Found a weird blockage in a flue over in the old part of town

I was working on a house built in the 1920s last Tuesday, one of those big brick places near the historic district. The homeowner said the fireplace hadn't drawn right for two winters. I got my camera up there and saw something solid about eight feet down. It wasn't creosote, it was hard and gray. Took me almost an hour with the rods and a special scraper to break it up and pull it out. Turns out it was a huge chunk of old mortar that must have fallen from the crown years ago and just got packed in by soot over time. The homeowner was shocked, he said three other sweeps had just told him the liner was shot. Has anyone else pulled out something that wasn't creosote or a nest?

2 comments

2 Comments

wyattbennett1mo ago

Yeah, that mortar find is wild but it makes total sense. Those old flues are basically stacked clay tiles, and the mortar between them crumbles after a century. I pulled a whole section of tile out of one once, it just slid down and jammed itself. The soot glues it all together into a fake wall. That's why the camera is so key, otherwise you're just guessing. A lot of guys see bad draft and immediately jump to relining, but sometimes it's just a simple, weird blockage.

the_henry1mo ago

Wyattbennett saying "the mortar between them crumbles after a century" is mostly right, but it's not JUST time. A lot of that old mortar was lime-based, not modern Portland cement. It was MEANT to be a little soft and flexible, but it really can't handle the newer, hotter fires people try to run now. That mismatch causes way more cracks and chunks to fall than just age alone. So you get these weird blockages from a system that worked fine for 80 years suddenly falling apart.