Deck Mud is designed for both interior and exterior use for direct bond to concrete slabs, or to be used with cleavage or waterproof membranes and reinforced with coated wire mesh or galvanized, treated metal lath. Deck Mud is not affected by prolonged contact with water. Use in areas with depressed slabs or use to plumb and square surfaces installed by other trades. Deck Mud used in conjunction with a membrane can eliminate the damaging effects of hydrostatic pressure for on grade slabs. Creates a dense substrate on which to apply ceramic tile or stone.