Condensation, damp and mould

Condensation usually occurs when lots of moisture or steam is produced or when there are changes in air temperature. If this air is cooled by contact with a cold surface such as a mirror, window or even a wall, the water vapour turns into droplets of water. 

Causes of condensation

It often appears during cold weather and appears on cold surfaces and in areas of the home where there is little movement of air. Everyday life can also cause condensation. The rooms where you need most ventilation are usually kitchens and bathrooms. You may also find it in corners and in or behind wardrobes and cupboards. It can also be found on north facing walls. 

Stop condensation

You get less condensation if you try to keep your home warm most of the time. Whenever possible open a window while cooking, running hot water or drying clothes. There are four steps you can follow to help stop condensation. 

Step one - produce less moisture

Ordinary daily activities can produce a lot of moisture very quickly. So when you are cooking -

  • put lids on pans
  • do not leave kettles boiling
  • open windows 

When you are drying your clothes, wherever possible try to dry them outside. If you have to dry inside -

  • try to avoid drying clothes on radiators. If you do, open windows slightly to give some ventilation
  • make sure your tumble dryer is always ventilated to the outside unless it is the condensing type

Step two - ventilate to remove moisture

Keep a small window or trickle vent (fitted in the window frame) open when the room is in use.

You need much more ventilation in the kitchen and bathroom when cooking, washing up, bathing and drying clothes. You should open windows wider or use a humidistat controlled electric fan (these come on automatically when the air becomes humid and are cheap to run).

Stop damp air from spreading by keeping kitchen and bathroom doors closed when the room is in use.

Ventilate cupboards and wardrobes and try not to put too many things in them. Where possible put them on internal walls rather than against outside walls.

When you have curtains or blinds drawn, it makes the surface of the window colder and this increases condensation. Try to open curtains or blinds for at least four or five hours each day. 

Step three - keep your home warm

Wherever possible try to heat your home using gas central or electric storage heaters. Do not use paraffin or portable gas heaters as these put a lot of moisture into the air. You can add draught proofing but remember  do not -

  • block permanent vents
  • draught proof rooms where there is condensation or mould.
  • draught proof where there is a cooker or a fuel burning heater, for example, a gas fire

Step four - treatment for mould growth

If you already have mould growth in your home, it must be treated. If you deal with the basic problem, mould should not reappear.
To kill and remove mould, wipe down walls and window frames with a fungicidal wash which carries a Health and Safety Executive approved number. Follow the manufacturer's instructions precisely. Dry-clean mildewed clothes and shampoo carpets.


After treatment

Redecorate using a good quality fungicidal paint to help stop mould coming back. You should be aware that this paint is not effective if covered with ordinary paints or wallpaper.