Used to swear by lime mortar for everything, now I see its limits

After repointing a 1920s brick wall in Portland last summer, the lime mix I used just crumbled within 6 months. Turns out modern brick absorbs way less moisture than the old soft stuff, and I should have gone with a Type N Portland mix for that job. Anyone else run into a restoration project where the old-school method just failed?

2 comments

2 Comments

james_kim28d ago

...and the thing is, even the old timers who taught me would admit that lime mortar has its place, but it's not a one-size-fits-all solution. I ran into a similar problem on a 1930s church repoint job a few years back. The original brick was so soft it practically drank the lime mortar, but the replacement brick from a modern batch was like glass. Ended up having to mix a custom batch with a bit of Portland in it to get the strength right without being too hard on the original brick. It's a shame because the old methods worked great for their time, but materials change and you have to adapt.

elizabethg1827d ago

Yeah I've been there too with soft brick and modern replacements. The trick I learned is to wet the old brick really well before applying anything, otherwise it just sucks the moisture right out of your mix and you get a weak bond. For those glassy modern bricks you gotta score the surface a bit or use a bonding agent, otherwise nothing sticks. It's a pain but you can't just use one mix for everything, every job needs its own approach.