A granny flat is a smaller, self-contained dwelling located on the same property as a primary home. It commonly includes a living area, bedroom or sleeping space, bathroom and kitchen, although the exact definition and permitted use depend on the state, council and approval pathway.
People build granny flats for many reasons: accommodating family, creating a more independent space for an older relative, making room for guests, or adding a flexible dwelling that may support a future change in household needs. It is important to plan for the site and the rules first, rather than starting with a particular floor plan.
What is it called in each Australian state?
“Granny flat” is the common term; the formal planning classification varies by jurisdiction. These are the terms to use when checking state legislation, planning schemes and council guidance.
| State or territory | Common formal term | Planning definition / note |
|---|---|---|
| Victoria | Small second home / dwelling | A self-contained second dwelling of 60 m² or less on the same lot as an existing home. “Dependent person’s unit” remains relevant to transitional arrangements and limited applications. |
| New South Wales | Secondary dwelling | A self-contained dwelling within, attached to or separate from the principal dwelling on the same site. Permitted in R1–R5 zones and potentially elsewhere under the applicable local environmental plan, subject to development standards and consent pathway. |
| Queensland | Secondary dwelling | A dwelling used in conjunction with, and subordinate to, another dwelling on the same lot; distinct from a dual occupancy. |
| South Australia | Ancillary accommodation | Accommodation ancillary to a principal dwelling, assessed under the South Australian Planning and Design Code and relevant development standards. |
| Western Australia | Ancillary dwelling | A self-contained dwelling on the same lot as a single house, attached to, integrated with or detached from that house. |
| Tasmania | Secondary residence | An additional self-contained residence appurtenant to a single dwelling, sharing specified access, parking and service connections. |
| Australian Capital Territory | Secondary residence | A second dwelling on a block that is subordinate to the principal dwelling and assessed under the Territory Plan. |
| Northern Territory | Independent unit / dwelling – independent | The NT Planning Scheme classification for an independent unit commonly referred to as a granny flat. |
These are useful search terms, not a substitute for the current planning scheme. Councils, zones, overlays and site conditions can change the approval pathway.
Granny flat, studio or cabin?
These terms are often used interchangeably in marketing, but they can describe different levels of self-containment and different approval requirements.
| Building type | Typical characteristics | Questions to check |
|---|---|---|
| Granny flat / secondary dwelling | Designed as a separate dwelling, often with a kitchen, bathroom, living area and sleeping space. | Can the site support a second dwelling? What occupancy and planning rules apply? |
| Garden studio | A flexible room for work, hobbies, study or relaxation; it may not be set up as a separate residence. | Are cooking, plumbing, sleeping or rental use allowed under the intended approval? |
| Backyard cabin | A broad description that can cover anything from a simple retreat to a fully fitted small dwelling. | What will the building be used for, and how does the council classify that use? |
Common reasons to build one
- A private space for parents, adult children or visiting family.
- A quieter home office, studio or creative room separated from the main house.
- More adaptable living space as household needs change.
- A potential rental or dual-occupancy use, where local rules and approvals allow it.
What to check before designing
- Local rules: identify the council, zoning, overlays and whether planning or building approval is required. A rule that applies in one state or council may not apply elsewhere.
- Site constraints: measure the block and locate boundaries, easements, sewer lines, stormwater, trees, slopes, access paths and existing structures.
- Services: consider electricity, water, drainage, waste-water connections, internet and how construction access will work.
- Daylight and privacy: think about window placement, overlooking, setbacks, ventilation, orientation and the relationship to neighbours.
- Future use: decide whether the building is for family, guests, work, study or independent living. The intended use affects the brief and may affect approvals.
Approvals are location-specific
There is no single Australia-wide granny-flat approval rule. State legislation, council planning schemes, building regulations, site constraints and the proposed use all matter. Victoria now generally uses the small second home or small second dwelling terminology; dependent person’s units remain relevant to transitional and limited cases.
Start with the relevant council and confirm the pathway with a registered building surveyor, designer, planner or other appropriately qualified professional. Treat online summaries and builder estimates as preliminary information until the site has been assessed.
How much does a granny flat cost?
The total budget is shaped by more than the building itself. Allow for design, surveys, engineering, approvals, site preparation, connections, drainage, access, landscaping and contingencies. A simple studio and a fully self-contained two-bedroom dwelling can have very different scopes even when they occupy a similar footprint.
Ask for an itemised estimate and clarify what is included, what is provisional, how variations are handled and whether external works are excluded. Our cost guide covers the main cost drivers in more detail.
A simple first brief
Before speaking with a designer or builder, write down who will use the space, the rooms you need, the preferred level of independence, the approximate budget, the access constraints and any important timing requirements. Bring a basic site sketch and photographs if you have them.