Condensation

Condensation, Damp & Mould Growth Advice 

Rentokil does not offer treatment methods for condensation problems, however understanding how condensation occurs may help you control the problem at minimum cost.

Why are you getting condensation and mould growth?

There is no magic solution to condensation, it occurs in older properties due to the design of the property and largely how the occupants live.

Air can only hold a certain amount of water vapour – the warmer it is the more it can hold. If there is little movement of air and if the water vapours are cooled by contact with a cold surface such as a mirror, a window or even a wall, the water vapour will turn into droplets of water-condensation. So, the warmer you keep your home the less likely you are to get condensation.

Condensation occurs in cold weather, even when the weather is dry. It doesn’t always leave a ’tidemark’ round its edges on walls.

If there is a ’tidemark’, this dampness might have another cause, such as water leaking into your home from penetrating damp, rising damp, a plumbing fault or loose roof tiles.

Look for condensation in your home. It can appear on or near windows, in corners and, in or behind wardrobes and cupboards.

When is condensation a problem?

Every home gets condensation at some time – usually when lots of moisture and steam are being produced, for instance at shower or bath-times, when a main meal is being cooked or when clothes are being washed. It is quite normal to find your bedroom windows misted up in the morning after a cold night. There is nothing much you can do to stop this. But if your home never seems to be free from condensation and you have mould or mildew on leather and clothes then you need to try and control these effects.

For mould growth to occur there needs to be a sufficient amount of water available, this is why mould growth often occurs with condensation or damp. This type of mould looks like 'black spots' and is typically found along skirting edges or corners of walls & ceiling edges.

How to tackle condensation problems

The first thing to do is remove the visual effects of the black spot mould by shampooing carpets, and dry cleaning of clothes etc.

Where walls & paint work are concerned a fungicidal wash should be used to clean down the walls & paintwork. The fungicidal wash can be obtained from major DIY outlets and it is stressed that the manufacturer’s instructions should be followed precisely. 

Any repainting should be carried out using a good quality fungicidal paint.

However the only permanent way to avoid severe mould is to eliminate the dampness.

How to avoid condensation

The following steps will help reduce the moisture vapour created in your home.

• Extractor fans: Have extractor fans fitted in the kitchen and bathroom to remove moist air before it spreads to other areas of the house, ideally these fans should be humidistat controlled so they switch on automatically when the air becomes humid, it is advisable to keep these doors closed when the rooms are in use.
• In the kitchen when cooking make sure any pans are covered and kettles are not left boiling.
• Fit double or secondary windows to reduce cold surfaces for moisture to condense on.
• Avoid drying clothes on radiators or in front of fires.
• Carry out draft proofing of windows & doors.
• Insulate the roof void and cavity wall to ensure as much heat is retained within the property.
• Try to maintain a constant temperature by having background heating on all day this will help avoid condensation occurring.

If the above measures do not resolve the condensation problems, further benefit could be achieved by the following measures. However, they can be expensive and you need to be convinced that it will be suitable for your property.

• Use of de-humidifiers which is a control measure these only reduce moisture when the de humidifier is switched on.
• Forced ventilation systems do work but all doors in all the rooms need to be kept open to achieve full benefit.
• Line walls with insulation plasterboard to increase surface temperature of walls.