Granny flat rules in WA

In Western Australia a granny flat is called an ancillary dwelling. The rules are in the Residential Design Codes (R-Codes), plus your council's local planning scheme and policies. Here are the main points for Perth owners.

Size: up to 70 m²

To meet the deemed-to-comply rules, the granny flat's plot ratio area can be up to 70 m². Patios and verandahs are generally not counted. Every design in our range is under this limit.

Lot size: no minimum

Changes to the R-Codes that took effect in 2024 removed the old 350 m² minimum lot size, so a compliant granny flat can go on residential lots of any size, as long as it fits the other rules.

Development approval

A granny flat that meets all of the deemed-to-comply requirements, such as setbacks, open space, size and parking where needed, is exempt from development approval. If any part does not comply, or your lot is affected by something like a heritage listing or special control area, you will need development approval from your council first.

Building permit: always

Every granny flat needs a building permit before work starts, including factory-made ones. We prepare and lodge it as part of your job.

Parking

Usually no extra parking bay is required, but there are exceptions depending on your density code and distance to public transport. We check this for your address.

Who can live in it

WA no longer requires a granny flat to be occupied by a family member, so you can rent it to anyone. It stays on the same title as your main house and cannot be sold separately. To create a separate title you would need to subdivide, which Perth Subdivisions can check for you.

Check with your council

Some councils have local planning policies that add detail, and rules change. Always confirm the position for your lot before you commit. We do this as part of the site visit.

Common questions