AS 4000 deemed variations and latent conditions in Australia

This page is the Australian answer to the question "the work changed and nobody issued a Variation: now what?". It sits under variations in Australia, next to the jurisdiction-neutral treatment of constructive and deemed variations. The notices that make the deemed routes work are on the variation notice and claim templates page.

A note on sources. Standards Australia's forms are paywalled, and no licensed copy of AS 4000:2025, AS 4000-1997, AS 2124-1992 or AS 4902-2000 was read. AS 4000-1997 clause numbers come from a public amended copy in a tender bundle; the 2025 and AS 2124 points come from named firm summaries. Kaloriziko, V601, Carr v Berriman, Mann v Paterson and Liebe v Molloy were read on AustLII. Read the executed contract: deeming provisions are a favourite target for amendment.

The short answer

No constructive change: four routes instead

Comparison, labelled as one: in the United States, owner conduct short of a change order can itself be a change (see constructive change in the United States). Nothing equivalent exists in Australia. The research corpus recorded a negative finding for the doctrine by name; nothing located on this pass contradicts it. A pleading that says "constructive variation" tells the other side the drafter has not found a cause of action.

What does the work instead:

1. Contractual deeming. The form says an event is a Variation, or is to be valued as one. No direction is needed; the contract supplies it.
2. A written direction the record already holds. A drawing revision, an RFI response or an email from the Superintendent may be the direction, even though nobody called it one.
3. Agreement or estoppel with the Principal. A written-order clause bars recovery under the contract but does not exclude a separate express or implied promise by the Principal to pay: Liebe v Molloy [1906] HCA 67. The owner's knowledge of the work is not enough on its own. The detail is on written instruction and waiver in Australia.
4. Damages for breach. Where the Principal or its Superintendent caused the cost by breaking the contract, the claim is not a variation at all.

AS 4000:2025: what the form now deems to be a Variation

HWL Ebsworth's comparison of the 1997 and 2025 editions (31 July 2025) reports three changes that put events into the Variation regime that were not clearly there before:

Why deeming matters: margin. A deemed Variation is valued like a directed one, up the cl 36.4 hierarchy, and as summarised only its last limb (reasonable rates or prices) expressly carries profit and overheads. (Inference.) Every event moved into the deemed set is one on which the Contractor can argue for margin rather than cost. The ladder is on valuing a variation in Australia. Pricing is cl 36.4 in AS 4000-1997 (confirmed from a public amended copy); the 2025 sub-number is reported by summaries, not read.

Bill of quantities items outside the limits of accuracy

A quantity overrun is the same work in a different amount, not a change of scope, and before 2025 it was argued as remeasurement. MinterEllison's commentary on the 2024 public draft (27 May 2024) described the change as clarifying that a variation is triggered when the actual quantity falls outside the upper or lower limit of accuracy.

Two consequences follow. (Inference.)

• The deeming works both ways. A quantity below the lower limit is as much outside the limits as one above. A Principal can use the same provision to price a reduction.
• The limits are a number in the contract, not in the form. Colin Biggers & Paisley (8 October 2025) report a changed monetary threshold for deemed variations where a bill or schedule of rates forms part of the contract. That figure comes from one summary and is not printed here SINGLE-SOURCE. Read the Annexure and the bill's preambles.

Provisional sums

A provisional sum is an allowance the contract anticipated, not a change the Principal imposed. The fight is over how the expenditure is valued, and the 2025 edition reportedly answers that by sending it through the Variation regime. (Inference.) That removes a common argument that provisional-sum work is paid at cost only. Check the executed contract: a Principal wanting the old position back will amend cl 2.

The discrepancy direction, and the clause-number conflict

CONFLICT on the clause number. One source in the research corpus places discrepancies at cl 6 of the 2025 edition; the 1997 edition has them at cl 8.1. HWL Ebsworth's table numbers its rows by topic, so its "Discrepancies" row settles nothing. No 2025 clause number is printed here. Verify it against the printed standard before citing it in a notice.

The substance is less contested: where documents are inconsistent, the Superintendent directs the interpretation, and under the 2025 edition that direction is reported to be a deemed Variation. (Inference.) On an AS 4000:2025 job, an RFI answer that resolves a genuine inconsistency is a pricing event, not just an administrative reply. The Contractor who treats it as routine loses the margin the form now gives it.

AS 4000 cl 25: latent conditions

Notification. HWL Ebsworth reports that the 2025 edition changed the latent-conditions notification timeframe under cl 25 to as soon as practicable after the Contractor becomes aware. Swaab (3 September 2025) independently reports the same cl 25 change. No day count is printed here.

Effect. In the 1997 edition, cl 25.3 (Assessment), as reproduced in a public amended copy of AS 4000-1997, has the Superintendent assess the latent condition and price it under cl 36.4 as a Variation. Turtons (2018) and Tenderbuilt (2026) describe the same effect. [EDITION ALERT] No summary of the 2025 edition located on this pass says in terms that the deeming survived, or gives the 2025 sub-clause number; HWL Ebsworth mentions only the notification change. Nothing suggests the deeming was removed, but this page states it as the 1997 position only.

(Inference.) If the deeming survived, a latent condition under AS 4000 is priced with margin, and the notice is the gate. Late notice is the Principal's best defence; one summary of the 1997 edition reports a cost cut-off tied to the date of notice SINGLE-SOURCE. As soon as practicable is softer wording, but it is still a trigger that can be argued about. Record the date the Contractor became aware, because that is when the clock starts.

In Victoria, s 10B(2)(b) of the security of payment Act excluded latent-condition compensation from progress claims until ss 10A–10B were repealed from 15 April 2026. (Inference.) Latent-condition claims in payment claims served after that date can now go to adjudication; how the repeal applies to claims already on foot is not answered by the transitional s 54. See adjudicating the variation account in Victoria.

AS 2124-1992: the same facts, a different measure

AS 2124-1992 is still in wide use, and it was not superseded by AS 4000:2025. On two events it allocates margin the opposite way.

Sources: Turtons (12 October 2018, on the 1997 edition of AS 4000; and 21 September 2018). The legislative-change row rests on the first alone; whether cl 11.2 changed in 2025 was not verified.

(Inference.) A contractor moving between the two forms carries the wrong instinct with it. On AS 2124, a latent condition is a cost claim and a change in law is a variation. On AS 4000, the reverse. Identify the form before pricing either. The research corpus's statement that an AS 2124 latent-condition claim carries no margin is stronger than the secondary located supports: Turtons describes margin as more limited, not excluded.

Where Storia fits

Every deemed Variation on this page is won or lost on a document that existed at the time: the bill quantity against the measured quantity, the RFI and the Superintendent's reply resolving it, the site record showing when the Contractor became aware of the latent condition. Storia turns drawings, RFIs, schedules, correspondence and field reports into one source-linked project record, so each trigger sits in the record beside the document it came from, dated when it happened. Because the record is built as the work happens, a team can settle the pricing in coordination, or move to a claim-ready case in days rather than reconstructing the awareness date months later.

Direction by conduct: the record may already hold the direction

Where no deeming provision applies, the question is whether the Contractor was in fact directed.

On AS 2124-1992, directions under cl 40.1 arguably need not be in writing, on the corpus's summaries. An oral direction, or conduct amounting to one, may found a variation, and the fight is evidentiary: did it happen, in what terms, from whom?

On AS 4000, both editions: cl 36.1 provides that the Contractor shall not vary the work except as directed in writing, and the power to direct runs only until the Date of Practical Completion. That wording appears in two independently amended public copies (an AS 4000-1997 tender copy and the AS 4902-2000-based contract in Kaloriziko); HWL Ebsworth reports that AS 4000:2025 restates it. (Inference.) A direction need not be headed "Variation" to be in writing. A revised drawing issued for construction, an RFI response or an email instructing a changed method may satisfy the requirement, if it comes from the Superintendent and changes the work. Failing that, the claim moves to agreement or estoppel with the Principal: a harder route, treated on written instruction and waiver in Australia.

On AS 2124 the fight over an unwritten direction is about what happened. On AS 4000 it is about whether a written direction from the Superintendent exists anywhere in the record.

Kaloriziko (2025): approval is not a direction

Kaloriziko, read in full for this page, cuts the other way from what the direction-by-conduct argument hopes.

The contract was a design and construct contract in the AS 4902-2000 format, as amended, not AS 4000. Its cl 36.1, read from the judgment, provided that the Contractor shall not vary the work under the contract except as directed in writing, and gave the Principal's Representative power to direct listed kinds of variation before the date of practical completion. That is this contract's amended wording, though the same words open cl 36.1 in an amended AS 4000-1997 copy.

Two holdings matter here:

• Items the builder called variations were not variations. Five items, paid at $569,778, were within the work under the contract. The developer's approval and payment did not change that, because payment other than final payment was payment on account only. But each was a separately payable excluded item, so the builder kept the money and no credit was owed.
• Approval was not a direction. On consultancy fees (V44, $133,175), approved but unpaid, the court held that the developer's approval did not operate as a direction under cl 36.1, and could not price a variation under cl 36.4. In the court's words, "The pricing of a non-variation does not convert it to a variation." Any approval was, as the headnote puts it, "no more than an implied admission capable of being displaced by the true contractual position". The developer received a credit of $133,175.

Only $133,175 of the $3,243,175 reduction concerned variations. The rest was liquidated damages ($210,000) and a $2.9 million contribution point under a deed of settlement. Statements that the court cut a builder's variations by $3.24 million are wrong.

(Inference.) A Principal's sign-off on a variation register is evidence, not a direction, and it can be displaced. What makes something a variation is a direction under the clause or a deeming provision; pricing follows. The court's separate finding that the date for practical completion was not varied was a finding on the evidence that no variation, oral or by conduct, was proved; it is not a holding that a written-variation clause excludes oral variation.

Design development or design change on AS 4902

On a design and construct contract, the commonest "was it a variation?" dispute is whether design work filled in what the Principal's brief already required, or went beyond it. (Opinion, on the corpus's neutral analysis.) Test it clause by clause: identify the performance requirement or positive specification the direction changed. "The design moved on from tender" is not a variation; "the brief specified X and the Principal's Representative (or Superintendent, depending on the contract) directed Y" may be.

NEGATIVE FINDING (scope limited) No Australian decision drawing the design development / design change line was located in the research corpus or in two targeted searches on this pass. The developed authorities are English: Co-operative Insurance Society v Henry Boot Scotland [2002] EWHC 1270 (TCC) and Workman Properties v ADI Building & Refurbishment [2024] EWHC 2627 (TCC), and they are a comparison, not Australian authority. The neutral treatment is on what counts as a variation.

Two Australian points do stand. Kaloriziko was itself a design and construct contract, and the consultancy-fee item failed because the fees were within the work under the contract and an entire-agreement clause shut out pre-contract discussions. And there is no AS 4902:2025, so AS 4902-2000 jobs run on older conditions. An AS 4000:2025 head contract over a subcontract on older or bespoke conditions carries different formality and deeming rules at each tier. (Inference.) A deemed Variation up the line may have no deemed counterpart down it unless the subcontract is drafted to match.

Variation claim or damages claim: the measure differs

The same facts can be put four ways, and each produces a different number.

(Opinion.) Plead the deemed Variation first where the facts fit, because it needs no breach and carries the contract's margin rules. Plead breach where the Principal's failure caused the cost (a wrongly refused extension, a wrongful omission) because a variation claim will be met with "nothing was directed". Plead restitution last: it concedes the work was outside the contract, and the contract price follows you there anyway.

Acceleration: V601 v Probuild and breach damages

Constructive acceleration is a US doctrine: an owner refuses an extension the contractor is owed and insists on the original date. The Australian route is different. In V601 Developments v Probuild, on an amended AS 4902-2000 contract with a Project Manager as certifier, Digby J awarded the contractor $1,346,799 in acceleration and mitigation costs as damages for the principal's breach, by its Project Manager, of the extension-of-time machinery ([1300]–[1302], [1325]). He did not accept that refusing extensions was a direction to accelerate, even though the contract had an express acceleration clause, and declined to imply one ([1239]–[1240]).

(Inference.) Acceleration cost is not a Variation on AS 4000 unless the Superintendent actually directs it; the corpus records that AS 4000:2025 has no dedicated acceleration clause. As breach damage, it must be proved as incurred. Segregate it as it is spent. The full treatment is on acceleration in Australia, and cost proof on prolongation and delay costs in Australia.

Omissions: Carr v Berriman, and a reported 2025 change

The variation power includes omitting work. Read in its natural meaning, it does not include taking work from the Contractor to give to someone else. In Carr v J A Berriman, the owner had the structural steel that was the builder's work fabricated by another firm. Fullagar J (Williams, Webb and Kitto JJ agreeing) held that the architect's power to direct omissions did not authorise that; it would be "a most unreasonable power, which very clear words would be required to confer" (at para 14). In any event no direction had been given: the architect "was never asked to exercise his discretion" (para 15). That breach, with the failure to give possession of the site, entitled the builder to rescind (paras 20–23).

(Inference.) The claim that follows is not "value my omission". It is "there was no valid omission, and I lost work I contracted to perform", a damages claim, measured by lost profit on the work taken away, not a negative variation priced up cl 36.4.

UNVERIFIED The reported AS 4000:2025 divergence. The research corpus records that AS 4000:2025 cl 36.1 now expressly permits omission whether or not others perform the omitted work. No independent secondary confirming it was located (two targeted searches; five 2025 summaries silent). If the printed standard says so, it supplies the clear words Carr v Berriman asked for. Check the executed cl 36.1 before pleading either way.

The strongest case against this page's framing

The framing here is that AS 4000:2025 moved a meaningful set of events into the margin-bearing Variation regime, and that the contractor should reach for deeming first. Three objections deserve weight.

First, the deemed set rests on summaries of a document nobody on this page has read. Every 2025 proposition comes from firm commentary, and one (the discrepancy clause number) is in open conflict. A deeming provision may carry conditions (a notice, a threshold, a limit on what is valued) that a one-line summary drops.

Second, most Australian contracts are amended, and principals were expected to target exactly these provisions. HWL Ebsworth said of the discrepancy clause that principals would continue to seek to alter its risk allocation. On a heavily amended contract, "the form deems it" may describe nothing in the executed document.

Third, the variation-versus-damages choice may matter less than the table suggests. (Opinion.) In adjudication a well-evidenced cost claim can land close to a priced Variation; the measure bites hardest at trial and in final accounts.

None of these displaces the method. They are reasons to read the executed contract first and to treat every clause reference on this page as a pointer, not a citation.

What to do about it

(Opinion, offered as working practice rather than as authority.)

1. Identify the form and the edition (AS 4000:2025, AS 4000-1997, AS 2124-1992 or AS 4902-2000) and then read the executed amendments to cl 2, the discrepancy clause, cl 25 and cl 36.
2. Treat every quantity overrun, provisional-sum instruction and discrepancy answer as a pricing event on an AS 4000:2025 job. Log it on the day with the source document attached.
3. Date the awareness of any latent condition in writing, and notify as soon as practicable. Use the variation notice templates.
4. Find the written direction before arguing conduct. On AS 4000, either edition, search the RFI log, drawing register and Superintendent emails first.
5. Do not rely on approval. After Kaloriziko, a signed-off variation register is evidence, not a variation. Put the direction and the price on the record under the clause.
6. Choose the route deliberately. Deemed Variation for contractual events; breach damages for acceleration and wrongful omission; restitution last.

About this material Library content is general information about construction claim practice, not legal advice. Entitlement, deadlines and procedure are governed by your own contract and by the law of the place the work is performed. Reviewed September 26, 2026 · Report a correction