Mould And Condensation

What is Condensation?

There is always some moisture in the air, even if you cannot see it. If the air gets colder, it cannot hold all the moisture and tiny drops of water appear. This is condensation. You notice it when you see your breath on a cold day, or when the mirror mists over when you have a bath.

Condensation occurs mainly during cold weather, whether it is raining or dry, it does not leave a ‘tidemark’. It appears on cold surfaces and in places where there is little movement of air.

Look for it in corners, or near windows, in or behind wardrobes and cupboards. It often forms on north-facing walls.

Is It Condensation?

Condensation is not the only cause of damp. It can also come from:

  • Leaking pipes, wastes or overflows
  • Rain seeping through the roof where a tile or slate is missing, spilling from a blocked gutter, penetrating around window frames, or leaking through a cracked pipe causing brown water marks
  • Rising damp due to a defective damp-course or because there is no damp-course. The plaster above the skirting board will look like puff pastry.

These causes of damp often leave a ‘tidemark’.

If your home is newly built it may be damp because the water used during its construction (for example, in plaster) is still drying out.

If your home is damp for any of these reasons it may take weeks of heating and ventilation to dry out. Hiring a dehumidifier will help.

If you do not think the damp comes from any of these causes, then it is probably condensation.

How to Avoid Condensation

These three steps will help you reduce the condensation in your home.

1. Produce Less Moisture

Some ordinary daily activities produce a lot of moisture very quickly.

  • Cover pans and do not leave kettles boiling
  • Avoid using paraffin and portable flueless bottled gas heaters as these heaters put a lot of moisture into the air
  • Use the fastest spin on your washing machine and dry clothes outdoors on a line, or put it in the bathroom with the door closed and the window open or fan on
  • Vent any tumble dryer on the outside, unless it is the self condensing type. DIY kits are available for this
  • If you have been provided with mechanical extract fans, particularly in your bathroom or kitchen, please use the fans while using these rooms. Please keep the fans clean of any dust, dirt etc.

2. Ventilate to Remove Moisture

  • You can ventilate your home without making draughts
  • Keep a small window ajar or a trickle ventilator open when someone is in the room
  • Ventilate kitchens and bathrooms when in use by opening the windows wider. Or better still, use an electric fan. These come on automatically when the air becomes humid, and are cheap to run
  • Close the kitchen and bathroom doors when these rooms are in use, even if your kitchen or bathroom has an extractor fan. A closed door will help prevent moisture reaching other rooms, especially bedrooms, which are often colder and more likely to get condensation
  • Ventilate cupboards and wardrobes. Avoid putting too many things in them as this stops the air circulating. Cut a ventilation slot in the back of each shelf or use slatted shelves. Cut ‘breather’ holes in doors and in the back of wardrobes and leave space between the back of the wardrobe and the wall.
  • Where possible, position wardrobes and furniture against internal walls
  • If you replace your window units at any time, make sure the new frames incorporate trickle ventilators.

3. Some Words of Warning:

  • Do not block permanent ventilators
  • Do not completely block chimneys. Instead, leave a hole about two bricks in size and fit a louvered grille over it
  • Do not draughtproof rooms where there is condensation or mould
  • Do not draughtproof a room where there is a cooker or a fuel burning heater, for example a gas fire
  • Do not draughtproof windows in the bathroom and kitchen.

First Steps Against Mould

  • First, treat any mould you may already have in your home. If you then deal with the basic problem of condensation 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 ‘approval number’. Follow the manufacturer’s instructions precisely. Dry-clean mildewed clothes and shampoo carpets. Disturbing mould by brushing or vacuum cleaning can increase the risk of respiratory problems
  • After treatment, redecorate using a good quality fungicidal paint to help prevent mould recurring. Note that this paint is not effective if overlaid with ordinary paints or wallpaper. The only lasting way of avoiding severe mould is to eliminate the moisture.


Estuary Housing Association

  • We will ensure your property has appropriate ventilation to help control condensation
  • We will safely clean and clear any mould growth affecting your property.

The Resident

  • You are responsible for all redecoration works once we have cleared away any mould growth
  • You are responsible for any goods, clothing, materials etc, affected by mould growth and should take out any appropriate insurance cover available to cover any loss in this area
  • If you have a mechanical extractor fan, and it is not working, please report this to repairs on 0808 169 1969 as soon as possible.

This information is available for you to download and print  Mould and Condensation Printable.pdf [pdf] 136KB