Written by: David Rule, Associate Solicitor, Commercial Law (Updated: 2 November 2026)
What builders and property owners need to know about rising material costs, escalation clauses, and statutory contract rules in Queensland.
Queensland house construction prices climbed 7.8% in the year to September 2026 (ABS, Producer Price Indexes, released 30 October 2026). When construction costs surge midway through a project, builders face eroded margins while owners face unexpected demands for extra funds. Under Queensland law, can a builder increase a fixed price contract in Queensland simply because supply costs have spiked?
Cost pressure alone provides no legal entitlement to lift a contract price. In August 2026, the Queensland Building and Construction Commission (QBCC) confirmed it is actively monitoring fixed-price exposure and contract repricing across the Sunshine Coast and broader Queensland.
When Can a Builder Increase the Price of a Signed Contract?
Under a fixed price building contract in Queensland, your builder generally carries the risk of rising labour and material costs. A builder cannot unilaterally increase the contract price simply because their trade expenses have risen.
For most domestic building contracts, strict statutory requirements apply. Any clause permitting a price increase must display an explicit warning and a brief explanation prominently on the first page of the contract schedule.
The Queensland District Court reinforced these protections in Perera v Bold Properties (QLD) Pty Ltd [2023] QDC 99, where a clause allowing the builder to adjust the contract sum to its “current base price” was struck down. The court ruled the clause void because:
- it omitted the mandatory warning on the first page of the contract schedule;
- the adjustment mechanism was void for contractual uncertainty; and
- it breached the unfair contract terms provisions in the Australian Consumer Law.
Unless a valid, fully compliant adjustment clause exists, the builder must bear the commercial risk of price increases.
How Provisional Sums and Prime Cost Allowances Alter the Price
Provisional sums and prime cost items provide flexibility when specific materials or trades cannot be priced definitively before work begins. Builders implicitly warrant that every provisional sum allowance is calculated with reasonable care and skill.
Deliberately under-quoting these allowances to present an attractive quote exposes a builder to statutory liability. When actual trade costs exceed the stated figure, that overrun is added to your contract price alongside the builder’s agreed margin percentage.
Artificial allowances inevitably trigger avoidable payment disputes.
Our Commercial Law team recently identified this exposure when reviewing a Sunshine Coast building contract for concrete pool construction. The contract relied on provisional allowances for critical site preparation, leaving the owner exposed to significant price increases across two areas:
- Subsurface rock and unpredictable ground conditions during deep excavation
- Additional piering and footings required after severe wet weather
Because ground conditions cannot be safely estimated using a flat percentage contingency, you should obtain an independent cost assessment from a quantity surveyor or building certifier prior to signing. Verifying these allowances before executing the contract helps protect your capital against unanticipated budget blowouts.
Strict Rules for Building Contract Variations in Queensland
Building contract variations cannot simply be approved verbally on site. A builder must document the variation in writing and secure agreement before any additional work begins.
The statutory rules require you to provide a copy to the owner before work commences, or within 5 business days of agreement, whichever is earlier.
The variation document must clearly detail:
- The full scope of the additional work;
- The cost of the variation or how it will be calculated; and
- Any delay or effect on the project completion date.
Ignoring these statutory steps can be fatal to your recovery. In MA & SK Jokovich Pty Ltd v Garland [2025] QCAT 191, a builder claimed roughly $85,000 in variations and prime cost items but was denied recovery because the changes were never properly documented.
For trade contractors, proceeding on informal site chats or an unexecuted quote strips away your contractual right to claim cost increases.
An undocumented variation leaves you in the weakest possible position during a payment dispute.
How to Handle Project Delays and Disputed Payment Claims
Failures in Queensland construction disputes frequently involve the absence or deficiency of written records. When material shortages or variations disrupt the project timeline, you must preserve contemporaneous evidence to support any adjustment:
- Daily site diary entries detailing idle labour or equipment;
- Formal delay notices served strictly within the contract’s required notification window; and
- Written extension of time (EOT) claims that clearly calculate the project impact.
Missing a strict notice deadline can extinguish your contractual right to extra time or delay costs.
If you dispute an unagreed price adjustment on a progress claim, do not stop work or withhold the entire sum without an express contractual or statutory right. Suspending works unlawfully may constitute contract repudiation. State your objections in writing immediately and ensure you pay the undisputed balance by the due date.
While Schedule 1B of the Queensland Building and Construction Commission Act 1991 (Qld) regulates domestic contracts, commercial arrangements turn on their express terms and statutory regimes. For commercial disputes, contractors and principals enforce payment through statutory adjudication under the Building Industry Fairness (Security of Payment) Act 2017 (Qld).
Strict statutory timeframes apply as soon as a commercial payment claim is served.
A Five-Point Checklist to Protect Your Cash Flow
Unforeseen cost spikes can significantly impact project viability. Applying a disciplined pre-dispute checklist protects your cash flow before disagreements derail the job.
- Price risk into initial terms: Set firm quote validity periods, negotiate realistic allowances for provisional sums, and define exact criteria for qualifying delays.
- Secure independent verification: Engage a quantity surveyor or commercial lawyer to inspect cost escalation clauses and adjustment mechanisms before executing the contract.
- Maintain daily contemporaneous records: Keep strict site diaries, log adverse weather conditions, and issue time-stamped written notices as soon as site events occur.
- Enforce strict variation compliance: Never execute or permit changed work without a signed variation that clearly details the agreed price and schedule adjustments.
- Isolate disputed amounts early: If a payment dispute arises on site, pay uncontested progress claims promptly while referring the contested balance to formal dispute mechanisms.
Disciplined financial administration prevents contested claims from compounding. Forecasting cash flow stage-by-stage across the project lifecycle ensures you identify cost pressures and manage commercial risk before project viability is compromised.
Key Takeaways
Rising building costs in Queensland do not grant an automatic right to renegotiate a fixed price contract. Cost adjustments depend strictly on objective escalation terms, compliant provisional sum reconciliations, or written variations executed prior to work commencing. Whether managing a commercial build or residential project, adhering to statutory notice requirements and maintaining precise project records will determine whether an increased price is legally enforceable or entirely unenforceable.
Sources
- Schedule 1B, section 14 of the Queensland Building and Construction Commission Act 1991 (Qld)
- Schedule 1B, section 26 of the Queensland Building and Construction Commission Act 1991 (Qld)
- Schedule 1B, section 40 of the Queensland Building and Construction Commission Act 1991 (Qld)
- Building Industry Fairness (Security of Payment) Act 2017 (Qld)
- Schedule 2, section 23 of the Competition and Consumer Act 2010 (Cth)
Disclaimer: This article provides general information only and does not constitute legal advice. It does not take into account your personal circumstances and should not be relied on as a substitute for professional legal advice. Commercial matters require advice tailored to your specific business circumstances. For advice about your specific situation, please contact Greenhalgh Pickard on (07) 5444 1022.
Greenhalgh Pickard’s Commercial Law Team
