This specification covers flexible, preformed sheet membrane materials to be used as vapor retarders in contact with soil or granular fill under concrete slabs. The specified tests are conducted on new materials and materials that have been conditioned or exposed to simulate potential service conditions. The membranes are classified into 3 classes. The materials shall be subject to tests for water vapor permeance, tensile strength, and puncture resistance. Under special conditions, the material shall also conform to the required flame spread, permeance after soil poison petroleum vehicle exposure, and permeance after exposure to ultraviolet light.