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The band-joist area can be a challenge to insulate correctly. A lot of contractors don’t want to spray foam into the area, so they opt for less-than-ideal solutions like cutting fiberglass batts and stuffing them into place. If you’re using blown fiberglass or cellulose, National Fiber offers a third way. Its Insul Cube is a fire-rated bag that you fill with blown insulation on the job site, then friction-fit between the joists. You vary the amount of insulation according to the size of the space. If you need to squeeze the bag behind pipes or wires, you can put it in place empty, then fill it. The bags cost $1.35 each.

National Fiber, 800/282-7711, insul-cube.com.