What is Damp?Structural dampness is the presence of unwanted moisture int he structure of a building, either the result of intrusion from outside or condensation from within the structure. A high proportion of damp problems in buildings are caused by condensation, rain penetration or rising damp
Rising DampMost people associate rising damp with water, but moisture (not water) is the key to understanding rising damp. The ground is always moist. Brickwork is naturally porous and absorbent. Moisture from the ground creeps up through the pores, or capillaries, in the masonry. Without a damp proof barrier to stop the moisture from rising in this way, the brick or other materials will continue to draw moisture from the ground until it eventually reaches its own level. The level depends on conditions such as humidity, temperature, evaporation, and the type of construction and insulating materials used. Masonry with fine pores, for example, will allow moisture to rise higher that a more coarse material. A humid environment slows evaporation, which also allows the moisture to rise higher. Where evaporation is severely inhibited (for instance, because of the use of sealants) moisture can sometimes rise more that 2 meters. Most often, rising damp will reach a level of 1.2meters
Salt is the CulpritGround water contains soluble salts, such as chlorides, nitrates and sulphates. These salts in solution with the ground moisture rise up the wall and are left behind when the moisture evaporates. Over time, large quantities of these salts are deposited in the masonry and decorative surface of the building. Salts (not water) cause most of the damage.
Dampness tends to cause secondary damage to a building. The unwanted moisture enable the growth of various fungi in wood, causing rot or mold health issues and may eventually lead to sick building syndrome. Plaster and paint deteriorate. The highest airborne mold concentrations are found in buildings where significant mold infestation has occurred, usually as a result of severe water intrusion. Molds can grow on almost any surface and occurs where there is a lot of moisture from structural problems such as leaky roofs or high humidity Levels. Airborn mold concentrations have the potential to be inhaled and cause serious health effects in humans. Externally, mortar may crumble and salt stains may appear on the walls. Steel and iron fasteners rust. it may also cause a poor indoor quality and respiratory illness in occupants. If extreme cases, mortar or plaster may fall away from the affected wall.
Signs of Rising DampUsually found at the base of the wall or where the ground level is higher on the opposite site Peeling and bubbling paint Efflorescence (white powdery substance on the all or paint) Mould growth and decayed skirtings
Treating Rising Damp
Treatment of rising damp typically involves injecting of a waterproofing chemical to the effected areas.