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How To Choose The Right Installer

Even the best quality replacement windows, if they are poorly installed and don’t work properly, will make your home look and feel tired and unloved. Combine that with the fact that a poor installation can cause significant air leakage from your home, which wastes money on heating bills, you can see why it is so important to choose an installer that will do the job right.

download guide choosing windows - guide
Mark Warren

Most people take one of two routes to choosing the right window installer. The first and most common is a search online, which has its pros and cons. The second is to ask friends, family or other people in the know that have direct experience of the service provided by a window installer. If it’s the latter you’re on fairly safe ground – if they get a good rating from people you know then it’s a fair bet that they are right for your windows. However, what about when you don’t have a recommendation? In all likelihood you’ll begin with an online search to find a list of installers in your area. Now, as we all know, this does work, but it can be a minefield sifting through the many hundreds of installers that will pop up in search results. Amongst these, there will be the good, the bad and the downright ugly. When it comes to finding a reputable window installer, there are a few simple rules that you need to follow that will make the whole process much easier. To guide you through this process, here is a checklist:

Ask for independent certification

As Chairman of FENSA, you would expect me to say this; however, there really are good reasons to choose an installer that is registered with our organisation. Firstly, FENSA is a non-profit making organisation that was set up by the Glass and Glazing Federation (GGF) at the request of the Department for Communities and Local Government (DCLG) to allow registered companies to self-certify that their installations comply with current Building Regulations.

Compliance with Building Regulations is mandatory and it doesn’t just apply to energy efficiency. Your replacement windows need to meet other legislative requirements such as safety, air supply, means of escape and ventilation. A FENSA registered window installer can take care of all this.

In fact, if you use a FENSA certified installer you will automatically receive a FENSA certificate that will state that the installation complies with Buildings Regulations. Keep this certificate safe – you might need it when youcome to sell your home. If you do lose it you can purchase a replacement certificate from FENSA.

As part of maintaining high standards, FENSA carries out random inspections of its registered installers, which include tests during installation and after the windows have been fitted.

If you use a non-FENSA registered installer or opt for installing the windows yourself, you’ll have to seek approval from the relevant Building Control body – either at your Local Authority or an Approved Inspector. They will check the replacement windows or doors for compliance and, if satisfied, issue you with certification. However, this is a time consuming and laborious process.

Members can display the FENSA logo on their letterhead, business cards or vehicle. Always check that an installer is currently FENSA certified by searching for them on the FENSA website.

Ask for references

Even if the installer has independent certification, for example, is a member of FENSA or GGF, you still need to check references. There are many websites that offer reviews and feedback about installers.

However, there is still no substitute for talking to some of the installer’s customers directly. The kinds of questions you need to ask are:
• Did the company complete the work on time and on budget?
• Do you feel the company was trustworthy and did what they say they would?
• Were they clean and tidy on site?
• Did you have any post-installation issues with the windows? If so, did the installer respond promptly to these issues?

Know what you are getting

A good installer will provide you with a written quotation that details what service they will provide and how long it will take. Bear in mind that it will take around 4–6 weeks to manufacture the windows once the installer has taken the final measurements from your home. An average size home should take 2–4 days to replace all the windows.

Ask about their work process too, as it’s better if the new window
is put in as soon as the old one is removed. Insist that the installer measures each replacement window before ripping out the old one. You don’t want a boarded-up hole while you’re waiting for the right sized window to arrive!

Shop around

Always ask for more than one quotation so that you know you are getting good value. When you compare the quotes always look closely at the detail such as window brand, number of windows, their size and type, plus any add-on features such as Secured by Design, energy efficient glass or non-standard colour. The key thing is to ensure you are comparing like with like.

A quote from a reputable tradesman should include installation details, such as how the windows will be sealed and insulated. Labour and material costs should always be broken down. This level of detail allows you to compare quotes easily and then choose the one that is most suitable to your requirements.

Question their knowledge

A knowledgeable installer that can offer you advice on energy efficiency, security and safety is a sign that they are a specialist, trustworthy company. Here are some of the things that they should know about:

Building Regulations

Building Regulations Approved Document L requires a minimum energy performance requirement for existing dwellings in England and Wales. These are:

Replacement windows
• Must meet a minimum Window Energy Rating (WER) of band C; or
• A whole element U-Value 1.6W/m2K or better

• Must meet a minimum Whole element U-Value 1.8W/m2K or better Glass

There are many types of glass but make sure you ask your installer about the benefits of Low Emissivity – this has a special invisible coating that prevents heat escaping through the glass on cold winter days by reflecting heat back into your room. It is worth considering as it will add to overall energy efficiency of your windows.

A-rated windows

One of the questions you need to ask a potential installer is whether your windows/doors are rated by BFRC (British Fenestration Rating Council) – the premier authority responsible for Window and Door Energy Ratings in the UK. The BFRC rates the energy efficiency of window and door products from ‘A+’ (the most energy efficient) to ‘C’ for windows and from ‘A’ to ‘G’ for doors. It uses the well-known rainbow label, similar to that found on fridges, freezers and washing machines.

The next question ought to be about the benefits of A-rated windows. The Energy Saving Trust has calculated the savings you could make on your heating bills by fitting energy rating windows. For more information please click: content/energy-efficient-windows They estimated that upgrading from single glazed to A-rated windows will save you around £85.00 – £110.00 on your heating bills each year.

More importantly, A-rated windows will improve the comfort of your home significantly and not just by making it warmer. External noise insulation, air tightness and security will all be better, so the improvement your new windows will make will be very noticeable.


A good installer should be able to offer guidance on the best way of making your windows more secure. Ask them about Secured by Design windows. This is a police initiative that focuses on designing out crime by encouraging the use of enhanced security standards for windows and a range of other products.


Often a specialist, local window installer can provide just as good a service and better value than a national company, but we would suggest checking them both out before making a decision. That involves making sure they have a track record of happy customers, can offer you knowledgeable advice and carry independent certification.

Getting recommendations from friends and family is always a sensible way to go. However, this kind of valuable information isn’t always available. If you follow the steps outlined above, you should be well on your way to choosing the right window installer.

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