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New windows are a big investment that can make a big difference to the look and feel of your home. Here's what to expect when replacing windows in your home, including the costs, the process, how to find an installer, what FENSA is and why it matters, how long it takes to replace windows and more.
With the rising cost of energy, for many, replacing windows and doors in their home has gone from ‘nice to do’ to ‘must have’. Not only do new windows and doors improve the aesthetics of your home, but they keep your home warm and improve its energy efficiency thereby reducing energy bills.
If your windows are old, draughty or showing signs of wear, replacing them with modern energy-efficient windows could make a noticeable difference to the warmth and comfort of your home.
Modern-day windows are incredibly versatile. You will have a variety of styles, materials, colours and costs to choose from that provide you with a more comfortable home environment and can make a genuine difference to how you utilise the space.
Not only that, but as energy prices continue to rise, British Fenestration Rating Council (BFRC) energy ratings will provide you with independent proof of how your windows will perform. Remember that only when a window has an ‘A’ rating or better does it save more energy than it lets out.
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When it comes to replacing windows, the cost is usually everyone’s main concern. That’s because the cost of replacing windows can be prohibitive. As a rough guide, replacing windows can cost anywhere from £500 to £3,200 per window, depending on the size, style and materials you choose.
The total cost of replacing windows will depend on various factors, including:
If you want to know how much it costs to replace windows, then get a quote from at least three installers that are members of FENSA – a government-authorised scheme that monitors building regulation compliance for replacement windows and doors. Make sure you are comparing like for like to ensure you are getting good value.
As windows are bespoke, it’s difficult to give a precise amount as to how much it costs to replace windows. But the following is a rough guide as to how much you can expect to pay to replace different types of windows:
| Type of window | Average cost |
|---|---|
| Sash windows | £1,300 |
| Timber casement window | £925 |
| Timber sash window | £1,490 |
| Aluminium window | £475 |
| uPVC window | £325 |
| Aluminium sliding windows | £665 |
| Grey uPVC window | £350 |
| Bay window | £2,000 |
You do not need to replace all of your windows in one go.
Window installation companies will try to convince you otherwise. They are right that, as well as spreading the cost, you are spreading the disruption. They are also right that replacing all your windows at once could improve your home’s energy efficiency sooner than replacing them in stages.
But, given the cost of replacing windows, it’s no surprise that many people opt to replace their windows in stages rather than all at once. Some people decide to do the upstairs and then the downstairs to spread the cost and disruption. Others decide to replace one window a year.
The best thing to do is get a few written quotes from contractors. Remember to compare like for like. For example, if you are replacing wooden windows, check whether quotes include painting and decorating costs. And then negotiate the price.
FENSA is a government-authorised competent person scheme for replacement windows and doors in England and Wales. As well as our Find a builder tool which includes ratings of providers, you can use the FENSA website to put you in touch with your local installers via their ‘Find An Installer’ search function to request a quote directly from your chosen installer.
A FENSA-approved installer is continually assessed to ensure their work complies with building regulations which then enables them to issue you with a FENSA certificate once the job is done. A FENSA certificate is a key document when it comes to moving home so make sure you confirm you’ll receive one when the job is done.
When you choose a FENSA-approved installer to work on your property, they are obligated to provide you with an Insurance Backed Guarantee (IBG). An IBG is an insurance policy that provides cover for your installer’s guarantee if down the line there is a problem with your installation and the company that did the work has ceased to trade. Think of it as warranty insurance. If there is a subsequent problem with the installation that would otherwise have been resolved by your installer’s guarantee you can submit a claim to your IBG provider.
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When it comes to knowing what to expect when replacing windows, it’s helpful to look at the process from quote through to installation.
It will vary from job to job as to whether your installer replaces the windows from the inside or outside. Where possible, your FENSA approved installer will undertake as much as possible of the installation from outside to minimise disruption in your home. But working inside your home is essential to ensure your windows are fitted correctly and in compliance with building regulations.
A straightforward window installation should take around an hour. This will obviously vary depending on the size of the job, the size of your house along with the number and type of windows that need first removing and then replacing, as well as the number of installers on site.
You can expect 3-4 windows to be replaced with new ones per day as a minimum. If you are having wooden windows which need priming and painting, then of course, this will take longer.
A window replacement can be very messy. Despite how careful your window installer is, there will be dust and debris from the removal of old windows.
Ask your installer what to expect when replacing windows in terms of how messy things will be and what measures they will take to minimise mess. For example, we would expect them to use dust sheets and cloths on the floor and clear up after themselves at the end of each day.
You could take matters into your own hands as well by making room in your house, particularly in hallways and around window openings, removing or covering objects in the rooms that are having replacement windows, and even considering plastic wrap to protect carpets.
Your window installers should remove all debris from your home and leave it as they found it. But with shiny new windows.
A FENSA certificate provides evidence that your replacement windows and doors comply with building regulations and that the installation has been registered with the local authority. The certificate ensures the following:
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Yes, ideally you would have a certificate for any windows you replaced when you are selling your house to demonstrate they are compliant with building regulations.
The certificate doesn’t have to be from FENSA. It could be from another authorised scheme, such as CERTASS. Or you may have had your windows signed off by your local authority building control as part of a larger home improvement project, in which case check with your contractor.
If you are struggling to find a copy of your certificate, check on the FENSA website or CERTASS website. FENSA currently charges £30, including VAT, for a replacement certificate.
If you used a window fitter who wasn’t registered with a competent person scheme, all is not lost. You may be able to apply for retrospective building regulations approval, although fees vary and remedial work could be required. If you’re selling your home, ask your conveyancer about your options first, including whether indemnity insurance may be available. Contacting the council could affect your ability to obtain indemnity insurance.
But the simplest option when replacing windows and doors is to use a window installer registered with FENSA. When selling your home, the solicitor will ask for evidence that those replacement windows comply with the building regulations. You can easily demonstrate compliance with your FENSA certificate showing that the work has been completed by a competent installer and member of FENSA.
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