The old way of mixing mortar for a 1920s chimney rebuild in St. Paul

I know everyone says you need to add lime to the mix for old brick, but I just did a full rebuild on a chimney from the 1920s with a standard type N mix and it turned out better than the last three jobs where I used lime. The old mortar was crumbling, so we tore it all out. I mixed one part portland cement, one part hydrated lime, and six parts sand for the first few courses, like the books say. It was slow going and the workability felt off. For the rest, I switched to a bagged type N pre-mix. The bond was just as strong, the color match after curing was spot on, and we finished the job two days faster. The homeowner hasn't had a single issue with water getting in after two Minnesota winters. Has anyone else had a good run with modern mixes on historic repair work, or did I just get lucky?

2 comments

2 Comments

coleman.christopher1mo ago

Hold up, you're gonna trust a bag mix over the right recipe? @king.river's uncle might be fine, but that pre-mix is way harder and can wreck old brick over time.

king.river1mo ago

Funny you mention that... my uncle swears by the bagged stuff for his old farmhouse repairs. He says the lime just makes a mess for no real gain.