Damp and Mould Before You Paint

Every February the corner behind Rob's wardrobe goes black. Anti-mould paint is on offer at the DIY shop. It's tempting, and it misses the point.

Mould grows where a surface stays damp, and paint can't take water out of a wall. Painting a damp wall is like wrapping a wet towel in cling film. The damp usually has one of three sources: condensation, when moist indoor air meets a cold surface; leaks from pipes, roofs or gutters; or rain getting in through the walls. They can combine, and the pattern alone doesn't prove which.

If you rent, report damp and mould promptly. You don't need to work out the cause first, or try a round of cleaning and window-opening before you report it.