The present invention relates to a waterproofing and air barrier coating composition that can inhibit mold formation on interior structural surfaces. The coating composition includes a broad spectrum antimicrobial agent and a waterproofing polymeric composition that can also prevent air penetration. The polymeric composition includes a solvent, a hydrocarbon resin, a polymeric composition, and a filler. The present invention also relates to methods for preparation of such a waterproof coating composition, and methods for preventing mold formation on a structural unit, by applying a coating composition to a surface of the structural unit.