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  1. #1
    Join Date
    Mar 2009
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    Boston
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    492

    Default Stucco over existing stucco

    I would like to install a finish coat on an existing stucco wall which is in pretty good shape. The reason is to get a smoother texture for client.

    Existing cement stucco has been painted in past. Is there a bonding agent which will allow us to go right over existing stucco without using metal lath?

    Would it make a big difference if wall wasn't painted?

    Realistically, what's the thinnest coat(s) you can add?

  2. #2
    Join Date
    Jul 2004
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    Default Re: Stucco over existing stucco

    Type of paint is important.'
    If it is paint that is firmly bonded it is not an issue.
    However if it is elastomeric it can be a problem.

    Acryl 60 is a typical bonding agent.
    If everything is in good condition you should be able to trowel on a skim coat.
    Another color coat.
    I would check with whatever product is available in your area to see what their instructions say.
    Ask their Tech support people.
    Bill R
    Last edited by Bill Robinson; 05-08-2009 at 07:46 PM.

  3. #3
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    Mar 2009
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    Boston
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    Default Re: Stucco over existing stucco

    paint is firmly bonded, no peeling.

    Is a bonding agent as good as wire lath? Mix the Acry 60 in with stucco or "paint" the existing stucco first.

    how thin can finish coat be?
    Last edited by cdservices; 05-08-2009 at 07:34 PM.

  4. #4
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    Default Re: Stucco over existing stucco

    Wire lath and bonding agents are apples and pomegranates.
    Wire lath will make the top coat very thick.

    I have had good success with brushing the bonding agent according to MFRINST.
    It can be as thin as you can apply it and get coverage.
    If it is 3-coat Portland cement then the existing top coat is as thin as it should have been troweled.
    BTW, it is Portland Cement stucco, yes?

  5. #5
    Join Date
    Jul 2006
    Location
    Portland, OR
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    2,444

    Default Re: Stucco over existing stucco

    You'll have lost any tooth you had when the paint went on, and it will be hard to skim a new coat over old and acheive a different texture.

    The proper way to do it is to sandblast the paint and original finish coat away, leaving the original brown coat. then apply bonding agent an new finish coat over that.

    Since you didn't know how thick a finish coat would be, you probably don't have the skills to get a good finish if you try to DIY this project. You need to call the pros.

  6. #6
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    Default Re: Stucco over existing stucco

    You need to call the pros.
    What he said.
    I worked in a stucco market for years and learned after a couple it was mo-betta' to get a stucco guy in to do the job.
    We used to do a lot of full frame window replacement where the entire frame was removed and a new one was installed to whatever wrb was there.
    This required breaking out stucco and patching after.
    I never saw a stucco applicator who was able to make the patch truly blend in.
    So we (the stucco guys) skimmed the entire surface from corner to corner blend.


    If the paint is well adhered, I did ask that, the stucco will stick.
    However the well adhered is probably a call best left to the stucco guys.
    Stucco Bill

  7. #7
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    Mar 2009
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    Boston
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    Default Re: Stucco over existing stucco

    Sometimes the pro is a 1/2 drywall, 1/2 stucco guy who hasn't changed manufacturers in years and may not be up on best practice.

    The existing stucco is very thick. 3/4" + and on top of that someone adhered board and a finish coat, probably to hide cracking. Don't know if finish coat is acrylic or cement, but the 3/4" stuff definitely is cement.

    Anyway, it's in good shape, we're just looking to smooth out texture and patch around new window install.

  8. #8
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    Default Re: Stucco over existing stucco

    Quote Originally Posted by cdservices View Post
    Sometimes the pro is a 1/2 drywall, 1/2 stucco guy who hasn't changed manufacturers in years and may not be up on best practice.

    The existing stucco is very thick. 3/4" + and on top of that someone adhered board and a finish coat, probably to hide cracking. Don't know if finish coat is acrylic or cement, but the 3/4" stuff definitely is cement.

    Anyway, it's in good shape, we're just looking to smooth out texture and patch around new window install.
    7/8" is typical nominal thickness on three-coat.
    What kind of board?
    How old?
    Maybe it is time to get to the supply shop and see what they have in stock and then make a plan.
    Did you remove stucco around the window?

    I did an article for JLC on replacing doors in stucco. In that one I went back with a trim board for architectural detail and to avoid the need for stucco repair.
    May be too late for that.
    PLease don't plan on the stucco patch to provide any waterproofing.
    I repeat:
    We used to do a lot of full frame window replacement where the entire frame was removed and a new one was installed to whatever wrb was there.
    This required breaking out stucco and patching after.
    I never saw a stucco applicator who was able to make the patch truly blend in.
    So we (the stucco guys) skimmed the entire surface from corner to corner blend.
    Very interesting detail if I get your drift.

    Bill R
    Last edited by Bill Robinson; 05-09-2009 at 12:22 PM.

  9. #9
    Join Date
    Nov 2007
    Location
    Dallas,PA
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    1,045

    Default Re: Stucco over existing stucco

    cd, most of my stucco work was 15-20 years ago and we would have typically sandblasted to remove as much old paint as possible. Cities are not too keen on sandblasting today for a lot of reasons, some of them actually good.

    We did use "WeldCrete" by Larsen, which I am sure would be available in your market. I can tell you we had fairly good results over painted surfaces with this product and a new base and finish coat. I just drove by a job we did 30 years ago and noticed a few spots where delamination seemed to be occurring but I can remember the substrate being particularly bad, so 30 years isn't bad.

    I would also check out the "Sto" site and look at the "Sto prep" stripping products if you want to get back to the original surface. They also have a product called "Restore" which may provide some alternatives.

    When I do a stucco job these days I like the Sto products, they seem to be very innovative and I have never been regretful of using them. We will be doing an "Italianette" style pool house soon and it will have a stucco finish with the Sto products.
    "ALS IK KAN" - Stickley

  10. #10
    Join Date
    Nov 2007
    Location
    Dallas,PA
    Posts
    1,045

    Default Re: Stucco over existing stucco

    cd, if the wall you are dealing with is relatively small, you can try a "needle scaler" for paint removal or check out the Bosch concrete grinder. I loaned a scaler to a friend of mine to strip his basement walls and he did about 1000 sq.ft. in roughly 40 hours. This was on paint that would not strip with any chemical removers. It did leave a nice rough surface for bonding of a new base coat material.
    "ALS IK KAN" - Stickley

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