How do I… find the source of the damp?

There are 3 key types of damp: condensing, rising and penetrating. Here are our tips for working out which is affecting your house, and how to deal with the problem.

If you are getting close to damp and mouldy conditions you should wear a face mask. Click here for information on choosing a face mask.

Condensing damp: Condensing damp is a particular problem in badly ventilated rooms, such as kitchens and bathrooms. Look out for signs such as steamed up windows, peeling wallpaper, black spotty mildew and water running down the walls. Condensing damp can also be found in less obvious places, such as blocked in fireplaces without vents and underneath laminated flooring with no air circulation. To solve this problem you need to increase the ventilation and ensure the area is properly heated. Opening windows to improve air circulation and fitting vents and extractor fans will help – in severe cases a dehumidifier might also be a good idea. Avoid non-porous paints and wall coverings as these will prevent air from circulating.

Rising damp: This is less obvious to spot as most of the evidence is below floor level. Often the smell is an indicator before you can see the damp, but in bad cases you can see patches above the skirting boards. If left unchecked the damp can cause damage to brick, concrete and wood, and can lead to wet and dry rot. You may need to have a chemical damp-proof course injected into the walls of your building to prevent the damp from rising any further. This is subject to regulations and should only be carried out by a reputable company who can provide you with the guarantee needed for selling your house or making an insurance claim.

Penetrating damp: This can be identified by damp patches on the wall, wet and crumbly plaster, mould/mildew on the walls, or even wet surfaces. Causes can include external damage, such as tiles missing, leaking downpipes, damaged pebbledash and ill-fitting windows and doors. On the ground level it can be a result of the ground outside being higher than the damp proof course designed to prevent water leaking through the walls, or blocking the air flow bricks designed to allow ventilation. Make sure your house is well maintained and any damage is quickly fixed. Check roofs regularly by looking for any signs of water leaking in. Keep areas around damp-proof courses and air bricks clear. In naturally damp, cool places such as basements, leave a heater constantly on a low heat to reduce moisture.

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