29th November 2021

Misted Double Glazed Windows – How to Clear and Prevent It

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Posted by: tina

During the colder winter months, misted double glazed windows is a common issue for many homeowners.

Whilst we would typically associate misting with single glazing, it can also occur with double or triple glazing.

Misted Double Glazed Windows

As double-glazing experts, one question we are asked many times at this time of year is ‘how to clear or prevent misted double glazed windows.

Misting is also known as condensation. It refers to the formation of water droplets between the two panes of glass within the double-glazed unit.

Misting on the inside and outside of your double-glazed windows means that your new windows are offering outstanding energy efficiency by preventing draughts and heat loss.

Why does misting happen, and how can we prevent it?

Misting happens when warm air comes into contact with colder surfaces (such as your double glazing) or the humidity is “too” high.

The scientific definition is that the air, touching colder surfaces, is cooled below its “dew point”. This temperature may vary depending on the humidity ratio in the given environment, so condensation happens even on warmer surfaces with higher humidity.

Depending on which side of the window the misting occurs, ensuring that your home is ventilated can prevent misted double-glazed windows from happening in most cases,

Misted Double Glazed Windows

Interior Misting

If the misting is on the inside of your double-glazed panes, it usually means that there is moisture in the air. So even if the glass is insulated from the cold temperature outside, the water vapour still reaches its dew point.

You can quickly resolve the issue by wiping the water in excess with a squeegee or microfibre cloth. Reduce the humidity in the room with a dehumidifier.

Other useful tricks comprise:  When cooking keep the kitchen door shut and cover pots and pan with a lid. Activating an extractor fan or slightly opening a window to let air flow around when showering or taking a hot bath. Avoid drying clothes inside or on radiators.

Install a smart thermostat and keep the house at a constant energy-efficient warm temperature.

Exterior Misting

Misting on the outside of your double glazing is perfectly normal – it means that your double glazed windows are extremely energy efficient. It happens when the air outside warms up more quickly than your glass, for instance, early in the morning, reaching its dew point.

Misted Double Glazed Windows

Misting between the Panes

If you see misting is between the panes of your double-glazed windows or doors, this is a concern and isn’t treated as easily. it usually means that the sealed unit has blown and will need to replace the glass unit.

Blown windows generally occur when the seal on the glazed unit has failed. This means that warm air can escape, and cold air can get in, creating moisture build-up on the spacer bar within the pane.

If your double-glazed windows were installed less than ten years ago, your glass unit might still be under the product guarantee.

Ventilating your home daily by opening a window for approx. 15 minutes will make a massive difference to moisture build-up and help prevent misted double glazed windows.

It is essential to remove any misting daily as the persistent presence of water may reduce the lifespan of a double glazed glass unit and favour the growth of mould, which may damage the window frame or cause health issues.

If you are interested in replacing your windows with new A-rated double glazing, contact us today for a free no-obligation quote.


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