Granny flat rules in the ACT

The E01 Residential Zones Policy applies to all development in the residential zones RZ1 to RZ5. Its Land Use Table marks each permissible use with a Y, and secondary residence carries a Y in all five columns. The table's preamble is the operative rule: listed uses require development approval unless they meet the exempt development definition in the Planning Act, and uses not listed are prohibited.

Because a secondary residence is a listed use, it is neither prohibited nor free of approval. It sits in the middle category, assessable development, which under section 143 of the Planning Act needs development approval. The next section explains why the exempt route is closed to it in every case.

District policies can add or remove uses in specific locations, and the Land Use Table says so expressly. Before relying on the zone table, the Part D district policy for the block should be read, because a district assessment requirement prevails over the zone policy where the two conflict. Blocks on Designated Land under the National Capital Plan are outside the Territory Plan altogether.

E01 sets three assessment requirements for secondary residences, and assessment requirements are the mandatory controls in the Territory Plan. First, a secondary residence is developed only in association with single dwelling housing. A block already used for multi-unit housing cannot add one. Second, the maximum dwelling size is 90m². Third, there is a maximum of one secondary residence per block.

The 90m² is measured in a particular way. The note to the requirement says dwelling size is the floor area measured to the outside face of external walls, including internal walls between the living areas and garage, but excluding the garage. So a garage attached to the flat does not eat into the cap, while wall thickness does.

The technical specifications add a floor. Specification 5.1 sets the minimum gross floor area of a secondary residence at 40m². Specifications are benchmarks rather than mandatory controls, so a smaller flat is not automatically refused, but the applicant then has to show the relevant assessment outcome is met another way.

For site coverage, storeys and building height, a secondary residence is treated as part of the single dwelling. The site coverage note in E01 says single dwelling includes all secondary residences and associated roofed Class 10 buildings, and the storey limits give a secondary residence 2 storeys in every zone. The height and setback guide covers those figures.

The Planning (Exempt Development) Regulation 2023 exempts a long list of residential work from development approval, including a compliant new single dwelling. Every exemption in Schedule 1 has to pass the general criteria in Part 1.3, and criterion 5 is decisive here: development must not increase the number of dwellings on a block to 2 or more dwellings. A secondary residence does exactly that, so no exemption can apply to it.

The result is that a granny flat in the ACT is always a development application to the Territory Planning Authority under section 166 of the Planning Act, assessed against the E01 assessment outcomes and requirements, the district policy and the technical specifications. The application also has to be consistent with the Crown lease for the block, and a lease that permits only one dwelling may need a lease variation first.

Section 150 of the Act confirms what exempt status would have saved: an exempt development needs no development application, no development approval and no exemption assessment. None of that relief is available for a second dwelling. Building approval under the Building Act 2004 is a separate step that applies either way.

The F01 Subdivision Policy closes the last question. Assessment requirement 5 says subdivision is not permitted to provide separate title, including subdivision under the Unit Titles Act 2001, to a secondary residence in any zone. A granny flat cannot be unit titled and cannot be cut off as its own block.

That rule is what separates the secondary residence pathway from dual occupancy. If two independent, separately saleable dwellings is the goal, the proposal has to be framed as multi-unit housing from the start, and the dual occupancy guide sets out the density, site coverage and unit titling rules for that. A secondary residence is the simpler approval precisely because it stays tied to the main house.

For an owner, the trade is clear. A secondary residence gives a second dwelling of up to 90m² on any residential block with a DA and no subdivision. A dual occupancy gives two full dwellings with the possibility of separate titles, at the cost of the tighter multi-unit rules.