Building materials in the hot climate zones

Cane and leaves are available in the warm-humid zones and grass in the intermediate and subtropical

zones. Vine, bamboo and palm-fronds are used for buildings in the warm-humid zones. Because these

materials are light, do not store heat, and allow the free passage of air, they are frequently used for

making roofs. However, they have a relatively short life span because they deteriorate rapid­ly due to

termite attack. They are also highly combustible.

Both hardwoods and softwoods are found in most tropical and subtropical areas with the exception of the hot dry zones. On exter­nal woodwork preservative stains should be used rather than paints which tend to deteriorate fairly rapidly in the hot zones. Extremes of climatic conditions cause dimensional changes producing cracks, splits and warping. Wind-blown sand and grit gradually erode ex­posed timber. In warm-humid zones timber is liable to wet and dry rot and to attack by termites and beetles.

Earth is one of the most widely used traditional building materials in hot-dry lands. Earth is used not only for walls but also for roofs; mud brick vaults and domes are common in countries like Iran and Egypt. Because mud has less strength than most other construction materials, mud walls are built thicker. Partly due to the thickness of mud walls and partly due to its low thermal conductivity, rooms built of mud are much cooler in hot climates than those of any other material. Mud bricks are brittle and do not withstand tension well. For this reason the vault and the dome were evolved in the East. There is a high risk of termite damage in some areas. Walls exposed to weathering and rain require frequent repair work.

Concrete and reinforced concrete are widely used throughout the non-temperate zones. Cement is manufactured locally in many places. Sand is found almost everywhere but it may be contaminated with soluble salts. Suitable aggregate may be difficult to find. Con­crete is most frequently used for the structure, foundations and floor slabs of buildings. Care must be taken when using concrete for walls and roofs. Heat builds up on the exterior of concrete walls and roofs.

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