What is rising damp?
Brick, limestone and mortar soak up moisture from the ground like a sponge. A damp proof course (DPC) is a barrier built into the wall near the ground to stop it. In older homes the original DPC can break down, and garden beds, paving or render can bridge over it. Moisture and the salts it carries then rise up the wall.
As the water evaporates, it leaves salt behind in the brickwork and plaster. That's what causes the white powdery deposits, bubbling paint and crumbling plaster you see at the base of affected walls.
Signs of rising damp
- A tide mark on internal walls, usually up to about a metre high
- Bubbling or flaking paint and blown plaster near the floor
- White salt deposits on bricks or plaster
- Crumbling mortar at the base of external walls
- Rotting skirting boards and a musty smell
How we fix it
First we confirm it really is rising damp and not a leaking pipe, a downpipe or a garden bed bridging the wall. Then we drill a line of holes along a mortar course at regular spacings and inject a chemical damp proofing product. It spreads through the masonry and forms a continuous water-repellent barrier.
Salt-contaminated plaster is removed and the wall is replastered with a salt-resistant render, so salts left in the wall don't come through the new finish. We'll also point out anything bridging the DPC outside, such as garden beds or paving that sit too high.
