Ask Before the Kettle Boils: Seven Questions That Separate a Good Window Installer from a Good Talker

The quote is on the kitchen table. The person who measured up was pleasant, didn’t tread mud through the hall, and said all the right things about U-values and sightlines. None of that is proof of anything.

Replacing windows is a big, dusty, once-in-a-generation purchase for most St Clement homes. The difference between a dependable firm and a smooth talker rarely shows up in the brochure. It shows up in the answers to a few direct questions — asked before you sign, preferably while the kettle is still warm.

Here are seven to keep on your phone or the back of an envelope.

1. “How long is the guarantee — and what does it actually cover?”

“Ten years” is a headline, not an answer. Ask what part carries which guarantee: the frames, the glass units, the locks and hinges, the labour, the fitting itself. A 10-year frame warranty with a two-year labour promise is a different animal from a whole-installation guarantee.

Ask for it in writing, with the start date and whether it transfers if you sell the house. Also ask what voids it — accidental damage, painted-over gaskets, a conservatory that’s been altered. A straightforward firm will have a one-page summary and no problem sending it.

2. “Is the guarantee insurance-backed — and who backs it?”

A guarantee is only as good as the company standing behind it. If that company stops trading, an insurance-backed guarantee (often called an IBG) can be the difference between a repaired window and a sorry story.

Ask for the name of the insurer or scheme provider, the policy document, and what you have to do to register. A logo on a leaflet is not the same as a policy in your name. While you’re there, ask how your deposit is protected. On a typical St Clement replacement job, a deposit is often a few hundred to a couple of thousand pounds — worth a paper trail.

3. “Are you FENSA or CERTASS registered — and will I get the certificate?”

Replacement windows are controlled work. In England and Wales, the installer should be able to self-certify compliance with the Building Regulations through a competent person scheme such as FENSA or CERTASS, or you’ll need a separate building control application. Ask for the registration number and check it on the scheme’s website — it takes two minutes.

Then ask when the certificate arrives. You’ll want it if you sell, and it’s evidence that the glass, ventilation and safety glazing were signed off properly. A firm that huffs at this question is telling you something.

4. “Can I see two recent jobs near me — and speak to those customers?”

A gallery of gleaming bay windows could have been photographed anywhere. Local references are better. Ask for a couple of recent jobs in St Clement or the nearby streets, and whether you can knock on the door or ring the homeowner.

Good installers are usually proud to point to their work. Listen for the small stuff: did they turn up when they said, how did they treat the garden, did they come back for the sticking handle? One glowing review is nice; two honest conversations are better.

5. “Who surveys my windows, and when?”

There’s a difference between a sales visit and a technical survey. Ask who will do the survey, what they check, and whether it happens before or after you sign. A proper survey looks at openings, lintels, sills, drainage, ventilation, access and how the new frames will meet the old walls. It is not just a second measurement.

If the survey only happens after a deposit has changed hands, ask why. You want the awkward discoveries — a rotten lintel, a wonky opening, a gas flue too close to an opener — found before the contract, not on fitting day.

6. “What happens if something isn’t right after fitting?”

Every installation has a snag list: a handle that needs adjusting, a trickle vent that whistles, a sealed unit that mists up a few months later. Ask how you report it, who answers the phone, and what response time they aim for.

Ask whether the fitter comes back or whether it goes through an office, and what happens out of hours. A dependable firm will have a boring, clear process. A vague “give us a ring and we’ll sort it” is not a process; it’s a hope.

7. “What exactly am I signing, paying, and when?”

Before the pen comes out, ask for the full contract and cancellation terms by email. Check the deposit, the staged payments, the start date, the expected number of days on site, and who will actually be doing the work — their own fitters or subcontractors.

Ask what’s included: scaffolding, making good, waste removal, curtain pole refitting, VAT. Ask what isn’t. And remember you’ll usually have a 14-day cooling-off period for a contract agreed at home, so don’t be rushed into waiving it.

The doorstep test, in one line

A good installer answers these questions plainly, sends the paperwork, and doesn’t mind you checking. A poor one deflects, dazzles with jargon, or offers a discount that expires before you’ve had time to think.

You’re not being difficult. You’re being a neighbour who plans to stay put. Ask before the kettle boils, and the rest of the job tends to go a lot more smoothly.