thatch

Thatch is a roofing material made from dry vegetation such as straw, water reed, or rushes. It is laid in overlapping layers on a timber frame to shed rain and provide insulation. The most common materials are straw (often wheat or barley), water reed, and thatching grasses; regional choices reflect climate, availability, and tradition.

Thatching typically starts at the eaves and proceeds toward the ridge, with bundles or strands secured to a lattice or thatching battens. In straw thatch, long-straw or combed straw is used; reed thatch uses bundles of water reed. Finishes at the ridge vary, with rolled or capped ridges and sometimes metal or ceramic fittings to help weatherproof the roof.

Thatch offers several advantages, including good natural insulation, low embodied energy, and a distinctive appearance that suits historic and eco-friendly buildings. It remains in use for traditional houses in many parts of Europe, Africa, and Asia, as well as in some modern sustainable designs. However, thatch has drawbacks: it is flammable, requires skilled maintenance, and is susceptible to moisture, moss, pests, and wind damage. Lifespans depend on material and climate but typically range from 15 to 40 years with regular re-thatching or patching.

Maintenance involves periodic inspection, replacement of degraded sections, and clearing debris. Fire risk is managed with protective mesh, spark arresters, and clearances from chimneys or vents, and some jurisdictions require fire retardant treatments. Thatching remains a recognized craft and can be protected as part of historical or vernacular architecture.