THATCH (O.E. lhaec; the word is common to many Teutonic languages in the sense of " roof," " cover "; cf. Du. dak, Ger. Dock; from Du. dekken comes " deck "; the Indo-European root is stag, whence Gr. ffrcyos, roof, Lat. tegere, to cover; the French equivalent is chaume), the material employed sometimes for roofs in the place of tiles or slates; it consists of wheat straw, of which several layers are required, to the depth of from 12 to 14 in., or even extending to 18 in. Unthreshed straw is said to last from twenty-five to thirty years, and is easily repaired. In Norfolk the reeds of marshland are employed, and they constitute a durable thatch lasting from thirty to forty years or more. Thatched roofs are not now allowed in London or other towns and their vicinity, but if saturated with a solution of lime the thatch is said to be incombustible. It forms an extremely good roof, warm in winter and cool in summer.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)