DRYLOK Extreme Concrete & Masonry Waterproofer is the ideal waterproofing solution for masonry structures. Its flexible encapsulated polymers provide a durable and aesthetically pleasing finish, while its biocide offers protection against mildew growth. DRYLOK is designed to stop 15 PSI of pressure - more than a wall of water 33 feet high! Perfect for interior and exterior home and commercial projects.