20 questions to ask a builder before you hire them

The questions to ask a builder before hiring them cover seven areas: their track record, who actually does the work, insurance and certification, the quote itself, payment terms, how problems get handled, and what happens after they finish. Twenty questions, asked at the first meeting, reveal more than any review page.

Good builders answer all of these comfortably, because they've been asked them a hundred times. Hesitation, vagueness or irritation is itself an answer. They sit inside the bigger job of finding a good builder in London; here they are, grouped by what they actually tell you.

What should you ask about their track record?

Ask what similar projects they've completed recently, whether you can speak to those clients, and whether you can see a current or recently finished site. Recent, relevant, checkable work is the strongest evidence a builder can offer.

What projects like mine have you finished in the last year? Like yours matters: a brilliant bathroom fitter isn't automatically the right lead for a structural renovation.

Can I speak to two or three of those clients? Then actually call them, and ask what went wrong, not just what went right. Every project hits problems; you're listening for how they were handled.

Can I visit a live or recent site? A tidy, organised site with protected floors and sequenced trades tells you more than a portfolio ever will.

How long have you been trading under this company name? Cross-check on Companies House. A long, unbroken history matters; serial dissolutions with the same faces behind new names are the classic pattern of builders who fold to escape liabilities.

What should you ask about who does the work?

Ask who will be on site day to day, which trades are employed versus subcontracted, and how many other projects run alongside yours. The person quoting is often not the person building.

Who is on site each day, and who supervises? You want a name, not a shrug.

Which trades are in-house and which are subbed out? Subcontracting is normal; not knowing who their electrician is, isn't.

How many other jobs will you be running at the same time? Overstretched builders create the classic stop-start project.

Who do I contact when I have a question, and how quickly do you respond? Agree the communication channel before it's tested by a problem.

What should you ask about insurance and certification?

Ask for proof of public liability insurance, employer's liability if they have staff, and the certifications behind gas and electrical work. Documents, not assurances.

Can I see your public liability certificate? £2 million is the sensible minimum for residential work, and check the dates.

Who certificates the electrical work? Notifiable work needs a qualified electrician registered with a competent person scheme, whether in-house or subbed.

Who does the gas work? Gas Safe registration, checkable on the register, no exceptions.

Will I get building control sign-off and certificates at the end? Completion certificates, electrical certificates and gas records are what your buyer's solicitor asks for years later.

What should you ask about the quote?

Ask whether the price is a fixed quote or an estimate, what exactly it includes and excludes, and how changes get priced once work starts. Most disputes are born in a vague quote.

Is this a fixed quote or an estimate? They're legally and practically different things. A single figure on one page is an estimate wearing a quote's clothing.

What's excluded? Skips, scaffolding, making good, decoration and VAT are the usual quiet omissions.

How do you price variations? Agreed day rates or itemised pricing for changes, in writing, before the first change happens.

How long is the quote valid, and when could you start? Instant availability from a good builder is rare; London's best are booked weeks or months out. Our guide to getting builder quotes covers how to make quotes genuinely comparable.

What should you ask about payment?

Ask what deposit they expect, how payments are staged, and whether they'll work to a milestone schedule where money follows completed work. How a builder wants paying tells you a lot about how they run.

What deposit do you ask for? 5 to 10% for materials on smaller jobs is reasonable; a demand for 25% or more before anyone lifts a tool is a warning.

Can we agree a milestone payment schedule? Staged payments tied to signed-off work protect both sides; it's how construction payments work on every Beams project, with funds held securely and released stage by stage.

What should you ask about problems and afterwards?

Ask what happens when something goes wrong mid-project, and what warranty covers the work once they've left. The last two questions are the ones people most regret skipping.

What happens if we disagree mid-project? You're listening for a process: written variations, a contract with a dispute route, not "we'll sort it out". A proper home improvement contract puts that process in writing before it's needed.

What warranty do you give on your workmanship, and is it written down? Twelve months on workmanship is a reasonable baseline; every Beams builder provides it as standard, backed by up to £10,000 of cover from Beams if that builder ever leaves the network.

Or skip the interrogation altogether

Twenty questions is what proper vetting takes when you're doing it alone. The alternative is starting with builders who've already answered them: Beams' builder vetting visits every builder in person, checks references, verifies insurance and inspects recent work before they join, then they quote against a detailed scope with contracts, payments and cover built in. Get a free estimate and meet up to three of them.

Where this guidance comes from

These questions reflect independent UK consumer and industry guidance rather than Beams' commercial terms: hiring guidance from the Federation of Master Builders, the government-endorsed TrustMark scheme, the HomeOwners Alliance, and Citizens Advice on consumer rights around building work.

Sources

1. Federation of Master Builders, hiring a builder: https://www.fmb.org.uk
2. TrustMark, government-endorsed quality scheme: https://www.trustmark.org.uk
3. HomeOwners Alliance, builder guidance: https://hoa.org.uk
4. Citizens Advice, problems with building work: https://www.citizensadvice.org.uk
5. Gas Safe Register: https://www.gassaferegister.co.uk