Condensation is the most common type of dampness. It can happen at any time, but is often a problem between September and April.

Condensation, and the mould that appears due to a build-up of condensation, are usually down to the incorrect use of heating and ventilation, but can also be linked with poor insulation.

For information on how to prevent condensation and treat mould, visit CSE and Envirovent.

Rising dampness occurs, particularly in older buildings, when groundwater rises up through walls, floors and masonry.

The brick or stone blocks soak up water from the ground like a sponge. It usually shows as a tide mark on the wall up to a metre in height.

Rising dampness does not normally cause mould, however, it can cause rot in skirting boards.

Penetrating dampness is usually caused by one of the following:

• Porous walls — aging bricks lose the ability to keep out rain penetration.
• Spalled bricks and degraded mortar — damage to brickwork allows water to penetrate.
• Building defects — for example, defective guttering and downpipes, roof damage, dilapidated or poorly installed windows.

Leaking pipes should be repaired straight away. If you are a tenant, let your landlord know immediately.

Condensation advice

Reducing condensation

Damp wall advice

Rising damp advice

Treating rising damp

Penetrating damp advice