Use of Damp-Proofing Courses (or DPC)

These are the layers or membranes of water repellent materials like as mastic asphalt, bituminous felts, cement concrete, plastic sheets, mortar, metal sheet, slates, stones, etc., that are interposed within the building structures at all locations wherever water entry is anticipated or suspected. These damp proof courses of appropriate materials should be given at appropriate locations for their effective use. Basically, DPC is provided to avoid the water rising from the sub-soil or ground and getting into the various parts of the building. The best position or location for DPC in case of buildings without basements, lies at the plinth level or in case of structures without plinth it should be laid at least 15 cm above the ground level (Figure 1). These damp-proof courses might be given horizontally or vertically in walls, floors etc.

                                                 Figure: DPC above Ground Level

Integral Damp Proofing This consists of adding certain water proofing elements of materials to the concrete mix, while that it becomes impermeable. These water proofing compounds might be in several forms such as compounds made from chalk, talc etc., that may fill the voids of concrete. Compounds such as alkaline silicates, calcium chlorides, aluminium sulphate, etc., react chemically along with concrete to generate water proof concrete. Compounds, like petroleum, soap, oils, fatty acid compounds like as stearates of calcium, sodium, ammonia etc. work on water repulsion principle. While these are mixed with concrete, the concrete becomes water repellent. A few commercially available compounds used for this purpose are Permo, Publo and Silka.