Condensation and mould growth

Is your home damp?

Damp housing encourages the growth of mites, causes mould on ceilings, walls and furniture and can increase the risk of respiratory illness. The following explains how condensation forms and how you can keep it to a minimum, thus reducing the risk of dampness and mould growth. Advice on the treatment of mould is also included.

Is it condensation?

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

• Leaking pipes, wastes or overflows
• rain seeping through the roof where a tile or slate is missing, through walls, spilling from a blocked gutter or penetrating around window or door frames
• rising damp due to a defective or bridged damp-proof course or because there is no damp-proof course.

These causes of damp usually leave a 'tidemark'. New repair and building work can also appear to be damp while it dries out. If you do not think the damp comes from any of these causes, it is probably condensation.

What is condensation?

There is always some moisture in the air, even if you cannot see it. When the air gets colder it cannot hold all of 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 or shower.

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

First steps against condensation

Wipe condensation off windows, doors and sills every morning. Wring out the cloth rather than drying it on a radiator.

Advice on producing less moisture

• Cooking - cover pans when cooking and do not leave kettles boiling
• washing clothes - put washing outdoors to dry if you can or put it in a room with the door closed and the window open or have a fan on. If you have a tumble drier make sure you vent it to the outside (unless it is self-condensing)
• paraffin and portable gas heaters - These heaters put a lot of moisture into the air, you should ensure that you ventilate any rooms that these are used in. If you have a problem with condensation, try to find an alternative means of heating.

Ventilate to remove moisture

• Some ventilation is needed to get rid of moisture being produced, including that from people's breath. Keep a small window slightly open or a trickle ventilator open when someone is in the room
• ventilate unheated rooms such as bedrooms for short periods (of 10 to 15 minutes) each day to remove moist air. On cold or wet days, keeping windows or vents open for long periods when rooms are not used may only make the room colder and the air damper, which may increase condensation
• you need much more ventilation in the kitchen and bathroom when cooking, washing up, bathing and drying clothes. Closing the kitchen and bathroom doors when in use will help stop the 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 air circulating and try to leave a space between furniture and the wall so that air can circulate. Where possible position wardrobes and furniture beside inside walls rather than against outside walls.

Heat your home a little more

• In cold weather, the best way to avoid condensation is to keep low background heating on all day, even when there is no one at home. This is very important in flats and bungalows and other dwellings where the bedrooms are not above a warm living room. So, if possible, install a very small heater with a thermostat in each bedroom which will help control heating and costs
• dehumidifiers will help reduce condensation in warm rooms or dry out new plaster, but are of little use in cold damp rooms.

Treating mould growth

• 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 instruction 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. Note that this paint is not effective if overlaid with ordinary paints or wallpaper.

Further advice on condensation, damp and mould treatment are available from either of our repairs teams.