Palm wood

The trunk and ribs (jrid) of the date palm, the principal local timber resource of the southern Moroccan and pre-Saharan oases. Whole or split palm trunks are used as primary roof beams; palm ribs are laid as a closely-spaced secondary layer and covered with reed matting and earth to form the characteristic flat-roof terrace (stah). Palm wood is fibrous, anisotropic, and does not produce structurally efficient long beams, which is one reason ksour and kasbahs are dimensioned around relatively short room spans. The systematic loss of date-palm cover to bayoud disease has measurably affected the supply of building-grade palm timber across the lower Drâa and Tafilalt valleys.