Roofing in Turkey

Turkey (officially Türkiye) straddles south-eastern Europe and western Asia and holds some of the oldest evidence of roofed buildings anywhere, from the Neolithic towns of Anatolia to the Byzantine and Ottoman domes of Istanbul. Its roofs reflect sharply different climates: the rain-soaked Black Sea coast, the hot-summered Aegean and Mediterranean shores, the cold, dry plateau of central and eastern Anatolia and the very hot plains of the south-east. Much of the country is highly seismic, which has shaped both traditional and modern construction.¹¹

The Turkish word for roof is çatı; a flat roof, especially a traditional earth roof, is dam; a roof tile is kiremit; and a dome is kubbe.

Climate and hazards

• Black Sea coast: the wettest part of the country, where steep pitched roofs with wide eaves have traditionally protected timber houses.
• Marmara, Aegean and Mediterranean coasts: hot, dry summers and mild, wet winters; clay tile roofs predominate in older towns and villages.
• Central and eastern Anatolia: low rainfall, hot summers and harsh winters. Thick flat earth roofs, valued for low cost, ease of construction and resistance to heat, were the vernacular norm, particularly where rainfall is low to moderate.⁸
• South-east: extreme summer heat on the Harran plain, met by thick-walled mud-brick domes.⁶
• Earthquakes: seismic hazard is high across much of the country, and building design is governed by a national earthquake regulation, most recently revised in 2018.¹¹

The national thermal insulation standard divides Turkey into degree-day climate zones, from the hottest (DG1) to the coldest (DG4), with insulation requirements that rise in colder zones.⁹

History

Neolithic Anatolia

Göbekli Tepe, in the Germuş mountains of south-eastern Anatolia, has monumental communal enclosures with T-shaped limestone pillars up to 5.5 m (18 ft) tall, built by hunter-gatherer communities between about 9600 and 8200 BC.² The structures were probably used for rituals and social gatherings, possibly funerary.²

Çatalhöyük, on the Konya plain, is one of the most famous early settlements in the world. Its eastern mound, rising up to 20 m (66 ft), holds 18 levels of Neolithic occupation dated to about 7400–6200 BC, and the western mound adds Chalcolithic levels from about 6200 to 5200 BC.¹ The houses were packed back to back without streets, so residents moved across the flat roofs and entered their homes through openings in them.¹ The roofscape thus served as the town's street, workspace and threshold. The site was discovered in 1958 and covers 37 ha (91 acres).¹

Ancient tile roofs

Fired clay roof tiles spread rapidly from mainland Greece to the eastern Mediterranean within about fifty years of their adoption on temples near Corinth around 700–650 BC, which places the Greek cities of western Asia Minor among the earliest tiled places in the world.³

The Harran beehive houses

At Harran, near the Syrian border, Assyrian reliefs of the 7th century BC already show domed buildings like the conical "beehive" houses still standing there.⁶ Because wood is scarce, the houses are built of stone, brick and mud, often with bricks salvaged from ancient ruins.⁶ Walls are typically 50–60 cm (20–24 in) thick and the domes 20–30 cm (8–12 in), with an opening at the top for ventilation; together these keep the interiors relatively comfortable through extreme summer heat.⁶ The weak plaster needs repair every one to three years.⁶ The 12th-century traveller Ibn Jubayr recorded beehive houses at Harran, and most of those standing today date from the early 20th century.⁶ A 2002 count found 2,760 such houses, though only a few dozen now remain in the old town, mostly used as stores and barns; some were lived in until the 1980s, and they have been protected since 1979.⁶

Byzantine Constantinople

The Hagia Sophia in Constantinople (now Istanbul), built in 532–537 for the emperor Justinian by Anthemius of Tralles and Isidore of Miletus, crowned a basilica with a vast dome on pendentives, the first use of the technique at monumental scale.⁴ Forty windows pierce its base, and after an earthquake brought part of it down, the dome was rebuilt taller and steeper to reduce its outward thrust.⁴ It became a mosque after the Ottoman conquest of 1453 and a museum in 1934.⁴

Seljuk and early Ottoman roofs

Anatolian Seljuk and early Ottoman builders developed the "Turkish triangle", a faceted form of pendentive used to carry domes over square rooms, as at the Green Mosque in İznik (1378–1391).⁵ Early Ottoman mosques in İznik and Bursa were single-domed or multi-domed buildings: the Hacı Özbek Mosque in İznik dates from 1333, the Orhan Gazi Mosque in Bursa from 1339, and the Grand Mosque of Bursa, finished in 1399–1400, covers its prayer hall with twenty domes.⁵

Classical Ottoman domes

Ottoman architects used simple hemispherical domes, usually built of brick over temporary timber centring and set on pendentives without the tall drums typical of Byzantine work.⁵ Early domes were usually covered with terracotta tiles, but by the 16th century lead sheet had become the standard covering, giving Ottoman skylines their characteristic grey domes.⁵

The architect Mimar Sinan, chief court architect from 1538 until his death in 1588, refined the domed mosque.⁵ His Şehzade Mosque (1545–1548) surrounds a central dome with semi-domes on all four sides; the Süleymaniye complex in Istanbul (1550–1557) places semi-domes before and after its central dome; and the Selimiye Mosque in Edirne (1568–1574 or 1575) raises a dome of roughly the same diameter as that of the Hagia Sophia.⁵ Later imperial mosques continued the tradition of a lead-covered central dome stepped down by semi-domes and smaller domes, among them the Blue Mosque of the 17th century and the New Mosque on the Golden Horn, completed in 1664, whose cascading roofs, together with the 15th-century Topkapı Palace and Fatih complex, define the skyline of Istanbul's historic peninsula.⁵¹³

Ottoman towns and houses

Safranbolu, a caravan town on the east–west trade route from the 13th century until the railway age, preserves the domestic architecture that peaked in the 17th century.⁷ Its older houses in the Çukur quarter are half-timbered with infilled frames, while those of Kıranköy are stone; interiors centre on halls called sofa, and many ceilings are richly carved and painted.⁷ Steep streets are paved with stone that slopes inwards to carry away rainwater.⁷

The Republic and modern construction

In the 20th century, reinforced-concrete frame construction became dominant throughout Turkey, with flat concrete roofs or timber-framed pitched roofs covered in tile, metal or bituminous products. Earthquake regulations were revised repeatedly; the Turkish Building Earthquake Regulation of 2018 (Türkiye Bina Deprem Yönetmeliği) succeeded the 2007 regulation and came into force on 1 January 2019.¹¹

Traditional and vernacular roofs

Flat earth roofs (dam)

Across central and eastern Anatolia, traditional houses were covered with flat earth roofs laid over timber beams and poles. Such roofs suit regions of low to medium rainfall, are cheap, easy to build from local materials and resist heat penetration.⁸ Their performance depends on coordinating the structural layer with waterproofing, insulation, soil and drainage, and researchers have proposed improved mud-roof sections to boost their thermal, structural and water-resistant qualities.⁸ Because the earth layer is heavy and can be planted or grassed over, such houses are effectively earth-sheltered buildings whose roofs must be designed together with drainage and landscaping.⁸

Tiled pitched roofs

Along the Aegean, Marmara and Black Sea coasts and in western Anatolian towns, hipped and gabled roofs covered with curved or interlocking clay tiles are the traditional form, often with wide eaves to protect timber-framed or stone walls. Safranbolu's half-timbered and stone houses are classic examples of the Ottoman town house beneath such roofs.⁷

Rock-cut Cappadocia

In Cappadocia, in central Anatolia, erosion of volcanic tuff produced "fairy chimney" pillars and towers up to about 40 m (130 ft) high, into which people carved cells, churches, whole troglodyte villages and underground towns such as Kaymaklı and Derinkuyu.¹⁴ Monastic communities lived in rock-cut cells from the 4th century, and more than 200 rock-hewn churches are recorded, many richly painted after 842.¹⁴ Here the "roof" is the living rock itself, a strategy that avoided the need for timber altogether.

Istanbul's timber houses

In the Süleymaniye and Zeyrek quarters of Istanbul, late Ottoman timber houses survive around Sinan's Süleymaniye Mosque (1550–1557) and the former Pantocrator church.¹³ They are regarded as exceptional evidence of the late Ottoman urban pattern, but were recognised as vulnerable when the Historic Areas of Istanbul were listed, and their timber structures have since been the subject of strengthening work.¹³

Domes and vaults

Domes cover not only mosques but baths, tombs, caravanserais and the beehive houses of Harran, where scarce timber made masonry roofs a practical necessity.⁵⁶

Roofing today

Materials

Most new buildings are reinforced-concrete frames. Flat roofs are waterproofed with bituminous or synthetic membranes, while pitched roofs on timber or steel framing are covered with clay or concrete tile, coated metal sheet or bituminous shingles. Insulation is now a significant part of roof construction: glass wool holds about 70% of the Turkish insulation market and is the typical material for roof insulation.⁹

Energy and insulation rules

Turkey's building energy code was published in 2008 as a national, performance-based code.¹⁰ Residential envelope minimums include a roof U-value of 0.4 W/(m²·K), external walls and floors of 0.6 W/(m²·K), and requirements to prevent air leakage.¹⁰ Thermal insulation rules are set out in TS 825, Binalarda Isı Yalıtım Kuralları (Thermal Insulation Rules in Buildings), published by the Turkish Standards Institution, whose limit values are based on heating loads in each degree-day zone.⁹ Studies have argued that cooling loads should also be considered in the hottest zones, and have calculated cost-optimal roof insulation of about 14.8 cm (5.8 in) of glass wool in DG1 and 20.1 cm (7.9 in) in DG2 when heating is the basis.⁹

Earthquake safety

Because many Turkish buildings are heavy concrete frames in seismic zones, roof weight and the connection of roofs to the structure matter for safety. The 2018 earthquake regulation governs design loads and analysis for new buildings, and studies comparing it with the 2007 rules have examined the resulting differences in earthquake load calculation.¹¹

Reed for thatch

Turkey supplies thatching reed to northern Europe. More than 80% of the water reed used in the United Kingdom is imported, from Turkey, Eastern Europe, China and South Africa.¹²

Notable roofs

• Çatalhöyük, Konya: Neolithic town of roof-entry houses, c. 7400–6200 BC.¹
• Göbekli Tepe, Şanlıurfa: monumental Pre-Pottery Neolithic enclosures, c. 9600–8200 BC.²
• Hagia Sophia, Istanbul (532–537): pendentive dome over a basilica.⁴
• Grand Mosque of Bursa (1399–1400): twenty domes over a hypostyle hall.⁵
• Süleymaniye Mosque, Istanbul (1550–1557), and Selimiye Mosque, Edirne (1568–1574/75): Sinan's lead-covered domes.⁵
• Harran beehive houses: corbelled mud-brick domes on the Syrian border.⁶
• Safranbolu: Ottoman town houses on a historic caravan route.⁷

Local roofing terms

• çatı: roof
• dam: flat roof, especially a traditional earth roof
• kiremit: roof tile
• kubbe: dome
• kurşun: lead, the traditional covering of Ottoman domes
• sofa: central hall of an Ottoman house⁷