Moisture is one of the main problems with older properties, the most common being rising damp. A high proportion of older buildings are aff ected by rising damp to some degree or another. The most common source of moisture in the base of the walls of buildings is from defective ground and surface drainage due to a combination of such factors as rising ground levels, the failure of ground drainage systems, and the increased use of concrete or finishes around buildings without consideration of drainage slopes.
Moisture, naturally present in the ground, rises inside the walls by capillary action. Ground water contains soluble salts that over time can accumulate within the masonry. When evaporation occurs within the material, salts can be deposited within the pores. The expanding salt crystals in these locations may result in fractures forming in the material and spalling of the surface.
If not properly protected with a water-repellent finish, the façades can absorb rainwater that, once inside the masonry, can contribute to the deterioration of materials, heat loss and the appearance of stains and mould.
The water vapour naturally present in indoor environments will condensate on cold wall such as to exposed elevations or to walls of solid construction, thereby increasing the amount of moisture inside the masonry.