uPVC windows: what to check before you sign

01 What counts as replacement work

You can use the scheme when you replace external windows, doors, roof windows and roof lights in your home in accordance with the relevant Building Regulations. The property must sit on its original footprint and the use and size of rooms must not be altered. That limit matters because it keeps a like-for-like window change apart from building work that moves walls, changes room use or adds floor area.

If your plan changes the footprint or the way rooms are used, the page treats it as something else and not as a standard replacement. You then need another route for approval. Ask the installer to confirm in the quote that your address falls inside the replacement definition and to describe the rooms involved.

02 Will you get a FENSA certificate?

Ask the question directly before you agree anything: will you get a FENSA certificate when the job is done? The certificate is presented as all the proof you need that the installer meets building regulations. When you use a FENSA Approved Installer, the installer should always promise that certificate at completion.

The same FENSA page links the certificate to five practical effects. It confirms compliance with building regulations, shows that your installation is energy efficient, ensures registration with the Local Council, verifies that your installer guarantee is insured and is described as essential when selling the property. Compliance and registration are required by law, and the page places responsibility on you to make sure the installation is registered with the local council.

Not all installers comply with building regulations and not all of them will register the installation with the local council. If your installer does not mention your responsibility and does not offer a FENSA certificate or other building regulations compliance certificate, you will need to pay for an inspection by building control. The page tells you to allow a few hundred pounds for this and to make sure the installer agrees in the quote to put right any non-compliance found by the building inspector.

03 How do you find an approved installer before you sign

Each FENSA Approved Installer, from large national brands to small local companies, is assessed regularly to maintain compliance with building regulations. You can search by postcode, by company name and by FENSA registration number to find the nearest approved installer and to check the firm that gave you a quote.

Use that search before you pay a deposit. Check the name on the quote against the register entry and keep a copy of what you found with the quote. If there are problems later and you cannot get the firm back, the pages warn that you may need to hire another firm to put things right, so the written quote needs to say who certifies, who registers and who returns.

04 What does the page not publish about frames and glass?

The page does not publish frame profiles, reinforcement, hardware tests, glass specifications or thermal values. It says the installation is energy efficient but it does not give a rating scale, a U-value or a test method. For that reason you cannot compare one uPVC system with another from this FENSA guidance alone, and you can read the homeowner guidance from FENSA to see where its statements stop.

You can still use the gap as part of your checklist. Ask the seller to put the exact product description on the quote and ask how energy ratings are read if a rating is claimed, since the homeowner page itself gives no figures for glass or frame performance. The discipline here is simple: what is not in the certificate record must be in the written quote if you want to rely on it later.

05 Guarantees, insurance and the documents you keep separately

The guarantee comes from your installer and not from FENSA. Because of that, your installer remains responsible for matters covered by its guarantee, and any issue with the products themselves sits under that installer guarantee rather than under the building compliance record. If you cannot find the guarantee document, the advice is to contact the installer directly.

Keep the insurance-backed guarantee separate from the certificate in your file. Installations completed after 2014 may have an insurance-backed guarantee policy, also called a warranty insurance policy, which is separate from the FENSA certificate and is issued by an insurance broker. It covers the written guarantee if the installer ceases to trade. Installations completed in 2013 or earlier may not have such a policy because such a policy was not mandatory until 2014. If you are unsure whether you hold a policy, look through all your paperwork first, then ask for help to trace the broker details through the Contact Us page and contact that broker directly about a claim. The pages add that you can also check your own home insurance policy, and that without an insurance policy in place you are likely to cover remedial costs yourself because FENSA does not issue guarantees. Keep both documents together with notes on what homeowners must keep on file.

06 What sits outside the scheme

FENSA does not cover the installation of windows and doors in new conservatories, porches, new builds, new extensions, repairs where the frame is not included and commercial properties. It does not cover new builds or new extensions at all, and for those cases the pages point you to Local Authority Building Control. It only covers replacement of windows or doors in the habitable and heated sections of your home, and for all other structures it points you to your local Trading Standards office.

That boundary shapes your uPVC order. A window swapped in an existing heated bedroom is inside the logic of the scheme, while a window set into a new porch wall or a repair that keeps the old frame is not. If your project mixes both types of work, ask for separate written lines so you know which openings receive a certificate route and which need another approval route.

07 If something goes wrong after the fitting

The advice pages filter complaints through five checks: whether the matter concerns compliance with building regulations for replacement windows or doors in a habitable area of a domestic building, whether the firm is a FENSA Approved Installer that you can check through the search, whether the matter concerns a new build, a new extension, a conservatory or an outbuilding such as a garage or porch, whether it concerns the installer guarantee, and whether you seek a refund or compensation.

Where FENSA can act, it can only request remedial works by the FENSA Approved Installer that completed the installation. It cannot recommend an alternative installer, though you can use the search to find others in your area, and you should check that further work by another firm will not affect your guarantee. It will only address the original installation and not remedial works completed by another installer. The pages advise you to write to the installer first, set out what needs to be addressed and allow a reasonable time to respond, then contact your local Trading Standards office if you remain unsatisfied. For financial matters, it advises you to ask the installer to direct you to its Alternative Dispute Resolution provider for mediation or to contact Trading Standards. A complaint about compliance by an approved installer is answered with an aim to reply within 5 working days.

Put the checklist in one folder before the fitters arrive: the quote with the certificate promise, the register search result, the guarantee wording and the broker contact. Write to the installer promptly if a fault appears and keep copies of each letter.

FENSA homeowners service

It is the homeowner section of the fenestration self-assessment body. It holds the Find a FENSA Approved Installer search by postcode, company name and registration number.

It explains the FENSA certificate, its cover for replacement external windows, doors, roof windows and roof lights, its limits and the insurance-backed guarantee route.