Why Your Chimney Is Leaking and How Stop It

Every chimney services professional will tell you that a leaky chimney is one of the main causes of significant chimney and home damage. They’ll also tell you that all chimney leaks can be repaired or resolved when approached the right way. National Chimney Cleaners of Fairfield County, CT, and Morris County, NJ, would like to share what we’ve found to be the four most common reasons for leaky chimneys and how we go about stopping the problems.

Chimney Brick Repair and tuckpointing in Stamford CTReason #1: Compromised chimney bricks

As strong as bricks are, they won’t hold up forever. Over the years, bricks can crack and let in small amounts of moisture. When this moisture freezes and expands, the bricks begin to deteriorate. Eventually, water is able to run into and through the masonry and damage other parts of the chimney system, as well as the roof, ceilings, walls and attic.Chimney bricks can also be damaged by lightning strikes, hail storms, major house settling and other causes.

Solution: If just select bricks are damaged, we can replace those bricks. If many are compromised, it’s sometimes best to rebuild parts or all of the chimney. Regardless of the solution, the final step is a water sealant to keep water out in the future.

Reason #2: Open chimney top

If you run your chimney without a protective chimney cap, water has a clear path into the flue. This can lead to damage to the chimney liner, the fireplace damper, the firebox and other parts of the chimney and fireplace systems. Anything that negatively affects the chimney liner is a major concern because a liner with holes, cracks or breaks can allow heat, flames and deadly carbon monoxide to escape.

Solution: Have a proper full-width chimney cap installed to shield the flue opening.

Reason #3: Cracks in the chimney crown

The concrete chimney crown that covers everything at the top of the chimney, except for the flue opening, is vulnerable to cracking. Freezing water in cracks, natural disasters and plain old age can seriously harm a crown. When the crown is sufficiently cracked and broken, water can run into the interior spaces of the chimney system, leading to damage to the chimney liner and interior masonry. Intruding water into dark, poorly ventilated spaces can also start a dangerous mold growth.

Solution: We can patch small cracks in the crown. For major damage, we’ll rebuild the crown correctly. Afterwards, the crown should be treated with a quality water repellant.

Reason #4: Issues with the chimney flashing

A fourth common cause of a leaky chimney is problems with the flashing that seals the gap between the chimney and the roof. If warped, rusted out or otherwise compromised, flashing will allow water to run down into the home, damaging building materials as well as the exterior masonry of the chimney. Mold growth is also very possible with a flashing leak.

Solution: We might be able to attach dislodged flashing, but usually the best solution is to have new flashing properly installed.

Chimney Crown Repair in Greenwich CTOther causes of chimney leaks

Above are the four most common reasons for a leaky chimney. There are other possible causes, including excess condensation in the flue and damaged roofing material (which can end up affecting the chimney). The first step with any leak is always an inspection to determine the cause and assess damage.

Get your leaky chimney fixed

National Chimney Cleaners is ready to resolve your leaky chimney. Speak with a chimney expert today at (800) 631-6177, or reach out with our simple contact form. We serve all of Fairfield County, Connecticut, and Morris County, New Jersey.


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