Budgets
& Costs
Construction costs are the most commonly misunderstood number in a project. Rates from the internet, from friends, or from the builder's website are almost always wrong for your specific project. Here is how to think about cost — and how to plan for reality.
These rates are order-of-magnitude guides for preliminary budgeting only — not quotations. Actual costs depend on site conditions, specification, programme, and market conditions at time of tender.
Brick veneer or lightweight construction. Standard fixtures and finishes.
Custom joinery, high-end fixtures, complex geometry, exposed structure.
Extension to existing dwelling, standard specification. Excludes demolition and make-good.
Works to heritage-listed buildings. Specialist trades, lime mortar, heritage joinery, additional documentation.
Apartments or townhouses, 3+ dwellings. Fire and acoustic compliance drives cost.
Public-use buildings. Higher durability specification, DDA compliance, complex services.
Commercial tenancy fitout. Base building services assumed complete.
Shopfront and retail interior. Highly variable with brand and fit-out tier.
All rates ex-GST. Current as at 2025. Market conditions can shift these ranges by ±20% depending on tender climate and regional factors.
At feasibility, you have a site and a rough brief. The cost estimate at this stage is based on project type and approximate area — the benchmark rates above. Accuracy is ±30–40%.
The purpose of this estimate is not precision — it is feasibility. Can the project type you want fit the budget you have? If not, what has to change — brief, specification, or expectations?
Do not use this estimate to decide whether to proceed. Use it to decide whether to invest in the next stage of design.
At developed design, the project is defined — areas are confirmed, structural approach is resolved, and specifications are set at a category level. Cost accuracy improves to ±15–20%.
This is the critical budget checkpoint. If the project is over budget, the options are: reduce scope, reduce specification, stage the works, or adjust the budget. Making these decisions here — before documentation — is far less expensive than discovering them at tender.
Engaging a quantity surveyor at this stage for an independent estimate is strongly recommended for projects over $1M.
Once construction documentation is substantially complete, a pre-tender estimate can be prepared against the actual drawings and specifications. Accuracy at this point should be within ±10%.
This estimate allows you to calibrate expectations before tenders are received. If the pre-tender estimate is above budget, there is still time to make targeted specification adjustments before builders price the work.
The contract sum is the price the builder has agreed to construct the project for, subject to the contract conditions. This is the first fixed cost number in the project — everything before it was an estimate.
The contract sum does not include provisional sums (items priced at an allowance pending selection), prime cost items (owner-supplied items), or variations. These will be reconciled during construction and at final account.
Construction contingency should still be held aside from the contract sum — latent conditions and variations are a certainty in any project of meaningful size.
budget for your
project?
We can help you build a cost model that is grounded in what your project will actually cost — before you commit to design.