Can I Build a Granny Flat in WA?
- Arcaia Studio
- May 18
- 4 min read
2024 Rules Explained
Thinking about building a granny flat in Western Australia? Under the updated 2024 R-Code rules, compliant ancillary dwellings up to 70sqm may no longer need planning approval, and the old minimum lot size requirement has been removed. Arcaia Studio explains what this means, what still needs to comply, and when you may still need council approval.
Can I build a granny flat in WA
The short answer is yes. And thanks to major rule changes in April 2024, it has never been more straightforward.
The WA Government updated the Residential Design Codes (R-Codes) and removed two of the biggest barriers homeowners used to face: minimum lot size and planning approval.
Here is exactly what changed, what it means for your property, and how to get moving.
Can I build on my property?
Yes. The 2024 R-Code update removed the minimum lot size requirement for granny flats in Western Australia.
Previously you needed at least 350sqm. That rule is gone. Whether you have a small suburban block or a large regional property, you now qualify.
Your granny flat can be:
Attached to the main house
Integrated within the existing structure
A fully separate building in the backyard
The only condition is that it sits on the same lot as your main home and meets the R-Code siting rules below.
How big can it be?
Sample of a 70 sqm Granny flat
The maximum size is 70 square metres of floor area.
Think of it as a generous one-bedroom apartment. Done well, 70sqm fits a kitchen, bathroom, laundry, living area, and one or two bedrooms comfortably.
Key siting rules to know:
1 metre minimum setback from rear and side boundaries
Maximum height of 4.2 metres for flat-roof structures
Visual privacy requirements between windows and neighbouring properties
A good designer sorts all of this before anything goes to council. That is the whole point of getting your drawings done properly.
Do I need council approval?
This is the big one. Under the 2024 changes:
If your granny flat is under 70sqm and meets the R-Code deemed-to-comply standards, you do not need planning approval.
You do still need a building permit. But these are two very different things:
Planning approval checks your design against zoning and neighbourhood impact rules. For compliant granny flats, this step is now waived.
Building permit confirms your structure meets the National Construction Code for safety and energy efficiency. This is always required.
The good news on timing: a certified building permit (BA1) is typically approved within 10 business days. Once your drawings are ready, you are not waiting months.
Can I put one in my backyard?
Yes. A detached granny flat in the backyard is the most popular option right now, especially in the South West and regional WA where blocks tend to be generous.
It gives whoever lives there real independence and privacy from the main house. With a well-considered design it feels like a complete small home, not an afterthought
Can I live in it or rent it out?
Yes, both. A granny flat in WA can be used for:
Housing an ageing parent or adult child nearby but independently
Generating rental income from a private tenant
Short-term or guest accommodation
A home office or studio with a living component
The 2024 reforms specifically opened granny flats up as rental properties to help ease the state housing shortage. Rental income may also qualify for negative gearing. Talk to your accountant about that one.
Does it have a kitchen and bathroom?
Yes. A properly designed granny flat is fully self-contained. That means:
Kitchen with cooking facilities
Bathroom and laundry
One or two bedrooms
Living and dining area
Its own utility connections
Fitting all of that into 70sqm takes real design skill. Spatial planning, natural light, ventilation, storage. This is where a good designer earns their fee.
Who owns it?
The granny flat belongs to the property owner. It cannot be sold separately from the main lot without going through a formal subdivision process.
If you sell the property later, the granny flat transfers with it. A well-designed one can add 20 to 30% to your property's market value according to recent reports
How do you get started?
Simpler than most people expect. Here is how it works at ArcaiaStudio:
Free consultation. We look at your site, talk through your brief, and confirm what is feasible under the R-Codes for your area.
Design. We create a layout that suits your block and your needs, with 3D visuals so you can see it clearly before anything is built.
Documentation. Full council-ready drawings delivered, typically within 14 days.
Building permit. Your builder lodges the application. Approval usually takes around 10 business days.
We work remotely with clients across all of WA. Geraldton, Margaret River, Busselton, Dunsborough, Exmouth and beyond. You do not need to be near us for this to work.
Book a free consultation:
Frequently asked questions
Do I need council approval for a granny flat in WA? Not for planning approval, provided it is under 70sqm and meets the R-Code standards. You still need a building permit, which takes around 10 business days for a certified application.
How long does it take to get plans drawn up? At ArcaiaStudio, council-ready drawings are typically delivered within 14 days of receiving your site information and brief. That includes floor plans, elevations, site plan, and 3D visuals.
Can I build on a small block? Yes. The minimum lot size requirement was removed in April 2024. Block size is no longer a barrier anywhere in WA.
Can I rent it to anyone? Yes. The 2024 reforms removed the restriction that previously limited occupancy to family members only.
Do you work outside Perth? Absolutely. We design for clients across regional WA digitally, from the first conversation through to council submission. No site visit required to get started.
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