Condensation, Damp and Mould

Why does it happen?
The amount of moisture that the air can hold increases as the temperature rises and decreases as it falls.

Just by living we put moisture into the air of our homes. As the temperature of the home rises and falls the amount of moisture the air can hold rises and falls. If it falls a lot, or there is a lot of moisture in the home then at some point it will "condense" on to cold surfaces. These are most often the windows or ceramic toilet cistern, but may also be walls, furniture, clothes etc.

If moisture is condensing on walls, furniture, clothes you may get mould growing in your home.

Over recent years landlords have been tackling fuel poverty and carbon reduction by increasing insulation, installing better doors and double glazed windows. There is no doubt that these help to keep the heat in, but they also keep the moisture in. Unlike years ago, homes now need our help to keep the moisture low.
 
Moisture is measured by "Relative Humidity". If the Relative Humidity is above 60% then you may start getting problems with damp and mould.

Every 1c drop in temperature increases the Relative Humidity by 5% and vice versa. So as your home gets cooler during the night the chance of there being a problem increase. You may remember having ice on the inside of windows in years gone by? There would have been less moisture in the house, but because they had little insulation and single glazing the temperature would drop really low, so the moisture n the air would condense and then freeze. These days you are more likely to have condensation forming on windows and in extreme cases, mould growth.

What can you do?
1 - Reduce the moisture in your home
2 - Don't let your home get too cold

Reduce the moisture in your home
We know that heating fuel is expensive and that some types of system are not very efficient, so first of all try to reduce moisture.

You have two options for reducing moisture, use them both!


1 - Put less moisture into the air
  • Put lids on saucepans
  • Use a microwave rather than hob where you can
  • Keep the kitchen door shut when cooking
  • Don't boil too much water in your kettle
  • Try to dry clothes outside whenever you can
  • If you have a tumble drier, make sure it is vented to the outside
  • Try to avoid drying clothes on radiators
  • The best place to dry clothes is in the bathroom, with the door closed and an extract fan on or window slightly open.
  • Keep the bathroom door closed when bathing or showering, and keep it closed until the steam all goes. Use the fan if you have one, and/or open a window.
  • Don't leave water standing, eg in a kitchen sink or bath
  • Mop up any spillages or condensed water, don't let them evaporate into the air
2 - Get the moisture out of your house
  • Don't close or block the trickle vents in your windows
  • Use your fans and other ventilation products. They don't cost much to run.
  • Open windows for a few seconds in the morning. The damp air will go outside, even when it's raining!

Don't let your home get too cold
Unfortunately the means of getting moisture out of the house is to ventilate, and often you will be sending warm air out with the moisture. This means it is important that you keep kitchen and bathroom doors closed, so that when you ventilate you are minimising the amount of heat that gets away.

How can you stop mould?
Mould only grows if there is enough moisture in the air. Sometimes there may be particular cold spots in your home. Air may get trapped in corners, cooling down and not moving. As it cools it may condense on the wall, after a few hours mould may start to grow. It particularly likes dark places, so may grow more during the night when your house may be colder. 

You need to reduce the moisture in your home, using the tips on the left hand side. Also, don't put furniture right against the wall as this can stop airflow, causing cold spots.