Before starting the process of waterproofing in buildings; its cause should be determined. The problem of rain water leakage in buildings can be classified as follows:-
Rain Water Leakage in Buildings
1)Leakage in the flat roof terrace
Stagnation of water on a flat roof is one of the common reasons for leakage and dampness in the building. Leakage happens in a flat roof due to bad drainage also.
The slope of roof terrace should be constructed in a way such that the rainwater drains off before seeping into the roof. The minimum recommended slope for a roof covered with tiles is 1 in 60. For a non-treats rough surface, it is 1 in 40.
2)Leakage in shells and sloped roof
~ Lack of compaction during the construction phase due to difficulty in compaction by vibrator.
~ Use of porous concrete.
~ Always use dense concrete.
~ All the valleys should be checked for leakage and grouted at the construction stage itself. Waterproofing coating in the form of the bituminous coat can also be applied. Check for the provision of the gutter, cave gutter, valley gutter, and boundary wall gutter.
3)Leakage through Junction of wall and sunshades
Stagnation of water at the junction between the wall and sunshade. Continuous long sunshades without joints or gaps tend to crack at the interval.
Give proper slope for quick drainage of the sunshades at the construction stage. Provide a fillet or goal by plaster at the wall junction.
In the case of a crack in sunshades, fill these cracks with an elastomeric compound that can accommodate the movement of joints. All leaves collected over the sunshade should be maintained, clean, especially during the rainy season.
4)Leakage Through cracks on external walls
Improper curing & Improper mix of materials are the main causes of cracks on external walls.
All the cracks that have been formed on the external wall should be deepened to 5 mm and filled with proper sealant.
5)Leakage at Junctions of outer walls with roof slab and other floor slabs
Due to the difference in the expansion of concrete and masonry; If there is a small gap at the junction at the external face, the water that flows down the external wall tends to be sucked into the building.
Provide a drip course with a projection with a shaped groove, called drip by extending the slab beyond the wall or by constructing a separate drip coarse in a framed building in the form of bend at the junction.
In the case of the existing building, the joint has to be sealed with a waterproof sealant or by the application of elastomeric paint with glass fibre.
6)Leakage from external electric points
All the external electrical points and fitting should be sealed with good sealants and made waterproof. Any wires and pipes taken into the building should be bent down. It should not carry water inside the building.
7)Leakage from expansion Joints of slabs or beams
Expansion or other joints provided by the designer in slab and beams should be properly filled with approved Joint Fillers. Joints fillers are special material that allows movement of the joints.