Hello – I have an elevated sunroom, so the floor is exposed to the outside temperature. The builders barely put in any insulation in the joist bays and what was there was in rough shape, so I tore it all down and am starting from scratch. This past week I installed foam board (polystyrene) into the bays and made sure it was all air tight by using spray foam to fill in the gaps. 

For the remainder of the bay space, my plan was to us rockwool insulation to get the appropriate R-value. That has been proven very difficult to find in my area, so I’m thinking of using regular, unfaced fiberglass insulation before ultimately finishing the ceiling with plywood. 

I’m located in Atlanta GA and my concern is if I’m doing these layers in the correct order. I always get confused on where the vapor barrier (foam in this case) needs to be in relation to the insulation, etc. Any issues with the foam up against the flooring, then unfaced fiberglass, closed in by breathable plywood? 

Thanks in advance for any guidance/recommendations!