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Price rises and variations in modular contracts
| NSW deposit cap | 10% of contract price[1] |
|---|---|
| NSW variations | In writing, signed, with the price effect shown as a calculation[1] |
| VIC escalation clause | Not permitted unless contract price exceeds A$500,000; none approved[2] |
| VIC small-change exemption | No Variation Notice if under 2% of price and no delay or permit change[3] |
| QLD price warning | Contract price and price change warning on first page of a Level 2 contract[4] |
| *Thresholds and rules change. Confirm the current position with the state regulator before signing. | |
In Victoria, Queensland and NSW, state law limits when the price of a home building contract can rise after signing. Victoria prohibits cost escalation clauses unless the contract price exceeds A$500,000, and Consumer Affairs Victoria states none has yet been approved;[2] Queensland requires any price change provision to be flagged on the first page of the contract;[4] and NSW requires variations to be written, signed and priced as a calculation.[1] Modular contracts follow these same state laws — the difference is that in a factory build, the point after which changes become expensive arrives much earlier.
A modular buyer faces the same two cost risks as anyone signing a building contract: the price rising for reasons outside the buyer's control, and the price rising because the buyer changes something. What is specific to off-site construction is when those risks bite. Most design decisions have to be made before manufacture starts, and the gap between signing and manufacture can be months. This page covers the state rules on both risks, then what is different about a factory build.
Fixed price and cost escalation clauses §
A cost escalation clause (also called a rise-and-fall clause) lets a builder increase the contract price if specified costs rise. The states treat these clauses very differently.
| State | Published position on price increases | Source |
|---|---|---|
| Victoria | Escalation clause illegal unless contract price exceeds A$500,000 and the clause is approved by the Director of Consumer Affairs Victoria; no clause has yet been approved. Expected cost rises must be built into the price. | Consumer Affairs Victoria[2] |
| Queensland | In a Level 2 contract (A$20,000 and over), the contract price and a price change warning must appear on the first page. Where the price is not fixed, the method of calculation must be stated. | QBCC[4] |
| New South Wales | In a large job contract (over A$20,000), the price must be prominent on the first page, with a warning and explanation if it is subject to change. | NSW Government[1] |
Victoria has also legislated to change this. Reforms introduced in June 2025 would allow escalation clauses only for contracts of A$1 million or more, cap increases at 5 per cent, and let a consumer cancel if costs rise by more than 15 per cent or timelines blow out by more than 50 per cent.[5] Those provisions take effect only on commencement; see the Victorian update linked in the note at the top of this page.
In Queensland, an escalation clause that does not meet the requirements can fail entirely. Law-firm commentary on a 2023 District Court decision reports a clause allowing the builder to raise the price if commencement was delayed was held void: the new price was at the builder's discretion, the first-page warning did not identify the clause, and the clause was found to be an unfair contract term.[6] The Queensland regulator has separately warned owners to seek legal advice before agreeing to pay an increase on a fixed-price contract, noting that higher material and labour costs may have no contractual basis as a "variation".[7]
Cost-plus contracts §
A cost-plus contract has no fixed price: the owner pays actual costs plus a margin. Victoria permits cost-plus contracts only above A$1 million.[3] In Queensland, the regulator reports cases where cost-plus final costs were 50 to 100 per cent higher than owners expected, and notes that home warranty protection for non-completion does not cover cost-plus or construction management contracts.[4] In NSW, cost-plus progress claims must be supported by invoices, receipts or other documents.[1]
Variations §
A variation is any change to the work, the plans or the specification after the contract is signed — whether the owner asks for it or the builder proposes it.
Every state covered by published comparison requires a variation to be written, priced and agreed by the owner before the work is carried out; what happens if that is skipped differs.[8] In Victoria and NSW, a builder who does not comply generally cannot recover payment for the variation; in Queensland, Western Australia and Tasmania non-compliance is an offence but the contract stands; in South Australia it is an offence with significant penalties.[8]
The state regulators set out what a variation document must contain:
- NSW. In writing, attached to the contract and signed by both parties, with the cost implications and the effect on the overall price shown as a calculation, not just a dollar figure. If the builder caused the need for the variation, the owner does not pay for the work to fix it.[1]
- Victoria. A Variation Notice agreed in writing before work starts, giving the details and cost of the change, the new contract price and the new completion date. No notice is needed if the builder reasonably believes the change will not need a permit change, cause delay or add more than 2 per cent to the original price. If the revised cost of the work increases by A$15,625 or more, the owner must notify the building regulator within 28 days.[3]
- Queensland. Agreed variations are listed among the provisions that can change the price, which must be warned about on the first page of a Level 2 contract.[4]
Why modular changes the timing §
In a site-built house, many finishes are chosen while the frame goes up. In a factory build, selections, services layouts and structural details are settled before manufacture starts, and a change made later affects the production file, the materials order and the production line schedule.[9] Flexibility is concentrated in the design stage.[9]
The knock-on effect can be larger than the change itself. Giving evidence to a Victorian parliamentary inquiry, the managing director of a modular manufacturer said a request for a different fixture can require a bathroom to be redesigned, with consequences elsewhere, and that individual customisation is difficult for that reason.[10]
For a buyer, three practical points follow:
- Finalise selections before the factory slot. A change requested before manufacture is a drawing change; after, it may be a production change, priced accordingly.
- Ask how long the price holds. Suppliers publish price-hold periods — one kit supplier, for example, protects its supply-contract price against eligible increases for six months from signing.[11] A project that will not reach the factory, or a later delivery stage, within that period carries price risk on the remainder.
- Read the variation clause alongside the payment schedule. In a modular contract much of the price is paid before the home reaches the site. How deposits and stage payments work for off-site builds is covered in Progress payments and off-site construction, and questions to put to a builder about variation pricing are in Choosing a prefab builder.
Where industry contracts fit §
prefabAUS released a standard form contract for factory-built Class 1 homes in September 2026. It is a voluntary industry document and does not displace any state's domestic building contract law; its scope is described in prefabAUS standard form contract. Whatever contract is used, the statutory rules above continue to apply.
What is not covered here §
The rules in Western Australia, South Australia, Tasmania, the ACT and the Northern Territory on cost escalation clauses are not covered by the sources compiled here; the variation position in four of those jurisdictions is summarised above from trade media only, and the ACT and Northern Territory are not covered at all.[8] How a court or tribunal would treat a particular clause, and whether a supply-only contract for a kit or imported module is a regulated domestic building contract in a given state, are questions for legal advice. Dispute pathways are covered in Builder disputes and tribunals by state.
Nothing on this page is legal advice.
Sent to info@modularlivingaustralia.com.au and handled by a person. See Privacy.
References §
- NSW Government — Contracts for residential building work page. States work over A$5,000 including GST needs a written contract and work over A$20,000 a large job contract; the maximum deposit is 10 per cent of the contract price; a large job contract must show the contract price prominently on the first page, with a warning and explanation if the price is subject to change; variations must be in writing, attached to the contract and signed by both parties, and must show the cost implications as a calculation; a builder who caused the need for a variation cannot charge for the work to fix it; and contracts over A$20,000 carry a five clear business day cooling-off period and must include a progress payment schedule tied to work actually done. nsw.gov.au/housing-and-construction/building-or-renovating-a-home/preparing/contracts
- Consumer Affairs Victoria — Preparing a major domestic building contract (guidance for builders). States a cost escalation or rise-and-fall clause is illegal unless the contract price is more than A$500,000, that such a clause must be approved by the Director of Consumer Affairs Victoria, that the Director has not yet approved any cost escalation clauses, and that likely cost rises from inflation and wage increases must be built into the contract price. consumer.vic.gov.au/licensing-and-registration/builders-and-tradespeople/running-your-business/domestic-building-contracts/preparing-a-major-domestic-building-contract
- Consumer Affairs Victoria — Checklist for changing a major domestic building contract. States owner-requested changes must be agreed in writing using a Variation Notice before work starts, setting out the details and cost of the change, the new contract price and the new completion date; that a Variation Notice is not needed if the builder reasonably believes the change will not need a permit change, cause delay or add more than 2 per cent to the original contract price; that an owner must notify the building regulator within 28 days if the revised cost of work increases by A$15,625 or more; that a major domestic building contract is one over A$10,000; and that cost-plus contracts are permitted only above A$1 million. consumer.vic.gov.au/housing/building-and-renovating/checklists/changing-a-major-domestic-building-contract
- Queensland Building and Construction Commission (QBCC) — Contracts and agreement types page. States a contract is required for domestic building work over A$3,300, with a Level 1 contract from A$3,301 to A$19,999 and a Level 2 contract from A$20,000; that in a Level 2 contract the contract price and a price change warning must appear on the first page of the schedule; that where the price is not fixed the method of calculation, including prime cost and provisional sum allowances, must be stated; that QBCC has received reports of cost-plus final costs 50 to 100 per cent higher than owners expected; and that home warranty protection for non-completion is not available for cost-plus or construction management contracts. qbcc.qld.gov.au/rn/node/7106
- Premier of Victoria — Media release, 18 June 2025, on reforms to the Domestic Building Contracts Act 1995 introduced to Parliament that day. States cost escalation clauses would be allowed for contracts of A$1 million or more, with increases capped at 5 per cent and additional consumer protections; that deposit limits and progress payment stages would be prescribed by regulation; and that consumers could cancel a contract if timelines blow out by more than 50 per cent or costs rise by more than 15 per cent. premier.vic.gov.au/new-building-reforms-protect-consumers-and-industry
- HWL Ebsworth Lawyers — Market insight, 18 July 2023, on a District Court of Queensland decision. Describes section 14 of Schedule 1B of the Queensland Building and Construction Commission Act 1991 as requiring a warning and explanation of any cost escalation clause on the first page of a domestic building contract, and reports the court found a clause allowing the builder to raise the price if commencement was delayed void because the new price was at the builder's discretion, the warning did not identify the clause, and the clause was an unfair contract term under the Australian Consumer Law. Law-firm commentary, not an official source. hwlebsworth.com.au/is-your-cost-escalation-clause-enforceable
- Queensland Building and Construction Commission (QBCC) — Public warning, 11 March 2024, about making payments outside building contract terms. Urges owners to seek legal advice before agreeing to or paying an increase in the price of a fixed-price contract, states there may be no contractual basis to treat material and labour cost increases as variations, and notes such a demand may be a breach of contract that allows termination and a home warranty claim. qbcc.qld.gov.au/resources/public-warning/warning-about-making-payments-outside-building-contract-terms
- The Good Builder — Trade media article, 23 August 2026, comparing variation rules in six states. States residential legislation in New South Wales, Victoria, Queensland, Western Australia, South Australia and Tasmania requires a variation to be written, priced and agreed by the owner before the work is done; that in Victoria (Domestic Building Contracts Act 1995 ss 37–38) and New South Wales (Home Building Act 1989 ss 7E and 10) a builder who does not comply generally cannot recover payment for the variation; that in Queensland, Western Australia and Tasmania non-compliance is an offence but the contract is preserved; and that in South Australia non-compliance is an offence with penalties reported to have increased in January 2026. Trade media summary, not an official source. thegoodbuilder.com.au/every-state-requires-the-variation-document-before-the-work-starts-what-happens-if-you-skip-it-splits-three-ways/
- The Good Builder — Trade media article, 3 October 2026, on housing factories scaling up. States that in factory construction selections, services layouts and structural details are settled before manufacture starts, that a change in the factory affects the production file, the materials order and the production line schedule, and that flexibility is concentrated in the design stage, with less room for variation afterwards. Trade media. thegoodbuilder.com.au/housing-factories-are-scaling-up-the-real-change-starts-before-the-truck-arrives/
- Parliament of Victoria — Legislative Assembly Environment and Planning Committee — Transcript of evidence, Inquiry into the Supply of Homes in Regional Victoria, Colac, 24 February 2025. The managing director of modular manufacturer FormFlow states that modular construction requires more design work up front, that individual customisation is difficult because a request for a different fixture can require a bathroom to be redesigned with knock-on effects, and that the company moved toward developer and community housing clients partly for that reason. Evidence of a company with a commercial interest. parliament.vic.gov.au/4abbab/contentassets/e22f1a2e56ad491d8689a6a45a2bfbfe/4.-formflow---24-february-2025.pdf
- iBuild Kit Homes — Kit Homes Australia page, modified October 2026. States a kit supply-contract price is protected against eligible increases for six months from signing. Supplier-published commercial guidance. i-build.com.au/kit-homes-australia/
Figures are as published by the sources above at their respective dates and are paraphrased summaries, not verbatim reproductions. Verify current pricing and rules directly with builders, lenders and planning authorities.