Vented Dirt Crawlspaces are a disaster waiting to happen. It first starts with the insulation hanging. The ground "moisture" seeps into the air between all the seams and holes in the existing builder grade liners and makes it into the insulation. This is where it will first start to collect. Once the weight becomes to heavy parts of the insulation will start to pull away. A short time after the fiberglass batts begin to fall. If insulation does not come in contact with the surface it has no effect at all on the room it supposed to be insulating.