Lightweight Cladding Coversion

Weatherboard usage on class 9b buildings

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

Converting an older dwelling into a Class 9b childcare centre often triggers practical façade challenges, especially when you’re recladding over existing masonry while also introducing new framed external walls. 

In this project, the external wall strategy included a mix of new cladding and recladding over portions of existing brickwork. This kind of hybrid façade can struggle to fit neatly within Deemed-to-Satisfy (DTS) assumptions, because moisture management relies on continuous water control layers, correct treatment of junctions, and robust detailing around openings and terminations

Without a clear performance pathway, the risk is straightforward: wind-driven rain and incidental moisture can enter the wall system, leading to loss of amenity, unhealthy conditions, and deterioration of building elements exactly what F3P1 is designed to prevent. 

What This Really Means

Weatherproofing compliance isn’t just about the cladding product—it’s about whether the entire wall system reliably sheds water and manages any water that gets past the outer face, then discharges it safely to the exterior. For conversions and reclads, the highest-risk points are usually openings, base terminations, roof-to-wall junctions, and service penetrations.

The Solution

A performance-based assessment was prepared to demonstrate that the proposed external wall cladding arrangement satisfies NCC 2022, Volume One, Amendment 2 – F3P1 for the project.

The assessment considered:

• Whether the cladding assembly provides a managed water-shedding façade with a reliable secondary drainage plane
• How moisture is drained and allowed to dry at critical interfaces—particularly where recladding occurs over existing masonry
• How windows, doors, and penetrations are integrated so water is directed back out to the exterior (not into the wall)
• Whether the proposed wall system fits within acceptable weatherproofing verification limitations (including project-specific risk considerations)
• Whether the overall performance is equivalent to, or better than, a conventional DTS wall assembly
• Ongoing maintainability—because façade performance depends on inspections, drainage clearances, and sealing upkeep over time

Rather than relying on a “one-size-fits-all” DTS recipe, the performance pathway focused on proving the façade manages rainwater as a complete system—especially at the junctions where real-world failures typically occur.

Why This Matters

The final report confirms a clear pathway to demonstrate weatherproofing compliance for a childcare conversion involving a mixed façade scope (new walls + recladding). It also reinforces a key point for Class 9b projects: weatherproofing risk is driven by interfaces, detailing, and verification—not just the cladding type.

This is where performance solutions add value: they allow practical construction outcomes while keeping the building envelope compliant, durable, and approval-ready.

Have a similar problem on your project? 

Reach out to our team for the solution.