Assessing an extension of time
Deferring the decision until the end of the job feels prudent and is the one thing the contract does not allow. Assess on what is known, and revisit if it changes.
QScope Team · 29 January 2026 · 5 min read
An extension of time claim arrives as a notice, usually thin, sometimes months after the event it describes. What happens next is governed by the contract, and the contract is more prescriptive than most people assume.
The clock on the certifier
Under JCT the contract administrator has a defined period from receipt of the particulars to notify a decision. Twelve weeks is typical, and it runs from the particulars, not from the notice.
That distinction matters both ways. A contractor who gives notice and never provides particulars has not started the certifier's clock. A certifier who receives full particulars and sits on them for six months is in breach of the assessment obligation, whatever the merits of the claim.
Assess prospectively
The obligation is to assess what is fair and reasonable on the information available, at the time. It is not to wait until the works finish and then work backwards from the actual completion date.
Retrospective assessment is attractive because it removes uncertainty, and it is wrong for two reasons. It denies the contractor the ability to plan around a known completion date, and under JCT it hands the contractor an argument that time has been set at large because the machinery for fixing it was not operated.
The standard is fair and reasonable
Not generous, not defensive. The question is what extension is fair and reasonable in the circumstances, judged against the delay the relevant event actually caused to completion.
That means the analysis is about the critical path. An event that delayed a non-critical activity by four weeks, where that activity had five weeks of float, delayed completion by nothing.
Float belongs to the project
The usual position under JCT is that float is available to whoever needs it first. A relevant event that consumes float without pushing completion generates no extension. A contractor who has already consumed the float through its own delay does not thereby convert a later employer event into a critical one, unless it genuinely became critical.
Write down the reasoning
The award is a number of weeks. What makes it defensible is the sentence explaining how the number was reached: which event, which period, what was on the critical path, and what was allowed or disallowed and why.
Two years later nobody remembers, the people have moved on, and a number with no explanation looks like a negotiation rather than a decision.
What the award does
It moves the completion date. From that moment, liquidated damages run from the new date, and any certificate of non-completion issued against the old one is cancelled and must be reissued.
It does not, on its own, carry loss and expense. That is a separate assessment against a separate list, and granting time without addressing money leaves half the claim open.
The review
JCT provides for a review after practical completion, in which the certifier can confirm, increase or, within limits, reduce previous awards. It exists precisely so that prospective assessment can be made without fear of being locked into an early view. Use it, rather than treating the first award as final.
QScope keeps notice dates, particulars dates and award dates against every delay event, so the assessment clock is visible while there is still time to act on it.