Condensation Control

Most of us will identify condensation as the steaming up of mirrors after a shower, or water vapour on our windows on a cold day.  However, condensation can be much more problematic than this, eventually creating a damp black mould on walls; usually at high level, and on external walls (which tend to be colder than internal walls).  Often, people confuse condensation for damp (rising damp or penetrating damp).

Causes of Condensation

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Persistent condensation, which causes black mould growth, is generally caused by inadequate heat or poor ventilation, and can cause health problems, especially for those with respiratory illnesses like asthma.

  • Condensation typically happens only in the colder months of the year, though the black mould once formed will not disappear unless cleaned, and is likely to reappear unless the core problem is rectified.
  • Water vapour and damp normally forms on the colder surfaces like, windows, mirrors, external walls (particularly corners), wall-to-floor junctions.
  • Condensation happens most often in areas where lots of moisture is produced, eg kitchens and bathrooms, and also unheated rooms into which moisture can drift (normally bedrooms where the heat isn't on as much).
  • Often condensation is worse in areas where air movement is restricted, eg behind furniture or inside cupboards on outside walls.
  • Condensation is a common problem where flueless paraffin or butane heaters or unvented tumble driers are used, and/or where clothes are dried indoors.

Treatment of Condensation

Condensation is caused by excessive moisture, inadequate ventilation and/or heat.  Water vapour is held in hot air, but once the air starts to cool, or meets a cold surface (eg an outside, unisulated wall), the vapour will condense on a cold surface, causing moisture or damp.  The remedy for this is to increase ventilation levels, circulate the air, and increase heat within the house, by using a Positive Air Ventilation unit.