“Granny flat” is a familiar marketing term, but it is not a single Australia-wide approval category. Depending on the jurisdiction, the legal description may be secondary dwelling, small second home, ancillary dwelling or ancillary accommodation. That distinction matters because the applicable definition controls where the dwelling may be built, how large it may be, whether it needs planning approval and whether it must remain associated with the principal home.
A reliable answer therefore has three layers: state or territory planning law, the local planning scheme and building regulation. Property-specific constraints then sit across those layers. A rule that appears favourable at state level does not remove a heritage control, flood requirement, easement, bushfire standard, title restriction or need for building approval.
Jurisdiction and currency note — 11 September 2026: This article is general Australian information, not legal, planning, building-certification, engineering, tax or financial advice. Rules, maps, adopted National Construction Code provisions and council practices change. Verify the current controls for the legal lot with the relevant state or territory authority, council, building surveyor or certifier and appropriately qualified advisers before relying on any statement.
Why state and council answers can differ
Australian states and territories establish planning systems through legislation and statewide instruments. Councils administer local schemes, zones, overlays and assessment processes within those systems. Building legislation and the adopted edition of the National Construction Code deal with technical construction matters. Planning permission and building approval are related, but neither automatically substitutes for the other.
This creates several possible pathways:
- development may be exempt from a planning permit but still require a building permit;
- a fast-track or complying pathway may be available only if every stated standard is satisfied;
- a council-assessed application may be required because of a mapped constraint or design departure;
- additional plumbing, drainage, driveway, asset-protection or utility consents may be separate;
- rental use may trigger residential-tenancy, safety, insurance and tax obligations beyond development approval.
Ask each authority to identify the instrument, clause and version supporting its answer. “Council said it should be fine” is not equivalent to a written planning-property report, approval or certificate.
A state-by-state orientation
This overview is a navigation aid, not a substitute for the current instruments.
New South Wales
NSW uses the term secondary dwelling. The NSW planning guidance explains the statewide framework, while the legally operative requirements sit in instruments including the State Environmental Planning Policy (Housing) 2021. A qualifying proposal may use complying development; otherwise a development application may be necessary. Do not assume the well-known 60 m² figure settles the whole question: zoning, lot area, setbacks, landscaped area, access, mapped exclusions and the relationship to the principal dwelling also matter.
Victoria
Victoria generally describes the product as a small second home. The official Small second homes guidance explains the framework for a self-contained dwelling of no more than 60 m² on the same lot as an existing home. Many proposals do not require a planning permit, but special controls and overlays can change that result. A building permit is still required, and the home cannot simply be treated as a separately saleable lot.
Queensland
Queensland’s secondary dwelling guidance confirms that these dwellings can provide housing for people other than relatives. However, local government planning schemes remain decisive for matters such as accepted development, maximum scale, siting and parking. Building approval remains a separate question. A Brisbane assumption should not be carried into Moreton Bay, the Gold Coast or a regional council without checking that council’s scheme.
Western Australia
WA uses ancillary dwelling in the Residential Design Codes. State reforms expanded opportunities, including removal of the former minimum lot-size requirement, but the proposal must still satisfy the relevant deemed-to-comply provisions to obtain a planning exemption. The official ancillary dwelling information sheet is a useful starting point. Local planning policies, R-Code requirements and a building permit must still be addressed.
South Australia
South Australian proposals are tested through the statewide Planning and Design Code, commonly under provisions for ancillary accommodation or residential development. The online Code should be searched against the actual address because zone, subzone, overlay and technical requirements combine to determine the assessment pathway. A generic statewide summary cannot establish whether a particular design is deemed-to-satisfy or needs a more detailed assessment.
Tasmania, the ACT and the Northern Territory
These jurisdictions also distinguish planning permission from building approval and use their own definitions, codes and application systems. Because reforms and scheme amendments can change terminology or pathways, begin with the relevant territory or state planning portal, then identify the current local scheme or Territory Plan provision. Obtain written property-specific advice where the outcome affects purchase, finance or a building contract.
The practical approval sequence
- Define the use. Record whether the dwelling is for family, long-term rental, accessible accommodation or another lawful purpose. Do not assume short-stay use is treated the same way.
- Identify the legal land. Obtain a current title, deposited or survey plan and any registered dealings. Confirm lot boundaries rather than relying on fences.
- Name the planning category. Ask which statutory definition applies and whether the existing house is lawfully established.
- Generate current planning information. Check zoning, overlays, hazard mapping, heritage, vegetation, minimum lot rules and local policies.
- Test the preferred pathway. Create a clause-by-clause matrix for exempt, complying, accepted or permit-free development. One failed criterion can move the project to another pathway.
- Commission site investigations. Survey levels and improvements; locate services, easements, trees, drainage and access constraints.
- Confirm building and ancillary approvals. Identify the building surveyor or certifier, plumbing authority, water authority, council asset requirements and any energy assessment.
- Lodge coordinated documents. Plans, reports and specifications must describe the same building.
- Preserve approvals and inspections. Keep stamped plans, conditions, certificates, inspection records and occupation evidence.
Evidence checklist
Before treating an approval pathway as established, hold:
- current title and registered plan;
- recent feature and level survey;
- dated planning-property report and relevant map extracts;
- copies or links to the exact current statutory clauses;
- written council, planner or certifier advice identifying assumptions;
- concept plans with dimensions, setbacks, floor area and site coverage;
- sewer, stormwater, water, electricity and telecommunications information;
- bushfire, flood, contamination, heritage, biodiversity or arborist advice where relevant;
- approval-pathway matrix showing pass, fail and unresolved criteria;
- fee, contribution and consultant allowances;
- building classification and applicable NCC edition confirmed by the certifier;
- final approvals, endorsed plans, conditions and inspection schedule.
Warning signs
- A supplier says “no council approval needed” without naming the legal exemption.
- Advice relies only on a neighbouring property or an old council web page.
- The quoted floor area excludes spaces that the applicable definition includes.
- A planning exemption is presented as exemption from all building, plumbing or asset approvals.
- The concept is drawn before boundaries, easements and sewer infrastructure are located.
- Rental income is promised without checking lawful occupation, tenancy rules, insurance and tax.
- Plans change after approval but nobody assesses whether an amendment is required.
- A deposit or non-refundable design fee is requested before basic property constraints are checked.
Questions to ask
Ask the council or planner: What is the statutory land-use definition? Which zone, overlays and local provisions apply? Is the pathway exempt, complying, accepted, code-assessable or permit-assessed? Which property constraints remove the simpler pathway?
Ask the certifier or building surveyor: Which NCC edition and state variations apply? What building classification is proposed? What fire separation, access, energy, stormwater and inspection requirements must be documented?
Ask the designer and builder: Which measurements establish floor area, site coverage and setbacks? What assumptions remain unverified? Are authority fees, service upgrades, retaining, access and approval conditions included? Who updates the drawings if an authority requires changes?
Source hierarchy
Use evidence in this order: current legislation and statutory planning instruments; official state or territory planning portals; address-specific council scheme information and written determinations; approval documents and certified plans; advice from appropriately registered professionals; then general guides. Supplier articles and social posts can generate questions, but should not decide legal compliance.
AMESCORP disclosure and limits
AMESCORP has a commercial interest in helping homeowners investigate, plan and potentially procure granny-flat projects. Its content may support enquiries about AMESCORP services. That interest does not replace independent advice or government approval. AMESCORP does not control councils, certifiers, utilities, lenders, insurers or market outcomes.
No approval, timeframe, price, buildability, rental income, valuation, tax result or investment return is guaranteed. A sound decision is one supported by current property-specific evidence, an identified statutory pathway and coordinated professional advice.
Reviewed official sources
These are the first-party and authoritative references reviewed for this article.
- Secondary dwellings — NSW Department of Planning, Housing and Infrastructure; accessed 2026-09-11.
- State Environmental Planning Policy (Housing) 2021 — NSW legislation; accessed 2026-09-11.
- Small second homes — Victorian Department of Transport and Planning; accessed 2026-09-11.
- Secondary dwellings providing housing solutions — Queensland Government; accessed 2026-09-11.
- Residential Design Codes — Western Australian Government; accessed 2026-09-11.
- Ancillary dwelling information sheet — Granny Flats — Western Australian Planning Commission; accessed 2026-09-11.
- Planning and Design Code — PlanSA; accessed 2026-09-11.
- National Construction Code — Australian Building Codes Board; accessed 2026-09-11.