This is my first post. I would greatly appreciate any insight to my query. Our home was built in 1903 and at some point in the history of the house, a previos owner had the exterior walls filled with expandable foam, which has since shrunk and separated in various places (determined by an I.R. camera). I need to replace the cedar shake siding come spring and am considering removing the sheathing underneath to expose the framing. I am considering removing the foam and replacing it with R-15 fiberglass batt, then covering with 1" polystyrene sheets and finally wrapping with tyvec before replacing the sheathing and new cedar siding. Does anyone think that this is worth the effort or have any other suggestions? Thanks so much for your help.