What our analysis shows
Analysis by Granny Flat Numbers, data as of 23 October 2026
- A standard 60 m² two-bedroom flat comes to $187,000 turnkey in Adelaide ($164,500–$209,500), the lowest of the capital cities in our model, and $159,500 in regional SA. The full 70 m²: $212,500.
- Eastern Adelaide gives the best payback in the state, 9.5 years, on a median two-bedroom house rent of $628. Northern Adelaide is the weakest metro region at 12.0 years.
- Land tax is where SA differs. RevenueSA gives a full home exemption only if at least 75% of the floor area of all buildings, sheds and garages included, is the owner's home. By our reading, a rented flat over a quarter of the total costs you part of the exemption. A 60 m² flat needs at least 180 m² of house, garage and sheds beside it; a 70 m² flat, 210 m².
- SA's one-bedroom "house" bond median is about $290 in every Adelaide region, against $474 for a one-bedroom flat. That category seems to hold rooms and old cottages rather than new granny flats, so we used flat rents for one bedroom.
Fastest payback in South Australia, 60 m² two-bedroom flat
- Eastern Adelaide9.5 years
- Western Adelaide10.2 years
- Adelaide metro10.6 years
- Southern Adelaide10.9 years
- Northern Adelaide12.0 years
- Regional SA13.7 years
After agent fees, insurance, maintenance and tax at 30%, no loan. Rents: SA Housing Trust private rental report, new bonds April–June 2026.
What you pay for
| Line, 60 m² in Adelaide | Cost |
|---|---|
| Construction | $153,000 |
| Site preparation (flat, easy access) | $12,000 |
| Sewer, water, power and stormwater connections | $10,000 |
| Design, engineering and BASIX/energy report | $8,000 |
| Approval: Deemed-to-satisfy planning and building consent | $4,000 |
| Total | $187,000 |
| Size | Budget | Standard | Premium | Standard, regional |
|---|---|---|---|---|
| Studio, 35 m² | $113,500 | $131,500 | $160,500 | $114,000 |
| 1 bed, 45 m² | $130,500 | $152,000 | $187,500 | $131,000 |
| 2 bed, 60 m² | $159,000 | $187,000 | $233,000 | $159,500 |
| 2 bed, 70 m² | $180,000 | $212,500 | $266,000 | $180,500 |
Rent and payback by region
| Area | 1-bed rent | 2-bed rent | 60 m² build | Net yield | Payback |
|---|---|---|---|---|---|
| Eastern Adelaide | $495 | $628 | $187,000 | 14.2% | 9.5 yrs |
| Western Adelaide | $390 | $585 | $187,000 | 13.1% | 10.2 yrs |
| Adelaide metro | $474 | $563 | $187,000 | 12.6% | 10.6 yrs |
| Southern Adelaide | $398 | $550 | $187,000 | 12.3% | 10.9 yrs |
| Northern Adelaide | $360 | $500 | $187,000 | 11.0% | 12.0 yrs |
| Regional SA | $260 | $380 | $159,500 | 9.5% | 13.7 yrs |
The two-bedroom figures are house rents. They run $40 a week above two-bedroom flats across Adelaide, which suits a detached granny flat with its own yard space. The one-bedroom figures are flat rents for the reason given above.
Rent data: SA private rental report data, April–June 2026.
The 75% floor-area test
RevenueSA's land tax guide sets three conditions for the full home exemption. The third: at least 75% of the total floor area of all buildings on the land, including sheds and garages, is used as the owner's principal place of residence. A tenanted granny flat is not part of your residence, so its floor area counts against you. Where 25–75% of the floor area is used for a business or commercial purpose, a partial exemption applies on a sliding scale.
| Granny flat | House, garage and sheds | Flat's share | Exemption |
|---|---|---|---|
| 45 m² | 150 m² | 23% | Full |
| 60 m² | 150 m² | 29% | Partial: 75% of value exempt |
| 60 m² | 200 m² | 23% | Full |
| 70 m² | 180 m² | 28% | Partial: 75% of value exempt |
| 70 m² | 240 m² | 23% | Full |
Partial exemption matters only if your land's taxable value is above the land tax threshold, and the guide frames the scale around business use. How RevenueSA treats a family member living rent-free is not addressed in the guide. If your flat is near the 25% line, ask RevenueSA before you build. Counting the garage and garden shed in the total is the easiest way to stay under it. The full rule is in RevenueSA's guide.
Approval
A design that meets the deemed-to-satisfy standards gets planning consent in five business days after the documents are checked; our model allows $4,000 for planning and building consent together. If the flat exceeds 70 m² or two bedrooms, or misses a standard, it is performance assessed: 20 business days without referrals, up to 70 if neighbours are notified. The flat must share the main dwelling's private open space; it cannot have a fenced-off yard of its own.
SA-only costs
- SA Water augmentation charge. Payable in Greater Adelaide if the flat gets its own water or sewer connection; sharing the main house's connection avoids it.
- Off-sewer blocks. In the Adelaide Hills and rural areas an aerobic wastewater system costs $8,000–14,000 plus an annual service contract.
This week's worked example
Week of 19 October 2026. A new example, rule and owner report every Monday.
A 60 m² two-bedroom flat with a premium finish on a steep block, services 30 m from the house, in Adelaide metro: our model puts it at $272,000 turnkey ($239,500–$305,000), or $4,540 per m². At the area's median 2-bedroom bond rent of $563 a week it would return 8.4% net and pay back in 15.3 years after tax.
Rule check: South Australia's ancillary accommodation can be fully self-contained, up to 70 m² and two bedrooms; the change started on an interim basis on 29 February 2024 and was adopted on 18 November 2024.
From an owner (Australia, 2018): Renters noted that older flats tend to include utilities in the rent while newer ones are separately metered.
Questions people ask
How much does a granny flat cost in Adelaide?
About $187,000 turnkey for a standard 60 m² two-bedroom flat; $159,000 with budget finishes and $212,500 for the 70 m² maximum.
Can a granny flat have its own kitchen in SA?
Yes. Since the 2024 change to the Planning and Design Code, ancillary accommodation can have its own kitchen, bathroom and laundry, up to 70 m² and two bedrooms.
Does a granny flat affect land tax in SA?
It can. A full principal place of residence exemption needs at least 75% of the floor area of all buildings to be used as the owner's home. If a rented flat takes more than a quarter, only a partial exemption may apply.
Can I rent out a granny flat in SA?
Yes, to anyone. The bond must be lodged with Consumer and Business Services within 2 weeks.