Damp, mould and condensation: Getting your home ready for winter
It’s that time of year: the heating has gone back on, and somewhere in your home, a window has started to fog up each morning. For many of us, over the next few months, damp will stop being an abstract worry and start showing up as black spots or a mysterious musty smell.
The good news is that the damp problems faced by many UK homes are not just fixable, but even preventable. The trick is working out which kind you’re dealing with, and acting quickly.
What kind of damp are you dealing with?
Condensation is by far the most common form of damp, particularly in winter. Warm, moist air from everyday life, such as cooking or a hot shower, meets a cold surface like a window or an external wall and turns back into water. Left alone, that moisture is what feeds black mould. The giveaway is timing and location: it appears in cold spots, often behind sofas and wardrobes, and gets worse in winter.
Penetrating damp comes from outside. A blocked gutter or a slipped roof tile lets rainwater work its way into the walls, usually showing up as a defined patch that grows after heavy rain.
Traumatic damp is the less familiar name for water from a leak inside the building: a dripping pipe, a perished seal around the shower or a burst pipe in the flat upstairs.
Rising damp, where groundwater soaks up through the walls, tends to affect older properties, but is frequently misdiagnosed. It’s important to identify the cause of the damp before deciding how to treat it, as different problems need different solutions.
Getting condensation under control
It’s easy to underestimate how much water an ordinary household puts into the air. Guidance from various local council sources puts the figure at around 12 litres a day, rising to more than 20 if you dry your laundry indoors. All of that moisture has to go somewhere.
Luckily, small habits can make the biggest difference. Put lids on pans when you cook, and keep internal doors closed while you cook or shower so moisture doesn’t drift into colder rooms. Running the extractor fan is also key, but do check what it’s doing: some cooker hoods only filter the air and blow it straight back into the kitchen, steam and all. If yours has no duct to the outside, it isn’t removing moisture.
Dry laundry outside where you can. If you can’t, use a single room with the door shut and a window open a crack. A dehumidifier helps too, especially in a flat or a terrace with limited airflow.
You don’t need to sit in the cold to ventilate your home properly. RICS recommends opening your windows for five minutes every hour while you’re in a room. Keep your trickle vents (the small slots at the top of many modern window frames) open throughout the day to allow fresh air to circulate.
Heating matters too. Short bursts of heat followed by long periods of cold can encourage condensation, especially on cold walls. Keeping your home at a steady temperature, rather than turning the heating up high for short periods, can help reduce this.
Move furniture a few centimetres away from external walls to allow air to circulate, and wipe down windows on cold mornings to stop water collecting on the sills.
Dealing with what’s already there
Small patches of surface mould on sealant or paintwork can usually be cleaned with a mould and mildew product, which is a safer choice than bleach.
Wear gloves, a mask and eye protection, shut the door to the room and open the window while you work. Painting over mould without treating it only hides the problem for a few weeks. Larger areas should be left to a professional, and if mould keeps returning to the same spot, the moisture source needs fixing first.
If you do call someone in, choose carefully. Be wary of anyone who diagnoses damp using a moisture meter alone: the meters are reliable on timber, but on brick and plaster they can pick up salts and other conductive materials and give high readings where there’s no real problem.
RICS recommends getting an independent building surveyor to inspect the damp. They should follow the 2022 Joint Position Statement on damp. Unlike a damp-proofing company, an independent surveyor won’t try to sell you the repairs, so you can get an unbiased opinion on what’s causing the problem.
A note for landlords
Damp and mould sit at the top of the list of tenant complaints, and the rules are tightening.
On 9 October 2026, the Government opened a consultation on extending Awaab’s Law to private rented homes. In social housing, the Law already sets legal deadlines for landlords to investigate and fix serious hazards, including damp and mould. No deadlines are in force for the private sector yet.
Your existing duties still apply in the meantime, including keeping the home free of serious hazards and fit to live in.
Government guidance is clear that damp and mould shouldn’t be blamed on tenants’ lifestyles, and the practical advice is the same whatever happens with the consultation.
Respond to reports quickly and fix the cause rather than repainting over the symptom. Photograph any mould before it’s removed, keep a record of what you did, and go back after six weeks or so to check the problem hasn’t returned. And don’t assume a fan on the wall means a room is properly ventilated; an old or underpowered unit might be doing very little. Void periods between tenancies are a good moment to test fans and upgrade them to humidity-sensing models.
