Sod
A sod is grass turf and the part of the soil beneath it held together by the roots, or a piece of this material. Sod has occasionally been cut out in blocks to use as a building material, especially in grasslands where grass is plentiful and few other materials are available. For use as a building material, sods are cut out in regular block shapes and laid like brickwork, although for strength blocks of sod are usually much longer and wider than typical bricks. Common dimensions in nineteenth century US prairie states were 600 × 300 × 150 mm. Cutting sods for building may be done with a spade and axe, but for large scale work a modified plough is used.The bare sod is prone to damage from rain or being knocked, so the outer walls are usually protected with a layer of stucco or wood pannelling. Similarly, bare sod inside is dirty, so the interior may be lined with canvas, tarpaper, or plaster. A variety of roofing methods can be used, and the house can be fitted with conventional windows and doors. Sod houses have the advantages of being very cheap, and well insulated, so that they are cool in summer and warm in winter. The main disadvantages are that they tend to be damp, and deteriorate quickly unless maintained.
Sod has also been used in fortification. Blockhouses have been constructed from sod, and it has also been used to make very effective berms or low defensive walls. Because of the cheapness of sod, these walls could easily be made thick enough to be bulletproof.
See also
Other meanings of sod: