Keeping the moisture out: Important NCC Updates for Australian Builders
Keeping the moisture out
Building regulations in Australia are shifting with adoption of the NCC 2025 progressively across Australia.
If you’re working in the cooler parts of the country, there are some critical changes you need to know about regarding condensation management and moisture control.
Whether you’re a builder, architect, or developer, staying compliant means understanding how the National Construction Code (NCC) is tightening the screws on moisture control. Here is a breakdown of the latest updates and what they mean for your next project—especially if you’re using Weathertex.
Mandatory wall cavities in cooler climates
For the first time, wall cavities are no longer just best practice, they are a legal requirement in cooler Australian climates. Under HP Clause 10.8.1 (External Wall Construction), drained and ventilated cavities are now mandatory across three climate zones.
Not sure which zone your project falls in? The ABCB maintains an interactive climate map to help you verify.
Weathertex has secured an approved CodeMark Performance Solution, allowing builders to continue using the standard 9.5mm cavity batten within a 9.5mm cavity, despite the general 12mm DtS requirement.
Vapour permeance: Class 4 is here to stay
There has been plenty of industry discussion about membrane classifications, but for Weathertex users, it remains business as usual. The NCC continues to emphasise the use of Class 4 vapour permeable membranes, allowing buildings to breathe while keeping liquid water out.
Weathertex continue to specify Class 4 membranes as per Section 1.4.6 of the Weathertex installation manual in Climate Zone 2 to 8. (In Climate Zone 1 typically use a vapour barrier (Class 1 or 2) and continue to seek further advice from your preferred membrane supplier.) If you’ve been following our guidelines, you’re already ahead of the curve.
Expanded scope: it's not just houses anymore
Perhaps the most significant shift in the updated code is where these condensation rules now apply. Previously focused largely on residential houses and apartments, the updated Part F8 of Volume One extends requirements to a broader range of building classes.
If you are currently working on hospitality or aged-care projects in the relevant climate zones, these requirements now apply directly to your builds. You can find out more information on PCD 2025 – Condensation mitigation
The NCC 2025 tightens the screws on moisture control,but builders and specifiers using the Weathertex system are well placed to stay compliant without significant changes to their workflow. The CodeMark Performance Solution for the 9.5mm cavity, combined with the continued use of Class 4 membranes, means the path forward is clear.
As always, verify your specific climate zone before commencing, and consult the full ABCB guidance for any edge cases on your projects.
Newsletter
Sign up for exclusive Weathertex tips and trends sent straight to your inbox
Sign up for exclusive Weathertex tips and trends sent straight to your inbox
Subscribe
Sign up for exclusive Weathertex tips and trends sent straight to your inbox
