Suburb guide · 2145
Can I build a duplex or granny flat in Girraween?
Girraween sits in Cumberland City Council's area under Cumberland Local Environmental Plan 2021. We ran 25 real Girraween addresses through the checker: the typical block is 611 m² with 15.3 m of frontage, 21 of the 25 could add a granny flat, and 21 could carry two separate homes today.
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The typical Girraween block
The middle block of the 25 we checked is 611 m² with 15.3 m of street frontage. The smallest was 526 m² and the largest 3,608 m². Zones in the sample: R2 (21), R3 (3), E4 (1).
The 25 blocks we checked, by land size.
What homes sell for in postcode 2145
Median sale prices for the whole of postcode 2145, January to March 2026. These cover every suburb sharing the postcode, not Girraween alone, and they are not a value for any one block.
- Houses: $1.48m (129 sales)
- Units and apartments: $600k (198 sales)
Source: NSW Government Rent and Sales Report (Department of Communities and Justice), sales tables by postcode, NSW Government. Updated each quarter.
A granny flat
21 of the 25 blocks we checked could take one. Cumberland LEP cl 5.4(9) — the greater of 60 m² or 10% of the house’s total floor area, parking excluded. Separately, the state Housing SEPP allows a granny flat of up to 60 m² through the ten-day complying-development route on a lot of 450 m² or more with a 12 m frontage, where the land is not flood, bushfire or heritage constrained.
Dual occupancy (duplex) rules in Girraween
21 of the 25 blocks we checked could carry two or more separate homes today.
Under Cumberland Local Environmental Plan 2021 a dual occupancy needs 550 m² — this LEP sets no frontage minimum, so Council's DCP governs width.
Of the 21 ordinary R2 blocks in our sample sitting outside the Low and Mid-Rise area, 18 had the 550 m². There is no LEP frontage test to pass here, but Council's DCP still judges width, setbacks and private open space, so clearing the area alone does not settle it.
Low and Mid-Rise
None of the 25 blocks we checked fell inside the state Low and Mid-Rise area, so in this part of Girraween the LEP minimums are what count. The boundary is a walking distance from a listed centre, so it can cut through a suburb — the checker reads which side of it your own address sits on.
What else turned up
None of the blocks we checked came back bushfire-prone, flood-mapped or heritage-listed. Any of those takes a block out of the fast-track routes and into a full DA, so it changes the answer more than the lot size does.
How we got these numbers
We took 25 real Girraween street addresses from the NSW geocoder and ran every one through the same engine this site runs for you, reading the planning controls live. Nothing here is modelled or estimated.
It is a sample, not a census. The addresses are a spread across what the geocoder returns, so treat these as "of the 25 blocks we checked" rather than a figure for every block in Girraween. Your own block is the only one that answers for itself — that is what the box on the right is for.
Enter the address — lot, frontage, zone, constraints and what it can carry.