The Proper Construction of a Thatched Roof

Materials

• In the British Isles, where thatched roofing remains popular, a thatched roof is made from bundles of grassy water reeds that are tied to a thin wooden lattice framework on the roof of a house. The grass bundles are 5 or 6 feet long. Brass screws are attached to the wooden lattice and the bundles are tied to the screws with steel wire. The structure topped with a durable wheat straw ridge.

Principles

• Thatched roofs require perfect ventilation or they will mildew and rot. The cellular structure of thatch makes each blade waterproof, but water does drain through the thatch as it descends the roof. Ventilation ensures the thatch dries after each rain. The lattice frame allows both circulation and a secure place to tie the thatch bundles.

Construction

• In quality applications, brass screws are installed on the frame. Reed bundles are tied to the screws in rows, then overlapped as the work rises up the roof. As each row of bundles is laid, the ones under it are once again tied to the frame, creating a well-bound, unified roof that is very strong. The work should be so tight that is difficult to work your finger up under the reeds. Ridges are typically made from wheat straw, which is more pliable than water reed, and attached with a wooden pole.

Considerations

• In England, thatched roofing is comparable in price to slate and tile. Here in North America, however, the expense is increased by the importation of both materials and labor. Most thatchers doing quality jobs on this side of The Atlantic commute from Wales or Ireland for each job. Thatch is flammable and, while thatch can be chemically fireproofed, getting approval from local authorities not familiar with thatched roofing may be challenging. Likewise, finding insurance for a thatched building may be difficult.