Just breathing produces half a pint of water an hour! When you factor in cooking, cleaning, and worst of all, drying clothes, the water that we produce every day saturates the air. Keep your property well ventilated by opening your windows / drip vents on a daily basis to allow moist air to escape. In cold weather there has to be a compromise between removing moist air and allowing heat to escape.
If using the kitchen or bathroom, keep the door closed when possible so that moist air is contained within the room. Open windows or use an extractor fan if one is installed to let the excess moisture out. Leave the extractor fan on for longer than you are cooking or bathing because there will be excess moisture in the air that you cannot see.
Try to keep at least a small gap between walls and furniture, particularly against ‘cold walls’, and allow ventilation of any cupboards to keep air flowing. If air lingers in these spaces it will condense onto walls and could eventually form into black mold.
If drying clothes, it is always better to do it outside. If this is not possible, put them in an enclosed room with plenty of ventilation and keep the window open. If using a tumble dryer, make sure the vent pipe runs outside your property or out of a window.
While cooking, try to cover all pots and pans and avoid leaving anything on the boil for too long. If the lids are off, moisture will be rising from the pans even if you cannot see it. Use ventilation such as cooker hoods where possible.
Check to make sure airways such as chimneys and air bricks are not blocked. Air ventilation is extremely important, you don’t want trapped moist air in one part of your home because it will condense on your walls.
Cold air causes warm air to release moisture, so keeping heating levels within a room or property at a constant temperature, especially in winter, means condensation is less likely to form. If your house is empty during the day this is not as much of an issue because people are not adding moisture to the air by breathing, cooking, etc.
For very moist areas, consider investing in a dehumidifier. These devices draw the moisture out of the air, stopping it forming on the windows. They can be expensive to buy, but you can hire them over the winter months and just leave your windows open in the summer. Be aware a dehumidifier may cost a lot to run – an average unit (330W) can cost around 4.7p per hour – at 4 hours per day for 3 months that would cost £17 equivalent to 56kg CO₂.
Check your roof to see if there are any problems such as holes or gaps between the tiles that would allow water to leak in.
Check the guttering and down pipes to make sure they are carrying the water away. At the same time check for damaged/blocked gutters or drainpipes which can cause the external wall to become wet.
Condensation forms in the attic if moist air from your house comes into contact with the underside of cold roof tiles or the side of your water tank. To stop the warm moist air contacting the cold surfaces in your attic make sure, (a) all cracks are sealed, (b) there are no gaps where wires and services go through the ceiling, (c) your roof hatch is well sealed.
Insulate your roof in 1 of 2 ways. Cold roof insulation is laid on the floor of your attic between the joists. It stops the heat from the rooms of your house escaping into the roof space. Warm roof insulation leaves the attic space warm. The insulation is laid between the rafters (against the underside of the roof cover) and should significantly reduce condensation.
Wipe down surfaces when moisture settles to prevent mold forming.
Try not to use bottled gas or paraffin heaters – these produce a lot of moisture and may be a health and safety risk.
Window coverings can increase condensation by trapping the moisture against the window. Make sure blinds and curtains allow airflow.
Cover fish tanks and remember that house pets and plants produce moisture as well.