DAE think using a faster mortar mix on cold days is overrated?

My foreman Jerry swore by Type S mortar when it dropped below 40 last winter, but I swapped to Type N on a 38-degree job and the bond held fine. He made me feel like I was cutting corners, but now I'm wondering if the old rules are just tradition. What's your take on matching mortar type to weather, or do you just grab whatever's closest?

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3 Comments

the_zara3mo ago

Respect Jerry on this one. Type N in cold weather is asking for trouble on tall walls.

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eric_murray263mo ago

N is actually fine down to 20 degrees per ASTM, but I hear you on tall walls.

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angelar572mo ago

Has anyone actually had a Type N joint fail on a tall wall in cold weather? I've used it plenty of times down to 40 degrees and never seen issues, but my experience is mostly on residential stuff not high rises. The cold slows the cure time for sure, but if you batch small and keep the mortar covered, it still bonds okay in my book. Just my two cents though, I know Jerry's got way more years on big jobs than me.

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