How to Choose a Double Glazing Installer (Checklist)

The installer matters as much as the windows. A great product fitted badly will leak and fail; a solid product fitted well will last decades. Use this checklist before you sign anything.

Check accreditations

Confirm FENSA (or another Competent Person Scheme) registration, and look for an insurance-backed guarantee so your warranty survives if the firm doesn’t. Membership of the Glass and Glazing Federation is a further good sign.

Compare like-for-like quotes

Get at least three quotes for the same specification — profile, glass U-value, colour, hardware and guarantee — so you’re comparing fairly. Be wary of “today only” discounts and inflated “was” prices.

Read real reviews

Look for recent, local reviews and ask to see examples of similar work. Independent, family-run firms often live or die by word of mouth, which keeps standards high.

Questions to ask

• What U-value / WER will the windows achieve?
• Who fits them — employed fitters or subcontractors?
• What’s covered by the guarantee, and is it insurance-backed?
• How is mess and “making good” handled?

Every firm in our directory shows its accreditations and area. Browse local installers or get matched to up to five and compare.

Frequently asked questions

How many quotes should I get?

Three is the sweet spot — enough to spot an outlier, not so many it’s overwhelming.

Are national brands better than local firms?

Not inherently — independent local installers often offer keener pricing and direct accountability. Judge each on accreditation, reviews and quote.