If a Window Quote Does These Five Things, Slow Down

Getting a window quote should feel roughly like buying a sofa: a bit tedious, mildly expensive, ultimately straightforward. Unfortunately, the double-glazing trade has earned its reputation for a reason, and a minority of firms still lean on the same old tricks.

None of these red flags is automatically a dealbreaker on its own. But two or three in the same conversation? Time to get another quote.

1. The energy rating that appears without context

"A-rated windows, all in, no messing." Fine — but A-rated to what standard, tested by whom, and is that the glass or the whole window?

What to ask: "Can you email me the BFRC certificate for the exact window you're quoting, including the frame and glazing spec?"

A good answer sounds like: "Of course, I'll send it this afternoon — the U-value is 1.3 for the whole window, and the g-value is 0.63 if you want solar gain."

Walk away if: they wave a brochure with a rainbow label, can't name the certification body, and get vaguely irritated by the question. If they can't evidence the rating, they're selling you a colour, not a window.

2. Silence on FENSA, CERTASS or Building Regs

Replacement windows in England and Wales are notifiable under Building Regulations. Registered installers self-certify through a Competent Person Scheme such as FENSA or CERTASS, and you should receive a certificate afterwards. There are narrow exceptions — some like-for-like repairs don't need notification — but a decent firm can explain them in a sentence.

What to ask: "Are you registered with a Competent Person Scheme, what's your registration number, and will you notify the work and send me the certificate?"

A good answer sounds like: "Yes, we're FENSA registered, the number's on the quote, and the compliance certificate goes out a few weeks after completion."

Walk away if: you get a shrug and a "don't worry, we've been doing this for years". Being in business a long time is not the same thing as being legally compliant, and a missing certificate can bite you when you sell the house.

3. A chunky deposit demanded before anyone has measured up

A proper survey should happen before significant money changes hands. A deposit is normal — usually in the 20–30% region, sometimes less — with the balance due once you've inspected the finished job.

What to ask: "How much deposit are you asking for, when is it due, and is it protected if something happens to the company?"

A good answer sounds like: "Twenty-five per cent after survey, balance on completion, deposit protected through our insurance-backed scheme."

Walk away if: they want half the money upfront on the day you sign, prefer cash, or dangle a discount that mysteriously expires at midnight. Pressure around payment is one of the oldest tricks in the book, and it's rarely the mark of a firm with a healthy order book.

4. A guarantee that's long on years and short on names

"Twenty-five year guarantee!" is a lovely sentence until you ask who's actually standing behind it. A guarantee is only as good as the company — or the insurer — backing it when year fifteen rolls around.

What to ask: "What's covered, what's excluded, how long does each part last — glass, hardware, frame, labour — and is the workmanship guarantee insurance-backed?"

A good answer sounds like: "Ten years on frames and hardware, twenty-five on the sealed unit against misting, ten on installation labour, and the workmanship side is insurance-backed with the paperwork included."

Walk away if: the guarantee is a verbal promise, the paperwork never materialises, or the only reassurance is "we're a family firm, we'll still be here". Family firms are lovely. Written, insured terms are better.

5. Pressure tactics and vanishing discounts

If a contract is signed in your home, the Consumer Contracts Regulations 2013 generally give you a 14-day cooling-off period. Any salesperson who discourages you from using it is telling you something about their business model.

What to ask: "Can I take the quote away in writing and come back to you next week?"

A good answer sounds like: "Definitely — everything's itemised, have a read, ring me if you've got questions. The price is the price for thirty days."

Walk away if: the salesperson won't leave without a signature, the discount is "only valid while I'm sat here", or you're offered a deal for signing on the spot without a survey. A real installer wants to measure before committing to a figure anyway.

What a properly good quote looks like

It's boring, and that's the point. A decent quote typically runs to several pages and itemises each window separately, with the frame spec, glazing spec, whole-window U-value, WER band, spacer bar type, trickle vents, fitting costs, making good, old-window disposal, VAT, lead time, payment schedule, guarantee terms and the FENSA or CERTASS registration number.

Three quotes from three different firms, lined up side by side, will tell you more than any single glossy brochure. You'll quickly see who is answering the questions and who is hoping you won't ask them.

When to walk

Walking away costs nothing and there are thousands of installers across the UK. If two or more of the red flags above show up, or if you simply feel talked-at rather than talked-with, get another quote. The best value in double glazing almost never comes from the firm applying the most pressure.

The dull, detailed, question-friendly quote is usually the one that ends up being the cheapest in the long run.