Why is mould appearing in my bedroom, and what should I do about it?
Mould in a bedroom is almost always the meeting of warm, humid air with a cold surface. People exhale a surprising amount of water overnight, the bedroom door is usually closed, and a corner of the room near an external wall sits cold enough for water to condense and feed the mould. Treating the spores without treating the conditions that grew them rarely works.
What it usually looks like
These are the symptoms readers describe most often. None of them alone is diagnostic, but together they build a picture.
- Black spotting in upper corners or behind furniture
- Musty smell on bedding or in the wardrobe
- Damp patch that returns after cleaning
- Wallpaper lifting in cold corners
Most common in: Victorian terrace · Edwardian semi-detached · New-build flat · Loft conversion
Before you buy anything
Watch the house respond as you scroll.
These checks are listed in the order we would work through them. The illustration on the left changes with each one, so you can see what each check is actually addressing before deciding whether it is worth doing.
Black spots in the corner behind the wardrobe. The wall is cold, the air is wet, and nothing moves it.
Pull furniture six inches away from external walls
A wardrobe pressed against a cold external wall traps cool, still air which condenses overnight. The gap alone often clears a recurring patch.
Sleep with the bedroom door open if possible
A closed door allows humidity from overnight breathing to build to far higher levels than a household with circulating air. The difference is often visible within a week.
Add or fix bedroom ventilation
Bedrooms are the most under-ventilated rooms in most UK homes. Trickle vents open at night make a measurable difference without affecting warmth significantly.
Measure the wall temperature where the mould appears
If the wall is below twelve degrees in winter, no amount of ventilation will permanently solve the problem. Insulation on that wall is the real answer.
Treat the mould with an appropriate fungicide before redecorating
Painting over mould seals the spores in. They will return through the new paint within months unless they have been killed first.
Products that may help
Only consider these once the checks above have been ruled out. A product fitted into the wrong cause is rarely satisfying.
The cheapest answer to mould in the bedroom is usually the one that addresses the cause rather than the symptom. The list above is in the order we would work through it, because the checks at the top tend to rule out the most expensive mistakes further down.
Run the Home Comfort Score for this room
A two-minute reading gives you a number to compare against after each improvement, so you know what is actually working.