Condensation Prevention: A Ventilation Checklist for UK Homes

Condensation happens when moist air meets a cold surface. You can’t eliminate moisture from daily life — cooking, showering, breathing, and drying clothes all release water vapour — but you can stop it building up and stop it reaching the coldest surfaces in the first place.

Daily habits

• Cover pans while cooking and use extractor fans or open a window — boiling pans release a surprising amount of moisture.
• Close the kitchen and bathroom doors while cooking or showering, so moisture doesn’t spread through the house, then ventilate that room directly.
• Don’t dry laundry on radiators indoors if you can avoid it — a full load of wet washing can release several litres of water into the air as it dries. If you have to dry indoors, keep the door shut and a window cracked in that room, or use a vented tumble dryer/dehumidifier.
• Open windows for 10–15 minutes each morning, even in winter, to clear overnight moisture — a short, sharp burst loses less heat than leaving a window ajar all day.

Heating

Keeping a home consistently at a moderate background temperature (rather than letting rooms go cold and then blasting the heating on) keeps wall surfaces above the temperature at which condensation forms. NHS-affiliated guidance for households with children suggests keeping the home above 15°C where possible, particularly in bedrooms overnight.

Ventilation

• Make sure trickle vents on windows aren’t painted shut or blocked.
• Use extractor fans in kitchens and bathrooms, and let them run for 15–20 minutes after cooking or showering, not just during.
• Don’t block air bricks or vents at the base of external walls — these are there to ventilate underfloor voids and cavity walls.
• Leave a gap between furniture and external walls to allow air to circulate rather than trapping a cold, still pocket of air where condensation and mould can form unnoticed.

When habits aren’t enough

If you’re already doing all of the above and still getting consistent condensation, the underlying issue may be poor insulation (cold walls) or genuinely inadequate ventilation for the household size, and might need a dehumidifier (see our dehumidifier buying guide) or a positive input ventilation (PIV) system, which a qualified installer can advise on.