Hard to tell for sure without a close look, but the roofing / waterproofing material looks like TPO, a single-ply roofing membrance. It is not made for direct traffic, so appears someone has installe ... read more
Dan, Both Hardie Plank and a 3/4" and 1.5" insulating foam board are good options. There is also the choice of using Insulated Siding that is a custom contoured foam backer. It fits to the specificati ... read more