Granny flat construction is on the rise – according to Google Trends, searches for “granny flat” in Australia increased over the past five years, with a noticeable spike in late 2023 and into 2025. Driven by a need for more living space, the potential for rental income, and the opportunity to house elderly parents, teenagers, or relatives, granny flats are a practical and flexible solution in maximising space on an existing property.
Building a granny flat in Western Australia has become easier than ever as a result of the April 2024 changes to the Residential Design Codes (R-Codes). The design code changes have reduced and removed planning hurdles and lot size restrictions that would have been previously holding many homeowners back from adding on a granny flat.
Granny Flat Building Requirements WA
Building a granny flat is governed by R-Codes Volume 1 (2021). Under the R-Codes, granny flats do not require planning approval when the build is 70 sqm or less and associated with a single house.
Given that planning approval in Western Australia can take between 90 and 120 days, this exemption from planning approval significantly reduces the timeline (and complexity) of building a granny flat.
Building a granny flat will still require a building permit from the local council and other requirements such as 1m from the boundary, maximum height (8.5m) and visual privacy. Council building permit approvals only take a maximum of 10 days.
How The Requirements Have Changed
The R-Codes previously required a minimum block size of 350 sqm for building a granny flat. As part of the 2024 update, this requirement has been removed – which means granny flats can be constructed on residential blocks regardless of size or zoning (as long as compliant with the R-Codes and the National Construction Code).
Building a granny flat also previously required the inclusion of an additional car bay. This requirement has now been removed as part of the 2024 R-Codes updates for granny flat constructions near public transport. Homeowners in metropolitan areas can now build a granny flat without needing to include an extra car bay, saving costs and planning effort.
The Process of Building A Granny Flat
Onsite inspection
A builder or designer will come to the property to assess the space and work out what’s possible for a granny flat with the current R-Codes and council regulations.
Measurements
Measurements are taken to work out the size of the granny flat and the indoor spaces. The floor plan of the granny flat cannot exceed 70 sqm.
Design development
The builder develops a floor plan that suits your preferences – you’ll be able to choose internal layouts, fixtures, finishes and external colours. Much alike our bathroom, laundry and kitchen renovation processes, the design will be presented using 3D modelling software to help you visualise the outcome.
Building approval
Although planning approval is no longer required, the project will require a building permit from the local council. The builder will handle the paperwork and submit it on behalf of the homeowner. Councils typically take up to 10 working days to issue the permit.
Construction
Once the permit is approved, the construction process can begin. Build time is usually 6-10 weeks depending on the design, weather, and availability of materials. A standard granny flat will include a kitchen, bathroom with laundry, bedrooms, and living spaces.
Why Build a Granny Flat?
A granny flat is a practical addition to any property, especially if the block has the space. Compared to a home extension, which will be more expensive and take longer, a granny flat offers the flexibility of a detached living space that can be used privately or as an investment property.
Granny flats can be used as a guesthouse or extra space for multigenerational families, allowing homeowners to keep elderly parents or teenagers close by while offering more privacy. Or, a granny flat can be used as a home office, studio, or as a rental opportunity.
For those looking to build a granny flat in Western Australia, Vensao Selections are the leading granny flat builders in Perth – we can design and execute an extension tailored to your budget, block size, and intended use. We manage the entire process from the initial design to overseeing construction, and work with household Australian brands to provide high-quality fixtures. Get in touch with our team to book a free measure and quote appointment for a granny flat build.