Cold weather roof profiles

RobertContractor
| Posted in GBA Pro Help on
For a vented wood frame roof with metal roofing and batt insulation is it advisable to apply poly to the heated side of the space?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details


Replies
Robert,
You need a warm side air-barrier. Poly works well except in hot humid climates.
Products like CertainTeed MemBrain or Intello Plus are Class II/III vapor retarders that allow the assembly to dry to the interior when humidity levels rise — exactly what’s needed in mixed or cold climates. At least you don't need to deal with the hostile work environment letter https://help-center.pissedconsumer.com/how-to-complain-about-hostile-work-environment/ like some of us here.
anrew,
The roof is vented so it dries to the outside. Vapour-drive in cold climates is to the exterior.