Questions to Ask a Builder Before Hiring: The Complete Checklist

Hiring the wrong builder is one of the most expensive mistakes a homeowner can make. A failed renovation — overrunning budget, abandoned mid-project, or structurally substandard — can cost tens of thousands to fix and years of stress to resolve. The good news: most bad hires are avoidable with the right due diligence before you sign anything.

This checklist covers every question worth asking before you appoint a builder, whether you're planning a kitchen extension, a full house renovation, or a straightforward bathroom refurbishment.

Are They Registered With a Recognised Trade Body?

Registration isn't a guarantee of quality, but it is a meaningful filter. Reputable builders often carry membership with one or more of the following:

• Federation of Master Builders (FMB) — members are independently vetted and must pass a site inspection. FMB also provides a free dispute resolution service.
• TrustMark — a government-endorsed quality scheme covering tradespeople across all disciplines.
• NFRC (National Federation of Roofing Contractors) — relevant if roofwork is involved.

Ask to see their membership number and verify it directly on the scheme's website. Anyone can claim membership; few will fake a live database entry.

Do They Have the Right Insurance?

This is non-negotiable. Before any work begins, confirm the builder holds:

• Public Liability Insurance (PLI) — minimum £2 million, though £5 million is standard for larger projects. This covers damage to your property and injury to third parties caused by the builder's work.
• Employer's Liability Insurance (ELI) — legally required for any builder employing staff (including subcontractors they manage). Minimum £5 million by law.
• Contract Works Insurance — covers materials and works in progress against damage, theft, or fire. Not always held; worth asking.

Ask for a copy of the insurance certificate and check the expiry date. A builder who can't produce documentation within 24 hours is a concern.

Can They Provide Three Recent References?

Three references minimum — and they should be for the same type of work you're commissioning. A builder who's brilliant at extensions but inexperienced with listed buildings is the wrong choice for a Grade II property.

When you follow up the references, ask:

• Did the project finish on time and on budget?
• Were there any disputes, and how were they resolved?
• Would you use them again?
• Can I come and look at the finished work?

At least one site visit is worth the half-hour. You'll learn more in five minutes of looking at joints, finishes, and detailing than from any amount of phone conversation.

Do They Use Subcontractors — and Who Is Responsible?

Most builders subcontract specialist trades: electricians, plumbers, plasterers. This is normal and not inherently a problem. The question is: who is contractually responsible when a subbie's work is defective?

The answer should always be the main contractor. A good builder takes responsibility for everyone on their site. Ask:

• Which elements do you subcontract?
• Are your subbies vetted, and how?
• If a subcontractor causes damage or delays, who is liable under our contract?

If the answer to the last question is "you'd need to take it up with them directly," walk away.

Are They VAT Registered?

VAT registration is required once a business turns over more than £90,000 per year (2024/25 threshold). Established builders doing significant volumes of work will almost always be VAT registered.

A builder who insists on cash-only payments and isn't VAT registered isn't necessarily fraudulent — but it's a yellow flag. It may indicate a sole trader working at low volume, which isn't inherently a problem, or it may indicate someone deliberately avoiding the tax system. Either way, it affects your paper trail and any future warranty claims.

For larger projects, always ensure invoices are VAT-compliant (VAT number, rate, and amount shown separately).

Quotation, Estimate, or Fixed-Price Contract?

These three terms are not interchangeable, and confusing them is how disputes start.

Always insist on a written, itemised quotation before work starts. For anything above £5,000, a proper fixed-price contract (see JCT below) is strongly advised.

What Is the Payment Schedule?

Never pay the full contract sum upfront. No reputable builder will ask you to. The standard approach is stage payments tied to verifiable milestones — foundations complete, roof watertight, first fix done, and so on.

A typical payment structure:

• 0–10% deposit on appointment (materials procurement)
• Staged payments as milestones are reached and inspected
• 5–10% retention held for 3–6 months after practical completion

The retention is your leverage. It gives you something to withhold if the snag list isn't cleared. Don't release it until you're satisfied.

What Is the Start Date and Estimated Duration?

A vague answer here ("probably sometime in spring," "few months, maybe") is a warning sign. A professional builder will have a programme of works — even a basic one — and will be able to commit to a start date and a realistic completion window.

Tie the start date to the contract. If they miss it by more than two weeks without a valid reason, you should be entitled to recover costs. For more on managing timelines, see our renovation project timeline guide.

Who Applies for Planning Permission and Building Regulations?

This question catches many homeowners off guard. Technically, it is the owner's responsibility to ensure the necessary approvals are in place — not the builder's. However, a good builder will either apply on your behalf or advise you clearly on what is needed.

Clarify in writing:

• Who is submitting the planning application (if required)?
• Who is serving as the principal contractor for building regulations?
• Who will liaise with the Building Control Inspector throughout the project?

For a full breakdown of the building regs process, see our post on getting building regulations approval.

How Is the Site Left Each Day?

This question sounds trivial. It isn't. A builder who leaves a chaotic, hazardous site at the end of each day — rubble in the garden, tools unsecured, dust sheets not replaced — is telling you something about how they work overall.

Ask:

• How will the working area be sealed off from the rest of my home?
• Where will materials and skips be located?
• How will debris be managed and removed?
• Will site access be locked at the end of each day?

Do You Recommend Using a JCT Minor Works Contract?

The Joint Contracts Tribunal (JCT) Minor Works Building Contract is the industry-standard written agreement for smaller residential projects. It sets out responsibilities, payment terms, variations procedure, practical completion, and dispute resolution clearly.

For any project above £5,000–£10,000, recommend it. If a builder refuses to work under a written contract, that alone is a reason to decline.

Printable Builder Due Diligence Checklist

Red Flags: Walk Away If You See These

• Cash only, no receipt — no paper trail, no VAT, no comeback.
• No fixed address or registered business — impossible to pursue if things go wrong.
• Wants full payment upfront — the single biggest warning sign in the industry.
• Unwilling to provide references — a confident, competent builder has satisfied clients.
• Vague verbal agreements only — anything not in writing doesn't exist legally.
• Significantly cheapest quote — sometimes genuine, often a sign of underquoting to win work, then variations to recover margin.

Get Started With Confidence

Finding the right builder is only the beginning. Renovate Me gives you a personalised renovation roadmap — step-by-step guidance on every stage of your project, from planning and procurement through to final snagging. Upload your photos, set your budget, and let the platform guide you through every decision. Start your roadmap at renovate-me.madethis.app.

• Renovation Cost Contingency: How Much to Budget and Why — build the right contingency into your budget before you even put questions to your builder
• When to Use a Project Manager vs Manage Your Own Renovation — once you've chosen a builder, decide whether to run the project yourself or bring in a PM