The difference between these residential development types is that a secondary residence is a second dwelling on a block that remains subordinate to the principal dwelling on that block, whereas dual occupancy housing is the use of land that was originally used or leased for single dwelling housing for two dwellings. In contrast, a townhouse development generally consists of multiple dwellings arranged as individual homes within one development site, usually involving a higher density of residential development than a dual occupancy.

Reference: Territory Plan 2023, Part G – Dictionary – Territory Plan 2023 | Notifiable instruments

Residential Zones Policy Land Use Table permits secondary residence for residential zones. The proposal must also comply with the relevant assessment requirements and obtain any required approval under the Planning Act 2023 (ACT).

Reference: Territory Plan 2023 – Part E, E1 Residential Zones Policy (Land Use Table) – https://www.legislation.act.gov.au/ni/2023-540/Current

A secondary residence (granny flat) cannot be sold separately because it is a smaller dwelling that is subordinate to the main dwelling and remains on the same title.

A dual occupancy may be sold separately if the dwellings are separately titled, such as through an approved unit-title subdivision. Simply building a dual occupancy does not automatically mean the dwellings can be sold separately.

Reference:

Territory Plan 2023 – Part E01 Residential Zone Policy, F01 Subdivision Policy –  Territory Plan 2023 | Notifiable instruments

Unit Titles Act 2001(ACT) (A2001-16) (registration and creation of unit titles) – Unit Titles Act 2001

Yes, potentially. The ACT Missing Middle Housing Design Guide specifically illustrates dual occupancy development where the existing dwelling is retained and a second dwelling is added. The completed development must still comply with the applicable Residential Zones Policy requirements, including site coverage, setbacks, private open space, planting, parking and access.

Reference: Planning (Missing Middle Housing) Design Guide 2026 – ACT Missing Middle Housing Design Guide & Territory Plan 2023 – Part E01 Residential Zone Policy –  Territory Plan 2023 | Notifiable instruments

No. A secondary residence (granny flat) cannot be separately unit titled in the ACT. It is subordinate to the main dwelling and remains part of the same block and title.

This means you cannot create a separate unit title for the secondary residence so that it can be independently owned or sold.

Territory Plan 2023 – Part E01 Residential Zone Policy, F01 Subdivision Policy –  Territory Plan 2023 | Notifiable instruments

Unit Titles Act 2001(ACT) (A2001-16) (registration and creation of unit titles) – Unit Titles Act 2001

The fire-separation requirements for a secondary residence depend on how close it is to the main dwelling, other buildings and the property boundaries.

Under the NCC, fire-resisting construction is generally required where a Class 1 building is less than 900 mm from a property boundary (other than a boundary adjoining a road or public space), or less than 1.8 m from another building on the same block, subject to the applicable exceptions.

Where a wall is required to be fire-resisting, the NCC provides compliant construction methods, including walls achieving an FRL of at least 60/60/60 or specified masonry construction.

If the secondary residence is attached to another Class 1 dwelling, additional requirements for separating walls may apply.

The exact fire-separation requirements should be confirmed by the building certifier based on the particular design and the version of the NCC being used for the Building Approval.

Reference: National Construction Code – Volume Two, Part H3 Fire Safety; ABCB Housing Provisions, Part 9.2 Fire Separation of External Walls & Part 9.3 Fire Protection of Separating Walls and Floors – https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-two/h-class-1-and-10-buildings/part-h3-fire-safety?utm_source

No, not necessarily. You may be able to retain your existing house and add a second dwelling to create a dual occupancy.

Whether this is possible depends on the existing house's location and whether the completed development can meet the applicable dual occupancy requirements, including site coverage, setbacks, private open space, planting, parking and access.

Reference: Planning (Missing Middle Housing) Design Guide 2026 – ACT Missing Middle Housing Design Guide & Territory Plan 2023 – Part E01 Residential Zone Policy –  Territory Plan 2023 | Notifiable instruments

Yes, potentially. You may be able to extend or alter your existing house as part of creating a dual occupancy.

The completed development must provide two dwellings and meet the applicable dual occupancy (multi-unit housing) requirements. This includes requirements such as site coverage, setbacks, building height, private open space, planting, parking and access.

Whether this is possible will depend on the existing house, the block and whether the proposed development can meet the applicable planning and building requirements.

Reference: Planning (Missing Middle Housing) Design Guide 2026 – ACT Missing Middle Housing Design Guide & Territory Plan 2023 – Part E01 Residential Zone Policy –  Territory Plan 2023 | Notifiable instruments

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. 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