When you start a new BASIX application, you must select the options that most closely describe the proposed development. Making the correct selections is important as it determines the assessment pathway applied by the BASIX tool (single dwelling, multi-dwelling, or alterations and additions to an existing home).
The assessment pathway determines the options that appear on the Project type page.
You must make either 2 selections (primary and secondary) or 3 selections (primary, secondary and tertiary), and then select ‘Start application’.
Assessment pathway selections
Primary, secondary and tertiary combinations
| Primary selection | Secondary selection | Tertiary selection(s) | BASIX tool assessment pathway applied |
|---|---|---|---|
| One dwelling | The dwelling is on a single lot of land | N/A (i.e. not selected) | Single dwelling |
| One dwelling | The dwelling is on a single lot of land | The lot includes common property and/or the project also includes a secondary dwelling | Multi-dwelling |
| One dwelling | The project involves sub-division or strata title | N/A (i.e. not selected) | Multi-dwelling |
| One dwelling | The project involves sub-division or strata title | The lot includes common property and/or the project also includes a secondary dwelling | Multi-dwelling |
Primary and secondary combinations
| Primary selection | Secondary selection | BASIX tool assessment pathway applied |
|---|---|---|
| Two or more dwellings | At completion, each dwelling will be on a separate lot of land | Multi-dwelling |
| Two or more dwellings | Some or all of the dwellings will be combined on one lot of land (such as dual occupancy or residential flat buildings) | Multi-dwelling |
| Secondary dwelling to an existing house e.g. granny flat | Conversion of a garage, out-building, or other existing non-habitable space | Single dwelling |
| Secondary dwelling to an existing house e.g. granny flat | A new structure (separate or attached to the existing house) | Single dwelling |
| Alteration or addition to an existing house | The project's estimated development cost is $50,000 or more | Alterations and additions |
| Alteration or addition to an existing house | The project includes a pool and/or spa with a combined size of 40,000 litres or more | Alterations and additions |
| Alteration or addition to an existing house | The project includes a secondary dwelling or 'granny' flat | Single dwelling |
| New pool or spa | The pool and/or spa has a combined size of 40,000 litres or more | Alterations and additions |
| New pool or spa | There is other work whose estimated development cost is $50,000 or more | Alterations and additions |
| New pool or spa | The project includes a secondary dwelling or 'granny' flat | Single dwelling |
Important note
Once you make your selections and start the application, the assessment pathway cannot be changed.
Last updated: 29/04/2026