A fixed-price building contract is one of the most reassuring documents a homeowner can sign, but the word “fixed” does a lot of heavy lifting. Knowing exactly what sits inside the price, and what can still move, is the difference between a smooth build and a stressful one.
What a fixed-price contract actually means in Victoria
In Victoria, most new homes are built under a major domestic building contract, and for projects over $10,000 that contract is regulated under the Domestic Building Contracts Act 1995. A “fixed-price” (sometimes called lump-sum) contract sets a single agreed figure for the works described in the plans, specifications and inclusions list.
It is important to understand that the price is fixed against a defined scope, not against your imagination. If the scope is clearly documented, your builder carries the risk of ordinary cost movements in labour and materials. Change the scope, and the price changes with it.
What’s typically included in the contract price
A well-prepared contract from a registered builder should leave very little to guesswork. As a general guide, the fixed price usually covers the following.
- The full build described in the working drawings and engineering plans.
- Structural elements: footings, framing, roofing, brickwork or cladding.
- A written schedule of inclusions covering fixtures, fittings and finishes.
- Domestic building insurance (builders warranty insurance) where the contract value requires it.
- Site supervision, project management and the builder’s margin.
- Compliance with the National Construction Code and a 7-star NatHERS energy rating.
The inclusions schedule is the heart of the document. Vague entries such as “quality tiles” invite disputes later, whereas a specific brand, model and allowance leaves no room for confusion.
Provisional sums and prime cost items
Even a fixed-price contract contains a few flexible line items, and this surprises many first-time builders. Two terms are worth learning before you sign.
Prime cost (PC) items
A PC item is an allowance for a product you haven’t finally selected, such as tapware, a kitchen sink or floor tiles. The contract carries an estimated amount; if your final choice costs more or less, the price is adjusted accordingly.
Provisional sums (PS)
A provisional sum is an estimate for work that can’t be precisely priced yet, often site works like rock excavation or complex drainage. On the sloping blocks common around Arthurs Seat, McCrae and the hills behind Dromana, provisional sums for site cut, retaining and footings are worth scrutinising closely.
Neither of these makes a contract dishonest. They are a normal and legal part of Victorian contracts, but a good builder keeps them realistic rather than artificially low to win the job.
What often sits outside the fixed price
Exclusions are just as important as inclusions. Common items that may not be in the base price include the following.
- Council and authority fees, planning permits and building permits.
- Connection of services: water, sewer, power, gas and NBN.
- Landscaping, driveways, fencing, decking and letterboxes.
- Bushfire (BAL) upgrades where a block carries a higher rating.
- Coastal detailing for salt air and coastal winds, such as marine-grade fixings near Safety Beach or Rye.
None of these are hidden traps when they’re disclosed up front. Ask your builder to walk you through the exclusions list line by line so there are no gaps between the contract and your budget.
Site-specific realities on the Mornington Peninsula
Local conditions shape what a fair fixed price looks like. A flat, serviced block in central Rosebud is a very different proposition from a battle-axe lot on a steep grade with reactive clay soil.
A soil report and contour survey should inform the price before you sign, not after. Where these aren’t available, expect provisional sums to carry more of the site-works risk, and factor that into your comparisons between quotes. A local builder who knows the Mornington Peninsula Shire planning process and the region’s soil and wind conditions can price the site far more accurately than someone working from a metro template.
Checks before you sign
Before committing, confirm the builder is registered with the Victorian Building Authority and holds current registration for domestic building work. Verify that the contract price matches the plans and inclusions exactly, and that domestic building insurance will be provided before you pay the deposit.
Deposits are capped by law: for most contracts the maximum deposit is 5 per cent (or 10 per cent for contracts under $20,000). Read the progress payment schedule, the variation clause and the cooling-off provisions carefully, and never feel rushed into signing on the spot.
At DARC Building Group, a Dromana-based builder, the aim is a contract that reads clearly enough that you understand every figure in it. You can see how the paperwork fits the build on our our process page, and the range of work covered under services.
Fixed price versus cost plus
Some builders offer “cost plus” contracts, where you pay the actual cost of works plus a margin. These can suit highly custom or uncertain projects, but they shift budget risk onto you. For most people building a family home, a properly documented fixed-price contract offers far more certainty and easier finance approval.
A fixed-price contract is only as strong as the detail behind it, so take your time reading it and ask questions freely. If you’re weighing up building a home in Dromana and want a contract explained plainly, get in touch for a straightforward conversation about scope, inclusions and price.
Frequently Asked Questions
Can the price in a fixed-price building contract still change?
Yes, in specific circumstances. The fixed price only covers the scope described in the plans and inclusions, so approved variations you request will change it. Prime cost items and provisional sums can also be adjusted up or down once final selections are made or actual site costs are known. A clearly documented contract keeps these movements to a minimum.
What are provisional sums in a Victorian building contract?
A provisional sum is an allowance for work that cannot be precisely priced when the contract is signed, such as rock excavation or retaining on a sloping block. If the real cost differs from the estimate, the price is adjusted accordingly. On hilly or reactive-soil sites around Dromana and Arthurs Seat, it is worth checking that these allowances are realistic rather than optimistically low.
Is domestic building insurance included in the contract price?
For most domestic building contracts above the legislated threshold, the builder must take out domestic building insurance (builders warranty insurance) before receiving a deposit, and the cost is usually built into the price. This insurance protects you if the builder dies, disappears or becomes insolvent. Always confirm the certificate is provided before you pay anything.
What is usually excluded from a fixed-price contract?
Common exclusions include council and permit fees, service connections, landscaping, driveways, fencing and sometimes bushfire (BAL) or coastal upgrades. These are not hidden costs when the builder discloses them clearly in the exclusions list. Ask for a line-by-line explanation so you can allow for them in your overall budget.