JCT contracts are the most widely used standard form contracts in the UK construction industry. They establish a detailed framework governing the relationship between employers and contractors — covering payment, programme, design responsibility, risk and the process for managing change. Understanding how risk is allocated under these contracts, and where the boundaries of that allocation sit, is fundamental to managing a construction project effectively from either side.
The JCT suite includes a range of forms designed for different procurement routes and project types. The Standard Building Contract, the Design and Build Contract and the Intermediate Building Contract each allocate risk differently, reflecting the different roles and responsibilities that arise under each procurement model. In each case, however, the core commercial questions are the same: who is responsible for design, how are changes managed, how is programme risk handled and what happens when things go wrong.
Risk allocation in JCT contracts
JCT contracts divide risk between the employer and the contractor according to the nature of the risk and the party best placed to manage it. Some risks — such as design deficiencies in employer-supplied information or changes instructed by the employer — sit with the employer. Others — such as the contractor's means and methods of construction, subcontractor performance and contractor-caused delay — sit with the contractor.
The balance of risk is not fixed across all JCT forms. Under a traditional procurement route using the Standard Building Contract, the employer retains responsibility for the completeness of the design and the contractor constructs to that design. Under the Design and Build Contract, design responsibility is largely transferred to the contractor. This shift in responsibility has significant commercial implications for both parties and needs to be understood clearly before a contract is entered into.
In practice, the standard risk allocation is frequently modified by amendments — either in the contract particulars or through bespoke amendments to the conditions. These modifications can shift risk in ways that are not immediately obvious from a high-level review of the contract. Careful scrutiny of amendments before execution is one of the most important steps in managing contractual risk.
Design responsibility
Design responsibility is one of the most commercially significant risk allocation questions in any construction contract. Under the JCT Standard Building Contract, design responsibility remains with the employer and their professional team. The contractor's obligation is to build in accordance with the information provided. If that information is deficient, the contractor has a basis for seeking additional time and money to deal with the consequences.
Under the JCT Design and Build Contract, the position is reversed. The contractor takes on responsibility for developing the design from the employer's requirements and is responsible for ensuring that the completed building meets those requirements. The standard of design responsibility under a Design and Build Contract is one of fitness for purpose unless the contract expressly limits it to the reasonable skill and care standard — a distinction that has material consequences for both the scope of liability and the availability of professional indemnity insurance cover.
Where a traditional contract includes contractor-designed portions — often referred to as CDP works — the design risk for those portions transfers to the contractor, while the employer retains responsibility for the remainder of the design. Clear delineation of CDP scope at the outset is essential to avoid disputes about the boundary of design responsibility later in the project.
Variations and change management
The JCT variation mechanism gives the employer the right to instruct changes to the works. This right is valuable but comes at a cost: properly instructed variations entitle the contractor to additional payment and, where the variation affects the programme, additional time. Managing the variation process carefully is therefore important for employers seeking to maintain cost and programme control.
For contractors, the variation mechanism is equally significant. Work carried out without a formal instruction — or work that falls outside the defined scope but which the contractor proceeds with informally — may not attract additional payment. The discipline of obtaining written instructions before proceeding with varied work is one that many contractors learn through experience rather than anticipation.
Disputed variations — work that the employer considers to be within the original scope and the contractor considers to be additional — are a frequent source of dispute. Maintaining a clear record of the scope at the time of contract, instructions given during the project and the contractor's responses is the most reliable way to manage this risk from either side.
Programme risk and extensions of time
JCT contracts provide a mechanism for extending the contract completion date where the contractor is delayed by events that are not their responsibility. These are referred to as Relevant Events and include employer-caused delays, exceptionally adverse weather, statutory undertakers' delays and other specified causes.
The extension of time mechanism serves two functions. First, it provides the contractor with relief from the obligation to complete by the original completion date — and therefore from liability for liquidated damages — where the delay is attributable to a Relevant Event. Second, it preserves the employer's right to deduct liquidated damages for contractor-caused delay, which would be lost if the employer's own acts of prevention had contributed to overrun without a corresponding extension being granted.
Notices are central to the operation of the extension of time regime. Contractors are generally required to give timely notice of delay and the cause of it. Failure to comply with notice requirements does not automatically defeat an extension of time claim under JCT forms, but it can complicate the assessment and create grounds for dispute. Employers, for their part, must ensure that extensions are assessed properly and in good time — a failure to do so can itself generate claims.
Loss and expense claims
Where the regular progress of the works is materially affected by specified matters — including employer-instructed variations, late receipt of information, employer-caused access issues and other listed causes — the contractor is entitled to recover loss and expense under JCT contracts. This is a separate entitlement from an extension of time and compensates the contractor for the financial consequences of disruption and prolongation.
Loss and expense claims are often the most contentious element of the final account. The contractor must demonstrate both that the regular progress of the works has been affected and that the financial loss claimed flows from the specified cause. Contemporaneous records, properly maintained throughout the project, are the foundation of any well-constructed loss and expense claim. Retrospective reconstruction — attempting to build a claim from incomplete records at the end of the project — is rarely straightforward and is easily challenged.
For employers, understanding the basis on which loss and expense claims are assessed, and the information that contractors are entitled to rely upon, is important for managing the final account process. Claims that are poorly substantiated can be challenged; claims that are properly evidenced require a considered and timely response.
Practical considerations
- Identify which JCT form applies to the project and understand how it allocates design responsibility before contract execution — the implications are significant and differ materially between forms
- Review any bespoke amendments carefully, as these can shift the standard risk allocation in ways that are not apparent without a detailed review
- Establish a clear process for instructing and recording variations at the outset of the project — informal instructions and scope creep are among the most common causes of final account disputes
- Ensure that notice obligations under the extension of time and loss and expense provisions are understood and observed throughout the project — late or incomplete notices can undermine otherwise valid entitlements
- Maintain contemporaneous project records throughout — site diaries, correspondence, instructions, payment applications and programme updates — as these form the evidential foundation for any claim or defence
- Where a contractor-designed portion is included within a traditional contract, define the scope of CDP works precisely and allocate design liability clearly in the contract documents
Conclusion
JCT contracts provide a well-established framework for managing the relationship between employers and contractors. But the standard provisions are a starting point, not a fixed outcome. The way risk is allocated under any particular contract depends on the form selected, the amendments adopted and the way the contract is administered during the project.
For both employers and contractors, the commercial consequences of the risk allocation built into a JCT contract are best understood before the contract is signed rather than after a dispute has arisen. Early engagement with the contract terms — and with the practical implications of how risk is distributed across design, variations, programme and loss and expense — is the most reliable way to manage those consequences.
We regularly advise employers, contractors and investors on JCT contract risk, amendments and administration across construction and real estate projects.
This includes strategic contract review before execution, analysis of risk allocation within JCT terms, and advice on contract administration issues that arise during project delivery.
Please contact us if you would like to discuss a JCT contract issue or a project you are currently involved in.