Sealing HVAC into boundary- Is it possible to do without spray foam? – GreenBuildingAdvisor

I have a cape style house, with HVAC in the upper attic. I want to enclose the space a “bring the HVAC inside”. The way I see it, I have only two options. Spray foam (closed cell), or seal & batt.

Seal and batt, I would form or purchase a 2″ baffle made of either foam board or solid plastic (like Smart Baffle) and continue the air channel to the ridge vent. I would seal the baffle edge seams with canned foam or polyurethane caulk for the air and vapor seal. On top of that I would install 7.25″ Rockwool. It would require furring out the rafter bottoms by 2″. LOTS of tedium here I would like to avoid, and I know despite my attempts, my work would never be nearly as air tight as spray foam. It would also take me a very long and time frankly… I don’t want to do any of it.

Spray foam, I would have the contractor install similar 2″ baffles to the ridge vent and spray on, presumably, around 3 or so inches of CC SPF. This would be the air seal, vapor barrier, and insulation in one. I would have the option of furring out and adding Rockwool later. I would ask the contractor to flash the remaining exposed ends of the rafters for thermal bridging unless its recommended against.

I have a contractor coming tomorrow and he will want to use spray foam and I will want to go that route. But I read a lot here about horror stories of off gassing and bad cell structure and y’all have me afraid and non-committal.

What’s the latest advice on sealing in a non-ideal cape attic with HVAC?