Old timer told me my mortar mix was too rich...

Guy I was working with on a repoint job in Baltimore said I was using too much Portland in my mix, making it harder than the old brick. Cut back from a 1:3 ratio to something closer to 1 part cement to 4 parts lime and sand and the joints came out way better... Has anyone else adjusted their mix after getting feedback like that?

2 comments

2 Comments

piper1755d ago

That old timer was looking out for you... modern mortar's way too hard for old soft brick and you'll end up cracking the masonry instead of preserving it. Dropping the Portland and bumping up the lime lets the mortar breathe and flex with the brickwork like it's supposed to. A 1:1:6 mix (cement, lime, sand) has saved me on plenty of historic repoint jobs.

black.margaret5d ago

Pfft, hard disagree on this one. That 1:1:6 mix you're pushing is just asking for trouble in a lot of modern situations. Old soft brick might like it, but if you're repointing anything from the last 50 years, you're gonna end up with a weaker joint that crumbles way too fast. I see it all the time where people go all-in on "breathability" and forget that modern brick is denser and needs a solid bond to hold up against weather. Plus, full lime mortars take forever to cure and can wash out in a heavy rain before they even set.