For many owners, a dual occupancy or duplex is the most accessible first step into development — two dwellings on land that once held one. But not every block qualifies, and not every duplex stacks up. Here's how to tell.
Dual occupancy, duplex, subdivision — what's the difference?
- Dual occupancy — two dwellings on one lot, attached or detached.
- Duplex — commonly two attached dwellings, often able to be subdivided so each can be sold or titled separately.
- Subdivision — creating separate titles (Torrens or strata), which is what lets you sell each dwelling individually.
The right structure depends on your goal: hold both, sell one and keep one, or sell both.
Does your block qualify?
Councils set the rules, and they vary. The usual tests:
- Minimum lot size for dual occupancy or subdivision
- Minimum frontage and useable dimensions
- Zoning that permits dual occupancy or multi-dwelling housing
- Setbacks, site coverage, private open space and parking
A wide, regular block in the right zone is the ideal starting point.
Attached or detached — and can you subdivide?
Whether you can build attached or detached dwellings, and whether each can be separately titled, drives both the design and the end value. Separately titled dwellings typically sell for more than one combined holding — but subdivision has its own requirements and costs.
Does it stack up?
Qualifying is only half the question. The other half is feasibility: the cost to build two dwellings, plus all fees and finance, against realistic end values — with a sensible contingency. A duplex that's easy to approve can still be marginal if the numbers are tight.
How we assess it
We run your block through Scout™ — checking zoning, lot size, frontage and overlays, then modelling a full feasibility for a dual occupancy or duplex scenario. You'll know whether it qualifies, and whether it's worth doing, before you spend on plans.
Frequently asked questions
What's the minimum block size for a duplex?
It varies by council and zone — many set a minimum lot size and frontage for dual occupancy or subdivision. We check your specific controls before advising.
Can I sell the two dwellings separately?
Often yes, if the site can be subdivided by Torrens or strata title. Separately titled dwellings typically achieve stronger end values, though subdivision has its own requirements.
Is a duplex always worth building?
Not necessarily — qualifying is one thing, feasibility another. We model the build cost against realistic end values so you know whether it stacks up.
This article is general information only and does not constitute planning, legal or financial advice. Every site is different — seek advice specific to your property.