Tips for Dealing with Damp and Condensation

This can ruin decorations, destroy floor coverings, damage walls and plaster, and cause woodwork to rot, so it is important not only to treat the symptoms, but also to track down the causes. These could vary from rain coming in through the roof or walls, condensation, moisture being absorbed through the ground or a mixture of these.

Penetrating damp
This is caused by moisture getting in from the outside, often because of wear and tear to the structure of your home, but it may also affect solid walls that are subjected to strong driving rain. The first sign of penetrating damp appears after a heavy downpour and can occur almost anywhere, although it may be some distance from the actual leak; mould often forms directly behind where the problem lies.

Causes of penetrating damp
– Damp on ceilings upstairs may be caused by broken or loose roof tiles, or damaged copings.
– Damp on a ceiling spreading from a chimney breast (fireplace projection) or rooflight, under the junction of two pitched roofs, or in corners that adjoin a single-storey extension, is usually caused by flashing that has parted company with masonry, or cracked and crumbling mortar fillets.
– When damp patches are high up on an upstairs wall, look for blocked, defective gutters or downpipes and a build-up of leaves.
– With widespread damp on a wall, look for cracked or porous bricks.
– Isolated damp patches on walls are caused by crumbling pointing and cracked or blown patches of render (large damp patches), or mortar-encrusted wall ties (small spots).
– Rotten woodwork and damp patches around door and window frames are caused by gaps between masonry and frames, missing weatherboard or a drip groove encrusted with paint or moss.

Condensation
When warm, moist air reaches a cold surface, such as a wall exposed to icy winter winds or ceramic tiles, the result is condensation. It is most likely to occur in bathrooms and kitchens where the main activities are bathing, washing and cooking. Controlling condensation requires a fine balance between good ventilation and adequate heating, but while the modern home is warm, it is also well insulated and draughtproofed, so the level of ventilation is often poor. The key to success is to provide sufficient ventilation, without allowing expensive heat to escape.

Is it damp or condensation?
If you are not sure if a moisture problem is due to condensation or damp, lay a piece of aluminium foil over the patch, seal the edges with adhesive tape and leave it for 48 hours. Condensation will cause beads of moisture to appear on the surface of the foil; penetrating or rising damp will produce beads of moisture underneath the foil.