The piers in this crawl space are wrapped with the CleanSpace vapor barrier. This ensures that there are no cracks or openings for which the Earth's moisture could rise into the crawl space from the dirt flooring. The vapor barrier cutting off the flow of moisture from the earth also helps to stop the relative humidity from increasing, which could lead to mold and mildew growth on any organic materials in the crawl space, such as the floor joists and subfloor.