Contracts
Extension-of-time mechanisms
An extension-of-time clause exists to keep the completion date operable when something outside the contractor’s risk delays the work. Without one, employer-caused delay can put time at large.
- Jurisdiction
- Comparative across the main standard forms
- Law and editions as at
- 3 August 2026
- Last reviewed
- 3 August 2026
- Editorial status
- Editorial draft, not yet independently reviewed
The common structure
- A list of qualifying events.
- A notice obligation, with or without a hard bar.
- An assessment by a named person, on stated information.
- A revised completion date, and relief from damages for the extended period.
- Often, a review after completion when the full picture is available.
Who decides
On the traditional JCT forms the architect or contract administrator assesses what is fair and reasonable. On design and build the employer’s agent fills that role. Under NEC the Project Manager accepts a quotation or makes their own assessment. Under FIDIC the Engineer makes a determination after consultation. The identity of the decision-maker changes the practical dynamics of a claim as much as the wording does.
Causation is the working word
A contractor does not get time because a qualifying event happened. It gets time because a qualifying event caused delay to completion. Establishing that link is where the programme and the site record earn their keep, and it is the step most often asserted rather than proved.
Prospective or retrospective
Some contracts require the effect of an event to be assessed when it arises, using the programme as it then stood. Others leave the assessment open, in practice inviting a retrospective analysis. That instruction is part of the analytical question and it constrains the method, which is why the contract is read before the method is chosen.
What the extension is worth
Relief from liquidated damages for the extended period, and nothing more unless the contract says otherwise. The money runs on its own track with its own trigger list and its own proof.
Where the record comes in
Every mechanism on this page turns on evidence: what happened, what was known and when. A record built as the job happens is worth more than any argument assembled afterwards. Construction Metric keeps that record automatically, from the messages, photographs and voice notes a site team already sends.
Built by AI Metric
The analysis on this site is only as fast as the evidence behind it. AI Metric builds bespoke systems for consultancies, contractors and claims teams: document and correspondence triage, event registers assembled from the project record, programme and cost reconciliation, and drafting support that always cites the document it came from. Built for review by your own experts, never to replace their judgement.
Do not overread this page
The forms are described in general terms and are all routinely amended. Your executed contract controls, and the assessment on any project is for the person the contract names.
General explanation of how contract mechanisms, analysis methods and legal principles generally work. It is not legal or contractual advice, not an opinion on any project, and no standard-form contract wording is reproduced anywhere on this site. Standard forms are routinely amended, so every default described here, including every time period, can be different on your project. Your executed contract, as amended, and the governing law and forum always control. Deadlines may already be running: if an event has occurred, preserve your position and take qualified advice.