When a damp proof course is ineffective or damp proofing was neglected during previous construction or renovations, rising moisture can form inside walls.

Rising damp can occur in a house in a variety of ways. Testing to the base of the damp walls during a building survey may reveal rising damp, but in more extreme situations when the damp has been neglected for extended periods of time, visible damp patches and hygroscopic salts on the wall surface may be observed.

Depending on the salts in the masonry and a number of other variables, removing the wall plaster to a height of one metre or more is necessary for an effective damp proofing treatment. Furthermore, the house will be better protected if a new damp proof course is installed inside the moist walls.