If you’ve ever thought about building a granny flat or adding a modular home to your property, now’s a great time. Recent changes in Western Australia have made it easier to get approval, cutting down on the red tape and making the process faster than ever.

Changes were made by getting rid of the planning approval requirement, then administration requirements were reduced and the time to take to start building a granny flat was lessened which allowed for quicker construction. Therefore helping with the housing situation across Perth and the state.

Whether you’re looking to create a cosy space for your adult kids, bring your ageing parents closer, earn a rental income, or simply increase your property’s value, here’s a guide to help you get started to see first, if you can fit a granny flat on your block.

1. What Are the New Block Size Rules for Building a Granny Flat?

In April 2024, the Cook Government announced some planning reform changes that would relax the amendments and restrictions that were previously held on building granny flats on your property.  The State Planning Policy 7.3 Residential Design Codes (‘R-Codes’)  were amended which removed the minimum lot size requirement for building a granny flat. Previously, you needed a minimum of 350m², which ruled out a lot of properties. Now, as long as your lot meets some basic requirements, you’re likely good to go.

To qualify, your granny flat should be an “ancillary dwelling,” meaning it’s built on a property that already has a primary residence. It must also be within a specific size limit—up to 70m² in some council areas and is likely to be more flexible in rural areas. These relaxed rules make it easier for more homeowners to add a granny flat to their property without the usual barriers.

2. Space and Setback Requirements

While you no longer need a minimum lot size, there are still some rules around how big the granny flat can be and where it sits on your property.

Granny flats must meet residential design codes (R-Codes) setback requirements, which are the minimum distances between the structure and the property boundary, typically the fencing. The exact setback distances may vary depending on the height of the granny flat, but they’re designed to ensure safety and adequate space between properties.

WA’s granny flat regulations can also be checked against:

The Planning and Development Act 2015

Western Australian Planning Commission

However, we recommend to check with your local council’s planning department as to their exact requirements around granny flats as all councils have different guidelines.  Once you’ve checked your size and setback boxes, you’re ready to move onto the approval phase!

3. The Approval Process: Quick and Simple

One of the best things about these new rules is that they simplify the approval process. Here’s how it works:

• Building Permit: For most granny flats that meet the size and setback standards, you only need a building permit. This ensures your project meets Australia’s standards for safety, energy efficiency, and construction quality. Generally, the permit approval takes around 10 business days, so you’re not left waiting months to get started.
• Council Planning Approval: In WA, council planning approval is no longer required if your granny flat is within the 70m² limit and complies with other Residential Design Codes (R-Codes). Previously, planning approvals could take months, as councils would assess factors like surrounding properties and local development rules. Now, if your granny flat ticks the right boxes, you can skip this step entirely.

This streamlined approval process saves both time and stress, allowing you to start construction sooner and with less hassle.

4. Building Approvals and Associated Costs

A building permit does have associated fees, and these can vary depending on your council. Keep in mind that if your initial permit doesn’t meet all requirements and needs to be resubmitted, additional costs could apply. It’s a good idea to budget for these when planning your granny flat project.

That said, with the relaxed requirements, most homeowners can avoid additional costs and delays that previously came with council planning approvals.

Check with your granny flat or modular home builder as most can organise this building permit process for you.

5. Why Now is the Perfect Time to Build a Granny Flat or Modular Home

With these updated rules, building a granny flat or modular home has become easier and faster, making it a timely choice. Not only do you get to make full use of your backyard space, but you’ll also be helping out your adult kids or elderly parents in the housing shortage, and also adding value to your property and potentially creating a new income stream (Check out our blog on renting out a granny flat).

Have Questions? We’re Here to Help!

If you’re thinking about adding a granny flat or modular home, but aren’t sure where to start, connect with us. We’re here to guide you through everything from the design phase to approvals to the build, so you can enjoy a smooth, stress-free experience. Whether it’s a place for family or a source of extra income, we’re excited to help bring your granny flat vision to life.