1930s18.7% of homes here
Cavity walls become standard, generally with clay tile or slate roofs, cast-iron rainwater goods and suspended timber ground floors. Bay-fronted semis dominate.
What we usually find. Wall-tie corrosion and bridged cavities are the usual structural concerns, and sub-floor ventilation is often obstructed by later paths, patios or extensions, which brings damp and timber decay to the ground floor. Original roof coverings are typically at the end of their life.
Worth knowing. Cavity wall insulation retrofitted into this stock can cause damp on exposed elevations if the wall was not suitable. Establishing whether the cavity was filled, and when, is worthwhile.
Pre-190017% of homes here
Normally solid walls of brick or stone with no cavity, lime mortar, timber suspended floors and lath-and-plaster internally. Any damp-proof course is either slate or absent altogether.
What we usually find. Damp at low level is the most frequent finding, usually where a slate damp-proof course has been bridged by raised ground or by later solid floors and cement render. Chimney stacks, roof coverings and rainwater goods are often at or beyond the end of their serviceable lives, and earlier repointing in cement rather than lime can trap moisture and spall the brick face.
Worth knowing. Solid walls cannot be treated like cavity walls. Injected chemical courses and internal tanking frequently move the problem rather than resolve it, so the cause matters more than the last remedy applied.