Height, setback and site coverage rules in the ACT

E01 requirement 6 fixes storeys by zone and use. RZ1 is 2 storeys for everything. RZ2 allows 2 storeys for a single dwelling or secondary residence and 3 for multi-unit housing. RZ3 allows 3 for a single dwelling and 4 for multi-unit, RZ4 allows 3 and 6, and RZ5 allows 3 and 7. A secondary residence is 2 storeys in every zone. The Dictionary counts a mezzanine as a storey and excludes attics and basements.

Requirement 7 fixes site coverage for single dwellings by block size: 40% of the block area on a large block, 60% on a mid sized block and 70% on a compact block. The Dictionary sets the bands, a compact block is 250m² or less, a mid sized block is over 250m² up to 500m², and a large block is over 500m². Blocks created by subdividing an original residential block are held to 45% in RZ1 and RZ2 and 50% in RZ3 to RZ5, and the single dwelling figure includes secondary residences and roofed Class 10 buildings.

Requirement 8 caps multi-unit housing at 45% of the original block area in RZ1 and RZ2 and 50% in RZ3 to RZ5. Requirement 9 is the redevelopment rule: where a lawful existing building already exceeds a maximum, a replacement or addition may go to the same maximum if there are no additional adverse impacts on neighbours, including solar access. Site coverage in the ACT includes balconies, basements and roofed terraces and decks, which is broader than most other states.

The metres come from specification 14.1 of the Planning (Residential Zones) Technical Specifications 2026, which commenced on 1 July 2026 and revoked the 2025 specification. RZ1 buildings are a maximum of 8.5m above datum ground level. In RZ2 a single dwelling is 8.5m and multi-unit housing 10.5m. In RZ3 the figures are 10.5m and 14m, in RZ4 10.5m and 21m, and in RZ5 10.5m and 24.5m. The note reminds readers that the storey limits in the Territory Plan apply as well.

Specification 14.2 shapes the building with an envelope. Buildings must sit wholly within planes projected at 45° to the horizontal from a height of 4m above each side and rear boundary, except on boundaries where the solar building envelope applies instead. Flues, chimneys, antennae and cooling or heating appliances may break the plane. The envelope does not apply to single dwellings on compact blocks or to buildings over 3 storeys in RZ5.

Specification 15.1 is the solar building envelope, which protects the northern neighbour. Planes are projected from a solar fence on any northern boundary of an adjoining residential block, and for a single dwelling on a large block the fence is 2.4m high in the primary building zone and 1.8m elsewhere. The angle differs for single dwellings and multi-unit housing, so the specification has to be read for the case at hand.

Setbacks are tables, not single numbers. Specification 14.3 requires front setbacks to comply with tables 1 to 4, and 14.4 requires side and rear setbacks to comply with tables 5 to 11. Which table applies depends on the date the original subdivision was approved, the block size band and whether the housing is single dwelling or multi-unit. The note to the tables is important: a new subdivision does not reset the date, it is based on the original block or estate creation.

Table 3, for single dwellings on blocks in subdivisions approved on or after 31 March 2008, sets the primary front setback at 4m for large and mid sized blocks and 3m for compact blocks, with a 3m or 2m setback to a secondary street. Table 5, for single dwellings on large blocks, sets the lower floor external wall at 1.5m from side boundaries and 3m from the rear, and the upper floor external wall at 3m from a side boundary in the primary building zone and 6m in the rear zone and from the rear boundary.

Specification 14.4(b) adds rules for walls within 900mm of a side or rear boundary: no windows in any part of the wall, and a garage or carport wall on a large block facing the boundary no longer than 8m. Specification 14.5 lists the encroachments allowed into a setback, including eaves up to 600mm, gutters, downpipes and steps up to 1m above ground. The Dictionary measures a setback from the boundary to the outside face of a wall or a roof-supporting post.

Start with the block size band from the Dictionary, because it drives site coverage, the front and side setback tables and the solar fence height. Then confirm the zone from the Part B maps and check the Part D district policy for any requirement that overrides E01. Then find the original subdivision approval date, because tables 1 to 3 and 5 to 7 turn on it.

With those three facts, E01 gives the storey and site coverage limits and the technical specifications give height, envelope and setbacks. If the proposal is a single dwelling that meets the declared development control it may be exempt from a DA altogether. If it is a second dwelling, or it departs from a mandatory requirement, it is a DA and the departure has to be justified against the assessment outcomes.

Where a block sits on Designated Land under the National Capital Plan, none of this applies and the National Capital Authority's controls govern instead. A Casa report states that boundary rather than applying the Territory Plan by default.