Damp Patch High on the Wall? Why It’s Usually the Roof, Not Rising Damp

If you have a damp patch or staining high up a wall or on an upstairs ceiling, you may have been told it is “rising damp”. In most cases, it is not — and treating it as rising damp will not fix it.

Why it is probably not rising damp

Rising damp comes up from the ground and rarely climbs more than about a metre up a wall. So if your damp is higher than that — upstairs, near the ceiling, or on a chimney breast — it is almost always coming from above, not below. That is called penetrating damp.

Where the water is really getting in

Penetrating damp means water is finding its way in from an external fault higher up, then tracking down inside. Common causes are:

• A leaking or blocked gutter spilling water down the wall.
• Failed lead flashing where the roof meets a wall or chimney.
• A slipped or cracked tile or slate.
• Cracked pointing or render letting rain soak in.
• A faulty chimney or worn flaunching.

The tell-tale signs

Two things usually give it away: the stain gets worse after heavy rain, and there is a plausible water route above it (a gutter, valley, flashing or chimney). If a damp-proofing firm treats the inside of the wall without fixing that external cause, it just keeps re-wetting.

The fix

The real fix is to trace the true source and repair it at the roof or gutter. As roofers, that is exactly what we do — find where the water is getting in and stop it, rather than papering over the inside.