Double glazing cost in 2026
Windows are the job where quotes vary most, because almost nothing about them is standard. Frame material, glass specification, opening style and the state of what is behind the existing frame all move the number. A three-bed house comes to around £7,500 across twelve windows, but the spread on any single window is wide.
Typical cost
£500 to £1,250
per uPVC casement window, supplied and fitted
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Windows & Doors prices in 2026
| Job | Typical cost | What that covers |
|---|---|---|
| Basic uPVC window | £350 to £520 | White frame with a standard A-rated double glazed unit. |
| uPVC casement window | £500 to £1,250 | The mainstream choice, and the range most quotes sit in. |
| Three-bed house, 12 windows | About £7,500 | uPVC casement throughout. |
| Bay, bow and sash windows | Above casement rates | More material and more installation time than a casement of the same width. |
Ranges, not quotes. Every job is priced on the property, so treat these as the bracket your quotes should land in rather than a figure to hold an installer to.
What shapes your quote
Frame material
White uPVC with standard A-rated glass is the cheapest route to that level of thermal performance. Woodgrain foils, aluminium and timber all cost more.
Opening style
A bay, a bow or a sliding sash is more material and more labour than a casement covering the same opening.
Glass specification
Acoustic, toughened, self-cleaning and triple glazing each step the price up. Compare the U-value across quotes rather than the marketing name.
Access
Upper floors above a conservatory, a flat roof or a steep garden can mean scaffolding, which deserves its own line on the quote.
What is behind the frame
Rotten timber sub-frames or damaged reveals turn a straight swap into remedial work. A survey before the quote is the only way to find out.
Listed and conservation areas
Where the property is listed or sits in a conservation area, style and material can be prescribed. That rules out the cheapest uPVC options and needs consent before work starts.
The rules that apply to glazing
Windows and doors sit outside the energy-saving materials VAT relief that covers solar and heat pumps, so the full 20% applies. Two other rules matter more.
- ✓Replacement windows are controlled work under building regulations, so the installation has to be certified.
- ✓Most installers self-certify through a competent person scheme and register the job, which produces the certificate you will need when you sell.
- ✓The zero VAT rate on energy-saving materials does not extend to glazing.
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Windows & Doors questions, answered
- How much does double glazing cost per window?
- A standard uPVC casement runs about £500 to £1,250 supplied and fitted, and basic units start nearer £350. Bay, bow and sash windows sit above that because of the extra material and labour.
- What does it cost to do a whole house?
- Around £7,500 for a three-bed house with twelve uPVC casement windows. That figure moves quickly with frame material, glazing specification and access.
- Is triple glazing worth the extra?
- It costs more and performs better, but the gain over a modern A-rated double glazed unit is far smaller than the gap between old glazing and new. Compare U-values across quotes rather than the label on the brochure.
- Do I need building regulations approval?
- Replacement windows are controlled work. Most installers register the job through a competent person scheme and issue a certificate, which you will need when you come to sell.
- Can I compare window quotes on WhatDeal?
- Yes. Tell us what needs replacing, and up to three trusted window and door installers quote for the work, with certified installation and the paperwork you need when you sell.
Why window quotes vary so much
Almost nothing about a window job is standard, which is why two quotes for the same house can sit thousands of pounds apart without either being wrong. The count and size of the openings set the base, the opening style moves it, a bay, a bow or a sliding sash is more material and more labour than a casement covering the same width, and the frame material and glass specification stack on top.
The variable nobody can price from the kerb is what is behind the existing frames. Rotten timber sub-frames or damaged reveals turn a straight swap into remedial work, and upper floors above a conservatory or a flat roof can add scaffolding. A proper survey before the final quote is the only way those costs get found before installation day instead of on it.
The paperwork that comes with new windows
Replacement windows are controlled work under building regulations, so every installation has to be certified. In practice most installers self-certify through a competent person scheme, FENSA and Certass are the best known, register the job, and a certificate follows in the post. If an installer is not registered with a scheme, the work needs building control sign-off instead, at extra cost and delay.
That certificate is not bureaucratic decoration: your solicitor will ask for it when you sell, and chasing paperwork for windows fitted years earlier is a miserable errand. So it belongs on your checklist when comparing quotes, alongside the requirement that new glazing must not leave the room ventilated worse than before, which is why many replacement windows now come with trickle vents in the frame.
Choosing glass by numbers, not names
A standard A-rated double glazed unit is the baseline nearly every quote starts from, and it is a high baseline: the leap from tired old glazing to any modern unit dwarfs the differences between modern units. Acoustic glass, toughened panes, self-cleaning coatings and triple glazing each step the price up from there, and each earns its keep only in the right house.
The way to compare is the U-value, the measure of how much heat the window lets through, rather than the marketing name on the brochure. Two quotes at different prices sometimes describe the same glass, and two units with the same label sometimes perform differently. Ask every installer for the U-value of what they are quoting and the comparison becomes honest arithmetic.
Doors, and how they ride along
Doors are usually bought the way they are quoted: alongside the windows, from the same installer, on the same certificate. A front door replacement runs from value uPVC through composite, the mid-market default with an insulated core and a tougher skin, up to timber and aluminium, and patio, French and bi-fold doors follow the same logic of frame, glass and hardware.
The comparison advice is the same as for windows: match specification, not just price. Two composite door quotes can differ on the core, the locking hardware and the glazing around it, and the cheaper one is sometimes the better one. Listing what each quote includes side by side takes ten minutes and settles most of the argument.
Windows & Doors guides & advice
Browse all guides →uPVC, aluminium or timber: choosing window frames honestly
The three window frame materials compared on cost, looks, upkeep and lifespan, and why white uPVC remains the default for most UK homes.
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Double or triple glazing: what the extra pane really buys
Triple glazing beats double on paper, but the gain over a modern A-rated unit is smaller than the sales pitch. When the third pane earns its cost.
Read the guide →
FENSA, Certass and building regs: the window paperwork explained
Replacement windows are controlled work under building regulations. What FENSA and Certass certificates are, and what to do if one is missing.
Read the guide →
How long uPVC windows last, and when misted glass means replacement
uPVC windows typically serve around 20 to 30 years. The signs a window is done, and why misted glass is often repairable rather than terminal.
Read the guide →
Composite or uPVC: choosing a front door that lasts
Composite doors cost more than uPVC and earn it in rigidity, looks and kerb appeal. How the two are built, where each wins, and what to check on any door quote.
Read the guide →
Do replacement windows need planning permission?
Most window replacements need no planning permission. The conservation area and listed building exceptions, and the checks that apply to flats.
Read the guide →
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Prices and grant rules change. Checked August 2026, and worth confirming the grant details on GOV.UK before you commit to anything.