Andre writes from Buffalo, New York: "I have a unheated crawlspace with a dirt floor. I have faced insulation on the exterior walls and I do have a glass block window with a vent to open. I just installed unfaced insulation in the floor above the crawl space. The floor already had a paper-type insulation already covering the floor part. Was it ok for me to install the unfaced on top of that paper-type insulation? Also, the floor has a (poly) sheething on it but it has blown in insulation on top. Is that correct? If not, can I remove the whole sheething and put new sheething down, and if so what do you recommend to hold it down into place? Can I staple it to the seal plate to cover the voids in the cinder blocks to stop cool air and insects from coming in?"

Answer: Most of your questions are answered on the Owens Corning website page for insulating crawlspaces under floors. The page has complete instructions for such projects including pictures.

Three points to keep in mind: (1) Always install the insulation with the vapor retarder toward the warm side of the structure in heating climates such as yours. In a vented crawlspace, the warm side is usually up, closest to the floor. (2) Once the insulation is in place between the floor joists, insulation hangers or nylon straps should be used to hold the product in place. (3) A 4- or 6-mil. polyethylene vapor retarder should be laid down to completely cover the ground. There is no need for insulation on top of that vapor retarder. I would not staple the polyethylene over the current insulation in the wall because you may trap moisture between the Kraft paper and poly.