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How to use Zip with continuous insulation stucco systems?

user-5023646 | Posted in Energy Efficiency and Durability on

I live in Denver and am building a custom house that I am hoping to have at lower than 2 ACH50. I see more & more construction using ZIP, so I wanted to use it as a first step toward a tighter house. Additionally I would like to utilize continuous insulation on the exterior to deal with thermal bridging. However the architectural design calls for stucco. While there are some systems, such as Senergy Platinum CI, that integrates continuous Neopor foam (graphite enhanced EPS), Senergy is only willing to provide warranty under their Senergy Platinum CI Stucco system and that warranty is ONLY for material. Given that some insurance companies are refusing to insure this based on its resemblance to EIFS and all that came before, I find it important to have a warranty for a stucco system that resembles EIFS that includes both materials AND labor.

So my question is twofold:
1. Does anyone know a solution that would allow using ZIP with a CI stucco system and still have a full warranty for labor & materials?
2. Is there another way to achieve the prevention of thermal bridging using a standard stucco system without having continuous insulation? Suggestions for optimizing such a system are welcome.

The stucco & insulation industry need to get together and find a way to perfect this. I spoke to engineers and techs from GAF, Owens Corning and STO at the IHB in January and everyone said they had a solution and their “guys” would talk with me after the show. A few months & several emails and phone calls later no one had a solution and the engineers still know there is a gap in this technology. As a LEED AP I would really like to see CI evolve with some tried & true options for homebuilding besides cement board & vinyl siding!

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Tracy,
    Are you the builder or the homeowner? If you are the builder, then you are the one providing the warranty. As a builder, you must provide whatever warranty is required by state law. In addition, you can provide a more generous warranty if you want.

    In order to provide a generous warranty, choose good details and do a good job of installation.

    It's possible to install a continuous layer of rigid foam on the exterior side of Zip sheathing. If you are installing stucco, I suggest that you follow the recommendations in this article: To Install Stucco Right, Include an Air Gap.

    This is the advice given in the article:

    If you’re installing stucco over foam, here’s how to create a ventilated rainscreen gap:
    Install 1x3 or 1x4 vertical strapping on top of the foam, screwed through the foam into the studs.
    Fasten paper-backed metal lath to the strapping, and proceed with a standard installation of three-coat stucco.

  2. JC72 | | #2

    Have you considered ZIP-R? It has a layer of foam attached on the interior face (against the studs) of the panel. The exterior side of the panel is your WRB and you would build the stucco like normal.

    The product is available all the way up to R-12.

    http://www.huberwood.com/assets/user/library/ZS_R-Sheathing_Installation_Manual-(R3-12)v21.pdf

  3. user-5023646 | | #3

    Thank you Martin & Chris.
    I am the homeowner (also a LEED AP) and the GC's insurance company won't insure any stucco system that is installed over insulation - and we looked for coverage from several providers. (That's where the stucco industry needs to educate...but that's a post for another story) However, as I am building to the 2015 IRC/ IECC the use of CI is important to me and I am willing to provide exception for the GC as long as the stucco company will guarantee the system.

    Originally I looked at the ZIP R but they max out at 1.5" providing only R6. That might have been a last resort had we not already sheathed in ZIP as we were led to believe that ZIP would work as an approved substrate. Didn't realize the warranty would only be for materials. After meeting with several stucco vendors and finding a contractor with the appropriate experience for the system, it was brought to our attention that the Senergy warranty only covered the material.

    Just today I received a call and was told that Senergy is willing to make an exception to their system and cover the warranty. Just today their engineer provided a letter specifying coverage using ZIP as the approved WRB with their Platinum CI Stucco system will include both materials and labor as they believe their system is superior to anything on the market. I guess we will be reporting back to this board in a few years to let you know if that is the case ;-) So it appears my dilemma has been resolved.

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