Damp

What causes damp and how to deal with it.

Penetrating damp, or moisture penetration, is caused by water leaking through walls, rather than rising up through them. This is more common in older properties without cavity walls.

Problems with damp can be a serious concern in any home and it can indicate structural or weatherproofing issues.
 

Causes of damp

Damp is normally caused by problems with external maintenance.

For example:

  • deteriorating structures with ageing mortar joints that have interfered with guttering and drainage systems
  • failed guttering
  • discharging overflows
  • excess moisture from leaking pipes
  • rain seeping in due to damage to the roof or around window frames
  • rising damp in basements or ground floors
  • building or plumbing problems that allow water or moisture into the property
     

Identifying damp

Damp from condensation

Signs of condensation damp are:

  • steamed up windows and walls
  • decay in decoration, like discolouration of window panes
  • the appearance of black mould

Damp patches and mould will usually form behind large furniture, in corners of external bearing walls, or around windows.

Damp from defects

Damp patches and mould will usually form in the area of the defect and beyond, due to water travel. This kind of damp may blister and damage decorative finishes.

Penetrating damp can be identified by moisture penetration on walls inside your house. Walls will be damp to the touch, or there will be discolouration of plaster or decorations. It's more likely to be at a high level on external walls and more noticeable when it rains.

You can spot the signs of damp on walls because they may feel cold. Ceilings with damp will look stained and tarnished.

Advice

Shelter have produced a short video with practical advice on how you can prevent mould and damp in your home.