Western Australia

Backyard homes in Western Australia

Locally referred to as Ancillary dwelling

Western Australia provides planning exemptions for compliant ancillary dwellings that satisfy the Residential Design Codes and local requirements.

Up to 70 m²

A compliant ancillary dwelling may have an internal floor area of up to 70 square metres.

Same site as an existing home

It may be attached, integrated or detached, but remains associated with the existing home.

No general minimum lot size

The previous 350 square metre minimum lot requirement has been removed for compliant proposals.

Planning approval may not be required

An exemption may apply where every relevant deemed-to-comply requirement is satisfied.

Local design controls still apply

Setbacks, height, site cover, privacy, access and local planning requirements must still be checked.

A building permit remains required

Planning exemption does not remove building permit or National Construction Code requirements.

Also worth knowing

•Not every 70 square metre ancillary dwelling is automatically exempt — the exemption depends on meeting all relevant requirements.

What may affect your property?

State-wide rules are only the starting point. Councils, sites and titles differ, so these are checked for your specific address.

•Local government area
•Land zoning
•Planning overlays
•Lot size and dimensions
•Existing dwelling
•Title restrictions and covenants
•Bushfire, flood and environmental risk
•Setbacks and site coverage
•Utility and wastewater capacity
•Delivery and construction access
•Intended residential or non-residential use

Intended use changes the pathway

A self-contained residence, a guest room, a home office and a non-habitable studio may be treated differently. The proposed facilities and how the building will be occupied can change the applicable planning and building pathway.

See what may suit your Western Australia property

Preliminary property guidance — not an approval, eligibility decision or permit.

Check my backyard

My Backyard Home provides general, preliminary information based on published planning and building material. It does not confirm that a dwelling or structure can be built on your property and is not legal, planning, building, engineering, financial or tax advice. Requirements may vary according to your address, council, title, zoning, overlays, site conditions, intended use and chosen product. Final feasibility, permits, approvals and compliance must be confirmed by the relevant authorities and qualified professionals.

Government sources and review date

WA Planning - Ancillary dwelling information sheet
Responsible authority: Government of Western Australia (Department of Planning, Lands and Heritage)
Source URL not yet verified — refer to the published government material by name.
Residential Design Codes Volume 1
Responsible authority: Government of Western Australia (Department of Planning, Lands and Heritage)
Source URL not yet verified — refer to the published government material by name.

Last reviewed 27 July 2026