At construction, a 6-mil vapor barrier is installed in the crawl space. The liner is staked down to the ground adding holes to an already flimsy material. Due to how delicate a 6-mil barrier is, similar to a trash bag, it is easily torn and does not stand up well to the critters and pests that like to make their home in a damp crawl space. Over time, the material deteriorates and is shifted allowing moisture into the crawl space.