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Fastening Lath to Concrete Wall in Basement

Fastening Lath to Concrete Wall in Basement


Old 07-07-19, 12:26 PM
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Join Date: Jul 2019
Location: United States
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Fastening Lath to Concrete Wall in Basement

Hello! I'm hoping to get some input on a project I completed in my basement that I now have serious doubts about. Sorry for the long post, but I want to be thorough:

I had a 50 square foot section of concrete wall that was uneven and pitted and also slightly recessed from the nicer wall to the right of it. This section of wall is shown in the picture with metal lath fastened to it. After putting up the lath, I used the three-coat stucco process to resurface the wall and bring it out to the level of the nicer wall to the right. I used lath because the wall was painted so there would be no chance of a good bond with the existing wall. I completed the project back in November as a complete newbie to stucco.

Eight months later, the wall looks fine, but after learning more about this recently, I've realized I made some key mistakes on it. I believe the three coats were done correctly, with each properly moist-cured, but unfortunately I...

1) used 3/4" fluted masonry nails, which went in snugly but seem dinky in retrospect.
2) put the nails in a grid pattern (as you can see) instead of staggering them.
3) used #10 flat washers with the masonry nails instead of lath and plaster washers.
4) used that light-weight expanded lath from home depot that may not be adequate for three coats. I furred the lath manually, which is also not ideal, so that the stucco would key behind it.

What I'm most worried about now is that the nails are not going to hold what's essentially a 500 lb slab of stucco standing on its side. Is there a risk of this new wall just falling down someday or would it fail more gradually over time? If it needs to be reinforced. what could I do about that now?

Thanks in advance.

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Old 07-07-19, 12:57 PM
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Join Date: Sep 2016
Location: USA MI
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Is there a risk of this new wall just falling down someday
Maybe, maybe not!

Honestly from a brief description and a couple of pictures it's not possible for any of us to predict what might happen.

My question, what was the intent of the repairs?

If just cosmetic would it have been easier to erect walls and finish the basement, or at least the one wall?
Old 07-07-19, 06:56 PM
Join Date: Jul 2003
Location: California
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You should have run all your lath horizontally. When run horizontally there is a right and wrong way to run it. I can't tell from the picture if you got it right or wrong. It is too late now anyway. 3.4# lath would probably have been better. 2.5 is probably fine. You used plenty of nails. You usually know immediately if you have a nail failure so if they seemed to hold you are fine.
Shorter nails probably hold better than longer ones. My rule of thumb is use the longest possible that go into the concrete without failing or bending. And of course the longer the nail the less you beat your fingers.
I don't think you will have a catastrophic failure. Give your wall plenty of time to cure then tap on it with a light hammer or screwdriver handle. You will know if it sounds solid or not and even if not you will have some warning if it ever fails. It will buckle or bulge or come away from flush with your good wall at which time you can decide if you want to do anything about it.
Oh, the washers. not a problem. I've done this a lot. How did you drive your nails and protect your fingers?
Oh and one more thing. Making it furred yourself works. I have done that too without problems
Old 07-09-19, 07:14 AM
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Join Date: Jul 2019
Location: United States
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tightcoat, thanks for the detailed response! I feel a bit more reassured now that it might hold up and, if not, that it won't outright collapse.

I had no idea there was a right and wrong way to run the lath horizontally. Aside from the obvious difference between running it vertically and horizontally, the lath looks roughly symmetric to me. Also, the wall has been curing for 8 months now, and it sounds solid when I tap it. I drove in the nails with a small sledge hammer after pre-drilling, which seemed to work pretty well...with no risk to my fingers.

Marq1, the intent was cosmetic, yes. I wanted to blend the new wall with the existing one, and this approach seemed most feasible for an inexperienced DIYer. I like the look of stucco too.
Old 07-09-19, 07:27 AM
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Join Date: Jul 2019
Location: United States
Posts: 3

By the way, here's the finished wall (painted beige) with some candle holders I made to cover up the seem with the new wall, which didn't blend as well as I'd hoped. You can see some vertical streaks in the top coat, but all-in-all, I'm happy with the appearance, so I hope I don't have to redo it, lol.
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