- We researched over 200 of the UK’s FENSA-certified double glazing companies
- We rated the best seven firms against 11 key criteria
- Criteria included warranties, accreditation and reviews from real customers
- Read our guide before choosing the best double glazing company for your home
Double glazing is one of the best ways to improve your home’s energy efficiency and cut your energy bills. But as our article on double glazing prices reveals, it costs upwards of £10,000 to replace all the windows on a typical house, so you’ll want to hire the best company for the job.
To help you get your money’s worth, we set out to find the best double glazing companies in the UK. After analysing current information about hundreds of firms, including big names such as Everest, Anglian and Safestyle as well as dozens of regional providers, we chose the best seven. We review them below.
We prioritised installers certified by FENSA (Fenestration Self-Assessment Scheme) and the BFRC (British Fenestration Rating Council), but our judging criteria also included warranties, choice of windows and other products, experience and customer service. Crucially, all the companies in our list below receive good feedback from customers.
See our methodology for more information on how we selected companies for our rundown.
Ready to collect a few quotes now? Fill in our form, and our hand-picked selection of double glazing installers will be in touch with a tailored estimate.
The best double glazing companies at a glance
Here’s a quick look at how the UK’s seven best double glazing installers compare on window guarantees, experience and geographical coverage.
| Double glazing company | Guarantee | Founded | Area covered |
|---|---|---|---|
| Anglian | 10 years | 1966 | Mainland UK |
| Everest | 10 – 20 years | 1965 | Mainland UK |
| Safestyle | 10 – 15 years | 1992 | Mainland UK |
| First Home Improvements | 12 years | Early 1970’s | UK |
| Britelite Windows | 10 years | 1970 | UK |
| CR Smith | 10 years | 1917 (glazing since 1970s) | Scotland |
| Clearview Home Improvements | 20 years | 2008 | North West |
What happened to Safestyle and Everest?
The past year has seen big changes at the top of the double glazing tree. Safestyle went into administration in October 2023, followed by Everest in April 2024. The brands and customer lists of both were bought by Anglian.
Everest, Safestyle and Anglian all still trade as separate brands, but they have the same parent company – Anglian Home Improvements (ASHI Group Ltd) – and share the same office in Norwich.
What does this mean for you? On the surface, not a lot. The only obvious development is that the three companies now offer the same financing options. You’re even greeted by an identical chat assistant on their Finance pages.
Anglian has worked to honour the orders of existing customers where possible. It does mean that warranties from previous Safestyle and Everest may not be valid, although as long as your installation was registered with FENSA you’ll still have recourse to an insurance-backed guarantee.
The three companies still have their own websites, product ranges, prices, accreditations and installers. However, we will keep a close eye on their customer feedback to ensure they’re keeping up more than just appearances.
Best choice of windows: Anglian
Anglian is now the dominant firm in doubling glazing in the UK, so it’s no surprise to find it offering the best range of windows we came across when researching this article. If you’re keen to upgrade your beloved sash windows or unusual wood frames with made-to-measure timber, uPVC or aluminium replacements, this is the company to try first.
Anglian Home Improvements, to give it its full name, launched just after Everest in 1966 and offers all the standard window types including casement, bay, tilt & turn and sash. You can also opt for custom shapes; etched and obscure glass in assorted designs; and cottage windows that meet tight rules in conservation areas and listed buildings. Anglian even lets you order bespoke blinds to match your windows.
The website has some excellent free tools to help you visualise various window types on your home, plus an inspiration gallery and guide to home renovation. Anglian’s site is less transparent on pricing than Everest’s, and its timber frames can get very pricey, but its quotes are said by some customers to match or undercut other companies.
The company receives a slightly mixed score of 3.9 from customers on Trustpilot, although they have a huge volume of reviews – nearly 34,000 at the time of writing, with 58% at the maximum five stars. Recent reviews include a large number of happy customers as well as some with concerns about customer service or the sales approach.
- Huge range of window styles and materials means you will find the ideal fit for your home
- Prices more affordable than Everest, except for timber frames
- Higher than average number of accreditations including FENSA, GGF and TrustMark
- Giant company, likely to be around for a long time – which is reassuring if you take out finance
- Customers often cite poor communication and aftercare, which may be a side effect of the company's large size
- Prices broadly similar to rivals but timber frames are expensive
What Anglian’s customers say
“They gave the best quote of five other companies, and one company couldn’t even match Anglian before they made some discounts. They fitted two weeks ahead of schedule and the installer knew exactly what he was doing” – Martin Spaven, August 2024
“I had some issues to manage as windows were going in a new hipped roof, but Anglian bent over backwards to be flexible and work around the roofer. The windows were installed to a high standard and look very good” – Claire Briault, August 2024
Best one-stop shop: Everest
“Fit the best: Everest!” went the legendary 1980s TV advert that made Everest the best-known double glazing company in Britain. Decades later, Everest still has the strongest brand recognition on this list. Does it deserve its high profile, especially now that it’s part of the Anglian family?
We think it does. Everest in its original form is the most experienced firm of its kind, having begun to produce and fit aluminium secondary glazing in 1965. It later added uPVC and timber frames across the full range of window styles. It has been through a couple of incarnations, having gone into administration in 2020 (when it rose again as Everest 2020) and then in April 2024 before the takeover by Anglian. It also offers doors (including garage doors), conservatories and roofline products such as guttering, adding up to a convenient one-stop shop when you’re renovating your home.
We found Everest’s website particularly easy to navigate, with clear information about guarantees, financing and prices. Uniquely among companies on this list, Everest displays price estimates online, rather than forcing you to submit details for a quote.
Prices start at £600 per uPVC casement window and rise to more than £2,000 if you opt for extras such as A++ rated triple glazing, custom frame colours and a wealth of security features such as “GrabLock” locks. These extras can boost the value of your property and reduce your insurance premiums, but they are a sizeable upfront investment.
Everest receives a pretty average score of 4.1 on Trustpilot, with some concerns about customer service.
Read our in-depth Everest review
- Price estimates are offered upfront, although you'll need a quote for proper planning
- A++ rated triple glazing option offered as standard, for top-notch insulation and soundproofing
- Guarantees range from 10 years on most products to 15 years on sealed units
- Reviews sometimes mention unreliable service
- Finance options are less eye-catching than they were before Everest joined the Anglian family
- It may be a little soon to fully judge the impact of the takeover by Anglian on its customer service
What Everest’s customers say
“Kept us well informed every step of the way. From first meeting to completion of work all involved were courteous and helpful, and answered any questions we had. Fitters were very efficient and treated us and our home with respect” – Mr and Mrs Clark, April 2024
“Had secondary glazing installed for sound proofing and its made a big difference. Windows all look great, fitted well, had some very minor issues they were quick to come in, inspect and resolve with very little hassle” – James, March 2024
What type of double glazing do you need?
Get startedBest for sustainability: Safestyle
Following its fall into administration in October 2023, Safestyle is now part of the Anglian Home Improvements family.
The Safestyle range isn’t as broad as Anglian’s or Everest’s, and its windows are all uPVC rather than aluminium or timber. But it does also offer doors and roofline, and its windows cover a decent range of styles including sash, leaded, etched and French windows.
Safestyle’s commitment to sustainability genuinely impressed us. The company recycles your old windows and re-uses what it can to make new windows and other products. Every month it recycles tonnes of used uPVC into drainpipes and plastic decking, and turns wood into pellet fuel for biomass heating systems.
Like Anglian, Safestyle doesn’t publish any prices upfront. However it does offer a quote-match promise and a guarantee of up to 15 years on its windows.
In terms of customer reviews, it receives a fairly average score of 4 on Trustpilot, with some of the most recent reviews since the takeover by Anglian raising concerns about customer service and quality.
Read our in-depth Safestyle review
- Safestyle pledges to meet any like-for-like quote
- Clear double-glazed units come with a 15-year guarantee
- The company takes away your old windows for recycling, so you don't have to worry about disposal or waste
- Safestyle is no longer an independent company following its rescue from administration by Anglian
- Only makes uPVC frames, not aluminium or timber
What Safestyle’s customers say
“One workman arrived who was polite and respectful. He proceeded to remove five windows, fit the new ones and all their trim, clean (the) wreckage up all by himself… gone before dinner with no breaks. Brilliant!” – Christine de Hamel, July 2024
“The windows and doors fitted all look great and are really good quality. We liked the fact they are made in the UK too” – Tamsyn, October 2023
Best for security: First Home Improvements
First Home Improvements will make any style of window you want, as long as it has a uPVC frame – no wood frames here, alas. The company also installs conservatories, porches and doors, including composite front doors that you can plan online using the website’s Door Designer tool.
All these products will enhance the security of your home, but First Home Improvements goes the extra mile by including Yale’s patented Blade Lock system – which it claims is “the strongest, safest and most secure lock on the market” – with all its windows and doors.
First Home Improvements guarantees the entire window, including locks and frames, for an unusually generous 12 years, compared with the typical 10 years for anything other than the sealed glazed unit. Customer reviews were among the best we saw, too, adding up to an “excellent” 4.5 average on Trustpilot.
- Windows and doors use Yale Blade Locks, claimed to be the strongest window locks on the market
- Windows and locks guaranteed for 12 years, compared with the usual 10
- Long list of accreditations includes FENSA, BFRC, GGF and Made in Britain
- Excellent customer reviews praise fast, polite, tidy installers
- Only makes uPVC frames, not aluminium or timber
What First Home Improvements’ customers say
“The installers turned up on time and were friendly, getting on with the job immediately. They worked non-stop until it was complete, doing a very professional job including taking away the old windows” – John Adams, August 2024
“When installation was complete, all window locks and opening/closing functions were explained thoroughly. A very good job done very well” – PB, August 2024
Best on a budget: Britelite Windows
Britelite is another company that doesn’t publish prices upfront, but when we asked for a free quote we were very pleasantly surprised by the result, with a uPVC casement window costing around half the price of the equivalent window from Everest. What makes this even more impressive is that all windows come with a 10-year guarantee that’s fully transferable if you sell your house.
We haven’t taken the quote process any further than that, so it’s hard to judge whether you get what you pay for with Britelite’s windows, but customer reviews mention “superb quality” and say the windows “stay looking good for a lifetime”.
Customer reviews aren’t quite as glowing for Briteline as for some other companies on our list (notably First Home Improvements, Clearview and Scottish company CR Smith), but it still scores a very respectable 4.4 on Trustpilot, with praise for the company’s quick responses and professional approach.
- Prices are at the affordable end, but you will have to submit your details and wait for a reply to get a quote
- 10-year guarantees are fully transferable to subsequent openers of your home
- Range includes aluminium frames and triple glazing as well as double glazed uPVC
- Also installs doors, conservatories, flat roofing and roofline
- Customer reviews occasionally cite installation errors, and Britelite doesn't respond to all comments
What Britelite’s customers say
“Luke and Paul came to install my bay window. Clean, efficient, very friendly and finished the job on time too. Definitely recommend to anyone wanting windows that last and stay looking good for a lifetime” – Ana Partlett, July 2024
“The workmen were clean and efficient, they worked hard, were diligent and tidied up everyday they were in the house. The windows are superb quality” – Liza Stubbs, August 2024
Best for 3D previews: CR Smith Windows
Many of the double glazing companies we researched offer 3D preview tools to help you visualise how your new windows, door or conservatory will look in your home. But none offer quite the design process that Scottish firm CR Smith does.
During CR Smith’s “virtual appointment”, the consultant uses photos and measurements of your property to create an immersive preview of how your windows or conservatory will look in your home. They talk you through the options available, and suggest alternatives if you’re not happy.
The company provides and installs Lorimer windows in many different finishes and styles, although you have to choose between uPVC (the cheapest) and timber (the most expensive) rather than opt for anything in between. If you go for those gorgeous wooden frames, you can at least spread the cost via finance options that the company itself handles.
With customer feedback averaging a superb 4.9 on Trustpilot, there’s only one significant downside we can find with CR Smith Windows: you have to live in Scotland to use them. Another reason to move north of the border, perhaps?
- Outstanding customer feedback is among the best we've seen for any firm
- Fully immersive digital preview of your project lets you check and tweak your choices before you commit
- Security guarantee promises to replace any any window frame broken by an intruder
- Financing is handled in-house rather than by a separate credit broker
- Only available in Scotland
What CR Smith’s customers say
“Fantastic service from start to finish. We were kept informed every step of the way. The installation team were professional and friendly throughout, hardly knew they were there. Extremely happy with our new window, great quality and value for money!” – KW, August 2024
“We wanted a company that we could trust and that’s what we got. The service from start to finish was great, the team are easily accessible by phone and email which made planning simple” – Rachael, July 2024
Best for warranty: Clearview Home Improvements
The average double glazing guarantee is around 10 years, roughly a third of the expected lifetime of a window, but Clearview doubles that with a 20-year guarantee. This market-leading pledge is one of the reasons the company has won the industry’s G Award two years in a row.
Clearview’s website and customer feedback has a strong focus on living spaces including conservatories and extensions rather than windows, but the company offers a decent range of window styles too, albeit in uPVC and aluminium only.
As with CR Smith, the key limitation with Preston-based Clearview is geographical coverage: North West England, in this case. However, this is only a downside if you don’t live there. If you do, you will benefit from the company’s local knowledge and teams – as confirmed by the firm’s excellent customer feedback, adding up to a strong 4.5 score on Trustpilot.
- Market-leading 20-year warranty on windows and other products, plus an outstanding 10-year labour guarantee to cover workmanship
- Superb range of home improvements including orangeries and extensions as well as windows and doors
- Windows made in the UK by manufacturing partner Conservatory Outlet
- Customer feedback is excellent, regularly citing great communication
- Coverage is currently limited to North West England, but that may change in time
What Clearview’s customers say
“Each stage ran like clockwork with no delays including when the roof and windows were fitted in a mini monsoon… Not only thrilled with the end result but extremely impressed with the individual and collective work, and definitely the end product” – John Barnard, August 2024
“Clearview were excellent from start to finish, from the initial design stage to final completion. We encountered delays outside their control, and they were very patient with us until we were in a position to proceed” – Keith Mcguire, April 2024
Our methodology explained
Our team of four researchers spent 28 hours investigating double glazing companies to find the top seven firms across the country. Here are the key criteria we used to whittle the list down to seven:
Warranty – windows need a solid warranty to protect them from unavoidable wear and tear. The average double glazing warranty is 10 years, with only the sealed units typically guaranteed for longer, so we prioritised companies offering longer warranties.
Choice – one window size does not fit all houses, and not everyone wants boring white uPVC. So we looked for companies that offered a wide range of materials and styles, and made all their windows to measure.
Customer feedback – we couldn’t test our best double glazing companies by hiring them, so we turned to our most trusted sources: customers. We analysed nearly 1,000 verified customer reviews via TrustPilot and Check-a-Trade and prioritised companies with a high proportion of positive reviews.
Customer service – we gave companies credit for responding quickly and graciously to feedback, and for offering easy ways to get in touch. Some of the companies we considered for this article had customer service email addresses that immediately “bounced back”, so we decided not to include them.
Accreditation – don’t even think about hiring a window installer in England and Wales who can’t give you a FENSA certificate for the job, because it will make your house harder to sell (take it from one who’s experienced it!). We also prioritised companies accredited by the TrustMark and the Glass and Glazing Federation.
Industry experience – companies with 50 years’ experience aren’t necessarily better than those with five years’ experience, but if a firm has a long and successful history of providing and fitting windows you can be fairly confident it knows its stuff.
Security – double glazing naturally enhances the security of your home, but we wanted to see what else companies could offer for extra peace of mind and potentially lower insurance premiums. For example security glass, complex locking mechanisms and break-in guarantees.
Previews – ideally you want to know how windows will look in your home before you commit, so we looked for clever preview tools such as 3D virtual consultations that give customers a realistic idea of the finished job.
Affordability – we didn’t just look for the cheapest windows overall, but instead considered a balance of cost, quality and transparency about pricing.
Finance options – following Anglian’s purchase of Everest and Safestyle there’s less competition in the field of financing for home improvements, and interest rates have risen in recent years. We looked for companies offering easy, flexible repayments.
Geographical coverage – we awarded star ratings for wide UK coverage, because there’s little point in raving about a double glazing company whose locality means you may not be able to use them. That said, we recommend considering installers local to you. They will benefit from local knowledge, and may be able to book you in more quickly. Use our free double glazing quote tool to find installers near you.
Next steps
By now, you’ll have a good idea of which double glazing installer is right for you. The next step is to find the best deal – and that’s where we come in.
Enter a few details about your home on our window quotes form and let us do the rest. We’ll pass on your details to our hand-picked selection of professional installers, who will then get in touch to let you know their best prices. You have no obligation to take them up on it.
If you’re looking to let some light in through a window in your roof, take a look at our guide to buying skylights and rooflights.
