Radon Mitigation and Vapor Barriers Under Slab

Hey folks, does anyone have an opinion about the thickness or spec for our under-slab vapor barrier for radon mitigation? Trying to decide between 15 and 20 mil. thanks Hey folks, does anyone have an opinion about the thickness or spec for our under-slab vapor barrier for radon mitigation? Trying to decide between 15 and 20 mil. thanksRead MoreGreenBuildingAdvisor