Attics, Roof Spaces and Roofing
Unconditioned attics must be separated from the conditioned environment by insulation, an air barrier system and a vapour barrier. They should be vented to remove any moisture that has entered from the conditioned interior environment or the exterior environment. The roof shape must effectively shed water and be covered with roofing materials and flashing that will prevent water from entering.
Source : Canada Mortgage and Housing Corporation (CMHC)