Augusta Margaret River Lifts Some Granny Flat Limits to 120 sqm

Augusta Margaret River’s new planning scheme increases the maximum size of ancillary dwellings on rural and rural residential properties from 70 to 120 square metres. The Shire says Local Planning Scheme 2 took effect after gazettal on 29 September 2026. The change is local and zoning-specific; it is not a new 120 sqm rule for every WA backyard.

Updated 2 October 2026. By The Granny Flat Guide Team.

Which properties the announcement covers

In its 30 September announcement, the Shire identifies rural and rural residential zoned properties. It describes the larger allowance as supporting long-term housing, including intergenerational living and worker accommodation. Its stated objective is not short-term rental accommodation.

The announcement also covers wider planning changes, but a property’s eligibility for a particular granny-flat proposal still needs checking. An address within the Shire is only the beginning. Owners need to establish the applicable zone and requirements before asking a supplier to redesign a building around the larger figure.

Check the scheme before commissioning a larger design

Use the Shire’s planning and mapping resources to start the property check, then ask its planning team how the current scheme applies to the proposed site. Give the full address and describe the intended use. Keep the written answer with the design brief so the builder and designer are working from the same information.

Questions worth resolving include how the relevant floor area is measured, which approvals are needed, and whether any property-specific controls affect the proposal. Don’t assume that a larger maximum removes the need to assess access, servicing or the position of the building. Those questions belong in the site investigation before a quote becomes a commitment.

Revisit the budget as well as the floor plan

A larger permitted floor area creates an option; it doesn’t establish that a larger building is the best choice for the household or site. Owners comparing a compact flat with a bigger dwelling should ask for both proposals to be priced on the same basis, including external work and connections. Otherwise the extra rooms are being compared against an incomplete budget.

Owners considering a kit should distinguish the supplied building components from the work needed on the property. Our kit-home guide covers that comparison. Use the cost calculator for early planning rather than as a project quote. For other jurisdictions, check the relevant local rules instead of carrying the Augusta Margaret River allowance across a boundary. Further dated changes appear in granny flat news.