A 2 bedroom granny flat gives it a job.

In 2026 the realistic all-in range is about $95,000 for a basic prefabricated unit up to $400,000 or more for an architect-designed build. Most two bedroom granny flats land between $140,000 and $210,000 for a quality project build with good finishes. The important word is all-in: that figure needs to carry design fees, the certifier, site preparation, service connections and landscaping, not just the builder's contract price. We advise holding a 20% contingency on top, because site conditions and scope changes are the two things nobody predicts accurately.

Modestly, yes labour and trade availability in Sydney push the same plan a little above what it costs in a regional centre, and inner-city access restrictions can add real money when a crane or a narrow side boundary is involved. The bigger swing is your site, not your postcode: a flat, clear block with a sewer line close by is far cheaper to build on than a sloping block with three trees and a 25-metre service run. Sydney also returns the highest rent, so the payback period is usually shorter here despite the higher build cost.

You can buy a factory-built two bedroom unit and have it delivered and installed, which is the closest thing to buying one off the shelf typically $80,000 to $180,000 supply-and-install, before site prep and connections. What you cannot do in NSW is buy a granny flat on its own title. A secondary dwelling approved under the Housing SEPP cannot be subdivided or sold separately from the main house. If you see a two bedroom granny flat advertised for sale, it is either a transportable unit, or it is the whole property being sold with the flat included.

Not as internal floor area in a NSW residential zone the Housing SEPP caps a secondary dwelling at 60 m² in R2, R3 and R4. There are three legitimate routes to something that lives larger. First, covered outdoor space: verandahs, patios, decks and carports generally sit outside the internal floor area calculation, so a 60 m² flat with a 12 m² covered alfresco feels like a 70 square metre granny flat and is fully compliant. Second, rural zones, where many councils allow up to 120 m² or 33% of the main dwelling, whichever is greater. Third, a development application, where a council may consider a larger secondary dwelling on its merits under the local environmental plan. Ask us to check your specific zoning before you fall in love with a plan.

It is possible, but it is a different project. Two storeys almost always takes you out of the complying development pathway and into a development application, because of height, overshadowing and overlooking of neighbours. Expect two to six months for approval rather than two to three weeks, a design that has to answer privacy objections, and a build cost from roughly $285,000. It is the right answer on a genuinely tight footprint or in a rural zone with generous floor area; it is the wrong answer on a standard block where a single-storey 60 m² plan fits comfortably.