Will faced insulation behind poly sheeting trap moisture?
We don't use plastic sheeting for vapor barrier (on warm side of wall) anymore. We've learned that moisture (vapor) will get past the plastic sheeting (I.e.: around outlets, switches, vents, etc.) and then not be able to "move" back out of the wall. Then, that creates rot. 

Also, the paper vapor barrier needs to be moved to the warm side of the wall.