A basement we just insulated in Bangor, Maine. The Silver Glow 2” foam is a great way to treat the rim joist, it has an R 10. Note that we still caulk and foam all the edges for an air tight fit. On the walls we have our Basement To Beautiful panel, it has an R 15 and allows the homeowner to install their own wall covering over it at a later date. Fine Home Building Magazine states that the # 2 best way to save on your heating bill is to install foam panels on the basement walls, a potential 15 to 20% on the heating bill.