Despite what many may think, rising damp is not the common form of dampness encountered within buildings, this is left to condensation. Many older buildings, however, are affected by rising damp to some degree.
Rising damp on buildings is commonly defined as the upward flow of moisture through a permeable wall structure. The moisture derived from ground water rises through the pores (capillaries) in the masonry by a process loosely referred to as capilarity, which in turn causes the masonry to act like wick.
Rising damp can vary in severity depending on a number factors, such as the level of groundwater, the pore structure of the masonry i.e. brick, stone mortar etc, together with the rate of evaporation away from the wall surface.
Rising damp can often require treatment due to the number of undesirable and unsightly consequential effects, such as;
- Decorative Spoiling Moisture and ground salts present due to rising damp can cause wallpaper to peel, plaster to deteriorate and paint to blister
- Erosion of Building Fabric Ground salts introduced into the wall as a result rising damp can attack and dissolve the binders in brick, stone and mortar, which in turn can cause them to lose their strength and structural integrity.
- Increased Heat Loss Dampness in porous building materials may cause a reduction of insulation properties as air in the pores is replaced by more conductive water. i.e. the thermal conductivity of a wet brick has been found to be twice that of a dry brick.