Granny flat cost per square metre: what the 2026 rates mean

Published 2026 Sydney rates for a granny flat sit between $2,200 and $3,300 per square metre for a medium to high specification brick veneer build. That is noticeably higher than the rate for a full sized house, and the reason is simple: a granny flat has all the expensive parts of a home packed into a much smaller floor area.

The rate is useful for understanding why a price is what it is. It is a poor tool for comparing 2 quotes, and this article explains why.

A house and a granny flat both need a kitchen, a bathroom, a hot water system, and connections to water, sewer, power and data. Those items cost roughly the same in both.

The kitchen, bathroom and connections are the most expensive square metres in any home. In a granny flat they make up a much larger share of the total floor area, so the average rate rises.

This is also why the rate falls as the granny flat gets bigger. A 40 m² studio carries the same kitchen as a 60 m² 2 bedroom, spread across two-thirds of the space.

This is where per-square-metre comparisons fall apart.

Two builders can quote the same rate per square metre and produce totals thousands of dollars apart, purely because of which column each one put those items in.

Three reasons.

It hides the inclusions. A $2,200/m² quote that excludes floor coverings, driveway and connections is more expensive than a $2,900/m² quote that includes them. The rate tells you nothing about scope.

It hides the specification. Rate ranges span low to high specification. The same footprint built with entry level fittings and with quality fittings will land at opposite ends of the range, and the rate alone will not tell you which you are looking at.

It ignores your block. Site costs are not a function of floor area. Rock does not care how many square metres you are building. On a difficult block, site costs can add more than the difference between the top and bottom of the rate range.

Compare total delivered cost for an identical scope.

• Write down every item you expect: the building, the approvals, the site works, the connections, the finishes, the external works.
• Ask each builder to mark every item included, excluded or provisional.
• Price the excluded items at market rates and add them to that builder’s total.
• Now compare.

The rate per square metre is worth knowing as a sanity check. If a quote works out at $1,500/m² for a full specification turnkey build, something is either excluded or the specification is well below what you are imagining. If it works out at $4,500/m², ask what is driving it, because there may be a good reason such as a difficult site or a high specification.

The practical takeaway: if your block allows the full 60 m² and your budget can reach it, building smaller saves less than you might expect. You still pay for the kitchen, the bathroom and the connections.