Why Use A Crawl Space Dehumidifier? Many homes that don't have a cellar truly do have an unfinished crawl space. This is particularly evident in the southeastern United States. In spite of the fact that you may not understand it, unnecessary dampness and stickiness are floating up from your unfinished plumbing space into your home. This is the place where a top notch unfinished plumbing space dehumidifier becomes possibly the most important factor.