Guidance on using Plywood Gussets Rather than Metal Truss Plates

[Ron247]

I am field repairing some wood roof trusses and using 3/4" plywood gussets rather than metal truss plates. I have the following questions about using plywood gussets and nails. In my case I am using 6d common nails and the wood trusses are all 2x4 components. There is a plywood gusset on each side of the truss joint. The sketch gives some idea of what I am asking. The detail is a generic one with 6d nails and I have way more fasteners in the sketch than needed. I have a highly populated generic detail and omit fasteners as needed.

Question 1: Since the 6d nail penetrates almost the entire thickness of the 2x4, should I double the distance between rows and distance between fasteners in a row value. Since there is a 6d nail coming from both directions, I typically do space them farther apart but have never been told to. Cleat type truss plates do not penetrate beyond the center of the thickness but using nails does tend to.

Question 2: What criteria do you use to decide on thickness of plywood to use for a gusset. I have used everything from 3/8” to 3/4" but do not have a firm rational about how I decide.

Question 3: Do you know of any “load rated” nail on metal plates? I see plates you can buy but have never seen a load rating for them.

Question 4: Do you think OSB is better or worse than plywood for gussets?

Question 5: NDS does not show values for 4d nails and does not show side plates thinner than 3/4", anyone know why I should not use thinner plywood and 4d nails as long as it calcs out?

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1562190194/tips/Eng-Tip_Gusset_krzkhv.pdf[/url]

 

[HouseBoy]

In no particular order:
I generally use 1/2" plywood and try to proportion the gusset so that nails will be no closer than 3" apart (but I have gone down to 2").
APA considers OSB and "plywood" to be the same (assuming they are "Rated Sheathing"). My thinking is that the main difference has to do with how they perform with regard to getting wet so... might not be a concern for this case.
I think APA has a reference for the lateral load values of nails in plywood.
I determine the force in the members and place sufficient nails to transfer that force (although admittedly, I mainly consider axial forces).
I prefer the nails to penetrate both pieces of plywood so I get double shear values. Nails can be clinched (if they extend out of the opposite side). I specify nails from opposing faces to be offset from each other.

 

[XR250]

I agree with Houseboy. Use 8d as they are the best length and are common for nail guns. I also specify poly subfloor adhesive for some belts and suspenders.
I generally wing it on the length of gusset - usually 16" long so it uses a sheet of plywood efficiently. If the gusset is really tall, then I sometimes go wider.

 

[BAretired]

Why not use 3" nails in order to get double shear? Maybe 3.5" to allow for clinching.

BA

 

[Ron247]

House: When you have opposing nails offset, what offset distance do you specify? Is it the same as the distance between rows or greater?

In the particular project I am on, I do not have excessive loads to deal with. This thread is more of a general inquiry. Seems like most responses so far attempt to use double shear where I have always tried to avoid that for no particular reason other than the fact most metal truss plates are single shear.

 

[MotorCity]

For questions 2 and 4, your loads will dictate you what type and thickness of plywood to use based on its capacity.