Controlling Condensation and Mould

Condensation occurs when there is a build up of moisture in the air. There is always some moisture in the air, even if you can't see it. Moisture is produced during everyday activities such as cooking, bathing, drying clothes and even breathing.

What causes condensation?

Warm, moist air condenses and forms water when it comes into contact with a cool surface, such as a wall or window.

Condensation is not caused by water penetrating from outside of your home, it is caused by moisture which is produced from inside the home.

There are four main factors that cause condensation:

  • Too much moisture being produced within the home
  • Not enough ventiliation
  • Cold surfaces
  • The temperature of your home.

Everyday activities add extra moisture to the air inside your home. You may notice that there is condensation on your windows first thing in the morning, this is because one person breathing ads half a pint of moisture to the air over night.

Problems that can be caused by excessive condensation

If the condensation can’t dry out it will cause mould to form on walls and furniture, and mildew to grow on clothes and other fabrics. Timber windows can become rotten as a result of excessive condensation.



What can I do to prevent condensation?

Avoid creating excessive moisture

  • Dry clothes outside whenever possible or in a well ventilated room
  • Keep saucepan lids on when boiling water or cooking
  • Ensure thimble dryers are vented to the outside
  • Avoid using bottled gas heaters
  • Wipe down the bath/shower after each use.

Reduce moisture in the air when using hot water

  • Keep kitchen and bathroom doors shut to prevent steam getting into the colder rooms
  • Use extractor fans when cooking or washing
  • Open windows and vents so that steam can escape
  • Wipe down condensation from cold surfaces such as windows, window sills and tiled surfaces in the kitchen and bathroom to prevent mould forming.

Increase ventilation to allow the moisture to escape

  • Open windows daily for around 30 minutes, to allow a change of air
  • Move large items of furniture away from external walls and radiators to allow the air to circulate
  • Allow air to circulate in wardrobes by not overfilling them.

Raise the temperature of your home

  • Take extra steps to prevent heat loss by fitting draught excluder to windows and doors, and use underlay under carpets
  • Maintain a consistently warm level of heating throughout your home.

What can I do to remove mould and mildew?

  • Treat and remove mould before it becomes a deep black colour as it will be much harder to remove
  • Wipe down affected areas with a fungicidal (mould killing) wash, carefully following the manufacturer’s instructions
  • Wash or dry-clean mildewed clothes and shampoo mouldy carpets
  • If the mould has been extensive – remove the wall lining and wallpaper, treat the plaster and then paint/paper the area
  • Re-decorate treated areas using a good quality fungicidal paint carefully following the manufacturer’s instructions.

Other types of damp

The three most common kinds of damp in the home are:

  • Condensation
  • Rising damp
  • Penetrating damp.

Rising damp

Rising damp is caused by ground water moving up through a wall. Most walls allow some water in, but it is usually stopped from causing damage by a barrier called a damp-proof course. Rising damp can occur if the damp-proof course in your home is either missing or not working properly, or the level of the ground outside your home is higher than your damp-proof course; allowing water to get above it.

If you have rising damp you may notice damaged skirting boards and floorboards, crumbling or salt stained plaster, and peeling paint and wallpaper. A typical sign of rising damp is the appearance or a tide mark running along the wall.

Penetrating damp

Penetrating damp is caused by water leaking through walls horizontally rather than by water travelling up walls (as is the case with rising damp). This type of damp is usually caused by structural problems such as faulty guttering or roofing.

Penetrating damp often shows up as damp patches on walls, ceilings or floors, which may darken when it rains. You are more likely to get penetrating damp if you live in an older building with solid walls, as cavity walls provide some protection.

If you think you may have rising damp, or penetrating damp in your home, get in touch with us straight away and we will take action to resolve the problem.

For further advice on saving energy, contact the Energy Saving Trust on 0300 123 1234 or visit