Had a weird moment with a brick last week that made me think about creosote differently.

I was cleaning a flue in an old farmhouse outside of Lexington, and a single brick in the firebox was just coated in this thick, glassy creosote. I've seen a lot of buildup, but this was like black ice. I chipped at it for a bit with my scraper, thinking it was just a stubborn spot. Then it hit me: that brick was way colder than the others around it. The homeowner said they had some masonry work done there about three years ago. I think that repair messed with the heat flow, creating a perfect cold spot for that crap to condense and bake on. It wasn't just a dirty chimney, it was a sign of a deeper problem. Anyone else run into a weird spot like that where the buildup told a bigger story about the structure?

3 comments

3 Comments

sammartinez1d ago

Wait, they just left a single cold brick in there from a repair three years ago? That's wild. I mean, you'd think they'd check the whole area for heat flow after messing with the masonry. Makes you wonder what else gets missed in those quick fixes.

paul_ramirez1d ago

Yeah, that "perfect cold spot" idea is spooky. Did you check if the repair mortar was a different type, like something that doesn't handle heat the same way?

jordan_hill22h ago

Found the same thing, and @paul_ramirez is right about the mortar.