Fiberglass insulation is the most common type of insulation to put in homes including in the basement/crawl space. Fiberglass is organic and not waterproof which makes it a great material for mold to grow on. Crawl spaces and basements are usually very damp and when fiberglass insulation gets wet it will fall down and make a mess. SilverGlo insulation is inorganic and waterproof. The material works to reflect heat back into the crawl space as well keeping it warmer in the winter months.