JCT Contracts Explained — Selecting, Drafting and Managing the Right Contract for Your Project
Why every project needs a properly prepared JCT contract
The Joint Contracts Tribunal (JCT) suite is the UK’s standard for construction contracts. The form you choose — and how you complete it — sets the rules on payment, time, design responsibility and change control. JCT’s own guidance is clear: start with procurement strategy, then choose the form that fits it. Only then draft and assemble the contract.
Contact Onform to select and assemble the right JCT form with contract-ready Employer’s Requirements (ERs) and appendices.
Start with procurement (traditional vs design & build) — then pricing basis
Traditional (design and construction are separate): the Employer’s team leads design; tender happens on complete information; independent CA/Architect administers; generally lump-sum with good cost certainty for a defined scope.
Design & Build (D&B) (single point for design and construction): the contractor prices to deliver the Employer’s Requirements; strong cost certainty if the Employer avoids changes; design and quality control depend on the clarity of the ERs and checking the contractor’s proposals.
Ask Onform to review your documents and recommend the safest route.
How JCT 2024 forms handle the Contract Sum (pricing basis)
- Lump Sum — a single price for a defined scope; variations valued as they arise. (Most JCT main forms.)
- Measurement / Approximate Quantities — price adjusts to actual measured work (more common in Standard Building Contract variants).
- Prime Cost (cost reimbursement) — Employer pays actual cost of the works plus a fee. High cost risk for the Employer; needs tight cost monitoring.
Onform will align your pricing basis with the right JCT form and complete the Contract Particulars correctly.
Main JCT options — when they’re appropriate
Minor Works 2024 (with or without Contractor’s Design)
- Use when: works are straightforward with normal trades.
- Design: by or on behalf of Employer; use the “with Contractor’s Design” variant if discrete elements (e.g., M&E, waterproofing) are contractor-designed.
- Pricing: lump sum; CA/Architect administers.
Onform tip: If any design passes to the contractor, your ERs must define those portions to avoid liability gaps. We can draft ERs.
Intermediate Building Contract 2024 (and with Contractor’s Design)
- Use when: projects involve normal/basic trades but require fuller procedures than Minor Works (e.g., stronger valuation, variation and EOT provisions).
- Design: Employer’s team; switch to the “with Contractor’s Design” form if defined elements are contractor-designed.
- Pricing: lump sum (or approximate quantities if appropriate).
Onform tip: Chosen for content and control needs, not a fixed value cap. Ideal where you want lump-sum delivery under your design team’s control with robust administration.
Design & Build 2024
- Use when: you want a single point for design and construction with a lump-sum price (or target).
- Risk/Control: strong cost certainty if the Employer avoids changes; design and quality depend on ER clarity and checks of Contractor’s Proposals.
Onform tip: You don’t lose design control if your ERs are robust. We define performance, materials, testing and aesthetic outcomes so the contractor’s proposals meet your brief. Ask us to prepare ERs.
Prime Cost Building Contract 2024
- Use when: early start is essential and scope cannot be fully defined at tender.
- Pricing: actual cost + fee; high cost risk for the Employer; requires disciplined reporting and certification.
Onform tip: Use for fast-track phases with strict cost logs, then convert to lump sum when design stabilises. We’ll set up the controls.
Risk, cost certainty and design control — in plain English
| Procurement / Form | Pricing Basis | Employer Cost Risk | Employer Design Control |
|---|---|---|---|
| Traditional — Minor Works / Intermediate | Lump Sum | Lower (defined scope) | Higher (client team leads design) |
| Traditional — with Contractor’s Design | Lump Sum | Low–Moderate | Moderate (define design portions in ERs) |
| Design & Build | Lump Sum (or Target) | Lower (if client avoids changes) | Depends on ER clarity |
| Prime Cost | Actual Cost + Fee | High | Varies (brief + controls essential) |
Ask Onform to recommend and prepare the right form based on design maturity, risk appetite and procurement strategy.
The Employer’s Requirements (and Project Brief) are the heart of control
Under D&B (and any form with contractor design), tender evaluation and cost certainty only work if the Employer’s Requirements are prepared at the right level and the contractor’s proposals are checked against them. In practice, that means a rigorous ER document covering scope, performance, materials, workmanship standards, testing/commissioning, and clearly defined contractor-design portions.
Onform prepares contract-ready ERs that align with your drawings/specs, so the priced documents and the JCT contract actually describe the same project.
How Onform helps
- Advise on the correct procurement and JCT form (Traditional, D&B, Prime Cost)
- Draft or refine Employer’s Requirements and appendices
- Complete the JCT Contract Particulars, schedules and key clauses
- Coordinate execution and issue a complete contract pack
- Act post-signing as Employer’s Agent / Contract Administrator
Request a fixed-fee proposal to have your JCT 2024 contract prepared and issued professionally.
In summary
Pick the JCT form that matches your procurement route and pricing basis, then lock in quality and design control through robust Employer’s Requirements. Traditional lump-sum (Minor Works/Intermediate) provides strong control with an Employer’s team; D&B can give cost certainty if the ERs are clear; Prime Cost is high-risk to the Employer and needs tight oversight.
Call to Action
Need help preparing your JCT contract?
Onform will select, draft and issue the correct JCT 2024 form — complete with Employer’s Requirements and appendices.
📞 Contact Onform today for a fixed-fee proposal.