches at Kizhi in Russia. Polish and Slovak split shakes are typically about 36 in (90 cm) long, 4-6 in (10-15 cm) wide and 1-1.25 in (2.5-3 cm) thick, considerably longer than North American products.\n\n## Laying\n\nShingles are nailed to battens in overlapping courses, usually with two or three layers at any point, so that every joint is covered by the shingle above. On steep Alpine roofs and walls they may be laid in decorative patterns, and some roofs use long split boards held down with poles and stones rather than nails.\n\n## Examples\n\nShingle facades and roofs are typical of villages such as Lech in Austria. In Poland, All Saints Church in Łaziska is documented as roofed with 1,467 fir shingles, and the UNESCO-listed Wooden Churches of Southern Małopolska carry tall shingled roofs over horizontal log structures.\n\n## Fire and maintenance\n\nWooden shingles burn, and many towns historically restricted them in favour of slate, sheet metal or clay tile. Shingle roofs also need more maintenance than many modern coverings. Today they are used mainly on heritage buildings, mountain architecture and in places where local rules protect traditional roofscapes, often with fire-retardant treatment.\n\n## Related traditions\n\nNorth American wood roofing distinguishes split shakes from sawn shingles, made from western red cedar, redwood or Atlantic white cedar. Japan uses very thin split shingles fixed with bamboo nails on temples such as Kinkaku-ji and Ginkaku-ji.","key_facts":[{"label":"Meaning","value":"Wooden shingle (German)"},{"label":"Typical timbers","value":"Spruce, Scots pine, larch, aspen"},{"label":"Polish/Slovak shake size","value":"About 90 × 10-15 × 2.5-3 cm"},{"label":"Manufacture","value":"Split along the grain"}],"regions":["Europe"],"aliases":["Alpine wood shingle","Lärchenschindel","Gont","Wood shake"],"related":["wood-shingle","wooden-churches-of-southern-malopolska","onion-dome","roofing-in-germany","roofing-in-poland-and-eastern-europe"],"sources":[{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Wooden Churches of Southern Małopolska","url":"https://whc.unesco.org/en/list/1053","publisher":"UNESCO World Heritage Centre"},{"title":"Kizhi Pogost","url":"https://en.wikipedia.org/wiki/Kizhi_Pogost","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"scottish-slate","title":"Scottish Slate","category":"materials","type":"term","summary":"Natural roofing slate once quarried in Scotland's West Highlands, Highland Border and Aberdeenshire; none has been quarried since 1965.","body":"Scottish slate is natural roofing slate from quarries in Scotland. It covers a large share of the country's historic roofs, but commercial quarrying ended in 1965, so repairs today depend on reclaimed Scottish slate or imported substitutes. Efforts to reopen historic sources began in the 2020s.\n\n## Types\n\nScottish roofing slate is usually grouped into three types:\n\n- **West Highland slate**, from more than 64 sites in Argyll and Inverness-shire centred on Ballachulish, Easdale, Cullipool and Tayvallich. It is the darkest type, dark grey to blue-black, often with a rippled surface and small cubes of iron pyrite.\n- **Highland Border slate**, from about 80 quarries in a strip running from Bute to Dunkeld along the edge of the Highlands. Colours range from reddish-purple grey to greenish grey; striped red and green slates from Aberfoyle have been nicknamed \"tartan\".\n- **Macduff slate**, from a few hundred mostly small quarries around the Hills of Kirkney and Tillymorgan in Aberdeenshire and in Banffshire. It is typically grey with a flat, slightly rough surface.\n\n## History\n\nThe first written reference to Easdale slate dates from 1554. Commercial extraction on the Slate Islands is recorded from the 17th century, and Easdale slate roofed Castle Stalker in Appin in 1631 and Ardmaddy Castle in 1676. The Marble and Slate Company of Netherlorn was formed in 1745, when over a million slates were made; pumping machinery later allowed quarrying below sea level, and output reached about 5 million slates a year by 1800. The Ellenabeich quarry was worked to a depth of 250 ft (about 76 m).\n\nA tidal flood in 1881 drowned the Easdale quarries, and output never recovered; the industry lost ground to Ballachulish and then to Welsh slate, and the last commercial shipment from Easdale left in 1911. In the 19th century Scottish slate was exported to the United States, Australia and New Zealand. The Cullipool quarries on Luing were the last to close, in 1965.\n\n## Supply today\n\nThe only genuine Scottish slate now available is reclaimed from older buildings, and that supply is shrinking. Most slate used in Scotland is imported, mainly from Spain. A 2024 British Geological Survey report funded by Historic Environment Scotland identified 32 historic sources with potential for development. At Cullipool, minerals planning consent was granted in 2024 and the Isle of Luing Community Trust secured £1.75 million from the Scottish Government, and test production was announced for summer 2026.\n\n## Conservation\n\nMatching the colour, texture and thickness of the original slate is important on listed and historic buildings, and reclaimed slates of the same type are usually preferred over new imports for repairs.","key_facts":[{"label":"Main types","value":"West Highland, Highland Border, Macduff"},{"label":"First record (Easdale)","value":"1554"},{"label":"Easdale output by 1800","value":"About 5 million slates a year"},{"label":"Last quarry closed","value":"Cullipool, Luing, 1965"},{"label":"Revival","value":"Cullipool planning consent 2024; test production announced for 2026"}],"regions":["Europe"],"aliases":["Ballachulish slate","Easdale slate","West Highland slate"],"related":["natural-slate","welsh-slate","spanish-slate","slate-repair","roofing-in-the-united-kingdom","delabole-slate"],"company":null,"sources":[{"title":"Sourcing Scottish slate in the 21st century","url":"https://www.designingbuildings.co.uk/wiki/Sourcing_Scottish_slate_in_the_21st_century","publisher":"Designing Buildings Wiki"},{"title":"Slate Industry","url":"https://easdalemuseum.org/slate-industry/","publisher":"Easdale Island Folk Museum"},{"title":"Easdale Slate Quarries","url":"https://canmore.org.uk/site/22614/easdale-slate-quarries","publisher":"Canmore / Historic Environment Scotland"}],"country":null},{"slug":"scupper","title":"Scupper","category":"low-slope-systems","type":"term","summary":"An opening through a parapet or roof edge that lets water drain off a low-slope roof, either as the primary outlet or as an emergency overflow.","body":"A scupper is an opening in a wall or parapet that allows water to escape from a roof, terrace or balcony instead of pooling. On low-slope roofs scuppers are set at roof level in parapets and usually discharge into a conductor head (collector box) and downpipe, or directly over the edge.\n\n## Types\n\n- **Primary (through-wall) scuppers:** the main drainage route on roofs drained to the perimeter.\n- **Overflow (emergency) scuppers:** set higher than the primary drains so that, if drains block, water exits the roof before it builds to a depth that overloads the structure or rises above flashings.\n\n## Construction\n\nScuppers are typically formed as metal boxes or sleeves, made of galvanised or coated steel, stainless steel, copper or aluminium, set through the parapet and flashed into the membrane. Single-ply manufacturers supply prefabricated scupper boots; liquid-applied membranes and PMMA are often used to seal them.\n\n## Design considerations\n\n- size and number based on rainfall intensity and roof area under the plumbing code (in the US, the International Plumbing Code) or BS EN 12056-3 in the UK and Europe\n- crickets or tapered insulation to direct water to the scupper\n- flashing heights that remain above the maximum water level in an overflow event\n- avoiding discharge onto walkways or building entrances\n\n## Advantages and limitations\n\nScuppers are simple, easy to inspect and less prone to hidden blockage than internal drains. They are limited to roofs where water can be brought to the perimeter, and in cold climates exterior discharge can freeze.","key_facts":[{"label":"Location","value":"Through parapet or roof edge"},{"label":"Types","value":"Primary and overflow"},{"label":"UK/EU sizing standard","value":"BS EN 12056-3"}],"regions":["Global"],"aliases":["roof scupper","through-wall scupper","overflow scupper"],"related":["overflow-drainage","roof-drain","parapet","cricket-roofing","positive-drainage"],"company":null,"sources":[{"title":"Scupper","url":"https://en.wikipedia.org/wiki/Scupper","publisher":"Wikipedia"},{"title":"Falls and drainage","url":"https://www.bauder.co.uk/roof-systems/refurbishment-projects/solving-the-challenge/improving-drainage-falls","publisher":"Bauder"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"}],"country":null},{"slug":"sealed-roof-deck","title":"Sealed Roof Deck","type":"term","summary":"A roof deck whose panel joints are sealed with tape or a self-adhered membrane so rain cannot pass through if the covering is lost.","body":"A sealed roof deck is a roof sheathing layer (usually plywood or oriented strand board) whose joints have been sealed so water cannot pass through the gaps between panels. It is one way of providing a secondary water barrier and is a core requirement of the FORTIFIED Roof standard developed by the Insurance Institute for Business & Home Safety (IBHS).\n\n## How it is built\n\nTwo methods are common:\n\n1. **Seam tape.** Self-adhering flashing tape is rolled onto every horizontal and vertical joint in the deck. A standard underlayment is then installed over the whole roof and the covering goes on top.\n2. **Full membrane.** A self-adhered underlayment is applied over the entire deck, sealing joints and field at the same time.\n\nDeck panels must be clean and dry for the adhesive to bond. Edges, valleys, penetrations and transitions need careful detailing because water driven by wind will find any gap.\n\n## Why it works\n\nWhen high winds strip shingles or tiles, the regular underlayment is often torn or lifted too, leaving deck joints exposed. Water entering through those joints soaks insulation and ceilings. IBHS testing found that one inch (25 mm) of rain on an unprotected deck can admit water equivalent to roughly nine bathtubs, and that sealing the deck can cut water intrusion by up to 95 percent.\n\n## Related upgrades\n\nIn the FORTIFIED Roof standard, a sealed deck is combined with:\n\n- 8d ring-shank nails at closer spacing for the deck, which IBHS says can roughly double uplift resistance compared with smooth nails;\n- a wider drip edge and a fully adhered starter strip at the edges;\n- coverings tested for wind (for shingles, ASTM D3161 Class F or ASTM D7158 Class H).\n\n## Where it is used\n\nSealed decks are most common in the US Gulf and Atlantic coastal states, especially where state grant programs (for example in Alabama) or insurance incentives reward FORTIFIED construction. The concept applies anywhere wind-driven rain is a hazard, including typhoon and cyclone regions.","key_facts":[{"label":"Methods","value":"Seam tape plus underlayment, or full self-adhered membrane"},{"label":"Water reduction (IBHS)","value":"Up to 95%"},{"label":"Paired with","value":"Ring-shank deck nails, enhanced edges"}],"regions":["North America","Global"],"aliases":["sealed deck","taped roof deck","SRD"],"related":["secondary-water-barrier","fortified-roof","hurricane-roof-damage","roof-insurance-discounts"],"sources":[{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/?p=2512","publisher":"Insurance Institute for Business & Home Safety (FORTIFIED Home)"},{"title":"Sealed Roof Decks and Fortified Systems","url":"https://finehomebuilding.com/2022/01/27/sealed-roof-decks-fortified-systems","publisher":"Fine Homebuilding"},{"title":"FORTIFIED Roof Guide (Hurricane)","url":"https://www.smarthomeamerica.org/assets/uploads/ibhs-fortified-roof-guide-HUR.pdf","publisher":"IBHS / Smart Home America"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"seam-failure","title":"Seam Failure","category":"problems-maintenance","type":"term","summary":"Opening or separation of the joints between sheets of a roof membrane or metal panel, allowing water into the roof assembly.","body":"Seam failure is the loss of a watertight bond at the laps where sheets of roofing meet. Because almost every low-slope membrane is made from many sheets joined in the field, the seams are often the weakest part of the system. Seams are also a concern on metal roofs and on taped or lapped underlayments.\n\n## Single-ply membranes\n\nThermoplastic membranes such as TPO and PVC are joined by hot-air welding, which fuses the two sheets together. Weld quality depends on temperature, travel speed, pressure, cleanliness and conditions such as wind, sun and the substrate below. Cold welds, scorched welds, contamination, wrinkles and fishmouths can all leave weak spots. Manufacturers typically call for test welds through the day and for every seam to be probed at the end of each work day.\n\nEPDM sheets are joined with seam tape or adhesive. Problems arise from poor cleaning or priming, insufficient rolling, or ageing of older liquid-adhesive seams. Shrinkage of the membrane can also put seams under stress.\n\n## Bituminous and other systems\n\nIn built-up and modified bitumen roofs, laps can open where bitumen was too cool, where there was too little of it, or where the roof has moved. On metal roofs, standing seams can open if not fully formed, and lapped seams on exposed-fastener panels may leak where sealant tape has failed.\n\n## Detection\n\nVisual signs include open edges, fishmouths and wrinkles at laps, loose flaps and dirt lines in the lap. A seam probe, a blunt hooked tool drawn along the edge of a welded lap, finds unbonded sections. Destructive cut tests and peel tests check bond strength. On a finished roof, leaks traced to seams can be confirmed with electronic leak detection where the system allows.\n\n## Repair\n\nRepairs follow the membrane manufacturer's procedures: thermoplastic seams can often be re-welded or covered with a welded patch after cleaning; EPDM seams are cleaned, primed and covered with cover tape. Widespread seam failure can indicate a systemic installation or product problem and may justify a professional survey.","key_facts":[{"label":"Most vulnerable roofs","value":"Low-slope membrane systems"},{"label":"Thermoplastic quality check","value":"Test welds and daily seam probing"},{"label":"Common defects","value":"Cold welds, wrinkles, fishmouths, contamination"}],"regions":["Global"],"aliases":["open seams","lap failure","split seam"],"related":["seam-probing","hot-air-welder","tpo-roofing","pvc-roofing","epdm-roofing","membrane-shrinkage","electronic-leak-detection"],"company":null,"sources":[{"title":"TPO and PVC Welding Guidelines","url":"https://www.versico.com/Resources/Media/Blog/2020/01/14/TPO-and-PVC-Welding-Guidelines","publisher":"Versico"},{"title":"Proper Installation and Maintenance Keys to Good Single-Ply Roofing","url":"https://facilitiesnet.com/roofing/article.aspx?id=16588","publisher":"Facilitiesnet"},{"title":"Troubleshooting a Failed TPO Roof","url":"https://www.jlconline.com/how-to/roofing/troubleshooting-a-failed-tpo-roof_o","publisher":"Journal of Light Construction"}],"country":null},{"slug":"seam-probing","title":"Seam Probe","category":"tools-equipment","type":"term","summary":"A small hooked or blunt-pointed hand tool drawn along the edge of welded or taped membrane seams to find unbonded voids.","body":"A seam probe is a simple hand tool used to check the seams of single-ply roof membranes for gaps, voids and unbonded sections. It typically has a handle and a slender metal shaft ending in a blunt, slightly hooked or rounded tip. The tip is drawn along the outer edge of a lap with light pressure; where the seam is properly fused or bonded the tip slides along the edge, but where there is a void it catches and enters the seam.\n\n## Where it is used\n\n- **Thermoplastic membranes** (TPO and PVC) joined by hot-air welding. Membrane manufacturers' guidance calls for all seams to be probed, typically at the end of each work day once they have cooled.\n- **EPDM** seams joined with tape or adhesive, to check edges for lifting.\n- **Flashings, patches and details** where hand welding is more prone to gaps.\n- **Inspection of existing roofs** during maintenance surveys and leak investigations.\n\n## Technique\n\nSeams must be allowed to cool fully before probing, since warm thermoplastic can be pushed open by the tool and give a false failure, or seal over a void. The inspector runs the probe along the entire length of each seam, paying special attention to T-joints (where three layers meet), step-offs, corners and around penetrations, which are the most common locations for voids. Defects found are marked with a crayon or marker and repaired, usually by re-welding or by welding a patch over the area, followed by probing again.\n\n## Limits\n\nProbing checks only the leading edge of a seam. A seam can be intact at the edge but poorly fused behind it, which is why manufacturers also call for test welds and peel tests during installation. Probing also cannot find punctures in the field of the membrane; electronic leak detection and visual inspection address those. A probe with a sharp point can damage membranes, so dedicated seam probes are designed with rounded tips.\n\n## Related tools\n\nHot-air welders, silicone seam rollers, and peel-test cutters make up the basic seam quality-control kit on thermoplastic roofs.","key_facts":[{"label":"Used on","value":"TPO, PVC and EPDM seams"},{"label":"When","value":"After seams cool; typically end of each work day"},{"label":"Problem areas","value":"T-joints, step-offs, corners, penetrations"}],"regions":["Global"],"aliases":["seam probing tool","seam pick","seam probe","probing welds"],"related":["hot-air-welder","seam-failure","tpo-roofing","pvc-roofing","electronic-leak-detection","hot-air-welding","roof-inspection-procedure","epdm-roofing"],"company":null,"sources":[{"title":"TPO and PVC Welding Guidelines","url":"https://www.versico.com/Resources/Media/Blog/2020/01/14/TPO-and-PVC-Welding-Guidelines","publisher":"Versico"},{"title":"Versico TPO Seam Probe Tool for Single-Ply Membrane Seam Inspection","url":"https://superarbor.io/products/versico-307687-versico-tpo-seam-probe-tool-for-single-ply-membrane-seam-inspection","publisher":"Superarbor"},{"title":"Plastic Handle Seam Probe","url":"https://www.bigrocksupply.com/plastic-handle-seam-probe.aspx","publisher":"Big Rock Supply"},{"title":"Canadian Roofing Reference Manual: 7.1.3 Thermoplastic Membrane Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-7-single-ply-roofing-membranes/7-1-thermoplastics/7-1-3-membrane-installation/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 13.1.2 Potential Problem Areas","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/canadian-roofing-reference-manual-chapter-13-troubleshooting-and-repairs/13-1-identify-cause-of-problem/13-1-2-potential-problem-areas/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"secondary-water-barrier","title":"Secondary Water Barrier","type":"term","summary":"A layer beneath the roof covering that limits water entry if shingles, tiles or panels are torn off in a storm.","body":"A secondary water barrier is a waterproofing layer installed under the main roof covering so that, if the covering is damaged or blown off, rain does not pour straight through the roof deck. It is a central idea in hurricane-resistant roofing because covering loss is common even when the roof structure survives.\n\n## Why it is needed\n\nInvestigations after Hurricane Andrew (1992) noted that wind-driven rain caused costly interior damage even on homes that kept most of their roof covering, and the report recommended a water-resistant membrane beneath the covering. Later storms reinforced the point: after Hurricane Michael (2018), FEMA documented water entering through damaged coverings, lost ridge vents and soffits, saturating insulation and causing mold.\n\nResearch by the Insurance Institute for Business & Home Safety (IBHS) illustrates the scale of the problem: one inch (25 mm) of rain falling on an exposed roof deck can let in water equivalent to about nine bathtubs.\n\n## Common approaches\n\n- **Self-adhered membrane over the whole deck.** A fully adhered underlayment (often modified bitumen or a synthetic with adhesive backing) stays bonded even if the covering leaves.\n- **Taped deck seams plus underlayment.** Self-adhering tape is applied over the joints between deck panels, then covered with a conventional underlayment. This is often called a sealed roof deck.\n- **Double-layer underlayment.** Two overlapped layers of felt or synthetic underlayment, with specific fastening, as permitted in some codes.\n\n## Codes and programs\n\nNewer code approaches in high-wind areas of the United States call for a secondary water barrier through either a sealed deck or enhanced underlayment, and the FORTIFIED Roof standard requires a sealed roof deck. IBHS reports that sealing the deck can reduce water intrusion by up to 95 percent in its testing.\n\n## Limits\n\nA secondary water barrier does not stop structural failure and is not a permanent roof. It buys time to make temporary repairs and protects the interior during the storm. Its performance depends on deck preparation, adhesion in hot or cold weather, and correct lapping at valleys, eaves and penetrations.","key_facts":[{"label":"Purpose","value":"Limit water entry after roof covering loss"},{"label":"IBHS figure","value":"Sealing the deck can reduce water intrusion by up to 95%"},{"label":"Typical methods","value":"Full self-adhered membrane, taped seams, or double underlayment"}],"regions":["North America","Global"],"aliases":["SWB","secondary water resistance","SWR"],"related":["sealed-roof-deck","fortified-roof","hurricane-roof-damage","roofing-underlayment"],"sources":[{"title":"From Hurricanes Andrew to Michael: Lessons Learned for Residential Roofing","url":"https://iibec.org/publication-post/from-hurricanes-andrew-to-michael-lessons-learned-for-residential-roofing/","publisher":"IIBEC"},{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/?p=2512","publisher":"Insurance Institute for Business & Home Safety (FORTIFIED Home)"},{"title":"Sealed Roof Decks and Fortified Systems","url":"https://finehomebuilding.com/2022/01/27/sealed-roof-decks-fortified-systems","publisher":"Fine Homebuilding"},{"title":"FORTIFIED Roof Guide (Hurricane)","url":"https://www.smarthomeamerica.org/assets/uploads/ibhs-fortified-roof-guide-HUR.pdf","publisher":"IBHS / Smart Home America"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"self-adhered-membrane","title":"Self-Adhered Roofing Membrane","category":"low-slope-systems","type":"term","summary":"A roofing sheet supplied with factory-applied adhesive under a release film, bonded by peeling the film and pressing the sheet down.","body":"A self-adhered membrane, often called \"peel-and-stick\", is a roofing or underlayment sheet whose bonding adhesive is applied in the factory and protected by a removable release liner. The installer positions the roll, peels away the liner and presses the sheet into place, usually with a weighted roller. Laps may be self-sealing or may use a separate adhesive strip.\n\n## Types\n\n- **Modified bitumen:** SBS base sheets and cap sheets with a self-adhesive rubberised bitumen underside. Some systems are fully self-adhered; others use a self-adhered base under a torched or hot-air-welded cap.\n- **Single-ply:** TPO, PVC and EPDM sheets are available with factory adhesive backings.\n- **Flashings and accessories:** peel-and-stick flashing strips, cover tapes and patches are widely used with EPDM and other systems.\n\n## Advantages\n\n- no open flame, kettle or wet adhesive\n- low odour, suitable for occupied buildings\n- consistent bond quality because the adhesive is factory-controlled\n- faster detailing; EPDM industry sources credit factory tape products with improving flashing quality\n\n## Limitations\n\nSelf-adhered products depend on clean, dry, primed substrates and on adequate temperature; adhesion falls off in cold weather. Some single-ply peel-and-stick products are more weather-sensitive during installation than welded or mechanically fastened systems, and their long-term performance record is shorter than older methods.\n\n## Uses beyond roofing\n\nSelf-adhered rubberised bitumen sheets also serve as temporary roofs, vapour retarders, air barriers and ice-barrier underlayments on steep roofs.\n\n## Historical context\n\nSelf-adhesive technology built on earlier advances in factory-applied tapes. In EPDM roofing, factory seam tapes replaced liquid seam adhesives during the 1980s and were followed by self-adhering flashing components with factory-applied adhesive, both credited with reducing reliance on site workmanship.","key_facts":[{"label":"Bond method","value":"Factory adhesive under release liner"},{"label":"Common materials","value":"SBS bitumen, TPO, PVC, EPDM"},{"label":"Key requirement","value":"Clean, dry, primed substrate in suitable temperature"}],"regions":["Global"],"aliases":["peel-and-stick membrane","SA membrane","self-adhesive membrane"],"related":["sbs-modified-bitumen","modified-bitumen-roofing","single-ply-roofing","cold-applied-roofing","vapor-retarder"],"company":null,"sources":[{"title":"Low-slope roofing systems: built-up roofs and modified bitumen","url":"https://buildingenclosureonline.com/articles/82366-low-slope-roofing-systems-built-up-roofs-and-modified-bitumen","publisher":"Building Enclosure"},{"title":"Fit for Mod-Bit","url":"https://roofingcontractor.com/articles/95892-fit-for-mod-bit","publisher":"Roofing Contractor / ARMA"},{"title":"Thermoplastic Polyolefin (TPO) Roofing Systems","url":"https://buildings.com/articles/35297/thermoplastic-polyolefin-tpo-roofing-systems","publisher":"Buildings"},{"title":"EPDM Historical Timeline","url":"https://epdmroofs.org/what-is-epdm/historical-timeline/","publisher":"EPDM Roofing Association"}],"country":null},{"slug":"seychellois-creole-house","title":"Seychellois Creole House","category":"world-roofing","type":"article","summary":"Timber house of the Seychelles with a high-pitched roof, first of pandanus thatch and later corrugated iron, a large verandah and raised stone foundations.","body":"The Seychellois Creole house is the traditional timber dwelling of the Seychelles. It is defined by a high-pitched roof, a large verandah or balcony with wooden balustrades, big double doors and windows, and a raised base of stone. Once common across the islands, it has become rare: an estimated 95% of such buildings are no longer standing.\n\n## Origins\n\nAccording to the historian Tony Mathiot, the first traditional Creole structures were designed and built by some of about 70 French Jacobins exiled to Mahe for allegedly plotting against Napoleon; the deportees arrived in 1801. The house type is attributed to French settlers from Ile Bourbon (Reunion) and developed through the 19th century.\n\n## Roof\n\n- **Form**: a high-pitched roof that, with large openings, gave natural ventilation and light. Some houses had small vertical windows in projecting gables.\n- **Thatch**: early roofs were thatched with pandanus leaves. A landslide in Victoria on 12 October 1862 washed away many thatched houses.\n- **Corrugated iron**: the Building Ordinance of 2 August 1902 restricted thatch in Victoria, after which builders there used corrugated iron sheets. Thatch was out of fashion by about 1910, though it continued in suburbs and rural districts.\n- **Structure**: a ridge pole of *capucin* and rafters of *bodamyen*, with hand-hewn casuarina beams joined by mortise and tenon.\n\n## Walls, floors and plan\n\nFrames and boards used tropical hardwoods including *capucin*, *bois rouge*, *albizzia*, *takamaka* and *kalis dipap*. Houses rest on masonry plinths, or in the 19th century sometimes on four stone piles or concrete pillars, with steps of coral limestone. A verandah with raffia blinds and a loft or garret were standard, and the kitchen was a separate outbuilding with a stone-flagged floor. Plantation houses had living rooms with up to ten pairs of double doors and windows. Coral lime, once used in masonry, is no longer used, partly to protect reefs.\n\n## Decline and conservation\n\nMany Creole houses were still lived in during the 1960s, but most were demolished after independence, and virtually no new traditional Creole buildings have been built since the 1970s. The Seychelles Heritage Foundation works on their preservation. Surviving examples include Kenwyn House in Victoria (1855), a declared National Monument renovated in 2003; the Grann Kaz on L'Union Estate, La Digue, restored in the late 1970s; and the restored town house Kaz Zanana in Victoria.","key_facts":[{"label":"Region","value":"Seychelles"},{"label":"Roof","value":"High-pitched; pandanus thatch, then corrugated iron"},{"label":"Thatch restricted","value":"Building Ordinance, 2 August 1902 (Victoria)"},{"label":"Timbers","value":"Capucin, bois rouge, takamaka, casuarina"},{"label":"Survival","value":"About 5% of such buildings remain"}],"regions":["Africa"],"aliases":["Seychelles Creole house","Creole house (Seychelles)"],"related":["roofing-in-seychelles","corrugated-iron","palm-thatch","roofing-in-mauritius"],"company":null,"sources":[{"title":"The traditional Creole architecture - An aspect of the Seychelles heritage in need of preservation","url":"https://www.seychellesnewsagency.com/public/articles/1652/The+traditional+Creole+architecture+-+An+aspect+of+the+Seychelles+heritage+in+need+of+preservation","publisher":"Seychelles News Agency"},{"title":"Those charming Creole houses of auld lang syne","url":"https://www.nation.sc/archive/243055/those-charming-creole-houses-of-auld-lang-syne","publisher":"Seychelles Nation"},{"title":"Seychelles: the island of exiles","url":"https://kreolmagazine.com/culture/history-and-culture/seychelles-the-island-of-exiles/","publisher":"Kreol Magazine"}],"country":null},{"slug":"shabono","title":"Shabono","category":"world-roofing","type":"article","summary":"Ring-shaped communal dwelling of the Yanomami of Venezuela and Brazil: a continuous palm-thatched lean-to roof around an open central plaza.","body":"A *shabono* (also *xapono*, *shapono* or *yano*) is the communal dwelling of the Yanomami, an Indigenous people of the forests of far southern Venezuela and far northern Brazil. It is essentially one enormous roof: a ring of lean-to shelters thatched with palm leaves, facing inward onto an open central plaza that is left unroofed.\n\n## Form\n\nEach family builds and occupies its own wedge of the ring, so the house is assembled from many family sections that together form a circle or oval. There are no internal walls between families; each household's area is marked off by a wooden post. EveryCulture, drawing on Gale's encyclopedia of world cultures, describes the whole as a giant circular lean-to made of a pole framework lashed together and thatched with palm leaves.\n\nHabitatio, a teaching resource of the Budapest University of Technology and Economics, gives diameters of 15 to 60 m (50 to 200 ft) and an internal height of 5 to 6 m (16 to 20 ft), with communities of about 40 to 300 people. The frame is of hardwood poles bound with lianas. Wikipedia describes outer walls formed by a palisade of timber cleared from the site, and an opening in the middle of the roof.\n\n## Adaptation\n\nAt higher elevations, where nights are cooler, communities build smaller houses with pitched roofs instead of open rings. Since about 1970 many villages have moved from small streams to larger rivers to stay in contact with missions.\n\n## Life span\n\nShabonos are short-lived. Habitatio reports that they usually have to be rebuilt every one to two years because of insect damage, heavy rain and strong winds, and that they are often burnt when abandoned. Building a new shabono is men's work.","key_facts":[{"label":"People","value":"Yanomami"},{"label":"Countries","value":"Venezuela, Brazil"},{"label":"Diameter","value":"15-60 m (50-200 ft)"},{"label":"Roof","value":"Palm-leaf thatch on lashed pole frame, open centre"},{"label":"Rebuilt","value":"Every 1-2 years (typical)"}],"regions":["Latin America"],"aliases":["xapono","shapono","yano","Yanomami roundhouse"],"related":["palm-thatch","thatch","maloca","roofing-in-venezuela","roofing-in-brazil"],"company":null,"sources":[{"title":"Shabono","url":"https://en.wikipedia.org/wiki/Shabono","publisher":"Wikipedia"},{"title":"Yanomamö - Settlements","url":"https://www.everyculture.com/South-America/Yanomam-Settlements.html","publisher":"EveryCulture (Gale)"},{"title":"Yanomami shabono","url":"https://habitatio.epitesz.bme.hu/en/portfolio/yanomami-shabono/","publisher":"Habitatio, Budapest University of Technology and Economics"}],"country":null},{"slug":"shed-roof","title":"Shed Roof (Skillion, Mono-Pitch, Lean-To)","category":"roof-forms","type":"article","summary":"A shed roof is a single flat plane sloping in one direction; it is called a skillion in Australia and a mono-pitch, pent or lean-to roof in the UK.","body":"A shed roof is the simplest pitched roof: a single, flat sloping plane. One wall is taller than the opposite wall and the roof runs between them. It is known by many regional names: skillion roof in Australia and New Zealand; mono-pitch, pent or lean-to roof in the UK and Ireland; and shed roof in North America. A lean-to specifically describes a mono-pitch roof whose high side leans against a taller wall of the main building.\n\n## Uses\n\n- Extensions, porches, verandas, carports, garden sheds and outbuildings.\n- Contemporary houses, where tilted planes create tall clerestory walls and dramatic interiors.\n- Combined in multiple offset planes with clerestory windows between them.\n- Solar installations, since a single plane can be oriented toward the sun; in the northern hemisphere a south-facing mono-pitch suits photovoltaic panels.\n\n## Pitch\n\nShed roofs range from very low slopes that require membrane roofing to steep slopes clad in tiles or metal. UK guidance commonly quotes a minimum of around 15° for pitched coverings on pent roofs, though the actual minimum depends on the covering manufacturer's specification. Standing-seam and other metal roofs can be used at lower pitches.\n\n## Advantages\n\n- Simple framing, often with rafters or mono-pitch trusses spanning from wall to wall.\n- Few joints: no ridge, hips or valleys, reducing leak points.\n- Easy drainage to a single gutter along the low eave.\n\n## Considerations\n\n- All water drains to one edge, so the gutter and downpipes must be sized for the whole roof area.\n- The high wall and the top edge of the roof need careful detailing; where a lean-to meets a main wall, an apron or headwall flashing seals the joint.\n- Large rooms under a single slope can have uneven ceiling heights.\n- On long spans, a shed roof may need intermediate beams.","key_facts":[{"label":"Planes","value":"One"},{"label":"Australian name","value":"Skillion"},{"label":"UK names","value":"Mono-pitch, pent, lean-to"}],"regions":["Global"],"aliases":["skillion roof","mono-pitch roof","monopitch","pent roof","lean-to roof","single-pitch roof"],"related":["flat-roof","apron-flashing","saltbox-roof","butterfly-roof","sawtooth-roof"],"company":null,"sources":[{"title":"Types of Roof: A Complete Guide to the Most Common Options","url":"https://www.homebuilding.co.uk/advice/types-of-roof","publisher":"Homebuilding & Renovating"},{"title":"Roof","url":"https://www.designingbuildings.co.uk/wiki/Roof","publisher":"Designing Buildings Wiki"}],"country":null},{"slug":"sheet-metal-brake","title":"Sheet Metal Brake","category":"tools-equipment","type":"term","summary":"A bending machine that clamps sheet metal and folds it along a straight line, used to make flashings, trims, drip edges and panels.","body":"A sheet metal brake is a machine for making straight, accurate bends in sheet metal. The sheet is clamped between a bed and a clamping bar, and a hinged bending leaf (apron) swings up to fold the metal along the edge of the clamp. Brakes are central to metal roofing and flashing work, where long, consistent bends are needed for drip edges, valley flashings, rake and fascia trims, coping caps and custom panels.\n\n## Types\n\n- **Portable brakes** (often called siding brakes in North America) are lightweight aluminium-framed units carried to the job site and set up on stands. Lengths of about 8 to 10 ft (2.4 to 3 m) are common, allowing full-length trim and flashing to be bent on site.\n- **Cornice brakes** have a solid clamping bar for long straight bends and creases, suited to high-volume shop work on standard profiles.\n- **Box and pan (finger) brakes** use removable clamping fingers of various widths, so pieces with existing flanges can be bent into boxes, pans and complex flashings.\n- **Magnetic brakes** clamp with an electromagnet, leaving room to form enclosed shapes.\n- **Press brakes**, powered by hydraulics or motors, bend heavier gauges with punch and die tooling in fabrication shops.\n- **Mini brakes and hand brakes**, around 4 ft (1.2 m) long, handle short pieces on the roof.\n\n## Capacity\n\nA brake's capacity is rated by length and by the thickest material it can bend, and ratings depend on the metal: a brake rated for aluminium may be overloaded by steel of the same gauge. Supplier guides note that a 22-gauge aluminium-rated brake would struggle with 16-gauge steel.\n\n## Good practice\n\n- Protect painted surfaces with clean clamping faces and, where needed, protective film.\n- Respect minimum bend radii for the metal and coating, especially in cold weather.\n- Mark and measure from the clamping edge for repeatable bends.\n- Use accessories such as slitters (to cut strips from coil), hemming bars and return gauges.\n\nBrakes complement hand seamers, snips and roll formers in the metal roofer's kit.","key_facts":[{"label":"Common portable lengths","value":"About 8-10 ft (2.4-3 m)"},{"label":"Main types","value":"Portable, cornice, box and pan, press"},{"label":"Typical products","value":"Drip edge, valley flashing, trims, copings"}],"regions":["Global"],"aliases":["metal brake","bending brake","siding brake","cornice brake","finger brake"],"related":["hand-seamer","hemming-tool","aviation-snips","portable-roll-former","drip-edge","flashing-failure"],"company":null,"sources":[{"title":"Sheet metal brake guide","url":"https://www.stortz.com/sheet-metal-brake-guide/","publisher":"John Stortz & Son"},{"title":"Sheet Metal Brake","url":"https://americanmachinetools.com/hand_brake.htm","publisher":"American Machine Tools"},{"title":"Van Mark Mark II TrimMaster portable siding brake","url":"https://superarbor.io/products/van-mark-products-mark-ii-trimmaster-brake","publisher":"Superarbor"},{"title":"Malco MB48A Portable Mini Brake","url":"https://www.supplyhouse.com/Malco-MB48A-Portable-Mini-Brake","publisher":"SupplyHouse"}],"country":null},{"slug":"sheet-metal-gauge","title":"Sheet Metal Gauge and Thickness Conversion","category":"standards-codes","type":"term","summary":"Gauge is a traditional, non-linear number for sheet thickness used in North America; a higher gauge means thinner metal, and values differ by metal.","body":"In the United States and Canada, steel roofing is usually described by gauge, such as 22, 24, 26 or 29 gauge. The gauge number is a traditional, non-linear scale rooted in weight per area, and a larger number means a thinner sheet. Most of the world specifies sheet directly in millimetres, and standards bodies including ASTM discourage gauge numbers, calling the term archaic. Copper is a further exception in North America: it is sold by weight in ounces per square foot.\n\n## Gauge does not mean the same thing for every metal\n\nThe same gauge number gives different thicknesses for plain steel, galvanized steel and aluminium. Typical published values:\n\n| Gauge | Steel sheet | Galvanized steel | Aluminium |\n|---|---|---|---|\n| 22 | 0.0299 in (0.76 mm) | 0.0336 in (0.85 mm) | 0.025 in (0.64 mm) |\n| 24 | 0.0239 in (0.61 mm) | 0.0276 in (0.70 mm) | 0.020 in (0.51 mm) |\n| 26 | 0.0179 in (0.45 mm) | 0.0217 in (0.55 mm) | 0.017 in (0.43 mm) |\n| 28 | 0.0149 in (0.38 mm) | 0.0187 in (0.47 mm) | 0.0126 in (0.32 mm) |\n| 29 | 0.0135 in (0.34 mm) | 0.0172 in (0.44 mm) | 0.0113 in (0.29 mm) |\n\nPublished figures for coated roofing sheet can differ slightly from these tables, partly because thickness may be stated with or without the metallic coating, as the plain and galvanized columns show. Always check the actual specified thickness.\n\n## Copper weights\n\n- 16 oz/ft2 copper: about 0.0216 in (0.55 mm), roughly 24 gauge.\n- 20 oz/ft2 copper: about 0.0270 in (0.69 mm), roughly 22 gauge.\n\n## Aluminium roofing\n\nAlthough aluminium gauge tables exist, aluminium roofing is normally quoted in thousandths of an inch or in millimetres, because a steel gauge number has no meaningful aluminium equivalent. Residential aluminium roofing typically runs from about 0.019 in (0.48 mm) for flashing and some stamped shingles to about 0.040 in (1.02 mm), with standing seam pans often 0.032 in (0.81 mm) or heavier. Temper and profile shape also affect stiffness, so two sheets of the same thickness can perform differently.","key_facts":[{"label":"Direction","value":"Higher gauge = thinner sheet"},{"label":"24 ga steel sheet","value":"0.0239 in (0.61 mm)"},{"label":"26 ga steel sheet","value":"0.0179 in (0.45 mm)"},{"label":"Outside North America","value":"Thickness specified directly in mm"}],"regions":["North America","Global"],"aliases":["metal roofing gauge","gauge to mm","gauge chart","steel gauge"],"related":["metallic-coating-designations","copper-roofing","aluminum-roofing","standing-seam-metal-roof","oil-canning"],"company":null,"sources":[{"title":"Sheet metal","url":"https://en.wikipedia.org/wiki/Sheet_metal","publisher":"Wikipedia"},{"title":"Copper Availability and Attributes","url":"https://atas.com/did-you-know-series/copper-availability-and-attributes","publisher":"ATAS International"},{"title":"14.3. Copper Roofing (architectural specifications)","url":"https://archive.copper.org/applications/architecture/arch_dhb/specifications/arch_specs/sheet_roofing.php","publisher":"Copper Development Association"},{"title":"Aluminum Roofing Gauge & Thickness Explained (2026)","url":"https://www.interlockroofing.com/kb/aluminum-roofing-gauge-thickness/","publisher":"Interlock Roofing"}],"country":null},{"slug":"shibam-tower-houses","title":"Shibam Tower Houses","category":"world-roofing","type":"place","regions":["Middle East"],"company":null,"summary":"The mud-brick tower houses of Shibam, Yemen, up to 11 storeys high, whose walls and roofs depend on constant re-mudding.","aliases":["Shibam","Manhattan of the Desert","Old Walled City of Shibam","Hadhramaut tower houses"],"body":"Shibam, in the Hadhramaut valley of Yemen, is a walled town of about 500 tall mud-brick tower houses packed together on a rise above the wadi floor. Often called the \"Manhattan of the Desert\", it is a UNESCO World Heritage site (the Old Walled City of Shibam) and one of the most striking demonstrations of what sun-dried earth can do as both wall and roof.\n\n## The buildings\n\nThe houses rise five to eleven storeys, with some over 30 m (98 ft) tall, and each floor usually holds one or two rooms. UNESCO describes towers of up to seven storeys rising from the cliff edge. All are of sun-dried mud brick. The walled city in its present form dates from the 16th century, after a flood in 1532-33 partly destroyed an earlier settlement, and many houses have been rebuilt several times since. The settlement itself has pre-Islamic origins and became the Hadhramaut's capital after about AD 300.\n\n## Earth roofs and maintenance\n\nOn a mud-brick tower, the flat roof and the parapets are the parts most exposed to rain and sun. Wind, rain and heat steadily erode the earth surface, so walls must be routinely maintained with fresh layers of mud. A rehabilitation programme run by Yemen's General Organization for the Preservation of Historic Cities (GOPHCY), with German support (GIZ) since 2000, documented 98% of the traditional houses and rehabilitated more than 60% of the private ones.\n\n## Threats\n\n- **Flooding** is the most serious risk. A tropical storm in October 2008 flooded the city, weakening foundations; some buildings later collapsed. The abandonment of the traditional flood-management system has made things worse.\n- **Water and drainage:** piped water without adequate drainage overloads the traditional sanitation systems.\n- **Concrete:** replacing traditional materials with concrete, and new concrete buildings nearby, threaten authenticity.\n- **Conflict:** the city was damaged during the Yemeni civil war, and UNESCO placed Shibam on the List of World Heritage in Danger in 2015.\n\n## Related\n\nSana'a, also on the World Heritage list, has tower houses of rammed earth and fired brick over stone ground floors. Both show that tall earth buildings survive only as long as their roofs and wall heads are cared for.","key_facts":[{"label":"Number of towers","value":"About 500"},{"label":"Height","value":"5-11 storeys; some over 30 m (98 ft)"},{"label":"Material","value":"Sun-dried mud brick"},{"label":"Present town","value":"Largely 16th century onward"},{"label":"Main threat","value":"Flooding and rain erosion"}],"related":["roofing-in-yemen","mud-roof","flat-roof","djenne-earthen-architecture","sahelian-earthen-roofs"],"sources":[{"title":"Old Walled City of Shibam","url":"https://whc.unesco.org/en/list/192","publisher":"UNESCO World Heritage Centre"},{"title":"Shibam","url":"https://en.wikipedia.org/wiki/Shibam","publisher":"Wikipedia"},{"title":"Old City of Sana'a","url":"https://whc.unesco.org/en/list/385","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"shifer","title":"Shifer (Asbestos-Cement Slate)","category":"world-roofing","type":"article","summary":"Shifer is the common Russian and Ukrainian name for corrugated asbestos-cement roofing sheet, the standard rural roof of the Soviet Union and its successor states.","body":"*Shifer* (Russian and Ukrainian шифер) is the everyday name across the former Soviet Union for corrugated asbestos-cement roofing sheet. In English it is often called asbestos slate or asbestos-cement slate. Grey wavy shifer sheets became the standard roof of rural houses, dachas, barns and garages from the Baltic to the Pacific, and huge areas of them remain in place.\n\n## Material\n\nShifer is made of Portland cement reinforced with asbestos fibre. The manufacturing process, which forms thin sheets on a machine adapted from cardboard making, was patented by the Austrian Ludwig Hatschek in 1900 and sold under licence as Eternit. In the former Soviet Union the fibre used was chrysotile from domestic mines.\n\nTypical corrugated sheets, according to a Russian trade guide, include:\n\n- 8-wave sheets of 1,750 by 1,130 mm (69 by 44.5 in), 5-5.8 mm (about 0.2 in) thick, weighing 20-26 kg (44-57 lb).\n- 7-wave sheets of 1.75 by 0.98 m (69 by 39 in), 5.8 mm thick.\n- 6-wave sheets of 2 by 1.125 m (79 by 44 in), 7.5 mm (0.3 in) thick.\n\n## History\n\nAsbestos-cement manufacture in Russia began at Bryansk in 1908. Because Russia and other Soviet republics had very large chrysotile reserves, the chrysotile-cement industry developed most intensively there. The town of Asbest in the Urals, founded in 1889 and renamed in 1928, grew around what is often described as the world's largest chrysotile mine, operated by Uralasbest. Asbestos cement was cheap, light and fire-resistant, and corrugated sheets became the standard roof for rural houses, dachas and farm buildings.\n\n## Today\n\n- **Russia:** consumption of asbestos-cement slate fell by about 28% over 2020-2024 and is now mostly bought for repairs, while metal tile and bitumen products take most of the market for new pitched roofs.\n- **Ukraine:** slate containing chrysotile is still used for house roofs, fences and farm buildings. During the war, environmental groups have warned that asbestos is among the most dangerous wastes in the rubble of damaged buildings and urged people clearing debris to wear protection and dampen dust. A draft law, No. 4142, to prohibit asbestos products passed its first reading.\n- **Poland:** the national programme for removing asbestos products assumes about 14.5 million tonnes of asbestos-containing material, much of it roofing sheet, must be withdrawn from use by 31 December 2032. Warsaw used artificial intelligence on aerial imagery to inventory its remaining asbestos-cement roofs, about 5 ha (12 acres) in total.\n\n## Health and handling\n\nWeathering, breaking, cutting and drilling can release asbestos fibres, which cause asbestosis and mesothelioma. Advice issued in Ukraine for clearing damaged buildings calls for protective clothing, a mask and glasses, wetting the site to limit dust, packing the waste and taking it to designated disposal sites. Asbestos-free fibre cement and corrugated bitumen sheets are now sold as alternatives; in Denmark, for example, asbestos-free fibre cement covers about 8.5% of all roofed area.\n\n## Related names\n\nIn other countries the same product is known as asbestos-cement sheet, AC sheet, fibro or by the trade name Eternit.","key_facts":[{"label":"Material","value":"Cement reinforced with chrysotile asbestos"},{"label":"Typical 8-wave sheet","value":"1,750 x 1,130 mm (69 x 44.5 in), 20-26 kg"},{"label":"Production in Russia","value":"From 1908 (Bryansk)"},{"label":"Russian consumption trend","value":"About -28% over 2020-2024"},{"label":"Poland removal deadline","value":"31 December 2032"}],"regions":["Europe"],"aliases":["шифер","asbestos slate","asbestos-cement slate","corrugated asbestos sheet"],"related":["asbestos-cement-roofing","history-of-asbestos-cement-roofing","fibre-cement-slate","roofing-in-russia","roofing-in-ukraine","roofing-in-poland","roofing-in-belarus","roofing-in-moldova","corrugated-iron"],"company":null,"sources":[{"title":"Shifer volnovoi: kak pravilno vybrat shifer","url":"https://strgid.ru/en/shifer-volnovoi-kak-pravilno-vybrat-shifer-poleznye-sovety","publisher":"Strgid"},{"title":"Construction with Slate – Quick Solution to the Country's Housing Problems","url":"https://vestnik-pp.samgtu.ru/0585-430X/article/view/635982","publisher":"Stroitel'nye Materialy (journal)"},{"title":"Asbest","url":"https://en.wikipedia.org/wiki/Asbest","publisher":"Wikipedia"},{"title":"Ludwig Hatschek","url":"https://en.wikipedia.org/wiki/Ludwig_Hatschek","publisher":"Wikipedia"},{"title":"Roofing materials market (Строительные материалы, оборудование, технологии XXI века, No. 4, 2025)","url":"https://www.techart.ru/files/publications/roofing-materials_pub-2025.pdf","publisher":"Techart marketing group"},{"title":"Ukrainians were explained the main health threat from bombed buildings","url":"https://ecopolitic.com.ua/?p=25391","publisher":"EcoPolitic"},{"title":"Masowe usuwanie szkodliwego azbestu potrwa dłużej niż zakładano?","url":"https://kb.pl/dachy/budowa-dachu/masowe-usuwanie-szkodliwego-azbestu-potrwa-dluzej-niz-zakladano-mamy-komentarz-eksperta/","publisher":"KB.pl"},{"title":"City of Warsaw: artificial intelligence detected asbestos-covered roofs remaining in the city","url":"https://acrplus.org/en/news/news-from-our-members/3532-city-of-warsaw-artificial-intelligence-detected-asbestos-covered-roofs-remaining-in-the-city","publisher":"ACR+"},{"title":"Flere asbestfrie tage i 2025","url":"https://www.dst.dk/nyt/53885","publisher":"Statistics Denmark (Danmarks Statistik)"}],"country":null},{"slug":"shingle-curling","title":"Shingle Curling, Clawing and Cupping","category":"problems-maintenance","type":"term","summary":"Distortion of asphalt shingles in which edges turn up (cupping) or corners and middles lift (clawing), usually from age, heat or moisture.","body":"Curling is the general name for asphalt shingles that no longer lie flat. Roofers and inspectors often split it into two patterns. **Cupping** describes the edges and corners turning upward so the tab forms a shallow dish. **Clawing** describes the middle of the tab lifting while the corners stay down, giving a humped look. Some sources also describe tab edges bending under. Whatever the name, a shingle that has lost its flat profile is more easily caught by wind, more prone to cracking, and may let wind-driven rain under the course above.\n\n## Causes\n\n- **Age and weathering.** As the asphalt loses its oils it shrinks and stiffens, and curling is widely treated as a sign of wear. Older organic-mat shingles are especially prone to it.\n- **Heat and poor attic ventilation.** An overheated, poorly ventilated roof deck can speed up ageing of the asphalt.\n- **Moisture from below.** Damp attics or wet sheathing can make the underside of the shingle expand differently from the sun-baked top.\n- **Installation errors.** High nailing, too few nails, shingles laid over an uneven old roof, or racked (straight-up) installation can leave tabs poorly held.\n- **Manufacturing defects** in some product batches.\n\n## Identification\n\nFrom the ground, curling shows as shadow lines, a ragged texture, or individual tabs that catch the light. Up close, the inspector checks whether the condition is uniform across the roof (pointing to age or ventilation) or limited to certain areas (pointing to installation, a wet spot, or a defective lot). Curled shingles may also be brittle; they can crack if bent or walked on, so inspections should avoid unnecessary foot traffic.\n\n## Remedies\n\nA few curled tabs on an otherwise sound roof can sometimes be re-adhered with roofing cement or replaced. Widespread curling usually means the shingles are near the end of their service life, and the roof is generally planned for replacement. Correcting attic ventilation and moisture problems at that time helps the new roof last.","key_facts":[{"label":"Cupping","value":"Edges and corners turn up"},{"label":"Clawing","value":"Centre of tab lifts, corners stay down"},{"label":"Most common cause","value":"Ageing asphalt; worsened by heat and moisture"}],"regions":["Global","North America"],"aliases":["curled shingles","cupped shingles","clawed shingles"],"related":["asphalt-shingle","roof-ventilation","wind-damage","roof-age-estimation","repair-vs-replace"],"company":null,"sources":[{"title":"Curling asphalt shingle roofs","url":"https://inspectapedia.com/roof/Shingle_Curling.php","publisher":"InspectAPedia"},{"title":"Curling Roof Shingles: What Should I Do?","url":"https://hansons.com/blog/curling-shingles/","publisher":"Hansons"},{"title":"Curling Shingles: Why It Happens And What You Can Do To Fix It","url":"https://www.housedigest.com/2056031/curling-roof-shingles-causes-how-to-fix","publisher":"House Digest"}],"country":null},{"slug":"shingle-exposure-and-offset","title":"Shingle Exposure and Offset","category":"installation","type":"article","summary":"Exposure is the visible height of each shingle course; offset is the horizontal stagger of joints between courses so water never lines up with a gap.","body":"Two layout rules govern how asphalt shingles are laid: **exposure** and **offset**. Exposure is the part of each course left visible to the weather. Offset (also called stagger) is the sideways shift of each course so that joints and cutouts do not line up vertically from one course to the next.\n\n## Exposure\n\nExposure is set by the shingle size and the manufacturer. Typical exposures are 5 in (127 mm) for traditional 12 x 36 in shingles and 5 5/8 in (143 mm) for \"metric\" 13 1/4 x 39 3/8 in shingles. Canadian guidance describes the relationship between exposure and headlap: each course laps the one below by the exposure plus a headlap that is typically 50 mm (2 in). Variable-butt and designer shingles use their own exposure rules.\n\nExposing shingles too much reduces the headlap and can leave nails uncovered; too little wastes material and changes the appearance.\n\n## Offset\n\nThe goal is that a joint or cutout in one course always sits over solid shingle in the course below. Common approaches:\n\n- **Stair-step (diagonal) method.** Each course starts a set distance further along than the one below, repeating after several courses. For traditional 3-tab shingles a 6 in (152 mm) step is common.\n- **Straight-up (racking) method.** Shingles are laid in vertical columns, alternating full and shortened shingles. Canadian guidance alternates full shingles with shingles cut 150 mm (6 in) shorter.\n- **Random offset.** Many laminated shingles allow variable offsets within a minimum set by the manufacturer.\n\nCanadian guidance warns against any layout where joints in successive courses are closer than 100 mm (4 in).\n\n## Chalk lines\n\nRoofers snap horizontal chalk lines every few courses to keep exposure even and vertical lines at the shingle length to keep offsets regular across large or broken roof planes. Valleys, dormers and hips are where layouts most often drift.","key_facts":[{"label":"Traditional 3-tab exposure","value":"5 in (127 mm)"},{"label":"Metric shingle exposure","value":"5 5/8 in (143 mm)"},{"label":"Typical headlap","value":"50 mm (2 in)"},{"label":"Minimum joint spacing (Canada)","value":"100 mm (4 in)"}],"regions":["North America","Global"],"aliases":["shingle stagger","shingle reveal","course offset","racking"],"related":["shingle-nailing-pattern","starter-course","asphalt-shingle","roof-measurement-and-estimating"],"company":null,"sources":[{"title":"Shingle Application Mechanics: Starter Courses, Offsets, Fastener Placement and Wind Sealant Activation","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-application-mechanics","publisher":"Open Exam Prep"},{"title":"Canadian Roofing Reference Manual: 9.1.2 Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-1-asphalt-shingles/9-1-2-installation/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"shingle-wind-rating","title":"Shingle Wind Resistance Ratings","type":"standard","summary":"Test classifications such as ASTM D3161 and ASTM D7158 that indicate how well steep-slope roofing resists wind blow-off.","body":"Shingle wind resistance ratings are laboratory classifications that indicate how well asphalt and other steep-slope roofing products resist being blown off. In North America, two ASTM International test methods dominate product literature and building codes.\n\n## ASTM D3161 (fan-induced method)\n\nASTM D3161 blows a stream of air from a fan across installed test specimens on a deck set at a 2:12 (17 percent) slope, or the lowest slope the manufacturer allows. It applies to discontinuous, air-permeable steep-slope products, including asphalt, polymer, fiber-cement, concrete, clay, metal and photovoltaic shingles. It does not apply to continuous membranes or mechanically seamed metal panels. Products are classified by the fan speed they withstand, with Class F the highest classification. The standard itself notes that results do not directly correlate to wind speeds experienced in service.\n\n## ASTM D7158 (uplift resistance)\n\nASTM D7158, first published in 2005 and adopted into the 2009 International Residential and Building Codes, measures the uplift resistance of the shingle's sealant bond and calculates performance at different design wind speeds. Its classes are:\n\n- **Class D:** up to about 145 km/h (90 mph)\n- **Class G:** up to about 193 km/h (120 mph)\n- **Class H:** up to about 241 km/h (150 mph)\n\n## Use in codes and programs\n\nUS building codes reference these classes for asphalt shingles based on the site's design wind speed. The FORTIFIED Roof standard requires shingles rated ASTM D3161 Class F or ASTM D7158 Class H. Other regions use their own national test methods and design-pressure approaches, so North American shingle classes do not translate directly to products sold elsewhere.\n\n## Limits of ratings\n\nA rating describes a new product installed correctly in a laboratory. Real performance depends on:\n\n- fastener placement in the nailing zone and correct number of nails;\n- whether the sealant strips have bonded (which needs warm weather after installation);\n- edge and starter details;\n- product aging, which can weaken sealant bonds.\n\nPost-storm investigations repeatedly identify misplaced nails and poor starter courses as causes of shingle loss on roofs with rated products.","key_facts":[{"label":"ASTM D3161 top class","value":"Class F"},{"label":"ASTM D7158 Class D","value":"About 145 km/h (90 mph)"},{"label":"ASTM D7158 Class G","value":"About 193 km/h (120 mph)"},{"label":"ASTM D7158 Class H","value":"About 241 km/h (150 mph)"},{"label":"D7158 first published","value":"2005"}],"regions":["North America"],"aliases":["ASTM D3161","ASTM D7158","Class F shingles","Class H shingles","wind-rated shingles"],"related":["wind-uplift","fortified-roof","asphalt-shingle","hurricane-roof-damage"],"sources":[{"title":"ASTM D3161/D3161M-20 Standard Test Method for Wind Resistance of Steep Slope Roofing Products (Fan-Induced Method)","url":"https://store.astm.org/d3161_d3161m-20.html","publisher":"ASTM International"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"From Hurricanes Andrew to Michael: Lessons Learned for Residential Roofing","url":"https://iibec.org/publication-post/from-hurricanes-andrew-to-michael-lessons-learned-for-residential-roofing/","publisher":"IIBEC"},{"title":"FORTIFIED Roof","url":"https://fortifiedhome.org/?p=2512","publisher":"Insurance Institute for Business & Home Safety (FORTIFIED Home)"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"siheyuan-roof","title":"Siheyuan Roof","type":"article","summary":"Ridged, tiled roofs of the siheyuan courtyard houses of Beijing and northern China, with curved eaves and a south-facing main hall.","body":"A *siheyuan* is a traditional Chinese courtyard house in which four buildings enclose a central yard. It is most closely associated with Beijing and northern China. Each of the four buildings has its own pitched, ridged roof, and together the roofs frame the courtyard.\n\n## Layout and orientation\n\nThe four buildings are aligned on north-south and east-west axes. The principal hall stands on the north side facing south, so its roof and eaves receive winter sun while shading the rooms in summer. The entrance gate is usually at the south-east corner.\n\n## Roof form\n\nSiheyuan roofs are gabled and ridged. Gabled roofs are the common type in Chinese domestic building, while hip roofs, with all four sides sloping, were historically reserved for the emperor. Roof form signalled rank: straight, single-slope roofs were the cheapest and common on commoners' houses, multi-slope roofs appeared on higher-status buildings, and dramatically upswept roofs were mostly found on temples, palaces and wealthy homes.\n\nThe ridged roof of a siheyuan helps provide shade in summer and keep warmth in during winter. The eaves curve downward at the edges, so rainwater runs along the curve and drops clear of the walls rather than falling straight down.\n\n## Materials and colour\n\nDomestic roofs used unglazed clay tiles. Glazed yellow tiles, the imperial colour, were reserved for imperial buildings such as those of the Forbidden City, while blue was used at the Temple of Heaven to represent the sky. Ridges on larger halls were weighted with tiles and decorative figures, which both ornamented the roof and held the tiles down.\n\n## Decline and conservation\n\nSince the 1990s many siheyuan have been demolished and replaced by apartment blocks, and many of the survivors are overcrowded with poor facilities. Conservation of Beijing's remaining courtyard houses includes repairing and relaying traditional tile roofs, which are sensitive to leaks and slipped tiles.\n\n## Related forms\n\nCourtyard houses with similar tile roofs are found throughout China, varying with climate: the large, enclosed Fujian tulou of the south-east are one dramatic variant.","key_facts":[{"label":"Region","value":"Beijing and northern China"},{"label":"Form","value":"Four ridged, gabled buildings around a courtyard"},{"label":"Main hall","value":"North side, facing south"},{"label":"Covering","value":"Unglazed clay tiles (glazed yellow reserved for imperial use)"}],"regions":["East Asia"],"aliases":["Courtyard house roof","Chinese courtyard house"],"related":["roofing-in-china","fujian-tulou-roofs","hanok-roof","clay-roof-tile","eaves"],"sources":[{"title":"Siheyuan","url":"https://en.wikipedia.org/wiki/Siheyuan","publisher":"Wikipedia"},{"title":"Chinese architecture","url":"https://en.wikipedia.org/wiki/Chinese_architecture","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"sika","title":"Sika","category":"manufacturers","type":"company","summary":"Sika is a Swiss specialty chemicals company founded in 1910 whose roofing range includes Sarnafil and Sikaplan single-ply membranes and liquid-applied roofing.","body":"Sika AG is a Swiss specialty chemicals company headquartered in Baar, in the canton of Zug. It was founded in Zurich in 1910 by Kaspar Winkler as Kaspar Winkler & Co.. It has grown into a global supplier of construction chemicals, adhesives, sealants and roofing systems, with subsidiaries in more than 100 countries.\n\n## History\n\nSika opened its first foreign subsidiary in southern Germany in 1912. An early reference project was the waterproofing of tunnels on the Gotthard railway line for Swiss Federal Railways around 1918. International expansion into Europe, the Americas and Asia followed from the 1930s. The company is listed on the Swiss stock exchange. A long dispute between the founding Burkard family and the French group Saint-Gobain over control of Sika was settled in 2018. Sika acquired the mortar maker Parex in 2019, and in May 2023 completed the purchase of MBCC Group (the former BASF construction chemicals business), its largest acquisition.\n\n## Roofing\n\nSika's roofing activities sit within its building finishing and envelope range. Its main roofing brands are:\n\n- **Sika Sarnafil**: thermoplastic single-ply roofing membranes.\n- **Sikaplan**: a further line of synthetic single-ply membranes.\n- **SikaRoof MTC**: a liquid-applied membrane system.\n\nSika's wider range of sealants and adhesives is also used around roof penetrations, joints and flashings.\n\n## Single-ply and liquid roofing\n\nThermoplastic membranes such as PVC are joined by hot-air welding of overlapping seams, producing a continuous waterproof layer. Liquid-applied membranes are brushed, rolled or sprayed onto the roof and cure to form a seamless coating, which makes them useful around complex details and penetrations and for overlaying existing roofs.","key_facts":[{"label":"Founded","value":"1910, Zurich"},{"label":"Founder","value":"Kaspar Winkler"},{"label":"Headquarters","value":"Baar, Switzerland"},{"label":"Roofing brands","value":"Sika Sarnafil, Sikaplan, SikaRoof MTC"}],"regions":["Global","Europe","North America"],"aliases":["Sika AG","Sika Sarnafil","Sarnafil"],"related":["pvc-roofing","single-ply-roofing","liquid-applied-roofing","green-roof"],"company":{"founded":"1910","headquarters":"Baar, Switzerland","website":"https://www.sika.com","known_for":["Construction chemicals","Sarnafil PVC membranes","Liquid-applied roofing"]},"sources":[{"title":"Sika AG","url":"https://en.wikipedia.org/wiki/Sika_AG","publisher":"Wikipedia"},{"title":"Sika","url":"https://www.sika.com","publisher":"Sika AG"}],"country":null},{"slug":"silicone-roof-coating","title":"Silicone Roof Coating","category":"low-slope-systems","type":"term","summary":"A high-solids, UV-stable elastomeric coating used for low-slope roof restoration and SPF protection; many products tolerate ponding water.","body":"Silicone roof coatings are elastomeric coatings based on silicone polymers. Most are moisture-curing, high-solids products that build film thickness quickly in one or two coats. Silicone's chemical structure makes it very resistant to ultraviolet light and weathering, so it ages more slowly than many organic coatings.\n\n## Uses\n\n- restoration of single-ply, modified bitumen, BUR and metal roofs\n- protective top coat for spray polyurethane foam roofs\n- areas where some ponding cannot be eliminated\n\n## Advantages\n\n- strong UV and weathering resistance\n- some silicone manufacturers include ponding water in their warranties, unlike most acrylic products\n- high solids content means less shrinkage between wet and dry film\n\n## Limitations\n\n- **Dirt pick-up:** silicone surfaces can attract dirt, reducing reflectance over time.\n- **Recoating:** few materials other than silicone adhere well to cured silicone, so future maintenance generally means more silicone.\n- **Slippery when wet**, and less abrasion-resistant than polyurethanes in high-traffic areas, so walkway paths are often provided.\n- **Adhesion:** some substrates need primers; adhesion tests on site are common.\n\n## Thickness\n\nLike other roof coatings, silicones are specified by dry film thickness; total coating thicknesses on SPF roofs typically range from 0.5 to 1.0 mm (20-40 mils), depending on the manufacturer and warranty length.\n\n## Reflectivity\n\nWhite silicone coatings are used for cool-roof restoration, and their solar reflectance and thermal emittance can be rated by the Cool Roof Rating Council. As with other light-coloured coatings, dirt and biological growth reduce reflectance over time, particularly in warm, humid climates, so periodic cleaning helps maintain performance.","key_facts":[{"label":"Cure","value":"Mostly moisture-curing, high solids"},{"label":"Ponding","value":"Some products warranted for ponding"},{"label":"Main drawback","value":"Dirt pick-up; only silicone adheres well for recoat"}],"regions":["Global","North America"],"aliases":["silicone coating","silicone restoration"],"related":["roof-coating","acrylic-roof-coating","spray-polyurethane-foam-roofing","ponding-water","roof-walkway-pad"],"company":null,"sources":[{"title":"Roof coating","url":"https://en.wikipedia.org/wiki/Roof_coating","publisher":"Wikipedia"},{"title":"RICOWI Roof Guide: Spray Foam","url":"https://ibhs.org/guidance/ricowi-roof-guide-spray-foam/","publisher":"IBHS / RICOWI"},{"title":"Cool roof","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"},{"title":"Cool Roofs","url":"https://www.energy.gov/energysaver/cool-roofs","publisher":"U.S. Department of Energy"}],"country":null},{"slug":"singapore-skyrise-greenery","title":"Singapore Skyrise Greenery","type":"standard","summary":"Singapore's policies and incentives that encourage rooftop and vertical greenery on buildings, including the Skyrise Greenery Incentive Scheme.","body":"Skyrise greenery is Singapore's term for rooftop gardens, green roofs and vertical greenery (green walls) on buildings. As a dense, tropical city-state, Singapore has promoted greenery on buildings to offset land taken by development, and reduce urban heat. Programs are run mainly by the National Parks Board (NParks) and the Urban Redevelopment Authority (URA).\n\n## Skyrise Greenery Incentive Scheme (SGIS)\n\nNParks introduced the SGIS in 2009 to encourage greenery on existing buildings. Under SGIS 2.0, launched in April 2015, the scheme funds up to 50 percent of installation costs, capped at:\n\n- SGD 200 per square metre of planted area for rooftop greenery;\n- SGD 500 per square metre of green coverage for vertical greenery.\n\nFunding is reimbursed after completion and allocated on a first-come, first-served basis. By the time of an NParks review, the scheme had helped green more than 100 existing buildings.\n\n## LUSH programme\n\nThe URA's LUSH (Landscaping for Urban Spaces and High-Rises) programme applies to new developments. It offers gross floor area exemptions to new buildings that incorporate rooftop greenery.\n\n## Scale and targets\n\nNParks reported about 72 hectares of rooftop greenery and 5 hectares of vertical greenery. A 2015 review of the Sustainable Singapore Blueprint set a target of 200 hectares of skyrise greenery by 2030.\n\n## Supporting programs\n\n- **Skyrise Greenery Awards**, held since 2008;\n- **LEAF** (Landscape Excellence Assessment Framework) certification, launched in 2013;\n- **International Skyrise Greenery Conference**, held every two years.\n\n## Design considerations in the tropics\n\nRooftop greenery in Singapore must handle intense tropical rain, high heat and humidity, and strong wind at height. Designers pay particular attention to drainage capacity, wind-resistant planting and anchoring, irrigation, and safe maintenance access.","key_facts":[{"label":"SGIS launched","value":"2009 (SGIS 2.0 in April 2015)"},{"label":"Funding","value":"Up to 50% of installation cost"},{"label":"Rooftop cap","value":"SGD 200 per m²"},{"label":"Vertical cap","value":"SGD 500 per m²"},{"label":"Target","value":"200 ha of skyrise greenery by 2030"}],"regions":["Southeast Asia"],"aliases":["SGIS","LUSH programme","skyrise greenery","Singapore green roofs"],"related":["green-roof","urban-heat-island","toronto-green-roof-bylaw"],"sources":[{"title":"Skyrise Greenery Incentive Scheme","url":"https://skyrisegreenery.nparks.gov.sg/incentive-scheme/about/","publisher":"National Parks Board, Singapore"},{"title":"Journey of Skyrise Greenery in Singapore (CITYGREEN 11)","url":"https://www.nparks.gov.sg/-/media/cuge/ebook/citygreen/cg11/cg11_journey_of_skyrise_greenery_in_singapore.pdf","publisher":"National Parks Board, Singapore"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"single-ply-roofing-association","title":"Single Ply Roofing Association (SPRA)","summary":"SPRA is the UK trade association for the single-ply membrane roofing industry, covering products, installation, training and aftercare.","body":"The Single Ply Roofing Association (SPRA) is a trade association for the single-ply roofing industry in the United Kingdom. Its members include manufacturers of single-ply membranes, specialist roofing contractors and suppliers of related components. Its website is spra.co.uk.\n\n## What single-ply roofing is\n\nSingle-ply roofs use one layer of flexible synthetic membrane to waterproof a flat or low-slope roof. Common materials are PVC, TPO, EPDM and other polymers. The membranes can be mechanically fastened, fully adhered or ballasted, and seams are joined by hot-air welding or by tapes and adhesives depending on the material. In the UK they are widely used on commercial, industrial, education and public buildings, and increasingly on homes with flat roofs.\n\n## Activities\n\n- **Technical guidance.** SPRA members monitor, develop and report on new technology for single-ply products, installation methods and aftercare. The association produces technical resources for designers and contractors.\n- **Training.** SPRA runs and supports training programmes, courses and qualifications for installers and is working to make training more accessible and affordable.\n- **Standards.** Single-ply products in the UK are tested and declared against European standards such as EN 13956 (flexible sheets for roof waterproofing). SPRA represents the sector in UK standards and regulation discussions, including fire performance of roof systems.\n\n## Relationship to other bodies\n\nSPRA is separate from the U.S. trade association SPRI, which develops ANSI standards for the North American single-ply market. In the UK, SPRA works alongside other roofing associations such as the National Federation of Roofing Contractors and the Liquid Roofing and Waterproofing Association.\n\n## For building owners\n\nMembership in a trade association like SPRA indicates that a contractor or manufacturer has chosen to join an industry body; it is not a licence. Owners should ask about installer training, manufacturer approval and the warranty terms offered for the roof system.","key_facts":[{"label":"Country","value":"United Kingdom"},{"label":"Sector","value":"Single-ply membrane roofing"},{"label":"Members","value":"Manufacturers, contractors, suppliers"},{"label":"Website","value":"spra.co.uk"}],"regions":["Europe"],"aliases":["SPRA"],"related":["single-ply-roofing","spri","national-federation-of-roofing-contractors","epdm-roofing","tpo-roofing"],"company":{"website":"https://www.spra.co.uk","known_for":["UK single-ply roofing guidance and training"]},"sources":[{"title":"Single Ply Roofing Association","url":"https://www.spra.co.uk/","publisher":"SPRA"},{"title":"NFRC home page","url":"https://www.nfrc.co.uk/","publisher":"NFRC"}],"category":"organizations","type":"organization","country":null},{"slug":"single-ply-membrane-recycling","title":"Single-Ply Membrane Recycling","type":"article","summary":"Collection and recycling of PVC, TPO and other thermoplastic roofing membranes, including Europe's Roofcollect scheme.","body":"Single-ply membrane recycling is the recovery of flat-roof waterproofing sheets, mainly thermoplastics such as PVC (polyvinyl chloride) and TPO (thermoplastic polyolefin), so the material can be reprocessed into new products. Thermoplastics can be melted and reformed, which makes them more readily recyclable than thermoset membranes such as EPDM rubber.\n\n## Roofcollect in Europe\n\nRoofcollect is a collection and recycling system set up by ESWA, the European Single Ply Waterproofing Association, to recover end-of-life waterproofing membranes. It organizes collection in most European countries. Recovered thermoplastic membrane can be reprocessed into new products. Separately, the European PVC industry's VinylPlus programme works on collection and recycling of PVC more broadly.\n\n## Sources of material\n\n- **Installation offcuts and trimmings**, which are clean and easiest to recycle.\n- **Tear-off membranes** from reroofing projects, which may be contaminated with adhesives, dirt, ballast or insulation facers.\n\n## TPO\n\nTPO membranes are blends of a thermoplastic (such as polypropylene or polyethylene), an elastomer or rubber, and usually a mineral filler such as talc. They are widely used in roofing because they resist UV degradation. As a thermoplastic, TPO can in principle be remelted and reprocessed, although post-consumer collection is less established than for metals.\n\n## Challenges\n\n- **Contamination** from adhesives, coatings and attached insulation reduces recycled quality.\n- **Additives** such as plasticizers, stabilizers and fillers vary between products and ages, which can complicate reprocessing.\n- **Logistics:** large, light rolls of used membrane are costly to transport.\n- **Overlay versus tear-off:** where codes and roof conditions allow, recovering an existing membrane rather than removing it avoids waste altogether.\n\n## Related approaches\n\nLong service life, repairability and roof designs that allow layers to be separated at end of life all help reduce membrane waste.","key_facts":[{"label":"Recyclable membrane types","value":"Thermoplastics: PVC, TPO"},{"label":"European scheme","value":"Roofcollect, set up by ESWA"},{"label":"Main challenge","value":"Contamination of tear-off membranes"}],"regions":["Europe","North America","Global"],"aliases":["Roofcollect","PVC membrane recycling","TPO recycling","roof membrane recycling"],"related":["roofing-waste","pvc-roofing","tpo-roofing","epdm-roofing","embodied-carbon-roofing"],"sources":[{"title":"Roofcollect","url":"https://www.roofcollect.com/","publisher":"ESWA / Roofcollect"},{"title":"VinylPlus","url":"https://www.vinylplus.eu/","publisher":"VinylPlus"},{"title":"Thermoplastic polyolefin","url":"https://en.wikipedia.org/wiki/Thermoplastic_polyolefin","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"single-ply-roofing","title":"Single-Ply Roofing","category":"low-slope-systems","type":"article","summary":"Low-slope roofing that uses one layer of factory-made polymer sheet, such as TPO, PVC, EPDM or PIB, joined at seams and held by ballast, fasteners or adhesive.","body":"Single-ply roofing is a family of low-slope waterproofing systems in which the membrane is a single layer of flexible, factory-made polymer sheet rather than several plies built up on site. Sheets are joined at overlapping seams by heat welding (thermoplastics) or by tapes and adhesives (thermosets), and are secured by ballast, mechanical fasteners or adhesives.\n\n## Main families\n\n- **Thermoplastics** soften when heated, so seams can be hot-air welded: PVC, KEE (ketone ethylene ester) blends, TPO and FPO (flexible polyolefin), and PIB (polyisobutylene).\n- **Thermosets** are cured (vulcanised) rubber that cannot be re-melted: EPDM is the dominant example; CSPE (Hypalon) was another until it was discontinued.\n\n## History and market\n\nPVC sheets were first installed in Europe in the early 1960s and EPDM entered US commercial roofing in the same decade. Single-ply use grew rapidly in North America in the 1970s and 1980s as bitumen prices rose and labour became scarce. TPO followed from 1989 and became the most widely installed low-slope covering in the US by the 2010s. In the UK the products are often called \"polymeric single ply\" and are typical on warehouses, factories and distribution centres.\n\n## Attachment methods\n\n- **Ballasted:** loose-laid sheet held down by stone or pavers.\n- **Mechanically attached:** fasteners and plates in the seams or through the sheet, or induction-welded plates.\n- **Fully adhered:** bonded across the whole underside with adhesive, or via a fleece backing.\n\n## Advantages and limitations\n\nSingle-ply membranes are light, fast to install over large areas and available in white for cool-roof performance. Their main vulnerabilities are workmanship at seams and details, puncture from traffic or hail, and, for some thermoplastics, long-term loss of plasticisers or surface coating.\n\n## Organisations\n\nIndustry bodies include SPRI in the US (founded 1981), which writes ANSI/SPRI standards on wind design, edge systems and ballast, and the Single Ply Roofing Association in the UK.","key_facts":[{"label":"Main thermoplastics","value":"PVC, TPO, KEE, PIB, FPO"},{"label":"Main thermoset","value":"EPDM"},{"label":"Attachment","value":"Ballasted, mechanically attached, fully adhered"},{"label":"US trade body","value":"SPRI (since 1981)"},{"label":"UK trade body","value":"Single Ply Roofing Association"}],"regions":["Global","North America","Europe"],"aliases":["single ply","polymeric membrane","single-ply membrane"],"related":["tpo-roofing","pvc-roofing","epdm-roofing","pib-roofing-membrane","kee-roofing-membrane","ballasted-roof-system","mechanically-attached-roof-system","fully-adhered-roof-system"],"company":null,"sources":[{"title":"Cool Roofs","url":"https://www.energy.gov/energysaver/cool-roofs","publisher":"U.S. Department of Energy"},{"title":"Technical Details: Thermoset Membranes - EPDM Technology and Repair","url":"https://roofingcontractor.com/articles/85516-technical-details-thermoset-membranes-epdm-technology-and-repairp","publisher":"Roofing Contractor"},{"title":"The ABCs of PVC Roof Membranes","url":"https://usa.sika.com/dms/getdocument.get/88a0c83a-9151-4100-84d6-dccadfebd4aa/the-abcs-of-pvc-roof-membranes.pdf","publisher":"Sika USA"},{"title":"Thermoplastic Polyolefin (TPO) Roofing Systems","url":"https://buildings.com/articles/35297/thermoplastic-polyolefin-tpo-roofing-systems","publisher":"Buildings"},{"title":"SPRI - Single Ply Roofing Industry","url":"https://www.spri.org/","publisher":"SPRI"},{"title":"Single Ply Roofing Association","url":"https://www.spra.co.uk/","publisher":"SPRA"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"}],"country":null},{"slug":"skara-brae-roofs","title":"Skara Brae and Neolithic Orkney Roofs","category":"history","type":"place","summary":"The debate over how the stone houses of Skara Brae, Orkney, were roofed, and the sandstone roof slabs found at the nearby Ness of Brodgar.","body":"Skara Brae is a Neolithic village on the Bay of Skaill in Orkney, Scotland, occupied from about 3180 to 2500 BCE. A severe storm in the winter of 1850 stripped earth from a mound and exposed the outlines of several roofless stone houses. Their stone walls and furniture survive remarkably well, but the roofs do not, and how they were covered has been debated for a century. Skara Brae is part of the Heart of Neolithic Orkney World Heritage Site, inscribed in 1999.\n\n## The village\n\nTen structures and four passageways are visible. Seven houses share a similar arrangement of stone furniture, and drains run under at least five. House 8 stands apart, with walls over 2 m (6.6 ft) thick and a porch.\n\n## Roofing theories\n\n- **Perishable roofs:** because nothing obvious survived, roofs were long assumed to be of whalebone or timber beams covered with turf, skins, seaweed thatch or straw. Whalebone does occur at the site, though as tools and beads, and driftwood is thought to have been burned as fuel.\n- **Corbelled stone:** after excavating in 1929-1930, V. Gordon Childe considered beehive-like corbelled roofs, but there was not enough rubble to have covered the full span.\n- **Stone slabs:** Childe also recorded thin slates on top of floor flagstones that broke underfoot, and broken slates among bone and shell on the floor of House 7. At Rinyo on Rousay in 1938, excavators found a layer of thin slabs on floors and interpreted it as a collapsed roof. These observations were largely overlooked.\n\n## The Ness of Brodgar evidence\n\nIn 2010, excavators at the Ness of Brodgar found what they describe as Orkney's first real evidence of a Neolithic roof, in Structure Eight. Trimmed rectangular sandstone slabs lay on the floor deposits and were first taken for paving. Similar tiles were later found in Structures One, Ten, Twelve and Twenty-Seven.\n\n- **Size:** 38-57 cm (15-22 in) long, 23-40 cm (9-16 in) wide and 1.3-2.7 cm (0.5-1 in) thick.\n- **Fixing:** none had peg holes. The slabs were probably laid on a timber frame, largest at the eaves and smallest near the ridge, held by their own weight and perhaps bedded or sealed with white clay found among them.\n- **Frame:** no internal post holes were found, so the frame probably rested on the wall tops. One calculation put the ridge up to about 4 m (13 ft) above the wallhead, close to 6 m (20 ft) above ground.\n- **Collapse:** the pattern of fallen slabs suggests one section of roof fell in a single event.\n\nNot every Ness building was stone-roofed. The excavators suggest some Skara Brae houses may have been as well, though this remains a possibility rather than a demonstrated fact.\n\n## Continuity\n\nOrcadian builders went on using stone slab roofs into the 20th century, so the Neolithic evidence connects with a long local tradition of flagstone roofing.","key_facts":[{"label":"Occupation","value":"About 3180-2500 BCE"},{"label":"Exposed","value":"Storm of winter 1850"},{"label":"World Heritage","value":"Heart of Neolithic Orkney, 1999"},{"label":"Ness of Brodgar slabs","value":"38-57 x 23-40 cm (15-22 x 9-16 in), 1.3-2.7 cm thick"},{"label":"Status","value":"Skara Brae roof covering unresolved"}],"regions":["Europe"],"aliases":["Skara Brae","Ness of Brodgar roof","Orkney Neolithic roofs"],"related":["prehistory-of-roofing","lauze","sod-roof","thatch","bronze-age-roundhouse"],"company":null,"sources":[{"title":"Skara Brae","url":"https://en.wikipedia.org/wiki/Skara_Brae","publisher":"Wikipedia"},{"title":"Neolithic roof tiles","url":"https://www.nessofbrodgar.co.uk/neolithic-roof-tiles/","publisher":"Ness of Brodgar Excavation"},{"title":"Skara Brae - the houses","url":"https://nessofbrodgar.co.uk/skarabrae-houses","publisher":"Ness of Brodgar Excavation"}],"country":null},{"slug":"skilled-trades-ontario","title":"Skilled Trades Ontario","summary":"Skilled Trades Ontario is the provincial agency that runs apprenticeship programs, trade exams and Certificates of Qualification in Ontario, Canada.","body":"Skilled Trades Ontario is an agency of the Government of Ontario, Canada, responsible for apprenticeship and trade certification. It was established under the *Building Opportunities in the Skilled Trades Act, 2021* and operates under the province's Ministry of Labour, Immigration, Training and Skills Development. Its website is skilledtradesontario.ca.\n\n## Role\n\nSkilled Trades Ontario:\n\n- develops and maintains apprenticeship programs and training standards for more than 140 skilled trades in Ontario;\n- schedules and administers trade certification exams;\n- issues Certificates of Qualification in all trades that have a certifying exam, and renews them in compulsory trades;\n- keeps a Public Register of people authorised to work in compulsory trades;\n- assesses experienced workers who want to challenge a trade exam.\n\nCompliance and enforcement of trade rules, such as inspections of job sites, are handled by the provincial ministry rather than by the agency itself.\n\n## Compulsory and voluntary trades\n\nOntario divides trades into **compulsory** trades, where a person must hold a Certificate of Qualification or be a registered apprentice to do the work, and **non-compulsory** (voluntary) trades, where certification is available but not legally required. Whether a particular trade is compulsory can be checked on the agency's trade information pages.\n\n## Relevance to roofing\n\nRoofing in Ontario is taught through apprenticeship and college programs, and roofers can earn a Certificate of Qualification after passing the trade exam. Consumers checking a roofer may ask whether the workers hold certificates or are registered apprentices, and may look up compulsory trade holders on the Public Register. Separate from trade certification, roofing contractors may also need municipal business licences, building permits for certain work and coverage with Ontario's workplace safety insurance board.\n\n## Other provinces\n\nEach Canadian province and territory runs its own apprenticeship authority, for example SkilledTradesBC in British Columbia. The interprovincial Red Seal program allows qualified tradespeople in designated trades to work across provinces. Trade associations such as the Canadian Roofing Contractors Association are separate and voluntary.","key_facts":[{"label":"Legal basis","value":"Building Opportunities in the Skilled Trades Act, 2021"},{"label":"Jurisdiction","value":"Ontario, Canada"},{"label":"Trades covered","value":"More than 140"},{"label":"Issues","value":"Certificates of Qualification; Public Register for compulsory trades"}],"regions":["North America"],"aliases":["STO"],"related":["how-to-find-a-licensed-roofer","canadian-roofing-contractors-association","roofing-apprenticeship"],"company":{"website":"https://www.skilledtradesontario.ca","known_for":["Ontario apprenticeship and trade certification"]},"sources":[{"title":"About us","url":"https://www.skilledtradesontario.ca/about-us/","publisher":"Skilled Trades Ontario"},{"title":"Skilled Trades Ontario home page","url":"https://www.skilledtradesontario.ca/","publisher":"Skilled Trades Ontario"}],"category":"organizations","type":"organization","country":null},{"slug":"skip-sheathing","title":"Skip Sheathing (Spaced Sheathing)","category":"components","type":"term","summary":"Skip sheathing is roof decking made of boards laid with gaps between them, traditionally used under wood shingles and shakes to let them dry.","body":"Skip sheathing, also called spaced sheathing or open sheathing, is a roof deck made of individual boards nailed across the rafters with open gaps between them rather than as a solid surface. It is the traditional substrate for wood shingles and shakes in North America, where the open spaces allow air to reach the underside of the wood so it can dry after rain, which helps reduce decay.\n\n## How it is laid out\n\nThe boards are set at intervals related to the exposure of the shingles or shakes so that every course has a board to nail into. Because the deck is open, the attic below is visible through the gaps on older houses.\n\n## Relation to battens\n\nSkip sheathing is the North American equivalent of the roof battens used in Britain, Europe, Australia and New Zealand to hang tiles and slates. Both provide spaced fixing points; battens are usually smaller-section strips and are often laid over an underlay and sometimes counter-battens.\n\n## Issues when re-roofing\n\nWhen an old wood roof on skip sheathing is replaced with asphalt shingles or other materials that need a continuous deck, the usual practice is to cover the skip sheathing with structural panels such as plywood or OSB, or to fill the gaps with boards. Manufacturers of most modern roof coverings specify a solid deck. Some metal roofing systems can be fixed to spaced battens or purlins instead.\n\nThe open boards also provide less diaphragm stiffness than a solid panel deck, which can be relevant in high-wind and seismic upgrades.\n\n## Note\n\nExact board widths, spacing and nailing for skip sheathing are set by the shingle or shake manufacturer and local code, and vary by product.","key_facts":[{"label":"Typical covering","value":"Wood shingles and shakes"},{"label":"Purpose of gaps","value":"Ventilation and drying"},{"label":"UK/AU equivalent","value":"Battens"}],"regions":["North America"],"aliases":["spaced sheathing","open sheathing","skip decking"],"related":["roof-sheathing","roof-battens"],"company":null,"sources":[{"title":"Batten","url":"https://en.wikipedia.org/wiki/Batten","publisher":"Wikipedia"},{"title":"Inspecting Roof Panel Sheathing","url":"https://nachi.org/inspect-roof-sheathing.htm","publisher":"InterNACHI"}],"country":null},{"slug":"skylight","title":"Skylight and Roof Window","category":"components","type":"article","summary":"A skylight is a glazed opening in a roof that admits daylight; an opening skylight within reach of occupants is usually called a roof window.","body":"A skylight (in the UK often called a rooflight) is a light-transmitting unit that forms part of a roof, admitting daylight and sometimes ventilation. Open roof apertures date back to antiquity, such as the oculus of the Pantheon in Rome; sealed glazed skylights became practical with improvements in glass manufacture during the Industrial Revolution, and mass production since the mid-20th century made them common in houses.\n\n## Types\n\n- **Fixed skylight:** a frame holding glazing that does not open.\n- **Venting (operable) skylight:** a hinged sash that opens for ventilation. When it is within occupants' reach in a sloping roof, it is generally called a roof window, a term used widely in Europe.\n- **Tubular daylighting device (sun tunnel):** a small roof dome, about 10 in (250 mm) in diameter for homes, connected to a reflective tube that delivers light to a ceiling diffuser.\n- **Sloped glazing and glazed roof systems:** larger multi-panel assemblies.\n- **Domed rooflights:** acrylic or polycarbonate domes, typical on flat roofs.\n\n## Installation and flashing\n\nSkylights interrupt the roof covering, so they are flashed much like a chimney: a sill or apron flashing at the bottom, step or side flashings along the sides, and a head flashing at the top, generally using the manufacturer's flashing kit. Self-adhered membrane is commonly used around the opening. Under the US IRC, skylights on roofs with a slope below 3:12 must be mounted on a curb at least 4 in (102 mm) above the roof plane unless the manufacturer specifies otherwise. Sealant alone should not be relied on.\n\n## Glazing and energy\n\nContemporary units usually use sealed double glazing, often with low-emissivity coatings and gas fills; triple glazing is used in the coldest climates. In the US, performance is rated by U-factor (heat loss) and solar heat gain coefficient (SHGC), both expressed from 0 to 1 with lower values meaning less heat transfer.\n\n## Building rules\n\nCodes govern the type of glazing used overhead, protection against falling glass, and in some jurisdictions fire separation distances. Large skylights may need structural framing around the opening.","key_facts":[{"label":"UK term","value":"Rooflight"},{"label":"Low-slope curb (IRC)","value":"At least 4 in (102 mm) below 3:12"},{"label":"Tubular device dome","value":"About 10 in (250 mm) residential"}],"regions":["Global"],"aliases":["rooflight","roof window","sun tunnel","tubular skylight"],"related":["dormer","roof-flashing","apron-flashing","chimney-cricket","sawtooth-roof"],"company":null,"sources":[{"title":"Skylight","url":"https://en.wikipedia.org/wiki/Skylight","publisher":"Wikipedia"},{"title":"Chimneys & Crickets, Skylights, Pipes, Flues, Exhaust Vents & Solar","url":"https://open-exam-prep.com/study-guides/mi-roofing-contractor/flashings-penetrations/chimney-crickets-skylights-penetrations","publisher":"Open Exam Prep"}],"country":null},{"slug":"skylight-flashing-installation","title":"Skylight Flashing Installation","category":"installation","type":"article","summary":"Skylight flashing seals a roof window or skylight to the roof using a head flashing, side step flashings and a sill apron, usually from a manufacturer's kit.","body":"A **skylight** or **roof window** creates a large opening in the roof plane that must be sealed on all four sides. The flashing approach follows the same logic as a chimney: water from above must be diverted around the unit, water at the sides must be shed course by course, and water at the bottom must be carried back out onto the roofing.\n\nMost modern units are installed with a **manufacturer's flashing kit** matched to the roof covering (low-profile kits for shingles and slate, deeper kits for profiled tiles). Following the kit instructions is usually a condition of the product warranty.\n\n## Typical components\n\n- **Sill (apron) flashing.** Fitted first at the bottom of the unit and laid over the course below.\n- **Side flashings.** Either step flashings woven into each course, as at a sidewall, or continuous side pieces for tile.\n- **Head flashing.** At the top, tucked under the roofing above so water is carried around the unit.\n- **Underlayment collar.** Many manufacturers supply a self-adhered or pleated underlay collar that seals the frame to the roof underlayment before the metal flashings go on.\n\n## General sequence\n\n1. Frame the opening and fasten the unit to the deck with the supplied brackets.\n2. Seal the frame to the underlayment with the collar or a self-adhered membrane, lapped so water flows over it.\n3. Install the sill flashing over the course below.\n4. Shingle up the sides, inserting step flashings with each course; each piece extends onto the roof and up the frame.\n5. Install the head flashing and continue the roofing above it.\n6. Leave a clear gap between the roofing and the head flashing so debris can wash out.\n\n## Considerations\n\nCanadian guidance on roof penetrations warns against exposed fastener heads and recommends sealing any that remain with compatible sealant. Wide skylights may need a small diverter or cricket above the unit, as with chimneys. Condensation on the inside of older skylights is sometimes mistaken for a leak.","key_facts":[{"label":"Main parts","value":"Sill apron, side step flashings, head flashing"},{"label":"Common approach","value":"Manufacturer-supplied flashing kit"},{"label":"Underlay detail","value":"Collar or self-adhered membrane around frame"}],"regions":["Global"],"aliases":["roof window flashing","skylight installation"],"related":["step-flashing-installation","chimney-flashing-installation","skylight","roof-flashing"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.4.1 Intersection of Shingle Roofing and Masonry","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-1-intersection-of-shingle-roofing-and-masonry/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 9.4.3 Intersection of Roofing and Wall Cladding","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-3-intersection-of-roofing-and-wall-cladding-other-than-masonry/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 9.4.4 Vent Pipes","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-4-vent-pipes/","publisher":"Canadian Roofing Contractors Association"},{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"}],"country":null},{"slug":"slate-cutter","title":"Slate Cutter","category":"tools-equipment","type":"term","summary":"A lever-action shear, often called a guillotine, that trims roofing slates to size and may also punch nail holes.","body":"A slate cutter is a hand-operated shear used to trim natural or fibre-cement slates to size. Most designs work like a small guillotine: the slate is placed on a fixed bed against a straight edge, and a long lever brings down a blade that snaps or shears the slate along the line. Many cutters also include a punch for making nail holes, so one tool handles both trimming and holing.\n\n## Uses\n\n- Cutting slates at valleys, hips, verges, abutments and around penetrations.\n- Producing half slates and slate-and-a-half widths at verges.\n- Punching nail holes in slates that arrive without them, or when a slate is re-holed for repairs.\n- Trimming fibre-cement and some synthetic slates, depending on the product.\n\n## Compared with traditional hand methods\n\nBefore mechanical cutters, slaters trimmed slates with a slater's hammer or zax over a bench iron, stake or slater's anvil, striking along the edge to dress it. These hand methods produce the bevelled or chamfered edges characteristic of traditional slating and remain in use, particularly on heritage work. Guillotine cutters are faster and easier to learn, and are common on new roofs and among general roofers. Patents for lever-action slate cutters date back to the 19th century.\n\n## Choosing and using\n\nCutters vary in blade length, which determines the largest slate width that can be cut in one stroke, and in whether they have a built-in punch and measuring guides. A sharp blade and firm support for the slate give cleaner cuts. Cutting from the back of the slate usually produces a better bevel on the visible face, following the same convention as hand dressing. Eye protection is advisable, as small fragments can fly.\n\n## Related tools\n\nSlate rippers remove damaged slates; slater's hammers and zaxes trim and hole by hand; angle grinders with diamond blades are used for some cuts, though they create silica-containing dust that needs control.","key_facts":[{"label":"Action","value":"Lever-operated guillotine shear"},{"label":"Extra function","value":"Nail-hole punch on many models"},{"label":"Traditional alternative","value":"Slater's hammer or zax over a bench iron"}],"regions":["Global","Europe","North America"],"aliases":["slate guillotine","slate shear","slate trimmer"],"related":["slaters-hammer","slate-ripper","natural-slate","tile-cutting"],"company":null,"sources":[{"title":"Roofers' slate tools","url":"https://www.cupapizarras.com/uk/news/roofers-slate-tools/","publisher":"Cupa Pizarras"},{"title":"Slate Cutters","url":"https://www.tooled-up.com/slate-cutters/cat/781/","publisher":"Tooled-Up"},{"title":"US552364A - Slate-cutter","url":"https://patents.google.com/patent/US552364A/en","publisher":"Google Patents"}],"country":null},{"slug":"slate-delamination","title":"Slate Delamination","category":"problems-maintenance","type":"term","summary":"The splitting and flaking of roofing slate into thin layers as it weathers, marking the end of an individual slate's service life.","body":"Delamination is the separation of a roofing slate into layers along its natural cleavage planes. As slate weathers, the surface can flake, spall, soften and split, and eventually individual slates break or crumble. It is one of the main ways slate wears out, alongside fixing failure (see nail sickness).\n\n## Why it happens\n\nSlate is a metamorphic rock that splits into thin sheets along cleavage planes, which is what makes it useful for roofing. Its durability varies greatly by geological source. Some slates contain minerals, such as certain carbonates or iron sulfides, that react with water and air, expand and break the slate apart. Repeated wetting and drying, freeze-thaw cycles and acidic pollution speed up the process. Softer slates may last far less time than hard, dense slates; heritage guidance in the UK and Ireland stresses that the service life depends heavily on the quarry and on matching like with like. Testing standards such as EN 12326 in Europe and ASTM C406 in North America are used to classify slate durability.\n\n## Signs\n\n- Flaking or powdery surfaces, often worse at the exposed lower part of the slate.\n- Slates that sound dull rather than ringing when tapped.\n- Edges that crumble, and slates that break when handled.\n- Softening around nail holes, causing slates to slip.\n- Rust-coloured staining from oxidising pyrite in some slates.\n\n## Assessment and repair\n\nConservation bodies such as Historic Environment Scotland, Cadw and national parks authorities recommend regular inspection and timely replacement of individual defective slates with matching slate of similar size, colour, thickness and durability. When a large proportion of slates are delaminating, the roof is usually stripped and reslated, salvaging sound slates for reuse where possible and making up the shortfall with compatible new or reclaimed slate. Mixing poor-quality substitutes into a historic roof can shorten its life and change its appearance. Walking on slate roofs damages them and should be avoided; access is normally by ladders, hooks and roof ladders.","key_facts":[{"label":"Process","value":"Splitting along cleavage planes as slate weathers"},{"label":"Accelerated by","value":"Reactive minerals, freeze-thaw, pollution"},{"label":"Durability standards","value":"EN 12326 (Europe), ASTM C406 (North America)"}],"regions":["Global","Europe","North America"],"aliases":["slate spalling","flaking slate","slate decay"],"related":["natural-slate","nail-sickness","slate-ripper","slaters-hammer","repair-vs-replace"],"company":null,"sources":[{"title":"Repairing Scottish Slate Roofs","url":"https://www.buildingconservation.com/articles/scottish-slate-roofs/scottish-slate-roofs.htm","publisher":"Building Conservation Directory"},{"title":"Roofs","url":"https://cadw.gov.wales/roofs","publisher":"Cadw"},{"title":"Tile and slate roofing","url":"https://www.newforestnpa.gov.uk/document/tile-and-slate-roofing/","publisher":"New Forest National Park Authority"},{"title":"A stitch in time: slate and stone roof coverings","url":"https://ihbc.org.uk/caring/elements/roofCoverings/slatestone/","publisher":"Institute of Historic Building Conservation"}],"country":null},{"slug":"slate-hook-fixing","title":"Slate Hook Fixing","type":"term","category":"installation","summary":"A method of securing roofing slates with metal hooks that grip the slate's tail, as an alternative to nailing through holes near the head or centre.","body":"Slate hook fixing is a way of fastening natural or fibre-cement slates to roof battens using small metal hooks instead of nails. Each hook is fixed to the batten (or driven into it) in the gap between two slates of the course below, and its lower end curls up to hold the bottom edge, or tail, of the slate above. The traditional alternative is nail fixing, where each slate is holed and nailed near its head or centre.\n\n## Origins\n\nEarly slates were hung on wooden pegs. Two traditions developed from this: in Britain, nails replaced the pegs, while on the European continent S-shaped metal hooks were adopted. Hook fixing is widespread on the continent, and in the UK it is common in exposed areas such as Scotland, Cumbria, Wales, Devon and Cornwall.\n\n## Advantages\n\n- **Wind resistance**: the hook holds the tail of the slate, which is where wind lift starts, and locks neighbouring slates together.\n- **Lower pitches**: suppliers state that hook fixing can be used below 20° pitch, where nailing is not recommended.\n- **Narrow slates**: nailed slates need a margin of about 25 mm (1 in) between hole and edge, which limits them to a minimum width of about 150 mm (6 in); hooked slates can be as narrow as about 100 mm (4 in).\n- **No holing**: slates do not need to be holed on site, saving labour and waste.\n- **Repairs**: a single broken slate can be slid out and replaced, and a slate that cracks across its width stays in place.\n- **No nail sickness**: corroded nails are a common cause of slipped slates on old nailed roofs.\n\n## Disadvantages\n\nThe hook ends are visible on the roof surface, giving a less smooth appearance than a nailed roof, where every nail is covered by the slates above.\n\n## Hook materials\n\nHooks are usually stainless steel, often supplied with a black coating to reduce their visibility. UK industry commentators have recommended grade 316 stainless rather than 304 near the coast, after reports of rusting in salty air.\n","key_facts":[{"label":"Alternative to","value":"Nail fixing (head- or centre-nailing)"},{"label":"Minimum slate width","value":"About 100 mm (4 in) hooked vs 150 mm (6 in) nailed"},{"label":"Common hook material","value":"Stainless steel (grade 316 near coasts)"}],"regions":["Europe"],"aliases":["slate clip","tail hook","hook fixing","slate hooks","tingle (hook)","crochet d'ardoise","Slate Hook"],"related":["slate-repair","slate-roof-installation","natural-slate","slate-ripper","spanish-slate","fibre-cement-slate","nail-sickness"],"sources":[{"title":"How Are Slate Roofs Attached? Nails, Hooks, and More","url":"https://engineerfix.com/how-are-slate-roofs-attached-nails-hooks-and-more/","publisher":"Engineer Fix"},{"title":"Slate Roof Repair","url":"https://www.slateassociation.org/slate-roof-repair/","publisher":"National Slate Association"},{"title":"Hook vs nail fixing: the facts","url":"https://www.ssqgroup.com/technical-articles/hook-vs-nail-fixing-the-facts","publisher":"SSQ"},{"title":"Should I nail or hook fix natural roofing slates?","url":"https://www.jrcslate.co.uk/should-i-nail-or-hook-fix-natural-roofing-slates/","publisher":"JRC Slate"},{"title":"Roofing: Quality shows","url":"https://www.stonespecialist.com/news/roofing-quality-shows","publisher":"Natural Stone Specialist"}],"company":null,"country":null},{"slug":"slate-landscape-of-northwest-wales","title":"Slate Landscape of Northwest Wales","category":"history","type":"place","summary":"A UNESCO World Heritage Site inscribed in 2021, recognising the Gwynedd slate quarries that roofed much of the world from 1780 to 1940.","body":"The **Slate Landscape of Northwest Wales** was inscribed on the UNESCO World Heritage List on 28 July 2021, at the 44th session of the World Heritage Committee (reference 1633). It recognises the quarries, mines, settlements and transport routes of the Welsh slate industry in Gwynedd.\n\n## What it covers\n\nThe property is made up of six component areas across the mountains of Snowdonia (Eryri) and the valleys and coast around them. They include major quarrying centres such as **Penrhyn** near Bethesda and **Dinorwig** near Llanberis, and other slate districts with their villages, chapels, railways, inclines and harbours.\n\n## Why it was listed\n\nUNESCO accepted the site under two criteria:\n\n- **Criterion (ii):** the landscape shows an interchange of developments in technology and architecture. Welsh quarrying methods and skilled workers were exported from the 1780s into the early 20th century, notably to slate industries in the United States, continental Europe and Ireland.\n- **Criterion (iv):** it illustrates how an agricultural upland was transformed by industry during the Industrial Revolution.\n\nUNESCO frames the industry's period of global dominance as **1780 to 1940**. By the late 19th century the region produced about a third of the world's roofing slates and architectural slabs.\n\n## Roofing significance\n\nWelsh slate roofed terraced houses, factories and grand buildings during rapid urban growth, in Britain and abroad. Its light, thin, regular slates also encouraged the shallow-pitched roofs typical of Georgian architecture. The inscription is one of very few World Heritage Sites defined chiefly by the production of a roofing material.\n\n## Management\n\nGwynedd Council leads the management of the site with partners. Slate is still quarried in the area, notably at Penrhyn, and the landscape includes active workings alongside heritage sites such as the National Slate Museum in Llanberis.","key_facts":[{"label":"Inscribed","value":"28 July 2021 (44th session)"},{"label":"Reference","value":"1633"},{"label":"Criteria","value":"(ii) and (iv)"},{"label":"Component areas","value":"Six"},{"label":"Period of dominance","value":"1780-1940"}],"regions":["Europe"],"aliases":["Welsh slate World Heritage Site","Wales slate UNESCO"],"related":["welsh-slate-industry","penrhyn-quarry","dinorwic-quarry","natural-slate"],"company":null,"sources":[{"title":"The Slate Landscape of Northwest Wales","url":"https://whc.unesco.org/en/list/1633","publisher":"UNESCO World Heritage Centre"},{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"},{"title":"The Slate Landscape of Northwest Wales World Heritage Site","url":"https://www.gwynedd.llyw.cymru/en/Businesses/Regeneration/Llechi-Cymru/The-Slate-Landscape-of-Northwest-Wales-World-Heritage-Site.aspx","publisher":"Gwynedd Council"}],"country":null},{"slug":"slate-repair","title":"Slate Repair","category":"installation","type":"article","summary":"Slate repair replaces individual broken slates by cutting the old nails with a slate ripper and securing a new slate with a nail and bib flashing, a hook or a tab.","body":"Natural slate roofs can last for generations, but individual slates crack, slip or break from impact, foot traffic or failed nails. Because each slate is held by nails hidden under the course above, repairs use special tools and methods that avoid disturbing the surrounding slates.\n\n## Removing the damaged slate\n\nA **slate ripper** is a long flat bar with a hooked blade. It is slid under the broken slate, hooked onto a nail, and either pulled to extract the nail or struck with a hammer to cut the shank. The National Slate Association notes that pulling the nail out is preferred. After both nails are dealt with, the slate pieces and remaining nail shanks are removed so a full-length replacement can slide in.\n\n## Choosing a replacement\n\nThe replacement should match the existing slate in size, thickness, colour and weathering. Size is the most important, because it sets the headlap and offset. Reclaimed slates of similar age are often a better match than new ones.\n\n## Fixing methods\n\n**Nail and bib flashing.** The new slate is slid into place and a hole is made through the joint between the two slates of the course above. It is fixed with a copper nail, and a small piece of sheet copper, the **bib**, is slid up under the course above so it covers the nail. US federal preservation guidance describes a bib about 3 by 8 in (75 by 200 mm), bent lengthwise and extending about 2 in under the next course.\n\n**Slate hook.** A stainless or copper hook is nailed to the deck or batten in the joint below, and the replacement slate is slid down until its tail rests in the hook.\n\n**Copper tab.** A narrow copper strip is nailed to the deck and folded up over the tail of the new slate. Federal guidance warns against this method in cold climates, where snow and ice can bend the tab open.\n\n## What to avoid\n\nMaterials that will not outlast the slate, such as galvanized nails, are discouraged because they rust and stain. Federal guidance suggests that if 20 percent or more of a roof needs repair, full replacement should be considered.","key_facts":[{"label":"Removal tool","value":"Slate ripper"},{"label":"Common fixings","value":"Copper nail with bib, slate hook, copper tab"},{"label":"Bib size (GSA)","value":"About 3 x 8 in (75 x 200 mm)"}],"regions":["Global"],"aliases":["slate replacement","replacing a broken slate","bib flashing repair"],"related":["slate-roof-installation","slate-ripper","slate-hook-fixing","natural-slate"],"company":null,"sources":[{"title":"Slate Roof Repair","url":"https://www.slateassociation.org/slate-roof-repair/","publisher":"National Slate Association"},{"title":"Minor Repairs to Slate Roofs","url":"https://gsa.gov/real-estate/historic-preservation/historic-preservation-policy-tools/preservation-tools-resources/technical-procedures/minor-repairs-to-slate-roofs","publisher":"U.S. General Services Administration"},{"title":"How Are Slate Roofs Attached? Nails, Hooks, and More","url":"https://engineerfix.com/how-are-slate-roofs-attached-nails-hooks-and-more/","publisher":"Engineer Fix"}],"country":null},{"slug":"slate-ripper","title":"Slate Ripper","category":"tools-equipment","type":"term","summary":"A long, thin steel blade with hooked notches used to reach under slates or tiles and cut or pull the hidden nails holding a damaged unit.","body":"A slate ripper, or slater's ripper, is a hand tool for removing individual slates, and sometimes tiles or shingles, without disturbing the surrounding pieces. On a slate roof each slate is held by nails hidden beneath the course above, so a broken slate cannot be lifted out directly. The ripper reaches under the course, hooks the nail, and either cuts it or pulls it out.\n\n## Design\n\nA typical ripper has a long, flat, thin steel blade with one or two hooked notches (sometimes called ears or barbs) near the tip, and a raised handle or striking block at the other end. Better models are forged from a single piece of spring-tempered steel so the blade can flex without breaking. A thin but strong blade slides under slates more easily and is less likely to crack neighbouring slates. Some models have interchangeable blades, which can be useful near edges, though one-piece forgings are generally considered stronger.\n\n## How it is used\n\n1. Slide the blade up beneath the damaged slate, feeling for the nail.\n2. Hook a notch around the nail shank.\n3. Strike the handle downward with a hammer to cut or pull the nail.\n4. Repeat for the second nail and slide the broken slate out.\n\nThe new slate is then fixed, commonly with a tingle or slate hook of copper, lead or stainless steel, because its nails cannot be driven through the course above.\n\n## Variations and related tools\n\n- Rippers come in various lengths; longer blades are used for slates with greater headlap.\n- Similar tools are used for removing clay and concrete tiles, wood shingles and asphalt shingles during repairs.\n- Slate repair kits often pair a ripper with a slater's hammer (or zax), a slate cutter and a bench iron or stake for trimming.\n\n## Care\n\nKeeping the notches sharp makes cutting nails easier. Working on slate roofs requires roof ladders or hooks rather than walking on the slates, which crack easily.","key_facts":[{"label":"Purpose","value":"Cut or pull hidden nails to remove one slate"},{"label":"Construction","value":"Long, thin, spring-tempered steel blade with notches"},{"label":"Typical refixing","value":"Tingle or slate hook"}],"regions":["Global","Europe","North America"],"aliases":["slater's ripper","slate puller","ripper"],"related":["natural-slate","nail-sickness","slaters-hammer","slate-cutter","tile-slippage"],"company":null,"sources":[{"title":"Slate Rippers Tips","url":"https://www.stortz.com/tips/slate-rippers-tips/","publisher":"John Stortz & Son"},{"title":"How to use a slate ripper","url":"https://www.jjroofingsupplies.co.uk/good-roofing-guide/how-to-guides/how-to-use-a-slate-ripper","publisher":"JJ Roofing Supplies"},{"title":"How to use a slater's ripper","url":"https://www.wonkeedonkeetools.co.uk/slaters-ripper/how-to-use-a-slater-s-ripper","publisher":"Wonkee Donkee Tools"},{"title":"Repairing Slate Roofing","url":"https://www.askthebuilder.com/repairing-slate-roofing/","publisher":"Ask the Builder"}],"country":null},{"slug":"slate-roof-installation","title":"Slate Roof Installation","category":"installation","type":"article","summary":"Slate installation lays split natural slates in double-lap courses, hung on copper or stainless nails (or hooks) with a set headlap that depends on pitch.","body":"Natural slate is laid as a **double-lap** covering: each slate is overlapped by the course above and also by the course two above, so that at any point there are at least two thicknesses of slate and the joints are always covered. The key measurement is the **headlap**, the distance by which a slate overlaps the slate two courses below it.\n\n## Headlap and exposure\n\nCanadian guidance sets a headlap of 75 mm (3 in) on slopes from 8:12 to 20:12 and 100 mm (4 in) on slopes below 8:12. The exposure (gauge) follows from the slate length and headlap: subtract the headlap from the length and divide by two. A 24 in (600 mm) slate with a 3 in headlap therefore has an exposure of 10 1/2 in (about 265 mm). Joints in each course are offset at least 38 mm (1 1/2 in) from those in the course below.\n\n## Fixing with nails\n\n- Slates are usually fixed with **two nails** through holes punched near the head, about 1 1/2 in (38 mm) in from the side edges, so the next course covers the nail heads.\n- **Copper** nails are the traditional choice, with stainless steel also common; galvanized steel is less durable and can rust before the slate wears out.\n- A common rule sets nail length at twice the slate thickness plus 1 in (25 mm). US federal preservation guidance gives 3d nails for standard slates up to 18 in long, 4d for longer slates and 6d at hips and ridges.\n- The nail is driven so the head sits just clear of the surface and the slate hangs on it. Driving it tight can crack the slate; leaving it proud lifts the slate above.\n\n## Starting and finishing\n\nA **cant strip** at the eaves, matching the slate thickness, tilts the first course so it lies at the same angle as the rest. An undercourse of shorter slates is laid first, followed by the first full course with joints offset. Hips and ridges are finished with slate, metal or lead depending on regional tradition.\n\n## Regional practice\n\nIn North America slate is normally nailed to solid wood decking over underlayment. In the UK and much of Europe slates are nailed or hooked to timber battens over an underlay, and UK work is governed by BS 5534 and BS 8000-6. In parts of Europe, slates are commonly fixed with stainless steel hooks instead of nails. Standard slates are about 4.8 mm (3/16 in) thick, with thicker grades used on heritage and heavy roofs.","key_facts":[{"label":"Headlap 8:12-20:12 (Canada)","value":"75 mm (3 in)"},{"label":"Headlap below 8:12 (Canada)","value":"100 mm (4 in)"},{"label":"Nails per slate","value":"Usually 2"},{"label":"Nail length rule","value":"2 x slate thickness + 1 in"}],"regions":["Global"],"aliases":["slating","slate roofing installation","natural slate roof installation"],"related":["natural-slate","slate-repair","slate-hook-fixing","slate-ripper","bs-5534-fixing-specification"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.3.4 Slate","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-3-tiles-clay-concrete-slate-metal/9-3-4-slate/","publisher":"Canadian Roofing Contractors Association"},{"title":"How Are Slate Roofs Attached? Nails, Hooks, and More","url":"https://engineerfix.com/how-are-slate-roofs-attached-nails-hooks-and-more/","publisher":"Engineer Fix"},{"title":"Minor Repairs to Slate Roofs","url":"https://gsa.gov/real-estate/historic-preservation/historic-preservation-policy-tools/preservation-tools-resources/technical-procedures/minor-repairs-to-slate-roofs","publisher":"U.S. General Services Administration"},{"title":"What is BS 5534?","url":"https://www.marley.co.uk/Blog/What-is-BS-5534","publisher":"Marley"}],"country":null},{"slug":"slate-roofing-contractors-association","title":"Slate Roofing Contractors Association of North America (SRCA)","summary":"The SRCA is a non-profit trade association for slate roofers, founded in 2005 in Pennsylvania, that publishes free slate installation guidelines.","body":"The Slate Roofing Contractors Association of North America (SRCA) is a trade association for contractors and professionals who install and repair natural slate roofs. It was founded in 2005 in Pennsylvania and incorporated as a non-profit in 2008. Its address is in Grove City, Pennsylvania, and its website is slateroofers.org.\n\nSRCA members are mainly slate roofing contractors, but the group also includes quarries, suppliers, consultants and tradespeople from other countries. The association reports members on three continents.\n\n## Activities\n\n- **Installation guidelines.** SRCA publishes guidelines for installing natural quarried slate roofs. They are available free to the public in both English and Spanish, which helps reach the many Spanish-speaking roofers in North America.\n- **Directory.** It runs a contractor directory and source lists so property owners can find slate specialists and materials.\n- **Conferences.** It holds an annual conference; the 2025 meeting was in Grove City, Pennsylvania.\n- **Training.** It is developing training on slate installation, repair, restoration and flashing, and lists courses and seminars.\n- **International ties.** SRCA is a member of the International Federation for the Roofing Trade (IFD) and takes part in its congresses and young roofer competitions. It is also an affiliate member of the U.S. National Roofing Contractors Association, and it exhibits at the International Roofing Expo.\n\n## Slate roofing basics\n\nNatural slate is a metamorphic rock that splits into thin, durable sheets. On a roof, slates are laid in overlapping courses with a set headlap and fixed with corrosion-resistant nails or hooks. Good slate work also depends on correct flashing in metals such as copper or lead. Because slate roofs often last for generations, repair skills are as important as new installation. Many SRCA members work on historic buildings where matching the original slate and methods is required.\n\n## Related bodies\n\nSRCA works in the same field as the National Slate Association, which focuses on technical standards and its design manual.","key_facts":[{"label":"Founded","value":"2005 (Pennsylvania)"},{"label":"Incorporated","value":"2008, as a non-profit"},{"label":"Address","value":"Grove City, Pennsylvania, USA"},{"label":"Affiliations","value":"IFD member; NRCA affiliate"}],"regions":["North America"],"aliases":["SRCA","Slate Roofing Contractors Association"],"related":["natural-slate","national-slate-association","international-federation-for-the-roofing-trade","slate-hook-fixing"],"company":{"founded":"2005","headquarters":"Grove City, Pennsylvania, USA","website":"https://www.slateroofers.org","known_for":["Free slate installation guidelines (English and Spanish)"]},"sources":[{"title":"Slate Roofing Contractors Association of North America","url":"https://www.slateroofers.org/","publisher":"SRCA"},{"title":"International Federation of the Roofing Trade directory","url":"https://www.rooferscoffeeshop.com/directory/international-federation-of-the-roofing-trade","publisher":"RoofersCoffeeShop"}],"category":"organizations","type":"organization","country":null},{"slug":"slaters-hammer","title":"Slater's Hammer and Zax","category":"tools-equipment","type":"term","summary":"Traditional slating hand tools: the slater's hammer drives nails, punches holes and trims slate; the zax is a bladed cutter with a punch point.","body":"Slate roofers have long used specialised hand tools that combine nailing, holing and cutting. The two best known are the **slater's hammer** and the **zax**.\n\n## Slater's hammer\n\nThe slater's hammer has a hammer face for driving nails at one end and a long, pointed pick at the other, used to punch nail holes through slate from the back. The shank or side of the head is usually sharpened as a cutting edge for trimming slates, and many patterns include a notch near the head for pulling nails. Leather or wooden handles and slightly curved heads are typical. Regional patterns exist, for example English, French and German styles, each with differences in head length, balance and the shape of the pick.\n\n## Zax\n\nA zax (also spelled sax, and sometimes called a slate cleaver or slate trimmer) is a hatchet-like tool with a long blade set off-centre from the handle and a sharp point projecting from the back. The blade trims slates and the point punches nail holes. Because the blade is offset, zaxes are made in left- and right-handed versions. The name is traced to the Old English *seax*, meaning knife.\n\n## How slate is trimmed by hand\n\nThe slater rests the slate on a bench iron, stake or slater's anvil, often fixed to a batten or scaffold, and strikes along the edge with the hammer or zax so the slate breaks cleanly along the line of the iron. Cutting from the back leaves a bevelled edge on the face, which is part of the traditional appearance of a hand-dressed slate roof.\n\n## Related tools\n\nThe slate ripper removes damaged slates; slate cutters (guillotines) provide a mechanical alternative for trimming and holing. Copper or stainless steel nails are generally preferred for fixing slates.\n\n## Today\n\nHand tools remain standard for skilled slaters, especially on heritage roofs, and are used alongside guillotine cutters on new work. Training bodies and conservation organisations in Europe and North America continue to teach hand dressing.","key_facts":[{"label":"Slater's hammer","value":"Nail face, punching pick, cutting edge"},{"label":"Zax","value":"Offset blade plus punch point; handed tool"},{"label":"Work surface","value":"Bench iron, stake or slater's anvil"}],"regions":["Europe","North America","Global"],"aliases":["zax","sax","slate hammer","slate cleaver"],"related":["slate-cutter","slate-ripper","natural-slate","roofing-hatchet"],"company":null,"sources":[{"title":"Zax","url":"https://designingbuildings.co.uk/wiki/Zax","publisher":"Designing Buildings Wiki"},{"title":"Roofers' slate tools","url":"https://www.cupapizarras.com/uk/news/roofers-slate-tools/","publisher":"Cupa Pizarras"},{"title":"Slater","url":"https://en.wikipedia.org/wiki/Slater","publisher":"Wikipedia"},{"title":"The evolution of slating tools","url":"https://rooferscoffeeshop.com/post/the-evolution-of-slating-tools","publisher":"RoofersCoffeeShop"}],"country":null},{"slug":"tile-slippage","title":"Slipped and Cracked Roof Tiles","category":"problems-maintenance","type":"article","summary":"Displacement or breakage of clay or concrete roof tiles from failed fixings, impact, foot traffic, frost or movement.","body":"Slipped and cracked tiles are among the most common defects on clay and concrete tile roofs worldwide. A slipped tile has moved down out of its course, usually because its nail, clip or nib has failed. A cracked tile has fractured but may stay in place. Both can let wind-driven rain reach the underlay and battens, and a gap can let further tiles move.\n\n## Causes\n\n- **Failed fixings**: corroded nails, missing clips, or nibs broken off the back of the tile.\n- **Rotting or broken battens** that no longer hold the tile.\n- **Foot traffic**: walking on tiles, especially unsupported parts of profiled tiles, is a frequent cause of cracks. Satellite, aerial and solar installers and other trades can damage roofs if they do not use roof ladders or boards.\n- **Impact** from hail, falling branches or debris.\n- **Frost damage** in porous tiles, causing spalling and lamination.\n- **Wind uplift**, especially at verges, ridges and eaves where tiles are not mechanically fixed.\n- **Building or roof movement** and thermal stress.\n\n## Spotting the problem\n\nTiles that sit out of line, gaps that show underlay or battens, debris in gutters, and damp patches in the loft after rain. Binoculars or a drone allow a safe check from the ground.\n\n## Repairs\n\nTypical repairs include sliding a single tile back and refixing it, replacing broken tiles with matching ones (lifting the tiles above with wedges and using a slate ripper to cut old nails where necessary), and fitting tile clips or hooks. Minor hairline cracks are sometimes sealed as a temporary measure, but manufacturers generally recommend replacing cracked tiles. Matching older or discontinued tiles may require reclaimed stock.\n\n## Prevention\n\nMinimise foot traffic, insist that other trades use roof ladders or crawl boards, and ensure tiles are fixed to current standards when reroofing. In the UK, BS 5534 sets fixing requirements for slating and tiling; other countries have their own codes and manufacturer installation guides, and in hurricane-prone regions tile fixing is tightly specified.","key_facts":[{"label":"Materials","value":"Clay and concrete tiles"},{"label":"Leading causes","value":"Failed fixings, foot traffic, impact, frost"},{"label":"UK fixing standard","value":"BS 5534"}],"regions":["Global"],"aliases":["slipped tiles","broken roof tiles","cracked tiles"],"related":["clay-roof-tile","concrete-roof-tile","ridge-repointing","slate-ripper","nail-sickness","tile-cutting"],"company":null,"sources":[{"title":"A homeowner's guide to cracked roof tile repair","url":"https://cm.marley.co.uk/blog/cracked-roof-tile-repair-homeowners","publisher":"Marley"},{"title":"A homeowner's guide to roof tile maintenance","url":"https://cm.marley.co.uk/blog/roof-tile-maintenance-homeowners","publisher":"Marley"},{"title":"Roof tile masonry cracked","url":"https://www.hometips.com/repair-fix/roof-tile-masonry-cracked.html","publisher":"HomeTips"}],"country":null},{"slug":"snap-lock-standing-seam","title":"Snap-Lock Standing Seam","category":"installation","type":"article","summary":"Snap-lock standing seam panels click together at the seam without a seaming tool, held down by concealed clips or an integral fastening flange.","body":"Snap-lock (also written snap-on or SnapLock) panels are roll-formed with seam edges shaped so that one panel's female leg snaps over the next panel's male leg by hand pressure or a light tap. No seaming machine is needed, which speeds installation and makes snap-lock a common choice for residential and light commercial roofs.\n\n## Attachment methods\n\nTwo broad variants exist:\n\n- **Clip-fastened snap-lock**: separate concealed clips are screwed to the deck and engaged in the seam before the next panel snaps on; they grip the seam while letting the panel expand and contract, which suits long panels and aluminium.\n- **Nail-strip (fastening flange) snap-lock**: the panel has a slotted flange along one edge that is screwed directly to the deck and is then hidden by the next panel. This is simple but restricts thermal movement more than sliding clips, so panel lengths are usually limited.\n\n## Strengths\n\n- Fast installation with basic tools.\n- Concealed fasteners keep the weathering surface unpierced.\n- Panels can be removed and replaced more easily than mechanically seamed panels.\n\n## Limitations\n\n- Seams are not folded, so they generally have lower uplift resistance and are less suited to very low slopes or areas where water or snow can stand against the seam than double-lock mechanically seamed systems.\n- As with all standing seam roofs, panels pinned so they cannot move can develop visible waviness and noise.\n\n## Performance testing\n\nSnap-lock systems are tested like other panels. Some coated steel snap-lock products are listed for UL 2218 Class 4 impact resistance and for wind uplift under standards such as UL 580 or ASTM E1592.","key_facts":[{"label":"Seam joining","value":"Snapped by hand, no seaming tool"},{"label":"Attachment","value":"Concealed clips or integral nail strip"},{"label":"Typical use","value":"Residential and light commercial roofs"}],"regions":["Global"],"aliases":["snap-on standing seam","SnapLock","nail strip panel","nail flange panel"],"related":["standing-seam-metal-roof","mechanically-seamed-standing-seam","standing-seam-clips","oil-canning"],"company":null,"sources":[{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Busting 5 Metal Roofing Myths","url":"https://www.rooferscoffeeshop.com/post/busting-5-metal-roofing-myths-2","publisher":"RoofersCoffeeShop"},{"title":"Standing Seam Types: Snap-Lock vs Mechanical Seam Explained","url":"https://www.interlockroofing.com/kb/standing-seam-types-snap-lock-vs-mechanical-seam/","publisher":"Interlock Roofing"},{"title":"What Is a Standing Seam Metal Roof? Definition, Pros & Costs","url":"https://www.interlockroofing.com/glossary/standing-seam-system/","publisher":"Interlock Roofing"}],"country":null},{"slug":"snow-guards","title":"Snow Guards and Snow Retention","category":"components","type":"article","summary":"Snow guards are devices fixed to a roof to hold or break up snow and ice so it does not slide off in dangerous slabs; they are especially common on metal roofs.","body":"Smooth metal roofs shed snow readily. That is useful for reducing snow load, but a large slab sliding off at once can injure people, damage vehicles, gutters, lower roofs and plants, or block exits. Snow guards, also called snow retention systems, hold snow on the roof or break it into smaller pieces so it melts or falls gradually.\n\n## Types\n\n- **Pad or individual guards**: small metal or polycarbonate units installed in staggered patterns across the roof.\n- **Rail or bar systems**: continuous pipes, bars or fences running across the slope, held by brackets.\n- **Panel guards**: decorative or plate-type units combining function and appearance.\n\nProducts are often powder-coated to match roof colour.\n\n## Attachment on metal roofs\n\n- **Standing seam**: clamps grip the vertical seams with set screws, so guards can be installed without penetrating the panels. Penetrating attachments are avoided on these roofs because they can leak.\n- **Through-fastened panels**: brackets are screwed through the panel into the structure with sealing washers.\n- **Adhesive mounting**: some small guards are bonded on; adhesive-only guards can fail in cold weather.\n\n## Design\n\nThe number, spacing and pattern of guards depend on roof shape, length of slope (panel run), pitch, ground snow load and what lies below; retention loads are calculated from these factors rather than estimated, and too few guards can shear off in the first large slide. Guards are usually concentrated above entries, walkways, gas meters, gutters and lower roofs. They are not meant to hold all snow indefinitely; the aim is controlled release.\n\n## History\n\nVariants of snow-retaining devices have been used for around 300 years in regions with seasonal snowfall, long before modern metal roofs.","key_facts":[{"label":"Purpose","value":"Prevent sudden slides of snow and ice"},{"label":"Main types","value":"Pad guards, rail/bar systems, panel guards"},{"label":"Standing seam attachment","value":"Non-penetrating seam clamps"}],"regions":["North America","Europe","East Asia","Arctic"],"aliases":["snow retention","snow stops","snow rails","snow fence (roof)","snow birds"],"related":["standing-seam-metal-roof","metal-roofing"],"company":null,"sources":[{"title":"Snow guard","url":"https://en.wikipedia.org/wiki/Snow_guard","publisher":"Wikipedia"},{"title":"What Are Snow Guards? Snow Retention for Metal Roofs","url":"https://www.interlockroofing.com/glossary/snow-guards/","publisher":"Interlock Roofing"},{"title":"Metal Roofs and Snow & Ice: Shedding, Ice Dams & Snow Guards","url":"https://www.interlockroofing.com/kb/metal-roofs-snow-ice/","publisher":"Interlock Roofing"}],"country":null},{"slug":"snow-load","title":"Snow Load","type":"term","summary":"The weight of accumulated snow and ice that a roof must be designed to carry, derived from local ground snow data and roof shape.","body":"Snow load is the downward force that accumulated snow, ice and meltwater place on a roof. In cold climates it is often the largest load a roof structure carries, and excessive snow is a recognised cause of roof failures.\n\n## From ground to roof\n\nDesign standards start with a ground snow load for the location, based on climate records, and then adjust it to estimate the load on a specific roof. In the United States, ASCE 7 considers the ground snow load, the roof's exposure to wind, its thermal condition (heated or unheated), roof shape and slope, drifting, and the importance of the building. Europe uses Eurocode 1, Part 1-3 (snow loads), which sets out characteristic ground snow loads for regions of Europe and shape coefficients for different roofs. Canada's National Building Code and other national codes use similar approaches.\n\n## Snow is variable\n\nSnow density changes a great deal. Fresh, dry snow is light, but a settled snowpack may reach about 30 percent of the density of water, and around 50 percent by late spring. Rain falling on snow, or snow that melts and refreezes, can add weight quickly. Ice, near the density of water, is far heavier than the same depth of fresh snow, so depth alone is a poor guide to load.\n\n## Drifts and unbalanced loads\n\nWind moves snow from one part of a roof to another. Drifts form:\n\n- against higher walls or parapets on lower roofs;\n- in valleys between roof planes;\n- on the leeward side of ridges, creating unbalanced loads;\n- around rooftop units and penetrations.\n\nWind-blown snow can form deposits several metres deep in sheltered spots, so drift loads often control the design of lower roofs next to taller buildings.\n\n## Ponding and freezing\n\nOn flat and low-slope roofs, meltwater that cannot drain adds load, and decking that sags under the weight can collect even more water. In cold climates, ponded water can freeze and damage the roof surface.\n\n## Practical guidance\n\nSigns of overload in buildings include sagging, cracking sounds, and doors that stick. Removing snow can be dangerous for people and can damage roofing; guidance generally recommends roof rakes from the ground or qualified contractors. Snow guards on steep roofs keep snow from sliding off suddenly but also retain the load on the roof, which the structure must be designed to carry.","key_facts":[{"label":"US design standard","value":"ASCE 7"},{"label":"European standard","value":"Eurocode 1, Part 1-3"},{"label":"Settled snowpack density","value":"About 30% of water, rising toward 50% in spring"},{"label":"Critical cases","value":"Drifts, rain-on-snow, ice"}],"regions":["North America","Europe","East Asia","Arctic"],"aliases":["roof snow load","snow loading","ground snow load"],"related":["snow-sliding","ice-dam","ponding-water","roof-drainage-design","climate-change-and-roofing"],"sources":[{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Flat_roof","publisher":"Wikipedia"},{"title":"Snow guard","url":"https://en.wikipedia.org/wiki/Snow_guard","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"snow-sliding","title":"Snow Sliding and Snow Guards","type":"term","summary":"The sudden release of snow and ice from a sloped roof, and the guards and rails installed to break it up and hold it in place.","body":"Snow sliding is the release of accumulated snow and ice from a sloped roof, often suddenly and in large masses. Smooth, steep surfaces such as metal panels, glazed tile and slate shed snow readily. This helps limit the load on the roof but creates hazards below: falling snow and ice can injure people, damage vehicles, plants, gutters and lower roofs, and block exits.\n\n## When and why snow slides\n\nSnow tends to slide when its bond with the roof weakens, typically during thaw, after rain, or when sun or building heat warms the roof surface. A layer of meltwater at the roof surface acts as a lubricant. Roofs over heated spaces, dark coverings in sunshine, and steep pitches all increase the likelihood of a slide.\n\n## Snow guards\n\nSnow guards are devices fixed to the roof to hold snow in place or break it into smaller pieces so it melts gradually or falls in smaller amounts. Variants have been used for more than 300 years in snowy regions. Types include:\n\n- **Individual guards (pads or brackets)** installed in staggered rows across the roof.\n- **Rails or bars (snow fences)** that run horizontally across the roof, sometimes in several rows.\n- **Clamp-on systems** for standing seam metal roofs that attach to seams without penetrating the panels.\n\nModern guards are made from metal, polycarbonate or both and can be coloured to match the roof.\n\n## Design considerations\n\nThe number and layout of guards depends on roof pitch, length of the slope, surface material, and expected snow load. Guards are not meant to retain all snow indefinitely; a fully held snowpack adds load and can promote leaks as it melts. Engineers check that the roof structure and fastening can carry the retained snow, and manufacturers publish layout guidance based on testing.\n\n## Where guards are used\n\nGuards are common over entrances, walkways, parking, decks, lower roofs, and gutters, and wherever people or property below could be struck by falling snow and ice.\n\n## Related issues\n\nSliding snow can tear off gutters, vent stacks, and rooftop equipment. Placing penetrations near the ridge, using diverters above chimneys and vents, and fitting heavy-duty gutter brackets help reduce this damage.","key_facts":[{"label":"Most prone surfaces","value":"Metal, slate, glazed tile on steep slopes"},{"label":"Guard types","value":"Pads/brackets, rails, seam-clamp systems"},{"label":"History","value":"Snow guards used for over 300 years"}],"regions":["North America","Europe","East Asia","Arctic"],"aliases":["snow guard","snow retention","snow rail","snow fence","snow slide"],"related":["snow-load","ice-dam","metal-roofing","standing-seam-metal-roof"],"sources":[{"title":"Snow guard","url":"https://en.wikipedia.org/wiki/Snow_guard","publisher":"Wikipedia"},{"title":"Ice dam (roof)","url":"https://en.wikipedia.org/wiki/Ice_dam_(roof)","publisher":"Wikipedia"},{"title":"Snow load","url":"https://en.wikipedia.org/wiki/Snow_load","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"sod-roof","title":"Sod Roof","type":"term","summary":"A traditional Scandinavian roof of turf laid over layers of birch bark on gently sloping boards; the forerunner of modern green roofs.","body":"A sod roof, or turf roof (Norwegian *torvtak*, Icelandic *torfþak*), is a roof covered with living turf laid over a waterproof layer. In the traditional Scandinavian form, the waterproofing is birch bark, and the sod's main job is to weigh the bark down and protect it. Until the late 19th century this was the most common roof on rural log houses in Norway and much of Scandinavia, and it is closely associated with the log-building traditions of Norway, Sweden and Finland. Turf roofs were also traditional in Iceland.\n\n## Traditional construction\n\n- Birch bark is laid inside-up on gently sloping roof boards, from the eaves upward, overlapping like shingles and lapping over the ridge. It is usually not nailed; friction and the weight of the sod hold it in place.\n- Six layers of bark were considered adequate; high-quality roofs had up to 16.\n- The first layers project about 8 cm (3 in) beyond the eaves to form a drip edge.\n- A turf log along the eaves, held by wooden hooks or pegs, stops the sod sliding off.\n- Sod is cut in pieces about 30 cm (12 in) square and 7.5 cm (3 in) thick. The first layer is laid grass-down to protect the bark, and a second grass-up.\n- About 15 cm (6 in) of sod is enough to survive a dry summer; more than 20 cm (8 in) adds unnecessary weight.\n\n## Weight\n\nA traditional sod roof weighs about 250 kg/m² (about 51 lb/ft²), rising to roughly 400-500 kg/m² (82-102 lb/ft²) with winter snow. The load was useful in log buildings because it compressed the logs and reduced draughts.\n\n## Lifespan\n\nAbout 30 years was considered a normal life for the bark layer in most places.\n\n## History and revival\n\nSod roofs were probably used since prehistoric times and were almost universal on rural houses during the Viking Age and the Middle Ages. During the 19th century tile and later corrugated iron replaced them except in remote areas. National Romanticism, open-air museums and demand for mountain cabins revived the type, and turf roofs are still widely built on new cabins in Norway. Modern versions replace birch bark with bitumen roofing membranes and a dimpled drainage sheet, an approach that overlaps with modern green-roof construction.\n","key_facts":[{"label":"Traditional waterproofing","value":"Birch bark, 6-16 layers"},{"label":"Sod depth","value":"About 15 cm (6 in) recommended"},{"label":"Weight","value":"About 250 kg/m² (51 lb/ft²); 400-500 kg/m² with snow"},{"label":"Bark life","value":"About 30 years"}],"regions":["Europe","Arctic"],"aliases":["turf roof","torvtak","torfþak","grass roof"],"related":["green-roof","thatch","birch-bark-roofing"],"sources":[{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"},{"title":"Roof","url":"https://en.wikipedia.org/wiki/Roof","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"soffit","title":"Soffit","category":"components","type":"term","summary":"A soffit is the underside lining of a roof overhang, closing the space between the fascia and the wall, often fitted with vents.","body":"In roofing, a soffit is the horizontal (or sometimes sloping) underside of the eaves, spanning from the back of the fascia to the face of the wall. More broadly in architecture, \"soffit\" means the exposed underside of any overhead element, such as an arch, beam or stair.\n\n## Purpose\n\n- It closes off the gap between rafters at the overhang, keeping out birds, insects, rodents and weather.\n- It gives the eaves a finished appearance.\n- It is commonly the location for intake vents that supply outside air to the roof space in a ventilated (cold) roof.\n\n## Boxed and open eaves\n\n- **Boxed (closed) eaves:** the overhang is enclosed with a soffit, sometimes on short horizontal lookouts that make a flat underside.\n- **Sloped soffit:** the lining is fixed directly to the underside of the rafters, following the roof pitch.\n- **Open eaves:** no soffit; rafter tails are left exposed, a common feature of Craftsman and many traditional styles. Blocking or bird-stop pieces close the gaps above the wall.\n\n## Materials\n\nSoffits have been made of timber boards, plywood, asbestos cement (in older buildings, which should be checked before disturbance), aluminium, vinyl, uPVC, fibre-cement and steel. Perforated aluminium and vinyl panels are common in North America; uPVC soffit boards are typical in UK house building.\n\n## Ventilation role\n\nWhere soffits provide intake ventilation, the vents must not be blocked by insulation inside the roof. US code requires at least 1 in (25 mm) of space between insulation and roof sheathing at eave vents, and baffles or eaves trays are used to maintain the air path. Ventilating soffit panels are rated by net free vent area so designers can confirm the intake meets code ratios.","key_facts":[{"label":"Location","value":"Underside of the eaves overhang"},{"label":"Common materials","value":"Aluminium, vinyl, uPVC, timber, fibre-cement"},{"label":"Vent clearance (IRC)","value":"Min 1 in (25 mm) under sheathing"}],"regions":["Global"],"aliases":["eaves soffit","soffit board"],"related":["fascia","eaves","roof-ventilation"],"company":null,"sources":[{"title":"Eaves","url":"https://en.wikipedia.org/wiki/Eaves","publisher":"Wikipedia"},{"title":"Attic-Ventilation Strategies","url":"https://finehomebuilding.com/project-guides/roofing/attic-ventilation-strategies","publisher":"Fine Homebuilding"}],"country":null},{"slug":"solar-reflectance","title":"Solar Reflectance","type":"term","summary":"The fraction of incoming sunlight a surface reflects, from 0 (absorbs all) to 1 (reflects all); also called albedo.","body":"Solar reflectance is the share of incoming solar energy that a surface reflects rather than absorbs. It is expressed on a scale from 0 to 1 (or 0 to 100 percent). A value of 0.05 means the surface reflects 5 percent of sunlight and absorbs the rest; a value of 0.80 means it reflects 80 percent. The term albedo is often used for the same property, particularly at the scale of cities or the planet.\n\n## Why it matters for roofs\n\nSunlight absorbed by a roof heats it. The US EPA identifies solar reflectance as the most important property for keeping a roof cool. Lawrence Berkeley National Laboratory reports that a white roof reflecting 80 percent of sunlight stays about 31 °C (55 °F) cooler on a summer afternoon than a grey roof reflecting 20 percent.\n\n## Visible and near-infrared light\n\nA large share of solar energy arrives as near-infrared light, which the eye cannot see. This means two roofs of the same visible colour can have very different solar reflectance. \"Cool colour\" pigments reflect near-infrared strongly, allowing darker-looking roofs, such as brown tile or grey metal, to stay cooler than conventional products of the same shade.\n\n## Initial and aged values\n\nReflectance declines as roofs collect dirt, soot, algae and biological growth, and as surfaces weather. Rating programs therefore report both an initial value and a value after several years of outdoor exposure. For example, ENERGY STAR criteria for low-slope roofs have used an initial solar reflectance of at least 0.65 and a weathered reflectance of at least 0.50. The Cool Roof Rating Council in the United States publishes measured initial and aged values for many products.\n\n## Typical values\n\nReflectance varies with product and condition, but in general:\n\n- black membranes and dark shingles are low;\n- conventional coloured shingles are low to moderate;\n- cool-coloured products are moderate;\n- white membranes and coatings are high when new and clean.\n\n## Related measures\n\nSolar reflectance is combined with thermal emittance to calculate the Solar Reflectance Index (SRI), which some codes and green building programs use as a single performance number.","key_facts":[{"label":"Scale","value":"0 (absorbs all) to 1 (reflects all)"},{"label":"Also called","value":"Albedo"},{"label":"ENERGY STAR low-slope (initial / weathered)","value":"At least 0.65 / 0.50"}],"regions":["Global"],"aliases":["albedo","SR","solar reflectivity"],"related":["cool-roof","thermal-emittance","solar-reflectance-index","cool-roof-rating-council","urban-heat-island"],"sources":[{"title":"Cool Roofs","url":"https://heatisland.lbl.gov/coolscience/cool-roofs","publisher":"Lawrence Berkeley National Laboratory, Heat Island Group"},{"title":"Using Cool Roofs to Reduce Heat Islands","url":"https://www.epa.gov/heatislands/using-cool-roofs-reduce-heat-islands","publisher":"US Environmental Protection Agency"},{"title":"Cool roof (reflective surfaces)","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"solar-reflectance-index","title":"Solar Reflectance Index (SRI)","type":"term","summary":"The Solar Reflectance Index (SRI) combines a surface's solar reflectance and thermal emittance into one number, where standard black is 0 and standard white is 100.","body":"The **Solar Reflectance Index (SRI)** is a single number that describes how well a roof surface stays cool in the sun. It combines two measured properties:\n\n- **Solar reflectance** – the fraction of sunlight the surface reflects.\n- **Thermal emittance** – how efficiently the surface radiates absorbed heat away as infrared energy.\n\nSRI is calculated relative to two reference surfaces: a **standard black** surface defined as SRI 0 and a **standard white** surface defined as SRI 100. Very reflective, high-emittance materials can score above 100; the theoretical maximum is around 122. Surfaces hotter than standard black can have negative values.\n\n## How it is calculated\n\nIn North America, SRI is calculated using ASTM E1980, which sets standard conditions for sun, air temperature and wind (low, medium or high convection) and computes the steady-state surface temperature. The input values of reflectance and emittance usually come from [Cool Roof Rating Council](/cool-roof-rating-council) ratings. Because results vary with the chosen wind condition, programs normally specify which one applies, commonly medium wind.\n\n## Why use a single number\n\nSeparate reflectance and emittance values can be hard to compare. A bare metal roof may have high reflectance but low emittance, so it heats up more than its reflectance suggests. SRI accounts for both. For example, stainless steel roofing can reach very high SRI values, while dark asphalt shingles have low SRI.\n\n## Where SRI is used\n\n- **Green building programs.** [LEED](/leed-heat-island-reduction) heat island credits set SRI thresholds for roofs. Under LEED 2009, for example, low-slope roofs needed SRI 78 or higher and steep-slope roofs SRI 29 or higher. Later LEED versions use both initial and three-year aged SRI values.\n- **Energy codes.** Some codes and local ordinances allow SRI as an alternative to separate reflectance and emittance criteria.\n- **Urban heat island programs.** Cities use SRI in cool roof ordinances and incentives.\n\n## Limitations\n\nSRI describes the surface only. It says nothing about insulation, ventilation or the roof's overall thermal performance. It also reflects ideal clean surfaces unless aged values are used, and reflectance can drop significantly as roofs get dirty or weather. In cold climates, high SRI roofs can slightly increase heating energy, so cool roof requirements are usually strongest in warm climate zones.","key_facts":[{"label":"Reference points","value":"Standard black = 0; standard white = 100"},{"label":"Theoretical maximum","value":"About 122"},{"label":"Calculation method (North America)","value":"ASTM E1980"},{"label":"Inputs","value":"Solar reflectance and thermal emittance"},{"label":"LEED 2009 thresholds","value":"Low slope ≥ 78; steep slope ≥ 29"}],"regions":["Global","North America"],"aliases":["SRI","solar reflectance index"],"related":["cool-roof-rating-council","cool-roof","leed-heat-island-reduction","title-24-cool-roof","urban-heat-island","solar-reflectance","thermal-emittance"],"sources":[{"title":"Cool roof","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"},{"title":"Cool Science: Cool Roofs","url":"https://heatisland.lbl.gov/coolscience/cool-science-cool-roofs","publisher":"Lawrence Berkeley National Laboratory"},{"title":"Using Cool Roofs to Reduce Heat Islands","url":"https://www.epa.gov/heatislands/using-cool-roofs-reduce-heat-islands","publisher":"US EPA"},{"title":"ASTM E1980 Standard Practice for Calculating Solar Reflectance Index of Horizontal and Low-Sloped Opaque Surfaces","url":"https://store.astm.org/e1980-11r19.html","publisher":"ASTM International"}],"category":"standards-codes","company":null,"country":null},{"slug":"solar-roof-mounting","title":"Solar Roof Mounting Systems","type":"term","summary":"Racking that secures solar panels to roofs: penetrating rail systems, seam clamps on metal roofs and ballasted racks on flat roofs.","body":"Solar roof mounting systems (racking) attach photovoltaic panels to a roof, hold them at the desired angle, and transfer wind, snow and dead loads into the building structure. The choice of system affects the roof's waterproofing, structural load and long-term maintenance.\n\n## Pitched roofs\n\nOn sloped roofs, arrays are usually mounted parallel to the roof surface with a gap of a few centimetres for airflow and drainage.\n\n- **Rail-based systems** use aluminium rails fixed to the roof with brackets (feet or hooks). Brackets are fastened into rafters or the deck and sealed with flashing designed for the roof covering: flashed mounts for shingles, tile hooks or replacement flashing tiles for tile roofs.\n- **Rail-less systems** fix panels directly to individual mounts.\n- **Seam clamps** on standing seam metal roofs grip the raised seams, avoiding holes in the panels.\n- **Tile roofs** often need tiles cut or replaced at each hook so the tile can sit flat and shed water.\n\nCommon guidance is roughly one support bracket per hundred watts of panels, but actual spacing depends on engineering for local wind and snow.\n\n## Flat and low-slope roofs\n\n- **Ballasted racks** sit on the membrane, usually on protective pads, and are held down by concrete blocks or the weight of the system. They avoid penetrations but add significant load and must be engineered for wind and, in seismic areas, sliding.\n- **Attached systems** use a limited number of flashed structural anchors, reducing ballast weight.\n- **Hybrid systems** combine some ballast with fewer attachments.\n- **Lightweight options** include plastic wedges and tension-based racking.\n\nPanels on flat roofs are usually tilted at a low angle; spacing between rows reduces self-shading and leaves access for maintenance.\n\n## Wind design\n\nWind pressures on arrays vary across the roof, with edges and corners most severe. ASCE 7-16 in the United States introduced specific methods for rooftop solar panels parallel to the roof surface. Racking manufacturers publish engineering based on these standards and on wind tunnel tests.\n\n## Roof compatibility\n\n- Racking metals should be compatible with roofing metals to avoid galvanic corrosion.\n- Penetrations through membranes must be flashed in accordance with the membrane manufacturer's details to preserve the roofing warranty.\n- Ballast pads must protect the membrane from abrasion.\n- Access paths and setbacks are often required for fire safety.\n\n## Removal and reinstallation\n\nBecause roof coverings may need replacing during an array's life, mounting systems that allow panels to be removed and reinstalled without damaging the roof reduce future costs.","key_facts":[{"label":"Pitched roof options","value":"Rail, rail-less, seam clamp, tile hook"},{"label":"Flat roof options","value":"Ballasted, attached, hybrid"},{"label":"Rule of thumb","value":"About one bracket per 100 W of panels"},{"label":"US wind standard","value":"ASCE 7-16 rooftop PV provisions"}],"regions":["Global"],"aliases":["solar racking","PV mounting","ballasted solar","solar standoffs","seam clamp"],"related":["rooftop-solar-pv","building-integrated-photovoltaics","roof-wind-pressure-zones","coastal-corrosion","standing-seam-metal-roof"],"sources":[{"title":"Photovoltaic mounting system","url":"https://en.wikipedia.org/wiki/Photovoltaic_mounting_system","publisher":"Wikipedia"},{"title":"ASCE 7-16 Wind for PV Parallel to Roof (SEAOC 2016 Convention presentation)","url":"https://www.seia.org/sites/default/files/Cain%20and%20Banks%20ASCE%207-16%20Wind%20for%20PV%20Parallel%20to%20Roof%20Presentation%20-%20SEAOC%202016%20Convention.pdf","publisher":"Solar Energy Industries Association"},{"title":"Determining Components and Cladding Roof Design Pressures","url":"https://structuremag.org/?p=13322","publisher":"STRUCTURE magazine"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"solar-shingle","title":"Solar Shingle","type":"term","summary":"A photovoltaic module shaped and installed like a roofing shingle or tile, so that it forms part of the roof covering while generating electricity.","body":"A solar shingle is a photovoltaic (PV) module designed to look and be installed like a conventional roofing shingle or tile. Rather than mounting panels on racks above an existing roof, the solar units themselves form part of the weather-shedding roof covering, usually mixed with matching non-solar shingles or tiles. Solar shingles and solar tiles are the most common form of building-integrated photovoltaics (BIPV).\n\n## History\n\nSolar shingles became commercially available in about 2005. Dow's POWERHOUSE Solar System went on sale in Colorado in October 2011; a later version was licensed to RGS Energy from 2017 until RGS filed for bankruptcy in 2020. In October 2016 Tesla, together with SolarCity, announced the Solar Roof. In January 2022 GAF announced a solar shingle product. A Dutch company developed and patented a ceramic solar roof tile in 2013.\n\n## Technology\n\n- **Cells**: most current products use monocrystalline or polycrystalline silicon cells; some early products used thin-film CIGS cells.\n- **Formats**: rigid shingle-sized panels, semi-rigid silicon designs and flexible thin-film units.\n- **Size and output**: many shingle products measure about 12 by 86 in (305 by 2,185 mm), with a 5 by 86 in (127 by 2,185 mm) exposed strip, and some reach up to 100 W DC per unit.\n\n## Cost\n\nInstalled costs have been reported at about US$3.80-9.00 per watt, depending on manufacturer, technology and system size, generally higher than conventional rack-mounted panels, though the gap has narrowed. Part of the cost is offset because the solar units replace ordinary roofing material.\n\n## Performance considerations\n\n- Because they sit close to the roof deck with little air flow, integrated modules run hotter than rack-mounted panels, and higher temperatures reduce output and can shorten life.\n- Output depends on roof orientation, pitch and shading.\n- Building codes require the assembly to meet both roofing (fire, wind, water) and electrical safety requirements.\n\n## Terminology\n\nSystems retrofitted onto finished roofs are usually called building-applied photovoltaics (BAPV), while BIPV replaces part of the building envelope.\n","key_facts":[{"label":"Commercial availability","value":"From about 2005"},{"label":"Typical cells","value":"Mono- or polycrystalline silicon; some thin-film CIGS"},{"label":"Example size","value":"About 12 x 86 in (305 x 2,185 mm)"},{"label":"Reported installed cost","value":"About US$3.80-9.00 per watt"}],"regions":["North America","Europe","Global"],"aliases":["solar roof tile","PV shingle","photovoltaic shingle","solar tile"],"related":["building-integrated-photovoltaics","asphalt-shingle","clay-roof-tile"],"sources":[{"title":"Solar shingle","url":"https://en.wikipedia.org/wiki/Solar_shingle","publisher":"Wikipedia"},{"title":"Building-integrated photovoltaics","url":"https://en.wikipedia.org/wiki/Building-integrated_photovoltaics","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"soldering-sheet-metal-roofing","title":"Soldering Sheet Metal Roofing","category":"installation","type":"article","summary":"Soldering joins copper, terne-coated stainless, zinc and similar roof sheets with molten tin-based alloy to make watertight seams, especially on low slopes.","body":"Soldered seams are used where a metal roof must be fully watertight even when water stands on it, as on flat seam roofs at slopes of 3 in 12 or less, built-in gutters, valleys and complex flashings. The process melts a tin-based alloy into a tightly folded joint so that it flows by capillary action and seals the seam.\n\n## Materials\n\n- **Solder**: North American specifications cite ASTM B32, typically 50/50 tin-lead or a lead-free alloy of similar or greater strength. Alloy and flux must suit the metals being joined.\n- **Flux**: cleans the metal and helps solder wet the surface. Acid fluxes are common for copper.\n- **Heat**: traditional soldering coppers (\"irons\") are heated in a furnace or by torch. One copper specification calls for furnace-heated coppers of at least 5 lb (2.3 kg) per pair, or torch-heated heads of at least 3 lb (1.4 kg).\n\n## Process for flat seam copper\n\n1. Clean and wire-brush the edges, apply flux, and pre-tin them about 1.5 in (38 mm) wide before folding.\n2. Lock the seams and dress them flat with a mallet.\n3. Sweat solder fully into the seams.\n4. Neutralise flux residues with a baking soda or washing soda solution and rinse thoroughly.\n\nOnly as many pans as can be soldered the same day should be installed, and tinned edges should be protected overnight.\n\n## Limits\n\n- Soldered roofs cannot move at their joints, so large areas need expansion joints, often every 25 to 30 ft (7.6 to 9 m).\n- Copper heavier than 20 oz is usually lapped and riveted as well as soldered.\n- Lead sheet is joined by lead welding (lead burning) rather than tin solder.","key_facts":[{"label":"Solder standard (US)","value":"ASTM B32"},{"label":"Typical alloy","value":"50/50 tin-lead or lead-free equivalent"},{"label":"Pre-tinning width","value":"About 1.5 in (38 mm)"},{"label":"Required on flat seam copper","value":"Slopes 3:12 or less"}],"regions":["Global"],"aliases":["roof soldering","sweating seams","tinning"],"related":["flat-seam-roofing","copper-roofing","terne-coated-stainless-steel","zinc-roofing"],"company":null,"sources":[{"title":"8.5. Flat Seam Roofing","url":"https://www.copper.org/applications/architecture/arch_dhb/arch-details/roofing/flat_seam_roofing.php","publisher":"Copper Development Association"},{"title":"14.3. Copper Roofing (architectural specifications)","url":"https://archive.copper.org/applications/architecture/arch_dhb/specifications/arch_specs/sheet_roofing.php","publisher":"Copper Development Association"},{"title":"Section 07 61 16 Sheet Metal Roofing (VA master specification)","url":"https://www.wbdg.org/FFC/VA/VANCAS/VANCA076116.pdf","publisher":"Whole Building Design Guide / U.S. Department of Veterans Affairs"}],"country":null},{"slug":"soprema","title":"Soprema","category":"manufacturers","type":"company","summary":"Soprema is a family-controlled French manufacturer of waterproofing, insulation and green-roof products, founded in 1908 and active in about 90 countries.","body":"Soprema is an independent, family-controlled French group specialising in waterproofing membranes, insulation, vegetated (green) roofing and soundproofing. The company traces its origins to 1908 and to founder Charles Geisen, who chose the name as an acronym of the French phrase Societe de Produits et Revetements d'Etancheite Mammouth. The mammoth remains the group's emblem. The present company structure dates from 1979.\n\n## Scale\n\nAccording to figures reported for 2023, Soprema had revenue of about EUR 4.8 billion, around 11,000 employees (roughly half of them in France), 128 production sites and about 120 subsidiaries, with a presence in some 90 countries. Its plants include dozens of waterproofing and insulation factories as well as sites producing smoke-ventilation equipment, adhesives and recycled materials. The group is chaired by Pierre-Etienne Bindschedler.\n\n## Products\n\nSoprema's core business is waterproofing for roofs, building envelopes and civil engineering works, alongside thermal insulation, vegetated roof systems and soundproofing. Its factories also produce geotextiles, mastics and adhesives, and smoke-ventilation equipment, and it runs recycling plants. In 2016 it acquired Pavatex, a maker of wood-fibre insulation based in the Vosges.\n\n## International presence\n\nSoprema operates national subsidiaries across Europe and in other regions, including North America, and supports its network with 23 research and development centres and 48 training centres in 16 countries.\n\n## Bituminous waterproofing\n\nModified-bitumen membranes combine bitumen with polymers and a reinforcing carrier, and are installed by torching, hot-air welding, cold adhesives or self-adhesion, often in two layers on flat roofs. Its mascot, the mammoth, also features in a mammoth skeleton displayed at its headquarters.","key_facts":[{"label":"Founded","value":"1908 (current company 1979)"},{"label":"Founder","value":"Charles Geisen"},{"label":"Ownership","value":"Independent, family-controlled"},{"label":"Production sites","value":"128 (2023)"}],"regions":["Europe","North America","Global"],"aliases":["SOPREMA","Soprema Group"],"related":["modified-bitumen-roofing","sbs-modified-bitumen","green-roof","liquid-applied-roofing","polyiso-insulation"],"company":{"founded":"1908","website":"https://www.soprema.com","known_for":["Bituminous waterproofing","Green roof systems","Insulation"]},"sources":[{"title":"Soprema","url":"https://fr.wikipedia.org/wiki/Soprema","publisher":"Wikipedia (French)"},{"title":"Soprema","url":"https://www.soprema.com/en/","publisher":"Soprema"}],"country":null},{"slug":"spanish-mediterranean-terracotta-roof","title":"Spanish Mediterranean Terracotta Roof","type":"article","summary":"Low-pitched roof of curved terracotta tiles laid in alternating channels and caps, typical of Spain and the Mediterranean and of Spanish colonial architecture.","body":"The terracotta tile roof of Spain and the Mediterranean is made of curved, half-cylinder clay tiles laid in alternating rows: one row of tiles laid concave side up forms channels, and the next row laid convex side up caps the joints between them. The result is a ribbed roof surface with deep shadows, warm red or orange colour and low pitch, recognised worldwide as the \"Spanish\" or \"mission\" roof.\n\n## Origins\n\nFired clay roof tiles appeared in the Greek world in the 7th century BC, when the paired *tegula* (flat pan) and *imbrex* (curved cover) replaced thatch on temples near Corinth. The Romans spread tile making across their empire, including the Iberian Peninsula. Over time, in Spain and much of the Mediterranean, the flat pan gave way to a second curved tile, producing the all-curved roof familiar today. Spanish-style tiles were traditionally formed by extrusion and bending over a mould.\n\n## Laying\n\n- The **channel** (under) tiles are laid on a bed of mortar or on battens with their wide end up-slope.\n- The **cover** (over) tiles are set convex side up over the joints.\n- Eaves are often finished with a double or triple row of tiles projecting beyond the wall.\n\nTraditional roofs bedded every tile in lime mortar; modern systems fix tiles mechanically to battens with clips or screws, often over a waterproof underlay, which reduces slippage and wind damage.\n\n## Climate fit\n\nThe low pitch suits a dry, sunny climate with occasional heavy rain. The air gaps under curved cover tiles help ventilate the roof and reduce heat gain. Clay tiles are durable, with high-grade products lasting more than a century.\n\n## Spread\n\nSpanish colonisers carried the roof to the Americas and Asia. Clay tiles were first produced on the US West Coast at Mission San Antonio de Padua in 1780, and Spanish-influenced tile roofs remain common in California, Florida and Latin America. In the Philippines, the curved *teja de curva* replaced nipa thatch on many colonial houses.\n\n## Today\n\nCurved terracotta tiles remain common on houses in Spain, Portugal, southern France and Italy, alongside flatter interlocking clay and concrete tiles that imitate the profile.","key_facts":[{"label":"Tile type","value":"Curved half-cylinder clay tiles"},{"label":"Arrangement","value":"Alternating channel and cover rows"},{"label":"Ancient precursor","value":"Tegula and imbrex (7th century BC)"},{"label":"First US production","value":"Mission San Antonio de Padua, 1780"}],"regions":["Europe","Latin America"],"aliases":["Spanish tile","Barrel tile","Mission tile","Teja árabe","Canal tile"],"related":["roofing-in-spain","clay-roof-tile","imbrex-and-tegula","roofing-in-italy","roofing-in-portugal"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Architecture of Greece","url":"https://en.wikipedia.org/wiki/Architecture_of_Greece","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"spanish-slate","title":"Spanish Slate","type":"term","summary":"Natural roofing slate from north-west Spain, mainly Galicia; Spain supplies about 90% of Europe's roofing slate.","body":"Spanish slate is natural roofing slate quarried in north-west Spain. Spain is the world's largest producer and exporter of natural slate and supplies roughly 90% of the roofing slate used in Europe.\n\n## Where it comes from\n\nMost production is in Galicia, with the larger companies concentrated in the Valdeorras area of Ourense province. Other workings are at Quiroga, Ortigueira and Mondoñedo. The deposits are Palaeozoic, more than 500 million years old.\n\n## Properties\n\nSpanish slates are usually dark blue-black or grey. Good-quality material has a water absorption below about 0.4%, which gives strong frost resistance. Because quality varies from bed to bed and quarry to quarry, buyers rely on test results to EN 12326, the European product standard for roofing slate. Key classifications are:\n\n- **A1** water absorption (0.6% or less by mass);\n- **S1** in the sulphur-dioxide test, linked to low carbonate content;\n- **T1** in the thermal-cycle test, meaning any oxidation of metallic minerals such as pyrite causes only minor colour change without runs of staining.\n\nSlates graded T2 or T3 may develop rust spots or staining, and UK industry commentators have warned that lower-grade imported material has caused disappointment on new roofs.\n\n## Use\n\nSpanish slate is widely used on new housing and re-roofing in the UK, Ireland, France and other parts of Europe. On the European continent it is commonly fixed with metal hooks rather than nails; in the UK both methods are used. It is produced in many standard rectangular sizes as well as cut shapes for decorative patterns.\n\n## Comparison with other slates\n\nWhere an original local slate is no longer available, Spanish slate is often considered as a substitute. Heritage guidance generally advises matching the colour, texture and thickness of the original as closely as possible.\n","key_facts":[{"label":"Main region","value":"Galicia (especially Valdeorras, Ourense)"},{"label":"Share of European roofing slate","value":"About 90%"},{"label":"Age of deposits","value":"Over 500 million years (Palaeozoic)"},{"label":"Product standard","value":"EN 12326"}],"regions":["Europe"],"aliases":["Galician slate","pizarra"],"related":["natural-slate","welsh-slate","en-12326","slate-hook-fixing"],"sources":[{"title":"Slate industry","url":"https://en.wikipedia.org/wiki/Slate_industry","publisher":"Wikipedia"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"},{"title":"Roofing: Quality shows","url":"https://www.stonespecialist.com/news/roofing-quality-shows","publisher":"Natural Stone Specialist"},{"title":"EN 12326-1 Test Results: Welsh Penrhyn","url":"https://cdn.shopify.com/s/files/1/0242/1053/8577/files/Welsh_Penryn_Test_Results.pdf","publisher":"Test report (supplier data sheet)"}],"category":"materials","company":null,"country":null},{"slug":"spanish-tile","title":"Spanish Tile","type":"term","summary":"A one-piece clay or concrete roof tile with a deep S-curve that imitates two-piece barrel tiling in a single unit.","body":"A Spanish tile, also called an S-tile, is a single-piece roof tile whose cross-section forms a deep S: a wide channel on one side and a raised roll on the other. Once laid, the rolls line up to give the same wavy appearance as two-piece mission or barrel tiling, but with fewer pieces and less weight.\n\n## Manufacture\n\nSpanish tiles are typically extruded: clay (or, for concrete versions, a cement mortar) is forced through a shaped die and cut to length before firing or curing. They are usually grouped in the same family as the pantile and the Scandinavian \"Scandia\" tile, all of which combine pan and cover in one piece.\n\n## Terminology\n\nNames vary by country and manufacturer:\n\n- In North America, \"Spanish tile\" usually means a one-piece S-tile, while \"mission\" or \"barrel\" tile means the two-piece system.\n- In the UK, a similar shape is generally called a pantile.\n- Some manufacturers use \"Spanish\" loosely for any red, curved Mediterranean-style tile.\n\nBecause of this inconsistency, specifiers usually refer to the exact profile and manufacturer rather than the generic name.\n\n## Use\n\nS-tiles are widespread in Spain and Portugal and throughout Latin America, and are common in Florida, California and the US Southwest. Concrete S-tiles are widely used where clay is more expensive.\n\n## Performance\n\nLike other curved tiles, S-tiles leave an air channel beneath each roll, which reduces heat transfer and allows some drying. Their open ends at the eaves and ridge are normally closed with special bird-stop pieces, mortar or proprietary closures. In hurricane-prone regions, codes require each tile to be fastened mechanically or with approved foam adhesives.\n","key_facts":[{"label":"Profile","value":"One-piece, deep S-curve"},{"label":"Usual manufacture","value":"Extruded clay or concrete"},{"label":"Related forms","value":"Pantile, Scandia tile, mission (two-piece) tile"}],"regions":["Europe","Latin America","North America"],"aliases":["S-tile","Spanish S tile","one-piece barrel tile"],"related":["mission-tile","pantile","clay-roof-tile","concrete-roof-tile"],"sources":[{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"},{"title":"Roof","url":"https://en.wikipedia.org/wiki/Roof","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"spray-polyurethane-foam-roofing","title":"Spray Polyurethane Foam (SPF) Roofing","category":"low-slope-systems","type":"article","summary":"A seamless roof made by spraying two-part rigid polyurethane foam onto the substrate and covering it with an elastomeric coating or aggregate.","body":"Spray polyurethane foam (SPF) roofing is formed on site by mixing two liquid components, an isocyanate (A side, typically polymeric MDI) and a polyol blend (B side), in a heated spray gun. The mixture expands within seconds into closed-cell rigid foam that bonds to the deck or existing roof. Because foam degrades in sunlight, it is always covered with a protective coating or aggregate.\n\n## Properties\n\n- **Density:** typically about 40-64 kg/m3 (2.5-4.0 lb/ft3) for roofing foam.\n- **Compressive strength:** usually above 276 kPa (40 psi).\n- **Insulation:** about R-5.5 to R-6.5 per inch (RSI roughly 0.97-1.14 per 25 mm).\n- **Weight:** coated SPF adds less than about 2.4 kg/m2 per 25 mm (0.5 lb/sq ft per inch); aggregate-covered SPF adds about 49 kg/m2 (10 lb/sq ft).\n\n## Installation\n\nFoam is applied in passes of at least 13 mm (1/2 in), usually no more than 38-51 mm (1 1/2-2 in) each, to a minimum total of 25 mm (1 in). Thickness can be varied to build slope toward drains and fill low areas, which makes SPF popular for re-covering old roofs. The base coat should be applied the same day or within 24 hours.\n\n## Coatings and surfacing\n\nCoatings must be elastomeric. Common types are acrylic, silicone, polyurethane, polyurea and butyl, typically 0.5-1.0 mm (20-40 mils) dry. Granules can be broadcast into the wet coating for traffic and hail resistance. Loose aggregate surfacing is limited to slopes of about 1/2 in per 12 in or less; coated SPF can be used on any slope.\n\n## Codes and performance\n\nThe IBC requires a minimum design slope of 1/4 in per 12 in for SPF roofs. Fire classification follows ASTM E108/UL 790, and uncoated foam must have a flame spread index of 75 or less (ASTM E84). Because foam bonds without fasteners, uplift resistance usually depends on the substrate; pull tests on decks have reached about 43 kPa (900 psf). Hail usually causes surface damage that seldom leaks and can be repaired with sealants.\n\n## Service life\n\nMaintained SPF roofs have documented lives exceeding 30 years, with recoating usually needed every 10 to 20 years. Inspections in spring and autumn are recommended. The US trade body is the Spray Polyurethane Foam Alliance (SPFA), founded in 1987.","key_facts":[{"label":"Density","value":"40-64 kg/m3 (2.5-4.0 lb/ft3)"},{"label":"R-value","value":"About R-5.5 to 6.5 per inch"},{"label":"Minimum thickness","value":"25 mm (1 in)"},{"label":"Coating thickness","value":"0.5-1.0 mm (20-40 mils) dry"},{"label":"Recoat interval","value":"About 10-20 years"},{"label":"IBC minimum slope","value":"1/4:12 (2%)"}],"regions":["North America","Global","Middle East"],"aliases":["SPF roof","spray foam roof","foam roofing","sprayed polyurethane foam"],"related":["acrylic-roof-coating","silicone-roof-coating","roof-coating","liquid-applied-roofing","tapered-insulation"],"company":null,"sources":[{"title":"RICOWI Roof Guide: Spray Foam","url":"https://ibhs.org/guidance/ricowi-roof-guide-spray-foam/","publisher":"IBHS / RICOWI"},{"title":"Spray foam","url":"https://en.wikipedia.org/wiki/Spray_foam","publisher":"Wikipedia"},{"title":"Minn. R. 1305.1507 - Requirements for Roof Coverings (IBC Section 1507 amendments)","url":"https://www.law.cornell.edu/regulations/minnesota/Minn-R-1305-1507","publisher":"Cornell Law School LII"},{"title":"Cool Roofs","url":"https://www.energy.gov/energysaver/cool-roofs","publisher":"U.S. Department of Energy"}],"country":null},{"slug":"spray-polyurethane-foam-application","title":"Spray Polyurethane Foam Application","category":"installation","type":"article","summary":"SPF roofing is applied by spraying two liquid components that react and expand into a seamless foam layer, then protecting it with a coating.","body":"**Spray polyurethane foam (SPF)** roofing is a low-slope system built in place by spraying a two-component liquid onto the roof. The liquids react and expand into rigid, closed-cell foam that bonds to the substrate, insulates, and forms a seamless layer that can be shaped to improve drainage. Because polyurethane foam degrades in sunlight, it is covered with a protective elastomeric coating or other surfacing.\n\n## Chemistry\n\nThe US Environmental Protection Agency describes SPF as a reaction between an **A side**, containing isocyanates such as MDI, and a **B side**, containing polyols with catalysts, flame retardants, blowing agents and surfactants. The two are mixed in roughly equal proportions and the reaction gives off heat as the foam forms. Roofing foam is applied with high-pressure equipment that heats and pumps both components to a spray gun.\n\n## Typical application sequence\n\n1. **Inspect and prepare.** Remove loose material, wet insulation and contaminants; the substrate must be clean and dry.\n2. **Prime** where the manufacturer requires it.\n3. **Mask and protect** nearby surfaces, vehicles and air intakes, since overspray can travel.\n4. **Spray in passes.** Foam is built up in layers to the specified thickness, with extra thickness to fill low spots and create slope to drains.\n5. **Inspect the foam surface.** Texture is checked; rough or blistered areas are corrected.\n6. **Apply the coating.** An elastomeric coating (often acrylic, silicone or polyurethane) is applied in one or more coats, sometimes with embedded granules for foot traffic.\n\n## Weather and conditions\n\nMoisture, low temperatures and wind affect foam quality and overspray. Applicators monitor substrate and air temperatures, humidity and wind speed against the manufacturer's limits, and stop work in rain or dew conditions.\n\n## Health and safety\n\nIsocyanates are respiratory and skin sensitisers. The EPA notes that spraying can produce aerosols and vapours, and that people already sensitised can react severely even to low concentrations. Applicators use respiratory and skin protection, and access to the area is controlled during and after spraying. The European Union requires training for professional users of products containing diisocyanates.\n\n## Other uses\n\nIn parts of Southeast Asia, foam is sprayed onto the underside of tile and metal roofs to seal and insulate them.","key_facts":[{"label":"Components","value":"A side (isocyanate) and B side (polyol blend)"},{"label":"Protection","value":"Elastomeric coating required against UV"},{"label":"Main hazard","value":"Isocyanate exposure during spraying"}],"regions":["Global"],"aliases":["SPF roofing","spray foam roofing","polyurethane foam roof"],"related":["roof-coating-application","low-slope-roof"],"company":null,"sources":[{"title":"Chemicals and Production of Spray Polyurethane Foam: Why It Matters","url":"https://archive.epa.gov/epa/saferchoice/chemicals-and-production-spray-polyurethane-foam-why-it-matters.html","publisher":"U.S. Environmental Protection Agency"},{"title":"Spray foam","url":"https://en.wikipedia.org/wiki/Spray_foam","publisher":"Wikipedia"}],"country":null},{"slug":"spri","title":"SPRI","summary":"SPRI is a U.S. trade association of single-ply membrane and roofing component suppliers that develops ANSI wind-design and edge standards.","body":"SPRI is a trade association in the United States that represents manufacturers and suppliers of sheet membranes and related components for commercial low-slope roofing. Its members make single-ply membranes such as EPDM, TPO and PVC, as well as insulation, fasteners, adhesives, edge metal and drains. A 2004 profile described it as having represented these suppliers for more than 20 years. Its website is spri.org.\n\n## Standards work\n\nSPRI is best known for developing consensus standards through the American National Standards Institute (ANSI) process. It became an official ANSI canvasser in 1994. Its standards are cited by designers, building codes and insurers. Examples include:\n\n- **ANSI/SPRI ES-1** – wind design for edge systems (such as copings and gravel stops) on low-slope roofs. Roof edges are where wind uplift failures often start, so this standard is widely referenced. Later editions were published jointly with FM Approvals.\n- **ANSI/SPRI RP-4** – wind design for ballasted single-ply roof systems, which use stone or pavers to hold the membrane down.\n- **ANSI/SPRI RD-1** – retrofit roof drains.\n- **ANSI/SPRI FX-1** – field test procedures for the pull-out resistance of roofing fasteners.\n\nSPRI also offers educational presentations and tools on wind design for low-slope roofs.\n\n## Other activities\n\nThe association holds conferences, publishes technical bulletins and environmental product declarations for membrane types, and works with other organisations such as roofing contractor associations and building consultant groups.\n\n## Context\n\nSingle-ply roofs are common on commercial, industrial and institutional buildings in North America, Europe and elsewhere. In the United Kingdom, the Single Ply Roofing Association plays a similar but separate role. SPRI standards are U.S.-based; other countries rely on their own wind-load codes and European or national standards.","key_facts":[{"label":"Country","value":"United States"},{"label":"ANSI canvasser since","value":"1994"},{"label":"Key standards","value":"ES-1, RP-4, RD-1, FX-1"},{"label":"Website","value":"spri.org"}],"regions":["North America"],"aliases":["Single Ply Roofing Industry"],"related":["single-ply-roofing","tpo-roofing","epdm-roofing","wind-uplift","single-ply-roofing-association"],"company":{"website":"https://www.spri.org","known_for":["ANSI/SPRI ES-1 edge standard","ANSI/SPRI RP-4 ballasted wind standard"]},"sources":[{"title":"SPRI builds on record of accomplishment","url":"https://www.roofingcontractor.com/articles/85078-spri-builds-on-record-of-accomplishment","publisher":"Roofing Contractor"},{"title":"SPRI ANSI standards: standardizing roof system performance","url":"https://iibec.org/publication-post/spri-ansi-standards-standardizing-roof-system-performance/","publisher":"IIBEC"},{"title":"Single Ply Roofing Industry publications","url":"https://www.theNBS.com/PublicationIndex/documents?Pub=SPRI","publisher":"NBS"}],"category":"organizations","type":"organization","country":null},{"slug":"st-pauls-cathedral-dome","title":"St Paul's Cathedral Dome","category":"history","type":"place","summary":"Christopher Wren's triple-layered dome over St Paul's Cathedral, London, completed in 1708-1711 and rising 111 m (365 ft) to the cross.","body":"The dome of **St Paul's Cathedral** in London, designed by **Sir Christopher Wren**, is one of the largest and most influential church domes in the world. It replaced the medieval cathedral destroyed in the Great Fire of London in 1666, whose own tall spire had already been lost to lightning in 1561.\n\n## Building the cathedral\n\nConstruction of the new cathedral ran from **1675 to 1710**. The building was consecrated on **2 December 1697**, while work continued. The final stone was placed on the lantern on **26 October 1708**, and Parliament declared the cathedral officially complete on **25 December 1711**.\n\n## A three-part dome\n\nRather than a single shell, Wren built the dome as three separate structures:\n\n1. An **inner dome** of brick, seen from inside the cathedral, with an oculus at its apex inspired by the Pantheon.\n2. A **brick cone**, hidden between the two visible domes. It carries the heavy stone **lantern**, which weighs about 850 tons, and supports the outer dome.\n3. An **outer dome** of timber framing covered in **lead**, which gives the familiar silhouette over the London skyline.\n\nThe inner dome and the cone are each about 457 mm (18 in) thick. Wrought iron chains bind them to stop them spreading and cracking under their own outward thrust.\n\n## Height\n\nThe dome and lantern rise to about 111 m (365 ft) at the top of the cross.\n\n## Survival\n\nThe dome survived the Blitz of the Second World War. Bombs struck the cathedral on 10 October 1940 and 17 April 1941; the second is believed to have shifted the dome slightly sideways. Anti-aircraft damage to the dome was repaired by 1967, and a 15-year restoration programme was completed on 15 June 2011.\n\n## Significance\n\nThe design shows how a lightweight timber-and-lead outer roof can create a monumental external form, while the real structural work is done by a concealed masonry cone. It is a frequently cited example of separating a roof's appearance from its structure.","key_facts":[{"label":"Architect","value":"Sir Christopher Wren"},{"label":"Built","value":"1675-1710 (declared complete 1711)"},{"label":"Height to cross","value":"About 111 m (365 ft)"},{"label":"Outer covering","value":"Lead over timber"},{"label":"Lantern weight","value":"About 850 tons"}],"regions":["Europe"],"aliases":["St Paul's dome","Wren's dome"],"related":["great-fire-of-london","pantheon-dome","florence-cathedral-dome","medieval-lead-roofs","dome"],"company":null,"sources":[{"title":"St Paul's Cathedral","url":"https://en.wikipedia.org/wiki/St_Paul%27s_Cathedral","publisher":"Wikipedia"},{"title":"Great Fire of London","url":"https://en.wikipedia.org/wiki/Great_Fire_of_London","publisher":"Wikipedia"}],"country":null},{"slug":"st-stephens-cathedral-roof","title":"St Stephen's Cathedral Roof","category":"world-roofing","type":"place","summary":"The steep glazed-tile roof of St Stephen's Cathedral in Vienna, about 230,000 tiles forming eagles and coats of arms, rebuilt on steel after a 1945 fire.","body":"The roof of **St Stephen's Cathedral** (*Stephansdom*) in Vienna is one of the best-known tiled roofs in the world. Its very steep slopes are covered with about 230,000 glazed tiles laid in a bold, multi-coloured pattern that includes large heraldic images, making the roof a symbol of the city.\n\n## Dimensions\n\nThe roof is 111 m (364 ft) long and rises 38 m (125 ft) above the cathedral floor. Its steepness is often credited with keeping it clean: it is mainly washed by rain and is seldom covered by snow, although this claim is not well documented.\n\n## Pattern\n\nThe glazed tiles form an ornate, richly coloured pattern. Above the choir on the south side, a mosaic of tiles shows the double-headed eagle, a symbol of the Habsburg empire. On the north side, the tiles show the coats of arms of the City of Vienna and of the Republic of Austria.\n\n## Destruction in 1945\n\nIn the last days of the Second World War, fires in nearby buildings spread to the cathedral. A fire started by looters on 12 April 1945 was carried by the wind, reached the north tower and destroyed the timber roof structure, which collapsed.\n\n## Rebuilding\n\nReconstruction began immediately after the war. Replicating the original timber bracing was judged too expensive, so more than 600 tonnes (about 660 short tons) of steel bracing was installed instead, and the roof was re-covered with glazed tiles in the traditional pattern. The cathedral partly reopened on 12 December 1948 and fully reopened on 23 April 1952.\n\n## Significance\n\nThe roof shows several features of central European church roofing: a very steep pitch suited to snow and to the tall Gothic form, durable glazed ceramic tiles, and the use of colour and heraldry to make the roof itself a display surface. Its post-war rebuilding on steel is an example of a common heritage choice, keeping the visible historic covering while replacing a lost structure with a modern one.\n\n## Sources and gaps\n\nThe tile manufacturers and the dates of later tile repairs: published information is limited.","key_facts":[{"label":"Location","value":"Vienna, Austria"},{"label":"Glazed tiles","value":"About 230,000"},{"label":"Length","value":"111 m (364 ft)"},{"label":"Height above floor","value":"38 m (125 ft)"},{"label":"Fire","value":"April 1945"},{"label":"New structure","value":"Over 600 t of steel bracing"}],"regions":["Europe"],"aliases":["Stephansdom roof","Vienna cathedral roof"],"related":["glazed-roof-tile","roofing-in-austria","notre-dame-de-paris-roof-fire","history-of-timber-roof-framing"],"company":null,"sources":[{"title":"St. Stephen's Cathedral, Vienna","url":"https://en.wikipedia.org/wiki/St._Stephen%27s_Cathedral,_Vienna","publisher":"Wikipedia"},{"title":"Historische Dachdeckungen","url":"https://www.baunetzwissen.de/altbau/fachwissen/dach-deckungen/historische-dachdeckungen-2949105","publisher":"Baunetz Wissen"}],"country":null},{"slug":"stainless-steel-roofing","title":"Stainless Steel Roofing","category":"materials","type":"article","summary":"Stainless steel roofing uses chromium-alloyed steel sheet, either bare or tin-coated, for long-life standing seam, seamed or shingle roofs.","body":"Stainless steel is iron alloyed with 10.5% or more chromium. The chromium forms a thin, self-healing passive film, so the metal does not need a zinc or paint coating to resist rust. In roofing it is used for roll-formed standing seam panels, traditional hand-seamed roofs, individual shingles, gutters and flashings, and very widely for fasteners and concealed cleats.\n\n## Grades and finishes\n\nDifferent grades suit different exposures. For tin-coated (terne-coated) stainless roofing, ferritic grade 439 is used in normal environments and the molybdenum-bearing austenitic grade 316L near the coast, where chlorides are a concern. Tin-coated versions weather to a soft matte grey.\n\n## Behaviour on the roof\n\n- **Thermal movement**: austenitic grades such as 304 expand about 17 x 10^-6 per degree C (about 9.6 x 10^-6 per degree F), noticeably more than carbon steel, so long panels need clips that allow sliding.\n- **Galvanic position**: stainless is close to copper on the galvanic scale, so 300-series stainless fasteners are the usual choice with copper roofing, but stainless will accelerate corrosion of zinc, galvanized steel or aluminium in contact with it in wet conditions.\n\n## Use in restoration\n\nStainless is also the base metal of terne-coated stainless, the common replacement for historic terne roofs.","key_facts":[{"label":"Defining alloy content","value":"At least 10.5% chromium"},{"label":"Typical grades in roofing","value":"439 (inland), 316L (coastal), 304/300-series fasteners"},{"label":"Thermal expansion (304)","value":"About 17.3 x 10^-6/K (9.6 x 10^-6/F)"}],"regions":["Global"],"aliases":["stainless steel roof","inox roofing"],"related":["terne-coated-stainless-steel","galvanic-corrosion","standing-seam-metal-roof","metal-roof-fasteners","thermal-movement-in-metal-roofs"],"company":null,"sources":[{"title":"Terneplate","url":"https://en.wikipedia.org/wiki/Terneplate","publisher":"Wikipedia"},{"title":"Busting 5 Metal Roofing Myths","url":"https://www.rooferscoffeeshop.com/post/busting-5-metal-roofing-myths-2","publisher":"RoofersCoffeeShop"},{"title":"Coefficients of Linear Thermal Expansion","url":"https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html","publisher":"The Engineering ToolBox"},{"title":"Galvanic corrosion","url":"https://en.wikipedia.org/wiki/Galvanic_corrosion","publisher":"Wikipedia"},{"title":"Stainless steel","url":"https://en.wikipedia.org/wiki/Stainless_steel","publisher":"Wikipedia"}],"country":null},{"slug":"standard-industries","title":"Standard Industries","category":"manufacturers","type":"company","summary":"Standard Industries is a privately held New York-based industrial group that owns GAF, BMI Group, Siplast and other building-materials businesses.","body":"Standard Industries is a privately held holding company headquartered in New York City. It traces its lineage to the Standard Paint Company of 1886, the same root as the roofing manufacturer GAF, and has grown through acquisitions into one of the largest owners of roofing and waterproofing businesses in the world. Its chief executive is David Winter.\n\n## Roofing holdings\n\nThe group's roofing interests span several continents:\n\n- **GAF**, the North American maker of asphalt shingles and commercial roofing, which merged with ElkCorp in 2007.\n- **BMI Group**, a European-based roofing and waterproofing group formed after Standard bought Denmark's Icopal in January 2016 (for roughly EUR 1 billion) and Germany's Braas Monier Building Group in April 2017 (for about EUR 1.1 billion). BMI combines concrete and clay roof tiles with bituminous and synthetic waterproofing.\n- **Siplast**, a manufacturer of roofing and waterproofing systems, mainly modified-bitumen based.\n- **GAF Energy**, launched in January 2019 to develop roof-integrated solar products.\n- **Specialty Granules (SGI)**, a North American aggregates and mining business that supplies mineral granules of the kind used to surface asphalt shingles.\n\n## Other businesses\n\nOutside roofing, Standard owns Schiedel, a European maker of chimney and ventilation systems, and the specialty chemicals company W. R. Grace, which it acquired in 2021 in a transaction valued at about USD 7 billion. It also operates an investment arm, Standard Investments.\n\n## Significance in roofing\n\nThrough GAF and BMI, Standard Industries is present in both the asphalt-shingle markets of North America and the tile and membrane markets of Europe, which differ considerably in materials and installation traditions. The group does not publish detailed public financial statements because it is privately held.","key_facts":[{"label":"Lineage","value":"Standard Paint Company, 1886"},{"label":"Headquarters","value":"New York City, US"},{"label":"Ownership","value":"Privately held"},{"label":"Roofing companies","value":"GAF, BMI Group, Siplast, GAF Energy"}],"regions":["North America","Europe","Global"],"aliases":["Standard Industries Holdings"],"related":["gaf","bmi-group","icopal","braas"],"company":{"founded":"1886","headquarters":"New York City, United States","website":"https://standardindustries.com","known_for":["Owner of GAF","Owner of BMI Group","Owner of Siplast"]},"sources":[{"title":"Standard Industries","url":"https://en.wikipedia.org/wiki/Standard_Industries","publisher":"Wikipedia"},{"title":"Who we are","url":"https://standardindustries.com/who-we-are","publisher":"Standard Industries"}],"country":null},{"slug":"standing-seam-clips","title":"Standing Seam Clips (Fixed and Sliding)","category":"components","type":"article","summary":"Standing seam clips are concealed brackets that hold panels down at the seams; fixed clips pin the panel, sliding clips let it move with temperature.","body":"Clips are the concealed connections between standing seam panels and the deck or purlins below. Each clip is screwed down and has a tab that is captured in the seam of the panel. Clips resist wind uplift and, just as importantly, decide how the panel is allowed to move as it expands and contracts.\n\n## Types\n\n- **Fixed clips**: a single piece that locks the panel in place. Panels may be fixed at one zone only (often near the ridge or mid-slope) so that they move away from that point.\n- **Sliding, expansion or floating clips**: usually two-piece, with a base fixed to the structure and a tab that can slide within it, allowing the panel to travel lengthwise. They are particularly important on long panels and on aluminium, which moves the most.\n- **Cleats**: in traditional copper, zinc and terne roofing, small strips of the same or compatible metal, often at about 12 in (300 mm) centres, do the job of clips. Specifications call for fixed or expansion cleats designed not to unhook under thermal movement.\n\n## Selection\n\nClip choice and spacing depend on the specific system and its manufacturer's specifications, the panel profile, the metal, the deck type, local codes and the design wind load. Corner and perimeter zones usually need closer spacing. One federal specification for copper roofing requires multi-piece clips for panels wider than 12 in and stainless steel screws, with nails not permitted for clip fastening. Bearing plates are sometimes used under clips on insulated assemblies.\n\n## Industry guidance\n\nThe Metal Construction Association's best practices guide for standing seam roof clips, published in 2018, addresses selecting and using clip connections so that systems accommodate thermal movement and resist attachment fatigue. As the association put it, correct attachment is central to the long-term performance of metal roofs.\n\n## Common mistakes\n\nUsing only fixed clips on long panels, mixing clip types from different systems, over-tightening or misaligning clips, and fastening through panels at both ends all restrain movement and can lead to oil canning, clip failure and seam damage.","key_facts":[{"label":"Fixed clip","value":"Pins panel; one fixed zone per panel"},{"label":"Sliding clip","value":"Usually two-piece; allows lengthwise movement"},{"label":"Typical cleat spacing (copper)","value":"About 12 in (300 mm)"},{"label":"MCA guide published","value":"2018"}],"regions":["Global"],"aliases":["standing seam clips","expansion clips","floating clips","sliding clips","cleats","standing seam cleats"],"related":["standing-seam-metal-roof","thermal-movement-in-metal-roofs","oil-canning","wind-uplift-testing-metal-roofs","standing-seam-installation","mechanical-seaming"],"company":null,"sources":[{"title":"MCA publishes best practices guide for standing seam roof clips","url":"https://designandbuildwithmetal.com/industry-news/2018/05/21/mca-publishes-best-practices-guide-for-standing-seam-roof-clips","publisher":"Design & Build with Metal"},{"title":"Section 07 61 16 Sheet Metal Roofing (VA master specification)","url":"https://www.wbdg.org/FFC/VA/VANCAS/VANCA076116.pdf","publisher":"Whole Building Design Guide / U.S. Department of Veterans Affairs"},{"title":"14.3. Copper Roofing (architectural specifications)","url":"https://archive.copper.org/applications/architecture/arch_dhb/specifications/arch_specs/sheet_roofing.php","publisher":"Copper Development Association"},{"title":"Essential Zinc: Building for the Future","url":"https://continuingeducation.bnpmedia.com/courses/umicore-building-products-usa-inc/essential-zinc-building-for-the-future/2/","publisher":"Continuing Education Center (BNP Media) / Umicore Building Products"},{"title":"How Is a Standing Seam Metal Roof Installed? (Step by Step)","url":"https://www.interlockroofing.com/kb/how-is-a-standing-seam-metal-roof-installed/","publisher":"Interlock Roofing"},{"title":"Cleat: Definition, Uses & Benefits in Roofing Systems","url":"https://www.interlockroofing.com/glossary/cleat/","publisher":"Interlock Roofing"},{"title":"Fasteners: Definition, Types & Benefits for Roofing","url":"https://www.interlockroofing.com/glossary/fasteners/","publisher":"Interlock Roofing"},{"title":"NZ Metal Roof and Wall Cladding Code of Practice: Thermal Expansion and Contraction","url":"https://www.metalroofing.org.nz/cop/roofing/thermal-expansion-and-contraction","publisher":"NZ Metal Roofing Manufacturers Inc."},{"title":"Standing seam metal roof","url":"https://en.wikipedia.org/wiki/Standing_seam_metal_roof","publisher":"Wikipedia"},{"title":"Canadian Roofing Reference Manual: 10.8 Metal Roofing Application","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-10-metal-roofing/10-8-application/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"standing-seam-installation","title":"Standing Seam Installation","category":"installation","type":"article","summary":"Standing seam installation fixes long metal panels to the deck with concealed clips and joins them along raised seams that are snapped or mechanically seamed.","body":"A **standing seam** roof uses long metal panels that run from eave to ridge and join along raised vertical seams. The fastening is concealed: clips fixed to the deck engage the panel edges and are covered by the next panel's seam. Panels may be factory-made or roll-formed on site from steel, aluminium, copper or zinc.\n\n## Panel types\n\n- **Snap-lock.** One panel edge snaps over the edge of the adjoining panel and its clips without tools.\n- **Mechanically seamed.** The seam is folded with a hand or powered seamer into a **single lock** (one fold) or **double lock** (two folds, sometimes called a 180-degree or 360-degree seam). Double-lock seams give the highest weather resistance.\n- **Nail-strip (fastener-flange).** One edge is screwed through slotted holes and the next panel covers the screws.\n\nCommon panel widths are 12 to 18 in (300 to 460 mm) and seam heights about 1 1/2 to 1 3/4 in (38 to 44 mm).\n\n## Slope and underlayment\n\nCanadian guidance notes that most architectural metal roof systems are designed for a minimum slope of 1:4 (25 percent, or 3:12). Below that, mechanically seamed panels with sealant in the seams are required. The same guidance calls for at least one ply of No. 30 felt with a slip sheet where the panels could bond to it, plus eave, valley and penetration membranes.\n\n## Installation outline\n\n1. Install underlayment, eave and rake trims and any eave cleat.\n2. Lay out the panels so widths are balanced at each end of a visible roof plane and seams meet at hips and valleys.\n3. Set the first panel square to the eave, engaging or hemming its lower end over the eave cleat.\n4. Fix clips along the seam at the spacing required by the panel system and design wind loads.\n5. Place the next panel over the clips and snap or seam it.\n6. Finish with ridge, hip and wall flashings and closures.\n\n## Thermal movement\n\nMetal expands and contracts with temperature. Long panels must be able to move between eave and ridge, typically by fixing them at one point and using clips that let the panel slide elsewhere. Failure to allow for movement can loosen flashings and cause leaks. **Oil-canning**, a visible waviness in the flat pan, is a cosmetic issue reduced by thicker metal and stiffening ribs.","key_facts":[{"label":"Minimum slope, most systems (Canada)","value":"1:4 (3:12)"},{"label":"Typical panel width","value":"12-18 in (300-460 mm)"},{"label":"Typical seam height","value":"1 1/2-1 3/4 in (38-44 mm)"}],"regions":["Global"],"aliases":["standing seam roof installation","SSMR installation","seamed metal roofing"],"related":["mechanical-seaming","standing-seam-clips","through-fastened-panel-installation","standing-seam-metal-roof","oil-canning"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 10.8 Metal Roofing Application","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-10-metal-roofing/10-8-application/","publisher":"Canadian Roofing Contractors Association"},{"title":"Standing seam metal roof","url":"https://en.wikipedia.org/wiki/Standing_seam_metal_roof","publisher":"Wikipedia"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"NZ Metal Roof and Wall Cladding Code of Practice: Thermal Expansion and Contraction","url":"https://www.metalroofing.org.nz/cop/roofing/thermal-expansion-and-contraction","publisher":"NZ Metal Roofing Manufacturers Inc."}],"country":null},{"slug":"standing-seam-metal-roof","title":"Standing Seam Metal Roof","category":"materials","type":"article","summary":"A standing seam roof uses long metal pans joined by raised seams and held down by concealed clips, so no fasteners pierce the weathering surface.","body":"A standing seam roof is made of long, narrow metal panels (pans) that run from eave to ridge. Adjacent panels meet in upstanding seams, typically about 1 to 2 in (25 to 50 mm) high, which are folded, snapped or crimped together. The panels are held to the deck or purlins by clips hidden inside the seams, so the flat of the panel is not punctured. Because the clips can allow the panel to slide, the metal can expand and contract without tearing fasteners.\n\n## Variants\n\n- **Mechanically seamed**: seams are folded by a seaming tool into a single lock or double lock; this is the most weathertight and usually the most expensive type.\n- **Snap-lock**: one panel edge snaps over the other without seaming, either over clips or over an integral nailing flange.\n- **Batten seam**: panels butt against a batten that is covered by a cap.\n- **Hand-formed**: traditional copper, zinc and stainless roofs formed on site with tools.\n\n## Typical dimensions\n\nPanels commonly run in continuous lengths of up to about 30 ft (9 m) on residential work and much longer on commercial roofs, with widths of about 12 to 18 in (300 to 460 mm). Narrower pans are less prone to visible waviness (oil canning).\n\n## Materials\n\nCoated steel (usually with an aluminium-zinc coating such as Galvalume), aluminium (often 0.032 in, 0.81 mm), copper (16 or 20 oz), titanium-zinc and stainless steel are all used.\n\n## Design points\n\n- Thermal movement is handled with fixed clips at one zone and sliding clips elsewhere.\n- Engineered systems are tested for wind uplift, for example to ASTM E1592 or UL 580.\n- Snow retention devices can be clamped to seams without penetrating the panels.\n- Ends, ridges and penetrations need flashings that accommodate movement.\n\nStanding seam is widely used on homes, commercial and industrial buildings, and low-slope roofs where exposed fasteners would be risky.","key_facts":[{"label":"Attachment","value":"Concealed clips within the seams"},{"label":"Typical panel width","value":"12-18 in (300-460 mm)"},{"label":"Typical seam height","value":"1-2 in (25-50 mm)"},{"label":"Common steel coating","value":"Aluminium-zinc (e.g. Galvalume)"}],"regions":["Global"],"aliases":["SSMR","standing seam","concealed fastener metal roof","seamed metal roof"],"related":["mechanically-seamed-standing-seam","snap-lock-standing-seam","batten-seam-roofing","standing-seam-clips","oil-canning","thermal-movement-in-metal-roofs","snow-guards"],"company":null,"sources":[{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Section 07 61 16 Sheet Metal Roofing (VA master specification)","url":"https://www.wbdg.org/FFC/VA/VANCAS/VANCA076116.pdf","publisher":"Whole Building Design Guide / U.S. Department of Veterans Affairs"},{"title":"Myths About Metal Roofing: Heat, Wind and Lightning","url":"https://www.mbci.com/blog/myths-about-metal-roofing/","publisher":"MBCI"},{"title":"What Is a Standing Seam Metal Roof? (Complete Guide 2026)","url":"https://www.interlockroofing.com/kb/what-is-a-standing-seam-metal-roof/","publisher":"Interlock Roofing"},{"title":"How Is a Standing Seam Metal Roof Installed? (Step by Step)","url":"https://www.interlockroofing.com/kb/how-is-a-standing-seam-metal-roof-installed/","publisher":"Interlock Roofing"},{"title":"What Is Oil Canning? Metal Roof Waviness Explained","url":"https://www.interlockroofing.com/glossary/oil-canning/","publisher":"Interlock Roofing"}],"country":null},{"slug":"starter-course","title":"Starter Course","category":"installation","type":"term","summary":"A starter course is the first row of roofing material along the eaves (and often rakes) that seals and backs the first visible course of shingles.","body":"The **starter course** (or **starter strip**) is the strip of roofing installed along the eaves before the first visible row of shingles. Without it, water could run through the cutouts and joints of the first course straight onto the deck. A starter also provides a line of sealant that holds the first course down in wind. Starter strips are commonly installed along the rakes as well.\n\n## Materials\n\nStarters may be purpose-made strips with a factory sealant line, or field-cut from standard shingles with the tabs removed. Wood shingle and shake roofs start with a doubled first course, and tile roofs start with eave closures or a raised fascia.\n\n## Asphalt shingle details\n\nCanadian guidance describes:\n\n- a starter at least 225 mm (9 in) wide with an adhesive strip;\n- hand-tabbing to the first course if there is no factory sealant;\n- starter end joints offset from first-course joints by at least 125 mm (5 in); and\n- an overhang of about 19 mm (3/4 in) at eaves and rakes, or flush with a T-type metal drip edge.\n\nCommon US practice is an overhang of 1/4 to 3/4 in (6 to 19 mm) past the drip edge. Guidance based on the IBHS FORTIFIED programme limits the overhang to 1/4 in, sets the starter in roof cement or uses a self-adhered ASTM D1970 starter, nails it 2 to 3 in above the eave and laps rake starters over the eave starter by 3 in.\n\nWhen a 3-tab shingle is used, the exposed tabs are cut off and the sealant strip is placed nearest the eave so it bonds to the underside of the first course.\n\n## Common faults\n\n- Starter installed with the sealant at the top instead of the eave.\n- Joints in the starter lining up with joints in the first course.\n- Nails placed where they show through the cutouts of the first course.\n- Too much or too little overhang, leading to blow-off or water running onto the fascia.","key_facts":[{"label":"Minimum width (Canada)","value":"225 mm (9 in)"},{"label":"Joint offset from first course (Canada)","value":"125 mm (5 in) or more"},{"label":"Typical eave overhang","value":"6-19 mm (1/4-3/4 in)"}],"regions":["Global"],"aliases":["starter strip","starter row","eave starter"],"related":["shingle-nailing-pattern","shingle-exposure-and-offset","asphalt-shingle","drip-edge"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.1.2 Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-1-asphalt-shingles/9-1-2-installation/","publisher":"Canadian Roofing Contractors Association"},{"title":"Shingle Application Mechanics: Starter Courses, Offsets, Fastener Placement and Wind Sealant Activation","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-application-mechanics","publisher":"Open Exam Prep"},{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"}],"country":null},{"slug":"stave-church-roofs","title":"Stave Church Roofs","type":"article","summary":"Steep, tiered timber roofs of Norway's medieval stave churches, such as Urnes (UNESCO) and Borgund, built to shed heavy rain and snow.","body":"Stave churches are medieval wooden churches built on a frame of vertical posts (staves). Norway preserves most of the surviving examples: sources count 28 or 29 still standing. Their roofs are among the most striking features, rising in steep, stacked tiers over the nave and aisles.\n\n## Roof forms\n\nTwo broad structural types are recognised:\n\n- **Type A** churches have a single space whose roof is carried by trusses of principal rafters combined with crossing \"scissor\" rafters and braced with brackets.\n- **Type B** churches have a raised central nave with lower aisles around it, so the roof steps down in two or more levels, much like a stone basilica.\n\nIn the most elaborate churches, such as Borgund in Lærdal, further tiers of roof, an open gallery (*svalgang*) roofed around the outside, and a central turret produce a pyramid of steep planes.\n\n## Protection from weather\n\nNorway's climate brings cold winters, frost, heavy precipitation and strong winds. The survival of these timber buildings for 800 years or more is credited to design features that kept water away from the structure, such as massive sills beneath the posts, steep roofs that shed rain and snow quickly, and generous overhangs. Exterior timber, including roof coverings of wooden shingles, was traditionally protected with wood tar, which gives many churches their dark colour.\n\n## Notable examples\n\n- **Urnes**, in Luster, Vestland, dates from the first half of the 12th century and is a UNESCO World Heritage Site.\n- **Borgund**, in Lærdal, has been dated by dendrochronology to timber felled in 1180-1181.\n\n## Relationship to vernacular roofs\n\nOrdinary Norwegian houses of the same period usually had low-pitched roofs of birch bark and turf (*torvtak*), while churches and other high-status buildings used steeper roofs of boards, shingles or lead. Stave churches therefore show the high-status end of the Norwegian timber roofing tradition.\n\n## Conservation\n\nMaintaining stave church roofs involves regular re-tarring, replacement of weathered shingles in kind, and monitoring for rot at joints and eaves.","key_facts":[{"label":"Surviving churches","value":"28-29 in Norway"},{"label":"Structure","value":"Timber staves, scissor-rafter or basilica roofs"},{"label":"UNESCO site","value":"Urnes Stave Church"},{"label":"Borgund timber dated","value":"1180-1181"}],"regions":["Europe"],"aliases":["Stavkirke","Norwegian stave church"],"related":["torvtak","roofing-in-scandinavia","wood-shingle","wooden-churches-of-southern-malopolska"],"sources":[{"title":"Stave church","url":"https://en.wikipedia.org/wiki/Stave_church","publisher":"Wikipedia"},{"title":"Architecture of Norway","url":"https://en.wikipedia.org/wiki/Architecture_of_Norway","publisher":"Wikipedia"},{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"step-flashing","title":"Step Flashing","category":"components","type":"term","summary":"Step flashing is a series of small L-shaped pieces woven into each course of shingles or tiles where a roof slope meets a sidewall or chimney side.","body":"Step flashing is the method used to seal the joint where a sloping roof runs alongside a vertical wall, such as a dormer cheek, a second-storey wall or the side of a chimney. Instead of one long strip, it uses many short L-shaped (bent) pieces of metal. Each piece is laid over a course of shingles, with one leg on the roof and the other turned up the wall, and the next course of shingles covers its roof leg. The result steps up the slope, overlapping like the shingles themselves, so water is always shed onto the course below.\n\nIn the UK and Ireland, the equivalent concealed pieces under tiles and slates are called soakers, and the visible metal stepped into the brickwork above them is a stepped cover flashing.\n\n## Typical dimensions and installation (North America)\n\nUS Department of Energy guidance summarising the IRC calls for each piece to extend at least 4 in (102 mm) up the wall and 4 in (102 mm) onto the roof deck, with retrofit guidance suggesting 5 in (127 mm). Pieces must overlap shingle-fashion, each upper piece over the one below; underlapped pieces can channel water into the wall. Corrosion-resistant metal of at least 0.019 in (0.48 mm), about 26-gauge galvanised steel, is the usual minimum.\n\nKey details:\n\n- Underlayment is laid first and turned up the wall.\n- The wall's water-resistive barrier or house wrap laps over the top of the step flashing, not behind it.\n- Siding or cladding is held about 1 in (25 mm) above the roof surface.\n- The lowest piece at the eaves becomes or is followed by a kickout flashing.\n\n## Covering the top edge\n\nStep flashing is not sealed to the wall. Its upper edge is protected by the wall cladding or by a counter-flashing let into masonry. This allows the roof and wall to move independently.\n\n## Common faults\n\nUsing a single long piece instead of separate steps, nailing through the vertical leg low on the wall, missing kickouts, and caulk used in place of proper laps are frequent causes of sidewall leaks.","key_facts":[{"label":"Minimum legs (IRC)","value":"4 in (102 mm) up wall and onto roof"},{"label":"Minimum metal","value":"0.019 in (0.48 mm)"},{"label":"UK equivalent","value":"Soakers with stepped cover flashing"}],"regions":["North America","Global"],"aliases":["step flashings","sidewall flashing","soakers"],"related":["counter-flashing","kickout-flashing","lead-soakers","chimney-flashing","roof-flashing"],"company":null,"sources":[{"title":"Step and Kick-Out Flashing at Roof-Wall Intersections","url":"https://basc.pnnl.gov/resource-guides/step-and-kick-out-flashing-roof-wall-intersections","publisher":"Building America Solution Center (PNNL / US DOE)"},{"title":"Inspecting Step and Kick-Out Flashing","url":"https://nachi.org/inspecting-step-kick-out-flashing.htm","publisher":"InterNACHI"},{"title":"Flashing (weatherproofing)","url":"https://en.wikipedia.org/wiki/Flashing_(weatherproofing)","publisher":"Wikipedia"}],"country":null},{"slug":"step-flashing-installation","title":"Step Flashing Installation","category":"installation","type":"article","summary":"Step flashing is a series of L-shaped metal pieces woven into each course where a sloped roof meets a sidewall or chimney side.","body":"**Step flashing** waterproofs the joint where a sloping roof runs alongside a vertical wall, such as a dormer cheek, the side of a chimney or a two-storey wall. Instead of one long piece, it uses many short L-shaped pieces, one per course of shingles or tiles, each overlapping the one below like the roofing itself. This allows the roof and wall to move independently without opening a gap.\n\n## Typical dimensions\n\nCanadian guidance specifies pieces:\n\n- rectangular and 75 mm (3 in) longer than the shingle exposure;\n- bent to extend at least 100 mm (4 in) onto the roof and 100 mm (4 in) up the wall; and\n- lapped over the next piece by at least 75 mm (3 in).\n\nAt walls other than masonry, the vertical leg runs 100 mm (4 in) up the wall behind the cladding and its sheathing paper.\n\n## Installation steps\n\n1. Install the underlayment and turn it up the wall a short distance.\n2. Lay each course of shingles up to the wall.\n3. Place a step flashing piece on top of that course, just above the exposed edge, so the next course covers it.\n4. Fasten the piece with a single nail high in the roof leg, never into the wall leg, so the wall and roof can move separately.\n5. Lay the next course over the flashing and repeat.\n6. Lap the wall cladding (or counterflashing on masonry) over the vertical legs.\n\n## Kick-out flashing\n\nWhere a roof edge ends against a wall that continues below it, a **kick-out** (diverter) flashing at the bottom of the run turns water into the gutter rather than letting it run down behind the wall cladding. Building America guidance stresses integrating roof-wall flashings with both the underlayment and the wall's water-resistive barrier.\n\n## Other coverings\n\nOn tiled and slated roofs in the UK and Europe, lead soakers (the equivalent of step flashings) are often combined with stepped lead cover flashings dressed into the mortar joints of masonry. Metal roofs normally use a continuous sidewall flashing instead.","key_facts":[{"label":"Size (Canada)","value":"Exposure + 75 mm (3 in) long"},{"label":"Legs","value":"At least 100 mm (4 in) on roof and wall"},{"label":"Piece overlap","value":"At least 75 mm (3 in)"}],"regions":["Global"],"aliases":["step flashings","soakers","sidewall flashing"],"related":["chimney-flashing-installation","roof-flashing","kickout-flashing","skylight-flashing-installation"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.4.1 Intersection of Shingle Roofing and Masonry","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-1-intersection-of-shingle-roofing-and-masonry/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 9.4.3 Intersection of Roofing and Wall Cladding","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-3-intersection-of-roofing-and-wall-cladding-other-than-masonry/","publisher":"Canadian Roofing Contractors Association"},{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"}],"country":null},{"regions":["Europe"],"company":null,"slug":"gjirokaster-stone-roofs","title":"Stone Roofs of Gjirokastër","category":"world-roofing","type":"place","summary":"The flat dressed-stone roofs of Gjirokastër, Albania, an Ottoman-era hill town known as the \"City of Stone\" and a UNESCO World Heritage site.","aliases":["City of Stone","Gjirokastra roofs","Gjirokastër stone houses"],"body":"Gjirokastër, in southern Albania, is a hill town below a large castle whose houses are roofed with flat dressed stones. The grey stone roofscape gives the town its nickname, the \"City of Stone\". Its historic core was inscribed on the UNESCO World Heritage List in 2005, after a nomination in 1988, as a well-preserved Ottoman town, and Berat was later added to form the joint property \"Historic Centres of Berat and Gjirokastra\".\n\n## The houses\n\nGjirokastër's typical house is a tall block of stone up to five storeys high, with external and internal stairs. Its design is thought to derive from the fortified country houses of southern Albania. The lowest storey contains a cistern and a stable; above are a guest room and a family room with a fireplace, and higher floors housed extended families. UNESCO describes the type as a tower house (*kullë*), with a raised ground floor, a first floor for winter and a second floor for summer use, and richly decorated interiors with floral paintings in the guest rooms.\n\n## Dates\n\nFortified towers existed in Gjirokastër in the 13th century, before Ottoman rule. Most of the existing houses date from the 17th and 18th centuries, with more elaborate examples from the early 19th century. The Ottoman bazaar was built in the 17th century and rebuilt in the 19th after a fire, and the Gjirokastër Mosque of 1757 dominates it.\n\n## The roofs\n\nThe roofs are covered with flat dressed stones. A similar roofing style is found across the border in the Pelion district of Greece, and stone-slab roofs are also characteristic of nearby Epirus.\n\n## Conservation\n\nMore than 500 houses are preserved as cultural monuments. Many are being reconstructed, but others are deteriorating through lack of investment, abandonment or inappropriate renovation, a problem made worse because local craftsmen are often excluded from restoration projects.\n## Sources and gaps\n\nDetails of the stone source, slab sizes and laying methods: published information is limited.","key_facts":[{"label":"Roof covering","value":"Flat dressed stones"},{"label":"House dates","value":"Mostly 17th-18th centuries"},{"label":"Protected houses","value":"More than 500"},{"label":"UNESCO","value":"Inscribed 2005 (with Berat as extension)"}],"related":["roofing-in-albania","kulla-tower-house","stone-slate","zagori-stone-roofs","roofing-in-greece"],"sources":[{"title":"Gjirokastër","url":"https://en.wikipedia.org/wiki/Gjirokast%C3%ABr","publisher":"Wikipedia"},{"title":"Historic Centres of Berat and Gjirokastra","url":"https://whc.unesco.org/en/list/569","publisher":"UNESCO World Heritage Centre"},{"title":"Tower houses in the Balkans","url":"https://en.wikipedia.org/wiki/Tower_houses_in_the_Balkans","publisher":"Wikipedia"}],"country":null},{"regions":["Europe"],"company":null,"slug":"zagori-stone-roofs","title":"Stone Roofs of Zagori","category":"world-roofing","type":"place","summary":"Roofs of limestone or sandstone slabs, held by their own weight, on the stone villages of Zagori in Epirus, Greece, a UNESCO cultural landscape.","aliases":["Zagorochoria roofs","Epirus stone roofs"],"body":"**Zagori**, in Epirus in north-western Greece, is a group of 46 stone villages known as the Zagorochoria. Their houses, churches and even courtyard gates are roofed with stone slabs, and in September 2023 UNESCO inscribed Zagori as a cultural landscape representative of traditional stone-built settlements.\n\n## Roof construction\n\nZagori roofs are covered with stone tiles of local limestone or sandstone. They are laid without cement and held in place only by the weight of the tiles above them, over strong timber structures. Heavy winter snow means the roofs need continual upkeep. Church roofs are usually timber, covered with slate, and courtyard gates have small stone roofs of their own. In the wider region, similar stone roofing is found across the Albanian border at Gjirokastër and in the Pelion district of Greece.\n\n## The houses\n\nHouses are built of local stone, with walls up to a metre (3.3 ft) thick, some with a sand-filled compartment for insulation. Until the 18th century most were simple rectangular dwellings, often with only a ground floor and basement stables. During the 18th and 19th centuries they grew into more complex forms, up to the multi-storey mansions of wealthy families. Villages centre on a square (*mesochori*) with a large church, a plane tree and a fountain.\n\n## Bridges and churches\n\nMore than 160 arched stone bridges were built in the wider area, mostly in the 18th and 19th centuries, with one to three arches. Most churches date from the 17th and 18th centuries onward, and the main village church is usually a stone basilica.\n\n## Conservation\n\nBecause the slabs are dry-laid, maintenance means resetting slipped stones, replacing broken ones and repairing the timber beneath. Keeping these skills alive is essential to preserving the roofscape that underpins the UNESCO listing.","key_facts":[{"label":"Roof material","value":"Limestone or sandstone slabs, dry-laid"},{"label":"Villages","value":"46 (Zagorochoria)"},{"label":"UNESCO","value":"Cultural landscape, September 2023"}],"related":["roofing-in-greece","stone-slate","gjirokaster-stone-roofs","roofing-in-albania"],"sources":[{"title":"Zagori","url":"https://en.wikipedia.org/wiki/Zagori","publisher":"Wikipedia"},{"title":"Architecture of Greece","url":"https://en.wikipedia.org/wiki/Architecture_of_Greece","publisher":"Wikipedia"},{"title":"Gjirokastër","url":"https://en.wikipedia.org/wiki/Gjirokast%C3%ABr","publisher":"Wikipedia"}],"country":null},{"slug":"stone-slate","title":"Stone Slate","type":"article","summary":"A roofing unit split from sedimentary limestone or sandstone, laid in diminishing courses; traditional in parts of Britain, France and the Alps.","body":"A stone slate is a thick, flat roofing piece split from a sedimentary rock, usually limestone or sandstone, rather than from true metamorphic slate. Because they split along their original bedding planes, geologists call such rocks tilestones. Stone slate roofs are heavy, long-lived and strongly tied to local geology, and they give regions such as the Cotswolds and the Pennines in England much of their character. In France, flat roofing stones of this kind are called **lauzes**, and in the Swiss Alps roofs are made from stone slabs several inches thick.\n\n## Main English types\n\nHistoric England groups English stone slates by rock type:\n\n- **Limestone**: Purbeck (Dorset), Stonesfield and other Cotswold slates, Collyweston (Northamptonshire) and Whitwell magnesian limestone (Derbyshire).\n- **Sandstone**: Horsham stone (Sussex, Surrey, west Kent), Pennine sandstones from the Coal Measures and Millstone Grit, and Welsh Marches tilestones.\n\nSandstone and limestone slates should never be substituted for one another or mixed on a roof.\n\n## Production\n\nMost stone slates came from shallow surface workings called delves rather than deep mines; weathering weakens the bedding planes and makes splitting easier. At Collyweston and Stonesfield, blocks were wetted, covered and left over winter so that frost would split them, producing thinner, lighter slates. Slates were then dressed to shape and holed with a pointed tool, giving a tapered hole that grips a peg.\n\n## Laying\n\n- **Diminishing courses**: slates come in random sizes. The largest go at the eaves and the sizes reduce towards the ridge, while the headlap is kept constant.\n- **Pegs**: slates were traditionally hung on laths with dried oak pegs, often bedded in lime mortar at the head; copper nails or pegs are also used.\n- **Torching**: lime mortar mixed with aggregate and hair may be applied to the underside to steady the slates and reduce draughts.\n- **Swept valleys**: specially cut slates turn the roof through a curve in place of a metal valley.\n\nPitch depends on the slate: small, thin Cotswold slates need about 50°, while large, thick Pennine sandstone flags suit lower pitches.\n\n## Weight and life\n\nStone slate roofs are very heavy; Cotswold guidance gives about 1,000 kg per 10 m², or roughly 100 kg/m² (20 lb/ft²). With regular maintenance, including scraping off moss, a roof can last about 100 years and possibly 200-300 years.\n\n## Supply and conservation\n\nDeclining production has led to the use of imported, second-hand or artificial substitutes. Historic England's guidance favours new slates matching the original geology over second-hand slates (which should stay on the building they came from), and regards concrete and reconstituted stone as unsuitable for historic buildings. Some quarries have reopened to supply conservation work, including Horsham stone at Nowhurst in 2004 and a Collyweston mine approved in 2015.\n","key_facts":[{"label":"Rock types","value":"Sedimentary limestone or sandstone"},{"label":"Laying pattern","value":"Diminishing courses"},{"label":"Traditional fixing","value":"Oak pegs on laths"},{"label":"Approx. weight","value":"About 100 kg/m² (20 lb/ft²), Cotswold"},{"label":"Life with maintenance","value":"About 100 years or more"}],"regions":["Europe"],"aliases":["stone tile","tilestone","lauze","stone roof slab","stone slates"],"related":["cotswold-stone-slate","collyweston-stone-slate","stonesfield-slate","horsham-stone","natural-slate"],"sources":[{"title":"Stone Slate Roofing: Technical Advice Note","url":"https://cms.historicengland.org.uk/images-books/publications/stone-slate-roofing-technical-advice-note/stoneslate","publisher":"Historic England (English Heritage)"},{"title":"Cotswold Stone Slate Roofing: Technical Guidance","url":"https://www.cotswold.gov.uk/media/hojnam3m/cotswold-stone-slate-roofing-technical-guidance-2000.pdf","publisher":"Cotswold District Council"},{"title":"Lauze","url":"https://fr.wikipedia.org/wiki/Lauze","publisher":"Wikipédia (French)"},{"title":"Roof","url":"https://en.wikipedia.org/wiki/Roof","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"stone-coated-steel","title":"Stone-Coated Steel Roofing","category":"materials","type":"article","summary":"Stone-coated steel roofing is pressed metallic-coated steel panels bonded with natural stone granules to look like tile, shake or shingle.","body":"Stone-coated steel products are steel sheets, usually with a zinc or aluminium-zinc metallic coating, that are press-formed into multi-tile panels or shingle shapes and then coated with an acrylic base, natural stone granules and a clear overglaze. The granules give a textured, matte surface that imitates clay or concrete tile, wood shake or asphalt shingles, while the steel provides strength and light weight.\n\n## Profiles\n\nManufacturers offer profiles that copy Mediterranean barrel tile, scalloped tile, flat shingle and split shake. Panels are typically fixed to battens or directly to the deck and lock together at their edges.\n\n## Performance claims\n\nProduct literature commonly reports:\n\n- **Impact**: UL 2218 Class 4, the highest class in that test.\n- **Fire**: Class A fire ratings for complete assemblies.\n- **Wind**: testing to wind-driven rain and high-velocity hurricane zone protocols, with wind warranties stated in miles per hour by individual manufacturers.\n\nAs with any proprietary product, these ratings apply to the tested assembly and should be checked against the specific product listing.\n\n## Characteristics\n\n- Light compared with clay or concrete tile, so it can suit older structures and re-roofing.\n- The textured, three-dimensional surface helps disguise minor dents.\n- Cut edges and scratches expose the metallic coating and need appropriate touch-up as directed by the manufacturer.\n\n## Regional use\n\nStone-coated steel is generally traced to New Zealand and is used in many regions, particularly where heavy tile is impractical or where hail and hurricanes are concerns.\n\n## Installation notes\n\nBecause the panels are steel, their life depends on the metallic coating and the protection given by the stone layer. Profiles imitating tile and shake allow owners to keep the appearance of traditional roofs while reducing weight.","key_facts":[{"label":"Base","value":"Metallic-coated steel sheet"},{"label":"Surface","value":"Acrylic base, natural stone granules, overglaze"},{"label":"Common impact rating","value":"UL 2218 Class 4"},{"label":"Common profiles","value":"Tile, shake, shingle"}],"regions":["Global"],"aliases":["stone coated metal roofing","granular-coated steel","stone-chip coated steel tile","SCS roofing"],"related":["metal-roof-tiles","metal-shingles","hail-resistance-metal-roofs","galvalume"],"company":null,"sources":[{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"DECRA Metal Roofing","url":"https://www.decra.com/","publisher":"DECRA Roofing Systems"},{"title":"DECRA Celebrates 50 Years of Strength","url":"https://www.roofingcontractor.com/articles/85479-decra-celebrates-50-years-of-strength","publisher":"Roofing Contractor"},{"title":"Stone coated steel roofing: Definition, Pros & Benefits","url":"https://www.interlockroofing.com/glossary/stone-coated-steel-roofing/","publisher":"Interlock Roofing"}],"country":null},{"slug":"stonesfield-slate","title":"Stonesfield Slate","type":"term","summary":"A frost-split Jurassic limestone roofing slate from Stonesfield, Oxfordshire, used on prestigious Cotswold and Oxford buildings and famous for its fossils.","body":"Stonesfield slate is a thin, fissile limestone from around the village of Stonesfield in Oxfordshire, England, once heavily worked for roofing slates. It is one of the two main sources of traditional Cotswold stone slates and is also of great importance to palaeontology.\n\n## Geology\n\nThe slaty limestone horizons date from the Middle Jurassic, mid-Bathonian stage. Earlier work placed them in the Sharp's Hill Formation, but borehole and shaft evidence indicates that at least three horizons within the Taynton Limestone Formation were quarried. The surrounding rock is mostly ooidal grainstone, a limestone made of small rounded grains.\n\n## Production\n\nThe stone was mined in the 18th and 19th centuries. Like Collyweston slate, Stonesfield slate was split by frost: blocks were wetted, covered with earth and left until frosts froze the moisture in the stone and opened its bedding planes. Frost-split slates are thinner, lighter and more regular than hand-split slates. Cotswold guidance notes that Stonesfield slates were used on prestigious roofs such as those of Oxford colleges.\n\n## Fossils\n\nThe slate beds have yielded plants, insects, fish and vertebrates, including some of the earliest known mammals, pterosaurs and *Megalosaurus*, the first dinosaur ever scientifically described. The fossil plants, about 25 morphospecies, suggest a coastal, possibly seasonally dry environment with mangrove-like vegetation.\n\n## Today\n\nConservation guidance discourages stripping slates from one building to supply another; reclaimed slates should stay on the building or group they came from. Matching new limestone slates from other Cotswold sources, or from geologically similar sources, are used where the original cannot be found.\n","key_facts":[{"label":"Rock","value":"Middle Jurassic (Bathonian) limestone"},{"label":"Location","value":"Stonesfield, Oxfordshire, England"},{"label":"Peak working","value":"18th-19th centuries"},{"label":"Notable fossil","value":"Megalosaurus"}],"regions":["Europe"],"aliases":["Stonesfield stone slate"],"related":["cotswold-stone-slate","collyweston-stone-slate","stone-slate"],"sources":[{"title":"Stonesfield Slate","url":"https://en.wikipedia.org/wiki/Stonesfield_Slate","publisher":"Wikipedia"},{"title":"Stone Slate Roofing: Technical Advice Note","url":"https://cms.historicengland.org.uk/images-books/publications/stone-slate-roofing-technical-advice-note/stoneslate","publisher":"Historic England (English Heritage)"},{"title":"Cotswold Stone Slate Roofing: Technical Guidance","url":"https://www.cotswold.gov.uk/media/hojnam3m/cotswold-stone-slate-roofing-technical-guidance-2000.pdf","publisher":"Cotswold District Council"}],"category":"materials","company":null,"country":null},{"slug":"stramit","title":"Stramit","category":"manufacturers","type":"company","summary":"Stramit is an Australian maker of roll-formed steel roofing, walling, rainwater and structural products, part of Fletcher Building since 2005.","body":"Stramit Corporation is an Australian manufacturer and supplier of roll-formed steel building products, including roofing and wall cladding, rainwater goods, purlins and girts, and formwork and flooring. It is a member of the Fletcher Building Group of New Zealand, which acquired it in 2005.\n\n## History\n\nStramit's roots lie in several family-owned roofing, rainwater and roll-forming businesses, some dating to the 1890s. Stramit Industries was created in 1930 and made roofing, tiles and modular buildings.\n\n- **1985**: KH Consolidated acquires Stramit Industries, then JL Rolling Mills, and renames itself KH Stramit.\n- **1988**: Monier sells its concrete tile division and renames itself Amatek.\n- **1989**: Amatek and KH Stramit merge to form the present Stramit Corporation.\n- **1995**: Launch of Speed Deck Ultra, a concealed-fix roof deck, which received an Australian Design Award.\n- **2001**: Acquisition of Creeks Metal Industries in Victoria.\n- **2005**: Acquired by Fletcher Building.\n- **2007-2008**: Shed businesses Eziform, Fair Dinkum Sheds and Shed Boss join the group.\n- **2010**: Introduction of the FarLap roof lap joint system.\n- **2019**: The company marks its 30th anniversary.\n\n## Products\n\n- **Roofing and walling**: profiled steel sheets including Monoclad and the Speed Deck concealed-fix range (Speed Deck Ultra and Speed Deck 500).\n- **Rainwater products**: gutters and downpipes.\n- **Structural**: Exacta C and Z purlins and girts.\n- **Other**: formwork and flooring, ceiling systems, perforated sheets, sheds, and garage doors through Taurean Door Systems.\n\n## Context\n\nRoll-formers such as Stramit buy pre-painted or metallic-coated steel coil and form it into roofing and walling profiles close to the markets they serve. Stramit describes its products as Australian made and lists NATA accreditation.","key_facts":[{"label":"Formed","value":"1989 (Stramit Industries from 1930)"},{"label":"Country","value":"Australia"},{"label":"Parent","value":"Fletcher Building (since 2005)"},{"label":"Products","value":"Steel roofing, walling, rainwater, purlins"}],"regions":["Oceania"],"aliases":["Stramit Corporation","Stramit Building Products"],"related":["fletcher-building","bluescope","corrugated-iron","metal-roofing"],"company":{"founded":"1989","website":"https://www.stramit.com.au","parent":"Fletcher Building","known_for":["Speed Deck concealed-fix roofing","Monoclad cladding","Exacta purlins"]},"sources":[{"title":"Our history","url":"https://www.stramit.com.au/about-us/our-history","publisher":"Stramit"},{"title":"Stramit","url":"https://www.stramit.com.au/","publisher":"Stramit"}],"country":null},{"slug":"swahili-coral-stone-house","title":"Swahili Coral-Stone House","category":"world-roofing","type":"term","summary":"The Swahili coral-stone house of the East African coast has lime-bonded coral walls and heavy coral roofs on mangrove-pole joists that limit rooms to about 3 m wide.","body":"The coral-stone house is the characteristic urban building of the Swahili coast of East Africa, from Kenya's Lamu archipelago and Mombasa to Zanzibar and Kilwa in Tanzania. Its walls are coral rag or coral blocks set in lime, and its roofs and upper floors are thick layers of coral and lime laid over closely spaced mangrove-pole joists. Two of its towns, Lamu Old Town in Kenya and the Stone Town of Zanzibar, are UNESCO World Heritage Sites.\n\n## History\n\nSwahili trading towns began building in stone in the late first millennium. At Shanga, in the Lamu archipelago, stone building started in the early to mid-10th century. At Kilwa Kisiwani in Tanzania, the Great Mosque's 12th-century prayer hall was fully roofed on coral and later timber pillars; a vaulted southern extension followed in 1294-1302 and a large dome in the early 14th century, showing that coastal builders could roof in vaults and domes as well as flat slabs. At Gedi in Kenya (12th to 16th centuries), mosque roofs rested on timber beams carried by square stone pillars. Lamu has been inhabited continuously for more than 700 years, and most of Zanzibar's Stone Town dates from its 19th-century trading boom.\n\n## Construction of the roof\n\nIn Lamu houses, walls are uncoursed coral blocks in lime mortar. Roofs and floors are thick coral laid on wooden joists spaced about 30 cm (12 in) on centre. The joists are mangrove poles, harvested from coastal mangrove forests and still sold on the Lamu waterfront for roofing. Scholars have suggested that the mangrove pole sets the module of the house: its practical span limits each room, which is why rooms are often only about 3 m (10 ft) wide.\n\nLime was made by burning coral and ageing it to a fine powder; mortar for structural work was strengthened with broken seashell. In Zanzibar, builders combined coral rag, lime, mangrove poles and coconut palm material in multi-storey buildings.\n\nThe flat roof was used as living and working space: a roof terrace over the outer living room served for drying laundry, and a small cooking penthouse, often under a thatched shelter (*kidara cha meko*), kept smoke away from the fine lime plaster below.\n\n## Maintenance and decline\n\nCoral stone is friable and needs frequent maintenance, and many historic houses are in poor repair: in Zanzibar's Stone Town about 80% of its 1,709 buildings were reported to be deteriorating. Traditional building knowledge is also at risk from the growing use of brick and cement and of imported building technologies, which has prompted documentation projects among Lamu's masons and master builders. In Zanzibar, conservation of the historic town is governed by the Stone Town Conservation and Development Act of 1994.\n\n## Regional terms\n\n- *kidara cha meko* (Swahili): thatched cooking shelter.\n- *ua* (Swahili): courtyard.\n- *mtatato*: a room bridging the street, carried on mangrove beams about 4 m (13 ft) above street level.","key_facts":[{"label":"Region","value":"Swahili coast: Kenya, Tanzania, Zanzibar"},{"label":"Walls","value":"Coral blocks or coral rag in lime mortar"},{"label":"Roof","value":"Thick coral and lime on mangrove-pole joists about 30 cm (12 in) apart"},{"label":"Typical room width","value":"About 3 m (10 ft), limited by pole span"},{"label":"UNESCO towns","value":"Lamu Old Town; Stone Town of Zanzibar (2000)"}],"regions":["Africa"],"aliases":["Swahili stone house","coral rag house","Lamu house"],"related":["flat-roof","makuti-thatch","roofing-in-kenya","roofing-in-tanzania","dome","roofing-in-east-africa"],"sources":[{"title":"Vernacular Housing of Lamu (Swahili Housing)","url":"https://www.archnet.org/sites/6076","publisher":"Archnet"},{"title":"Lamu Old Town","url":"https://whc.unesco.org/en/list/1055","publisher":"UNESCO World Heritage Centre"},{"title":"Swahili architecture","url":"https://en.wikipedia.org/wiki/Swahili_architecture","publisher":"Wikipedia"},{"title":"Stone Town","url":"https://en.wikipedia.org/wiki/Stone_Town","publisher":"Wikipedia"},{"title":"Great Mosque of Kilwa","url":"https://en.wikipedia.org/wiki/Great_Mosque_of_Kilwa","publisher":"Wikipedia"},{"title":"Coral stone house construction on the Swahili coast, Lamu, Kenya","url":"https://www.emkp.org/coral-stone-house-construction-on-the-swahili-coast-lamu-kenya/","publisher":"Endangered Material Knowledge Programme"}],"company":null,"country":null},{"slug":"swallowtail-roof","title":"Swallowtail Roof","category":"world-roofing","type":"term","summary":"A swallowtail roof has a main ridge whose ends sweep up and split like a swallow's tail, typical of Hokkien temples and mansions in Fujian and Taiwan.","body":"A swallowtail roof (燕尾脊, Hokkien *ìnn-bé-tsiah*, Mandarin *yanwei ji*) is a tiled roof whose main ridge curves upward toward each end and finishes in a forked point resembling a swallow's tail. It is the signature roofline of Hokkien (Minnan) architecture in southern Fujian and in Taiwan, and also appears in Hokkien communities in South-East Asia.\n\n## Form\n\nThe ridge rises in a continuous curve from the centre and splits at the tip into two points. The degree of upsweep varies from a gentle lift to a dramatic, almost vertical flourish. The ridge can be single or doubled, with a second, shorter ridge stacked above. Swallowtail ridges are usually richly decorated with coloured carvings and figures of dragons, phoenixes, flowers and legends, often in cut-porcelain work.\n\n## Origins and use\n\nThe style is associated with the 16th century, in the Ming dynasty, when Hoklo merchants grew rich through trade with South-East Asia, Taiwan, the Ryukyu Islands and Japan and used ornate roofs to display their wealth. It is rarely seen in the architecture of other Han Chinese groups. Swallowtails appear mainly on major temples, mansions and ancestral halls rather than ordinary houses. Some sources link the right to a swallowtail ridge with families of official rank, but the association is not well documented.\n\n## Cut-porcelain decoration\n\nThe ridges are often covered in cut-porcelain work (剪瓷雕, *tsián-huî-tiau*): craftsmen cut or grind small coloured porcelain pieces, such as bowls, and press them into mortar sculptures on ridges, eaves and gables. Taiwan has developed a newer style that combines cut porcelain with glazed cochin ware.\n\n## Construction\n\nLike other southern Chinese roofs, a swallowtail roof is laid with clay tiles on a timber frame, with the decorated ridge built up on top of the tiled slopes.\n\n## Examples\n\nNotable examples include temples such as Beipu Citian Temple in Hsinchu County and Fengtian Temple in Chiayi in Taiwan, and Hokkien temples and ancestral halls across southern Fujian.","key_facts":[{"label":"Local name","value":"Yanwei ji / ìnn-bé-tsiah (燕尾脊)"},{"label":"Tradition","value":"Hokkien (Minnan), Fujian and Taiwan"},{"label":"Origin","value":"16th century, Ming dynasty"},{"label":"Typical buildings","value":"Temples, mansions, ancestral halls"},{"label":"Decoration","value":"Cut-porcelain mosaic"}],"regions":["East Asia","Southeast Asia"],"aliases":["swallowtail ridge","yanwei ji","swallow-tail roof","Hokkien swallowtail"],"related":["roofing-in-taiwan","roofing-in-china","chiwen","clay-roof-tile","roof-ridge","fujian-tulou-roofs"],"company":null,"sources":[{"title":"Hokkien architecture","url":"https://en.wikipedia.org/wiki/Hokkien_architecture","publisher":"Wikipedia"},{"title":"Architecture of Taiwan","url":"https://en.wikipedia.org/wiki/Architecture_of_Taiwan","publisher":"Wikipedia"},{"title":"Chinese architecture","url":"https://en.wikipedia.org/wiki/Chinese_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"sydney-opera-house-roof","title":"Sydney Opera House Roof","category":"history","type":"place","summary":"The shell roofs of the Sydney Opera House, built of precast concrete ribs and panels and clad in 1,056,006 Swedish-made ceramic tiles.","body":"The **Sydney Opera House** in Sydney, Australia, is famous above all for its roof: groups of nested white \"shells\" or \"sails\" covering two main performance halls and a restaurant. Designed by Danish architect **Jørn Utzon**, who won an international competition in **1957**, it opened on **20 October 1973** and was inscribed on the UNESCO World Heritage List in 2007.\n\n## The geometry problem\n\nUtzon's competition design showed curved shells whose geometry still had to be worked out before they could be built. The structural engineers were **Ove Arup & Partners**. In mid-1961 the team adopted the **spherical solution**: every shell surface would be cut from the same sphere, with a radius of 75.2 m (247 ft). Because all the curves were the same, the shells could be made from repeated, prefabricated parts. Who first proposed the idea is disputed.\n\n## Structure\n\nStrictly speaking, the roofs are not thin shells. They are made of **precast concrete ribs** supporting precast concrete panels. The builders, Hornibrook, made about 2,400 ribs and 4,000 roof panels on site, and the roof comprises 2,194 precast sections weighing up to 15 tonnes each. The highest point is about 67 m (220 ft) above sea level.\n\n## The tiles\n\nThe shells are clad in **1,056,006 tiles** made by the Swedish firm **Höganäs AB**, which normally made stoneware tiles for the paper-mill industry. The \"Sydney tile\", 120 mm (4.7 in) square and made of clay with a small proportion of crushed stone, took three years to develop. Tiles come in two finishes, glossy white and matte cream, laid in a subtle chevron pattern.\n\n## Construction stages\n\n- Stage I (1957-1959): planning; site work began in March 1959.\n- Stage II (1959-1963): podium.\n- Stage III (1963-1967): outer shells.\n- Stage IV (1967-1973): interiors.\n\nUtzon left the project on 28 February 1966 after disputes with the New South Wales government and never returned to Australia. The final cost was about A$102 million.\n\n## Significance\n\nThe roof made the building one of the world's most recognisable structures and a landmark in the use of prefabrication to build a complex curved roof.","key_facts":[{"label":"Architect","value":"Jørn Utzon (competition won 1957)"},{"label":"Opened","value":"20 October 1973"},{"label":"Tiles","value":"1,056,006, by Höganäs AB, Sweden"},{"label":"Shell geometry","value":"Sphere of 75.2 m (247 ft) radius"},{"label":"Highest point","value":"About 67 m (220 ft) above sea level"},{"label":"World Heritage inscription","value":"2007"}],"regions":["Oceania"],"aliases":["Sydney Opera House sails","Sydney Opera House shells"],"related":["jorn-utzon","munich-olympic-stadium-roof","clay-roof-tile"],"company":null,"sources":[{"title":"Sydney Opera House","url":"https://en.wikipedia.org/wiki/Sydney_Opera_House","publisher":"Wikipedia"},{"title":"Sydney Opera House","url":"https://whc.unesco.org/en/list/166","publisher":"UNESCO World Heritage Centre"},{"title":"Jørn Utzon","url":"https://en.wikipedia.org/wiki/J%C3%B8rn_Utzon","publisher":"Wikipedia"}],"country":null},{"slug":"synthetic-shake","title":"Synthetic Shake","type":"term","summary":"A polymer or rubber roofing product moulded to imitate split cedar shakes, with lower maintenance and fire risk than wood.","body":"A synthetic shake is a manufactured roofing unit moulded to reproduce the look of split wood shakes. Most are made from the same families of materials as synthetic slate: engineered plastics such as polypropylene or polyethylene, or rubber compounds, combined with mineral fillers, pigments and UV stabilisers.\n\n## Why they are used\n\n- **No rot or insect attack**: plastic and rubber shakes do not decay, split along the grain or host fungi the way cedar can. Rubber shakes made largely from recycled tyres are described as resistant to rot, curling and cracking and as non-absorbent.\n- **Fire**: wood shakes are combustible and restricted in some fire-prone areas; fire ratings of synthetic shakes vary by product and assembly.\n- **Hail**: many products carry UL 2218 Class 4 impact ratings.\n- **Weight**: similar to synthetic slate, roughly 200-350 lb per square (10-17 kg/m²).\n- **Uniform supply**: colours and sizes are consistent, while natural cedar quality varies.\n\n## Limitations\n\n- Synthetic shakes lack the natural variation and silver-grey weathering of real cedar, though many are made in blended colours to imitate it.\n- Thermal expansion is greater than wood, so manufacturers' spacing rules must be followed.\n- Long-term performance of many products is still being established; fading and heat distortion are known concerns for some plastics.\n\n## Installation\n\nSynthetic shakes are typically nailed to a solid deck with corrosion-resistant nails. Requirements for underlayment and interlay differ from those for real shakes and vary between manufacturers.\n\n## Comparison with wood\n\nReal cedar shakes are split along the grain and weather naturally to silver-grey, while synthetic shakes keep a more constant colour. Choosing between them usually comes down to local fire rules, hail exposure, maintenance expectations and appearance.\n","key_facts":[{"label":"Typical materials","value":"Polypropylene, polyethylene, recycled rubber"},{"label":"Advantages","value":"No rot; often Class 4 hail rating"},{"label":"Weight","value":"About 200-350 lb per square (10-17 kg/m²)"}],"regions":["North America"],"aliases":["composite shake","faux shake","polymer shake","plastic shake"],"related":["wood-shake","synthetic-slate","rubber-shingle","impact-resistant-shingle"],"sources":[{"title":"Natural Slate & Synthetic Tile Roofing: Installation Fundamentals, Headlap & Fastening","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/metal-tile-slate-steep-slope-systems/slate-synthetic-tile-roofing","publisher":"Open Exam Prep"},{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"synthetic-slate","title":"Synthetic Slate","type":"term","summary":"A roofing tile moulded from polymers such as polypropylene, polyethylene or rubber with mineral fillers, made to look like natural slate.","body":"Synthetic slate is a manufactured roofing product moulded or extruded to imitate natural slate. Most products are made from engineered plastics such as polypropylene, polyethylene or TPO, or from EPDM and recycled rubber, combined with mineral fillers, colour pigments and ultraviolet stabilisers. They are also marketed as composite or polymer slate.\n\n## Properties\n\n- **Weight**: about 200-350 lb per square (roughly 10-17 kg/m²), compared with about 700-900 lb per square for standard natural slate. Most can be installed on ordinary framing without reinforcement.\n- **Impact resistance**: many products carry UL 2218 Class 4 ratings for hail.\n- **Wind**: products are tested to standards such as ASTM D3161; Class F is quoted for some.\n- **Fire**: ratings vary by product and assembly, so the listed assembly should be checked.\n- **Appearance**: products vary from single-colour units to blended, textured moulded surfaces. Synthetic slates are lighter and more flexible than stone, and do not have the natural cleft surface.\n\n## Installation\n\nSynthetic slates are usually nailed to a solid deck, for example 7/16 in (11 mm) OSB or 1/2 in (12.7 mm) plywood, with corrosion-resistant ring-shank nails, often from a pneumatic coil nailer. Because plastics expand and contract more with temperature than stone, manufacturers specify side gaps between units, and these must be followed. Many products can be cut with a utility knife or saw rather than a slate cutter.\n\n## Durability\n\nManufacturers offer warranties that are often long, but real-world service lives are still being established for many products. Concerns include colour fading, warping or curling in high heat, and brittleness with age as stabilisers are used up.\n\n## Use in conservation\n\nHeritage bodies generally do not accept synthetic slates as replacements on historic buildings, because they do not match the colour, texture, weathering and thickness of natural stone.\n","key_facts":[{"label":"Typical materials","value":"Polypropylene, polyethylene, TPO, EPDM/rubber, mineral fillers"},{"label":"Weight","value":"About 200-350 lb per square (10-17 kg/m²)"},{"label":"Typical impact rating","value":"UL 2218 Class 4"}],"regions":["North America","Global"],"aliases":["composite slate","polymer slate","plastic slate","faux slate"],"related":["natural-slate","synthetic-shake","rubber-shingle","fibre-cement-slate","designer-shingle","impact-resistant-shingle"],"sources":[{"title":"Natural Slate & Synthetic Tile Roofing: Installation Fundamentals, Headlap & Fastening","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/metal-tile-slate-steep-slope-systems/slate-synthetic-tile-roofing","publisher":"Open Exam Prep"},{"title":"Asphalt Shingle Types (3-Tab vs. Laminated Architectural), ASTM Classifications & Thermal Behavior","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-types-astm-thermal","publisher":"Open Exam Prep"}],"category":"materials","company":null,"country":null},{"slug":"t-lock-shingle","title":"T-Lock Shingle","type":"term","summary":"An asphalt shingle with a T-shaped profile that hooks into neighbouring shingles instead of relying on a sealant strip; production ended around 2006.","body":"A T-lock shingle is a type of interlocking asphalt shingle shaped roughly like a letter T. Instead of being held down by a factory-applied adhesive strip, each shingle hooks under the edges of its neighbours, and the interlocking pattern, together with the nails, resists wind lift.\n\n## Appearance\n\nA T-lock roof has a distinctive woven or basket-weave look, with each shingle's narrow lower tab locked between the shingles on either side. They were often used to re-roof directly over an existing layer of shingles because the interlocking pattern bridged irregularities.\n\n## History\n\nInterlocking shingles were developed in the mid-20th century, when wind resistance of strip shingles was a concern and before self-sealing adhesive strips became reliable. Self-sealing strips came into general use in the 1950s, and laminated shingles later offered higher wind ratings. According to the US home-inspection association InterNACHI, manufacture of T-lock shingles ended around 2006, although many roofs covered with them remain in service.\n\n## Repair issues\n\nBecause T-lock shingles are no longer made, damaged roofs cannot be patched with matching material. Insurers and adjusters sometimes treat a damaged T-lock roof as unrepairable for that reason, and replacement with a different shingle type is usually required. The interlocking design also makes individual shingles difficult to remove without damaging neighbouring pieces.\n\n## Related forms\n\nOther interlocking asphalt designs included \"Dutch lap\" and hexagonal shingles. All have largely disappeared from the market in favour of self-sealing strip and laminated shingles.\n","key_facts":[{"label":"Fixing principle","value":"Interlocking shape plus nails; no adhesive strip"},{"label":"Production ended","value":"Around 2006"}],"regions":["North America"],"aliases":["interlocking shingle","T-lock","lock-down shingle"],"related":["asphalt-shingle","three-tab-shingle","architectural-shingle"],"sources":[{"title":"Mastering Roof Inspections: Asphalt Composition Shingles, Part 6","url":"https://nachi.org/asphalt-comp-shingles-part6-60.htm","publisher":"InterNACHI"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"tamko","title":"TAMKO Building Products","category":"manufacturers","type":"company","summary":"TAMKO is a family-led US roofing manufacturer founded in Joplin, Missouri in 1944, known for asphalt shingles, underlayments and waterproofing.","body":"TAMKO Building Products is a privately owned roofing manufacturer based in Joplin, Missouri. It was founded on 5 September 1944 by E.L. Craig and Mary Ethel Craig, and is led by the third generation of the founding family.\n\n## Name and origins\n\nThe name TAMKO is an acronym of five US states, Texas, Arkansas, Missouri, Kansas and Oklahoma, which the founders expected to form their sales territory. Mary Ethel Craig chose the name. The business started in a former streetcar barn in south-west Missouri; E.L. Craig was 69 years old when he launched it.\n\n## Development\n\nFrom its regional start, the company grew to more than 20 facilities across the United States and now sells in all 50 states. In 1981 J.P. Humphreys introduced continuous-improvement management practices based on the ideas of W. Edwards Deming, which the company credits with driving later vertical integration and product development. David Craig Humphreys has served as president and chief executive since 1994. The company marked its 75th anniversary in 2019.\n\n## Products\n\nTAMKO's main products are residential roofing shingles. These include laminated and three-tab asphalt shingles, impact-resistant lines aimed at hail-prone regions, and steel shingles. It also makes roofing underlayments and accessories, waterproofing products, and roof cements and coatings. Lines sold under names such as Heritage, Titan XT and StormFighter are marketed mainly to the US residential re-roofing market.\n\n## Ownership\n\nThe company describes itself as privately owned and operated, with family members in the roles of chairman and chief executive. Its range targets both new construction and re-roofing.","key_facts":[{"label":"Founded","value":"5 September 1944"},{"label":"Founders","value":"E.L. and Mary Ethel Craig"},{"label":"Headquarters","value":"Joplin, Missouri, US"},{"label":"Facilities","value":"20+ in the US"}],"regions":["North America"],"aliases":["TAMKO","TAMKO Roofing"],"related":["asphalt-shingle","impact-resistance-rating","roofing-underlayment"],"company":{"founded":"1944","headquarters":"Joplin, Missouri, United States","website":"https://www.tamko.com","known_for":["Asphalt shingles","Heritage shingle line","Roofing underlayment","Waterproofing"]},"sources":[{"title":"TAMKO celebrates 75 years in roofing industry this week","url":"https://www.tamko.com/about/media-center/news-releases/post/2019/09/05/TAMKO-celebrates-75-years-in-roofing-industry-this-week","publisher":"TAMKO"},{"title":"TAMKO celebrates 75 years in the roofing industry","url":"https://roofingcontractor.com/articles/93916-tamko-celebrates-75-years-in-the-roofing-industry","publisher":"Roofing Contractor"}],"country":null},{"slug":"tandrotrano","title":"Tandrotrano","category":"world-roofing","type":"term","summary":"Malagasy 'roof horns': gable timbers crossed above the ridge of highland houses, whose length once signalled the rank of a noble family.","body":"*Tandrotrano* (literally \"house horns\") are the crossed timbers that project above each end of the ridge on traditional houses of the Malagasy highlands. They form where the roof beams cross at each end of the gable peak.\n\n## Meaning\n\nIn the Merina kingdom the length of the roof horns indicated the rank of the noble family who owned the house: the longer the horns, the higher the status. On the royal house of Andrianampoinimerina at Ambohimanga the horns were silver-plated, and a silver eagle was once mounted at the centre of the ridge.\n\n## Change in the 19th century\n\nLouis Gros, who designed the Tranovola palace in the Rova of Antananarivo for Radama I in 1819, and Jean Laborde, who built the Queen's Palace there in 1839-1841, turned the horns into carved posts at each gable end of their wooden buildings. On the brick houses that spread under Ranavalona II (1868-1883), tandrotrano were shortened. After building restrictions were abolished in 1869 the horns were gradually replaced by a simple finial, which no longer signals class.\n\n## Where they appear\n\nTandrotrano belong to the aristocratic timber houses of Imerina, which were built flush to the ground rather than on stilts, with a steep peaked gable roof often carried on a central pillar (*andry*). The surviving house of Andrianampoinimerina at Ambohimanga, with its rosewood walls, 10 m (33 ft) central pillar and silver-plated horns, is a well-known example (see Ambohimanga royal houses).\n\n## Related practice\n\nIn the south-east, actual zebu horns were traditionally fixed to the gable peak, a different way of marking the roof's apex.","key_facts":[{"label":"Region","value":"Central highlands of Madagascar"},{"label":"Meaning","value":"Length signalled noble rank"},{"label":"Decline","value":"After restrictions were abolished in 1869"}],"regions":["Africa"],"aliases":["roof horns","tandro-trano"],"related":["roofing-in-madagascar","ambohimanga-royal-houses","ravinala-thatch"],"company":null,"sources":[{"title":"Architecture of Madagascar","url":"https://en.wikipedia.org/wiki/Architecture_of_Madagascar","publisher":"Wikipedia"},{"title":"Ambohimanga","url":"https://en.wikipedia.org/wiki/Ambohimanga","publisher":"Wikipedia"}],"country":null},{"slug":"tapered-insulation","title":"Tapered Insulation","category":"low-slope-systems","type":"term","summary":"Roof insulation boards cut with a built-in slope and laid in a planned sequence to create falls toward drains on a level deck.","body":"Tapered insulation is rigid insulation manufactured in boards of varying thickness so that, when assembled to a layout drawing, the top surface slopes toward drains, gutters or scuppers. It lets designers create falls on a level structural deck without sloping the structure or adding heavy screeds.\n\n## Materials\n\nTapered boards are made from polyiso, EPS, XPS, mineral wool, cellular glass and other insulants. Typical systems use a sequence of lettered boards, each increasing in thickness, with flat \"fill\" boards underneath where more height is needed.\n\n## Common slopes\n\n- North America: 1/8 in per ft (about 1%) and 1/4 in per ft (about 2%) are standard tapers; the IBC requires 1/4:12 for most membranes on new roofs, and NRCA notes that a truly flat deck may drain adequately with a 1/8:12 taper.\n- UK and Europe: schemes are designed to achieve at least a 1:80 finished fall, using design falls from 1:60 to 1:40 under BS 6229:2025.\n\n## Design elements\n\n- **Main falls** run toward lines of drains or gutters.\n- **Crickets and saddles** divert water between drains and around curbs, often at twice the main slope.\n- **Sumps** of thinner insulation around outlets bring water into the drain.\n- **Hip and valley layouts** create four-way slopes to point drains.\n\n## Thermal considerations\n\nBecause thickness varies, the thermal value varies too. North American energy codes allow an average R-value with minimum thickness limits; UK guidance requires that no point, including the thinnest areas at outlets and gutters, exceeds a U-value of 0.35 W/m2K on heated buildings.\n\n## Advantages\n\nTapered insulation is lightweight, quick to install, adjustable to existing decks in refurbishment, and works with single-ply, bituminous and liquid systems.","key_facts":[{"label":"Common tapers (N. America)","value":"1/8 and 1/4 in per ft (about 1% and 2%)"},{"label":"UK target","value":"At least 1:80 finished fall"},{"label":"Materials","value":"Polyiso, EPS, XPS, mineral wool, cellular glass"},{"label":"UK minimum U-value at any point","value":"0.35 W/m2K"}],"regions":["Global"],"aliases":["tapered roof insulation","tapered scheme","tapered system"],"related":["positive-drainage","cricket-roofing","roof-drain","roof-insulation","ponding-water"],"company":null,"sources":[{"title":"Falls and drainage","url":"https://www.bauder.co.uk/roof-systems/refurbishment-projects/solving-the-challenge/improving-drainage-falls","publisher":"Bauder"},{"title":"Tech Today: roof slope and positive drainage (M. Graham, March 2005)","url":"https://professionalroofing.net/articles/article/615","publisher":"Professional Roofing / NRCA"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"},{"title":"How to avoid ponding on flat roofs","url":"https://www.specifiedby.com/soprema-uk/news/how-to-avoid-ponding-on-flat-roofs","publisher":"Soprema UK via SpecifiedBy"},{"title":"Rules for long-lasting BUR systems (H. H. Pierce, Interface, Oct 2006)","url":"https://iibec.org/wp-content/uploads/2006-10-Pierce.pdf","publisher":"IIBEC"}],"country":null},{"slug":"tapersawn-shake","title":"Tapersawn Shake","type":"term","summary":"A thick wooden shake sawn on both faces to a taper, combining the bulk of a shake with the smoother look of a sawn shingle.","body":"A tapersawn shake is a wooden roofing unit that is sawn to a taper on both faces. It is made from a split block, but unlike a handsplit shake it has no rough split face; instead it has the clean surfaces of a sawn shingle while keeping the thickness of a shake. The result is a roof with crisp, deep shadow lines and a more tailored look than a handsplit roof.\n\n## Manufacture\n\nMills first split a block of cedar along the grain to obtain a blank that follows the wood fibres. The blank is then sawn on each face to create the taper, from a thick butt to a thin tip. In the Cedar Shake & Shingle Bureau's system, tapersawn shakes are certified under the Certi-Sawn label.\n\n## Compared with other wood units\n\n- **Versus sawn shingles**: tapersawn shakes are thicker at the butt, so they have more material to weather away and a bolder appearance.\n- **Versus handsplit shakes**: the surfaces are smooth rather than rough, so courses fit more tightly and the roof looks more regular. Handsplit shakes have a more rustic texture.\n\n## Species\n\nWestern red cedar is the main species for tapersawn shakes in North America; Alaskan yellow cedar is also used, particularly where a more uniform colour is wanted.\n\n## Installation\n\nInstallation follows the general rules for shakes: corrosion-resistant fasteners, appropriate spacing between units to allow for swelling, and attention to ventilation so the wood can dry. Manufacturers and the Bureau publish exposure tables that link the shake length and roof pitch to the maximum weather exposure allowed.\n","key_facts":[{"label":"Faces","value":"Sawn on both faces"},{"label":"Certification label","value":"Certi-Sawn (CSSB)"},{"label":"Main species","value":"Western red cedar"}],"regions":["North America"],"aliases":["taper-sawn shake","tapersawn","sawn shake"],"related":["wood-shake","handsplit-shake","wood-shingle","cedar-shake-and-shingle-bureau"],"sources":[{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Cedar Shake & Shingle Bureau","url":"https://www.cedarbureau.org/","publisher":"Cedar Shake & Shingle Bureau"}],"category":"materials","company":null,"country":null},{"slug":"taq-kasra","title":"Taq Kasra","category":"history","type":"place","regions":["Middle East"],"company":null,"summary":"The great Sasanian brick vault at Ctesiphon, Iraq, about 37 m high and 26 m wide, built without centring.","aliases":["Arch of Ctesiphon","Iwan of Khosrow","Taq-i Kisra","Ctesiphon arch"],"body":"Taq Kasra, the surviving great hall of the Sasanian palace at Ctesiphon south of Baghdad, is one of the largest brick vaults ever built. Its barrel vault forms the roof of an open-fronted hall (*iwan*) and is a landmark in the history of masonry roofing.\n\n## Date\n\nThe construction date is uncertain, somewhere between the 3rd and 6th centuries AD, with sources crediting Shapur I, Shapur II, Khosrow I or Khosrow II.\n\n## Dimensions\n\n- Height: about 37 m (121 ft)\n- Span: about 26 m (85 ft)\n- Length: about 50 m (160 ft)\n- Thickness: about 1 m (3 ft) at the crown, with supporting walls up to 7 m (23 ft) thick at the base\n\n## Building a vault without centring\n\nLarge Roman vaults were usually built over temporary timber formwork (centring). Timber was scarce in Mesopotamia, and the Taq Kasra was instead built without it. Bricks were laid leaning at roughly 18 degrees from vertical, so that the rear wall partly supported them during building, and a quick-setting mortar let each new brick be held by those already laid. The method allowed builders to roof a wide space in brick alone.\n\n## Damage and restoration\n\nA serious flood in 1888 demolished the greater part of the building. The fallen northern wing was partly rebuilt in the 1980s, but work stopped after the 1991 Gulf War. Restoration with the University of Chicago's Diyala Project took place in 2004-2008, and a Czech firm completed further work in 2017. On 7 March 2019 part of the structure collapsed.\n\n## Significance for roofing\n\nThe Taq Kasra shows how far masonry vaulting could go in a region without long timbers. Vaulted iwans and domes remained central to roofing large spaces in later Persian architecture (see roofing-in-iran and middle-eastern-domes).","key_facts":[{"label":"Location","value":"Ctesiphon, Iraq"},{"label":"Period","value":"Sasanian, 3rd-6th century AD"},{"label":"Vault height / span","value":"C. 37 m (121 ft) / 26 m (85 ft)"},{"label":"Material","value":"Unreinforced brick, fast-setting mortar"},{"label":"Partial collapse","value":"7 March 2019"}],"related":["roofing-in-iraq","roofing-in-iran","barrel-vault-roof","middle-eastern-domes","nubian-vault"],"sources":[{"title":"Taq Kasra","url":"https://en.wikipedia.org/wiki/Taq_Kasra","publisher":"Wikipedia"},{"title":"Iranian architecture","url":"https://en.wikipedia.org/wiki/Iranian_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"tas-100","title":"TAS 100","summary":"TAS 100 is a Florida Building Code test protocol that checks whether discontinuous roof systems keep out wind-driven rain at speeds up to 110 mph.","body":"TAS 100, *Test Procedure for Wind and Wind Driven Rain Resistance of Discontinuous Roof Systems*, is one of the Testing Application Standards (TAS) published with the Florida Building Code. The TAS documents originated in the South Florida Building Code used by Miami-Dade and Broward counties and are closely tied to the High-Velocity Hurricane Zone (HVHZ) provisions.\n\n## Purpose\n\n\"Discontinuous\" roof systems are those made of individual units or panels that overlap rather than forming one continuous membrane, such as tile, metal panels, metal shingles, and composite shingles. TAS 100 checks whether such a system, together with its underlayment, prevents wind-driven rain from reaching the roof deck. It is also used for roof accessories such as ridge vents and attic fans.\n\n## How the test works\n\nA test deck is built as it would be in the field, including eave, valley and rake details, with fasteners spaced to corner and perimeter requirements rather than the lighter field spacing. A spray rack wets the deck at 8.8 in (224 mm) per hour while a wind generator blows across it in stages at 35, 70, 90 and 110 mph (56, 113, 145 and 177 km/h), with 10-minute rests between stages. To pass, no water may penetrate through the deck sheathing.\n\n## Where it is used\n\nManufacturers use TAS 100 results to support Miami-Dade Notices of Acceptance and Florida Product Approvals for roof coverings and accessories. A TAS 100 result is often presented on vent and ridge product literature as evidence of wind-driven rain resistance.\n\n## Review and modernization\n\nThe Florida Building Commission's Hurricane Research Advisory Committee has studied whether water penetration tests such as TAS 100 need updating, partly because of lessons from recent hurricanes about water entry at vents and roof edges.\n\n## Related standards\n\nTAS 100 is one of a family of Testing Application Standards used for HVHZ product approval. Others, such as TAS 114, appear alongside it in Miami-Dade approvals for underlayments and roof components.","key_facts":[{"label":"Issued with","value":"Florida Building Code (Testing Application Standards)"},{"label":"Water rate","value":"8.8 in/h (224 mm/h)"},{"label":"Wind stages","value":"35, 70, 90 and 110 mph (56–177 km/h)"},{"label":"Pass criterion","value":"No water through the deck sheathing"},{"label":"Applies to","value":"Tile, metal panels, shingles, roof accessories"}],"regions":["North America"],"aliases":["TAS-100","TAS 100-95","wind-driven rain test"],"related":["miami-dade-noa","florida-product-approval","roofing-underlayment","ridge-vent"],"sources":[{"title":"TAS 100: Standard Test Method for Wind and Wind Driven Rain Resistance of Discontinuous Roof Systems","url":"https://www.intertek.com/building/standards/tas-100/","publisher":"Intertek"},{"title":"Testing Application Standard TAS No. 100-95","url":"https://basc.pnnl.gov/library/testing-application-standard-tas-no-100-95-test-procedure-wind-and-wind-driven-rain","publisher":"Building America Solution Center (PNNL)"},{"title":"Final Report: Assessing the Need to Modernize Water Penetration Resistance Test Procedures","url":"https://www.floridabuilding.org/fbc/Commission/FBC_0623/HRAC/Final_Report-Assessing_the_Need_to_Modernize_Water_Penetration_Resistance_Test_Procedures.pdf","publisher":"Florida Building Commission"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"tata-steel-colors","title":"Tata Steel Colors (formerly Tata BlueScope Steel)","category":"manufacturers","type":"company","summary":"Tata Steel Colors, formerly Tata BlueScope Steel, is an Indian coated-steel and roofing maker founded in 2005 as a Tata Steel-BlueScope joint venture.","body":"Tata Steel Colors Private Limited, formerly Tata BlueScope Steel, is an Indian producer of metallic-coated and colour-coated steel and of roof and wall cladding, headquartered in Pune. It was established in 2005 as a 50:50 joint venture between Tata Steel and Australia's BlueScope Steel. Tata Steel signed an agreement on 12 November 2025 to buy BlueScope's 50 percent stake for about INR 1,100 crore and completed the purchase on 31 December 2025, making the company a wholly owned Tata Steel subsidiary.\n\n## Operations\n\nThe company's plants are at Jamshedpur (Jharkhand), Sriperumbudur (Tamil Nadu), Bhiwadi (Rajasthan) and Pune (Maharashtra). The Jamshedpur coated steel plant was inaugurated in March 2012. Annual capacity is about 250,000 tonnes of metallic coating and 150,000 tonnes of colour coating.\n\n## Businesses\n\nUnder the joint venture the company operated three lines of business:\n\n- **Coated steel**: aluminium-zinc coated and pre-painted steel coil for roofing and cladding manufacturers.\n- **Roof and wall cladding products**: roll-formed profiled sheets and accessories for industrial, commercial and residential buildings.\n- **Pre-engineered building solutions**: steel-framed buildings supplied with their roof and wall cladding.\n\n## Context\n\nIn India, coated steel roofing sheets are used on factories, warehouses and other buildings, alongside fibre-cement corrugated sheets and reinforced concrete slabs. The joint venture combined BlueScope's metallic coating and painting technology with Tata Steel's steelmaking base.\n\n## Coated steel\n\nMetallic coatings such as aluminium-zinc protect the steel base from corrosion, while a paint system on top adds colour and further protection. The combination is the standard material for roll-formed roofing and wall sheets.","key_facts":[{"label":"Founded","value":"2005 (joint venture)"},{"label":"Headquarters","value":"Pune, India"},{"label":"Owner","value":"Tata Steel (100% from 31 December 2025)"},{"label":"Plants","value":"Jamshedpur, Sriperumbudur, Bhiwadi, Pune"}],"regions":["South Asia"],"aliases":["Tata BlueScope Steel","TBSL"],"related":["bluescope","metal-roofing","everest-industries"],"company":{"founded":"2005","headquarters":"Pune, India","parent":"Tata Steel","known_for":["Coated steel coil","Roof and wall cladding","Pre-engineered buildings"]},"sources":[{"title":"Tata BlueScope Steel","url":"https://en.wikipedia.org/wiki/Tata_BlueScope_Steel","publisher":"Wikipedia"},{"title":"BlueScope","url":"https://en.wikipedia.org/wiki/BlueScope","publisher":"Wikipedia"}],"country":null},{"slug":"tear-off-vs-overlay","title":"Tear-Off vs Overlay","category":"installation","type":"article","summary":"Tear-off removes the existing roof covering down to the deck; an overlay (recover) installs a new covering over the old one where codes permit.","body":"When a roof is replaced, the old covering can either be removed completely (a **tear-off**) or left in place with the new roof installed over it (an **overlay**, also called a **recover** or \"layover\"). Codes in many places limit when an overlay is allowed, because extra layers add weight, hide deck damage and can make the new roof less flat and less durable.\n\n## Code limits in the United States\n\nThe International Residential Code (IRC), adopted with local amendments across much of the US, treats overlays in section R908 (Reroofing). In the 2018 edition, section R908.3.1.1 does not permit a recover, so tear-off is required, when:\n\n- the existing roof or roof covering is water-soaked or has deteriorated so that it is not an adequate base;\n- the existing covering is slate, clay, cement or asbestos-cement tile; or\n- the roof already has two or more applications of any type of roof covering.\n\nIn practice this usually means one existing layer of asphalt shingles may be covered once, giving two layers in total. Local rules can be stricter. The City of Norman, Oklahoma, for example, does not allow a recover over any existing asphalt shingle layer, while Bloomington, Minnesota, applying a code based on the 2018 IRC, allows a total of two layers before tear-off is needed.\n\n## Overlay technique\n\nWhere an overlay is permitted, Canadian guidance describes a \"butt-up\" or nesting method for strip shingles: old ridge caps are removed, edges are trimmed and fitted with new metal edging, and each new shingle is pushed up against the butts of the old course so the new roof lies flat. Nails must be long enough to pass through both layers into the deck.\n\n## Pros and cons\n\n| | Tear-off | Overlay |\n|---|---|---|\n| Deck inspection | Full | Not possible |\n| Flashing renewal | Straightforward | Often compromised |\n| Weight | Lower | Higher |\n| Cost and waste | Higher | Lower |\n\nMany manufacturers' warranties and high-wind programmes favour or require a tear-off. A tear-off also allows the deck to be re-nailed and sealed. Overlays are mainly used for asphalt shingles and for some low-slope and metal recover systems designed for that purpose.","key_facts":[{"label":"US code section","value":"IRC R908 (Reroofing)"},{"label":"Common US limit","value":"Tear-off required if two or more coverings exist"},{"label":"Coverings that cannot be overlaid (2018 IRC)","value":"Slate, clay, cement, asbestos-cement tile"}],"regions":["North America","Global"],"aliases":["recover","re-cover","layover","roof overlay","shingle-over"],"related":["roof-replacement-process","roof-deck-inspection-and-replacement","roofing-permits-and-inspections","asphalt-shingle"],"company":null,"sources":[{"title":"Can you put new shingles over old shingles under IRC 2021?","url":"https://www.jaspector.com/codes/irc-2021/ch09-roof-assemblies/reroofing-code-existing-shingles/","publisher":"Jaspector"},{"title":"Roofing FAQs","url":"https://www.normanok.gov/sites/default/files/documents/2023-07/roofing_faqs.pdf","publisher":"City of Norman, Oklahoma"},{"title":"Reroofing","url":"https://www.bloomingtonmn.gov/sites/default/files/2023-08/Reroofing.pdf","publisher":"City of Bloomington, Minnesota"},{"title":"Canadian Roofing Reference Manual: 9.1.3 Overlaying an Existing Roof","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-1-asphalt-shingles/9-1-3-overlaying-an-existing-roof/","publisher":"Canadian Roofing Contractors Association"},{"title":"Reroofing (2018 IRC R908)","url":"https://gillettewy.gov/files/assets/public/v/1/development-services/documents/reroofing-2018.pdf","publisher":"City of Gillette, Wyoming"}],"country":null},{"slug":"tegola-canadese","title":"Tegola Canadese","category":"manufacturers","type":"company","summary":"Tegola Canadese is an Italian maker of asphalt (bitumen) shingles and roofing components based in Vittorio Veneto, part of the IWIS Group.","body":"Tegola Canadese S.r.l. is an Italian manufacturer of asphalt shingles, waterproofing membranes and roof components, based in Vittorio Veneto in the province of Treviso, north-eastern Italy. It is part of the IWIS Group (IWIS Holding). The company name translates as \"Canadian tile\", the common Italian term for asphalt shingles, reflecting the product's North American origins.\n\n## Products\n\n- **Asphalt shingles**: fibreglass-reinforced bitumen shingles with mineral granule surfaces, in a variety of shapes and colours, including the UNICA line.\n- **Safety membranes**: waterproofing underlays and membranes for use beneath shingles and other coverings.\n- **Roof components** to complete shingle roofs.\n\nThe company promotes research carried out with universities and offers long-term limited warranties on its shingles.\n\n## Markets\n\nItaly is Tegola Canadese's home market. Its network of partner websites covers Slovenia and Croatia, the Czech Republic, Poland, Hungary, Romania, Moldova, Ukraine, Brazil, India and Russia.\n\n## Asphalt shingles in Europe\n\nAsphalt shingles are far less common in Europe than in North America, where they cover most houses. In Europe they are used mainly on timber-frame houses, holiday homes, mountain buildings and roofs with curved or complex shapes, where flexible shingles are easier to fit than rigid tiles. They are typically nailed to a continuous timber deck with an underlay, unlike tiles hung on battens, and are covered in Europe by the harmonised product standard EN 544. Shingles are fixed with nails, and in some systems also with self-adhesive strips that bond the overlapping shingles together in the sun's heat to resist wind uplift.","key_facts":[{"label":"Headquarters","value":"Vittorio Veneto, Italy"},{"label":"Group","value":"IWIS Group"},{"label":"Products","value":"Asphalt shingles, safety membranes, roof components"}],"regions":["Europe"],"aliases":["Tegola Canadese S.r.l."],"related":["asphalt-shingle","en-544","roofing-underlayment","onduline","iko"],"company":{"headquarters":"Vittorio Veneto, Italy","website":"https://www.tegolacanadese.com","parent":"IWIS Group","known_for":["Asphalt shingles in Europe","Safety membranes"]},"sources":[{"title":"Tegola Canadese","url":"https://www.tegolacanadese.com/","publisher":"Tegola Canadese"},{"title":"Tegola Canadese (English)","url":"https://www.tegolacanadese.com/en/","publisher":"Tegola Canadese"}],"country":null},{"slug":"tejuela","title":"Tejuela (Chilean Wood Shingle)","category":"materials","type":"term","summary":"Hand-split wooden shingle of southern Chile and adjoining Argentina, used to clad roofs and walls, notably in Chiloé and Aysén.","body":"A *tejuela* is a hand-split wooden shingle used in southern Chile and neighbouring parts of Argentina to cover roofs and exterior walls. The word is a diminutive of *teja* (roof tile). Tejuelas are the characteristic cladding of the wooden churches and houses of the Chiloé archipelago, and are also found across the Aysén region and in Argentine border areas of Río Negro, Chubut, Santa Cruz and Tierra del Fuego. When used on walls, the cladding is often called *tingle* in Aysén.\n\n## Timber\n\nA study of traditional shingle-making in Aysén by Carlos Castillo Levicoy, published in 2015 in *Conserva*, the journal of Chile's National Centre for Conservation and Restoration (CNCR), lists the native timbers used: alerce (*Fitzroya cupressoides*), Guaitecas cypress (*Pilgerodendron uviferum*), mountain cypress (*Austrocedrus chilensis*), mañío, canelo, lingue, lenga and coigüe. Alerce was heavily logged in the colonial period for building and export, and UNESCO notes that the fine hardwoods used on Chiloé's heritage churches have become scarce.\n\n## Making\n\nShingles are split rather than sawn, so that they follow the natural grain of the wood. The CNCR study describes Mapuche-Huilliche workers splitting timber by driving hardwood wedges with a mallet along the grain. The arrival of metal nails replaced older rustic fixings and allowed simpler nailed joints.\n\n## History and decline\n\nThe CNCR study describes shingle-making as one of the most traditional timber trades of southern Chile. It was carried to Aysén by European and Chilean settlers in the 19th and 20th centuries, and the shingled buildings catalogued in the region date from about 1930 to 1995. The author found many of these buildings deteriorating and described the trade as close to extinction.","key_facts":[{"label":"Region","value":"Southern Chile (Chiloé, Aysén) and Argentine Patagonia"},{"label":"Use","value":"Roof and wall cladding"},{"label":"Main timbers","value":"Alerce, Guaitecas cypress, mountain cypress, mañío, coigüe"},{"label":"Method","value":"Hand-split along the grain with wedges and mallet"}],"regions":["Latin America"],"aliases":["tejuelas","Chilote shingle","tejuela de alerce","tingle"],"related":["wood-shingle","churches-of-chiloe","roofing-in-chile","roofing-in-argentina","wood-shingle-installation"],"company":null,"sources":[{"title":"Tejuela artesanal (Conserva 20, 2015)","url":"https://www.cncr.gob.cl/sites/www.cncr.gob.cl/files/2023-01/Tejuela%20Artesanal.pdf","publisher":"Centro Nacional de Conservación y Restauración (Chile)"},{"title":"Churches of Chiloé","url":"https://whc.unesco.org/en/list/971","publisher":"UNESCO World Heritage Centre"},{"title":"Churches of Chiloé","url":"https://en.wikipedia.org/wiki/Churches_of_Chilo%C3%A9","publisher":"Wikipedia"}],"country":null},{"slug":"tensile-membrane-roof","title":"Tensile Membrane Roof","category":"roof-forms","type":"article","summary":"A roof of tensioned fabric or foil, such as PTFE-coated glass fibre, PVC-coated polyester or ETFE, held in curved shapes by masts, cables and edge beams.","body":"A tensile membrane roof is a roof whose covering carries load purely in tension: a thin fabric or plastic film is stretched between supports so that it stays taut under wind, rain and snow. Instead of resting on rafters or a deck, the membrane spans between masts, arches, cables, compression rings or edge beams. Membrane roofs are used for stadiums, airports, canopies, atria and shade structures, where long spans, low weight and daylight are wanted.\n\n## History\n\nTents have always worked on the same principle, with poles and guy ropes pretensioning the cover. The Russian engineer Vladimir Shukhov was among the first to calculate stresses in such structures, designing eight tensile and thin-shell pavilions covering about 27,000 m² (290,000 sq ft) for the 1896 Nizhny Novgorod fair. Frei Otto popularised modern tensile architecture with the West German pavilion at Expo 67 in Montreal and the roof of the 1972 Munich Olympic Stadium. Engineers including Ove Arup, Buro Happold and Horst Berger developed the field from the 1960s. Later landmarks include the terminal of Denver International Airport and the Millennium Dome (now The O2) in London. Until computer analysis matured in the 1990s, designers relied heavily on physical models and soap films to find shapes.\n\n## Shape and prestress\n\nA flat membrane would flap and pond, so tensile roofs are given double curvature. The basic form is the saddle (anticlastic) surface, curving up in one direction and down in the other; conical and radial shapes are also common. Pretension in the fabric and supports keeps the surface stiff. The final shape depends on the cutting pattern, the support geometry and the pretension. Poor drainage is a key risk: water ponding in a hollow can deform the membrane progressively, and snow often does not slide off, so some roofs use heating to clear it.\n\n## Membrane materials\n\n- **PTFE-coated glass fibre:** woven glass cloth coated with PTFE. Inherently non-combustible, largely self-cleaning in rain, and expected to last 30-50 years; the earliest projects outlived their 25-year design life. Heavier grades transmit about 9-12% of daylight and lighter grades about 14-16%. Single-skin weight is about 1.5 kg/m² (0.3 lb/sq ft).\n- **PVC-coated polyester:** the more economical woven alternative, with a typical life of about 15-20 years.\n- **ETFE (ethylene tetrafluoroethylene):** a fluoropolymer foil used as single layers or, more often, as inflated multi-layer cushions. A double-layer cushion weighs about 0.7 kg/m² (0.14 lb/sq ft), a small fraction of 6 mm glass, and transparency can reach about 90%. Cushions need a continuous low-pressure air supply. ETFE clads the biomes of the Eden Project in Cornwall (opened 2001), the Beijing National Aquatics Centre (2008) and the Allianz Arena in Munich.\n\nIn woven fabrics the warp threads are stronger than the weft, which affects how panels are cut and orientated.\n\n## Cables and supports\n\nMembranes are usually edged or reinforced with cables of high-strength steel, stainless steel, polyester or aramid. Steel spiral strand is pre-stretched and load-cycled to remove construction stretch before use. Masts and arches carry the resulting compression into the foundations.\n\n## Maintenance\n\nPTFE membranes are typically cleaned every few years with soft brushes and mild detergent. Tears in ETFE can be patched by welding from outside.","key_facts":[{"label":"Structural action","value":"Pure tension in a doubly curved surface"},{"label":"Main materials","value":"PTFE-glass, PVC-polyester, ETFE"},{"label":"PTFE-glass life","value":"About 30-50 years"},{"label":"PVC-polyester life","value":"About 15-20 years"},{"label":"Landmark","value":"Munich Olympic Stadium roof, 1972 (Frei Otto)"}],"regions":["Global"],"aliases":["tensile structure roof","fabric roof","membrane structure","PTFE roof","ETFE roof","tensile fabric roof"],"related":["polycarbonate-roofing-sheet","single-ply-roofing"],"company":null,"sources":[{"title":"Tensile structure","url":"https://en.wikipedia.org/wiki/Tensile_structure","publisher":"Wikipedia"},{"title":"Using PTFE Glass Cloth","url":"https://www.architen.com/articles/using-ptfe-glass-cloth/","publisher":"Architen Landrell"},{"title":"ETFE","url":"https://www.designingbuildings.co.uk/w/images/6/68/Designing_Buildings_Wiki_ETFE_.pdf","publisher":"Designing Buildings Wiki"}],"country":null},{"slug":"tension-leveling","title":"Tension Leveling","category":"installation","type":"term","summary":"Tension leveling stretches metal coil slightly beyond its yield point to flatten it and release built-in stresses, reducing oil canning in roof panels.","body":"Metal coil leaves the rolling mill with uneven internal stresses. Some parts of the strip may be slightly longer than others, creating conditions known as full centre (a longer middle), wavy edge (longer edges) or camber (sideways bow). When such coil is formed into wide, flat roof panels, the trapped stresses can show up as waviness, known as oil canning.\n\n## How it works\n\nIn tension leveling, the strip is stretched under tension slightly beyond its yield point, so that shorter areas of the strip lengthen to match longer ones. When the tension is released, the strip is flatter and more uniform, with less stored stress.\n\nFor roofing, leveling done after slitting is particularly useful, because cutting a wide master coil into narrower widths can itself redistribute stresses.\n\n## Benefits\n\n- Reduces the tendency to oil canning in flat-pan standing seam and architectural panels.\n- Improves flatness for wall cladding and flashings.\n- Helps roll-forming produce consistent profiles.\n\n## Limits\n\nTension leveling cannot fix waviness caused after forming, for example by out-of-plane decks, over-engaged seams, over-driven fasteners or restrained thermal movement. Industry guidance therefore treats it as one measure among several, alongside thicker gauges, narrower pans, stiffening ribs, low-gloss finishes and good installation practice.\n\n## Specifying it\n\nTension-leveled coil is usually specified for architectural standing seam panels, especially wide flat pans in dark or glossy colours where waviness would be most visible. Even with leveled coil, industry guidance notes that no single measure can ensure flat panels; combined measures give the best results.","key_facts":[{"label":"Purpose","value":"Flatten coil and relieve residual stresses"},{"label":"Defects addressed","value":"Full centre, wavy edge, camber"},{"label":"Main roofing benefit","value":"Less oil canning"}],"regions":["Global"],"aliases":["tension levelling","stretcher leveling","tension-leveled coil"],"related":["oil-canning","standing-seam-metal-roof","sheet-metal-gauge"],"company":null,"sources":[{"title":"Oil Canning (MCA technical sheet)","url":"https://www.mcelroymetal.com/hubfs/assets/OilCanningTechSheetfromMCA.pdf","publisher":"Metal Construction Association"},{"title":"Product Advisory Bulletin PAB05: Oil Canning","url":"https://cdn.dcs.lysaght.com/download/lysaght-product-advisory-bulletin-pab05-oil-canning","publisher":"Lysaght (BlueScope)"}],"country":null},{"slug":"terne-plate","title":"Terne Plate","category":"history","type":"article","summary":"Terne plate is iron or steel sheet coated with a dull lead-tin alloy, historically used for painted roofs; it is no longer produced.","body":"Terne plate (terneplate) was thin iron, and later steel, coated by hot-dipping in an alloy of lead and tin. The coating was typically 10 to 20% tin and the rest lead. The name is usually traced to a French word for dull, describing its matte look compared with bright tinplate, which carried a pure tin coating.\n\n## Use in roofing\n\nBecause the low tin content made it cheaper than tinplate, terne became a common roofing metal in the nineteenth and twentieth centuries, often installed as flat seam or standing seam roofs and as flashings and gutters. Old records frequently describe terne roofs as \"tin\" roofs, and the two are easy to confuse.\n\n## Maintenance\n\nTerne roofs are iron-based and must be painted. Preservation guidance stresses that the underside should be primed before installation and the exposed face kept painted. With paint maintained, terne roofs are reported to last 90 years or more; neglected roofs rust through.\n\n## End of production\n\nLead's toxicity led manufacturers to replace it with a tin-zinc alloy, and traditional terne-coated carbon steel is no longer sold. Repairs and replacements on historic buildings now generally use terne-coated stainless steel (a tin coating over stainless) or copper.\n\n## Conservation notes\n\nWhen an old terne roof is repaired, matching the seam type, pan size and colour of the original helps keep the building's character. Lead-based coatings on surviving sheets require appropriate care during removal or soldering.\n\n## Related materials\n\nTerne plate sat between tinplate and galvanized iron in cost and appearance. Zinc-coated (galvanized) iron, developed in France in 1837, gradually took over many uses because it did not need constant painting, while copper remained the premium choice for important buildings.","key_facts":[{"label":"Coating","value":"Lead-tin alloy, typically 10-20% tin"},{"label":"Base","value":"Iron, later steel"},{"label":"Maintenance","value":"Must be kept painted"},{"label":"Current status","value":"No longer manufactured"}],"regions":["Global"],"aliases":["terneplate","terne","terne metal","roofing terne"],"related":["terne-coated-stainless-steel","tin-roof","flat-seam-roofing","copper-roofing"],"company":null,"sources":[{"title":"Terneplate","url":"https://en.wikipedia.org/wiki/Terneplate","publisher":"Wikipedia"},{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"}],"country":null},{"slug":"terne-coated-stainless-steel","title":"Terne-Coated Stainless Steel (TCS)","category":"materials","type":"article","summary":"Terne-coated stainless steel is stainless sheet with a thin tin coating that weathers to matte grey; it replaced traditional lead-tin terne plate.","body":"Terne-coated stainless steel, often shortened to TCS, is a roofing and flashing metal made by coating stainless steel sheet with tin. It was developed as a durable, unpainted successor to traditional terne plate, which was carbon steel or iron coated with a lead-tin alloy and had to be painted to survive.\n\n## Coating history\n\nEarly terne coatings contained mostly lead. For environmental reasons lead was later dropped in favour of a tin-zinc alloy of roughly equal parts, and that product has since been discontinued too. Current terne-coated stainless uses a coating of about 99.9% tin, applied electrolytically (by galvanic deposition) rather than by hot-dipping. Proprietary names include TCS II and Roofinox.\n\n## Appearance and weathering\n\nFresh material is bright; the tin surface then dulls to a soft, uniform matte grey patina outdoors. Because the base metal is stainless, the roof does not need painting. Service lives of 100 years or more without painting are commonly cited.\n\n## Base grades\n\nGrade 439 stainless is used as the substrate for ordinary inland exposures, and 316L, which resists chlorides better, for coastal sites.\n\n## Uses\n\nTCS is formed and soldered much like traditional terne, so it is widely used to replace old terne and tin roofs on historic buildings, as well as for standing seam, flat seam and batten seam roofs, gutters and flashings on new work. Copper is the other common choice for replacing terne roofs.\n\n## Practical notes\n\nAs with all stainless products, the thermal movement of long pans must be allowed for with sliding cleats, and contact with less noble metals such as zinc, aluminium or galvanized steel should be avoided in wet locations.","key_facts":[{"label":"Base metal","value":"Stainless steel (439 inland, 316L coastal)"},{"label":"Coating","value":"About 99.9% tin, electrolytically applied"},{"label":"Weathered colour","value":"Matte grey"},{"label":"Cited service life","value":"100+ years unpainted"}],"regions":["Global"],"aliases":["TCS","tin-coated stainless steel","terne II"],"related":["terne-plate","stainless-steel-roofing","tin-roof","flat-seam-roofing","standing-seam-metal-roof"],"company":null,"sources":[{"title":"Terneplate","url":"https://en.wikipedia.org/wiki/Terneplate","publisher":"Wikipedia"},{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"}],"country":null},{"slug":"terra-amata","title":"Terra Amata","category":"history","type":"place","summary":"A Lower Palaeolithic beach site in Nice, France, interpreted as a camp of pole-and-hide huts about 400,000 years old; the interpretation is disputed.","body":"Terra Amata is an archaeological site on the slopes of Mount Boron in Nice, France, about 26 m (85 ft) above present sea level on what was once a beach. It was found during building work in 1966 and became famous as a candidate for the oldest known built shelters. The site now lies beneath an apartment block that houses the Musée de Préhistoire Terra Amata.\n\n## Excavation\n\nHenry de Lumley was given permission to excavate from 28 January to 5 July 1966. His team worked seven days a week and, by the end, around the clock to record the deposits before construction resumed.\n\n## The hut interpretation\n\nDe Lumley described a series of huts on the beach, each with a hearth in the middle. Low walls of stones and pebbles on the northwest side of the hearths were read as windbreaks against the Mistral. He proposed that the huts were made of animal skins stretched over poles, with a hole for smoke, and that one shelter could hold twenty to forty people. The Smithsonian Human Origins Program describes post holes and evidence of several shelters, some up to 14.9 m (49 ft) long, and dates the site to about 400,000 years ago. De Lumley dated the dwellings to about 380,000 years ago.\n\n## The critique\n\nArchaeologist Paola Villa studied the site for her doctoral research and published *Terra Amata and the Middle Pleistocene archaeological record of southern France* in 1983. Her main points were:\n\n- the stone \"arrangements\" could have formed naturally, through stream flow, soil creep or similar processes;\n- stone artefacts from supposedly separate living floors fit back together, showing that objects had moved up and down through the sediment;\n- the layers were therefore mixed, so neither the floors nor the dates could be treated as single episodes.\n\nVilla suggested a younger age, around 230,000 years ago. Other archaeologists, including Roebroeks and van Kolfschoten in 1994, have also treated natural deposition as at least as plausible as deliberate building.\n\n## Significance for roofing history\n\nTerra Amata is often reproduced in textbooks as an image of early hide-covered huts. For roofing history its value lies as much in the debate as in the reconstruction: it shows how little can be proven about perishable roofs, and how easily natural patterns can be read as architecture. The nearby Lazaret cave raises similar questions for a later period.","key_facts":[{"label":"Location","value":"Mount Boron, Nice, France"},{"label":"Excavated","value":"January-July 1966, by Henry de Lumley"},{"label":"Proposed age","value":"About 380,000-400,000 years; about 230,000 in Villa's view"},{"label":"Proposed covering","value":"Animal skins on poles"},{"label":"Status","value":"Interpretation disputed"}],"regions":["Europe"],"aliases":["Terra Amata huts"],"related":["lazaret-cave-shelter","prehistory-of-roofing","prehistoric-shelters-and-early-thatch"],"company":null,"sources":[{"title":"Terra Amata (archaeological site)","url":"https://en.wikipedia.org/wiki/Terra_Amata_(archaeological_site)","publisher":"Wikipedia"},{"title":"Terra Amata Shelter","url":"https://humanorigins.si.edu/evidence/behavior/terra-amata-shelter","publisher":"Smithsonian National Museum of Natural History"}],"country":null},{"slug":"terracotta","title":"Terracotta","type":"term","summary":"Fired, usually unglazed clay, typically reddish from iron oxide; in roofing the word is often used for natural clay tiles.","body":"Terracotta (Italian for \"baked earth\") is fired clay, especially the porous, reddish-brown kind left unglazed. In roofing, the word is widely used to describe natural, unglazed clay tiles and their colour, though manufacturers also use it loosely for any red-brown tile, including concrete.\n\n## Firing and colour\n\nTerracotta is typically fired at around 1,000 °C (1,830 °F); some historic and archaeological pieces were fired at temperatures as low as about 600 °C (1,112 °F). During firing, iron oxides in the clay react with oxygen to produce the familiar red; depending on the clay and kiln atmosphere, colours range from yellow, buff and orange to pink, grey and brown.\n\n## Porosity and frost\n\nOrdinary terracotta is not watertight. Its porosity can be reduced by burnishing the surface before firing or by glazing, but glazing alone does not seal a porous body. Clay products exposed to freeze-thaw cycles and salts, including roof tiles in cold climates, are generally fired to or near vitrification so that they absorb little water. Low-fired terracotta can flake and crumble when absorbed water freezes.\n\n## In roofing\n\n- Unglazed clay roof tiles of many profiles (plain, pantile, mission, Spanish and interlocking) are commonly called terracotta tiles.\n- Terracotta-coloured concrete tiles imitate the look but obtain their colour from pigment, which can fade.\n- Architectural terracotta, the moulded decorative facing used on buildings, had a major revival in the mid-19th century and, after the Great Chicago Fire of 1871 raised demand for fireproof materials, remained popular in North America into the early 1900s.\n\n## Weathering\n\nUnglazed terracotta roofs weather gradually, often darkening and gaining lichens and mosses that many owners regard as part of their character. Because the colour runs through the whole tile, chips and wear do not reveal a different-coloured core.\n","key_facts":[{"label":"Meaning","value":"Italian for \"baked earth\""},{"label":"Typical firing","value":"About 1,000 °C (1,830 °F)"},{"label":"Colour source","value":"Iron oxides in the clay"}],"regions":["Global"],"aliases":["terra cotta","terra-cotta tile","unglazed clay tile"],"related":["clay-roof-tile","glazed-roof-tile","concrete-roof-tile"],"sources":[{"title":"Terracotta","url":"https://en.wikipedia.org/wiki/Terracotta","publisher":"Wikipedia"},{"title":"Roof tiles","url":"https://en.wikipedia.org/wiki/Roof_tiles","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"terreal","title":"Terreal","category":"manufacturers","type":"company","summary":"Terreal is a French maker of clay roof tiles and brick formed in 2002 from older French tile works, and part of Wienerberger since 2024.","body":"Terreal is a French manufacturer of fired-clay building products, best known for clay roof tiles. Its oldest predecessor, TBL Guiraud Freres, dates from 1855. The group itself took shape when three French tile and brick makers, Lambert, TBF and Guiraud, were brought together, first under a holding company created in 1991 and then as Saint-Gobain Terreal in 2002. Terreal was acquired by the Austrian group Wienerberger, a process completed in early 2024.\n\n## Ownership history\n\n- **1991**: A holding company, Industrielle de Tuiles, consolidated the three French firms.\n- **1996**: The business joined Saint-Gobain.\n- **2002**: Saint-Gobain Terreal was formed.\n- **2003**: The company left Saint-Gobain and became Groupe Terreal, taking with it the US clay tile maker Ludowici.\n- **2020-2021**: Terreal combined with the German clay tile maker Creaton.\n- **2022**: Wienerberger made an offer for Terreal.\n- **2024**: The acquisition was completed. Terreal's French website now redirects to Wienerberger France.\n\n## Products\n\nTerreal produces clay roof tiles in regional French styles, including flat tiles and Roman or canal (curved) tiles used in southern France, plus ridge and fitting pieces, chimneys, clay facade cladding and load-bearing brick. It developed roof-integrated solar products through Terreal Solaire, created in 2010, and also supplied metal roofing components.\n\n## Footprint\n\nBefore its acquisition the group had manufacturing in France, Italy, Spain, Germany, Poland and the United States, with additional activity in Belgium, the Netherlands and Hungary, a plant in Malaysia opened in 2017, and joint ventures or sales offices in Mexico and Brazil. Spanish and Italian businesses were added through purchases of Ceramicas del Ter and San Marco Laterizi in 1987.","key_facts":[{"label":"Oldest predecessor","value":"TBL Guiraud Freres, 1855"},{"label":"Formed","value":"2002 (as Saint-Gobain Terreal)"},{"label":"Country","value":"France"},{"label":"Parent","value":"Wienerberger (since 2024)"},{"label":"Products","value":"Clay roof tiles, brick, facade cladding"}],"regions":["Europe","North America"],"aliases":["Groupe Terreal","Saint-Gobain Terreal"],"related":["wienerberger","creaton","ludowici","clay-roof-tile","building-integrated-photovoltaics"],"company":{"founded":"2002","parent":"Wienerberger","known_for":["Clay roof tiles","Brick","Clay facade cladding"]},"sources":[{"title":"Terreal","url":"https://fr.wikipedia.org/wiki/Terreal","publisher":"Wikipedia (French)"},{"title":"Wienerberger","url":"https://en.wikipedia.org/wiki/Wienerberger","publisher":"Wikipedia"},{"title":"Creaton","url":"https://de.wikipedia.org/wiki/Creaton","publisher":"Wikipedia (German)"}],"country":null},{"slug":"tesla-solar-roof","title":"Tesla Solar Roof","category":"manufacturers","type":"company","summary":"Tesla Solar Roof is a roof covering of glass solar tiles and steel tiles sold by Tesla's energy business, unveiled in 2016 and in volume production from 2020.","body":"Tesla Solar Roof is a building-integrated photovoltaic (BIPV) roofing product sold by Tesla, the US electric-vehicle and energy company. Rather than mounting solar panels on top of an existing roof, the system replaces the roof covering with a mix of active glass solar tiles and matching non-solar tiles, so that the whole roof has a uniform appearance. Each system is designed to work with Tesla's Powerwall home battery.\n\n## History\n\nTesla unveiled the Solar Roof in August 2016, shortly after announcing on 1 August 2016 its all-stock acquisition of the solar installer SolarCity, valued at about USD 2.6 billion. The SolarCity deal closed on 21 November 2016. Limited tile production began in August 2017 at Tesla's factory in Buffalo, New York (Giga New York). By July 2019 only around a dozen roofs had been completed. Tesla introduced a redesigned version later in 2019, after an earlier design proved too costly to make in volume, and began volume production in March 2020.\n\nIn January 2021 Panasonic, Tesla's manufacturing partner at Buffalo, withdrew from solar production. In April 2021 Tesla notified customers who had pre-ordered roofs of price increases of about 30 percent, and Elon Musk acknowledged significant mistakes in the project. A March 2023 estimate by Wood Mackenzie put total US Solar Roof installations since 2016 at about 3,000, far below early projections.\n\n## Product\n\nThe roof combines tempered-glass solar tiles with architectural-grade steel tiles that are visually matched in colour and trim. Because the tiles are smaller than conventional panels, the active area can be laid out around vents, skylights and other roof obstructions. Tesla offers separate module, product and weatherisation warranties.\n\n## Context\n\nSolar Roof is one of several solar-shingle approaches in North America, alongside nailable solar shingles introduced by conventional roofing manufacturers. Installation involves both roofing and electrical work, since the tiles form the weatherproof roof covering as well as the generating surface.","key_facts":[{"label":"Unveiled","value":"August 2016"},{"label":"Volume production","value":"March 2020"},{"label":"Maker","value":"Tesla, Inc."},{"label":"Components","value":"Glass solar tiles, steel tiles, Powerwall"},{"label":"US installs (est. to 2023)","value":"About 3,000"}],"regions":["North America"],"aliases":["Solar Roof","Tesla solar tiles"],"related":["building-integrated-photovoltaics","gaf"],"company":{"website":"https://www.tesla.com/solarroof","parent":"Tesla, Inc.","known_for":["Glass solar roof tiles","Integration with Powerwall battery"]},"sources":[{"title":"Solar Roof","url":"https://en.wikipedia.org/wiki/Tesla_Solar_Roof","publisher":"Wikipedia"},{"title":"Solar Roof support","url":"https://www.tesla.com/support/energy/solar-roof","publisher":"Tesla"}],"country":null},{"slug":"thai-temple-roof","title":"Thai Temple Roof","category":"world-roofing","type":"article","summary":"The tiered, steep roof of Thai Buddhist halls and palaces, with overlapping tiers, naga bargeboards (lamyong), hang hong finials and the bird-beak chofa.","body":"The Thai temple roof is the stacked, steeply pitched roof of Buddhist ordination halls (*ubosot*), shrine halls (*wihan*) and royal buildings in Thailand, recognisable by its overlapping tiers and its serpent and bird ornaments. Related forms appear in Laos, Cambodia and Myanmar.\n\n## Tiers\n\nOrnamented, tiered roofs are reserved for temples, palaces and important public buildings. Most have two or three tiers, and some royal temples have four. The lowest tier is the largest and the top the smallest, which makes the mass of the roof look lighter. Each tier is also broken into overlapping sections along its length; a double-tiered roof may have two to four breaks per tier. Sources describe the tiering as more aesthetic than functional.\n\nRegional differences:\n\n- **Central Thai temples:** the lower tiers project only a short way beyond the top roof at the gable ends.\n- **Northern (Lanna) temples:** the roof is larger and sweeps low over the walls, and the lower tiers telescope toward the entrance.\n\n## Ornaments\n\nMost decoration sits on the bargeboards at the gable ends:\n\n- **Lamyong** - the long bargeboard, carved in a wavy, serpent-like shape that evokes the *naga*.\n- **Bai raka** - blade-like projections along the lamyong, read as naga fins or Garuda feathers.\n- **Hang hong** - the lower finial at the foot of each bargeboard, usually an upturned naga head, sometimes multi-headed; multi-tiered roofs have one at the bottom of each tier.\n- **Chofa** - the tall curved finial at the peak, shaped like a bird's beak and often interpreted as Garuda.\n- **Kranok** - flame-like motifs used on naga heads and other ornament.\n\nSome Ayutthaya-style halls, such as Wat Oi, have no chofa, and Chinese-influenced halls from the reign of Rama III, such as the ubosot of Wat Ratchaorasaram in Bangkok, have single-front roofs without chofa.\n\n## The \"sagging hull\" roofline\n\nIn late Ayutthaya architecture, both the base and roofline of some halls curve concavely, resembling the hull of a Chinese junk. The form is called *yon thong samphao*, also *tok thong chang* (\"sagging elephant's belly\").\n\n## Examples\n\n- **Wat Phra Kaew, Bangkok** - ordination hall with a multiple-front roof.\n- **Wat Ratchaorasaram, Bangkok** - Thai-Chinese hall without chofa.\n\n## Related forms\n\nThe Burmese *pyatthat* uses odd-numbered stacked roofs with corner ornaments analogous to the chofa. Lao temples, such as Wat Xieng Thong in Luang Prabang, have cascading multi-tiered roofs, and Khmer pagodas use double-tiered roofs.","key_facts":[{"label":"Tiers","value":"Usually 2-3; some royal temples 4"},{"label":"Main ornaments","value":"Chofa, lamyong, bai raka, hang hong"},{"label":"Regional types","value":"Central; Lanna (northern)"},{"label":"Late Ayutthaya form","value":"Yon thong samphao (sagging-hull roofline)"}],"regions":["Southeast Asia"],"aliases":["chofa","chofah","lamyong","Thai wat roof","Thai tiered roof"],"related":["roofing-in-thailand","pyatthat","pagoda-roof","roofing-in-laos","roofing-in-cambodia","clay-roof-tile","bargeboard"],"company":null,"sources":[{"title":"Thai temple art and architecture","url":"https://en.wikipedia.org/wiki/Thai_temple_art_and_architecture","publisher":"Wikipedia"},{"title":"Architecture of Thailand","url":"https://en.wikipedia.org/wiki/Architecture_of_Thailand","publisher":"Wikipedia"}],"country":null},{"slug":"thatch","title":"Thatch","type":"article","summary":"A roof covering of dry plant stems such as reed, straw, sedge, palm or grass, laid thickly so rain runs off the outer layer.","body":"Thatch is a roof covering made from dry vegetation, most often water reed, cereal straw, sedge, heather, palm leaves or grasses, laid in thick layers on a steeply pitched roof. Water runs down the outer stems and drips off the eaves before it can soak deep into the bundle. Thatching is one of the oldest building crafts and is still practised on every inhabited continent.\n\n## How thatch works\n\nThatch does not form a waterproof skin. Instead, steeply angled stems carry water from one to the next along the surface, so only the outer few centimetres get wet. A pitch of about 45-55° is typical, and a pitch of at least 50° helps rain run off before it penetrates. Areas with heavy snowfall, such as parts of Japan, use even steeper roofs.\n\n## Main materials\n\n- **Water reed** (Norfolk reed): the most durable thatch in northern Europe.\n- **Long straw**: threshed wheat or rye straw, traditional across much of lowland England.\n- **Combed wheat reed**: straw combed to remove grain and leaf, typical of south-west England.\n- **Sedge**: a wetland plant used mainly for ridges.\n- **Heather, broom, rushes, marram and bracken**: local materials in upland and coastal areas, now rare in Britain.\n- **Palm leaves and grasses**: including coconut palm in East Africa (makuti), pili grass in Hawaii and alang-alang in South-east Asia.\n\n## Lifespan and maintenance\n\nGood water reed on a steep roof in a dry climate can last 50 years or more, and some roofs have lasted over 70 years; modern imported reed on an average English roof is more likely to give about 40 years. Long straw roofs have lasted 25-50 years. The ridge takes the most weather and usually needs renewing every 10-15 years. In Britain, many old roofs have been recoated again and again (\"spar coating\") rather than stripped, building up layers more than 2 m (7 ft) thick and in some cases preserving thatch over 600 years old.\n\n## Insulation\n\nThatch is a good insulator. Historic England gives theoretical U-values of about 0.29 W/m²K for 300 mm (12 in) of water reed and 0.23 W/m²K for the same thickness of long straw, close to modern replacement-roof standards without added insulation.\n\n## Fire\n\nFire risk is often overstated but is real: fire can spread very quickly once thatch ignites. Most thatch fires start from chimneys, wood burners or electrical faults. UK guidance recommends well-maintained, lined chimneys swept at least twice a year, loft smoke alarms and fire-retardant boards under new thatch.\n\n## Distribution\n\nEngland has an estimated 50,000 thatched buildings, and the UK as a whole about 60,000 thatched properties (2013 estimate). Thatch is also traditional in Ireland, the Netherlands, Denmark, northern Germany, Japan, sub-Saharan Africa, the Pacific islands and South-east Asia.\n","key_facts":[{"label":"Typical pitch","value":"45-55°"},{"label":"Water reed life","value":"About 40-70 years"},{"label":"Long straw life","value":"About 25-50 years"},{"label":"Ridge renewal","value":"Every 10-15 years"},{"label":"U-value (300 mm reed)","value":"About 0.29 W/m²K (theoretical)"},{"label":"Thatched buildings, England","value":"About 50,000"}],"regions":["Global","Europe","Africa","East Asia","Southeast Asia","Oceania"],"aliases":["thatched roof","thatching"],"related":["water-reed-thatch","long-straw-thatch","combed-wheat-reed","palm-thatch","sod-roof","bamboo-roofing"],"sources":[{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Thatched Roofs - An Introduction","url":"https://www.buildingconservation.com/articles/thatchrf/thatchrf.htm","publisher":"Building Conservation"},{"title":"Energy Efficiency and Historic Buildings: Insulating Thatched Roofs","url":"https://cms.historicengland.org.uk/images-books/publications/eehb-insulating-thatched-roofs/heag079-thatched-roofs","publisher":"Historic England"},{"title":"About thatch","url":"https://eamta.co.uk/about-thatch/","publisher":"East Anglia Master Thatchers Association"}],"category":"materials","company":null,"country":null},{"slug":"thatch-maintenance","title":"Thatch Maintenance and Decay","category":"problems-maintenance","type":"article","summary":"The care cycle of a thatched roof, including periodic ridge replacement, patching, and eventual rethatching as the coatwork wears away.","body":"A thatched roof wears differently from most other coverings. Rather than failing at joints, the whole surface slowly erodes as the exposed ends of the straw or reed decay and are washed away. The roof stays watertight as long as there is enough thickness of sound material over the fixings. Maintenance therefore follows a predictable cycle of ridge work, patching and, eventually, a new top coat or full rethatch.\n\n## The maintenance cycle\n\n- **Ridges.** The ridge is the most exposed and most worked part of a thatched roof. UK thatching advice commonly cites ridge replacement roughly every 10 to 15 years, regardless of the main coat's condition.\n- **Coatwork.** The main body of thatch lasts much longer, but its life varies with material (water reed, combed wheat reed, long straw, sedge and others), the skill of the thatcher, roof pitch, local climate, shading and how well the roof can dry. Repairs become poor value once the surrounding material has little life left.\n- **Rethatching.** Traditionally, many roofs are re-coated by fixing a new layer over sound base coats; in other cases the roof is stripped back. Heritage authorities may require that the original material type and local style be retained on listed buildings.\n\n## Signs of decay\n\n- Wire netting standing proud and fixings (spars, liggers, crooks) exposed on the ridge or coat.\n- Lines, hollows and dips across the coatwork.\n- Dark, wet-looking areas at the eaves that may indicate water penetration.\n- Cracked or detached flashings at chimneys.\n- Heavy moss and lichen, which tend to accompany well-decayed roofs and keep the thatch wet.\n- Bird and rodent damage, with holes and loose material.\n\n## Care\n\nThatchers advise keeping the roof able to dry by cutting back trees and vegetation, avoiding ladders and foot traffic on the thatch, and wiring ridges or whole roofs against vermin where appropriate. Isolated bird damage can be patched in matching material. Fire safety is a specific concern: chimney maintenance, spark arrestors, fire-retardant barriers and suitable insurance are widely recommended. Thatch is used in many regions, including the UK, the Netherlands, Denmark, Japan and southern Africa, each with its own materials and conventions.","key_facts":[{"label":"Typical ridge renewal","value":"About every 10-15 years (UK guidance)"},{"label":"How thatch fails","value":"Gradual surface erosion of the coatwork"},{"label":"Key decay signs","value":"Exposed fixings, dips, wet eaves, heavy moss"}],"regions":["Europe","Africa","East Asia","Global"],"aliases":["thatched roof maintenance","rethatching","re-ridging"],"related":["thatch","water-reed-thatch","long-straw-thatch","roof-moss","animal-damage"],"company":null,"sources":[{"title":"Overview of thatch maintenance","url":"https://www.thatchadvicecentre.co.uk/?p=220","publisher":"Thatch Advice Centre"},{"title":"Thatch Maintenance and Repair","url":"https://www.thatchadvicecentre.co.uk/?p=186","publisher":"Thatch Advice Centre"},{"title":"Thatched roofs","url":"https://www.spab.org.uk/node/514","publisher":"Society for the Protection of Ancient Buildings"},{"title":"How thatch works","url":"https://eamta.co.uk/about-thatch/how-thatch-works/","publisher":"East Anglian Master Thatchers Association"}],"country":null},{"slug":"thatch-ridge","title":"Thatch Ridge","category":"installation","type":"term","summary":"A thatch ridge is the separate covering laid over the apex of a thatched roof to bind and protect the main coat; it is renewed more often than the roof.","body":"The **ridge** of a thatched roof is a separate layer of pliable material laid along the apex, where the two slopes of thatch meet. It binds the top courses together and protects them from the weather, which is most severe at the top of the roof. Because of that exposure, ridges are renewed more often than the main coat of thatch, on average every 10 to 15 years according to Building Conservation guidance.\n\n## Materials\n\nRidges are usually made of the same material as the main coat, but water reed is too stiff and brittle to bend over the apex, so water reed roofs are commonly ridged with **sedge** or straw. Sedge grows in wetland areas and is used extensively for ridging.\n\n## Types\n\n- **Wrap-over ridge.** The most widely used type: a thick layer of straw or sedge is folded over the apex and fixed on both sides.\n- **Butt-up ridge.** Found mainly in south-west England: bundles are forced together with their butts meeting from either side to form the apex.\n- **Flush ridge.** Finished level with the surface of the main coat.\n- **Block-cut (raised) ridge.** Built up proud of the main coat and cut to a decorative edge with scallops, points or other patterns.\n\n## Fixing and decoration\n\nRidges are held with hazel **spars**, twisted and pointed into staples, and with **liggers**, split hazel or willow rods laid along the surface. Liggers are often arranged in diamond or cross-hatched patterns that both secure the ridge and serve as a thatcher's signature. Wire netting is commonly added to protect against birds.\n\n## Maintenance\n\nWhen a ridge is replaced, the old ridge and any decayed material beneath it are removed back to sound thatch before the new ridge is laid. Regular ridge renewal extends the life of the main coat beneath. Ridge styles are often regulated on listed buildings in England so that local traditions are kept.","key_facts":[{"label":"Renewal interval","value":"About 10-15 years on average"},{"label":"Common ridge material on water reed","value":"Sedge"},{"label":"Main types","value":"Wrap-over, butt-up; flush or block-cut"}],"regions":["Europe"],"aliases":["thatched ridge","ridge thatching"],"related":["thatching-process","yealming","thatch"],"company":null,"sources":[{"title":"Thatched Roofs: An Introduction","url":"https://buildingconservation.com/articles/thatchrf/thatchrf.htm","publisher":"Building Conservation"},{"title":"Thatching Terms","url":"https://thatchingadvisoryservices.co.uk/thatching-terms","publisher":"Thatching Advisory Services"},{"title":"Types of thatching","url":"https://www.lookingatbuildings.org.uk/construction/materials/thatch/types-of-thatching.html","publisher":"Looking at Buildings (Pevsner Architectural Guides)"}],"country":null},{"slug":"thatching-advisory-services","title":"Thatching Advisory Services","summary":"Thatching Advisory Services is a UK firm based in Devon that gives advice on thatching and thatch fire safety and supplies fire-protection systems.","body":"Thatching Advisory Services is a private company in the United Kingdom that provides advice on thatched roofs, with a particular focus on fire safety. It has operated for more than 45 years and is based in Seaton, Devon, in south-west England. Its website is thatchingadvisoryservices.co.uk.\n\nBecause it is a commercial firm rather than a membership association, it differs from bodies such as the National Society of Master Thatchers. It is included here because it is a widely known source of thatch-related guidance in the UK.\n\n## Areas of advice\n\n- **General thatching advice** for owners, buyers, architects and insurers on thatch materials, condition and maintenance.\n- **Fire safety for thatched buildings.** The company publishes guidance on fire barriers for existing thatched properties and for new builds and extensions.\n\n## Fire protection products\n\nThe company supplies fire-protection systems used with thatch, including fire boards and fire-wall membranes installed beneath the thatch, insulation batts, fire-retardant sprays and a chimney monitoring system that warns of overheating. It also supplies an intumescent joint sealant.\n\n## Why fire safety matters for thatch\n\nThatch is made of dry plant material such as water reed or straw. Fires in thatched buildings are uncommon, but they can spread quickly once the roof ignites and are hard to put out, because fire travels inside the thick layer of thatch. Common causes include chimney sparks and heat transfer through chimney walls, electrical faults and work involving open flames. Measures commonly recommended in the UK include:\n\n- regular chimney sweeping and inspection;\n- correct chimney height and spark arrestors;\n- fire barriers between the thatch and the roof structure on new or re-thatched roofs;\n- care with outdoor fires, fireworks and hot works nearby.\n\nBuilding regulations, insurers and local fire services may set their own requirements, and listed building consent may be needed for changes to historic thatched roofs.\n\n## Neutral note\n\nProduct choices for thatch fire protection vary, and owners usually take advice from a thatcher, building control and their insurer.","key_facts":[{"label":"Type","value":"Private advisory and supply company"},{"label":"Location","value":"Seaton, Devon, England"},{"label":"Operating","value":"More than 45 years"},{"label":"Focus","value":"Thatch advice and fire safety"}],"regions":["Europe"],"aliases":["Thatching Advisory Service","TAS"],"related":["thatch","national-society-of-master-thatchers","historic-england"],"company":{"headquarters":"Seaton, Devon, England","website":"https://www.thatchingadvisoryservices.co.uk","known_for":["Thatch fire-safety advice and products"]},"sources":[{"title":"Thatching Advisory Services","url":"https://www.thatchingadvisoryservices.co.uk/","publisher":"Thatching Advisory Services"},{"title":"National Society of Master Thatchers","url":"https://www.nsmt.co.uk/","publisher":"National Society of Master Thatchers"}],"category":"organizations","type":"organization","country":null},{"slug":"thatching-process","title":"Thatching Process","category":"installation","type":"article","summary":"Thatching lays bundles of water reed, wheat straw or similar plants in thick overlapping coats, fixed with sways, spars and liggers and finished with a ridge.","body":"**Thatching** is the craft of building a roof covering from dry plant stems laid in thick, steeply pitched layers. It is practised across the world, using water reed, cereal straw, sedge, heather, palm leaves and grasses. In England, where the craft is well documented, three main materials are used: **water reed**, **combed wheat reed** and **long straw**. Each has its own preparation, fixing and dressing methods, and regional traditions remain strong.\n\n## Preparing the material\n\n- **Water reed** is used in bunches with little further preparation.\n- **Combed wheat reed** is wheat straw passed through a comber that removes the grain and leaf, leaving the butts aligned; it is tied into bundles.\n- **Long straw** is threshed but not combed, then **yealmed** on the ground: wetted, straightened and tidied into compact layers called yealms, level at both ends.\n\n## Fixing\n\nFor a new water reed roof, bunches are fixed directly to the rafters or battens starting at the eaves, butts outward. Each course is held down by horizontal **sways** (rods of steel, hazel or willow) secured to the rafters, and the reed is beaten into shape with a **legget**, a wooden tool with a ridged face. Combed wheat reed is laid and dressed in a similar way.\n\nLong straw is usually applied as a new coat over an existing base coat. The thatcher removes old weathered material back to sound thatch, then fixes the new yealms with twisted, pointed hazel **spars**. Hazel rods called **liggers** are fixed across the eaves and gables, and the roof is often covered with wire netting against birds and rodents.\n\n## Ridges\n\nThe ridge takes the most weather and is replaced more often than the main coat, on average every 10 to 15 years according to Building Conservation guidance. Ridges are usually made from the same material as the main coat, except that water reed roofs are commonly ridged with sedge. The two main ridge types are the **wrap-over** and the **butt-up**, and either may be finished **flush** with the main coat or **block-cut** and raised, often with decorative patterns of liggers and spars.\n\n## Durability\n\nWater reed is the most durable of the English materials; steep Norfolk reed roofs in East Anglia last about 50 to 60 years on average, and some longer. Life for all thatch depends heavily on pitch, exposure, material quality and workmanship. Fire safety measures and regular maintenance are important parts of owning a thatched roof.","key_facts":[{"label":"Main English materials","value":"Water reed, combed wheat reed, long straw"},{"label":"Ridge renewal","value":"Every 10-15 years on average"},{"label":"Water reed life (East Anglia)","value":"About 50-60 years"}],"regions":["Europe","Africa","Southeast Asia","Global"],"aliases":["thatching","thatched roof construction"],"related":["yealming","thatch-ridge","thatch","water-reed-thatch"],"company":null,"sources":[{"title":"Thatched Roofs: An Introduction","url":"https://buildingconservation.com/articles/thatchrf/thatchrf.htm","publisher":"Building Conservation"},{"title":"Thatching Terms","url":"https://thatchingadvisoryservices.co.uk/thatching-terms","publisher":"Thatching Advisory Services"},{"title":"Types of thatching","url":"https://www.lookingatbuildings.org.uk/construction/materials/thatch/types-of-thatching.html","publisher":"Looking at Buildings (Pevsner Architectural Guides)"}],"country":null},{"slug":"thermal-emittance","title":"Thermal Emittance","type":"term","summary":"How efficiently a surface releases absorbed heat as infrared radiation, rated from 0 to 1; high values help roofs stay cool.","body":"Thermal emittance (also called emissivity) describes how efficiently a surface cools itself by radiating heat as far-infrared energy. It is rated on a scale from 0 to 1. A surface with high emittance releases absorbed heat readily; a surface with low emittance holds on to heat and stays hotter.\n\n## Role in cool roofs\n\nA roof heats up by absorbing sunlight and cools by convection (air moving over it) and radiation. Lawrence Berkeley National Laboratory defines a cool roof as one with both high solar reflectance and high thermal emittance. The two properties are independent because they involve different parts of the spectrum: solar reflectance concerns sunlight, while thermal emittance concerns the much longer infrared wavelengths a warm surface emits. The US EPA notes that thermal emittance matters most in warm, sunny climates.\n\n## Typical values\n\nMost non-metallic roofing materials, including membranes, shingles, tile, coatings and painted metal, have high emittance. Bare, shiny metal surfaces, such as unpainted aluminium or galvanized steel, have low emittance. That is why a bright bare metal roof can reflect sunlight well yet still run warmer than expected: it absorbs less heat but releases what it does absorb slowly.\n\n## Measurement and rating\n\nThermal emittance is measured with standard laboratory methods and reported, along with solar reflectance, by rating programs such as the Cool Roof Rating Council. Values are often reported both when new and after outdoor aging.\n\n## Night-time effects\n\nHigh emittance helps a roof shed heat to the night sky. On clear nights this can cool the roof surface below air temperature. That benefits cooling in hot climates but can contribute to condensation on the underside of roof decks in some climates if moisture is present.\n\n## Combined index\n\nSolar reflectance and thermal emittance are combined in the Solar Reflectance Index (SRI), which estimates how hot a surface will get in the sun relative to standard black and white surfaces.","key_facts":[{"label":"Scale","value":"0 to 1"},{"label":"Also called","value":"Emissivity"},{"label":"Low-emittance example","value":"Bare, shiny metal"},{"label":"Independent of","value":"Solar reflectance"}],"regions":["Global"],"aliases":["emissivity","infrared emittance","TE"],"related":["cool-roof","solar-reflectance","solar-reflectance-index","attic-condensation"],"sources":[{"title":"Cool Roofs","url":"https://heatisland.lbl.gov/coolscience/cool-roofs","publisher":"Lawrence Berkeley National Laboratory, Heat Island Group"},{"title":"Using Cool Roofs to Reduce Heat Islands","url":"https://www.epa.gov/heatislands/using-cool-roofs-reduce-heat-islands","publisher":"US Environmental Protection Agency"},{"title":"ASTM E1980 Standard Practice for Calculating Solar Reflectance Index of Horizontal and Low-Sloped Opaque Surfaces","url":"https://store.astm.org/e1980-11r19.html","publisher":"ASTM International"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"thermal-movement-in-metal-roofs","title":"Thermal Movement in Metal Roofs","category":"installation","type":"article","summary":"Metal roof panels lengthen and shorten with temperature; systems must let them slide, or seams, fasteners and flashings will fatigue, buckle or leak.","body":"All metals expand when heated and contract when cooled. A metal roof can swing from below freezing at night to well above air temperature in sun, so a long panel changes length noticeably every day. Good metal roof design does not try to stop this movement; it controls where it happens.\n\n## How much metals move\n\nApproximate coefficients of linear expansion:\n\n| Metal | per degree C (x 10^-6) | per degree F (x 10^-6) |\n|---|---|---|\n| Carbon steel | 10.8-12.5 | 6.0-6.9 |\n| Copper | 16-16.7 | 8.9-9.3 |\n| Stainless steel 304 | 17.3 | 9.6 |\n| Aluminium | 23 | 12.8 |\n| Lead | 29 | 16.1 |\n| Zinc | 30-35 | 16.7-19.4 |\n\nAs a worked example, a 10 m (33 ft) aluminium panel warming by 50 degrees C (90 degrees F) grows by about 11.5 mm (0.45 in). One zinc producer's rule of thumb is about 1 in per 30 ft of panel. Aluminium moves roughly twice as much as steel.\n\n## Design responses\n\n- **Clips**: standing seam panels use a fixed zone (often at the ridge or mid-slope) and sliding or expansion clips elsewhere, so the panel can move away from the fixed point. Sliding clips matter most on long panels and on aluminium; nail-strip (fastening flange) panels restrict movement and are limited to shorter lengths.\n- **Slip sheets**: on copper and other seamed roofs, rosin paper stops heat-softened asphalt underlayment from bonding the metal to the deck.\n- **Bay and pan limits**: lead, zinc and soldered flat seam copper are laid in limited bay sizes or with expansion battens and drips.\n- **Fasteners**: through-fastened sheets must not be overtightened; repeated cycling can loosen or snap screws.\n- **Flashings**: trims at eaves, ridges and walls must not lock panels at both ends.\n\n## Symptoms of restrained movement\n\nWaviness that comes and goes with temperature, popping or ticking noises, elongated fastener holes, broken clips, cracked solder joints and torn seams all suggest that movement has been restrained.","key_facts":[{"label":"Aluminium vs steel","value":"Aluminium moves about twice as much"},{"label":"Zinc rule of thumb","value":"About 1 in per 30 ft (25 mm per 9 m)"},{"label":"Standing seam solution","value":"Fixed zone plus sliding clips"}],"regions":["Global"],"aliases":["thermal expansion metal roof","expansion and contraction","thermal cycling"],"related":["standing-seam-clips","oil-canning","rosin-paper-slip-sheet","creep-in-sheet-metal","aluminum-roofing","zinc-roofing"],"company":null,"sources":[{"title":"Coefficients of Linear Thermal Expansion","url":"https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html","publisher":"The Engineering ToolBox"},{"title":"Essential Zinc: Building for the Future","url":"https://continuingeducation.bnpmedia.com/courses/umicore-building-products-usa-inc/essential-zinc-building-for-the-future/2/","publisher":"Continuing Education Center (BNP Media) / Umicore Building Products"},{"title":"8.1. Special Roofing Design and Installation Considerations","url":"https://copper.org/applications/architecture/arch_dhb/arch-details/roofing","publisher":"Copper Development Association"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Thermal Expansion & Oil Canning in Aluminum Roofs Explained","url":"https://www.interlockroofing.com/kb/aluminum-roof-thermal-expansion-oil-canning/","publisher":"Interlock Roofing"},{"title":"Standing Seam Types: Snap-Lock vs Mechanical Seam Explained","url":"https://www.interlockroofing.com/kb/standing-seam-types-snap-lock-vs-mechanical-seam/","publisher":"Interlock Roofing"}],"country":null},{"slug":"three-tab-shingle","title":"Three-Tab Shingle","type":"term","summary":"A single-layer asphalt strip shingle whose lower edge is divided by two cutouts into three equal tabs, giving a flat, uniform roof pattern.","body":"A three-tab shingle is the basic form of asphalt strip shingle. Each piece is a single layer of asphalt-coated mat with two notches, called cutouts, along the lower edge. The cutouts divide the exposed part of the strip into three tabs that look like three separate shingles once installed, producing a flat, brick-like grid on the roof.\n\n## Dimensions and weight\n\nThe traditional North American (\"English\") size is about 12 in by 36 in (305 by 914 mm), laid with a 5 in (127 mm) weather exposure. Metric strip shingles, slightly larger at about 13 by 39 in (333 by 1000 mm), are laid with a 5-5/8 in (143 mm) exposure. Three-tab shingles typically weigh 190-250 lb per square, or roughly 9-12 kg/m².\n\n## Performance\n\nBecause the product is a single layer, it is thinner and lighter than laminated shingles and usually costs less. Inspection references note typical wind ratings of about 60-70 mph (97-113 km/h); in strong wind the individual tabs can lift and tear if the sealant strip has not bonded. Manufacturer warranties have commonly run 20-30 years, but typical real-world lives are commonly given as about 15-18 years, depending on climate and ventilation.\n\n## Use today\n\nThree-tab shingles dominated the North American market for much of the 20th century. They are now losing share to architectural shingles, but remain common on lower-cost housing and rentals, and are still widely used as **starter strips** along the eaves and cut into pieces for **hip and ridge caps**. When a roof is repaired, colour and style matching can be difficult because product lines change over time.\n\n## Identification\n\nAn inspector can recognise a three-tab roof by the regular vertical slots repeating every 12 in (305 mm) and the even horizontal lines of each course. Laminated shingles, by contrast, have no cutouts and show irregular shadow lines.\n","key_facts":[{"label":"Size (US)","value":"About 12 x 36 in (305 x 914 mm)"},{"label":"Exposure","value":"5 in (127 mm); metric 5-5/8 in (143 mm)"},{"label":"Weight","value":"About 190-250 lb per square (9-12 kg/m²)"},{"label":"Typical life","value":"About 15-18 years (climate dependent)"}],"regions":["North America"],"aliases":["3-tab shingle","strip shingle","three-tab"],"related":["asphalt-shingle","architectural-shingle","starter-course"],"sources":[{"title":"Mastering Roof Inspections: Asphalt Composition Shingles, Part 6","url":"https://nachi.org/asphalt-comp-shingles-part6-60.htm","publisher":"InterNACHI"},{"title":"Asphalt Shingle Types (3-Tab vs. Laminated Architectural), ASTM Classifications & Thermal Behavior","url":"https://open-exam-prep.com/study-guides/la-roofing-contractor/asphalt-shingles-steep-slope-assemblies/shingle-types-astm-thermal","publisher":"Open Exam Prep"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"through-fastened-metal-panels","title":"Through-Fastened (Exposed-Fastener) Metal Panels","category":"materials","type":"article","summary":"Through-fastened metal panels are corrugated or ribbed sheets screwed through their face into the roof structure, with sealing washers under each screw head.","body":"Through-fastened, or exposed-fastener, metal roofing is the most widespread and least expensive form of metal roof. Profiled sheets, either corrugated or trapezoidal (box-ribbed), are laid with side laps over a rib and screwed directly through the sheet into purlins, battens or a deck. In North America common trapezoidal profiles are sold under names such as R-panel and PBR panel; in Europe, Australia and Asia they are usually called trapezoidal or ribbed sheets.\n\n## Fastening\n\nEach screw carries a sealing washer or gasket, typically EPDM rubber, that closes the hole. Screw metal must be compatible with the sheet to avoid galvanic corrosion; on aluminium, for example, aluminium or stainless steel fasteners are used rather than ordinary steel.\n\n## Advantages\n\n- Low material and labour cost.\n- Sheets span between supports and can be used over open framing on agricultural and industrial buildings.\n- Fast installation with simple tools.\n\n## Limitations\n\n- Every screw is a potential leak point; sunlight hardens washers and thermal cycling loosens screws, with problems typically starting after about 10 to 15 years, so periodic checking and re-screwing is part of maintenance.\n- Over-driven or angled screws distort the sheet and damage washers, and fasteners overtightened against thermal movement can fatigue.\n- Restricted thermal movement on long sheets can cause noise and waviness.\n- Over open framing without a deck or insulation, rain noise is more noticeable than on solid-deck systems.\n\n## Comparison with standing seam\n\nStanding seam panels use concealed clips and raised seams, allowing freer movement and fewer penetrations, which is why they are preferred on low slopes and long runs. Through-fastened sheets remain dominant on farm, industrial and low-cost housing roofs worldwide.","key_facts":[{"label":"Fixing method","value":"Screws through panel face with sealing washers"},{"label":"Common washer material","value":"EPDM rubber"},{"label":"Typical profiles","value":"Corrugated, trapezoidal (R-panel, PBR)"},{"label":"Main maintenance item","value":"Fastener and washer condition"}],"regions":["Global"],"aliases":["exposed fastener metal roof","R-panel","PBR panel","trapezoidal sheet","box profile","ag panel","screw-down panel"],"related":["corrugated-iron","standing-seam-metal-roof","metal-roof-fasteners","metal-roof-noise","oil-canning"],"company":null,"sources":[{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"},{"title":"Busting 5 Metal Roofing Myths","url":"https://www.rooferscoffeeshop.com/post/busting-5-metal-roofing-myths-2","publisher":"RoofersCoffeeShop"},{"title":"Product Advisory Bulletin PAB05: Oil Canning","url":"https://cdn.dcs.lysaght.com/download/lysaght-product-advisory-bulletin-pab05-oil-canning","publisher":"Lysaght (BlueScope)"},{"title":"Standing Seam vs Corrugated & Exposed-Fastener Metal Roofing","url":"https://www.interlockroofing.com/kb/standing-seam-vs-corrugated-metal-roofing/","publisher":"Interlock Roofing"},{"title":"Aluminum Roofing Fasteners: Concealed vs Exposed Explained","url":"https://www.interlockroofing.com/kb/aluminum-roofing-fasteners-concealed-vs-exposed/","publisher":"Interlock Roofing"}],"country":null},{"slug":"through-fastened-panel-installation","title":"Through-Fastened Panel Installation","category":"installation","type":"article","summary":"Through-fastened metal panels are screwed directly through the sheet into purlins or decking with sealing washers, with side and end laps sealed against water.","body":"**Through-fastened** (also called **exposed-fastener** or **pierce-fixed**) metal roofing is fixed by screws or nails that pass through the sheet into the supporting purlins, battens or deck. Corrugated sheet and trapezoidal (ribbed) profiles are the most common forms. It is the dominant roof type for houses in Australia and New Zealand and is widely used on agricultural, industrial and residential buildings around the world.\n\n## Fasteners and washers\n\nEach fastener needs a sealing washer to keep water out of the hole. The New Zealand metal roofing code of practice recommends washers of EPDM rubber and says fasteners should be tightened only enough to form a weatherproof seal, since overtightening dents the sheet and lets water pond around the seal. Metal swarf (drilling filings) should be cleared from the roof surface and from under washers, because it rusts and stains the coating.\n\nManufacturers specify whether screws go through the raised crests (ribs) or the flat pans of a given profile, and set screw spacing from wind loads, with closer spacing at edges and corners.\n\n## Side laps\n\nSheets overlap along their sides by a set amount, often one or more ribs or corrugations; corrugated sheet commonly laps by one and a half corrugations. Laps are normally laid so that the exposed edge faces away from the prevailing wind.\n\n## End laps\n\nThe New Zealand code recommends avoiding end laps where possible. Where they are needed, it gives a minimum lap of 150 mm on pitches of 10 degrees or more and recommends 200 mm on lower pitches, sealed at both ends of the lap, with the upper seal being critical.\n\n## Thermal movement\n\nLong pierce-fixed sheets expand and contract and can elongate fastener holes or shear screws. The New Zealand code requires expansion provisions for run lengths over 20 m when fixing into timber or hot-rolled steel, using measures such as oversized holes or a stepped joint in the roof.\n\n## Installation outline\n\n1. Check purlin or batten spacing and alignment.\n2. Start laying from the end of the roof opposite the prevailing wind, square to the eave.\n3. Fix each sheet with screws in the specified positions, lapping and stitching side laps as required.\n4. Turn up the sheet pans at the ridge (stop ends) and turn down at the gutter (drip edge) where specified.\n5. Install ridge, barge and wall flashings and clear all swarf.","key_facts":[{"label":"Sealing washer material (NZ COP)","value":"EPDM"},{"label":"End lap, pitch 10 degrees or more (NZ COP)","value":"Minimum 150 mm"},{"label":"End lap, pitch under 10 degrees (NZ COP)","value":"200 mm recommended"},{"label":"Corrugated side lap","value":"About 1 1/2 corrugations"}],"regions":["Oceania","Global"],"aliases":["exposed fastener metal roofing installation","pierce-fixed roofing","corrugated roof installation","screw-down metal roof"],"related":["standing-seam-installation","corrugated-iron","metal-roofing"],"company":null,"sources":[{"title":"NZ Metal Roof and Wall Cladding Code of Practice: Fastening Roofing","url":"https://www.metalroofing.org.nz/cop/roofing/fastening-roofing","publisher":"NZ Metal Roofing Manufacturers Inc."},{"title":"NZ Metal Roof and Wall Cladding Code of Practice: End Laps","url":"https://www.metalroofing.org.nz/cop/roofing/end-laps","publisher":"NZ Metal Roofing Manufacturers Inc."},{"title":"NZ Metal Roof and Wall Cladding Code of Practice: Thermal Expansion and Contraction","url":"https://www.metalroofing.org.nz/cop/roofing/thermal-expansion-and-contraction","publisher":"NZ Metal Roofing Manufacturers Inc."},{"title":"Corrugated galvanised iron","url":"https://en.wikipedia.org/wiki/Corrugated_galvanised_iron","publisher":"Wikipedia"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"}],"country":null},{"slug":"tile-battens","title":"Tile Battens","category":"installation","type":"term","summary":"Tile battens are horizontal timber strips fixed across the rafters or deck that set the spacing of tile or slate courses and provide their fixing point.","body":"**Battens** (in North America sometimes called **lath**, **strapping** or **purlins** on tile roofs) are lengths of sawn timber fixed horizontally across the rafters or roof deck. Tiles hang from them by their nibs and are nailed or clipped to them, and slates are nailed or hooked to them. The distance between battens, the **gauge**, equals the exposure of each course.\n\n## Counter-battens\n\nOn many modern roofs a second set of timbers, **counter-battens**, runs up the slope beneath the battens. They lift the battens off the underlay so that water that gets past the tiles can run down to the gutter and air can circulate. Canadian guidance for one tile system uses 38 x 9.5 mm (1 1/2 x 3/8 in) counter-battens and sets additional straps beside valleys, hips and walls.\n\n## Sizes and spacing\n\nBatten size depends on rafter spacing, tile weight and national rules. Canadian guidance for one concrete tile system calls for 25 x 100 mm (1 x 4 in) spruce battens of No. 2 grade or better, nailed into the trusses with nails long enough to penetrate at least 25 mm (1 in). The first batten is set from the eave blocking and the rest are spaced equally between eave and ridge, no more than 345 mm (13 3/4 in) apart.\n\n## Setting out\n\n1. Mark the eave and top batten positions from the tile manufacturer's gauge and the first-course details.\n2. Divide the distance into equal gauges within the manufacturer's maximum.\n3. Snap chalk lines on the rafters or counter-battens.\n4. Fix battens to each rafter, joining them only over supports.\n\n## UK practice\n\nIn the UK, BS 5534 covers the specification of battens alongside tile fixing, and BS 8000-6 covers workmanship on site. Battens there are commonly graded and marked as suitable for roofing. Timber treatment and grading rules differ by country and should be taken from national standards and the tile manufacturer.","key_facts":[{"label":"Function","value":"Set course gauge and provide fixing point"},{"label":"Batten example (Canada)","value":"25 x 100 mm (1 x 4 in) spruce"},{"label":"Counter-batten example (Canada)","value":"38 x 9.5 mm (1 1/2 x 3/8 in)"}],"regions":["Europe","Oceania","Global"],"aliases":["roofing battens","lath","counter-battens","strapping"],"related":["clay-and-concrete-tile-installation","bs-5534-fixing-specification","slate-roof-installation","underlayment-installation"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.3.3 Tile Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-3-tiles-clay-concrete-slate-metal/9-3-3-installation/","publisher":"Canadian Roofing Contractors Association"},{"title":"What is BS 5534?","url":"https://www.marley.co.uk/Blog/What-is-BS-5534","publisher":"Marley"},{"title":"What are the fixing requirements of BS 5534?","url":"https://www.marley.co.uk/blog/what-are-the-fixing-requirements-of-bs-5534","publisher":"Marley"}],"country":null},{"slug":"tile-clips","title":"Tile Clips","category":"installation","type":"term","summary":"Tile clips are metal fixings that hold the tail or side of a roof tile down against wind uplift; in storm-prone areas they are often called hurricane or storm clips.","body":"**Tile clips** are small metal fixings, made of corrosion-resistant metal, that hold a roof tile against wind uplift. Nails alone fix a tile near its head; a clip holds the tail or side, where wind suction tends to lift the tile. Clips are known by several names depending on design and region: **tail clips**, **eaves clips**, **verge clips**, **storm clips** and **hurricane clips**.\n\n## Types\n\n- **Tail clips.** Nailed to the batten below and hooking over the side lock or tail of the tile.\n- **Eaves clips.** Used on the first course, where uplift is highest.\n- **Verge clips.** Hold the cut tiles at gable edges.\n- **Hurricane and storm clips.** Heavier-duty clips used in high-wind regions, including on North American tile roofs, often combined with nails or adhesives.\n\n## When clips are used\n\nThe number and position of clips is set by wind calculations, not by habit. In the UK, BS 5534 requires single-lap tiles to be mechanically fixed and assumes higher wind loads than earlier editions; its 2018 amendment refined how clip uplift tests are interpreted. Manufacturer fixing specifications then show which tiles are nailed, which are clipped and which are both.\n\nIn Canadian guidance for one concrete tile system, metal storm clips are normally used on buildings taller than 12.2 m (40 ft) or where wind speeds exceed 130 km/h (80 mph), in consultation with the manufacturer.\n\n## Installation\n\n1. Lay the tile and nail it through its head hole where the specification calls for nails.\n2. Position the clip in the side lock or over the tail, as designed for that tile profile.\n3. Fix the clip to the batten with the nail supplied, without crushing the tile.\n4. Check that the next tile seats correctly over the clip.\n\nClips are profile-specific: a clip designed for one tile shape may not grip another.","key_facts":[{"label":"Purpose","value":"Resist wind uplift at tile tails and edges"},{"label":"UK basis","value":"BS 5534 wind-load fixing specification"}],"regions":["Global"],"aliases":["hurricane clips","storm clips","tail clips","tile clip"],"related":["clay-and-concrete-tile-installation","bs-5534-fixing-specification","wind-uplift","tile-battens"],"company":null,"sources":[{"title":"What are the fixing requirements of BS 5534?","url":"https://www.marley.co.uk/blog/what-are-the-fixing-requirements-of-bs-5534","publisher":"Marley"},{"title":"Canadian Roofing Reference Manual: 9.3.3 Tile Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-3-tiles-clay-concrete-slate-metal/9-3-3-installation/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"tile-roofing-industry-alliance","title":"Tile Roofing Industry Alliance (TRI Alliance)","summary":"The TRI Alliance is a North American association for concrete and clay roof tile, providing installation guides, training and code work.","body":"The Tile Roofing Industry Alliance (TRI Alliance) is a North American trade association for the concrete and clay roof tile industry. Its members include tile manufacturers, roofing contractors, consultants and suppliers. The organisation says it has represented the tile roofing industry for more than half a century. It lists an address in Seattle, Washington, and its website is tileroofing.org.\n\n## Mission\n\nThe TRI Alliance works to grow the market for tile roofs by raising awareness of their properties, providing technical expertise, and offering training and certification in code-approved installation methods.\n\n## Technical work\n\n- **Installation guides.** The association publishes installation guides for concrete and clay tile. The best known is the Florida High Wind Concrete and Clay Tile Installation Manual, produced with the Florida Roofing and Sheet Metal Contractors Association (FRSA). The manual has gone through several editions; the 6th edition was filed with the Florida Building Commission in 2020.\n- **Codes and testing.** It works on building code development and with ASTM on test methods for roof tile.\n- **Fire.** It worked with the Committee for Firesafe Dwellings on California legislation restricting combustible roofing materials.\n- **Wind and seismic.** After Hurricane Andrew in 1992, it supported stronger high-wind codes and upgraded installation standards. It also took part in a seismic study with the University of Southern California.\n\n## Training\n\nThe TRI Alliance runs training and certification classes on its installation manuals for roofers and inspectors, with sessions held in several U.S. states where tile roofs are common.\n\n## Context\n\nClay tile has been used for thousands of years around the Mediterranean, in East Asia and in Latin America. Concrete tile became widespread in the 20th century. In North America, tile is most common in the Sun Belt. Because tiles are heavy and can be dislodged by wind, attachment methods (nails, screws, clips, foam adhesive or mortar) are a central topic in its manuals.","key_facts":[{"label":"Focus","value":"Concrete and clay roof tile"},{"label":"Address","value":"Seattle, Washington, USA"},{"label":"Key publication","value":"Florida High Wind Concrete and Clay Tile Installation Manual (with FRSA)"},{"label":"Website","value":"tileroofing.org"}],"regions":["North America"],"aliases":["TRI Alliance","TRIA","Tile Roofing Institute"],"related":["concrete-roof-tile","florida-roofing-and-sheet-metal-contractors-association"],"company":{"headquarters":"Seattle, Washington, USA","website":"https://www.tileroofing.org","known_for":["Tile installation manuals","Installer training and certification"]},"sources":[{"title":"About TRI Alliance","url":"https://www.tileroofing.org/about-tri-alliance.html","publisher":"Tile Roofing Industry Alliance"},{"title":"Florida High Wind Tile Installation Manual, 6th Edition","url":"https://floridabuilding.org/upload/PR_Instl_Docs/FL24172_R1_II_Florida-High-Wind-Tile-Installation-Manual-6th-Edition-092020.pdf","publisher":"Florida Building Commission"},{"title":"How the TRI Alliance can help you","url":"https://eagleroofing.com/2019/02/how-the-tri-alliance-can-help-you/","publisher":"Eagle Roofing"}],"category":"organizations","type":"organization","country":null},{"slug":"tin-roof","title":"Tin Roof","category":"history","type":"term","summary":"\"Tin roof\" historically meant iron sheet coated with tin (tinplate); today it is a colloquial name for almost any sheet-metal roof.","body":"A true tin roof is made of tinplate: thin iron or steel sheet coated with tin. Very few modern roofs fit that description, but the phrase lives on as an everyday label for metal roofs in general, including galvanized corrugated steel, coated steel panels and even aluminium.\n\n## Historic tinplate roofs\n\nTin roofing was used widely in Canada in the eighteenth century and became common in the United States somewhat later. Thomas Jefferson put a standing seam tin roof on Monticello in the period around 1770 to 1802, and the Arch Street Meetinghouse in Philadelphia (1804) had tin shingles laid in a herringbone pattern. Once American rolling mills were operating, tinplate became the most common roofing metal because it was cheap, light and needed little upkeep. Embossed tin shingles were popular in the late nineteenth century.\n\nTin roofs were kept well painted, usually red. Because the base metal is iron, preservation guidance calls for priming the underside and maintaining the paint on top.\n\n## Tin versus terne\n\nHistoric records often confuse tinplate with terne plate, which used a cheaper lead-tin coating and has a duller finish. Both were installed with flat seams or standing seams and soldered joints, and both were eventually replaced in new construction by galvanized and aluminium-zinc coated steel, copper and terne-coated stainless steel.\n\n## Modern usage\n\nSpeaking of a \"tin roof\" today usually tells you only that the roof is metal. For repair, insurance or conservation work it is worth identifying the actual metal and coating, since compatible materials, fasteners and solders differ.","key_facts":[{"label":"Original meaning","value":"Tinplate: iron or steel sheet coated with tin"},{"label":"Historic finish","value":"Painted, usually red"},{"label":"Notable early example","value":"Monticello, standing seam tin roof (ca. 1770-1802)"},{"label":"Modern meaning","value":"Colloquial term for metal roofs generally"}],"regions":["North America","Global"],"aliases":["tinplate roof","tin roofing","tin shingles"],"related":["terne-plate","metal-roofing","corrugated-iron","metal-shingles","flat-seam-roofing"],"company":null,"sources":[{"title":"Preservation Brief 4: Roofing for Historic Buildings","url":"https://www.nps.gov/orgs/1739/upload/preservation-brief-04-roofing.pdf","publisher":"U.S. National Park Service, Technical Preservation Services"},{"title":"Terneplate","url":"https://en.wikipedia.org/wiki/Terneplate","publisher":"Wikipedia"},{"title":"Metal roof","url":"https://en.wikipedia.org/wiki/Metal_roof","publisher":"Wikipedia"}],"country":null},{"slug":"tongkonan","title":"Tongkonan","type":"article","summary":"Ancestral house of the Toraja of South Sulawesi, Indonesia, raised on piles under a huge boat-shaped saddleback roof of layered bamboo.","body":"The *tongkonan* is the ancestral house of the Toraja people of the highlands of South Sulawesi, Indonesia. It stands on wooden piles and is dominated by an oversized saddleback roof whose ends sweep upward, often compared to the hull of a boat. The name comes from the Torajan word *tongkon*, \"to sit\".\n\n## Roof construction\n\nThe roof is built from layers of split bamboo bound with rattan, laid across the rafters and tied lengthwise to form a thick, curved covering. Bamboo culms are also used as the under-roof. The structure below consists of large vertical posts joined by horizontal tie beams; hanging spars and angled members create the curve, and a free-standing pole often supports the projecting ridge at the front.\n\nBecause the roof extends well beyond the house at both ends, it shelters the front and rear and gives the building its dramatic profile.\n\n## Meaning and decoration\n\nThe tongkonan is the centre of Torajan family and social life, linking living relatives to ancestors and descendants. Origin stories say the first tongkonan was built in heaven on four poles with a roof of cloth, and the first ancestor copied it on earth. Traditionally three types were recognised, from the house of highest authority (*tongkonan layuk*) to houses of ordinary family members (*tongkonan batu*).\n\nWalls are covered in carvings painted red, black and yellow. Buffalo horns mounted in a vertical row on the front post signal the family's status, and a carved wooden buffalo head may crown the facade.\n\n## Modern change\n\nBuilding a tongkonan is labour-intensive and usually involves the extended family. Zinc or corrugated metal sheets and nails are increasingly used in place of bamboo layers, especially for repairs. The form is no longer reserved for nobility, and remittances from Toraja living elsewhere in Indonesia help fund larger houses. The silhouette also appears on government buildings in the region, such as administrative offices in Rantepao.","key_facts":[{"label":"People","value":"Toraja, South Sulawesi, Indonesia"},{"label":"Roof form","value":"Boat-shaped saddleback roof"},{"label":"Traditional covering","value":"Layered split bamboo tied with rattan"},{"label":"Modern covering","value":"Often zinc or corrugated metal"},{"label":"Structure","value":"Raised on wooden piles"}],"regions":["Southeast Asia"],"aliases":["Toraja house","Tongkonan house"],"related":["rumah-gadang","roofing-in-southeast-asia","bamboo-roofing","gable-roof"],"sources":[{"title":"Tongkonan","url":"https://en.wikipedia.org/wiki/Tongkonan","publisher":"Wikipedia"},{"title":"Torajan people","url":"https://en.wikipedia.org/wiki/Torajan_people","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"torch-applied-roofing","title":"Torch-Applied Modified Bitumen","category":"installation","type":"article","summary":"Torch-on application bonds modified bitumen membrane rolls by melting their underside with a propane torch as the roll is unrolled over the roof.","body":"**Torch-applied modified bitumen**, often called **torch-on**, is a low-slope roofing method in which rolls of polymer-modified bitumen membrane are bonded by heating their underside with a propane torch until the bitumen melts, then rolling them into place. It is common in Europe, Canada, the Middle East and many other regions, typically as a two-layer system of base sheet and cap sheet.\n\n## Technique\n\nCanadian guidance describes holding the flame 50 to 150 mm (2 to 6 in) in front of the roll at the point where it meets the substrate, moving the torch steadily across the full roll width, and unrolling once a small bead of melted bitumen appears. On field sheets a roll puller lets the installer walk backward so they never step on hot membrane. Signs of overheating include melted surface film, sinking granules, bitumen burning away to expose the reinforcement, and waves in the laid sheet.\n\n## Laps and staggering\n\n- Side laps of at least 75 mm (3 in) and end laps of at least 150 mm (6 in) for both base and cap sheets.\n- Cap sheet side laps offset at least 300 mm (12 in) and end laps at least 450 mm (18 in) from base sheet laps.\n- A visible bleed-out at side laps of no more than about 6 mm (1/4 in).\n- Granules at granular end laps embedded by heating and pressing with a hot trowel.\n\n## Flashings\n\nBase flashings extend at least 100 mm (4 in) onto the deck and at least 200 mm (8 in) up walls, and cap flashings at least 150 mm (6 in) onto the deck. Reinforcing gussets are used at inside and outside corners.\n\n## Safety\n\nTorch flames can exceed 1093 °C (2000 °F). Canadian guidance restricts torching to trained workers, requires a fire extinguisher on hand, and warns against torching near combustible materials. Many insurers and jurisdictions require torch safety training and a fire watch after work ends, and some restrict torch application on certain buildings. Where open flame is not acceptable, the same membranes are available for cold-adhesive or self-adhered installation, or can be set in hot-mopped asphalt.\n\n## Weather\n\nTorching slows in cold, humid conditions, and rolls should be kept warm and dry before use.","key_facts":[{"label":"Flame distance from roll","value":"50-150 mm (2-6 in)"},{"label":"Minimum side / end laps","value":"75 mm (3 in) / 150 mm (6 in)"},{"label":"Torch flame temperature","value":"Can exceed 1093 C (2000 F)"}],"regions":["Global"],"aliases":["torch-on","torch-down roofing","torched membrane","APP torch-on","torch-on felt","heat-welded bitumen"],"related":["modified-bitumen-roofing","hot-mopped-built-up-roof","fully-adhered-vs-mechanically-attached","roofing-torch","app-modified-bitumen","sbs-modified-bitumen","reinforced-bitumen-membrane","self-adhered-membrane","cold-applied-roofing"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 5.2.2 Application of Membrane","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-5-modified-bituminous-membranes/5-2-membrane-installation/5-2-2-application-of-membrane/","publisher":"Canadian Roofing Contractors Association"},{"title":"Canadian Roofing Reference Manual: 3.3.7 Cold Weather Material Application","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-3-roofing-preparation/3-3-cold-weather-conditions/3-3-7-material-application/","publisher":"Canadian Roofing Contractors Association"},{"title":"Who Put the Modified in Modified Bitumens?","url":"https://buildings.com/feature/article/10187932/who-put-the-modified-in-modified-bitumens","publisher":"Buildings"},{"title":"Low-slope roofing systems: built-up roofs and modified bitumen","url":"https://buildingenclosureonline.com/articles/82366-low-slope-roofing-systems-built-up-roofs-and-modified-bitumen","publisher":"Building Enclosure"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"BS 6229:2018 and flat roofing systems","url":"https://ikogroup.co.uk/?p=820","publisher":"IKO"}],"country":null},{"slug":"tornado-roof-damage","title":"Tornado Roof Damage","type":"article","summary":"How tornado winds strip roof coverings, lift decks and remove roof structures, and how the Enhanced Fujita scale uses roof damage to rate tornadoes.","body":"Tornadoes produce some of the strongest winds on Earth over a narrow path. Roofs are usually the first part of a house to fail, and damage to them is one of the main indicators used to estimate tornado wind speeds.\n\n## The Enhanced Fujita scale\n\nIn the United States, tornadoes are rated after the event on the Enhanced Fujita (EF) scale, which entered operational use on February 1, 2007. It uses 28 damage indicators, including one- and two-family homes, to estimate three-second gust speeds:\n\n- **EF0:** 105-137 km/h (65-85 mph). Some shingles blown off.\n- **EF1:** 138-177 km/h (86-110 mph). Much of the roof covering may be stripped.\n- **EF2:** 178-217 km/h (111-135 mph). Entire roof structures may be removed.\n- **EF3:** 218-266 km/h (136-165 mph). Well-built houses lose most walls.\n- **EF4:** 267-322 km/h (166-200 mph).\n- **EF5:** 323 km/h (201 mph) or more.\n\nOther countries use adapted versions of this scale or their own tornado intensity scales.\n\n## A typical failure sequence\n\nFEMA's Mitigation Assessment Team studied homes after the April 2011 outbreak in Alabama and the May 2011 Joplin, Missouri tornado. It described a progressive sequence:\n\n1. Loss of roof covering and siding, allowing water in.\n2. Breach of windows or garage doors, which pressurizes the interior.\n3. Uplift of roof decking, concentrated at corners, overhangs, hips and ridges.\n4. Loss of the roof structure where roof-to-wall connections fail.\n5. Collapse of walls that lose their top support.\n\nLoose shingles and decking also become windborne debris; in one Tuscaloosa building a shingle passed through gypsum board on both sides of an interior wall.\n\n## Lessons for roofs\n\nThe FEMA team found that decking often detached because nails missed framing, were spaced too far apart, or were undersized, and that roof-to-wall connections were the weak link most often responsible for roof loss. Metal connectors outperformed toenails when installed correctly.\n\nBecause most tornadoes are rated EF0 to EF2, engineers argue that wind-resistant details already used on hurricane coasts (ring-shank deck nails, connectors at every rafter, stronger garage doors) can prevent much tornado damage inland. Homes cannot practically be designed to resist the direct hit of a violent EF4 or EF5 tornado, which is why storm shelters and safe rooms are recommended for life safety.","key_facts":[{"label":"Rating scale (US)","value":"Enhanced Fujita, in use since Feb 1, 2007"},{"label":"EF0","value":"105-137 km/h (65-85 mph)"},{"label":"EF2","value":"178-217 km/h (111-135 mph)"},{"label":"Most common weak link (FEMA 2011)","value":"Roof-to-wall connection"}],"regions":["North America","Global"],"aliases":["tornado damage to roofs","twister roof damage"],"related":["roof-to-wall-connection","hurricane-tie","wind-uplift","hurricane-roof-damage","roof-wind-pressure-zones"],"sources":[{"title":"Enhanced Fujita scale","url":"https://en.wikipedia.org/wiki/Enhanced_Fujita_scale","publisher":"Wikipedia"},{"title":"Tornado Outbreak of 2011 Mitigation Assessment Team Report, Chapter 4 (FEMA P-908)","url":"https://webarchive.library.unt.edu/web/20161127152300/https://www.fema.gov/media-library-data/20130726-1827-25045-9156/tornado_mat_chapter4_508.pdf","publisher":"FEMA (archived by UNT Libraries)"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"toronto-green-roof-bylaw","title":"Toronto Green Roof Bylaw","type":"standard","summary":"A 2009 City of Toronto bylaw requiring green roofs on many new large buildings, with coverage that rises with building size.","body":"The Toronto Green Roof Bylaw is a municipal law adopted by Toronto City Council on May 25-26, 2009. It requires green roofs on many new developments above a size threshold. The bylaw is part of Chapter 492 of the Toronto Municipal Code, which also contains the Toronto Green Roof Construction Standard.\n\n## Who it applies to\n\n- **Residential, commercial and institutional development** with a gross floor area of 2,000 m² (about 21,500 sq ft) or more. Residential buildings under six storeys or 20 m (about 66 ft) in height are exempt.\n- **Industrial buildings** (new buildings or additions) with a gross floor area of 2,000 m² or more.\n\n## Required coverage\n\nFor residential, commercial and institutional buildings, the required share of \"available roof space\" rises with gross floor area:\n\n- 2,000-4,999 m²: 20 percent\n- 5,000-9,999 m²: 30 percent\n- 10,000-14,999 m²: 40 percent\n- 15,000-19,999 m²: 50 percent\n- 20,000 m² or more: 60 percent\n\nIndustrial buildings may either green the lesser of 10 percent of available roof space or 2,000 m², or use cool roofing materials on all available roof space and meet stormwater performance measures.\n\n## Cash in lieu\n\nWith the Chief Planner's approval, an applicant can provide less green roof than required by paying $200 per square metre of shortfall. These payments go to the City's Eco-Roof Incentive Program.\n\n## Construction Standard\n\nAll green roofs in Toronto must meet the Toronto Green Roof Construction Standard, which covers structural loads, fire safety, waterproofing, drainage, plant selection, irrigation and maintenance.\n\n## Significance\n\nThe bylaw is frequently cited as a model by other cities. It combines a size-based mandate, a cool roof alternative for industrial buildings, a payment option, and incentives for retrofits.","key_facts":[{"label":"Adopted","value":"May 25-26, 2009"},{"label":"Threshold","value":"2,000 m² gross floor area"},{"label":"Coverage range","value":"20% to 60% of available roof space"},{"label":"Cash in lieu","value":"$200 per m² of shortfall"},{"label":"Code location","value":"Toronto Municipal Code Chapter 492"}],"regions":["North America"],"aliases":["Toronto green roof by-law","Toronto Green Roof Construction Standard","Eco-Roof Incentive Program"],"related":["green-roof","cool-roof","copenhagen-green-roof-policy","basel-green-roof-policy"],"sources":[{"title":"Green Roof Bylaw","url":"https://www.toronto.ca/city-government/planning-development/official-plan-guidelines/green-roofs/green-roof-bylaw/","publisher":"City of Toronto"},{"title":"Toronto Municipal Code Chapter 492, Green Roofs","url":"https://www.toronto.ca/legdocs/municode/1184_492.pdf","publisher":"City of Toronto"},{"title":"Green roof","url":"https://en.wikipedia.org/wiki/Green_roof","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"torvtak","title":"Torvtak (Scandinavian Turf Roof)","type":"article","summary":"Traditional Norwegian and Scandinavian roof of birch bark covered with layers of turf, still used on cabins and heritage buildings.","body":"*Torvtak* is the Norwegian name for a turf or sod roof: a low-pitched timber roof covered first with a waterproof layer and then with living turf. Turf roofs were the ordinary roof on rural houses across Norway and much of Scandinavia for centuries, and similar roofs were used in the Faroe Islands and Iceland. They are still built today on mountain cabins, holiday homes and heritage buildings.\n\n## Traditional build-up\n\nIn the traditional method, the turf itself is not the waterproofing. That job is done by birch bark:\n\n- Sheets of birch bark are laid on gently sloping roof boards, inner side up, overlapping like shingles from the eaves to the ridge. Six layers were considered enough, and up to 16 have been recorded on high-quality roofs.\n- The lowest layers project about 8 cm (3 in) beyond the eaves and curve down to form a drip.\n- Turf pieces about 30 cm (12 in) square and 7.5 cm (3 in) thick are laid in two layers, the first grass-side down and the second grass-side up.\n- A timber log or board at the eaves, held by wooden hooks, stops the turf from sliding.\n\nA total turf thickness of about 15 cm (6 in) is enough to survive a dry summer. A finished roof weighs roughly 250 kg/m² (about 51 lb/ft²), and with winter snow the load can reach 400-500 kg/m² (82-102 lb/ft²). That weight helped compress log walls and made them more draught-proof.\n\n## History\n\nBirch bark and turf have probably covered Scandinavian roofs since prehistory. In the Viking period and Middle Ages most houses had turf roofs, while churches and other steep buildings used boards, wooden shingles or lead. Turf remained almost universal in rural areas until the early 18th century. In the 19th century clay tiles, and later corrugated iron, replaced it in most places except remote inland valleys.\n\nNational romanticism and the open-air museum movement helped save the craft, and demand for mountain cabins kept it alive.\n\n## Modern turf roofs\n\nContemporary turf roofs usually replace birch bark with a bituminous or synthetic waterproof membrane and a dimpled drainage layer, with turf or sedum above. They are a close relative of the modern extensive green roof. Typical service life for a traditional roof was about 30 years in most places, with periodic repairs.","key_facts":[{"label":"Waterproof layer (traditional)","value":"Birch bark, 6-16 layers"},{"label":"Turf thickness","value":"About 15 cm (6 in)"},{"label":"Roof weight","value":"About 250 kg/m² (51 lb/ft²), more with snow"},{"label":"Traditional lifespan","value":"About 30 years"},{"label":"Region","value":"Norway, Sweden, Faroe Islands, Iceland"}],"regions":["Europe","Arctic"],"aliases":["Sod roof","Turf roof","Grass roof","Torvtak"],"related":["green-roof","icelandic-turf-house","roofing-in-scandinavia"],"sources":[{"title":"Sod roof","url":"https://en.wikipedia.org/wiki/Sod_roof","publisher":"Wikipedia"},{"title":"Green roofs, turf roofs or torvtak in Norway","url":"https://salvoweb.com/salvonews/16721-green-roofs-turf-roofs-or-torvtak-in-norway","publisher":"SalvoWEB"}],"company":null,"category":"world-roofing","country":null},{"slug":"tpo-roofing","title":"TPO Roofing","category":"low-slope-systems","type":"article","summary":"Thermoplastic polyolefin single-ply membrane, usually white and scrim-reinforced, joined by hot-air welding; the most widely used US low-slope membrane.","body":"TPO (thermoplastic polyolefin) is a single-ply roofing membrane based on polypropylene blended with ethylene-propylene rubber. It is a thermoplastic, so its seams are fused with hot air. TPO contains no chlorine and needs no liquid plasticisers, which distinguishes it from PVC.\n\n## History\n\nTPO compounds were available in the 1980s, and the first TPO roofing sheets appeared in 1989. Early non-reinforced sheets had been replaced by fabric-reinforced versions by 1993. TPO sales grew quickly in the 2000s; one estimate says US TPO sales quadrupled those of other flat roofing materials between 2007 and 2012, and it was the most popular commercial low-slope covering in the US by about 2016.\n\n## Product standard\n\nThe US product standard is ASTM D6878, first published in 2003 using 45-mil sheets as its basis. Revisions in 2011 raised the minimum thickness of the layer over the scrim from 12 mils to 15 mils (0.30 to 0.38 mm) and lengthened heat ageing before testing from 28 to 224 days at 116 C (240 F). The 2013 edition required the weathering-side coating over the scrim to be at least 30% of nominal thickness. NRCA has advised designers to specify a minimum 60-mil sheet.\n\n## Sheets\n\nCommon thicknesses are 45 mil (1.1 mm) and 60 mil (1.5 mm), with 80 mil (2.0 mm) and thicker for greater puncture resistance. Sheets up to about 3.7 m (12 ft) wide reduce field seams. White is standard; grey, tan and black are also made. Fleece-backed versions are used for adhered and recover work.\n\n## Installation\n\nTPO is most often mechanically fastened in the seams. It can also be fully adhered, induction welded or, less often, ballasted (ballast hides the reflective surface). Seams are welded with automatic or hand-held hot-air welders. Known workmanship risks include \"cold\" welds at start-stop points and T-joints, scorching, and difficulty re-welding sheets that have weathered.\n\n## Performance notes\n\nSources report that TPO is stiffer than some membranes, changes colour and texture with age, and has a shorter field history than EPDM, PVC or BUR. Laboratory ageing temperatures are far above typical rooftop temperatures; white membrane surfaces seldom exceed about 49-71 C (120-160 F).","key_facts":[{"label":"First roofing sheets","value":"1989"},{"label":"US standard","value":"ASTM D6878 (first published 2003)"},{"label":"Common thickness","value":"45, 60, 80 mil (1.1, 1.5, 2.0 mm)"},{"label":"Seaming","value":"Hot-air welding"},{"label":"Min. thickness over scrim (D6878-11)","value":"15 mil (0.38 mm)"}],"regions":["North America","Global"],"aliases":["thermoplastic polyolefin","TPO membrane","FPO"],"related":["single-ply-roofing","pvc-roofing","hot-air-welding","mechanically-attached-roof-system","induction-welding-roofing","cool-roof"],"company":null,"sources":[{"title":"Thermoplastic Polyolefin (TPO) Roofing Systems","url":"https://buildings.com/articles/35297/thermoplastic-polyolefin-tpo-roofing-systems","publisher":"Buildings"},{"title":"Tech Today: ASTM D6878 revisions (2011)","url":"https://www.professionalroofing.net/articles/article/1983","publisher":"Professional Roofing / NRCA"},{"title":"TPOs face a changing landscape (2017)","url":"https://professionalroofing.net/articles/article/4063","publisher":"Professional Roofing / NRCA"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"},{"title":"Cool roof","url":"https://en.wikipedia.org/wiki/Cool_roof","publisher":"Wikipedia"}],"country":null},{"slug":"traditional-thai-house","title":"Traditional Thai House (Ruean Thai)","category":"world-roofing","type":"article","summary":"The raised timber or bamboo house of Thailand, with a steep gable roof and long eaves, built in distinct central, northern, northeastern and southern forms.","body":"The traditional Thai house (*ruean thai*) is a timber or bamboo house raised on posts under a steep roof with long eaves. Its form varies by region, but nearly all versions share a shaded underfloor space, a veranda and a roof designed to shed monsoon rain and release heat.\n\n## Raised floors\n\nTraditional houses are generally raised at least 2 m (6.5 ft) above the ground, mainly because many villages lie beside rivers and canals that flood in the rainy season. The underfloor space (*tai thun*) is used for storage, crafts, resting in the heat of the day and sometimes livestock. Ayutthaya-period accounts record common houses raised about 3-4 ft (0.9-1.2 m). Northern houses stand lower than central ones, and southern posts rest on stone or cement bases rather than being sunk into the ground.\n\n## Roofs by region\n\n- **Central plains:** a high gable with a curved ridge and long eaves. The verges carry wooden boards with distinctive ends, the *ngao* and *hang pla*, and the *panlom* windbreak board.\n- **North (Lanna):** lower, thicker roofs with long eaves. The gable peak may carry a *kalae*, a carved V- or X-shaped crossed board, often on the houses of wealthy families or community leaders. Coverings are terracotta tiles or wooden tiles (*pan kled*); some houses use clay tiles laid in a fish-scale pattern. The oldest northern type had roofs of woven grass over bamboo walls tied with rope.\n- **Northeast (Isan):** gentler slopes, often without eaves; temporary and semi-permanent houses use baked clay tiles or thatch, sometimes with sunburst carving.\n- **Korat:** Mon-influenced houses with acute gables sharper than 50 degrees.\n- **South:** roofs built to withstand frequent storms. Forms include the gable, the five-ridged hipped *lima* or *panya* roof, influenced by Malay and Indonesian design and common in Pattani, and the *Manila* or *blanor* roof, a gable top over a hipped lower section, used by many Muslim households.\n\n## Materials\n\nTemporary houses use grass, bamboo or palm-leaf thatch, which releases heat quickly. Permanent houses use terracotta tiles in several shapes: *kap kluay* (half-cylindrical, \"banana trunk\"), *kled tao* (square, \"turtle shell\") and *hang yiao* (upturned corners, \"falcon tail\"). Construction is either *khrueang sab*, nail-free timber joinery that allows a house to be dismantled and moved, or *khrueang phook*, tied bamboo.\n\n## Cluster houses\n\nLarger households built a *ruean mu*, several gabled units on a shared raised veranda (*chaan*), each with its own roof.","key_facts":[{"label":"Floor height","value":"Generally at least 2 m (6.5 ft)"},{"label":"Roof coverings","value":"Thatch; terracotta tiles (kap kluay, kled tao, hang yiao); wooden tiles (pan kled)"},{"label":"Steepest gables","value":"Korat houses, over 50 degrees"},{"label":"Southern roof forms","value":"Lima/panya hip roof; Manila/blanor hip-and-gable"}],"regions":["Southeast Asia"],"aliases":["ruean thai","Thai stilt house","kalae house"],"related":["roofing-in-thailand","thai-temple-roof","clay-roof-tile","palm-thatch","bamboo-roofing","gable-roof","hip-roof"],"company":null,"sources":[{"title":"Ruean Thai: Understanding Traditional Thai Houses","url":"https://thailandfoundation.or.th/?p=530402","publisher":"Thailand Foundation"},{"title":"Traditional Thai house","url":"https://en.wikipedia.org/wiki/Traditional_Thai_house","publisher":"Wikipedia"},{"title":"Architecture of Thailand","url":"https://en.wikipedia.org/wiki/Architecture_of_Thailand","publisher":"Wikipedia"}],"country":null},{"slug":"tremco-roofing","title":"Tremco Roofing","category":"manufacturers","type":"company","summary":"Tremco Roofing is the commercial roofing and building maintenance business of Tremco CPG, part of RPM International, based in Beachwood, Ohio.","body":"Tremco Roofing is a North American supplier of commercial roofing systems and roof maintenance services. It operates as part of Tremco CPG Inc., a business of RPM International, the Medina, Ohio-based specialty coatings group. Tremco Roofing's offices are in Beachwood, Ohio.\n\n## Parent company\n\nRPM International was founded in May 1947 by Frank C. Sullivan as Republic Powdered Metals. Its first product was a heavy-duty aluminium roof coating called Alumanation, giving the group roots in roofing from the start. RPM became a holding company in 1971 and today owns many coatings, sealants and building-products brands.\n\n## Products\n\nTremco Roofing's range covers most low-slope roofing technologies:\n\n- Hot and cold built-up roofing (BUR).\n- Modified-bitumen membranes.\n- Single-ply membranes.\n- Liquid-applied roof coatings and restoration systems.\n- Metal roofs and walls and metal edge systems.\n- Mastics, primers, sealants, insulation, fasteners and underlayments.\n- Rooftop safety equipment.\n\n## Services\n\nUnusually among manufacturers, Tremco provides direct services to building owners, including roof assessment, a maintenance programme branded RoofTec, general contracting and building asset management. It also runs its own fire test laboratory. Sister brands within the wider business include Dryvit wall systems and Nudura insulated concrete forms.\n\n## Government contracts\n\nIn 2013 RPM and Tremco paid more than USD 60 million to settle a US False Claims Act lawsuit relating to roofing contracts with government customers.\n\n## Built-up roofing\n\nBuilt-up roofing, one of Tremco's oldest product areas, uses several layers of reinforcing felts bonded with hot or cold-applied bitumen, finished with gravel or a coating.","key_facts":[{"label":"Parent","value":"RPM International (via Tremco CPG)"},{"label":"Office","value":"Beachwood, Ohio, US"},{"label":"Products","value":"BUR, modified bitumen, single-ply, coatings, metal"}],"regions":["North America","Europe"],"aliases":["Tremco","Tremco CPG"],"related":["built-up-roofing","modified-bitumen-roofing"],"company":{"headquarters":"Beachwood, Ohio, United States","website":"https://www.tremcoroofing.com","parent":"RPM International","known_for":["Built-up and modified-bitumen roofing","Roof restoration coatings","RoofTec maintenance services"]},"sources":[{"title":"Tremco Roofing","url":"https://www.tremcoroofing.com/","publisher":"Tremco CPG"},{"title":"RPM International","url":"https://en.wikipedia.org/wiki/RPM_International","publisher":"Wikipedia"}],"country":null},{"slug":"trulli-of-alberobello","title":"Trulli of Alberobello","type":"place","summary":"Dry-stone limestone houses in Puglia, Italy, capped by conical corbelled roofs of stone slabs; a UNESCO World Heritage property.","body":"The trulli of Alberobello are small houses in the Puglia region of southern Italy built without mortar from roughly worked local limestone and topped by distinctive conical stone roofs. The town holds the largest concentration of these buildings, and the ensemble is inscribed on the UNESCO World Heritage List under criteria (iii), (iv) and (v) as an outstanding example of a vernacular settlement that keeps much of its original form.\n\nThe stone used for a trullo usually came from the house site itself, dug out while forming the cistern below the floor, or from boulders and outcrops cleared from surrounding fields. That made the building method a direct expression of local geology and farming.\n\n## How the roof is built\n\nA trullo roof is a corbelled structure, not a true arch or vault. Each course of stone projects slightly inward over the course below until the opening closes at the top. The roof has two skins:\n\n- An inner dome of wedge-shaped stones, closed by a single capstone.\n- An outer cone of thin, overlapping limestone slabs known locally as *chianche* or *chiancarelle*, laid so that rainwater runs off.\n\nThe walls below are also dry-stone, built as two faces with a rubble core and finished with whitewash. Many cones carry a carved pinnacle at the apex, and some are painted with symbols in white.\n\n## Water management\n\nThe roofs are part of a rainwater system. Projecting eaves gather runoff and lead it through a channelled slab into a cistern beneath the house, which mattered in a karst landscape with little surface water.\n\n## History and protection\n\nAccording to the UNESCO listing, the oldest surviving structures date from as early as the mid-14th century, and the building of new trulli declined after feudal rule ended in 1797. Individual parts of the town gained Italian protection long before world heritage status: the Trullo Sovrano was declared a national monument in 1923, and the Rione Monti district followed in 1928. The protected property covers about 11 hectares (27 acres) in six parcels, including the Rione Monti and Rione Aia Piccola districts, with more than 1,500 trulli.\n\n## Maintenance today\n\nBecause the cone is made of loose-laid slabs, repairs involve resetting or replacing individual stones rather than applying a membrane. Conservation practice aims to keep the dry-stone technique, the local limestone and the whitewashed walls so that the townscape remains authentic.","key_facts":[{"label":"Location","value":"Alberobello, Puglia, Italy"},{"label":"Roof type","value":"Corbelled dry-stone cone, double skin"},{"label":"Outer covering","value":"Limestone slabs (chianche / chiancarelle)"},{"label":"Earliest structures","value":"Mid-14th century"},{"label":"Protected area","value":"About 11 ha (27 acres)"}],"regions":["Europe"],"aliases":["Trullo","Trulli","Chianche roof"],"related":["roofing-in-italy","rainwater-harvesting-roofs"],"sources":[{"title":"The Trulli of Alberobello","url":"https://whc.unesco.org/en/list/787","publisher":"UNESCO World Heritage Centre"},{"title":"I Trulli di Alberobello","url":"https://unesco.cultura.gov.it/en/projects/i-trulli-di-alberobello/","publisher":"Italian Ministry of Culture"}],"company":null,"category":"world-roofing","country":null},{"slug":"trustmark","title":"TrustMark","summary":"TrustMark is the UK Government Endorsed Quality Scheme for home improvement work, including roofing, with vetted registered businesses.","body":"TrustMark is the UK's Government Endorsed Quality Scheme for work that consumers choose to have carried out in or around their homes. Businesses registered with TrustMark have been vetted against required standards and commit to good customer service. Its website is trustmark.org.uk.\n\n## How it works\n\nBusinesses are vetted through scheme providers, such as trade associations and certification bodies, that check firms in specific trades. Businesses that pass are listed as TrustMark Registered Businesses for the trades they are approved for.\n\nRequirements generally cover:\n\n- technical competence in the trade;\n- trading practices and customer care;\n- financial and insurance arrangements;\n- complaint handling and access to dispute resolution.\n\n## Finding a tradesperson\n\nTrustMark's website has a **Find a tradesperson** search, with a guided option for people unsure what kind of trade they need and an advanced search. It advises consumers to check that a business is registered for the specific trade they need, since a firm may be approved for some trades and not others.\n\n## Relevance to roofing\n\nThe UK has no general legal licence for roofers. Instead, consumers rely on several signals of competence:\n\n- **TrustMark registration** for the roofing trade;\n- membership of trade associations such as the National Federation of Roofing Contractors (NFRC) or the Confederation of Roofing Contractors (CORC);\n- registration in a **Competent Person Scheme**, which lets firms self-certify re-roofing work under the building regulations;\n- references, written quotations and insurance-backed warranties.\n\nTrustMark registration can also be a condition of some government-funded home energy-efficiency work, such as certain insulation measures, which may overlap with roofing projects.\n\n## Comparison\n\nOther countries handle trade quality differently. Many U.S. states and Australian states license contractors directly, while Germany requires a master craftsman qualification to run certain trade businesses.","key_facts":[{"label":"Status","value":"UK Government Endorsed Quality Scheme"},{"label":"Scope","value":"Work in or around the home"},{"label":"Consumer tool","value":"Find a tradesperson search"}],"regions":["Europe"],"aliases":["Trustmark"],"related":["how-to-find-a-licensed-roofer","national-federation-of-roofing-contractors","confederation-of-roofing-contractors"],"company":{"website":"https://www.trustmark.org.uk","known_for":["Government Endorsed Quality Scheme for home improvement"]},"sources":[{"title":"TrustMark home page","url":"https://www.trustmark.org.uk/","publisher":"TrustMark"},{"title":"About TrustMark","url":"https://www.trustmark.org.uk/about-us","publisher":"TrustMark"}],"category":"organizations","type":"organization","country":null},{"slug":"tukul","title":"Tukul","category":"world-roofing","type":"term","summary":"Round hut of mud, poles and grass with a conical thatched roof, typical of South Sudan, Sudan, Ethiopia and Eritrea.","body":"A tukul (also tukal or tukl) is a round dwelling with a conical thatched roof, found across South Sudan and in neighbouring Sudan, Ethiopia and Eritrea. It belongs to the wider family of African round huts, alongside the Southern African rondavel.\n\n## Construction\n\nEncyclopaedia Britannica describes the tukul of South Sudan as a round hut made of mud, grass, millet stalks and wooden poles, with a thatched conical roof. Walls are typically of mud on a framework of poles, sometimes mixed with stones, grass and cow manure. The roof is a cone of poles or sticks covered with grass.\n\nA record of the method survives in photographs taken by the anthropologist E. E. Evans-Pritchard among the Zande at Yambio (now in South Sudan) between 1927 and 1930: the roof framework was laid on the ground while thatch of *bingba* grass (*Imperata cylindrica*) was worked onto it.\n\n## Performance\n\nThe steep thatched cone sheds the heavy rain of the southern savanna, which makes sloping grass roofs necessary there. Mud walls are less durable: a new mud hut is said to last about one to two years, depending on rainfall and erosion, before major repair. Huts are often loosely grouped around open spaces, which helps ventilation in hot weather.\n\n## Names\n\n- **Tukul**: name used in South Sudan and Eritrea; also widely used in English for Ethiopian round huts.\n- **Agudo**: name given for the round hut in Eritrea.\n- **Godjo**: listed for Ethiopia.\n- **Hotnhial**: listed for South Sudan.\n\n## Today\n\nThatch remains the most common roof in South Sudan: in a 2010 household survey sample, thatch or palm leaf was recorded for about 60% of households (unweighted). In Ethiopia, thatch has been giving way to corrugated iron; a 2011-2012 rural survey sample recorded thatch and corrugated iron in roughly equal numbers of households (see Roofing in Ethiopia).","key_facts":[{"label":"Plan","value":"Round"},{"label":"Roof","value":"Conical grass thatch on poles"},{"label":"Walls","value":"Mud, poles, stalks"},{"label":"Region","value":"South Sudan, Sudan, Ethiopia, Eritrea"}],"regions":["Africa"],"aliases":["tukl","tukal","toukoul","agudo"],"related":["roofing-in-south-sudan","roofing-in-ethiopia","roofing-in-sudan","roofing-in-eritrea","thatch","conical-roof","rondavel","roofing-in-east-africa"],"company":null,"sources":[{"title":"Tukul","url":"https://www.britannica.com/topic/tukul","publisher":"Encyclopaedia Britannica"},{"title":"Zande hut roof construction (1998.341.668.2)","url":"https://southernsudan.prm.ox.ac.uk/details/1998.341.668.2/index.html","publisher":"Pitt Rivers Museum, University of Oxford"},{"title":"Moru tukuls according to traditional architecture","url":"https://africanmission.org/blog/moru-tukuls-according-to-traditional-architecture/","publisher":"African Mission"},{"title":"African round hut","url":"https://en.wikipedia.org/wiki/African_round_hut","publisher":"Wikipedia"},{"title":"South Sudan Household Health Survey 2010: main material of the roof (HC4)","url":"https://microdata.worldbank.org/catalog/2588/variable/F3/V355?name=HC4","publisher":"World Bank Microdata Library"}],"country":null},{"slug":"tunduk-and-shangyrak","title":"Tunduk and Shangyrak (Yurt Crown)","category":"world-roofing","type":"term","summary":"The tunduk (Kyrgyz) or shangyrak (Kazakh) is the wooden crown ring at the top of a Central Asian yurt roof, and a national symbol of both countries.","body":"The **tunduk** (Kyrgyz *түндүк*, *tyndyk*) and **shangyrak** (Kazakh *шаңырақ*, *shangyraq*) are the names for the same thing: the wooden crown ring at the top of the Central Asian yurt. All the roof poles lean against it, it lets light in and smoke out, and it closes the dome of felt that forms the roof. Because the yurt was the home of the nomadic Kyrgyz and Kazakhs for centuries, the crown has become a symbol of home and family, and today appears on the flag of Kyrgyzstan and the state emblem of Kazakhstan.\n\n## Place in the roof\n\nThe Kazakh yurt, *kiyiz üy* (\"felt house\"), has three main timber parts:\n\n- **Kerege**: the folding lattice wall, set up in a circle.\n- **Uyk**: the roof poles. In Kazakh and Kyrgyz yurts, as in other Central Asian yurts, they are bent, giving the roof a rounded profile. This differs from the Mongolian *ger*, whose poles are straight and whose crown is usually propped on one or more central columns (see *ger roof*).\n- **Shangyrak / tunduk**: the wooden crown, into which the upper ends of the poles are fixed.\n\nThe frame is covered with felt made from the wool of the herders' own sheep and tied together with ropes and bands.\n\nThe yurt as a type is very old. The earliest written description of a yurt-like dwelling is usually traced to Herodotus' account of the tents of the Scythians, nomads of the Black Sea and Central Asian steppe.\n\n## A family heirloom\n\nIn old Kazakh communities, the yurt itself was repaired or rebuilt many times, but the shangyrak was kept and passed from father to son. The smoke stains built up on it were taken as a sign of the age and standing of the family.\n\n## National symbol\n\n- **Kyrgyzstan**: the flag adopted on 3 March 1992 shows a red field with a yellow sun, at the centre of which is a tunduk seen from inside the yurt. In the redesign that took effect on 26 December 2023, the sun's 40 rays were straightened and the drawing of the tunduk's crossing bars was changed. The tunduk is said to represent the origin of life, home and the unity of time and space.\n- **Kazakhstan**: the state emblem adopted on 4 June 1992 is built around a shangyrak against a sky-blue field, with the uyk poles shown as rays and winged horses on either side. The shangyrak stands for the well-being of the family and for peace.\n\n## Heritage recognition\n\nIn 2014 UNESCO added the traditional knowledge and skills of making Kyrgyz and Kazakh yurts to its Representative List of the Intangible Cultural Heritage of Humanity; in 2025 the listing was extended to include the Karakalpak yurt of Uzbekistan. Men and apprentices make the wooden frame, including the crown, while women make the felt coverings and interior decoration.","key_facts":[{"label":"Kyrgyz name","value":"Tunduk (tyndyk)"},{"label":"Kazakh name","value":"Shangyrak (shanyrak)"},{"label":"Roof poles","value":"Bent uyk poles from wall to crown"},{"label":"National symbol","value":"Flag of Kyrgyzstan; emblem of Kazakhstan"},{"label":"UNESCO","value":"Yurt-making on Intangible Heritage list (2014; extended 2025)"}],"regions":["Central Asia"],"aliases":["tunduk","tyndyk","tündük","shangyrak","shanyrak","shañıraq","yurt crown","roof wheel","kiyiz uy roof"],"related":["ger-roof","roofing-in-kyrgyzstan","roofing-in-kazakhstan","roofing-in-uzbekistan","skylight","dome","conical-roof"],"company":null,"sources":[{"title":"Yurt","url":"https://en.wikipedia.org/wiki/Yurt","publisher":"Wikipedia"},{"title":"Flag of Kyrgyzstan","url":"https://en.wikipedia.org/wiki/Flag_of_Kyrgyzstan","publisher":"Wikipedia"},{"title":"Emblem of Kazakhstan","url":"https://en.wikipedia.org/wiki/Emblem_of_Kazakhstan","publisher":"Wikipedia"},{"title":"Traditional knowledge and skills in making Kyrgyz and Kazakh yurts (Turkic nomadic dwellings)","url":"https://ich.unesco.org/en/RL/traditional-knowledge-and-skills-in-making-kyrgyz-and-kazakh-yurts-turkic-nomadic-dwellings-00998","publisher":"UNESCO Intangible Cultural Heritage"}],"country":null},{"slug":"uk-building-regulations","title":"UK Building Regulations and Approved Documents (B, C, L)","summary":"In England, the Building Regulations are supported by Approved Documents; Parts B (fire), C (moisture) and L (energy) most affect roofs.","body":"In England, building work must comply with the **Building Regulations**, a set of legal functional requirements. The government publishes **Approved Documents** as statutory guidance on ways to meet them. Following an Approved Document is not mandatory, but doing so is normally accepted as evidence of compliance. Wales, Scotland and Northern Ireland have their own regulations and guidance with similar subjects but different detail.\n\nThe Approved Documents are labelled by Part, from A (Structure) through T (Toilet accommodation), plus guidance on Regulation 7 (materials and workmanship). Three are especially important for roofs.\n\n## Approved Document B – Fire safety\n\nPart B deals with fire safety, including the external fire performance of roofs. Roof coverings near boundaries and on certain buildings must meet minimum classes, expressed using the European classification of [EN 13501-5](/en-13501-5) (for example BROOF(t4)). It also covers fire spread at junctions between roofs and compartment walls, and the materials used in and on roofs of taller buildings. Approved Document B has been revised repeatedly since the Grenfell Tower fire in 2017; the government's collection page lists an update in September 2026.\n\n## Approved Document C – Site preparation and resistance to contaminants and moisture\n\nPart C requires roofs to resist the passage of moisture from outside and to avoid harmful condensation. It points to British Standards for detailed guidance, notably [BS 5534](/bs-5534) for slating and tiling, and to British Standards on moisture management. The current edition dates from 2013 with later amendments.\n\n## Approved Document L – Conservation of fuel and power\n\nPart L sets energy-efficiency standards, including maximum U-values for roofs in new buildings and for work on existing roofs. Replacing a roof covering on an existing dwelling is often \"renovation of a thermal element,\" which can trigger a requirement to upgrade insulation where technically and economically feasible. The collection page lists the current version as updated in February 2023.\n\n## Other relevant parts\n\n- **Part A** – structural safety, including wind and snow loads, using Eurocodes such as [EN 1991-1-4](/en-1991-1-4) with UK National Annexes.\n- **Part F** – ventilation.\n- **Part K** – protection from falling, relevant to roof access.\n- **Regulation 7** – materials and workmanship.\n\n## Building control\n\nCompliance is checked by local authority building control or registered building control approvers. Competent person schemes allow registered roofing contractors to self-certify certain work, such as re-roofing, in England and Wales.","key_facts":[{"label":"Jurisdiction","value":"England (separate regimes in Wales, Scotland, Northern Ireland)"},{"label":"Fire","value":"Approved Document B"},{"label":"Moisture","value":"Approved Document C"},{"label":"Energy","value":"Approved Document L"},{"label":"Status of guidance","value":"Statutory guidance, not mandatory"}],"regions":["Europe"],"aliases":["Approved Document B","Approved Document C","Approved Document L","Part L","Building Regulations 2010"],"related":["bs-5534","en-13501-5","en-1991-1-4","roof-insulation","breeam"],"sources":[{"title":"Approved documents","url":"https://www.gov.uk/government/collections/approved-documents","publisher":"UK Government (MHCLG)"},{"title":"Approved Documents","url":"https://www.planningportal.co.uk/applications/building-control-applications/building-control/approved-documents","publisher":"Planning Portal"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"ul-1897","title":"UL 1897","summary":"UL 1897 is a static-pressure test that measures how much wind uplift a roof covering system and its attachment can resist, usually run until failure.","body":"UL 1897, *Standard for Safety, Uplift Tests for Roof Covering Systems*, is a North American test method maintained by UL Standards & Engagement. It evaluates how well a roof covering and its means of attachment, such as fasteners, plates, clips or adhesive, resist wind uplift.\n\n## Method\n\nA roof covering system is installed over a test frame and placed in a chamber. Static uplift pressure is raised in steps and held at each step while any vertical movement is recorded. Test laboratory Intertek describes the increments as no more than 15 psf (0.72 kPa), each held for at least 1 minute. The test is normally run until something fails, for example loss of adhesion, fastener pull-out, seam disengagement or metal fatigue, so the result is a measured ultimate pressure rather than a pass/fail class.\n\n## What it covers\n\nUL 1897 is used for a wide range of products, including:\n\n- single-ply membranes (mechanically fastened or adhered)\n- built-up and modified bitumen systems\n- standing seam metal roofs\n- metal and composite shingles\n\n## Relationship to other wind tests\n\nThe International Building Code lists UL 1897 alongside [UL 580](/ul-580) and [FM 4474](/fm-4474) as acceptable methods for membrane roof systems. UL 580 gives fixed classes up to Class 90; UL 1897 is often used where design pressures exceed what a Class 90 rating demonstrates, or where an engineer needs the actual failure pressure to apply a safety factor.\n\nBecause the test applies static pressure, it does not reproduce the gusting and cycling of real wind. Dynamic tests such as [CSA A123.21](/csa-a123-21) in Canada were developed partly for that reason, especially for mechanically attached membranes that flutter.\n\n## Using results\n\nA UL 1897 report states the maximum pressure the specific assembly withstood. Designers usually divide this by a safety factor to obtain an allowable design pressure, then compare it with site-specific wind loads calculated under ASCE 7 or the applicable code. The result only applies to the exact configuration tested.","key_facts":[{"label":"Publisher","value":"UL Standards & Engagement"},{"label":"Load type","value":"Static uplift pressure in steps"},{"label":"Pressure increments","value":"Up to 15 psf (0.72 kPa), held at least 1 minute"},{"label":"Result","value":"Pressure at failure"},{"label":"Applies to","value":"Membranes, BUR, mod bit, metal panels, shingles"}],"regions":["North America"],"aliases":["UL1897","UL 1897 uplift test"],"related":["ul-580","fm-4474","csa-a123-21","wind-uplift","single-ply-roofing"],"sources":[{"title":"UL 1897: Standard for Safety, Uplift Tests for Roof Covering Systems","url":"https://www.intertek.com/building/standards/ul-1897/","publisher":"Intertek"},{"title":"An uplifting experience: certifying roof deck constructions for wind resistance","url":"https://code-authorities.ul.com/about/blog/certifying-roof-deck-constructions-for-wind-resistance/","publisher":"UL Solutions"},{"title":"UL 1897 Uplift Tests for Roof Covering Systems","url":"https://standards.globalspec.com/std/14544137/ul-1897","publisher":"GlobalSpec"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"ul-2218","title":"UL 2218","summary":"UL 2218 is a North American impact test that drops steel balls on roof coverings to rate their hail resistance from Class 1 to Class 4.","body":"UL 2218, *Standard for Impact Resistance of Prepared Roof Covering Materials*, is the most widely used hail-resistance rating for steep-slope roofing in the United States and Canada. It was created in 1996 through work involving insurers, the Institute for Business & Home Safety (now IBHS) and Underwriters Laboratories. The \"Class 4\" label seen on shingles, metal panels and other roof products usually refers to this standard.\n\n## How the test works\n\nRoofing is installed on a test deck according to the manufacturer's instructions. A solid steel ball is dropped from a set height, twice on the same spot, at several locations chosen as the most vulnerable (for example near edges and over joints). The size of the ball and the drop height increase with each class:\n\n| Class | Steel ball diameter | Drop height |\n|---|---|---|\n| 1 | 1.25 in (31.8 mm) | 12 ft (3.7 m) |\n| 2 | 1.50 in (38.1 mm) | 15 ft (4.6 m) |\n| 3 | 1.75 in (44.5 mm) | 17 ft (5.2 m) |\n| 4 | 2.00 in (50.8 mm) | 20 ft (6.1 m) |\n\nAfter impact the specimens are examined on the face, the back and the underlying layers. For shingles, samples are bent over a mandrel so that hidden cracks open up. A product fails if there is tearing, fracturing, cracking or rupture through the material. Purely cosmetic marks such as granule loss or shallow dents are not counted as failure.\n\n## Use in insurance\n\nMany US insurers and some state insurance regulators offer premium credits for roofs rated Class 4 (and sometimes lower classes). In Texas, for example, the Texas Windstorm Insurance Association requires products to be labelled with the impact class and laboratory mark, and the installing contractor must complete a state form. See [impact-resistant roof insurance discounts](/impact-resistant-roof-insurance-discounts).\n\n## Criticisms and alternatives\n\nBecause a steel ball delivers a hard, concentrated blow, it does not behave exactly like real hail, which can shatter or flatten. Brittle materials like tile and slate may be penalized, and soft materials may pass while still showing heavy cosmetic damage. For rigid roofing, many specifiers use [FM 4473](/fm-4473), which fires ice balls. IBHS also runs its own hail ratings for asphalt shingles using laboratory-made hailstones, which it describes as more demanding than UL 2218.\n\n## Cosmetic damage\n\nA Class 4 roof can still dent. Some insurance policies in hail-prone states exclude or limit coverage for cosmetic damage to metal roofs, so homeowners are advised to read policy wording alongside the product rating.","key_facts":[{"label":"Full title","value":"Impact Resistance of Prepared Roof Covering Materials"},{"label":"Introduced","value":"1996"},{"label":"Projectile","value":"Steel ball, 1.25–2 in (32–51 mm)"},{"label":"Drop heights","value":"12–20 ft (3.7–6.1 m)"},{"label":"Classes","value":"1 (lowest) to 4 (highest)"}],"regions":["North America"],"aliases":["UL2218","Class 4 impact rating","Class 4 shingles","hail rating"],"related":["fm-4473","ibhs-fortified-roof","impact-resistant-roof-insurance-discounts","hail-damage","asphalt-shingle"],"sources":[{"title":"A closer look at roof impact testing","url":"https://lsc-pagepro.mydigitalpublication.com/article/A+closer+look+at+roof+impact+testing/4287233/749783/article.html","publisher":"Asphalt Magazine"},{"title":"Tech Today: impact resistance testing","url":"https://professionalroofing.net/articles/article/1363","publisher":"Professional Roofing (NRCA)"},{"title":"Roof hail impact resistance","url":"https://roofobservations.com/roof-hail-impact-resistance/","publisher":"Roof Observations"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"ul-580","title":"UL 580","summary":"UL 580 is a North American test standard that rates roof assemblies for wind uplift resistance using static and oscillating air pressure, in Classes 15 to 90.","body":"UL 580, *Standard for Tests for Uplift Resistance of Roof Assemblies*, is a test standard developed by UL (now maintained by UL Standards & Engagement). It measures how well a complete roof assembly, including the deck, its attachment to the structure and the roof covering, resists wind uplift. It is one of the oldest wind uplift tests in North American use and is widely cited for metal roof panels.\n\n## How the test works\n\nA sample roof assembly about 10 by 10 ft (3 by 3 m) is built into a chamber. Air pressure is applied beneath and suction above to simulate wind. Each class consists of a sequence of static pressure holds and a period of oscillating pressure. According to UL's code authority materials, static pressures are held for 5 minutes and oscillating pressures cycle at a 10-second frequency for 60 minutes.\n\n| Class | Nominal static | Oscillating range | Maximum static |\n|---|---|---|---|\n| 15 | 15 psf (0.72 kPa) | 11–21 psf | 23 psf (1.10 kPa) |\n| 30 | 30 psf (1.44 kPa) | 22–42 psf | 45 psf (2.15 kPa) |\n| 60 | 60 psf (2.87 kPa) | 44–83 psf | 75 psf (3.59 kPa) |\n| 90 | 90 psf (4.31 kPa) | 66–90 psf | 105 psf (5.03 kPa) |\n\nClasses are cumulative. A Class 90 assembly has passed the Class 30, 60 and 90 sequences in turn without failing.\n\n## Code use\n\nThe International Building Code (Section 1504) requires that through-fastened and standing seam metal panel roof systems be tested to UL 580, and lists UL 580 among acceptable methods for membrane roofs along with [UL 1897](/ul-1897) and [FM 4474](/fm-4474). Many US product approvals, including Florida Product Approval files, cite UL 580 results.\n\n## Limits\n\nA UL 580 class describes the tested assembly only: the specific panel, gauge, clip, fastener, spacing and deck. Changing any of these can change performance. The class is also not a design wind speed. The design uplift pressure at a given site must be calculated (for example under ASCE 7) and compared with the tested capacity, with appropriate safety factors. For pressures beyond Class 90, designers often use [UL 1897](/ul-1897), which runs to failure and reports an ultimate pressure.","key_facts":[{"label":"Publisher","value":"UL Standards & Engagement"},{"label":"Sample size","value":"About 10 x 10 ft (3 x 3 m)"},{"label":"Classes","value":"15, 30, 60, 90"},{"label":"Load type","value":"Static and oscillating pressure"},{"label":"Code reference","value":"IBC Section 1504"}],"regions":["North America"],"aliases":["UL580","UL 580 Class 90","Class 90 wind rating"],"related":["ul-1897","fm-4474","wind-uplift","standing-seam-metal-roof","international-building-code"],"sources":[{"title":"An uplifting experience: certifying roof deck constructions for wind resistance","url":"https://code-authorities.ul.com/about/blog/certifying-roof-deck-constructions-for-wind-resistance/","publisher":"UL Solutions"},{"title":"UL 580: Safety Testing for Uplift Resistance of Roof Assemblies","url":"https://intertek.com/building/standards/ul-580","publisher":"Intertek"}],"category":"standards-codes","type":"standard","company":null,"country":null},{"slug":"uma-lulik","title":"Uma Lulik","category":"world-roofing","type":"article","summary":"The sacred clan house of Timor-Leste, a raised timber house with a tall, steep roof of thatch or palm leaves, rebuilt widely since independence.","body":"The *uma lulik* is the sacred clan house of Timor-Leste. In Tetum, the national language, *uma* means house and *lulik* means sacred. Each house belongs to a lineage, holds the clan's heirlooms and acts as the spiritual and social centre of the community. Its most visible feature is a tall, steep thatched roof over a raised timber platform.\n\n## Construction\n\nRecent descriptions record the following traditional features:\n\n- **Frame:** local hardwood posts and beams, bamboo and timber planks.\n- **Joints:** members tied with rope made from native palms rather than fixed with metal nails.\n- **Roof:** high-pitched and covered in natural thatch or coconut palm leaves.\n- **Platform:** the house is raised, and the shaded space underneath serves as a public meeting place.\n\nIn Lautem municipality, at the eastern end of the island, the Fuiloro community builds square houses up to about 9 m (30 ft) high, where the roof makes up most of the building's height. Forms differ between Timor's many ethno-linguistic groups.\n\n## Role\n\nThe house stores *sasan lulik*, sacred heirlooms guarded by senior elders. Ceremonies such as *nahe biti* (\"spreading the mat\"), in which elders settle disputes, are associated with the clan house.\n\n## Destruction and rebuilding\n\nMany uma lulik were destroyed during the Indonesian occupation (1975-1999). Since independence there has been a sustained revival of custom that includes the phased reconstruction of origin houses. Research among the Fataluku people describes a delayed revival of their equivalent houses, with builders combining traditional forms and new methods as economic conditions improve. Rebuilt houses show recent innovations within traditional construction.\n\n## Context\n\nNationally, traditional palm-leaf, thatch or grass roofs covered 18.9% of houses in the 2015 census, and about a quarter of rural houses. The uma lulik is therefore one of the main places where thatching skills remain in active use in Timor-Leste.","key_facts":[{"label":"Meaning","value":"Sacred house (Tetum)"},{"label":"Roof","value":"High-pitched thatch or coconut leaf"},{"label":"Height","value":"Up to about 9 m (30 ft) for Fuiloro houses, Lautem"},{"label":"Fixings","value":"Palm-fibre rope, traditionally no nails"}],"regions":["Southeast Asia"],"aliases":["Timorese sacred house","sacred house Timor-Leste"],"related":["roofing-in-timor-leste","palm-thatch","thatch","tongkonan","rumah-gadang"],"company":null,"sources":[{"title":"Uma Lulik: the secret sacred houses of Timor-Leste","url":"https://seasia.co/2026/08/27/uma-lulik-the-secret-sacred-houses-of-timor-leste","publisher":"Seasia"},{"title":"Refashioning Fataluku origin houses (in Economic Diversity in Contemporary Timor-Leste, Leiden University Press, 2023)","url":"https://researchers.westernsydney.edu.au/en/publications/refashioning-fataluku-origin-houses/","publisher":"Western Sydney University"},{"title":"2015 Census thematic report: Housing characteristics and amenities","url":"https://inetl-ip.gov.tl/wp-content/uploads/2023/05/2015-Housing-characterics-thematic-report_consolidated.pdf","publisher":"General Directorate of Statistics, Timor-Leste / UNFPA"}],"country":null},{"slug":"underlayment-installation","title":"Underlayment Installation","category":"installation","type":"article","summary":"Underlayment installation is the laying of a secondary water-resistant sheet over the roof deck, lapped shingle-fashion, before the main roof covering.","body":"**Underlayment** (called **underlay** in the UK, Ireland, Australia and New Zealand) is a sheet laid over the deck or rafters beneath the main roof covering. It sheds water that gets past the covering, protects the deck during construction and, in some systems, adds wind resistance. Traditional products are asphalt-saturated felt; modern options include synthetic sheets, breathable membranes and self-adhered polymer-modified bitumen.\n\n## General method\n\n1. Start at the eaves and work upward, so each upper course laps over the one below.\n2. Lap horizontal edges (headlaps) and vertical joints (endlaps or sidelaps) by the amount the manufacturer and code require. Canadian tile guidance, for example, gives 100 mm (4 in) headlaps and 150 mm (6 in) endlaps for underlayment beneath tile.\n3. Fasten only as much as needed to hold the sheet flat, with the fasteners the manufacturer specifies.\n4. Line valleys with a separate centred strip before the field underlayment, and trim field courses to overlap it.\n5. Turn underlayment up walls and around penetrations so it integrates with step and apron flashings.\n\n## Low slopes\n\nUnder the IRC, asphalt shingles are limited to slopes of 2:12 (about 9.5 degrees) or more, and slopes between 2:12 and 4:12 require two layers of underlayment or another approved method. Building America guidance repeats this requirement.\n\n## High-wind practice\n\nUS guidance based on the IBHS FORTIFIED programme gives three ways to seal the deck: a self-adhered membrane over the whole deck, tape over all deck seams covered with underlayment, or two layers of No. 30 felt.\n\n## Drip edge\n\nMetal drip edge at eaves and rakes keeps water off the fascia and supports the shingle edge. The order in which drip edge and underlayment are installed varies with the code, the manufacturer and programmes such as IBHS, so installers follow the governing instructions. Some local codes require drip edge only when the shingle manufacturer does.\n\n## Tiled and slated roofs in Europe\n\nOn batten-hung roofs, underlay is draped over the rafters and held by counter-battens and battens. In the UK, BS 5534 requires underlays to be classified for wind uplift resistance, and its 2018 amendment set a maximum drape of 15 mm between rafters.","key_facts":[{"label":"IRC double-layer range","value":"Slopes 2:12 to under 4:12"},{"label":"Minimum slope for asphalt shingles (IRC)","value":"2:12"},{"label":"Maximum underlay drape (BS 5534 A2:2018)","value":"15 mm"}],"regions":["Global"],"aliases":["underlay","roofing felt installation","synthetic underlayment installation"],"related":["ice-barrier-installation","roof-replacement-process","valley-installation","bs-5534-fixing-specification","roofing-underlayment"],"company":null,"sources":[{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"},{"title":"Reroofing","url":"https://www.bloomingtonmn.gov/sites/default/files/2023-08/Reroofing.pdf","publisher":"City of Bloomington, Minnesota"},{"title":"Canadian Roofing Reference Manual: 9.3.3 Tile Installation","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-3-tiles-clay-concrete-slate-metal/9-3-3-installation/","publisher":"Canadian Roofing Contractors Association"},{"title":"What are the fixing requirements of BS 5534?","url":"https://www.marley.co.uk/blog/what-are-the-fixing-requirements-of-bs-5534","publisher":"Marley"},{"title":"Canadian Roofing Reference Manual: 9.4.2 Valleys","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-2-valleys/","publisher":"Canadian Roofing Contractors Association"}],"country":null},{"slug":"urban-heat-island","title":"Urban Heat Island","type":"article","summary":"The tendency of cities to be warmer than surrounding rural areas, driven partly by dark roofs and pavement that absorb sunlight.","body":"An urban heat island is a city or district that is warmer than the rural land around it. The difference arises because buildings and pavement replace vegetation and moist soil, absorb more solar energy, store heat during the day and release it at night. Roofs make up a large share of urban surface area, so roof colour and type have a significant influence on urban temperatures.\n\n## Discovery\n\nThe effect was first described by Luke Howard in the 1810s, who found that central London was about 2.1 °C (3.7 °F) warmer at night than the surrounding countryside.\n\n## Magnitude\n\nThe US EPA cites a review finding that, in the United States, urban daytime temperatures run about 0.6-3.9 °C (1-7 °F) higher than outlying areas and night-time temperatures about 1.1-2.8 °C (2-5 °F) higher. Differences tend to be largest in humid regions and in larger, denser cities, and are often greater at night.\n\n## Causes\n\n- **Less vegetation and water**, which normally cool through shade and evaporation;\n- **Building materials** such as dark roofing and pavement that absorb and re-emit heat;\n- **Urban geometry**, where tall buildings and narrow streets trap heat;\n- **Waste heat** from vehicles, air conditioning and industry;\n- **Weather**, with calm, clear conditions intensifying the effect.\n\nThe EPA notes that conventional roofing can become as much as 37 °C (66 °F) warmer than the air. Hot roofs also warm stormwater runoff, which can affect streams.\n\n## Health and energy effects\n\nHeat islands raise cooling demand and electricity peaks and worsen heat-related illness and mortality, particularly among older adults, children, people with chronic illness and low-income households. Warm nights reduce the relief people would otherwise get after hot days. Higher temperatures also increase ground-level ozone formation.\n\n## Roof-based mitigation\n\n- **Cool roofs** reflect more sunlight. A simulation of a 2018 heatwave in London found that cool roofs could reduce average outdoor temperatures by up to 1.2 °C, more than added trees or solar panels in the same study.\n- **Green roofs** cool through shade and evapotranspiration and also manage stormwater.\n- **Solar panels** shade the roof and convert part of the energy to electricity.\n\nResearch groups such as Lawrence Berkeley National Laboratory's Heat Island Group have studied these measures for decades, and many cities now include roof requirements in heat action plans.","key_facts":[{"label":"First described","value":"Luke Howard, London, 1810s"},{"label":"US daytime difference (EPA)","value":"About 0.6-3.9 °C (1-7 °F)"},{"label":"US night-time difference (EPA)","value":"About 1.1-2.8 °C (2-5 °F)"},{"label":"Roof-based measures","value":"Cool roofs, green roofs, rooftop solar"}],"regions":["Global"],"aliases":["UHI","heat island effect","urban heat"],"related":["cool-roof","green-roof","heat-island-group","solar-reflectance","climate-change-and-roofing"],"sources":[{"title":"Learn About Heat Islands","url":"https://www.epa.gov/heatislands/learn-about-heat-islands","publisher":"US Environmental Protection Agency"},{"title":"Urban heat island","url":"https://en.wikipedia.org/wiki/Urban_heat_island","publisher":"Wikipedia"},{"title":"Cool Roofs","url":"https://heatisland.lbl.gov/coolscience/cool-roofs","publisher":"Lawrence Berkeley National Laboratory, Heat Island Group"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"uros-totora-houses","title":"Uros Totora Reed Houses","category":"world-roofing","type":"article","summary":"Houses of totora reed built by the Uros on floating reed islands in Lake Titicaca, Peru, with walls and roofs of woven reed mats.","body":"The Uros (Uru) people of Lake Titicaca live on artificial floating islands built from totora reed (*Schoenoplectus californicus* subsp. *tatora*), near Puno in Peru. Their houses, boats and the islands themselves are all made largely of this reed, making them one of the few building traditions in the world where the ground, walls and roof come from the same plant.\n\n## Islands\n\nThe islands are built on blocks of the matted root mass of the reed, called *kile*, which grows 1 to 2 m (3 to 7 ft) thick. According to a study by Rocío Torres Méndez for the CIB (International Council for Research and Innovation in Building and Construction), the root mass is cut into blocks about 3 m by 10 m (10 by 33 ft), tied together and anchored with ropes to stakes. Fresh reeds are laid on top continually because the lower layers rot: the study reports maintenance about monthly in the dry season and weekly in the rainy season. An island can last about 30 years before it decays and is abandoned. Smithsonian Magazine counted roughly 70 such islands, each about 15 by 15 m (50 by 50 ft).\n\n## Houses\n\nThe houses are also made of reed. The CIB study describes a frame of bamboo or wood covered with *kesanas*, mats of totora reed, laid in one or two layers. A double layer gives better resistance to water and better thermal performance.\n\n## Change\n\nTourism has become central to island life; Smithsonian Magazine reported that around 80% of the local population works in it. Modern materials such as solar panels now appear on some islands, and plastic bottles are used inside some reed boats.","key_facts":[{"label":"Location","value":"Lake Titicaca near Puno, Peru"},{"label":"Material","value":"Totora reed (Schoenoplectus californicus subsp. tatora)"},{"label":"Wall and roof mats","value":"Kesanas, in one or two layers"},{"label":"Island base","value":"Kile root blocks about 3 x 10 m"},{"label":"Island life","value":"About 30 years"}],"regions":["Latin America"],"aliases":["Uros reed houses","Uru houses","totora houses","floating islands of Lake Titicaca"],"related":["roofing-in-peru","roofing-in-bolivia","andean-ichu-thatch","thatch","water-reed-thatch"],"company":null,"sources":[{"title":"Uros hand made reed floating islands: a proved ancient technique","url":"https://www.irbnet.de/daten/iconda/CIB21650.pdf","publisher":"CIB / IRB (ICONDA)"},{"title":"Visit These Floating Peruvian Islands Constructed From Plants","url":"https://www.smithsonianmag.com/travel/people-peru-live-manmade-islands-constructed-plants-180956218/","publisher":"Smithsonian Magazine"}],"country":null},{"slug":"hook-blade-utility-knife","title":"Utility Knife with Hook Blade","category":"tools-equipment","type":"term","summary":"A retractable or fixed utility knife fitted with hook-shaped blades for pull-cutting asphalt shingles, roofing felt and membranes.","body":"A utility knife is a standard cutting tool on almost every roofing job. Roofers commonly fit it with **hook blades**, which have curved, hook-shaped cutting edges instead of the pointed ends of the standard trapezoidal blade. Hook blades are designed for cutting with a pulling motion through flexible sheet materials such as roofing felt, underlayment, asphalt shingles and some membranes, as well as linoleum and carpet in other trades.\n\n## Why hook blades\n\n- **Pull cutting**: the hook draws through the material as the roofer pulls the knife along a straightedge or chalk line, rather than pushing a point into it.\n- **Protection of the surface below**: because the tip is shielded inside the hook, cutting a shingle or membrane laid on the roof is less likely to slice into the layer underneath than with a pointed blade.\n- **Back cutting of shingles**: asphalt shingles are often cut from the back (the mat side), where the hook cuts cleanly through the asphalt and mat without dragging through the granules, which dull blades quickly.\n- **Reversible blades**: like standard trapezoidal blades, most hook blades have two cutting ends, so the blade can be turned when one end is dull.\n\n## Knife types\n\n- **Retractable knives** let the blade be withdrawn into the handle when not in use, reducing accidental cuts.\n- **Fixed-blade knives** hold the blade rigidly for heavy cutting.\n- **Folding knives** fold the blade into the handle for carrying.\n- Many models store spare blades in the handle and allow tool-free blade changes.\n- **Hatchet-knife combinations** and holsters are sold for roofers.\n\n## Use and safety\n\nHook blades dull quickly on granule-surfaced products, and a dull blade needs more force, which increases the chance of slips. Practical guidance from tool makers and safety bodies includes changing blades frequently, cutting away from the body, keeping the free hand clear of the cutting line, wearing cut-resistant gloves, and retracting or sheathing the blade when moving around the roof. Used blades should go into a closed container rather than being left on the roof or in debris. In hot weather, asphalt products are softer and cut more easily; in cold weather they can crack, and some roofers warm shingles before cutting.","key_facts":[{"label":"Blade shape","value":"Hooked ends instead of points"},{"label":"Cutting action","value":"Pulling cut along a line"},{"label":"Typical materials","value":"Shingles, felt, underlayment, membranes"}],"regions":["Global"],"aliases":["hook knife","roofing knife","hook blade"],"related":["chalk-line","roofing-hatchet","asphalt-shingle","roofing-underlayment","roofing-nailer"],"company":null,"sources":[{"title":"Utility knife","url":"https://en.wikipedia.org/wiki/Utility_knife","publisher":"Wikipedia"},{"title":"AJC Guardian Angle Knife Hatchet","url":"https://www.bigrocksupply.com/ajc-057-mcga-guardian-angle-knife-hatchet-red.aspx","publisher":"Big Rock Supply"},{"title":"Roofing hammers, hatchets and hand tools","url":"https://www.bigrocksupply.com/roofing-hammers-hatchets-hand-tools.aspx","publisher":"Big Rock Supply"}],"country":null},{"slug":"uv-degradation-roofing","title":"UV and Heat Degradation of Roofing","type":"article","summary":"How sunlight and heat break down roofing materials over time through photo-oxidation, embrittlement, chalking and loss of protective surfaces.","body":"Sunlight and heat are among the main causes of roof aging. Ultraviolet (UV) radiation breaks chemical bonds in organic materials such as asphalt and plastics, while high temperatures speed up these reactions and cause repeated expansion and contraction. The combined effect shortens the service life of many coverings, especially in hot, sunny climates.\n\n## How UV damages materials\n\nIn polymers, UV light and oxygen together cause photo-oxidation: chain reactions that break long molecules into shorter ones, making the material brittle and eventually causing cracking. The process is self-accelerating once radicals form. Research on polymers notes that temperature often has a larger effect on degradation rate than UV exposure alone.\n\n- **Polyolefins** (the base of many TPO membranes) and **PVC** need stabilizing additives to resist UV. PVC degradation can cause yellowing and browning without stabilizers.\n- **UV stabilizers** absorb UV light and dissipate it as low-level heat; typical loadings are 0.05 to 2 percent of the material.\n- **Carbon black** screens UV, which is one reason black EPDM rubber membranes are UV-stable.\n\n## Asphalt roofing\n\nAsphalt oxidizes and hardens with exposure to heat and UV. Mineral granules on shingles and cap sheets shield the asphalt from sunlight; as granules wear away, aging accelerates. Inspection guidance notes that hot climates drastically reduce asphalt shingle life.\n\n## Heat and thermal movement\n\nDark roofs can become far hotter than the air. The US EPA notes that roof surfaces can reach as much as 37 °C (66 °F) above air temperature, and Lawrence Berkeley National Laboratory has measured black roofs about 30 °C (54 °F) hotter than white roofs on summer afternoons. Large daily temperature swings cause materials to expand and contract, stressing seams, fasteners and flashings.\n\n## Other materials\n\n- **Metal roofing:** the metal itself is not affected by UV, but paint and coating systems can fade and chalk, and coating chemistry affects colour retention.\n- **Wood:** UV breaks down lignin at the surface, causing greying and erosion.\n- **Clay and natural slate:** inorganic and largely unaffected by UV.\n- **Coatings and sealants:** elastomeric coatings, mastics and sealants weather and need periodic renewal.\n\n## Reducing UV and heat damage\n\nMeasures include reflective (cool) surfaces, UV-stabilized membranes, protective granules or ballast, adequate ventilation under steep-slope roofs, and regular recoating of coatings and sealants.","key_facts":[{"label":"Main mechanism","value":"Photo-oxidation of organic materials"},{"label":"Typical UV stabilizer loading","value":"0.05-2% of polymer"},{"label":"Roof surface vs air (EPA)","value":"Up to about 37 °C (66 °F) hotter"},{"label":"Largely UV-stable","value":"Clay, slate, bare metal"}],"regions":["Global","Middle East","Oceania","Africa"],"aliases":["UV damage","sun damage to roofs","photo-oxidation","heat aging"],"related":["cool-roof","solar-reflectance","asphalt-shingle","tpo-roofing","epdm-roofing","roof-lifespan-comparison"],"sources":[{"title":"UV degradation","url":"https://en.wikipedia.org/wiki/UV_degradation","publisher":"Wikipedia"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"InterNACHI's Standard Estimated Life Expectancy Chart for Homes","url":"https://www.nachi.org/life-expectancy.htm","publisher":"InterNACHI"},{"title":"Cool Roofs","url":"https://heatisland.lbl.gov/coolscience/cool-roofs","publisher":"Lawrence Berkeley National Laboratory, Heat Island Group"},{"title":"Learn About Heat Islands","url":"https://www.epa.gov/heatislands/learn-about-heat-islands","publisher":"US Environmental Protection Agency"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"valley-installation","title":"Valley Installation","category":"installation","type":"article","summary":"Valley installation is how roofing is laid where two roof slopes meet in an internal angle, using open, closed-cut or woven methods over a valley lining.","body":"A **valley** is the internal angle where two roof slopes meet. Because it collects water from both slopes, it carries more flow than any other part of the roof and is a common source of leaks. On asphalt shingle roofs there are three main valley methods: **open**, **closed-cut** and **woven**. Tile, slate and metal roofs use their own valley details, usually with a metal valley gutter.\n\n## Valley lining\n\nAll methods start with a lining. Canadian guidance centres a 1 m (39 in) wide strip of felt, self-adhering underlayment or modified bitumen sheet in the valley, then trims the field underlayment so it overlaps that strip by at least 150 mm (6 in). The lining must be in place before shingling begins.\n\n## Open valley\n\nThe valley is lined with corrosion-resistant metal (or mineral-surfaced roll roofing) and left exposed.\n\n- Metal at least 600 mm (24 in) wide, nailed at its edges every 300-450 mm (12-18 in) without puncturing the centre.\n- Joints lapped 300 mm (12 in) in the direction of flow and set in cement.\n- Chalk lines 100 mm (4 in) from the centre at the top, widening toward the bottom by about 10 mm per metre (1/8 in per foot).\n- Shingles trimmed to the lines, upper corners clipped and the edges set in a band of plastic cement, with no exposed nails.\n\n## Closed-cut valley\n\nShingles from the lower or smaller slope are run through the valley at least 300 mm (12 in) onto the adjoining slope. Shingles on the other slope are laid over them and cut along a line at least 50 mm (2 in) back from the centreline, with the cut edges set in cement. No nail should be within 150 mm (6 in) of the centreline.\n\n## Woven valley\n\nBoth slopes are shingled at the same time, with courses alternately woven across the valley and each end shingle extending at least 300 mm (12 in) onto the other slope. Whole shingles are used so no joint falls in the valley. Woven valleys work best with flexible 3-tab shingles; many manufacturers do not allow them with thick laminated shingles.\n\n## Other coverings\n\nOn tiled roofs in Europe and Australia, valleys are usually lined with lead, aluminium or preformed valley troughs, with tiles cut and mechanically fixed alongside. Debris build-up in valleys is a common maintenance issue on all roof types.","key_facts":[{"label":"Valley lining width (Canada)","value":"1 m (39 in)"},{"label":"Minimum metal width, open valley","value":"600 mm (24 in)"},{"label":"No nails within","value":"150 mm (6 in) of centreline"}],"regions":["Global"],"aliases":["roof valley","open valley","closed-cut valley","woven valley"],"related":["underlayment-installation","roof-valley","step-flashing-installation","asphalt-shingle"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.4.2 Valleys","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-4-flashings-valleys-walls-and-chimneys/9-4-2-valleys/","publisher":"Canadian Roofing Contractors Association"},{"title":"Asphalt Shingle Roofs","url":"https://basc.pnnl.gov/resource-guides/asphalt-shingle-roofs","publisher":"Pacific Northwest National Laboratory, Building America Solution Center"}],"country":null},{"slug":"vapor-retarder","title":"Vapour Retarder (Vapour Control Layer)","category":"low-slope-systems","type":"term","summary":"A layer placed on the warm side of roof insulation to limit water vapour moving from the building into the roof, where it could condense.","body":"A vapour retarder, called a vapour control layer (VCL) in the UK and often a vapour barrier, is a membrane or coating with low permeability to water vapour. In a roof it limits the amount of indoor moisture that diffuses upward into the insulation, where it could condense on the cold underside of the membrane, wetting insulation, corroding fasteners and degrading adhesives.\n\n## Classes\n\nNorth American practice groups retarders by permeance measured to ASTM E96:\n\n- **Class I:** 0.1 US perm or less (about 5.7 SI perm or less), such as polyethylene sheet, sheet metal, rubber membranes and bitumen membranes\n- **Class II:** 0.1-1 perm\n- **Class III:** 1-10 perm\n- **Permeable:** over 10 perm\n\n## Roof materials used\n\n- self-adhered or torched modified bitumen sheets\n- hot-applied asphalt with felts on concrete decks\n- polyethylene or reinforced foil-faced sheets\n- aluminium-faced bitumen VCLs common in Europe\n\n## Where they are needed\n\nNeed depends on climate, indoor humidity and the roof type. In heating-dominated climates the retarder goes on the interior side of the insulation; in hot, humid climates exterior vapour drive matters more. Buildings with high indoor humidity such as pools, laundries and food plants usually need robust retarders. In the UK, BS 6229 refers to BS 5250 for condensation risk analysis and uses an external temperature of minus 5 C over 60 days of the heating season.\n\n## Vapour retarders and air barriers\n\nA vapour retarder slows diffusion; an air barrier stops air leakage. Air movement carries far more moisture than diffusion, so on roofs, especially mechanically attached roofs over steel decks, the retarder layer is often designed and sealed to act as an air barrier too. Inverted roofs place the membrane itself on the warm side, so it serves this function.","key_facts":[{"label":"Class I permeance","value":"0.1 US perm or less"},{"label":"UK term","value":"Vapour control layer (VCL)"},{"label":"UK condensation standard","value":"BS 5250 (referenced by BS 6229)"},{"label":"Placement (cold climate)","value":"Warm side of insulation"}],"regions":["Global"],"aliases":["vapour control layer","VCL","vapor barrier","vapour barrier","air barrier"],"related":["warm-roof","roof-insulation","roof-deck","protected-membrane-roof"],"company":null,"sources":[{"title":"Vapor barrier","url":"https://en.wikipedia.org/wiki/Vapor_barrier","publisher":"Wikipedia"},{"title":"BS 6229:2018 and flat roofing systems","url":"https://ikogroup.co.uk/?p=820","publisher":"IKO"},{"title":"Built-Up Roofing (BUR): What It Is, Types, Issues & More","url":"https://roofonline.com/built-up-roofing-introduction/","publisher":"RoofOnline"},{"title":"Fit for Mod-Bit","url":"https://roofingcontractor.com/articles/95892-fit-for-mod-bit","publisher":"Roofing Contractor / ARMA"}],"country":null},{"slug":"vapour-permeable-underlay","title":"Vapour-Permeable Underlay (Breather Membrane)","category":"components","type":"article","summary":"A vapour-permeable underlay, or breather membrane, is a roof underlay that resists liquid water but lets water vapour pass, widely used in UK and European pitched roofs.","body":"A vapour-permeable (VP) underlay, often called a breather membrane, is a roof underlay designed to stop liquid water and wind-blown snow while allowing water vapour from inside the building to diffuse outward. Such underlays are standard in pitched roofs in the United Kingdom, Ireland and much of Europe, and similar products are used in Australia and New Zealand.\n\n## Background\n\nVP underlays have been used in Europe since the 1970s. In the UK the British Board of Agrément first certified them in 1982 for timber-frame sheathing and ventilated cold roofs.\n\n## LR and HR underlays\n\nUK guidance divides underlays by vapour resistance:\n\n- **Low-resistance (LR):** vapour-permeable products that let moisture through to the batten space.\n- **High-resistance (HR):** traditional vapour-impermeable sheets; the loft beneath must be ventilated to BS 5250.\n\nThe two can be hard to tell apart by eye, so third-party certification should be checked. Some VP underlays are also \"air-open\", allowing air movement, while others are air-tight.\n\n## Batten space ventilation\n\nWhen an LR underlay is used under an air-impermeable covering, UK warranty guidance calls for the batten space to be ventilated, for example with openings equivalent to a 25 mm slot at the eaves and a 5 mm slot at the ridge, created with counter-battens. BS 5534 Annex L describes a test for whether tiles or slates are air-permeable.\n\n## Installation\n\nIn a typical UK cold roof the underlay is draped over the rafters and held by battens. BS 5534 refers to a nominal 10 mm drape so water can run beneath the battens to the eaves. Because VP membranes do not self-seal around nails as bitumen felts do, poor drape can let trapped water leak through batten fixings. Counter-battens fixed over the underlay create a drainage path and reduce this risk. BS 5534 also sets out a method for checking the underlay's resistance to wind uplift.","key_facts":[{"label":"UK standards","value":"BS 5534, BS 5250"},{"label":"First BBA certification","value":"1982"},{"label":"Batten space vent (LR, cold roof)","value":"25 mm eaves / 5 mm ridge equivalent"}],"regions":["Europe","Oceania"],"aliases":["breather membrane","breathable membrane","VP underlay","LR underlay","roof breather membrane"],"related":["roofing-underlayment","roof-battens","cold-roof","warm-roof","roof-ventilation"],"company":null,"sources":[{"title":"The use of vapour permeable underlays in compliance with BS 5534","url":"https://rcimag.co.uk/sandtoft-blog/the-use-of-vapour-permeable-underlays-in-compliance-with-bs-5534","publisher":"Roofing Cladding & Insulation (RCI) magazine"},{"title":"Batten space ventilation for pitched roofs","url":"https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/LABCW%20Batten%20space%20ventilation%20for%20pitched%20roofs%20V2.pdf","publisher":"LABC Warranty"}],"country":null},{"slug":"ventilation-under-metal-roofs","title":"Ventilation and Condensation Under Metal Roofs","category":"installation","type":"article","summary":"Some metal roofs, notably zinc and lead, need a ventilated or drained space beneath them so condensation cannot corrode the metal's underside.","body":"Metal sheets are impermeable and cool quickly at night by radiating heat to the sky. Warm, moist air from inside the building can then condense on the underside of the metal or on the deck beneath. For some metals, trapped moisture causes underside corrosion that can perforate the sheet from below while the visible surface looks sound.\n\n## Metals most affected\n\n- **Zinc**: underside moisture produces white, chalky corrosion. Zinc roofs are built with a ventilated space or open skip sheathing, a drainage mat, or a factory polymer backside coating, typically 30 to 60 micrometres thick.\n- **Lead**: UK guidance calls for a through-ventilated void of at least 50 mm (2 in) beneath lead-covered decks, and at least 25 mm (1 in) behind vertical work, with no stagnant air pockets.\n- **Coated steel and aluminium**: less sensitive, but condensation can still drip into buildings, rot timber decks or corrode unpainted backs, particularly over unheated or humid spaces such as livestock buildings.\n\n## Warm and cold roofs\n\nIn a \"cold\" (ventilated) roof the insulation sits below a ventilated air space, and outside air carries away moisture. In a \"warm\" (unventilated) roof the insulation is above the deck or directly below the metal; it relies on an effective vapour control layer on the warm side and careful detailing. Warm roofs lack the drying capacity of ventilated designs, so specifications for zinc and lead are particularly strict about them.\n\n## Good practice\n\n- Provide continuous vapour control on the warm side of insulation.\n- Provide eave-to-ridge ventilation paths where the design requires them.\n- Use underlayments and drainage layers approved by the metal manufacturer.\n- Avoid installing metal over wet decks or insulation.","key_facts":[{"label":"Lead deck ventilation (UK)","value":"Minimum 50 mm (2 in) void"},{"label":"Zinc protection options","value":"Ventilation, drainage mat, 30-60 micron backside coating"},{"label":"Risk","value":"Hidden underside corrosion"}],"regions":["Europe","Global"],"aliases":["underside corrosion","metal roof condensation","ventilated metal roof","cold roof","warm roof"],"related":["zinc-roofing","lead-roofing","rosin-paper-slip-sheet","metal-roof-over-existing-shingles"],"company":null,"sources":[{"title":"Essential Zinc: Building for the Future","url":"https://continuingeducation.bnpmedia.com/courses/umicore-building-products-usa-inc/essential-zinc-building-for-the-future/2/","publisher":"Continuing Education Center (BNP Media) / Umicore Building Products"},{"title":"The top ten dos and don'ts of rolled lead sheet","url":"https://ribaj.com/products/the-top-ten-dos-and-don-ts-of-rolled-lead-sheet","publisher":"RIBA Journal"},{"title":"Condensation vs. Roof Leak: Diagnosing Attic Moisture","url":"https://www.interlockroofing.com/kb/metal-roof-condensation/","publisher":"Interlock Roofing"},{"title":"Roof Deck, Underlayment & Ventilation for Metal Roofs","url":"https://www.interlockroofing.com/kb/metal-roof-deck-underlayment-ventilation/","publisher":"Interlock Roofing"}],"country":null},{"slug":"verdigris","title":"Verdigris","category":"materials","type":"term","summary":"Verdigris is a green copper acetate compound; the word is often used loosely for the natural green patina on copper roofs, which is chemically different.","body":"Verdigris strictly refers to copper acetate, a bright green compound formed when copper reacts with acetic acid (vinegar). It has been made deliberately for centuries as a pigment. Unlike roof patina, copper acetate is water soluble.\n\n## Verdigris versus patina\n\nIn everyday speech and in many roofing brochures, \"verdigris\" is used for the green coating on old copper roofs. Technical guidance points out that this is inaccurate. The patina that forms outdoors is made of basic copper salts, chiefly sulphates in urban and industrial air and carbonates in cleaner air, with chlorides contributing near the sea. These compounds are insoluble and form a stable protective layer, whereas true verdigris would wash away.\n\nDictionary and encyclopedic definitions are not fully consistent; some broader definitions include basic copper carbonates and sulphates under the verdigris name. For roofing purposes, the useful distinction is between natural, protective patina and corrosion products caused by acids or contamination.\n\n## Where acetate-type products may appear\n\nGreen, powdery or streaky deposits can form where copper is exposed to unusual chemistry, for example acidic run-off or organic acids. These deposits behave differently from a normal patina and may wash off or stain adjacent surfaces.\n\n## Practical notes\n\n- A normal green roof patina is not damage and does not need removing.\n- Artificially patinated copper uses controlled chemical treatments to imitate the natural colour; results can vary.\n- Run-off from any weathering copper surface can stain light-coloured masonry and concrete below.\n\n## Colour without verdigris\n\nA copper roof's colour sequence normally runs from salmon pink through russet and chocolate browns to blue-green or grey-green. In dry climates the green stage may never arrive, leaving the copper dark brown, which shows that the green colour depends on moisture and airborne compounds rather than on any acetate formation.","key_facts":[{"label":"Strict meaning","value":"Copper acetate"},{"label":"Solubility","value":"Water soluble (unlike roof patina)"},{"label":"Roof patina compounds","value":"Basic copper sulphates, carbonates, chlorides"}],"regions":["Global"],"aliases":["copper acetate"],"related":["copper-patina","copper-roofing","copper-runoff-staining"],"company":null,"sources":[{"title":"Copper Patina","url":"https://www.metalroofing.org.nz/node/3860","publisher":"NZ Metal Roof and Wall Cladding Code of Practice (metalroofing.org.nz)"},{"title":"Verdigris","url":"https://en.wikipedia.org/wiki/Verdigris","publisher":"Wikipedia"},{"title":"Copper Alloys Finishes – Natural Weathering","url":"https://www.australwright.com.au/technical-data/advice/copper-brass/copper-alloys-finishes-natural-weathering/","publisher":"Austral Wright Metals"}],"country":null},{"slug":"vermont-slate","title":"Vermont Slate","type":"term","summary":"Natural roofing slate from the Slate Valley of western Vermont and eastern New York, one of the few sources of naturally coloured slate.","body":"Vermont slate is natural roofing slate quarried in the Slate Valley, a district straddling the border between western Vermont and eastern New York State, centred on Granville, New York. It is known for its range of natural colours.\n\n## Colours\n\nSlate Valley is one of the few places in the world that produces coloured slate in commercial quantities. Colours include green, grey, black and red, which allows patterned roofs to be laid using slates of contrasting colour.\n\n## History\n\nSlate was quarried at Fair Haven, Vermont, by 1839. Immigrants from north Wales brought quarrying skills and drove a production boom that peaked in the second half of the 19th century. In 2003 the district had 23 full-time mines employing 348 people.\n\n## Other American slate districts\n\n- **Pennsylvania**: the first commercial slate quarry in the United States opened in 1785 in Peach Bottom Township. The Lehigh and Northampton county area, around Slatington and Bangor, has roughly 400 former quarries and in 1929 produced nearly half of the value of US slate output.\n- **Maine**: slate from the Monson district roofs St Patrick's Cathedral in New York City.\n- **Virginia** also produces slate.\n\n## Standards\n\nIn the United States, roofing slate is specified to ASTM C406, which grades slate S1, S2 or S3. S1 slate is rated for a service life of more than 75 years. US quarries mostly produce slate about 1/4 to 3/8 in (6-10 mm) thick, and the industry redefined \"standard\" slate in 2015 as nominal 1/4 in (6 mm).\n","key_facts":[{"label":"Location","value":"Slate Valley, Vermont-New York border"},{"label":"Notable colours","value":"Green, grey, black, red"},{"label":"Early quarrying","value":"Fair Haven, Vermont, by 1839"},{"label":"Standard","value":"ASTM C406"}],"regions":["North America"],"aliases":["Slate Valley slate","New York slate","American slate"],"related":["natural-slate","welsh-slate","astm-c406"],"sources":[{"title":"Slate industry","url":"https://en.wikipedia.org/wiki/Slate_industry","publisher":"Wikipedia"},{"title":"Slate","url":"https://en.wikipedia.org/wiki/Slate","publisher":"Wikipedia"},{"title":"Slate Roofing: Innovation in an Old Industry, Part II: Standards, Codes, Testing and More","url":"https://iibec.org/publication-post/slate-roofing-innovation-in-an-old-industry-part-ii-standards-codes-testing-and-more/","publisher":"IIBEC"}],"category":"materials","company":null,"country":null},{"slug":"versico","title":"Versico Roofing Systems","category":"manufacturers","type":"company","summary":"Versico is a commercial single-ply roofing brand and division of Carlisle Construction Materials, offering EPDM, TPO and PVC systems.","body":"Versico Roofing Systems is a North American commercial roofing brand operated as a division of Carlisle Construction Materials, itself a wholly owned subsidiary of Carlisle Companies (NYSE: CSL). Like its sister brand Carlisle SynTec Systems, it uses a mailing address in Carlisle, Pennsylvania.\n\n## Products\n\nVersico offers low-slope roofing systems built around three membrane families:\n\n- **EPDM**: synthetic rubber sheets, typically adhered, mechanically fastened or ballasted, with taped seams.\n- **TPO**: thermoplastic sheets joined by hot-air welding.\n- **PVC**: thermoplastic sheets, also hot-air welded.\n\nIt also markets fleece-backed membranes under the VersiFleece name and a range of specialty products and components, including insulation, coatings and adhesives needed to complete a roof assembly.\n\n## Distribution model\n\nVersico sells through roofing distributors to contractors who are authorised to install its systems. Like other single-ply manufacturers, it publishes installation specifications and offers manufacturer system warranties for roofs installed and inspected according to those requirements. Running two parallel brands allows the parent company to serve separate distributor and contractor networks with similar membrane technology.\n\n## Context\n\nSingle-ply membranes became widespread in North America from the late twentieth century as alternatives to multi-ply built-up and modified-bitumen roofs, because they can be installed with fewer layers and less on-site heating. EPDM, TPO and PVC each have different seaming methods, chemical resistance and reflectivity, and building owners and designers choose among them according to climate, building use and energy-code requirements such as roof reflectance. Both companies' products are typically installed over rigid insulation boards on low-slope decks.","key_facts":[{"label":"Parent","value":"Carlisle Construction Materials"},{"label":"Listed parent","value":"Carlisle Companies (NYSE: CSL)"},{"label":"Products","value":"EPDM, TPO, PVC, VersiFleece"}],"regions":["North America"],"aliases":["Versico"],"related":["carlisle-syntec-systems","carlisle-companies","epdm-roofing","tpo-roofing","pvc-roofing"],"company":{"website":"https://www.versico.com","parent":"Carlisle Companies","known_for":["EPDM, TPO and PVC single-ply systems","VersiFleece membranes"]},"sources":[{"title":"Versico Roofing Systems","url":"https://www.versico.com/","publisher":"Versico"},{"title":"Carlisle SynTec Systems","url":"https://www.carlislesyntec.com/","publisher":"Carlisle SynTec Systems"}],"country":null},{"slug":"vietnamese-yin-yang-tile","title":"Vietnamese Yin-Yang Tile (Ngói Âm Dương)","category":"materials","type":"term","summary":"Ngói âm dương, a thin handmade curved clay tile from northern Vietnam laid alternately face up and face down; still made by Tay and Nung craftspeople.","body":"The Vietnamese yin-yang tile (*ngoi am duong*) is a thin, curved, handmade clay roof tile laid in alternating rows, one set face up and the next face down, like the two halves of the yin-yang symbol. It is closely associated with the Tay and Nung peoples of the northern border provinces, and in some parts of Vietnam ordinary red clay roof tiles are called yin-yang tiles because of their concave and convex shape.\n\n## Laying\n\nThe name comes from the way the tiles are placed: alternate tiles face up and down. Concave tiles form channels that carry rainwater, and convex tiles cap the joints between them. This is the same pan-and-cover principle used for Chinese, Roman and Spanish curved tiles and for split-bamboo roofs elsewhere in Southeast Asia.\n\n## Production\n\nTwo documented craft centres give a picture of the process:\n\n- **Quynh Son and Long Dong communes, Bac Son district, Lang Son province:** about 50 households have made the tiles for over a century. Clay from wet rice fields is kneaded with water, cut into pieces about 1 cm (0.4 in) thick, pressed in wooden moulds, sun-dried for one to two months and fired in round wood kilns for about 10 days. Kiln operators judge temperature by smoke colour. One kiln firing of about 10,000 tiles is enough for a three-compartment house.\n- **Lung Ri hamlet, Cao Bang province:** 23 of 80 Nung households still make tiles. Clay is soaked for 10 days, kneaded by buffalo for 4-5 days, rested, sieved, cut into 1 cm sheets and wrapped around cylindrical wooden moulds, each producing four tiles. The blanks dry for 30-40 days, then 16,000-20,000 tiles are fired together for seven days and nights and cooled in the kiln for two to three weeks. Lung Ri was recognised as a traditional craft village in 2024.\n\n## Performance\n\nMakers and reporters describe the tiles as light, waterproof and heat-resistant, keeping houses warm in winter and cool in summer. Published sources give no reliable lifespan figure.\n\n## Status\n\nFactory-made tiles, metal sheet and other materials have taken most of the market, and makers report shortages of suitable clay. Vocational classes have been organised to pass on the skill, and the villages are promoted for craft tourism. Contemporary Vietnamese architects also reuse traditional clay tiles in new buildings.","key_facts":[{"label":"Local name","value":"Ngói âm dương"},{"label":"Makers","value":"Tay and Nung, Lang Son and Cao Bang provinces"},{"label":"Blank thickness","value":"About 1 cm (0.4 in)"},{"label":"Kiln load","value":"About 10,000 (Bac Son) to 16,000-20,000 (Lung Ri) tiles"}],"regions":["Southeast Asia"],"aliases":["ngoi am duong","ngói âm dương","yin yang tile","Nung tile"],"related":["roofing-in-vietnam","clay-roof-tile","pantile","spanish-tile","chinese-glazed-roof-tiles","bamboo-roofing"],"company":null,"sources":[{"title":"Yin-yang tile of the Tay, Nung in Lang Son","url":"https://vov5.vov.gov.vn/colorful-vietnam-vietnams-54-ethnic-groups/yin-yang-tile-of-the-tay-nung-in-lang-son-1807089.vov5","publisher":"Voice of Vietnam (VOV5)"},{"title":"Centuries-old clay tile craft thrives in Vietnam's Lung Ri","url":"https://vietnamnet.vn/en/centuries-old-clay-tile-craft-thrives-in-vietnam-s-lung-ri-2406078.html","publisher":"VietNamNet"},{"title":"Tradition in Clay: Vietnam's Architectural Exploration with Traditional Tiles","url":"https://www.archdaily.com/1032189/tradition-in-clay-vietnams-architectural-exploration-with-traditional-tiles","publisher":"ArchDaily"}],"country":null},{"category":"world-roofing","type":"article","company":null,"slug":"viga-and-latilla-roof","title":"Viga-and-Latilla Roof","summary":"Flat earth roof of the American Southwest built on round log beams (vigas) and small poles (latillas), used since Ancestral Puebloan times.","body":"A viga-and-latilla roof is a flat or nearly flat earth roof carried on round timber beams (*vigas*, Spanish for beams) with smaller poles or split boards (*latillas*, laths) laid across them. It is the traditional roof of Pueblo and Spanish colonial adobe buildings in New Mexico and the wider American Southwest, including the Hopi village of Walpi, and its projecting log ends are a signature of the region's architecture.\n\n## Origins\n\nThe technique goes back to the Ancestral Puebloan peoples between about 750 and 1300 CE. Vigas, or the holes left where they have rotted away, survive in many ruins, including Pueblo Bonito at Chaco Canyon, built between about 850 and 1150 CE. At Walpi, vigas were salvaged and reused from older buildings. Taos Pueblo, built in the late 13th and early 14th centuries and still inhabited, is a well-known living example; its adobe requires regular replastering by community members.\n\n## Construction\n\n- **Vigas** are usually peeled logs 6-10 in (15-25 cm) in diameter and about 15 ft (4.6 m) long, which limited rooms to under about 15 ft wide. They sit directly on adobe or stone walls, roughly 3 ft (0.9 m) apart, with about six to a room as a common standard; Spanish colonial work often spaced them irregularly.\n- **Latillas** are laid across the vigas, sometimes diagonally, and could be peeled branches or hewn boards. In some interiors they were sorted and painted in colours.\n- **Fill**: layers of brush or soil may go on next, followed by a slightly sloped layer of adobe that insulates the room and drains water. Vigas were laid with their small ends to one side to help create the fall.\n- **Parapets and eaves**: parapets enclose the sides, and vigas extended past the wall can carry a covered porch (*portal*) on posts and lintels, often with carved corbels.\n\n## Timber\n\nIn the 17th century piñon (*Pinus edulis*) and ponderosa pine were the common species. Engelmann spruce was valued because it cracks less, but ponderosa pine was used more. Logs were felled in winter from dead and downed trees, hauled from the mountains by oxen, and large vigas were cut first so they could season longest.\n\n## Later changes\n\nThe arrival of the railroad in the 1880s brought dimensioned lumber and eastern building methods, and machine-sawn beams replaced round vigas for many structural uses. Later builders added horizontal bond beams to spread loads and rebar anchors through pre-drilled holes to resist uplift. In the Pueblo Revival style of the 1920s and 1930s, associated with the Santa Fe architect John Gaw Meem, vigas became largely ornamental. Santa Fe's codes, revised in 2012, give credit for structural vigas, although most new buildings use them as decoration. The reconstructed Palace of the Governors in Santa Fe contains both structural and ornamental vigas.\n\n## Performance\n\nEarth roofs of this kind provide thermal mass suited to hot days and cold nights, but they are heavy, need regular maintenance of the earth and plaster, and depend on parapets and drainage outlets to keep water from pooling.","key_facts":[{"label":"Region","value":"American Southwest (New Mexico, Arizona)"},{"label":"Earliest use","value":"Ancestral Puebloan, c. 750-1300 CE"},{"label":"Typical viga","value":"6-10 in (15-25 cm) diameter, ~15 ft (4.6 m) long"},{"label":"Spacing","value":"About 3 ft (0.9 m)"},{"label":"Covering","value":"Brush or soil, then sloped adobe"}],"regions":["North America"],"aliases":["Viga roof","Vigas and latillas","Pueblo roof","Terrado (Southwest)"],"related":["roofing-in-the-united-states","roofing-in-mexico","flat-roof","mud-roof","sod-roof"],"sources":[{"title":"Viga (architecture)","url":"https://en.wikipedia.org/wiki/Viga_(architecture)","publisher":"Wikipedia"},{"title":"Taos Pueblo","url":"https://whc.unesco.org/en/list/492/","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"viking-age-longhouse","title":"Viking Age Longhouse","category":"history","type":"article","summary":"The long, often curved-walled farmhouse of Viking Age Scandinavia, roofed with reed, straw, turf or wooden shingles depending on region and status.","body":"The Viking Age longhouse was the main farmhouse of Scandinavia between about the 8th and 11th centuries. It was a long timber building in which people lived and, in many cases, cattle were kept at one end. Because the timber walls and roofs have rotted, Viking Age houses are known from post holes, wall trenches and a few burnt or waterlogged remains. Full-scale reconstructions at open-air museums show a range of possible roof coverings.\n\n## Form\n\nViking Age walls were often built in a curved, bow-sided plan, so that the ridge line also curved. Houses used earth-fast construction, with load-bearing posts set into the ground, which required good-quality oak. The chieftain's house excavated at Tarm in western Jutland had three or four rooms, with cattle kept at one end.\n\n## Roof coverings\n\n- **Reed thatch:** many reconstructions in western Jutland, Denmark, are thatched with reed, which was plentiful there.\n- **Straw:** craftsmen's houses reconstructed from finds at Hedeby, in Schleswig, around 900 CE, have timber-framed walls filled with wattle and clay and roofs of straw.\n- **Wooden shingles:** the reconstructed longhouse at Ribe VikingeCenter, based on an estate at Gammel Hviding of about 980 CE and following the Trelleborg-Fyrkat house type, is 35 m (115 ft) long and 8 m (26 ft) wide. It used 160 oak trunks and about 5,000 hand-made roofing shingles.\n- **Turf:** where timber was scarce, as in western Jutland, some walls and fences were built of turf. For the turf-roofed traditions of Norway and Iceland, see the entries on sod roofs and the Icelandic turf house.\n\nWindows, where present, were filled with stretched parchment-like skin on frames, and doors and gable boards were sometimes painted with ox blood and pigment.\n\n## Reconstruction sites\n\nBork Vikingehavn in western Jutland rebuilt a chieftain's longhouse excavated at Tarm, on a farm plot of about 100 by 100 m (330 by 330 ft) used from around 700 CE for about 300 years, together with sunken huts, Hedeby-type houses and boathouses. Ribe VikingeCenter rebuilt the Hviding estate. Such reconstructions are partly evidence-based and partly conjectural: Ribe notes, for example, that no late 10th-century barns have been excavated, so its thatched barn is an informed guess.\n\n## Significance for roofing history\n\nThe Viking Age longhouse links the aisled timber houses of earlier prehistoric Europe with medieval farmhouses and the turf-roofed buildings of the North Atlantic. Its variety of coverings shows that the same house type could be roofed in different ways according to local materials and the owner's status.","key_facts":[{"label":"Period","value":"About 8th-11th centuries CE"},{"label":"Wall form","value":"Often curved (bow-sided), with curved ridge"},{"label":"Coverings","value":"Reed, straw, turf or wooden shingles"},{"label":"Ribe reconstruction","value":"35 x 8 m (115 x 26 ft), about 5,000 shingles"},{"label":"Structure","value":"Earth-fast oak posts"}],"regions":["Europe"],"aliases":["Viking longhouse","Norse longhouse","Trelleborg house","langhus"],"related":["scandinavian-sod-roofs","sod-roof","icelandic-turf-house","dutch-and-danish-reed-thatch","wood-shingle","linear-pottery-longhouse","prehistory-of-roofing"],"company":null,"sources":[{"title":"The Hviding Farm buildings","url":"https://www.ribevikingecenter.dk/en/explore/viking-farm-buildings","publisher":"Ribe VikingeCenter"},{"title":"Bork Vikingehavn: Buildings","url":"https://ringkobingfjordmuseer.dk/en/museer/bork-vikingehavn/om-bork-vikingehavn/bygninger/","publisher":"Ringkobing-Skjern Museum"}],"country":null},{"slug":"warm-roof","title":"Warm Roof","category":"components","type":"term","summary":"A warm roof is a construction in which insulation follows the roof slope or sits above the deck, so the structure and roof space stay within the heated envelope.","body":"A warm roof is a roof in which the insulation is placed at rafter level (in pitched roofs) or above the structural deck (in flat roofs), rather than at the ceiling. The timber or steel structure is therefore on the warm side of the insulation, and any roof space is within the conditioned or semi-conditioned volume of the building. The term is common in the UK and Europe; in North America related designs are called unvented or conditioned attics, or compact and insulated roof assemblies.\n\n## Pitched warm roofs\n\nIn UK practice the insulation runs along the line of the rafters, between and/or over them, and an air and vapour control layer (AVCL) is placed on the warm side. Where a high-resistance underlay is used, ventilated voids are provided between underlay and insulation; with a suitable low-resistance (vapour-permeable) underlay, the void may be omitted according to the product's certification. Counter-battens over rigid insulation boards can carry the tiling battens.\n\nWarm pitched roofs are popular for loft conversions and rooms in the roof, because the whole space under the slope can be used.\n\n## Flat warm roofs\n\nIn a warm flat roof, rigid insulation boards are laid above the deck and a vapour control layer, with the waterproof membrane on top. In an inverted (or \"upside-down\") warm roof, the insulation goes above the membrane, protected by ballast or paving, so the membrane is shielded from temperature extremes.\n\n## North American unvented attics\n\nThe US IRC allows unvented attic assemblies under specific conditions in section R806.5, typically requiring air-impermeable insulation, or a combination of insulation types, directly against the underside of the roof deck so the deck stays above the dew point.\n\n## Considerations\n\nWarm roofs generally need careful air sealing, correct vapour control, and adequate insulation thickness, which can raise the roof line when insulation is placed over rafters.","key_facts":[{"label":"Insulation position","value":"Rafter level or above deck"},{"label":"Key layer","value":"Air and vapour control layer (AVCL)"},{"label":"US equivalent","value":"Unvented / conditioned attic (IRC R806.5)"}],"regions":["Europe","North America","Oceania","Global"],"aliases":["unvented attic","conditioned attic","warm deck roof","inverted roof","cold deck roof","hybrid flat roof"],"related":["cold-roof","roof-ventilation","vapour-permeable-underlay","roof-battens","flat-roof","protected-membrane-roof","vapor-retarder","roof-insulation"],"company":null,"sources":[{"title":"Batten space ventilation for pitched roofs","url":"https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/LABCW%20Batten%20space%20ventilation%20for%20pitched%20roofs%20V2.pdf","publisher":"LABC Warranty"},{"title":"IRC R806 Roof Ventilation (code change proposal)","url":"https://iccsafe.org/wp-content/uploads/bcac/IRC-R806.pdf","publisher":"International Code Council"},{"title":"Warm roof","url":"https://www.designingbuildings.co.uk/wiki/Warm_roof","publisher":"Designing Buildings Wiki"},{"title":"Flat roof","url":"https://www.designingbuildings.co.uk/wiki/Flat_roof","publisher":"Designing Buildings Wiki"},{"title":"BS 6229:2018 and flat roofing systems","url":"https://ikogroup.co.uk/?p=820","publisher":"IKO"},{"title":"BS 6229:2025 - The key changes and implications for flat roof design","url":"https://www.bauder.co.uk/technical-centre/standards-and-knowledge/bs-6229-2025-key-changes","publisher":"Bauder"}],"country":null},{"slug":"warning-line-system","title":"Warning Line System","category":"installation","type":"term","summary":"A warning line system is a barrier of rope, wire or chain on stanchions set back from the edge of a low-slope roof to warn workers of the fall hazard.","body":"A **warning line system** is a temporary barrier erected on a low-slope roof to mark the area where work can be done without conventional fall protection. It consists of rope, wire or chain supported on weighted stanchions and flagged so it is clearly visible. It does not physically stop a fall; it warns workers that they are approaching an edge.\n\n## Use under US rules\n\nOSHA's construction standard (29 CFR 1926.501(b)(10)) allows roofing work on **low-slope roofs** (4:12 pitch or less) to be protected by a warning line system combined with guardrails, safety nets, personal fall arrest or a **safety monitoring system**. A safety monitoring system alone is permitted only on roofs 50 ft (15.25 m) or less wide. The detailed construction criteria for warning lines are set out in 1926.502(f).\n\n## Set-back distance\n\nFor roofing work, OSHA interpretations confirm that a warning line set **6 ft (1.8 m)** from the roof edge can protect roofers. Other trades, such as HVAC workers, cannot use the 6-foot roofer provision; under an OSHA enforcement policy they may use a warning line set **15 ft (4.6 m)** or more from the edge, provided no work is done between the line and the edge and a work rule forbids crossing it.\n\n## How it is used\n\n- Workers inside the line work without harnesses.\n- Any worker who must go between the line and the edge needs conventional fall protection, such as a personal fall arrest system.\n- Access paths for materials and equipment are planned so lines are not breached.\n- A **safety monitor**, where used, must be competent, stay on the same roof within sight and voice range, and have no other duties that distract them.\n\n## Outside the US\n\nMany other jurisdictions do not accept warning lines as fall protection for roofers and instead require guardrails or restraint systems at edges. In the UK and Australia, edge protection with guardrails is the normal expectation on flat roofs.","key_facts":[{"label":"US low-slope limit","value":"4:12 or less"},{"label":"Roofer set-back (OSHA)","value":"6 ft (1.8 m) from edge"},{"label":"Other trades set-back (OSHA policy)","value":"15 ft (4.6 m) or more"}],"regions":["North America"],"aliases":["warning lines","safety warning line","controlled access line"],"related":["roofing-fall-protection","personal-fall-arrest-system","low-slope-roof"],"company":null,"sources":[{"title":"1926.501 Duty to have fall protection","url":"https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.501","publisher":"U.S. Occupational Safety and Health Administration"},{"title":"Standard interpretation: warning lines for roofers and other trades (2002-11-15)","url":"https://www.osha.gov/laws-regs/standardinterpretations/2002-11-15","publisher":"U.S. Occupational Safety and Health Administration"},{"title":"Fall Protection in Residential Construction: Frequently Asked Questions","url":"https://www.osha.gov/residential-fall-protection/faq","publisher":"U.S. Occupational Safety and Health Administration"}],"country":null},{"slug":"waste-factor","title":"Waste Factor","category":"installation","type":"term","summary":"The waste factor is the extra percentage of roofing material added to the measured roof area to cover cutting, trimming and breakage.","body":"The **waste factor** (or **waste allowance**) is the additional material an estimator adds on top of the measured roof area. No roof can be covered with exactly its surface area of material: pieces are cut at hips, valleys, rakes, dormers and penetrations, some offcuts are too small to reuse and a few units arrive damaged or break during installation.\n\n## How it is applied\n\nWaste is usually expressed as a percentage of the measured roof area:\n\nMaterial needed = roof area x (1 + waste factor)\n\nFor example, 20 squares (about 186 m²) of roof with a 10 percent waste factor calls for 22 squares of material. Starter strips, ridge and hip caps, and underlayment laps are often calculated separately rather than included in the general waste figure.\n\n## What affects waste\n\n- **Roof shape.** A simple gable roof produces little waste; a hip roof, many valleys or numerous dormers produce more.\n- **Material.** Large or brittle units (slate, tile) or patterned layouts generate more offcuts than flexible shingles. Metal panels cut to length can produce very little waste on simple roofs but more on complex hips.\n- **Exposure and pattern.** Some products, such as wood shakes, vary in coverage with exposure.\n- **Installer practice.** Planning cuts and reusing offcuts reduces waste.\n\n## Published guidance\n\nCanadian guidance for wood shakes and shingles recommends adding 5 to 10 percent to total material requirements, plus extra for valleys. Shingle, tile and metal manufacturers, as well as estimating software, publish their own allowances for different roof shapes.\n\n## Over- and under-ordering\n\nToo low a waste factor can stop work while more material is ordered, possibly from a different production batch with slight colour differences. Too high a factor wastes money and adds disposal costs. Many contractors keep a few spare units for future repairs, which can be useful when a product is later discontinued.","key_facts":[{"label":"Formula","value":"Roof area x (1 + waste factor)"},{"label":"Wood shake and shingle guidance (Canada)","value":"5-10%"},{"label":"Main driver","value":"Complexity of hips, valleys and dormers"}],"regions":["Global"],"aliases":["waste allowance","roofing waste percentage"],"related":["roof-measurement-and-estimating","roofing-square","roof-pitch-calculation"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.2.1 Estimating Materials","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-2-wood-shakes-and-wood-shingles/9-2-1-estimating-materials/","publisher":"Canadian Roofing Contractors Association"},{"title":"Square (unit)","url":"https://en.wikipedia.org/wiki/Square_(unit)","publisher":"Wikipedia"}],"country":null},{"slug":"water-reed-thatch","title":"Water Reed Thatch","type":"term","summary":"Thatch made from the stems of common reed harvested from wetlands; the most durable thatching material in northern Europe.","body":"Water reed thatch is made from the dried stems of reed grown in wetlands and reed beds. In England it is often called **Norfolk reed** after the reed beds of the Norfolk Broads, although much of the reed now used in Britain is imported, including from eastern Europe and South Africa.\n\n## Appearance\n\nA water reed roof has a close, crisp, brush-like surface, because the butt ends of the reed face outward. The reed is not trimmed with a knife; instead it is beaten (\"dressed\") into place with a flat, ridged wooden tool called a leggett. Ridges are usually made of sedge, because water reed is too stiff to bend over the apex. When new, sedge ridges are mid-light brown; after weathering they are hard to tell from straw.\n\n## Fixing\n\nBundles of reed are laid in courses from the eaves upward and held down with horizontal rods called sways, made of hazel or steel, which are fixed to the rafters with hooks or ties. Unlike straw roofs, which can be recoated over old work, a water reed roof is normally stripped back to the roof timbers before rethatching.\n\n## Grading\n\nReed is sorted by length, shape and stem thickness. Thatchers' associations classify lengths as short (3-4 ft, 0.9-1.2 m), medium (4 ft-5 ft 6 in, 1.2-1.7 m) and long (over 5 ft 6 in, most around 6 ft or 1.8 m). Stem diameters range from fine (about 1/8 in, 3 mm) to coarse (1/4 in, 6 mm, or more). Good reed is bright and clean; dark, dull reed is often brittle.\n\n## Durability\n\nWater reed is regarded as the most durable thatch. A steep East Anglian roof might average 50-60 years, and many roofs have lasted 70 years or more; imported reed on an average English roof is more likely to last around 40 years. The sedge ridge needs replacing more often, typically every 10-15 years.\n\n## Conservation issues\n\nIn areas with a straw-thatching tradition, replacing long straw or combed wheat reed with water reed can change a building's historic character. Historic England notes that numerous planning appeal decisions have found such changes harmful to listed buildings.\n","key_facts":[{"label":"Also called","value":"Norfolk reed"},{"label":"Dressing tool","value":"Leggett"},{"label":"Typical life","value":"About 40-70 years"},{"label":"Ridge material","value":"Usually sedge"}],"regions":["Europe","Africa"],"aliases":["Norfolk reed","reed thatch","water reed"],"related":["thatch","long-straw-thatch","combed-wheat-reed"],"sources":[{"title":"Thatched Roofs - An Introduction","url":"https://www.buildingconservation.com/articles/thatchrf/thatchrf.htm","publisher":"Building Conservation"},{"title":"Water reed","url":"https://eamta.co.uk/about-thatch/water-reed/","publisher":"East Anglia Master Thatchers Association"},{"title":"Thatching","url":"https://en.wikipedia.org/wiki/Thatching","publisher":"Wikipedia"},{"title":"Traditional straw thatching in times of shortage","url":"https://historicengland.org.uk/content/docs/advice/traditional-straw-thatching-times-of-shortage-context167-mar21","publisher":"Historic England"}],"category":"materials","company":null,"country":null},{"slug":"welsh-slate","title":"Welsh Slate","type":"term","summary":"Roofing slate quarried in north-west Wales, historically the world's leading source and now part of a UNESCO World Heritage Site.","body":"Welsh slate is natural roofing slate from the quarries of Gwynedd in north-west Wales, especially around Bethesda, Llanberis, Nantlle and Blaenau Ffestiniog. For about 150 years it was the dominant roofing slate in the world, and it is still produced today.\n\n## History\n\nSlate has been worked in north Wales for nearly two thousand years: the Roman fort of Segontium at Caernarfon was roofed with local slate in the late second century. Large-scale commercial quarrying began in 1782 at what became Penrhyn Quarry near Bethesda. By 1882 Wales produced 92% of Britain's slate, about 451,000 tonnes, with Penrhyn and Dinorwic together accounting for half. According to UNESCO, by the late 19th century the region produced about a third of the world's roofing slates and architectural slabs. Skilled Welsh quarrymen emigrated to start or expand slate industries in the United States, continental Europe and Ireland.\n\nLabour relations were difficult. The Great Strike at Penrhyn, which began on 22 November 1900 and lasted three years, is often described as the longest dispute in British industrial history. The last large underground working, Maenofferen, closed in 1999.\n\n## Penrhyn Quarry\n\nAt the end of the 19th century Penrhyn was the largest slate quarry in the world. Its main pit is nearly 1 mile (1.6 km) long and about 1,200 ft (370 m) deep. Nearly 3,000 men worked there at its peak; the workforce is now nearer 200. Larger quarries now exist in Spain, China and the United States, but Penrhyn remains the largest in Britain.\n\n## Heritage status\n\nThe Slate Landscape of Northwest Wales was inscribed on the UNESCO World Heritage List on 28 July 2021. It is a serial site of six components that includes quarries, mines, settlements, railways and the export harbours of Port Penrhyn and Porthmadog. Welsh slate was also designated a Global Heritage Stone Resource by the International Union of Geological Sciences in 2019.\n\n## Properties\n\nWelsh slate is typically blue-grey, purple or heather-toned. EN 12326 test results published by a supplier for Penrhyn slate report very low water absorption (0.14%, class A1), low carbonate content and the T1 and S1 classifications.\n","key_facts":[{"label":"Main area","value":"Gwynedd, north-west Wales"},{"label":"Large-scale quarrying began","value":"1782 (Penrhyn)"},{"label":"Late-19th-century share","value":"About one-third of world roofing slate (UNESCO)"},{"label":"UNESCO inscription","value":"28 July 2021"}],"regions":["Europe"],"aliases":["Penrhyn slate","Blue Welsh slate","Bangor slate"],"related":["natural-slate","spanish-slate","vermont-slate","en-12326"],"sources":[{"title":"Slate industry","url":"https://en.wikipedia.org/wiki/Slate_industry","publisher":"Wikipedia"},{"title":"The Slate Landscape of Northwest Wales","url":"https://whc.unesco.org/en/list/1633/","publisher":"UNESCO World Heritage Centre"},{"title":"Wales's slate landscape becomes World Heritage Site","url":"https://www.museumsassociation.org/museums-journal/news/2021/07/were-thrilled-wales-slate-landscape-becomes-world-heritage-site","publisher":"Museums Association"},{"title":"Penrhyn Quarry","url":"https://en.wikipedia.org/wiki/Penrhyn_Quarry","publisher":"Wikipedia"},{"title":"EN 12326-1 Test Results: Welsh Penrhyn","url":"https://cdn.shopify.com/s/files/1/0242/1053/8577/files/Welsh_Penryn_Test_Results.pdf","publisher":"Test report (supplier data sheet)"}],"category":"materials","company":null,"country":null},{"slug":"welsh-slate-industry","title":"Welsh Slate Industry","category":"history","type":"article","summary":"The slate quarries of north-west Wales, which by the late 19th century produced about a third of the world's roofing slate.","body":"North-west Wales was the world's leading producer of roofing slate in the 19th century. Quarries in the old counties of Caernarfonshire and Merioneth, now Gwynedd, shipped slate to roofs across Britain, Europe and North America, and their techniques and workers spread the industry to other countries.\n\n## Early history\n\nSlate roofed the Roman fort of Segontium at Caernarfon. The Cilgwyn quarry in the Nantlle Valley is thought to date from the 12th century and to be the oldest in Wales, and the first record of quarrying near the later Penrhyn quarry is from 1413. A small export trade to Ireland existed by the late 16th century, and in 1713 fourteen shipments carried 415,000 slates to Dublin.\n\n## Industrial growth\n\nBetween about 1730 and 1740 standard sizes were introduced, with aristocratic names. The largest, the **Duchess**, measured 24 by 12 in (610 by 305 mm), followed by Countess, Lady, Double and Single sizes. Large estate quarries opened in the late 18th century:\n\n- **Penrhyn**, near Bethesda, developed by Richard Pennant from the 1770s and greatly expanded from 1782;\n- **Dinorwig**, near Llanberis, worked commercially from 1787.\n\nCanals, tramways and railways, such as the Padarn Railway, carried slate to the coast. Exports to the United States grew after a 1794 coastal tax, and Germany became an important market after the Hamburg fire of 1842.\n\n## Peak and decline\n\nWelsh production peaked at over half a million tons in 1898, when about 17,000 men worked in the industry. The industry was then hit by a recession from 1879, the Penrhyn dispute of 1900-1903, competition from tiles and imported slate, and two world wars. Output fell from 54,000 tons in 1958 to 22,000 tons in 1970, and by 1972 fewer than 1,000 men worked in North Wales slate.\n\n## Legacy\n\nWelsh slate shaped the look of British towns and encouraged the shallow-pitched roofs of Georgian architecture. In 2018 it was designated a Global Heritage Stone Resource, and in 2021 the Slate Landscape of Northwest Wales was inscribed as a UNESCO World Heritage Site. Penrhyn is still worked today.","key_facts":[{"label":"Peak output","value":"Over 500,000 tons (1898)"},{"label":"Peak workforce","value":"About 17,000 (1898)"},{"label":"Largest standard size","value":"Duchess, 24 x 12 in (610 x 305 mm)"},{"label":"World share","value":"About one third of roofing slate, late 19th century"}],"regions":["Europe"],"aliases":["Welsh slate","North Wales slate industry"],"related":["penrhyn-quarry","dinorwic-quarry","slate-landscape-of-northwest-wales","penrhyn-strike","natural-slate"],"company":null,"sources":[{"title":"Slate industry in Wales","url":"https://en.wikipedia.org/wiki/Slate_industry_in_Wales","publisher":"Wikipedia"},{"title":"The Slate Landscape of Northwest Wales","url":"https://whc.unesco.org/en/list/1633","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"western-red-cedar","title":"Western Red Cedar","type":"term","summary":"Thuja plicata, a Pacific Northwest tree whose light, decay-resistant heartwood is the main species for wood shingles and shakes in North America.","body":"Western red cedar (*Thuja plicata*) is a large conifer native to the Pacific Northwest of North America. Its heartwood is light, aromatic, straight-grained and naturally resistant to decay, which has made it the dominant species for wood roofing shingles and shakes in North America.\n\n## Range\n\nThe tree grows from central south-east Alaska to northern California, mainly between the Cascade Range and Coast Mountains and the Pacific Ocean. It needs moist sites and occurs only where annual precipitation exceeds about 71 cm (28 in). An inland population grows in south-eastern British Columbia and the Idaho Panhandle.\n\n## Why it suits roofing\n\n- **Natural decay resistance**: the heartwood contains thujaplicins, natural fungicides that inhibit rot. The protective effect is reported to last about a century after felling. Young trees do not produce thujaplicins, so durability depends on harvesting mature, older-growth wood.\n- **Light weight**: dried wood weighs roughly 390-400 kg/m³ (24-25 lb/ft³), so a cedar roof is light compared with tile or slate.\n- **Stability and grain**: tight, straight grain with few knots allows clean splitting and sawing and reduces warping.\n\n## Weathering\n\nFreshly installed cedar is reddish to tan; exposed to sun and rain it weathers to silver-grey. Many owners apply treatments to slow this colour change, while others leave it to weather naturally.\n\n## Supply and certification\n\nThe Cedar Shake & Shingle Bureau, founded in 1915, sets grading rules for certified products made by its member mills.\n\n## Limitations\n\nThe wood is fairly strong for its weight but can be brittle. Despite its natural resistance, cedar roofing still decays if it is kept wet by debris, moss or poor ventilation.\n","key_facts":[{"label":"Botanical name","value":"Thuja plicata"},{"label":"Range","value":"South-east Alaska to northern California; inland BC and Idaho"},{"label":"Dry density","value":"About 390-400 kg/m³ (24-25 lb/ft³)"},{"label":"Natural fungicides","value":"Thujaplicins"}],"regions":["North America"],"aliases":["Thuja plicata","red cedar","WRC"],"related":["wood-shingle","wood-shake","alaskan-yellow-cedar","cedar-shake-and-shingle-bureau"],"sources":[{"title":"Thuja plicata","url":"https://en.wikipedia.org/wiki/Thuja_plicata","publisher":"Wikipedia"},{"title":"Cedar Shake & Shingle Bureau","url":"https://www.cedarbureau.org/","publisher":"Cedar Shake & Shingle Bureau"}],"category":"materials","company":null,"country":null},{"slug":"western-states-roofing-contractors-association","title":"Western States Roofing Contractors Association (WSRCA)","summary":"WSRCA is a regional association for roofing contractors in the western United States, founded in 1974.","body":"The Western States Roofing Contractors Association (WSRCA) is a regional trade association for roofing contractors and related companies in the western United States. It was formed in 1974, a year after western contractors met during a national convention in 1973 to discuss creating a group focused on the West.\n\nThe association serves contractors, manufacturers, distributors and consultants. Its members work across a region with very different roofing conditions: coastal rain in the Pacific Northwest, intense sun and heat in the desert Southwest, wildfire exposure in many areas, and snow loads in the mountains.\n\n## Activities\n\n- **Conventions and trade show.** WSRCA holds an annual convention with an exhibit hall for suppliers. An early milestone was its tenth-anniversary convention in San Diego, California, in 1984.\n- **Education and safety.** The association offers safety resources, training and technical education for members.\n- **Industry media.** WSRCA's activities and history are regularly covered by *Western Roofing* magazine, a trade publication focused on the western states.\n\n## History\n\nWSRCA marked its 50th anniversary in 2024. Over that time it has worked alongside national bodies such as the National Roofing Contractors Association and state-level groups.\n\n## Regional context\n\nWestern states differ in how they regulate roofers. California, for example, licenses roofing contractors through its state contractors board, while other states rely more on local registration. WSRCA membership is voluntary and does not replace a state or local licence. Homeowners should check licensing with their state authority.\n\n## Typical roof types in the region\n\nRoofing in the West covers a wide mix of systems. Concrete and clay tile are common on homes in California, Arizona and Nevada; asphalt shingles and metal dominate in the Pacific Northwest and mountain states; and single-ply membranes, spray polyurethane foam and coatings are widely used on low-slope commercial roofs in hot, dry areas. Fire-rated roof coverings matter in wildfire-prone zones.","key_facts":[{"label":"Founded","value":"1974"},{"label":"Region","value":"Western United States"},{"label":"Origin","value":"Meeting of western contractors in 1973"},{"label":"Milestone","value":"50th anniversary in 2024"}],"regions":["North America"],"aliases":["WSRCA","Western States RCA"],"related":["nrca","midwest-roofing-contractors-association","how-to-find-a-licensed-roofer"],"company":{"founded":"1974","known_for":["Annual western roofing convention"]},"sources":[{"title":"WSRCA Hits 50 Year Milestone","url":"https://westernroofing.net/?p=6984","publisher":"Western Roofing"},{"title":"Celebrating 50 Years of Safety & Excellence","url":"https://www.westernroofing.net/?p=6987","publisher":"Western Roofing"},{"title":"Half a century of industry leadership","url":"https://www.rooferscoffeeshop.com/post/half-a-century-of-industry-leadership","publisher":"RoofersCoffeeShop"}],"category":"organizations","type":"organization","country":null},{"slug":"westlake-royal-roofing","title":"Westlake Royal Roofing","category":"manufacturers","type":"company","summary":"Westlake Royal Roofing is the roofing business of Westlake Corporation, built largely from Boral's North American roofing operations bought in 2021.","body":"Westlake Royal Roofing Solutions is the roofing arm of Westlake Royal Building Products, part of Westlake Corporation, a Houston, Texas-based chemicals and building-products company founded in 1986. The roofing business was assembled mainly from the North American building products operations of the Australian company Boral, which Westlake agreed to buy in June 2021.\n\n## The Boral acquisition\n\nOn 20 June 2021 Westlake announced an all-cash agreement to acquire Boral's North American building products businesses for USD 2.15 billion. The businesses covered roofing; siding, trim and shutters; decorative stone; and windows. Boral had been a significant producer of concrete and clay roof tile in the United States. The deal was expected to close in the second half of 2021.\n\n## Brand\n\nIn January 2022, at the International Roofing Expo, Westlake introduced the Westlake Royal Building Products brand, combining the former Boral businesses with Westlake's existing building-products lines, and presented new roofing product lines.\n\n## Products\n\nWestlake Royal Roofing supplies roof tile, including concrete and clay tile, along with stone-coated steel and composite roofing products, and related roofing components, mainly for the US residential market. Westlake also owns DaVinci Roofscapes, a maker of synthetic (composite) slate and shake roofing.\n\n## Market context\n\nTile roofing in the US is concentrated in warm and coastal states such as California, Arizona, Texas and Florida. Westlake's entry into the sector placed one of the larger US tile producers inside a vertically integrated chemicals company that also makes PVC and other polymers used in building products. Its current roofing product brands include Newpoint concrete tile, US Tile clay roofing and Unified Steel stone-coated steel.","key_facts":[{"label":"Parent","value":"Westlake Corporation (Houston, Texas)"},{"label":"Key acquisition","value":"Boral North America building products, USD 2.15 billion (2021)"},{"label":"Brand launched","value":"January 2022"}],"regions":["North America"],"aliases":["Westlake Royal Roofing Solutions","Boral Roofing","Westlake Royal Building Products"],"related":["concrete-roof-tile","clay-roof-tile","davinci-roofscapes","stone-coated-steel","eagle-roofing-products"],"company":{"headquarters":"Houston, Texas, United States","website":"https://westlakeroyalroofing.com","parent":"Westlake Corporation","known_for":["Concrete and clay roof tile","Stone-coated steel roofing"]},"sources":[{"title":"Westlake significantly expands its presence ... by acquiring Boral's North American building products businesses","url":"https://businesswire.com/news/home/20210620005247/en/Westlake-Significantly-Expands-its-Presence-in-the-Growing-North-American-Home-Construction-Materials-Markets-by-Acquiring-Boral%E2%80%99s-North-American-Building-Products-Businesses","publisher":"Business Wire"},{"title":"Westlake Royal Building Products debuts new brand and roofing lines at 2022 International Roofing Expo","url":"https://www.businesswire.com/news/home/20220131005175/en/Westlake-Royal-Building-Products-Debuts-New-Brand-and-Roofing-Lines-at-2022-International-Roofing-Expo","publisher":"Business Wire"},{"title":"Westlake Corporation","url":"https://en.wikipedia.org/wiki/Westlake_Corporation","publisher":"Wikipedia"}],"country":null},{"slug":"westminster-hall-roof","title":"Westminster Hall Roof","category":"history","type":"place","summary":"The oak hammerbeam roof of Westminster Hall, London, commissioned by Richard II in 1393 and the largest medieval timber roof in northern Europe.","body":"**Westminster Hall** is the oldest surviving part of the Palace of Westminster in London. Its walls date from 1097-1099, under William II, but its fame rests on the oak hammerbeam roof built for Richard II at the end of the 14th century, often described as the greatest creation of medieval timber architecture.\n\n## Construction\n\nRichard II commissioned the new roof in 1393. The king's master mason, **Henry Yevele**, raised the walls and added heavy buttresses to resist the outward thrust, while the king's carpenter, **Hugh Herland**, designed the roof. Sources give the main carpentry period as 1395-1399. Two lanterns on the ridge were completed in 1397-98, and work stopped in 1401 before details such as the decorative tracery were fully finished. How the earlier roof of the hall was supported is unknown.\n\n## Scale\n\n- The roof covers about 20.7 by 73.2 m (68 by 240 ft).\n- The arched trusses meet in a central span of about 18 m (60 ft) or more.\n- Timbers were lifted to about 28 m (92 ft).\n- The framed timber weighed about 660 tons, and its lead covering about 176 tons.\n\nThe oak came from woods in Hampshire, Hertfordshire and Surrey. The trusses were framed near Farnham, Surrey, then carried to Westminster by wagon and barge. The work was partly funded by fees paid by exiles for licences to return to England.\n\n## Decoration\n\nThe ends of the hammer beams carry 26 carved angels.\n\n## Survival and repair\n\nThe hall survived the 1834 fire that destroyed most of the old palace, and incendiary bombs on 10 May 1941. In 1913 deathwatch beetle was found in the timbers, and the architect Frank Baines led an extensive restoration of the roof in the following years. Sources differ on the details and completion date of that work.\n\n## Significance\n\nThe roof showed how far timber could be pushed without a continuous tie beam. It remains a reference point for historic carpentry, conservation engineering and the study of medieval building logistics.","key_facts":[{"label":"Commissioned","value":"1393, by Richard II"},{"label":"Carpenter","value":"Hugh Herland"},{"label":"Roof area","value":"About 20.7 x 73.2 m (68 x 240 ft)"},{"label":"Timber weight","value":"About 660 tons"},{"label":"Lead covering","value":"About 176 tons"}],"regions":["Europe"],"aliases":["Westminster Hall hammerbeam roof"],"related":["hammerbeam-roof","history-of-timber-roof-framing","medieval-lead-roofs"],"company":null,"sources":[{"title":"The hammer-beam roof","url":"https://webtest.parliament.uk/about/living-heritage/building/palace/westminsterhall/architecture/the-hammer-beam-roof-","publisher":"UK Parliament"},{"title":"Westminster Hall","url":"https://en.wikipedia.org/wiki/Westminster_Hall","publisher":"Wikipedia"},{"title":"Hammerbeam roof","url":"https://en.wikipedia.org/wiki/Hammerbeam_roof","publisher":"Wikipedia"}],"country":null},{"slug":"wharenui","title":"Wharenui","type":"article","summary":"The Māori meeting house at the heart of a marae in New Zealand; its gabled roof structure represents the body of an ancestor.","body":"A *wharenui* (\"large building\") is the meeting house that stands at the centre of a Māori *marae* in Aotearoa New Zealand. It faces the open ceremonial space called the *marae ātea*, where visitors are welcomed and issues are debated, and inside it hosts meetings, gatherings, overnight stays and cultural activities. The building is usually gabled, with a deep front porch, and its roof is central to its meaning.\n\n## The roof as an ancestor\n\nA wharenui is commonly understood as the body of an ancestor, and the parts of the roof structure are named accordingly:\n\n- **Tāhuhu** - the ridge beam, the ancestor's backbone.\n- **Heke** - the rafters, the ribs, which run from the wall posts up to the ridge.\n- **Maihi** - the carved diagonal bargeboards on the front gable, the arms; their ends are called *raparapa*, the fingers.\n- **Koruru** - the carved face at the apex of the front gable, the head.\n- **Amo** - vertical supports beneath the ends of the maihi.\n- **Poutokomanawa** - the central post inside, sometimes called the heart-supporting post, which helps carry the ridge.\n\n## Construction history\n\nTraditionally the framing members were bound with complex rope lashings (*mīmiro*) rather than nails. After European contact, steel tools allowed meeting houses to become larger from the 1840s, and nails gradually entered part of the woodwork, so the old lashing methods became less common.\n\nCarving (*whakairo*) is an essential part of the building. The New Zealand Māori Arts and Crafts Institute, set up under a 1963 Act of Parliament, has worked to sustain the carving tradition and has built or restored more than 40 marae.\n\n## Today\n\nModern meeting houses are designed to meet the New Zealand Building Code like any other public building, and they generally use contemporary roof coverings and structures. The symbolic layout of ridge, rafters and bargeboards is retained, so the roof continues to express genealogy and identity as well as providing shelter.","key_facts":[{"label":"Meaning","value":"Large building (meeting house)"},{"label":"Ridge beam","value":"Tāhuhu, the ancestor's backbone"},{"label":"Rafters","value":"Heke, the ribs"},{"label":"Bargeboards","value":"Maihi, the arms"},{"label":"Setting","value":"Marae, Aotearoa New Zealand"}],"regions":["Oceania"],"aliases":["Whare nui","Whare whakairo","Meeting house"],"related":["roofing-in-new-zealand","samoan-fale","ridge-board","bargeboard","gable-roof"],"sources":[{"title":"Wharenui","url":"https://en.wikipedia.org/wiki/Wharenui","publisher":"Wikipedia"},{"title":"Marae","url":"https://en.wikipedia.org/wiki/Marae","publisher":"Wikipedia"}],"company":null,"category":"world-roofing","country":null},{"slug":"white-rust","title":"White Rust (Wet Storage Stain)","category":"problems-maintenance","type":"term","summary":"A white, powdery zinc corrosion product that forms on galvanised steel kept wet without air, often while panels are bundled in storage.","body":"White rust is a white or grey, sometimes chalky deposit of zinc corrosion products that forms on zinc-coated (galvanised) steel. In the galvanising industry, the deposit that forms on new material during storage or transport is usually called **wet storage stain**. The American Galvanizers Association treats the two names as related but distinct: wet storage stain refers to the storage problem on newly galvanised items, while the term white rust was historically associated with galvanised cooling towers.\n\nZinc normally protects itself by forming a thin, stable patina of zinc carbonate when it is exposed to free air and allowed to dry. White rust forms instead when zinc stays wet without good air circulation.\n\n## How it happens on roofing\n\n- **Bundled or stacked sheets** that get wet in transit or on site. Water held between tightly nested sheets is starved of oxygen and attacks the zinc quickly.\n- **Condensation** inside packaging when temperatures swing.\n- **Panels left on the ground** or uncovered under tarps that trap moisture.\n- **Laps and crevices** on installed roofs that stay damp.\n\n## Significance\n\nLight staining is usually cosmetic; it tends to weather to a normal patina once the surface is exposed and able to dry. Heavy deposits indicate that a significant amount of zinc has been consumed, which can shorten the life of the coating. Painted and aluminium-zinc coated products can also show staining when stored wet. Many manufacturers exclude storage damage from their warranties, which is why delivery inspection matters.\n\n## Prevention and treatment\n\nIndustry guidance focuses on keeping material dry: store bundles off the ground, slope them so water drains, cover them with breathable rather than sealed coverings, and separate wet sheets so they can dry. Light deposits may be removed with a stiff nylon brush and allowed to weather. Heavier deposits should be assessed against the product's coating specification, and coating thickness can be measured to decide whether the protection is still adequate.","key_facts":[{"label":"Metal affected","value":"Zinc and zinc-coated (galvanised) steel"},{"label":"Main cause","value":"Moisture trapped without air circulation"},{"label":"Prevention","value":"Dry, ventilated, sloped storage off the ground"}],"regions":["Global"],"aliases":["wet storage stain","zinc corrosion","white corrosion"],"related":["red-rust","galvanized-steel-roofing","metal-roofing","zinc-roofing"],"company":null,"sources":[{"title":"Wet Storage Stain vs. White Rust","url":"https://galvanizeit.org/knowledgebase/article/wet-storage-stain-vs.-white-rust","publisher":"American Galvanizers Association"},{"title":"A Guide to Minimizing and Treating Wet Storage Stain","url":"https://galvanizeit.org/uploads/publications/Wet_Storage_Stain_On_Galvanized_Steel.pdf","publisher":"American Galvanizers Association"},{"title":"White rust prevention and treatment","url":"https://www.steel.org.au/getattachment/074d4981-2f9d-42d6-b772-e07e8186edac/White-rust-prevention-and-treatment_INGALSM3.pdf","publisher":"Australian Steel Institute"},{"title":"GalvInfoNote 3.2","url":"https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote_3_2.pdf","publisher":"GalvInfo Center"}],"country":null},{"slug":"wienerberger","title":"Wienerberger","category":"manufacturers","type":"company","summary":"Wienerberger is a Vienna-based building-materials group founded in 1819, the world's largest brick maker and a leading European producer of clay and concrete roof tiles.","body":"Wienerberger AG is an Austrian building-materials company headquartered in Vienna. It was founded in 1819 by Alois Miesbach, who began making bricks from clay deposits in the Wienerberg district south of the city; after his death in 1857 his nephew Heinrich Drasche took over. The company has been listed on the Vienna Stock Exchange since 1869. It is the world's largest brick producer and describes itself as Europe's leading maker of roof tiles.\n\n## Roofing businesses\n\nWienerberger built its roof tile business through acquisitions:\n\n- **Tondach Gleinstatten** and the UK maker **Keymer Tiles**, both acquired in 2014.\n- **Terreal**, the French clay tile and brick group, acquired in 2024. Terreal brought with it the German clay tile maker **Creaton** and the US terracotta tile maker **Ludowici**.\n\nWienerberger was formerly a joint owner of the Austrian concrete roof tile maker **Bramac**, which it entered in the late 1960s or early 1970s (sources give 1969 or 1973). In 2011 it sold its 50% share to the Monier group, which became sole owner; Bramac is now part of BMI Group, not Wienerberger.\n\nIn November 2025 Wienerberger opened an electrically powered concrete tile factory at Sittingbourne in England, and in May 2026 it started building an electric roof tile kiln at Broomfleet, UK, part of efforts to cut fuel-related emissions from tile production.\n\n## North America\n\nWienerberger entered the US in 1999 by buying the brick maker General Shale for USD 260 million. General Shale bought Meridian Brick from Boral in 2021 and, after the Terreal deal, took over management of Ludowici.\n\n## Other activities\n\nBesides bricks and roof tiles, the group makes concrete pavers (Semmelrock, acquired 2010) and plastic and ceramic pipe systems. It reported revenue of about EUR 4.6 billion for 2025.","key_facts":[{"label":"Founded","value":"1819, Vienna"},{"label":"Founder","value":"Alois Miesbach"},{"label":"Headquarters","value":"Vienna, Austria"},{"label":"Listing","value":"Vienna Stock Exchange (since 1869)"},{"label":"Roof tile brands","value":"Tondach, Keymer, Terreal, Creaton, Ludowici"}],"regions":["Europe","North America"],"aliases":["Wienerberger AG"],"related":["clay-roof-tile","concrete-roof-tile","terreal","creaton","ludowici","bmi-group"],"company":{"founded":"1819","headquarters":"Vienna, Austria","website":"https://www.wienerberger.com","known_for":["Bricks","Clay roof tiles","Concrete roof tiles"]},"sources":[{"title":"Wienerberger","url":"https://en.wikipedia.org/wiki/Wienerberger","publisher":"Wikipedia"},{"title":"Creaton","url":"https://de.wikipedia.org/wiki/Creaton","publisher":"Wikipedia (German)"},{"title":"Ludowici Roof Tile","url":"https://en.wikipedia.org/wiki/Ludowici_Roof_Tile","publisher":"Wikipedia"},{"title":"Bramac","url":"https://de.wikipedia.org/wiki/Bramac","publisher":"Wikipedia (German)"}],"country":null},{"slug":"wildfire-roofing","title":"Wildfire Roofing","type":"article","summary":"Roof design and materials that reduce the chance of a building igniting from embers, radiant heat or flames during a wildfire or bushfire.","body":"Wildfire roofing refers to the choice of roof coverings and details that help a building survive a wildfire (called a bushfire in Australia). The roof is a large, upward-facing surface that collects wind-blown embers, and research and post-fire surveys consistently identify embers as a major cause of home ignition.\n\n## How roofs ignite\n\n- **Embers (firebrands).** Wind can carry burning fragments well over a kilometre ahead of a fire front. Embers that land in gutters, valleys, roof debris or gaps under tiles can ignite leaves and combustible materials. Embers that enter vents can ignite the attic.\n- **Radiant heat.** Nearby burning vegetation or buildings can heat roof edges and openings to ignition.\n- **Direct flame contact.** Flames from vegetation, fences or decks close to the house can reach eaves.\n\nThe Insurance Institute for Business & Home Safety (IBHS) notes that no single hardening measure fully protects a building and recommends a system-based approach.\n\n## Roof coverings\n\nFire classifications such as Class A under ASTM E108 or UL 790 in North America indicate how a covering performs against external fire. Materials commonly available with Class A ratings include asphalt shingles, metal, clay and concrete tile, and slate, sometimes with a specific underlayment. Untreated wood shakes perform poorly and can themselves generate embers; many fire-prone jurisdictions restrict them.\n\n## Details that matter\n\n- **Gutters and valleys:** keep free of leaves and needles; non-combustible gutter guards can help.\n- **Gaps at ridges and eaves:** under barrel tiles and profiled panels, bird stops or closures keep embers and debris out.\n- **Vents:** eave, gable and roof vents should have fine non-combustible mesh or ember-resistant vent designs.\n- **Eaves and soffits:** enclosed, non-combustible soffits resist ember entry better than open rafter tails.\n- **Roof-to-wall junctions and skylights:** need non-combustible flashing and tempered or rated glazing.\n\n## Surroundings\n\nGuidance in the United States describes a Home Ignition Zone, with the first 1.5 m (5 ft) around the building kept free of combustibles. IBHS experiments found that even well-watered plants within that zone can increase heat exposure. Trees should be pruned back about 3 m (10 ft) from roofs.\n\n## Regional codes\n\nCalifornia's building code has dedicated wildland-urban interface requirements, the International Wildland-Urban Interface Code is used in other US jurisdictions, and Australia uses AS 3959 with Bushfire Attack Levels. In the US, the wildland-urban interface was the fastest-growing land-use type between 1990 and 2010, increasing the number of homes exposed.","key_facts":[{"label":"Leading ignition source","value":"Wind-blown embers"},{"label":"North American fire rating","value":"Class A (ASTM E108 / UL 790) is highest"},{"label":"Ember-resistant zone","value":"About 1.5 m (5 ft) around the building"},{"label":"Australian standard","value":"AS 3959 (Bushfire Attack Levels)"}],"regions":["North America","Oceania","Europe","Global"],"aliases":["fire-resistant roofing","bushfire roofing","WUI roofing"],"related":["class-a-fire-rating","ember-resistant-roofing","bushfire-attack-level","climate-change-and-roofing"],"sources":[{"title":"Wildfire","url":"https://ibhs.org/wildfire/","publisher":"Insurance Institute for Business & Home Safety"},{"title":"Wildland-urban interface","url":"https://en.wikipedia.org/wiki/Wildland%E2%80%93urban_interface","publisher":"Wikipedia"},{"title":"ASTM E108-20a Standard Test Methods for Fire Tests of Roof Coverings","url":"https://store.astm.org/e0108-20a.html","publisher":"ASTM International"},{"title":"2009 Victorian bushfires","url":"https://en.wikipedia.org/wiki/2009_Victorian_bushfires","publisher":"Wikipedia"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"wind-damage","title":"Wind Damage","category":"problems-maintenance","type":"article","summary":"Roof damage caused by wind uplift, typically lifted, creased, torn or missing shingles, tiles or panels, often starting at edges.","body":"Wind damage occurs when wind pressure lifts or tears roofing materials. As wind flows over a building it creates suction on the roof, strongest at corners, eaves, rakes, ridges and hips. If the uplift force exceeds the resistance of fasteners, adhesive or interlocks, roofing units lift, crease, break or blow away. Damage often starts at an edge and then progresses as the wind gets under the next course.\n\n## Asphalt shingles\n\nOn self-sealing asphalt shingles, technical literature describes a progression: uplift breaks or stretches the sealant bond, the tab flips upward, a crease forms across the shingle (usually just below the butt of the course above), and repeated flexing tears the tab off. Creases may be faint on new, flexible shingles and need close inspection with gentle hand pressure.\n\nAn important point in claims and investigations is that **unsealed shingles are not automatically wind damaged**. Shingles can fail to bond, or lose their bond, through manufacturing variation, cold-weather installation, dirt in the sealant, stuck release tape, thermal cycling, racked installation, under-driven or misplaced nails and age. Research cited by roof consultants found shingles tend to stay sealed for their first few years, with unsealing becoming more common later. Patterns help: wind damage concentrates on exposed slopes and edges facing the storm, while thermal or installation-related unsealing often follows diagonal or repeating patterns unrelated to exposure.\n\n## Other materials\n\n- **Tiles and slates** may lift, crack or slide, especially at ridges, hips and verges, or where mortar bedding has weakened.\n- **Metal panels** can peel back from edges if fastening or clips are inadequate; trims and ridge caps are frequent failure points.\n- **Low-slope membranes** may billow, peel at the perimeter or tear from fasteners; loose ballast can scour the membrane.\n\n## After a storm\n\nOwners should first look from the ground for missing pieces, debris and displaced flashings, then arrange a professional inspection. Temporary tarping limits interior damage. Higher-wind-rated products, stronger edge details and correct nailing are the main ways to improve resistance on reroofing; in some regions, fortified roofing programmes specify enhanced details.","key_facts":[{"label":"Highest uplift zones","value":"Corners, eaves, rakes, ridges, hips"},{"label":"Shingle evidence","value":"Creased, torn or missing tabs"},{"label":"Common misconception","value":"Unsealed shingles are not necessarily wind damage"}],"regions":["Global"],"aliases":["wind uplift damage","blown-off shingles","creased shingles"],"related":["storm-damage-inspection","hail-damage","emergency-roof-tarping","roof-insurance-claims","asphalt-shingle"],"company":null,"sources":[{"title":"Misconceptions of Wind Damage to Asphalt Composition Shingles","url":"https://iibec.org/misconceptions-wind-damage-asphalt-composition-shingles/","publisher":"IIBEC"},{"title":"Mastering Roof Inspections: Asphalt Composition Shingles, Part 51","url":"https://www.nachi.org/asphalt-comp-shingles-part51-105.htm","publisher":"InterNACHI"},{"title":"R-143 Damage to Shingles Caused by Extraordinary Wind Events","url":"https://www.gaf.com/en-us/document-library/documents/technical-bulletins-&-notes/r-143-damage-to-shingles-caused-by-extraordinary-wind-events.pdf","publisher":"GAF"},{"title":"Wind damaged roof FAQs","url":"https://inspectapedia.com/roof/Wind_Damaged_Roof_FAQs.php","publisher":"InspectAPedia"}],"country":null},{"slug":"wind-uplift","title":"Wind Uplift","type":"term","summary":"The upward suction and pressure that wind exerts on a roof, which must be resisted by the covering, deck, fasteners and framing.","body":"Wind uplift is the upward force that wind places on a roof. As air speeds over and around a building, it lowers the pressure on the roof surface, creating suction. If air also enters the building through an opening, the pressure inside rises and pushes up on the underside of the roof. The two effects add together.\n\nUplift acts on every layer: the covering (shingles, tiles, panels, membranes), the fasteners and adhesives, the deck, and the connections from framing to walls. Each must be strong enough, and the forces must travel through an unbroken load path to the foundation.\n\n## Factors that affect uplift\n\n- **Wind speed.** Pressure rises with the square of wind speed, so a modest increase in speed produces a much larger load.\n- **Exposure and height.** Open terrain, coastlines and taller buildings see higher pressures than sheltered sites.\n- **Roof shape and slope.** Hip roofs generally see lower uplift than gable roofs. Low slopes and overhangs can concentrate suction.\n- **Location on the roof.** Corners, edges, ridges and hips have far higher pressures than the middle (field) of the roof. Design standards divide roofs into pressure zones for this reason.\n- **Openings.** A broken window or failed garage door can raise internal pressure and sharply increase net uplift.\n\n## How uplift is handled in design\n\nNational standards translate a design wind speed into pressures for each roof zone. Examples include ASCE 7 in the United States, Eurocode 1 (EN 1991) in Europe, and AS/NZS 1170.2 in Australia and New Zealand. Roofing products are then tested and rated for uplift resistance. Low-slope systems are often tested to FM Global or UL uplift methods; asphalt shingles are classified by ASTM D3161 (fan-induced) and ASTM D7158 (sealant bond uplift), with ASTM D7158 Classes D, G and H corresponding to about 145, 193 and 241 km/h (90, 120 and 150 mph).\n\n## Field practice\n\nCorrect fastener type, number and placement often matter more than the product itself. Post-storm investigations frequently find shingle nails placed above the nailing line, too few fasteners at edges, or deck nails that missed framing. Enhanced fastening at corners and perimeters, ring-shank nails for decks, and sealed edges are common upgrades in high-wind regions.","key_facts":[{"label":"Main sources of uplift","value":"External suction plus internal pressure"},{"label":"Highest-pressure areas","value":"Corners, edges, ridges, hips"},{"label":"ASTM D7158 Class H","value":"Up to about 241 km/h (150 mph)"},{"label":"Design standards","value":"ASCE 7, Eurocode 1, AS/NZS 1170.2"}],"regions":["Global"],"aliases":["roof uplift","wind suction","uplift pressure"],"related":["roof-wind-pressure-zones","shingle-wind-rating","hurricane-roof-damage","roof-to-wall-connection","tornado-roof-damage"],"sources":[{"title":"Determining Components and Cladding Roof Design Pressures","url":"https://structuremag.org/?p=13322","publisher":"STRUCTURE magazine"},{"title":"ASCE 7 and roof wind design (SPRI technical bulletin 2022.2)","url":"https://www.spri.org/wp-content/uploads/2022/10/2022.2-ASCE-7.pdf","publisher":"SPRI"},{"title":"Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","publisher":"Wikipedia"},{"title":"Hurricanes and High Winds Overview","url":"https://basc.pnnl.gov/information/hurricanes-and-high-winds-overview","publisher":"Building America Solution Center (PNNL)"}],"category":"climate-sustainability","company":null,"country":null},{"slug":"wind-uplift-testing-metal-roofs","title":"Wind Uplift Testing of Metal Roofs","category":"standards-codes","type":"article","summary":"Metal roof systems are rated for wind by laboratory tests such as ASTM E1592, UL 580 and UL 1897, which apply suction to full roof assemblies.","body":"Wind blowing over a roof creates suction that tries to lift panels, especially at corners, edges and ridges. Because metal panels are attached at discrete points (clips or screws) rather than continuously, the design of those connections and their spacing is critical. Engineered metal roof systems are therefore tested as complete assemblies.\n\n## Common test methods\n\n- **ASTM E1592**: a structural test of sheet metal roof panel assemblies under uniform static air pressure.\n- **UL 580**: a standard test for uplift resistance of roof assemblies.\n- **UL 1897**: another uplift test for roof assemblies.\n- **Regional approvals**: hurricane regions such as Miami-Dade County, Florida, have their own product approval and test requirements, and some products are tested for high-velocity hurricane zones.\n\n## Design factors\n\n- Engineering calculations, often based on ASCE 7 in the United States, set design pressures for each roof zone.\n- Clip and fastener spacing is reduced at corners and perimeters, where uplift forces are highest.\n- Locking seams that engage clips firmly (\"active fastening\") help panels pass uplift tests; mechanically seamed double-lock panels typically achieve higher values than unseamed snap-lock panels.\n- Substrate type and fastener pull-out strength matter as much as the panel itself.\n\n## Real-world performance\n\nIndustry reviews of hurricane and tornado damage report that properly engineered and installed metal roofs perform well, while failures usually trace to inadequate attachment at edges, missing clips, weak decks or fasteners driven into poor substrates.\n\n## Using ratings\n\nA rating applies only to the specific tested assembly, including panel, gauge, clip, fastener, spacing and deck. Specifiers should match project details to the tested configuration, and some specifications require wind uplift ratings to meet the local building code.","key_facts":[{"label":"Key tests","value":"ASTM E1592, UL 580, UL 1897"},{"label":"Highest-load zones","value":"Corners, perimeters, ridges"},{"label":"Critical detail","value":"Clip/fastener spacing and substrate"}],"regions":["Global"],"aliases":["ASTM E1592","UL 580","UL 1897","wind uplift rating","metal roof wind rating"],"related":["standing-seam-clips","mechanically-seamed-standing-seam","snap-lock-standing-seam","hail-resistance-metal-roofs"],"company":null,"sources":[{"title":"Myths About Metal Roofing: Heat, Wind and Lightning","url":"https://www.mbci.com/blog/myths-about-metal-roofing/","publisher":"MBCI"},{"title":"DECRA Metal Roofing","url":"https://www.decra.com/","publisher":"DECRA Roofing Systems"},{"title":"Section 07 61 13 Standing Seam Metal Roof (design requirements)","url":"https://designconstruct.cufo.columbia.edu/sites/designconstruct.cufo.columbia.edu/files/content/Design%20Requirements/TMP%20SECTION%2007%2061%2013%20-%20STANDING%20SEAM%20METAL%20ROOF.pdf","publisher":"Columbia University Facilities"}],"country":null},{"slug":"wood-shake","title":"Wood Shake","type":"article","summary":"A thick, rough-textured wooden roofing unit split from a log on at least one face, giving a rugged, deeply shadowed roof.","body":"A wood shake is a wooden roofing unit that has been split, rather than sawn, along the grain on at least one face. Splitting follows the natural fibres of the wood, so shakes have a rough, textured surface and straight, continuous grain, which makes them stronger and less likely to warp than sawn shingles. Shakes are thicker than shingles and produce a heavier, more rustic-looking roof.\n\n## Types\n\nNorth American shakes are classified by how they are made:\n\n- **Handsplit and resawn**: a split blank is run through a band saw diagonally, producing two shakes each with one split face and one sawn back.\n- **Tapersawn**: sawn on both faces from a split block, giving a thick, tapered unit with a smoother surface than a handsplit shake.\n- **Straight-split and tapersplit**: split on both faces; tapersplit shakes are tapered by reversing the block between each split.\n\nThe Cedar Shake & Shingle Bureau's product lines include Certi-Split (handsplit and split shakes) and Certi-Sawn (tapersawn shakes).\n\n## Sizes\n\nNorth American shakes are most commonly 24 in (610 mm) long; 18 in (457 mm) shakes are sometimes called barn shakes, and 48 in (1.2 m) shakes are mainly used for siding.\n\n## Installation features\n\nBecause the rough split surfaces do not lie tightly together, shake roofs traditionally include a strip of roofing felt **interlay** between each course to stop wind-driven rain and snow being blown through the gaps; the Cedar Shake & Shingle Bureau's manual specifies felt interlay for shakes only. Shakes are fixed with corrosion-resistant fasteners and spaced slightly apart to allow for swelling.\n\n## Performance\n\nSplit shakes resist water penetration well along their grain, and their thickness gives them a longer service life than shingles of the same species, provided they can dry. They require more maintenance than many modern roofing materials: debris, moss and lichens must be removed, and shakes that are split or cupped need replacing. Like all wood roofs, untreated shakes are combustible, and pressure-impregnated fire-retardant shakes are required in many fire-prone jurisdictions.\n\n## Alternatives\n\nRubber, plastic and fibre-cement \"shake-look\" products imitate the appearance of wood shakes with lower maintenance, though they lack the natural texture and weathering of real wood.\n","key_facts":[{"label":"Definition","value":"Split on at least one face"},{"label":"Common length","value":"24 in (610 mm)"},{"label":"Types","value":"Handsplit/resawn, tapersawn, straight-split, tapersplit"},{"label":"Special detail","value":"Felt interlay between courses"}],"regions":["North America","Europe"],"aliases":["cedar shake","shake roof","split shake","hand-split shake"],"related":["wood-shingle","tapersawn-shake","handsplit-shake","western-red-cedar","synthetic-shake","rubber-shingle"],"sources":[{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Cedar Shake & Shingle Bureau","url":"https://www.cedarbureau.org/","publisher":"Cedar Shake & Shingle Bureau"},{"title":"Roof Installation Manual","url":"https://www.cedarbureau.org/installation/roof-installation-manual/","publisher":"Cedar Shake & Shingle Bureau"}],"category":"materials","company":null,"country":null},{"slug":"wood-shake-installation","title":"Wood Shake Installation","category":"installation","type":"article","summary":"Wood shake installation lays split cedar shakes in spaced courses with felt interlay between each course, two nails per shake and offset joints.","body":"**Wood shakes** are split (rather than sawn) wooden roofing units, usually of western red cedar in North America. Because a shake's split face is rough and the pieces do not lie tightly together, shake roofs normally use an **interlay** of roofing felt between courses to stop wind-driven rain and snow from passing through the gaps. Shake installation details are published by the Cedar Shake and Shingle Bureau (CSSB) and in building codes and national roofing manuals.\n\n## Underlayment and interlay\n\nCanadian guidance starts with a 1 m (39 in) strip of No. 30 felt at the eave. Each course then receives an interlay strip of No. 30 felt 450 mm (18 in) wide, placed above the shake butts at a distance equal to twice the exposure, so the lower part of the felt is covered by the shakes of the next course. The CSSB warns that felt should not be visible in the gaps between shakes, because sunlight degrades it.\n\n## Spacing and offset\n\n- **Keyways.** Shakes are spaced with a gap between adjacent pieces to allow swelling. The Cedar Shake & Shingle Bureau specifies a gap of 3/8 to 5/8 in (10 to 16 mm) between shakes. The CSSB notes that keyways should never be caulked.\n- **Side lap.** Joints are offset at least 38 mm (1 1/2 in) from those in adjacent courses, and no two joints should line up in any three courses.\n\n## Nailing\n\nCanadian guidance specifies two nails per shake regardless of width, about 25 mm (1 in) in from each edge and about 50 mm (2 in) above the butt line of the following course. Nails must be corrosion resistant; the CSSB requires Type 316 stainless steel fasteners for fire-retardant or preservative-treated shakes.\n\n## Exposure\n\n| Shake length | Max exposure, standard (Canada) |\n|---|---|\n| 600 mm (24 in) | 250 mm (10 in) |\n| 450 mm (18 in) | 189 mm (7 1/2 in) |\n\nShakes are typically used on slopes of 4:12 or steeper. Exposure must not be exceeded, since that reduces the overlap.\n\n## Deck\n\nShakes can be laid on solid sheathing or on spaced boards that allow air to dry the underside. Ridge and hip caps are made from overlapping pairs of shakes with alternating joints.","key_facts":[{"label":"Interlay","value":"No. 30 felt, 450 mm (18 in) wide"},{"label":"Nails per shake","value":"2"},{"label":"Keyway gap (CSSB)","value":"3/8-5/8 in (10-16 mm)"},{"label":"Max exposure, 24 in shake","value":"250 mm (10 in)"}],"regions":["North America"],"aliases":["cedar shake installation","shake roofing","hand-split shake installation"],"related":["wood-shingle-installation","wood-shake","cedar-shake-and-shingle-bureau"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.2.8 Installation of Wood Shakes","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-2-wood-shakes-and-wood-shingles/9-2-8-installation-of-wood-shakes/","publisher":"Canadian Roofing Contractors Association"},{"title":"CSSB Installation Tips","url":"https://www.cedarbureau.org/wp-content/uploads/2020/04/CSSB-installation-tips.pdf","publisher":"Cedar Shake and Shingle Bureau"},{"title":"Wood Shake Roof Installation","url":"https://inspectapedia.com/roof/Wood_Shake_Roof_Installation.php","publisher":"InspectApedia"},{"title":"General Design and Application Details","url":"https://www.cedarbureau.org/wp-content/uploads/2020/05/Page-04-General-Design-and-Application-Details.pdf","publisher":"Cedar Shake & Shingle Bureau"}],"country":null},{"slug":"wood-shingle","title":"Wood Shingle","type":"article","summary":"A thin, tapered piece of wood, sawn on both faces, laid in overlapping courses as a roof or wall covering.","body":"A wood shingle is a thin, tapered piece of wood used in overlapping rows to shed water from a roof or wall. In current North American usage, a **shingle** is sawn smooth on both faces and is thinner and more regular than a **shake**, which is split from the log on at least one face. Historically the two words were used more loosely, and in colloquial speech \"shake\" is still often applied to any wood roof unit.\n\n## Species\n\nDurable, straight-grained, decay-resistant woods are preferred, and traditionally only the heartwood was used, because sapwood rots quickly. In North America the main roofing species are western red cedar, with Alaskan yellow cedar, California redwood and Atlantic white cedar also used. In Scandinavia and central Europe, Scots pine and local spruce are more common, and in Latvia aspen is the most popular shingle wood. Oak shingles are recorded in the history of ancient Gaul and Iberia. In Japan, very thin split shingles fastened with bamboo nails roof temples such as Kinkaku-ji and Ginkaku-ji in Kyoto; Korean shingle-roofed houses are called *neowa-jip*.\n\n## Sizes\n\nNorth American sawn shingles are made in 16, 18 and 24 in (406, 457 and 610 mm) lengths; under the Cedar Shake & Shingle Bureau's grading rules these are known as Fivex, Perfection and Royal respectively. Butts are usually about 3/8 in (10 mm) thick. European shingles vary widely: Scandinavian shingles may be only 13-16 in (33-41 cm) long and about 1/8 in (3 mm) thick, while Polish and Slovak shingles can be around 36 in (91 cm) long and over 1 in (25 mm) thick.\n\n## History\n\nBefore the 19th century, shingles were split by hand from straight, knot-free blocks with a froe and mallet, then smoothed with a drawknife. Steam-powered sawmills in the early 19th century made uniform sawn shingles cheap and plentiful, and wood shingles remained common in North America into the 20th century, including on Colonial Revival and Tudor Revival houses. In many cities, fire risk led authorities to restrict wood roofs in favour of slate, tile or metal.\n\n## Performance\n\nShingles are thinner than shakes and generally less durable, especially in wet climates. They need good ventilation underneath so they can dry after rain; many installers lay them on spaced battens or a ventilating mat. Wood shingles can be treated with preservatives and fire retardants before or after installation; untreated wood roofs are restricted in many wildfire-prone areas. Wood shake is among the coverings typically used at pitches of about 3:12 (14°) or steeper.\n\n## Weathering\n\nUntreated cedar weathers from reddish-brown to silver-grey within a few years. Moss, lichen and debris that hold moisture shorten life, so regular cleaning is part of normal maintenance.\n","key_facts":[{"label":"Definition (North America)","value":"Sawn on both faces; thinner than a shake"},{"label":"Main species (N. America)","value":"Western red cedar; also Alaskan yellow cedar, redwood"},{"label":"Standard lengths","value":"16, 18, 24 in (406, 457, 610 mm)"},{"label":"Grading body (N. America)","value":"Cedar Shake & Shingle Bureau"}],"regions":["North America","Europe","East Asia","Global"],"aliases":["cedar shingle","wooden shingle","sawn shingle"],"related":["wood-shake","western-red-cedar","alaskan-yellow-cedar","cedar-shake-and-shingle-bureau","tapersawn-shake","handsplit-shake"],"sources":[{"title":"Wood shingle","url":"https://en.wikipedia.org/wiki/Wood_shingle","publisher":"Wikipedia"},{"title":"Cedar Shake & Shingle Bureau","url":"https://www.cedarbureau.org/","publisher":"Cedar Shake & Shingle Bureau"},{"title":"Roof","url":"https://en.wikipedia.org/wiki/Roof","publisher":"Wikipedia"}],"category":"materials","company":null,"country":null},{"slug":"wood-shingle-installation","title":"Wood Shingle Installation","category":"installation","type":"article","summary":"Wood shingle installation lays sawn cedar shingles in triple-coverage courses with small gaps, two nails each and exposures set by length and pitch.","body":"**Wood shingles** are sawn, tapered pieces of wood, usually western red cedar in North America and other durable species elsewhere. Unlike shakes, they are smooth and lie close together, so they are normally installed without felt interlay and give roughly three layers of coverage at any point.\n\n## Deck\n\nWood shingles can be laid on solid sheathing or on spaced (skip) sheathing. With spaced boards, Canadian guidance sets the board spacing equal to the shingle exposure so that each course has a board to nail into.\n\n## Spacing and edges\n\n- A gap of about 6.4 mm (1/4 in) between shingles allows them to swell when wet without buckling.\n- Side laps between successive courses are at least 38 mm (1 1/2 in), and joints separated by only one course should not line up.\n- Eave overhang is about 32-38 mm (1 1/4-1 1/2 in) and rake overhang about 19-25 mm (3/4-1 in).\n- The first course is doubled (or tripled) at the eave.\n\n## Exposure\n\nCanadian guidance, drawing on Cedar Shake and Shingle Bureau grades, gives maximum exposures for No. 1 grade shingles:\n\n| Length | Pitch 4:12 or steeper | Pitch 3:12 to under 4:12 |\n|---|---|---|\n| 400 mm (16 in) | 125 mm (5 in) | 95 mm (3 4/5 in) |\n| 450 mm (18 in) | 140 mm (5 1/2 in) | 100 mm (4 in) |\n| 600 mm (24 in) | 189 mm (7 1/2 in) | 146 mm (5 4/5 in) |\n\nLower grades require less exposure.\n\n## Nailing\n\n- Two nails per shingle regardless of width, within about 19 mm (3/4 in) of each edge.\n- Nails placed high enough to be covered by the next course; nailing too high or too far from the edges encourages curling.\n- Corrosion-resistant nails only: hot-dip galvanized, aluminium or stainless steel. Plain steel nails stain and fail.\n- Typical sizes are 3d for 16 and 18 in shingles and 4d for 24 in shingles, with longer nails for re-roofs and ridges.\n\n## Ridge and hips\n\nRidges are formed from pairs of shingles with alternating overlaps, fastened with two nails per side and laid at the same exposure as the field.","key_facts":[{"label":"Gap between shingles","value":"About 6.4 mm (1/4 in)"},{"label":"Nails per shingle","value":"2"},{"label":"Max exposure, 18 in No. 1 at 4:12+","value":"140 mm (5 1/2 in)"}],"regions":["North America","Europe"],"aliases":["cedar shingle installation","sawn shingle installation"],"related":["wood-shake-installation","wood-shingle","cedar-shake-and-shingle-bureau"],"company":null,"sources":[{"title":"Canadian Roofing Reference Manual: 9.2.7 Installation of Wood Shingles","url":"https://roofingcanada.com/docs/canadian-roofing-reference-manual/chapter-9-steep-slope-roofing/9-2-wood-shakes-and-wood-shingles/9-2-7-installation-of-wood-shingles/","publisher":"Canadian Roofing Contractors Association"},{"title":"CSSB Installation Tips","url":"https://www.cedarbureau.org/wp-content/uploads/2020/04/CSSB-installation-tips.pdf","publisher":"Cedar Shake and Shingle Bureau"}],"country":null},{"slug":"wooden-churches-of-southern-malopolska","title":"Wooden Churches of Southern Małopolska","type":"place","summary":"Six medieval log churches in southern Poland with tall, steep shingled roofs; inscribed as a UNESCO World Heritage site in 2003.","body":"The Wooden Churches of Southern Małopolska are a group of six Roman Catholic churches in southern Poland, built using horizontal log construction and covered with tall, steep roofs of wooden shingles. UNESCO inscribed them on the World Heritage List in 2003 as some of the best preserved and oldest wooden Gothic churches in the region. They stand in Blizne, Binarowa, Dębno Podhalańskie, Haczów, Lipnica Murowana and Sękowa.\n\n## Construction\n\nThe churches use the horizontal log technique, common in northern and eastern Europe in the Middle Ages, in which squared logs are laid one on another and joined at the corners. A single steep roof often covers both the nave and the chancel. Roof trusses tie the log structures of the two parts together and stiffen the whole building, and the listing notes king-post trusses among the original structural elements.\n\n## Shingle roofs\n\nThe roofs, and often the walls and towers, are clad with hand-split wooden shingles. Steep pitches shed rain and snow quickly, and the overlapping shingles allow the timber to dry between wet spells. Shingle cladding has to be renewed periodically, and conservation work aims to replace it in kind using split, not sawn, timber.\n\n## Regional context\n\nThe churches belong to a wider tradition of wooden sacred architecture in the Carpathian region. In 2013 UNESCO separately inscribed the Wooden Tserkvas of the Carpathian Region in Poland and Ukraine, a group of 16 log churches, eight in each country.\n\n## Why they matter for roofing\n\nThese buildings show how a timber-rich region solved roofing without clay or metal: a steep, continuous roof plane, deep overhangs and a renewable covering of split wood. The same principles appear across the wider Carpathian timber-building tradition.","key_facts":[{"label":"Location","value":"Lesser Poland (Małopolska) and Subcarpathia, Poland"},{"label":"Number of churches","value":"Six"},{"label":"Structure","value":"Horizontal log, king-post roof trusses"},{"label":"Roof covering","value":"Wooden shingles"},{"label":"UNESCO inscription","value":"2003"}],"regions":["Europe"],"aliases":["Drewniane kościoły południowej Małopolski","Wooden Gothic churches of Poland"],"related":["wood-shingle","roofing-in-poland-and-eastern-europe","schindel","king-post-truss"],"sources":[{"title":"Wooden Churches of Southern Małopolska","url":"https://whc.unesco.org/en/list/1053","publisher":"UNESCO World Heritage Centre"},{"title":"Wooden Churches of Southern Małopolska","url":"https://zabytek.pl/en/obiekty/drewniane-koscioly-poludniowej-malopolski","publisher":"National Heritage Board of Poland (zabytek.pl)"}],"company":null,"category":"world-roofing","country":null},{"slug":"wooden-tserkva-roofs","title":"Wooden Tserkva Roofs of the Carpathians","category":"world-roofing","type":"article","summary":"Shingle-clad tiered domes and pyramidal roofs of the Orthodox and Greek Catholic log churches (tserkvas) of the Carpathians in Poland, Ukraine and Slovakia.","body":"A *tserkva* is an Eastern-rite wooden church of the Carpathian region, built by Orthodox and Greek Catholic communities. Their roofs are a defining feature: stacked, tiered domes and pyramids of timber, clad together with the walls in wooden shingles. In 2013 UNESCO inscribed 16 of these churches, eight in Poland and eight in Ukraine, as the Wooden Tserkvas of the Carpathian Region.\n\n## Construction\n\nThe tserkvas are built of horizontal logs and date from the 16th to the 19th centuries. They usually have a tripartite plan, with three log chambers in a row, each crowned by an open quadrilateral or octagonal dome or a pyramidal roof. Builders recorded construction dates and carpenters' names in inscriptions on the door lintels.\n\nWooden shingles cover both roofs and walls. This cladding wears out and, according to UNESCO, has to be replaced every 20 to 30 years.\n\n## Regional types\n\nUNESCO groups the listed churches into four traditions, each with its own roof profile:\n\n- **Hutsul:** Nyzhnii Verbizh and Yasinia in Ukraine.\n- **Boyko:** Smolnik in Poland and Uzhok and Matkiv in Ukraine, on both sides of the border.\n- **Lemko:** Powroźnik, Brunary Wyżne, Owczary, Kwiatoń and Turzańsk in the western Polish Carpathians.\n- **Halych:** Rohatyn, Drohobych, Zhovkva and Potelych in Ukraine, and Radruż and Chotyniec in Poland.\n\n## Slovakia\n\nEight wooden churches in the Slovak part of the Carpathians, two Roman Catholic, three Protestant and three described by UNESCO as Greek Orthodox, built between the 16th and 18th centuries, form a separate UNESCO World Heritage Site and share the shingle-clad timber tradition.\n\n## Relationship to other wooden churches\n\nThe tserkvas belong to the same Carpathian timber tradition as the Gothic Roman Catholic Wooden Churches of Southern Małopolska and the wooden churches of Maramureș in Romania, but their Eastern-rite plans produce a different roofscape: several separate domes rather than one long, steep roof. See Wooden Churches of Southern Małopolska and Maramureș church roofs.\n\n## Care\n\nBecause the shingles, the main protection for the timber, last only a few decades, the survival of these churches depends on a continuing supply of suitable wood and of carpenters who can split and lay shingles by hand.","key_facts":[{"label":"UNESCO inscription","value":"2013, 16 churches (8 Poland, 8 Ukraine)"},{"label":"Built","value":"16th-19th centuries"},{"label":"Roof cladding","value":"Wooden shingles on roofs and walls"},{"label":"Shingle renewal","value":"Every 20-30 years"}],"regions":["Europe"],"aliases":["tserkva","cerkiew","Carpathian wooden churches","Lemko church roofs","Boyko church roofs","Hutsul church roofs"],"related":["wooden-churches-of-southern-malopolska","maramures-church-roofs","wood-shingle","roofing-in-poland","roofing-in-ukraine","roofing-in-slovakia","aspen-ploughshare-shingles","onion-dome"],"company":null,"sources":[{"title":"Wooden Tserkvas of the Carpathian Region in Poland and Ukraine","url":"https://whc.unesco.org/en/list/1424","publisher":"UNESCO World Heritage Centre"},{"title":"Wooden Tserkvas of the Carpathian Region in Poland and Ukraine","url":"https://en.wikipedia.org/wiki/Wooden_Tserkvas_of_the_Carpathian_Region_in_Poland_and_Ukraine","publisher":"Wikipedia"},{"title":"Wooden Churches of the Slovak part of the Carpathian Mountain Area","url":"https://whc.unesco.org/en/list/1273","publisher":"UNESCO World Heritage Centre"}],"country":null},{"slug":"work-at-height-regulations-2005","title":"Work at Height Regulations 2005","category":"installation","type":"standard","summary":"The Work at Height Regulations 2005 are the main UK law on preventing falls, requiring a hierarchy of avoid, prevent and minimise for all work at height.","body":"The **Work at Height Regulations 2005** (SI 2005/735) are the principal regulations in Great Britain for preventing death and injury from falls. They apply to employers and to anyone who controls work at height, including facilities managers and building owners who hire contractors. Roof work is one of the activities most affected: the Health and Safety Executive (HSE) reports that almost one in five construction deaths involve roof work.\n\n## The hierarchy (regulation 6)\n\nRegulation 6 sets out a three-step approach:\n\n1. **Avoid** work at height where it is reasonably practicable to do the work safely another way, for example from the ground.\n2. **Prevent** falls where work at height cannot be avoided, using an existing safe place of work or suitable work equipment such as scaffolds and guardrails.\n3. **Minimise** the distance and consequences of a fall where the risk cannot be eliminated, using work equipment such as safety nets or fall arrest systems, together with training and instruction.\n\n## Duties\n\nDuty holders must ensure that work at height is properly planned, appropriately supervised and carried out by competent people with suitable equipment. Risks must be assessed first, and simple, low-risk tasks need less planning than complex ones. Employees must take reasonable care and cooperate with their employer.\n\n## Application to roof work\n\nHSE roof work guidance, together with its publication **HSG33, Health and safety in roofwork**, applies the regulations to roofing:\n\n- **Sloping roofs:** scaffolding or edge protection at the eaves, including the rear of terraced houses; secured ladders and roof ladders only for short tasks lasting minutes.\n- **Flat roofs:** secure double guardrails and toeboards around the edge.\n- **Fragile roofs:** treat every roof as fragile until confirmed otherwise by a competent person; use stagings, guard rails, nets or harness systems, and protect fragile rooflights with secured, labelled covers or barriers.\n\n## Enforcement\n\nThe HSE and local authorities enforce the regulations. Prosecutions following falls through fragile roofs and rooflights are regularly publicised.","key_facts":[{"label":"Statutory instrument","value":"SI 2005/735"},{"label":"Hierarchy","value":"Avoid, prevent, minimise (regulation 6)"},{"label":"HSE roofing guide","value":"HSG33 Health and safety in roofwork"}],"regions":["Europe"],"aliases":["WAHR 2005","Work at Height Regs","WAH Regulations"],"related":["roofing-fall-protection","fragile-roof","australian-whs-roof-work","health-and-safety-executive"],"company":null,"sources":[{"title":"The Work at Height Regulations 2005, regulation 6","url":"https://www.legislation.gov.uk/uksi/2005/735/regulation/6","publisher":"legislation.gov.uk"},{"title":"Work at height: the law","url":"https://www.hse.gov.uk/work-at-height/the-law.htm","publisher":"Health and Safety Executive (UK)"},{"title":"Roof work","url":"https://hse.gov.uk/construction/safetytopics/roofwork.htm","publisher":"Health and Safety Executive (UK)"}],"country":null},{"slug":"xps-insulation","title":"XPS (Extruded Polystyrene) Roof Insulation","category":"low-slope-systems","type":"term","summary":"Closed-cell polystyrene foam board made by extrusion, with low water absorption, used above the membrane in inverted and green roofs.","body":"Extruded polystyrene (XPS) is rigid foam insulation produced by forcing molten polystyrene with a blowing agent through a die, forming continuous boards with a fine closed-cell structure and a smooth skin. The best-known brand, Dow's Styrofoam, was patented in 1944, and the name is often used loosely in North America for all polystyrene foams.\n\n## Properties\n\n- **Density:** about 28-34 kg/m3 (1.7-2.1 lb/ft3).\n- **Thermal conductivity:** about 0.029-0.039 W/(m.K), averaging roughly 0.035.\n- **Vapour resistance factor:** about 80-250, higher than EPS.\n- **Water resistance:** low absorption compared with EPS, which is why XPS is chosen where insulation will be wet, though prolonged immersion or humidity can still raise moisture content.\n- **Compressive strength:** grades are made for foot traffic, paving, parking decks and green roofs.\n\n## Use in inverted roofs\n\nXPS is the standard insulation for protected membrane (inverted) roofs, where it sits above the waterproofing, is wetted by rain, and is held down by ballast, paving or soil. Boards often have shiplapped edges, and a water flow reducing layer may be laid on top. Design must allow for rainwater cooling and include ballast to prevent flotation.\n\n## Blowing agents\n\nXPS was historically blown with HFCs such as HFC-134a, which have high global-warming potential. In Europe, where HFC-134a was banned in XPS from 2022, manufacturers use carbon dioxide, giving a global-warming potential below 5.\n\n## Fire\n\nLike EPS, XPS is combustible and is typically protected by ballast, paving or a non-combustible layer on roofs.\n\n## Trademark use\n\nStrictly, Styrofoam refers only to Dow's extruded closed-cell product, which Dow developed from a method first patented in the early 1930s by Carl Munters.","key_facts":[{"label":"Density","value":"About 28-34 kg/m3 (1.7-2.1 lb/ft3)"},{"label":"Conductivity","value":"About 0.029-0.039 W/(m.K)"},{"label":"Typical use","value":"Inverted (protected membrane) roofs"},{"label":"Styrofoam patent","value":"1944 (Dow)"}],"regions":["Global"],"aliases":["XPS","extruded polystyrene","Styrofoam (trademark)"],"related":["protected-membrane-roof","eps-insulation","roof-insulation","green-roof"],"company":null,"sources":[{"title":"Polystyrene","url":"https://en.wikipedia.org/wiki/Polystyrene","publisher":"Wikipedia"},{"title":"Inverted roof","url":"https://www.designingbuildings.co.uk/wiki/Inverted_roof","publisher":"Designing Buildings Wiki"},{"title":"Flat roof","url":"https://en.wikipedia.org/wiki/Built-up_roof","publisher":"Wikipedia"}],"country":null},{"slug":"yakhchal","title":"Yakhchāl","category":"history","type":"term","regions":["Middle East"],"company":null,"summary":"A Persian ice house: a tall domed earth structure over a deep pit, used to store ice through the desert summer.","aliases":["yakhchal","Persian ice house","ice pit","yakh-chal"],"body":"A yakhchāl (Persian for \"ice pit\") is a traditional ice house of the Iranian plateau. Above ground it appears as a tall, usually conical dome of earth; below ground it covers a deep storage pit where ice made or collected in winter was kept into the hot season. Records point to such structures as far back as about 400 BC.\n\n## The dome\n\nThe dome is the yakhchāl's roof and its cooling machine. Its tall, tapering form encourages warm air to rise and escape at the top, working like a solar chimney, while cooler air settles toward the pit. The Kerman yakhchāl is cone-shaped and about 18 m (59 ft) high.\n\n## Sarooj\n\nWalls and domes were built of *sarooj*, a water-resistant mortar of sand, clay, lime, ash, goat hair and egg whites mixed in set proportions. Sarooj resists heat transfer, and walls were made at least 2 m (6.5 ft) thick at the base. Underground storage could reach about 5,000 m³ (180,000 cu ft).\n\n## Making the ice\n\nNext to many yakhchāls ran long shade walls, often about 10 m (33 ft) and sometimes 15 m (49 ft) high, protecting shallow ice pools. Water, often brought by qanat, was let into the channels to freeze on clear winter nights, when dry air allows heat to radiate to the sky. Ice was also carried down from nearby mountains. Some sites used windcatchers (*bâdgir*) to draw air over the store.\n\n## Where they survive\n\nMost examples are in the desert regions of the Dasht-e Lut and Dasht-e Kavir, at places such as Abarkuh, Meybod, Sirjan, Kowsar and Kerman. Many have decayed but some are well preserved. In modern Persian, and in Afghanistan and Tajikistan, the word now also means \"refrigerator\".","key_facts":[{"label":"Function","value":"Ice storage through summer"},{"label":"Earliest records","value":"C. 400 BC"},{"label":"Material","value":"Sarooj mortar"},{"label":"Wall thickness at base","value":"At least 2 m (6.5 ft)"},{"label":"Kerman example height","value":"About 18 m (59 ft)"}],"related":["roofing-in-iran","badgir","middle-eastern-domes","dome","history-of-cool-roofs"],"sources":[{"title":"Yakhchāl","url":"https://en.wikipedia.org/wiki/Yakhch%C4%81l","publisher":"Wikipedia"},{"title":"Iranian architecture","url":"https://en.wikipedia.org/wiki/Iranian_architecture","publisher":"Wikipedia"}],"country":null},{"slug":"yealming","title":"Yealming","category":"installation","type":"term","summary":"Yealming is the preparation of wetted long straw into neat, compact layers called yealms that a thatcher can carry onto the roof and lay.","body":"**Yealming** is the ground-level preparation of **long straw** for thatching. Threshed straw is wetted, drawn out and straightened, and then gathered into tidy, compact layers with both ends level. Each prepared layer is a **yealm** (also spelled **yelm** or **yealm**), which the Thatching Advisory Services glossary describes as a prepared bundle used like a thick roof tile. \n\n## Why it is needed\n\nLong straw, unlike combed wheat reed, is not combed after threshing. The stalks keep their ears and are mixed in direction, length and alignment. Without yealming, the straw would be too loose and irregular to lay evenly. Yealming produces a manageable unit with a consistent thickness, so each course can be fixed and shaped neatly.\n\n## Process outline\n\n1. Wet the threshed straw thoroughly so it becomes supple and easier to handle.\n2. Draw the straw out by hand, removing short material and debris and laying the stalks parallel.\n3. Build up a tight, compact layer with both ends level.\n4. Gather the finished yealm and carry it up to the roof, where it is laid and fixed with hazel spars.\n\nBuilding Conservation describes the aim as straightening and tidying the straw into a tight, compact layer that is level at both ends, which makes it manageable on the roof.\n\n## Appearance\n\nBecause long straw is laid with heads and butts in mixed directions and the surface is not dressed with a legget, long straw roofs have a softer, shaggier look than reed roofs. They are typically fixed with hazel spars and finished with liggers along the eaves, gables and ridge.\n\n## Regional use\n\nLong straw was once used across the main corn-growing areas of England from Dorset northwards. Today it is found mainly in East Anglia, with examples elsewhere, and is a recognised regional tradition that heritage authorities often wish to preserve on listed buildings.","key_facts":[{"label":"Material","value":"Long straw (threshed, uncombed)"},{"label":"Product","value":"Yealm (prepared layer)"},{"label":"Region of use (England)","value":"Mainly East Anglia today"}],"regions":["Europe"],"aliases":["yelming","yealm","yelm"],"related":["thatching-process","thatch-ridge","thatch"],"company":null,"sources":[{"title":"Thatched Roofs: An Introduction","url":"https://buildingconservation.com/articles/thatchrf/thatchrf.htm","publisher":"Building Conservation"},{"title":"Thatching Terms","url":"https://thatchingadvisoryservices.co.uk/thatching-terms","publisher":"Thatching Advisory Services"},{"title":"Types of thatching","url":"https://www.lookingatbuildings.org.uk/construction/materials/thatch/types-of-thatching.html","publisher":"Looking at Buildings (Pevsner Architectural Guides)"}],"country":null},{"slug":"yingzao-fashi","title":"Yingzao Fashi","category":"history","type":"standard","summary":"The Yingzao Fashi is a Chinese building manual by Li Jie, published in 1103, that standardised timber framing, bracketing, tiling and glazes.","body":"The *Yingzao Fashi* (營造法式, \"Treatise on Architectural Methods\" or \"State Building Standards\") is a technical manual of the Song dynasty, compiled by the official Li Jie (1065-1110) of the Directorate of Buildings and Construction. It is the oldest complete Chinese building manual to survive and the key source for how the roofs of Song-period halls were designed and built.\n\n## Compilation and editions\n\nLi Jie revised older building treatises from 1097 to 1100 and completed his own text by 1100, presenting it to Emperor Zhezong. Emperor Huizong had it published in **1103**. A second edition followed in 1145, and a third printing was made at Pingjiang (modern Suzhou) in 1222-1233; this was later copied into the great imperial compilations, the Yongle Encyclopedia and the Siku Quanshu. A hand-copy of the Pingjiang edition was rediscovered in 1919 and printed in facsimile in 1920, which made the text available to modern architectural historians.\n\n## Contents\n\nThe manual has **34 chapters**. It covers units of measurement, earthworks and fortifications, stonework, and \"greater\" and \"lesser\" woodwork, with specifications and drawings for bracket sets and column-and-beam joints. It also covers carving, bamboo work, wall building, painting and decoration, and **tiling**, including formulas for glazes and coatings and mixing proportions for mortars and glazed tile. A glossary defines technical terms, and labour tables give cost estimates based on a day's work.\n\n## The cai-fen module\n\nThe best-known feature of the manual is its modular system for timber, known as *cai-fen*. Timber member sizes were graded in eight standard ranks, so that the scale of beams, brackets and other parts followed from the rank chosen for a building. The Tang-period East Hall of Foguang Temple (857) corresponds closely to a seventh-rank building in this system.\n\n## Roofs and tiles\n\nFor roofing, the *Yingzao Fashi* standardised tile manufacture and set out the terminology, elements and dimensions of ridge-end ornaments (*chiwen*). Song tiling practice overlapped plain tiles by about 40 per cent; later Qing rules increased this to about 70 per cent to stop leaks through cracked tiles.\n\n## Significance\n\nThe manual records the building practice of a single dynasty in detail and allows surviving halls, such as Foguang Temple, to be compared with an official standard. It remains the starting point for the study of Chinese roof construction.","key_facts":[{"label":"Author","value":"Li Jie (1065-1110)"},{"label":"Published","value":"1103, Song dynasty"},{"label":"Length","value":"34 chapters"},{"label":"Module","value":"Cai-fen system, 8 ranks of timber size"},{"label":"Rediscovered","value":"1919 copy, facsimile 1920"}],"regions":["East Asia"],"aliases":["Ying Zao Fa Shi","Treatise on Architectural Methods","State Building Standards"],"related":["dougong","chiwen","chinese-glazed-roof-tiles","roofing-in-china","history-of-roofing","china-roofing-codes"],"company":null,"sources":[{"title":"Yingzao Fashi","url":"https://en.wikipedia.org/wiki/Yingzao_Fashi","publisher":"Wikipedia"},{"title":"Foguang Temple","url":"https://en.wikipedia.org/wiki/Foguang_Temple","publisher":"Wikipedia"},{"title":"Chinese glazed roof tile","url":"https://en.wikipedia.org/wiki/Chinese_glazed_roof_tile","publisher":"Wikipedia"},{"title":"Chiwen","url":"https://en.wikipedia.org/wiki/Chiwen","publisher":"Wikipedia"}],"country":null},{"slug":"zinc-and-copper-strips","title":"Zinc and Copper Strips","category":"problems-maintenance","type":"term","summary":"Metal strips fixed near a roof's ridge whose rain runoff carries metal ions that discourage moss, algae and lichen below.","body":"Zinc and copper strips are narrow bands of sheet metal installed along or just below a roof's ridge to slow the growth of moss, algae and lichen. When rain runs over the metal, small amounts of zinc or copper dissolve and are carried down the roof, where the metal ions inhibit the organisms. The same effect explains why areas directly below galvanised flashings, copper vents or chimney flashings often stay clean while the rest of the roof turns green or black.\n\n## Installation\n\nStrips are usually fixed along both sides of the ridge, with the lower edge exposed to rain. Guidance from horticultural libraries describes nailing them roughly every foot (about 300 mm), and fasteners should be placed where they are covered or sealed to avoid leaks. On long slopes, some installers add a second row lower down, because the effect weakens with distance from the strip. Copper and zinc should not be placed where their runoff will reach incompatible metals, such as aluminium or galvanised gutters in the case of copper.\n\n## Effectiveness\n\n- Strips work best as **prevention** on a clean roof or after existing moss has been removed; they are slow to clear established growth.\n- Effectiveness varies with the amount of metal exposed, rainfall and roof length. University of Washington library material notes that many commercial strips work for around a year, while larger galvanised flashings can continue for decades.\n- Copper is generally considered more toxic to moss and algae than zinc, but is more expensive.\n\n## Environmental notes\n\nZinc and copper in roof runoff are pollutants, and both are toxic to aquatic life at sufficient concentrations. Extension and environmental sources advise directing runoff away from ponds, streams and sensitive plants, and avoiding use with strong acids or bases. Some local authorities regulate metal-bearing runoff or discourage zinc products near waterways. The US Environmental Protection Agency lists zinc metal strips among minimum-risk pesticides.\n\n## Related products\n\nAlgae-resistant asphalt shingles use copper-treated granules for a similar effect spread across the whole roof.","key_facts":[{"label":"Placement","value":"Along or just below the ridge"},{"label":"Best use","value":"Preventing regrowth after cleaning"},{"label":"Environmental caution","value":"Metal runoff is toxic to aquatic life"}],"regions":["Global","North America","Europe","Oceania"],"aliases":["zinc strips","copper strips","moss strips"],"related":["roof-moss","roof-algae","lichen-on-roofs","roof-cleaning","copper-roofing"],"company":null,"sources":[{"title":"On-roof moss removal","url":"https://depts.washington.edu/hortlib/pal/on-roof-moss-removal/","publisher":"University of Washington Elisabeth C. Miller Library"},{"title":"Preventing Roof Moss with Zinc Strips","url":"https://www.thisoldhouse.com/roofing/preventing-roof-moss-with-zinc-strips","publisher":"This Old House"},{"title":"Chemical Moss Control for Roofs, Decks, and Sidewalks","url":"https://bryophytes.science.oregonstate.edu/page24.htm","publisher":"Oregon State University"}],"country":null},{"slug":"zinc-roofing","title":"Zinc Roofing (Titanium-Zinc)","category":"materials","type":"article","summary":"Zinc roofing uses an alloy of zinc with small amounts of copper and titanium that weathers to a self-healing blue-grey patina and is common in Europe.","body":"Architectural zinc, often called titanium-zinc, is nearly pure zinc alloyed with small additions of copper and titanium. It is used for standing seam roofs, wall cladding, gutters and flashings, and is especially traditional in France, Belgium, Germany and the Netherlands. Paris rooftops, many dating from the late nineteenth century under Napoleon III, are still largely zinc.\n\n## Alloy and standard\n\nBuilding zinc is made to the European standard EN 988. Typical trace contents are copper about 0.08 to 1.0%, titanium about 0.06 to 0.2% and aluminium under 0.015%. Copper raises strength; titanium improves resistance to creep, the slow downhill stretching that soft metals suffer on a roof.\n\n## Patina\n\nBright zinc reacts with moisture and carbon dioxide to form a grey layer of zinc hydroxy-carbonate, typically over 2 to 5 years and faster in polluted air. The layer heals itself when scratched. Factory pre-weathered zinc gives the grey colour from the start.\n\n## Design rules\n\n- **Ventilation**: moisture trapped on the underside causes white corrosion. Zinc is laid over ventilated decks, drainage mats or skip sheathing, or uses a factory backside coating.\n- **Thermal movement**: zinc moves about 1 in per 30 ft (roughly 25 mm per 9 m); roofs combine a fixed zone with sliding clips.\n- **Cold forming**: zinc can crack if folded below about 7 degrees C (45 degrees F); installers warm it in cold weather.\n- **Contamination**: salt spray, acid rain and masonry dust can mark or accelerate corrosion.\n- **Compatibility**: copper run-off and contact with copper should be avoided.\n\n## Life and environment\n\nA properly installed zinc roof is commonly cited at 60 to 100 years, with weathering rates of about 1 to 7 micrometres per year depending on pollution. Zinc is widely recycled and needs less energy to refine than aluminium, copper or steel.","key_facts":[{"label":"Standard","value":"EN 988"},{"label":"Alloying elements","value":"Copper (0.08-1.0%), titanium (0.06-0.2%)"},{"label":"Natural patina time","value":"About 2-5 years"},{"label":"Cited service life","value":"60-100 years"}],"regions":["Europe","Global"],"aliases":["titanium zinc","titanium-zinc roofing","architectural zinc","zinc standing seam"],"related":["pre-weathered-zinc","ventilation-under-metal-roofs","creep-in-sheet-metal","thermal-movement-in-metal-roofs","standing-seam-metal-roof"],"company":null,"sources":[{"title":"Essential Zinc: Building for the Future","url":"https://continuingeducation.bnpmedia.com/courses/umicore-building-products-usa-inc/essential-zinc-building-for-the-future/2/","publisher":"Continuing Education Center (BNP Media) / Umicore Building Products"},{"title":"Pre-weathered zinc: durable and truly maintenance free","url":"https://www.nedzink.com/en/pre-weathered-zinc-durable-and-truly-maintenance-free/","publisher":"NedZink"},{"title":"Durability: Compatibility (NZ Metal Roof and Wall Cladding Code of Practice)","url":"https://www.metalroofing.org.nz/cop/durability/compatibility","publisher":"NZ Metal Roofing Manufacturers"}],"country":null},{"slug":"zinc-roofs-of-paris","title":"Zinc Roofs of Paris","category":"history","type":"place","summary":"The grey zinc roofscape of Paris, established in the mid-19th century under Napoleon III and Haussmann and proposed for UNESCO listing since 2014.","body":"The grey roofs of Paris, sheathed in zinc and slate and punctuated by chimney pots and dormer windows, are one of the world's best-known urban roofscapes. They largely date from the transformation of the city in the mid-19th century.\n\n## Origins\n\nMetallic zinc became available as an industrial building material in the early 19th century. In 1806 the Napoleonic authorities granted the Belgian industrialist Jean-Jacques Dony the right to work the zinc deposit at La Vieille Montagne near Liège. The Société des Mines et Fonderies de Zinc de la Vieille-Montagne, founded in 1837, became a major producer of rolled zinc for building. Its rolled-zinc business continues today under the VMZinc brand, now part of Umicore.\n\n## The Haussmann era\n\nThe typical Parisian combination of zinc, slate and green-tinged metalwork became established under Napoleon III's Second Empire (1852-1870), during Baron Haussmann's rebuilding of the city. Haussmannian apartment blocks spread quickly along the new boulevards. Zinc suited them well: it was inexpensive, easy to cut, solder and form, and light enough to allow lighter roof frames over the mansard attics that the building rules encouraged.\n\n## Mansards and height rules\n\nA 1783 rule limited Paris buildings to a height of 20 m (66 ft) measured to the cornice, so space inside a roof did not count. Mansard roofs, steep on the lower slope and shallow above, created extra rooms within the roof. A 1902 revision allowed three or four storeys within the roof envelope. Zinc covered the flatter upper slopes and many of the dormers.\n\n## The roofers\n\nThe roofs are maintained by *couvreurs-zingueurs*, roofers who cut, solder and fit zinc and slate.\n\n## UNESCO proposal\n\nSince 2014 the roofs of Paris have been the subject of a proposed World Heritage inscription. The Paris Council approved the project in October 2014, and a support committee was launched on 5 February 2015.\n\n## Legacy\n\nThe Paris roofscape is closely tied to the mansard form named after François Mansart and to the rolled-zinc industry that grew up in Belgium in the 19th century. Zinc remains a widely used architectural roofing metal.","key_facts":[{"label":"Main period","value":"Second Empire, 1852-1870"},{"label":"Paris height rule","value":"20 m (66 ft) to cornice, 1783"},{"label":"UNESCO project","value":"Approved by Paris Council, October 2014"},{"label":"Vieille-Montagne founded","value":"1837"}],"regions":["Europe"],"aliases":["Paris rooftops","toits de Paris","Parisian zinc roofs"],"related":["mansard-roof-history","zinc-roofing","history-of-standing-seam-roofing","francois-mansart"],"company":null,"sources":[{"title":"Toits de Paris","url":"https://fr.wikipedia.org/wiki/Toits_de_Paris","publisher":"Wikipédia (French)"},{"title":"Vieille Montagne","url":"https://en.wikipedia.org/wiki/Vieille_Montagne","publisher":"Wikipedia"},{"title":"Mansard roof","url":"https://en.wikipedia.org/wiki/Mansard_roof","publisher":"Wikipedia"}],"country":null},{"slug":"zulu-beehive-hut","title":"Zulu Beehive Hut","category":"world-roofing","type":"article","summary":"Hemispherical Zulu dwelling (indlu) of bent sapling arches covered in two layers of grass thatch, tied down by ropes gathered at an apex top-knot.","body":"The traditional Zulu dwelling of KwaZulu-Natal, South Africa, is a hemispherical, or \"beehive\", house in which roof and wall are one continuous surface of grass thatch over a frame of bent saplings. The general isiZulu word for a dwelling is *indlu*, and the homestead that groups several dwellings is the *umuzi*. The architectural historian Franco Frescura recorded the parts of the house in detail, and his glossary is the principal source for the terms below.\n\n## Frame\n\nThe frame is a lattice of arches made from saplings (*izintingo*):\n\n- The first arch is built over the front door (*ikotamo*).\n- Two arches (*imiqolo*) spring back from either side of the door arch.\n- The highest arch (*inqo*) runs parallel to the door arch; together with the imiqolo it sets the height and direction of the dome.\n\nOn plan, the house has a front point (*omnyango*), a back point (*ofundo*) and two side points (*isintini*). Inside, timber posts beside the hearth (*izinsika*) carry a trellis (*imishayo*) that supports the thatcher's weight while the dome is built.\n\n## Thatch\n\nGrass is applied in two layers: an inner insulating layer (*umfuguzelo*) and an outer layer (*umxhebulo*). Ropes hold the thatch down and are gathered at the apex into a top-knot (*isiqongo*), for which a fine thatching grass (*inca ebomvana*) is used. Inside, a large woven grass mat (*isihlandla*) forms the main ceiling at the apex, with further mats (*umyagazo*) beside it, which are also wound around the lower wall as a protective skirt. Hard reeds (*umhlanga*, *Phragmites*) are used in construction, and a reed windbreak (*iguma*) may stand in front of the door.\n\nThe usual word for grass is *inca*; *utshani* is avoided in respectful speech because it is also the name of an ancestral chief.\n\n## Interior\n\nThe hearth (*iziko*) lies on the axis between the door and the back of the house, where a raised shelf (*umsamo*) is used for storing food and for ancestral observance by the head of the household.\n\n## Comparison\n\nThe hemispherical form contrasts with the cone-on-cylinder rondavel of the interior plateau, where a separate conical roof sits on a vertical wall. In the beehive house there is no separate wall: the whole envelope is thatch over the sapling frame, with an inner insulating layer beneath the outer coat.","key_facts":[{"label":"Region","value":"KwaZulu-Natal, South Africa"},{"label":"Form","value":"Hemispherical (beehive)"},{"label":"Frame","value":"Sapling arches (izintingo)"},{"label":"Covering","value":"Two layers of grass thatch"},{"label":"IsiZulu name","value":"Indlu (dwelling)"}],"regions":["Africa"],"aliases":["indlu","Zulu hut","Zulu hemispherical dwelling"],"related":["roofing-in-south-africa","rondavel","thatch","roofing-in-eswatini","harran-beehive-houses","roofing-in-southern-africa"],"company":null,"sources":[{"title":"Glossary - Zulu terms","url":"https://francofrescura.sahistory.org.za/glossary/glossary-zulu-terms/","publisher":"Franco Frescura / South African History Online"},{"title":"Glossary","url":"https://francofrescura.sahistory.org.za/glossary/","publisher":"Franco Frescura / South African History Online"}],"country":null},{"slug":"zvdh-fachregeln","title":"ZVDH Roofing Rules and DIN 4108 (Germany)","summary":"German roofing follows the technical rules of the roofers' federation ZVDH, alongside DIN standards such as DIN 4108 for thermal and moisture protection.","body":"In Germany, roofing practice rests on two main bodies of technical rules: the trade rules of the German roofing federation, and national standards from DIN, the German Institute for Standardization.\n\n## ZVDH and its technical rules\n\nThe **Zentralverband des Deutschen Dachdeckerhandwerks (ZVDH)** is the national federation of the German roofing trade. It was founded on 2 April 1949 in Marburg and is based in Cologne. Its direct members are the 16 state-level roofing associations, and through them it represents about 6,700 roofing businesses (2024 figure).\n\nThe ZVDH publishes the **Regelwerk des Deutschen Dachdeckerhandwerks**, a collection of technical rules (*Fachregeln*), guidelines (*Richtlinien*) and work instructions (*Hinweise*). They cover the main pitched and flat roof types and related components. The rules set out minimum pitches, overlaps, fixings, underlay classes and detailing. They are widely treated as the \"generally recognized rules of technology\" (*anerkannte Regeln der Technik*), which matters legally: German construction contracts and courts use these rules to judge whether work is free of defects.\n\n## DIN 4108: thermal and moisture protection\n\n**DIN 4108**, *Wärmeschutz und Energie-Einsparung in Gebäuden* (Thermal protection and energy economy in buildings), is the main German standard series on thermal insulation and moisture protection. It applies to habitable rooms in buildings such as homes, offices, schools and hospitals. Parts most relevant to roofs include:\n\n- **DIN 4108-2** (2013) – minimum thermal protection, including avoiding condensation and mould and limiting summer overheating\n- **DIN 4108-3** (2018) – climate-related moisture protection, including the Glaser method for calculating condensation in building elements such as insulated roofs\n- **DIN 4108-7** (2011) – airtightness of buildings, important for pitched roofs with insulation between rafters\n\nGermany's Building Energy Act (*Gebäudeenergiegesetz*, GEG) refers to DIN 4108 in several places. DIN 4108-6 is being phased out in favour of DIN V 18599 for energy calculations.\n\n## How they fit together\n\nA typical insulated pitched roof in Germany must meet GEG energy requirements, demonstrate moisture safety under DIN 4108-3, achieve airtightness to DIN 4108-7, and follow ZVDH rules for the covering, underlay and details. European product standards such as [EN 1304](/en-1304) and [EN 12326](/en-12326) apply to the materials themselves.","key_facts":[{"label":"ZVDH founded","value":"2 April 1949, Marburg"},{"label":"ZVDH seat","value":"Cologne"},{"label":"Member businesses","value":"About 6,700 (2024)"},{"label":"Thermal/moisture standard","value":"DIN 4108 series"},{"label":"Energy law","value":"Gebäudeenergiegesetz (GEG)"}],"regions":["Europe"],"aliases":["ZVDH","Fachregeln des Dachdeckerhandwerks","Regelwerk des Deutschen Dachdeckerhandwerks","DIN 4108"],"related":["dtu-40-series","en-1304","en-12326","roof-insulation","vapor-retarder"],"sources":[{"title":"Zentralverband des Deutschen Dachdeckerhandwerks","url":"https://de.wikipedia.org/wiki/Zentralverband_des_Deutschen_Dachdeckerhandwerks","publisher":"Wikipedia (German)"},{"title":"DIN 4108","url":"https://de.wikipedia.org/wiki/DIN_4108","publisher":"Wikipedia (German)"}],"category":"standards-codes","type":"standard","company":null,"country":null}]