I am renovating my personal home. It is a 1970s ranch on a basement. We have fully gutted it back to the studs and I am trying to determine best course of action for insulation/air sealing prior to drywall.

Exterior sheathing is plywood in the corners and a gypsum wall board product everywhere else. No house wrap/tar paper/etc over exterior sheathing. Brick or stone facade on all 4 sides of the house with 1”ish air cavity between back of brick and exterior sheathing.

onviously in a perfect world, I would remove the exterior facade, properly detail the exterior sheathing with a membrane and then add a new facade back but that’s not in the budget.

looking for advice on what my best course of action should be on the inside. I am in Stone Mountain, Georgia.

plan is to have conditioned attic with some sort of insulation at the roof line. I was assuming open cell spray foam at the roof applied directly to the bottom of the roof sheathing. Would then eliminate the ridge when i reroof the house. When I reroof, is there a underlayment for asphalt that I should look into to encourage drying to the outside? I was considering vapor dry sa but not sure if it’s necessary. Can I just go regular synthetic felt with ice and water in the valleys? If I wanted to go ice and water everywhere for belt and suspenders approach, am I shooting myself in the foot since it isn’t vapor permeable?

for walls, I am concerned with the fact that I don’t have any sort of exterior waterproofing membrane. I would like to get a better air seal but concerned that if I foam it, I’ll be asking for trouble. Thoughts? I thought maybe I should use mineral wool so that if do get some moisture, the insulation won’t absorb it.  Or would I be fine with a unfaced fiberglass batt? If I did fiberglass batt, would there be any benefit to putting a control layer on the inside face of studs?

Any thoughts or comments are much appreciated!