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  1. #1
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    Default Stucco over masonry or framing

    I'm in a debate with a architect whether the stucco should have masonry backup or should go over the framed wall. The house has a combination of masonry, stone, and stucco. I proposed to use the stucco in areas above roof lines and areas that would need steel to carry the masonry. He would like to have the whole house be veneered in masonry and apply the stucco in areas over the masonry. His concern is the stucco will crack with the movement of the framing. My proposed idea is for cost savings, with over 1000 S.F. of wall area, to be stucco, we could be talking $$$$$, especially if there is a lot of structural steel that needs to carry the masonry. Does the architect have a valid point? If so, does it outweigh the increased cost?

  2. #2
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    Default Re: Stucco over masonry or framing

    Stucco can be applied over framing with control joints and be reasonably free of cracks.

    I am having difficulty "seeing" how this home would be built when you talk about Stucco having masonry backup and structural steel supporting the masonry.

    Can you help me to understand?

    Bill R

  3. #3
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    Default Re: Stucco over masonry or framing

    Bill,

    The architect wants to veneer the entire house including were the stucco is. In order to support some of the masonry, steel I-beams will have to be installed. I don't get the drawings until Thursday afternoon so I really don't know exactly what or how he will handle these conditions. I have no problem doing it the way the architect wants but, if there's no problem with the stucco over the framed wall, I just can't justify the additional expense.

  4. #4
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    Default Re: Stucco over masonry or framing

    OK,
    I do not understand the design.

    So it is difficult for me to comment on the rest but stucco applied correctly should not crack.

    Bill R

  5. #5
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    Default Re: Stucco over masonry or framing

    Maybe the architect is looking for a "sacked" appearance in his stucco. We use it all the time around here. We use a grade B brick, which is cheaper and then apply a thin coat of mortar. By allowing the mortar coat to be thin, the brick lines show through, creating a ghosting affect, which is typical for older style homes. It really looks great.

  6. #6
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    Default Re: Stucco over masonry or framing

    I am also working for an architect who believes materials should not be mixed. If you want a masonry finish (stone, brick or stucco) it should be installed over a masonry structure. That means stucco should be applied over cement block or concrete walls.

    If wood cladding is going to be used it should be over a wood frame.

    We are going to build a stone english manor and the walls will be CMU with cast-in-place concrete floors. Of course I still need to build wood walls and ceilings for my mechanical systems and finishes.

    His theory is the movement ratio of stone to wood makes them incompatible.

    I too worry about how to explain the additional cost to the client. A wood frame with a stone veneer (or stucco) is certainly less expensive then a CMU structure with wood furring walls.
    Adam Greisz

    Wood is Good

  7. #7
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    Default Re: Stucco over masonry or framing

    Quote Originally Posted by Adam Greisz
    I am also working for an architect who believes materials should not be mixed. If you want a masonry finish (stone, brick or stucco) it should be installed over a masonry structure. That means stucco should be applied over cement block or concrete walls.

    If wood cladding is going to be used it should be over a wood frame.

    We are going to build a stone english manor and the walls will be CMU with cast-in-place concrete floors. Of course I still need to build wood walls and ceilings for my mechanical systems and finishes.

    His theory is the movement ratio of stone to wood makes them incompatible.

    I too worry about how to explain the additional cost to the client. A wood frame with a stone veneer (or stucco) is certainly less expensive then a CMU structure with wood furring walls.
    Adam,

    Have you mentioned using ICF's to your boss? You can solve your problems by using them. No furring and apply the stucco directly to them and you are done. With the quality of masonry work today, there's no way I would use cmu's on the entire house.

  8. #8
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    Default Re: Stucco over masonry or framing

    Adam,

    All the walls will be framed. The exterior will be brick and stone veneer. The areas were there is stucco he wants to use masonry veneer, i.e. CMU or brick, under the stucco. I agree this is a more expensive way to go, that's why I suggested furring out the walls were there's stucco. As far as the cost, the owner is willing to pay if the added cost is justified, meaning if there is no problem using the stucco over the framed walls why add the expense.

  9. #9
    Join Date
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    Default Re: Stucco over masonry or framing

    If I understand the design, the upper stucco on wood framing would have to be brought forward to the same plane as the veneer cavity wall below. This would require cantilevering the wall out at the floor line (I guess) and allowing the brick veneer to touch the overhang above which could cause a problem when the wood frame shrinks more than the masonry veneer. If the stucco finish could overlap the masonry there would not be a problem but that could be a difficult or unsightly detail.

  10. #10
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    Default Re: Stucco over masonry or framing

    Sweep,

    I'll have to see the detail the architect has drawn, supposed to be getting the prints on Friday afternoon.

  11. #11
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    Default Re: Stucco over masonry or framing

    Has anyone demo'ed Stucco where Regular Tyvek was used underneath instead of Stucco Wrap, Tarpaper or building paper ? Does the Tyvek hold up under the Stucco. I have been told that overtime the lime that is in the Stucco mix will break down regular Tyvek, has any one seen this happen?-Jud

  12. #12
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    May 2005
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    597

    Default Re: Stucco over masonry or framing

    The surfactants in stucco, hardiplank and cedar will reduce the water resistance of Tyvek and other underlayments. But worse than that is the tendency of stucco to adhere to the Tyvek which eliminates the normal drainage plane.
    Joe Lstiburek covers the issue well:

    http://hem.dis.anl.gov/eehem/01/010902.html

  13. #13
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    Default Re: Stucco over masonry or framing

    Another question.

    Recently we remodeled a 1926 Stucco'ed Tudor in Rye Ny. When we demo'ed the original stucco the build up was as follows: 1x6 T&G sheathing, 1 layer of tar paper, 1/4” x1” furring strips 16”oc, chicken wire nailed to the furring strips and then 3 coat stucco. The Stucco was never in contact with the tar paper because the furring strips held it away and thus created a drainage plain and allowed the Stucco to Key into the chicken wire.

    I asked the Stucco sub to do the same on the new work, but instead he used “Self Firing” Wire lath and said the would have the same effect, but I am skeptical about this as the wire lath seemed to be tight to the tar paper.

    Can anyone comment on “Self Firing” Wire lath, does it create a drainage plain, or is it as I believe intended to hold the wire off the paper just enough so the Stucco can grab on to it ?-Jud

  14. #14
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    Default Re: Stucco over masonry or framing

    I can't be 100% sure without seeing the lath but since the stucco will be touching the underlayment I would say that you are right and the stucco sub is wrong.

    The self-furring lath works only if it is placed over two layers of plastic housewrap or two layers of asphalt felt underlayment (or a combination of the two materials) or if a single layer of asphalt felt is thick enough and of high enough quality (which is hard to find these days) so that the stucco won't adhere to it (creating a thin drainage plane).

    Using vertical furring strips is a smart detail in my opinion and well worth the effort and cost. Be sure to allow water to exit the drainage plane at horizontal interruptions and at the bottom of the wall.

  15. #15
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    Default Re: Stucco over masonry or framing

    You will have a pretty difficult time finding a stucco contractor do the lath method you speak of.

    The self furring lath should go over two layers of paper, the drainage plane is established by the two layers of paper.

    The self furring applys to keeping the wire off the paper enough for the scratch coat to bond to the wire, and it will.

    If oyu are not comfortable with the process ask the stucco sub to show you some older jobes they have done and you can always buy a stucco manual or somply contact the product manufacturers.

    Bill R

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