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Common Causes of Chimney Leaks and How to Fix Them


Chimneys are essential for many homes, offering warmth and ambiance during cold months. However, they can also be prone to leaks, causing damage to the house's interior if not promptly addressed. At Holloway Roofing, we often encounter chimney leak issues and understand the importance of diagnosing and fixing them correctly.

Common Causes of Chimney Leaks

Damaged Flashing

Flashing is the thin metal sheet installed where the chimney meets the roof. Its purpose is to create a waterproof barrier. Over time, flashing can corrode, lift, or crack due to weather exposure or poor installation. When damaged, water can seep through the gaps between the chimney and roof, causing leaks.

Cracked Chimney Crown

The chimney crown is the cement-like layer that covers the top of the chimney. Its primary function is to prevent water from entering the chimney system. Cracks in the chimney crown can develop due to freeze-thaw cycles, age, or poor construction. These cracks allow water to penetrate the chimney structure and eventually into the house.

Porous Brick and Mortar

Bricks and mortar are porous materials that can absorb water. If the chimney bricks or mortar are old or deteriorated, they can become saturated during rain or snow. This water can then find its way through the chimney structure into the house, causing leaks and potentially damaging the interior walls and ceilings.

Chimney Cap Issues

A chimney cap is positioned atop the chimney to shield it from rain, snow, debris, and animals. Damage, absence, or improper chimney cap installation can result in direct water entry into the flue, potentially causing leaks. Moreover, a compromised chimney cap may cause additional problems like animal intrusion and accumulation of debris.


In some cases, chimney leaks are not due to external water penetration but condensation inside the flue. This can occur when significant temperature differences exist between the inside and outside of the chimney. Condensation forms inside the chimney, drips down, and can sometimes be mistaken for a roof leak.

How to Fix Chimney Leaks

Inspect and Repair Flashing

Examine the flashing at the chimney base for any indications of damage, such as rust, lifting, or gaps. Depending on the severity of the damage, repairs or replacement of the flashing may be necessary. Well-installed and sealed flashing is a barrier, preventing water from infiltrating the roof system.

Repair Chimney Crown

If the chimney crown is cracked or damaged, it should be repaired promptly. This typically involves applying a waterproof sealant or a new layer of crown material to seal the cracks and prevent further water intrusion. Properly maintaining the crown can extend the chimney's life and reduce the risk of leaks.

Waterproof Brick and Mortar

A waterproof sealant can be applied to the exterior of the chimney to address porous bricks and mortar. This sealant helps repel water while still allowing the chimney to breathe. Choosing a sealant specifically designed for chimneys is essential to ensure effectiveness and longevity.

Replace or Repair the Chimney Cap

Inspect the chimney cap regularly for any damage or debris buildup. Replace missing caps or repair damaged ones to prevent water entry and maintain proper chimney function. A well-maintained chimney cap prevents leaks and protects against other chimney-related issues.

Manage Condensation

Consider installing a chimney liner or using chimney insulation to reduce condensation inside the chimney. These measures help regulate the temperature inside the chimney, minimizing the risk of condensation buildup and subsequent leaks.

Understanding the common causes of chimney leaks is the first step in effectively preventing and addressing these issues. Regular inspection and maintenance of the chimney, including flashing, crown, brick, mortar, and chimney cap, can significantly reduce the likelihood of leaks. By proactively addressing these issues and promptly taking corrective measures, homeowners can safeguard their homes from water damage and maintain the long-term integrity of their chimneys.

Contact Holloway Roofing today to learn more!

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