Dual Occupancy
Two dwellings on one lot — attached (a duplex) or detached. In NSW the Housing SEPP now permits dual occupancy with consent in R1–R4 zones on lots of at least 450m² with 12m frontage, and the pair can be Torrens-subdivided and sold separately where each new lot is at least 225m². A value-add step between a cosmetic flip and a full subdivision.
Dual occupancy means two dwellings on a single lot. They can be attached (a duplex sharing a common wall) or detached (two separate houses on the one title). It sits between a straight cosmetic flip and a full subdivision as a value-add strategy: you double the dwellings, and potentially the income, without necessarily creating two separate titles.
Whether a lot can carry a dual occupancy is set by planning controls, and in NSW those controls changed. Under the Low and Mid-Rise Housing reforms — the first stage commenced 1 July 2024, with the controls finalised on 28 February 2025 — dual occupancy is now permitted with consent in the R1, R2, R3 and R4 zones across the state on a lot of at least 450m² with a 12m frontage, up to a 0.65:1 floor space ratio and a 9.5m height limit. Overlays such as flood, bushfire and heritage still sit on top, so it always comes back to checking the individual block: a site a metre short on frontage or under the minimum lot size simply will not qualify. See how much it costs to build a duplex in NSW for the build-cost side.
Dual occupancy vs the alternatives
It is easy to confuse dual occupancy with a granny flat and with subdivision, and the differences drive the numbers. A granny flat (secondary dwelling) is subordinate to the main house and capped in size; a dual occupancy is two genuine dwellings of comparable standing. Subdivision splits the land into separate titles; a dual occupancy sits on one title until you subdivide too — and in NSW the reforms now allow Torrens subdivision of a dual occupancy where each resulting lot is at least 225m², so the two dwellings can be sold separately as freehold homes.
The right move depends on lot size, zoning, your capital and what comparable sales support on exit. Rather than assume, test the options side by side: the feasibility tool models a dual occupancy against a straight flip and a split on the same address, and granny flat vs subdivision compares the two most common small-scale plays. General information only, not planning advice.
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