WHAT IS RISING DAMP ?
Rising damp is an issue that has troubled builders and homeowners since Roman times.
Rising damp is the term used for the slow movement of water from the lower parts of walls to higher parts of the structure. It is a common problem affecting older homes as well as newer buildings that may not have been correctly constructed.
Rising damp occurs when groundwater rises up through tiny cracks in the brickwork or masonry of a structure through a process called capillary action. When moisture infiltrates the walls of a building it can cause damage to its integrity and physical appearance.
Rising damp is prevented in modern buildings through the use of a damp-proof course a waterproof plastic membrane that goes along the mortar line of a building. Older buildings or buildings where the damp-proof course has been damaged are susceptible to damp.
Rising Damp is called 'Rising Damp' because the moisture starts at the base of the wall and moves slowly upwards. The reason rising damp rises up the wall is due to capillary action, evaporation and salt. Water rises up the wall by capillary action homogenizing through the masonry to the point where evaporation occurs. As the dampness evaporates from the wall into the atmosphere, the solids that had diluted the water will accumulate in the surface layer of the masonry.
Salts accumulate in the masonry at the first point where the dampness evaporates, usually the first 10mm at the base of the wall just above your skirting boards. As the salts accumulate on the surface of the masonry, the pores of the masonry gradually become blocked which slows down the evaporation in that lowest 10mm of the wall. The water then rises above the masonry pores which had been partially blocked by salts to the next point of least resistance, to evaporate more easily.
Damage will keep rising up the wall until the weight of the water has enough downwards force, from gravity, that it cannot rise any higher. Even if the pores of the masonry beneath the highest point of vertical capillary action are already semi restricted by prior salt accumulation.
Dampness will continue to evaporate from the already effected areas, accumulating to the surface point of the masonry wall and eventually crumble to dust. It can take some years for rising damp to become a structural issue.
Rising Damp with Exposed Brick will normally show with deterioration of the mortar between the bricks and after some time the bricks will start to collapse.
Rising Damp with Render will usually show in 'bubbling paint' starts out looking more like pimples in the paint, salt deposits, stains and render breaking down to its base components appearing as sand and cement dust.
The damage resulting from Rising damp is not caused by the actual water itself, water is just the carrier for diluted salts. Water travels through masonry via capillary action which causes the masonry to become damp. Water is the vehicle that carries the salt.
As Remedial Experts we see dampness and wetness as two distinctly different problems. There is a difference between damage from water and damage from dampness.
The damage you can see from rising damp is most often from salt. As salt dries, salt crystals grow. These salt crystals grow between the tiny bonds of the sand and cement particles that make up the masonry and causes the bond between the sand and cement to “unstick”.
When the bond is broken, the once solid masonry will return to its base components of individual grains of sand and cement, showing at the base of the wall. Salt is transported up the wall by water 'the vehicle'.
The catalyst for the damage caused by rising damp is evaporation. If masonry is holding water that contains diluted salts, the water evaporates, leaving solids behind. The accumulation of salt crystals is what causes your masonry to turn to dust and bubble your paint.
Therefore, more evaporation actually speeds up the damage being caused by the rising damp. Evaporation is the 'ENGINE' that drives rising damp.
What does Rising Damp do to the building?
Rising damp can cause a number of aesthetic, structural, and even health related problems.
Aesthetically, rising damp can peel, crack, and bubble paint and plaster work, create a water-tide marks that show where the water has risen to along walls, as well as efflorescence (a white salt deposit which also looks unsightly on walls, floors or ceilings).
Structurally, damp can get into timber structures and skirting boards causing them to rot. Also when water rises it can deposit salt in building structures which causes corrosion and deterioration of integrity through a phenomenon known as salt attack.
Damp conditions also encourage the growth of mould, which can be a significant health hazard. The damp itself can be a factor in health conditions such as asthma, allergies, cold and flu.
Rising damp can significantly affect the integrity and value of a property and superficial treatments such as repainting, coating, or cleaning the surface won't make it go away.