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AS 3740:2021


Waterproofing of domestic wet areas

Included in Waterproofing and tiling set
Sets out minimum requirements for the materials, design and installation of waterproofing for domestic wet areas in Class 1, Class 2 and Class 4 buildings as defined in the NCC. It also applies to wet areas within Class 3 to 9 buildings as if it were a Class 2 or 4 part of a building. KEYWORDS: waterproofing, wet areas
Published: 23/07/2021
Pages: 67
Table of contents
Cited references
Content history
Table of contents
About this publication
1 Scope and general
1.1 Scope
1.2 Normative references
1.3 Terms and definitions
2 Design
2.1 Design principles
2.1.1 General
2.1.2 Material selection
2.2 Shower classification
2.2.1 Enclosed showers
2.2.2 Unenclosed showers General
2.3 Requirements for fall
2.3.1 Falls in substrate
2.3.2 Falls in shower area floor finishes (Category 1)
2.3.3 Falls in wet area floor finishes adjacent to shower area where there is a floor waste (Category 2)
2.3.4 Falls in wet area floor finishes where there is no floor waste (Category 3)
2.3.5 Whole of bathroom designed as an unenclosed shower
3 Materials
3.1 Scope of section
3.2 Compatibility
3.3 Materials
3.3.1 Waterproof
3.3.2 Water-resistant substrates
3.3.3 Water-resistant surface materials
3.4 Preformed, prefinished shower bases and enclosures
3.5 Sealants
3.6 Fastenings for substrate sheet linings
3.7 Adhesives
4 Installation
4.1 Scope of section
4.2 Membrane installation for tile bed or screed
4.3 Membrane to drainage connection
4.3.1 Leak control flanges
4.3.2 Linear drainage connections
4.4 Surface preparation
4.4.1 Surface preparation
4.4.2 Requirements for fall in substrate
4.4.3 Moisture content of substrates
4.4.4 Wall sheeting preparation
4.4.5 Render preparation
4.5 Membrane application
4.5.1 Installation of an external membrane
4.5.2 Curing of membranes
4.5.3 Membrane inspection
4.5.4 Additional continuity testing
4.6 Membrane termination
4.6.1 Termination of membranes at shower recess waterstops
4.6.2 Termination of membranes at showers with hobs
4.6.3 Vertical membrane termination
4.7 Hob construction
4.8 Waterstops
4.8.1 General
4.8.2 Waterstop for unenclosed showers
4.8.3 Waterstops for enclosed showers
4.8.4 Waterstop for enclosed showers without hobs or set-downs
4.8.5 Showers located near exits to wet areas
4.9 Door openings
4.9.1 Perimeter flashing at floor level openings
4.9.2 Protection of door frames and architraves
4.10 Fillets and bond breakers — bond breaker installation for bonded membranes
4.11 Junctions, transitions, and terminations
4.11.1 Types of junctions, transitions, and terminations
4.11.2 Vertical flashing for shower wall junctions
4.12 Penetrations
4.12.1 Shower areas
4.12.2 Horizontal surface taps
4.12.3 Other penetrations in Category 1 areas
4.12.4 Niches, inlaid soap holders, and footrests
4.13 Baths and spas
4.13.1 General
4.13.2 Baths without showers over them Baths without an integral upstand edge — insert baths Baths to be recessed into a wall with no shower over them
4.13.3 Baths with showers over them Bath adjoining a Type 2 unenclosed shower Baths recessed into a wall — fitted baths Baths without an integral upstand edge — insert baths
4.13.4 Freestanding baths
4.13.5 Bath end walls abutting a shower
4.13.6 Spa baths
4.14 Preformed shower bases
4.15 Enclosed shower screen placement
4.15.1 Showers with hobs
4.15.2 Showers with step-downs
4.15.3 Showers without hobs or step-downs
4.15.4 Bath end walls and nib walls abutting a shower
4.16 Vinyl
4.17 Polished concrete
4.18 Floor heating
Appendix A
A.1 Scope
A.2 General
A.3 Category of risk for wet areas
A.3.1 General
A.3.2 Category 1 wet areas (high risk)
A.3.3 Category 2 wet areas (moderate risk)
A.3.4 Category 3 wet areas (low risk)
A.4 Leakage through finishes
A.5 Movement and waterproofing
A.5.1 General
A.5.2 Structure movement
A.5.2.1 Frame movement
A.5.2.2 Masonry movement
A.5.2.3 Panel movement
A.5.3 Wall linings under tiles in shower areas
A.5.4 Prefinished wall panels
A.5.5 Floors
A.5.5.1 General
A.5.5.2 Efflorescence
A.5.5.3 General requirements of barriers
A.5.5.4 In situ barriers — properties and installation
A.5.5.5 Set-downs
A.5.5.6 Tiles within shower area
A.6 Design solutions for single floor waste wet areas with linear drains
Appendix B
B.1 General
B.2 Factors affecting falls
B.3 Fall ratios
B.4 Diagonal cutting of tiles
B.5 Determination of ponding
Appendix C
C.1 Scope
C.2 Flood test
C.2.1 Principle
C.2.2 Procedure
C.2.3 Report
C.3 Electronic leak detection
C.3.1 Application
C.3.2 Procedure
C.3.3 Report
C.4 Seam probe test
C.4.1 Application
C.4.2 Procedure
C.4.3 Report
Appendix D
D.1 Scope
D.2 Checklist
Appendix E
E.1 General
E.2 Compatibility chain
E.2.1 General
E.2.2 Substrate primer
E.2.3 Junction/connectors
E.2.4 Bond breaker/fillets
E.2.5 System components
E.2.6 Membrane
E.2.7 Surface finish primer
E.2.8 Surface finish adhesive
E.2.9 Fillers, welds, grouts and finish sealants
E.2.10 Penetration sealants
Appendix F
F.1 Background
F.2 Testing procedures
F.2.1 General
F.2.2 Concrete subfloors
F.2.2.1 Test methods
F.2.2.2 Relative humidity (RH) in situ probe test (primary test method)
F.2.2.3 Moisture vapour emission rate surface test (secondary test method)
F.2.2.4 Calibration of scale
F.2.3 Timber and plywood membrane substrates
F.2.4 Concrete or cementitious screeds
F.3 Calibration of testing equipment
F.4 Test report
Cited references in this standard
Cellulose-cement products, Part 2: Flat sheets
Gypsum plasterboard
AS/NZS 2269 (all parts)
Structural design actions, Part 2: Wind actions
Structural design actions, Part 1: Permanent, imposed and other actions
Content history
[Available Superseded]
DR AS 3740:2020
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