Quick answer: An Insurance-Backed Guarantee (IBG) is a third-party insurance policy that pays for warranty work if your installer goes out of business. It’s typically included in the install price (£25–£75 of the total), runs for 10 years, and covers the same defects as the installer’s own warranty. The two main UK providers are Installsure and QANW. Without an IBG, your “10-year warranty” is worth whatever the installer is worth — which can be nothing, as Safestyle UK and Everest customers found out the hard way.
What an IBG actually is
When you buy double glazing, the installer gives you a written warranty — usually 10 years on the frame, 5–10 years on the sealed unit. That warranty is a contractual promise from that specific company. It’s only worth anything if the company is still around when you need to claim.
An Insurance-Backed Guarantee is a separate insurance policy, taken out on your behalf by the installer (and paid for by them as part of your job cost), that continues to cover you even if the installer goes bust. The insurer takes over the warranty obligation.
- Cost: typically £25–£75 per project — almost always built into the price; you should never be quoted as an extra
- Length: usually 10 years from install date
- Cover scope: matches the installer’s own warranty, but operated by the insurer if needed
- Claim limit: usually capped at the original installation value
Why IBGs matter much more than 5 years ago
Several major UK installers have entered administration in the last few years:
- Safestyle UK — entered administration October 2023; trading was wound down. Anglian Home Improvements bought the brand assets but does not honour pre-administration warranties for free unless you have an IBG.
- Everest Home Improvements — entered administration twice in the last decade (2020 and again under a separate restructuring). Anglian acquired the brand in 2024.
- Multiple regional installers have failed during 2023–2025 as raw-material costs and consumer demand fluctuated.
For customers with no IBG, the company-issued warranty was worthless from day one of administration. For customers with a valid IBG, the warranty is honoured by the insurer for the full 10-year term. The IBG is the only protection that survives a company failure.
The two main UK providers
| Installsure | QANW | |
|---|---|---|
| Formerly known as | GGFi (until 2018) | Quality Assured National Warranties |
| Affiliated with | Glass & Glazing Federation (GGF) | Independent |
| Used by | Most FENSA-registered installers; Anglian, Everest (post-2024) | Many independents and CertAss-registered installers |
| Cover length | Up to 10 years | Up to 10 years |
| Underwriter | Suresure Insurance Services | HCC International (a Tokio Marine brand) |
| FCA-regulated | Yes | Yes |
Both are reputable, FCA-regulated, and broadly equivalent for consumer purposes. The differences in claim experience are minor.
What an IBG typically covers
- Sealed glass unit failure (misting, condensation between panes — see our condensation guide)
- Frame defects — warping, cracking, frame distortion not caused by impact
- Hardware failure within the warranty period — hinges, locks, handles
- Failed seals around the perimeter causing draughts (when the cause is the original install, not subsequent damage)
- Workmanship defects traceable to the original install
What an IBG does NOT cover
- Normal wear and tear (gaskets that have aged out — see our draughty windows guide)
- Accidental damage — broken glass from impacts, kids, weather
- Cosmetic issues like minor surface scratches or discolouration over time
- Damage from poor maintenance — pressure-washing, painting with the wrong paint, blocked drainage holes
- Issues outside the original install scope — e.g. a problem with a window that wasn’t part of the original job
- Issues already known before install (frame distortion that existed before they fitted the unit)
- Building Regs non-compliance — if your install never met regs (e.g. missing trickle vents), the IBG can decline cover
How to verify your IBG is genuine
You should receive an IBG certificate within 30 days of the install completing — usually emailed or posted, often included with the FENSA certificate. The certificate must show:
- Your name and full installation address
- Original installer name + their FENSA / CertAss / TrustMark number
- Install date and warranty period
- The insurer’s name and policy number
- A claims contact phone or email at the insurer (NOT the installer)
Verify it directly with the insurer. Don’t trust just the installer’s word. Both Installsure and QANW have customer-facing phone lines and email addresses where you can confirm the policy number is real and active.
If you can’t find the certificate, contact the installer first. If they’ve gone out of business, contact the insurer directly with your install date, address, and FENSA certificate number — they can usually find the policy from those details.
Red flags before signing
- Installer says “we don’t do IBGs — our warranty is enough.” Walk away. The whole point of an IBG is that “their warranty” stops existing the day they go bust.
- “IBG is an extra £200.” Real IBGs are £25–£75 per project and almost always built into the price. £200 is a markup or a different (possibly worse) product.
- “It’s a ‘self-insured’ guarantee.” A “self-insured guarantee” is just the company’s own warranty rebranded — same risk if they fail. Real IBGs are FCA-regulated insurance products from a separate company.
- The certificate doesn’t arrive within 30 days. Chase. If it never arrives, the IBG was probably never set up.
- The certificate doesn’t name a real insurer (Installsure, QANW, or another FCA-regulated underwriter). Treat as not having one.
Comparison: with IBG vs without
| Scenario | With IBG | Without IBG |
|---|---|---|
| Sealed unit fails year 7, installer trading fine | Installer fixes; IBG not needed | Installer fixes — same result |
| Sealed unit fails year 7, installer in administration | Insurer arranges fix at no cost | £40–£600 out of pocket |
| Frame warping year 4, installer disputes liability | You can escalate to insurer if installer refuses | Small claims court only option |
| Selling year 5, buyer’s solicitor checks | Property sale unaffected — IBG transfers | May trigger indemnity insurance requirement |
Frequently asked questions
Is an IBG required by law?
No — Building Regs don’t require IBGs. But FENSA, CertAss, GGF and TrustMark all require their member installers to offer one, and a quote without an IBG is a sign of a non-compliant installer.
Does the IBG transfer to a new homeowner?
Yes — both Installsure and QANW policies are tied to the property, not the original buyer. When you sell, the IBG transfers automatically (no admin needed) and runs to the original 10-year end date.
Can I buy an IBG retrospectively if my install didn’t have one?
Generally no — IBGs must be issued within a short window of install completion. Some installers can backdate a few months if the original paperwork was missed but you can’t add IBG cover to a 5-year-old install.
What happens if both the installer AND the insurer go bust?
Both Installsure and QANW are FCA-regulated, which means policies are protected by the Financial Services Compensation Scheme (FSCS). FSCS covers up to 90% of a valid claim if the insurer fails. So even in the worst case, you’re not at zero protection.
My IBG is from “GGFi” — is that still valid?
Yes. GGFi rebranded to Installsure in 2018; existing GGFi certificates remain valid for their full term. Use the Installsure customer line to make claims on old GGFi policies.
Are there cheaper alternatives to a real IBG?
“Deposit Protection” schemes are sometimes offered as alternatives — these only cover your deposit if the company fails before completing the install, not the long-term warranty. Useful for new orders but not a substitute for an IBG. Always have both: deposit protection until install, then IBG for the long-term warranty.
Get quotes from installers with proper IBG cover
Our quote service only matches you with FENSA-registered installers who offer either Installsure or QANW insurance-backed guarantees as standard. We drop installers from our network if they push back when challenged on IBGs. Free, no obligation, no pressure.
For more on what to verify before signing any glazing contract: Before You Sign A Double Glazing Contract · FENSA vs Certass vs TrustMark explained
Sources: Installsure consumer information (installsure.co.uk, 2026), QANW policy documentation, GGF Insurance-Backed Guarantee guidance, FENSA homeowner protection pages, Financial Services Compensation Scheme glazing IBG cover (2026), FCA register for Suresure Insurance Services and HCC International. Anglian acquisition of Safestyle (Interpath Advisory, October 2023), Anglian acquisition of Everest brand (May 2024). Last reviewed: April 2026.
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