Problem: Bricks or stones spalling or flaking off. Masonry chimney exteriors take a beating during the winter months by exposure to harsh weather, and can have noticeable damage by springtime. Rain year-round does not help the issue. If you see spalling or flaking bricks, or find pieces of brick on your roof or yard, this is an indication that the bricks have been saturated with water, and subjected to freeze/thaw cycles. Soft type bricks, which are commonly used by masons are more susceptible to water penetration than hard type bricks and may show significant damage in just a few years. Deteriorated or missing mortar joints also need to be addressed in order to prevent water from entering the inside of the chimney where it can cause further damage.
Solution: Remove badly damaged bricks and replace with new similar color and style bricks. Grind out bad mortar joints and point or “tuckpoint” with new matching color mortar and joint style. Then apply a special masonry water repellant sealer to the entire chimney, being careful not to get the solution on the roof, windows, or cars. It is best to hire an expert for the job who knows the proper materials and methods to use.