I have to do a one side 8ftx6” slab repair on 6 lower chords on my trusses. I can use 10dx3 nails or #8x3 screws. Do you think it would be better to use nail gun or screws?. I understand nails have better shear strength but not sure if that is an issue on this application. And if i use screws, do they have to be structural screws? I asked the engineer but he is an ass and will not answer more questions without paying him more. I have about 80 fasteners to install. Thanks Dean
With that many I would probably use nails in my gun. If you don’t have a gun but do have an impact driver I would use screws , this would be the last time I used that guy , yes there are structural screws I like fasten master torx head, these have a long smooth shank with the threads on the bottom 1/2 maybe slightly less on 3”.
The strength of 10d nails and #8 screws are similar. Nails have a slight advantage in shear and screws have an advantage in pulling the two members together. Here’s an article that explains it better:
I’d use a power driven 10d box nail because it tends not to split the wood as much as screws. Remember, you’ll be working very close to the ends of the chord members and that makes them susceptible to splitting...especially if you over tighten.
I’d practice with some “Dry” lumber trying not to split the wood. Use “Dry” lumber because the trusses have dried out. Be careful not to nail too close together in the same “grain vein.”
Btw, I’ll bet your engineer did not “stamp” the letter he gave you. If you want to have some fun (beings he’s such a jerk) tell him you’re going to turn him into the state engineering board because he didn’t stamp the letter. (Any professional advice used for construction needs a stamp.) Tell him you’re getting a Building Permit and the Building Official is upset. (Leave it on his answering machine after hours so he can’t respond. He’ll loose some sleep over that. Oh, and if he calls you back, don’t answer.)