How to prevent condensation, damp and mould in your home

Condensation forms when warm, moisture-laden air meets a cold surface. It often appears on windows, external walls and behind furniture. Damp can also come from leaking pipes, damaged roofs, blocked rainwater goods, penetrating rain or moisture rising through the building fabric. The correct remedy depends on the cause.

How can you tell condensation from another damp problem?

Condensation is commonly worse during cold weather and in rooms where moisture is produced, such as kitchens, bathrooms and bedrooms. It may show as water on glass or dark mould in corners. A localised patch that grows after rain, a tide mark near floor level or staining below plumbing may suggest a leak or building defect.

Reduce moisture at its source

• Use extractor fans while cooking and bathing and leave them running for the recommended period afterwards.
• Keep lids on pans and avoid drying clothes indoors where possible.
• If clothes must dry inside, use a ventilated room and keep the door closed.
• Do not use unflued bottled-gas or paraffin heaters; they release water vapour into the room.

Ventilate without making the home unnecessarily cold

Keep purpose-provided vents open, including trickle vents and air bricks. Open windows briefly to purge moist air where appropriate. Avoid blocking ventilation behind furniture; leave a small gap between large items and cold external walls.

Use steady, appropriate heat

Very cold surfaces encourage condensation. A lower, more consistent background temperature can be more effective than allowing rooms to become very cold and then heating them sharply. Heating does not remove moisture on its own, so it must work with ventilation.

Deal with mould safely

Small areas may be cleaned using a suitable mould-removal product and its safety instructions. Do not dry-brush mould, as this can release spores. Larger, recurring or unexplained growth needs proper investigation. Anyone with health concerns should seek appropriate medical advice.

When should you get help?

Arrange an inspection when damp persists despite sensible heating and ventilation, follows rainfall, appears near plumbing, damages finishes or affects several rooms. Repair the source before redecorating. If you rent, report the problem promptly to your landlord or housing provider and keep dated photographs and correspondence.