We used to get away with not fastening. Then the AHJ starting using the NEC by the book. Hey, if I have to strap more in exchange for an inspector that submits to the code just like we do, I'll take it any day. No more "his way because he likes it that way".

But for (what used to be before steel prices $.22 each) just smack a couple of these http://www.erico.com/products/CADDYcfcCS812ScrwOnConSuppt.asp on there and your good to go.