A close-up photograph of the lower four courses in a red brick wall, with weeds growing where it meets the ground. There is an airbrick very close to ground level. The holes in the airbrick are blocked with dirt.

This house has a suspended timber ground floor and through-wall air vents at a low level, just below its damp-proof course. The blocked vents stop air flow under the floor, leading to damp floor timbers and moisture in the air, creating condensation.

Also, the ground level has been raised, meaning that water can bypass the damp-proof course and get into the house.

Source of moisture: natural groundwater and penetrating water evaporating in the space between the ground and the floorboards due to high humidity and an unventilated sub-floor void.

Repair: clear the air vents and lower the ground level.

Damp and mould consumer guide