My boat has vinyl or fabric covered foam backed inserts on the sides through out the cabin. These also insulate to some degree. Most have hidden clips to retain them. Vinyl ceiling or headliner. It was reupholstered about two years ago. The P.O. said about 7 grand! Actually pretty reasonable considering the amount of time and material. Even though we are having a very deep hot humid spell there is no mold. I have lots of mold killer buckets all over plus the AC runs 24/7. I’m in my second week of live aboard.