Why bedrooms
Two people breathing overnight add a lot of moisture to a closed room. Bedrooms are often kept cooler than living rooms, and many have external walls. Behind wardrobes, beds and drawers the air does not move and the wall stays cold, so moisture condenses there and mould grows unseen.
What helps straight away
- Pull furniture 5 to 10cm away from external walls
- Open trickle vents or crack a window for part of the night
- Keep the bedroom at a steady low heat rather than cold all day
- Do not dry clothes in the bedroom
- Keep wardrobe doors slightly open and do not overfill them
Clothes and fabrics
If mould has got onto clothes, wash them on the hottest setting the label allows and dry them outside or in a dryer. Mould on soft furnishings like mattresses often cannot be fully cleaned out.
When it is more than condensation
If the mould is on one wall only and gets worse after rain, check for penetrating damp. If it is in neat lines at the ceiling edge, the wall or ceiling may have missing insulation. A survey will tell you.
Last reviewed 15 November 2026 by the Home Damp and Mould team. Read our editorial policy.