Talked to a mason from the 70s about lime mortar, now I second guess everything

Had a guy come into my local supply spot on Friday, must be pushing 70, been laying brick since before I was born. He watched me grab a bag of Portland mix and just shook his head. Said modern mortar is too hard for old brick, makes the brick fail before the joint does. He went on about lime putty and how you have to let it cure slow, and how his crew would mix in a pit and wait a week. I brushed it off at first, but then I looked at a repointing job I did last summer and sure enough, a couple of the old bricks are spalling. I never thought about matching the mortar strength to the brick age, I just used what the hardware store had. Any of you guys actually switch to lime-based mixes for older structures, or is that overthinking it for residential work?

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1 Comment

rivera.henry16h ago

Did you catch that old episode of This Old House where they talked about how modern mortar basically acts like a sponge holder for water against old soft brick? I read somewhere that lime mortar is meant to be the weak link so it cracks and sheds water instead of the brick face popping off. Honestly for old houses I started cutting my mix with lime putty for repointing, just not the full week in a pit process, and it seems to work alright so far.