External waterproofing NCC 2025 Volume One changes explained

External waterproofing rules are changing in NCC 2025. The updates go well beyond a simple tweak to standards. Volume One introduces a new “water management” framework, reshaping how rainwater and other moisture must be managed around buildings. There are major implications for balconies, podiums and flat roofs above internal spaces - especially in Class 2 apartments.

This detailed resource breaks down what’s new in plain language, including the reworked Performance Requirements, new Deemed-to-Satisfy pathways for concrete balconies, mandatory falls in structural slabs, overflow requirements, and where membranes and surface finishes must now sit in the build-up. It also explains what’s changed around drainage design and which situations are exempt, so you can quickly see how your current detailing may need to be adjusted. 

Because waterproofing failures are costly and highly scrutinised, getting these details right at design and construction stage is critical. Access clear, practical guidance to help you update your drawings, subcontractor scopes and site checks. Avoid being caught out by the new rules as NCC 2025 is rolled out across states and territories.

What does it include?

• Overview of changes
• Changes to Part F Performance Requirements
• Managing rainwater impact on the building and adjoining properties
• Drainage systems
• New DtS provisions for balconies
• Overflow provisions
• Substrate materials
• Membrane location
• Surface finishes
• Volume Two
• When the changes take effect