Granny Flat

A granny flat — in planning terms, a secondary dwelling — is a self-contained home with its own kitchen, bathroom and entrance, sharing a lot with the main house. For a flipper it is one of the cleaner ways to lift both rent and resale value without going through a full subdivision, because it adds a second income-producing dwelling to a single title.

The rules are state-specific, and the differences matter. In NSW, a secondary dwelling can be approved as complying development under the Housing SEPP up to 60m² of floor area on lots of at least 450m² in residential zones, which skips a full development application where the block and design comply. In Queensland the state code generally treats a secondary dwelling up to 70m², within 20 metres of the main dwelling on a lot under 1,000m², as accepted development — but individual councils set their own size caps (Brisbane commonly allows up to about 80m²), so the binding number is your council's, not the state baseline. Never carry a NSW rule of thumb into a QLD deal or vice versa.

What it does — and doesn't — do

Since occupancy restrictions were relaxed (in Queensland from September 2022), a compliant secondary dwelling can generally be rented to anyone, which is what turned the granny flat from a family annexe into a genuine income play. On resale it can lift the after-repair value in suburbs where buyers pay for dual-income or multi-generational living.

The key limitation: a secondary dwelling stays on the same title as the main house. You cannot sell it separately without subdividing, which is a different and far more expensive strategy. Overlays — flood, bushfire, heritage, and in QLD character and koala mapping — can also push a build off the fast-track pathway. Check the block before you bank the upside. The full rules are set out for each state in granny flat rules in NSW, granny flat rules in QLD and granny flat rules in VIC. General information only, not planning advice.