timber trusses - retrofitting pre-fabbed metal plate trusses with plywood gussets

[cmbyrd77]

Looking for some experienced knowledge. Is there any literature, seminars, classes, or unwritten rules of thumb on how many nails to use in a plywood gusset that would compare to the amount of "spikes" or contact area of an original metal plate connected pre-fab truss?

Any help would be greatly appreciated. Thank you!

 

[EngineeringEric]

it needs to be calculated. You can find the forces with statics as pin-pin connections and then figure out the value per nail in strong/weak direction of plywood (critical alignment issues here) and also determine if double-shear or single. Double shear will require plywood on both sides (recommended) and then crimping the tips of nails (use nails 1" longer than total thickness of system and bend edges over).

There are some good sources of info online. Repair of Wood Trusses by Steven Fox for starters... But it is simpiler than you think as long as you pay attention to alignment and fastening details.

For a quick rough estimate, assume 80-100 pounds per nail if you want and this can be used to compare values to number of spikes per a ICC-Report... But i have never really done that since it would not add value to any of my past projects.