Johnnie writes again from Steele, Missouri: "The problem is that the crawl space is so small. There are trenches to crawl through. The center of the house is 125 yrs. old. It has been added on to twice. The last addition was 125' across back 52 years ago. I was thinking completely filling crawl sp. under north bedroom (15' by 25") with blown insulation. I had a problem with black mold. It is taken care of. I don't want that to start again."

Answer: I would be a little leery about filling the space since my friends at Owens Corning do not have any experience with filling crawlspaces. A typical crawlspace application would have a vapor retarder up against the floor above, a poly sheet on the ground to keep moisture from coming up and ventilation to allow any that does to escape. What you propose will have none of those. We don't have any good recommendations for you, other than to insulate the exterior of the foundation with FOAMULAR® extruded foam insulation and then cover the foam with an appropriate exterior finish.