What humidity should my house be in winter? (UK)
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Most damp and mould problems come down to one number: relative humidity. Once you know yours, it is much easier to decide whether you need to change habits, buy a dehumidifier or call a landlord.
How to measure it
A digital hygrometer (a small thermometer that also shows humidity) costs only a few pounds and is the most useful thing you can buy before spending money on anything else. Put one in your bedroom and one in the living room, away from windows, radiators and the kitchen. Check them in the morning and the evening for a week.
Where to buy (prices change often, so check the current price):
What your readings mean
| Reading | What it means | What to do |
|---|---|---|
| Below 35% | Dry air | Rare in UK homes in winter; turn the dehumidifier down or off |
| 40 to 60% | Healthy | Nothing, keep your habits |
| 60 to 70% | Too damp | Ventilate more, dry clothes differently, consider a dehumidifier |
| Above 70% | Mould risk | Dehumidifier plus finding the source of the moisture |
Short peaks after a shower or cooking are normal. What matters is where the reading settles a couple of hours later.
Bringing humidity down
- Use extractor fans and keep the bathroom door closed while showering.
- Open trickle vents and air rooms for 10 to 15 minutes each morning.
- Dry washing in one closed room with a window cracked, or with a dehumidifier.
- Keep the home at a steady temperature; cold rooms have higher relative humidity.
- Run a dehumidifier with a humidistat set to 50 to 55% so it only works when needed. See which type to choose.
Our guide to stopping condensation on windows goes into more detail.