Building a granny flat in Brisbane: rules, size limits and approvals

What counts as a secondary dwelling

A secondary dwelling is a self-contained residence on the same lot as your main house. It has its own kitchen, bathroom and living area, and is generally smaller than the principal dwelling. It might be a standalone building, an extension, or a conversion of an existing structure such as a garage.

Under Brisbane City Plan 2014, a secondary dwelling is generally treated as accepted development, meaning it can often proceed without a council development application, provided it meets the relevant size and siting criteria. That is a significant advantage for homeowners, because it usually means your certifier can issue the building approval directly, without a separate planning approval step from council.

Size limits: what is commonly cited

The figure most often quoted for a Brisbane secondary dwelling is a maximum gross floor area of around 80 sqm (check current limits with us). This limit, along with site coverage, height and setback requirements, is what determines whether your proposed granny flat sits within accepted development or needs a full development application.

Because planning scheme thresholds are reviewed and can vary between council areas and even between different parts of the same council area, do not rely on a figure you have seen quoted online or from a neighbour's project. Have your certifier check the specific limits that apply to your lot before you finalise your design.

If your planned granny flat exceeds the accepted development thresholds, for example because of its size, its position relative to boundaries, or overlays that apply to your land such as flood or bushfire risk, it will likely need a development approval from council before a building approval can be issued. This adds a step and generally more time to the process, so it is worth confirming early.

Can you rent it out?

Under Queensland changes introduced in 2022, secondary dwellings can generally be rented out to tenants who are not part of the same household as the occupants of the main house. Previously, many councils restricted secondary dwellings to family members or dependants living on the property. This change has made granny flats a genuinely useful option for homeowners wanting extra rental income or separate accommodation for older or younger family members without being locked into a household-only arrangement.

As with size limits, planning conditions and any specific requirements tied to your property should be confirmed before you commit to a design, particularly if renting the dwelling independently is part of your plan.

The approval process with your certifier

Once your design is ready, the process for getting your granny flat certified generally runs like this:

What we check along the way

A note on separate title and finance

A granny flat cannot be sold separately from the main dwelling on the same title, so it is generally an income or family accommodation option rather than a subdivision strategy. If your plans involve future subdivision or dual occupancy arrangements, that is a different approval pathway with different requirements, and worth raising with your certifier before you design around a granny flat concept.

Key takeaways

If you are planning a granny flat anywhere in Brisbane, Logan, Moreton Bay, Ipswich, Redland or the Gold Coast, our granny flat and secondary dwelling approvals page has more detail on the process. Call our Woolloongabba office on (07) 3112 7689 to talk through your site, or send your plans through our get a free quote page.