Wood Truss Gable End Bracing (piggy back condition)

[bsh117]

I have a project where the roof trusses need to be constructed with piggy backs due to their height. The roof is also configured so that this piggy back condition occurs at the gable end of the building. Typically, I show the standard MiTek gable end bracing details. However, because the overall height of the truss (17' from bearing to peak) and the truss is in two pieces, I'm unsure as to how to brace the gable end. If I use the standard bracing detail, the diagonal brace could be up to 22' long.

Any assistance or input would be greatly appreciated. Oh, the project is located in central Florida.

Thank you!

 

[ToadJones]

I have a way of framing gable ends that you may not like because of labor costs, but it is simply the best way I have found to do it; on paper and in the field in my carpenter days.
When I was building houses for a living, I quit using gable trusses because they were too flimsy in the out of plane direction, leading to wavy walls and wavy sheathing and siding.
So, rather than use a gable truss, I simply ordered a regular truss and set that truss just inside the gable wall (for a 4" wall I set the truss from 4" -5.5" as in a nailer location).
Then I either balloon framed the gable wall all the way up past the truss or simply framed the gable in as a regular 2x4 wall on top of the regular end wall.

 

[vandede427]

I use diagonal bracing sometimes.

Other times I will provide blocking between the bottom chord of the gable truss and the first interior truss, then deck that top surface. This acts like a beam to the perpindicular walls. It's kind of like a ceiling diaphragm b/c it's at that elevation, but it's with actual sheathing.

 

[bsh117]

ToadJones ,

I understand what you are saying. In my case, the bearing wall is a masonry wall around the perimeter of the building. If it were my choice, I would be framing the gable end by extending the gable masonry wall up to the roof diaphragm. However, the contractor (who has the ear of the Owner), would rather use a wood gable end truss.

 

[bsh117]

vandede427,

Thanks. I did think about using this condition. However, it would be required at the piggyback bearing condition as well. At that elevation, this additional sheathing would create some bearing issues with the truss manufacturer.

 

[ToadJones]

same thing could be done for masonry walls. I am assuming you have a wood sill plate atop the masonry wall.

 

[Catacus]

Be sure to make sure that the top chord of the main truss is adequately braced too. With a higher roof load it can be a more likely failure mode, with the top chord buckling into an S shape.

 

[vandede427]

then stick build a horizontal truss at the piggyback elevation. it's not only need for wind bracing but for permanent bracing anyway.