Planning rules in Western Australia

Not if it meets the deemed-to-comply rules of the R-Codes - up to 70 m² and the required setbacks - in which case only a building permit is needed.

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.

The Western Australian Planning Commission (WAPC), not your local council. You lodge the subdivision application directly with the WAPC through the Planning Online portal; the WAPC refers it to your council and to servicing agencies for comment and then decides within 90 days. Councils in WA still assess development applications for buildings, but they cannot approve a subdivision.

A house deck 500 mm or less above natural ground usually needs no planning approval. A building permit is still required for most decks, and councils commonly require one once a deck is over 500 mm high, over 20 m², or within 900 mm of a boundary.

A prefabricated shed of 10 m² or less and up to 2.4 m high needs no building permit. Bigger sheds need a building permit, and need planning approval only if they exceed the R-Codes outbuilding limits.

There is no single statewide figure. Dividing fences are commonly 1.8 m and street fences are usually solid to 1.2 m with permeable infill above; the binding number comes from your local government's fencing local law and the R-Codes.