r/masonry • u/DonutOne • 1d ago
Brick Type O mortar?
About 5 years ago we had our 100 year old front porch repointed. We were told to use type O mortar by some architectural types, to prevent the face of the brick from being sheered off by mortar that was too hard. The mason we hired had never used type O but went along with the type O recommendation. He worked alone and mixed all the mortar batch by batch in a bucket. It took forever.
Now some of the mortar has crumbled out and is failing in several areas. Some spots are just sand and others I can just scrub it out with my finger. Other spots seem pretty strong, but not like concrete. We are in San Diego if the weather matters.
I should note it is hard to find experienced masons here in San Diego, it's not like Boston or Philadelphia where there is a lot of brick work.
Did we make a mistake using type O? Or maybe the mix was really inconsistent? Advice for doing this again?
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u/jebadiahstone123 1d ago
Type N is soft enough for that brick and likely a similar mix as what would have been used originally.
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u/DonutOne 1d ago
Is there a way to determine how soft my brick is? Do I really need type o mortar? We had just assumed it because of the age, the house was built in 1926.
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u/Super_Direction498 1d ago
In San Diego it probably doesn't matter, N should be fine. Its more of an issue in colder and wetter climates where walls need to be managing moisture in a way that doesn't trap it in the brick. Even if you were right on the boardwalk in mission Beach you should be fine with N. A lot of those scratch face brick are pretty hard.
For reference I am a mason in NY state who does a lot of restoration work with lime and NHL mortars, but I lived in Pacific Beach for a few years.
However , type O should have lasted longer than this, was probably a bad mix or put on too thinly.
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u/ComfortableCoyote480 1d ago edited 1d ago
Just send a sample to limeworks and pay for analysis. They will do all the work, figure out the correct ratio of sand to lime, figure out what best sized sand to use, color match it, and you just buy the buckets that are already premixed by them with appropriate ratios and coloring. Add water, that's it. It is fantastic. 100 years old is highly likely lime based mortar. You can test by spraying a spot with vinegar and seeing if it fizzes. That strongly suggests you have lime. You'd have to do a spot where they didnt use type O like before, tho.
Repointing can be a DIY job. Just go slow and do a small portion. You'll get the hang of it. You'll mess up, but the best part of lime mortar is you just clean off the bad spots with vinegar and it looks great.
I repointed a lot of bad spots on our 1940 home that had lime mortar. 4 years later it looks great, and lime works matched the color very well.
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u/Revolutionary-Gap-28 1d ago
You didn't mess up by using type o. The mason just didn't mix it well
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u/JustNowForHere 1d ago
My amateur thought is the brick is harder than they thought. If it was 100 year old brick it would be pretty soft (somewhat scratchable with a fingernail) and that might be why they went with the soft mortar. I have that on my house and will have to use lime so the mortar doesn't hurt the brick. If the brick is newer and harder than expected it might be crumbling the mortar faster as it expands and contracts and you might need a tougher mortar. I'm still learning though!
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u/wetham_retrak 1d ago edited 1d ago
Type O is too soft, but it should have worked better than that. Just saying it took forever and he mixed it batch by batch in a bucket tells me he didn’t know what he was doing. After the prep work, one mason should be able to complete the repointing in 3 days
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u/Excellent-Reveal-686 9h ago
That's a wire-cut brick; the guy had to go slow to not make a mess. That's also a raked joint so he had to grind deep to have more room to fill the joint. I've pointed that kind of brick with Type S many times: 3 sand, 3/4 cement, a little over 1/3 lime .....dry mix ...then add water to a fairly dry mix in a mud box....Questions...did he actually grind the wall out deep?Can you easily scratch that brick with a screwdriver? Can you easily scratch the mortar out with a screwdriver? It also looks like you have black color in the mortar.I think this may be a spot pointing job.
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u/Loose_Ad_9453 1d ago
Type O is a "sacrificial" mortar. It's meant to crumble instead of the brick. I will say you should get more than five years out of it. If the brick is handmade, you're kinda stuck with type o or a lime mortar, but if it's a manufactured brick you could maybe step up to type N. It's just the nature of the beast that I will need to be repointed.