PDD - INSULATION CHART READING

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    Matthew Bowers

    A2.3.2.5 from ASHRAE 90.1:

    The first rated R-value of insulation represents faced or unfaced insulation installed between the purlins. The second rated R-value of insulation represents unfaced insulation installed above the first layer, perpendicular to the purlins and compressed when the metal roof panels are attached. A supporting structure retains the bottom of the first layer at the prescribed depth required for the full thickness of insulation. A minimum R-5 thermal spacer block between the purlins and the metal roof panels is required unless compliance is shown by the overall assembly U-factor.

    FC stands for filled cavity. The code excerpt is telling you that for this particular climate zone, the minimum R-value for a metal building is for an R-19 fill between the purlins, with an R-10 facing layer.

     

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    Rebekka O'Melia

    Hi Jun,

    I think it's 'filled cavity".  They really should have specified.  "ci" is continuous insulation, so it's different.

    Hope this helps!

    Rebekka O'Melia, Registered Architect, NCARB, B. Arch, M. Ed, Step UP,  Step UP ARE 5.0 Courses

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    Jun Guo

    Hi Rebekka,

     

    Thank you very much for your fast response!!! It is much clear now to me that the R-value is written separately because of two different types. May I ask an additional question according to this one? Why the building is steel frame other than a metal building? How can we tell the metal stud backup wall is a steel frame? 

    The question mentioned  " An architect is reviewing insulation values for a new two-story office building. The building is designed with an aluminum standing seam roof with insulation entirely above the structural roof deck, an exterior brick veneer and metal stud back-up wall assembly, and concrete slab on grade with concrete foundations. Insulation values are as follows: "

    Again, deeply appreciate your kind help here for us!!!

    Jun

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    Jun Guo

    - Mattew,

     

    Thanks for the code information. Somehow I just saw your posting. Thank a lot!!!

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    Rebekka O'Melia

    Jun,

    You are welcome.  I don't have the exam question you are referring to, so I'm not sure if the building in question is metal building or steel frame.  See the * and footnote which defines metal bldg, which is different than what you mentioned, it seems.

    Hope this helps!

    Rebekka O'Melia, Registered Architect, NCARB, B. Arch, M. Ed, Step UP,  Step UP ARE 5.0 Courses

     

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    Charlotte Lu

    just took the practice exam last night and almost struggled with the difference too, until I saw “metal building” is defined in the footnote of the chart.

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    Jun Guo

    - Rebekka

    Many thanks. I noticed the footnote but did not really understand it well at first.

     

    - Charlotte

    I googled " metal building' which is very clear. lol

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    Agnieszka Jastrzebska

    NCARB wants us to read footnotes..:)
    Especially if it is mark with asterisk next to “Metal Building” column.
    Very easy to miss. But I think that type of questions makes us LOOK for footnotes on the exam..

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    Rebekka O'Melia

    Jun,

    You're welcome!  GL on the exam!

    Rebekka O'Melia, Registered Architect, NCARB, B. Arch, M. Ed, Step UP,  Step UP ARE 5.0 Courses

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    Jun Guo

    Hi Matthew, Rebekka, Charlotte, Agnieszka

    I'm writing to update you guys that I finally PASS my PDD exams! Deeply appreciate your time for answering my questions. Thank you all for your help here. :)

    Cheers,

    Jun

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    Agnieszka Jastrzebska

    Wow! CONGRATS! 

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    Jun Guo

    Thanks, Agnieszka! Feel much relief now. Good luck with yours! 

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