The problem with fiberglass insualtion in crawlspaces is that they are vulnerable to moisture. Instead of keeping the moisture out of the crawlspace, fiberglass batts absorb humidity, and lose insulation value when they do. When we arrived in this Stamford home, we found that the insulation had already grown heavy with absorbed water, and had fallen from the ceiling. After we removed the ineffective fiberglass insulation, we used closed cell spray foam in combination with our CleanSpace vapor barrier to block out moisture entirely. Closed cell foam is dense and waterproof, and provides an airtight seal along with a high R-value per inch. The owners of this home no longer have to worry about energy loss and high energy bills because of a leaky crawlspace!