I live in Virginia Beach, VA and have a brick ranch on a crawl space with sand base and moisture barrier over the majority of it. I crawled under the house this weekend to fish some speaker wire and when I was under there I noticed a significant amount of condensation on the bottom of the bat insulation and some of the floor joists. This is under an area that was added on about 15 years ago (original 1955 construction) and though it has 4 or 5 vents in the foundation for that area, all but one are blocked off by the deck that was built onto the house.
My question is, what is the best way to remedy this situation? I'd like to take care of it before my insulation is ruined or even worse, before I start to grow mold. This area has a moisture barrier but truthfully it could probably stand to be replaced/relaid as it's been pulled around all over. I don't seem to have any problems under the remainder of the house and the moisture barrier is in the same condition throughout but the vents are not blocked anywhere else so I'm thinking that is the root of the problem. Should I just install something like this in the one accessible vent (assuming it would fit)?