How to reduce condensation on VELUX windows

Condensation on a VELUX roof window is a common concern, particularly during colder weather. Water droplets may form on the room-facing surface of the glass, run down the pane or collect around the lower part of the window.

This does not automatically mean the window is leaking. Condensation is usually caused by warm, moist indoor air meeting a colder surface. However, repeated moisture should still be managed because it can affect frames, paintwork, plaster and the comfort of the room.

Why condensation forms on roof windows

Warm air rises, carrying moisture with it. This means roof windows can be one of the first places condensation appears, especially in loft conversions, bedrooms, bathrooms, kitchens and rooms where clothes are dried indoors.

Condensation becomes more likely when:

• the weather outside is cold
• indoor humidity is high
• the room has limited ventilation
• warm air rises into an upper floor or loft space
• showers, cooking or drying clothes add moisture
• air cannot circulate around the roof window

Ventilate the room regularly

Ventilation allows moisture-laden air to leave the room before it settles on cold surfaces. Opening the roof window for short periods can help exchange humid indoor air for drier outdoor air.

Some VELUX windows also have a ventilation feature that can provide background airflow while the window remains closed. This should be used in line with the window's intended operation.

Ventilation is particularly important:

• after showering or bathing
• while cooking and shortly afterwards
• when drying clothes indoors
• in bedrooms first thing in the morning
• in loft rooms where warm air naturally gathers

Use extractor fans effectively

Bathrooms and kitchens produce significant amounts of moisture. An effective extractor fan can remove humid air before it moves through the rest of the property.

Run the extractor during moisture-producing activities and leave it operating for a suitable period afterwards. Make sure vents are not blocked and that the fan is actually extracting air rather than simply making noise.

Avoid drying washing without ventilation

Drying washing indoors releases a surprising amount of moisture into the air. If this cannot be avoided, keep the room ventilated and consider using a dehumidifier.

Avoid placing wet washing directly beneath a roof window, as warm moist air will rise towards the cold glass.

Keep the room consistently heated

Large temperature changes can increase condensation. A room that becomes very cold and is then heated quickly may produce more surface moisture than a room kept at a steadier temperature.

Consistent background heating, combined with ventilation, can help reduce the temperature difference between the glass and room air.

Allow air to circulate around the window

Heavy blinds, curtains, furniture or stored items can restrict airflow around a roof window. Moist air may then become trapped close to the glass.

To improve circulation:

• avoid blocking the window area with furniture
• open blinds regularly
• do not leave wet items beneath the window
• allow warm room air to move across the glazing
• keep ventilation openings clear

VELUX blinds can improve light control and comfort, but they should still allow the room and window area to ventilate appropriately.

Consider using a dehumidifier

A dehumidifier can be useful in rooms with consistently high humidity, particularly during winter. It removes moisture from the indoor air before it settles on windows and other cold surfaces.

A basic humidity monitor can also help you understand when moisture levels are highest and whether changes to ventilation are working.

Wipe away condensation when it appears

Wiping the glass does not solve the underlying humidity problem, but it can reduce the amount of water sitting against the window frame or running onto surrounding finishes.

Use a clean, absorbent cloth and dry the lower corners and frame area carefully. Repeated heavy condensation should prompt a closer look at room ventilation and humidity.

Is it condensation, a leak or failed glazing?

These three issues are sometimes confused, but they need different solutions.

For more help distinguishing the cause, read Is It a Leak or Condensation on My VELUX Window?

When condensation may indicate a wider problem

Occasional light condensation during cold weather may be manageable through ventilation and humidity control. Persistent heavy condensation, however, may point to wider issues.

Ask for advice if:

• condensation is present most days
• water is damaging the frame or surrounding plaster
• the window is also draughty or difficult to close
• moisture appears between the panes
• there are damp marks after rainfall
• the window is older and showing several signs of wear

AR Windows can advise whether the roof window needs maintenance, repair, glazing work or replacement.

Can servicing help with condensation?

Servicing cannot remove excess moisture from a room, but it can help identify whether the roof window is closing properly, whether seals are worn and whether another fault is contributing to the problem.

Planned care through an Annual Service Contract can be useful for suitable windows, particularly where there are several units or older installations.

What information should you send AR Windows?

Clear photographs and a short description can help distinguish between condensation, failed glazing and possible water ingress.

Helpful information includes:

• a photo of the full roof window
• close-up photos showing where moisture forms
• whether the moisture wipes from the glass
• whether it appears during rain or cold weather
• a photo of the VELUX product code if safe to access
• the approximate age of the window
• whether the window is also stiff, draughty or misted
• details about the room and how it is used

Final thoughts

The most effective way to reduce condensation on VELUX windows is to control indoor moisture, improve ventilation and maintain consistent airflow around the glass.

If moisture remains persistent, appears between the panes or is accompanied by leaks, draughts or operational problems, AR Windows can help identify whether maintenance, repair or replacement is needed.