Fixed Price Agreements
On receipt of your final concept drawings and engineering, we'll prepare a comprehensive quote for the project, including a detailed breakdown of all costs, inclusions and allowances.
If you'd like to proceed, we'll then prepare a fixed-price building contract for your review and signing. This provides certainty around pricing, inclusions, project scope and the construction schedule before work begins, allowing you to understand the expected build timeframe and make any alternative accommodation arrangements if required.
Upon signing the contract, a 5% deposit is payable, with the remaining balance drawn down through clearly defined progress payments as the project reaches each agreed milestone. In accordance with QBCC requirements, you will never pay more than the value of work completed on site.
Outlined below is a detailed explanation of the contract inclusions, insurance cover and other important information relating to your project, helping you move forward with confidence and a clear understanding of what is included.
For more specific project costs, including recent examples.
The Three Insurance Certificates Every Professional Builder Should Provide
QBCC Home Warranty Insurance.
QBCC Home Warranty Insurance is a mandatory statutory scheme administered by the Queensland Building and Construction Commission. The premium is included as part of your Fixed Price Agreement and paid by the builder before site start on any residential job over $3,300, with the certificate of insurance issued in the homeowner's name. The cost is tiered to the project's value.
Non-completion
If the builder dies, disappears, or becomes insolvent before practical completion, the policy pays the reasonable cost of having another licensed contractor finish the work, up to the scheme cap.
Defective work
Covers the cost of rectifying defective building work for 6 years from the date of practical completion where the original builder cannot or will not return to remedy it.
Subsidence & structural
Structural defects and subsidence are covered for 6 years and 6 months from practical completion, the longest residential cover in any Australian state.
Two further policies sit alongside QBCC cover on every Topbuild project: Contract Works Insurance protects the partially built structure, on-site materials, and damage caused by events such as storm, fire, or impact during construction; Public Liability Insurance ($20M) protects against claims arising from accidental injury to third parties or damage to property caused by our construction activities. Certificates of currency are issued with the contract and renewed annually.
Contract Works Insurance.
This is separate from QBCC Home Warranty Insurance, and it covers something that QBCC cover does not. It's a common misconception, even amongst builders, that the QBCC will cover damage to the existing structure during a renovation. It won't. QBCC cover is consumer protection against the builder; it is not property insurance over your home.
We're in a tropical state. If a storm rolls through mid-build and water gets into your existing home through a wall we've opened up or a roof we've lifted, that damage needs to be insured. Separate from QBCC Home Warranty Insurance, this insurance covers the partially built structure, on-site materials, and damage caused by events such as storm, fire, or impact during construction. It can also extend to the existing structure where it forms part of the building works. Every Topbuild project is covered before site start.
Your home and contents insurance is unlikely to cover damage during a renovation. Before any renovation begins, make sure your builder provides you with a Certificate of Currency for their Contract Works Insurance.
Public Liability Insurance.
Topbuild carries $20 million Public Liability cover on every project. This protects against claims arising from accidental injury to third parties or damage to property caused by our construction activities, including impacts to neighbouring properties. A Certificate of Currency is issued with your contract and renewed annually.
Provisional sums & prime cost items, explained.
A "fixed price" contract still carries allowances for things that genuinely cannot be priced exactly at signing, either because the product hasn't been chosen, or because the work can't be fully scoped until the ground is open. The QBCC requires these to be disclosed clearly and reconciled in writing.
Prime Cost (PC) items
A PC item is an allowance for a product not yet selected, typically tapware, tiles, appliances, door hardware, light fittings. The contract names the item and the dollar allowance. Once you select the actual product, the difference is reconciled: under-spend is credited, over-spend is added to the contract sum with the disclosed builder's margin.
Example: $2,000 PC for a kitchen mixer. You select a $2,800 mixer. The $800 difference (plus margin) is added by written variation before order.
Provisional Sums (PS)
A PS is an allowance for work that can't be fully scoped at contract signing, for example rock excavation, contaminated fill removal, undocumented services, or a landscape package still in design. The estimate is made in good faith based on available information. Actuals are reconciled against supplier invoices and trade quotes once the scope is known.
We mitigate PS exposure upfront with soil tests, service locates and intrusive investigations during preconstruction so they're the exception, not the rule.
The legitimate ways a fixed price changes.
A fixed price isn't a guess, it's a commitment. But the QBCC contract defines specific events where the sum or programme can legitimately move. Every one of them must be in writing, signed, and priced before work proceeds.
Variations
Any change to scope, specification or drawings after contract signing, initiated by you, the designer, the certifier, or required by site conditions. Under QBCC rules every variation must be in writing, signed by both parties, and priced before work proceeds. We issue variations on a single-page form showing scope, cost (including the disclosed margin) and any time impact. No verbal instructions are actioned.
Variation example: client requests bathroom tiling be changed from skirting height to full height or to add an additional window etc.
Disclosed builder's margin: the margin we apply to variations and PC/PS reconciliations is fixed in the contract and disclosed before signing. There is no hidden uplift on changes, and no margin on credits back to you when an allowance comes in under.
Extensions of time (EOT)
The builder is entitled to an EOT for delays outside our control, inclement weather, council/certifier turnaround, client-directed variations, late selections, supplier failure, or industrial action. Each EOT is notified in writing within 10 business days of the delay event with supporting evidence (BOM rainfall data, RFI logs, supplier letters). Builder-caused delays do not attract an EOT. To avoid delays as best possible, in the initial construction schedule we always allow for some weather delays, such as, extended rainfall that prevents exterior painting etc.
Latent conditions
A latent condition is something the contract assumed wasn't there but is — typically rock under the slab line, asbestos in a wall cavity, contaminated fill, undocumented services, or an old footing. These are excluded from the fixed price (you can't price what you can't see) and handled as a written variation once the condition is exposed and quoted.
Latent condition example: stormwater not connected, leaking underground, unknown until excavation works are underway.
The rest of the contract, in plain English.
The clauses most clients never have walked through, but the ones that quietly govern how the build runs day-to-day and how risk is shared.
Practical Completion
Practical completion (PC) is the contractually defined moment the home is reasonably fit to occupy, all works complete except minor defects that don't prevent use. PC triggers handover of keys, the start of the 12-month defects liability period, the final progress claim, and the start of the statutory QBCC warranty clock. A joint inspection produces the defects list signed by both parties.
Site access & possession
On the site-start date the owner gives the builder exclusive possession of the construction zone for the duration of the works (with the exception of minor works where the owner continues to live in the home during renovations). Owner visits are welcomed and scheduled for safety reasons , under WHS law the builder is the Person Conducting a Business or Undertaking (PCBU) and is responsible for everyone on site.
Working hours & site conduct
Our standard working hours are 6:30am–3:30pm Monday to Friday, however on occasion we may be required to extend this till 5:30pm and 7:00am–3:30pm Saturday, this is in line with the Brisbane City Council Local Law for noisy works. No Sunday or public holiday work without written approval. Site amenities, fencing, signage and waste management are all builder-supplied.
Statutory warranties
Beyond the contract, the QBCC Act implies non-excludable warranties into every residential building contract: work performed in an appropriate and skilful way, materials good and suitable for purpose, work in accordance with all laws, calculations performed with reasonable care and skill, and completion within the stated time. These run with the land, they survive a sale of the property within their warranty period.
Dispute resolution
The contract sets a tiered process: first, written notice and a 10-business- day good-faith negotiation between the parties. Unresolved matters can then be referred, free of charge, to the QBCC's Early Dispute Resolution service. Beyond that, payment disputes can be adjudicated under the BIF Act (a fast statutory process), and broader disputes go to QCAT or the courts.
Confidentiality & privacy
Project drawings, financial information and personal details shared during the build are treated as confidential. We won't publish photographs of your completed home, name you as a client, or share your address without written permission, even after handover.
Assignment & novation
Neither party can assign the contract to a third party without the other's written consent. If the property sells mid-build (rare, but it happens), the contract can be novated to the new owner so the build continues seamlessly under the same terms.
Governing law
The contract is governed by the laws of Queensland and read together with the QBCC Act, the Domestic Building Contracts schedule, and the BIF Act. Where the contract and statute conflict, statute prevails, consumer protections cannot be contracted out of.
What does a builder's margin cover?
- Extensive Work Health and Safety (WHS) management systems, including specialist compliance software, site-specific safety planning, inductions and daily compliance documentation.
- Public liability, construction works and workers compensation insurance.
- Ongoing investment in specialised tools, equipment and builders' trailers, all requiring regular safety inspections, maintenance and frequent replacement.
- Project management responsibilities undertaken before construction begins and continuing throughout the project, often outside of onsite hours. This includes planning, scheduling, coordinating trades, resolving issues and managing decisions — extending well beyond the time spent physically onsite.
- Administration and bookkeeping staff required to assist with the significant volume of purchasing, invoices, payments, scheduling and project documentation involved in coordinating multiple trades and suppliers throughout the project.
- Specialist accounting costs for the preparation and submission of annual QBCC MFR reporting, which is mandatory and separate from standard tax compliance.
- QBCC licensing, Master Builders membership, ongoing compliance costs and general business overheads, including tax compliance, vehicles and other operational expenses required to run a professional building business.
Master Builders Queensland Level 2, fixed-price residential building contract.
QBCC-compliant, with full statutory cooling-off, capped deposits and the QBCC Pocket Guide provided before signing. Full licensing details on the QBCC page.