A damp proof course (DPC) is a barrier installed in a building to prevent moisture from rising through walls and floors by capillary action, a phenomenon known as rising damp. DPCs can be horizontal or vertical and are usually made of durable, impermeable materials such as slate, felt paper, metal, plastic, or special engineered bricks. The DPC is usually laid below all masonry walls, regardless of whether the wall is a load-bearing wall or a partition wall. The DPC is installed at various levels of the building to prevent the entry of moisture from walls, floors, and the basement of a building.
The installation of DPCs depends on the type of building and the thickness of the walls. For DPC above ground level with wall thickness generally not exceeding 40 cm, any one of the types of materials mentioned above may be used. Cement concrete is a commonly adopted material for DPC at plinth level, and a 38 to 50mm thick layer of cement concrete M15 (1:2:4 mix) serves the purpose under normal conditions. For greater wall thickness or where DPC is to be laid over large areas such as floors, roofs, etc., the choice is limited to flexible materials that provide a lesser number of joints like mastic, asphalt, bitumen felts, plastic sheets, etc. .
To ensure a complete and continuous barrier to the passage of water from floors, walls, or roof, each DPC should be placed in the correct relation to other DPCs. The mortar bed upon which the DPC is to be laid should be made level, even, and free from projections. Uneven base is likely to cause damage to DPC. When a horizontal DPC is to be continued up a vertical face, a cement concrete fillet 75mm in radius should be provided at the junction before the treatment.
In summary, a DPC is an essential element in building construction that prevents moisture from rising through walls and floors by capillary action. It is usually made of durable, impermeable materials and installed at various levels of the building. The installation of DPCs depends on the type of building and the thickness of the walls.
