What Causes Rising Damp?
Rising damp is caused by the rising of groundwater through capillaries in masonry. As this has been a well-known problem for some years, buildings these days are built with a DPC. However, rising damp can still occur, especially in older buildings. The cause of this is often a faulty or non-existent DPC. If this is the case a remedial DPC needs to be installed to stop rising damp from occurring.
How Does Rising Damp in Houses Occur?
Rising damp in walls, also called capillary ascending moisture, is the ascent of moisture through capillaries in masonry.
Capillaries are fine, elongated tubes with very small internal diameters. In masonry, these tubes are of varying thickness and can, in some cases, form cavities. The smaller the diameter of the capillary, the more the surface tension comes into force. This capillary force, which develops due to the surface tension, creates the effect of capillary action and causes moisture to rise. The smaller the capillaries, the higher moisture rises.
Capillary action means the rising of moisture in capillaries contrary to gravity. The effect of capillary action is used in medicine as well as in nature. To take a small blood sample a very fine tube is held against a small cut, at the ear or a finger for example, and the capillary action draws the blood into the small tube. Plants use capillaries as water-conducting system for watering. In masonry, which contains fine piliform tubes, capillary action can have negative effects and lead to rising damp.
Rising damp is a much disputed field, due to the common misdiagnosis of damp walls. The source of dampness should always be thouroughly investigated because an incorrect diagnosis can lead to further damage and unnecessary costs. If in doubt, it is recommended to consult an expert, as both condensation and penetrating damp could also be cause of dampness.