Before accepting a builder's quote, check it names both parties in full, sets out a written scope of work, states materials and specification, gives a fixed or clearly itemised price, sets a payment schedule tied to progress, confirms insurance, and states a start date and rough timescale. If any of these are missing, ask for them in writing before you sign anything.
Why the checklist matters more than the number at the bottom
After 38 years in the trade I can tell you that homeowners nearly always focus on the total figure and skim past everything above it. That's understandable — it's the number that matters to your bank account — but it's also how disputes start. Two builders can quote the same total for an extension while one has included the scaffolding, skip hire and making good, and the other hasn't. The cheaper-looking quote can end up costing more once the gaps are filled in.
A quotation is meant to be a firm, considered price for a defined piece of work. If the document in front of you reads more like a rough note on a compliments slip, that's not really a quotation at all — it's closer to an estimate, and the two things carry different expectations. This checklist is about turning a vague piece of paper into something you can hold a builder to.
The basics: who, what, where
- Full trading name of the business, not just a first name or a mobile number
- Company number or sole trader status — check it against Companies House if it's a limited company (gov.uk/get-information-about-a-company)
- Business address, not just a mobile number and a van
- The property address the work relates to
- The date the quote was issued and how long it remains valid for
Scope of work: what's actually being done
This is where most disputes are born, because scope is where assumptions live. A quote that says 'build extension as discussed' is not a scope — it's a placeholder for an argument in six months' time. A proper scope breaks the job into stages: groundworks, drainage, brick and blockwork, roof structure and covering, first fix, plastering, second fix, decoration, and external works.
Look for whether the scope names the specification — brick type, window make and U-values, roof covering, flooring, and any items you've specifically discussed like a particular boiler or a rooflight. If it just says 'as per drawings' check the drawings actually specify these things, because vague drawings and a vague quote leave you with nothing to hold anyone to.
Price structure and what it excludes
- Is the price fixed, or is it described as approximate, provisional, or subject to survey?
- Are provisional sums (PC sums) identified for items not yet chosen, such as sanitaryware or kitchen units?
- Does it state what's excluded — for example scaffolding, skip hire, structural engineer's fees, building control fees, party wall costs, or decoration?
- Is VAT shown separately, and is the builder VAT registered (worth checking if the price looks suspiciously round)?
- Are day-rate or hourly charges given for any variation work, so you know what an extra costs before it happens?
Payment schedule
A sensible payment schedule is tied to visible stages of completed work, not to the calendar. Be wary of schedules that ask for large sums before work starts or that are front-loaded so the bulk of the money is paid before the bulk of the work is done.
For more detail on what a reasonable deposit and staged schedule looks like, see our guides on deposits and stage payments — they go into the numbers this checklist only flags.
Insurance, guarantees and paperwork
- Public liability insurance — ask to see the certificate and the expiry date
- Whether the builder is registered with a scheme such as TrustMark (trustmark.org.uk) or a trade body, and what that does and doesn't guarantee
- Whether a workmanship guarantee or insurance-backed guarantee is offered, and for how long
- Confirmation that Building Control will be notified where the work requires it, and who is responsible for that
- A written variation process — how changes to the job get priced and agreed before the work happens
Timescale and practicalities
A start date and a realistic duration should be stated, along with what happens if either side needs to move it. It's also worth checking working hours, arrangements for access, parking, welfare facilities, and who's responsible for protecting existing finishes and clearing rubbish as the job goes.
Practical checklist
- Builder's full trading name, company number (if applicable) and address
- The property address and date the quote was issued
- A written, staged scope of work rather than a one-line description
- Specification of materials, fittings and finishes referenced by name or model
- A fixed price, or clear description of what is estimated versus firm
- Provisional sums clearly identified for items not yet chosen
- A list of exclusions — scaffolding, skips, fees, decoration, and so on
- VAT treatment stated separately
- Day rate or unit prices for likely variations
- A payment schedule tied to completed stages, not the calendar
- Deposit amount and what it's for
- Public liability insurance confirmed and in date
- Any guarantee or insurance-backed warranty on workmanship
- Building Control route confirmed, if the work needs it
- A written process for agreeing changes and extras
- Start date and expected duration
- Who is responsible for skips, waste, and protecting existing finishes
- Contact details for who to raise problems with during the job
Good and bad examples
What good looks like
A four-page quote from a local builder for a single-storey rear extension: it lists each construction stage separately with materials named, states a fixed price for the build and a provisional sum for the kitchen units, sets out five stage payments tied to sign-off points, attaches a current public liability certificate, and states that Building Control will be notified by the builder before work starts.
What to push back on
A single paragraph on headed paper: 'Rear extension as discussed, brick to match existing, roof as per drawing. Price £48,000 + VAT. 50% deposit, balance on completion.' No scope breakdown, no exclusions listed, no payment stages, and no mention of insurance or Building Control.
Worked example
Illustrative example only — figures are for illustration, not typical national prices
| Stage | What it should cover | Typical trigger for payment |
|---|---|---|
| Deposit | Materials ordering, scheduling | On signing contract |
| Groundworks & foundations | Excavation, footings, drainage | On completion of foundations |
| Structure to roof | Walls, roof structure, weatherproofing | On watertight shell |
| First fix & plastering | Wiring, pipework, insulation, plaster | On completion of first fix |
| Second fix & decoration | Fittings, flooring, painting | On practical completion |
| Retention | Snagging held back | After snagging list cleared |
Commonly missed items
- Scaffolding, skip hire and waste disposal
- Building Control fees and inspections
- Structural engineer's calculations and fees
- Party wall surveyor costs where a party wall award is needed
- Making good to existing rooms disturbed by the works
- External works — paths, drainage runs, landscaping reinstatement
- Decoration to the whole extension rather than just plastering
Warning signs
- The quote is verbal or a single unstructured paragraph with no breakdown
- A large deposit is requested with no explanation of what it covers
- There's no mention of insurance and the builder is reluctant to provide it
- The price looks unusually low with no explanation of exclusions
- Pressure to sign quickly to 'lock in' a price
- No fixed address for the business, only a mobile number
Questions to ask
- Can you break the price down by stage so I can see where the money goes?
- What is and isn't included — can you list the exclusions in writing?
- How do we agree and price any changes once work has started?
- Can I see your public liability insurance certificate?
- Who will handle Building Control notification and inspections?
- What happens if we need to delay the start date?
When to seek professional advice
- If the value of the work is substantial and you want the contract terms checked before signing
- If you're unsure whether planning permission or Building Control approval is needed — check Planning Portal (planningportal.co.uk) or your local authority
- If a dispute arises over what was included and informal discussion doesn't resolve it — Citizens Advice (citizensadvice.org.uk) can point you to next steps
Official sources
Frequently asked questions
- Is a builder legally required to give me a written quote?
- There's no general legal requirement for a builder to provide a written quotation for domestic work, but without one you have very little to rely on if a dispute arises. A written, itemised quote that you both sign forms the basis of your contract, so it's worth insisting on one regardless of the size of the job.
- How many quotes should I get before choosing a builder?
- Most people get three, which is usually enough to spot an outlier and to understand the general shape of the job's cost. What matters more than the number of quotes is making sure they're all pricing the same scope of work — see our guide on comparing quotes like for like.
- What if the builder won't put anything in writing?
- Treat that as a warning sign rather than something to work around. A reluctance to commit scope and price to paper often means either disorganisation or an intention to add costs later. Ask directly for a written quote and be prepared to look elsewhere if you don't get one.
- Does a detailed quote guarantee a good builder?
- No — a well-presented quote tells you the builder is organised on paper, which is a good sign, but it doesn't confirm workmanship or reliability. Combine the quote checklist with the checks in our how to check a builder guide.
- Should I accept a quote that has no expiry date?
- It's better to have one. Material and labour costs move, and a quote without a validity period can be reissued at a higher price later, or honoured reluctantly. Ask the builder to state how long the price stands.
Builder Proof UK publishes general educational information for homeowners. It is not legal, structural, surveying, planning, electrical, gas, insurance or financial advice, and it does not replace advice from a suitably qualified professional for your specific project.