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What is Condensation?

Condensation is a physical process that occurs when there is a build-up of moisture in the air. Condensation is caused when moisture held in warm air meets a cold surface like a window or wall and condenses into water droplets.

If this is allowed to happen regularly, mould may start to grow on cold ceilings, outside walls, around windows and in the places where air doesn’t circulate well.

Where does the water come from?

There are 3 mains factors which contribute to condensation inside the home:

  1. Humidity of the air
  2. Low temperature
  3. Poor ventilation

Everything that breathes and perspires puts moisture into the air. You notice it when you see your breath on a cold day, or when the mirror mists over when you have a shower or bath.

An adult breathes out about 1 pint of water each day. Bathing and personal washing produces about 2 pints of water a day. Boiling water when cooking and drying clothes inside puts much more water into the air.

Drying clothes, cooking, bathing and personal washing all put much more water in the air.

Does condensation leave a ‘tide mark’?

No, condensation does not leave a ‘tide mark’. If there is a 'tidemark', this dampness might have another cause, such as water leaking into your home from a plumbing fault, loose roof tiles or rising damp. If you discover this, please report this to our Customer Service Centre as soon as possible on the contact details below.

How do I control condensation?

You can control condensation, by reducing the amount of moisture created in your home by following the steps:

  • Wipe down the surfaces affected by condensation regularly.
  • Wipe down windows to remove condensation from the pane.
  • Dry washing outside if possible. Otherwise, hang it up in the bathroom, close the door and have the window open or a fan working continuously while it dries.
  • When cooking/boiling water put lids on saucepans.
  • While cooking, bathing or washing, use an extractor fan or open a window and keep the door closed. Keep the extractor fan on or the window open for about 20 minutes after you have finished (with the door closed).
  • Leave trickle vents (vents in the window frames) open when rooms are occupied - even in the winter when your heating is on.
  • During cold weather, use the heating programmer to set up the on/off times for the heating. The temperature can be set a few degrees lower while you are out and turned up when you return home.
  • Move wardrobes and furniture at least 100mm away from external walls to allow the air to circulate.
  • Avoid using paraffin or bottled-gas heaters that do not have an exhaust pipe to the outside. Burning paraffin or gas produces large amounts of moisture. (these are not permitted in council properties).
  • If you use a vented tumble drier, make sure it is properly vented through an external wall.
  • Do not block permanent ventilators.
  • Do not draft proof any rooms that have existing condensation problems.
  • Do not draft proof rooms where there is a fuel-burning heater (gas fire) or cooker.
  • Do not draft proof windows in the bathroom and kitchen.

Why do I have mould in my home?

Mould is a natural organic compound that develops in damp atmospheres. In housing terms, mould is often a consequence of water penetration and/or condensation in properties that are not adequately heated and/or ventilated.

Can the mould affect my health?

Yes, if you have damp and mould in your home, you are more likely to have respiratory problems, respiratory infections, allergies or asthma. Damp and mould can also affect the immune system.

Who can be affected?

Some people are more sensitive than others, including:

  • Babies and children
  • Elderly people
  • Those with existing skin problems, such as eczema
  • Those with respiratory problems, such as allergies and asthma
  • Those with a weakened immune system

These people should stay away from damp and mould.

How does it affect your health?

Mould growth can produce allergens (substances that can cause an allergic reaction), irritants and, sometimes, toxic substances.

Inhaling or touching mould spores may cause an allergic reaction, such as sneezing, a runny nose, red eyes and skin rash and can also cause asthma attacks.

For more information about how damp and mould can affect your health visit the NHS website.

How can I prevent mould growth?

Preventing or reducing the build-up of moisture is the main way to limit the growth of mould.

No Water = No Mould

There are 3 main actions to combat mould are:

  1. Detect the source of the moisture problem
  2. Remove the mould; and
  3. Taking action to control the moisture and condensation

How can I treat the mould?

You can take the following steps to manage the mould:

  • Check for mould weekly. Clean any signs of mould as soon as you see them.
  • Mould can easily be removed if found early by washing surfaces with a Health and Safety Executive approved fungicidal wash making sure you follow the manufacturer’s instructions.
  • Keep checking the affected area for at least a week. If the mould reappears, wash it down again with the fungicidal wash to make sure the area is thoroughly sterilised.
  • To redecorate after mould treatment, use a good quality fungicidal paint to help prevent mould reoccurring or use a paint additive.
  • Dry clean any clothes and shampoo any carpets that have been affected.
  • Follow the advice above to control condensation.
  • Do not use washing up liquid or bleach as a source to clean mould.
  • Do not try to remove mould by using a brush or vacuum as this may help mould growth spread.

I have tried all these steps but I still have damp, condensation or mould. Who do I contact?

Please contact us by email:

We will ask you what you have done to eliminate the issue in your home and may send a surveyor to visit you at home. If we think the cause of the problem is down to lifestyle we will consult with you and identify ways that may help resolve the problem. In many cases, we will ask you to revisit the steps above.

Other useful contacts

  • Environmental Health Department 01438 242916 or 01438 242908
  • Energy Savings Trust 0300 123 1234 Monday to Friday, 9am to 8pm.
    (Calls cost no more than a national rate call)