Hello everyone. This was the first issue I had to solve when my son and daughter-in-law moved into the 390MP. We live in Idaho and it's pretty cold during the winter. All that warmth from inside the rig coming into contact with the cold surface below the mattress created quite a bit of moisture. We took the wood bed board off and tossed it - didn't want mold of any kind in the rig. We found there was no insulation below the board. I added a cross-member and we put some fiberglass bat insulation under the new bed board and also put some foam insulation in the storage compartment under the bed against the floor. This prevented the moisture issue and also kept the bedroom quite a bit warmer.