Quote Originally Posted by jkirk View Post
if your using gun nails youll notice that gun spikes have teh same diameter as screws.. my engineer doesnt really care which we use as long as we draw the new joist tight to the old with hand spikes first. one top and bottom every 2'
Diameter isn't the issue; it all comes down to shear strength. A nail will bend, a screw will snap; it has continuous stress risers built in. That's why it takes 1/4" screws (like timberlocks, etc.) to equal the shear strength of 16d nails.

Casey