Damp can be a serious problem for your home and your health. The longer it goes on, the more expensive it will be to repair any damage. Living with damp and mould also puts you at greater risk of respiratory problems, allergies and asthma, and can affect your immune system.
It’s been a wet week, with more bad weather forecast to come. If you’re worrying about damp, you’ve come to the right place.
You can tackle small amounts of damp yourself by making simple lifestyle switches and potentially buying a dehumidifier. If your damp problem is serious, you may need to call in a professional.
Read on for five tips on treating damp to get you started.
Or, if you’re looking for a dehumidifier, jump straight to our list of the best dehumidifiers to buy.
Diagnose your damp problem
You need to establish exactly what type of damp you have, and what’s causing it, or the problem will just keep coming back.
Condensation is caused by warm, moist air meeting colder air or a colder surface. It’s more of a problem in winter – when walls tend to be colder than the outside air – than it is in the summer.
Windows dripping with water are an obvious sign of condensation, but you might also notice dark mould appearing around your windows and, in time, your window frames decaying.
Penetrating damp is caused by water leaking through walls, getting in through gaps in window frames and doors, burst gutters and bricks that have become porous.
Penetrating damp is a particular problem with older properties. In newer homes, cavity wall insulation often helps, although cavities that have been filled with debris that take in moisture from the outside wall and pass it to the inner wall can themselves pose a problem.
Rising damp is when ground water is sucked upwards from the ground through bricks, sandstone and mortar. Tide marks on your wall suggest rising damp, rather than condensation.
If you have rising damp, you’ll almost certainly need professional help to sort it. Use our Which? Trusted Traders tool to find a tradesperson you can trust.
Stop damp coming back again
There are two reasons why you’d have damp: moisture coming in from outside, and moisture inside not being able to get out.
To stop water coming in, keep on top of home maintenance, as prevention is always better than cure. Check your roof after spells of wet and windy weather. Clear gutters that are blocked with leaves and replace any damaged ones. Consult a professional if you see crumbling mortar.
Replace windows that are old and leaking. This won’t be cheap, but a leaky window is probably costing you money in heating and leading to mould growth.
Keep your home warm, but avoid sudden increases and decreases in temperature, which can lead to condensation. Using your thermostat to a maintain a more constant temperature should help.
To allow moisture to escape, ventilate regularly. It’s tempting to keep windows tightly shut in winter but moisture needs to go somewhere. Open windows, particularly after cooking and showering, and use your extractor fans.
Clean up damp and mould
Wipe moisture away from misty windows and the surrounding area down with a soft, dry cloth.
Keep a sharp eye out for mould. Wear gloves and, if you have goggles, pop them on before tackling mould. Open the window but keep the door closed to avoid mould spores spreading. Dry the area with a rag afterwards, and throw it away rather than attempting to reuse it. Vacuum the floor to capture any mould spores you’ve dislodged.
If you’re clearing up after a storm, contact your insurance company and follow its advice: your insurer might stipulate that any repair work needs to be carried out by their appointed professionals.
Buy a good dehumidifier
A dehumidifier can help you by extracting water from the air in your home. You need to choose wisely, though. Make sure you:
- buy one that works well: we’ve uncovered some that really struggle
- buy one that’s the right capacity: you don’t need a great hulking 21-litre dehumidifier if there’s just one of you in a tiny flat with a mild damp problem. But, equally, you can’t buy an 8-litre dehumidifier and expect it to tackle severe damp in a large property
- know where you’re going to use it: in a nutshell, refrigerants work well in the home but poorly in unheated rooms like garages; desiccants work well in both.
You’ll also need to consider size, weight and whether it has castors (particularly if you have reduced strength and plan on moving it around) and how much noise it makes (you won’t want it making a racket if you’re working from home).
Our guide to buying the best dehumidifier explains all the factors to consider.
Make sure you’re using your dehumidifier properly
Just as important as buying the right dehumidifier is making sure you’re getting the most out of it.
Resist the temptation to tuck it discreetly into a corner. Dehumidifiers tend to need to be placed at least 30cm away from the wall so that air can circulate around them.
Set up your dehumidifier somewhere central in your home, if you can, keeping internal doors open, so that the dehumidifier can draw in moisture from a whole range of sources across your home, including your bathroom and kitchen. Moist air migrates towards drier spaces so keep external windows closed to prevent moisture outside being attracted inwards.
Clean the filter regularly to avoid it getting clogged with dirt. Check the manufacturer instructions first to avoid damaging the filters through over-enthusiasm. Some manufacturers say you should vacuum the filter, while others say to rinse it in warm, soapy water. It might well need replacing after a time.
Empty the tank regularly: once it’s full, it will stop extracting water so that it doesn’t overflow. Don’t leave the water sitting in the tank for days. Make sure you’re cleaning and drying it according to the manufacturer instructions so that you don’t get mould there too.
Read more about how a dehumidifier works.
Which? dehumidifier reviews
We’ve tested more than 45 dehumidifiers. For each dehumidifier, we assess: how much water it extracts from damp air, how much energy it uses, how noisy it is (and whether the noise it makes is an irritating one) and whether the humidistat function works well, if there is one.
We also put any dehumidifiers that can be operated via a smartphone app through a privacy and security test, to check for any loopholes that hackers could exploit.
Here are some dehumidifiers we’ve reviewed at a range of price points: Which? members can read the full reviews to find out which ones we liked and disliked.
- Meaco 25L Ultra Low Energy – £285 (pictured above). A large, refrigerant dehumidifier with a more sophisticated laundry-drying mode than most
- Ebac 3850e 21 Litre – £230. A large dehumidifier with an auto mode designed to determine the most appropriate relative humidity (RH) for your home (but no humidistat allowing you to request to specific RH)
- ElectriQ CD20PRO-LE-V2 – £230. A refrigerant dehumidifier that you can control from your smartphone app and through Alexa or Google Assistant.
- Ecoair DD3 Classic MK2 – £215. A desiccant dehumidifier that runs quietly
- Russell Hobbs 20 Litre RHDH2002 – £195. a refrigerant dehumidifier with a large capacity.
- Logik L20DH19 – £130. A Currys own-brand dehumidifier with castors to make it easier to roll around: something a fair few dehumidifiers don’t have
- Argos Challenge 10L 849/9493 – £120. A frills-free Argos own-brand dehumidifier.
Or head over to our dehumidifier reviews to see all those we’ve tested.