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As the colder weather begins to bite, the instances of condensation causing dampness within the home rise. From black mould and staining on walls to mildew on clothes and shoes in cupboards, this problem, although usually seasonal, can be a major nuisance. The cause of condensation is simple - air contains water vapour and when air cools down enough, that water vapour turns to liquid. Cold surfaces in the home, such as the inner surfaces of an outer wall, can cause the air to cool enough to deposit moisture on that surface in exactly the same way as a milk bottle taken from the fridge will attract moisture to its outer surfaces. The transfer of cold through a wall is often referred to as "cold bridging".

Reducing condensation can therefore be achieved by lowering the moisture content of the air in the home or by dealing with cold surfaces or, ideally, both.

Lowering Moisture Content of The Air
A few simple measures should be taken to avoid the build-up of water vapour in the atmosphere inside the home:-

  • Provide adequate ventilation to allow moist air to escape, in particular from areas where moisture is produced the most such as kitchens and bathrooms. Current regulations for new houses stipulate that these areas must have adequate ventilation, however there are many existing homes that do not have any form of mechanical air extraction.
  • Reduce the sources of moisture, for example avoid drying clothes inside the home without adequate ventilation. Ensure tumble dryers are vented correctly.
  • The use of a dehumidifier unit to remove moisture from the air.
  • The use of a whole home ventilation system. This gently forces a continuous air change, replacing moist damp air in the home with fresh filtered air.
Dealing With Cold Surfaces Caused By Cold Bridging
Insulation of external walls is the key to reducing cold surfaces within the home. In addition to reducing condensation this of course has benefits in heat conservation and therefore savings on heating costs.
  • If the wall is of cavity construction, cavity wall insulation can be installed.
  • Many older homes are of solid wall construction making cavity wall insulation impossible, however in these situations, internal or external wall insulation can be applied.
  • The application of a polystyrene wallpaper lining should be considered when next decorating.
  • Doors to cold cupboards should be left ajar to allow warm air from the heated room to circulate (cupboards against outer walls are often a few degrees colder that the room).

Dealing With Mould On Walls
Eliminating condensation will prevent black spot mould/mildew spreading but surfaces should be treated correctly to remove existing mould. There are specialist products available for cleaning off and preventing the re-occurrence of black spot mould/mildew. These contain a fungicide which kills any spores which would allow the mould to grow again or spread to other areas. These products are available from DIY and decorating stores. They should never be used without first reading the instructions.

Some Facts To Bear In Mind

  • An average family produces about 11 litres of water per day by breathing, washing, cooking, etc.
  • Paraffin and liquid gas heaters produce about 1.3 kg of water for each kg of oil/gas burned.
  • Normal gas ovens and gas fires produce water but in less quantity.
  • Dogs and cats emit about twice as much moisture per unit of body weight as do human beings. A human adult puts between 50 and 200 grams of moisture into the air each hour by breathing and perspiration.
Where Damp Shield Can Help
We are able to carry out many of the works to enable the reduction of moisture within the home and cold bridging. Some of the services we can provide include the supply and installation of:-
  • Whole home ventilation systems.
  • Extractor fans in bathrooms and kitchens.
  • Internal wall insulation (polystyrene and PIR dry lining systems).
  • Passive air ventilation.
For further information and advice, please do not hesitate to contact us



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