Can I use a 6 mil plastic sheet for a vapor barrier in my garage?

My house is 50 years old and is lacking in insulation in the garage ceiling. Above the garage are bedrooms. Currently there is 3'; of fiberglass with an aluminum vapor barrier within a 2x10 joist. I'd like to put R-30 fiberglass in the cavities but the 25' rolls of insulation are unfaced and the faced R-30 rolls are only in 48'; batts. 4' sections are easier to put up but that is not a concern of mine.Can I use a 6 mil plastic sheet for a vapor barrier in my garage?
Don't use a plastic sheet, use 15# asphalt impregnated felt or a fabric like Tyvek. The vapor barrier must be able to breathe or you run the risk of trapping dampness which will lead to mold.Can I use a 6 mil plastic sheet for a vapor barrier in my garage?
Yea you can do that .Get a good stapler to ad hear the plastic to the wood. No stapler , Use Tacks. or even nails..