Can I build a duplex or granny flat in Carss Park?

The typical Carss Park block

The middle block of the 25 we checked is 656 m² with 13.8 m of street frontage. The smallest was 521 m² and the largest 174,442 m². Zones in the sample: R2 (21), R4 (2), E1 (1), RE1 (1).

What homes sell for in postcode 2221

Median sale prices for the whole of postcode 2221, January to March 2026. These cover every suburb sharing the postcode, not Carss Park alone, and they are not a value for any one block.

• Houses: $2.30m (11 to 30 sales, a small sample)
• Units and apartments: $923k (11 to 30 sales, a small sample)

Source: NSW Government Rent and Sales Report (Department of Communities and Justice), sales tables by postcode, NSW Government. Updated each quarter.

A granny flat

19 of the 25 blocks we checked could take one. Georges River 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 Carss Park

6 of the 25 blocks we checked could carry two or more separate homes today.

Under Georges River Local Environmental Plan 2021 a dual occupancy needs 650 m² and 15 m of frontage.

Of the 21 ordinary R2 blocks in our sample sitting outside the Low and Mid-Rise area — where that minimum is the only test that applies — 6 had the frontage and 9 had the land. 4 had both.

So in Carss Park it is the frontage that does the stopping — the land is there on plenty of blocks, but they are narrow and deep. Width is the harder of the two to solve.

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 Carss Park 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

1 of 25 carried a heritage listing or conservation area. 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 Carss Park 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 Carss Park. Your own block is the only one that answers for itself — that is what the box on the right is for.