Chimney Rx Trowelable Chimney Crown Repair is a proprietary elastomeric coating that forms a flexible waterproof membrane. Product is specifically formulated to repair and protect chimney crowns from water intrusion. Chimney Rx Trowelable Chimney Crown Repair can also be used for a variety of horizontal and vertical exterior waterproofing applications. It dries to a natural concrete/mortar appearance. Chimney Rx Trowelable Chimney Crown Repair is an extremely long lasting and durable coating that requires no mixing or special bonding agents.