I finally saw why old timers insist on lime mortar

I was restoring a 1920s brick wall in Portland last spring and had to match the original mortar. Mixed up a batch of straight Portland like I always do and it just cracked all over after a week. An old mason I know told me to try hot lime mortar instead and the stuff actually flexed with the old bricks. Has anyone else dealt with modern mortar failing on historic brick?

2 comments

2 Comments

tessa3681mo ago

Lime mortar is just trendy right now because some YouTube restoration guy made a video about it. Your Portland cement probably cracked cause you mixed it too wet or didn't let it cure slow enough.

river_hall441mo ago

Figure it's like that whole "natural cleaning products are a fad" thing where people swear bleach is just as good until their stone countertops get wrecked. Portland cement is fine for a concrete driveway or a cinder block wall, but old brick and soft stone need to breathe or you trap moisture and it blows out the face of the brick. Seen that happen on a hundred year old house near me where someone "fixed" the pointing with modern mortar and now the bricks are crumbling after just one freeze thaw cycle. You can baby your mix and cure all you want but the fundamental chemistry just doesn't match the materials in most old buildings.