Chimney Leaks: What’s so bad about a little water?

Water damage is the leading cause of chimney decay and can dramatically shorten the life of an otherwise-healthy chimney. With the somewhat drastic environmental changes that we are experiencing in this day and age, the modern chimney is under even greater threat than has historically been the case. Storms seem to be getting stronger and more frequent and are showing up in areas previously unthreatened. With these intense winds and rain accumulations, most chimneys will experience water damage at some point.

chimney with crown damage

What causes a chimney to leak?

There are many factors that can contribute to a leaky chimney and it is not always easy to identify the cause. Most masonry chimneys are built with brick and mortar which are porous by nature. This porosity plays an important role in the function of the chimney but can also cause the brick to decay over time, allowing water to seep in. Once water enters the masonry, it begins to corrode the inside of the chimney and can also lead to lime-leaching and cracks.

As our weather becomes more and more unreliable, we also experience more drastic shifts in temperatures. If water is allowed to enter a porous brick on a warm day and is met by a particularly frigid night, the water expands in its frozen state, constricts in its thawed state and will eventually cause the brick to deteriorate from the inside. This process of decay is known as spalling.

Other common causes of leaks are:

  • Damaged or improperly installed chimney flashing
  • A deteriorating crown
  • A decaying or absent chimney cover

The only way to protect your chimney from the inevitable effects of water damage is to have it professionally waterproofed. With White Glove’s proven products and expertise, you can be confident that your chimney will live a long, healthy life.

Evidence of Water Penetration

efflorescence on a chimney Efflorescence – The white stains on the outside of a masonry chimney indicate that water has penetrated the brick, causing salt to pour out of the chimney.
spalling bricks on a chimney Spalling – When water enters the brick, and continuously freezes and thaws, the affected brick will deteriorate and separate piece by piece from the chimney. This leads to a structurally unsound chimney, and should be taken very seriously.
chimney erosion Erosion – Over time, bricks exposed to wind, rain, and changing temperatures weaken and decay along with the mortar that maintains the integrity of the chimney.


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The chimney crown could be the culprit when it comes to a leaking chimney, so ask White Glove Chimney to perform an inspection and any needed repairs to this often neglected part of your chimney system.