StandAId › NCC explained › Wet area waterproofing in houses: showers, baths, floors and walls
Wet areas — bathrooms, showers, laundries and sanitary compartments — have to be built so water can't get into the structure. The NCC splits the requirements by location: the shower area gets the strictest treatment (waterproof floors, water-resistant or waterproof walls to set heights), areas around baths and outside the shower have their own rules, and the whole thing hangs off a defined list of what counts as 'waterproof' versus 'water resistant' material.
For sparkies the same zones matter for a different reason — AS/NZS 3000's bathroom zones for electrical equipment are measured from the same bath and shower. For plumbers and builders, the falls to floor wastes and the membrane rules decide whether the job leaks in five years.
The clauses below are the Housing Provisions Part 10.2 core. South Australia replaces 10.2.1 with its own version — SA readers should check the SA entry.
This page is a plain-English guide written by StandAId, followed by the actual NCC 2025 clause text. It is not professional advice and StandAId is not endorsed by the ABCB — always check the current edition on ncc.abcb.gov.au and your state's requirements.
(1) Building elements in wet areas within a building must be protected with a waterproofing system.
(2) The waterproofing system in (1) must be either waterproof or water resistant in accordance with 10.2.2 to 10.2.6.
State variation: this clause is varied in South Australia. Check the state schedule on the ABCB site, or set your state in StandAId to get the right version.
(1) For a shower area with a hob, step-down or level threshold, the following applies:
(a) The floor of the shower area must be waterproof, including any hob or step-down (see Figure 10.2.2); and
(b) The walls of the shower area must be waterproof not less than 1800 mm above the floor substrate (see Figure 10.2.2).
(c) Wall junctions and joints within the shower area must be waterproof (see Figure 10.2.2).
(d) Wall/floor junctions within the shower area must be waterproof (see Figure 10.2.2).
(e) Penetrations within the shower area must be waterproof.
(2) A shower with a preformed shower base must also comply with the requirements of (1), except for (a) which is not applicable.
[See Figure 10.2.2 — Extent of treatment for shower areas — concrete compressed fibre-cement and fibre-cement sheet floors]
Note: Where a shower is above a bath or spa, use requirements for shower.
Figures referenced (view on the ABCB site — images aren't reproduced here):
(1) For areas adjacent to all baths and spas, the following applies:
(a) For concrete, compressed fibre-cement and fibre-cement sheet flooring, the floor of the room must be water resistant.
(b) For timber floors including particleboard, plywood and other timber based flooring materials, the floor of the room must be waterproof.
(c) Tap and spout penetrations must be waterproof where they occur in horizontal surfaces.
(2) For areas adjacent to non-freestanding baths and spas, the following applies:
(a) Walls must be water resistant (see Figure 10.2.4a and Figure 10.2.4b)—
(i) to a height of not less than 150 mm above the vessel, for the extent of the vessel, where the vessel is within 75 mm of a wall; and
(ii) for all exposed surfaces below vessel lip.
(b) Wall junctions and joints must be water resistant within 150 mm above a vessel for the extent of the vessel.
(c) Wall/floor junctions must be waterproof for the extent of the vessel (see Figure 10.2.4a and Figure 10.2.4b).
(3) For inserted baths and spas, the following applies:
(a) For floors and horizontal surfaces:
(i) Any shelf area adjoining the bath or spa must be waterproof and include a waterstop under the vessel lip.
(ii) There are no requirements for the floor under a bath or spa.
(b) For walls:
(i) Waterproof to not less than 150 mm above the lip of a bath or spa.
(ii) There are no requirements for the floor under a bath or spa.
(c) For wall junctions and joints, the following applies:
(i) Waterproof junctions within 150 mm of a bath or spa.
(ii) There are no requirements for junctions and joints in walls beneath the lip of a bath or spa.
(d) Tap and spout penetrations must be waterproof where they occur in horizontal surfaces.
[See Figure 10.2.4a — Areas adjacent to baths and spas without showers for concrete, compressed fibre-cement and fibre-cement sheet flooring]
[See Figure 10.2.4b — Areas adjacent to baths and spas without showers for timber floors including particleboard, plywood and other floor materials]
Figures referenced (view on the ABCB site — images aren't reproduced here):
(1) The following materials used in waterproofing systems are deemed to be waterproof:
(a) Stainless steel.
(b) Flexible waterproof sheet flooring material with waterproof joints.
(c) Membranes complying with AS/NZS 4858.
(d) Waterproof sealant.
(1) The following materials are deemed to be water resistant:
(a) For walls:
(i) Concrete complying with AS 3600, treated to resist moisture movement.
(ii) Cement render, treated to resist moisture movement.
(iii) Fibre-cement sheeting manufactured in accordance with AS/NZS 2908.2.
(iv) Water resistant plasterboard sheeting.
(v) Masonry in accordance with AS 3700, treated to resist moisture movement.
(b) For floors:
(i) Concrete complying with AS 3600.
(ii) Concrete slabs complying with AS 2870.
(iii) Fibre-cement sheeting manufactured in accordance with AS/NZS 2908.2.
(1) Where a floor waste is installed—
(a) the minimum continuous fall of a floor plane to the waste must be 1:80; and
(b) the maximum continuous fall of a floor plane to the waste must be 1:50.
Got a follow-up? StandAId answers questions on the text of the NCC 2025 — Volumes One, Two, Three and the Housing Provisions — with the clause linked. Free account, 3 questions a day; upload your own standards for more.
Ask the NCC in StandAId — free, 3 questions a dayIt depends on the area: shower area floors must be waterproof, and floors elsewhere in the wet area have their own requirement depending on the flooring material and whether a floor waste is provided. See Housing Provisions 10.2.1 to 10.2.4.
The NCC lists deemed water resistant materials for walls and floors — concrete, cement render, fibre-cement sheeting, water resistant plasterboard and compliant masonry among them. See Housing Provisions 10.2.9.
Housing Provisions 10.2.12 sets the minimum falls to a floor waste in shower areas and other wet-area floors — read the clause for the ratios.
The National Construction Code 2025 was provided by the Australian Building Codes Board under the CC BY 4.0 licence. © Commonwealth of Australia and the States and Territories of Australia 2026, published by the Australian Building Codes Board. Licence: CC BY 4.0. NCC text on this page was extracted from the ABCB's NCC 2025 dataset (v1.2) and reformatted; figures, diagrams and photographs are not reproduced (they are outside the licence) — follow the links to view them on the ABCB site. The ABCB publishes the NCC without warranty and it is not legal or professional advice.
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