Tried a new mortar mix on an old job and got a crack line I've never seen before

I decided to use a Type S pre-blend on a 1920s brick wall last Tuesday instead of my usual lime based mix and within 3 days a hairline crack showed up along a whole row. Turns out that old soft brick can't handle the rigid bond and it just pulled apart instead of flexing like the lime stuff does. Has anyone else run into problems mixing modern materials with old school brickwork?

3 comments

3 Comments

wilson.joseph1mo ago

Oh man, I learned that lesson the hard way too, now I always stick with a lime based mix for old brick.

piper7791mo ago

Lime based is the way to go for sure. Learned that after a failed job with modern mortar on a 1920s house. Stuff just crumbled right off.

jana_shah1mo ago

Switched to a lime mix after my first brick repair job turned into a hot mess about five years back. Old mortar was basically dust, and the modern stuff just sat on top like a bad glue job. Tried redoing it with a pre-bagged lime blend from the hardware store and it actually stuck and matched the color pretty well. Let it cure slow by covering it with damp burlap for a few days, that made a huge difference. Now I always test a small spot first before committing to the whole wall, saves so much headache later.