Reviews help, but they’re not enough. Choosing a builder well means looking past the headline figures and asking questions that reveal how someone actually runs a project — not just whether their previous clients were happy. The right choice isn’t the cheapest quote or the best-reviewed name on a search result; it’s the builder whose approach and capability match what your specific project needs.

Key takeaways

• Relevant experience on comparable projects matters more than years in the trade or volume of reviews
• Communication style in the early stages is a reliable indicator of how the project will run
• Clear, itemised quotes reveal how well a builder understands the scope — vague ones don’t
• Red flags are usually visible before you sign anything: vague pricing, pressure to decide quickly, and overpromised timelines are all worth taking seriously
• You’re choosing how the whole project will be managed, not just a price

Relevant experience

A builder who has done twenty bathroom renovations is not automatically the right choice for a structural extension. A builder who specialises in new builds may not have the experience to work sensitively in an older Cornish stone property. Experience in the trade matters — but the specific type of experience matters more.

When you’re speaking to builders about your project, ask directly: have they done this kind of work before? Not generally — specifically. A rear extension with structural steelwork and bifold doors is a different project from a new-build timber-frame. A listed building requires a different approach from a standard renovation. A builder who can point to completed projects that genuinely resemble yours — and who can give you contact details for the clients — is in a fundamentally different position from one who suggests their general experience qualifies them for anything.

Ask to see examples of comparable work. Ask how long ago the work was done. Ask what the challenges were and how they were handled. The answers reveal both experience and honesty — a builder who can describe the problems they encountered and how they resolved them is telling you something useful. One who suggests nothing went wrong on any project probably isn’t.

What the quote tells you

A quote is not just a price — it’s a document that reveals how well a builder understands your project and how clearly they communicate. The detail, or lack of it, is informative.

An itemised quote that breaks down labour and materials by trade, identifies provisional sums clearly, lists exclusions explicitly, and specifies the assumptions behind the figure is produced by someone who has thought the job through. A lump-sum quote with a single total, minimal description, and no breakdown is much harder to hold to and much easier to dispute.

When comparing quotes, look at what’s included and excluded before you look at the total. Two quotes for the same project can differ by 20–30% and still be pricing different things. The cheapest quote on the page is often the one that’s excluded the most — or the one that has understated provisional sums that will increase once work starts.

Ask each builder to walk through their quote with you. How they respond to that request is itself informative. A builder who is comfortable explaining the detail and who can answer questions clearly is likely to communicate the same way throughout the project. One who deflects, becomes vague, or can’t explain individual line items is flagging a communication problem early.

Communication style

Building projects run over months, involve constant decision-making, and require a working relationship between the homeowner and the builder that functions well under pressure. The quality of that relationship is one of the most significant variables in whether a project goes smoothly — and the early stages of contact give you genuine information about what it will be like.

A builder who responds promptly, asks sensible questions about your brief, communicates clearly about their availability and process, and treats early conversations as a genuine exchange is demonstrating something real. One who is hard to reach, provides vague responses to specific questions, or treats early contact as an obstacle to getting to the price is showing you something equally real.

Pay attention to how questions are answered. If you ask about a specific aspect of the project — the foundation approach, how they handle a particular detail — a knowledgeable builder will give you a clear answer or tell you honestly that they’d need to open up the site to be certain. An evasive or overconfident response to a question that genuinely requires more information should make you cautious.

This matters because problems occur on every building project. The question is not whether something will go wrong — it’s how it will be handled when it does. A builder who communicates clearly and honestly when things are easy is far more likely to do the same when something difficult arises.

References and completed work

Reviews on a website or third-party platform are a starting point, not a conclusion. They’re self-selected, often written immediately after completion before any defects have emerged, and they rarely describe what happened when something went wrong.

More useful is speaking directly to clients whose projects resemble yours. Ask the builder for two or three references — specifically from projects similar to what you’re commissioning — and actually call them. The questions worth asking: did the project finish on time and on budget? Were there variations, and how were they handled? How did the builder communicate during the project? Would you use them again?

If a builder can’t or won’t provide references, treat that as a meaningful signal. Builders with strong track records are generally confident about putting previous clients in contact with prospective ones.

Where possible, visit a completed project. Photographs don’t show the quality of junctions, the finish around windows and doors, the levelness of floors, or the care taken on details that aren’t in the hero shot. Being in a space that a builder has delivered gives you a different quality of information.

Trade membership and insurance

Membership of a recognised trade body — the Federation of Master Builders, TrustMark, or the National Federation of Builders — is not a guarantee of quality, but it does indicate that the builder has met minimum criteria, carries appropriate insurance, and has agreed to a code of conduct that includes a dispute resolution process.

For most residential projects, the minimum insurance to verify is public liability cover — typically £2m to £5m — and employer’s liability if the builder has direct employees. Ask to see the certificate rather than taking it on trust. A reputable builder will have no hesitation providing it.

On projects involving structural work or more complex builds, checking whether the builder carries professional indemnity insurance and whether they work with approved structural engineers and building control is also worthwhile.

The Federation of Master Builders is particularly useful as a reference in the domestic sector. FMB members are vetted, carry appropriate insurance, and have access to a consumer protection scheme. The FMB also produces a standard domestic building contract that most reputable builders in the domestic sector will be familiar with.

Red flags

Most problems with building projects are foreseeable. The signals are usually there before anything is signed, and they’re worth taking seriously.

Vague or lump-sum pricing. A quote that can’t be broken down is a quote that can’t be held to. It creates the conditions for disputes about what was included. Ask for a breakdown — and if the builder won’t or can’t provide one, ask yourself why.

Prices that are significantly below everyone else. Not all builders have the same overheads, and genuine efficiency exists. But a quote that is 30% or more below others for an apparently equivalent scope is almost always explained by something: less included, understated provisional sums, unrealistic programme, or a builder pricing to win the work with the expectation of recovering margin through variations. Ask the question directly; the explanation will either reassure you or confirm the concern.

Overpromised timelines. A builder who tells you what you want to hear about when the project will start and finish, without having seen the site properly or assessed the programme realistically, is optimistic at best. Ask how they arrived at the timeline. A credible answer involves the programme stages, trade sequencing, and any known dependencies. A vague answer doesn’t.

Pressure to commit quickly. “I’ve got a gap in my schedule that I can give you, but only if you confirm this week” is a sales technique. A builder with a genuine gap in their programme doesn’t need to pressure you into filling it. A well-run builder with forward bookings has a clear pipeline and no need to push.

Reluctance to put things in writing. Verbal agreements, handshake deals, and informally agreed variations are where most building disputes originate. A builder who is uncomfortable with written contracts, written variations, or written confirmation of what’s agreed is creating conditions for problems.

The question to ask yourself

After meeting a builder and reading their quote, ask yourself one question: if something goes wrong on this project — as something will — do I believe this person will communicate with me clearly, take responsibility where it’s theirs to take, and work with me to resolve it?

That’s ultimately what you’re choosing. Not a price, not a schedule, not a list of completed jobs. A person and a working relationship that will be tested by time, pressure, and the unpredictability that comes with building work. The early stages of contact are the best information you have about what that relationship will look like.

Frequently asked questions

How many builders should I get quotes from?

Three is the standard recommendation for most residential projects. It’s enough to establish whether any quote is an outlier in either direction, and to compare scope and approach without asking builders to invest disproportionate time in quotes they have no realistic chance of winning. For straightforward smaller projects, two quotes may be sufficient.

Should I always choose the cheapest builder?

No. The cheapest quote is often cheapest because less has been included, provisional sums are understated, or the programme is unrealistic. Compare quotes on scope first, then price. A quote that’s genuinely cheaper because the builder is more efficient or has lower overheads is worth taking seriously — but a quote that’s cheaper because it’s missing something is not.

What should a building contract include?

At minimum: scope of works, programme, payment schedule (stage payments tied to work completion rather than upfront lump sums), how variations are agreed and priced, what happens in the event of delay, and the defects liability period. The Federation of Master Builders produces a plain-English domestic building contract appropriate for most home renovation and extension projects.

How do I know if a builder is legitimate?

Check trade body membership (FMB, TrustMark, NFB), ask to see current public liability insurance, request references from comparable recent projects and follow them up, and search Companies House if the business is registered as a limited company. A builder who is reluctant to provide any of these should be treated with caution.

What is a defects liability period?

A period after practical completion — typically six to twelve months — during which the builder is obligated to return and rectify defects in the work at no additional cost. It should be written into the contract. Defects that become apparent after this period may still be covered under broader consumer protection legislation, but the contractual obligation is clearer within the liability period.