Tried a new mortar mix ratio for a chimney rebuild in Boise last month

We were working on a 1920s brick chimney and the old mortar was crumbling like crazy. My foreman, Carl, insisted we try a 1:1:6 mix instead of our usual 1:2:9 for the repointing. The extra lime made it way more flexible and it matched the historic color perfectly. Anyone else have a go-to mix for old brickwork?

4 comments

4 Comments

lily573mo ago

Yeah, that extra lime is key for old bricks. Lets them breathe and move a bit. Hard sell on some crews though, they just want the modern stuff.

ward.kim3mo ago

Nice. Carl knows his stuff, that's the right call for old work.

ivan7743mo ago

Read an article a while back about a church restoration where they used the wrong mortar. The modern stuff was too hard and didn't let moisture out. It ended up spalling the bricks, basically pushing the face right off them. That lime mix is slower to work with but it saves the brick in the long run. Some guys just don't want to hear it because it takes more time.

claire_davis311mo ago

Saw the exact same thing happen to a historic library downtown. They repointed with that modern cement mortar and within a few years, whole sections of brick just crumbled. It's heartbreaking because the repair now costs ten times more. That lime mortar is like a flexible joint, it moves with the building instead of fighting it. You're totally right, some contractors just see the clock ticking and go for the fast set.