rethatching

Rethatching is the renewal of the outer layer of a thatched roof after the existing thatch has deteriorated or become ineffective at keeping out rain. Thatch is a natural roofing material made from bundles of dry vegetation such as water reed, long straw, wheat straw, or heather. The frequency of rethatching depends on climate, material, and workmanship, but roofs commonly require renewal after several decades.

The rethatching process often begins with removing a portion or all of the old thatch to expose a sound roof structure. Damaged supporting timbers or battens are repaired or replaced as needed. New thatch is then laid in courses, typically starting at the eaves and worked toward the ridge, and secured with binding materials. The thatch is shaped and trimmed to shed water, and the ridge is finished with a cap or rolled thatch to seal the apex. Some installations include a ventilating layer or protective underlay, and the roof is treated to improve weather resistance. Work is done by trained thatchers who use specialised tools and safety equipment.

Rethatching is labor-intensive and costly, and many jurisdictions regulate the work due to fire risk and building standards. Regular maintenance, such as removing moss, checking for loose thatch, and ensuring proper drainage, can extend roof life. Lifespan varies with material and exposure, ranging from a few decades to several decades before another renewal is needed.