How are setbacks measured on an irregular boundary?
The setback follows the actual shape of the boundary. If the boundary is angled, curved or changes direction, you measure the distance from that boundary to the building at the relevant points.
This means an irregular block can have different setback distances at different points along the same building, particularly where the building and boundary are not parallel.
Example: If a side boundary angles toward the house, the setback becomes smaller as the boundary gets closer. The design therefore needs to be checked at the point where the building is closest to that boundary.
A registered surveyor establishes the accurate block boundaries so that the proposed building can be correctly positioned and its setbacks checked. ACT Planning specifically states that survey information is used to ensure development complies with building setback requirements.
Reference: Territory Plan 2023 | Notifiable instruments
Short Answer
On an irregular-shaped block, the setback is measured horizontally from the relevant block boundary to the outside face of the building or structure. Because an irregular boundary may change direction, the setback needs to be checked against the actual surveyed boundary at the relevant location, rather than assuming one uniform measurement across the site.
Detailed Explanation
The Territory Plan defines setback as the horizontal distance between a block boundary and the outside face of a building or structure.
Accordingly, an irregular boundary does not create a different method of calculating a setback. The applicable setback is still measured from the legally defined block boundary to the relevant outside face of the proposed building or structure.
Where the boundary changes direction, the setback should therefore be checked against the relevant boundary segment and at the locations necessary to demonstrate that the minimum required setback is maintained.
The boundary itself should be established by survey. ACT Planning's Survey Certificates guidance states that a registered surveyor can establish accurate block boundaries and that a survey certificate shows the boundaries of the land and location of each building or structure.
No minimum block size does not remove the need for planning assessment.
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