I’ve been trying to beef up my attic insulation. I have a kneewall with faced fiberglass batts between the 2×4 studs. I’ve already air sealed all the gaps and holes around the studs. 

(See photo of open kneewall on left; polystyrene foam board on deck at right)

I wanted to add some R10 Polystyrene rigid foam over the top of the batts/studs, then seal around the edges with foam or caulk.

Question: will I be creating two vapor barriers with the faces batts AND the polystryrene? Can I proceed as planned? Or do I need to removed the faced batts and replace with UNfaced?

Thanks for your help.

Dennis