1.1 ,These test methods2 cover the determination of the properties of flexible membranes to be used as vapor retarders in contact with earth under concrete slabs, against walls, or as ground cover in crawl spaces. The test methods are applicable primarily to plastic films and other flexible sheets. The materials are not intended to be subjected to sustained hydrostatic pressure. The procedures simulate conditions to which vapor retarders may be subjected prior to and during installation, and in service.