ARDEX S 1-K One-Component Waterproofing and Crack Isolation Membrane is an easy-to-use, single-component, load-bearing waterproofing compound that produces a flexible, positive-side waterproof coating for all common interior building substrates requiring protection from topside water exposure that could damage tile installations. It also provides an excellent bonding layer for ARDEX tile and stone setting materials. ARDEX S 1-K can also be used for crack isolation up to 1/8? (3 mm).