# Joints to concrete?



## philatx (Sep 11, 2014)

I am working on a job where a masonry guy goofed in placement of a stuccoed wall by a couple of inches. The contractors insist, "No big deal. We will build out one portion of wall with sheetrock, and float the joint to the masonry."

Since masonry and sheetrock react to climate so differently, I am skeptical that this will be a suitable long-term solution. Even with fiberglass tape and a hot-set mud, it seems that the seam will reveal itself in short order. I should add that this is being done in a *very* humid climate in a prominent public area that is not consistently climate-controlled.

My question is, can this be made to work, and to be essentially maintenance-free?? We really need a pretty flawless finish in this location.

The work is now cost-plus on a tight deadline, otherwise I would argue for tearing down and redoing the wall, though the decisions aren't mine to make.

Thanks for any insights/experience.


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## mld (Jul 2, 2012)

Sounds like a good place for an expansion joint, otherwise it will make it's own.


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## philatx (Sep 11, 2014)

That's what I feared. 

It's a renovation on a masonry building with CMU curtain walls. We are making a new stairwell. The masonry guys built a wall upstairs *before* cutting the well, nor verifying the location of a structural beam on the ceiling below, with which the new wall was to align (*sigh*)

The stairwell is a main feature at the entrance, and this seam will be horribly visible in a building that we are trying to make quite elegant and refined.

If we were to use fiberglass tape and a hot-set compound, do you even think it will last a year or two? What if we used something other than sheetrock? 

Or should I just recuse myself from this job now? ;-)

Thanks for your input.
Philatx


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## silverstilts (Oct 15, 2008)

Make a expansion joint as stated earlier, Just use a zip strip (l-bead) then keep it tight or leave a minimal gap and caulk it with something that will expand and contract.


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## spacklinfool (Sep 23, 2011)

*joints to concrete*

Vario would solve that problem...hands down with no tape needed!!!


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## philatx (Sep 11, 2014)

Thanks, guys!

The two walls are in the same plane, and the seam would be on the front and side as one ascends the main, formal, stairwell. A *really* obvious location.

Silverstilts, how inconspicuous could such a joint be? I assume there will be a visible line that really couldn't be finished over to completely make it "go away". (Are we talking about the "Caulk Channel Tear Away Bead" from Trim-Tex?)

Spacklinfool, is the Vario really flexible enough that it would not cause issues? (When I see "sandable" I get a little skeptical about the elasticity of a product.) If we could use it in lieu of caulk, that might be a good option, though I think I would still want to use some fiberglass tape to insure its durability.

Thanks everyone! As I say, my biggest concern is completely avoiding the visible joint here, and not creating maintenance headaches down the road. The guys doing the work just want it to look good enough until they get paid, but I feel it's my responsibility to see to it that it's done right.


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## thefinisher (Sep 2, 2011)

36" wide fibafuse is your answer here. I would float out the whole area and put a solid 3' wide piece down the whole joint. I would then put a second layer of fibafuse over it. As for mud I would go get you some brown bag "Durabond" and add a ton of white glue to it. I would skim it with successive coats of standard quick set (sandable type). I would bet it wouldn't have a chance of cracking then. :thumbsup:


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## moore (Dec 2, 2010)

Is It a poured wall? If so.. How long since the pour?


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## thefinisher (Sep 2, 2011)

Think he said it was Stucco Moore....


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## moore (Dec 2, 2010)

thefinisher said:


> Think he said it was Stucco Moore....


Oh..I see !


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## philatx (Sep 11, 2014)

Apologies -- I should have been more clear on materials.

The wall itself is CMU, and I don't know exactly what it was finished with, but it's something cementitious. It's more portland cement based and not plaster-based. It is the same material on the exterior. 

I think it was described as a "concrete coat" and "brought to a smooth finish". The work was done by the masonry guys, and it's probably about 2 months old.


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## moore (Dec 2, 2010)

philatx said:


> Apologies -- I should have been more clear on materials.
> 
> The wall itself is CMU, and I don't know exactly what it was finished with, but it's something cementitious. It's more portland cement based and not plaster-based. It is the same material on the exterior.
> 
> I think it was described as a "concrete coat" and "brought to a smooth finish". The work was done by the masonry guys, and it's probably about 2 months old.


So your looking at period of good cure time ? I'd go with the expansion joint.. just In case. I've never been asked to do something like that so I can't say for sure how finishing that joint out will last.


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## philatx (Sep 11, 2014)

Thanks. Can that be done to be essentially invisible? If not, I might just let 'em know I don't like our options, and give the owners the heads-up. They might opt for a "better looking" option and plan on high maintenance, though I'm pretty unhappy about it.

Thanks all.


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