How to Repair Chimney Cracks

Repairing Brick Chimney Cracks

Perhaps you've noticed some dampness in your attic. One cause might be a leak in the chimney crown. If there are hairline cracks in your chimney, it's likely that water is entering during pounding rainstorms. These cracks can occur even during new construction, due to shrinkage [source: Carter].

Strong winds can also cause cracks in the mortar. It can take as long as a few months for mortar to reach its full strength. During this curing period, strong winds can create tension. This is why modern builders often insert steel rods into chimneys as they are building [source: Carter].

One solution for leaks in the bricks themselves is to apply a clear silane-siloxane water repellent to the bricks. The water repellent allows the water vapor to escape, but keeps liquid from entering the brick [source: Carter].

If the problem lies with mortar as opposed to the bricks, you know what to do. Head back to the previous page and follow the procedure for mortar repair. You can use this versatile procedure for many chimney types, be it stone, brick or concrete.

Always use a herbicide to kill plants before removing them from a chimney. When alive, they often have their roots or vines settled into the mortar, meaning ripping them away could cause damage. Cut them off at the ground level where they're fully rooted, and then use a putty knife to remove the dead plant [source: Warde].

Keeping your chimney in good repair will allow you to enjoy many hours of safe fireplace use. Use caution when implementing the tips and suggestions you have learned about in this article, and consider hiring a well-respected professional.

For more information, check out the links below.

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  • "Frequently Asked Questions." (Accessed 1/16/09)
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