Can my block fit a duplex? NSW lot size, frontage and low-rise housing rules (2026)

The lot size, width and land rules that decide whether a Sydney block can take a duplex (an attached dual occupancy), by approval route, with council examples. Every rule links to the NSW Government or council source.

By XLGUpdated: 2026-10-28Every rule and figure is dated and sourcedPublished by AUD Build

Short answer

For a fast complying development certificate (CDC), a duplex lot generally needs to be in an R1, R2, R3 or RU5 zone where dual occupancy is permitted, meet the council’s dual occupancy minimum lot size (400 m² if the LEP sets none), be at least 15 m wide at the building line (12 m if vehicle access is only from a secondary road, parallel road or lane), front a public road, and not be a battle-axe lot, heritage item, heritage conservation area or BAL-40 or flame-zone bushfire land [3] [4] [1] [5]. Through a development application (DA), lots within 800 m of 171 nominated stations and town centres can use the Low and Mid-Rise Housing standards: 450 m² minimum lot size and 12 m minimum width [6] [7]. Councils set very different minimums elsewhere: Ku-ring-gai requires 1,015 m² outside its Local Housing Areas and for every CDC, and Hornsby 700 m² (attached) or 800 m² (detached) outside heritage conservation areas [13] [14].

These are summaries of official guidance read on 28 October 2026, not planning advice; confirm your own lot with a section 10.7 planning certificate and a certifier or planner.

The two approval routes compared

Rule	CDC (Low Rise Housing Diversity Code)	DA inside a Low and Mid-Rise Housing area
Zones	R1, R2, R3, RU5, where dual occupancy is permitted with consent [1] [2]	R1, R2, R3, R4 where permitted [7]
Minimum lot size	The LEP’s dual occupancy minimum, or 400 m² if none [3]	450 m² [7]
Minimum lot width	15 m at the building line; 12 m if access is only from a secondary road, parallel road or lane [3]	12 m [7]
Maximum height	8.5 m [3]	9.5 m [7]
Floor area	Gross floor area up to 25% of the lot area plus 300 m² (lots of 400–2,000 m²) [3]	Floor space ratio up to 0.65:1 [7]
Parking	At least one off-street space per dwelling [3]	1 space per dwelling [7]
Subdivision	Torrens only if the LEP allows it; each lot meets the LEP minimum, or 200 m² if none [3]	225 m² and 6 m wide per lot (R1–R3) [7]
Who decides and how fast	Council or a registered certifier, within 20 days if it complies [1]	Council; it cannot refuse for failing an LEP or DCP standard that these standards meet [7] [8]

The CDC standards summary still carries its 2020 content date, and the Department exhibited changes to complying development from 14 May to 24 June 2026, so check the rules that apply on the day you lodge [3] [10]. Official sources also differ on whether a CDC is available where the Housing SEPP, rather than the LEP, newly permits dual occupancy; confirm this with a certifier [2] [8].

The Low and Mid-Rise Housing changes

Stage 1, from 1 July 2024, permitted dual occupancies and semi-detached homes in the R2 low-density residential zone across NSW [6]. Councils note this does not apply on some excluded land, such as heritage items and bushfire-prone land [13] [16].
Stage 2, from 28 February 2025, created Low and Mid-Rise Housing areas: residential land within 800 m walking distance of 171 nominated town centres and train, metro or light rail stations [6] [8].
If any part of a site is in the area, the provisions apply to the whole site [8].
Excluded from the policy: bushfire-prone land (vegetation categories 1–3 and buffer), certain flood land, land within 200 m of a dangerous-goods pipeline, high aircraft-noise land, TOD areas, heritage items, and the whole Hawkesbury, Blue Mountains, Wollondilly and Bathurst council areas [9].

Council examples

Council	What the council states (read 28 October 2026)
Ku-ring-gai	1,015 m² minimum for a dual occupancy DA outside the Local Housing Areas and for every CDC in the council area; inside those areas a DA can use the state 450 m² standard [13]
Hornsby	Outside heritage conservation areas: 700 m² (attached) or 800 m² (detached), with subdivided lots of 350 m² or 400 m²; inside them, 800 m² or 900 m² [14]
The Hills	600 m² (attached) or 700 m² (detached) in R2 and R3; the LEP prohibits Torrens or strata subdivision of dual occupancies, with narrow exceptions [15]
Parramatta	At least 600 m² and a 15 m frontage to a public road; 450 m² and 12 m inside Low and Mid-Rise Housing areas [16]
Ryde	The council states attached dual occupancies under the Code need at least 580 m² and 15 m at the building line (12 m with rear vehicle access); its page is undated, so confirm with council [17]
Blacktown	Within about 800 m of Blacktown, Mt Druitt, Seven Hills, Doonside and Kellyville stations, 450 m² to build a dual occupancy; Torrens lots of 225 m² and 6 m there, or 450 m² per lot for an attached dual occupancy under the LEP elsewhere [18]

Torrens or strata after the build

A Torrens-titled attached duplex becomes two semi-detached dwellings; strata subdivision does not change the land-use definition [8] [18].
Under a CDC, the duplex and its subdivision can be approved together, but the subdivision is registered only after an occupation certificate is issued [3]. Torrens title under the Code is not available with basement car parking [5].
Some councils limit or prohibit dual occupancy subdivision (for example The Hills), and Parramatta says the Low and Mid-Rise subdivision standards apply only where the LEP already permits subdivision [15] [16].
For the state Housing and Productivity Contribution, a dual occupancy and its Torrens subdivision are treated as separate developments [19].

How to check your own lot

Look up zoning, heritage, bushfire-prone land, TOD areas and the Low and Mid-Rise maps in the NSW Planning Portal Spatial Viewer [12] [9].
Order a section 10.7 planning certificate from your council; it shows zoning, planning controls, contamination, flooding and bushfire-prone land [11].
Check both the LEP minimum lot size map and the LEP’s separate dual occupancy clause, which often sets a different minimum (for example Hornsby LEP clauses 4.1C and 4.1D) [14].
On bushfire-prone land, get a bushfire attack level (BAL) from the NSW Rural Fire Service or a bushfire consultant; flood control lots are usually mapped in the council DCP [5].
Measure the width at the building line, not just at the street, and check whether your only vehicle access is from the front.

Where AUD Build fits

AUD Design, the group’s design studio, checks the lot and prepares the DA or CDC drawings for both homes; design decides how the duplex is built and what it costs.
AUD Build prices the shared-site works, home A and home B separately, and lists subdivision as a separate item showing who prepares the documentation and its cost. Materials for both homes come from www.audbuild.net as one order with two specifications.
After completion, Real Estate AU (NSW agency licence 10147202) can sell or lease a home; construction finance can be arranged through AUD Lend (Australian Credit Licence 565029). AUD Build itself does not provide credit.
Estimate the cost with the duplex cost calculator and compare builders in Sydney duplex builders compared.

Questions

What is the minimum lot size for a duplex in NSW?

Under a CDC, the council LEP’s dual occupancy minimum, or 400 m² if the LEP sets none. Through a DA inside a Low and Mid-Rise Housing area, 450 m². Councils set higher minimums elsewhere, such as 1,015 m² in Ku-ring-gai outside its Local Housing Areas and 700–800 m² in Hornsby.

How wide does a block need to be for a duplex?

For a side-by-side duplex under a CDC, at least 15 m at the building line, or 12 m if the only vehicle access is from a secondary road, parallel road or lane. Inside a Low and Mid-Rise Housing area, a DA can use a 12 m minimum width.

Can I build a duplex on a battle-axe block?

Not as complying development: the Low Rise Housing Diversity Code does not cover battle-axe lots. A DA may still be possible under council rules.

Can I subdivide my duplex onto separate titles?

Often, but it depends on the LEP: under a CDC, Torrens subdivision is allowed only if the LEP allows it, and each lot must meet the LEP minimum (200 m² if none). Some councils, such as The Hills, prohibit dual occupancy subdivision.