Rethinking mortar mix after a talk with a mason from the 70s

An old timer at the supply house said he used nothing but Type N lime mortar for 30 years and swore modern pre-mixes cause more cracks. He showed me a wall from 1982 that still looked solid. Has anyone else switched back to a lime based mix?

3 comments

3 Comments

angelarivera17d ago

That wall from 1982 that still looked solid" is great and all, but you know what else is solid? The fact that modern pre-mixes are way more consistent and stronger than anything lime based. I've seen too many lime mortar jobs from the 80s and 90s that look fine on the surface but are actually crumbly and soft underneath because one batch got too wet. The old timers forget that they had to babysit lime mortar for days, mixing it wet and letting it sit, and most people today don't have that kind of time. Plus, modern pre-mixes have fibers and additives that actually resist cracking better over time, especially with freeze-thaw cycles. That mason might have gotten lucky with one wall, but I've patched hundreds of lime based failures that just don't hold up to modern weather patterns. Type N lime is fine for historic restoration, but for new work give me a good modern mix that actually cures hard and fast.

ivan_murphy8016d ago

Stick with @angelarivera on this one, but don’t you think the real issue is that neither lime nor pre-mix survives bad labor or wet weather if nobody follows the bag directions? How often do you actually see folks measure water or let it slake properly on a jobsite?

riverdavis17d ago

Yeah so @angelarivera brings up a point about babysitting lime mortar but honestly I've seen plenty of modern pre-mix walls that cracked because the mix was too stiff. A buddy of mine had a patio job from 2019 that looked perfect for two years then all these hairline cracks showed up after one bad winter.