Quantity surveyors Rider Levett Bucknall (RLB) put a custom-built single or double storey house in Sydney at $2,500 to $7,600 per square metre in their 2025 Riders Digest. Those are fourth-quarter 2024 rates, and they exclude GST, land, professional fees, and site works and drainage.

That range is wide on purpose. Here's what it covers, what it leaves out, and what moves you up or down it.

What does a house cost per square metre in Sydney?

Two published sources give you a starting point:

RLB Riders Digest 2025 (Sydney): $2,500 to $7,600/m² for custom-built houses. For a 325 m² house, RLB puts that at $777,500 to $2,375,000.
ABS building approvals, NSW 2024–25: 21,802 new houses approved, with an average estimated value of about $548,000 each. That's the value of the building work, not the land, and it covers the whole state, including project homes in growth areas.

From our own pricing, for new detached houses in Sydney metro in 2025–26:

Standard custom build: $2,900 to $3,900/m²
High-end custom: $3,400 to $5,500/m²
Luxury: $6,000 to $11,000/m²

A 280 m² house at $3,400/m² is $952,000. The same house at $4,800/m² is $1.34 million.

What isn't included in the per square metre rate?

More than people expect. RLB's rates exclude GST, land, legal and professional fees, and site works and drainage. A builder's rate often leaves out some of the same things.

In our experience on knockdown rebuilds, the items outside the build quote, such as demolition, consultants, council fees, HBCF insurance, service connections, site costs and landscaping, routinely add 25–35% on top. In our worked example, a $1.176 million build quote became a $1.6 million project.

So when you compare a "per square metre" figure, ask what's inside it.

What makes building on a Sydney site cost more?

The site, before anything else:

Slope. Sloping sites add 10–25%, before you've chosen a tap, for retaining walls, drainage and often piling.
Rock. Sandstone has to be cut or broken out, and it's slow work. Our figures for site costs range from about $15,000 on a flat sand block to $150,000 or more on a steep Northern Beaches site with sandstone.
Access. If machines and trucks can't get in, more of the work is done by hand, and it takes longer.
Coastal exposure. Within about a kilometre of open ocean, corrosion protection adds 5–15% to the reinforced concrete work. If the house needs piles, the foundation alone can run from about $90,000 to well past $250,000. See building on a steep or coastal site.

Get a geotechnical report before you sign a fixed price. Without one, the builder is guessing about the ground, and the guess won't be in your favour.

How much does the design affect the cost?

A lot, and most of it is decided before you lodge for approval:

Roof shape. Every change of roof plane adds framing, flashing and labour. A complex roofline can add $60,000 over a simple one on the same floor area.
Wet areas. Bathrooms stacked above each other and a kitchen next to the laundry keep plumbing runs short.
Working with the slope. A house that steps down with the land costs much less than flattening the land to suit the house.
Storeys and structure. Large spans, cantilevers and big glazed openings need more steel and engineering.

Do finishes and PC items change the price much?

Less than most people think. On a million-dollar build, there's maybe $40,000 of difference in tapware and stone.

Where finishes catch people is in the quote. A low PC (prime cost) allowance makes a quote look cheap, then you pay the difference when you pick what you actually want. Check every allowance against real prices for the products you want before you sign.

Should I get a fixed price or cost plus?

It depends on how complete your drawings are and how much is still unknown about your site. A fixed price only gives you certainty if the scope, the ground and your selections are all settled. Fixed price or cost plus goes through the trade-offs.

Whichever you choose, ask every builder the same thing: "What's in your quote, and what will I be invoiced for separately?" Their answer tells you more than their rate per square metre.

The short version

RLB puts a custom house in Sydney at $2,500 to $7,600/m² (2025 Riders Digest), before GST, land, fees and site works.
The average new NSW house approved in 2024–25 was about $548,000 of building work, across the whole state and including project homes.
Costs outside the build quote often add 25–35%.
Slope, rock, access and coastal exposure can move the price more than finishes.
Design decisions like the roof, wet area layout and working with the slope matter more than tapware.
Get a geotech report and a clear list of exclusions before you sign.

Pricing a build in Sydney? Tell us about your site and we'll give you a straight read on what it's likely to cost.