One of the best ways to accomplish that is to use this Chimney Shield Water Repellent made by Rutland, A single application of this water repellent treatment will protect your chimney masonry from both moisture and freeze/thaw damage, Not only does this repellent block water, but it also allows any liquid to evaporate rather than keeping it locked against the masonry where it could potentially cause damage, This Rutland water repellent can be used with brick, concrete, stone and stucco chimneys, Effective water repellent for masonry chimneys, Protects against spalling and freeze/thaw damage, Unique formula blocks liquid water while allowing water vapor to escape, Safe to use on brick, concrete, stone, and stucco, Cleans up with just soap and water, Can be applied with any low-pressure sprayer, 10-year limited warranty, Coverage:, Soft Brick: 100-150 sq, ft, per gallon, Hard Brick: 175-225 sq, ft, per gallon, Stucco: 100-200 sq, ft, per gallon, Concrete Block: 125-175 sq, ft, per gallon, Natural Stone: usually 75-150 sq, ft, , depending upon porosity, SKU: RTLD320