Australia National Construction Code 2022 Volume Two (Building Code of Australia, Class 1 and 10 Buildings) H4P1: H4P1 Wet areas

To protect the structure and occupants' amenity, water must be prevented from penetrating behind fittings and linings, or into concealed spaces, of sanitary facilities, bathrooms, laundries and similar rooms. Deemed-to-Satisfy route: H4D2 wet areas to AS 3740 or Housing Provisions Part 10.2, protected as clauses 10.2.1 to 10.2.6 and 10.2.12 require; H4D3 building elements in wet areas water resistant or waterproof per clauses 10.2.1 to 10.2.6, and materials and installation to AS 3740 plus clause 10.2.12, or to clauses 10.2.7 to 10.2.32. In a Class 1a dwelling at least one bathroom and one toilet must also meet the ABCB Standard for Livable Housing Design, which may override H4D3. South Australia adds SA H4P1(2): floors of bathrooms and rooms with a shower or sanitary fixture must not let water pool on the surface.