Building a granny flat in WA could soon get bigger, simpler and faster. On 24 October 2026, the West Australian State Government released proposed changes to the Residential Design Codes (R-Codes) that would lift the maximum granny flat size from 70 to 90 square metres, scrap minimum car parking requirements and ease rear setbacks in lower density areas.

If you’ve been weighing up a granny flat for an ageing parent, a young adult who’s not quite ready to leave home or extra rental income, these proposals are worth knowing about. Here’s what’s on the table, what it could mean for your block and what still applies today.

What’s being proposed for granny flats

The R-Codes are the state-wide rules that control residential design and density in WA, from lot sizes and building heights to parking, setbacks, open space, privacy and landscaping. The Western Australian Planning Commission is reviewing them to make them simpler and more flexible, and three proposed changes speak directly to granny flats:

• More room to live in. The maximum floor area for a granny flat would increase from 70 to 90 square metres. That’s enough to comfortably fit a second bedroom, a more generous living area or a proper home office.
• No minimum car parking. Minimum car parking requirements for granny flats would be abolished, freeing up space on smaller or narrower blocks where a dedicated parking bay can be the deal-breaker.
• Smaller rear setbacks. The required setback from the rear boundary would be reduced in lower density areas, giving you more options for where the granny flat sits on your block.

The broader package also proposes scrapping average lot sizes for R10 to R25 codes in Perth and Peel, which the Government says would make more than 70,000 existing properties eligible to subdivide.

What it could mean for you

The biggest win is time. According to Planning and Lands Minister John Carey, the adjusted standards mean more granny flats would skip the two-to-three-month planning approval process altogether, needing only a building permit. For many homeowners, that’s the difference between moving family in before winter or after it.

A 90 square metre limit also changes what a granny flat can be. At 70 square metres, most designs are a tight one-bedroom or compact two-bedroom. An extra 20 square metres opens up genuine two-bedroom layouts, a second bathroom or more storage, which makes a granny flat a more realistic long-term home for an ageing parent, an adult child or a tenant.

And for blocks that were previously ruled out because there was nowhere to put a car bay, or not enough depth to meet the rear setback, the proposed changes may put a granny flat back on the table.the life of the project. It’s a large part of why a construction loan often beats simply topping up your existing home loan.

These are proposals, not law (yet)

It’s important to note that these changes are out for public comment and haven’t been adopted. Until the final R-Codes are approved, the current rules, including the 70 square metre limit, still apply to any granny flat you build today. Feedback from the consultation will shape the final version before it goes to the Western Australian Planning Commission for consideration.

You can have your say until 5pm (AWST) on Friday 26 February 2027 through the Have Your Say WA R-Codes Review page. There’s a short 5 to 10 minute survey, a detailed feedback form and in-person community pop-ups across Perth in late November and early December 2026.

Thinking about a granny flat? Start planning now

You don’t need to wait for the final R-Codes to start exploring your options. Understanding your block, your budget and how you’ll use the space now means you’ll be ready to move as soon as the rules are confirmed, whether you build under today’s standards or the new ones.

The team at Fox Granny Flats can walk you through what’s possible on your property under the current rules and how the proposed changes could open up more options. Get in touch to start the conversation.

Call our team on (08) 6117 5719, or book a free consult and come see the range at our Gnangara display village.

Sources:

Changes to cut red tape for new granny flat developments, WA Government media statement, 24 October 2026

Residential Design Codes Review, Have Your Say WA