26/05/2026
NASH has recently published a new Technical Note:
NTN 009 NCC 2025 Drained and Ventilated Cavities
This Technical Note provides guidance on the new NCC 2025 drained and ventilated cavity requirements for external walls, particularly in climate zones 6 to 8, and how these can be achieved in typical steel-framed construction.
Drained and ventilated cavities – why they matter
Drained and ventilated cavities support moisture management, condensation control and long-term durability by providing drainage paths and ventilation to assist drying within wall assemblies.
The Technical Note also outlines key considerations for ventilation openings, vapour permeable membranes and Total R-Value calculations for steel-framed systems.
