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My uncle said we should stop using lime mortar on old chimneys

He's been laying brick in Charleston for 40 years and swears modern cement mix is fine for any repair. I've always been taught to match the original material, especially on historic work. What's your take on using modern mixes for old brick?
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3 Comments
pat_park
pat_park2mo ago
Hold on, is it really that big of a deal? I see old brickwork patched with modern cement all the time and it's still standing. People act like the bricks will turn to dust overnight. Your uncle has four decades of experience, so maybe the purists are just too worried. If it was truly that bad, we'd see way more failed chimneys around town.
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murray.grace
Doesn't cement crack the old bricks because it's too hard?
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jordancoleman
Honestly, pat_park saying we'd see more failed chimneys misses the point. It's not about sudden collapse, it's a slow grind. That hard cement mortar doesn't flex like the old soft brick, so over years it forces the brick to crack instead. Tbh I see this everywhere, not just chimneys. People use the strongest modern fix for old things without realizing it can cause more damage. It's like using super glue on a delicate antique, you're just making the next problem worse.
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