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How to buy double glazing

Double glazing sales and quotes

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Avoid being overcharged for double glazing. Read our expert guide to getting double glazing quotes and finding a reputable company.

Double glazing salespeople have a dubious reputation. But knowing their tactics and being one step ahead means you're far more likely to pay the right price. 

That's why we've spoken to experts and homeowners to get their advice on how to find the right double glazing company and get the best double glazing quote.

Which? members can log in now to read their tips on steering clear of the tricks that some double glazing companies use, on this page. If you're not yet a Which? member, you can unlock our expert advice by joining Which? now.

Joining Which? or logging in will also give you access to the results of our double glazing customer survey, where we reveal which double glazing companies are the best - see our double glazing company reviews

Buying double glazing

Before you start getting quotes for your double glazing, having a good idea of what you want means you'll be better informed and more in control with a salesman.

Trade shows or consumer home exhibitions are a good place to start. You'll be able to see a wide range of double glazed windows and doors in one place. 

Also, take a look at the homes in your area. What kind of windows do similar homes to yours have? Is there a type that's common in your road? You don't want your home to stick out like a sore thumb.

Remember also that at some point you may sell your home, so make sure the style you choose won't put potential buyers off. 

A number of homeowners we spoke to suggested visiting companies' showrooms/warehouses. When there, ask whether the double glazing is made on site to order, or bought in. This will give you an idea on how long it might take to get the products to you, and whether the company will have control over quality.  

It's a good idea to also discuss the technological benefits of different systems when visiting a showroom, so that you can get a feel for how knowledgeable and professional the company seems. 

One homeowner said: 'Visiting companies' premises to view options and discuss requirements was very helpful, especially as we got a good feel for the company by talking to its people. We then chose the one that answered questions in a straightforward manner, without trying to evade them and without applying pressure.'

Double glazing prices

Double glazing can cost vastly different amounts depending on whether you use a local or national company, how many windows you're getting installed, the type of window and type of frame. 

To find out how much you should expect to pay for different double glazing jobs, from sash windows to uPVC doors, see our double glazing pricing guide.

Double glazing quotes - and side-stepping sales tactics

The majority of double glazing buyers we asked* (53%) said that the reason they chose the company they used was because the sales person didn’t make them feel pressurised.

We've heard about instances of double glazing salespeople quoting a high price to begin with, and then dropping over the course of their sales visit, to encourage you to sign on the spot. The price you're quoted could drop by 75%, or more than £10,000, during a sales pitch. 

One homeowner said: 'All salesmen I have encountered use the same method - the first, second or third offer is not the cheapest. Even after the salesperson has phoned their boss, there is still room for further discount.'

This practice appears to be industry wide, as customers from all three big-name companies we've reviewed - Anglian, Everest and Safestyle - reported this happening to them. 

Which? members can log in now to read examples and tips on using your own tactics, so you can see what to avoid and how to get the best price. If you're not yet a Which? member, you can join Which? now. This will also give you full access to our double glazing pricing guide

Getting the right quote

Be wary of any salesman using tactics like this, and don't be persuaded to sign a contract there and then. Instead, aim to get three quotes – more than a third of the people we surveyed got only one. Getting three quotes not only buys you time to think carefully and make an informed decision, but also means you’re likely to get a competitive price.

Ensure each company gives you prices for exactly the same products and materials, so you can compare the quotes fairly. Compare the costs of what is included as standard and what is priced up separately as an optional upgrade or extra.

Finding a reputable double glazing company

Our double glazing company reviews show how major national brands compare with independent installers. We can tell you what their customers think about value for money, the quotation process, and of course the quality of the windows. 

Many of the homeowners we spoke to said speaking to friends and family for their recommendations was key in getting the right company. In fact, 52% said that choosing a company that had a good reputation was one of the most important factors in their decision. We'd also recommend using a company that's been around for 10 years or more.

Also ask to see examples of previous work. If possible, speak to these customers about their experiences, rather than just going by testimonials on the firm's website or in brochures. 

You can also find recommended local double glazing installers on Which? Trusted Traders, where traders listed have been through our rigorous checks. If you've encountered a good double glazing company yourself, you can also make a recommendation using the site.

Top tips from installers

We've also spoken to independent double glazing installers from around the UK to get the inside scoop on how to find the best company and ensure things run smoothly during and after the double glazing installation. Which? members can log in now to reveal these tips, along with the rest of this page and guide.  

Double glazing contracts

Once you have chosen a company, it's legally obliged to provide you with certain information in writing, such as a description of the goods/services, the total price (inclusive of any additional charges known at the start), when it will be provided and your rights to cancel - all of which it must adhere to.

However, be aware that in some circumstances, the company isn’t bound to provide as much detail, and you won’t have the right to cancel. This applies if you’re getting made-to-measure double glazing, or enter into an ‘on-premises contract’. This includes a situation where a trader has discussed the contract with at your home, but you agree to enter into this sometime later. 

What they do provide you with is still legally binding, so ask for as much as possible, and if you’re unhappy with what they provide you, reconsider that trader.

You can find out more about contracts on our page about your rights when buying double glazing.

BM Trada, Certass and Fensa-registered glaziers

It's a good idea to choose a double glazing installer that is registered with BM Trada, Certass or Fensa. Membership of competent person schemes, such as these, means that companies can self-certify that their work complies with building regulations. It also means that the work is covered by an insurance-backed guarantee if it's not compliant and the company goes bust.'

In England and Wales, new and replacement windows must meet a certain level of energy efficiency, and you need to get a certificate to show that your windows comply with these regulations. An installer registered with one of the self-certification schemes will issue this certificate for you - otherwise your council will need to come and check the work.

For the Channel Islands, Northern Ireland and Scotland, contact your local authority for information on applicable regulations for windows.

Our research

In August 2016, we asked 2,239 Which? members about their experiences with buying double glazing, as well as the company they bought double glazed windows and/or doors from, and had them installed by, in the last five years.