Can I build a duplex or granny flat in Mount Vernon?

The typical Mount Vernon block

The middle block of the 25 we checked is 10,160 m² with 74.7 m of street frontage. The smallest was 8,997 m² and the largest 24,435 m². Zones in the sample: C4 (24), ENZ (1).

A granny flat

24 of the 25 blocks we checked could take one. Penrith 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 Mount Vernon

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

Under Penrith Local Environmental Plan 2010 a dual occupancy needs 650 m² — this LEP sets no frontage minimum, so Council's DCP governs width.

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 Mount Vernon 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

5 of 25 were on bushfire-prone land; 3 of 25 were flood-mapped. 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 Mount Vernon 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 Mount Vernon. Your own block is the only one that answers for itself — that is what the box on the right is for.