Chimneys are usceptible to other common deterioration problems. Partially because of their exposure to the harsh weather elements, repairs to chimneys are among the most common needs when it comes to brick repairs.
Deterioration. Both brick and mortar can be subject to deteriorate over time. While most bricks are hard-fired and should last well over 100 years, many adobe or antique blends are softer and more porous, and may last only 50 years or less. “Spalling” occurs through freeze-thaw cycles, when rain soaks into the brick, then freezes and expands, separating thin layers of the brick from the face. These layers may eventually begin to fall off and be found at the base of the chimney or other exposed walls. Mortar joints can also deteriorate or develop voids prematurely, depending on the type used and the methods employed during original construction.
Cracked Crowns. Simply as a matter of convenience, chimneys are most commonly finished off with a crown built with mortar, although this practice is clearly substandard.Mortar crowns shrink, crack, and deteriorate prematurely, allowing water to enter the top of the chimney. This then may cause brick to pop loose or deteriorate, and contribute to problems with other chimney components and adjoining construction materials.
Chimney crowns should be poured with portland cement or concrete, rather than mortar, or be completely covered with a custom chimney cap.
A basic chimney cap that clamps onto the protruding flue liner can be purchased from a hardware store (in season) and installed by the average do-it-yourselfer. Custom caps made of galvanized sheet metal, stainless steel, or copper can be quite expensive, but are designed to protect the entire top of the chimney. Brick Doctor’s custom caps fit like a glove because there are nine measurements made for each one…and they’re securely installed with masonry anchors drilled into the chimney. These handsome caps provide the ultimate protection for both the crown and the flue.