What is Rising Damp?
Rising Damp is usually easy to recognise, its given the name because its caused when moisture from the ground spreads into the brick work and rises through the fine cracks in the masonry, this process is referred to as capillary action. All houses built in the last 130 years should have been constructed with a damp proof course (DPC) which is a physical barrier inserted into the fabric of a building to stop water passing from one place to another. Rising damp can affect any property if the DPC is ‘bridged’ this is when something is providing a route for the moisture to get past or above the DPC – for example when a raised flowerbed, patio or path is built against the house above the damp course.
Symptoms
Rising damp will almost always mean damp patches and stains up to about 1 meter up the wall. In should not go higher, once this height is reached, the weight of water usually becomes too much for the capillary action to be able to draw it any higher. Only in extreme cases where it has been allowed to go unchecked for an extended period of time will it have spread higher up. Look at the exposed surface of the brick. Check to see if there are salts forming, that the brick is actually wet (not just the wallpaper or paint), that there is no mold present and whether the skirting board is showing any signs of rot.
Treatment
The correct procedure for dealing with a broken DPC is to have either a new section fitted in the area or, to have a chemical injected into the wall to make that section impervious. Both these jobs are normally carried out by specialists who should also be able to provide a guarantee on the work.The common treatment is to install a
damp proofing course. This generally involves removing the sodden skirting board and plaster to about a meter to expose the brick. Holes are then drilled and a silicone-based chemical injected into the brickwork. The chemical seeps through the brick and the mortar to form a new impervious barrier. Once complete and dry the wall is re-plastered with sand and cement containing a powerful waterproof additive.
If an external feature like a flowerbed or patio is to blame, the dampness can be cured by lowering it below the level of the original damp course and then allowing the area to dry out naturally by opening windows, aerating and heating the room.
