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Question about repointing old brick in humid climates, saw a mess in New Orleans
I was down in New Orleans last month visiting my cousin and walked past this old Creole cottage, probably 1850s or so, and the brick joints were crumbling bad, like you could pull chunks out with your fingers. The mortar was soft and sandy, which I get is part of the old lime mix, but someone had tried to patch it with a hard Portland cement in spots and it was cracking the brick faces along the edges. Made me think about my own place back home in Savannah, which has similar humidity and old soft brick. I've been reading up on lime putty vs hydraulic lime for repointing, but I'm still torn on what to actually use for a house that gets soaked with rain and 90% humidity. Anyone here done repointing on historic brick in the deep south, and did you stick with a pure lime mortar or go with a modified mix? Also, how do you judge when the old mortar is too far gone to save versus just raking out the top inch and starting fresh?
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tessa_roberts11mo ago
That crumbling and cracked brick faces thing makes my stomach turn, I saw the exact same mess on a row of townhouses here in Savannah. You're right about the humidity being a beast, pure lime putty can wash out way too fast down here unless you stay on top of it like every couple years. I ended up going with a 2.5 to 1 lime putty to natural hydraulic lime mix for my place, it's still soft enough to let the brick breathe but sets up a bit better against all that rain. For judging how far gone the mortar is, I rake out anything that crumbles when you poke it with a screwdriver, but if the bricks themselves are spalling or feel soft, that's when you gotta step back and think about bigger repairs. That hard Portland cement is the WORST though, it's like a death sentence for old brick, better to patch and repoint a little more often than to trap all that moisture in.
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