All parts and pieces are from other projects so no cost was direct to camper. Layed down a layer of material that is normally put down under the engineered hard wood flooring,"used as a sound suppressant" it looks kind of like a compressed wool fabric. On top of that a layer of "reflex" this is closed cell bubble wrap with an aluminum coating on both sides. both can be bought @ big box stores, worjed for us and have not had a problem with moisture under mattress, and this is something you should check when in a cold humid climate.