There are three different jobs hiding under this heading, and they cost very differently. You can swap failed sealed units inside frames that are still sound, replace individual windows, or renew a whole house. For double glazing replacement the typical range runs from about £150 for a few units to £11,000 for a whole house, and the first question is always whether the frames can stay.
Typical double glazing replacement prices
Typical double glazing replacement costs in Hampshire, supplied and fitted
| Job size | What it usually covers | Typical cost |
|---|---|---|
| Small | A few sealed units replaced in sound frames | £150–£600 |
| Typical | Three to five complete windows | £1,500–£4,000 |
| Large | Whole house, including modern energy-rated glazing | £4,000–£11,000 |
Route one: new units in the old frames
A sealed unit is the sandwich of two panes and a spacer. When the seal fails, moisture gets between the panes and the glass looks misted. The unit can be swapped without touching the frame, which makes it the cheapest fix by a wide margin. It only makes sense if the frame is straight, the hinges work and the seals are in decent shape. A ten-year-old uPVC window with one misted pane is the classic case.
The price depends on the size of each unit and on whether the glass is special, such as laminated or obscure. Small jobs can carry a minimum call-out charge, so ask the installer to quote a group of units together. Some companies measure and make the units, and others will only fit units you supply. Our guide to misted, draughty and failed double glazing covers how to tell which route fits.
Route two: replacing whole windows
When the frame is the problem, the glass goes with it. Common signs are warped sashes, sagging casements, cold bridging at the corners and hardware you can no longer buy. A new window brings modern low-emissivity glass and better draught sealing, and that is what makes it a better fit than patching an old one.
What changes the price
- Unit size and thickness. Larger panes cost more, and 28mm or thicker units for better insulation cost more again.
- Glass type. Low-E coatings, argon fill, laminated and acoustic glass all add cost.
- Frame material for full replacement. See our guides for casement and sash windows.
- Number of units. Fitting costs are shared across the order.
- Disposal. Old units, especially large ones, often come with a charge.
- Access. Upper floors and tight spaces add time.
What suits Hampshire housing
A lot of the county's housing was glazed in the 1980s and 1990s, from the overspill estates around Basingstoke and Andover to the suburbs of Southampton, Portsmouth and Fareham. Units from that period are now at the age where seals fail. Some frames still have years left, and some have not. A surveyor or a candid installer will check the frame before offering to replace only the glass, and a company that always recommends replacing everything is worth questioning.
If your windows were fitted with a guarantee, a failed unit may still be covered. Look for the paperwork before paying for a replacement. The installer may have gone, but the guarantee can sometimes be honoured by an insurance-backed scheme.
Checks before you commit
- Whether the quote covers units only or complete windows
- The glass specification, including any low-E coating and gas fill
- Competent person scheme sign-off, such as FENSA, if you are replacing windows
- How long the new units are guaranteed and whether the guarantee covers the seal
The cost calculator shows how the three routes compare for a house of your size. If you are not sure the windows need replacing at all, our casement window cost guide covers the main alternative.
Frequently asked questions
How much does it cost to replace a misted double glazing unit?
As a guide, replacing a few sealed units in sound frames costs about £150–£600, depending on size and glass type. Small jobs may carry a minimum charge.
Is it cheaper to replace the glass or the whole window?
The glass, if the frame is sound. If the frame is warped, rotten or draughty, new units in it will not solve the real problem.
How long does double glazing replacement take?
Replacing sealed units can take as little as a couple of hours, while a whole-house window replacement typically takes one to three days.
Do new units make a big difference to heating bills?
If your existing glass is failed or very old, usually yes, because modern units with a low-E coating and gas fill insulate better. The difference is smaller if the old units are in good order.
Ready to talk to a double glazing replacement specialist?
Get Free Quotes →