Yes, in limited circumstances. A Development Approval generally lasts for 5 years after it takes effect. An application to extend the approval can be made within 6 months after the end of that 5-year period, but the development must have started and substantially progressed, and the development would still need to be approvable if a DA were lodged at the time of the extension application.

Extensions can be granted more than once, but generally for a combined maximum of 2 additional years.

If the development has not started and substantially progressed, this extension pathway would not satisfy the stated requirements, and a new DA would generally be needed to proceed.

Reference: ACT Possible Outcomes – https://www.planning.act.gov.au/applications-and-assessments/development-applications/after-you-apply/possible-outcomes

Generally, no. The age of the existing house by itself does not determine whether a dual occupancy can be approved. The application is assessed against the current planning requirements applying to the block and proposed development.

The ACT Missing Middle Housing Design Guide specifically illustrates a detached dual occupancy that retains the existing dwelling, showing that retaining an older/existing house is contemplated.

However, the age of the house may become relevant if it has heritage protection or other site-specific constraints. Heritage requirements can affect alterations, additions, new buildings, demolition, landscaping, site coverage and setbacks.

Reference: ACT Missing Middle Housing Design Guide – ACT Missing Middle Housing Design Guide

Yes, potentially. Having an easement on your block does not automatically prevent a dual occupancy, but it can restrict where buildings and other structures can be located.

An easement gives another person or organisation rights to use or access part of the land—for example, for stormwater, sewer, water, electricity or access.

If the proposed development affects an easement, the easement and relevant infrastructure must be considered in the design. For example, Icon Water states that permanent structures cannot be built over easements affecting its infrastructure/access, and appropriate access and clearances must be maintained.

Therefore, the dual occupancy may need to be positioned or redesigned around the easement, and approval or written consent from the relevant utility/infrastructure provider may be required where the proposal affects its easement or assets.

Reference: ACT Planning – Easements – https://www.planning.act.gov.au/community/get-to-know-your-block/surveying-a-boundary/easements

Yes, potentially. Having protected or regulated trees on the block does not automatically prevent a dual occupancy, but the development must be designed to appropriately retain and protect trees where required.

ACT Planning says existing regulated or registered trees need to be identified when preparing a development proposal. Depending on the works, you may need an arborist's tree survey/report and a Tree Management Plan.

The Missing Middle Housing Design Guide – 3.3D Tree Retention also recommends conducting a tree survey, incorporating significant existing trees into the site design, establishing appropriate protection zones around retained trees, and protecting them during construction.

If the proposed building, excavation, driveway or other works would affect a protected tree, the design may therefore need to be adjusted around the tree, or the appropriate approval obtained for works affecting it.

Reference: ACT Missing Middle Housing Design Guide – 3.3D Tree Retention – ACT Missing Middle Housing Design Guide

It depends on the easement. An easement can restrict where a dual occupancy, driveway or other structures can be located, so it should be identified and considered when designing the development.

For a dual-occupancy DA, the requirements depend on the purpose of the easement and the entity responsible for it. You may need to maintain required clearances, obtain advice or approval from the relevant entity, or redesign the development so it does not interfere with the easement. ACT Planning specifically identifies utilities and easements as matters that should be considered when preparing a DA.

Reference: ACT Planning – Easements – https://www.planning.act.gov.au/community/get-to-know-your-block/surveying-a-boundary/easements

Building height on a sloping block is measured from Datum Ground Level (DGL) to the highest point of the building.

ACT Planning’s Advisory Note 09 specifically explains that DGL is the base used for calculating building height. It is determined from an authorised field survey from the time of subdivision or grant of the lease. If that information is unavailable, a registered surveyor determines the best estimate having regard to surrounding ground levels. For a DA, the DGL is normally shown on the field survey submitted with the application.

This means the building height on a sloping site is assessed against the surveyed DGL, rather than simply measuring from the lowest or highest point of the current ground.

Reference: ACT Advisory Note 09 – Building Heights, Storeys and Basements – Building heights, storeys and basements

Generally, no. A driveway or other hard-paved vehicle area should not be counted as planting/landscaped area where the applicable Territory Plan requirement is specifically for planting area.

The current Residential Zones Technical Specifications 2026 (NI2026-303) distinguishes planting areas from driveways, parking and other hard-surfaced areas. For dual-occupancy/multi-unit development, the required planting area must be capable of supporting planting and tree canopy, so ordinary driveway paving cannot simply be included in that calculation.

Some forms of landscaping or specially designed permeable surfaces may serve other environmental or site-design purposes, but that does not automatically make them qualifying planting area.

Planning (Residential Zones) Technical Specifications 2026 (NI2026-303) – Planning (Residential Zones) Technical Specifications 2026 | PDF

Yes. Existing trees that are retained can count toward the applicable tree planting and canopy-cover requirements. Where an existing tree is relied on for canopy cover, it must meet requirements relating to tree health, protection during construction, adequate deep-soil area and suitable location.

Reference: Planning (Residential Zones) Technical Specifications 2026 (NI2026-303) – https://www.legislation.act.gov.au/View/ni/2026-303/current/PDF/2026-303.PDF

A deep soil zone is an area of soil that provides sufficient space and soil conditions to support the healthy growth and retention of trees, including their root systems.

For a dual-occupancy development, deep-soil provision is relevant where trees are being provided or retained to meet the applicable tree planting and canopy-cover requirements. The required area should therefore be determined from the applicable tree and canopy provisions and the particular trees proposed or retained.

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

For a dual occupancy, privacy between the two dwellings should be considered as part of the overall design. The Missing Middle Housing Design Guide provides general guidance for multi-dwelling development on minimising overlooking between dwellings, balconies and private open spaces, including through appropriate siting, landscaping, fencing and screening.

These are design considerations applicable to missing-middle housing generally, rather than privacy rules written specifically for dual occupancy.

Reference: Planning (Missing Middle Housing) Design Guide 2026 – 5.2C Privacy and Outlook – ACT Missing Middle Housing Design Guide

You can find your property's zoning using ACTmapi, the ACT Government's official online mapping tool. Search for your property and use the Territory Plan Map to view its zone, such as RZ1 – Suburban Zone or another residential zone. ACT Planning specifically recommends ACTmapi for finding a block's zone details and potential site considerations.

Once you know the zone, check the Territory Plan to determine what development is permitted and which planning requirements apply to the property.

An Assessment Requirement is a specific requirement in the Territory Plan that must be met for the development to be approved. These can set defined controls for matters such as building height, setbacks or other development limits. ACT Planning describes zone policies as containing the assessment requirements that must be met.

An Assessment Outcome describes the result the development is expected to achieve rather than prescribing only one way of achieving it. There is generally more flexibility in demonstrating how the proposal satisfies an Assessment Outcome.

Reference: ACT Territory Plan – Territory Plan 2023 | Notifiable instruments

Yes. During assessment, ACT Planning can identify parts of a Development Application that do not meet the Territory Plan requirements and provide pre-decision advice recommending changes to the design. The applicant can then amend the DA or ask ACT Planning to decide the application as originally submitted; if the identified issues are not resolved, the application may be refused.

ACT Planning can also conditionally approve a DA and require changes to plans or drawings. Those amended documents may need to be submitted to the Authority for review and endorsement before development starts or before the approval takes effect.

Reference: ACT: After you apply – https://www.planning.act.gov.au/applications-and-assessments/development-applications/after-you-apply

If a pipe runs underneath the proposed dwelling, first determine what the pipe is and who owns it.

• Sewer: Icon Water controls ACT water/sewer network assets. Alteration or relocation may be possible with Icon Water approval, although not all assets can be altered and approved works are generally at the applicant’s expense.
• Municipal stormwater: A new dwelling/building is not permitted within a stormwater easement. City Services does, however, have an approval process covering infrastructure relocation or removal.
• Private drainage: This may potentially be redesigned or relocated as part of the development’s plumbing/drainage design.

Importantly, moving the pipe does not automatically remove its easement. An existing easement may need to be legally changed or extinguished separately.

Reference: ACT City Services, Stormwater Applications – https://www.cityservices.act.gov.au/plan-and-build/building-works/stormwater-applications & Icon Water, Relocate or Alter a Service – https://www.iconwater.com.au/Developers-and-Renovators/Relocate-or-alter-a-service

There isn't a general rule saying every dual-occupancy dwelling must be at least, for example, 80 m² or 100 m².

You can therefore have one dwelling smaller than the other, provided both dwellings still achieve the applicable requirements for things such as private open space, parking, solar access, amenity and building design.

There is an important exception to keep in mind: specific size controls can apply for particular purposes. For example, ACT planning requirements have included a 120 m² maximum (excluding garage) for one dwelling in certain RZ1 dual-occupancy unit-title arrangements.

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

The DA needs to show how soil, mud and sediment will be kept on the property during construction instead of washing onto the road or into stormwater drains.

For sites under 3,000 m², the plan should show at least:

• sediment controls, such as sediment fencing;
• a stabilised site access point;
• a designated cutting/wash area; and
• the water-flow path, such as contours.

For a simple dual occupancy, this information can be shown on another plan rather than requiring a completely separate drawing. More complex developments may require a separate Erosion and Sediment Control Plan.

Reference: ACT Minimum DA Documentation Guideline 2026 (NI2026-13)

The DOR is essentially the document that explains why your dual-occupancy proposal should be approved under the Territory Plan.

Rather than just submitting drawings, the report explains how the proposal responds to the relevant planning requirements and Assessment Outcomes.

For a dual occupancy, the documentation guideline also separately identifies a Design Response as required. So the DOR and Design Response should not be assumed to be the same document.

Reference: ACT Minimum DA Documentation Guideline 2026 (NI2026-13)

Yes. ACT Planning can approve a Development Application subject to conditions that require changes to the plans or other documents originally submitted.

These conditions are generally used to make sure the development is consistent with the Territory Plan or relevant entity advice. You may need to amend a plan, drawing or other document and submit it to the Territory Planning Authority—or a relevant entity—for review and endorsement. Minor changes may sometimes be annotated directly on the approved plans.

Reference: ACT: Possible Outcomes – https://www.planning.act.gov.au/applications-and-assessments/development-applications/after-you-apply/possible-outcomes

Yes. You can withdraw a Development Application at any time before ACT Planning decides it. If major design changes are needed, withdrawing and lodging a new DA may be necessary where the revised proposal is too different from the original application. Under the Planning Act 2023, an applicant may withdraw a DA at any time before it is decided.

Before withdrawing, you may be able to amend the existing DA instead. However, ACT Planning will only accept an amendment where the amended development is substantially the same as the original proposal and satisfies the other amendment requirements. If the changes are not substantially the same, ACT Planning states that a new DA is required for the amended proposal.

Reference: Planning Act 2023 – section 183, Withdrawal of development applications – https://www.legislation.act.gov.au/View/a/2023-18/current/html/2023-18.html

No. A neighbour’s objection—formally called a representation—does not automatically prevent a Development Application from being approved.

ACT Planning must consider representations made during the public notification period, particularly where they raise relevant planning issues such as privacy, solar access or traffic. However, ACT Planning expressly states that a DA decision is not based on the number of representations received; it is the content and planning relevance of the representations that matters.

A relevant objection may result in ACT Planning requesting further information, imposing conditions, requiring changes, or ultimately refusing the proposal—but an objection by itself does not determine the outcome.

Reference: ACT Planning – After You Apply – Planning Act 2023

Generally, no. If the demolition requires Building Approval (BA), the BA must be issued before the demolition work can start. ACT Planning states that most building projects involving demolition require BA.

After the BA is issued, the builder must also obtain a commencement notice from the building certifier. Building work can start once that notice has been issued.

However, some demolition work can be exempt from BA. ACT Planning states that demolition is BA-exempt where the building would be exempt from BA if it were built today and the work satisfies the other applicable general exemption rules.

Reference: ACT: Building Approvals – https://www.planning.act.gov.au/applications-and-assessments/building-approvals

Generally, no, if the site works or excavation form part of building work requiring Building Approval. ACT Planning states that building work can start once the commencement notice has been received.

For a dual-occupancy project, excavation for foundations, footings or other construction forming part of the approved building work should therefore not start before the required BA and commencement notice are in place.

However, not every activity carried out on a site is necessarily “building work.” Whether preliminary works can occur earlier depends on what the work involves, whether it requires a separate approval, and any conditions of the Development Approval that must be satisfied before construction starts. ACT Planning specifically says DA conditions may impose requirements that must be met before any construction or building work can start.

Reference: ACT: Building Approvals – https://www.planning.act.gov.au/applications-and-assessments/building-approvals

Yes. You can change builders after Building Approval (BA) has been issued. ACT Planning’s building approval guideline expressly states that a BA is issued to the landowner, not to a particular builder, and that the owner may decide to change builders after approval is issued.

However, if a building commencement notice has already been issued for the existing builder, the change must be properly dealt with before the new builder carries out the work. The new licensed builder will generally need to be appointed and obtain the appropriate commencement notice for the work. The current approved form is AF2025-14 – Appointment of builder and application for commencement notice.

Reference: Building Act 2004—Form—Appointment of builder and application for commencement notice – https://www.legislation.act.gov.au/af/2025-14/

Yes. A landowner can change the building certifier after construction has started. The Building Act 2004 specifically allows an eligible certifier to be appointed where building work has already begun, provided the work has been carried out in accordance with the relevant requirements.

The landowner, not the builder, is responsible for appointing the certifier. The existing appointment must be properly ended and a suitably licensed replacement certifier appointed to take over the certification and inspection responsibilities for the remaining work.

Reference: Building Act 2004(2004-11), Sections 19A and 19D – https://www.legislation.act.gov.au/View/a/2004-11/current/html/2004-11.html

For a dual occupancy, the building certifier must inspect the work at prescribed stages. For Class 1 residential buildings, these generally include:

• Footings: after excavation, formwork and steel reinforcement are completed, but before concrete is poured.
• Reinforced concrete: after formwork and reinforcement are completed and before concrete is poured.
• Structural frame: after the structural framework is completed and before internal linings are installed.
• Final inspection: when the building work covered by the Building Approval is completed.

The certifier may require additional inspections depending on the project. Separate mandatory ACT Government inspections also apply to relevant electrical, plumbing, drainage and gasfitting work.

Reference: ACT Planning : During Construction, Inspections – https://www.planning.act.gov.au/community/build-or-renovate/during-construction