A musty, mouldy smell is a sign that moisture levels are too high. Even if you cannot see mould, the smell often means spores are present on soft furnishings or hidden surfaces.
Step one: reduce moisture
Use a dehumidifier to bring humidity down to around fifty percent. This alone can remove the smell within a few days.
Step two: ventilate the room
- Open windows for short bursts.
- Leave internal doors open to improve airflow.
- Run extractor fans if available.
Step three: deep clean affected areas
Clean window frames, skirting boards and wardrobes with a mould spray or diluted vinegar solution. Wash bedding, clothes and upholstery where possible.
Prevent the smell returning
- Keep humidity between forty and sixty percent.
- Avoid drying laundry in poorly ventilated rooms.
- Use a dehumidifier in winter to prevent condensation.
Once humidity is under control, most musty smells disappear quickly.