Extension of Time, Variations and Latent Conditions

Before considering how your contract handles an extension of time, a variation or a latent condition, you’ll need professional advice from a construction lawyer. These three mechanisms are the ones most likely to move money and time on a job that is already under way, and the drafting that decides each of them is settled before the builder starts, not after the claim lands. That advice is worth most while the tender documents are still yours to change. The consequences fall on you rather than on the builder or the superintendent: the extra cost lands in your total development cost, interest keeps running on the drawn facility while the programme stretches, presold settlements move, and if a notice provision you relied on turns out to be unenforceable you are the party funding the difference. This guide is written to make that conversation shorter and better informed, not to answer it. The section on what to ask your construction lawyer sets out the specific questions.

The rules, dates and thresholds below were current at the date of writing and change. Two of them changed recently and directly: Victoria’s security of payment regime was amended with effect from 15 April 2026, and it now allows a notice-based time bar to be declared unfair, and Western Australia has had an equivalent provision since its 2021 Act commenced. Each linked primary source is where to confirm the current position before relying on it.

Why do extensions of time, variations and latent conditions belong in one guide?

Because they are the three routes by which a fixed contract sum and a fixed completion date stop being fixed, and because they feed each other.

A latent condition is usually discovered, then instructed around. The instruction is a variation. The variation takes time, so the contractor claims an extension of time. If the extension of time carries delay costs, a fourth number appears. One event on site has now touched your contract sum, your programme, your liquidated damages entitlement and your interest bill, and each of those consequences runs through a different clause with a different notice clock.

Developers who treat these as three separate administrative processes tend to discover the connection late. The useful framing is the reverse. Ask what a single unexpected event on your site does to each of the four numbers, and then read the clauses that decide each one.

There is a separate reason they belong together. The mechanics of all three are notice-driven. Each generally requires the contractor to tell you something within a defined period, and each generally makes the entitlement contingent on that notice. That shared architecture is why a change in the law about notice provisions, which is what happened in Victoria in April 2026, affects all three at once.

What does an extension of time actually give the contractor?

It moves the date for practical completion, and nothing more unless the contract says otherwise.

This is the distinction developers most often collapse. An extension of time is relief from lateness. It changes the date against which the contractor’s performance is measured, which means the contractor stops accruing liability for liquidated damages over the extended period. It does not, by itself, entitle the contractor to be paid anything for the extra time.

Payment for the extra time is a separate entitlement, usually called delay costs or delay damages, and a contract can grant an extension of time without granting it. The two are commonly written into adjacent clauses, which is part of why they get conflated, but they answer different questions:

The extension of time question is: who bears the consequence of the programme moving?

The delay cost question is: who pays the contractor’s time-related overhead while it does?

A contract can answer these differently for different causes. It is common to see forms that grant an extension of time for weather, industrial action and the acts of authorities, but grant delay costs only where the delay was caused by the principal or those for whom the principal is responsible. Under that split, a six-week weather delay costs you your liquidated damages recovery for six weeks and your own holding costs for six weeks, but not the builder’s preliminaries. A six-week delay caused by your architect issuing revised drawings late can cost you all three.

The practical question to hold in front of the lawyer is not whether your contract has an extension of time clause. It will. It is which causes carry an extension of time only, which carry an extension of time plus delay costs, and how those delay costs are calculated and capped.

What counts as a qualifying cause of delay?

Whatever the contract says qualifies, which is why the list is worth reading line by line rather than assuming it.

Most general conditions define a category of causes that can support an extension of time. The categories that recur across Australian forms tend to include acts, omissions or breaches by the principal or the superintendent, variations directed by the principal, inclement weather beyond a defined allowance, latent conditions where the contract puts that risk on the principal, industrial action of a defined kind, delays by authorities in granting approvals, and changes in statutory requirements.

Three points about that list matter more than its contents.

The weather allowance is a number, not a concept. Most forms allow an extension of time only for weather beyond a stated allowance for the site and season, set in the annexure. A generous allowance transfers weather risk to the builder and shows up in the tender price. A tight one keeps it with you. It is a negotiated figure, and it is often accepted without anyone modelling what the site’s historical rainfall actually implies.

A change in statutory requirements is a live category. National Construction Code adoption dates, state building reform commencements and changes to certification requirements can all land mid-build. Whether the contractor gets time, cost, both or neither for that is a drafting question decided before any of it happens.

Your own conduct is the category you control and the one most often overlooked. Late responses to requests for information, late principal-supplied items, slow variation decisions, restricted site access and delayed authority approvals you were responsible for pursuing are all capable of being qualifying causes. Every day your side takes to answer a question is potentially a day of extension of time and, in many forms, a day of delay costs.

How do the notice clocks work?

On two separate timers, and missing either one is generally what kills a claim rather than the merits of the claim itself.

The architecture in the Australian Standard general conditions and most forms derived from them runs in two stages. First, a notice of delay, due promptly once the contractor becomes aware of something that will probably cause delay, identifying the cause and an estimate of the effect. Second, a formal claim for an extension of time within a defined number of days of the point at which the contractor should reasonably have become aware that the delay had occurred, supported by evidence of causation and extent.

For a developer, the two-stage structure is the useful part. The first notice is an early warning, and its real value is that it arrives while the event can still be managed. A contractor telling you in week three that a services relocation will probably push the slab is giving you the chance to reorder the programme, accelerate another trade, or accept the delay knowing what it costs. The same information arriving as a formal claim in week nine is an invoice.

Variations run on their own clock. A common structure requires the contractor to notify within a short period that it considers an instruction to be a variation, before doing the work. Latent conditions typically run on a shorter clock again, because the point of the notice is to let the principal inspect the condition before it is covered up or removed.

Three practical consequences follow.

Silence is a position. If the contract makes the entitlement contingent on notice and the contractor does not give it, the contractor may lose the claim. That looks like a win for the developer. The section below on prevention and the sections on statutory review of time bars explain why it may not be.

The clock usually starts at awareness, not at the event. A provision that runs from when the contractor “should reasonably have become aware” invites an argument about what the contractor knew and when. Contemporaneous site records are what resolve that argument, and they are generally the contractor’s records unless your superintendent keeps their own.

The person receiving the notice matters. If notices must go to the superintendent and they go to the site supervisor, whether that counts is a question of construction of your contract. Getting that right is administrative, cheap, and regularly got wrong.

Can a notice-based time bar be struck down?

In Victoria and Western Australia, yes, by statute, in defined circumstances. Elsewhere in Australia the question is one of general contract law rather than a specific statutory test.

This is the most significant recent change in this area and the one least reflected in the material written for developers.

Western Australia. Section 16 of the Building and Construction Industry (Security of Payment) Act 2021 (WA) deals with notice-based time bars. It defines a notice-based time bar provision as one that makes contingent on the provision of notice either “an entitlement to payment for construction work carried out or undertaken to be carried out, or for related goods and services supplied or undertaken to be supplied, under the contract” or “an extension of time for doing a thing that affects an entitlement referred to in paragraph (a)”. Such a provision “may be declared under this section to be unfair in the case of a particular entitlement under the contract if compliance with the provision in that case … is not reasonably possible; or … would be unreasonably onerous.”

The declaration can be made by an adjudicator or review adjudicator, a court, an arbitrator, or an expert appointed by the parties. The effect is narrow: the provision “has no effect in the case of the particular entitlement that is the subject of the proceedings in which it was declared unfair, but continues to have effect in other circumstances or challenges arising under the same or a related contract.” The contractor alleging unfairness carries the onus.

The matters the decision-maker must consider are set out in the section and are worth reading in full, because they are the shape of the argument you would be answering. They include when the party required to give notice would reasonably have become aware of the event, having regard to the last day notice could be given; when and how notice was required to be given; the relative bargaining power of each party; an irrebuttable presumption that the parties read and understood the contract; a rebuttable presumption that the notifying party has the commercial and technical competence of a reasonably competent contractor; and, where the complaint is that compliance would be unreasonably onerous, whether the matters set out in the notice are final and binding.

Victoria. The Building and Plumbing Commission states that from 15 April 2026 the Victorian security of payment regime includes an equivalent concept, and that the amendments apply to “all construction contracts, including contracts entered into before the amendments came into operation on 15 April 2026”. The Commission describes a notice-based time bar as a provision making contingent on notice an entitlement to be paid, “an extension of time for doing a thing that affects an entitlement referred to above”, or the release of a performance security, and states that such a provision “may be determined to be ‘unfair’ by an adjudicator, a court, an arbitrator or an appointed expert if compliance with the provision … is not reasonably possible or … would be unreasonably onerous”.

The retrospective reach is the part with immediate consequences. A Victorian contract signed in 2024, with a notice regime negotiated on the assumption that a missed notice ended the claim, is now a contract in which that assumption is testable. The Commission notes transitional provisions can displace that, including where a payment claim was issued or an adjudication application made before the commencement date.

For a developer the shift is not that time bars have gone. They have not, and in both jurisdictions the onus sits with the party attacking them. The shift is that an aggressively short or procedurally elaborate notice provision has become a less reliable defence than it used to be, and in two jurisdictions the reliability now depends on facts about the particular claim rather than on the words alone. Whether that changes what your contract should say is a question for your lawyer, and it is a different question in Perth and Melbourne than it is in Sydney or Brisbane.

The relevant provisions are in the Western Australian Act and, for Victoria, in the Building and Plumbing Commission’s summary of the changes affecting construction contracts.

What happens if nobody can extend the date?

The date can fall away, and the liquidated damages entitlement can go with it. This is the prevention principle, and it is the reason a strict notice regime is not automatically in a developer’s interest.

The principle is that a party generally cannot enforce a time obligation against the other party where its own acts caused the failure to meet it. Applied to a building contract, if the principal or its representatives cause delay and the contract gives no route to extend the date for practical completion for that delay, the date can be displaced and time becomes “at large”. The contractor is then obliged only to finish within a reasonable time, and with no fixed date to measure lateness against there is generally nothing for liquidated damages to attach to.

In Gaymark Investments Pty Ltd v Walter Construction Group Ltd [1999] NTSC 143, the contract made compliance with notice requirements a condition of any extension of time. The contractor did not comply, so it could not obtain an extension for delays that were nonetheless the principal’s responsibility. Time went at large and the principal recovered no liquidated damages at all. The reasoning has been debated and distinguished since, and how a court would treat a comparable clause today is a question for your lawyer on your contract. The commercial lesson is more durable than the legal debate: a notice regime that leaves no route to extend time for the principal’s own delays is not obviously the principal’s friend.

The usual drafting answer is a clause allowing the superintendent or contract administrator to extend the date unilaterally, whether or not a valid claim has been made. That clause is what keeps the date alive when the contractor misses a deadline, and it is standard across the Australian Standard general conditions and most bespoke forms.

That answer has its own consequence. In Peninsula Balmain Pty Ltd v Abigroup Contractors Pty Ltd [2002] NSWCA 211, the New South Wales Court of Appeal considered a unilateral power of that kind and held that it was to be exercised honestly and impartially, with the result that the superintendent was required to grant an extension of time even though the contractor’s own claim was out of time. So the clause that protects your entitlement also constrains how the person administering your contract can behave.

The practical point is narrow and worth putting to the lawyer directly. A superintendent who refuses an extension of time that the contractor was substantively entitled to, on the ground that the paperwork was late, may be creating the exposure rather than avoiding it.

How is concurrent delay handled?

By whatever the contract says, and if the contract is silent the position is contested.

Concurrent delay is the situation where two independent causes of delay, one the principal’s risk and one the contractor’s, operate over the same period. Australian standard forms commonly deal with it by apportionment, giving the superintendent a discretion to apportion the delay between the causes. Bespoke amendments frequently replace that with a rule, most often one denying the contractor an extension of time to the extent that a contractor-risk event was operating concurrently.

Two observations for a developer.

The concurrency clause is where the prevention principle and the notice regime meet. If your amendment denies any extension of time whenever a contractor delay is running concurrently, and the principal’s own delay is one of the concurrent causes, you have created exactly the structure the prevention principle is aimed at. Whether it survives is not something a guide can answer on your facts.

Concurrency is a programming question before it is a legal one. Establishing that two causes were genuinely concurrent, and over what period, requires a programme that was baselined, updated and retained. Our guide to construction programming covers what makes a programme evidentially useful rather than decorative, and that distinction is where most concurrency arguments are actually won and lost.

When does an instruction become a variation?

When it changes the scope of the work as defined by the contract documents, and the contract’s definition of scope is what decides it.

That sounds circular, and in practice it is the whole fight. A variation is a change to the work the contractor agreed to do. The contractor priced a set of documents. Anything within those documents is included. Anything outside them is a variation, and is paid for separately.

Which means the quality and completeness of your documentation set is the single biggest determinant of your variation exposure. A tender issued on drawings at eighty per cent completion will generate variations for the missing twenty per cent, and the price of that twenty per cent is set after the builder has been appointed and you no longer have a competitive market. Compressing the design programme to hit a land settlement date is the most common way developers create this problem for themselves, and the cost of it appears eight months later in a place that looks unrelated.

A few categories generate most of the argument.

Documentation gaps and inconsistencies. Where the drawings and the specification disagree, the contract usually sets an order of precedence. Whether resolving the inconsistency is a variation depends on which document wins and what the contractor was entitled to assume.

Provisional sums and prime cost items. These are allowances for work not yet defined. When the real number lands, the difference adjusts the contract sum through the variation machinery. A contract carrying large provisional sums is not a fixed-price contract in any meaningful sense, and the sum you signed is a forecast.

Statutory and authority requirements. Conditions imposed by a certifier, a services authority or a council after the contract is signed usually land as variations unless the contract puts the risk of them on the contractor.

Design development. The distinction between resolving the design the contractor priced and changing it is the fine line, and it is usually drawn by reference to what a competent contractor would have inferred from the documents.

Standard forms also increasingly attach consequences to the contractor’s silence. The New South Wales government GC21 form is a useful illustration because its amendments are published. The buy.nsw amendment log records changes made on 1 December 2025 adding notes confirming that a contractor commits a breach of contract if it fails to notify a possible variation or a delay within the specified period. Read the equivalent provision in your own form and work out which side the silence favours.

How is a variation valued?

Under the contract’s valuation rules, in a defined order, and the order is usually more favourable to you the earlier in the list a variation falls.

The typical hierarchy runs: rates or prices already in the contract, then rates in the schedule of rates applied to the new work, then reasonable rates or prices determined by the superintendent, then daywork. Each step down that list moves you from a price you agreed in a competitive tender to a price determined after the fact.

Two levers sit in that hierarchy and both are pulled before the contract is signed.

The schedule of rates is a pricing document, not paperwork. A contract with a thin schedule of rates pushes most variations down to “reasonable rates”, which is a negotiation. A contract with a detailed one keeps a larger share at tendered rates. Builders understand this asymmetry well and developers frequently do not.

Daywork is the most expensive way to buy anything. It is paid on cost plus a margin with no productivity risk on the contractor. A form that allows the superintendent to direct daywork, rather than requiring it, is a different document from one that does not.

Whether the contractor can start work before the price is agreed is the other variable. Most forms allow the superintendent to direct a variation and have it valued later, because the alternative is that the job stops while the parties negotiate. That is practical, and it is also the mechanism by which a developer ends up committed to work at an unagreed price. The trap is the sequencing, not the rate.

Can a disputed variation be pushed through a payment claim?

In most Australian jurisdictions, yes, and Victoria’s recent change made that materially more true there.

A builder’s progress claim is usually also a payment claim under the relevant security of payment legislation. That legislation provides a fast statutory process for getting an interim determination of what is payable, and it generally sets the valuation rules an adjudicator applies.

The New South Wales Act is representative on valuation. Under the valuation provisions of the Building and Construction Industry Security of Payment Act 1999 (NSW), construction work is valued in accordance with the contract, including “any variation agreed to by the parties to the contract by which the contract price, or any other rate or price set out in the contract, is to be adjusted by a specific amount”, and where the contract does not provide, by reference to the reasonable value of the work. The Western Australian Act uses materially the same formulation, referring to “any variation agreed to by the parties to the contract by which the contract price, or any other rate or price set out in the contract, is to be adjusted by a stated amount”.

The practical effect for a developer is that a variation you have not agreed does not simply sit unpaid. It can be put in front of an adjudicator on a short statutory timetable, and your reasons for not paying are generally locked in at the payment schedule stage. Whatever you did not say then, you generally cannot say later in that adjudication.

Victoria has changed most. Victoria was previously the only jurisdiction that carved whole categories of claim out of adjudication through the concepts of “claimable variations” and “excluded amounts”. The Building and Plumbing Commission’s summary of the scheme changes records that both concepts have been repealed, so claimants no longer have to work out whether a variation can be claimed, and amounts previously excluded can now be claimed, including compensation for events arising from latent conditions, time related costs, damages for breach of contract and any amount arising at law. If your Victorian contract administration was built around the assumption that a delay cost claim could not be adjudicated, that assumption no longer holds.

The repeal runs both ways, which is the part favourable to a developer. A respondent is no longer prevented from relying on previously excluded amounts either, so liquidated damages for delay can now be set off against a payment claim in a payment schedule.

The Victorian amendments also render ineffective any term providing for payment of a progress payment, or release of a performance security, later than 20 business days after the claim is served, and parties cannot agree a longer period. Where the contract says nothing about a due date, payment falls due 10 business days after the earliest day a claim could be served. They further restrict pay-when-paid provisions.

Three other changes shift the timetable. The latest day for serving a payment claim is now the day before the date six months after practical completion, or six months after the supply of all related goods and services, against three months previously, unless the contract allows longer. That lengthens the tail on claims after a job finishes. A respondent served with notice of a claimant’s intention to apply for adjudication now has 5 business days to serve a payment schedule, up from 2. And an adjudicator has 10 business days from appointment or from the last day for an adjudication response, whichever is later, extendable by agreement. The Building and Plumbing Commission’s summary of the changes sets out the detail and is the place to confirm the current position.

A separate change affects the other direction. Before having recourse to the whole or any part of a performance security, a party must serve written notice of that intention, identifying the contract and the provision relied on, the amount if it is not the whole security, and the circumstances said to entitle it to recourse, and must then wait at least 5 business days, or longer where the contract says so. Business days exclude Saturdays, Sundays, Victorian public holidays and the period from 22 December to 10 January. The notice requirement forms part of every construction contract, so a developer intending to call on a bank guarantee in Victoria now has a notice step and a waiting period ahead of it.

What is a latent condition?

A physical condition on or near the site that differs from what the contractor could reasonably have anticipated at the time of tender. The definition varies between forms and the variation is where the money is.

The usual suspects are contaminated soil, unexpected rock, buried structures, poor or variable ground, groundwater at unanticipated levels, unrecorded services, archaeological or heritage material, and unrecorded underground works from a previous use.

Three drafting variables decide how much of that risk is actually yours.

The reference point. Most definitions measure the condition against what an experienced and competent contractor could reasonably have anticipated. Some measure it against the information the principal actually provided. The second formulation transfers substantially more risk to you, because it removes the contractor’s obligation to make its own inferences from what it was given.

The information you supplied. Geotechnical reports, contamination assessments, services searches and survey information provided at tender generally define what could be anticipated. Providing more information narrows the latent conditions the contractor can later claim. Providing less does not protect you, because the definition still runs on what could reasonably have been anticipated.

The notice and inspection regime. Latent condition clauses typically require short notice so the principal can inspect. The notification periods are genuinely short and they move. The GC21 amendment log shows the notification period for adverse site conditions moving from seven days to three business days in December 2025 and reverting to seven days in February 2026, and shows the entitlement narrowed by the removal of the word “direct” from the phrase describing recoverable additional costs. A day either way on a notification clock, or a single word in a costs formula, can decide whether a claim survives and what it is worth.

Latent conditions are also the risk that most directly drives the size of the contingency you need. Our guide to construction contingency covers how to size that allowance against the risks your contract actually leaves with you.

Do tender disclaimers protect the principal?

Not reliably, and the assumption that they do has been tested.

Principals commonly attach disclaimers to geotechnical and site information provided at tender, to the effect that the information is provided for convenience only, is not warranted, and is not to be relied on. The intent is to hand over the data without accepting responsibility for its accuracy.

In BMD Major Projects Pty Ltd v Victorian Urban Development Authority [2007] VSC 409, the Supreme Court of Victoria considered the effectiveness of tender disclaimers in the context of latent conditions. The case is the one developers in this area are most often pointed to, and the broader lesson drawn from it is that a disclaimer does not automatically neutralise the effect of information provided, particularly where the contract’s own latent conditions definition measures the condition against what could reasonably have been anticipated from that information.

There is a second exposure that a disclaimer does not touch at all. Providing site information that is misleading, or omitting material you hold, can raise questions under the misleading or deceptive conduct provisions of Australian Consumer Law and the Australian Securities and Investments Commission Act 2001 (Cth), and those provisions do not depend on what your tender documents say about reliance. That is a specific question for your lawyer, and it is the reason the useful pre-tender question is what to disclose rather than how to disclaim.

What do these three mechanisms do to a feasibility?

They move four lines, and only one of them is the construction cost line.

The contract sum moves by the value of variations and, where the risk is yours, latent condition costs. This is the movement developers model.

The contingency absorbs some of it, and then stops. A contingency is a finite provision. Once it is consumed, every further dollar comes off profit.

The programme moves, which moves holding costs and finance costs. Every week of extension of time is a week of interest on drawn debt, a week of land tax and rates, and a week of consultant and site overhead. Our guides to land holding costs and peak debt and funding exposure cover how those accumulate.

Delay costs, where the contract grants them, move the contract sum again, separately from the variation itself.

There is a fifth effect that sits outside the feasibility model. Extensions of time push out practical completion, which pushes out the occupation or compliance certificate, which pushes out settlements on presold stock. On a project with sunset dates in the contracts of sale, that is not only a cash flow question.

A worked example

A 42-apartment project, with these assumptions at contract signing:

Now run one site event and its consequences, with every other input unchanged.

Excavation exposes uncontrolled fill that was not identified in the geotechnical report. The contract puts latent conditions with the principal. Remediation and redesign of the footing system are instructed as a variation valued at $680,000. The work takes six weeks, for which the superintendent grants a six-week extension of time carrying delay costs at the rate stated in the annexure of $18,000 per week, a further $108,000. Separately, two documentation gaps in the facade package are instructed as variations totalling $310,000, with no extension of time.

Claims against the contingency total $1,098,000, against a provision of $1,100,000. The contingency holds, with $2,000 left.

The six-week extension does not stop there. Interest continues to accrue on the drawn facility and the site keeps running, adding $195,000 in finance costs and $40,000 in land holding costs. Neither sits inside the construction contingency.

Then a third variation arrives in month eleven, for $260,000 of services coordination work. The contingency has $2,000 left, so $258,000 of it falls straight through to profit.

The arithmetic is unremarkable. What it shows is where the damage actually accrued. The contingency did its job on the construction cost and absorbed $1,098,000 without complaint. The 1.7 percentage points of margin that disappeared came from the $235,000 of time-related cost that nobody had provided for, and from the variation that arrived after the contingency was spent. Our guide to development margin covers how that measure behaves, and the development cashflow modelling guide covers how to phase the timing effect rather than treat it as a single lump.

Which pre-contract decisions move this risk?

All of the ones that matter, which is the uncomfortable part, because they are made when the site is quiet and the claim is hypothetical.

The levers, none of which is free:

Documentation completeness. Every gap is a future variation priced without competition. The saving from compressing the design programme is usually smaller than the cost of the variations it generates, though neither figure is knowable in advance.

The latent conditions allocation. Moving it to the contractor raises the tender price and narrows the distribution of outcomes. Keeping it lowers the price and widens the distribution. Which you want depends on how much variance your equity and your facility can tolerate, not on which is cheaper.

The schedule of rates. Detail here converts future negotiations into arithmetic.

Provisional sums. Each one is a number you have not yet agreed. Reducing them before contract means resolving the underlying design, which costs time.

The site information you provide. More information generally narrows what can later be claimed as unanticipated. What to provide, and how, is a legal question given the misleading conduct exposure.

The notice regime. Shorter and stricter is not automatically better, for the prevention reasons above, and in Victoria and Western Australia is now statutorily testable.

Who administers the contract, and how independently. The superintendent assesses extension of time claims and values variations. If that person is your employee, or a consultant taking instructions from you on claims, the impartiality question is sharper, and Peninsula Balmain is the reason it is not merely theoretical.

The relationship between these choices and the price you are quoted is the thing to keep in view. Every risk you push onto the builder comes back as a number in the tender. Our guide to choosing a builder covers how to read a tender field where the prices reflect different risk positions rather than different efficiencies.

Does this work differently on a domestic building contract?

Yes, and the differences are statutory rather than contractual, so they cannot be drafted around.

Domestic building work is separately regulated in each state and territory, and the legislation commonly prescribes how variations are to be documented and priced, imposes written-notice requirements before variation work starts, and constrains what a builder may recover for a variation that was not properly documented. Most domestic building contracts are also excluded from the security of payment regimes, which changes the enforcement route entirely: a builder’s claim on a domestic contract generally goes to the relevant tribunal rather than to an adjudicator.

Consumer Affairs Victoria’s guidance on changing a domestic building contract price sets out the Victorian position on variation documentation. The Building and Plumbing Commission confirms that the Victorian security of payment regime excludes “most domestic building contracts”, which is why the time bar and adjudication changes discussed above may not reach a domestic contract at all.

The category matters to developers more often than they expect. Small infill projects, townhouse developments and dual occupancies can fall within the domestic building definition in some jurisdictions depending on the number of dwellings and who holds the land, and the definitions differ between states. Whether your project is a domestic building contract or a commercial construction contract is a threshold question with consequences for every mechanism in this guide, and it is one to settle with the lawyer before the contract is drafted rather than after the first variation.

How does this work in New Zealand?

The mechanisms are the same and the standard form that carries them was rewritten recently.

NZS 3910:2023 is the current Standards New Zealand conditions of contract for building and civil engineering construction, and Standards New Zealand describes an overarching objective of the revision in its reference guide as being “to lessen the need to add special conditions of contract”. The most consequential structural change for a principal is the separation of what was a single engineer role into a contract administrator, who acts for and on behalf of the principal and issues instructions including on variations, and an independent certifier, who acts impartially on decisions entrusted to that role. A New Zealand developer needs to budget for both appointments and decide who fills each, and the split changes who assesses what.

The Construction Contracts Act 2002 provides the New Zealand payment and adjudication regime, and the Ministry of Business, Innovation and Employment’s guidance on the Act is the place to start on how a disputed variation moves toward an adjudicator. Building Performance’s material on contracts for your building project covers the residential requirements.

New Zealand has no equivalent of the Western Australian and Victorian statutory unfair time bar provisions, so a New Zealand notice regime stands or falls on general contract principles.

What to ask your construction lawyer

• Under this contract as amended, which causes give the contractor an extension of time only, and which also give delay costs? Are the delay costs a stated rate, actual cost, or something else, and are they capped?
• What is the weather allowance in the annexure, and what does the site’s rainfall record imply about how often it will be exceeded?
• Does the superintendent have power to extend the date for practical completion unilaterally, whether or not a claim has been made? If not, what is our exposure to time going at large?
• How does this contract deal with concurrent delay, and has the standard apportionment provision been amended?
• Given the Victorian changes from 15 April 2026 and section 16 of the Western Australian Act, is our notice regime in this jurisdiction likely to be enforceable as drafted, and would a shorter or longer period be more defensible?
• If the project is in Victoria, does the retrospective operation of the April 2026 amendments change the position under contracts we have already signed?
• How does this contract define a latent condition, and is it measured against what a competent contractor could anticipate or against the information we provided?
• What is our exposure under Australian Consumer Law and the misleading or deceptive conduct provisions for the site information we intend to issue at tender, and what should we disclose or withhold?
• What is the valuation hierarchy for variations here, and in what circumstances can the superintendent direct daywork?
• Can the contractor be directed to proceed with a variation before the price is agreed, and what protects us if the eventual valuation is far above our expectation?
• Is this project a domestic building contract in this jurisdiction, and if so which statutory variation and notice requirements apply?
• What are our obligations if the contractor gives notice of a delay caused by our own consultants, and what should our response look like?

What to ask your superintendent or contract administrator

• What records will you keep of delay events, and will they be independent of the contractor’s records?
• How will you assess an extension of time claim where causation is contested, and what will you require the contractor to produce?
• What is your process when a claim arrives out of time but appears substantively justified?
• Will the programme be formally baselined, and how often will updates be required and retained?
• How will you distinguish between resolving design documentation and changing scope when an instruction is issued?
• What will you do if the contractor proceeds with work it says is a variation and we say is not?

What to ask your quantity surveyor

• What contingency does this contract’s risk allocation justify, and how would that change if latent conditions moved to the contractor?
• How much of the contract sum sits in provisional sums and prime cost items, and what is the realistic range on each?
• Is the schedule of rates detailed enough to price the variations this project is likely to generate?
• What does a week of programme extension cost us in finance and holding costs, and is that provided for anywhere?
• How do the tender prices differ once the different risk positions in each tender are normalised?

The short version

An extension of time moves the date and nothing else unless the contract also grants delay costs, and the two are separate questions that developers routinely merge. A variation is anything outside the documents the contractor priced, which makes documentation completeness the largest single lever on variation exposure. A latent condition is measured against what could reasonably have been anticipated, and the information you provide at tender shapes that benchmark more than any disclaimer does.

All three run on notice, which is why the recent statutory changes matter: in Western Australia under section 16 of the 2021 Act, and in Victoria from 15 April 2026 with retrospective effect, a notice-based time bar can be declared unfair where compliance was not reasonably possible or would be unreasonably onerous. A strict notice regime is a less reliable defence than it was, and it never was a free one, because a regime that leaves no route to extend time for your own delays is the structure the prevention principle is aimed at.

The feasibility consequence is the one to hold on to. Contingency protects the construction cost line. It does not protect the finance and holding costs that a granted extension of time creates, and those are usually the ones that were never modelled.