Vent: A chimney job in St. Louis made me change how I mix my mortar for good

I was repointing an old brick chimney last fall, and after two days of work, a big rainstorm rolled through. The next morning, I saw my fresh mortar joints had washed out and sagged... it was a total mess. The old guy who owned the house told me his granddad always added a half bag of lime to every six bags of mix for jobs like that, and I've done it ever since. Has anyone else found a simple mix change that saved a project from the weather?

3 comments

3 Comments

miles_jackson92mo ago

Ever try adding lime like @terry_mitchell?

lily_sullivan821mo ago

YES, exactly this, the whole local weather thing is SO real. I had a job in this old Victorian once near the coast - not even that close, maybe a mile inland? - and the mortar was setting before I could even finish buttering the brick. It was like the wind was sucking the moisture right out of it (I'm pretty sure it was). Someone told me to try the same thing, just a little more lime, and it honestly saved my bacon. It's wild how these tiny tweaks make the difference between a clean finish and something that looks like a dog's breakfast. That old guy giving you the tip was a real one, those little secrets are worth their weight in gold.

terry_mitchell2mo ago

Honestly, it's wild how much local weather changes things. I was doing a small wall in a coastal town once, and the salt air seemed to set the mortar INSTANTLY, like it was in a hurry. My usual mix felt wrong, too stiff. An old mason there saw me struggling and just said to cut the sand with a bit more lime to keep it workable in that damp air. It was a tiny change but it made all the difference. You just don't know until you're in it.