ON THIS PAGE

• 01. The rule that changed
• 02. Three pathways, not two
• 03. What actually decides it
• 04. The Pattern Book track
• 05. Subdivision: the question everyone asks second
• 06. Low and mid rise housing areas, and where they are not
• 07. Where Sydney councils sit
• 08. What is coming, and what is not law yet
• 09. Before you buy a block
• 10. FAQ

The rule that changed

Three moves, over roughly eighteen months. The third one is the reason this article exists, and it was barely reported.

Move one, 1 July 2024 
The Housing SEPP was amended to permit dual occupancies and semi-detached dwellings with consent in R2 Low Density Residential zones. That overrode local environmental plans which had prohibited them outright, and a number of LEPs had.
It was not, despite how it was widely reported, a statewide change. Four local government areas were excluded and remain excluded: Bathurst Regional, City of Hawkesbury, City of Blue Mountains and Wollondilly.

Move two, the catch. 
That new permissibility could not be used for complying development. Clause 1.19(3B) of the Codes SEPP excluded a dual occupancy from the Low Rise Housing Diversity Code where it was permissible only because of the new Housing SEPP provision, with an exception for land where dual occupancy was already permitted under the LEP.
So you had permissibility without a fast track. The practical effect was that thousands of R2 blocks became theoretically developable and practically stuck in a development application.

Move three, the one nobody reported
Clause 1.19(3B) has been repealed. It appears in the current instrument as “(Repealed)”. A dual occupancy that is permissible in R2 only because of the Housing SEPP is no longer excluded from the Low Rise Housing Diversity Code on that ground, anywhere in New South Wales.

All the other eligibility requirements continue to apply, and they are the subject of the rest of this article.

Why you did not hear about it
The change came through an instrument titled as a Mosman local environmental plan amendment, dealing with the Exempt and Complying Development Codes and dual occupancies under the Housing SEPP (EPI 2025-597). Despite the name it amended both the Housing SEPP and the Codes SEPP with statewide effect, and amended twelve local environmental plans in one go.
An amendment named after one council on the lower north shore that changes the rules in Albury, Cowra, Liverpool and Tamworth is not going to attract the coverage it deserves. That is not a conspiracy. It is how consolidated amending instruments are titled.

Three pathways, not two

These periods are expressed in the Regulation as days, not business days. You will see “business days” used. It is wrong, and it overstates every period by roughly forty per cent.

One further point that matters more than the headline comparison. Neighbour notification for a standard CDC only applies to land in a limited list of local government areas, and then only where the lot has a boundary within 20 metres of a lot containing a dwelling. Outside those areas, there is no 14 day notification and the standard determination period is already 10 days. Which means outside those areas the Pattern Book delivers no determination time advantage at all. Its advantages there are certainty and documentation cost, not speed.

What actually decides it

Six questions, in order. The order matters, because there is no point optimising a design against the built form standards if the land is excluded.

1. Permissibility

Dual occupancy must be permissible with consent on your land, either under your council’s LEP or under the Housing SEPP overriding it. Complying development is available under the Low Rise Housing Diversity Code where the lot is in Zone RU5 Village, R1 General Residential, R2 Low Density Residential or R3 Medium Density Residential. The Pattern Book Development Code is narrower: R1, R2 and R3 only, with no RU5 pathway.

2. Minimum lot area

This is the first place articles get it wrong, and it is wrong in the expensive direction.

The area of the parent lot must not be less than whichever is the greater of 400m² and the minimum lot area specified for dual occupancies in the environmental planning instrument that applies to the land. Minimum lot sizes set under the low and mid rise provisions of the Housing SEPP are expressly excluded from that calculation.

It is a greater of test, not a default. If your LEP specifies 300m², the operative minimum is 400m², not 300m². If it specifies 500m², the minimum is 500m². The same structure applies to manor houses and to a dual occupancy where part of one dwelling sits above part of the other.

3. Lot width

This is the second place articles get it wrong, and in our view it is the single most likely reason someone reading a duplex article buys a block that does not work.

The width of the parent lot, measured at the building line, must not be less than:

• 12 metres if the car parking space for the lot is accessed only from a secondary road, a parallel road or a lane; or
• 15 metres otherwise.

For a typical suburban lot with a driveway off the street frontage, the figure is 15 metres. Twelve metres is the exception, not the rule. And for a manor house, or a dual occupancy where one dwelling sits above the other, the requirement is 15 metres with no exception at all.

Measured at the building line. Not at the street frontage, and not at the widest point. On battleaxe and irregular blocks this is where otherwise promising sites fail.

4. Land exclusions

These sit in four separate places, and merging them into one list is how errors creep in. They also differ between the two codes.

Applying to complying development under any planning instrument: critical habitat, wilderness areas, heritage items, and environmentally sensitive areas.

Applying to the housing codes: heritage conservation areas and draft conservation areas, subject to exceptions; land reserved for a public purpose; Class 1 and Class 2 acid sulfate soils; significantly contaminated land; biobanking, property vegetation plan and private land conservation agreement land; land identified in a planning instrument as a buffer area, river front area, ecologically sensitive area, environmentally sensitive land or protected area; coastal and coastal erosion hazard land; foreshore areas; land in the 25 ANEF contour or higher, with carve outs; Water NSW special areas; and specified unsewered land in drinking water catchments.

Two of the exclusions everyone assumes are absolute are not, under the Low Rise Housing Diversity Code:

• Bushfire. Only land at BAL-40 or in the flame zone is excluded. Bushfire prone land below that threshold remains eligible, subject to additional standards, and a council or an RFS recognised bushfire consultant can determine that land is not BAL-40 or BAL-FZ. Being on the bushfire prone land map does not, on its own, disqualify you.
• Flood. Development must not be carried out on a flood control lot other than on a part of the lot that the council or a professional engineer specialising in hydraulic engineering has certified is not a flood storage area, floodway or similar. It is a certifiable, part of lot test.

Where only part of a lot is affected by an exclusion, the balance of the lot may still be usable. That is expressly preserved, and it is how a good many constrained sites still work.

One exclusion you will see listed that does not exist: proximity to a gas or dangerous goods pipeline. There is no pipeline exclusion in the Codes SEPP. A 200 metre pipeline buffer exclusion does exist, but it belongs to the Housing SEPP low and mid rise policy, which governs a development application pathway, not complying development. The two instruments are frequently merged in commentary and they should not be.

5. Heritage

Two different rules, and both are usually overstated.

A heritage item is a bar to complying development anywhere in the state, whether on the State Heritage Register, subject to an interim heritage order, or identified in a planning instrument. Two qualifications matter: development that is exempt or has been granted an exemption under section 57 of the Heritage Act 1977 may still be complying development, and where the item does not occupy the whole lot, the bar applies only to the mapped part. Draft heritage items are also excluded, and the Low Rise Housing Diversity Code and Pattern Book Code are separately excluded on land on which there is a heritage item or a draft heritage item.

A heritage conservation area is a narrower bar. It excludes the housing codes unless the development is a detached outbuilding, detached development other than a detached studio, or a swimming pool. A new dual occupancy is out. Some ancillary work is not.

Conservation areas cover whole streets rather than individual houses across much of the inner and northern suburbs, which is why this catches so many otherwise straightforward sites.

6. The built form standards

Under the Low Rise Housing Diversity Code the controls are maximum building height of 8.5 metres above existing ground level, a maximum gross floor area, setbacks, minimum landscaped area, articulation zones, privacy screens, car parking and vehicle access, and building design.

The gross floor area cap is 25 per cent of the lot area plus 300m² for lots between 400m² and 2,000m², and 800m² for larger lots.

Note what is not there. The code sets a gross floor area cap, not a floor space ratio, and the two behave differently. It contains no deep soil provision, no principal private open space standard for dual occupancy, and no solar access standard. Those appear in other codes and in design guidance, and importing them into a complying development assessment is a common error.

The 0.65:1 figure you may have seen is a different regime altogether. It is a non-discretionary standard for dual occupancy in low and mid rise housing areas under the Housing SEPP, on the development application pathway, alongside a 450m² minimum lot size, 12 metre lot width, 9.5 metre height and one parking space per dwelling. It has no application to a complying development certificate under the Low Rise Housing Diversity Code, where the controls are 8.5 metres and a gross floor area cap.

Every standard that does apply must be met exactly. The landscaped area provisions in particular have a long history of catching out designs that satisfy everything else.

The Pattern Book track

Since 30 July 2025 there has been a separate, faster complying development pathway for designs taken from the NSW Housing Pattern Book, sitting in Part 3BA of the Codes SEPP and applying to land zoned R1, R2 and R3.

The low rise catalogue comprises eight designs endorsed by the Government Architect, covering semi-detached dwellings, manor homes, row homes and terraces. Nine mid rise designs were added later. Those mid rise designs are not in Part 3BA and have no complying development pathway. If someone tells you “the Pattern Book has seventeen designs and they all get a 10 day CDC”, only the first half is close.

How it works:

• The application must be determined within 10 days, and cannot be issued until at least 7 days after neighbours and the council are notified.
• The application must be accompanied by a written statement from an accredited designer, identifying the development type, the pattern selected and that the development will comply with the pattern’s development standards, location requirements, technical drawing set and technical information. An accredited designer means either a qualified designer, which is a person registered as an architect under the Architects Act 2003, or a person accredited as a building designer by the Building Designers Association of Australia. That is narrower than it sounds.
• The ordinary dual occupancy design statement requirement does not apply to a Pattern Book application. The designer’s statement replaces it.
• Patterns cost $1,000 per lot. They were available at an introductory price of $1 per lot until 31 January 2026. The licence covers one building on one site. Using the same pattern on another lot, or for an additional building, requires a further fee, and volume or other commercial use requires the prior written consent of the Government Architect.
• One mechanical point that is often described vaguely. Under the Pattern Book Code the minimum lot size in your planning instrument applies to the lot unless the lot is within a low and mid rise housing area, in which case it is switched off. That is a lot size rule, not a zone rule, and it applies across all four housing types

Subdivision: the question everyone asks second

Building two dwellings and being able to sell them separately are different things, tested separately.

• No subdivision leaves two dwellings on one title.
• Strata title creates separate lots within one parcel.
• Torrens title creates two entirely separate lots.

Torrens subdivision of a dual occupancy as complying development runs through the Subdivisions Code, not the Low Rise Housing Diversity Code. The Low Rise Housing Diversity Code certificate is the trigger. The Subdivisions Code is the authority. Under it:

• Only one dwelling may be on each resulting lot.
• Each resulting lot must be in Zone RU5, R1, R2 or R3.
• Each resulting lot must be at least 6 metres wide measured at the building line, with lawful access and frontage to a public road. This one is routinely forgotten.
• The area of each resulting lot must be at least the minimum specified for subdivision for the purpose of a dual occupancy in the applicable planning instrument, or 200m² where none is specified.

Note that 200m² is a different number from the minimum for building the duplex in the first place, and it is drafted differently: here it genuinely is a default that applies only where the instrument is silent. Do not apply the greater of logic from the lot area rule to this one.

Separately, an amendment to the Housing SEPP has been reported as overriding local environmental plans that prohibited dual occupancy subdivision in low and mid rise housing areas across R1, R2 and R3 zones. If a council has told you subdivision is not permissible, that advice may predate the amendment and is worth revisiting. We have deliberately not stated a clause number for it here, because we have not been able to verify the numbering against the current Housing SEPP, and a wrong citation is worse than none.

Be careful not to merge the two figures either. The subdivision standard in low and mid rise housing areas is a different number again from the 200m² default.

Low and mid rise housing areas, and where they are not

Several of the figures floating around duplex commentary belong to the low and mid rise housing policy rather than to complying development, and that policy is not statewide.

Low and mid rise housing areas exist only across metropolitan Sydney, the Central Coast, the Illawarra and Shoalhaven, and the Hunter, in walking catchments around a defined list of nominated town centres and stations. Not every station. Not every centre. And Transport Oriented Development areas are expressly excluded from the policy.

If you are in Dubbo, Wagga or Coffs Harbour, the 450m² minimum, the 0.65:1 ratio and the low and mid rise subdivision standards have no application to your site at all.

Within those catchments, walking distance is measured along a publicly accessible walking route that can safely be walked using footpaths and pedestrian crossings, not as the crow flies, out to 800 metres. You will see an inner 400 metre and outer 400 to 800 metre split quoted. That split applies to residential flat buildings and shop top housing in R3 and R4 zones. For dual occupancy there is a single set of standards across the catchment, so in a duplex context the split is a distraction.

One more caution. The Department’s indicative maps of these areas are not legislative and should not be used to make planning decisions. Whether a particular lot is in a low and mid rise housing area is a question to be answered against the instrument, not a map.

Where Sydney councils sit

Twelve local environmental plans were amended by the consolidated instrument. Eight of them will matter to most Sydney readers, and four are regional: Albury, Cowra, Murray and Tamworth Regional.

Beyond those, thirteen councils were given the opportunity to nominate a minimum lot size for dual occupancy in their area, on the condition that dual occupancy is delivered on at least half of their R2 land. Ku-ring-gai, for example, consulted its community on two options while trying to protect its tree canopy and conservation areas.

The practical consequence is that “the minimum lot size in R2” is now a council by council question with a moving answer, and it interacts with the greater of test described above. Which is exactly why an article cannot tell you whether your block works.

What is coming, and what is not law yet

The NSW Government has legislated, but not commenced, a complying development variations pathway at section 4.31A of the EP&A Act. The section does not appear in the Act as currently in force. An Explanation of Intended Effect was exhibited from 14 May to 24 June 2026, the Department is reviewing submissions, and commencement has been signalled for the third quarter of 2026.

As proposed, and every element of this is a proposal capable of changing:

• The variation would be assessed by the council, which would issue a variation certificate. A certifier could not issue one, though a certifier could still issue the complying development certificate itself.
• No more than three to four development standards could be varied for a single development. The Department’s own wording is “3 to 4”, so do not sharpen it.
• A short written justification, of one to two pages, would accompany the application.
• The pathway could not be used where construction has already commenced, or to address non compliances that arise during construction.
• The first stage targets low rise housing under the Codes SEPP.

The rationale is the Department’s estimate that proposals which fall marginally short of complying development standards and are pushed into a full development application take on average more than 60 days longer to assess. That figure is the Department’s own, published in support of the reform, with no methodology published alongside it. It measures additional assessment time for narrowly non compliant proposals. It is not a general comparison between a development application and a complying development certificate.

Before you buy a block

Three things, and none of them are our work. Do them yourself.

Measure the width at the building line

Not the frontage on the contract diagram. Not the widest point. If it is within half a metre of the threshold that applies to your access arrangement, get a surveyor before you commit. Remember the threshold is 15 metres unless parking comes only off a lane, a secondary road or a parallel road.

Get the section 10.7 planning certificate, and know what it does not tell you

A section 10.7 certificate reliably gives you the zone, the applicable planning instruments, whether the land is in a conservation area or contains a heritage item, whether the land is bush fire prone, and whether the complying development codes are varied for the land.

What it does not give you:

• The bushfire attack level. Eligibility turns on whether the land is BAL-40 or flame zone. The certificate tells you only whether the land is bush fire prone. The rest needs a council or RFS recognised consultant determination.
• Which parts of a flood control lot are floodway or flood storage. The certificate discloses flood related development controls in defined circumstances. It does not answer the question the Codes SEPP actually asks.
• Contamination, reliably. There is no dedicated contaminated land item. Contamination surfaces only where a council or public authority has an adopted policy restricting development on that ground.

And the caveat almost nobody mentions: where the council does not have sufficient information to work out the extent to which complying development can be carried out on the land, the certificate may lawfully say a restriction applies, that it may not apply to all the land, and that the council does not know. A certificate in those terms tells you nothing. Treat a section 10.7 as a prompt for further investigation, not as a clearance.

Confirm the pathway before you brief a designer

The order in which people usually do this is backwards. A design is commissioned, then the pathway is tested, then the design is reworked. Confirming permissibility, area, width and exclusions first costs a fraction of a redesign, and it is the single highest return hour on a dual occupancy project.

Key takeaways

• The R2 complying development exclusion is gone. Clause 1.19(3B) of the Codes SEPP is repealed. Anything you read about a Ballina carve out is out of date.
• Width is 15 metres, not 12. Twelve applies only where parking is accessed solely from a lane, secondary road or parallel road, and never for a manor house or a stacked dual occupancy.
• Lot area is the greater of 400m² and your instrument’s figure, not the instrument’s figure with 400m² as a fallback.
• Bushfire and flood are qualified exclusions under the Low Rise Housing Diversity Code and absolute under the Pattern Book Code. The same lot can be eligible under one and not the other.
• There is no pipeline exclusion in the Codes SEPP. That belongs to a different instrument and a different pathway.
• The 450m² and 0.65:1 figures are development application standards in low and mid rise housing areas, which exist only in defined catchments in Sydney, the Central Coast, the Illawarra and Shoalhaven and the Hunter.
• Determination periods are days, not business days, and outside the notification areas a standard CDC is already 10 days.
• Section 4.31A is not law. Do not plan around the variations pathway.

Frequently asked questions

Primary sources and further reading

1. NSW Legislation, State Environmental Planning Policy (Exempt and Complying Development Codes) 2008, in particular clauses 1.17A, 1.18, 1.19, 1.19A, Part 3B, Part 3BA and Part 6
2. NSW Legislation, Environmental Planning and Assessment Regulation 2021, sections 131, 131A, 133, 134 and 290 with Schedule 2
3. NSW Legislation, Environmental Planning and Assessment Act 1979, sections 4.28 to 4.31
4. NSW Legislation, State Environmental Planning Policy (Housing) 2021
5. NSW Planning, NSW Housing Pattern Book, using the pattern book and terms and conditions
6. NSW Planning, Low and Mid-Rise Housing Policy, summary of key provisions and policy exclusions
7. NSW Planning Portal, Variations and changes to complying development: explanation of intended effect

Related insights: The fast-track assumption: why confirming comes before designing · Why a site change that feels minor can stop your project cold · When your reports don’t talk to each other, neither does your approval

This article is general information about NSW planning and certification prepared by registered certifiers. It is not legal advice and does not take account of the circumstances of any particular site. Planning instruments in this area change frequently. Eligibility must be confirmed against the current instruments for the individual lot before any commitment is made, including a purchase.

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