The essential clauses

1. Full description of the work

Detailed scope: exactly what’s being built, demolished, installed. Reference drawings and specifications by date/version. Vague scopes (“renovate bathroom”) breed disputes; specific scopes (“remove existing suite, install [named] suite, tile walls to 1.2m with [named] tiles…”) prevent them.

2. Fixed price (or how price is calculated)

• Fixed lump sum preferred for defined work
• Itemised breakdown: labour, materials, subcontracts
• VAT: state whether the price includes VAT (20% on most building work; 5% for some conversions/renovations — confirm)
• Provisional sums: if some costs are genuinely unknown (groundworks), cap them and define how they’re finalised

3. Payment schedule

• Deposit: 10–25% maximum upfront
• Staged payments tied to completed milestones (e.g. “foundations complete”, “watertight”, “first fix complete”) — never pay for work not done
• Retention: hold back 5–10% until snagging is complete (typically 2–4 weeks after “completion”)
• Payment method and timing (e.g. within 7 days of stage sign-off)

4. Start and completion dates

• Agreed start date and completion date
• Programme of works (week-by-week plan for larger jobs)
• Liquidated damages: agreed compensation per week of delay (e.g. £200/week) — this focuses minds wonderfully
• What counts as excusable delay (extreme weather, unforeseen ground conditions) vs not (builder took another job)

5. Variations (changes)

Define the process: all changes in writing, priced before work starts. The classic dispute is “you said to do X” / “no I didn’t” — a written variation order signed by both sides kills it. State the builder’s markup on extra materials if applicable.

6. Materials and workmanship standards

• Named products where it matters (boiler model, tile range, window spec)
• Workmanship to building regulations and relevant British Standards
• Who supplies what (client-supplied items listed explicitly)

7. Insurance and liability

• Builder’s public liability insurance (£2m+; copy attached)
• Contract works insurance for the project itself (covers fire/theft/damage during construction)
• Who’s responsible for existing property damage

8. Snagging and defects

• Snagging period: typically 2–4 weeks post-completion to identify defects
• Defects liability: 6–12 months for issues that emerge (cracks, leaks)
• Builder returns to fix defects at their cost within an agreed timeframe

9. Termination

How either party can end the contract: notice period, payment for work done to date, what happens to materials on site. Hope you never need it; essential if you do.

10. Dispute resolution

Escalation path: discussion → mediation → adjudication/arbitration. For domestic work, mention TrustMark or relevant trade body mediation if applicable.

Standard contract templates

• JCT Minor Works — the industry standard for smaller projects; your architect or solicitor can provide it
• FMB contracts — Federation of Master Builders members use plain-English contracts
• TrustMark guidance includes contract checklists
• For jobs under ~£5,000, a detailed written quote + these key clauses in an email exchange can suffice — but get it in writing regardless

Before signing

• Read it fully — boring but essential
• Check the builder’s insurance certificates are current and attached
• Confirm building control arrangements (who notifies, who pays fees)
• For Party Wall situations, confirm notices are served — see loft conversion planning guide
• For projects over £20k, consider having a solicitor review it (£200–£400 well spent)

The bottom line

Scope + fixed price + staged payments + dates + variations in writing + insurance + snagging. Those seven elements cover 95% of domestic building disputes. A builder who won’t sign a clear contract is telling you everything you need to know — walk away. For finding the right builder in the first place, see our guide to finding a reliable builder.

What happens without a contract (cautionary tales)

The patterns repeat endlessly. The disappearing deposit: £8,000 paid upfront for materials, builder never returns — no contract, no proof of what was agreed, police call it a civil matter. The endless extras: £20,000 quote becomes £38,000 through verbal “while you’re at it” additions with no written prices — no contract, no way to dispute. The unfinished job: builder leaves at 80% complete demanding final payment — no stage definitions, no retention clause, no leverage.

The blame game: leak appears six months later — builder says it’s wear and tear, homeowner says it’s defective work — no defects liability clause, no snagging process, stalemate. Every one of these is preventable with a two-page written agreement. You don’t need a solicitor for most domestic work — a clear email exchange covering scope, price, payments, dates and snagging, confirmed by both sides, is infinitely better than nothing. The builders who resist even that are the ones you needed the contract for.

Building contract FAQs

Do I need a solicitor to draft it? Not for most domestic work. Use a standard template (JCT Minor Works, FMB contract) or a detailed written quote + key clauses confirmed by email. For projects over £50,000 or complex structural work, £300–£500 of solicitor review is cheap insurance. Your architect (if you have one) usually provides/administer the contract as part of their service.

What if the builder won’t sign a contract? Walk away. There is no legitimate reason to refuse a clear written agreement — it protects the builder too (guaranteed payment terms, defined scope preventing scope-creep disputes). Refusal signals either disorganisation (they’ll be disorganised on site too) or intent (they plan to exploit ambiguity). Either way, not your builder.

Can I use a contract for a small job (£1,000–£5,000)? Yes — a simplified version. Scope + fixed price + payment terms + dates + what’s excluded, in an email, confirmed by both sides. Takes 15 minutes. Small jobs generate disproportionate disputes precisely because people skip paperwork “for something this small”. The plumber who floods your kitchen doesn’t care that it was “only” a £2,000 job.

Who owns the materials if the builder goes bust mid-job? Generally, whoever paid for them — but proving it without paperwork is hard. Protect yourself: pay suppliers directly for large material orders where possible, keep all receipts, and ensure the contract states that materials paid for become your property. If a builder goes bust owing suppliers, suppliers can sometimes claim materials on site — another reason to pay suppliers direct for big-ticket items.

What about a handshake deal with someone I trust? Still write it down. This isn’t about trust — it’s about memory. Six months later, you remember “the quote included painting” and they remember “painting was extra”. Both are sincere; both can’t be right. A written note prevents the argument that destroys the friendship. Good builders aren’t offended by paperwork — they’re relieved.

Related reading

Find the right person first: finding a reliable builder — and check TrustMark’s contract guidance.