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How to stop condensation on UPVC windows

21 December 2022

Central heating, cavity wall insulation, double glazing… they’re all brilliant for keeping our homes warm. But they can, occasionally, also lead to condensation by inadvertently ‘shutting in’ unwanted moisture.

In this guide, we’ll show you how to stop condensation on your UPVC windows and what to do if the problem persists.

Contact Us for Specific Advice


What is the most effective way to combat condensation?

Whatever type of house you live in, and whatever type of windows you have, ventilation is the single biggest weapon in your battle against condensation.


How to get rid of condensation on double- or triple-glazed windows

If condensation appears on the room side of your windows:

  • Open windows or trickle vents to increase ventilation and replace warm, moist air with cool, dry air (note: in UK law, any room with a freestanding gas or paraffin heater must be permanently ventilated).
  • Fit an extractor fan or air heat exchange unit in your bathroom.
  • Hang curtains at least 15cm from your windows, giving enough space for warm air to circulate and keep the glass warm enough to stop condensation forming.
  • Consider installing wall vents to increase airflow.
  • Fit an extractor hood, regularly change or clean the filters, and make sure it vents to the outside if possible.
  • Ensure internal doors are draught-proofed and closed, especially bathroom and kitchen doors.
  • Fit radiators directly beneath windows to increase the temperature of the glass.

If condensation appears on your window frames:

  • Call your local window installer for advice. This problem usually only occurs on steel or aluminium frames and is often the result of poor fitting or a failure within the frame itself.

If condensation appears on the outside of your windows:

  • Use a squeegee and a dry cloth to remove any excess water. There is no fault with your windows. This is a natural consequence of normal weather conditions.

If condensation appears inside the sealed glazed unit:

  • Call your window’s manufacturer or installer. There is a fundamental failure in the unit.


How to get rid of condensation on secondary double glazing

On secondary double glazing, there is no airtight seal between the glass layers. This means air can flow through, meet the cold outer glass window, and produce condensation.

  • Ensure the seal between the secondary glass and the original single-glazed window is as airtight as possible.
  • Check desiccant packages for moisture. Dry them on radiators or replace them if necessary.
  • Check for moisture in any unsealed wooden separators. Replace them if necessary.
  • Limit the amount of warm, moist air getting behind the secondary glazing by reduce how often you open it, especially in cold weather.

Contact Us for Specific Advice or view the UPVC Windows range.


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