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Condensation and mould

Now that we are in the winter months condensation symptoms (particularly mould) are becoming prevalent again.

The recent, desperately sad, news of Awaab Ishak the two-year-old who died has brought the topic of mould into sharp focus. The inquiry concluded that Awaab died of a severe respiratory condition caused by prolonged exposure to mould. The findings of the enquiry can be found here.

Whilst tragic, this was an extreme case with failures being found in both the local authorities handing of the issue and in the healthcare provided.

Dampness caused by condensation is often mis-diagnosed as rising or penetrating damp. Incorrect remedial works can often be carried out only for the original problems to return.

In the home, condensation is largely the consequence of today’s improved standards of insulation and draught proofing, particularly when older properties have been upgraded.  Lack of adequate ventilation allied to modern occupancy lifestyles in terms of cooking, washing and bathing can lead to a build-up of excessive humidity and moisture.


This leads to condensation forming on cooler surfaces, particularly in areas with little air circulation.  The result can be peeling decorations, unhealthy living conditions, unsightly mould growth and damage to fabrics and clothing.


The ability of air to hold water vapour increases with temperature.  Condensation arises when the air is fully saturated and 100% relative humidity (dew point) is reached.   Then any air in contact with colder surfaces will cool and release moisture in the form of water droplets.


Air with a high moisture content will have a high vapour pressure.  Water vapour does not always condense in the room of it’s source and as a gas will move through the property seeking pressure equalisation with the colder air outside.


Building materials vary in their heat conduction capabilities and so their capacity to stop surface condensation forming.


Various general measures can be adopted to help alleviate the problem of condensation, including:


Reduce sources of excess moisture (eg. drying clothes indoors, keeping lids on saucepans, venting tumble driers, etc).

Improve ventilation and air circulation (eg. open windows, utilise kitchen and bathroom extractor fans, keep furniture and clothing clear of external walls, etc).

Improve heating and maintain constant levels.

Improve levels of insulation and, therefore, increase surface temperatures.


Should problems persist following practical measures it may be that mechanical ventilation needs to be considered. Further information on positive input ventilation systems can be found here.

Condensation problems are often found in tenanted properties and an informative article from the National Association of Landlords can be read here.

Please contact us if you have any questions or if you would like a survey carried out to correctly identify the cause of dampness and the most-appropriate course of action.

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