Short answer
Building costs in the ACT are driven mainly by three things: the block itself, the complexity of the design, and the level of finishes you choose. Site conditions such as slope, ground conditions and access can move the figure significantly before a single wall goes up. Approvals, engineering, demolition and external works are the costs most often left out of an early budget.
Site conditions
The cost of building on a sloping block is higher than on a flat one. A steep or irregular site may require additional engineering, deeper footings, retaining walls, and more complex concrete work. Before a detailed quote can be prepared, a site assessment is usually needed to understand the ground conditions and what the structure will require.
Access can also affect cost. If a site is narrow, has limited vehicle access, or is close to neighbouring structures, this affects how efficiently trades can work and how materials can be delivered.
Design complexity
A straightforward single storey home with a simple roof form will generally cost less per square metre than a multi-level home with complex rooflines, large cantilevers, or extensive glazing. This is not a reason to avoid good design. It is just a factor worth understanding when evaluating what a design will realistically cost to build.
Floor area is an important driver of cost, but it is not the only one. A smaller, well specified home can cost more than a larger but simpler one.
Finishes and inclusions
The selections you make for flooring, joinery, benchtops, tapware, appliances, tiles and external materials all have a direct bearing on cost. It is worth being realistic about your priorities early in the process, rather than discovering late that your preferred finishes significantly exceed the original budget.
Approvals and engineering
Development approval fees, engineering reports, energy assessments, soil tests and survey costs all form part of the overall project budget. These are not negotiable costs. They are required as part of the building process, but they are sometimes overlooked in early budget estimates.
Demolition and site preparation
For knockdown rebuild projects, demolition, asbestos testing and removal (where applicable), connection and disconnection of services, and site clearing all need to be budgeted. These costs vary depending on the size of the existing structure and site conditions.
Landscaping and external works
Driveways, paths, fencing, turf, plants, retaining walls and other external works are often excluded from a building contract and need to be budgeted separately. This is a common source of budget surprise at the end of a project.
The value of a clear contract
One of the most useful things a homeowner can do is work with a builder who provides a clear, detailed contract with transparent inclusions and a well specified allowance schedule. Vague contracts with low provisional sums are a common source of cost blowouts.
Cost and builder choice go hand in hand. Our guide on choosing the right builder for your Canberra project covers what to look for in a contract and a quote, and you can view completed Ottimo Homes projects to see the standard we build to. If you are planning a new home in the ACT, the custom home builder page sets out how Ottimo Homes approaches pricing and contract transparency.
For a current builder's view of material inflation, supplier competition and the effect on a complete home, read our guide to Canberra building costs in 2026.
Planning a project in Canberra? Start a conversation with Ottimo Homes.
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