I also use 3M Cold Weather aluminum tape to seal the insulation to the frame sticks to create the final total vapor barrier seal.
Not cheap though at $15 a roll!
I spent almost as much on foil tape as I did on the insulation. Of course, I pulled some out and retaped for various reasons (like adding wiring after I thought I was finished wiring). Sadly, I've grown quite accustomed to the smell of voil tape.