How can I tell if I have rising damp?
Rising damp is groundwater moving up through walls by capillary action, and it produces a fairly distinctive pattern of symptoms. But it is also the most over-diagnosed damp problem in Britain, so the pattern is worth knowing properly.
The classic signs
- Damp patches on ground-floor walls, typically rising no higher than 1 metre
- A 'tide mark', a visible line where the moisture stops
- White, fluffy salt deposits (ground salts carried up with the water)
- Peeling wallpaper or blown paint at low level
- Crumbling or 'blown' plaster that sounds hollow when tapped
- Rotting skirting boards and a persistent musty smell
Why it's so often misdiagnosed
A damp patch at skirting level can just as easily be a leaking pipe, a bridged damp proof course (soil, render, or a raised patio bridging the DPC from outside), penetrating damp through defective pointing, or condensation collecting at the coldest part of the wall. Each has a completely different fix, and only one of them needs an injected DPC. London's Victorian and Edwardian housing stock, much of it built with no DPC or with slate DPCs that have failed, genuinely does suffer rising damp; but in our experience a large share of 'rising damp' diagnoses turn out to be something else.
If you're seeing these signs, an independent survey confirms the true cause with moisture profiling before you spend anything on treatment.