Secondary dwellings and dual occupancy: granny flats, DPUs, duplexes in AU

TL;DR

From 1 July 2024, dual occupancies became permissible in R2 Low Density Residential zones across all of NSW, overriding council LEPs that had previously prohibited them. That was the biggest shift in NSW residential planning in a generation. Secondary dwellings (granny flats) have been state-wide permissible development in NSW since 2009 under a 60m² internal area cap with a CDC pathway giving 20-day approvals. Other states have their own regimes: VIC’s Dependent Person’s Unit (DPU) has a dependency requirement and is movable; WA’s ancillary dwelling can now go up to 70m² without planning approval on any residential lot. If you’re building or advising on either typology, the first question is always: which state, which zone, and which consent pathway?

What this article is for

Granny flats, DPUs, dual occupancies and duplexes all sit in the same planning neighbourhood but operate under different rules in every state. Builders and designers regularly conflate them, and clients often assume the rules are simpler than they are. This article maps each typology, covers the NSW 2024 reform, runs through the CDC pathway, and closes with the state-by-state comparison table and common gotchas.

Secondary dwellings (granny flats)

A secondary dwelling is a self-contained dwelling that is secondary to, and on the same lot as, a principal dwelling. In NSW the term and its rules are set by Chapter 3 of the State Environmental Planning Policy (Housing) 2021 (Housing SEPP 2021).

NSW Housing SEPP 2021 Chapter 3 key rules:

Zones: R1, R2, R3, R4, R5 (rural zones subject to clause 5.4 or 5.5 in the local LEP).
Maximum internal floor area: 60m². Excludes verandahs, patios, decks, garages, and attached ancillary storage. A 60m² interior can still have a generous covered verandah without breaching the cap.
Lot size: no minimum for the planning permission itself. The CDC pathway requires at least 450m².
Only one principal dwelling and one secondary dwelling per lot.
No subdivision permitted under the SEPP pathway. If separate titles are the goal, a dual occupancy is the correct typology from the start.
No additional parking mandated by the SEPP (council DCPs may differ if the project goes as a DA).

Dependent Person’s Units (VIC)

Victoria does not use the term “secondary dwelling” for its established small-dwelling regime. Instead, VIC has two overlapping instruments.

Dependent Person’s Units (DPU) are defined in the VPP as movable buildings on the same lot as an existing dwelling, used to house a person dependent on a resident. Key rules:

No fixed size limit (can exceed 60m²), but must be designed to be relocatable on more than one occasion. Fixed slab construction does not qualify.
Generally exempt from planning permit under Clause 62.02 of the VPP, unless another provision triggers a permit.
When the dependency relationship ends, the DPU is typically required to be removed. It does not convert to a permanent freestanding dwelling.

Small Secondary Dwellings (SSD, Clause 52.04): introduced as a transitional measure with a 60m² gross floor area cap, self-contained, no dependency rule. Planning permit required where the lot is under 300m² in a residential zone. The SSD provisions (extended by VC266 and VC304) run until 28 March 2027, after which VIC expects to absorb SSDs into the Clause 54 framework. Confirm current status before quoting a VIC SSD project.

Dual occupancy (attached vs detached)

A dual occupancy is two dwellings on a single lot. Unlike a secondary dwelling, there is no principal/secondary hierarchy, no 60m² cap on either dwelling, and subdivision into separate titles is often possible.

Attached (duplex): two dwellings sharing a common wall, each with its own entry, services, and private open space.

Detached: two dwellings structurally separate on the same lot. Less common; subject to tighter LGA controls on lot width and setbacks.

The assessment pathway is typically a DA. The Low and Mid-Rise Housing Code (February 2025) introduced a CDC pathway for complying dual occupancies within the 800m catchment.

The NSW Low and Mid-Rise Housing Reforms (1 July 2024)

Before 1 July 2024, many council LEPs prohibited dual occupancies in R2 Low Density Residential zones. The NSW Government used the Housing SEPP 2021 to override those prohibitions state-wide.

Stage 1 (1 July 2024): Dual occupancies and semi-detached dwellings permissible with consent in R2 zones across 124 LGAs. The state-level permission overrides LEP prohibitions but does not override minimum lot size controls. Excluded areas: bushfire prone land, heritage items, specific flood-prone areas, and entire LGAs including Bathurst Regional, Blue Mountains, Hawkesbury, and Wollondilly.

Stage 2 (28 February 2025): Low and Mid-Rise Housing Code commenced, creating a CDC pathway for dual occupancies, terraces, and townhouses within 800m walking distance of nominated town centres and train or light rail stations.

Minimum lot: 450m². Minimum width: 12m.
Maximum FSR: 0.65:1. Maximum height: 9.5m.
Minimum resulting lot after Torrens title subdivision: 225m².

Outside the 800m catchment, Stage 1 applies: permissible with consent via DA only, no CDC pathway.

The CDC pathway for granny flats

The CDC pathway under the Housing Code (Codes SEPP 2008) is the reason NSW granny flats became a volume product.

Eligibility checklist:

Lot at least 450m², zoned R1-R4 or RU5.
Secondary dwelling meets Housing SEPP 2021 Chapter 3 standards (60m² max, single secondary dwelling on lot, setbacks per the Housing Code).
Principal dwelling complies with Codes SEPP 2008 standards.

A private accredited certifier issues the CDC. Statutory decision period: 20 days. The CDC covers both planning and building approval in a single instrument.

Exception: if the secondary dwelling sits entirely within the existing dwelling house (e.g. a converted garage), the 450m² lot minimum does not apply. The 60m² cap and all other SEPP standards still do.

The alternative, a DA, typically takes four months or more and reintroduces council discretion. The CDC pathway removes that entirely for compliant proposals.

Subdivision implications

Secondary dwellings in NSW cannot be subdivided off the principal dwelling under the SEPP pathway. If separate titles are the goal, use a dual occupancy pathway from day one.

For dual occupancies in NSW, Torrens title subdivision requires a separate DA after construction. Minimum resulting lot: 60% of the LEP minimum, or 200m² where the LEP sets none. Stage 2 Low and Mid-Rise areas: 225m² per lot. Strata subdivision is an alternative: typically 180m² strata area per lot at ground level, but varies by council.

Not all council DCPs allow Torrens title subdivision of a dual occupancy in R2 zones. In VIC, a planning permit for subdivision is almost always required. In QLD, reconfiguration of a lot is a separate approval under the Planning Act 2016.

State variance

State	Typology name	Max floor area	Lot size minimum	Planning approval required?	Dependency rule
NSW	Secondary dwelling	60m² internal area (SEPP standard)	450m² for CDC pathway; no minimum for DA	CDC (20 days) or DA	None; can be rented to anyone
VIC	Dependent Person’s Unit (DPU)	No fixed limit (movable building)	Set by zone schedule	Generally Clause 62.02 exempt; permit required if other provisions trigger	Yes; must house a person dependent on principal occupant
VIC	Small Secondary Dwelling (SSD, Clause 52.04, expires 28 Mar 2027)	60m² gross floor area	Clause 54 triggers permit if lot under 300m²	Planning permit in some cases; building permit always	None
QLD	Secondary dwelling (dwelling house)	No state-set cap; council planning schemes vary	Varies by planning scheme and zone	Building approval (and sometimes DA depending on council scheme)	None since Sept 2022; can be rented to anyone
WA	Ancillary dwelling	70m² (deemed-to-comply, R-Codes Vol 1, revised April 2024)	No minimum lot size since April 2024	No planning approval needed if deemed-to-comply; building permit still required	None
SA	Ancillary accommodation	60m² (DTS criterion); no more than 2 bedrooms	Set by zone in Planning and Design Code	DTS pathway (no consent) if compliant; otherwise performance assessed	None since 2024; can be rented to anyone

Notes: QLD secondary dwellings must remain secondary to a principal dwelling on the same lot. WA removed the 350m² minimum lot size in April 2024. SA changed its rules in 2024 to allow self-contained ancillary accommodation rented to non-residents. These are actively amended instruments; verify against each state’s current planning portal before quoting.

What can go wrong

Assuming “granny flat” means unrestricted. Going 1m² over 60m² on the CDC pathway drops the project into DA territory: months, not weeks. Measure internal floor area precisely.

Confusing secondary dwelling with dual occupancy. You cannot convert a secondary dwelling approval into separate Torrens titles after the fact. If the client wants two sellable lots, the dual occupancy pathway is the one to start with.

The VIC dependency trap. A DPU built for a parent who later moves to a nursing home is supposed to be removed when the dependency ends. Renting it to an unrelated tenant without changing the approval is technically unlawful. The SSD (Clause 52.04) is the right pathway when no dependency exists.

Shared entry assumptions. Some older DCPs required a secondary dwelling and principal dwelling to share an entry. The current Housing SEPP 2021 has no such requirement at state level. On the CDC pathway, the SEPP prevails. On a DA, the DCP can be assessed. Confirm with the certifier which instrument governs.

The dual occupancy subdivision trap. Not every council DCP allows Torrens title subdivision of a dual occupancy in R2. Building the duplex expecting to sell on separate titles, then finding the DCP prevents it, is an expensive mistake.

The 800m catchment assumption. The Stage 2 CDC standards (height 9.5m, FSR 0.65:1, 225m² minimum lot) only apply within 800m of a nominated centre or station. Outside that catchment, Stage 1 governs: DA only.

The Housing SEPP 2021 blanket override covers how SEPPs override LEPs. CDC in NSW covers the 20-day pathway mechanics. Subdivision controls: residential covers Torrens and strata options across states. For WA context, WA planning scheme structure explains how R-Codes integrate with Local Planning Schemes.

References

State Environmental Planning Policy (Housing) 2021 (NSW), Chapter 3 (Secondary dwellings), via legislation.nsw.gov.au (verified 2026-05-23).
NSW Planning Portal, secondary dwellings guidance, via planning.nsw.gov.au (verified 2026-05-23).
NSW Low and Mid-Rise Housing Policy, summary of key provisions, via planning.nsw.gov.au (verified 2026-05-23).
Victoria Planning Provisions, Clause 62.02 (DPU permit exemption) and Clause 52.04 (Small Secondary Dwellings), via planning.vic.gov.au (verified 2026-05-23).
Victorian Building Authority, small second homes guidance, via vba.vic.gov.au (verified 2026-05-23).
State Planning Policy 7.3 Residential Design Codes Volume 1 (March 2024), ancillary dwellings provisions, via wa.gov.au (verified 2026-05-23).
WA Department of Planning, revised R-Codes now in effect (10 April 2024), via planning.wa.gov.au (verified 2026-05-23).
Queensland Planning, changes to secondary dwellings (September 2022 amendments), via planning.qld.gov.au (verified 2026-05-23).
PlanSA, ancillary accommodation rules (2024 update), via plan.sa.gov.au (verified 2026-05-23).