Mould and condensation

Published , updated

Guidance on how to deal with mould and condensation in your home. 

Mould caused by condensation can look unsightly and cause damage to your belongings and your property. Use our guidance below to reduce the effects of mould and condensation.

What is condensation?

Air always contains some moisture, even if you cannot see or feel it. Condensation occurs when warm air collides with cold surfaces, or when there’s too much moisture in your home. Condensation is a more frequent problem in cold weather and it can appear on or near windows, in corners and in wardrobes or cupboards.

Dampness caused by excessive condensation then leads to mould growth on walls and furniture, mildew on fabrics or rotting of wooden window frames. These conditions are also ideal for dust mites, which thrive in moist environments.

Unlike damp, condensation does not leave a ‘tidemark’ – this type of dampness might have another cause, such as a water leak. Our tick sheet included with this leaflet can help you identify whether your property has mould or damp.

What are the causes of condensation?

There are three main factors that contribute to condensation.

Too much moisture in the air

As mentioned there is always moisture in the air, but it can be increased by a number of simple, everyday activities. This includes things like cooking, showering, using a tumble drier or drying washing indoors. Even breathing adds moisture into the air.

Not enough ventilation

If the air in your home is unable to circulate freely, it increases the risk of condensation. A good example of this is when wardrobes or sofas are placed flat against a wall, restricting air flow.

Cool temperatures

The colder your home is, the more likely you are to have condensation. Heating one room and leaving others cold is common, but this makes condensation worse in the unheated rooms. It is better to have an even temperature throughout the house.

You need to take all of these things into account in order to tackle condensation in your home.

Reducing condensation

It is your responsibility to ensure that the property you live in is free from condensation and mould. There are a number of ways in which you can try to prevent condensation from becoming a problem in your home.

Drying clothes

Where possible, always dry clothes outside. If drying inside, use a clothes horse (not a radiator) and dry next to an open window or in a bathroom with an extractor fan.


Ventilate your kitchen and bathroom for about 20 minutes after use, by opening a small window or using an extractor fan if possible – they are cheap to run and very effective. Always keep the door to the room shut while you do this.

Ventilate your bedroom by leaving a window slightly open at night (if safe to do so) or open a window in the morning for 30 minutes when you wake up. Use trickle ventilators if fitted.


Avoiding condensation is about balance, so even when ventilating your property you should also make sure the temperature in your home is consistent and warm – it should not drop below 15°C at any time. Ideally, the temperature would be between 16-18°C in your home.

Most modern boilers cost less to run if the heating is kept on low for longer periods, rather than short bursts of heat. If you’re worried about the cost of heating your home, the Money Saving Expert website has some great advice for keeping these costs down.

Action you can take to reduce moisture:

  • Keep a small gap between large pieces of furniture and the walls, to help air circulate. Where possible place furniture against internal walls.
  • If you use a tumble drier, make sure that you vent it to the outside of the property.
  • Always cook with pan lids on and turn the heat down once the water has boiled. Make sure you keep a small window open to allow excess moisture to escape. If you have an extractor fan leave it running for around 10 minutes after you’ve finished cooking.
  • When filling your bath, run the cold water first then add the hot – it will reduce the steam by 90%.
  • Do not block permanent ventilators or airbricks.
  • Do not draught-proof the bathroom or kitchen windows

Buy a temperature and humidity monitor to help you keep an eye on the level of moisture in your home. They are available from as little as £3.

Identifying and removing mould

If you find water on the inside of your windows or on other cold surfaces, it is likely to be condensation. You may also find black mould on walls or ceilings, or blue/green mould on leather or wood. If you have mould it is usually found in cold corners or cupboards.

Mould, although unpleasant, can be treated very easily. You should remove mould as soon as it appears, to prevent it from spreading.

  • Wipe down affected areas with a fungicidal wash or spray that carries a Health and Safety Executive (HSE) approval number. Always follow the instructions very carefully. DO NOT use bleach.
  • After treatment, use fungicidal resistant paint to help prevent mould growth recurring.
  • Dry-clean mildewed clothes, and shampoo carpets.
  • Do not try to remove mould using a brush or vacuum cleaner.

If you suspect asbestos please contact Derwent Living in the first instance with details and photos using the form below. 

Damage from damp

Mould is most commonly caused by condensation, but other causes of moisture could be:

  • Leaks e.g. windows, roofs or guttering
  • Penetrating moisture through walls

If you are still concerned that any unusual marks on your walls might be caused by something other than condensation, you should contact Derwent Living using the form below.

Adding photos or video will help our team to identify the problem more easily and speed up the process.

Report mould

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We will send someone out to inspect your property and monitor the levels of condensation in your home.

If you disagree with any of our findings, you should contact your local council’s Environmental Health office – they are independent of Derwent Living and they will investigate further on your behalf.

The NHS also has help and advice on the health problems caused by mould and condensation.