ROOF :A roof is the uppermost part of a building, provided as a structural covering, to protect the building from rain, sun, wind, etc. Roof protects the building from the dam- ages starting from the top.
FLAT ROOF
The roof which is nearly flat or at a slope upto 10° is known as flat roof.
1. R.C.Croof
2. Madras Terrace roof
3. Lime concrete roof
4. Bengal Terrace roof
1 METHOD OF CONSTRUCTION OF REINFORCED CEMENT CONCRETE (RCC) ROOF SLAB
i. CENTERING: Since the con- crete is in a semisolid state dur- ing placing it becomes necessary to give support until it gains suf- ficient strength. Centering is a temporary platform which is formed by using wooden planks and props or steel plates and steel pipes. It should be strong enough to withstand the weight of the roof concrete. Before laying the steel rods the surface of centering should be applied with grease for easy removal of plank. The steel rods are then placed in position and are tied by using binding wires. Usually the concrete mix proportion of 1:1.5:3 is placed over the centering and they are compacted by using vibrator. STOR
ii. CURING AND REMOVAL OF FORM WORK: After laying of concrete the surface of concrete should be cured for about 21 to 28 days. Only then the concrete will attain its strength. The form work should be removed after 14 days.
iii. WEATHERING COURSE: The weathering course will protect the surface of the roof from weathering actions. The surki mortar of 1:1.5 (1 lime and 1.5 brick bats) ratio is laid on the roof surface for about 100 mm thick. Above this flat tiles are laid by using cement mortar 1:3. The joints inbetween the tiles are pointed by using cement mortar. Proper slope is maintained for easy drainage of rain water.
2. MADRAS TERRACE ROOF
● Madras terrace roof was widely used in Madras Province.
●A course of well burnt bricks is laid in lime mor- tar keeping the bricks on their edges diagonally across the joists.
● A10cm thick brick bat concrete is laid over it and thor- oughly compacted by frequent wetting with water.
● Flat tiles are laid in 3 layers over this in lime mortar.
● Finally three coats of plaster are applied for finishing the surface and a slope of about 1 30 is given for draining rain water.
Advantages and Disadvantages Offlat Roof
ADVANTAGES
1. It is easy for construction and maintenance.
2. Upper floor can be easily constructed.
3. Flat roof possess good insulation properties.
4. A flat roof provides better light, ventilation and architectural appearance to the building.
DISADVANTAGES
1. Flat roof is not suitable forplaces of heavy snowfall.
2. Construction speed is slower than the pitched roof.
