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
John,
I must confess to never having seen that application.
I am not sure the finish would look good or even hold up over the long term. I would also be worried about the potential vapor retarder ... read more