By Er. Ved Parkash Takyar
Various causes of dampness in buildings are as given below :
There can be breakage of D.P.C (Damp Proof Course) by Plumbers, so the cast iron sanitary and rain water pipes should be erected before laying the DPC. The plain Cement Concrete once broken will never reunite. Even a hair crack leads to dampness in walls due to capillary action.
Unequal floor levels within a house or between two houses, and not providing vertical D.P.C. plaster along the inner side of walls from horizontal D.P.C. (Laid on the wall at the lower floor level) up to the higher floor level i.e. the depth which needs to be sealed from dampness which enters the walls from underneath the higher floor and further rises above in the wall.
Not providing permanent treatment of dampness with effective chemical in the basement floor slab & its outer walls, and out side of the walls from the bottom slab of floor up to the filling. The water proof treatment is required to be provided on the sides of filling & not on the inner exposed sides. The basement R.C.C. slab under floor should be laid before the sides walls.
Flooring if laid above the level of horizontal D.P.C., results in dampness of walls from the underneath brick ballast concrete and sand/earth filling. If any one wants to increase any floor level, vertical D.P.C. plaster from lower Horizontal D.P.C. must be provided along the wall up to the proposed higher floor level.
There will be Dampness in cupboards & Kitchen Cabinets i.e. under the working slab. It is due to absence of Horizontal and Vertical D.P.C's. 4 1/2" or 3" thick walls are generally constructed later on & masons usually forget to lay the Horizontal D.P.C. on them. More over their floor levels are also raised up to the skirting level, so therefore, the horizontal D.P.C on the walls and vertical D.P.C. plaster along the inner side of walls up to the purposed raised level of floor is necessary.
There will be Dampness under the terrace floors if laid other than brick tiles. Hair Cracks do not occur in joints of brick tiles terracing when these will definately occur in concrete, crazy and stone floors in summer on account of their thermo behaviour. For such floors, necessary remedial measures must be taken during construction.
If separate walls instead of common walls are constructed between two houses, there will be crack between two walls at top. During rains, the water will enter through the crack between two walls. Common walls should be preffered otherwise foundations of both the houses will remain weak.
Where dampness exist in the already constructed walls or in the neighbourer wall and a new wall is proposed to be constructed adjacent with the existing wall, dampness will travel in new wall due to capillary action. To avoid dampness, remedial measure should be taken between two walls above the horizontal D.P.C.
There will be dampness a/c of cracks, If expansion/contraction and construction joints are not provided in he R.C.C slab/beams at required distance and place. Cracks with the parapet on outers walls is common site which can be all together avoided if 3/8" to 1/2" expansion joint is provided between the R.C.C. slab and masonary wall.
There will be dampness in external 9" thick wall if effective water proof chemical is not mixed in the cement plaster when done on the exterior.
Leakage in the water storage tanks of masonary /concrete is often due to inside chipping with stone chips or enfacing glazed tiles etc. Cracks are liable to occur when emptied in summer. Cracks on the glazed surface are not repairable whereas on the cement plaster surface, the same are repairable.
There will be dampness in walls behind stone Butch face work if laid without waterproof chemical in the cement mortar.
When Sanitary and Rain water cast iron pipes are not of standard quality and not checked before embedding in walls and their points are not fully filled with molten lead. The H. D.P.C. and PVC pipes which have high thermo expansion, are not recomended in this hot region.
Dampness/Leakage will happen where Inverted/hidden beams are provided in the roof slab.
There will be Dampness in toilets & kitchen due to Carelessness in fittings of water supply and sanitary fittings by plumbers.
by Er. Ved Parkash Takyar
( Building Consortium ) 19 - H, B. R. S. Nagar, Ludhiana.