An extension of time under JCT works in the same order on the Standard Building Contract (SBC) and the Design and Build Contract (DB). The contractor gives a notice of delay as soon as delay becomes reasonably apparent, follows it with particulars and an estimate, and the Architect/Contract Administrator (SBC) or the Employer (DB) fixes a later Completion Date if a Relevant Event is likely to delay completion. JCT 2024 kept the clause numbers but tightened the timetable: any request for further information must come within 14 days, and the decision is due within 8 weeks rather than 12.
With the 2016 edition withdrawn and its transition period ending on 31 December 2026, new projects now run on these rules, while many live projects are still on 2016. This guide covers both.
Who this is for: commercial managers, quantity surveyors and contract managers on JCT SBC or Design and Build projects who need to claim, track or answer an extension of time, especially teams moving from the 2016 to the 2024 forms.
JCT extension of time clauses (SBC and Design and Build)
The clause numbers are the same in the 2016 and 2024 editions:
| Step | SBC | DB |
|---|---|---|
| Definitions | 2.26 | 2.23 |
| Contractor's notice of delay | 2.27 | 2.24 |
| Fixing the Completion Date | 2.28 | 2.25 |
| Relevant Events | 2.29 | 2.26 |
| Non-completion | 2.31 (Non-Completion Certificate) | 2.28 (Non-Completion Notice) |
| Liquidated damages | 2.32 | 2.29 |
The steps below use the Design and Build clause numbers. The Standard Building Contract follows the same sequence, with the Architect/Contract Administrator making the decisions.
How to claim an extension of time under JCT 2024
- Notice, forthwith. As soon as it becomes reasonably apparent that progress is being or is likely to be delayed, the contractor gives notice of the material circumstances, including the cause of the delay, and identifies any event it considers a Relevant Event (2.24.1).
- Particulars and an estimate. For each Relevant Event, the contractor gives particulars of its expected effects, including an estimate of the delay to completion. These go in the notice if practicable, otherwise in writing as soon as possible afterwards (2.24.2).
- Updates. The contractor notifies any material change in the estimated delay or the particulars (2.24.3).
- The 14-day request (new in 2024). If the Employer needs further information, it must say so within 14 days of receiving the particulars or a notice of material change (2.24.4). Under 2016 it could ask at any time.
- The 8-week decision (shortened in 2024). The Employer notifies its decision within 8 weeks, running from the later of receiving the particulars or notice and receiving the further information (2.25.2). If it decides an extension is due, it fixes the later Completion Date it estimates to be fair and reasonable.
- The final review. After practical completion, the Employer carries out a final review of the Completion Date (2.25.5). JCT says the timetable for this review is unchanged from 2016: in the standard forms it is within 12 weeks of practical completion.
Worked example: the 14-day and 8-week deadlines
An example on an unamended Design and Build Contract 2024, with illustrative dates:
| Date | What happens | Clause |
|---|---|---|
| Mon 2 November 2026 | Steel delivery slips because the Employer approved the shop drawings late. The contractor gives notice the same day, naming the Employer's impediment as a Relevant Event. | 2.24.1 |
| Fri 6 November 2026 | Particulars and an estimate of three weeks' delay to completion follow. | 2.24.2 |
| By Fri 20 November 2026 | Last day for the Employer to ask for further information (14 days). It asks on 18 November. | 2.24.4 |
| Fri 27 November 2026 | The contractor provides the further information. | |
| By Fri 22 January 2027 | The Employer's decision is due: 8 weeks from 27 November. | 2.25.2 |
Under the 2016 edition there would be no 14-day limit on the request, and the decision would be due 12 weeks from receiving the required particulars.
JCT 2016 vs 2024: what changed for extensions of time
| JCT 2016 | JCT 2024 | |
|---|---|---|
| Request for further information | Any time | Within 14 days of receiving the particulars or notice of change |
| Decision period | 12 weeks from receiving the required particulars | 8 weeks from the later of particulars and further information |
| Final review after practical completion | Within 12 weeks | Unchanged |
| Asbestos, contaminated material, unexploded ordnance | Not covered: 2.26.4 dealt with antiquities only | Added to 2.26.4 |
| Epidemics | Not listed (arguably force majeure, 2.26.14) | New Relevant Event (DB 2.26.7) |
| Changes in law and published guidance | Exercise of statutory power after the base date | Expanded to changes in law and published guidance after the base date (DB 2.26.8) |
| Clause numbering | Unchanged |
JCT Relevant Events: what's new in 2024
The Design and Build Contract 2016 lists 14 Relevant Events. They include Changes and certain instructions, impediment, prevention or default by the Employer, civil commotion or terrorism (2.26.10) and force majeure (2.26.14).
JCT 2024 added or widened three:
- Asbestos, contaminated material and unexploded ordnance discovered or excavated during the Works, unless shown in the Contract Documents or brought onto site by the contractor (2.26.4).
- Epidemics occurring after the base date, or whose effects change after it (2.26.7).
- Changes in law and published guidance after the base date, alongside the exercise of statutory powers (2.26.8).
These give time. Money is a separate question: the matching Relevant Matters for epidemics and changes in law only apply if the parties select them in the Contract Particulars.
What if the employer misses the 8-week deadline?
Neither edition grants an extension automatically when the decision is late. In Mansion Place Ltd v Fox Industrial Services Ltd [2021] EWHC 2972 (TCC), on an amended Design and Build Contract 2016, the court said the Completion Date remains as defined "until a new Completion Date is actually fixed", and that failing to fix one, or doing so late, may be a breach (para 84). The contractor can refer that breach to adjudication, and the final review gives a second chance at the right date. The court's view on this point wasn't needed for the outcome of that case, which turned on an oral agreement, but it shows why waiting for the Employer to act is risky.
Until a new date is fixed, the existing Completion Date drives liquidated damages: the Non-Completion Certificate (SBC 2.31) or Non-Completion Notice (DB 2.28), and then the liquidated damages notices (SBC 2.32, DB 2.29).
Extension of time vs loss and expense
An extension of time protects you from liquidated damages for the period it covers, but it doesn't pay for the delay. Loss and expense has its own notification, its own list of Relevant Matters and, after the FES v HFD decision, a real risk of being lost without notice. See our guide to the JCT loss and expense notice, and use the notice of delay template to get the time notice out the same day.
Where OnNotice fits
The notice of delay is due forthwith, which in practice means the day the problem shows up in a site message, an email or the minutes. OnNotice reads those as they arrive and, on JCT Design and Build projects, flags events that may need a notice of delay under clause 2.24 or a loss and expense notification under clause 4.20, with each flag linked to the original message. It drafts the notice; a person decides what gets sent. See how it works.
For the wider picture across NEC4, FIDIC and JCT, see why contractors lose entitlements to time-bars.
Sources
- JCT contents pages for the 2024 Standard Building Contract and Design and Build Contract (clause numbering)
- JCT, JCT 2024 Edition information booklet, on the review period cut from 12 to 8 weeks and the unchanged final review timetable
- JCT, Withdrawal of the JCT 2016 Edition
- RICS, JCT Design and Build 2024, Construction Journal, on clauses 2.24.4, 2.25.2 and 2.26.4
- Mills & Reeve, JCT DB 2024: delay and completion (January 2025), on the 14-day request, the 8-week decision and the new Relevant Events
- BCLP, JCT 2024 Editions: key changes
- Construction Management, Coronavirus: dealing with it under JCT, on the 14 Relevant Events in Design and Build 2016 and force majeure
- Mansion Place Ltd v Fox Industrial Services Ltd [2021] EWHC 2972 (TCC), judgment, paras 12 to 14 (clause text) and 84
This is general information about how the JCT standard forms typically deal with extensions of time, not legal advice for your contract. Time provisions are often amended, so have a contracts specialist confirm the position on your project.
Frequently asked questions
- How do I claim an extension of time under JCT?
- Give a notice of delay forthwith once delay becomes reasonably apparent, naming the cause and any Relevant Event (SBC clause 2.27, DB clause 2.24). Then give particulars of the expected effects and an estimate of the delay, and update them if anything material changes. The Architect/Contract Administrator (SBC) or Employer (DB) then decides whether to fix a later Completion Date.
- How long does the employer have to decide an extension of time under JCT 2024?
- Eight weeks, down from 12 under JCT 2016. Under the Design and Build Contract 2024, the 8 weeks run from the later of receiving the contractor's particulars (or notice of a material change) and receiving any further information the Employer asked for. The Employer must ask for that further information within 14 days.
- Is there deemed approval if the JCT employer doesn't decide in time?
- No. Neither JCT 2016 nor JCT 2024 says an extension is granted if the decision is late. A late or missing decision may be a breach, which can be referred to adjudication, but the Completion Date stays where it is until a new one is actually fixed.
- Do I lose my extension of time if I don't give a JCT notice of delay?
- Not necessarily under the unamended forms, because the Architect/Contract Administrator or Employer must still carry out a final review after practical completion. But a missing notice is a breach of the contract, weakens your position, and amendments can turn the notice into a condition precedent. Give it forthwith.
- Are epidemics a Relevant Event under JCT 2024?
- Yes. JCT 2024 added epidemics as a Relevant Event (Design and Build clause 2.26.7), so they can give an extension of time. Recovering money for them is optional: the matching Relevant Matter only applies if it is selected in the Contract Particulars.