What happens if the proposal meets the Technical Specifications but not the Design Guide?
Technical Specifications = measurable numbers
Things like setbacks, building height, site coverage, private open space dimensions, etc.
Design Guide = quality of the design
Things like whether the development fits the neighbourhood, provides good privacy, has sensible entrances and landscaping, gives residents good amenity, and responds appropriately to adjoining properties.
So you could have a dual occupancy that ticks all the numerical boxes but still has a design problem.
For example, imagine the Technical Specification allows a particular setback and your proposal meets it exactly. However, the resulting second storey has a poor relationship with the neighbouring property.
The Authority can still look at the Design Guide and the underlying Assessment Outcome. Simply saying “we comply with the setback number” may not resolve the broader design issue.
On the other hand, not following a particular Design Guide suggestion does not automatically mean refusal. Alternative design solutions are possible if you can demonstrate that your proposal still comprehensively achieves the relevant Assessment Outcome. ACT Government guidance specifically recognises alternative approaches.
Reference: ACT Planning , The Territory Plan – https://www.planning.act.gov.au/professionals/our-planning-system/the-territory-plan
Short Answer
Meeting the Technical Specifications does not automatically mean the proposal will be approved if it does not adequately address the applicable Design Guide.
The key legal test is whether the proposal meets the relevant Territory Plan Assessment Outcomes and mandatory Assessment Requirements. Technical Specifications provide measurable benchmarks; Design Guides help demonstrate good design and achievement of those outcomes.
Detailed Explanation
Under the ACT's outcomes-focused Territory Plan, the fundamental requirements are the applicable Policy Outcomes, Assessment Outcomes and Assessment Requirements in the relevant District and Zone Policies. Assessment Requirements are mandatory controls.
The Planning (Residential Zones) Technical Specifications 2026 (NI2026-303) are made under s 51 of the Planning Act 2023. The Planning (Missing Middle Housing) Design Guide 2026 (NI2026-312) is separately made under s 50 and applies from 1 July 2026.
The important distinction is:
Technical Specifications → benchmark/possible solution.
They provide measurable and quantitative guidance for demonstrating an Assessment Outcome.
Design Guide → design response/guidance.
For developments to which the Missing Middle Housing Design Guide applies — including relevant dual and multi-occupancy housing — the proposal must demonstrate how the relevant design guidance has been considered. The Authority uses both the Design Guide and Territory Plan requirements when assessing the DA.
Therefore, compliance with NI2026-303 is strong evidence toward satisfying the relevant Assessment Outcome, but it should not be treated as blanket approval of the entire design. If the Design Guide identifies an issue that shows the underlying Assessment Outcome has not been achieved, the Authority can require that issue to be addressed. Conversely, departure from a Design Guide solution can be acceptable where the alternative design is properly justified and still comprehensively achieves the Assessment Outcome.
Practical rule for your dual-occupancy questions:
Assessment Requirement = must comply. Technical Specification = strong measurable pathway. Design Guide = must be properly considered/responded to where applicable. Assessment Outcome = ultimately must be achieved.
No minimum block size does not remove the need for planning assessment.
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