Q: I need to install fiberglass insulation batts in the drafty crawlspace of the “fix’er upper” house I recently purchased. How do I do this?
A: First, install the insulation in the transition where the foundation wall meets the floor joists. Cut the batts large enough so you can pack the insulation between the joists and wall just tightly enough to prevent it from falling out. Next, install batts between the floor joists so that the vapor barrier is facing upward. You can support the batts from below by fastening chicken wire or insulation stays onto the joists. Install the batts so they are long enough to drape from the mudsill, down the foundation wall and about 2 feet on the floor. Hold the draping insulation in place by nailing a 1-by board over the insulation and into the mudsill. Only tack the nails deep enough to hold the insulation in place while only slightly compressing it. If there is no vapor barrier covering the dirt floor, then install 6-mil plastic over the entire surface, anchoring it with bricks.