Avoiding condensation

Guidance for tenants and residents

Condensation is the most common form of unwanted dampness in buildings and occurs when warm moist air comes into contact with a cold surface.

In just one day, the average family makes about 15 pints of water vapour.

This vapour stays in the air in warm rooms but turns back into water when it touches cold surfaces such as a wall, window or ceiling.

The four main causes of condensation are:

  • Lack of heat

  • Lack of insulation

  • Lack of ventilation

  • Moisture production

Problems caused by condensation

The most common indication of a condensation problem is water running down windows and walls. If ignored this can lead to water collecting on the window sills, decay in window frames, stained curtains and black mould growing on walls and woodwork.

How to prevent condensation

If you find water on the inside of your windows, on cold walls and surfaces, in cold rooms or near windows it is likely to be condensation. You may also find black mould on the walls or blue/green mould on leather or wood. Mould is usually found in cold corners, cupboards or on external walls inside the property. In most cases condensation can be prevented by opening a window and making sure that all rooms within the home are heated adequately.


  • Keep your property well ventilated - especially when washing and drying clothes. If you have a tumble dryer, make sure the vent pipe runs outside or out a window

  • Open the kitchen window, close internal doors and use lids on boiling pans when cooking. Use an extractor fan if you have one

  • Keep bathroom windows open and the door shut when taking a bath or shower, and for a short time afterwards. Run a little cold water into the bath or basin before the hot water is turned on to reduce the amount of steam produced

  • Provide continuous slight ventilation by keeping window vents open at all times

  • Make sure that your roof space is properly ventilated.

  • Stop warm air hitting the windows by hanging heavy close fitting curtains

  • Put wardrobes and furniture against inside/internal walls. If you put them against outside walls, make sure there is a small gap between the wall and furniture for the air to circulate

  • Improve the insulation of your home


  • Dry clothes on radiators, portable bottled gas or paraffin heaters

  • Block up a fire place without fitting an air vent to the chimney flue

  • Ignore any leaks - they'll only get worse and cost more to repair

  • Put too many clothes in a wardrobe as this stops the air from circulating

  • Do not use unventilated airing cupboards for clothes - drying this way will encourage moisture build up

Please use the 'contact us' box if you have any questions. For more information, see 'related pages', 'downloads' or 'other useful websites'.

Stay in touch

Follow us on Twitter and Facebook and receive instant updates on our winter services and any disruptions caused by bad weather.

You can also sign up to email alerts and stay in touch with the latest Winter Services news.

Email alerts This link opens in a new browser windowFacebook This link opens in a new browser window Twitter This link opens in a new browser window

A to Z of services