JCT is the default language of UK building contracts. If you can't read it, you're relying on luck and "that's how we've always done it" on most jobs you'll touch.
This section gives you: what the main JCT types are for, how they handle money, time and risk, and what to watch for in the bits that get edited.
1. What "JCT" actually is and when you see it
JCT is a suite of standard contract forms put together by the Joint Contracts Tribunal -- a mix of clients, contractors, consultants and lawyers. They're meant to be a fair, known starting point that everyone recognises.
You'll see JCT used:
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On the bulk of building projects in England and Wales, especially commercial and larger residential jobs.
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As the main contract (employer--main contractor) and matching sub-contracts beneath (main contractor--subbies) so risk and payment flow down the chain.
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In different "families" so the form (Design & Build, Standard Building, Minor Works etc.) matches the size and complexity of the job.
The starting point is always: Which JCT are we on and why did they pick it?
2. The main JCT types and what they're trying to do
You don't need the whole catalogue in your head, just the big ones and what they mean for you.
Design & Build (DB)
You take full responsibility for both design and construction (often including employer's requirements and your contractor's proposals).
Suits employers who want one point of responsibility and contractors who are comfortable managing design risk and specialists.
Standard Building Contract (SBC)
Traditional route: employer's team designs, contractor builds to that design. Used on big or complex projects with full drawings, specs and bills.
There are options with and without quantities, and with some contractor's design for packages.
Intermediate Building Contract (IC)
For medium projects with multiple trades but not huge complexity, often with limited services.
Minor Works (MW)
For small, simple jobs -- basic alterations, small extensions. Often mis-used on jobs that are too big or complex just because it "looks simple".
Term / Measured Term
For ongoing maintenance or repeat small works under one umbrella over a period.
On sub-contract level you get matching flavours (e.g. JCT Design & Build Sub-Contract, Intermediate Sub-Contract) so the main contract obligations are mirrored downstream.
3. How a JCT is put together (and where the landmines are)
Once you've seen the skeleton, they stop being mysterious.
Most JCT main contracts have:
Agreement / Articles -- Who's who, what the project is, the contract sum, and what documents make up the contract. This is where you check: are the drawings, specs and any pre-contract clarifications you're relying on actually listed?
Contract Particulars -- The "options and settings" page:
- Start and completion dates, liquidated damages, sectional completion.
- Payment options (frequency, valuation method, retention, interest).
- Insurance option (who insures what).
- Dispute route (adjudication, then court or arbitration).
Conditions (clauses) -- The rules of the game:
- carrying out the works and quality
- instructions and changes (variations)
- payment and notices
- extensions of time
- loss and expense
- insurance and damage
- termination and disputes.
Most of the commercial pain you see on jobs comes from three places: how the Contract Particulars were filled in, how the payment/time clauses are amended, and how little anyone read them.
4. What JCT does with payment, notices, and cash-flow
JCT is built to comply with the Construction Act, so it has a structured payment process. How those bits are filled in decides how your money moves.
Core payment ideas:
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Interim payments -- Regular payments (usually monthly) based on the value of work done, design completed (if relevant), and sometimes materials on/off site.
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Valuation methods -- Choice of interim valuation based on stage/milestones or periodic re-measurement against bills/schedules. This is in the Contract Particulars.
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Payment notices -- After each due date, the payer (or their agent) serves a notice stating the sum they think is due and how it's worked out. If they don't, pay-less notices and default notice provisions kick in under the Act.
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Pay-less notices -- If they want to pay less than the notified sum, they must serve a valid pay-less notice by the deadline. If they miss it, they're on the hook for the full notified amount unless they fight it in adjudication.
JCT gives you the structure; the Act sits behind it. Between the two, you've got a legal timetable for applications, notices and payment -- but only if you actually follow it.
5. How JCT handles design, changes, time, and loss & expense
These are the other big levers that decide who pays when things move.
Design risk
- SBC: employer's design, contractor builds. You still have temporary works, methods and any packaged design you take on.
- DB: you own design, coordination and build. JCT 2024 DB still keeps most design responsibility on the contractor, though with updated provisions and guidance.
Variations / changes
- Architect/CA or Employer's Agent can instruct changes to the works (additions, omissions, changes to materials/methods).
- Variations are generally valued by reference to contract rates, similar work, or fair valuation if there's nothing suitable.
- JCT expects you to act on instructions, then argue price/time through the proper mechanism -- not ignore them.
Extensions of time (EOT)
- JCT has a list of "Relevant Events" (e.g. employer changes, delay in information, exceptionally adverse weather, strike, specified risks) that can give you more time.
- If you don't notify and substantiate, you risk missing EOTs and getting hit with liquidated damages.
Loss and expense
- Separate from time: certain "Relevant Matters" (e.g. variations, late information, disruption caused by the employer) let you claim your additional cost.
- JCT expects you to notify and detail this too -- just moaning at final account isn't enough.
If you only ever check three things on a live job, check: how variations are valued, what counts as a Relevant Event/Relevant Matter, and how you've got to notify to protect your position.
6. How amendments to JCT quietly move the goalposts
Most JCTs you see won't be "vanilla". They'll be full of tracked changes or a Schedule of Amendments that quietly re-write the deal.
Common tricks:
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Shifting design/fault risk more heavily onto the contractor/subbie, even on Standard Building form.
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Tightening notice periods for EOT and loss/expense, or making claims procedures more onerous so they can refuse late or badly-presented claims.
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Tweaking payment clauses to add extra hurdles before sums are "due", or to blur who actually issues payment notices.
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Hardening termination rights for the employer and softening them for the contractor.
Your simple rule: treat the amendments as the "danger list". That's usually where your normal assumptions about JCT stop being true.
7. What you actually do with all this
On any JCT job, whether you're a small trade firm or a main contractor, your basic moves are:
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Identify the exact JCT form and version (e.g. JCT Design & Build 2024, SBC 2016 etc.).
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Read the Contract Particulars and Schedule of Amendments with a "money and risk" eye: payment, time, design, insurance, termination, dispute route.
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Make yourself a one-page crib for the job:
- payment cycle and notice deadlines
- key EOT/L&E triggers and notice requirements
- who can instruct changes and how they must be confirmed
- LD rate and when it starts biting.
That's how you turn JCT from a doorstop into something that actually protects you on a live project.
The main JCT forms at a glance
| JCT form | Typical job / use | Who holds design risk? | Payment style | Complexity / admin feel | Classic pros | Classic cons |
|---|---|---|---|---|---|---|
| Design & Build (DB) | Medium--large jobs where client wants "one point of responsibility" | Mostly contractor (design and build, then pushed to designers/subbies) | Regular interim payments; often milestone or % complete | High -- more contract admin, design management, change control | Clear single responsibility, more control over programme and supply chain | You eat design errors; big exposure if you don't manage design and changes properly |
| Standard Building Contract (SBC) | Larger / complex traditional builds with full drawings/specs/bills | Mainly employer's professional team; contractor still has methods/temporary works | Interim valuations based on measured work, variations, materials | High -- detailed procedures for valuation, EOT, L&E | Clear traditional split of roles; good for complex measured work | Heavy paperwork; can feel slow and consultant-driven if you don't stay on it |
| Intermediate (IC) | Mid-size projects with several trades but not highly complex | Mainly employer, with some contractor's design where stated | Regular interims; simpler options than SBC | Medium -- lighter than SBC, heavier than MW | Fits a lot of bread-and-butter commercial work; not as admin-heavy | Can be stretched too far on complex jobs; less detailed mechanisms than SBC |
| Minor Works (MW) | Small, simple jobs and straightforward refurbs | Usually employer, with only limited contractor design | Simple interim or stage payments | Low -- short form, fewer moving parts | Quick to agree; easy for smaller firms to get their heads round | Often mis-used on jobs that are too big/complex; gaps on risk and detail |
| Term / Measured Term | Frameworks, maintenance, repeat small works over time | Depends how packages are set up; often shared or mixed | Payment against schedules of rates / measured work | Medium -- more about orders and call-offs than one-off build | Good for steady pipelines of small works; clear structure for call-offs | Easy to drift into scope creep and under-priced variations if rates are weak |
Disclaimer: SiteKiln gives you plain-English information, not legal advice. Talk to a solicitor before making big decisions on live disputes.
What to do next
- Find out which exact JCT form and version your current job is on -- if you don't know, ask your QS or the contract administrator.
- Read the Contract Particulars and any Schedule of Amendments before you start work, not after the first row.
- Make yourself a one-page crib sheet for the job: payment cycle, notice deadlines, EOT triggers, LD rate and who can instruct changes.
- If your JCT has been heavily amended, treat the amendments as a "danger list" and flag anything that moves risk onto you.
Sources
- Housing Grants, Construction and Regeneration Act 1996 -- https://www.legislation.gov.uk/ukpga/1996/53/contents
- Scheme for Construction Contracts (England and Wales) Regulations 1998 -- https://www.legislation.gov.uk/uksi/1998/649/contents
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