The old-fashioned way to insulate a crawl space was to install fiberglass batts between the overhead joists in the crawl space. This is no longer recommended for several reasons. In a crawl space, fiberglass insulation tends to absorb moisture, which causes it to lose R-value and fall out of place, rendering it totally ineffective while also creating a mess. To repair and insulate this crawlspace, we first removed the old insulation. To keep moisture from entering the space, we installed drainage matting beneath TerraBlock foam insulation on the floors, and the CleanSpace vapor barrier above it. On the walls, we used closed cell spray foam. It's perfect for a crawlspace environment! Closed cell foam cures dense and hard and is heavier than open cell foam, and it forms an effective barrier against both moisture and air. After we repaired and waterproofed the crawl space, the owners never had to worry about crawl space humidity and energy loss again!