Hi Gary.
At the risk of starting an argument, I will toss in my opinion. Mind you that I am not in the construction business.
The material that is used for insulation does little to insulate in and of itself, but it is selected to have a very low coefficient of thermal conduction. Fiberglass excels in that arena as does foam. All of these products have the main job of trapping air and not allowing it move. The trapped air is the main insulator. Compressing fiberglass bats into the wall stud spaces reduces the amount of stagnant air trapped by the fiberglass, and thus reduces the overall quality of the insulation.
What I did in my garage addition was to staple the insulation to the 2" edge of the suds. This gives the insulation room to trap the air and gives more effective insulation of the wall. If you are not using 2x6 studs, you should be in order to get an R19, instead of a meager R11.
Regarding the vapor barrier, I haven't seen this done recently so I can't speak with any authority. When I built a home back in the 1976 time frame, in Ohio, the vapor barrier was just stapled to the edge of the studs. Today would guess it is glued to the studs. Either way, it performs the same task, that of keeping the transfer of moisture to a minimum. When we built 5 years ago, I used SIPs(R30)for walls, and vapor barriers were not required. Our drywall was just nailed to the SIPs.
So, what I would do is to secure the fiberglass bats to the inside 2" stud surface using staples being sure that the fiberglass is not compressed. I would go over the bats assuring that the staples are completely driven into the studs. Then I would follow up with the standard vapor barrier. I think just stapling the barrier to the studs over the insulation kraft paper would work. By the time you screw the drywall the vapor barrier will be firmly pressed against the studs and work just fine.
As I said above, I am not in the construction business. While I am most likely not up to date on current construction techniques, I will standby my trapped air theory of insulation.
So, Steve and Bart, where am I going wrong.
I won't argue with you, but I reserve the right to ask question.