We have purchased a new old house in Maine that includes a detached garage. There is a concrete foundation but the garage floor itself is dirt and gravel. I have no idea how waterproof this floor is and wonder how typical this floor is and what can be done to make it waterproof. Can another concrete floor be poured over the existing one? I've read about tiles and mats used on garage floors. Is this a viable and economic solution? I want to use the garage for storage but do not want water to damage what is stored there.