Where required front setbacks are not specified in the relevant district technical specification, the secondary street frontage may be nominated by the applicant, but the nomination must consider the front setback of existing buildings. On a block with existing buildings, the existing building setback is used to determine the primary and secondary frontages.

• – For Single Dwelling, blocks in subdivisions approved originally before 18 October 1993, the secondary street frontage setback is a minimum of 4m for Large blocks and 3m for Mid-sized and Compact Blocks.
• – For Single Dwelling, blocks in subdivisions approved on or after 18 October 1993 but before 31 March 2008, the secondary street frontage setback is a minimum of 4m for Large blocks and 3m for Mid-sized and Compact Blocks.
• – For Single Dwelling, blocks in subdivisions approved on or after 31 March 2008, the secondary street frontage setback is a minimum of 3m for Large and Mid-Sized blocks and 2m for Compact Blocks.
• – For Multi-Unit Housing, all residential zones, the secondary street frontage setback is a minimum of 2m for Large and Mid-Sized blocks.

Reference: Planning (Residential Zones) Technical Specifications 2026 (NI2026-303), Assessment Outcome 14.3- Planning (Residential Zones) Technical Specifications 2026

The ACT building height rules have changed significantly between the 2025 and 2026 planning provisions.

The 2025 rules mainly controlled building height by the maximum number of storeys, with some zones using a maximum height in metres. The 2026 rules move to a height-based system measured in metres above datum ground level and introduce different height limits depending on whether the development is single dwelling housing or multi-unit housing.

This change provides more flexibility for higher-density housing while maintaining lower height limits for individual houses.

Comparison of Building Height Rules

Reference: Reference: Planning (Residential Zones) Technical Specifications 2026 (NI2026-303), Assessment Outcome 14.1- Planning (Residential Zones) Technical Specifications 2026

According to ACT – Advisory Note 09 – Building Heights, Storeys and Basements, building height is measured as the vertical distance from the datum ground level to the highest point of the building.

The datum ground level is the surveyed ground level used as the reference for measuring height and is typically shown on the field survey submitted with a development application. The height measurement includes the highest part of the building, including rooftop elements such as lift overruns, fixed mechanical plant, and rooftop garden structures. It does not include features such as paving, driveways, roads, surface car parks, fences, courtyard walls, retaining walls, or transportable buildings not intended for long-term habitation.

Reference: ACT – Advisory Note 09 – Building Heights, Storeys and Basements – https://www.planning.act.gov.au/__data/assets/pdf_file/0012/2323002/an09-working-out-building-heights-storeys-basements.pdf

Yes. The side and rear building envelope has increased by 500 mm, from 3.5 m under the 2025 specifications to 4.0 m. The building envelope is formed by 45-degree planes projected from a height of 4 m above each side and rear boundary, with all height measurements taken from datum ground level. This requirement does not apply where solar building envelope requirements apply or where the specified exemptions in the Territory Plan apply.

The change in the solar building envelope requirements from 2025 to 2026 also affects maximum building height differently depending on whether the development is a single dwelling or multi-unit housing.

For single dwellings, the solar building envelope remains unchanged with the 31° projection angle, so there is no change to the height control.

For multi-unit housing, the projection angle increases from 31° to 45°, creating a larger buildable envelope and allowing greater design flexibility. However, the final maximum height is still determined by the interaction of the solar envelope, building envelope, height limits, setbacks, and other applicable planning controls.

Reference: Planning (Residential Zones) Technical Specifications 2026 (NI2026-303) – Planning (Residential Zones) Technical Specifications 2026

Yes. The 2026 specifications introduced new stronger solar access and overshadowing rules that could affect a two-storey addition. The main issue is that a new upper floor must be designed so it does not block too much sunlight from neighbouring homes, private outdoor areas, or existing solar panels and solar hot-water systems.

This means a two-storey addition may need changes to its height, setbacks, or location on the block to meet the new requirements. Even if a second storey was previously possible, the new rules may limit how large it can be or where it can be placed if it creates too much overshadowing for adjoining properties.

In simple terms, the new rules could make some two-storey additions harder to approve because they must protect neighbours’ access to sunlight while still allowing the development to proceed.

Reference: Planning (Residential Zones) Technical Specifications 2026 (NI2026-303) Assessment Outcome 15.3-15.5 – Planning (Residential Zones) Technical Specifications 2026

The solar building envelope checks whether a proposed building fits within a set height and location limit to protect sunlight to the site and neighbouring properties.

It is assessed by:

1. Identifying the relevant adjoining residential boundary, especially a northern boundary.
2. Applying the required solar fence height, which depends on the development type and block category:
   • Single dwelling – large block: 2.4 m in the primary building zone and 1.8 m for other areas.
   • Single dwelling – midsized or compact block: 3 m in the primary building zone and 2.3 m for other areas.
   • Multi-unit housing: 3 m in the primary building zone and 2.3 m for other areas.
3. Creating the solar envelope by projecting an imaginary solar plane from the solar fence:
   • 31 degrees for single dwellings.
   • 45 degrees for multi-unit housing.

The proposed building must fit within this envelope to meet solar access requirements.

Reference: Planning (Residential Zones) Technical Specifications 2026 (NI2026-303), Assessment Outcome 15 – Planning (Residential Zones) Technical Specifications 2026 | PDF