Last reviewed: August 2026
In NSW a granny flat is capped at 60m² of floor area, needs a lot of at least 450m² to use the fast approval pathway, and cannot be subdivided off the main house. Setbacks, frontage and landscaping requirements are not fixed numbers. They step up as your lot gets bigger, which is the detail most guides leave out.
Everything below comes from the State Environmental Planning Policy (Housing) 2021, with the section numbers so you can check it yourself.
What a granny flat legally is
The legal term is a secondary dwelling. It is a self-contained home on the same lot as a principal dwelling, sharing the same title.
Three rules define it more than anything else:
- 60m² maximum floor area, unless another planning instrument covering your land allows more (section 52(2)(c))
- No subdivision. You cannot split it off and sell it separately (section 51)
- One only. When the work is done, the lot can have exactly one principal dwelling and one secondary dwelling (section 52(2)(a))
It is permitted with consent in residential zones R1 through R5. For the fast complying development pathway, R5 Large Lot Residential is excluded (section 54(1)(a)).
The size and dimension rules
Floor area
60m². This is a hard ceiling on both approval pathways.
Worth knowing what counts and what does not. Covered outdoor areas, carports and garages are treated as ancillary structures with their own rules rather than being counted in the 60m² in the same way. How your particular design is measured is a question for your certifier, and it is worth asking early, because a design that measures 61m² is not a minor problem, it is a different approval pathway.
Height
| Structure | Maximum height |
| The granny flat | 8.5m above existing ground level |
| A detached outbuilding | 4.8m |
| A fence | 1.8m |
Most single storey granny flats sit well under 8.5m. The number that actually bites is 3.8m, because going above it increases your required setbacks. More on that below.
Lot area and frontage
Minimum 450m² for complying development. Frontage is measured at the building line and steps up with lot size.
| Lot area | Minimum frontage |
| 450m² to 900m² | 12m |
| Over 900m² to 1,500m² | 15m |
| Over 1,500m² | 18m |
For a battle-axe block, the access handle is excluded when calculating the lot area. A title showing 490m² can fall under the 450m² threshold once the driveway strip comes out.
The setback rules, properly
Here is where most published guides are wrong. They quote “900mm side, 3m rear” as though it applies everywhere. Those are the figures for lots between 450m² and 900m² only.
Side setbacks
| Lot area | Minimum side setback |
| 450m² to 900m² | 0.9m |
| Over 900m² to 1,500m² | 1.5m |
| Over 1,500m² | 2.5m |
Then add 25% of any height above 3.8m.
Rear setbacks
| Lot area | Base | Height loading over 3.8m | Capped at |
| 450m² to 900m² | 3m | 3× the height above 3.8m | 8m |
| Over 900m² to 1,500m² | 5m | 3× the height above 3.8m | 12m |
| Over 1,500m² | 10m | 3× the height above 3.8m | 15m |
The height loading is aggressive. On a standard 600m² block, a building 4.8m tall needs 3m plus three times the 1m of extra height, so 6m from the rear boundary instead of 3m. That one metre of height costs you three metres of yard.
If your rear boundary is on a laneway, the building may abut it for up to half that boundary’s length (section 10(2)).
Front and corner setbacks
The front setback is normally the average of the two nearest houses on your side of the street within 40m. Where there are not two within 40m, it is 4.5m on lots up to 900m², 6.5m up to 1,500m², and 10m above that. A classified road requires 9m.
On a corner lot, the secondary road setback is 2m for lots between 450m² and 600m², 3m up to 1,500m², and 5m above that.
A boundary with a public reserve needs at least 3m.
Landscaping
| Lot area | Minimum landscaped area |
| 450m² to 600m² | 20% |
| Over 600m² to 900m² | 25% |
| Over 900m² to 1,500m² | 35% |
| Over 1,500m² | 45% |
At least half of it has to be behind the building line. This one quietly limits how much of a small backyard you can build on and pave.
Design requirements people do not expect
The SEPP has rules about how the buildings look and how they treat neighbours.
- Either the house or the granny flat must present a front door and a habitable room window to the primary road (section 13(1))
- On a corner lot, a habitable room window of at least 1m² must face and be visible from the secondary road (section 13(4))
- Privacy screens are required on habitable room windows close to a boundary where the floor level is raised. Within 3m of a boundary the trigger is a floor more than 1m above ground. Between 3m and 6m it is a floor more than 3m above ground. Bedroom windows of 2m² or less are exempt (section 15)
- Privacy screens must be 1.7m to 2.2m above the finished floor level
The bedroom limit that does not exist
You will see it stated confidently across the internet that a NSW granny flat is limited to two bedrooms.
That limit is not in the Housing SEPP secondary dwelling provisions. What is in there is the 60m² floor area cap. The practical reason most granny flats have one or two bedrooms is that 60m² does not comfortably fit more once you account for a kitchen, bathroom and living space.
That said, your council’s own local environmental plan or development control plan may impose a bedroom limit, and some do. So the honest answer is that it is not a state rule, it may be a local one, and it is worth checking for your address rather than assuming either way.
What is not covered by the fast pathway
Complying development will not cover a basement or a roof terrace on the topmost roof. Land that is heritage listed or environmentally sensitive is excluded. Bush fire prone land, flood control lots and land near the Siding Spring Observatory carry additional standards under sections 57 to 59.
Any of these push you to a development application, which is a merit assessment by council rather than a compliance check.
Frequently asked questions
Can I build a granny flat on a block smaller than 450m²?
Not through complying development. 450m² is the threshold. On a smaller block you would need a development application, and approval is at council’s discretion rather than guaranteed.
Can I rent out my granny flat in NSW?
Yes. A secondary dwelling can be rented to anyone, including people unrelated to the household. What you cannot do is subdivide it and sell it separately.
Does the 60m² include the carport or covered patio?
Not in the same way. Carports, patios and similar structures are treated as ancillary structures under Schedule 1 with their own height and setback rules. Exactly how your design is measured is a question for your certifier, and it is worth asking before the plans are finalised.
Do these rules change between councils?
The state standards above are consistent across NSW. What varies is whether another planning instrument covering your land permits a larger floor area, imposes a bedroom limit, or adds local controls. That is why a compliance check is done against your specific address rather than a general rule.
How do I know which lot size band I am in?
From your title and survey, not from memory or a real estate listing. For a battle-axe block, remember the access handle comes out of the calculation, which can move you into a different band than you expect.
Check the rules against your actual block
The bands above mean the answer genuinely differs from one property to the next. A 620m² block and a 950m² block on the same street have different setbacks, different frontage requirements and different landscaping minimums.
Check your block, or call BlueGum on 1300 060 651 for a site assessment.
BlueGum Granny Flats is a licensed NSW builder, licence number 247388C. This article summarises the State Environmental Planning Policy (Housing) 2021 as in force in August 2026 and is general information, not planning advice. Other planning instruments applying to your land can vary these standards. Confirm the requirements for your block with a certifier or your council.
