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Condensation and mould

There is always some moisture in the air, even if you can’t see it. If air gets cold, it can’t hold all the moisture produced by everyday activities.

When moist air hits a cold surface, such as a wall, window, or a mirror, it turns into droplets of water which can form condensation and mould. This tends to be worse during the cold winter months.

Condensation and mould can appear on, or around windows, in corners, behind wardrobes and cupboards, and on any cold surface where there is little or no movement of air. Mould and mildew can also form on furniture, clothes and other fabrics such as curtains.

Condensation and mould can also rot wooden window frames and carpets.

There are four main things that cause condensation:

  • Too much moisture being produced in your home
  • Not enough ventilation
  • Cold surfaces
  • Not enough heat in your home.

You need to look at all of these things to reduce or cure condensation and mould.

Reducing condensation and mould

If you have mould in your home, it should be easy to remove.

Wipe down, or spray the affected surface with a safety approved fungicidal fluid, making sure that you follow the manufacturer’s guidelines for use. Wash, or dry clean clothes or fabrics that are affected, and shampoo carpets soiled by mould or mildew.

Important note: Don’t try to remove mould by brushing it off, or vacuuming. This will only spread mould spores throughout your home, and make things worse!

After you have cleared the mould, we advise you to re-decorate using a good quality fungicidal paint, and fungal resistant wallpaper paste, to help prevent mould coming back.

Important note: Don’t cover fungicidal paint with ordinary paint or wallpaper, as this will undo the effect of the fungicide.

For a long lasting cure for condensation and mould problems, you will need to take some positive steps to stop it coming back, and prevent re-growth of mould and mildew spores.

One of the first things to do is to look at your lifestyle in your home.

The only lasting way of preventing condensation and mould is to make sure your home isn’t damp. This means keeping your home warm, and ventilated so that air can circulate, helping to reduce cold spots.


Everyday activities that we carry out in our homes produce moisture in the air. Simple things that we take for granted such as breathing, making tea or coffee, cooking, washing and drying clothes, all add moisture to the air.

To give you an idea of how much extra water you could be producing in the air in your home, here are some common

Two people living at home3 pints (per day)
A bath or shower2 pints
Drying clothes indoors9 pints
Cooking and using a kettle6 pints
Washing dishes2 pints
Bottled gas heater used for 8 hours4 pints
Total moisture produced26 pints (3 1/4 gallons - 14.8 litres)

To prevent condensation in your home, which can lead to mould and mildew forming, you need to reduce the amount of extra moisture in the air.

There are many ways of reducing moisture in the air:

  • Hang your washing outside to dry. If you can’t do this, hang it in the bathroom with the door closed, and a window slightly open, or the extractor fan on (Important: Don’t put clothes on a radiator, or in front of a radiant heater or night storage heater).
  • Always cook using the smallest pan that will do the job, with the lid on, and turn down the heat as soon as the water has boiled.
  • Use the minimum amount of water for cooking vegetables.
  • When filling the bath, put cold water in first, then add the hot, this will reduce the steam created by up to 90%!
  • If you use a tumble dryer, make sure it’s vented outside your home, or of a condensing type.
  • If you have a gas cooker, don’t use it to heat your kitchen, because it produces moisture when
    burning gas.
  • Avoid using bottled gas heaters, because they produce about eight pints of water from an
    average sized gas cylinder.


Ventilating your home can reduce condensation. This also helps move air around your home to prevent moisture from settling. You need more ventilation in some rooms than others, especially the kitchen and bathroom. Keep the doors closed when they are in use, even if they have extractor fans.

  • Help reduce overnight condensation by cross-ventilating your home in the morning - slightly open a small window upstairs, and a diagonally opposite one downstairs for about half an hour. (Make sure that open windows will not create a security problem!)
  • Ventilate your kitchen when cooking, washing up, or using your washing machine by slightly opening a window. If your cooker has an extractor hood, make sure you use it.
  • Ventilate your bathroom while in use, and for about twenty minutes afterwards by slightly opening a top window or using an extractor fan if there is one - they’re not expensive to run, and are very effective.
  • Make sure that the extractor fan isolating switches are in the “on” position at all times.
  • Ventilate your bedroom by leaving a window slightly open overnight, or using trickle ventilators if fitted.
  • Allow air to circulate behind wardrobes and large cupboards.
  • Try not to overfill wardrobes and cupboards as this will stop air circulating, and increase the likelihood of mould or mildew forming.


Warm air holds more moisture than cold air. The warmer it is, the more moisture it can hold. Heating one room, and leaving the others cold, will lead to more condensation forming in the cold rooms.

If you have central heating with radiators in every room, it is best to have a medium level of heat throughout your home.

If you don’t have heating in every room, leave the doors open to allow some heat to spread to all your rooms. Avoid using paraffin and portable bottled gas as they give out a lot of moisture when in use, which will make condensation and mould worse.