A granny flat and a duplex can both provide two dwellings, but they are not interchangeable planning descriptions. In Queensland, a secondary dwelling is used with and subordinate to another dwelling on the lot. A dual occupancy is a different use. Confirm which proposal you are making before relying on a design or rental estimate.
Compare the intended outcomes
| Question | Secondary dwelling | Dual occupancy |
|---|---|---|
| Relationship | Subordinate to the main dwelling and used in conjunction with it. | Two dwellings falling within the dual-occupancy definition. |
| Scale and design | Local controls govern size and other requirements; it is not simply another full-sized home labelled a granny flat. | Check the scheme’s dual-occupancy provisions and assessment pathway. |
| Occupation | Queensland permits unrelated occupants, subject to the relevant lawful approval position and other requirements. | Occupation must accord with the applicable approvals and requirements. |
| Separate ownership | Do not assume subdivision or separate title is available. | A separate-title proposal needs its own planning, survey and legal assessment. |
Can a granny flat be rented to someone outside the family?
Queensland changed the state definitions in September 2022 to allow secondary dwellings to be occupied by people unrelated to the main household. That change did not remove relevant planning, building or fire-safety requirements. If an older development approval restricts occupancy, investigate whether its conditions need to be changed before relying on the new rental arrangement.
Check local rules and existing approvals
Review zoning, overlays, the building’s approved status, dimensions, access, parking and any approval conditions. Noosa and Sunshine Coast have their own provisions. Noosa’s guidance distinguishes permanent occupation of a secondary dwelling from short-stay accommodation and explains that it remains on the main property’s title. Do not treat permission for permanent rental as permission for Airbnb or visitor accommodation.
Converting a garage or buying a modular unit
The way the building is supplied does not settle its approval requirements. A garage, studio or shed may not be approved for habitation. A prefabricated dwelling must still meet applicable siting, building and plumbing requirements. Involve a building certifier early to identify matters such as fire separation, sound transmission and the suitability of the existing structure.
Test the complete cost and layout
- Show both dwellings, floor areas, private outdoor areas and access.
- Check the main home’s required parking and how the additional occupants will use the site.
- Establish plumbing, sewer, drainage, water and electricity requirements.
- Obtain current advice on infrastructure charges or any relevant concession; do not assume all councils apply the same treatment.
- Compare the scheme and building requirements before purchasing a unit or accepting a construction quotation.
Illustrative example: an owner wants a second home of similar size to the existing house. The design may need assessment as a dual occupancy rather than a subordinate secondary dwelling. Renaming it a granny flat does not establish the appropriate pathway.
Send the address or lot/plan reference, existing approvals and a sketch showing the proposed size, location and intended occupation. Planco can identify the planning questions and coordinate with your designer and certifier on the next steps.
Related planning advice
General Queensland planning guidance. Updated 29 October 2026. Requirements depend on the applicable municipal or council planning controls, approval history and property. Confirm the current position before committing to work or a purchase.