Since he is using closed cell foam the spans can be sprayed as long as there is a batten board for a backer. The closed cell foam will harden and create it's own self supporting wall to an extent. Incredible stuff.
My opinion, do not build a "pole" barn. They are cheaper because there is no "foundation". Instead, you get "pole's" of wood put into the ground. Even in the desert around here the poles will rot or be eaten. Well worth the price of a foundation. I have a few pole barns both in the desert and the high desert and they are not worthy of the cost savings of not having a foundation.
