the_julia•1d agoProlific Poster

A drywaller in Denver gave me a warning about lime mortar that I ignored

I was working a small garden wall job in Denver a few years back, and a drywaller unloading his truck next to me saw my bags of Portland cement. He said 'You use that for repointing old brick, you'll crack the face off in a year.' I brushed him off because I was in a hurry and figured he just worked with drywall, not masonry. Three months after I finished a job in Capitol Hill, the homeowner called me showing me hairline cracks in the bricks. He was right. The Portland was too hard for the soft old brick. I had to chip it all out and redo it with NHL lime. Has anyone else ran into trouble mixing modern cement with historic brick?

2 comments

2 Comments

coran631d ago

I used to think lime mortar was just some old-timer superstition until I ran into this exact problem on a 1920s bungalow in my neighborhood. The Portland I used was so stiff it acted like concrete against those soft old bricks, and they started spalling within six months. Now I always test the brick first with a scratch test before I mix anything.

margaret2341d ago

Six months seems fast for spalling unless those bricks were already on their way out. A scratch test tells you a lot but it doesn't guarantee a mortar failure is coming that quick. Could have just been a bad batch of bricks or some frost damage that was already hiding in there.