Good afternoon all,
So approximately 15 years ago I finished the attic of my 1895 home to create a master bedroom and sitting room. At the time it seemed there was questions going back and forth if open cell or closed cell was the best option. I chose open cell for 2 reasons.

1. Cost. Considerably less expensive and I was on a very tight budget.
2. Open-cell allows for the passage of water. My thoughts are that if a leak develops in the roof, I will now because the insulation will let the water through. Closed cell will not allow anything to pass, so I may not know for a long time. It is hard to see a leak from the outside. Especially when the roof is so high

The attic rafters 2×6’s, so I had them sprayed full (non-vented) and finished the underside with 5/8″ gypsum board. I still have some unfinished areas that has exposed insulation. I tried to paint these with a fire retardant paint which seemed questionable. The insulation does not paint well.
I also had a new asphalt roof installed and have the attic on a dedicated HVAC system
2 Questions
1.  At the time, the installer said that would work fine, and it has from a heating/cooling perspective. My worry is that the new accepted practice has told me I might get moisture problems within the roof cavity. Is there anything to be done, or do I have to wait and see….

2.  The unfinished area I want to finish as a bathroom. Since the insulation is exposed, can I add a layer of poly-iso to the underside of the rafters to avoid moisture problems?

Ughh….. I’m ready to jump out the window of my very nice third floor bedroom!