What is a damp-proof course - DPC?

A damp-proof course, commonly referred to as a DPC, is the first layer of brick laid over a damp-proof membrane as a moisture barrier applied to foundations to prevent moisture rising into brickwork. A damp-proof course is imperative in maintaining the integrity of a building, as moisture ingress can cause many problems, both cosmetic and structural.






A damp-proof membrane is a roll of polythene strip that is applied on top of a concrete floor or foundation to act as protection against damp. The DPC is then built directly on top of the membrane. In most residential construction the DPC is a minimum of 200mm above ground level to exclude moisture seepage from the surrounding ground. Water is blocked from rising into walls and timber frames, which would otherwise result in rot and rising damp.

In many older properties where the original DPC has deteriorated, or was not installed, the fix for this was to have a professional contractor inject chemicals into the walls.

New technology now offers DIY enthusiasts the ability to reliably and cheaply inject their own chemical DPC. Chemical treatment is absorbed into the mortar and brickwork to provide a waterproof barrier once cured. The more recent DIY alternatives are faster to install and do not require drilling and injection, as they are drawn into the brickwork.