Sto Gold Coat is a ready-mixed flexible waterproof air barrier membrane for use in StoTherm® ci Systems. It is applied directly to vertical above grade wall sheathing and concrete masonry, and functions as a waterproof air barrier when combined with StoGuard joint and rough opening treatment. Sto Gold Coat is one component of the StoGuard Assembly, a fluid-applied membrane that offers a superior waterproof air barrier.