Yes, for a unit-titled dual occupancy. Each dwelling must be covered by a Certificate of Occupancy and Use. ACT Planning specifically requires the most recent certificate for each unit before the unit-title application can be approved.

Reference: ACT Planning: Guide to Unit Titling Process – https://www.planning.act.gov.au/community/buy/leasing-and-titles/unit-titles/guide-to-the-unit-title-application-process

Before either dwelling in a dual occupancy can be occupied, it must be covered by a Certificate of Occupancy and Use for its intended residential use. For building work requiring a certifier, the certifier must first issue the required Certificate of Completion. ACT Planning also notes that completion includes relevant electrical, gasfitting and plumbing work.

It is unlawful to occupy or use a building, or part of a building, without the required Certificate of Occupancy and Use.

Reference: Act Planning: Completion Certificates – https://www.planning.act.gov.au/community/build-or-renovate/upon-completion/completion-certificates

Yes, potentially. One dwelling may be occupied while the other is still under construction if the completed dwelling is covered by an appropriate Certificate of Occupancy and Use.

The Building Act 2004 allows a certificate to be issued for a completed part of a building where that part satisfies the applicable requirements. The remaining uncertified part cannot be occupied.

This means it is not automatic that one dwelling can be occupied simply because it is finished—the required occupancy certification must first be obtained.

Reference: Building Act 2004 (2004-11) – Sections 69(3), Certificates of occupancy & 76, Occupation and use of buildings – https://www.legislation.act.gov.au/View/a/2004-11/current/html/2004-11.html

Not necessarily for every dual occupancy. The current Residential Zones Technical Specifications 2026 does not impose a general requirement that every dual-occupancy site must provide a turning area so vehicles can always leave in a forward direction. The need for vehicle manoeuvring depends on the applicable parking, access and site-design requirements.

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

Certain building elements can extend into the required setback without being treated in the same way as the main building. These include:

• eaves or roof overhangs up to 600 mm;
• fascias, gutters, downpipes, light fittings and sun blinds;
• landings, steps or ramps that are no more than 1 m above finished ground level; and
• for side and rear setbacks only, certain additional elements such as rainwater tanks, clotheslines, hot water systems, chimneys, heating or cooling appliances, utility meters, unroofed pergolas, solar inverters and batteries.

Balconies are not included in the listed allowable setback encroachments, so they should not automatically be assumed to be permitted within the required setback.

Reference: Residential Zones Technical Specifications 2026 (NI2026-303), 14.5 Allowable setback encroachments – https://www.legislation.act.gov.au/View/ni/2026-303/current/PDF/2026-303.PDF

Yes, generally. Site coverage is based on the area of the site occupied by buildings and roofed structures. This means structures such as garages and carports generally contribute to site coverage.

A covered outdoor area may also contribute to site coverage where it forms part of the roofed/built development. By contrast, unroofed areas should not automatically be treated as site coverage merely because they are paved or used as outdoor space.

For a dual occupancy, all relevant roofed structures should therefore be considered when calculating the total site coverage against the applicable limit.

Reference: Residential Zones Technical Specifications 2026 (NI2026-303) – Site Coverage provisions – https://www.planning.act.gov.au/__data/assets/pdf_file/0020/3092411/ACT-Missing-Middle-Housing-Design-Guide.pdf

Not necessarily. Upper-floor windows do not automatically need privacy screens. The design must appropriately address privacy and overlooking under the applicable ACT planning provisions and design guidance.

The Missing Middle Housing Design Guide recommends designing private spaces and openings to minimise overlooking and identifies measures such as building and window positioning, landscaping, louvres, screens, battens and other architectural treatments where additional privacy is needed.

A privacy screen is therefore one possible design solution, rather than an automatic requirement for every upper-floor window.

Reference: Planning (Residential Zones) Technical Specifications 2026 (NI2026-303), Assessment Outcome 16 – https://www.legislation.act.gov.au/View/ni/2026-303/current/PDF/2026-303.PDF & Missing Middle Housing Design Guide 2026,5.2C Privacy and Outlook – https://www.planning.act.gov.au/__data/assets/pdf_file/0020/3092411/ACT-Missing-Middle-Housing-Design-Guide.pdf

Yes. Existing utility easements can significantly affect where a second dwelling in a dual occupancy can be located. Easements protect access to infrastructure such as sewer, water, stormwater, electricity and other services, and the proposed dwelling must respect the applicable access and asset-protection requirements.

For Icon Water infrastructure, the location of easements, pipe protection envelopes, zones of influence and required access ways can restrict where building is permitted. Icon Water specifically advises applicants for homes and dual occupancies to identify these constraints before beginning the design.

For stormwater easements, the restrictions can be particularly important: ACT City Services states that new dwellings and buildings are not permitted within stormwater easements. Footings and foundations adjacent to an easement must also be positioned and designed so they do not load the stormwater pipe or prevent future access and excavation.

Therefore, an easement may require the second dwelling to be repositioned or redesigned, and the relevant utility or infrastructure authority may need to approve works near its assets.

Reference: Icon Water, Applications for Homes and Dual Occupancies and Where Can I Build on My Property? – https://www.iconwater.com.au/Developers-and-Renovators/project-applications-compliance/applications-change

ACT driveway standards prescribe minimum clearances from street trees, utility infrastructure and intersections. For a dual-occupancy driveway, the location should be checked against these clearances before the access is finalised.

• Existing mature street tree: the driveway must be outside the greater of the tree's canopy drip line or the minimum offset specified in MIS 07. In some circumstances, works within the canopy drip line may be considered where they remain outside the Structural Root Zone and appropriate tree-protection measures are demonstrated.
• New or small street tree: the required clearance is determined under MIS 07, Section 2.2.3, based on the applicable tree requirements.
• Power pole, streetlight column, mini-pillar or padmount substation: at least 1.5 m from the outside edge of the asset to the edge of the driveway.
• Ground-level services such as pits and manholes: generally at least 1.2 m clear, although MIS 07 contains asset-specific requirements.
• Intersection: for a block at an intersection, City Services requires the driveway to be at least 6 m clear of the tangent point.

The driveway must also maintain appropriate sightlines to oncoming traffic, taking into account street trees and other structures or obstructions.

Reference: Municipal Infrastructure Standard 07 (MIS 07) Driveways, Edition 1 Revision 2 – Sections 2.1.2 and 2.2.3, Tables 7-1 and associated tree-clearance tables – Municipal Infrastructure Standard 07 Driveways (Edition 1 Revision 2)

Yes, in some circumstances. A neighbour who made a representation during the DA notification period may be able to apply to the ACT Civil and Administrative Tribunal (ACAT) for review of an approved or conditionally approved dual-occupancy DA if the decision may cause them material detriment. A person who had a reasonable excuse for not making a representation may also have review rights in some circumstances.

However, not every dual-occupancy approval can be appealed by a neighbour. The Planning Act 2023 contains specific matters that are exempt from third-party ACAT review. The Notice of Decision should therefore be checked to confirm whether review rights apply to the particular DA.

Where a third-party ACAT review right applies, the application generally must be lodged within 20 working days of receiving the decision.

Reference: ACT planning Amend or appeal an application – https://www.planning.act.gov.au/applications-and-assessments/development-applications/amend-or-appeal-an-application

Yes, potentially. The two dwellings in a dual occupancy do not necessarily have to be the same size.

For an RZ1 dual occupancy on a standard block proposed for unit titling, the Subdivision Policy requires one dwelling to have a maximum dwelling size of 120 m². This requirement applies to one dwelling only, so the other dwelling may be larger, subject to all other applicable planning requirements. ACT Planning likewise explains the rule as requiring “one dwelling” to be no more than 120 m².

Reference: ACT Territory Plan, F01 Subdivision Policy – Territory Plan 2023 | Notifiable instruments

Not generally. There is no single maximum floor area that applies to each dwelling in every dual occupancy. The allowable size depends on the zone and the applicable planning controls.

A specific 120 m² dwelling-size limit is relevant to certain RZ1 dual occupancies. For example, where an RZ1 dual occupancy on a standard block is proposed for unit titling, the applicable subdivision provisions require the block to be at least 800 m² and one of the dwellings to have a maximum dwelling size of 120 m². The 120 m² limit applies to one dwelling, not both dwellings.

The size of the overall dual occupancy is also affected by other applicable planning controls, including site coverage, setbacks and building height.

Reference: ACT Territory Plan, Part F01 Subdivision Policy – Assessment Requirement 14 – Territory Plan 2023 | Notifiable instruments

Possibly. If a Development Application is amended during assessment, ACT Planning will determine whether the changed application needs further public notification.

If further notification is required, the amended application is notified again using the applicable notification methods, and people who made a representation on the original DA must be notified in writing. The public can then make further representations on the changes.

Further public notification may be waived where ACT Planning is satisfied that the changes result in no or only a minimal increase in the adverse or environmental impacts of the development.

Reference: ACT Planning, After you Apply, Further entity referrals and further public notification – https://www.planning.act.gov.au/applications-and-assessments/development-applications/after-you-apply

Yes, potentially. An existing driveway can be retained as part of a dual-occupancy development where it is suitable for the proposed development and meets the applicable access requirements.

ACT Planning specifically confirms that, for an RZ1 dual occupancy, an existing driveway may be retained as common property for use by both dwellings where the development is unit titled.

If the existing driveway needs to be modified or upgraded, additional driveway approval requirements may apply. ACT Planning distinguishes between constructing a new driveway, adding a second driveway and modifying an existing driveway.

Yes, potentially. An existing garage, shed or other Class 10 structure does not automatically have to be demolished simply because a dual occupancy is proposed.

It may remain where it can be incorporated into the proposed development and the overall dual occupancy complies with the applicable ACT planning requirements. Existing Class 10 structures should therefore be shown on the development plans and considered as part of the overall site design, including their relationship to the new dwellings, parking, setbacks and other applicable requirements.

The existing structure should also have the necessary approval or lawful status. ACT Planning separately recognises garages and sheds as Class 10a buildings and provides specific DA and BA exemption criteria for these structures.

Reference: 

Not necessarily. A dual occupancy must demonstrate compliance with the ACT’s applicable water-efficiency requirements, including a target of 40% reduction in mains water use compared with an equivalent development constructed in 2003.

ACT Planning treats dual occupancy as multi-unit residential development for this assessment—the Multi-unit Waterways Calculator specifically covers developments from dual occupancy through to multi-storey apartments. The calculator considers rainwater tanks alongside other water-saving measures, including water-efficient fixtures and greywater systems.

Therefore, a rainwater tank is not automatically required simply because the development is a dual occupancy. A tank may form part of the design used to demonstrate compliance with the required water-efficiency target.

Reference: ACT Planning, Water Efficiency – https://www.planning.act.gov.au/professionals/regulation-and-responsibilities/responsibilities/water-efficiency

Not necessarily a requirement for a physical fence between the two dwellings. For a dual occupancy, the ACT planning framework focuses on providing appropriate privacy, private open space, landscaping and separation rather than imposing a blanket rule that the dwellings must be divided by a boundary fence.

The Missing Middle Housing Design Guide recognises dual occupancies with private yards as well as shared/common areas, such as landscaping associated with a shared driveway. This means the appropriate treatment between the dwellings will depend on the proposed layout and how private and shared spaces are designed.

Where a fence is proposed, separate planning requirements may apply to the location and height of the fence, particularly where it is near the street/front boundary. ACT Planning notes that fences within the area between the front boundary and building line are generally not DA-exempt under the standard fencing exemption.

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

Yes. For a driveway serving a dual occupancy, the driveway width is determined by the designer based on the development, but it must not exceed 5.5 m at the property boundary or kerb.

Unlike driveways serving a single dwelling, the standard does not specify a fixed minimum driveway width for two or three dwellings. The appropriate width is instead assessed by the designer. Where additional width is needed—for example, to allow two vehicles to safely pass in opposite directions—the driveway may be designed wider, but cannot exceed the 5.5 m maximum. The width at the property boundary also cannot be greater than the width at the kerb.

Reference: Applicable ACT driveway requirements – Municipal Infrastructure Standard 07 (MIS 07) Driveways, Edition 1 Revision 2 – Section 2.3.2 – Municipal Infrastructure Standard 07 Driveways (Edition 1 Revision 2)

Not always. For a dual-occupancy DA, shadow diagrams are required if relevant or requested by ACT Planning, including where requested at a pre-application meeting.

Whether they are needed will therefore depend on the particular proposal and its potential overshadowing impacts.

Reference: ACT Planning (Minimum Development Application Documentation) Guideline 2026 (No 1) (NI2026-13) 

If you're converting a normal residential block into a dual occupancy, you do not automatically need an OSD tank.

The important question under the current Residential Zones Technical Specifications is the size of the site.

For example:

• 800 m² block + dual occupancy → the >2,000 m² OSD rule does not apply.
• 1,200 m² block + dual occupancy → the >2,000 m² OSD rule does not apply.
• 2,500 m² block + development that changes the stormwater runoff → the stormwater detention requirements apply.

This is important because the older WSUD material contained a 100 m² increase in impervious-area trigger. I would not use that old 100 m² trigger as the current Territory Plan requirement for your 2026 dual-occupancy assessment.

You still need to properly design the property's stormwater drainage — roof water, gutters, downpipes, connection/discharge points, etc. Not requiring OSD does not mean there are no stormwater requirements.

Reference: Planning (Residential Zones) Technical Specifications 2026 (NI2026–303), Assessment Outcome 24.5 Stormwater Retension and Detention – Planning (Residential Zones) Technical Specifications 2026 | PDF

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

For a dual occupancy, the plans should give the planner enough information to understand where the existing services are and whether the new dwellings will interfere with them.

This can include things such as sewer, stormwater, water, electricity and other existing/proposed utility infrastructure, particularly where they affect where you can put the dwellings, driveway, retaining walls or landscaping.

You don't necessarily need a separate complicated engineering utilities drawing for every DA. The utility information can sometimes be incorporated into the relevant plans. ACT's DA naming guidance specifically says that a Utilities Services Plan details existing and proposed utility services.

The important practical issue is clearances. For example, if a sewer line or utility easement runs through the block, you can't simply draw a dwelling over it because the building otherwise meets the planning setbacks. Utility access and protection requirements still need to be dealt with. ACT Planning expressly recognises easements, utility infrastructure access/protection spaces and plumbing/drainage clearances as separate constraints.

So for a dual occupancy DA, I would normally want the site documentation to identify any utility infrastructure that could affect the proposed development, rather than leaving it until building approval.

Reference: Planning (Minimum Development Application Documentation) Guideline 2026 (No 1) (NI2026–13)

Think of site coverage as how much of the block is physically covered by buildings or covered structures when viewed from above.

For a dual occupancy, the following are specifically identified as included:

• Balconies
• Basements
• Roofed structures such as carports, terraces, pergolas, patios, decks and garden sheds
• Cantilevered upper-floor elements

The following are specifically excluded:

• Awnings and eaves
• Unroofed decks, terraces, pergolas and patios
• Swimming pools
• Hard surfaces such as retaining walls and driveways

The lists are not exhaustive.

Site coverage is measured from the external faces of exterior and basement walls. For balconies, terraces, pergolas and similar structures, the furthest extent of the structure is generally used.

Reference: ACT Planning Advisory Note 08 – Working out gross floor area and site coverage – https://www.planning.act.gov.au/__data/assets/pdf_file/0011/2323001/an08-working-out-gross-floor-area-site-coverage.pdf

In practical terms, notification may be sent to:

• neighbours beside your property;
• neighbours behind your property;
• relevant neighbours directly across the street; and
• potentially other nearby neighbours if ACT Planning considers they could be affected by the proposal in a similar way.

The exact neighbours notified therefore depend on the shape and location of the block and the surrounding properties.

Reference: ACT Planning: Development Application Public Notification and Representations – https://www.planning.act.gov.au/__data/assets/pdf_file/0015/2323014/development-application-public-notification-representations.pdf

The Landscape Plan shows how the areas around both dwellings will actually be landscaped, rather than simply showing the buildings.

It should show relevant details such as proposed planting, plant species and quantities, planting sizes and locations, together with other required landscape information. ACT Planning also describes the Landscape Plan as showing trees to be retained, their size/height, protection measures and surface treatments.

So for a dual occupancy, landscaping shouldn't just be labelled “landscaped area” on the site plan—the DA should include the required Landscape Plan information.

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