Insulation, Radiant and Vapor Barriers - Unfaced fiberglass at sill?

I am finishing my basement. The existing insulation above the sill plate ( the vertical board that rims the entire perimeter of the house and can be accessed via the basement between the floor joists) is unfaced fiberglass. This are will be enclosed by a ceiling and walls. Should this insulation have a vapor barrier? I am using rigid foam for the walls and fiberglass in the 'look out' part of the wall above grade which is faced by a metallic foil/paper. I live in northern Illinois.

Do I need to add a vapor barrier to the insulation above the sill?

Thanks

Yes you need to add a vapor barrier but first see if there is a vapor barrier on the other side of the insulation. Then all you have to do is turn the insulation around. If not tape plastic over the unfaced insulation.