Subdivision in Outer South Perth: City of Rockingham, City of Armadale & Shire of Serpentine-Jarrahdale — 2026 WA Council Guide

Overview

The outer southern corridor of metropolitan Perth encompasses three councils that represent very different phases of Perth's suburban development. The City of Rockingham, established from the 1960s and 1970s, is now a mature suburban council where infill subdivision on existing lots is the primary form of residential growth. The City of Armadale straddles the transition between established inner suburbs and rapidly growing outer growth precincts — and has been transformed by the October 2025 opening of the Byford Rail Extension, which has introduced a new transit-oriented development dynamic to Byford and the surrounding corridor. The Shire of Serpentine-Jarrahdale, immediately south and east of Armadale, is predominantly rural and rural-residential, with subdivision feasibility governed by bushfire risk, servicing availability, and rural zoning minimums rather than the suburban R-code framework.

For property owners across all three councils, the overarching planning authority is the WAPC, which determines whether any subdivision application is approved. Each council's local planning scheme sets the zone, R-code, and any special control areas that frame the WAPC's decision. The 2024 R-code minimum reductions have been the dominant driver of new subdivision feasibility in Rockingham's and Armadale's established suburbs, while Serpentine-Jarrahdale's rural character means those reforms have limited direct impact outside the small pockets of residential-zoned land within township areas.

Outer South Perth Planning Landscape

The Kwinana Freeway corridor, which runs through the heart of the outer south, is the primary infrastructure spine along which residential growth in Rockingham and Armadale has been directed for decades. The Mandurah rail line, which terminates at Mandurah with stations at Rockingham and Warnbro within the LGA, underpins transit-oriented residential development in Rockingham's southern growth areas. A future Karnup station is planned further south within the LGA but is not yet operational. The Armadale rail line, which now terminates at Byford following the extension's completion, has created a new TOD focus area at Byford that sits within the City of Armadale's boundary.

State planning policy for the outer south is shaped by the Peel Region Scheme — which technically governs planning south of the Serpentine River — and by the Metropolitan Region Scheme for areas within the metropolitan boundary. The Shire of Serpentine-Jarrahdale straddles both schemes in parts, which creates a planning complexity for landowners near the metropolitan boundary. The District Structure Plans that govern Byford and the surrounding growth areas in Armadale and Serpentine-Jarrahdale are WAPC documents that sit above local planning schemes in the planning hierarchy.

City of Rockingham

Rockingham is one of metropolitan Perth's most active outer-ring subdivision councils. The combination of large established lot sizes — many lots in Rockingham, Cooloongup, Orelia, and Hillman sit in the 700–950m² range from 1970s and 1980s subdivision patterns — with relatively affordable land values and R20–R30 designations across most residential suburbs creates a compelling feasibility case for two-lot subdivision. Following the 2024 R-code minimum reductions, a significant additional pool of previously marginal lots has moved into subdivision viability.

Rockingham's coastal growth areas in the south of the LGA — Baldivis, Secret Harbour, and Golden Bay — contain newer residential development on standard 450–600m² lots, where subdivision feasibility is more limited due to the smaller parent lot areas. These areas are also characterised by more recent development patterns where lots were already designed at medium density and have less residual subdivision potential than the older established suburbs in the northern parts of the LGA. The land release pipeline in Baldivis continues under the Baldivis District Structure Plan, with ongoing WAPC-approved subdivision creating new lots in the growth precinct.

The Rockingham city centre — around the Safety Bay Road commercial spine — carries higher-density R-code designations that support medium-density residential development. R40 and R60 designations near the Rockingham train station precinct reflect the State Government's TOD policy and create opportunities for strata subdivision that are not available in the lower-density outer residential suburbs.

City of Armadale

The City of Armadale presents a dual character for subdivision. In its established inner suburbs — Armadale townsite, Kelmscott, Camillo, and Seville Grove — the planning context is similar to Rockingham: post-war residential lots of 700–950m² with R20–R25 designations, where the 2024 R-code minimum reductions have meaningfully expanded subdivision feasibility. These suburbs also benefit from proximity to the Armadale rail line stations, and the Armadale City Centre precinct carries higher-density R-code designations consistent with the State Government's activity centre policy.

In Armadale's outer growth areas — Byford, Wungong, Hilbert, Harrisdale, and Piara Waters — subdivision is driven by the greenfield structure plan pipeline. These precincts are governed by WAPC-endorsed District Structure Plans that control the layout, density, and sequencing of new residential lots. Individual property owners within these structure-plan areas who wish to further subdivide their land must demonstrate consistency with the applicable structure plan — and many of the lots in newer stages of these precincts were created at or near the minimum lot size for their R-code designation, leaving limited further subdivision potential.

Byford TOD Precinct

The Byford Rail Extension — the 8km rail extension from Armadale to Byford — reached practical completion in December 2025 after opening to passengers in October 2025. Byford station is now the southern terminus of the Armadale line, and the area within walking distance of the station is subject to significant TOD-related planning uplift. The WAPC and DPLH have identified the Byford station precinct as a priority location for increased residential density, consistent with the State Government's policy of concentrating housing growth around new rail stations.

Shire of Serpentine-Jarrahdale

The Shire of Serpentine-Jarrahdale (SJ) is one of WA's most rapidly growing local government areas by population — driven largely by the expansion of the Byford and Mundijong urban growth corridor, which straddles the boundary between the City of Armadale and the shire. The shire's planning environment is divided between its urbanising northern fringe, where structure plans are progressively delivering new residential lots in suburbs like Whitby and North Byford, and its predominantly rural and rural-residential southern and eastern areas where subdivision is governed by rural zone minimums, bushfire overlays, and limited servicing infrastructure.

In the northern growth areas, SJ is working through a series of District Structure Plans and Local Structure Plans that are progressively being endorsed by the WAPC and implemented through subdivision approvals. These areas are connected or being connected to reticulated water, sewerage, and electricity services as part of the development process. For landowners within these structure plan areas, the subdivision pathway is relatively well-defined: consistency with the applicable structure plan is the primary requirement, alongside compliance with servicing conditions set by the Water Corporation and Western Power.

In the rural and rural-residential areas of SJ — which cover the majority of the shire by area — subdivision is a more complex and constrained exercise. Zone minimums in the Rural zone are typically 40 hectares for lot creation, while Rural Residential zones allow smaller lots (often 2–10 hectares) but require that each lot can demonstrate water supply and an acceptable BAL rating. The combination of these constraints means that rural subdivision in SJ is not a common outcome — and owners of rural parcels who are seeking to create a second lot should expect a thorough and time-consuming assessment process.

Bushfire and Rural Subdivision Constraints in Serpentine-Jarrahdale

Serpentine-Jarrahdale sits at the edge of the Darling Range, and large parts of the shire carry high to very high bushfire risk. The application of SPP 3.7 in SJ is material: any subdivision application on bushfire-prone land (which covers most of the rural and rural-residential areas of the shire) must include a site-specific BAL assessment, and any resulting lot must be capable of accommodating a habitable dwelling at an acceptable BAL rating.

Council Comparison: Outer South Perth

2026 Outlook

The outer south corridor presents one of the most varied subdivision outlooks in metropolitan Perth for 2026. Rockingham's established suburbs are an active infill market benefiting from the 2024 R-code reforms, with strong investor and owner-occupier demand for affordable entry-level lots in the outer southern corridor. Armadale's established suburbs are following a similar trajectory, while the Byford station precinct — still in the early phase of its TOD evolution — is beginning to attract the type of investor and developer interest that precedes a meaningful uplift in medium-density development activity near the new station. Serpentine-Jarrahdale's northern growth precincts are expanding under the structure plan pipeline, but the shire's rural and rural-residential areas will remain constrained by bushfire, servicing, and zoning limitations.

• Rockingham infill continuing: Suburbs like Cooloongup, Hillman, Orelia, and Peron remain attractive infill markets. The 2024 R-code reforms have expanded the feasible lot pool, and construction cost normalisation from 2025 peaks has improved project feasibility for developers and owner-builders alike.
• Armadale TOD watch list: DPLH is expected to finalise R-code uplift designations for the Byford station 400m and 800m catchment zones during 2026. Landowners within this catchment should monitor planning scheme amendment proposals closely.
• SJ northern corridor active: The Whitby and North Byford precincts in SJ are among WA's fastest-moving greenfield release areas. The structure plan pipeline is well-advanced, and lot registration volumes in these precincts will increase through 2026–2027 as servicing works complete.
• Rural subdivision constrained: The combination of bushfire risk, rural zone minimums, and limited Water Corporation reticulation in SJ's southern areas means rural subdivision approvals will remain limited in volume. Demand for rural lifestyle lots is strong, but supply is genuinely constrained by policy rather than just lack of interest.