Rim joist rigid foam combos – GreenBuildingAdvisor

Hi, I’m insulating my rim joists soon in zone 5a. I’ve decided on EPS foam for its vapor permeability and to allow drying in my very old home. I also don’t want to break the bank by using EPS foam exclusively so I am considering using stone wool or a mineral wool batt in the rim joists after the foam board goes in.

How do I determine how much EPS foam board is enough for the interior rim joist to avoid the foam being the new condensation layer?

I haven’t decided on a foam so I don’t have density, perm, or R values.

The articles I’ve found have been about determining exterior rigid insulation needs which isn’t a possibility at this time.