Roof : Depending upon the climatic conditions building can have a sloping roof or a flat roof. The roof should be structurally safe. Durable and should provide adequate protection against adverse effects of elements like rain, snow, sun and wind etc. It should provide desired insulation against heat and sound drainage arrangements. In areas having heavy rainfall or snowfall sloping roof is preferred to flat roof. In other areas flat roof is provides and it has the added advantage that the roof can be used as terrace for sleeping purposes. Sloping roof can be made by use of timber,structural sheets/bricks tiles etc. Flat roof can be in the pre-cast units (cored units, channel units, cellular units, waffle units funicular slabs etc.)
In case of sloped roof it is necessary to provide false ceiling made out of insulating materials like asbestos sheets, timber, fibre boards etc to meet the requirements of the thermal comfort. In case of flat roof it is necessary to provide terracing for this purpose.
Terracing: Terracing treatment is given over flat roofs to perform the combined function of providing roofs to perform the combined function of providing thermal insulation and water proofing simultaneously. It is necessary to provide the layer of terracing material in slope varying form 1:48 to 1:60 so as to ensure quick disposal of the rain water. Prior to laying terracing, the top of the roof slab is painted with layer of bitumen of penetration 80/100 using 17 kg bitumen for every 10 sq.m area and impregnated with a coat of coarse sand @60dm/10sq.m.
The choice of specifications for the terracing under different climatic conditions should be as under:
1. For hot and arid regions
Providing 10 cm thick (average) layer of mud phuska laid to a slope of about 1:50. This layer is consolidated and plastered with 25mm thick mud mortar mixed with bhusa @35kg/ci.m of earth and gobri leaping with mix 1:1 (1 clau : 1cow dung). This layer is covered with flat tile bricks grouted with cement mortar 1:3. The joints of the bricks are pointed on top with cement mortar 1:3.
In place where good earth is not available lime concrete terracing may be specified in place of mud husk thick stone slabs or 35mm thick M50 grade(1:2:4) cement concrete flooring may be laid as the topping .
2. Hot and humid regions:75 mm thick (average) lime concrete terracing laid to a slope of 1:50 may be specified.
3. In regions of heavy rainfall: In case it is necessary to provide flat roof regions of heavy rainfall, lime concrete terracing layer is covered with a layer of pressed clay tiles or 2 layers 5% crude oil by weight of cement. The joints should be pointed with the same mortar.
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