Rising Damp Treatment

Rising damp is the action of water moving vertically through porous building material in contact with the ground. This is brought about by the drying action of air on the upper surfaces which causes the wall to act like a wick, drawing water upwards from the ground by capillary action, which then evaporates from the surface into the atmosphere. The moisture will continue to rise until it reaches a height where unless no evaporation is possible, gravity takes over and pulls it down again.

Water coming from the soil will have various dissolved nitrates, chlorides and other salts (called hydroscopic ground salts) which will be carried upwards into the brickwork and plaster. As the water then evaporated, an increasing amount of these salts will be deposited in the wall. As ground salts are easily dissolved they also readily attract moisture from the atmosphere. This means that even if the rising damp is cured, the plaster will always be damp or contaminated. For this reason the plaster is always removed and replaced when treating rising damp.

Rising damp occurs because the building's damp proof course (DPC) has broken down or is being bridges by high ground. A DPC installed during construction will be a physical layer of an impermeable material. This can consist of slate, bitumen impregnated felt or plastic, for example. Many older properties do not have a DPC.

Where appropriate, Damp-Tech will install a chemical DPC system to control the problem.

The chemical DPC is injected into the walls at regular intervals. There will often be a small level of moisture held in the substrate due to salt contamination even when rising damp is controlled. Replastering will replace the salt contaminated plaster and protects the decorated surface from any residual moisture held in the wall.

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