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Five common double glazing faults and how to resolve them

31% of the double glazing owners we spoke to had problems after installation

Five common double glazing faults and how to resolve them

Double glazing should last and weather well – that’s what it’s designed for. So encountering problems within the first 10 years of installation is incredibly frustrating, especially if it means your home is less secure until it’s fixed. But nearly a third of the 2,155 people we spoke to were in that situation. 

The most common fault was the windows or doors becoming difficult to open or close (10%). This was followed by them dropping over time so that they don’t fit as well (5%).

While it’s encouraging that 69% of people didn’t experience issues in that time, if you’re someone that has, knowing what you can do to fix it will make it easier to stomach –  read on for our expert advice.

If you’re looking to buy double glazing, visit our guide to the best and worst double glazing companies, where we review national heavyweights in the glazing world Anglian, Everest and Safestyle.  

Top 5 double glazing faults

How to fix double glazing faults

Double glazing being difficult to open or dropping

Difficulties with opening and closing your doors or windows could be down to:

  • the mechanism being stiff (if they’re doors or casement windows that are hinged)
  • the lock/handle catching/being faulty (more on this below)
  • the hinges having moved/become loose.

Try oiling the mechanism, hinges, handles or places where the windows/doors pass the frame (for example, if they’re sash) to see if that will help.

You can also adjust screws to tighten hinges or mechanisms to see if that helps. If you think these need replacing instead, contact the company you bought them from.

It could also be caused by the weather – extreme temperatures may make the frame expand or shrink and therefore not move as smoothly or ‘stick’. This may also be the cause of double glazing dropping.

To fix this, you might be able to wipe down the frames with cold water to help shrink them down slightly – but you don’t want to be doing that regularly.

Woman opening a double glazed sash window

If the problems aren’t too severe, it might be worth waiting until cooler or warmer weather to see if that solves it.

However, if either of these problems are persistent or significantly impact you (for example, actually stopping you from shutting and locking your door), contact the company you bought it from.

Find out more below about how to contact them to get the best result and visit our full guide to your rights with double glazing.


Condensation or ‘steamed up’ glass can appear if there isn’t enough ventilation in a house or room. Even new double glazing can experience issues if this is the case. In fact, in some cases, it can cause it – homes need to ‘breath’ and energy-saving measures can trap all moisture inside.

Make sure you air rooms as much as possible and consider installing ventilation. This could be with air bricks, vents in window and door frames or extractors. Also think about using a dehumidifier. See our full guide to getting rid of condensation for more and read our dehumidifier reviews to find the best.

However, with new double glazing, it shouldn’t steam up within the glass panes. If it does, the seals around the windows or doors are likely to be broken or no longer working properly – read on for more information.

Window and door locks

Handle and lock on a double glazed door with a frame

You could try some of the methods mentioned above, if the fault is to do with heat or the mechanism getting stiff. But if that’s not applicable or doesn’t work, getting it replaced is usually a job that can be done without having to change the entire frame.

Technically, you could try and replace it yourself, depending on the type of lock. But this might affect the seals and is likely to void your warranty. Plus, because locks are crucial for your home’s security, and they shouldn’t fail after a fairly short time, we’d recommend calling the company.

If you need to call in a locksmith as opposed to calling the company, it’s possible that this could void your warranty, so check the terms.

However, as this is likely to be in an emergency situation, for example because it’s the weekend and you can’t lock your home safely, you might be able to argue for a fault goods claim and compensation for the cost of the locksmith.

Visit our guide to claiming for a for a refund, repair or replacement for more details on what exactly to do. You can also find out more about home security, including burglar alarms, in our full guide.

Double glazing seals

You can just leave broken window or door seals, unless they’re causing considerable problems with condensation, drafts or allowing leaks to occur.

If you want to take action, they can sometimes be replaced without the entire window or door being changed. This is easier to do on frames where the seals (also called gaskets) are separate, rather than built into it.

If just the seal on their own can’t be changed, it might be that the glass can be replaced instead of the whole frame as well. The benefit of this over replacing the seals alone is the the gas between the panes, which acts to stop heat from passing through, will be restored.

This is also the case if the entire window is replaced. Either way, contact the company or trader you bought it from a soon as possible.

See our page on common double glazing questions answered to get to the bottom of your questions.

Getting your double glazing fixed

Young woman drinking a cup of tea looking out of a double glazed window

Under the Consumer Rights Act 2015 you’re entitled to have double glazing that is:

  • of satisfactory quality
  • fit for their purpose
  • as described – eg. what you ordered
  • and fitted with reasonable care and skills.

The company you bought it for should, therefore, rectify any problems that are a fault of the windows or doors.

80% of the people who experienced an issue went directly to the company they bought it from to get it resolved. They most commonly did so by phone (45%) and 20% did so in person. Some chose to write to the company (12%), while 2% contacted them by text.

Some people chose to use more than one of these methods. We’d recommend contacting the provider as soon as you notice the issue and doing so by calling or visiting the company, following up with it in writing. This can be done by letter or email, but ideally not text.

Having everything in writing in these forms, including images if applicable, will make things easier if the company isn’t helpful or the problem continues. Preferably, get a confirmation from the company of this and any agreements to fix it, along with a date.

Also take a look at your warranty. Many doubly glazing companies offer 10 or 20 year ones, but some lifetime. Check exactly what it covers and when until, as some only include hardware fixes within one to five years.

Even if the issue occurs after the warranty has run out, you are protected by the consumer rights act. You will need to prove that the fault is because of a defect in the product or the installation, as opposed to wear and tear or something you might have done. It might be worth calling in an independent expert, such as a surveyor, to prove this.

The majority of the people who did get in touch with the company (75%) a resolution was reached.

Our guide to resolving problems with a trader or company gives full details on what you need to do if you hit any problems and take a look at our guide to warranties to understand how they work.

Our research into double glazing

In September 2018, we asked 2,155 Which? members about their experiences with the company they bought and got double glazing installed by in the last 10 years.

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