Double glazing near me: how to choose a window installer in 2026 (UK)
Search “double glazing near me” and you get big-brand advertisers next to local fitters, with no way to compare on quality. Replacing windows is notified work under the Building Regulations, so the installer must be able to self-certify or get council sign-off — which makes the ranking beside the point. What matters is a short set of checks: FENSA or CERTASS registration, an insurance-backed guarantee, honest energy ratings, and a written, measured quote. Get those right and the search order does not matter.
- Check registration: FENSA or CERTASS (Competent Person Scheme); GGF membership as a quality signal
- Typical 2026 rate: £450–£900 per uPVC window supplied and fitted; £5,000–£9,000 for a typical whole-house job
- Always compare: three written quotes, like for like
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Why we do not publish a “top 10 double glazing firms” list
A national ranking of window companies is close to useless for your project. A conservation-area sash replacement is a different job from a run of uPVC casements on a 1990s semi, and the best firm for one may not even quote for the other. The salesman’s brand recognition tells you nothing about the fitter who turns up.
The method, though, works for every job. If you can confirm FENSA or CERTASS registration, read the guarantee, understand the energy rating and compare measured quotes, you can judge any window installer — national advertiser or local independent alike.
The accreditations that actually matter
Replacement windows are “notifiable” under the Building Regulations, so the installer must either be in a Competent Person Scheme or get the council to inspect. These are the credentials worth insisting on.
Verify the card, not the logo
A FENSA or CERTASS logo on a brochure is not proof of current membership. Check the installer on the FENSA or CERTASS “find an installer” directory, and confirm the guarantee is insurance-backed in writing. A legitimate firm will give you the certificate details before you sign anything.
What window installers charge in 2026
Double glazing is priced per window plus the frame material, glass spec and access. The figures below are indicative UK ranges for 2026, supplied and fitted with the old units removed; sash, aluminium and bespoke shapes cost more.
For a full breakdown of window costs, see our cost guides.
How to compare quotes without comparing apples and oranges
Window quotes vary wildly because firms use different frame profiles, glass specs and sales tactics. Level them up before you judge on price — and never accept a “today only” discount.
- Insist on it in writing. A doorstep verbal figure is a negotiating tactic, not a quote.
- Check the frame profile, glass and energy rating. A cheaper quote may drop to a lower spec.
- Ask whether it is a quote or an estimate. Rotten sub-frames or lintels can change it.
- Confirm VAT, the guarantee and the IBG. Make sure the guarantee is insurance-backed.
- Match the finish and hardware. Colour, trickle vents, locks and glass (obscure, toughened, acoustic) all move the price.
Questions worth asking before you book
About the business
Are you FENSA or CERTASS registered, and can I check you on the directory? Is the guarantee insurance-backed and how long? Do you use employed fitters or subcontractors? Are you GGF members?
About the job
What frame profile and energy rating are you quoting? Is the glass toughened where the regs require it? Are trickle vents included? Do you make good the plaster and render, and remove the old windows?
Red flags to walk away from
- Cash only, no paperwork. No FENSA/CERTASS certificate, no written guarantee.
- Large deposit up front. Windows are made to order, so a deposit is normal — but keep it protected and not the whole price.
- Pressure to decide today. The classic “sign tonight for half price” pitch is the biggest warning sign in this trade.
- No Building Regs certificate promised. Without FENSA/CERTASS self-certification or council sign-off, you may struggle to sell the house.
uPVC, timber or aluminium — and the sales pitch to ignore
Double glazing is notorious for high-pressure selling: a “manager’s special” price that halves if you sign that evening. Treat any such offer as a reason to walk away, not a bargain. A fair price is a fair price next week too. The most reliable route is three measured quotes from FENSA or CERTASS installers on the same specification, taken calmly.
On frames, uPVC is the cheapest and lowest-maintenance and suits most homes; aluminium offers slimmer sightlines and strength at a premium; timber or timber-look uPVC often suits period and conservation-area properties, where planning rules may dictate the style. If you live in a conservation area or a listed building, check what is permitted before you order — the wrong window can mean an enforcement notice. A good local installer will know your area’s rules and steer you correctly.
FAQs: finding a good window installer in the UK (2026)
Do window installers need to be FENSA or CERTASS registered?
Replacement windows are notifiable under the Building Regulations, so the installer must either be in a Competent Person Scheme such as FENSA or CERTASS and self-certify, or arrange council inspection. Registration lets them issue the certificate you need when selling the property, so always confirm it.
How much does double glazing cost in 2026?
A uPVC casement window is roughly £400–£950 supplied and fitted, sash windows more, and a whole-house uPVC job of 8–10 windows typically £5,000–£12,000. Aluminium and bespoke frames cost more, and London prices sit at the top of each range.
What is an insurance-backed guarantee and do I need one?
An insurance-backed guarantee (IBG) protects your window guarantee if the installer stops trading, which is why it matters — a normal guarantee is worthless if the firm folds. It is usually provided through FENSA, CERTASS or the GGF. Get confirmation in writing before you pay.
Why are double glazing salespeople so pushy about signing today?
The “sign tonight for half price” pitch is a sales tactic, not a real discount. A fair price stands next week. Ignore time-limited doorstep offers, take three measured quotes from FENSA/CERTASS installers on the same spec, and decide in your own time.
Do I need planning permission for new windows?
Usually not — like-for-like replacements are normally permitted development. But conservation areas and listed buildings often restrict the style, material and glazing, and can require permission. Check with your local authority, or use an installer who knows your area’s rules, before ordering.
How long does double glazing last and what guarantee should I get?
Quality uPVC double glazing typically lasts 20–30 years, with sealed units sometimes needing replacement sooner if they mist up. Look for a written guarantee of 10 years or more, backed by an insurance-backed guarantee so it survives the installer.
Compare real window installers, on your actual home
Forget the doorstep pitch and the search ranking. Tell us your windows and we will match you with vetted, FENSA/CERTASS-registered local installers who can measure and quote on the real job — so you compare three prices side by side.