Window and Door Guarantees Explained: FENSA Certificates, Warranties and Insurance Backing

Home » Window and Door Guarantees Explained: FENSA Certificates, Warranties and Insurance Backing

The paperwork that comes with new windows or doors matters as much as the installation. You should end up with three things: a FENSA certificate or a Building Control completion notice proving the work meets Building Regulations, a written installer guarantee covering the products and the workmanship, and an insurance backed guarantee that stands behind that promise if the installer is no longer trading. Missing any of the three creates a problem, usually at the point you sell the house.

Key takeaways

A FENSA certificate is regulatory compliance evidence. It is not a guarantee and does not cover faults.
The installer guarantee is the document that actually gets a fault put right, so read what it covers and for how long.
An insurance backed guarantee protects the installer guarantee if the company ceases trading.
Product guarantees and workmanship guarantees are separate things with different durations.
A conveyancing solicitor will ask for the certificate. Keep all three documents together with the deeds.

What a FENSA certificate actually proves

When you replace a window or a door in an existing home, that work falls under Building Regulations. There are two legitimate routes to compliance: the installer is registered with a competent person scheme and self certifies the work, or you make a Building Control application and the local authority inspects it. FENSA is the best known of those schemes for replacement glazing, and the certificate it issues is your evidence that the installation met the regulations on thermal performance, ventilation, safety glazing and means of escape.

What it is not is a warranty. A FENSA certificate says the work complied on the day it was done. If a hinge fails two years later, the certificate is irrelevant and your guarantee is what matters. That distinction catches people out. Our article on what FENSA actually means goes into the compliance side, and FENSA publishes the scheme rules directly.

The certificate normally arrives within a few weeks of completion and is registered against the property address. If it has not appeared, chase it, because reissuing later is harder than getting it at the time.

Reading an installer guarantee properly

This is the document that gets things fixed, so it deserves a careful read rather than a glance. Look for four things. What is covered, meaning the frames, the sealed units, the hardware and the workmanship separately. How long each element is covered for, because a ten year headline figure often applies to the frame while hardware carries a shorter term. What is excluded, typically accidental damage, misuse and normal wear on moving parts. And what you have to do to keep it valid, which is usually reasonable maintenance and reporting faults promptly.

Sealed units are the element worth checking hardest, because they are the most common thing to fail. A guarantee that covers sealed units against misting for a decent term is meaningfully better than one that covers them for a couple of years. Ask for the term in writing rather than accepting a verbal figure.

The three documents and what each one does

Document	What it proves	What it will not do
FENSA certificate	The installation complied with Building Regulations	Fix a fault or cover a failure later on
Installer guarantee	The company will remedy defects in product or workmanship	Help you if that company stops trading
Insurance backed guarantee	A third party insurer stands behind the installer guarantee	Cover things the installer guarantee excluded anyway

Why an insurance backed guarantee matters

A guarantee is only as good as the company standing behind it. If an installer ceases trading, their guarantee normally goes with them, and you are left with a fault and nobody to call. An insurance backed guarantee is a policy taken out at the time of installation which transfers that obligation to an insurer for the remaining term. It is the difference between a promise and a promise with something behind it.

Perfect Wirral installations carry an IWA insurance backed guarantee giving ten year protection, alongside our TrustMark registration, which is the government endorsed quality scheme. Ask any installer whether their guarantee is insurance backed, who the insurer is, and to see the policy document rather than a logo on a brochure.

What to collect and keep after an installation

1 The written quotation and specification

This is what you agreed to. It settles any later question about what was supposed to be fitted.

2 The FENSA certificate or Building Control notice

Your regulatory evidence. A buyer’s solicitor will ask for this, so file it with the deeds.

3 The installer guarantee

In writing, with the covered items and terms set out. A verbal assurance is worth nothing at year four.

4 The insurance backed guarantee policy

The actual policy document, not just a reference to one, including the insurer and the policy number.

What happens at the point of sale

When you sell, your solicitor will ask whether any replacement glazing has been installed since April 2002 and, if so, for the compliance evidence. Without a certificate or a Building Control notice, the usual outcomes are a delay while a retrospective indemnity policy is arranged, a price adjustment, or a buyer who walks. None of that is dramatic, but all of it is avoidable by keeping a piece of paper. If a certificate has genuinely been lost, FENSA can search its register by address, and the GOV.UK guidance on building regulations approval explains the regularisation route where no scheme certificate exists.

Questions to ask before you sign an order

Will this work be certified through FENSA or a Building Control application?
What exactly does the guarantee cover, and for how long on each element?
Is the guarantee insurance backed, and who is the insurer?
What are the exclusions, and what maintenance keeps the guarantee valid?
Are you a TrustMark registered business, and can I verify the registration?

Frequently asked questions

Is a FENSA certificate a legal requirement?

The legal requirement is that the work complies with Building Regulations and that you can demonstrate it. A FENSA certificate is the most common way to demonstrate it for replacement glazing, but a Building Control completion notice does the same job. What you cannot do is have replacement windows installed with no compliance evidence at all, because that surfaces when you sell.

How long should a window guarantee last?

There is no fixed answer, and the useful comparison is element by element rather than headline number. Frames commonly carry ten years, sealed units often a similar term against misting, and hardware such as hinges and handles usually less. A short hardware term is not necessarily a red flag, because moving parts wear, but you should know the figure before you order rather than after.

What if my installer has gone out of business?

If the work carried an insurance backed guarantee, contact the insurer named on the policy and they will handle the remaining term. This is precisely the situation those policies exist for. Without one, you are looking at paying another installer to put the fault right. It is the strongest practical argument for checking the insurance backing before you commit.

Does a guarantee transfer to a new owner?

Often yes, but it depends on the terms, and some guarantees are personal to the original purchaser while others transfer with the property. Check the wording. Where a guarantee does transfer, it is a genuine selling point, so hand the documents to your buyer rather than leaving them in a drawer. The compliance certificate transfers with the property regardless.

I have lost my FENSA certificate. What now?

FENSA maintains a register searchable by property address, so a replacement can usually be obtained provided the work was registered at the time. If the original installer never registered it, that is a different problem, and the route is a regularisation application to your local authority building control. Start that before you put the house on the market rather than during the conveyancing.

Are guarantees on conservatories and garden rooms different?

Yes, because there are more elements involved. A conservatory or garden room involves a base, a structural frame, glazing, a roof and sometimes electrics, and each can carry a different term. Roofline products are another example: our Freefoam registered installer status carries a lifetime warranty on those specific products. Ask for the breakdown rather than a single figure for the whole job.

Paperwork you can actually rely on

Good installation and good paperwork should come together. Every job we complete is certified, guaranteed in writing and backed by an IWA insurance backed guarantee, and we hand you the documents rather than leaving you to chase them. If you are getting quotes for replacement double glazing or composite doors, compare the paperwork as carefully as the price.

Thinking about upgrading your windows, doors, conservatory, roofline or garden room?

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Serving Wirral, Chester and Cheshire.

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