Buyer's guide / Off the plan vs building
Off the plan vs building or renovating: why a fixed price matters.
When you buy off the plan, your price is fixed when you sign the contract. When you build or renovate, it often isn't. Here is what that means, what is still not fixed, and what the official sources say.
Published by Off Plan Properties. When you are ready to decide, our property team, including licensed real estate agent Breige Quinn, is a call away.
01 Building costs
Building costs keep rising.
House construction prices rose 5.9% across Australia in the year to June 2026, and 8.0% in Queensland. In New South Wales they rose 4.8%. The June quarter alone was up 2.0% nationally and 3.1% in Queensland (ABS, Producer Price Indexes, Australia, June quarter 2026, released 31 July 2026).
These are producer price indexes: what the ABS measures builders receiving for house construction. They are not a quote for any particular home.
02 What is fixed
Off the plan, your price is set when you sign.
An off-the-plan contract names the price you will pay at settlement. A deposit goes down now and the balance is due at completion, so rising building costs between signing and completion are not added to your price unless the contract allows it. Check the contract for any price adjustment clause, and have your solicitor review it before you sign.
03 What is not fixed
The price is fixed. The value is not.
This is the part that is easy to skip. The price you pay is locked in, but what the property is worth when it is finished can be higher or lower. The bank values the property before it lends, and buyers come unstuck when the valuation comes in below the contract price. Settlement can also be later than expected, and the plans and finishes can change within what the contract allows.
That is why we look at what similar new and resale properties nearby are selling for before you commit. Our buyer's guide covers what a developer can change and what you can do about it, with sources, and the contract clauses guide lists the 12 clauses to check before you sign.
04 Building and renovating
What the Queensland regulator says about building.
The QBCC says these "carry heightened risks for homeowners because of the lack of certainty regarding the final cost", and that final costs are "often considerably more than the homeowners anticipated". Assistance for non-completion under the Home Warranty Scheme is not available when a cost-plus or construction management contract is used (QBCC, updated 10 March 2024).
The QBCC warned in March 2024 that some contractors were asking owners for extra money for higher material and labour costs, and that under a fixed price contract there may be no contractual basis to demand it (QBCC, 11 March 2024). A fixed-price building contract helps, but you may still have to deal with these requests.
The Queensland Home Warranty Scheme covers incomplete work, defective work and subsidence, up to $200,000 for incomplete work, with up to $300,000 in total with optional additional cover. For a non-completion claim the contract must end within 2 years of work starting, and you must lodge the claim within 3 months of the contract ending (QBCC, 6 October 2026).
This section covers Queensland only. Building rules in New South Wales are different; check NSW Fair Trading before comparing.
05 How to compare
Compare the same things, in writing.
Off the plan
- Contract price and deposit terms
- Any price adjustment clause
- Sunset date and what happens if it passes
- What the developer can change
- The likely valuation at settlement
Build or renovate
- Fixed-price or cost-plus contract
- How variations are priced
- The builder's licence and insurance
- Council approvals and timing
- Your own contingency for cost rises
Prefer an established home to building or buying new? Here is how to buy on the southern Gold Coast before a home is listed.
Neither option is risk-free. Always have your solicitor or conveyancer review the contract before you sign.
Sources