Tuck-pointing question


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Old 04-16-07, 12:52 PM
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Tuck-pointing question

Hi all,

I am trying to learn tuck and pointing to fix up an 80 year old brick house in CO. The house has one or two feet of dark red brick around the base and for the columns, then the remaining walls, up to the roof, use a light tan colored brick. The mortar in the tan brick is pretty solid. The mortar in the red brick is quite crumbly and when you scratch its gray surface, it crumbles and is like black dust inside.

Does anyone know why the red brick's mortar is this way while the tan brick's mortar still looks pretty good?

I was planning to do the type N mortar plus sand plus fortifier per my DIY booklet but wanted to ask some experts about this first.

Regards,
Dave.
 
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Old 04-16-07, 04:59 PM
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Do you know if all of the brick was laid at the same time? Is there a flashing between the different brick?
 
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Old 04-16-07, 07:13 PM
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Re: Tuck-pointing question

I see no flashing (metal?) between red and tan brick. I think different mortar was used as you suggest.

The tan bricks' mortar has more of a tan color and is mostly hard.

The red bricks' mortar is more grayish on the outside, then black dust when you dig in. Maybe it had a charcoal tint 80 years ago. Whatever it had, it does not seem to have weathered well.

I notice some patching already done to sections of red bricks. Some of these patches lift out in pieces; maybe their mortar had no fortifier.

Not sure what the best approach is for the red bricks. How deep to dig in before adding new mortar? 1/3, 1/2, all the way thru to second layer of bricks? As a do-it-yourself-er, I'd like to leave things at least a little better structurally, rather than just a cosmetic cover-up, but don't think I'm up to rebuilding entire wall sections.

Your advice is much appreciated.
 
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Old 04-16-07, 07:24 PM
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Well, there are a couple of issues. First, if the mortar in the red brick is deteriorating, there must be a reason. If the two were installed at different times, I would say it is likely that the red brick is laid with a strong lime mortar, while the tan has a portland cement mortar. 80 years old is on the weak edge for lime mortar, but it is also possible that the foundation was built earlier.

If there is no flashing, that somewhat eliminates moisture wicking up from the ground, though it doesn't rule it out.

There is a risk to doing a repair without diagnosing what the actual problem is, but to answer your question, the joints should be racked back at least as deep as they are thick, but not much deeper unless the mortar is really bad. Remember that mortar has very low requirements for compressive strength, so soft does not mean it is bad.

A good tuckpointing mortar does not have to be strong, it has to have excellent bond strength and low shrinkage. To that end, it should be lime rich, dry mixed, and hard tooled.


Pictures, as always, are very helpful.
 
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Old 04-17-07, 07:42 AM
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Images

I have two images on disk, I see the {img} tag in this forum, but I don't know where to put my image data anonymously for public viewing. I could put it on my ISP and point to that but would rather not add more personal info to the public domain. Spammers are watching, you know.

What do folks here normally do for posting photos?
 
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Old 04-17-07, 06:04 PM
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Either thier own webspace or something like photobucket.
 
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Old 04-17-07, 07:35 PM
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Smile Photos

I see we can only use smilies in this forum but photobucket is perfect and I can just copy the urls here:

http://i167.photobucket.com/albums/u159/Oachita/070417A003.jpg

http://i167.photobucket.com/albums/u159/Oachita/070417A002.jpg

The first shows what happens when a cracked water pipe sprayed the wall during this cold winter. Water also leaked thru the wall (whoops) and damaged basement floor.

The second photo is a close-up of where I dug into mortar with a screw driver. It is fairly crumbly.

I will try to read up on lime and such. Thanks T.
 
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Old 04-17-07, 07:49 PM
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It appears that the lower section was laid with carbon black as a colorant, then tuck pointed at a later date with regular gray cement. In either case, they did not use masonry sand.

From what little I can tell, I would grind out all the lower joints to 3/8", then tuckpoint with a portland-lime mortar mixed to type N specification (1 part portland to one part type S lime, by volume mixed with 2-1/2 parts sand, also by volume), and hard tool the joints. If you want to keep the dark color, be sure to use only a ferrous oxide powdered pigment. There also appear to be issues with soil in contact with the brick. Is there any waterproofing/drainage on the outside of the wall below grade?
 
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Old 04-19-07, 05:15 PM
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I don't think there is soil in contact with brick in pictures I posted. The brick wall meets a concrete patio. There is leaking probably between patio and brick and maybe into brick, might not know until basement wall is removed. The dirt you see on patio is washed out mortar from last winter.

I will try a section and let you know how it goes.

Thanks again.
 
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Old 05-21-07, 12:01 PM
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Repointed

Hi T and all, here is a picture of my amateur repointing:

http://i167.photobucket.com/albums/u159/Oachita/070521A001.jpg

I used 5 parts Quikrete mortar mix to 2 parts sand, a 50-50 mix of water and Quikrete Concrete Acrylic Fortifier, prehydrated as described here, http://www.quickrete.com/PDFs/Projects/TuckPointingMortarJoints.pdf, mortar hawk and tuck-pointer. I tried a mortar bag, but could not squeeze anything out.

It is hard work!

Do you have any suggestions for cleaning repointed brick surfaces? I scrubbed with rough cloth and water several times but there is still whitish residue near edges where wet mortar touched.

Regards,
Dave.
 
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Old 05-21-07, 12:30 PM
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Tuck-pointing question

I think TS will jump in with better ideas on clean-up that I can give you.

Did you actually use an "Acrylic Fortifier"? That could be part of the reason for a stubborn deposit.

Dick
 
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Old 05-21-07, 02:19 PM
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Sure Klean 600 used in STRICT accordance with directions will take that off no problem. For your next panel, do not try and tool the joint so soon. When you run your jointer across it, it should crumble off, not smear, but still have enough moisture to compact. It is a fine line and a narrow window to hit, but once you find the proper time, it tools very cleanly and easily.
 
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Old 05-21-07, 05:13 PM
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Yes Dick, Acrylic Fortifier is recommended by one of the do-it-yourself guides for improved bonding and water resistance. Guess it may also increase stains.

I will try Klean 600.

I will hold off on tooling too soon. I was waiting longer like you say but when I went back to begin cleaning the slop (before it hardened!), it sometimes flattened a nice curved joint. (But maybe that means it is still too wet.)
 
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Old 05-28-07, 12:41 PM
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Klean 600

Just wanted to post final before-and-after photos and thank you again for your advice:

http://i167.photobucket.com/albums/u159/Oachita/070521A002.jpg

http://i167.photobucket.com/albums/u159/Oachita/070528A001.jpg

Klean 600 works great as photos show. The instructions are for industrial users with pressure applicators though; next time, rather than 1) wetting brick; 2) brushing on acid; 3) scrubbing with pad, I will dip pad directly in acid and go after stains while brick is dry because once brick is wet, it is harder to see smears (so I miss some).

Happy Memorial Day,
~A
 
 

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