How much does blown window repair cost in 2025?

Spotted mist or condensation between the panes of your double glazed windows? That’s a sign of a blown window – also known as failed double glazing.

Blown windows aren’t just an issue from an aesthetic point of view – they’re also a problem for your home’s energy efficiency and could cause your bills to rocket.

So, you’ll want to get the issue fixed sooner rather than later. Here, we’ll reveal the average blown window repair cost and the different factors to consider. But first…

What is a blown window?

A blown window occurs when a gap appears between the panes of your double (or triple) glazed windows – often due to damaged sealant or damage to one of the panes of glass itself.

This allows moisture to get into the window unit, which can then cause it to mist up or take on a cloudy appearance.

Not only can blown windows make it hard to see out, but they can also lead to damp, reduce your home’s energy efficiency and even let in more noise from outside.

What causes blown windows?

Some common causes of blown windows are:

• Windows that were installed poorly
• Damaged window seals due to wear and tear or accidental damage
• Old windows that have deteriorated over time
• Using harsh chemicals to clean windows

A blown window can also be a sign that the glass has weakened, which could pose a security risk for your home.

How much does blown window repair cost in the UK?

Some companies can fix your blown windows by removing moisture and resealing the window.

However, usually, the most cost-effective way to repair a blown window is to replace the double glazed unit (leaving the window frame in place).

Depending on the extent of the damage, you may be able to replace just a single pane of glass – which generally costs somewhere around £55 to £145 per pane.

Alternatively, if you need to replace the glazing for a whole window, costs range from £100 for a small window up to around £850 for a large bay window.

Misted window repair cost for a single pane

Replacing a single pane is the most cost-effective option – but it’s only possible if the damage isn’t far-reaching.

• Replacing a 200mm x 400mm pane of glass costs around £55
• For a 500mm x 700mm blown window pane, the cost is about £74
• You’re looking at a cost of about £117 to replace a pane of 800mm x 1,000mm
• For a 900mm x 1,200mm pane of glass, the cost will be around £145 per pane

Whole window blown double glazing repair cost

If your whole window is affected, your costs will be higher. The main factor that will impact how much you pay is the size of your window.

• Replacing the double glazed unit in a small blown window will cost around £100 to £200
• If it’s a standard-sized window, costs range from around £200 to £325
• To repair a large blown window you’re looking at a price tag of £350 to £850

Additional double glazing condensation repair costs

Occasionally, you’ll face additional costs when getting your blown window repaired.

For instance, if your window is in bad condition, it may be a good opportunity to replace the whole window (including the frames) – rather than just the double glazed unit.

Often, additional costs like these will be included in your overall quotes from local double glazing specialists – but it’s always worth checking.

• A new window frame can cost anywhere from £250 to £1,500 each, providing a smart and longlasting finish
• Finishing trims for a window will typically cost £6 to £26 per m², providing a polished look while helping to seal any gaps
• New sealant costs around £5 per 100ml and is essential for sealing your new double glazing
• New window handles cost roughly £5 to £20 each – a small price to pay for a big improvement in your home security
• Removing a blown window costs around £140 to £400 per window but will be necessary if you decide a full window replacement is the way to go

If you’re looking to replace all of the double glazing in your home, check out our double glazing cost guide.

Or, if you need other work carried out to your windows, head over to our related guides:

• Window frame repair costs 
• Window glass replacement costs 
• Window fitting costs

Get a quote for double glazing repair cost near me

Every project is unique. So, the best way to get an accurate blown window repair cost for your needs is to reach out to local double glazing specialists near you.

They’ll be able to assess your windows and advise you on the best fix for the problem before providing a bespoke quote for your needs.

Factors affecting blown window repair costs

There are lots of different factors that can affect how much it costs to replace a blown double glazed window.

Here are the main ones to bear in mind.

Size and style of window

The larger your window, the more double glazing it will require, and the higher your costs will be.

Similarly, larger window styles with more panes of glass will usually cost more to repair – such as bay windows.

Extent of damage

If only a small area is affected, you may be able to replace just a single pane.

However, if the problem affects several panes, your costs will be higher.

Similarly, if your window frame itself is damaged, you may need to consider a whole window replacement, which will push your costs up further.

Type of glazing

There are lots of different types of glazing available, including toughened, frosted, and self-cleaning – all with different prices

Triple glazing will also cost more than double glazing.

Additional work and materials

Depending on the condition of your windows, you may need to pay extra for additional prep work or structural repairs.

Likewise, any additional materials that are needed to repair your blown windows will come at an additional cost.

Where you live

Lastly, labour prices can vary widely across the UK. For instance, costs tend to be higher in the south of the country and in big cities like London.

Accessibility can also be a factor.

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Blown window repair vs full window replacement: which is better?

Most of the time, you won’t need to fully replace a blown window.

Rather, you’ll be able to get away with just replacing the double glazed unit, which will cost significantly less.

However, in some cases, it might be worth considering a full window replacement.

For instance…

• Your window is structurally damaged
• Your windows are old (over 15 years)
• They’re difficult to open
• You don’t like the way they look
• Your window frames are soft

Ultimately, if your windows are likely to need replacing in the next couple of years, you might as well do it now.

This will save you money in the long run as you won’t be forking out on replacing the double glazed unit only to replace the whole window just a little while down the line.

If you’re not sure whether to opt for a repair or full window replacement, talk to your double glazing specialist. They’ll be able to advise you on the condition of your windows and walk you through your options.

How to prevent blown windows

As we all know, prevention is better than cure!

Taking some small steps to prevent blown windows could save you the cost of blown window repair – or, if you’ve just repaired your blown windows, prevent the problem from reoccurring.

• Check the sealant and caulking regularly for gaps and cracks
• Caulk around the edges and fill any cracks with silicone sealant (or get a professional to do it for you)
• Keep your windows clean by washing them at least every six months
• Avoid using harsh cleaning chemicals

If you’re investing in new windows or in a blown window repair, it’s also vital to ensure proper installation.

If your windows aren’t installed properly, this can lead to gaps forming between the double glazing – and the last thing you want is for your new double glazing to blow!

Hence the importance of hiring a qualified, FENSA-registered expert for the job. Which brings us onto…

Find the best double glazing experts near you

Ready to find a double glazing expert for blown window repair?

Fortunately, you’re in the right place!

All our tradespeople have to pass up to 12 rigorous checks to get listed on our directory – so you can be confident that you’re hiring a skilled person for the job.

In fact, we’re so confident in the quality of the trades on Checkatrade that if you book through us, we guarantee their work up to £1,000 (guaranteed for 12 months – eligibility and T&Cs apply).

Enter your postcode in the box below to browse approved tradespeople near you.

FAQs

Can blown windows be fixed?

Yes! Fixing a blown window is usually straightforward and involves replacing the double-glazed unit.

Here are the steps involved:

• An initial inspection to identify the extent of the blown windows
• Removal of affected double glazed units
• Installation of new double glazed units
• Final checks to ensure that the new double glazing is fitted and sealed properly

What is the average cost of repairing blown double glazing in the UK?

The average cost of repairing blown double glazing in the UK can range from £55 if just a small area is affected, to £600 if the problem affects a whole large window.

Can I fix a blown window myself?

While it is technically possible to fix a blown window yourself, we wouldn’t recommend it.

Fixing blown double glazing requires specialist knowledge and tools to carry out the work safely and efficiently – and to prevent the problem from reoccurring.

That’s why we always recommend hiring a local double glazing expert. An experienced tradesperson will know exactly how to fix a blown window in a way that will stand the test of time.

How long does it take to repair a blown window?

It shouldn’t usually take more than a few hours to replace a single blown double-glazed unit.

However, if you need to repair multiple blown windows, this could take longer.

Is blown double glazing covered by insurance?

Whether blown windows are covered by insurance will depend on your specific policy. However, often, it will depend on the cause. Most insurance companies won’t pay out if the seal is broken and the glass is intact unless it specifically says so in your policy.

What are the signs of a blown window?

Signs of a blown window can include internal condensation, cloudy windows, higher-than-usual heating bills and increased noise penetration.

How do I prevent condensation inside double glazing?

To prevent condensation inside double glazing, you should check that your windows are sealed tightly and fill any cracks with silicone sealant. It’s also helpful to keep your windows clean, but avoid using harsh cleaning chemicals as this can cause blown windows.

Should I repair or replace misted double glazing?

Some companies can repair misted double glazing by removing any moisture and resealing the window. However, usually, the most effective and cost-efficient way to repair misted double glazing is to replace the double glazed unit (note that this doesn’t normally mean replacing your whole window!).

Can blown windows impact my energy bills?

Yes! Blown windows will impact your home’s energy efficiency, which will cause your energy bills to rise. In fact, an unexpected increase in your energy bills can be one of the signs of a blown window.

Is it worth replacing blown double glazing?

Yes! Blown double glazing doesn’t just look bad. It can also cause problems in the home, from dampness to reduced energy efficiency and even increased noise penetration. With that in mind, it’s important to replace blown double glazing as soon as you can.