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What to Do About Common Problems With Double Glazed Windows

(4 min read)

While double-glazed windows are incredibly durable, nothing is 100% fault-proof, and a problem may arise post-installation. However, there tend to be very easy solutions to the most common problems, some of which can be completed without the need to call out an engineer.

Difficulty opening

Occasionally, windows and doors may stick and become hard to open. This poses ventilation and security issues, not to mention the possible loss of an emergency escape route. This can be caused by a number of things.

Firstly, it could simply be because of a change in the weather. Warmer weather and the sun directly hitting the windows can cause the uPVC to expand, making less of a gap for the window to open through. While there isn’t necessarily a fix for this other than waiting for it to cool down later, this should only make the windows slightly stiff, and they will still open. If this continues past the hot weather and becomes a more frequent issue, it is worth contacting your window installer as there may be an underlying issue.

The mechanism may be stiff. This often can be resolved by oiling or tightening the mechanism, though this should only be done if you are confident in what you are doing. Overtightening, loosening or using the wrong products could lead to damage which may lead to a costly repair or replacement anyway.


A small amount of condensation on your windows is usually fine; this tends to just be the outside temperature clashing with the inside temperature and will usually disappear within a few hours. This could also be due to a lack of ventilation, in which case opening a window should speed up the process of getting rid of the moisture. You can also have vents installed on older windows to increase ventilation. However, if there is a lot of condensation on the inside of the window, or even between the panes, this can indicate a bigger issue. This could mean that the seals are broken, or aren’t working as they should, and these seals can be replaced without having to replace the entire window. Though, if the seal isn’t the problem and the moisture continues, it may have been a waste of time and money to replace the part when a new window is needed. A proper investigation can rule this out.

Glass units can also be replaced on their own. You would keep your original window frames but gain brand new units which will have the right amount of gas needed between them for proper insulation. This also would need to be done if the units themselves are trapping moisture between the panes. This will normally come from a small hole between the panes, causing gas to leak and moisture to enter in, so this can’t simply be repaired without replacement.

Windows Catching

When opening your windows, they may feel like they are catching on the bottom of the frame. If this is a new installation, the windows may have settled slightly off, and a minor adjustment of the hinges should solve this issue.
If the issue is more severe, like the window cannot open or close without force or at all, then a bigger adjustment may be needed. This, again, could just be resolved by adjusting the hinges. However, there also may be some damage to the hinges, and they might need to be replaced. This is generally easy to do, and the wear can come from standard use, an underlying fault or they might not have been maintained properly.

Replacing the hinges, in this case, should solve the problem, but it may be more cost-effective to have the window replaced entirely, as a new window will come with a new warranty, and any faults with the hinges should be covered for a few years.


Older uPVC windows can succumb to discolouration. White windows may turn an off-white, yellowy tone, and coloured windows might fade. This usually takes a long time but can be accelerated if they are directly facing the sun or cleaned using the wrong cleaners.

The only way to rectify this is to replace the windows. While paints do exist for these issues, an already discoloured window provides a less than ideal base for the paint, and it will likely need topping up more frequently. Plus, discolouration usually indicates a window or door is older than 10 years, so it’s likely they are coming to the end of their lifespan anyway.

To prevent this in your windows, using the correct cleaners and avoiding anything harsh or abrasive will limit the amount of compromise to your uPVC. Obviously, discolouration doesn’t mean that your windows are no longer fit for use, but it can be unsightly and can indicate that they are older and need replacing soon anyway.

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Paul Wallis
Paul Wallis
We recently decided to replace our front door, and could not be happier with the result! Thanks so much to Kate, for her time and understanding. Cannot say enough good things about the installation, and Cameron was tidy and efficient. It's been a pleasure to work with Three Counties recently, doors and windows. Many thanks!
Danielle Horsley
Danielle Horsley
Lovely looking door
Agatha W
Agatha W
Three Counties have been superb, their customer service is great and their workman were polite, cleaned up after themselves and the workmanship is excellent!! I am very pleased with their work and would happily recommend them.
Tom Winter
Tom Winter
Excellent service!! We had 21 windows and 3 doors installed and very happy with it all. The process from start to finish was stress free and Ron and Lee who installed the windows and doors were great. Would definitely recommend!
Phil Redhead
Phil Redhead
Just had my tatty old windows replaced by Three Counties, and it’s been a highly professional job from start to finish. Communication from the administration team was prompt and courteous at all times, and installation ended up being much quicker than advertised projections. Installation was without issue and the lads who did the work were amenable to my requirements and did an excellent job. Very happy with the entire process. Three Counties were recommended to me by friends and I can certainly now recommend them to others.
Mark Boyce
Mark Boyce
Bought two new windows and a new front door from Three Counties, was very impressed with the attitude of all staff, who were friendly and informative. Price was good, and installation completed without a hitch - very happy with the final product, and would definitely use again.
Paul Picknett
Paul Picknett
We have just had all our windows (18) replaced, french doors (20 and side panels (2) by Three Counties. We could not be more pleased with their workmanship and the finished product. They left the property incredibly clean after each day, and this despite the messy nature of ripping out old windows and frames. We were kept informed at each stage and a minor snagging issue was resolved promptly and efficiently after installation. A first class service. We would not hesitate to recommend Three Counties.
Anna Trevelyan
Anna Trevelyan
Three Counties have now installed several windows and doors on our house and they're always my go-to company. I used another before I discovered them and they let me down, but I absolutely cannot fault Three Counties. From the moment you contact them they're courteous and professional, and they keep in touch with timescales and installation times. Friendly installers too, who go above and beyond. You'd think all this great service would cost more but they beat other companies on price. Highly recommended and trusted, I'd never go anywhere else now.