Sometimes in the process of installing a full perimeter waterproofing system, we will recommend our Moisture Vapor Barrier as an extra layer of protection. CleanSpace Moisture Vapor Barrier is a strong liner material that we install to the walls and floor of the crawl space to prevent moisture, humidity and water from passing through the foundation. It works with our waterproofing system to keep this space dry and healthy, sealing off the crawl space from the earth.