Granny flat costs, designs
and build options.
Research a granny flat for your block, budget and the space you need. Explore the guides, compare build options and keep your design ideas, cost assumptions and supplier questions together in a brief you can save.
Before you compare quotes
A useful brief makes your assumptions and unanswered questions visible. Work through the checks that could change your project before choosing a supplier.
- Check the property and intended use
Start with the rules for your state, then confirm the pathway for your property with council or a qualified adviser.
- Separate the home price from the project cost
Record site work, services, approvals and finishing allowances. Calculator results are illustrative assumptions, not a supplier quote.
- Compare the same scope
Use the supplier hub to research build options. Ask what is included, excluded and left for you to arrange.
Compare the project, from budget to design
Costs and build options
A home’s advertised starting price and the cost of a finished project can cover different work. Separate the supply package from delivery, foundations, service connections, approvals and finishing. Ask who organises each stage before comparing quotes.
Research prefab and modular suppliers, DIY kit suppliers and custom builders. The build type comparator helps you record the trade-offs. Dated supplier offers identify their scope and exclusions; calculator allowances are illustrative, rather than a market average or a quote for your block.
Design, site fit and services
Start with the space you need and how it will be used. The planner’s room-zone concepts give you something concrete to discuss with a designer. They are illustrative layouts, not approved construction drawings or confirmation that a design fits your property.
Use the setback and size checker to organise questions about the block, and the metering estimator for service-cost assumptions. Check each assumption with the appropriate professional. The granny flat guides cover design choices, costs and construction questions in more detail.
Start with the rules for your state
Your property and intended use determine which checks matter. Read the state rules comparison, then follow the official sources in the relevant guide. Confirm the planning and building pathway with council or a qualified adviser before committing to a design or supplier.
The approval pathway wizard helps you prepare questions. Its result does not approve a property or replace the applicable authority’s assessment.
Questions before you get started
How much does a granny flat cost in Australia?
There is no single verified national finished-project price on this site. Compare dated supplier prices with their supply stage and exclusions, then obtain site-specific quotes for foundations, services, approvals and fit-out. Our calculator uses illustrative assumptions rather than market averages.
Is a DIY kit always the cheaper option?
A kit can shift assembly and project-management work to you. Compare the complete scope, licensed trades, delivery and site costs, and allow for your time. Ask what is still required to reach a completed dwelling; a supply-only price is not the complete project cost.
Can I take the planner’s concept to a builder?
You can download a concept and print or share your project brief as a starting point for a discussion. The room zones and dimensions are illustrative. A designer and the appropriate professionals need to develop and check the design, site fit, documentation and compliance.
Already researching a specific question? Browse the guides or choose a planning tool.
The Granny Flat Guide is an independent research site. We do not build homes or sell kits. Our editorial standards.
