Damp-Proof Course (DPC)

Layers of impermeable material (often plastic or bitumen) used to prevent passage of water. Either vertical (e.g. where room is below ground level to prevent lateral passage of water from ground into the walls) or horizontal, inserted at base of walls to stop rising damp. When inserting a new DPC in older buildings, a "chemical" form may be used that consists of impregnating wall at ground floor level with silicone, which percolates walls and forms barrier against rising damp.