I’d like some advice on converting an unfinished insulating attic into a finished attic. Live in SE Michigan (climate zone 5),  in a traditional 4 square house and have a walkable unfinished, insulated attic. I air sealed as much as I could and blew 15 inches of cellulose over existing old fiberglass batts. In the process of having a contractor finish my attic with a large bedroom, bathroom and room for an HVAC system. Also, I will be having the roof re done at that time. I haven’t talked much with the builder about the thermal materials they will be using. He said “we’ll take it out and put it in the roof rafters”. We haven’t discussed any further. I planned on doing some of the work myself with either mineral wool or spray foam or a mix of the 2. Any thoughts or concerns? Thanks in advanced.
Rudy