Rising damp is groundwater soaking up through a wall from the soil below, usually because the original damp-proof course has failed or was never there. It shows up as a tide mark, bubbling paint, or crumbling plaster low down on the wall, rarely higher than about a metre.
Damp on a wall is not always rising damp, and the fix is different for each, so it is worth getting right.
If the damp sits low and runs along the wall in a band, rising damp is the likely cause.
Most homes have a damp-proof course built into the wall near the bottom, a layer meant to stop moisture climbing past it. On older houses it can break down over time, or it was never installed. Sometimes a raised garden bed, a new path, or plaster bridged across the course gives the damp a way around it. Once moisture is moving up the wall, it carries salts from the ground with it, and those salts keep pulling in moisture even after the source is dealt with.
Covering rising damp with a coat of paint or a waterproof sealer traps the moisture and pushes it somewhere else. The paint bubbles, the plaster blows, and you are back where you started in a season or two. Damp has to be treated at the source, not hidden. That is the part most quick fixes get wrong.
The right repair depends on the cause. It can mean installing a new chemical damp-proof course, excavating and sealing the wall below ground where the outside level is the problem, removing the salt-laden plaster, and re-plastering with a proper waterproof backing coat. We did exactly this on a damp excavation in Rosebank where the original course had failed.
If you have a damp line creeping up a wall, see our damp-proofing work or get in touch and we will come and find what is actually causing it.
Tell us what you are seeing and we will come and take a look, no charge.
