We are in the process of building Ralph a new house. I am wondering about insulation. Is it okay to use insulation that would normally be used for a house? The kind you can just get in a roll at Home Depot? My husband is going to build the house with insulation between the plywood walls. We will have a door, hinged roof, and the whole thing will be shingled. Size will be approx. 4x4x4. Heat fixtures will be inside. What can we coat the plywood with to make it fluid proof on the inside? Would it be recommended to drill drain holes on the floor to make it easier to clean? Or would that defeat the purpose of keeping it warm? We are in San Diego.