I have seen other posts on this topic of whether to insulate or not and it seems the overwhelming answer is, insulate. My return duct is in the attic. So, can I wrap it with some left over unfaced-batting from my attic insulation job, or do I need to use special duct insulation? And does it need to be faced with a moisture barrier or unfaced, if so which side does the moisture barrier go on?

Thank you.