Condensation and Damp

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, on 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.
• Rising damp due to a defective damp-course or because there is no damp-course. Rising damp only appears in ground floor rooms, and only to a maximum of 1m up a wall.

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 in the worst cases.

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.

(a) 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 bottled gas heaters as these heaters put a lot of moisture in the air.
• Dry washing outdoors on a line, or put it in the bathroom with the door closed and the window open or fan on.
• Tumble dryers must be vented to the outside air.

(b) 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 a humidity-controlled 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. This 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 that the new frames incorporate trickle ventilators.

(c) Insulate, Draughtproof and Heat Your Home

• Insulation and draughtproofing will help keep your home warm and will also cut fuel bills. When the whole home is warmer, condensation is less likely.
• Insulate your loft. Remember to draughtproof the loft hatch but do not block any ventilation under the eaves.
• Consider cavity wall insulation. Before deciding though, you should talk to your local Building Inspector as Building Regulations approval is required.
• Consider secondary and double glazing of windows to reduce heat loss and draughts but you must ensure that there is some ventilation.
• In cold weather, keep low background heating on all day, even when there is no one at home.

Some Don't Do's:

• Do not block permanent ventilators.
• Do not completely block up chimneys. Instead, leave a hole about two bricks in size and fit a louvered grille over it (this work should be done by a builder or specialist).
• Do not draught-proof rooms where there is condensation or mould.
• Do not draught-proof 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 dampness.

Useful Information

If you are a householder who receives a qualifying income or disability related benefits, or are aged 60 or over, you may be eligible for a grant for the installation of a major insulation measure such as draught-proofing, loft insulation, or cavity wall insulation, under the Home Energy Efficiency Scheme.

For information on grants under the Home Energy Efficiency Scheme, contact EAGA Limited, Freepost, PO Box 130, Newcastle upon Tyne NE99 2RP (Free phone 0800 181 667).

You can also obtain information and advice on insulation, heating, condensation and damp from the Northumbria Energy Advice Centre who can be contacted on Freephone 0800 512 012.

RNID Typetalk service prefix number 18001