Ventilation baffle materials & cathedral ceiling – GreenBuildingAdvisor

CZ 3A/4A

2001 gut reno

We’re trying to ensure the sloped ceilings at the knee walls in our attic maintain open ventilation channels. We had our insulation company install Provents, but they did an awful job. They’re incredibly squished, and I’m tempted to scrap the whole thing and start over.

1. Does the material selection for ventilation baffles (plastic like we have vs rigid foam vs wafer board) matter that much if we make sure they’re air tight (tape the sides to the roof sheathing, tape between each baffle seam, etc.)? Trying to prevent condensation and mold, so do we need a more vapor permeable option in our climate.

2. If we keep the plastic baffles, is there a way to create braces/blocks in the middle of them to make sure the channels don’t get squished?

3. Do we have to go from soffit up to the hip vent above second floor ceiling insulation? Or can we start at the back of the knee wall and go up above the ceiling? We used rigid foam to block at the knee wall “top plate” (on the attic side).

Thanks!

Stephen