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While condensation can have horrid consequences if left untreated, this build-up of moisture is possibly the easiest damp problem to fix – especially if tackled at first sight. The solution to this problem is -more often than not- quick and easy, however, if both landlords and tenants work together to cover all bases before the problem arises, it can almost always be prevented from occurring all together.

Why does condensation occur?

Condensation occurs when warm moist air meets a cold surface, therefore the risk of condensation depends upon how moist the air is and how cold the surfaces are within a property – and both of these factors depend, to some extent, on how a building is used. Condensation occurs most in winter, when a building’s structure is cold and when windows are opened less, as moist air cannot escape. Nevertheless, this does not mean that condensation cannot appear in warmer months too.

Where does condensation occur?

Condensation occurs often for short periods of time in bathrooms and kitchens as a result of a steamy atmosphere as well as for longer periods in unheated bedrooms. It can also be found in cupboards or corners of rooms where ventilation and movement of air are restricted. Besides condensation on visible surfaces, damage can also occur to materials which are out of sight, for example from condensation in roofs.

How to stop condensation

To stop condensation on windows, as well as other surfaces, two particularly important steps should be followed:

  1. Provide ventilation to rooms and prevent moist air spreading to additional areas.
  2. Use the heating reasonably.

Ventilation and preventing moisture spreading

Good ventilation in a property, especially in kitchens and bathrooms, is essential. If your rented property has an electric extractor fan present, ensure your tenants use it when cooking or washing clothes, and particularly whenever the windows show any sign of misting. Tenants should leave the fan on until the misting has cleared. If there is not an extractor fan, landlords should advise tenants to open kitchen windows but keep all doors closed as much as possible. This will ensure moist air does not spread to other rooms where it may cause trouble.

After bathing bathroom windows should also be opened and bathroom doors are shut for long enough to dry off the room. If washing is hung up to dry, for example in a bathroom or kitchen, it is also advisable to open a window or turn on an extractor fan to ventilate the room. 

It is not only kitchens and bathrooms that need ventilation. In old houses a lot of ventilation occurs through fireplace flues and draughty windows meaning most other rooms will be okay, however in modern properties sufficient ventilation does not occur unless a window or ventilator is open for a reasonable time each day, as well as for nearly all the time a room is in use. Too much ventilation in cold weather can be uncomfortable for tenants and can waste heat, however, all that is needed is a very slightly opened window or ventilator – a 10mm opening will usually be sufficient.

Heating rooms to avoid condensation

To prevent condensation, try to make sure that all rooms are at least partially heated continually through cold months. Providing heating should be a priority whether are tenants in the property or not, and tenants should be advised that it is best to keep heating on, even if at a low level, even if they are out. Houses and flats left unoccupied and unheated during the day get very cold. The heat provided has to keep room surfaces reasonably warm; it takes a long time for a cold building structure to warm up, so it is also better to have a small amount of heat over a long period of time than to provide a lot of heat for just a short time.

Mould growth

Any sign of mould growth is an indication of the presence of moisture and if caused by condensation gives warning that heating, structural insulation or ventilation or all three, may require improvement. Tenants should make their landlord aware of any mould within their property as soon as it has been spotted so that an investigation into the cause of the issue can be carried out.