Rising Damp / Damp Proofing Solutions / Treatments
Moisture in the soil can rise up through a wall by a process known as capillary action. Most old buildings were built without a damp proofing course or the damp proofing course may have failed due to the age of the property. The rise of water in capillaries is caused by the affinity of building materials for water. All building materials are wettable and will absorb water just like blotting paper.
Rising damp will appear along the base of the wall forming a characteristic tide mark 500/600 mm above floor level depending on the porosity of the building fabric and the rate of evaporation.
Impervious coatings such as vinyl wallpapers and the like, will retard evaporation and force the dampness higher up the wall.
If allowed to continue unchecked the process will cause the plaster and wall fabric to break down and timber in contact with the damp wall will decay.
Persistent rising damp often takes from the soil chlorides, nitrates and other salts which are deposited on the face of the plaster as the water evaporates from the surface.
Such salts are hydroscopic with the result that the face of the wall has the tendency of being persistently damp, particularly during humidity of the atmosphere, even after the rising damp has been arrested.
PREVENTION AND CURE
Building Regulations require that all modern properties are constructed with an effective damp proof course. Older buildings which have no damp proof course, or where the original damp proof course has failed due to deterioration with the passage of time, must be treated in-situ if dampness is to be prevented.
Pro-Tech CHEMICURE GROUTING
Provides an ideal solution to the problem of rising damp in the majority of situations – it can be successfully applied to walls of brick or stone construction, to walls of widely different thicknesses, and to walls of very old buildings where the method of construction may preclude the use of other systems.
The double action, two-part grout forms, in a single treatment, an insoluble silca gel which blocks the pores and the capillary paths within the wall, this forming a physical barrier to rising damp in addition to causing the reversal of the capillary force as provided by simple silicone damp proof courses.
INJECTED DAMP PROOF COURSE
This system consists of a water based siliconate solution which is injected into the base of the wall and forms a stable water repellent coating to the fabric of the wall. The injection treatment does not make the wall dry.
The residual moisture, therefore, must be allowed to dry out. If the plaster is badly affected by hydroscopic salts, replastering will be very desirable.
LECTROS / ELECTRO OSMOTIC DAMP PROOFING
This system works by introducing a very small and perfectly safe electric current into the wall just above ground level through a serious of titanium anodes inserted into the brickwork.
Its effect is to repel the rising moisture down the walls into the ground. This ensures the protected walls remain dry and totally free of damp. Installation involves the removal of damp defective plaster and drilling a series of small holes into the masonry just above ground level and inserting titanium anodes that are linked by a connecting wire. The area is replastered and the system is invisible and disruption is minimal.
CAUSE AND AFFECT
Unless unblocked by a damp proof course, moisture in the ground can rise within the wall of a building by capillary action. The resultant dampness can cause damage to the wall fabric due to frost action, continually spoil decorations and provide conditions in which timber in contact with the damp walls may be attacked by rot.
Replastering will be very desirable in any event and is normally recommended as part of any curative treatment for rising damp. Hack off the old plaster to a height of at least 400 mm above the uppermost limit of the damp.
This will remove deposits of soil salts which have accumulated in the past but will leave some in solution in the walls. Therefore, replastering with a rendering which resists movement of water and salts to the surface. There are many specifications for these and a number of proprietary “renovating” plasters are available for this purpose.
Alternatively, either of the following specifications may be used:
1. Replaster using an undercoat of 1:3 cement – sand to which is added an integral water proofing compound. Follow with a plaster finishing coat.
2. Apply an undercoat of aerated 1:6 sand – cement using an air – entraining agent to produce the aeration. Follow with plaster finishing coat. This second specification is recommended on old walls which may not be strong enough to resist the shrinkage of a dense 1:3 rendering.