Is rising damp common in old buildings?
A. Rising damp is commoner in old buildings than new ones but rarer than often supposed. Modern buildings keep water out with a system of barriers: damp-proof courses (DPCs) have been required in walls since 1875 and damp-proof membranes (DPMs) in floors from the 1960’s. Most old buildings lack these and therefore damp rises to some degree. This is usually not a problem where the construction can ‘breathe’, allowing evaporation, and may actually be advantageous in humidifying overly-dry centrally-heated buildings. Excessive dampness arises where the moisture equilibrium is disturbed, as with misguided attempts to seal surfaces. Q. How is rising damp diagnosed? A. Rising damp is widely misdiagnosed on the basis of high electrical moisture meter readings alone. Elevated readings occur not infrequently in old buildings that are virtually dry, due to salt deposition from evaporation, or can indicate another problem altogether, such as penetration from rainsplash. If rising damp exists, the
