Best and worst double glazing companies

We've asked thousands of double glazing customers to rate the company they used, including major brands Anglian, Everest and Safestyle, as well as independent traders.

The answers, from more than 3,000 double glazing customers who bought double glazing in the past 10 years, mean we've been able to rate seven of the biggest firms based on their customers' experience.

Half of those who responded to our survey bought their double glazing from a local or independent double glazing company. So besides rating seven of the big brands, we also have a dedicated advice guide for buying from an independent double glazing firm.

Our results rate each double glazing company across lots of factors, including customer service, quality of products and installation, knowledge and helpfulness of staff, and how much mess they made during the installation.

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Which is the best double glazing company?

Only logged-in Which? members can access the customer ratings in the table below. If you're not yet a member, join Which? to unlock our results. 

You'll see data about where companies are succeeding, and which are disappointing their customers. 

You'll also get access to the full reviews of Anglian double glazing, Everest double glazing, Safestyle double glazing, as well as insight from those who purchased from a local independent on our dedicated independent glazing companies page.

The table gives a snapshot of the areas on which we've rated double glazing firms, based on the feedback of their customers. Our full ratings cover sales and purchase, delivery, installation, aftersales support and how well the windows or doors stand up to the test of time.

Double glazing companies rated by their customers

 Ready to buy? Find out how much double glazing costs.

Which? double glazing company reviews

Our ratings include customer feedback across all aspects of buying and owning double glazing – from sales and purchase, to delivery, installation and how well the windows or doors lasted.

The results for each company are based on our survey of 3,409 people in August 2022 who bought double glazing for their home in the past 10 years. 

Customer scores are based on a combination of how satisfied customers of the brand say they are, and how likely they are to recommend it, if asked.

We also ask customers to rate more than 10 other aspects including the choice of products, clarity of documents (eg the contract), how well the installers communicated and how well the double glazed windows or doors have lasted. Customers rate them on a scale from very poor to excellent, which we translate into a star rating.

See how owners rated independent double glazing firms by visiting our dedicated page. If you want to find a reputable double glazing company near you, use Which? Trusted Traders.

If you're ready to buy now, check out our double glazing buying guide for tips on getting quotes, side-stepping sales tactics and avoiding being overcharged.

Anglian, Everest and Safestyle double glazing compared

Anglian, Everest and Safestyle are the three major double glazing firms and are the companies that customers most commonly consider. Of those who considered other double glazing firms to the one they chose, 25% considered Anglian, 22% considered Everest and 12% considered Safestyle.

Visit our dedicated pages on Anglian, Everest and Safestyle to find out more about how the firms compare and the services they offer.

Only logged-in Which? members can access our full analysis. If you're not yet a member, join Which? to unlock our results.

Britelite double glazing

Founded in 1970, Britelite has more than 50 years' experience of fitting windows, doors and conservatories.

The firm says it has always aimed to supply the best product at the most competitive price possible. It serves customers in Kent, Sussex, Essex, Surrey and London. But how did its customers rate it in our survey?

Which? members can log in to find out what customers thought of Britelite in our survey. If you’re not a member, you can join Which? to see our exclusive ratings.

Britelite windows, doors and guarantee

Britelite installs windows, doors and conservatories in Kent, Sussex, Essex, Surrey and London.

All of its products have a 10-year guarantee.

Britelite is a Which? Trusted Trader, which means it has passed rigorous checks and vetting. Use our free service to find a reputable, reliable double glazing firm near you.

Coral Windows

Serving households in Yorkshire since 1990, Coral Windows has five showrooms and develops, designs and manufactures all of its doors, windows and conservatories in Bradford.

The firm says it's an established customer favourite across Yorkshire, and prides itself on providing market-leading products and excellent customer service. But how did it fare in our survey?

Which? members can log in to find out what customers thought of Coral Windows in our survey. If you’re not a member, you can join Which? to see our exclusive ratings.

Coral Windows products and guarantee

Coral windows sells double-glazed windows, doors, conservatories and orangeries, all of which it makes at its manufacturing plant and head office in Bradford. The areas it covers include Yorkshire as well as parts of Lancashire, Cheshire, Nottinghamshire and Lincolnshire.

Its uPVC frames have a 15-year guarantee, and sealed units have a 10-year guarantee.

Unusually, it doesn't take deposits; customers pay in full when their project is complete.

Coral Windows is a Which? Trusted Trader, which means it has passed rigorous checks and vetting. Use our free service to find a reputable, reliable double glazing firm near you. 

Get more information on the range of double glazing products and services provided at Coral Windows.

Crystal Windows and Doors

Which? members can log in to find out how customers rated Crystal Windows and Doors in our survey. If you’re not a member, you can join Which? to see our exclusive ratings.

Based in Essex, Crystal Windows and Doors has been trading since 1995 and makes all of its products in its Romford factory. 

It says it has become one of the most trusted home improvement brands in the south-east, and has carried out over 90,000 installations in the region. But how did it compare with other big brands according to its customers in our survey?

Crystal Windows and Doors products and guarantee

Crystal Windows and Doors sells a range of double-glazed windows, including sliding sash, casement, tilt and turn and bay windows. It also offers a range of front doors and patio doors, as well as garage doors, roof services, driveways and spray-foam insulation.

It offers a 10-year guarantee, which it says is its customers’ favourite feature about the service. It says that this means if you have any problems with its products, its dedicated team will help sort things out.

It's not the same company as Crystal Direct, a Hertfordshire manufacturer of uPVC windows, doors and conservatories which are available in B&Q and Screwfix.

Get more information on the range of double glazing products and services provided at Crystal Windows.

First Home Improvements

First Home Improvements claims to be one of the longest-established double glazing companies, and it says it offers a first-class service to help customers choose the best double glazing. 

Which? members can log in to find out if First Home Improvements lives up to its promise, according to customers in our survey. If you’re not a member, you can join Which? to see our exclusive ratings.

First Home Improvements products and guarantee

First Home Improvements installs windows, doors, conservatories, porches, garages and does roofline work.

It serves counties across the Midlands, East Anglia and southern England and has 18 showrooms across these regions.

It offers a 12-year warranty on all of its double glazed windows. The locks on its windows (supplied by Yale) are also included as part of the 12-year warranty.

Get more information on the range of double glazing products and services provided at First Home Improvements.

Independent double glazing companies

Half of the double glazing owners that we spoke to used an independent company, such as a small firm local to them that may not be widely known outside the local area.

This may also include local builders and joiners, who you're more likely to use if you're having new windows or doors as part of a home renovation, such as a new extension.

Find out why customers chose independent double glazing companies and what they thought of them in comparison with bigger brands.

You can also use Which? Trusted Traders to find a reputable local company.

All traders who use our Which? Trusted Traders logo have been through rigorous background checks, done by ex-Trading Standards assessors. The traders must also agree to follow our code of conduct and are checked on an ongoing basis. 

Don't get overcharged for your new windows. We've crunched the numbers to find out the average cost for various sizes and types of double-glazed windows and doors. See the latest double glazing prices. 

Common double glazing problems

No matter how good a company is, problems can arise. To help you avoid potential pitfalls, we asked double glazing customers what issues they came across with the purchase, delivery and installation of their double glazing, as well as problems they experienced after the installation.

Reassuringly, 77% of our survey respondents said they had no problems. 

Post-installation problems were the most commonly reported, followed by installation problems, delivery problems and problems when buying.

While 13% told us about post-installation issues, just 2% reported a problem with buying their double glazing.

The most common post-installation problems included:

• doors and windows becoming difficult to open or close
• windows or doors sagging or dropping so that they don't fit as well
• locks not working.

Visit our page on double glazing repairs and maintenance for tips on how to fix window problems.

The most common issues with installing double glazing were:

• windows not fitting as well as they should
• installation taking longer than planned
• wrong positioning of panes or parts.

To head off potential problems early, make sure you have a clear idea of what you want, that you understand what you're buying, you get clear and detailed information, and that you don't feel under pressure to make a purchase quickly. 

If you're currently having difficulties with your double glazing company, our page on your rights when buying double glazing talks you through the steps you need to take.