Vapor barrier in garage ceiling – GreenBuildingAdvisor

We had a major leak in our shower due to a bad tiling job and had to demo the entire thing to check for water damage and mold.

Before closing everything back up I am wondering what we need in terms of a vapor barrier.

The bathroom is above a fully finished garage. The insulation when built was a couple inches of closed cell spray foam with rockwool batts beneath it to fill the cavity. We had to take out the spray foam to check for water damage. I remember the insulation company telling me the closed cell spray foam acted as a vapor barrier between the garage and the living space above.

Seeing as it is such a small space, I would prefer not to have the insulation company come back to spray foam it again. We did not have to open up the garage ceiling so the only access is through the shower floor.

I am concerned about not having a vapor barrier for this section before we close everything back up. What are my options aside from opening up the garage ceiling and having it spray foamed again? Could I put a vapor barrier underneath the subfloor before we close it back up, or would that potentially cause problems? I do plan to put the rockwool back in there.