"Floor" in this case refers to the plywood upon which my furniture rests. Beneath the "floor" is a crawl space with a dirt surface which is damp but not wet. The crawl space is well ventilated and essentially the same temperature and humidity as outside. Pipes are insulated but there is no insulation between the joists. Therefore, when it is zero degrees outside, the kitchen floor inside is around 45 degrees. At one end of the house, the crawlspace is barely a foot high and at the other end it is four feet high. I've seen a "profile" of the topsoil at the nearby quarry. The soil is clay approx two feet deep on top of solid limestone so drainage beneath the clay is poor, although with it being on the side of a mountain, there is no surface accumulation of water. It helps that I'm 10 vertical feet from the top of the 300 foot mountain. The question is, what type of insulation to use between the joists? I don't care if moisture from the house goes into the crawl space because the crawl space is essentially open. But, it could be bad if moisture from the house went halfway through the insulation, then condensed and turned the insulation into a soggy, icy mess. I don't know how moisture acts within the insulation fibers when it's 70 degrees in the house and zero degrees outside. I know that in the walls, the purpose of the vapor barrier is so moisture doesn't condense on the inside of the exterior surface, but what happens when the other side of the insulation in unfinished and open to outside air?
Bob