In NSW a granny flat is a secondary dwelling under State Environmental Planning Policy (Housing) 2021. On residential zoned land it is permitted with consent, capped at 60 square metres of floor area (or a larger figure if the council’s LEP allows one), must stay on the same title as the main house, and can be approved either as complying development through a private certifier or through a development application to council. Which pathway suits you depends mostly on lot size, site constraints and whether the design fits the complying development standards.
Key takeaways
- The Housing SEPP makes secondary dwellings permissible in the R1 to R5 residential zones across NSW, so a council cannot prohibit them outright on that land.
- The maximum floor area is 60 square metres, or the larger area a council LEP specifically allows, and the granny flat cannot be subdivided from the principal dwelling.
- Complying development is generally available on residential lots of at least 450 square metres where the design meets the Codes SEPP standards, with a certifier issuing the CDC.
- A DA is the fallback for smaller or constrained lots, heritage items, some flood affected land and designs that need a variation.
- The Housing SEPP does not require an extra car space for a granny flat, but BASIX, bushfire and stormwater requirements still apply.
What the Housing SEPP actually says about secondary dwellings
Before 2021 the granny flat rules sat in the Affordable Rental Housing SEPP. They now live in Chapter 3 of the Housing SEPP secondary dwelling provisions. The core rules are short:
- A secondary dwelling is a self contained dwelling on the same lot as a principal dwelling. It can be within, attached to or detached from the main house.
- Only one principal dwelling and one secondary dwelling are allowed on the lot. You cannot pair a granny flat with a dual occupancy.
- The lot cannot be subdivided to separate the two dwellings. This applies to Torrens, strata and community title.
- No additional off street parking is required by the SEPP for the granny flat.
- The total floor area of the secondary dwelling must not exceed 60 square metres, or a greater area if the LEP permits one for secondary dwellings.
Because the SEPP overrides the LEP where they conflict, a council DCP cannot impose a smaller floor area, ban detached granny flats or require two car spaces. Councils can and do set controls for setbacks, private open space, landscaping and privacy, and a DA is assessed against those controls under section 4.15 of the Environmental Planning and Assessment Act 1979.
The 60 square metre limit and how it is measured
The 60 square metre cap trips up more owners than any other rule. Three things to understand:
It is total floor area, not the footprint
The SEPP measures the floor area of the secondary dwelling itself. Uncovered decks, a carport and an open pergola are not counted as living floor area, although how attached structures are treated can differ between a certifier reading the Codes SEPP and a council reading its DCP. Ask before you design around the edge of the number.
Some LEPs allow more
The SEPP says the limit is 60 square metres or the larger figure the LEP specifies. A few regional and rural LEPs allow a percentage of the principal dwelling’s floor area instead. Most metropolitan LEPs, including Blacktown LEP 2015, Penrith LEP 2010 and The Hills LEP 2019, do not offer a larger figure for residential land, so 60 square metres is the working number across most of Sydney. Check your LEP before assuming otherwise.
CDC or DA: which pathway fits your block
Complying development is the faster route because a private certifier checks the proposal against fixed standards in the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008, the Codes SEPP, and issues the certificate without a merit assessment. That speed only exists if every standard is met. The moment one is not, you are in DA territory.
| Question | Complying development (CDC) | Development application (DA) |
|---|---|---|
| Who approves it | Private certifier or council as certifier | Council under s4.15 |
| Minimum lot size | Generally 450 square metres | No SEPP minimum, DCP controls apply on merit |
| Variations to standards | None, every standard must be met | Merit based, with a Statement of Environmental Effects justifying departures |
| Heritage items, some flood control lots | Usually excluded from CDC | Available, with specialist reports |
| Neighbour notification | Limited notice, no objection process | Notified, neighbours can make submissions |
| Typical timing | Weeks once documentation is complete | Several months depending on council workload |
On a standard 550 to 700 square metre block in Blacktown, Penrith, Liverpool or Campbelltown with a rear yard clear of easements and large trees, a detached single storey granny flat is often a straightforward CDC. On a 400 square metre lot in a newer release area such as Marsden Park or Gregory Hills, the 450 square metre threshold usually pushes it to a DA before you even look at setbacks. Our DA or CDC pathway advice is designed to settle this question early, before drawings are paid for.
Where granny flat applications go wrong
These are the issues we see most often on secondary dwelling projects across Western Sydney and the Hills:
- Trees. A detached flat in the rear yard usually lands inside the tree protection zone of a neighbour’s tree or a street tree. An arborist report under AS 4970-2009 is often needed, and a CDC cannot approve removal of a protected tree.
- Stormwater. Rear lots with no drainage easement and a fall away from the street need a charged line or an absorption system designed to AS/NZS 3500.3:2021. Some councils accept absorption trenches, some do not. Our civil colleagues at Contrive Consultants handle this regularly.
- Bushfire. On bushfire prone land in the Hawkesbury, Wollondilly or the Blue Mountains foothills, the flat needs a bushfire attack level assessment under Planning for Bush Fire Protection 2019 and construction to AS 3959:2018.
- Private open space for both dwellings. Councils expect the main house to keep usable open space too. A granny flat that eats the entire yard tends to draw a request for information or a refusal.
- BASIX. A new secondary dwelling needs a BASIX certificate under SEPP (Sustainable Buildings) 2022 regardless of pathway.
Council controls still shape the design in a DA
Even though the SEPP guarantees permissibility, the DCP sets the detail. Blacktown DCP 2015, Penrith DCP 2014, Liverpool DCP 2008 and Cumberland DCP 2021 each have a secondary dwelling section with setbacks, solar access, privacy and landscaping expectations. The numbers vary between councils, so read the current DCP for your LGA rather than relying on a builder’s standard plan. In a DA the Statement of Environmental Effects is where we show how the flat sits against those controls and why any departure is reasonable. Most councils also levy a section 7.11 or 7.12 contribution on a new secondary dwelling, so check the contributions plan early.
Frequently asked questions
Can I build a granny flat bigger than 60 square metres in NSW?
Only if the council LEP specifically allows a larger floor area for secondary dwellings on your land. Most Sydney LEPs do not, so 60 square metres is the cap. Attached garages, carports and open decks are treated separately from the living floor area, and the treatment can differ between a CDC and a DA.
Do I need a DA for a granny flat or can a certifier approve it?
A private certifier can approve a secondary dwelling as complying development if the lot is at least 450 square metres, the land is not excluded from the Codes SEPP, and every development standard is met. If any standard is not met, or the land is a heritage item or on certain flood control lots, you need a DA to council.
Can I subdivide a granny flat from the main house?
No. The Housing SEPP prohibits subdivision of a secondary dwelling from the principal dwelling, whether by Torrens, strata or community title. If separate titles are the goal, a dual occupancy is the right development type, with its own lot size rules.
Does a granny flat need its own car space?
The Housing SEPP does not require additional parking for a secondary dwelling. Existing parking for the main house should be retained, and a DCP may still ask you to show how vehicles are managed on site, but a council cannot refuse a DA solely because the granny flat has no dedicated space.
URBA prepares the Statement of Environmental Effects, pathway advice and council liaison for secondary dwelling and granny flat approvals across Sydney, the Central Coast, the Hunter and regional NSW. If you have a block in mind, send us the address and a sketch and we will prepare a fee proposal based on the pathway that fits it.