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How to deal with condensation in double-glazed windows

Tom Gill
Written By
Maximilian Schwerdtfeger
Reviewed By
Updated on 20 August 2026
  • Condensation on the windows is a sign of poor ventilation
  • Try to keep your home at a consistent temperature
  • Prevention is the best way to maintain your windows

Double-glazed windows help keep your property insulated, helping to keep the heat in, lower your energy bills and reduce outside noise.

One of their few downsides, though, is condensation, which can occur when there’s a fault with your double-glazed windows.

This guide will tell you everything you need to know about dealing with and preventing condensation on inside of double glazing and in your double-glazed windows.

If you don’t have double-glazed windows currently installed or are looking to replace your current ones, we can help. Fill in our simple quote tool and our trusted suppliers will be in touch with free, no obligation quotes.

Condensation trapped between the panes of a double-glazed window
Condensation can occur when there's something wrong with the double-glazing

Double glazing costs can mount up if you don’t deal with condensation, which can be caused by a number of factors.

It all depends on the type of condensation – here are the most common kinds.

Condensation on inside of double glazing

If you have condensation on inside of double glazing, it means there’s too much humidity in the room, and little to no air circulation.

You’ll commonly see this in kitchens and bathrooms, where humidity levels are naturally higher than in other parts of your home.

Condensation on the inside of a window is also common if you’ve just had work done to your home. Wet plaster, drying cement and paint give off moisture that can easily lead to condensation.

This type of condensation can also cause mould on windows, so it’s important to tackle it.

If you want to know how much new windows might set you back, look at our double glazing cost calculator.

Condensation on the outside of your window

It’s rarer, but outside condensation can happen. Thankfully, it’s not the bad sort of condensation — in fact, it shows your double glazing is working properly.

It means your home’s insulation is thermally efficient, with little to no heat leaking out. Cold air from the outside reacts with the warm surface temperature of the windows, creating condensation.

Condensation in the gap between the double glazing

Condensation between the panes of your double-glazed windows usually means the sealant around the two panes is deteriorating.

Over time, the sealant used for double-glazed windows starts to degrade and crack, which lets air into the gap between the panes. This air then reacts with the moisture in the air to create condensation.

The type of sealant used can accelerate condensation. In cheaper double glazing, you’ll often see rubber strips used as a sealant, which deteriorates quicker than the more expensive silicone variety.

Another reason for condensation between the panes is a faulty spacer bar, which is used to separate the window panes creating an insulating cavity.

The spacer bar in double glazing is filled with a desiccant, which is a highly absorbent material that picks up moisture between the panes. If the spacer bar either degrades or absorbs more moisture than it can hold, excess moisture will start to form as condensation.

Heavy condensation covering the interior surface of a double-glazed window
Condensation between the panes of your double-glazed windows usually means the sealant around the two panes is deteriorating

Which process you use to remove condensation from your window depends on where the condensation is – inside, outside, or in the window panes.

Here are the best ways to get rid of each type of condensation.

Removing inside condensation

A dehumidifier is an excellent way to remove condensation on the inside of your double-glazed windows. You can pick one up for £60–£150 and it’s a great tool for dealing with all types of excessive moisture.

A downside to dehumidifiers is their running cost, which is around 50p per day.

You can remove condensation on inside of double glazing in your bathroom with an extractor fan. If you don’t have a fan, just open the window.

Removing outside condensation

Although outside condensation shows your double glazing is working properly, it can still be irritating to not see outside clearly.

Create more air flow by opening your windows to remove the condensation and stop it from building up again.

Removing condensation between window panes

Condensation between the panes of your double-glazed window means the seal has failed. You can either repair the window, or replace it entirely.

Repairing it is the cheaper option in the short term, but you should consider the expected life cycle of the window, and think about whether it’s worth replacing instead.

If you’re getting condensation in double glazing that’s less than 10 years old, you should check if the window’s still under guarantee. A decade is the standard warranty most double glazing companies provide.

The best way to deal with condensation is to prevent it happening in the first place. How you do that differs depending on whether it’s on the inside or outside of your windows, or between the two window panes.

Here’s how you can prevent each type of condensation.

Preventing inside condensation

Improving air circulation inside the affected room will help reduce humidity and help prevent condensation forming on your windows.

Try keeping your home at a consistent temperature too — frequent changes in temperature increase the chances of condensation forming.

When showering or having a bath, keep the extractor fan running throughout, or open a window. Do the same when cooking, and think about covering pots or pans to reduce excess water vapour from circulating.

You should also avoid drying clothes inside, as this can increase moisture levels. If you have a tumble dryer, make sure the ventilation pipe points outside the window, and that there are no leaks.

Preventing outside condensation

The best way to prevent condensation forming outside your double glazing is to increase the amount of shade in the area. Shade helps to retain warmth, which limits or stops condensation from appearing.

Use tall trees, bushes, or other plants to create shade, or a dedicated structure such as an overhang.

Preventing condensation between window panes

Stopping condensation forming in between window panes is very difficult, because spotting when a gap is starting to appear in the sealant is almost impossible.

Your best option is to periodically reseal windows, which will cost you between £50–£180 per window.

  • Getting condensation on double-glazed windows can be frustrating, but the benefits of double glazing far outweigh any inconvenience
  • Better insulation, lower energy bills, reduced noise levels and an increased property value are just a few reasons to get double glazing
  • Improving air circulation inside the affected room will help reduce humidity and help prevent condensation forming on your windows
  • Stopping condensation forming in between window panes is very difficult, because spotting when a gap is starting to appear in the sealant is almost impossible
  • If you’re ready to get double-glazed windows, why not fill in this short form? Once you’ve entered a few details, our trusted suppliers will contact you with quotes to compare.

Written By

Tom Gill

Tom has been writing for The Eco Experts for nearly five years an in that time, he has calculated the carbon footprint of the Roman Empire, profiled the world’s largest solar farms, and investigated what a 100% renewable UK would look like.

He has a particular interest in the global energy market and how it works, including the future of hydrogen, and Cornwall’s growing lithium industry.

Tom also regularly attends Grand Designs Live as a Green Living Expert, where he provides expert solar panel advice to members of the public.

He frequently focuses on niche environmental topics such as the nurdle problem, clever ways to undo the effects of climate change, and whether sand batteries could store enough energy for clean heating in the winter.

If there’s an environmental niche to be covered, it’s a safe bet Tom’s already thinking of how to write about it.

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Reviewed By

Maximilian Schwerdtfeger

Max joined The Eco Experts as content manager in February 2024 and became deputy editor in 2025. He has written about sustainability issues across numerous industries, including maritime, supply chain, finance, mining, and retail. He has also written extensively for consumer titles like City AM, The Morning Star, and The Daily Express.

He has represented The Eco Experts on national television several times, including the BBC’s Sunday Morning Live and ITV Tonight .

In 2020, he covered in detail the International Maritime Organisation’s (IMO) legislation on sulphur emissions and its effects on the global container shipping market as online editor of Port Technology International.

He also explored the initiatives major container ports and terminals have launched in order to ship vital goods across the world without polluting the environment.

Since then, he has reported heavily on the impact made by environmental, social, and governance (ESG) practices on the supply chain of minerals, with a particular focus on rare earth mining in Africa.

As part of this, in 2022 Max visited mines and ports in Angola to hone in on the challenges being faced by one of the world’s biggest producers of rare earth minerals.

His most recent sustainability-related work came much closer to home, as he investigated the eco-challenges faced by independent retailers in the UK, specifically looking at how they can cut emissions and continue to thrive.

Max lives in South London and is an avid reader of books on modern history. He has also recently learned to play the game Mahjong and takes every opportunity to do so. He is also yet to find a sport he doesn’t enjoy watching.

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