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NCC 2022 waterproofing requirements: what Class 1 and 10 buildings must meet

NCC 2022 waterproofing requirements for Class 1 and 10 buildings. H4P1 performance requirement, H4D2/H4D3 DTS pathways, AS 3740 vs Housing Provisions Part 10.2.

By Dan Waring. Last updated 9 May 2026. Verified 9 May 2026.

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TL;DR

NCC 2022 Volume Two imposes one Performance Requirement for wet areas in Class 1 and 10 buildings: H4P1, which requires water to be prevented from penetrating behind fittings and linings or into concealed spaces. Two DTS pathways satisfy it: follow Housing Provisions Part 10.2 in full (free on the ABCB site), or use AS 3740:2021 together with clauses 10.2.1-10.2.6 and 10.2.12 of the Housing Provisions. A Performance Solution is also available but needs a registered building surveyor or certifier to assess and document it. Most residential jobs run the DTS path. The cost of a missed waterproofing defect: the average Queensland bathroom warranty claim ran close to $25,000 in rectification in 2024-25 (QBCC, verified 2026-05-09).

In plain English

NCC 2022 Volume Two is the residential building code that governs Class 1 buildings (houses, attached dwellings) and Class 10 structures (sheds, garages, carports, and the like). Part H4 covers health and amenity, and within it, wet area waterproofing sits under the H4P1 Performance Requirement.

The code does not prescribe how to waterproof. It says what must be achieved (water stays out of concealed spaces). How you achieve it is then structured as either a Deemed-to-Satisfy (DTS) solution or a Performance Solution. On residential jobs, builders and waterproofers almost always use a DTS path.

This article covers the NCC regulatory framework side: the Performance Requirement, the two DTS pathways, how they relate, and when a Performance Solution applies. For the on-site installation procedure, see Wet area waterproofing membranes. For the AS 3740 standard itself, see AS 3740:2021.

What it requires

H4P1: the Performance Requirement

H4P1 is the single wet area waterproofing Performance Requirement in NCC 2022 Volume Two for Class 1 and 10 buildings:

“Water must be prevented from penetrating behind fittings and linings; or into concealed spaces, of sanitary facilities, bathrooms, laundries and the like.”

Source: NCC 2022 Volume Two Part H4, ABCB (verified 2026-05-09).

“Concealed spaces” means inside wall cavities, under timber framed floors, and behind substrate sheets. The failure mode H4P1 guards against is water tracking unseen into framing, subfloor, and building elements for months or years before the damage surfaces.

Building classes covered

Part H4 waterproofing provisions (H4P1, H4D2, H4D3) apply to Class 1 and Class 10 buildings (verified 2026-05-09, ABCB NCC 2022 Vol 2 Part H4).

Class 2, 3, and 4 buildings fall under NCC Volume One, not Volume Two. If the job is a Class 2 apartment complex, stop here and refer to Volume One.

NCC classDescriptionPart H4 applies?
Class 1aSingle detached houseYes
Class 1bGuest house, boarding house (small)Yes
Class 10aNon-habitable structure (shed, garage)Yes (where wet areas present)
Class 2Apartment (multi-storey)No: Volume One
Class 4Dwelling in non-residential buildingNo: Volume One

H4D2 and H4D3: the DTS provisions

NCC 2022 introduced two DTS provisions under H4 for waterproofing. Both must be read together to understand the full DTS compliance picture.

H4D2 specifies which wet areas must be protected and to what extent. This is the “where” clause: it identifies the spaces within a building that require waterproofing or water resistance protection, referring to the zone-by-zone requirements in Housing Provisions Part 10.2 clauses 10.2.1 to 10.2.6.

H4D3 specifies the materials and installation method requirements. This is the “how” clause. Under H4D3, compliance can be achieved via either:

  • Pathway A (Housing Provisions only): Follow clauses 10.2.7 to 10.2.32 of the ABCB Housing Provisions 2022 in full, in combination with clauses 10.2.1 to 10.2.6 (zone requirements from H4D2). This pathway is self-contained; AS 3740 is not required.
  • Pathway B (AS 3740 + Housing Provisions): Follow AS 3740:2021 for materials and installation, in combination with Housing Provisions clauses 10.2.1 to 10.2.6 and 10.2.12 (floor fall requirements). This pathway uses the AS standard as the technical reference and supplements it with the NCC floor fall rule.

Source: ABCB guidance document, Waterproofing in residential buildings NCC 2022 (verified 2026-05-09); NCC 2022 Vol 2 Part H4, ABCB (verified 2026-05-09).

Comparing the two DTS pathways

FeaturePathway A: Housing Provisions onlyPathway B: AS 3740 + Housing Provisions
Primary technical referenceABCB Housing Provisions 2022 Part 10.2 (free)AS 3740:2021 (paywalled, approx $300)
Clauses that must be followed10.2.1 to 10.2.3210.2.1-10.2.6, 10.2.12 plus AS 3740:2021 in full
Zone requirements (where)Part 10.2.1-10.2.6Part 10.2.1-10.2.6
Floor fall requirementsPart 10.2.12 (embedded in full pathway)Part 10.2.12 (explicitly cross-referenced)
Typical useBuilder or waterproofer following the NCC directlyLicensed waterproofer who works to AS 3740 as their trade reference
In practiceLess common: most licensed waterproofers know AS 3740, not the Housing Provisions by heartMore common: AS 3740 is the day-to-day trade standard

In practice, most licensed waterproofers in Australia work to AS 3740. Pathway B is the de facto standard on residential sites. Pathway A is useful where the builder wants to verify compliance directly against a free, publicly available document without buying the standard.

Both pathways produce the same physical outcome. There is no performance difference between them. The certifier accepts either.

The Performance Solution pathway

The NCC always permits a Performance Solution as an alternative to DTS, including for waterproofing. A Performance Solution is an alternative design that is assessed and documented by a suitably qualified practitioner (typically the private building certifier or a specialised engineer/consultant) to demonstrate that H4P1 is met by means other than the DTS prescriptions.

Performance Solutions for waterproofing are rare in residential construction. They are most relevant where the DTS prescriptions are genuinely impractical: unusual substrate materials, heritage structures, or design features that cannot accommodate standard upstands, hob heights, or floor falls. On a standard residential bathroom, a Performance Solution introduces cost and complexity for no benefit.

If a Performance Solution is proposed, it must be documented and formally assessed before construction and kept in the build file. It does not relieve the builder of the H4P1 obligation; it changes how compliance is demonstrated, not what must be achieved.

Source: NCC 2022 Vol 2 Part H4, ABCB (verified 2026-05-09).

What it doesn’t cover

Class 2, 3, and 4 buildings. NCC Volume Two applies to Class 1 and 10 only. Apartment buildings and similar are Volume One.

External building envelope waterproofing. Roofs, external walls, below-ground waterproofing, and balcony-to-wall junctions on multi-storey buildings have their own NCC provisions (H2 Damp and weatherproofing, and Volume One where applicable). H4P1 covers wet rooms inside the building.

Swimming pools, spas, and tanks. These are excluded from the AS 3740 scope and do not fall under H4P1. Pool waterproofing uses different standards.

Commercial wet areas. Kitchens and wet areas in Class 5-9 commercial buildings fall under NCC Volume One Specification 26 and separate standards, not Volume Two H4.

Practical implications

What the certifier inspects

In most states, waterproofing is a mandatory inspection hold point before tiling. The certifier confirms:

  1. Membrane is installed and fully cured (no tiling over uncured membrane)
  2. Zone requirements from Part 10.2.1-10.2.6 are met (shower walls to 1800 mm, floor falls correct, etc.)
  3. Flood test has been conducted and documented
  4. Waterproofing certificate from the licensed contractor is in the build file

The certifier needs to be able to sight the membrane. Once tiles go down, the inspection cannot happen. Missing this hold point is one of the most common reasons for compliance issues at occupation certificate stage.

Licensing

Waterproofing is licensed work in NSW, VIC, and QLD. The NCC compliance obligation runs through to the builder: it is the builder’s responsibility to engage a licensed waterproofer and to hold the flood test certificate. See AS 3740:2021 for the state-by-state licensing table.

NCC 2022 vs NCC 2019 for waterproofing

NCC 2022 restructured the waterproofing provisions compared to NCC 2019. In NCC 2019, the wet area waterproofing requirements were under the Housing Provisions (then part of the NCC directly, not a separate document). NCC 2022 separated the Housing Provisions into a standalone ABCB document and introduced H4D2 and H4D3 as distinct clauses. The technical requirements are largely consistent with the old F1.7 provisions, but the clause numbering and document structure changed.

For work under building permits issued under the NCC 2019 adoption cycle, check the applicable state adoption dates. Most states had adopted NCC 2022 by 2023-2024, but state adoption is staggered.

State variations

States may apply variations to the NCC. The ABCB Housing Provisions list SA variations for Part 10.2. As a general rule, the national DTS provisions apply unless your state’s adoption instrument specifies otherwise. Check with the building certifier if in doubt. Detailed per-state callouts below.

State variations

WA

Western Australia commenced NCC 2022 on 1 May 2023 under the Building Regulations 2012, with a 12-month transition window allowing permit applications under NCC 2019 until 30 April 2024 (WA Government, NCC 2022 implementation, verified 2026-05-09). WA does not vary Part 10.2 / H4P1: AS 3740-2021 and the Housing Provisions DTS pathways apply unmodified for wet area waterproofing. WA does, however, license waterproofing as a standalone trade under the Building Services (Registration) Act 2011, with registration administered by Building and Energy and the Building Services Board (Building and Energy, verified 2026-05-09). Waterproofing defects on residential work under $20,000 are covered under the statutory Home Indemnity Insurance scheme for six years from completion. Tolerances are not state-published in WA, so most builders default to the HIA Guide to Standards and Tolerances and the contract spec.

TAS

Tasmania commenced NCC 2022 on 1 October 2022 with a transition period, with condensation and commercial energy efficiency provisions taking effect on 1 October 2023 and livable housing becoming mandatory from 1 October 2024; the 7-star energy and whole-of-home provisions were deferred to NCC 2025 (CBOS, NCC 2022, verified 2026-05-09). Tasmania does not vary Part 10.2 / H4P1, so AS 3740-2021 and the Housing Provisions apply as published. Waterproofing is not separately licensed in Tasmania: the work is performed under a builder licence issued by Consumer, Building and Occupational Services (CBOS) under the Occupational Licensing Act 2005 (CBOS builder licence, verified 2026-05-09). Residential building work over $20,000 must be covered by a residential building work contract; statutory defect liability runs six years for major defects under the Building Act 2016.

NT

The Northern Territory commenced the general provisions of NCC 2022 on 1 May 2023, with the Livable Housing standard following on 1 October 2023 (NT Government, NCC 2022 NT variations, verified 2026-05-09). The NT Appendix carries variations for masonry veneer, special use buildings, energy efficiency, heated water and sanitary drainage, but does not vary Part 10.2 / H4P1, so wet area waterproofing follows the national DTS pathway against AS 3740-2021. Waterproofing is performed under a Building Contractor (Residential) registration issued by the Building Practitioners Board for any work of $12,000 or more; there is no standalone waterproofer licence (NT Building Practitioners Board, verified 2026-05-09). The NT does not operate a statutory home warranty scheme, so warranty cover for waterproofing defects is contractual unless the builder voluntarily holds a private policy.

ACT

The ACT commenced NCC 2022 on 1 May 2023 for general provisions, with livable housing, energy efficiency and condensation provisions following on 15 January 2024 after a phase-in extension (ACT Planning, NCC, verified 2026-05-09). The ACT Appendix does not vary Part 10.2 / H4P1, but Access Canberra has issued Construction Note 01/2023 Wet Areas, which sets the regulator’s expectations for documentation, pre-tile inspection and certifier sign-off, and warns that insufficient or undocumented waterproofing can trigger a Stop Work Notice under section 53 of the Building Act 2004 (Access Canberra, Construction Note 01/2023, verified 2026-05-09). Waterproofing is not a separately licensed occupation in the ACT; it is performed under a Construction Occupations Licence (Builder) administered by the Construction Occupations Registrar under the Construction Occupations (Licensing) Act 2004 (ACT Planning, construction licences, verified 2026-05-09). Residential builders must hold statutory warranty insurance for work over $12,000, with cover running six years for structural and two years for non-structural defects.

The ABCB Housing Provisions 2022 Part 10.2 is free: ncc.abcb.gov.au, Part 10.2 Wet area waterproofing (verified 2026-05-09).

NCC 2022 Volume Two Part H4: ncc.abcb.gov.au, Part H4 Health and amenity (verified 2026-05-09).

AS 3740:2021 is paywalled: Standards Australia store (verified 2026-05-09).

References

  1. Australian Building Codes Board, NCC 2022 Volume Two, Part H4 Health and amenity. https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-two/h-class-1-and-10-buildings/part-h4-health-and-amenity (verified 2026-05-09).
  2. Australian Building Codes Board, ABCB Housing Provisions Standard 2022, Part 10.2 Wet area waterproofing. https://ncc.abcb.gov.au/editions/ncc-2022/adopted/housing-provisions/10-health-and-amenity/part-102-wet-area-waterproofing (verified 2026-05-09).
  3. Australian Building Codes Board, Understanding waterproofing in residential buildings, NCC 2022 guidance document. https://ncc.abcb.gov.au/sites/default/files/resources/2023/UTNCC%20Water%20proofing-residential-buildings-NCC%202022.pdf (verified 2026-05-09).
  4. Standards Australia, AS 3740:2021 Waterproofing of domestic wet areas (product page). https://store.standards.org.au/product/as-3740-2021 (verified 2026-05-09).
  5. Queensland Building and Construction Commission, Waterproofing done right: what you need to know in 2025. https://www.qbcc.qld.gov.au/news/waterproofing-done-right-what-you-need-know-2025 (verified 2026-05-09).
  6. Australian Building Codes Board, Waterproofing in houses. https://www.abcb.gov.au/ncc-navigator/waterproofing-houses (verified 2026-05-09).

See also

Last updated: 2026-05-09. Verified: 2026-05-09. Quarterly review for currency.

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