Second quick question....(I have been saving them up while I searched for a good forum). I want to use the generous dry warm crawlspace of the house for my hobby (model trains) and hobby storage. 1. I will be putting down used carpet all over the concrete without an underlay...just for comfort. Should I put any plastic barrier on the concrete first? The area is nice and dry in all seasons and if necessary I will put a small dehumidifier in later. 2. To help with air quality would it be a good idea to put some venting to the outside from the crawlspace. I had this in past homes. This house seems not to have any. It would be easy. I was thinking even of some vent with closeable louvres....perhaps electrically operated. Or should I wait to see if humidity increases as much as I think it might when used as a living area with me down there breathing heavily? Maybe it won't be so bad. Any ideas and tips on products would be very appreciated. Thanks.