Proposed NCC2025 Changes to Prevent Water Ingress

Engineers are calling for changes to the National Construction Code (NCC) to prevent water leaks in Australian apartments and commercial buildings, states an article on BuildAustralia.com.au. Water leaks are the leading cause of defects, accounting for 80% to 90% of all issues and costing building owners and insurance companies up to $3 billion annually.

Engineers Australia, in collaboration with industry experts from the Water-shedding Community of Practice and the Australian Building Codes Board, has proposed four key changes to the NCC:

1. Utilising Gravity

The proposed changes advocate for using natural forces to collect, redirect, and drain water. This method draws inspiration from ancient Roman engineering techniques and aims to reduce dependence on artificial waterproofing systems, which can fail over time.

2. Eliminating Flat Surfaces

To mitigate common water issues, the new requirements suggest removing flat surfaces from balconies, roofs, and basement floors, which are prone to water accumulation and leaks.

3. Managing Underground Water

For the first time, the NCC will include guidelines for underground water management. These guidelines recommend incorporating specific elements into the construction of outdoor concrete slabs:

? A slope of 1:80 falls to drainage outlets

? A 70mm step down at sliding doors

? A 70mm edge (hob) around the perimeter

? 50mm edges (hobs) at construction joints

4. Emphasising Concrete Durability

Concrete slabs are crucial for waterproofing. The proposed changes require structural engineers to consider how these slabs will sag over a 10-year period during the design phase. This proactive approach ensures that the structure will continue to drain water effectively, even if membranes fail over time.

These recommendations aim to significantly reduce the occurrence of water leaks and improve the longevity of buildings in Australia.

The NCC is updated every three years, based on required regulatory practices, industry research, public feedback, and policy directions from governments to the Australian Building Codes Board (ABCB) between publishing cycles. Public feedback was invited on the NCC 2025 Public Comment Draft (PCD) until Monday, 1 July 2024, and is now closed.