The most common cause of dampness in buildings is condensation, which can often lead to the appearance of mould growth. It is the presence of water condensed on the wall, ceilings and other cold surfaces which support mould growth.


The amount of water vapour that the air can contain is limited and when the limit is reached the air is said to be saturated. The saturation point varies with temperatures, higher the temperature of the air the greater the weight of water it can contain. Water vapour is a gas and if in a mixture of gases such as when present in the air, it contributes to the total vapor pressure exerted by the mixture.(moist air exerts a greater pressure than dry air).


Too much water vapour

The main cause of condensation is naturally the generation of moist warm air by domestic activities. Moist air can come from cooking, bathing, washing, drying clothes as well as paraffin and flueless gas heaters. Up to 17 litres of water can be produced daily in some homes. Usually in certain areas such as bathrooms and kitchens where moist, warm air can then spread to cooler parts of the house to condense on cold surfaces.

Inadequate heating – The best heating to avoid condensation is continuous background heating


The effect of moisture generation is further aggravated by the way houses are ventilated, it is theoretically possible to avoid condensation with adequate ventilation. Up to about the late 1960s there was natural ventilation in many homes because of the lack of double glazing poorly fitted windows, door and open fire places.

Present attitudes have eliminated natural ventilation by double glazing, draught excluders, fitted carpets and the removal of open fire places. To put it simply the greater ventilation the great heat capacity required to replace heat loss. Builders have effectively sealed and provided better conditions for condensation to occur.

Ventilation is only effective if consistent throughout the whole inside of the house.

There is real danger of condensation occurring where air is left undisturbed behind furniture and cupboards, often recognized by the appearance of mould growth


Unless cold spots are eliminated condensation is inevitable. Any action must therefore involve a lowering of moisture levels in the air and eliminating cold surfaces with in the building.

RTM Services can provide for all aspect of condensation from passifier vents and humidity fans to lower the humidity in your homes and creams for external masonry walls which will build up the UV value and retain the heat in your house.

Contact us today for a free survey and estimate on 0800 955 8995 or