Guide
Granny flat rules in NSW
What the Housing SEPP actually allows, as opposed to what the 60 m² figure everyone repeats implies.
What a secondary dwelling is, legally
A self-contained dwelling on the same lot as a principal dwelling, governed by Chapter 3 of the Housing SEPP with its complying development pathway in Schedule 1.
It is not a dwelling house for the purposes of the Housing Code. That matters because the figures people find online for a new house — the floor area table, the setbacks — do not apply here. Different instrument, different standards.
It is permitted with consent on a lot in a residential zone where a dwelling house is permissible under another planning instrument. If a house isn't permissible in the zone, a granny flat generally isn't either.
The 60 m² figure is a default, not a rule
The standard is 60 m², or a greater area permitted by the LEP. That second limb is where the value is, and it is the part every summary drops.
Councils that permit more commonly allow up to 100 m². The difference between 60 and 90 m² is typically the difference between a one-bedroom and a genuine two-bedroom dwelling, which changes both what it rents for and who will live in it. It is the first thing worth checking and it takes minutes.
Note also that the total floor area of all buildings on the lot is capped as well, so on a block with a large existing house the granny flat can be constrained by the combined figure rather than by its own.
What usually stops one
In rough order of how often we see it:
- Frontage. The minimum primary road frontage rises with lot size and it is the most common failure.
- Rear setback. Deeper on larger lots, and increased further where the building is taller. On a block with an existing house well back from the street, the buildable band left at the rear can be narrower than the dwelling needs.
- Lot area. Below about 450 m² the complying development tables don't operate.
- Flood. The probable maximum flood refuge level, which is a materially higher bar than the 1% AEP most people have heard of.
- Heritage, or an environmentally sensitive area.
None of these ends the project. They move it to a development application, where a granny flat on a smaller or narrower lot can be approved on merit. That is a real route, and worth pricing rather than abandoning.
Where to go next
- Granny flats and secondary dwellings — the full standards, setbacks and amenity requirements
- CDC or DA — which pathway applies, and why
- What one costs to build — note the service connections line, since a granny flat usually needs separate metering
- Our fees for the design and approval documentation
Common questions
How big can a granny flat be in NSW?
The Housing SEPP default is 60 m² of floor area, or a greater area where the council’s local environmental plan permits it. Many councils do permit more, commonly up to 100 m², so the LEP is worth reading before accepting the 60 m² figure.
What size block do I need?
For the complying development pathway the Schedule 1 setback tables operate from 450 m² upward, so that is the practical floor, and the lot also has to meet a minimum primary road frontage that increases with lot size. A smaller or narrower lot can still support a granny flat by development application.
Do I need extra parking for a granny flat?
No additional space is required. The rule is that the number of on-site spaces after the development must be the same as before it — so you cannot delete the existing house’s parking to make room, which is what a lot of concept plans quietly do.
Can I build a granny flat on a flood-affected block?
Sometimes, but the bar is higher than people expect. For a secondary dwelling on a flood control lot the flood refuge level is the probable maximum flood level, not the 1% AEP. Where that cannot be met, complying development is closed.
Can I subdivide the granny flat onto its own title?
No. A secondary dwelling is on the same lot as the principal dwelling and stays there. If separate titles are the goal, the project is a dual occupancy, not a granny flat.
Can I rent it out separately?
Yes. A secondary dwelling can be rented independently of the principal dwelling, which is the reason most of them get built.
General information about NSW planning, current at September 2026. Not advice on a particular site — the instruments are amended often and councils vary them locally.
Will one fit on your block?
Send us the address. We'll tell you the size you can actually build.