Ventilated Cold Roof Construction Diagram
50 mm
In a ventilated cold roof construction, a clear void, typically a minimum of 50mm, is maintained between the insulation layer and the roof deck
In a ventilated cold roof construction, a clear void, typically a minimum of 50mm, is maintained between the insulation layer and the roof deck. This void facilitates cross-ventilation, often using battens, and helps prevent condensation within the roof structure.
Basis in regulation
How to check it on site
During construction, check that the specified ventilation void depth is maintained consistently across the roof area.
Common failure
Blocked or insufficient ventilation voids can lead to interstitial condensation, degrading insulation performance and causing timber decay.
Last updated 23 August 2026. This is our editorial summary of publicly available regulation, not building control approval or a warranty determination.