Causes of Damp

Leaks

Light brown damp patch on ceiling caused by a leak A current or previous plumbing leak can affect internal walls, ceilings  and flooring. If you think you have a leak, check around the water and waste pipes inside your home, and the seals around the bath, shower and sinks. Externally you should check to see if the guttering is leaking or blocked or if any roof tiles are missing or dislodged.

 

Penetrating Damp  

Penetrating damp shown on wall next to window

This is where water is passing through a building defect and will appear as an obvious damp patch, particularly after rainfall. Examples of penetrating damp can be a leaking roof, cracked wall, missing pointing/render, leaking external gutters or external pipes, leaking drainage pipe and rotten windows or door.

 

 

Rising Damp  

Rising damp example shown on lower half of wall with crumbling plaster work

This is more common in older properties. It generally affects the lower part of the ground floor up to the height of about 1 meter. The main cause of rising damp is where the ground water rises through capillaries in masonry to saturate the wall, mainly due to a failed damp proof course or where the damp proof course has been breached, or the cavity is blocked. 

The signs to look out for usually are a damp tide mark low down on the ground floor and hygroscopic salts showing on the wall and damaged timber on skirting boards. Black mould rarely appears on these types of dampness because the area is usually too wet and the water contains salt picked up when passing through the surface, which prevents growth.