Truss design name?

New construction
I have not seen this type of design before, looking to identify what it is called and more specifically what the horizontal 2 x 4’s are called that are installed between truss, 1 is damaged. Included is 2 pictures.

  1. from client during build with red circle
  2. from my inspection.
    Any concerns with this damaged 2x

Those are piggyback trusses installed over regular trusses.
They set on top of furred 2x4’s at 2’ o. c. The damaged one should be replaced if it impacts the bearing of the top truss and also provides lateral stability of all the trusses also.
Piggyback trusses are utilized when there is a height restriction on transporting over the highway.


Marcel has it correct…

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Thank you Marcel & Larry.


Yes… piggybacks… BCSI calls for there to be permanent top chord diagonal bracing for the base trusses… which there is none are visible in that photo.

See the docs here…
One pic from BCSI manual showing TCDB for top chord of base trusses which have piggyback trusses.

They don’t have typical structural attachments that we see in this area either. Those 2x4’s are permanent lateral bracing… the damaged 2x4 looks like significant damage… new construction, you need the TDD’s to provide your client with the best information.


That is correct Dave, and I am sure in your area, it would call for these also to tie the piggyback to the main truss.


Absolutely Marcel… fantastic graphic!

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They are called purlins.


Thank you Dave, good info.

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