When the double chord style truss is used, is it the intent that the panel joints occur at truss centerline? Or perhaps they are intended to occur over the left or right chord?
The top image below is from catalogue
The bottom image below is from ESR-1774
Triangled:
The nailing of wooden shear panels, be they plywood, OSB, etc. is generally dependent upon the specific panel material, thickness, panel size, etc. And then, testing programs to set design shear values for various nail sizes, nailing patterns/spacings, long edges or all edges nailed and blocked, intermediate blocking and field nailing, etc. So, the nailing is really based on the sheathing materials. Based on your two pictures, they are pretty general in nature to show min. nailing, max. nail spacing at edges and some blocking schemes. Some truss manufacturers get all exercised when you nail into the edges of laminated chord members, either edge dist. and/or spacing can cause splitting of the chord member laminations. I would think it would be o.k. to have the sheathing panel edges at the center of the truss and then use the tabulated nailing criteria on each panel on each chord member. Although, we edge nail two panels to 2x joists every day.
Edit: Ask the truss supplier (manufacturer’s engineering dept.) these very same questions, and get some answers right from the horses mouth.
My $0.02, the truss supplier doesn't really give a shit exactly where that joint lines up. That's also why they specify maximum 24" o/c. That's for truss top chord bracing and has nothing to do with diaphragm nailing as the maximum spacing for that is 12" o/c. And as far as location of the joint, I'd bet from a construction perspective directly over the centre of the chord gap is preferable. That's where they're measuring the joist spacing and I assume they're at some 12", 16", 19.2", 24" or 32" spacing. therefore they're looking to use 8ft long panels.
1. I have reached out to manufacturer and not heard back as yet.
2. Concern #1 is how the shear is transferred from one diaphragm panel to the adjacent diaphragm panel across the "gap" between to two elements of the top chord. Are we to rely upon the truss topchord-to-web-to-topchord connection?
3. Concern #2 is, from Table 4.2 NDS wood diaphragms, would we consider the width of the framing member to be 3x? or 2x?
Thx
Red-built will design the truss to transfer the loading thru the top chord connection to web. Typically for lightly loaded members it will not be a issue and high-load diaphragm they will up the connection.
