Was skeptical about lime mortar until I tried it on an old house foundation

I always used standard type N for everything, figured lime was just for the history buffs. Last fall I had to repoint a 1920s foundation in Portland where the brick was soft as chalk. Three months later the regular mortar I used on one wall is already cracking, the lime side is fine. Anyone else had better luck with lime on older soft brick?

2 comments

2 Comments

david_stone28d ago

The 1920s brick in Portland is probably what they called "clinker" or soft reds from that era, real spongy stuff. Did you notice if the lime mortar actually let the brick breathe better after it rained hard? I had a similar issue on a 1910 bungalow in Seattle where the old cement mortar was trapping moisture behind the brick and making it spall off in chunks. Switched to a 3:1 lime putty mix on the back wall and the difference in how fast it dried out after a storm was night and day.

danieltaylor27d ago

@david_stone, actually that 3:1 lime putty mix is a bit rich for soft reds. You really want something closer to a 2:1 if you want it to breathe without washing out too fast.