I am in zone 6 (Peterborough, Ontario). I am thinking of installing Intello Plus only on the walls. The directions/videos from the company and the distributor 475 say to use it also on the ceiling for a wood frame house. Would not doing so compromise the air barrier? I am retrofitting an uninsulated cottage, installing Roxwul batts inside and XPS foam panels outside on all sides. It has an unpainted cathedral ceiling whose original surface, rafters, and roof deck boards, I am considering keeping. I am planning to tape the seams of the OSB sheathing on the roof, using 3M 8064, which can be an effective air barrier, and install 9 inches of R5/in foam in 3 staggered layers. I am planning to use Intello’s related items (tapes, gaskets). The Intello membrane cannot be continued from the walls to the roof side, as far as I know, since I am not raising the roof frame. The roof is metal, the visible fastener type, which I plan to reuse. Could Intello be used on the roof side, right next to the deck under the felt? Maybe not, since it should be preserved from punctures, as when installing battens to introduce a gap. I can borrow techniques from an example on the 475 page of using Intello plus with a liquid application, which would be messy for the exposed ceiling. Or I could install Intello and drywall over the spaces on the ceiling between the unpainted exposed rafters. Though drywall is not a permanent solution. – John