Granny Flat Rules in Australia: What Changes by State

Granny flat rules in Australia are set state by state, not nationally. The maximum floor area runs from 60 square metres in New South Wales, Victoria and Tasmania to 70 in South Australia and Western Australia, 75 in the Northern Territory, 80 across most South East Queensland councils and 90 in the ACT. A building permit is always required.

That paragraph explains most of the confusion. Two neighbours either side of a state border can build the same unit and face different paperwork. Below is what differs, where the traps are, and what a factory-built unit has to carry before a certifier will look at it.

What counts as a granny flat under Australian planning law?

A granny flat is a self-contained secondary dwelling on the same title as an existing house. It shares that lot’s services, it is subordinate to the main house, and it cannot be sold off separately. Nobody in the planning system calls it a granny flat.

Every jurisdiction uses its own legal term, and that is the single biggest reason the rules look inconsistent when you search for them:

• NSW and Queensland: secondary dwelling.
• Victoria: small second dwelling, a term that only entered the Victoria Planning Provisions at the end of 2023.
• South Australia: ancillary accommodation.
• Western Australia: ancillary dwelling.
• Tasmania and the ACT: secondary residence.
• Northern Territory: dwelling-independent, or independent unit in plain language.

If your council’s planning scheme returns nothing for “granny flat”, search the term your state actually uses.

What are the granny flat rules in Australia, state by state?

Floor area caps, lot size thresholds and approval pathways all differ. This table sets out the current position in each jurisdiction and the condition that most often catches people out.

Two patterns matter. Caps have moved upward almost everywhere since 2023, and four jurisdictions have scrapped a minimum lot or block size in the last three years. The second change is the bigger one in practice: it puts previously ineligible suburban blocks back in play.

Why is the planning permit not the same as the building permit?

Removing the planning permit does not remove the building permit, and this is where most granny flat projects come unstuck. Victoria and Western Australia both dropped the planning approval step for compliant small second dwellings, and both explicitly kept the building permit. The Western Australian Planning Commission puts it in a boxed note on its own information sheet.

A building permit means an Australian building surveyor or certifier assesses your unit on your site. What they need is site-specific engineering, not a generic factory drawing:

• Soil classification to AS 2870. A geotechnical report classifies your ground from Class A (stable sand or rock) through to Class H (highly reactive clay) and Class P (problem sites, soft soil or uncontrolled fill). The footing design follows from that.
• Wind actions to AS/NZS 1170.2. A unit designed for a suburban Melbourne block is not designed for a cyclonic north Queensland site. Tie-down and bracing change.
• Bushfire attack level where a bushfire overlay applies, plus any flood or heritage overlay that survives the planning exemption.

Structural design certified by an Australian registered engineer for your site’s wind and soil classification. We supply the compliance documentation to your building certifier or surveyor, who issues the approval. Compliance is collaborative and site-dependent, and the final decision always rests with the certifier or council.

Can you rent a granny flat out to anyone?

In most of the country, yes, and the most recent change was in Queensland. The Planning (Secondary Dwellings) Amendment Regulation 2022 commenced on 26 September 2022 and removed the rule that a secondary dwelling had to be occupied by a member of the same household as the main house. Before that date a Queensland granny flat was effectively family-only. Western Australia states plainly that anyone can live in an ancillary dwelling, and NSW, Victoria and South Australia all permit renting.

What you generally cannot do is subdivide. In New South Wales the rule is explicit: a lot with a secondary dwelling on it cannot be subdivided. If separate titles are the goal, you are looking at a dual occupancy.

Does a tiny home on wheels count as a granny flat?

Usually not, and treating one as the other is an expensive mistake. A granny flat is a fixed building assessed under the building code. A dwelling that stays on its chassis is generally regulated as a caravan or moveable dwelling under separate rules, with occupancy limits that vary by council.

The trade-off is real. A tiny home on wheels can often go in without a building permit but may be limited in how long it can be lived in. A fixed secondary dwelling needs the permit and gives you a permanent, lawful, rentable dwelling. Decide which outcome you want before you choose the structure. We set that comparison out in full in tiny house on wheels vs a fixed tiny home in Australia.

What is changing in 2026?

Tasmania is the one to watch. State Planning Provisions amendment 01/2026 proposes lifting the allowable gross floor area for a secondary residence from 60 m² to 90 m² and clarifying the servicing requirements. Representations to the Tasmanian Planning Commission closed on 22 July 2026 and the statutory process runs for months after that, so the current 60 m² figure still applies until the amendment takes effect. Design to the rule in force on the day your permit is lodged, not the rule you expect later.

What does a modular granny flat need to get through?

Floor area caps are the easy part for a factory-built unit. Most modular secondary dwellings land well under every state cap, so the size question usually resolves itself and the real work goes into engineering and documentation. If a shipping container is the shell you had in mind, the ceiling height arithmetic is unforgiving, and what a container home or granny flat conversion really takes works through it.

Three units from our Australian granny flat range make that concrete:

• The TH95 capsule home at 31 m², with a full kitchen and a panoramic balcony, sits under even the tightest 60 m² cap with room to spare.
• The TH115 designer pod is a one bedroom layout with a real wall between the bed and the living space, which matters when the unit will be tenanted rather than used by family.
• The EX20 expandable home ships as a 6 metre unit and opens both walls out to a near square 38 m², useful where crane access is the constraint rather than floor area.

Every unit is built to order to NCC Class 1a requirements, compliance documentation supplied. Timing runs to typical factory production of 20-30 days and typical delivery of 20-30 days, around 40-60 days in total from order to site. Site works, services and the certifier’s assessment run on your local timeline alongside that, which is why the approval work should start the day you order.

If your block, overlay or intended use does not fit a standard layout, that is what our custom project process is for. For a broader look at secondary dwellings, see our granny flat guide.

Frequently asked questions

Which state has the most generous granny flat size limit?

The ACT, at 90 m² for a secondary residence in RZ1, with Brisbane next at 80 m². Tasmania has an amendment in progress that would also take it to 90 m². NSW and Victoria are the tightest at 60 m².

Do I need a planning permit for a granny flat in Victoria?

In most residential zones, no. Amendment VC253 exempted small second dwellings of 60 m² or less on lots over 300 m² from needing a planning permit. Overlays such as bushfire or flood, and title covenants, can still trigger one. A building permit is required either way.

Can a granny flat be sold separately from the main house?

No. A secondary dwelling sits on the same title as the principal dwelling and is subordinate to it. New South Wales states directly that a lot containing a secondary dwelling cannot be subdivided. Separate titles require a dual occupancy or a subdivision approval.

Does the factory drawing satisfy the certifier?

No. A factory drawing shows what the unit is. The certifier needs evidence that this unit, on your soil class and in your wind region, meets the code. That comes from an Australian registered engineer working to your site report.

General information about Australian planning and building requirements, not planning, building or legal advice. Requirements change and vary by council. Confirm your position with your council and your certifier before committing to a design.