Thatch Ridge

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.

Materials

Ridges 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.

Types

• 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.
• Butt-up ridge. Found mainly in south-west England: bundles are forced together with their butts meeting from either side to form the apex.
• Flush ridge. Finished level with the surface of the main coat.
• Block-cut (raised) ridge. Built up proud of the main coat and cut to a decorative edge with scallops, points or other patterns.

Fixing and decoration

Ridges 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.

Maintenance

When 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.