Whether you’re moving into a new home in Leicester, or starting to think your existing home might have a problem with its double glazed windows or doors, it’s important to check for signs of double glazing failure.

Double glazing is generally designed to last 20-35 years, sometimes a little longer.

But maintaining their longevity is dependent on ensuring correct installation to start with, and proper maintenance thereafter.

It is therefore important to ensure that, when choosing a company to fit your new windows or doors, that you choose one that is reputable.

If you do think your double glazing is starting to have problems – don’t worry – in this article we will look at common signs of double glazing failure, some solutions, and at what point you might want to consider replacement double glazing.

We will take a deep-dive look into some common signs that your double glazing could be failing, including:

  • Condensation
  • Leaks
  • Scratches, cracks or chips
  • Draughts

Let’s get right into looking at the signs and some solutions to potential double glazing failure.


Condensation often forms on double glazing in the cooler months. It can cause alarm at first sight, with many thinking that there’s something wrong with their double glazing.

In actual fact, condensation is usually normal behaviour and shouldn’t be a cause for concern, as long as it is on the outside or inside of the glass, and not within the unit.

Nonetheless, no-one wants their windows to be covered in condensation. To help alleviate the problem, there are some remedies.

Condensation on the inside

For condensation that is inside the home, you can try improving ventilation throughout the property. Should this not help, or your home is prone to condensation, a dehumidifier will help to reduce the humidity of your property.

Condensation on the outside

For condensation on the outside, this is a tell-tale sign that the double glazing is working as it should, and as purely the difference in temperature between the outside and the window reacting. It shows that the window is helping to retain the heat inside your home.

Condensation between double glazing panes

If, however, the condensation is forming within the double glazed unit itself (between the panes), this is the point at which you should consider replacement double glazing. This often means that the seal has broken or sprung a leak.

We have put together a more in-depth article on double glazing condensation should you wish to find out more.


Have you found water leaking in through your windows?

Whilst windows are equipped with features to prevent water leaking in, sometimes these features can fail, resulting in water leaking into the property.

If you take a look at where the water appears to be coming from, and it looks as if it’s coming via the window frame itself, then it’s possible that the weather seals have broken or that some debris is blocking the drainage section.

If it looks to be the drainage section being blocked by debris, then cleaning it out should do the trick.

However, if it looks like the weather seals have failed, then the seals will need replacing. We would recommend contacting a window company, such as ourselves, to look at repairing this.

In more severe cases, the sealant between the frame and the aperture could fail. This can result in watering seeping through the gaps. If this appears to be the case, it is important to contact a double glazing specialist to have this resolved as soon as possible, otherwise the water ingress could end up damaging the surrounding walls and plaster.

Scratches, cracks or chips

As careful as you may be, sometimes glass just ends up getting damaged, resulting in all sorts of problems, from basic scratches, through to chips, or even cracks.

If the glass of your window has a scratch, this can sometimes be buffed out, assuming it’s not too deep. You can find tips for buffing glass here.

On the other hand, cracks and chips are a bit more troublesome.

Sometimes, chips may not cause any negative impact, as long as they aren’t too deep.

But if the cracks or chips penetrate the frame or the glass, it could cause problems. You may experience more condensation, draughts from the window, or reduce the overall energy efficiency of the window, potentially resulting in higher energy bills.

In most cases, a replacement window is likely to be needed if you have a deep penetrating chip or crack. At this point, it is recommended to contact a local window installer.


Draughts can be a nuisance. Whether you’re sitting watching TV, or trying to read a book, noticing a draught can be a distraction.

Assuming all of your windows and doors are shut, and there’s no electrical item creating a flow of air, draughts can be a sign of a problem with your double glazing.

It often can mean a seal within the window or door has failed.

To help diagnose the problem further, you will need to figure out from what part the draught is coming from.

To begin, feel around the brickwork where it joins the window frame. If you can feel the draught there, it’s possible the sealant has failed and will need resealing.

If this isn’t the case, it’s possible the draught could be coming from the glass and in between the frame. Like with the leaking discussed previously, this can mean the weather seal has failed, and as such, could also allow water ingress in the future. It’s a good idea to get this checked out by a local firm who can inspect the problem and replace the weather seal.

When is a replacement recommended?

Whilst we have spoken about some common problems and their remedies, sometimes a replacement really is the only option.

This can be the case when the frame that holds the double glazing unit is too old, meaning that it couldn’t support a new unit. At this point, a replacement frame is recommended.

In other cases, such as if the frame has been penetrated deeply, a replacement is also recommended.

For problems such as seals failing, replacement generally isn’t required, as they can often be replaced.

If you have come to the conclusion that your double glazing needs replacing, or that you’re still not sure what the problem is, get in touch with us today. With over 15 years of experience in double glazing across Leicestershire, we’re sure we can help diagnose the problem and find a suitable solution.