Dense packed cellulose against above grade concrete
I’m building a 2-story house in climate zone 5. Plans are to pour 6″ concrete exterior walls above grade. Then use 8″ metal studs on the outside of the concrete walls for insulation and cladding. The house wrap will go on the metal studs, then a drainage gap, and then cladding (steel).
For the metal studs, we have two options –
1. Screw in the metal studs vertically into the concrete layer. But add a narrow strip (2″ thick and 2″ wide) of EPS between the studs and the concrete to minimize thermal bridging. Then use dense packed cellulose to fill the stud cavities.
2. Build a double wall system with a 2″ cavity between the metal studs and the concrete. Then fill the 2″ cavity and the stud cavity with dense packed cellulose right up against the concrete.
I know the general advice is to put foam or mineral wool on the outside of exterior walls. However, missus would like to minimize using foam insulation in the house. And mineral wool boards are outright expensive.
So this brings up two questions –
1. Which option is better – #1 with metal studs on 2″ EPS on concrete, or #2 with metal studs as a separate wall and a 2″ cavity between the metal studs and the concrete?
2. Is it okay to put cellulose in contact with poured-in-place concrete? What about fiberglass? What if we put poly or house wrap between the insulation and the concrete?