Window guarantees & warranties explained

A guarantee is only as good as the company standing behind it. Understanding the different types of cover — and what happens if an installer stops trading — helps you judge a quote on more than just price.

Product versus workmanship

Two different things are usually covered. The product guarantee covers the windows themselves — frames, sealed units and hardware — against defects such as discolouration, faulty mechanisms or a failed sealed unit that mists up. The workmanship guarantee covers the quality of the installation: fixings, seals and weatherproofing. A common arrangement is around ten years on both, though terms vary, so read exactly what is included and for how long. Ask whether the guarantee is transferable if you sell the house, as this can be a selling point.

Why insurance-backed guarantees matter

A guarantee from the installer is worthless if that installer ceases trading — which is where an insurance-backed guarantee (IBG) comes in. An IBG is a separate policy from an independent insurer that steps in to honour the terms of your guarantee if the original company is no longer around. Because windows should last decades, this protection is genuinely valuable. Always check that the IBG is provided, that you receive the certificate, and how long it runs.

Protecting your deposit

Many installers ask for a deposit before manufacturing begins. Deposit protection — whether through a scheme, insurance or paying by credit card — safeguards that money if the firm fails before the work is done. Paying larger amounts by credit card can add protection under Section 75 of the Consumer Credit Act for eligible transactions. Be cautious of any installer asking for a very large deposit in cash with no protection in place.

What to check before you sign

Get every promise in writing. Confirm the length and scope of both guarantees, whether an insurance-backed guarantee is included, how deposits are protected, and the process for reporting a problem and how quickly the installer will respond. Keep the paperwork with your FENSA or CERTASS certificate — you will want both if you ever make a claim or sell the property. Cross-check this against the firm’s accreditations covered in our guide to choosing an installer.