Dampness, condensation and mould growth in dwellings is a commonplace problem, especially in older buildings. Condensation can often be seen as water droplets on windows or water pooling on windowsills. If you find patches of mould on walls, furnishings or clothes and have patches of damp it is possible condensation may be the cause.

Watch this video from the Energy Saving Trust and find out how to manage condensation in your home to prevent damp and mould.

The following advice may help you reduce the problem:

Condensation in dwellings

It is not always easy to tell if your damp problem is caused by condensation, but there are some key differences between condensation and other forms of damp.

Condensation is usually found on north facing walls and in corners, in cupboards and under work surfaces – in fact wherever there is little air movement. 

Other kinds of dampness, such as rain or plumbing leaks, usually leave a ‘tidemark’.   

Condensation can often be characterised by mould growth – mould generally grows on cleaner water so is unlikely to grow on moisture from penetrating or rising damp.

The causes of damp in the home

If you are not sure what is causing the damp in your home, start by checking pipes and overflows and under sinks to see if there are any obvious leaks. Have a look outside, too – you may be able to see if there are slates missing from the roof or cracked gutters or rainwater pipes.

If you live in a new or recently modernised house or flat, don’t forget that it may not have dried out from the water remaining after the building work. It usually takes 9 to 18 months for this to happen and you may need to use more heat during that time.

Condensation and mould growth

Every home gets condensation at some time – usually when lots of moisture and steam are being produced, for instance at bath-times, when a main meal is being cooked or when clothes are being washed. It is quite normal to find your bedroom windows misted up in the morning after a cold night. 

Air can only hold a certain amount of water vapour – the warmer it is the more it can hold.  If air is cooled by contact with a cold surface such as a mirror, a window or even a wall, the water vapour will turn into droplets of water-condensation.  So the warmer you keep your home the less likely you are to get condensation.

Mould appearing in your homes

For mould growth to occur there needs to be a sufficient amount of water available, this is why mould growth often occurs with condensation or dampness. This type of mould looks like 'black spots' and is typically found along skirting boards or ceiling edges.

How damp, condensation and mould affects your health

If your home is damp or has lots of condensation, the chances are the house will be a cold house.  Living in a cold house may lead to negative health effects, therefore, it is important to keep your house warm.

Mould produces tiny spores which can cause an allergic reaction and make existing breathing problems worse. However house dust mites are the most common triggers of asthma rather than mould growth. House dust mites thrive where the amount of ventilation is reduced, warmer indoor temperatures and high humidity. These conditions can also lead to condensation. 

Getting rid of mould

To kill and remove mould, wipe down or spray walls and window frames with a fungicidal wash that carries a Health and Safety Executive (HSE) 'approval number', and ensure that you follow the instructions for its safe use. These fungicidal washes are often available at local supermarkets. Dry-clean mildewed clothes, and shampoo carpets. Do not try to remove mould by using a brush or vacuum cleaner.

After treatment, redecorate using good-quality fungicidal paint and a fungicidal resistant wallpaper paste to help prevent mould recurring. The effect of fungicidal or anti-condensation paint is destroyed if covered with ordinary paint or wallpaper.

The only permanent cure is to reduce the amount of condensation in your home. Remember, the way you use your home affects the amount of condensation you get. This does not mean that you should alter your habits drastically, just be extra mindful and follow this advice.

Gas boilers

It is important that your heating system is checked regularly so that it works efficiently. A gas boiler which is not in good working order can produce more moisture. Ensure you have a current satisfactory gas safety certificate by a Gas Safe Registered Engineer.

Reducing your energy costs

You will get less condensation if you keep your home warm most of the time. This is not easy with fuel prices so high, but try to remember the following:

Heating one room to a high level and leaving other rooms cold makes condensation worse in the unheated rooms. Instead, try to leave some background heat on through the day in cold weather.  Most dwellings take quite a long time to warm up, and it may cost you more if you try to heat it up quickly in the evening. If you don't have heating in every room, you could keep the doors of unheated rooms open to allow some heat into them.

If you can’t afford to spend more on fuel because of high quarterly bills, ask your fuel supplier or your local gas or electricity board about their budget schemes, for example fuel saving stamps, which help to spread the cost of fuel.

Heaters

To add extra heat to rooms without any form of heating, it is better to use electric heaters, for example oil-filled radiators or panel heaters, on a low setting. Try not to use portable bottled gas heaters in homes suffering with condensation as they give out a lot of moisture whilst in use.  Contrary to popular belief, it is actually cheaper to heat a room with on-peak electricity than by bottled gas heaters.

If you use bottle gas and paraffin heaters, you will need to allow extra ventilation. Flueless heaters of this sort produce more than a pint of water for every pint of fuel they burn. So, using a bottled gas heater for 8 hours would produce around 4 pints of moisture. 

Don't use your gas cooker to heat your kitchen as it produces moisture when burning gas. (You might notice your windows misting over).

Insulating your home

Condensation forms more easily on cold surfaces in the home, insulation and draught proofing can help keep your home warmer. Loft and wall insulation are the most effective forms of insulation. If you use draught proofing remember that you should not block permanent ventilators or airbricks and do not draught proof kitchen or bathroom windows. You may be eligible for financial assistance for insulation and heating. Call our energy advice line on 0800 500 3076 for further information.

Drying clothes

Drying clothes indoors, particularly on radiators, can increase condensation unless you open a window to allow air to circulate. Up to 9 pints of excess water can be produced by drying your clothes inside. Hang your washing outside to dry if at all possible or hang it in the bathroom with the door closed and a window slightly open or extractor fan on. Don't be tempted to put it on radiators or in front of a radiant heater.

If you have a tumble dryer which is not vented to the outside you will need to allow more ventilation when you use it.

Reduce condensation when having a bath

When filling your bath, run the cold water first then add the hot - it will reduce the steam by 90% which leads to condensation.

Stop clothes from getting mouldy in wardrobes

Don’t overfill cupboards and wardrobes. Always make sure that some air can circulate freely by fitting ventilators in doors and leaving a space at the back of the shelves.

Chimneys

Never block up your chimney completely. If you are blocking up a fireplace, fit an air vent to allow ventilation.

Kitchen and bathroom doors

Keep kitchen and bathroom doors shut, particularly when cooking, washing or bathing – otherwise water vapour will spread right through the house and condensation will probably reach other rooms.

Ventilating your home

The more moisture produced in your home, the greater are the chances of condensation, unless there is adequate ventilation. Nobody likes draughts, but some ventilation is essential.

Help to reduce condensation that has built up overnight by opening to the first notch a small window downstairs and a small window upstairs (they should be on opposite sides of the house, or diagonally opposite if you live in a flat). At the same time open the interior room doors, this will allow drier air to circulate throughout your home. This should be carried out for as long as possible each day.

Ventilate your bedroom by leaving a window slightly open at night or use trickle ventilators if fitted.

Reduce the risk of mildew on clothes and other stored items, by allowing air to circulate round them; remove 'false' wardrobe backs or drill breather holes in them; place furniture on blocks to allow air to circulate underneath; keep a small gap between large pieces of furniture and the walls; and where possible place wardrobes and furniture next to internal walls instead of external ones.

Pull shelves away from the backs of wardrobes and cupboards; never overfill wardrobes and cupboards as it restricts air circulation.

Important advice: make sure that accessible windows will not cause a security problem - remember to close windows when you go out.

If you have an extractor fan use it when cooking or having a bath /shower to stop the windows getting steamed up and keep it running for a while after you have finished.

Make a difference now!

Don’t allow kettles and pans to boil away any longer than is necessary.

Always cook with pan lids on and turn the heat down once the water has boiled.  Only use the minimum amount of water for cooking vegetables

The key points to remember to control condensation 

• Try to reduce the amount of moisture you produce 
• Improve ventilation in your home
• Try and maintain an adequate temperature throughout your home

Read our damp and mould leaflet.

Here are some further top tips for reducing damp and mould in your home or property:

• Maintain a good level of heating within the property and ensure it's warming the house evenly
• place radiator reflector panels behind your radiators
• close curtains or blinds to keep the heat in
• turn off taps whilst brushing your teeth
• pull furniture away from the walls
• keep humidity between 40 - 60% (purchase a hygrometer!)
• cook with saucepan lids on to reduce condensation, close the kitchen door and open a window
• dry clothes outside where you can 
• wipe away condensation around windows
• clean off mould with a spray containing bleach
• paint affected areas with mould-resistant paint
• keep the bathroom door closed while having a bath, or ensure your extractor fan is turned on
• stop condensation forming on windows by rubbing a small spot of washing up liquid over the surface with a cloth. Try this at home or in the car - taxi drivers have been doing this for years
• prevent condensation forming on windows by cutting a potato in half and rubbing it across the window, buffing with a cloth afterwards.