Vapor barrier for elevated room?

[FITO]

I have a 14x14 sunroom that is about 4' off the ground. It's completely sealed and on the houses HVAC and has a tile floor.
I recently re-piered and lifted/leveled it 4"and in doing so had to remove some of the OSB underlayment and blown in insulation. It had no vapor barrier and for some reason 4 joist bays were left empty.
I am going to remove all of the OSB and drop all of the blown in insulation out and replace with kraft-faced batts. My question is do I need to put a vapor barrier between the OSB and the batts?

Included is a pic of the underside before the OSB removal.
Thanks for looking.

 

[jameswilson]

Vapor barriers, if applied correctly over the batts, can prevent moisture buildup. They are a great moisture barrier especially if you live in places where it’s mostly humid. I plan to get a new sunroom and install vapor barriers because I know moisture gets trapped very easily and they’re a good way to take care of the heating and cooling bills! I might just go with Champion Windows for the sunroom, just visited championwindows.com and called their guys over for an estimate. Let’s see how it goes!

 

[Tim The Tool Man]

With spray foam you do not need a vapor barrier as it is a vapor barrier. If you re do the job put the vapor barrier against your floor NOT the OSB. Vapor barrier goes toward the conditioned/heated living space always. You will have real moisture issues otherwise.

I know it might be expensive but I would look into the cost of having more foam sprayed on top of your existing foam + those empty bays.

Otherwise I would just stuff as thick a layer of Kraft faced insulation as I could into the cavities and put the OSB back up. (Kraft paper side up towards the floor!)