English Thatch

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.

Materials

Three materials dominate:

• 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.
• 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.
• 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.

Water 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.

Pitch and lifespan

Thatch 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.

Ridges and styles

Ridges 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.

Fire and insurance

Thatch 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.