NSW Dual Occupancy Planning Guide

Can I build a duplex on my land in NSW?

Zoning, lot size, frontage and approval pathway all affect whether a dual occupancy is permissible on a NSW property. SiteScope's free scan retrieves the current planning controls for any NSW address from the NSW Planning Portal.

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NSW planning terminology

What is a dual occupancy in NSW?

In NSW planning law, the development type is called dual occupancy — two dwellings built on a single lot. A duplex is the common term for an attached dual occupancy, where the two dwellings share a party wall. A detached dual occupancy has two separate structures on the same lot.

Both types require development consent — either a Development Application (DA) assessed by council, or a Complying Development Certificate (CDC) issued by a private certifier. Which pathway applies depends on the site and the proposal.

Important: The minimum lot size, frontage and other development standards for dual occupancy vary by council and by whether the site is within a Transport Oriented Development (TOD) or Low and Mid-Rise Housing (LMR) precinct. Do not rely on any single threshold as universal. Check the current controls for your specific address.
Eligibility factors

What determines whether a duplex is permissible?

Several planning controls must all be satisfied before a dual occupancy can be approved. The main ones are:

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Zone — Dual occupancy must be a permissible land use in your zone. Following NSW Government planning reforms, dual occupancy is permitted in R1, R2, R3 and RU5 zones across NSW. Some councils have additional controls. The zone for your address is confirmed in the free SiteScope scan.
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Minimum lot size — Your lot must meet the minimum area set in the Local Environmental Plan (LEP) for dual occupancy. This threshold varies by council. For sites within a TOD precinct near a train station, the NSW Government's TOD SEPP may allow reduced lot sizes. SiteScope retrieves the LEP minimum for your specific address.
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Frontage — Most councils require a minimum street frontage for dual occupancy. Requirements typically range from 12 m for CDC to higher thresholds for some DA schemes. Frontage is a common reason CDC is ineligible on narrow suburban lots.
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FSR and height — The Floor Space Ratio (FSR) and maximum building height in the LEP constrain the size and envelope of the development. A site may be permissible for dual occupancy but may not have sufficient FSR to achieve a viable build.
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Heritage and overlays — If the property is a heritage item, within a heritage conservation area, affected by a flood overlay, on bushfire prone land, or in an acid sulfate soils area, additional conditions apply and the CDC pathway may be blocked entirely. SiteScope checks these overlays for every scan.
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TOD and LMR precincts — Properties within Transport Oriented Development precincts (within walking distance of certain train stations) or Low and Mid-Rise Housing precincts may qualify under different standards. The NSW Government has progressively expanded these areas. SiteScope checks TOD and LMR status live for each scan.
Approval pathways

CDC or DA — which applies to a duplex?

Whether a dual occupancy can use the faster CDC pathway depends on whether the proposal meets all non-discretionary standards under the applicable State Environmental Planning Policy. If one standard cannot be met — lot size, setback, height or an overlay — a DA is required.

CDC — Complying Development Certificate
Assessed byPrivate certifier
Minimum timeframe20 business days
Council involvementNone (for eligible sites)
When it appliesAll non-discretionary standards met
Key riskIneligible if any standard fails
DA — Development Application
Assessed byCouncil
Typical timeframe40–220 days (varies by council)
Council involvementFull merit assessment
When it appliesCDC excluded or preferred by applicant
Key riskCouncil discretion; conditions of consent
SiteScope's scan identifies the likely approval pathway for a given site based on live planning data — zone, overlays and LEP controls. For CDC, a certifier must confirm full eligibility before lodgement. See the CDC eligibility guide →
Common reasons a duplex cannot proceed

When a duplex is not permissible.

Planning controls
  • Lot is below the LEP minimum size for dual occupancy
  • Frontage is below the minimum required for CDC or DA
  • Zone does not permit dual occupancy (e.g. RU1, RE1, E zones)
  • FSR leaves insufficient build area for a viable dual occupancy
Site overlays
  • Heritage item or conservation area (CDC excluded; DA may have conditions)
  • Flood planning area (may require flood report and mitigation)
  • Bush fire prone land (BAL assessment required; CDC restrictions)
  • Acid sulfate soils, mine subsidence or contamination
Important: These restrictions do not always mean development is impossible — some sites with overlays can still proceed with additional requirements or conditions. A licensed town planner can advise on the specific implications for your site. SiteScope's scan identifies which overlays apply, but does not advise on how to address them.
What SiteScope checks

What the free scan confirms — and what it does not.

What the scan checks
  • Zone and permitted development types
  • FSR, maximum height and minimum lot size from the LEP
  • Lot area from the NSW cadastre
  • Heritage, flood, bushfire and other overlays
  • TOD and Low and Mid-Rise Housing SEPP status
  • Likely approval pathway (CDC or DA)
  • Development potential score (0–100)
What requires professional advice
  • Exact frontage of the lot (requires a survey)
  • Full CDC eligibility (requires a certifier)
  • DCP controls (setbacks, landscaping, car parking)
  • Utility connections and drainage feasibility
  • Strata subdivision requirements post-construction
  • Title conditions, easements and covenants
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Common questions

Questions about building a duplex in NSW.

What lot size do I need to build a duplex in NSW?
Minimum lot sizes are set by the LEP for your council. They vary — and have changed following recent NSW Government planning reforms. Sites within TOD or Low and Mid-Rise Housing precincts near train stations may qualify under different standards. SiteScope's free scan retrieves the current minimum for your specific address from the NSW Planning Portal rather than applying a generic number.
Can I build a duplex in an R2 Low Density Residential zone?
Following recent NSW Government reforms, dual occupancy is now permitted in R1, R2, R3 and RU5 zones. However, your lot still needs to meet the minimum size and frontage requirements set in the LEP, and overlays such as heritage or flood may apply. Scan your address to see the current controls.
What is the difference between a duplex and a dual occupancy?
In NSW planning law, the formal term is dual occupancy — two dwellings on one lot. A duplex is the common name for an attached dual occupancy where the two dwellings share a party wall. A detached dual occupancy has two separate freestanding structures. Both require either a DA or a CDC.
Do I need council approval to build a duplex?
Yes, development consent is required for dual occupancy in NSW. This is either a Development Application (DA) assessed by council, or a Complying Development Certificate (CDC) issued by a private certifier for eligible sites. See the CDC eligibility guide for more detail.
If my property is eligible for a duplex, does that mean the development is financially viable?
Not necessarily. Planning permissibility and financial feasibility are separate questions. A site can be legally permissible for dual occupancy but still not viable if the land price, construction costs or achievable sale prices leave no margin. A development feasibility report assesses whether the numbers stack up at the current asking price.
What does a duplex feasibility report include?
A SiteScope duplex feasibility report includes planning controls for the address, CDC vs DA pathway assessment, estimated construction costs, gross realisation value, profit margin, statutory costs and a sensitivity analysis. Tier 3 reports add multiple scenarios and comparable sales. View report tiers and pricing →
Related guides

Continue your research.

CDC Eligibility Check NSW Complying Development — what qualifies and what doesn't → NSW Development Feasibility Reports From $299 — founder-reviewed, within 24 hours → Central Coast Development Market Zoning, prices and development activity → NSW Development Resources Guides on planning, approvals and feasibility →