I live in a small cape cod built in the 1940s with a tucked under garage. The garage and basement are one large space under the whole of the house, including the front porch. The porch is wood slats, and is covered, but open on the sides. In northern Kentucky, we get a decent amount of snow/rain that will blow onto the porch. After insulating the rim joists this fall, the porch floor/basement ceiling seems to be a big energy leak area. What is the best way to seal and insulate this spot, accounting for any issues with moisture trying to get through when there are heavy storms? Will foam board work? Do I need to add any sort of barrier with insulation?