Which contract a small UK builder should actually sign

You priced the extension, emailed the quote, the customer replied "yes please, when can you start", and that was the paperwork. It works fine for years. Then one job goes sideways: the client changes the kitchen layout in week three and refuses to pay for it, the plaster cracks in February and they want you back for a week, or the final £8,000 sits unpaid because they say the tiling is not what they asked for. At that point the only document either of you has is an email, and an email says nothing about when payment falls due, what a change costs, how long you are on the hook for defects, or who decides.

This page is the realistic set of forms a small UK builder can put in front of a client, what each one costs, and the five clauses inside any of them that decide whether the money arrives. Then the consumer layer that sits on top of all of it on domestic work, because the Consumer Contracts Regulations 2013 can turn a finished job into an invoice you have no right to send.

How it gets talked about

Two things are true at once, and the trade says both of them out loud. On a self-build forum, a member weighing up whether to put a formal contract in front of a jobbing builder:

"Your builder will probably run a mile if you mention a full on JCT contract on small works like this.. also these tend to need a professional to administer = cost."

Gus Potter on BuildHub

And on the same forum, a builder explaining what happens to the price when you do:

"The bigger problem would be finding a builder prepared to work under such a formal form of contract."

RandAbuild on BuildHub, on a client asking about JCT Intermediate for a self-build, adding that a contractor would "add costs to cover such things as Liquidated & Ascertained damages, retention and unforeseen delay etc."

Both are right, and both point at the same answer: the form has to match the job. A JCT Intermediate on a £30,000 loft is a way to lose the job and pay a contract administrator for the privilege. A bare email on a £180,000 barn conversion is a way to fund somebody else's mistake. The forms below are graded so you can pick the one that fits, and the cheapest one on the list is £40.

The realistic options, priced

Prices are the publishers' current list prices, excluding VAT, for a single copy or single-use digital licence.

Two things to read off that table before anything else.

JCT publishes a home owner form and it costs £40. The Home Owner contracts are the part of the JCT suite most small builders have not looked at, because the word JCT carries the smell of a 90 page Standard Building Contract and a quantity surveyor. HO/B 2021 is not that. It is written for a homeowner working direct with a builder and no consultant in between, it covers the work, the price, VAT, payment, insurance, working hours and disputes, and it lets the price be paid either as a single sum on completion or in agreed interim payments. Current editions are HO/B 2021 and HO/C with HO/CA 2021: the 2024 label applies to Minor Works and Intermediate, and there is no 2024 home owner edition.

The adjudication column changes meaning depending on who the client is. That is section 106 of the Housing Grants, Construction and Regeneration Act 1996, and it is the single most surprising thing in UK construction law for someone doing domestic work.

Adjudication, and the job where it switches off

On a commercial contract, section 108 of the Construction Act gives either party the right to refer a dispute to adjudication at any time. The contract must let you give notice at any time, get an adjudicator appointed and the dispute referred within 7 days, and have a decision within 28 days of referral, extendable by 14 days with the referring party's consent. The decision binds until a court, an arbitrator or agreement finally determines the matter. If your contract does not say all that, section 108(5) drops the Scheme for Construction Contracts in over the top of it, so a commercial job carries adjudication whether or not anyone printed a contract.

Section 106 takes it away again on one specific job. Part II of the Act "does not apply to a construction contract with a residential occupier", which means a contract that "principally relates to operations on a dwelling which one of the parties to the contract occupies, or intends to occupy, as his residence."

Read that definition carefully, because it is narrower than the trade assumes. It turns on occupation by a party to the contract, not on the building being a house:

That last row is worth twice what the rest of the page costs. A subcontract sitting under a domestic job is a normal construction contract: the residential occupier exclusion looks at the parties to your contract, and your client is the main contractor. The statutory payment notices, the pay less notice, the right to suspend and the right to adjudicate are all live on that subcontract.

Where the exclusion does bite, JCT put adjudication back in by hand. Both HO/B 2021 and HO/C 2021 are written as consumer contracts outside the Construction Act, and both provide for adjudication in the event of a dispute anyway. That is the strongest single argument for spending the £40: on a homeowner's own house, a £40 form buys you a route to a binding decision in about a month that the law does not otherwise give you, and the alternative is Money Claim Online and a county court list.

The five clauses that decide whether you get paid

Whatever form you use, the money lives in five places. These are the ones to read before signing, and the ones to write into your own terms if you are working off a quote.

1. The payment schedule and its dates

A payment clause needs three dates, not one. The due date is when the sum becomes due. The final date for payment is the last day it can be paid without being late. Between them sits the window for notices.

On a commercial job where the contract is silent, the Scheme for Construction Contracts fills it in, and the default numbers are worth knowing because they are the floor:

Worked through on a subcontract with a valuation period ending on Wednesday 30 September 2026:

Section 111(1) then does the work: "the payer must pay the notified sum (to the extent not already paid) on or before the final date for payment." If they served no payment notice, section 110B lets you serve one in default and your figure becomes the notified sum. If they served no pay less notice by 17 October, the notified sum is payable in full on 24 October regardless of what they think of the work. Section 112 then lets you suspend performance for non-payment after giving at least seven days' notice stating the grounds.

Section 109 gives you the right to payment by instalments on any contract where the work is not specified to last less than 45 days, and section 113 makes pay-when-paid clauses ineffective except where the party further up the chain becomes insolvent. Both are statutory, and neither depends on you having negotiated anything.

On a homeowner's own house, none of that machinery exists. Section 106 switches off the whole of Part II, which means the statutory notices, the notified sum, the right to suspend and the 45 day instalment right are all gone, and there is no Scheme sitting underneath to supply defaults. Whatever your contract says about payment dates is the entire law of that job. That is the real reason to write a stage schedule down: on domestic work, the schedule is not a formality on top of a statutory backstop, it is the only backstop there is.

A stage schedule on a domestic job wants stages tied to observable events rather than to weeks, because "week four" is arguable and "roof watertight" is not:

Add a payment period to each line. Fourteen days from the stage being reached is the shape a homeowner will accept; seven is worth asking for on a job you are funding materials on.

2. Retention, and the date it comes back

Retention is a percentage of every payment the client keeps back as security. It is purely contractual, so the Construction Act has nothing to say about the percentage or the release. Five per cent during the works is the figure quoted most often in the UK, with half released at practical completion and the balance at the end of the rectification period once defects have been made good.

On a £120,000 contract that is £6,000 held during the works, £3,000 released when you finish, and £3,000 you collect somewhere between six and twelve months later. Retention has never been in NEC's core clauses. It applies only where the client selects secondary Option X16 and writes the percentage into the Contract Data, and NEC4 lets the contractor give a retention bond instead of leaving money held, with a retention-free amount on top. That NEC treats retention as an opt-in rather than a default is the precedent to point at when a client asks for 10%.

Three things belong in the retention clause and are usually missing: the percentage, the date the second half is released (an actual trigger, such as 12 months from practical completion or issue of the certificate of making good, whichever is earlier), and a sentence saying the retention is released whether or not the client has got round to inspecting. Retention that has no release date is not retention, it is a discount you agreed to in advance.

3. Variations, and how they are valued

A variation clause has two halves and small builders usually write only the first. The first half is who can instruct a change. The second half, the one that pays, is how the change is priced and when.

The order that protects you, in your own words on a quote or in the change sheet of a JCT form:

1. A change is only a change when it is instructed in writing by the client or their consultant.
2. Where practical, the price is agreed in writing before the work is done.
3. Where it is not practical to agree first, the work is valued using the rates in the contract for comparable work, and where there are no comparable rates, at fair and reasonable rates.
4. A change that affects the programme carries an adjustment to the completion date, agreed at the same time as the price.

Point four is the one people leave out and it is the expensive one. Agreeing £2,400 for moving a doorway and saying nothing about the fortnight it added is how a builder ends up paying liquidated damages on a delay the client caused.

NEC4 handles the same ground with different vocabulary: changes are compensation events, the contractor submits a quotation covering both cost and time, and the early warning mechanism obliges both sides to flag anything that could increase price or delay completion as soon as they know. If you are working for a client who runs NEC, the early warning register is the thing to actually operate, because a compensation event you flagged early is one you get paid for.

4. Extensions of time

Liquidated damages let a client charge a fixed sum for every week you overrun. An extension of time clause is the mechanism that stops the clock when the delay was not yours: client instructions, late information, changes, and whatever else the form lists.

The counterintuitive part is that the extension of time clause protects the client as much as you. Where the client causes delay and the contract has no mechanism to extend the completion date, time goes "at large", the fixed completion date falls away, you are obliged only to finish within a reasonable time, and the liquidated damages become unenforceable. A client who strikes out the extension of time clause to keep you on the hook has usually just deleted their own remedy.

What a workable clause needs: a list of relieving events that includes client instructions and variations, a requirement on you to notify within a stated period of becoming aware of the delay, and an obligation on the client or administrator to grant a fair and reasonable extension within a stated period. Put a diary reminder against the notification period, because a notice period you miss is an extension you lose.

5. The rectification period

JCT calls it the rectification period; the trade still says defects liability period. It runs from practical completion, and during it the client notifies defects and you are entitled and obliged to come back and fix them. Six to twelve months is the usual range on small works.

Two points decide whether it works in your favour. The first is that it is a right as well as a duty: within the period, you get to put the defect right yourself rather than pay somebody else's invoice for doing it. That right is worth having, and it disappears if the clause is not there. The second is that the end of the period is what releases the second half of your retention, so the date it ends is a date to have in the diary.

The period ending does not end your exposure to a claim, and the contract is not the only thing that decides quality. That is the next layer.

The consumer layer: 14 days that can wipe out the invoice

This one catches builders who have done nothing wrong except sign at the kitchen table.

The Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013 (SI 2013/3134) apply to a contract between a trader and a consumer that is concluded away from the trader's business premises. Signing the quote in the customer's kitchen is an off-premises contract. So is signing it in their driveway, or handing over a paper acceptance on site. If the whole thing was done by email or over the phone it is a distance contract, which carries the same 14 day right by a different route.

The right. Under regulation 30(2), for a service contract "the cancellation period ends at the end of 14 days after the day on which the contract is entered into." The consumer can cancel in that window for any reason, or for none.

What you have to give them, and when. Regulation 10 requires the trader, before the consumer is bound, to give the Schedule 2 information "in a clear and comprehensible manner", on paper, or on another durable medium if the consumer agrees, and legible. Where a right to cancel exists, regulation 10 also requires the trader to give the consumer the cancellation form set out in Part B of Schedule 3. Regulation 12 then requires a copy of the signed contract or a confirmation of it, on paper or a durable medium, before performance begins.

Three items in Schedule 2 do the heavy lifting:

• (l) "Where a right to cancel exists, the conditions, time limit and procedures for exercising that right in accordance with regulations 27 to 38"
• (m) where applicable, that the consumer bears the cost of returning goods
• (n) "That, if the consumer exercises the right to cancel after having made a request in accordance with regulation 36(1), the consumer is to be liable to pay the trader reasonable costs in accordance with regulation 36(4)"

What happens if you leave them out. Regulation 31(3): where the paragraph (l) information was not given, "the cancellation period ends at the end of 12 months after the day on which it would have ended under regulation 30." Regulation 31(2) offers the repair: supply the information inside that 12 months and the cancellation period ends 14 days after the consumer receives it.

Then regulation 36(6), which is the one that costs money. Where a consumer cancels after the service has been supplied, they normally pay a proportionate amount under regulation 36(4). But they bear no cost at all where the trader failed to give the information in paragraph (l) or (n) of Schedule 2, or where the work was not supplied in response to their express request. A finished job, cancelled inside a window that stayed open for a year, with no right to charge for any of it.

Regulation 19 adds a criminal offence: a trader who enters into an off-premises contract and fails to give the consumer the information in paragraph (l), (m) or (n) commits an offence punishable on summary conviction by a fine at level 5 on the standard scale, which in England and Wales has been a fine of any amount since 12 March 2015 under section 85 of the Legal Aid, Sentencing and Punishment of Offenders Act 2012.

Starting work inside the 14 days. Regulation 36(1) is the whole answer, and it has two limbs. The trader must not begin supplying the service before the end of the cancellation period unless the consumer has made an express request, and for an off-premises contract that request must be made on a durable medium. Written, signed, dated, in your file. Regulation 36(2) goes further for short jobs: where the service is fully performed within the cancellation period, the consumer loses the right to cancel altogether if performance began at their express request and they acknowledged that they would lose the right once the service was fully performed.

The wording and the timing

Three documents, in this order, before a spade goes in the ground.

Before they sign. The quote carries the Schedule 2 information, including a plainly worded cancellation notice covering the conditions, the 14 day time limit and how to cancel, plus the statement required by paragraph (n) that if they cancel after asking you to start early they will pay for what has been done.

With the quote. The Part B model cancellation form, on paper or on a durable medium they have agreed to. A PDF attached to an email counts as a durable medium; a line in the body of a WhatsApp message is a fight you do not want.

Before you start, if you are starting inside the 14 days. A dated request in their own hand or their own email, along these lines:

I have read the cancellation notice you gave me. I request that you begin work on 14 September 2026, which is before the end of my 14 day cancellation period. I understand that if I cancel after work has begun I will pay you for the work carried out up to the point of cancellation.

And where the job will be finished inside the 14 days, one more sentence:

I acknowledge that once the work has been fully performed I will lose my right to cancel.

The same job, both ways

A loft conversion, £34,000 including VAT. The quote is signed in the client's kitchen on Tuesday 8 September 2026. Work starts Monday 14 September. On Saturday 19 September the client's circumstances change and they cancel. £6,300 of work has been done: scaffold up, roof opened, steels in.

The right-hand column is not a hypothetical. It is what regulation 36(6) says, on a job that was priced properly and built properly.

The standard the work is held to: Consumer Rights Act 2015

On any contract between a trader and a consumer, Chapter 4 of the Consumer Rights Act 2015 writes terms into the contract that the contract itself cannot displace.

Section 50 is the one worth a second read. "It will be finished before Christmas" said on a doorstep, or "we use a specialist damp firm for that", becomes a contract term if the customer relied on it. The defence is a quote specific enough that the spoken version adds nothing: named products, named subcontractors, a completion date with the extension of time mechanism attached to it.

Section 55 is why the rectification period earns its keep. Repeat performance is the consumer's first remedy, and a contract that gives you a defined window to come back and put things right is a contract that keeps that work in your hands and off somebody else's invoice.

Where the sums are large or the client has instructed solicitors, an hour with a construction solicitor before you reply is the cheapest hour on the job.

Choosing, in one pass

• Homeowner, their own house, job worth more than a few thousand pounds: JCT HO/B 2021, £40 + VAT. It buys you a payment schedule, a defects position, and an adjudication route the law would otherwise deny you on that exact job.
• Homeowner with an architect already appointed: HO/C and HO/CA 2021, £46 + VAT, so the consultant's role is written down rather than assumed.
• Commercial client, straightforward lump sum work, up to about a year: JCT MW 2024, £100 + VAT, or MWD 2024 at the same price where you are designing part of it.
• Bills of quantities, named specialists, phased handovers: JCT IC 2024, £178 + VAT.
• A client who runs NEC: NEC4 ECSC, and operate the early warning register from day one.
• Small works and day rate weeks: your own written terms, carrying the five clauses above and the cancellation pack.

Whichever you pick, the domestic cancellation pack is separate from all of it and applies on top. The JCT Home Owner forms address cancellation rights, and your own terms will not unless you put them there.

What it costs

The contract itself is the cheap part: £40 to £178 plus VAT for a JCT form, or nothing at all for your own terms with the five clauses in them. The expensive version is the one with no dates in it.

On AEC Stack there is no monthly subscription. The platform fee is 2.5% of each invoice processed through the platform, taken when the invoice is paid, so a quiet month costs nothing. Your quotes carry the stage schedule and the cancellation pack as attachments, each stage invoice is raised against the trigger it belongs to rather than against a week number, and the retention held on a job sits against that job until the release date rather than disappearing into a spreadsheet.

Take the quote you are about to send, add the stage schedule and the cancellation notice to it, and put them in front of the client before they sign rather than after: start with the quote.