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Is structural sheathing required on the faces of gable-end trusses?

etting | Posted in Building Code Questions on
All of the walls on the house I’m building are covered by structural SmartSide panels that serve as both sheathing and siding, but (quite a while ago when I had a bit less acquired wisdom) I bought the non-structural SmartSide, which looks identical from the outside, to cover the triangles formed by the trusses at the gable ends, figuring that they don’t need bracing.  Buying the more expensive structural type would have saved me spending much of today searching for any requirement, including in the 2012 IRC, that I use a structural sheathing instead, and I’ve found none, except for one APA document that recommended it for better resistance of tornadoes, which never occur here in Arizona.   The gable triangles are small: 20′ wide with a 4:12 pitch, and because I ordered the trusses with 2′ wide access openings, there’s a lot more 2×4 than in a standard truss. If you know of a reference that addresses this question one way or the other, it would be greatly appreciated.  
If I do need structural sheathing, could I provide it by attaching OSB to the inside faces of the gable triangles and thereby still use the unreturnable SmartSide I already have for the outer faces?

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  1. Expert Member


    It's not something I've ever had occasion to look into, but I suspect the only requirement would come from the truss supplier. You might want to check the installation drawings they sent with your truss package.

  2. etting | | #2

    Thank you, Malcolm. I did check those drawings; they did not say.

    1. Expert Member
      MALCOLM TAYLOR | | #3

      Trussed roofs are considered engineered products and their stamp typically covers everything above the walls, so it's their domain, and their call. I have had structural engineers who were engaged for the whole building over-ride their specifications and call for more aggressive fasteners and hold-down hardware, but that's probably only something that occurs in high seismic areas like here.

  3. etting | | #4

    Thanks again, Malcolm. The truss drawings specified quite a few other requirements, so their silence on this one may indicate that the faces don't need structural sheathing. I'll see whether SmartSide has an answer, as theirs is one of the very few products where this question would even arise.

  4. Expert Member
    Michael Maines | | #5

    I can't think of a reason why structural sheathing would be required, but I've never seen it omitted on a job site, or spec'd gable trusses without sheathing. I would ask your truss supplier for a definitive answer. It may vary locally.

  5. Zdesign | | #6

    Gable trusses with Flat 2x4s vertical as a non structural gable will require bracing as specified on the truss designs as well as sheathing of a minimum 7/16" thickness or metal strapping. Sheathing does not need to be Structural 1 rated but does have a minimum thickness.

    1. Expert Member
      MALCOLM TAYLOR | | #7


      The gable trusses we get supplied all have the same chords as the regular trusses, but with the vertical spaced studs mounted in between. Must be a regional thing.

  6. etting | | #8

    Thank you all for your input. It reinforced my impression that the fiber-based SmartSide seems to be used primarily if not almost exclusively for sheds and such, so I decided to get the strand-based, structural type instead. I figured out a cut pattern that will use only three sheets, and their cost is worth not having to climb up there a second time--or, in the event of an extremely rare, truly high wind--having something fail. Even though this turns out to be a sensible conclusion, it wasn't inevitable. If people had responded that they use the fiber type for this all the time and that that use has documentation, I would have used what I have.

    1. Expert Member
      MALCOLM TAYLOR | | #9


      I don't know where you are on your build, but when we sheath a gable-truss we do it before we stand it - either on the ground if the crane operator isn't too impatient, or laid flat on the walls with a prop under the peak. I guess that might be harder if the sheathing is also the siding, as you want to overlap the cladding below.

  7. etting | | #10

    I'm long past that option, Malcolm, but I definitely see its appeal. I raised all of the trusses by myself, so I'm not sure whether the extra weight would have been difficult. I hadn't thought of sheathing them after getting them up to the tops of the walls, but not yet tilted up. Once I get the gable truss faces covered, the house will be all dried in.

    1. Expert Member
      MALCOLM TAYLOR | | #11

      'Once I get the gable truss faces covered, the house will be all dried in."

      Good stuff! Hope things are going well.

  8. etting | | #12

    Thank you, Malcolm. Other than incredibly slowly, it's going well. Your advice has been a big help.

    1. Expert Member
      MALCOLM TAYLOR | | #13

      Hope you post pics once it's done.

  9. etting | | #14

    By then I'll be able to upload it to your Holodeck.

    1. Expert Member
      MALCOLM TAYLOR | | #15

      No - the hard stuff is over.

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