Added on a new family room has a crawl space only 3 ft from ground . I insulated in between the floor joist and screwed 2" foam to the bottom of joist . And ran the duck threw the floor joist as well. It sit on a beam so the ground is dirt and I want to close this in can i or should I cover the ground with plastic. Then what should I use for the outer walls concerned about mold and don't want the wood sitting in the dirt .