Question about brick

Is it normal for the inside of a brick to crumble when rubbed? I think I could have dug through this brick with my fingernail. This is on a chimney with many spalled bricks.

The fireplace has been boarded up. The cap looked good, so I said it is likely that the flue liner had failed and was not noticed for some time. That can lead to spalling, right?


No, it’s not “normal” for brick to spall, it is obviously failing. Did you try to google what causes masonry spalling? did you come up empty handed? You also have free access to NACHI material that explains this.

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Here is info for you to start.

Common Causes Of Spalling Bricks & How To Fix Crumbling Masonry.
Technical Notes

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I found the image " Chimney Deterioration due to Condensation" in the inspection gallery, and also saw it when I looked through the chimney inspection course again. It shows combustion gases going out through a gap between flue sections. If I understand this better now, it is the moisture that causes the issue as it penetrates the bricks. The nature of the flue gases may not be as important as the moisture they carry. At any rate, it appears the chimney is failing and needs further evaluation by a qualified brick mason.

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Thank you kindly! What a wealth of information!

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Maybe I need to get better at searching the forum. lol

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