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Chimney Crown Damage: Seal or Repair

Cracked Chimney CrownsLike most homeowners, you probably notice your chimney every day. Whether you’re coming home from work, doing some gardening or enjoying the outdoors, the chimney is hard to miss. But do you know what the uppermost section of the chimney is called? If you guessed the chimney crown, you’re right.

What is the Chimney Crown?

The chimney crown is the upper-most portion of the chimney. Its purpose is to allow smoke and fume to vent through the flue to prevent moisture from getting inside. It is built using cement reinforced with a wire mesh for stability and durability. The lip of the crown is sloped to direct moisture away from the chimney.

While concrete is extremely durable, it isn’t impenetrable. And without annual chimney inspections by a certified professional chimney sweep, homeowners have no way of knowing that they may have a problem with the chimney crown until they notice water inside the chimney. The exposure to pounding rain, sleet, and snow can eventually cause the crown to crack under the pressure of Mother Nature. When these cracks begin to surface on the crown, it exposes the interior of the chimney to moisture. Without repairs, the crown will continue to deteriorate. As it continues to decline, the stack is at a higher risk for spalling and cracked bricks and weakened mortar joints that can affect the structural integrity of the chimney. Depending on the extent of the damage, your chimney mason may recommend sealing or repairing the chimney crown.

Sealing the Chimney Crown

If there are a few small cracks in the chimney crown but it is otherwise intact then sealing the crown is a viable repair option. Sealing the cracks will prevent any more moisture from leaking between the walls and flue inside the chimney. The chimney mason will use a specially formulated waterproof sealant that will lock-out moisture but will allow it to breathe to minimize deterioration further.

Repairing the Chimney Crown

Repaired Chimney CrownRather than sealing, repairing the chimney crown is a better option when there are more significant, hairline cracks in the surface. When repairing the crown, a skilled mason carefully fills the cracks with a patch cement material. The entire chimney crown is then sealed with a waterproof sealant to protect the surface. In more extreme repairs where there is major damage such as large chunks missing, or the walls between the flue are exposed, rebuilding the crown is the most reliable and safe option.

Protecting the Chimney Crown

Installing a chimney cap will help protect the chimney and the crown. The cap is attached to the crown and acts like an umbrella keeping the surface underneath dry. A wire mesh surrounds the cap allowing smoke and contaminants to ventilate while preventing small animals, pests, and debris from obstructing the flue. It also has a spark arrestor that protects the roof from hot embers that could otherwise fly out of the vent.