Damp and mould

Condensation is the most common cause of dampness and most homes will be affected by it at some point.

It is caused by water vapour or moisture from inside the property coming into contact with colder surfaces, such as windows or walls. The resultant water drops (condensation) may then soak into the wallpaper or paintwork or even plasterwork. In time, the affected damp areas attract black mould that grows on its surface.

Condensation is usually found in the corners of rooms, north facing walls and on or near windows. It is also found in areas of little air circulation such as behind wardrobes and beds, especially when they are pushed up against external walls.

Cooking, washing and drying clothes indoors all produce water vapour.

The ‘amount’ of condensation in a home depends upon different factors, including:

1. How much water vapour is produced by the actions of the household
2. How cold or warm the property is
3. How much air circulation (ventilation) there is.

Turning up the heating alone will not sort out the problem. All three factors should be looked at to reduce the problem.

Black mould

Mould spores are invisible to the human eye and are always present in the atmosphere both inside and outside dwellings. They only become noticeable when they land on a surface upon which they can grow and then multiply.

By dealing with the causes of condensation you will automatically deal with the problem of mould.

How to reduce condensation

Produce less moisture

• Keep the kitchen door shut and leave the windows open and/or extractor fan on when cooking
• Cover pans when cooking and do not leave kettles boiling
• Ensure washing is hung outside when possible. Avoid drying it on radiators. If you need to dry clothes indoors, open the window and close the door of the room where the clothes are drying so the moisture can escape outside rather than circulate around your home
• Ensure your home is not overcrowded. More people and pets living in your home means there will be more moisture produced.

Remove excess moisture

• Wipe dry the windows and window sills of your home every morning to remove condensation. This is especially important in the bedroom, bathroom and kitchen - just opening the window is not enough
• Open the bathroom window and/or keep the extractor fan on when taking a shower or bath
• Keep the window trickle vents open. They are designed to ventilate your accommodation without causing draughts
• Open the bedroom windows (for up to 20 minutes) in the morning and throw back the sheets or duvet to air the bed and bedding. A window slightly open is as good as one fully open. Remember to close your windows for security when you go out.

Heat your home

• Having a medium-to-low level of heat throughout the house by keeping the heating on at low all day in cold weather will help to control condensation. Heating one room to a high level and leaving other rooms cold makes condensation worse in the unheated rooms. It will cost more initially to warm the walls, but once the walls are dry, your heating bills will reduce
• Do not put your heating on for short periods of time (one hour or less) – this will make the problem worse. The air will absorb moisture quicker than the walls can warm up
• When the heating is turned off, the air will cool quickly and condensation will be formed, cooling the walls further
• Try to keep your home properly heated. It usually helps to have a low background temperature of at least 15 degrees in all rooms.

Remove mould growth

• Mould growth should be removed as soon as you see it
• Where there is mould, wipe down or spray walls and window frames with a fungicidal wash that carries a HSE ‘approval number’ or a weak water and bleach solution
• Do not remove mould by using a brush or vacuum cleaner as this may disturb the mould spores and can increase the risk of breathing problems
• After treatment, redecorate using a fungicidal paint or wall paper paste – do not paint over using an ordinary paint.

Ventilate your home

• Make sure you are ‘cross-ventilating’ your home – opening a small window downstairs and a small one upstairs (they should ideally be on opposite sides of the house or diagonally opposite if you live in a flat). At the same time, open the interior room doors, this will allow drier air to circulate throughout your home. This cross-ventilation should be carried out for about 30 minutes each day
• Ventilate your kitchen and bathroom for about 20 minutes after use by opening a small top window. Use an extractor fan if possible
• Keep a small gap between large pieces of furniture and the walls, and where possible place wardrobes and furniture against internal walls
• Where possible, remove or replace bulky furniture in your home to allow air to flow through rooms and near walls
• Do not over-ventilate your accommodation by leaving the windows open as your walls will lose all the heat stored in them. Only open the windows for a short period at a time so that any moisture is able to escape. Then close your windows, leaving a small gap of about 5mm (quarter of an inch). It is advised to open the window slightly anytime that condensation is forming on the glass.

Dealing with condensation is not easy. Only carrying out one or two of the above steps may not solve your problem. You need to do as many as possible every day, so that it becomes part of your habits and lifestyle.