Exterior insulation on climate zone 6/7 – GreenBuildingAdvisor

Hello,

I’m planning to reside a house built circa 1960s in northern Michigan climate zone 6/7 (boarder line).

I’d like to add continuous exterior insulation. 

Has 2×4 walls with: 

Outside 1/2-inch plywood-tar paper-wood siding.

Inside foil face fiberglass insulation-drywall-paneling, and wallpaper over all of that.

There is also an addition with clear polyethylene behind the drywall.

Based on the that climate zone I’m in. I would need a minimum R10 exterior insulation to prevent any condensation problems in the walls right?

Would 2 inch XPS foam over a tyvek drain wrap or tyvek and home slicker 1/4 thick work for some place for the moisture to go, or would I need to go with something like 2.5 inches of Rockwool that is vapor open. 

There is no air conditioning in the house although someday there may be.

Thanks, Dan