Q: I always hear about the importance of insulating the attic, but rarely hear much talk about insulation between the floor joists of crawlspaces? Is this something that should be done? Will it save anything on heating/cooling?
A: If there is no moisture in the crawlspace the insulation will be safe and at the same time assist in keeping the floors above warmer. However, you must be careful not to allow moisture in the area. The insulation will absorb water, and mold and mildew will thrive in this type of environment. For that reason, you should stay clear of insulating the floors unless the crawlspace is encapsulated and has a dehumidifier.