An insurance backed guarantee (IBG) protects the installer's written guarantee on your new windows or doors if the company stops trading. It is a separate document from the FENSA certificate, which shows the work meets building regulations, and it sits alongside your legal rights under the Consumer Rights Act 2015. Before you sign, check who the insurer is, how long cover lasts, what it excludes, and whether your deposit is protected too.
Every window company promises a guarantee. Long guarantee periods are common in quotes. But a guarantee is only a promise from the company that gave it, and it is only as good as that company's ability to honour it. If the firm closes in year three, a ten-year guarantee from it may be worth very little on its own.
That is the gap an insurance backed window guarantee is designed to fill. This guide explains how it works, how it fits with your FENSA certificate and your statutory rights, and what to check in the paperwork. It draws on guidance from FENSA, the Planning Portal and Citizens Advice, with one Leicester installer used as a worked example based on what it publishes online.
Three different kinds of protection
Window paperwork is confusing because several documents sound alike. Here is how they differ:
| Document or right | Who provides it | What it does | What it does not do |
|---|---|---|---|
| Installer's written guarantee | The installer | Promises to fix covered faults for a stated period | Cannot be honoured if the installer stops trading |
| Insurance backed guarantee (IBG) | An insurer, usually arranged through a broker | Covers the installer's written guarantee if the installer ceases to trade | Does not normally add cover beyond the original guarantee terms |
| FENSA or other compliance certificate | A competent person scheme | Shows the installation meets building regulations and is registered with the council | FENSA says it does not issue guarantees |
| Consumer Rights Act 2015 | The law | Requires services to be carried out with reasonable care and skill | Depends on the trader still being there to put things right |
What FENSA says about insurance backed guarantees
FENSA's homeowner guidance is the clearest official explanation. It says that if your installation was completed after 2014, you may have received an insurance backed guarantee policy, also known as a warranty insurance policy. It is separate from the FENSA certificate, issued by an insurance broker, and covers the installer's written guarantee if they cease to trade.
FENSA adds that installations completed in 2013 or earlier may not have an IBG, because these were not mandatory until 2014. If you cannot find your policy, it may be able to help you find the broker's details, and you should contact the broker directly to make a claim. Without a policy, FENSA warns, you are likely to have to pay for any remedial work yourself.
FENSA also lists "verifies your installer's guarantee is insured" among the reasons a FENSA certificate matters, which is why the two documents usually arrive together.
Why the building regulations certificate matters too
The Planning Portal says building regulations have applied to all replacement glazing since 1 April 2002, covering thermal performance, safety, air supply, means of escape and ventilation. Using an installer registered with a competent person scheme means the work can be self-certified, and you receive a certificate when it is complete. If you use an unregistered installer, you need approval from a building control body instead.
FENSA notes that it is the homeowner's responsibility to make sure an installation is registered with the local council. You will usually be asked for this certificate when you sell your home, so file it with your guarantee.
A local example of how it is presented
Some installers now spell out their protection on their own websites. URG Windows & Doors in Leicester, for example, says every job it does is covered by Home Improvement Protection, describing three parts: the deposit is protected, the guarantee is insurance-backed and stands even if the firm is no longer trading, and there is a free independent route to resolve disputes. It also lists itself as a FENSA Approved Installer, giving its registration number so customers can check it on the FENSA site.
That three-part structure is a useful checklist for any quote: protection for your money before the work, protection for the guarantee after it, and a way to resolve problems without going to court.
Seven things to check before you sign
- The insurer's name. Ask who provides the policy and who the broker is. A real policy has a named insurer.
- When you receive the policy. You should get a policy document or certificate in your own name after installation. Ask when it will arrive.
- How long it lasts. Check that the insurance period matches the length of the written guarantee.
- What is excluded. Read the guarantee terms for exclusions such as misuse, unauthorised alterations or wear and tear. The insurance usually follows those terms.
- Deposit protection. An IBG protects the guarantee after the job. Ask separately whether your deposit is protected if the firm fails before fitting.
- The compliance certificate. Confirm the installer is registered with FENSA or another competent person scheme, and check the registration yourself.
- The complaints route. Ask what happens if you disagree about a fault. FENSA recommends contacting your local Trading Standards office if an installer is not honouring its guarantee and you have used its complaints process.
Your rights under the Consumer Rights Act
An insurance backed guarantee adds to your legal rights rather than replacing them. Under section 49 of the Consumer Rights Act 2015, every contract to supply a service includes a term that the trader must perform it with reasonable care and skill. Citizens Advice explains how to ask a trader to put right poor work. Keep your contract, quote, invoices, photos and guarantee papers together, because you will need them for any claim.
FENSA also points out that any extra work by another installer could affect your guarantee, so check before you let someone else alter windows or doors that are still under guarantee.
Frequently asked questions
Is an insurance backed guarantee the same as a FENSA certificate?
No. FENSA says the IBG is a separate policy issued through an insurance broker, while the FENSA certificate shows building regulations compliance.
Do all window installers have to provide one?
FENSA says IBGs were not mandatory until 2014, so older installations may not have one. Ask any installer to confirm in writing that your job will be covered.
What if the installer is still trading but will not fix a fault?
Use the installer's complaints process first. FENSA suggests contacting Trading Standards if that fails.
Where do I find my policy?
Check your installation paperwork. If you cannot find it, FENSA may help you identify the broker.
Sources
- FENSA: Homeowners
- Planning Portal: Doors and windows building regulations
- GOV.UK: Competent person schemes
- Consumer Rights Act 2015
- Citizens Advice: Problem with building work or home improvements
General information only, not legal advice. Details were checked in October 2026; read your own policy and guarantee terms, and check details directly with any installer.