From the street, a backyard studio and a granny flat can look the same. NSW planning law treats them very differently, and the difference comes down to one question: can the building work as a separate home?
What a detached studio is
The Exempt and Complying Development Codes SEPP defines a detached studio as a habitable building used for purposes that support the main house, such as a home office, art studio, entertainment area or guest room. To fit the definition, the studio must:
- be built in conjunction with the house and sit on the same lot
- stand apart from the house rather than attach to it
- never serve as a second, independent home
- have no cooking facilities
In short, a studio is extra space for the household that lives in the main house. It is not a second home.
What a granny flat is
A granny flat, or secondary dwelling, is a self-contained home with its own kitchen, bathroom and living area. Someone can live in it independently, including a tenant. It is approved under the State Environmental Planning Policy (Housing) 2021, which has its own set of standards.
Size and lot limits side by side
- Studio (Housing Code): a gross floor area cap of 20 m² where the lot is 200 to 350 m², rising to 36 m² where the lot is larger than 350 m². Other codes, such as the Rural Housing Code, use different figures.
- Granny flat: up to 60 m² of floor area (or more if your LEP allows it), and the lot must be 450 m² or more to use complying development.
The NSW Government asked for feedback in May 2026 on letting studios take up to 10% more floor area. That was a proposal when this article was written, so check the current code before you design to a bigger number.
Both are habitable buildings
Because people use a studio as a room, the National Construction Code (NCC) treats it as part of the Class 1 house, much like a sleepout. It is not a Class 10 shed. That means it needs the same basics as any habitable room: adequate ceiling height, natural light, ventilation, damp protection and suitable insulation. A granny flat goes further. It is a separate Class 1a dwelling with its own smoke alarms, wet areas and BASIX certificate.
The reverse matters too. A garden shed approved as a non-habitable Class 10 building can't be used as an office or bedroom without a fresh approval. Our guide on What you use an outbuilding for changes how it is approved explains why.
Choosing, and changing your mind later
If there is any chance the space will be rented, or that a relative will live there independently, approve it as a granny flat from the start. Turning a studio into a granny flat later means a new approval that must meet the secondary dwelling rules in full, including the lot size threshold for a CDC. Adding a kitchen to a studio without approval can lead to council orders and problems when you sell.
If a studio is the right fit, our backyard studios page explains how we certify them. If you want a self-contained home, see granny flats. Either way, a plan assessment confirms which rules your design must meet before you lodge.
Local help across NSW
CertifiBuild certifies Class 1 and Class 10 work in 39 council areas. Local rules on these council pages are a good place to start: Kiama Municipal Council, Willoughby City Council, Wollondilly Shire Council, Randwick City Council, Georges River Council, Penrith City Council.
Suburb pages with local planning notes: Minnamurra, North Willoughby, Oakdale, South Coogee, South Hurstville, St Clair, Strathfield, Strathfield South, Summer Hill, Tahmoor. You can also browse every service area.
Sources
- State Environmental Planning Policy (Exempt and Complying Development Codes) 2008, NSW Legislation
- Variations and changes to complying development, Explanation of Intended Effect (May 2026), NSW Planning Portal
- Building classification rules (NCC 2022 Vol. 2, Part A6), ABCB
- Secondary dwellings guidance, NSW Department of Planning