South Australia · Planning guide
Dual occupancy rules in SA
In South Australia two dwellings on one allotment are assessed under the Planning and Design Code as detached, semi-detached, row or group dwellings, and the answer turns on the zone's site dimensions criteria. In the General Neighbourhood Zone the deemed-to-satisfy criterion is either that the development does not result in more than 1 dwelling on an existing allotment, or that each dwelling site meets the zone's minimum site area and frontage, for example 300m2 and 9m for a detached dwelling. Other zones set their numbers through technical and numeric variations mapped to the site. If the criteria are met the Act requires planning consent to be granted, and if they are not the proposal is performance assessed on its merits.
Sources read on 9 September 2026. Provisions are quoted word for word from the instrument.
How SA classifies two dwellings on a site
The Planning and Design Code does not use the phrase dual occupancy. Two houses side by side on one allotment are two detached dwellings, or semi-detached dwellings if they share a wall, and two or more dwellings sharing a common driveway on one site are group dwellings. Each of those classes appears in the zone's classification tables with its own deemed-to-satisfy criteria.
A dwelling is a building or part of a building used as a self-contained residence. That is what separates a dual occupancy from a granny flat. Ancillary accommodation shares utilities and open space with the main house. Two dwellings each stand on their own site with their own site area and frontage.
Dwelling Means a building or part of a building used as a self-contained residence.
Read the source · retrieved 9 September 2026
If a proposed development comprises more than one element or more than one class (or form) of development, each of the applicable listed classes of development is relevant. This means that: (a) for the purposes of assessment - all applicable policies and criteria must be considered by the relevant authority for the purposes of section 102 of the Act; and (b) for the purposes of procedural matters - any development that comprises more than one of the listed classes of development may trigger more than one relevant procedure.
Read the source · retrieved 9 September 2026
The zone's site area and frontage test
The controlling rule for a dual occupancy is the zone's Site Dimensions and Land Division policy. In the General Neighbourhood Zone, PO 2.1 asks that sites created for residential purposes are of a suitable size and dimension for the dwelling form and stay compatible with a low-rise, predominantly low-density neighbourhood. The deemed-to-satisfy criterion DTS/DPF 2.1 is met in one of two ways: the development does not result in more than 1 dwelling on an existing allotment, or each dwelling site meets the table of minimum site area and frontage.
That table in the General Neighbourhood Zone gives a detached dwelling 300m2 and 9m of frontage, or 5m on a battle-axe site, a semi-detached dwelling 300m2 and 9m, a row dwelling 250m2 and 7m averaged, and a group dwelling or dwelling in a residential flat building an average of 300m2 including common areas and 15m total frontage. These figures belong to that zone. They are not statewide numbers.
Other zones write the same criterion differently. The Suburban Neighbourhood Zone sets its DTS/DPF 2.1 site areas through a Minimum Site Area technical and numeric variation, and the Code lists dozens of location-specific values for it. Part 6 of the Code is the index of those variations. The value that applies to your allotment is the one spatially mapped to it in the SA planning database.
Allotments/sites created for residential purposes are of suitable size and dimension to accommodate the anticipated dwelling form and remain compatible with the pattern of development in a low-rise and predominantly low-density neighbourhood, with higher densities closer to public open space, public transport stations and activity centres. Development will not result in more than 1 dwelling on an existing allotment or Allotments/sites for residential purposes accord with the following: Dwelling Type Minimum site/allotment area per dwelling Minimum site/allotment frontage Detached dwelling (not in a terrace arrangement) 300m2 (exclusive of any battle-axe allotment 'handle') 9m where not on a battle-axe site 5m where on a battle-axe site Semi-detached dwelling 300m2 9m Row dwelling (or detached dwelling in a terrace arrangement) 250m2 7m (averaged) Group dwelling 300m2 (average, including common areas) 15m (total) Dwelling within a residential flat building 300m2 (average, including common areas) 15m (total)
Read the source · retrieved 9 September 2026
Development will not result in more than 1 dwelling on an existing allotment or Allotments/sites for residential purposes accord with the following: (a) site areas (or allotment areas in the case of land division) are not less than the following (average site area per dwelling, including common areas, applies for group dwellings or dwellings within a residential flat building): Minimum Site Area
Read the source · retrieved 9 September 2026
One type of adaption of the rules is a variation of a technical or numeric requirement that would otherwise apply under a zone, subzone or overlay that applies to a particular location. A technical or numeric variation of a technical or numeric requirement operates within parameters specified in the Code and is spatially applied through the operation of the Code and its interaction with the SA planning database.
Read the source · retrieved 9 September 2026
Keeping the existing house and adding one behind
Many dual occupancies keep the existing house and add a second dwelling at the rear. The General Neighbourhood Zone deals with this directly in PO 2.2. Where the site of a dwelling does not make up the whole allotment, the balance must meet the zone's site area and frontage figures, and the retained house must still meet the private open space table in Design in Urban Areas and the car parking rates in Transport, Access and Parking.
In practice the retained house is often what fails. A rear dwelling that leaves the front house with too little private open space or no compliant parking takes the whole proposal out of deemed-to-satisfy, even if the new dwelling itself is compliant.
Development creating new allotments/sites in conjunction with retention of an existing dwelling ensures the site of the existing dwelling remains fit for purpose. Where the site of a dwelling does not comprise an entire allotment: (a) the balance of the allotment accords with site area and frontage requirements specified in General Neighbourhood Zone DTS/DPF 2.1 and (b) if there is an existing dwelling on the allotment that will remain on the allotment after completion of the development, it will not contravene: (i) Private open space requirements specified in Design in Urban Areas Table 1 - Private Open Space (ii) off-street vehicular parking exists in accordance with the rate(s) specified in Transport, Access and Parking Table 1 - General Off-Street Car Parking Requirements or Table 2 - Off-Street Car Parking Requirements in Designated Areas to the nearest whole number.
Read the source · retrieved 9 September 2026
Built form criteria the second dwelling must meet
Site area is only the first criterion. The zone's Table 2 row for a detached dwelling in the General Neighbourhood Zone cross-references the site coverage, building height, primary and secondary street setback, boundary wall, side and rear setback criteria of the zone, and a long list of Design in Urban Areas criteria for privacy, earthworks, waste and street frontage. Site coverage must not exceed 60% and height is limited to 2 building levels and 9m with a 7m wall.
Each row also lists the overlays that exclude the class from Table 2 entirely, including the Character Area Overlay, Historic Area Overlay, heritage overlays, the bushfire hazard overlays and the Hazards (Flooding) Overlay. A site inside one of those overlays is performance assessed no matter how compliant the design is.
The development does not result in site coverage exceeding 60%. Building height (excluding garages, carports and outbuildings) no greater than 2 building levels and 9m and wall height that is no greater than 7m (not including a gable end).
Read the source · retrieved 9 September 2026
Each zone contains a table - Table 2 - which specifies classes of development which will be classified as “deemed-to-satisfy development” under section 106 of the Act in that zone if all of the corresponding criteria in the table are satisfied, insofar as they are relevant to the nature of the particular development.
Read the source · retrieved 9 September 2026
What happens if the criteria are not met
A dual occupancy that misses a deemed-to-satisfy criterion is not refused. Under section 107 of the Act it becomes performance assessed and is judged on its merits against the performance outcomes the zone's Table 3 lists for that class. The elements that were deemed-to-satisfy are taken to have consent, and only the balance is assessed. The Act allows refusal on merit only where the proposal is seriously at variance with the Code, disregarding minor variations.
Performance assessed applications for dwellings are notified to adjacent owners under section 107(3) unless the zone's notification table excludes them, and the relevant authority weighs any representations before deciding.
In a case where proposed development is to be assessed as code assessed development and the development cannot be assessed, or fully assessed, as deemed-to-satisfy development, the development will be assessed on its merits against the Planning Rules. (a) to the extent that 1 or more elements of the proposed development may be classified as deemed-to-satisfy under the Planning and Design Code (if any)—that part of the development will be taken to have been granted planning consent; and (b) to the extent that paragraph (a) does not apply (including on the basis that that paragraph does not apply at all)—the development will be assessed on its merits against the Planning and Design Code; and (c) to the extent that paragraph (b) applies—the development must not be granted planning consent if it is, in the opinion of the relevant authority, seriously at variance with the Planning and Design Code (disregarding minor variations).
Read the source · retrieved 9 September 2026
A DPF, including a Technical and Numeric Variation (TNV) or other numeric value which forms part of a DPF, provides a guide to a relevant authority as to what is generally considered to satisfy the corresponding performance outcome but does not need to necessarily be satisfied to meet the performance outcome, and does not derogate from the discretion to determine that the outcome is met in another way, or from the need to assess development on its merits against all relevant policies.
Read the source · retrieved 9 September 2026
What changes council by council in South Australia
The state instruments set the frame. These points are set by each council's own instrument or mapping, so the answer for an address depends on which council it sits in.
- SA has no council planning schemes. The zone and subzone at a site are set by the Planning and Design Code and mapped spatially, so the site area and frontage test differs by zone and location rather than by council.
- In zones that use a Minimum Site Area technical and numeric variation, such as the Suburban Neighbourhood Zone, the figure is one of many location-specific values indexed in Part 6 of the Code and mapped to the allotment.
- Overlays listed in each zone's Table 2, including Character Area, Historic Area, heritage, bushfire and flooding overlays, remove the deemed-to-satisfy pathway for dwellings on affected sites.
- Subzones prevail over zone policy, so a subzone can change the site area, frontage or built form criteria that the zone sets.
- The council's assessment manager or panel is usually the relevant authority for performance assessed dwellings, so the exercise of merit discretion happens locally.
For your address
How the $150 report settles this for one site
A Casa preliminary planning report reads the Code zone, subzone, overlays and mapped technical and numeric variations at your parcel from the SA planning database, applies that zone's site area and frontage criteria to your allotment, and identifies the overlay exclusions that would take a second dwelling out of the deemed-to-satisfy pathway. It sets out the pathway and the numbers that apply at that address, and it does not decide the application or replace building consent.
Common questions
What lot size do I need for two dwellings in SA?
It depends on the zone and any mapped technical and numeric variation. In the General Neighbourhood Zone the deemed-to-satisfy table requires 300m2 and 9m frontage per detached dwelling, 250m2 and 7m averaged for a row dwelling, and an average of 300m2 with 15m total frontage for group dwellings. Other zones set their figures through a Minimum Site Area variation mapped to the site.
Can I build a second house behind my existing one?
Yes if the balance of the allotment meets the zone's site area and frontage figures and the retained house still meets the Design in Urban Areas private open space table and the car parking rates. General Neighbourhood Zone DTS/DPF 2.2 sets those tests.
Is a dual occupancy deemed-to-satisfy in SA?
It can be, where every criterion in the zone's Table 2 row for the dwelling class is met and the site is outside the excluded overlays. Section 106 of the Act then requires planning consent to be granted without public notification.
What if my block is just under the site area?
The proposal is performance assessed under section 107 rather than refused outright. The Code says a technical and numeric variation is a guide to what generally satisfies the performance outcome and does not have to be met if the outcome is achieved another way, but the relevant authority must refuse a proposal that is seriously at variance with the Code.
Do I have to subdivide to build two dwellings?
No. DTS/DPF 2.1 applies to sites as well as allotments, so two dwellings can sit on one allotment as group or detached dwellings. Dividing the land into separate titles is a separate land division approval under section 102(1)(c) of the Act.
Sources read for this guide
- Planning and Design Code (SA), Version 2026.15 (13 August 2026), State Planning Commissionread 9 September 2026
- Planning, Development and Infrastructure Act 2016 (SA), version 30.7.2026read 9 September 2026
Not covered here
- The Part 7 definitions of detached, semi-detached, row and group dwelling were not extracted, so the descriptions of those classes in the first section are general and not quoted.
- The General Neighbourhood Zone Table 2 row for a detached dwelling is a multi-column table and its cross-references are described rather than quoted. The overlay exclusions named are taken from that row.
- Only the General Neighbourhood Zone and the Suburban Neighbourhood Zone site dimension criteria were read. Other residential zones were not extracted.
- Planning and Design Code quotes were taken from Casa's cached copy of the plan.sa.gov.au PDF (Version 2026.15, sha256 ca767fce, fetched 2026-09-08 and re-read 2026-09-09). The Act was fetched live from legislation.sa.gov.au on 2026-09-09.
More SA guides
- Granny flat rules in SA
- Subdivision rules in SA
- Fast-track approvals in SA
- Height and setback rules in SA
- Do I need a DA in SA?
Dual occupancy and duplex rules in other states
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