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Rafter thrust control for flush beam

Discussion in 'Residential Structural Codes' started by jar546, Oct 5, 2013.

  1. MASSDRIVER

    MASSDRIVER Registered User

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    [​IMG]
     
  2. RJJ

    RJJ Platinum Member

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    I would go for the ties!
     
  3. jar546

    jar546 *****istrator

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    Using nails, an LSTA18 works best unless the holes line up with the LSTA12 since it has to span the beam width and joist hangar bottoms. Anything from the LSTA12 on up works with nails. With simpson screws the numbers are even better
     
  4. 4thorns

    4thorns Bronze Member

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    Who is responsible for determining this information and the required connection? Is this something you would determine and inform the builder?
     
  5. jar546

    jar546 *****istrator

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    It is the builder's responsibility to provide this information and our job to check it. We are not designers.
     
  6. fatboy

    fatboy Administrator

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    "It is the builder's responsibility to provide this information and our job to check it. We are not designers."

    Agree.........
     
  7. 4thorns

    4thorns Bronze Member

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    OK. Let's say that the builder has provided you with all the info and has chosen a strap that he feels is adequate.

    Would you be willing to explain to me how you would prescriptively determine whether or

    not his fix is acceptable?
     
  8. jar546

    jar546 *****istrator

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    By the manufacturer's rating of the strap and the information that he provides. There are plenty of easy calculations that can be performed to verify this. In addition, through conversations with structural engineers in the past, we have an idea what works in our area(snow load may vary) based on the size of the roof and the direct comparison to the nailing requirement VS the specifications of the strap from the manufacturer.

    We can always tell them to go to a PE and get the non-prescriptive fix specified. Please don't forget that not everything is in the IRC and we are sent to the IBC and NDS which has much of this information prescriptively.
     
  9. ICE

    ICE Moderator

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    It is called flying by the seat of your pants.
     
  10. mark handler

    mark handler Sawhorse

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    You could offer guidance, everyone needs to learn.
     
  11. DRP

    DRP Gold Member

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    Simply provide equivalent to table R802.5.1(9) footnote e.
     
  12. jar546

    jar546 *****istrator

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    Yes, absolutely. It is much simpler than I am explaining it and that table is the entire key to prescriptive compliance.
     
  13. RJJ

    RJJ Platinum Member

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    Yes it is simple and 802.5.1(9) footnote e. is spot on.
     
  14. RJJ

    RJJ Platinum Member

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    Was this beam on the original plan? I believe you stated a wall was removed thus the need for the beam CJ connection?
     
  15. jar546

    jar546 *****istrator

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    Beam was not expected to be there. It was a post fire renovation that they decided to change the layout for and a surprise to us.
     
  16. RJJ

    RJJ Platinum Member

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    surprises happen all the time.
     
  17. steveray

    steveray Sawhorse

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    couldn't they use something like a simpson VB brace over the top? I have not seen it done or looked much into it, but have seen it in the catalog and seemed reasonable.......
     
  18. Rio

    Rio Silver Member

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    That was my thought............

    VB Knee Braces
     
  19. Rio

    Rio Silver Member

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    I just read the catalog page again and the VB brace requires the members being connected to be a minimum of 2-1/2" so that's out if those are 2x joists; strapping on the bottom and blocking to pick up where the gyp. bd. can't be nailed as suggested above would be quick, good, and easy.
     
  20. mtlogcabin

    mtlogcabin Registered User

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    [​IMG]

    Would make the drywall guy happy. Probably only needed every 2nd or 3rd rafter
     

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