Details A chimney can literally fall apart unless properly maintained. CrownCoat will waterproof your chimney crown keeping it from deteriorating. Think of CrownCoat as a brush grade version of their very popular crown repair product CrownSeal. CrownCoat goes on fast and easy with a paintbrush - that's all it takes. Simply put a light coat over the entire crown followed immediately with a thicker topcoat. CrownCoat cures in two to four hours, that's about half the time as other products. Just make sure the temperature stays above freezing for four hours after application. One gallon covers about 40 square feet.