If you’re thinking of building a granny flat, one of the first questions you’ll likely ask is: how big should it be? The size of a granny flat plays an important role in how comfortable, functional, and compliant it is with local regulations. For many homeowners, a 2-bedroom granny flat strikes the perfect balance between space and practicality. But what is the average size you can expect?
Standard Size of a 2-Bedroom Granny Flat in Australia
In most parts of Australia, especially New South Wales, the average size of a 2-bedroom granny flat is around 50 to 60 square metres. This size is largely determined by local planning regulations, with 60 square metres typically being the maximum allowable floor area under the NSW State Environmental Planning Policy (SEPP) for a secondary dwelling.
While 60 square metres might sound compact, thoughtful design can make it feel surprisingly spacious. Many standard layouts fit two bedrooms, a bathroom, an open-plan living area, a small kitchen, and sometimes even a laundry within this limit.
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Factors That Affect the Size of a 2-Bedroom Granny Flat
The exact size and layout of a 2-bedroom granny flat can vary depending on a few key factors:
Local Council and Zoning Rules
Even though state planning policies allow up to 60 square metres, your local council’s rules around setbacks, site coverage, and zoning may reduce the available building area. It’s important to confirm these details early to avoid disappointment.
Design Choices
The way you design your granny flat will also affect its usable size. Open-plan layouts, clever storage solutions, and multi-functional spaces can make a smaller footprint feel larger. If you’re exploring different options, it’s worth looking at a range of 2 bedroom granny flat layouts to see how designs can maximise space.
Attached vs Detached Granny Flats
Whether the granny flat is attached to your main dwelling or built as a standalone structure can influence its size. Attached designs may allow a bit more flexibility by sharing a wall or utilities, while detached granny flats need to meet setback requirements that can limit buildable space.
Can a 2-Bedroom Granny Flat Be Bigger Than 60m²?
While 60 square metres is the standard maximum under NSW rules, some situations may allow you to build larger. For example, if you obtain a Development Application (DA) approval instead of a Complying Development Certificate (CDC), or if you build in a council area with different regulations, you might be permitted to exceed the 60m² limit.
Alternatively, some homeowners explore two-storey designs or build above garages to increase living space without increasing the footprint.
Why Does Size Matter for a 2-Bedroom Granny Flat?
Size has a direct impact on liveability and functionality. A well-designed 2-bedroom granny flat offers enough space for couples, small families, or two unrelated tenants sharing. It also makes the property more appealing for rental, potentially increasing your return on investment.
At the same time, staying within the 60m² limit helps ensure you qualify for a faster approval process and avoid costly compliance issues.
Example Floor Plans and Layout Ideas
Many 2-bedroom granny flats achieve a comfortable living arrangement within 50–60 square metres by focusing on open-plan kitchen and living areas, compact yet functional bathrooms, and smart use of natural light. Common layouts place bedrooms on either side of the living area or side by side with a shared bathroom in between.
Depending on your site, you may also incorporate a small outdoor patio or covered entryway to extend the living space visually without affecting the internal floor area.
Wrapping Up
The average size of a 2-bedroom granny flat in Australia is typically between 50 and 60 square metres, with design, council rules, and site conditions all influencing the final result. Whether you’re building for family, downsizing, or adding a rental income stream, understanding these size guidelines is a crucial first step in the process.
Before you start building, it’s worth exploring design options and checking local requirements to ensure you get the most out of your available space.
