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Granny flat or tiny home — which is right for you?
| Legal category | Granny flat: secondary dwelling. Tiny home: varies by construction[1][2] |
|---|---|
| Needs an existing dwelling on the lot? | Granny flat: yes, always. Tiny home: only if on wheels and treated as ancillary[1][2] |
| Typical size cap | Granny flat: 60 m² (NSW/TAS), up to 90 m² (ACT)[3] |
| Can it be sold separately? | Granny flat: no, in NSW[1] |
| Council approval | Required for both, by different pathways[1][2] |
| Cost (NSW, professional build) | Granny flat: ≈ A$140,000–$260,000[4]. Tiny home: ≈ A$85,000–$164,000[5] |
| *A tiny home fixed to the ground is assessed like a granny flat in most states, not like a caravan. | |
Both are compact, and both often get pitched at the same buyer — someone wanting a smaller, cheaper second dwelling. But they answer different questions and sit in different legal categories, and confusing them is the single most common mistake buyers make when comparing the two.
The distinction that actually matters §
A granny flat — formally a secondary dwelling — is always a fixed, permanent structure on the same lot as an existing principal home, self-contained with its own kitchen, bathroom and entrance.[1] It cannot exist on vacant land as the only dwelling: the whole legal category depends on there being a main house already there.
A tiny home is defined by size rather than legal relationship to another dwelling — typically 15–55 m² — and can be either fixed to the ground or built on wheels.[6] A fixed tiny home used as a permanent residence is generally assessed the same way as any other house or secondary dwelling, regardless of its small size. A wheeled tiny home is a different matter again: it is usually treated as a caravan-type structure, and whether it needs approval depends heavily on whether it is genuinely mobile, unconnected to services, and used ancillary to an existing dwelling.[2]
| Granny flat | Fixed tiny home | Tiny home on wheels | |
|---|---|---|---|
| Needs existing dwelling on lot | Always[1] | Only if used as ancillary accommodation | Only if used as ancillary accommodation[2] |
| Can stand alone on vacant land | No[1] | Yes, as a primary dwelling | Generally no, treated as caravan/moveable housing[2] |
| Building approval | Yes, always[1] | Yes, same pathway as a house | Only if building work is involved (fixed to ground, hard-plumbed)[2] |
| Typical size cap | 60 m² (NSW/TAS); 90 m² (ACT)[3] | No specific cap — assessed like any house | Road limits apply: ≈4.3m high, 2.5m wide, ≈9m long[6] |
Cost comparison §
Published NSW guidance puts a professionally built one-bedroom granny flat (35–40 m²) at roughly A$140,000–$180,000, and a two-bedroom (50–60 m²) at A$180,000–$260,000.[4] Professionally built tiny homes run somewhat lower, roughly A$85,000–$160,000 or more for a custom build.[5] Both figures are builder-published commercial guidance rather than independent survey data, and both scale heavily with size, finish and location — see site works and site costs for what typically sits outside these headline figures.
Approval pathway is where they genuinely diverge §
A granny flat's approval pathway is well-worn in every state, usually via a fast-track Complying Development-style certificate for compliant designs, or a full development application where it doesn't qualify. See this site's state-by-state granny flat guides for the specific rules in your state.
A tiny home's pathway depends entirely on which of the three rows in the table above it falls into — and the difference between them often comes down to details that seem trivial at the time: whether a deck is attached, whether the plumbing is hard-connected or uses flexible caravan-style hookups, whether the unit sits on piers or genuinely remains mobile. See on wheels or fixed foundation for how that choice cascades into approval, finance and resale outcomes.
Which one fits your situation §
- You already have a house on the block and want a self-contained space for family, rental income, or a home office — a granny flat is the well-established, better-understood pathway in every state.
- You're on vacant land, or want the option to move the dwelling later — a tiny home (fixed or on wheels) is the more natural fit, though a wheeled unit intended for long-term occupation still needs to clear the specific state tests in the table above.
- You want maximum rental flexibility — check your state's current rules on renting a granny flat to non-family tenants, since these have changed in several states; see can you rent out a granny flat.
- Budget is the primary driver — a tiny home generally starts lower, but a granny flat's larger size and unambiguous approval pathway can make it the lower-friction option once approval delays and holding costs are factored in.
Related guides §
- What is a granny flat?
- On wheels or fixed foundation
- Can you live in a tiny house full time in Australia?
- Glossary
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References §
- Buildana — NSW granny flat guide — Secondary dwellings are self-contained, sit on the same lot as the principal home, and cannot be sold separately from the main title; governed by the State Environmental Planning Policy (Housing) 2021. buildana.com.au/guides/granny-flat-nsw
- PlanSA (Government of South Australia) — Ancillary accommodation, caravans and moveable housing FAQ — A tiny house on wheels is most commonly a dwelling but can also be used for ancillary accommodation. The occupation of a tiny house on wheels will require development approval unless it is used for ancillary accommodation and does not involve building work, such as permanent connection to the ground or services. plan.sa.gov.au/__data/assets/pdf_file/0018/1344132/Ancillary-accommodation-caravans-and-moveable-housing-FAQ.pdf
- ACT Government — Territory Plan 2023, Residential Zones Policy (NI2023-540) — The maximum dwelling size of a secondary residence in the ACT is 90 m², larger than the 60 m² cap that applies in NSW and Tasmania. legislation.act.gov.au/DownloadFile/ni/2023-540/copy/169931/PDF/2023-540.PDF
- Buildana — Granny flat rules NSW 2026 — One-bedroom builds of 35–40 m² around A$140,000–$180,000; two-bedroom builds of 50–60 m² around A$180,000–$260,000; premium 60 m² builds to A$300,000. Builder-published guidance. buildana.com.au/insights/granny-flat-rules-nsw-2026
- LJM Tiny Homes / Aussie Tiny Houses — 2026 tiny home cost guides — Professionally built tiny homes typically cost roughly A$85,000 to A$160,000-plus for custom builds, with turnkey ranges around A$101,900–$163,900. Builder-published commercial guidance. ljmtinyhomes.com.au/how-much-does-a-tiny-home-cost-in-australia/
- Wright Choice Homes — Wheeled dwellings must respect road limits of about 4.3 m height, 2.5 m width and roughly 9 m length to travel without special permits; Australian tiny homes are typically 15–55 m². wrightchoicehomes.com.au/blog/how-much-do-modular-homes-cost/
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.