What to Ask a Builder Before You Hire Them

The questions that separate a reliable builder from one you'll regret hiring.

RenoHub · 18 June 2026 · 6 min read

Why this conversation matters

Hiring the wrong builder is one of the most expensive mistakes you can make on a renovation. Disputes about what was included, extras that appear without warning, work that stops when the money runs out — these situations are far easier to prevent than to fix. Most of them trace back to a conversation that never happened before work started.

The questions below are not about catching anyone out. A good builder will welcome them. They show you are serious, organised, and worth working with. If a contractor becomes evasive or offended, that tells you something useful too.

References and recent work

Ask for two or three references from jobs completed in the past 12–18 months, ideally work that is similar in scope to yours. Then actually contact them.

Good questions to ask a previous client: Did the job finish on budget? On time? Were there any unexpected extras, and how were they handled? Were the site and surrounding rooms kept reasonably clean? Would you use them again?

If the builder can offer to show you a completed job in person, take them up on it. Photographs are easily cherry-picked; a real kitchen extension or loft conversion speaks for itself.

A written, itemised quote

This is the single most important document in your whole project. A written quote is not just a price — it is a record of what has been agreed. Without it, disputes about what was included are almost impossible to resolve fairly.

A proper quote should set out:

• Each section of work, broken into individual line items with costs
• The materials and finishes specified (not just "bathroom tiles" — which tiles, from where)
• What is explicitly not included (groundworks? decorating? making good?)
• The total price, and whether VAT is included or extra
• Projected start and end dates
• How variations and extras will be priced and agreed in writing

If a builder offers only a rough ballpark figure or a single-line total, ask for a full breakdown. If they are reluctant to provide one, that is a red flag.

Get at least three written quotes before committing. The cheapest is not always the best value — compare scope carefully, because a lower price sometimes means less is included.

Payment schedule

Agree a staged payment schedule before work begins. Payments should be tied to clearly defined milestones — for example, completion of foundations, completion of structure, completion of first fix, and so on — rather than to dates on a calendar.

A small initial deposit (typically 10–20%) to cover materials ordered upfront is reasonable for larger jobs. Be cautious of any builder who asks for a large proportion of the total cost before work starts. If a contractor requires more than around 25–30% upfront, or insists on cash with no paper trail, walk away.

Never pay the full balance until you are satisfied the work is complete to the agreed standard. Keep a small retention — perhaps 5% — for a short period after completion, to cover any snags that emerge once the site is cleaned up.

Insurance and trade registrations

Ask to see proof of public liability insurance. This covers damage to your property or injury to a third party during the works. A reputable builder will produce the certificate without hesitation. Check the level of cover is adequate for your job — for larger projects, you want at least £1–2 million cover, though many builders carry £5 million or more.

For specialist trades, check the relevant registration:

• Gas Safe Register — any builder or sub-contractor working on gas appliances, boilers, or pipework must be Gas Safe registered. You can verify at gassaferegister.co.uk.
• NICEIC or NAPIT — electrical contractors should be approved by one of these competent-person schemes. Verify at niceic.com or napit.org.uk.
• TrustMark — a government-endorsed quality scheme covering a wide range of trades. Not a legal requirement, but a useful signal of accountability.
• FMB (Federation of Master Builders) — membership requires passing an independent inspection and carrying insurance. Worth checking for general builders at fmb.org.uk.

Timescales and who's on site

Ask when the builder can start and how long the job is expected to take. A realistic answer is specific: "We'd aim to start the week of 14 July, and the structural work should take around three weeks, with second fix and decorating four to five weeks after that." Vague answers ("a few weeks, maybe a couple of months") suggest the builder has not thought through the programme — or has too many jobs running at once.

Find out who will actually be on site every day. Many builders sub-contract significant parts of a job — plastering, electrical, plumbing. That is perfectly normal, but you want to know who is responsible for managing those trades and who your day-to-day contact will be. If the person quoting the job is rarely on site, ask who the site manager is.

How variations and extras are handled

Almost every renovation involves something unexpected. A wall that opens up to reveal old wiring that needs replacing. Dimensions that turn out to be different from the drawings. A product that is discontinued. How your builder handles these moments will define a large part of your experience.

Before work starts, agree in writing that any variation or extra will be costed and approved by you before it is carried out. This does not need to be a formal contract — a simple statement in the quote or a short email exchange is enough. What matters is that neither side can spend your money without the other's agreement.

Be wary of builders who are vague about extras, or who present large variation invoices at the end of a job. The time to have this conversation is before the work starts, not after.

Red flags to watch for

• Cash-only, no receipts. This is not just a financial risk — it means no paper trail if something goes wrong.
• No written quote. If they will not put it in writing before the job, they will not put anything in writing during it.
• Pressure to decide quickly. "I've got another job lined up, I need to know by Friday" is a classic pressure tactic. A good builder has work; they do not need to rush you.
• Unusually low price. A quote significantly lower than others may mean something has been left out, inferior materials are assumed, or the builder is in financial difficulty.
• No fixed address or landline. A contractor with only a mobile number and no registered business address is harder to pursue if problems arise.

How RenoHub helps

Once you have chosen your builder and received a written itemised quote, RenoHub's Contractor Works Tracker turns that document into a live project checklist. You import the builder's PDF quote, and RenoHub's AI extracts every section and line item — groundworks, structure, first fix, finishes — into a tracker you update as work progresses. You can see at a glance what has been completed, what is outstanding, and how actual spending compares to the quoted price.

This is especially useful when managing variations. Every time an extra is agreed, you record it in the tracker. By the time the final invoice arrives, there should be no surprises — you have a complete picture of what was agreed, what was completed, and what was spent.

RenoHub also keeps all your project documents in one place: the quote, any revised quotes, insurance certificates, Gas Safe certificates, NICEIC completion certificates, building control sign-off — everything organised and accessible from your phone. No more hunting through email threads when a query comes up six months later.

RenoHub is an iPhone app. Your data stays on your device and in iCloud — it never passes through RenoHub's servers.