Damp-Proof Course (DPC)
Impervious horizontal barrier at plinth stopping rising damp into walls
A Damp-Proof Course (DPC) is a continuous impervious layer provided at plinth level (and wherever a wall meets a damp surface) to stop ground moisture from rising into the superstructure by capillary action. The commonest form in Indian building practice is a 40–75 mm thick course of dense cement concrete (typically M15/1:2:4 or richer) with an integral or applied waterproofing compound, laid over the full width of the plinth wall and turned up at junctions; bitumen, mastic, polythene sheet and metal flashing are alternative or supplementary materials guided by IS 3067 (code of practice for damp-proofing of buildings).
A defective or discontinuous DPC is one of the most frequent causes of efflorescence, paint peeling, plaster blistering and timber decay in the lower few courses of masonry. The course must be unbroken, properly lapped at junctions, continuous with the floor waterproofing and never bridged by later plaster, soil banking or sunken-floor fill — bridging short-circuits the barrier and reintroduces rising damp. It is measured and paid per the relevant IS 1200 part and the governing schedule of rates.
- Plinth level of all load-bearing + framed masonry walls
- Junction of wall with sunken floors, planters + water tanks
- Retaining + basement wall internal faces
- Parapet + chajja-to-wall junctions
- Repair of rising-damp affected walls