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AS/NZS 4858: the wet-area membrane product standard

AS/NZS 4858:2004 is the product standard a wet-area waterproofing membrane must meet. It classifies membranes by elasticity, separate from AS 3740 (installation).

By Chalkline. Last updated 24 May 2026. Verified 24 May 2026.

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TL;DR

AS/NZS 4858:2004 is the product standard for waterproofing membranes used in wet areas. It is the benchmark a membrane material has to meet to be fit for the job, and it sits alongside (not instead of) AS 3740, the standard that governs how the membrane is installed. The simple split: AS/NZS 4858 certifies the membrane; AS 3740 governs the waterproofing work. The standard classifies membranes by their elastic properties, which then guides the detailing a given membrane needs when it is applied under AS 3740 (verified 2026-05-24, Standards Australia AS/NZS 4858:2004). For a builder, the practical point is to confirm the membrane your waterproofer is using is an AS/NZS 4858 compliant product.

Two standards, two jobs

Wet-area waterproofing is governed by two standards that are easy to confuse:

StandardGovernsQuestion it answers
AS/NZS 4858:2004The membrane productIs this membrane material fit for a wet area?
AS 3740:2021The waterproofing workWas the wet area waterproofed correctly?

A compliant job needs both: an AS/NZS 4858 compliant membrane, installed to AS 3740. A premium membrane installed badly fails AS 3740; a perfect installation of a non-compliant product fails on the material. Both standards are picked up through NCC 2022 Housing Provisions Part 10.2 for wet-area waterproofing.

What AS/NZS 4858 covers

The standard sets the test methods and performance requirements a membrane has to satisfy, and it classifies membranes by their elastic properties (how far the membrane can stretch and recover). That classification then informs the detailing a particular membrane needs, for example how it bridges joints and movement, when it is used under AS 3740 (verified 2026-05-24, Standards Australia AS/NZS 4858:2004). The specific class definitions and numeric thresholds sit in the standard itself (paywalled); confirm them against the current document.

It applies to both liquid-applied membranes and sheet membranes: the product type does not matter, the compliance benchmark is the same.

Builder takeaway

  • Confirm the membrane on the job is an AS/NZS 4858 compliant product. Reputable brands state compliance on the data sheet.
  • The membrane data sheet and the waterproofer’s compliance certificate are what you keep for the file: the product (AS/NZS 4858) and the installation (AS 3740) are both part of demonstrating the wet area is compliant.
  • Do not let a substitution slip through: a cheaper membrane that is not AS/NZS 4858 compliant undermines the whole wet area, even with a perfect install.

References

  • AS/NZS 4858:2004, Wet area membranes (Standards Australia) (verified 2026-05-24)
  • AS 3740:2021, Waterproofing of domestic wet areas (Standards Australia) (verified 2026-05-10, corpus)
  • NCC 2022 Housing Provisions Part 10.2, Wet area waterproofing (ABCB) (verified 2026-05-10, corpus)

See also

Last updated: 2026-05-24. Verified: 2026-05-24. Quarterly review for currency.

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