When is a dwelling ancillary?

In terms of building approvals, a building is ancillary to a dwelling when it is additional to, but not required for the dwelling to function: the dwelling can operate perfectly well without it.

A dwelling requires the following features: a bedroom, living space, kitchen, bathroom, toilet and washbasin, and laundry. (Many dwellings can also include other optional features such as a study, studio, recreation or hobby room, or garage.)

• If one of more of these required features are missing, then that building is ancillary.
• If one of more of these required features are missing AND the building is used for sleeping in, then that building is an ancillary dwelling.

For example, the following are ancillary buildings:

• A home office with a kitchenette.
• A studio with a bathroom.
• A hobby room or workshop.
• A recreation room with a toilet and washbasin.
• A garage.

And the following are ancillary dwellings:

• A granny flat with a bedroom, living space, kitchenette, bathroom, and toilet.
• A sleepout with a bedroom only.
• A bunkhouse with a bathroom and toilet.

If an additional building has all the required features of a dwelling, it’s no longer ancillary because it can function independently of the main dwelling. So it can be occupied by separate, unrelated people and becomes a second dwelling. Check out our infographic for a nice visual breakdown of this information.

Keep in mind, this definition is for building approvals only. The definition for planning approvals (issued by local councils) may differ, so you should check with your council as to how they might define your second building.