One reason fiberglass insulation is a poor choice for crawlspaces is that it is an area that is vulnerable to moisture. Where the goal is to keep moisture out of the crawlspace, and subsequently the home, fiberglass batts absorb humidity and lose R-value when they do. When we arrived in this Stamford home, we found that the insulation had already grown heavy with dampness and had fallen. After removing the ineffective fiberglass, we used closed cell spray foam on the walls and our CleanSpace vapor barrier on the ground to insulate, air seal, and block out moisture entirely. The owners of this home have improved energy efficiency and home comfort, and lower energy bills because of encapsulating their crawl space!