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Condensation and Mould

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Fact Sheet

What is condensation?condensation

Moisture is always in the air, even when you can't see it. If the air gets colder, it can't hold all the moisture and tiny drops of water appear on cold surfaces. You will have noticed it when you can see your breath on a cold day or if your mirror mists over in the bathroom or when condensation appears on windows.


It occurs normally during cold weather and unlike other forms of dampness, it does not leave a tidemark, but it will leave patches of mould. Look for it in corners, on or near windows, in or behind furniture, cupboards and anything that may be resting or hanging on walls such as pictures. It often forms on walls and/or in unheated spaces.

Why do we get too much moisture in the house?

During our daily routine we can be adding more than 11 litres (20 pints) of moisture into the air of our homes, this comes from:

  • Open fires including gas flame heaters

  • Bathing/showering 

  • Using washing machines, tumble dryers and dishwashers

  • Cooking

  • And breathing!

If this moisture cannot escape it will build up and then find its way to a cold spot in the house. When it comes into contact with a cold surface it will condense (turn to water).
Moisture that is produced in a kitchen or bathroom can circulate around the house and settle in a colder room such as porches or halls. Problems are worse in the winter due to less ventilation and outside surfaces are at their coldest.


Damp can also come from

  • Rising damp* - due to an absent or ineffective damp proof course

  • Damaged roof tiles or slates*

  • Blocked gutters*

  • Leaking waste or overflow pipes*

These causes of damp will often leave a "tidemark" or have a defined edge.


*Remember these matters are structural and the responsibility lies with the Council. Please contact us directly if the damp is stemming from any of these reasons - Contact OneVale on

  • 01446 700 111


How to avoid condensation

There are three main steps that can be used to help reduce condensation in your home:


  • Produce less moisture

    Use lids on pans and do not leave the kettle boiling.

    Avoid using paraffin and portable flueless gas bottle heater as they put excess moisture into the air.
    If you do have to dry washing inside, then dry it in the bathroom with the door closed and the window open or with the extractor fan on.
    Vent tumble dryers to the outside air unless they are the self-condensing type.

  • Ventilate to remove moisture 

    Keep a small window and ventilator open or a fan on when someone is in a room.
    Ventilate kitchens and bathrooms when in use by opening windows wider or use a heat recovery humidity-controlled fan. (They will come on automatically when the air is humid while retaining the heat in the room)
    Close kitchen and bathroom doors, even if there is an extractor fan. This will prevent excess moisture reaching other rooms - particularly unheated rooms, which will be colder and more likely to get condensation.

    A dehumidifier will extract the moisture so if producing excessive amounts is unavoidable, this could be an alternative and will certainly prevent the mould spores from flourishing.

  • Lessen temperature variations between rooms with insulation, draught proofing and heating your home 

    During cold weather, make sure there is some low-level heating on all day, even when the home is not occupied.
    Keep all radiators on, but reduce the temperature using the radiator thermostat in any unoccupied rooms.

    If you are struggling with heating costs, please call our Money Advice Team:

    • 01446 709588 / 146 / 312

Be careful!

  • Do not block permanent ventilatorsDo Not Sign
  • Do not completely block chimneys. Instead leave a hole about two bricks in size and fit a louvered grille over it
  • Do not draught proof rooms where there is a cooker or a fuel burning heater e.g. a gas fire
  • Do not draught proof windows in the kitchen or bathroom

What if I have mould?

Firstly, treat or remove any mould you may have in your home and then deal with the basic problem of condensation. If you can avoid the condensation, mould should not reappear. To kill and remove mould, wipe down the affected surfaces with fungicidal wash which carries a health and safety executive approval number. Follow all the instructions. mould


Disturbing mould by vacuuming carpets and soft furnishings can increase the risk of respiratory problems. You can also buy fungicidal paint to help prevent mould reoccurring on cold surfaces such as north facing walls.


*Remember taking a proactive approach to managing condensation, mould and damp could help prevent long term health conditions*

If you have/or still are experiencing problems with damp in your property after carrying out the above steps, please telephone OneVale on the number below

  • 01446 700 111