What Causes Rising Damp ?
Leodis Damp Control
Damp proof courses (DPC) can fail for several reasons and here we will look at some of the most common problems.
As explained in the previous section Rising Damp is caused by moisture rising up through the masonry by a process called ‘capillary action’ Usually we have a physical barrier made up of a waterproof material inserted on both internal and external skins of brick, at least 6 inches above outside ground levels, over time however these can deteriorate due to natural erosion of the material first used. This can allow moisture to get through the inadequate DPC continuing its upwards journey seeking a means of evaporation, resulting in damp patches on your internal plaster work.
You may be experiencing rising damp even if your damp proof course is functioning well, in this case you may have a breached DPC. Breached DPC is a term used when something is allowing moisture to bypass your damp proof course. For example, plant pots lent against your external wall can act as a bridge, raised timber decking can allow moisture to bypass the original DPC, also raised garden beds and internal plaster work in contact with the damp substructure can all allow moister to travel around the DPC.
High ground levels are another reason you may be suffering from rising damp, this is when over time, the outside ground level garden/driveway has been raised above the original DPC or close to it. Without the 6-inch clearance needed between the ground level and DPC, rain water can splash above the DPC and start the upwards motion of capillary action totally bypassing the fully working damp proof course.
It’s important to remember that not all damp patches on internal plaster work are caused by rising damp, there may be another source of water ingress that you are not aware off. In this case you could be looking at condensation or penetrating damp, if your damp patches are higher up than 1200mm or unevenly distributed along the affected wall you could be looking a penetrating damp. Damp patches around your windows and doors or a build up of black spot mould could also point in the direction of condensation. To be sure of the issue you’re facing read more about Penetrating damp or Condensation. Alternately contact the experts here at Leodis Damp Control
