On the back side of the shop the wall need to be made of some kind of brick or concrete. It also need to be insulated. My wall is made of this new "material" or process from Vartdal. It consists of foam bricks that are set in place, then filled with reinforcement bars and concrete is poured into it. Almost exactly like LEGO. The result is a very strong and completely insulated wall. On the inside the wall must be plated with sheets of plaster for fire proofing. A rather interesting house building concept and a movie of the process can be seen here
