Dual occupancy rules in Western Australia (2026)
Driven by your R-code density - most R20 lots need about 900 m²
It comes down to your R-code. Two dwellings on one lot are grouped dwellings under the Residential Design Codes, and the density code mapped to your lot - R20, R30, R40 and so on - sets the average and minimum site area per dwelling, which is what decides whether your block can take two.
Key rules at a glance
| Site area per dwelling | Set by your R-code. Indicative figures: R20 average 450 m² and minimum 350 m²; R25 average 350 m² and minimum 300 m²; R30 average 300 m² and minimum 260 m²; R40 average 220 m² and minimum 180 m². |
| What that means for two dwellings | Roughly 900 m² at R20, 700 m² at R25, 600 m² at R30 and 440 m² at R40 (indicative - the average site area applies across the whole lot). |
| Density code | Mapped per property by the local planning scheme. Split codes such as R20/R40 apply in some areas and can unlock a higher density where the scheme criteria are met. |
| Approval pathway | Development approval from the local council in most cases, assessed against the R-Codes, plus WAPC approval for any subdivision or survey-strata. |
| Can it be subdivided or strata titled? | Yes. Green title subdivision creates fully independent lots; survey-strata is used where a driveway or services are shared. Both are approved by the WAPC, generally within 90 days, then conditions must be cleared before new titles issue. |
| Typical timeframe | Commonly 2-4 months for development approval, plus around 90 days for WAPC subdivision approval and further time to clear conditions and create titles. |
Conditions & eligibility
- Your lot's R-code must provide enough average and minimum site area for two dwellings.
- Open space, setbacks, site cover, outdoor living areas and car parking under the R-Codes must be met.
- Medium density provisions in Part C of the R-Codes apply to grouped dwellings at R30 and above.
- Reticulated sewer connection is generally required; unsewered lots are usually ruled out.
- Heritage listings, bushfire prone areas and flood-affected land add assessment and can prevent approval.
- Subdivision or survey-strata is a separate WAPC approval, not automatic with development approval.
Heritage, flood and bushfire controls on your specific lot can remove the fast-track and require a full application, even when the general rules say you're fine.
How approval works in Western Australia
Grouped dwellings normally need development approval from your local council, assessed against the R-Codes and the local planning scheme. Some councils exempt a fully deemed-to-comply proposal from development approval, so check locally. Creating two titles is separate again: green title subdivision or survey-strata is approved by the Western Australian Planning Commission (WAPC), which has a 90 day statutory period. A building permit is always required.
Local planning schemes and local planning policies vary setbacks, site cover and split-code criteria, and some councils require development approval where neighbouring councils do not.
Dual occupancy rules by council in Western Australia
Local councils apply the Western Australia framework and can add their own controls. Pick your council:
Frequently asked questions
What size block do I need for a duplex in Perth?
Divide the lot area by the average site area for your R-code. At R20, where the average is 450 m² per dwelling, you generally need about 900 m²; at R30 (average 300 m²) about 600 m²; at R40 (average 220 m²) about 440 m². If your lot falls under the average needed for two dwellings it will not support a duplex unless a split code or a specific scheme provision applies.
Can a duplex in WA be sold as two separate properties?
Yes. You apply to the Western Australian Planning Commission for either a green title subdivision, which creates two fully independent lots, or a survey-strata, which is used where a common driveway or shared services are involved. The WAPC has a 90 day statutory period, after which conditions must be cleared before the new titles issue.
Do I need council approval to build two dwellings on one lot in WA?
Usually yes. Grouped dwellings normally need development approval from the local council, assessed against the R-Codes and the local scheme, although some councils exempt proposals that meet every deemed-to-comply provision. A building permit is always required, and subdivision or strata titling is a separate WAPC approval.
Sources
- Residential Design Codes Volume 1 (including Medium Density) - WA Government ↗
- Revised R-Codes now in effect - Department of Planning, Lands and Heritage ↗
- Residential Design Codes Volume 1, Table D site area requirements (10 April 2026, PDF) ↗
Related building rules
This is general guidance, not professional planning advice. Figures are summarised from the sources above and can change — confirm with your council or the WA Planning before starting work. Last reviewed: July 2026.
Talk to a town planner in Western Australia
This page covers the general rules. A qualified town planner can tell you what applies to your block, including the zone, overlays and approval path, before you spend money on drawings.
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