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Are Chimney Cracks A Critical Issue?

Most homeowners see at least some portion of their chimney virtually every day. From a comfortable distance, everything looks fine, so there is nothing to worry about, right? However, looks can be deceiving. Unbeknownst to the casual observer, tiny cracks may be forming in the chimney. As these cracks continue to expand, water can seep in which can be destructive. Without intervention and repair, the structural integrity of the chimney is at risk.

Weather Causes Chimney Cracks Weather

One of the leading causes of chimney cracks is due to weather. After years of battling rain, wind, and ice, it is not uncommon for small exterior surface cracks to develop in the chimney. Since the bricks are porous, it soaks up moisture like a sponge.



The freezing and thawing that occurs in the winter will widen the cracks further, eventually causing bricks to spall with pieces of brick lying on the ground and gaps in the mortar joints.

Poor Construction

Cracks can also occur when a chimney is not constructed correctly or built on a solid foundation. When the chimney begins to sink into the ground, the shifting structure can cause vertical cracks to appear on the surface. The chimney can also separate from the roof and lean, resulting in more extensive cracks and structural damage. Inadequate clearance between the flue liner and chimney can also cause chimney cracks.

Tree Roots

Nearby trees pose another potential problem for chimneys. Its vast underground root network continues to spread as the tree matures. The roots can grow underneath the foundation, causing it to shift, resulting in cracks in the masonry and foundation. Also, pollen carried by the wind, especially in the spring, can cause plants and weeds to sprout between the bricks in the chimney. Improperly removing the weeds can further damage the masonry.

Satellite Dishes and Antennas

Since the chimney is often the highest point of the home, it is a preferred spot for mounting an antenna or satellite dish.  However, it is not the ideal location. The additional load on the chimney forces a constant downward pressure that can eventually lead to cracks appearing in the masonry. Also, drilling holes into the chimney to secure the antenna or dish is not recommended as it damages the brickwork.  

Seismic Activity

Although relatively rare in the Hudson Valley, seismic activity is not uncommon in New York. A 2.3 magnitude earthquake was recently detected on May 19, 2020, near Wanakah, just 300 miles west of Hudson, NY, according to Earthquake Track. The energy from a small earthquake can travel great distances that cause subtle movements of the chimney and its foundation, that can cause chimney cracks.

chimney brick damagePreventing Chimney Cracks

Most chimneys will inevitably develop some cracks during its life span. The key is early detection and repair. Chimney cracks are easy to repair when they are caught in their early stages through annual chimney inspections. Once the cracks and any missing bricks and mortar are fixed, your chimney technician may recommend waterproofing the chimney to prevent moisture intrusion, which will help avoid weather-related cracks from developing in the future.

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