What changed
Western Australia updated the Residential Design Codes (the R-Codes), and the new rules became operational in mid-April 2024. The aim was more housing choice and more support for ageing in place.
Under the R-Codes, an ancillary dwelling (a granny flat) can be up to 70 m² of plot ratio area. That's the floor area of the home itself; verandahs open on at least two sides and parking areas generally aren't counted. Anyone can live in it: a relative, a friend or a tenant. The old minimum lot size has been removed.
Do I need planning approval?
In residential zones, usually not, as long as your granny flat meets the R-Codes' deemed-to-comply provisions, such as setbacks from your boundaries. It generally can't sit in the front setback.
Rural zones are different. They follow your shire's local planning scheme, which sets its own size limits and setbacks, so check with your shire first.
You still need a building permit
Every granny flat needs a building permit, whatever the zone. If your block is in a bushfire-prone area, it also needs a BAL (bushfire attack level) assessment, and the home is built to suit that rating.
For work valued over $20,000 you'll need either owner-builder approval or a registered builder to apply for the permit.
Renting it out
You can rent a granny flat out. If you're planning short stays, such as Airbnb, every short-term rental in WA has had to be on the state register since 1 January 2025, granny flats included, and some shires add their own planning rules. Check with your shire before you build.
How Peak homes fit the rules
The Ridge (41.4 m²), The Cape (45 m²) and The Headland (70 m², two bedrooms) all sit within the 70 m² limit. Open decks and patios generally aren't counted, but your shire makes the final call. The Point is two separate stays under one roof, so talk to us and your shire about how it fits your block.
Mum or Dad just across the garden, a place for the grandkids to stay, or a quiet place of your own. For most South West blocks, the rules now make that a lot easier.
Questions
How big can a granny flat be in WA?
Up to 70 m² of plot ratio area under the R-Codes. Verandahs open on at least two sides and parking areas generally aren't counted. Rural zones follow your shire's own scheme, which may allow a different size.
Do I need council approval for a granny flat in WA?
You always need a building permit. In most residential zones you no longer need planning approval for a granny flat up to 70 m² if it meets the R-Codes' deemed-to-comply provisions. Rural lots follow your shire's rules.
Can I rent out my granny flat?
Yes. Anyone can live in a granny flat, including a tenant. Since 1 January 2025, short-stay rentals in WA must be on the state register, and some shires add their own rules.
Is there a minimum lot size?
The minimum lot size requirement for ancillary dwellings has been removed in residential zones. Setbacks and other R-Codes provisions still apply.
Sources
- Department of Planning, Lands and Heritage: ancillary dwellings
- City of Gosnells: ancillary dwellings
- Shire of Harvey: ancillary dwelling information sheet
- Shire of Dardanup: ancillary dwellings information sheet
- Consumer Protection WA: short-term rental accommodation register
- WA Government: owner-builder approval
General information only, not legal or financial advice. Rules change and each shire applies its own scheme, so check with your shire before you build.
