Rain screen cavity
A rain screen cavity is a drained, ventilated air gap between external cladding and the wall frame. Mandatory in Climate Zones 6, 7 and 8 under NCC 2025.
Ask Chalkline about this →A rain screen cavity is a continuous drained and ventilated air gap between the external cladding and the wall membrane or frame, formed by fixing cavity battens or spacers over the wall wrap before the cladding is installed. The gap allows wind-driven rain that gets behind the cladding face to drain out at the base rather than soak into the frame, and lets moist air escape so condensation does not accumulate inside the wall assembly.
Under NCC 2025 Housing Provisions Part 10.8, a rain screen cavity with a minimum depth of 12 mm and openings of at least 1,000 mm2/m at the base and top of each wall is mandatory for external walls in Climate Zones 6, 7 and 8, effective from 1 May 2026 in Victoria and 1 May 2027 in NSW and QLD (verified 2026-05-10, NCC 2025 HP Part 10.8, ABCB). Cavity battens must be minimum natural durability Class 2 or H3 treated timber.
Also known as: drained cavity, ventilated cavity, drainage cavity.
Category: External wall systems / cladding.
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Last updated: 2026-05-10. Verified: 2026-05-10. Quarterly review for currency.