Crawl-space insulating tips

Q: We have no insulation under the floor in our crawl space, and I have heard different versions of the best way to go. I heard that batts (installed under the floor) could get damp and moldy and keep the area damp, and that this might attract termites. I also fear that this space would become too cold and the water pipes would freeze.We now have old rugs in the living room above and the dining room. I want to remove them and just keep the hardwood floors, but without insulation these rooms would be too cold. What do you think?

A: I recently reinsulated the crawl space under the kitchen addition at my house and achieved what I set out to do — narrow the temperature gap between the portion of the kitchen over the basement and the part over the crawl space. So I can speak with a little authority.

According to the code of crawl-space insulating, if there are pipes and uninsulated ducts present, the walls, not the floor above the space, need to be insulated.

To insulate the walls, I’d cover that floor with polyethylene sheeting, so the unfaced R-19 insulation could be laid from the top of the wall-band joist extending out two feet over the floor of the crawl space. The poly is designed to keep ground moisture from rising and causing rot or mold.

In addition, I’d seal the vents and insulate them. If you’re concerned about termites, install a continuous termite shield between the band joist and masonry foundation wall that covers the wall insulation and extends completely outside (or leave a 2-to-4-inch insulation gap at the top for termite inspection).