Exterior Walls

Use of cladding in a commercial setting 

NCC 2022 Volume One 

Area of NCC Requirements:

• Section F – Health & Amenity

• F3P1 – Weatherproofing of External Walls

• F3D1 – Deemed-to-Satisfy Provisions for Roof and Wall Cladding

 

The Challenge

The architectural proposal includes multiple wall types (WT01 to WT14), many of which are not listed within the DTS provisions of NCC 2022. These deviations create compliance challenges, particularly with weatherproofing standards designed to prevent water ingress and internal moisture accumulation. This non-compliance could potentially lead to unhealthy indoor environments, deterioration of building materials, and legal/approval hurdles in the permit process.

What This Really Means

The NCC’s weatherproofing provisions are not about mandating specific products—they are about outcomes. External walls must resist water penetration, avoid moisture accumulation within the building fabric, and maintain healthy internal environments over the life of the building.

Where DTS tables don’t cover a proposed wall system, a performance-based approach is required to demonstrate that the design still achieves these outcomes. The question becomes whether the wall performs as intended—not whether it appears in a prescriptive list.

The Solution

A performance-based design assessment was undertaken to evaluate the proposed wall systems against the NCC’s weatherproofing intent.

The assessment considered:

• How each wall type manages external moisture and incidental water ingress
• Whether the systems provide continuous weather protection across interfaces and junctions
• How material selection and system configuration influence durability and internal amenity
• Alignment with relevant Australian Standards and accepted construction principles
• Whether the overall performance is equivalent to, or better than, a conventional DTS wall assembly

Rather than applying a one-size-fits-all rule, each wall type was assessed on its ability to achieve the functional outcomes required by F3P1.

Why This Matters

The final report confirmed that all proposed wall systems satisfied the NCC’s performance requirements, provided they are installed in accordance with documented specifications. By adopting a structured performance-based pathway, the project avoided unnecessary redesign while maintaining confidence in weatherproofing, durability, and occupant health.

This case demonstrates how performance solutions support architectural flexibility without compromising compliance. For complex buildings with multiple wall types, they provide a clear, defensible pathway through the NCC—focused on outcomes, not limitations.

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