When to replace your windows

• Double glazed windows last 25 to 30 years on average
• Draughts, noise and warped frames are all signs that it’s time to replace your windows
• Scrappage schemes, financing and grants can help you cover the cost

Knowing when to replace double glazing is sometimes easy, for example when the glass is broken. Other signs are less obvious – but they could be costing you dear.

Old and worn-out windows may still look fine, but they don’t insulate or protect your home as well as they should. Replacing your double glazing will improve your security, cut your heating bills and even improve your family’s health.

But with double glazing costing around £10,000-£15,000 for a three-bedroom house, it’s a hefty investment and a big decision. Below we’ll reveal whether it’s more cost-effective to replace one, some or all of your windows, or even opt for a repair.

To cut straight to double glazing quotes, add a few details to this form and we’ll ask our hand-picked selection of window installers to be in touch with a tailored estimate.

How often should I replace my windows?

A window’s lifespan depends on many things including materials, installation quality and exposure to the elements.

Single glazed windows break much more easily than double glazed windows, and they need replacing after 15 to 20 years on average.

Double glazing is more robust. The inert gas between the two panes (or three panes in a triple glazed window) creates a pressure vacuum that makes the glass much less liable to break.

Double glazed windows last an average 25 to 30 years. The best double glazing companies guarantee their windows for 10 to 20 years, but they can perform well for as long as 50 years if they’re well maintained and relatively sheltered from wind and rain.

However, double glazing has its own vulnerabilities. Seals can crack and detach, and uPVC frames can warp when temperatures go up and down. Once this starts to happen, it may be time for an upgrade.

Can I replace one window at a time?

Yes, you could cut costs in the short term by replacing just the problem window, but it makes sense to replace all your windows at once. Here’s why:

• Double glazing companies charge less per window when installing multiple windows, so you effectively get a bulk discount
• Your windows are probably all around the same age, so if one window develops problems the others may soon follow soon
• Having all your windows done at once means less disruption to your home
• Replacing all your windows together makes your home look more attractive – and will increase its value.

To spread the cost of a full replacement, Anglian suggests doing it in two stages: “Replacing the windows at the front or back of your house is a good alternative.”

Can I repair double glazed windows instead of replacing them?

Some problems can be fixed without replacing the window, at least in the short term. For instance, failed seals are much cheaper to upgrade than entire windows, and misted double glazing units can be replaced.

According to Check-a-Trade, a window seal replacement costs from £125 to £180 depending on window size. A window frame repair costs from £170 to £300 for uPVC, but refurbishing a sash window can cost £800 or more.

A good window installer will discuss repair options with you. To chat to someone, fill in our double glazing quotes form and we’ll ask selected companies to get in touch.

How much does it cost to replace windows?

Double glazing costs vary widely. The main factor is the window frame material, from the cheapest uPVC to the most expensive timber.

According to the Federation of Master Builders, uPVC starts at around £500 per window and should last at least 20 years. Aluminium double glazed windows start at £1,000 and can last 45 years, while timber double glazed windows cost from around £1,500 and can last many decades.

To replace all the windows on an average terraced house, Check-a-Trade estimates a cost of £5,000-£7,000. The Federation of Master Builders puts it at up to £8,000 for uPVC, up to £13,150 for aluminium and up to £18,150 for timber.

Can I get help to replace my double glazing?

Government grants for double glazing are less generous than grants for renewables such as air source heat pumps and solar panels.

If you are on a low income you may qualify for help from schemes such as ECO4 and the Home Energy Scotland Loan. The best double glazing companies will find grants you’re entitled to, and help you apply.

The best way to cut the cost is to recycle your old windows. Anglian will shave up to about £1,000 off the cost of installing new windows and doors if they can recycle your old ones under the Anglian Scrappage Scheme.

It’s also worth looking at double glazing finance to spread the cost. At time of writing (October 2024), companies including Anglian, Everest and Safestyle offer credit terms at around 12.9% APR over 36 months.

Summary

• Double glazed windows last 25 to 30 years on average
• Draughts, noise and warped frames are all signs that it’s time to replace your double glazing
• Timber windows generally last longer than aluminium or uPVC, but uPVC is cheapest to replace
• You can save money by opting for repair or single window replacement, but these are short term fixes
• Scrappage schemes, double glazing finance and government grants can help you cover the cost