Guarantees & what they cover
A long guarantee sounds reassuring, but the detail matters more than the number of years. Here is the window guarantee explained — what is covered, who stands behind it and what to check before you sign.
Product versus workmanship cover
Most quotes bundle two different guarantees, and it helps to separate them. The product guarantee covers the windows themselves — faults such as failed sealed units that mist up, discoloured frames or faulty hardware. The workmanship guarantee covers the installation: leaks, draughts or units that were not fitted correctly. A firm might advertise “10 years” but apply that only to the product, with a shorter period on the fitting, so ask what each covers.
What a guarantee typically excludes
Guarantees rarely cover everything. Common exclusions include accidental damage, misuse, condensation caused by lifestyle rather than a unit failure, and normal wear on moving parts. Some require you to register the guarantee within a set time or to have the windows serviced. None of this is unusual, but you want to read the terms so there are no surprises if you need to claim later.
Compare the cover, not just the years
Get free, no-obligation quotes from vetted local installers and check the guarantee terms side by side. Subject to eligibility and a home survey.
Get into the quote zone →Why insurance-backed guarantees matter
A guarantee from the installer is only worth anything while that installer is trading. An insurance-backed guarantee (IBG) is a separate policy that steps in if the company ceases trading, so your cover survives even if the firm does not. For a purchase you expect to last decades, an IBG is a meaningful protection — check whether it is included, how long it runs and who the underwriter is.
Accreditations and building regulations
Replacement windows must meet building regulations, and most installers self-certify through a competent-person scheme such as FENSA or CERTASS. This gives you a compliance certificate — which you will need when you sell — and often ties into a guarantee or deposit-protection scheme. Membership of a scheme, plus TrustMark registration, is a good sign a firm takes its obligations seriously.
The guarantee sits alongside your deposits and payment terms as the commercial protection on a quote, and it is a big part of spotting a fair window quote. Before you commit, it is worth vetting your installer before you commit and reading verified feedback there.
Check who stands behind the work
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