WA Granny Flat Regulation Change 2024 — What Perth Homeowners Need to Know

If you've been thinking about adding a granny flat to your Perth property, April 2024 changed the game. Significant amendments to WA's planning framework mean that most single-storey granny flats under 70m² no longer require planning approval. For Perth homeowners, this is a big deal.

Here's what changed, what it means for your project, and how to make the most of the new rules.

What changed in April 2024?

The WA State Government amended the Residential Design Codes (R-Codes) and associated planning instruments to streamline the approval process for secondary dwellings — including granny flats, ancillary dwellings and studio apartments.

The key change: single-storey granny flats up to 70m² on R20 and above residential lots no longer require a development approval (DA) from your local council. You only need a building permit — which is a much simpler, faster process handled by a private building surveyor or your local council's building department.

What does this mean in practice?

Before April 2024, building a granny flat in Perth typically involved two separate approval processes:

• Development approval (DA) from your local council — often 8–16 weeks

• Building permit — additional 2–4 weeks on top

Under the new rules, most granny flats under 70m² skip the DA entirely. You go straight to a building permit, which typically takes around 10 business days.

That's the difference between a 3–4 month approval process and a 2-week building permit. Faster project start, lower professional fees, and less time spent waiting.

Does this apply to my property?

The new rules apply to most residential lots in Perth, but there are some conditions. Your property needs to meet the following criteria for the simplified pathway to apply:

• The lot is zoned Residential (R20 or above) under the relevant local planning scheme

• The granny flat is single-storey

• The total floor area of the granny flat is 70m² or less

• The granny flat meets the relevant setback requirements

• There are no heritage overlays, special control areas or restrictive covenants that apply

The majority of suburban Perth properties — including Baldivis, Rockingham, Mandurah, Joondalup, Wanneroo, Midland and most metropolitan areas — will meet these criteria. However, it's worth confirming before you commit to a design.

At BuildWise WA, we assess your property against the current regulations as part of our free initial consultation. If the simplified pathway applies, we'll tell you. If it doesn't, we'll explain exactly what's required.

What about larger granny flats?

If your granny flat is over 70m², or if your property doesn't meet one of the above criteria, you'll still need a development approval from your local council. The DA process typically takes 4–8 weeks, and the full design-to-approval timeline at BuildWise WA is 4–6 weeks end to end.

That said, most of our clients who want a rental-ready granny flat find that a well-designed 60–65m² dwelling ticks every box — two bedrooms, a bathroom, open-plan living and kitchen — and comes in well under the 70m² threshold.

How much does a granny flat cost in Perth under the new rules?

The simplified approval process has reduced the cost and time associated with getting a granny flat approved. Our all-in design and approvals service — including working drawings, building permit application and management — starts from $7,000 for a standard granny flat.

Compare that to the $15,000–$30,000+ that architects and planning consultants typically charge for the same scope. Our focus on granny flats means we're faster, more efficient, and considerably more affordable.

How do I get started?

The best first step is a free consultation with our team. We'll review your block, confirm the applicable approval pathway, and give you a clear picture of timelines and costs — no obligation.

Call us on 0492 972 408 or fill in the quote form on our website. We respond within 2 hours.

  BuildWise WA specialises in granny flat design, council approvals and project management across all of Perth. Our all-in service starts from $7,000. Free consultations available Monday to Friday.