What does it cost per square metre to build a house in NSW?

As at late 2025, quantity surveying guides put standard project homes at roughly $1,600 to $2,700 per square metre and custom homes at $2,700 to $3,900 or more, GST exclusive and assuming a straightforward site. A builder active on the Central Coast publishes an indicative $2,100 to $2,600 per square metre for knockdown rebuilds. Sloping, rocky or bushfire prone sites sit above these ranges.

Why do project home base prices grow so much by handover?

Because base prices generally exclude site costs, and often driveways, flooring, landscaping and upgrades needed for your specific block, like retaining, piering or bushfire construction. Site preparation alone commonly runs $10,000 to $70,000 or more. Consumer guides suggest allowing 20 to 30 per cent above an advertised base price.

How much should I hold as a contingency when building?

Quantity surveyors commonly recommend 10 to 15 per cent of the build cost as a contingency, more on complicated or sloping sites. If the budget cannot absorb that buffer, the project scope needs to change before contracts are signed, not after.

How Much Does It Cost to Build on the Central Coast?

Shea CullenNSW Registered Architect 9748 · Updated 10 July 2026

Cost is the question I am asked most, and the one the industry answers worst, because almost everyone publishing numbers is selling a build. I am not a builder, so here are the real figures with their sources and dates attached, the costs the glossy numbers leave out, and the Central Coast specifics that move the total. Where a figure is my own observation from projects rather than a published source, I say so.

One rule before any numbers: all per square metre figures are rubbery. They vary with what is counted (garages? decks? site costs?) and they age quickly. Use them to set expectations and compare like with like, never as a quote.

The headline ranges, with sources

Standard project homes: roughly $1,600 to $2,700 per m², and custom or luxury homes $2,700 to $3,900+ per m², per the quantity surveying firm Duo Tax (September 2025). Those figures are GST exclusive and, in their own words, assume a straightforward site with no major earthworks, retaining or bushfire compliance. That caveat is doing a lot of work on the Central Coast, as we will get to.
Sydney region residential: Rider Levett Bucknall's 2025 figures, as republished by a volume builder, span roughly $2,500 to $7,600 per m², with the top of the range being full custom work. Treat the upper numbers as Sydney custom pricing, not a Coast baseline.
Central Coast specifically: Montgomery Homes, a volume builder active on the Coast and in Newcastle, published (March 2026) an indicative $2,100 to $2,600 per m² for knockdown rebuild projects, with total project ranges of $580,000 to over $1 million.
The statewide average: analysis of ABS approvals data for 2024-25 put the average cost of building a new house in NSW at about $558,000. Averages hide everything interesting, but it is a useful sanity check against advertised prices that sound too good.

Why the advertised base price is not your price

A project home base price buys the house from the catalogue, standing on a perfect imaginary block. Your block is real, so the difference gets added back later. The usual gaps:

Site costs. Earthworks, piering, retaining, connections. Montgomery Homes' own published guidance puts site preparation at $10,000 to $70,000 or more depending on slope, access and soil. On a knockdown rebuild, demolition adds roughly $20,000 to $55,000.
The liveability items. Depending on the builder: driveways, flooring, window coverings, landscaping, fencing, sometimes even paint upgrades. "Turnkey" packages exist precisely because base prices are not turnkey. Consumer cost guides commonly suggest allowing 20 to 30 per cent above the base price for a realistic move-in figure.
Compliance for your specific block. BASIX and the 7 star energy standard (the NSW Government's own 2023 estimate was about $7,150 added to an average new house, against roughly $1,070 a year in energy savings), plus whatever your site's overlays require.

None of this makes project homes bad value. It means the comparison point is always the finished price on your block, which is also the honest way to weigh a project home against an architect designed build.

What the Central Coast adds

The Coast's beauty is geological, and geology sends invoices.

Slope. Our suburbs run up ridgelines and down to the water, and slope is the biggest single site cost driver: cut and fill, retaining, piered slabs, split levels. Industry guides put retaining walls alone at several hundred dollars per square metre of wall face. A gentle fall to the street is money in your pocket; a steep fall away from it is the opposite. Check whether a site is too steep before you buy it.
Rock. Hawkesbury sandstone is wonderful until your excavator meets it. Rock excavation rates run several times soil rates, which is why a thin "excavation" provisional sum on a Coast block should worry you. That mechanism has its own explainer: provisional sums and prime cost items.
Bushfire (BAL) construction. A bushfire prone classification adds construction requirements that scale steeply with the rating. Industry cost guides put the premium at a few thousand dollars at BAL 12.5, tens of thousands through BAL 29 and BAL 40, and potentially six figures at BAL FZ. Treat those as indicative, but treat the direction as certain.
Flood levels. On flood affected land, habitable floors (and now parking) must sit above the minimum habitable level, which can mean suspended floors and more structure. The Flood Information Certificate that tells you your level costs $370 from Council.

The pattern: the same house costs meaningfully different amounts on different blocks. Which is why pricing the build before committing to the land is step one of my checklist for buying a block on the Central Coast.

Where costs are heading

The panic years are over: national construction cost growth was 2.5 per cent for 2025 per Cotality's Cordell index, the smallest annual rise since 2002, against a pre-COVID decade average of 4.7 per cent. But the step change already happened and is not reversing. Rider Levett Bucknall put the rise in residential building costs at about 31 per cent over the five years to mid 2025. Anyone whose budget expectations were formed before 2020 is working from a different world, and it shows in a lot of first conversations I have.

How to budget like it will actually go

Set the finished-house budget first, then work backwards to land plus build plus buffer.
Hold a 10 to 15 per cent contingency (the standard quantity surveyor advice), more on a sloping or constrained block.
Get the site information early: survey, geotech, flood and bushfire layers. Every dollar spent knowing the block is ten not spent discovering it.
Interrogate allowances and exclusions in every quote before comparing totals, and know the questions to ask before signing.
If the numbers only work with no buffer and skinny allowances, change the design, not the arithmetic.

If you want a reality check on what a build is likely to cost on your specific block, before an agent or a salesperson gives you their version, send me the address and I will tell you what I see, including the site costs people forget. The rest of the journey is mapped in before you build on the Central Coast.