The short answer
The Australian Building Codes Board says wet area waterproofing in NCC 2022 can be done two ways: the Housing Provisions on their own, or the Housing Provisions together with AS 3740. If you use AS 3740, the board says to use the 2021 edition.
General information read in full from the ABCB on 12 November 2026. Rules about who may do waterproofing and what certificate a council wants vary by state and council, so check yours.
The two routes
Option 1 is the Housing Provisions only, using Part 10.2 in full. Option 2 is the Housing Provisions (10.2.1 to 10.2.6 and 10.2.12) together with AS 3740. The ABCB says to make sure you use AS 3740:2021, which NCC 2022 references.
The certificate
Many councils ask for a waterproofing certificate before they issue a completion or occupation certificate. Check your council's form to see who has to sign it, and ask for a copy for your records.
Questions to ask
- Who does the waterproofing and what is their licence?
- Which route are they following, and which membrane will they use?
- Who signs the certificate and when will I get it?
- Is the waterproofing included in the tiling price?
- What warranty do I get on the membrane?
Common questions
Who is responsible for waterproofing a bathroom?
It depends on your contract and your state. Ask in writing who does it, who certifies it and what warranty applies.
Sources
- ABCB: waterproofing in houses, checked 12 November 2026