VCONST14130 - Dwellings - an explanation of terms: what ‘designed as a dwelling or number of dwellings’ means: Note 2(b) - internal access to other dwellings
The test is whether there is no direct internal access to another dwelling or part of a dwelling. An example of direct access is a connecting door allowing movement between dwellings.
There is no direct internal access when it isn’t possible to move from one dwelling to another dwelling or part of a dwelling, without first moving across an area outside the dwelling, such as a landing or corridor.