truss clips for non-load bearing walls.

[Rich Zimmerman]

Do truss clips (simpson STC/DTC) make any sense with low-pitch roofs framed with I-Joists? Typically I've seen them with actual roof trusses, where unexpected point support under certain chords could be detrimental to the overall structure. But I'm trying to understand what the reasoning for truss clipping interior partition walls rather than direct fastening when the roof isn't a truss, but rather a conventional I-Joist system.

 

[jayrod12]

Because you don't want load going where it wasn't designed to go.

If you tightly frame your walls to the i-joists, the load from the i-joist will go through that wall to whatever supports the wall. Is the floor below that wall designed for the load? Unlikely.

 

[XR250]

What Jayrod says is true, however, in my 25 or more years of field experience I have yet to see this as an issue as long as the roof is designed with reasonable deflection limits.
The truss clips are also there to compensate for truss uplift due to moisture and temperature differentials between the top and bottom chords. I have seen this occur on a number of occasions but not enough for me to include them in my designs. None of my competitors seem to think it is an issue either.

 

[jayrod12]

I'll agree that most people don't specify them on single family residences. Except for basement walls that are supported on a slab-on-grade.

This omission of them on upper level walls to me has is due to what XR alluded to, reasonable deflection tolerances allow the high level i-joists to span on their own, to their intended bearing locations, after the low level joists begin to deflect. Essentially you will get a certain amount of load share between the high and low level joists.

 

[Rich Zimmerman]

Thanks. I see that. The floor is I-Joists and was certainly not designed for any additional roof load. I'm just concerned that the interior walls will be less structurally rigid if not directly attached and I'll have problems when I go to cantilever things like kitchen cabinets off of them. I'm also concerned about the drywall constantly cracking at the ceiling/wall joint every time a gust of wind comes by or someone walks on the roof. This is a 1000 sf single family residence and it seemed a bit of overkill...