Signs of rising damp, and when it is something else

Genuine signs of rising damp

• A tide mark on ground floor walls, usually below about one metre
• White, fluffy salt deposits on the plaster
• Crumbling or blown plaster at the bottom of the wall
• Rotting skirting boards
• Damp present all year, not just in winter or after rain

Things often mistaken for rising damp

• Condensation low on cold walls behind furniture
• Bridging, where soil, paving or render lets moisture bypass a working damp proof course
• Leaks from pipes running in or along the wall
• Penetrating damp from splashback off paths, leaking downpipes or blocked gullies
• Hygroscopic salts left in old plaster that pull moisture from the air

Why meter readings alone are not enough

Standard moisture meters are designed for timber. On plaster and brick, salts give high readings even when a wall is not wet. A proper diagnosis looks at the pattern, the outside of the building and the history, not just a number on a meter.

Before you pay for a damp proof course

1. Check outside ground levels are at least 150mm below the damp proof course
2. Make sure air bricks are clear
3. Check render does not run down to the ground
4. Check for leaking gutters and pipes near the patch
5. Get an independent minded damp survey