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Keep the damp-proof course identifiable and check its height against the finished external surfaces before paving, landscaping or rendering conceals it.

A damp-proof course (DPC) helps prevent ground moisture rising through masonry. A cavity flashing drains moisture out of the wall; one component can sometimes perform both functions.

Where the NCC 2022 Housing Provisions pathway applies

Clause 5.7.4(1)(b) requires DPCs and flashings to run continuously through the wall or pier and remain visible at the outside face. The following table summarises the common clearances in Clause 5.7.4(2). These are DPC clearances, not finished slab heights.

Low-rainfall exception: Clause 5.7.4(2)(d) also specifies 15 mm above finished paved, concreted or landscaped areas in low rainfall intensity areas, or 0 mm where additionally protected from direct weather. Confirm that this exception actually applies to the site and design; it is not a general permission to cover a DPC.

Which locations need attention?

• The bottom perimeter of walls built on a slab, and walls and piers beneath suspended floors.
• Where masonry passes through a roof, or a roof meets an external masonry wall.
• Window and door sill and head locations, with the detailing in Clause 5.7.4(3). The head-flashing exception requires an eave wider than three times the masonry veneer height above the opening.

Check the complete masonry pathway

The Housing Provisions are one compliance pathway. AS 3700 or AS 4773.1 together with AS 4773.2 may be the nominated alternative for a Class 1 project. Do not combine selected details from different pathways. Building Commission NSW distinguishes DPCs from cavity flashings: some flashings that do not act as a DPC may finish short of the outside face under the relevant standards.

Where AS 4773.1 is the nominated design standard, check Clause 14.8.2 for DPC positioning, alongside the construction requirements of AS 4773.2 and the approved details.

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Set the paving level and fall before it is poured. A surface that covers the DPC or blocks required weepholes can compromise wall drainage and prevent compliance being verified.

Check three separate details together: the DPC clearance under Clause 5.7.4, drainage through required weepholes under Clause 5.7.5, and the finished surface falls and slab heights under Clause 3.3.3 of the NCC 2022 Housing Provisions.

Accessible entries need their own coordinated detail. Clause 3.3.3 has a limitation for a landing provided under Clause 2.3 of the Livable Housing Design Standard, except its Clause 2.4 channel drain or drainage surface. Clause 5.7.5 also has specific weephole exceptions. Confirm the approved entry and drainage design rather than applying these tables in isolation.

Read Item 1: damp-proof course location

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Black plastic is not automatically compliant or non-compliant. In NSW, the required membrane grade, branding and installation matter more than its colour.

For projects using NCC 2022 Housing Provisions Schedule 5, NSW 4.2.8 applies beneath a Class 1 slab-on-ground and a Class 10 slab continuous with that Class 1 slab.

The NSW note permits different film colours, including black and orange, where the required high-impact criteria are met. The correct clause references are NSW 4.2.8(2) for material, (3) for branding, (4) for installation and (5) for placement.

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Not by itself. A CodeMark certificate is evidence for its stated scope and conditions; it is not an approval of the whole project.

1. Check the certificate. Confirm it is current and applies to the exact product or system and relevant NCC edition.
2. Match the proposed use. Check the building class, installation details, limitations and every applicable condition.
3. Identify what it covers. Establish which NCC provisions or Performance Requirements it addresses and what remains to be demonstrated for the project.

Does CodeMark replace the performance-solution process?

A certificate covering Performance Requirements supports a Performance Solution; it does not turn the product into a Deemed-to-Satisfy system. ABCB guidance says the A2G2(4) process does not need to be repeated where the certificate fully addresses all relevant Performance Requirements. If coverage is incomplete, further assessment and the applicable performance-solution process are needed for the gaps.

What about a weatherproofing risk score?

If the certificate requires a risk score, document it and satisfy the relevant conditions. Our calculator assists with Table H2V1a; select the applicable NCC edition. The score alone does not establish full H2V1 compliance, satisfy every certificate condition or approve the cladding system.

And EPS foam cladding?

Do not assume an expanded polystyrene (EPS) wall system is Deemed-to-Satisfy because it has a CodeMark certificate or meets a risk-score limit. Confirm the complete system’s compliance pathway, including weatherproofing, fire safety, structural and other applicable requirements, and any product restrictions. Any requirements outside the certificate’s scope still need suitable evidence.

Understand the performance-solution process

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A rainhead needs a compliant overflow arrangement, not simply an opening somewhere in its face. Confirm the design before it is fabricated or installed.

A rainhead receives water from a box gutter and directs it to a downpipe. Its overflow provides a route for excess water if the outlet is blocked. The sizing and arrangement must be assessed as part of the complete roof-drainage system.

Is there only one Deemed-to-Satisfy option?

For a rainhead, the prescribed arrangement described in BPC Practice Note RP 02 uses a full-width overflow weir, with its crest at least 25 mm below the box-gutter sole and the front fully open above the weir. The sole is the bottom of the gutter. This is a summary of that detail, not a complete sizing or fabrication instruction.

It would be too broad to say that every other box-gutter arrangement requires a Performance Solution. A correctly designed sump with a side overflow or high-capacity overflow can also follow a Deemed-to-Satisfy pathway.

What does a Performance Solution involve?

1. 01

   Define the proposal

   Identify the departure and relevant Performance Requirements with an appropriately qualified roof-drainage practitioner. Prepare the required performance-based design brief with the relevant stakeholders.

2. 02

   Demonstrate performance

   Assess the whole arrangement, including design flows, blockage, overflow capacity and safe discharge. Provide calculations, testing or other appropriate evidence.

3. 03

   Document and coordinate

   Record the assessment, conclusions and installation conditions. Coordinate the solution with the relevant building surveyor or certifier and plumbing practitioner before work proceeds.

A product brochure, installer’s assurance or a hole added after installation does not, by itself, document a compliant Performance Solution.

Check the applicable edition. RP 02 is a 2023 practice note. BPC advises that Victorian plumbing work commenced on or after 20 October 2025 must comply with AS/NZS 3500.3:2025. Confirm the edition, state variations and project requirements before relying on older details.

Read more about performance solutions

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