Can I build a duplex or granny flat in Glenbrook?

The typical Glenbrook block

The middle block of the 25 we checked is 928 m² with 20.0 m of street frontage. The smallest was 428 m² and the largest 5,904 m². Zones in the sample: DM (9), C4 (9), R2 (5), C2 (1), E1 (1).

What homes sell for in postcode 2773

Median sale prices for the whole of postcode 2773, January to March 2026. These cover every suburb sharing the postcode, not Glenbrook alone, and they are not a value for any one block.

• Houses: $1.69m (11 to 30 sales, a small sample)
• Units and apartments: not published (10 or fewer sales this quarter)

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

A granny flat

14 of the 25 blocks we checked could take one. Blue Mountains LEP cl 5.4(9) — the greater of 60 m² or 25% 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 Glenbrook

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

Under Blue Mountains Local Environmental Plan 2015 a dual occupancy needs 1,000 m² — this LEP sets no frontage minimum, so Council's DCP governs width.

Only 5 of the 25 blocks we checked were ordinary R2 land outside the Low and Mid-Rise area, which is too few to read anything into — most of Glenbrook in our sample was zoned or mapped some other way.

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 Glenbrook 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

14 of 25 were on bushfire-prone land. 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 Glenbrook 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 Glenbrook. Your own block is the only one that answers for itself — that is what the box on the right is for.