Granny flat costs in South Australia
| Studio, 35–45 m² | A$90,000 – A$135,000[1] |
|---|---|
| One bedroom, 45–60 m² | A$120,000 – A$165,000[1] |
| Two bedrooms, 60–70 m² | A$150,000 – A$210,000[1] |
| Garage conversion | A$45,000 – A$95,000[2] |
| Programme, DTS pathway | 16 – 28 weeks, contract to occupation[3] |
| *Figures describe metropolitan Adelaide. Most of the SA-specific published data located for this guide comes from a single quote-comparison operator; see the closing section. | |
Published figures for metropolitan Adelaide put an installed studio of 35–45 m² at about A$90,000–A$135,000, a one-bedroom of 45–60 m² at A$120,000–A$165,000 and a two-bedroom of 60–70 m² at A$150,000–A$210,000, with garage conversions at A$45,000–A$95,000.[1][2] They come from a quote comparison operator and are commercial guidance, not independent survey data.
South Australia is the cheapest mainland market for secondary dwellings on the published figures, and the most procedurally demanding. Every project needs both planning consent and building consent — there is no fast pathway that removes an approval — and two numerical thresholds, 70 square metres and 600 square metres, determine whether a project is possible at all. This guide sets out the published ranges and the SA-specific factors behind them.
Terminology comes first §
South Australia does not use "granny flat" in its planning instruments. The Planning and Design Code uses secondary dwelling for detached structures and ancillary accommodation for attached arrangements[3]. The Code itself was introduced in 2021, consolidating the previous suite of Development Plans into a state-wide framework with zone-specific rules, and the PlanSA portal is the definitive source for a property's zone and requirements[4].
This matters for cost research: searching the wrong term returns figures for the wrong product, and a builder quoting "ancillary accommodation" and one quoting a "detached granny flat" may be describing different planning pathways with different fee structures.
What the published sources say §
| Configuration | Total installed | Self-contained basis |
|---|---|---|
| Studio, 35–45 m² | A$90,000 – 135,000[1] | A$95,000 – 140,000[5] |
| One bedroom, 45–60 m² | A$120,000 – 165,000[1] | A$125,000 – 175,000[5] |
| Two bedrooms, 60–70 m² | A$150,000 – 210,000[1] | A$155,000 – 220,000[5] |
| Garage conversion | A$45,000 – 95,000[2] | — |
Across the whole market, total project costs are put at approximately A$80,000 for a compact studio or small prefabricated installation on a flat site through to A$250,000 or more for a fully specified two-bedroom detached secondary dwelling. The building contract itself is put at A$65,000 to A$200,000, with site preparation, service connections and approvals adding A$15,000 to A$40,000 on top[3].
That last figure is the one to carry into a quote comparison. A South Australian building contract price is not a project price, and the difference is not small.
There is no approval-free pathway §
This is the structural difference between South Australia and every other state in this series.
Every form of granny flat addition in South Australia — attached, detached, garage conversion or internal conversion — requires planning consent under the Planning and Design Code followed by building consent assessed against NCC 2022. There is no approval-free pathway in established South Australian residential zones[2].
Compare that with Western Australia, where a design deemed to comply with the R-Codes needs only a building permit, or Victoria, where a compliant small second dwelling can skip the planning permit stage. The South Australian position adds a consent step to every project regardless of how modest it is.
The mitigation is that a proposal meeting the criteria can go through as complying development, which is faster and does not require public consultation, rather than as a full Development Application[4]. Designing to the Deemed-to-Satisfy criteria is therefore worth real money. Those criteria include, in the General Neighbourhood zone, setbacks of typically 0.9 metres from side boundaries for a single-storey wall up to 3.5 metres high and 0.5 metres from the rear boundary; a design that cannot achieve them requires a performance-assessed application instead[1].
On the Deemed-to-Satisfy pathway the typical timeline from signing a building contract to occupation is put at 16 to 28 weeks[3].
Two thresholds decide feasibility §
A 70 square metre maximum gross floor area and a 600 square metre minimum lot size apply to all forms of ancillary accommodation, together with a maximum of two bedrooms and a requirement for a direct-access entrance that does not pass through the primary dwelling[2].
The 600 m² minimum is the one that ends projects. It is a lot-size test rather than a design test, so no amount of budget or design skill resolves it — a smaller allotment simply does not qualify. Confirming lot area against the title before commissioning any design is the first step in a South Australian project.
Private open space competes for the yard §
The Planning and Design Code requires a minimum of 20 square metres of private open space accessible to the ancillary accommodation[1].
On a 600 m² lot that already carries a primary dwelling with its own private open space allocation, that requirement reduces the residual rear yard available for the secondary dwelling footprint[1]. In practice this is a siting constraint disguised as an amenity rule, and it is a common reason a design that satisfies the 70 m² cap still will not fit.
Service connections §
Utility connection is stated separately at A$6,000 to A$15,000 where fully independent services are provided[5].
Whether independent services are needed or wanted is a decision with consequences beyond cost: separately metered services simplify renting the dwelling, while shared services are cheaper to install and complicate the tenancy. Since November 2023 a self-contained South Australian granny flat can be rented to any person, the previous family-only occupancy conditions having been removed by regulation[5] — which makes the metering decision a live one rather than academic.
Items commonly outside the quote §
Demolition, tree removal, stormwater drainage, retaining walls and landscaping are commonly excluded from builders' quotes and can add A$10,000 to A$30,000[6]. A registered surveyor, at A$800 to A$1,500, is needed before any builder can quote accurately, because it confirms boundaries, easements and contour levels[6].
In a state with a hard 600 m² lot threshold and a hard 70 m² floor area cap, a survey is not optional diligence — it is what establishes whether the project qualifies.
Adelaide, along with Hobart and regional areas generally, is put at 5 to 15 per cent below the national average for this type of work[6].
The Adelaide ranges above, including the garage conversion figure and the separately stated site allowance, are in the cost range finder alongside every other state.
What is not covered here §
No independent Australian survey of completed South Australian secondary dwelling costs has been located for this guide.
A caution specific to this page: most of the SA-specific published figures located are produced by a single quote-comparison operator across several of its service pages. Four sources that agree with each other are not four independent confirmations when they share an author and a commercial interest in generating enquiries. The ranges are reproduced because they are the most detailed SA-specific material available, not because they are corroborated.
Regional South Australian costs, council fees, and the tax treatment of a rented secondary dwelling are not covered by the sources compiled here. Rental yield figures circulating in this market are promotional and are not reproduced.
Sent to info@modularlivingaustralia.com.au and handled by a person. See Privacy.
References §
- The Quote Yard — Adelaide backyard secondary dwelling guide, 2026. States total installed metropolitan Adelaide costs of A$90,000 to A$135,000 for a studio of 35–45 m², A$120,000 to A$165,000 for a one-bedroom of 45–60 m², and A$150,000 to A$210,000 for a two-bedroom of 60–70 m². States Deemed-to-Satisfy setbacks in the General Neighbourhood zone are typically 0.9 m from side boundaries for a single-storey wall up to 3.5 m and 0.5 m from the rear boundary, and that the Planning and Design Code requires a minimum of 20 m² of private open space accessible to the ancillary accommodation. thequoteyard.com.au/services/backyard-granny-flat-sa
- The Quote Yard — SA granny flat additions guide, 2026. States garage conversions in metropolitan Adelaide cost A$45,000 to A$95,000 depending on the work required to achieve NCC 2022 habitable room compliance; that every form of granny flat addition in SA requires planning consent followed by building consent, with no approval-free pathway in established South Australian residential zones; and that a 70 m² maximum gross floor area and 600 m² minimum lot size apply to all forms of ancillary accommodation, with a maximum of two bedrooms and a direct-access entrance not requiring passage through the primary dwelling. thequoteyard.com.au/services/granny-flat-additions-sa
- The Quote Yard — Quote comparison operator, 2026. States total South Australian granny flat project costs from approximately A$80,000 for a compact studio or small prefab installation on a flat site to A$250,000 or more for a fully specified two-bedroom detached secondary dwelling; a building contract price of A$65,000 to A$200,000 with site preparation, service connections and approvals adding A$15,000 to A$40,000; and a typical timeline of 16 to 28 weeks from contract to occupation on the Deemed-to-Satisfy pathway. Notes the Planning and Design Code uses "secondary dwelling" for detached structures and "ancillary accommodation" for attached arrangements. thequoteyard.com.au/services/granny-flat-cost-sa
- Your Property Guide — Information site, April 2026. States South Australia introduced a consolidated Planning and Design Code in 2021 replacing the previous Development Plans, that secondary dwellings can be approved as complying development or through a Development Application depending on whether the proposal meets the criteria, and that the PlanSA portal is the definitive source for a property's zone and applicable rules. yourpropertyguide.com.au/guides/granny-flat-guide-sa
- The Quote Yard — Self-contained SA granny flat guide, 2026. States metropolitan Adelaide costs of A$95,000 to A$140,000 for a compact studio, A$125,000 to A$175,000 for a one-bedroom and A$155,000 to A$220,000 for a two-bedroom at or near the 70 m² gross floor area limit, stated to include design fees, slab, construction, kitchen and bathroom fit-out and planning and building consent, with utility connection of A$6,000 to A$15,000 to be added for fully independent services. States a self-contained SA granny flat can be rented to any person as of November 2023, the previous family-only occupancy conditions having been removed by regulation. thequoteyard.com.au/services/self-contained-granny-flat-sa
- TradieVerify — Commercial licence-checking service, February 2026. States Adelaide, Hobart and regional areas are generally 5 to 15 per cent cheaper than the national average; that demolition, tree removal, stormwater drainage, retaining walls and landscaping are commonly excluded from quotes and can add A$10,000 to A$30,000; and that a registered surveyor costs A$800 to A$1,500 and is needed before any builder can quote accurately. tradieverify.com.au/guides/how-much-does-a-granny-flat-cost-in-australia/
Figures are as published by the sources above at their respective dates and are paraphrased summaries, not verbatim reproductions. Verify current pricing and rules directly with builders, lenders and planning authorities.