Guides

Duplex & Dual Occupancy Resources

Straight answers to the questions that decide your project, written and reviewed by a Registered Architect. No hype, no guaranteed-approval nonsense.

Can I Build a Duplex on My Block in Sydney?

It's the first question every duplex project starts with, and the answer almost always comes down to five checks. Here's how an architect works out whether your Sydney block can support a dual occupancy before you spend a cent on plans.

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Duplex DA vs CDC in NSW: Which Approval Pathway Is Right?

Two roads lead to an approved duplex in NSW: a Complying Development Certificate (CDC) or a Development Application (DA). Choosing the right one is one of the most consequential decisions in the whole project. Here's how they differ and when each wins.

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Minimum Block Size for a Duplex in NSW

The single most-asked duplex question. The short answer is 450m² with a 12m frontage for the CDC fast-track, but the real answer depends on your council's LEP and your approval pathway. Here's the full picture.

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Narrow Block & 12m Frontage Duplexes in Sydney

Frontage width is where many duplex dreams stall, and where good architecture earns its keep. A 12m frontage is the common CDC threshold, but narrower blocks can still work with the right design. Here's how.

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Battle-Axe Block Duplexes in NSW: Why CDC Is Difficult

Battle-axe blocks, the hatchet-shaped lots with a long access handle to a rear allotment, are a classic 'tricky site'. The Low Rise Housing Diversity Code excludes them from CDC, so a dual occupancy here almost always means a DA. Here's how to approach it.

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Flood, Bushfire & Heritage Duplex Approvals in NSW

Three overlays account for a large share of 'is a duplex even possible?' questions: flood, bushfire and heritage. Each changes the approval pathway and the design, but each also has a response. Here's how we handle them.

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Torrens vs Strata Subdivision for Duplexes in NSW

Building two dwellings doesn't automatically give you two titles. If your goal is to sell or hold the halves separately, subdivision has to be designed in from the start, and the choice between Torrens and strata matters for value.

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Sydney Duplex Approval Checklist

Every approved duplex follows the same underlying sequence. This checklist walks you through it, from the first feasibility check to a lodgement-ready application, so you know what's ahead and where the decisions are. Download the PDF to keep it handy.

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How Much Does a Duplex Approval Cost & How Long Does It Take in Sydney?

The two questions every owner wants answered, and the two most competitors dodge. There's no single fixed number, because it depends on your site and pathway. But there are honest ranges and clear factors that move them. Here's a straight answer.

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Looking for the latest NSW planning changes? See Planning Updates →

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