Damp and mould is often the result of water vapour condensation on cold surfaces. This type of mould looks like “black spots” and is typically found in corners, behind furniture, along skirting boards or ceiling edges.
Heat:
Heating one room to a high level and leaving other rooms cold makes condensation worse in the unheated rooms. Try to leave some background heat on throughout the day in cold weather. Most dwellings take quite a long time to warm up, and it may cost you more if you try to heat your home up quickly in the evening. If you don't have heating in every room, you could keep the doors of unheated rooms open to allow some heat into them.
To add extra heat to rooms without any form of fixed heating, it is better to use electric heaters, for example oil-filled radiators or panel heaters, on a low setting. Try not to use portable bottled gas heaters in homes suffering with condensation as they give out a lot of moisture whilst in use.
Ventilate:
Ventilation is essential. Help to reduce condensation that has built up overnight by keeping a small window open where possible and opening any trickle vents on windows upstairs and downstairs. They should 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.
Ventilate your bedroom by leaving a window slightly open at night, or use trickle ventilators if fitted.
Allow air to circulate around stored clothes. Keep a small gap between large pieces of furniture and the walls, and where possible place wardrobes and furniture next to internal walls instead of external ones. Pull shelves away from the backs of wardrobes and cupboards and try not to overfill wardrobes and cupboards as it restricts air circulation.
If you have an extractor fan use it when cooking or having a bath/shower to stop the windows getting steamed up and keep it running for a while after you have finished.
Reduce water vapour in your home:
Drying clothes indoors, particularly on radiators, can increase condensation unless you open a window to allow air to circulate. Up to 9 pints of excess water can be produced by drying your clothes inside. Hang your washing outside to dry if at all possible, or hang it in the bathroom with the door closed and a window slightly open or extractor fan on. If you have a tumble dryer which is not vented to the outside you will need to allow more ventilation when you use it.
Always cook with pan lids on, and turn the heat down once the water has boiled. Only use the minimum amount of water for cooking vegetables.
Remove existing mould:
Existing mould can be removed by wiping down walls and window frames with a fungicidal wash that carries a Health and Safety Executive (HSE) approval or by using a diluted bleach solution. These are often available at local supermarkets or DIY shops. Always follow manufacturers’ guidelines.
Remember: The most important action is to improve ventilation and maintain low level background heating