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I have already touched on a number of damp problems over the page, rising and penetrating damp, these are covered by the first 9 items on the above list. However the most common cause of dampness is condensation, a diagnosis which people often find hard to believe.
What is condensation.
Condensation is when the (technical bit) Relative Humidity (RH) which is regarded as "the amount of water vapour in the air expressed as a percentage of the amount that would saturate it at the same temperature" reaches its dew point (DP) (the temperature at which water vapour changes to water droplets) easy isn't it.
Lets try an easier way to explain.
Moisture is given off by a number of items around the house, cooking, washing/drying machines, gas heaters, bathing/showers and one of the worst culprits, human beings.
The moisture content (RH) of the air in the house rises during the winter because the heating is on more and the windows are closed up, the heavily moistened air comes in contact with colder surfaces often windows or outside walls and because of the sudden drop in temperature (DP) the moisture in the air changes back to water droplets which is the reason why water appears on your window cill.
A simple experiment to prove this is to exhale onto a window or mirror when it is cold, water droplet will occur. This is condensation.
Condensation is caused by the way we live, if the heating was turned down slightly, windows to bathrooms and kitchen were opened when in use and extra ventilation was allowed condensation would not occur.
Black mould, often found in bathrooms, kitchens and cupboards, is due to condensation. By simply increasing ventilation, and treating the mould with a good bleach the mould will disappear. Customers are often disappointed that nothing more is required, but condensation is easily, and relatively inexpensively treated.
Treatments of rising damp.
The skirting boards need to be removed to facilitate the injection of a new damp proof course.
Remove the internal plaster to a height of 1 metre or 300 mm above last sign of dampness which ever is highest, the plaster needs to be removed due to the probable build up of nitrate and chloride salts which will attract moisture from the atmosphere.
Inject a new damp proof course above the external ground level, any internal wall below the external ground level should be tanked (a vertical treatment which keeps dampness from permeating through)
Re render using a course sand and a Portland cement (3:1) with a slat inhibitor added, this will stop any salt transference from the old brickwork through to the new plaster.
Re plaster using a gypsum thistle plaster.
Re fit skirting boards replacing any rotten timber as necessary.
The above treatments is the most common type of treatment carried out and is a general guide, but each property is different and should be assessed and treated accordingly.
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