How an extension of time claim is assessed.
Cause, notice, critical path, concurrency, and the answer in writing.

What is actually being decided

A building contract sets a date for practical completion. If the builder finishes late, the builder pays liquidated damages at the rate in the contract for every day or week of delay. An extension of time moves the date. Each day granted is a day the builder does not pay for, and a day the owner waits without compensation. Some extensions also carry a claim for the builder's delay costs. So the assessment is not an administrative courtesy. It is a decision about money, made under a procedure the contract sets out.

The superintendent makes that decision. Under AS 4000 the Principal must ensure the superintendent fulfils the role reasonably and in good faith, and the contract fixes the period within which the superintendent must respond to a claim. Neither the owner nor the builder can dictate the answer. What the owner can insist on is that the procedure is followed and the reasons are written down.

Step one: is the cause one the contract recognises?

Not every delay earns time. The contract lists the causes that qualify. Under AS 4000 they include any act, default or omission of the owner, the superintendent or their consultants, which is how variations and late information qualify, and, unless the contract's annexure excludes them, causes beyond the builder's control such as industrial conditions and inclement weather occurring before the date for practical completion. Typically they exclude anything within the builder's own control: late subcontractor engagement, defective work, poor planning, or a supplier the builder chose.

Special conditions frequently change this list. Some remove weather altogether. Some cap the days available. Some make the builder bear risks the standard form would have given the owner. The first thing the superintendent does is read the cause claimed against the executed contract, including its amendments, and never against a memory of the standard form.

Step two: was notice given in the way and within the time the contract requires?

Australian Standard contracts require the builder to notify delay promptly when it becomes aware of it, and then to claim the extension within a stated period, in writing, with the information the contract specifies. These are time bars. If the builder is late or the notice is deficient, the entitlement can be lost regardless of how real the delay was.

Time bars are unpopular with builders and are applied carefully by superintendents, because a harsh reading invites dispute. But they exist to give the owner a chance to respond to delay while it is happening rather than to pay for it afterwards, and a superintendent who ignores them is giving away a right the owner negotiated. The assessment records the date the delay began, the date the builder notified it, the date the claim arrived and what the contract required, and draws the conclusion from those facts.

Step three: did the delay affect the date for practical completion?

This is where most claims are won or lost, and where most owners are least equipped to judge. A delay to one activity only delays the project if that activity is on the critical path, the chain of tasks that determines the end date. A two-week hold on landscaping while the structure is still going up does not push out completion. A two-week hold on the structure does.

The superintendent looks at the builder's programme at the time of the delay, the activity affected, whether it was critical, and whether the builder had float it could have used. Where the builder's programme is out of date or was never updated, which is common on smaller projects, the superintendent has to reconstruct the position from site records, and the claim is weaker for the builder's failure to keep the programme current. Owners should insist from the first month that an updated programme accompanies every claim.

Step four: was anything else delaying the work at the same time?

Concurrent delay is the hard case. The owner's variation held up the kitchen for two weeks, and in the same two weeks the builder's plasterer failed to turn up. Two causes, one period, one of them the builder's fault. AS 4000 directs the superintendent to apportion the delay according to each cause's contribution where qualifying and non-qualifying causes overlap; other contract forms and the case law treat concurrency differently, and special conditions often address it expressly.

The practical point for an owner is that the superintendent must identify concurrent causes and address them in the determination, rather than granting the full period because the owner's cause was real. Where concurrency reduces or removes the builder's entitlement, the reasons say so.

Step five: how many days, and are costs attached?

The extension is the period the qualifying cause actually delayed practical completion, no more. It is not the period the builder asked for, and it is not the period the builder was on site doing something else. Where the contract allows delay costs for certain causes, the costs are assessed separately and only for the days granted for a cause that carries them. A claim that bundles time and money together is separated before it is assessed.

Step six: the determination, in writing, inside the period

The superintendent's determination states the cause claimed, the notice history, the critical path finding, any concurrency, the days granted or refused, the revised date for practical completion, and whether delay costs apply. It is issued within the period the contract sets. Silence is not neutral: under AS 4000, if the superintendent does not direct the extension within the period the contract allows, there is a deemed assessment and direction of the extension as claimed.

The determination is also the document the owner will rely on if the matter goes to adjudication, expert determination or court. A one-line email granting "two weeks as requested" is not a determination. It is a concession, and it will be read as one.

What the board should see

• An extension of time register: every claim, the days claimed, the days granted, the running revised completion date.
• The determination for each claim, with the reasons.
• The current programme, and confirmation that it was updated with the claim.
• The liquidated damages position: what would apply today if the builder finished today.

Those four items, reported monthly, mean the board never learns about a slipped opening date from the builder's final account.

This article is general information about the assessment of extension of time claims under Australian Standard general conditions of contract. It is not legal advice. The executed contract and its special conditions govern any particular claim, and the treatment of concurrent delay in particular varies between contract forms and jurisdictions.

Sources. AS 4000-1997 General conditions of contract, incorporating Amendments 1 to 3 (Standards Australia). Checked against the current versions on 9 September 2026.