Water vapour is continually present in the atmosphere and in the home this natural water content is increased by day-to-day activities which create steam such as cooking, bathing, washing, boiling water etc.
This water vapour is undetectable when carried in warm air, but it condenses into water droplets when it comes into contact with cold surfaces such as glass. Normally, water vapour is controlled through natural ventilation via airbricks and chimneys etc but conservation measures have lead to more efficient sealing of buildings. This may result in trapped water vapour and increasing problems with condensation.
Condensation is best controlled by ventilation and this is achieved by opening windows, fitting extraction units or by fitting wall vents to provide airflow. Some heat should always be maintained in the building during cold weather. The temperature may be increased in areas where condensation is a particular problem. If possible, internal doors to kitchens and bathrooms should be kept closed and sealed against draughts to prevent excessively moist air being transferred to other areas. Bedroom windows should have night ventilation facilities to provide air circulation. Curtains should be a minimum of 150mm away from the window to ensure airflow, with suitable gaps.
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