Building Best crawl space doors that last and are as easy to install as they are to use. Cathmer's patent-pending design is different than other crawl space doors on the market. Cathmer crawlspace doors are designed for ease of use and ease of install. The door is designed to limit failure points, allowing for an attractive door that isn't going to rot or rust. Designed by contractors, for contractors & homeowners alike. A crawl space door that any average DIYer can confidently install themselves, with a professional finish.