Bathroom waterproofing in Sydney must comply with the National Construction Code (NCC), including NSW variations, and the referenced edition of AS 3740, Waterproofing of domestic wet areas. The requirements vary with the building classification, shower design, substrate and bathroom layout. Tiles and grout are finishes, not the waterproofing system.
How the NCC and AS 3740 work together
The NCC sets mandatory performance requirements for wet areas. AS 3740 provides a Deemed-to-Satisfy pathway for meeting them in domestic bathrooms. A documented Performance Solution may be used instead if it satisfies the relevant NCC requirements.
The applicable NCC and AS 3740 editions depend on when the project is approved or undertaken. Houses and townhouses generally fall under the NCC Housing Provisions, while apartments may be subject to the provisions for Class 2 buildings and additional approval requirements.
Which areas require protection?
The required waterproof or water-resistant treatment depends on the bathroom design, but key areas include:
- Showers: Shower floors and specified wall areas must be waterproof. Unenclosed showers generally require protection over a wider area than enclosed showers.
- Floors and walls: Coverage depends on factors such as the shower configuration, substrate, floor waste, floor level and adjoining spaces. Not every bathroom requires the same extent of waterproofing.
- Junctions and penetrations: Wall-to-floor junctions, corners, hobs, doorways, screen connections and pipe penetrations must be detailed without breaking membrane continuity. Movement-prone junctions may require compatible bond breakers or reinforcement.
- Wastes and drainage: The membrane must connect correctly to shower and floor wastes using an appropriate drainage detail. The finished system must direct water to the waste.
- Membrane system: The membrane, primer, sealants, substrate, bond breakers, waste fittings and finishes must be compatible and installed to the applicable specification and manufacturer’s instructions.
Waterproofing is concealed once tiling begins. Homeowners should not attempt membrane application, junction detailing or waste connections unless appropriately licensed and competent; errors can cause concealed water damage.
How to confirm compliance
Before work is covered, homeowners should:
- confirm which NCC and AS 3740 editions apply;
- obtain the membrane specification and installation instructions;
- confirm that all system components are compatible;
- establish who will inspect and document the work before tiling;
- keep product details, invoices, photographs and required compliance documents; and
- verify the contractor’s current NSW licence and that it covers the work being performed.
Plumbing and drainage connections must be completed by an appropriately licensed plumber. For a Sydney renovation, our plumbing team can assess the plumbing interfaces and coordinate them with the waterproofing contractor before tiling.