Cold snap cracked my tuckpointing on a church job in Detroit

We did tuckpointing on St. Mary's church in Detroit back in October. After that freeze last month, I went back to check and found hairline cracks in about 30 feet of joints. My crew used a 3:1 lime mix like always, but I'm wondering if the cold got under it before it cured. Anyone else run into this with historic brickwork in cold weather?

2 comments

2 Comments

kim96322d ago

Oh man, that's rough. I've seen the same thing happen with old brickwork around here too. That 3:1 lime mix is usually solid, but if it got down to like 20 degrees before it was fully set, yeah that cold can mess with the cure and cause those hairline spots. Next time try adding a little bit of accelerator or even just mixing it a bit wetter on the day, it helps it bond better in the cold. Also consider covering it with tarps overnight for a few days after you finish, keeps the frost from getting into the fresh mortar. If the cracks are real fine you might get away with patching them thin, but if they're deep you'll probably have to rake and redo those sections.

victorb1722d ago

Ngl, I gotta push back a little on the accelerator idea. Adding accelerator to a lime mix is risky on old brick like that. Lime needs to cure slow and breathe, and accelerator can make it set too fast which causes even more shrinkage cracking down the road. The wetter mix suggestion is also iffy - too much water in cold weather can freeze before it bonds, which is probably what happened here. Honestly, the real fix is what you said about tarps and keeping the frost off, but skipping the additives. A 3:1 lime mix is the right call, it just needs protection for the first week or so after application in cold conditions. Also, hairline cracks that shallow might not need full raking - you can sometimes just brush a thin lime slurry into them and keep the moisture off for a few days.