How to correct and prevent damp walls, floors or ceilings

There are different kinds of damp, and sometimes you need a surveyor to identify which is which, but to help you make a start, here are some basic pointers.

Penetrating damp happens when there’s a problem with the fabric of the building and although the damp usually moves horizontally from the outside in, patches can also appear on ceilings and floors as well as walls. Missing or loose flashing; missing, rusting or blocked guttering; defective pointing and bricks, and cracked or missing render typically cause penetrating damp.

If the damp is at the bottom of a wall, it’s usually rising damp (water coming up from the ground), in which case the solution is a new damp proof course (DPC), installed by a specialist damp company. Often, they’ll also have to remove the damp plaster and replace it.

Sometimes, the DPC is just being prevented from doing its job. You should be able to see it (providing there is one) along your home’s exterior brickwork.

Perhaps you’ve noticed damp on a chimney breast, or where the chimney breast would have originally been? This could be because the chimney stack needs to be repaired, the chimney pot isn’t capped, or the chimney breast isn’t ventilated properly indoors. Other common causes of damp are problems with the roof. All roofs should be inspected regularly and maintained when necessary, but flat roofs are problematic.