We have veneer plaster ceilings through out our home. The 2nd floor bathroom sink ran over for about 10 minutes. The water ran into the first floor ceiling which is 2 x 6 construction. From there it ran along the blue board, which is the backside of the first floor ceiling. The water drained to the first floor along the seams of 6" x 6" barn beams in the ceiling. We were able to dry out the floors, which are tongue and groove oak, but are concerned about the water that may still be laying in the first floor ceiling on top of the blue board. I did put several small nail hoes in the diamond coat through the board, but there does not seem to be any water coming out.
Question: Should we replace the ceiling and do you think mold will form in the area between 1st floor ceiling and second floor flooring?