The National Construction Code (NCC) 2022 recently released both Volume One and Volume Two containing a range of waterproofing changes for both internal and external waterproofing.
What are the main changes?
Shower walls must be completely waterproofed
Gradient requirements for surface finishes have changed.
Waterproof membranes must be graded to the drain waste puddle flange.
You can avoid grading the membrane in housing if you only use the NCC (Part 10.2 Housing Provisions) and not the new AS 3740:2021
All commercial wet areas require graded membranes and surface finishes to a drain waste.
Waterproof Shower Walls
The new requirement mandates waterproofing the entire water-resistant wall lining in a shower area to a minimum height of either 1800 mm above the finished floor level or 50 mm above the shower rose, whichever is higher.
Wet Area floors – Gradients
Where a floor waste is installed:
(a) the minimum continuous fall of a floor plane to the waste must be 1:80, and
(b) the maximum continuous fall of a floor plane to the waste must be 1:50.
Membrane – Gradients
New requirement that where the surface finish (e.g. tiles) is required to drain to a floor waste, then the waterproof membrane wherever placed below those finishes must also be graded.
Are graded membranes required in every wet area?
Membrane grading requirements can be applied differently between AS 3740 & NCC Volume 1 & 2.
In Volume 2 residential you can choose to disregard AS 3740 entirely and use all of Section 10.2 that does not require graded membranes to a drain waste. For Volume 1, commercial buildings and units there is no opting out of the graded membrane requirements in any wet area with a drain waste.