Overtime metal crawlspace doors begin to rust. It normally starts with the lock, once that goes different objects are used to keep the door in place. Without the crawlspace door it's an open invitation for different animals. Once inside your crawlspace squirrels, snakes, and larger animals love to curl up in the fiberglass insulation.
The EverLast Crawl Space Door is the answer to this problem. Made entirely out of completely inorganic plastics and foams. Once installed on your crawl space entryway, they create an airtight, waterproof seal between your crawl space and the cold or humid air outside.