In South Australia, wet areas in a home have to be waterproofed to the National Construction Code. In practice that means following AS 3740 (Waterproofing of domestic wet areas) or the deemed-to-satisfy rules in Part 10.2 of the NCC Housing Provisions. For a shower, the headline requirements are simple: the whole shower floor is waterproof, the walls are waterproof to at least 1800 mm above the floor substrate, and every corner, junction and penetration is sealed. Most failures we see come down to how the job was done, not which product was used.
Which rules apply in South Australia right now
According to PlanSA, NCC 2022 Amendment 2 remains SA's Building Code until 30 April 2027, and the Building Code within NCC 2025 is adopted from 1 May 2027. Under NCC 2022, a home's wet areas meet the performance requirement by complying with AS 3740 or Part 10.2 of the ABCB Housing Provisions (NCC Volume Two, H4D2). The current edition of AS 3740 is AS 3740:2021, which covers waterproofing of domestic wet areas.
What has to be waterproof, and how high
This summary is taken from NCC 2022 Housing Provisions Part 10.2. It isn't the whole Part, but it covers what matters in a typical bathroom.
| Area | Requirement |
|---|---|
| Shower floor (including any hob or step-down) | Waterproof |
| Shower walls | Waterproof to at least 1800 mm above the floor substrate |
| Wall junctions inside the shower | Waterproof at least 40 mm either side of the junction |
| Wall/floor junctions and penetrations inside the shower | Waterproof |
| Bathroom floor outside the shower | Water resistant on concrete or fibre-cement; waterproof on timber or particleboard |
| Wall/floor junctions outside the shower | Waterproof; a flashing's horizontal leg at least 40 mm |
| Walls beside an inserted bath | Waterproof to at least 150 mm above the bath lip |
| Laundry and WC floors | Water resistant |
Two more details matter. Membranes deemed waterproof under Part 10.2 are those that comply with AS/NZS 4858. And where a floor waste is installed, the floor has to fall to it at between 1:80 and 1:50, so water actually drains instead of sitting on the membrane. South Australia also has its own variation requiring the floor of a wet area containing a fixture such as a shower or bath to be graded to a floor waste, with some exceptions.
Why shower waterproofing fails
- Tiled before it cured. Membranes need time. As one example, the datasheet for ARDEX WPM 001 gives 1 to 2 hours between coats at 23°C, normally ready to tile in 48 hours, but up to 72 hours at 10°C in corners or thick films. Adelaide winters slow things down, and rushing this step is a common cause of failure.
- Corners and junctions skipped or done rigid. The wall/floor junction and internal corners move. If they aren't detailed properly, the membrane splits there first.
- Not high enough. A membrane that stops short of 1800 mm, or misses the tap and shower arm penetrations, leaves a path for water.
- Poor connection at the floor waste. The membrane has to be properly connected to the waste so water that gets through the grout is carried away.
- Bad substrate or falls. Membrane applied over dusty, damp or uneven surfaces, or a floor without proper fall, won't perform for long.
How we waterproof a shower
The order matters more than the brand. On a full job we strip back, check the substrate and the falls, screed or level the floor where needed, prime, detail the corners, junctions and penetrations, then apply the membrane in coats and let it cure before testing it and tiling. Shower recess, floor and wall membranes, balconies and laundries are all part of our waterproofing service, done to AS 3740 on every job.
Questions to ask whoever waterproofs your bathroom
- Which membrane will you use, and does it comply with AS/NZS 4858?
- How high will the membrane go on the shower walls, and what happens at the corners and penetrations?
- How long will you leave it to cure before tiling, and will it be tested?
- Will I get documentation for the waterproofing?
- Are you licensed? In SA you can check a builder or tradesperson on the CBS Find a licence holder search. For domestic building work worth $20,000 or more, SA also requires a written contract (sa.gov.au).
If your shower is already leaking, our guide to leaking shower signs and causes explains when a regrout will do and when it has to be re-waterproofed. We waterproof showers and bathrooms right across the south, including Woodcroft and Happy Valley.
