I am doing an air sealing and insulation addition project. I want to address the knee spaces and the upper attic. Upper attic has a 3 ton unit with exposed flex duct with R4. The house is a 2005 Cape style. Climate Zone 4. The rafters are 2×8 and have R19 in them. The attic joists are 2×8 (wide span of the house) and 2×6 (narrow span of the house).

I plan to follow this detail (https://www.greenbuildingadvisor.com/app/uploads/sites/default/files/GBA_INDIVIDUAL_PDF_FILES/GBA_PDF_Series-5/5-01005.pdf) to insulate the knee wall. My question is regarding beyond that. I can install foam board along the underside of the rafters and air seal that to the top of the knee wall.

But beyond that, I have not found an article or detail detailing how to address the upper attic floor where it rises from an air dammed bay. I realize air doesn’t have an ingress point, however wouldn’t there still be thermal effects attempting to move heated air up and out and change it with cold attic air? Would I not want to seal the rafter bay here, too, keeping the drywall joint on the slope-side of the air dam?

My second part pertains to the sections of the house that are NOT paired with knee walls. These run down to the back side of a porch overhang, or straight to soffit vents. Would I air dam these at the top, too?

In essence- doing the upper attic, would I want air dams in each rafter bay?

My last question is regarding the stud walls on the other two sides. I can see down onto dusty fiberglass batts. I would want to air seal across these tops as well, right?

My worry is that I proceed with damming as I’ve stated and found out that I’m trapping moisture or causing a condensation point somewhere unexpectedly.