Weather Barrier Liquid EPDM One is a thermoplastic rubber, premium quality, single component waterproofing membrane for metal roofs, concrete decks and roofs that pond water. It is solvent-based and may be applied in a wide temperature range. Weather Barrier Liquid EPDM One as a vapor barrier is suitable for cold-storage applications. It is designed for permanent flexibility and toughness, to bridge and move with hairline cracks.