Engineers Australia is calling for changes to the National Construction Code (NCC) that could prevent the leading cause of defects in Australian apartments and commercial buildings: water leaks. These leaks account for 80 – 90 per cent of defects and cost building owners and insurance companies up to 3 billion dollars annually.

Industry experts from the Watershedding Community of Practice have collaborated with the Australian Building Codes Board to propose four critical changes to the code:

1. 1. Using gravity: New requirements focus on naturally collecting, redirecting, and draining water, just like the Romans did 2000⁺years ago.
   2. Fixing flat areas: Removing leaks by removing flat surfaces from balconies, roofs, and basement floors, which are common trouble spots for water issues.
   3. Managing underground water: For the first time, we’re addressing underground water. New guidelines for outdoor concrete slabs include casting the following into the structure while being built not after:

1. A slope of (1:80) falls to drainage outlets.
2. A 70mm step down at sliding doors.

• A 70mm edge (hob) around the perimeter.

1. 50mm edges (hobs) at construction joints.

1. 1. Concrete is key: Concrete slabs are vital for waterproofing. Structural engineers must now consider how slabs will sag over 10 years when designing them so the structure will continue to drain.

Engineers Australia and Watershedding Community of Practice member Michael van Koeverden says “Urgent change is required to address building performance and leakage issues. Structural engineers play a critical role in preventing building leaks. While membranes typically last 10-15 years, structural designs are intended to last 40-60 years. When membranes fail, the structure must continue to drain water. The proposed changes to the NCC 2025 aim to address these issues by improving design and construction processes and enhancing collaboration among all parties involved in building projects”.

Engineers Australia CEO Romilly Madew AO says “Engineers Australia is advocating for the proposed changes to the NCC 2025. Engineers are critical to delivering resilient and safe buildings, and we cannot meet Australia’s unprecedented housing demand without addressing the challenges facing the industry. We fully support the government’s efforts to implement comprehensive building reforms. Improving standards is a responsibility that spans the entire industry, including builders, architects, developers, and designers”.

Engineers Australia encourages public feedback on the NCC 2025 improvements related to waterproofing and water shedding. The proposed changes are open for review on the Australian Building Codes Board (ABCB) website.;