A musty smell is usually caused by mould or fungal growth somewhere, often where you can't see it: behind furniture, inside wardrobes, under floors, in a cellar or in damp timber. It means there's moisture where there shouldn't be, so the source needs finding rather than covering up with air fresheners.
People can live with a musty smell for years and stop noticing it, until a visitor mentions it or they come back from holiday and it hits them at the door. That damp, earthy smell is caused by mould and other fungi growing and giving off gases. Where there’s that smell, there’s moisture.
Where to look
- Behind and under furniture on outside walls, and inside wardrobes and cupboards on cold walls. Pull them out and look at the back of the furniture as well as the wall.
- Under carpets and behind skirtings, especially on ground floors.
- Under suspended timber floors. Blocked air bricks, high ground levels or water in the subfloor create a damp, still void. Lift a board or use a hatch if you can.
- Cellars and basements.
- Under the stairs, particularly where the stair cupboard sits against an outside or party wall.
- Around baths, showers and sinks, where a slow leak can soak the floor without obvious signs above.
- Loft spaces, where condensation on the underside of the roof can cause mould on timbers.
What the smell might mean
- Surface mould from condensation. Unpleasant, but usually straightforward to deal with once ventilation and heating are improved.
- Wet rot or dry rot in timbers. A strong mushroomy smell, especially with soft or cracked timber, shrinking skirtings or springy floors, needs investigating promptly.
- A leak. If the smell is concentrated in one area, check pipework and the floor underneath.
What not to do
Air fresheners, scented candles and plug-ins just mask it, and anti-mould sprays on what you can see won’t touch what you can’t.
Getting rid of it
Find and fix the moisture source, clean or remove mouldy materials, dry the area out and improve ventilation. Under floors, that usually means clearing air bricks and making sure air can flow through the void. Soft furnishings and carpets that have gone mouldy may need replacing.
If you can’t find the source, a survey can. A surveyor will look at the floors, walls, timbers and ventilation, inside and out.
When to call a specialist
If your house smells musty and you can't find the cause, or you suspect rot under the floor, get a damp and timber survey. Book a survey with All Dry on 01226 287181 or email info@alldrydampproofing.com.
Frequently asked questions
Is a musty smell always mould?
It's usually mould or other fungal growth, which means there's moisture somewhere.
Can a musty smell mean dry rot?
It can; a strong mushroomy smell with damaged timber should be checked promptly.
How do I get rid of a damp smell?
Find and fix the moisture source, clean or remove affected materials and improve ventilation.