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

2 Answers 2


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”.

  • Shoot them at a slight angle and the tip won’t be exposed.
    – Ed Beal
    Mar 21, 2020 at 23:09

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.)

  • Hey lee. Thanks. He did stamp the dwg because i paid for his service. He finally answered my questions. He said he would us nail gun if his home. But screws would be fine. Did not say they have to be structural screws because Its a very low load application. But said he cant tell me to use non structural screws but that in his 30 yrs no inspector has ever asked about the screws. I plan to use 10d box nails with nail gun, 1 1/2 edge margin, spaced 6 in on center with two stagger rows. Per engineer dwg. Should be a piece of cake
    – Dean
    Mar 7, 2020 at 0:46
  • I am using a nail gun with 10d 3" nails. When I drive nail in test boards with head flush I get a 1/16" of nail poking though the back of board. This is normal or should I do something different?
    – Dean
    Mar 20, 2020 at 18:56
  • Yes, it’s normal to have the nail extend through both boards. Remember, splitting will cancel all holding strength. Don’t get too close to the ends of any board and don’t put two nails in the same “grain vein”.
    – Lee Sam
    Mar 20, 2020 at 22:17

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