When should I replace my old double glazing?

2 Aug 2023

Double glazing has a lifespan 15-20 years. Is is time to replace yours?

Double glazing has a lifespan 15-20 years. This can vary depending on the materials used, insulation, maintenance and weather conditions. Even if yours is showing no visible signs of age, it could be contributing to your energy bills. Seals can fail on old double glazing which means they will not be as energy efficient. The double glazing industry has seen huge advances in technology and thermal performance in the last 20 years, making it well worth the investment in your home.

Signs it’s time to replace your double glazing:

Visible Damage

Cracked or rotten window frames are not only unsightly, but they could be damaging your home. When windows don’t insulate your home properly, mould and damp can form.


If you can feel drafts around your windows they are not working efficiently and it is a sign the seals may have failed. They will certainly be letting warm air out and cold air in which will contribute to higher energy bills.


Condensation on the inside of your windows means there is a ventilation issue. Newer double glazing can solve this. If the condensation is between the two panes of glass, it means the double glazing has failed and the windows will not be insulating your home.

UV Damage

If you notice your furniture or textiles have faded, it’s time to swap for new glazing. Modern glazing has UV protection which helps to stop the sun from damaging your furniture.


If the outside noise is coming inside loud and clear your windows are not as effective as they should be and it’s time for an upgrade.


If your windows are not opening or closing properly it can pose a security and safety risk, not to mention a daily annoyance.

Benefits of new double glazing

  • Cuts heat exchange by 50%

  • Energy efficient

  • Lower heating bills

  • Increase insulation by 40%

  • Security

  • Noise Reduction

  • Increase Property Value

  • Safety

  • Easy Maintenance

  • UV Protection

  • Kerb Appeal

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What to look for in a window fitter

Windows fitted incorrectly can cause structural damage to your home which is both costly and time consuming to repair. It is important that you choose a window fitter who is qualified, certified, and experienced.

Building regulations and legislation must be met when fitting new windows so ensure your window fitter is knowledgeable.

Always get three quotes and ensure they are like for like.

Here are a few tips when looking for a window fitter…

Check Reviews

“You’re only as good as your last job”. Reviews will certainly tell you if the last job was good. Word of mouth recommendations are always great for any home improvements, but make sure you do your own research too.


Make sure your window fitter has relevant experience to what you need from them. For example if you have structural bay windows, check their experience and knowledge in this area.


Window fitters should be registered with government authorised schemes such as FENSA or CERTASS. FENSA and CERTASS monitor building regulation compliance for replacement windows and doors.

If the window fitters are not registered you will need building control to sign off on the installation of your doors and windows. You will incur an additional cost for this.

Windows that have been replaced since 1st April 2002 must be supported by a FENSA certificate or a building regulations certificate, to show that they legally comply with building regulations.


Check your builder is registered with services such as The Consumer Protection Association. This way any deposits you pay are protected, and the window fitter will have an insurance backed guarantee which protects you should the company go into liquidation.

It’s important to note that most home insurance companies will not cover any structural damage to your home caused by new window installation. That’s why it is vital to use a reputable fitter who knows what they are doing.


Check out their website and Facebook page for examples of their work. You should also read testimonials.

Questions to ask a window fitter

  • Who is doing the work?

  • Is scaffolding included in the quote?

  • Will you be removing and disposing of the old windows?

  • What energy rating are the windows?

  • Will they plaster around windows after fitting?

  • Will they provide a Fensa certificate?

  • Is any of the work they need to do structural?

  • What warranty do they provide?

  • What insurance do they have?

  • How long will the job take?


It’s not too hard to assess if you need to replace your old double glazing. And if you do, there are many benefits to the modern standards of glazing. Ensure you do your research and use a reputable fitter to avoid any issues further down the line. The CPA boasts a long list of vetted and reputable tradespeople, so get in touch with a member today if you’d like to start the process off right.