Roof Diaphragm

[SperlingPE]

See table 2306.3.1 in IBC 2006.
The column talking about required minimum nominal width of framing members; would a 2-ply truss be sufficient for the 3" requirement?

I am trying to find some commentary or insight on this. My initial thought is no.

 

[msquared48]

If yourare talking about a 2 BY truss meening 1.5" framing members, no, that will not suffice for a 3" nominal requirement, as that means members of a 2.5" minimum dimension.

Mike McCann
MMC Engineering

 

[JAE]

Right - you must use 2.5" wide single member (3" nominal) to suffice. Two - 2x wood members aren't acceptable.

 

[DaveAtkins]

I think it would be OK if the two plies were adequately nailed together to transfer the diaphragm shear. The load path would be sheathing to truss chord to truss chord to sheathing.

DaveAtkins

 

[bylar]

There was some data regarding "Stitch" nailing of two 2x members to act as a 3x member.

 

[msquared48]

Yhere us no mention of two- 2X members by SPE, only if a 2X will suffice as a 3X for the diaphragm nailing as I understand it.

Mike McCann
MMC Engineering

 

[SperlingPE]

By 2-ply truss, I meant (2)-2x trusses nailed together.
Thanks for the input.
At this time, I am pursuing a more conventional (for my area) roof framing design.

 

[msquared48]

Got it...

Mike McCann
MMC Engineering