Minimum Lot Size for a Granny Flat in NSW
The minimum lot size is 450 sqm under the SEPP (Affordable Rental Housing). Most residential blocks in Western Sydney exceed this — Fairfield typical blocks are 500–700 sqm, Liverpool 500–700 sqm, Canterbury-Bankstown 500–650 sqm. Newer estates (post-2010) may be under 450 sqm and would not qualify.
Practical Space Beyond the Minimum
Meeting 450 sqm does not guarantee a granny flat fits well. You also need: 60 sqm footprint, setbacks (0.9m sides + 3m rear + gap behind house), private open space (24 sqm per dwelling), landscaped area (30–40% of lot), parking (1 space), and access path.
On a 450 sqm block with 150 sqm house, you have approximately 300 sqm remaining. After setbacks and landscaping, buildable area for a granny flat is 80–120 sqm. A 60 sqm granny flat fits but with modest outdoor space. On 600+ sqm blocks, flexibility is much better.
Challenging Block Types
Battle-axe blocks: access handle counts toward lot area but is not usable. Blocks with large houses: 450 sqm block with 200 sqm house = only 250 sqm remaining — tight. Blocks with pools: pool + setback zone consumes 40–80 sqm. Blocks with easements: sewer/stormwater easements prevent building over them.
Buildana's free site assessment evaluates all factors. We will tell you honestly whether a granny flat fits and what size is feasible. Contact us.
