How high does waterproofing need to extend on shower walls, and does the whole bathroom floor need to be waterproofed?
Inside the shower area, the requirements are strict: [1]
- Walls: waterproof to not less than 1800 mm above the floor substrate.
- Floor: waterproof, including any hob or step-down.
- Wall junctions and joints: waterproof to not less than 40 mm either side of the junction, and all penetrations waterproofed.
For an unenclosed shower, the floor must be waterproofed to at least 1500 mm from the shower outlet, with walls still waterproofed to 1800 mm. [2]
Outside the shower, the whole bathroom floor does not automatically need waterproofing. A concrete or fibre-cement floor needs to be water resistant, not waterproof. [2] The exception is the waterstop detail: where the waterstop meets a wall and that junction is not itself made waterproof, the whole wet area floor must be waterproofed and drained to a floor waste, the same as the shower area. [3]
Worth noting for forward planning: NCC 2025 (which NSW adopts on 1 May 2027) keeps the 1800 mm wall height but drops the 40 mm junction dimension in favour of a plain "must be waterproof", and requires timber-based floors outside the shower to be fully waterproof. [4]
- 1NCC 2022 Volume Two — ABCB Housing Provisions10.2.2 Waterproofing of shower areas · p. 243
- 2NCC 2022 Volume Two — ABCB Housing Provisions10.2.2 and 10.2.3 · p. 244
- 3NCC 2022 Volume Two — ABCB Housing Provisions10.2.18 Waterstops · p. 254
- 4NCC 2025 Volume Two — ABCB Housing Provisions10.2.2 and 10.2.3 · pp. 250–252
This answer is for professional reference only and does not replace a registered building surveyor or certifier. The operative edition of the NCC differs by jurisdiction and changes over time. Verify against the current code for your jurisdiction before relying on it.