Warm roofs with vapour permeable underlays and normal ceilings
All warm roofs require a continuous vapour control layer (VCL) to be installed on the warm side of the insulation. The VCL should be lapped and sealed and all penetrations of the VCL, e.g. pipes, wires, etc., should be sealed to prevent moisture transfer into the insulation and the fabric of the roof structure. If a well-sealed ceiling is not provided and / or the integrity of the VCL cannot be maintained, then, regardless of the type underlay used a ventilated air space should be provided.
The eave and ridge ventilation is provided to a 50 mm cavity above the underlay.
