I finally figured out why my chimney crowns kept cracking after two years

For about three years I was mixing my crown mortar way too dry because I thought stiffer meant stronger. It wasn't until I had a job up in Portland last spring where the homeowner was watching me and said 'hey, that mix looks like it's gonna dust out in a season.' I blew him off at first (I've been doing this 12 years, you know?). But I went back and checked some of my older crowns and sure enough, they had these hairline spider cracks all over the top surface. So I tried a wetter mix on the next one, like almost soup consistency but still holding shape, and it cured out smooth as glass. Now I wet the brick edges too before I trowel on the crown, which helps with adhesion. Anyone else had trouble finding that sweet spot with mortar consistency for flat work?

2 comments

2 Comments

rodriguez.jordan20d ago

Wait, you've been doing this twelve years and nobody ever told you about wetting the brick edges? That's like chimney work 101 right there. I had a guy train me back in '08 who would practically spray the whole crown area down with a hose before he even mixed anything.

emerycarr20d ago

Funny you mention that spray bottle trick. Reminds me of this old timer I worked with back in '11 who insisted on soaking his bricks in a bucket of water for like ten minutes before laying them on the crown. He'd grab each one, shake it off, and slap it down. Said it kept the mortar from drying out too fast in the sun. One time he forgot a brick in there for almost an hour and it was so waterlogged it basically squished out all the mortar when he set it. We had to chip the whole thing out the next day. You ever run into someone with a weird ritual like that or did you just get the hose-down method passed down to you?