Misting on the Outside of Roof Windows

Posted by Becky Graham on 25th October 2017

As insulation properties of glazing have improved and will continue to do so a common concern has arisen – misting of the glass on the outside of your roof window for short periods of time. This is not caused by any defect of the window but a result of the increased insulation properties of modern glazing.

Dew starts forming when the temperature of the exterior glass reaches the dew-point temperature of the outside air. This is most common early morning and at night.

If you’re looking at a new installation or replacing old windows you can buy a window with anti-dew coating such as the VELUX 66 and 62 panes which are triple glazed. These also have excellent insulation properties. For more information on glazing options click here.

The anti-dew coating doesn’t prevent dew forming but it does reduce the number of hours external condensation is present and helps clear it more quickly. If you’ve already got your roof windows installed exterior sun screening such as a roller shutter can help.

For further information on misting on the outside of your roof windows, you can contact VELUX directly on 01592 778 225.