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One hour fire rated exterior wall

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  • #1

    One hour fire rated exterior wall

    OK. Need a little help here. Frustration at dangerous level and rising..
    Many times in the past I have drawn/specified and had approved the following as a 1hr. fire rated wall.

    5/8X gyp.bd.int. finish, 2x4 studs 16"o.c., db. top pl., sgl. bot. pl., 3&1/2 FG batts, 1/2" osb/ply'd sheathing with 3&5/8" thk. brick veneer ext. finish.
    Now the new plan checker wants me to indicate a specific assembly listed in the IRC table 720.1 or a UL approved assembly. for a one hour wall.
    There are dozens in the IRC but none exactly like this and only about a gadzillon UL listed assemblies that would take days to search through.

    Anyone have any idea where I might get this information. Thanks
    Tags: None
  • #2
    Re: One hour fire rated exterior wall

    I'm not familiar with the IRC but around here they are always requiring 5/8" DensGlass on the exterior for sheathing. The Fire rating assemblies are provided by the manufacturer and should be in that link.
    "The only communists left in the world are in American Universities."

    --Mikhail Gorbachev

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    • #3
      Re: One hour fire rated exterior wall

      Try UL #U305.

      http://database.ul.com/cgi-bin/XYV/c...XUV%3CIN%3ECCN

      Tom
      1) Unconsciously Incompetent: He knows not, and knows not that he knows not. He is a fool. Shun him.
      2) Consciously Incompetent: He knows not, and knows that he knows not. He is simple. Teach him.
      3) Unconsciously Competent: He knows, and knows not that he knows. He is asleep. Wake him.
      4) Consciously Competent: He knows, and knows that he knows. He is wise. Follow him.

      May we all endeavor to progress from not knowing that we know not, to knowing that we know.

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      • #4
        Re: One hour fire rated exterior wall

        The reason they are asking for a reference number is because you are using a variable/uncontrollable material as one of the layers. The veneer brick at first glance would seem to be a fire-rated material, however, most materials used in these assemblies are independently rated materials having already had their properties tested and analyzed.

        A typical one-hour wall, as shown in U305, is the start point for achieving a rated wall when required at say closer than 3' to the property line or a one-hour rated exterior wall bearing assembly. OK, there are also interior one-hour rated walls, but in this case, the brick veneer tells me its probably exterior.
        Take Care

        Jim

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        • #5
          Re: One hour fire rated exterior wall

          James. Thanks. You are right. I was trying to make the brick veneer as part of the assembly. That's why I couldn't find it anywhere. Actually I have a one hour assembly without the brick veneer. It is item #15-1.15 in the 2003 IRC, table 702.1(2) which we are still using.
          I have to consider the 1 hr. rating from the inside only since I'm more than 5' from prop. line.

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          • #6
            Re: One hour fire rated exterior wall

            I have the IRC2003, both the standard book, and the Connecticut amended versions, and I do not find item 15-1.15 in Table 702.1(2). That table is in the IWall Covering Section of the codebook.

            Now I can find Item 15-1.15 in the IBC2003, page 120, however, that is a 2 hr 2x6 wall assembly.

            What happens is although the base codes are the same, different states adopt different versions, then they amend them for specifics. For example, we use the 2005 CTSBC, Connecticut State Building Code, which is the base IRC2003 "amended" to create our 2005 code. Gets to be a pain sometimes, especially if you work across state lines.

            Anyway, you get the drift of the assembly and how it works; it's pretty difficult to change a part, and keep the assembly rating!
            Take Care

            Jim

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            • #7
              Re: One hour fire rated exterior wall

              James you are right again. I had read the D**m things so many times that I was seeing double. I have know idea what I was thinking.
              However, I did find what I needed. I think?
              "American Wood Council/American Forest & Paper Assoc". ASTM E 119 / NFPA 251
              Thanks for the help.

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              • #8
                Re: One hour fire rated exterior wall

                According to the Fort Worth Building Codes website, the current version of the Commercial Building Code for that jurisdiction is the 2009 IBC (with local amendments) and commercial structural designs are typically required to be prepared by a design professional.

                http://www.fortworthgov.org/Planning...5580_0_31710_3

                See Section 107.1

                It appears you're not even using the correct Code (IBC not IRC) or Code Cycle (2009 not 2003)


                You will likely do best to have a professional designer handle this submittal for you.

                The designer will know what to provide and save you all the wasted time and frustration not knowing where to begin.

                Good Luck.

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                • #9
                  Re: One hour fire rated exterior wall

                  UL listings for fire rated assemblies actually do make sense once you've decoded the systems and their applications. This table helps tremendously:
                  http://database.ul.com/cgi-bin/XYV/t...gbxuvhelp.html

                  NFPA-80A (http://www.nfpa.org/aboutthecodes/Ab...asp?DocNum=80A) is also noteworthy if we are talking about exterior protectives.

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