Waterproofing and Crack-Isolation Membrane Mapelastic WaterStop is a flexible, thin, fast-drying, one-component, liquid-rubber waterproofing and crack-isolation membrane for installation under ceramic tile or stone in residential, commercial and industrial environments. It provides a continuous barrier to protect adjacent floors and rooms below from water damage. Mapelastic WaterStop also prevents in-plane floor cracks (up to 1/8" [3 mm]) from transmitting through tile or stone. In problem areas such as coves, corners, cracks and drains, it can be combined with MAPEI’s optional Reinforcing Fabric or Mapeband™ accessories (cove roll and drain flashing) to provide additional protection.