Damp proofing describes the control methods used to prevent rising damp in walls of buildings. Given a basic understanding of cause and cure, rising damp can be prevented by professional or DIY damp proofing, whereby a remedial damp proof course is installed using damp proofing cream designed for the professional builder and those competent in DIY or by the insertion of an electro osmosis damp proof course.
Rising damp is a form of dampness caused by the movement of ground water through a permeable masonry wall having no effective damp proof course by which to stop damp from rising. The water rises through the pores in the masonry via a process called capillarity.
Capillarity is an electrochemical action which attracts water molecules to mineral surfaces, enabling water to move vertically through pores of a certain size despite the counteractive force of gravity. The same process is responsible for the movement of moisture from tree roots to tree tops via intricately stacked hollow cells. Fortunately the pores in masonry are not as fine as those in trees and rising damp in walls rarely ascends more than about one metre in height.
Rising damp only becomes a problem if it affects vulnerable materials or finishes that are in contact with the damp wall. For example if it affects timbers such as joists, skirting boards or the bottom of door frames such as to provide wood rotting potential or if it causes wall plaster or wall coverings to deteriorate or become stained. Damp proofing products and techniques are designed.to stop capillary action and prevent damp in walls.