Condensation is an increasingly common problem in the home.

Part of the reason is that all those measures we’ve taken to make our homes more comfortable and energy efficient - such as central heating, cavity wall insulation and double glazing - serve to ‘shut in’ the moisture that actually causes condensation in the first place.

So although double or triple glazing hugely reduces condensation by insulating rooms from the cold outside, it can occasionally be part of the problem. That’s why the the most effective way to combat condensation is to ventilate any affected rooms by partially opening the window or opening up the trickle vents in the top of your window frame, if you have them. (It may feel like you’re letting all the heat escape but actually, you’re replacing warm, moist air with cool, dry air that’s cheaper to heat in the long run.)

If that doesn’t get rid of the problem, there are other steps you can take, depending on what kind of condensation you have and what’s causing it. Use our easy checklist to assess the nature of your condensation problem and the best way to tackle it.

A. Double or triple glazed windows.

If condensation appears on the room side of your windows:

  • Increase natural ventilation by opening windows and/or trickle vents
  • Make sure any room with a freestanding gas or paraffin heater is PERMANENTLY ventilated (NOTE: This required by law)
  • Fit an extractor fan or air heat exchange unit in your bathroom
  • In cold weather especially, keep the heating on a low setting, even when you’re out of the house. Even a couple of degrees extra can be enough to deter condensation
  • Hang curtains at least 15-20 cm in front of your windows. This will allow warm air to circulate between them and keep the glass surface warm enough to stop condensation forming
  • If your fireplace has been blocked, consider fitting wall vents to increase airflow. If you have a gas fire, check that the back plate has vent holes below the fire, unless this is provided for in the fire design
  • Fix an extractor hood over your hob and make sure it vents to to the outside if possible. Change or cleans filters as often as stated by the manufacturer
  • Draught proof internal doors and keep them closed, particularly those leading from bathrooms and kitchens. You can’t stop moisture circulating through your house altogether, but limiting its movement will help
  • Wherever possible, fit radiators directly beneath windows, This will increase the surface temperature of the inner glass and prevent moisture condensing onto it

If condensation appears on your window frames:


This is usually limited to steel or aluminium frames.

Most modern profiles have a thermal break built into them to prevent heat escaping through the frames to the outside, so any condensation is usually the result of poor fitting or a failure within the frame itself.

The solution


  • If the problem persists, call your local Eurocell installer for advice.

If condensation appears on the outside of your windows:


This is a natural consequence of weather conditions and doesn't indicate a fault with your double glazing windows.

The solution


  • To clear any excess water, uses a squeegee followed by a dry cloth

If condensation occurs inside the sealed glazed unit:


This indicates a failure with the unit itself.

The solution


  • If your windows are still under warranty, call the manufacturer or your installer

B. Secondary double glazing

If condensation appears on the inside surface of the outer glass:

Secondary double glazing doesn’t provide a completely airtight seal between glass layers, so air can inevitably creep in between them, where it will meet the cold outer glass window and produce condensation.

  • Make the seal between the secondary glass and the original single glazed window as airtight as possible
  • Check desiccant packages for moisture. If necessary, dry them out on radiators or replace with new ones
  • Check for moisture in any unsealed wooden separators and replace if necessary
  • Try to limit how often you open the secondary glazing, particularly in cold weather, to limit the volume of warm, moist air that gets behind it
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