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Waterproofing of wet areas

Requirements for the materials, design and installation of waterproofing for domestic wet areas for residential buildings.

Overview of the Standard 

AS 3740 sets out the requirements for the materials, design and installation of waterproofing for domestic wet areas for residential buildings.

What does it Include?

AS 3740 is broken into 3 sections consisting of:

  • Section 1 – provides the scope and definitions applicable to this standard and the other normative reference documents that are specified
  • Section 2 - sets out the acceptable waterproof and water-resistant materials to be used in waterproofing systems for walls and floors in wet areas 
  • Section 3 - sets out the details for the installation of waterproof and water-resistant materials to be used in shower areas, showers over baths, baths and spas, junctions, and penetrations. As well as general requirements in shower areas such as step downs, hob construction and requirements for enclosed and unenclosed showers 

This standard also contains 3 informative appendices consisting of:

  • Appendix A - (informative) Design consideration in wet area requirements provides information that should be considered when designing waterproofing systems for wet areas and includes guidelines for dealing with the degree of risk, and the types of materials used and their locations in the construction
  • Appendix B - (informative) Falls in floor finishes outlines the primary consideration for falls in floor finishes
  • Appendix C - (informative) Extent of waterproofing. The information in this appendix is based on Table F1.7 BCA Vol 1 and Table BCA Vol 2 and provides diagrammatic representation of the extent of the waterproofing specified in the tables

Is the Standard referenced in NCC or Other legislation?

This standard is referenced in both Volume One and Two of the NCC and applies to Class 1, Class 2, and Class 4 buildings and to wet areas within other buildings with a similar level of use including sole-occupancy units within a Class 3 building.

Who is the Standard for?

This standard primary users are builders, kitchen and bathroom installers, waterproofing installers, carpenters, building designers, building certifier and surveyors, site supervisors and inspectors.

Related Australian Standards

  • AS 4654 External waterproofing
  • AS 1684 Residential timber-framed construction series
  • AS 3958.1 Part 1: Guide to the installation of ceramic tiles

Related HIA Information Sheets

Getting a copy of the Standard

An electronic copy of this Australian Standard can be purchased through the Digital Australian Standards webpage.

To find out more, contact HIA’s Building Services team.

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