"Bob Simon" wrote in message
...
I've opened up the RFP at the back of my shower and removed five 4x6
baseboard tiles that were loose. I put a dehumidifier in the bathroom
and closed the door. Can I reasonably expect that most of the
moisture will have been removed in 24 hours?

No... give it several days, especially if there is no air movement in the
room to draw the dampness out.

Would it be a good idea to spray some Clorox or something similar
wherever I can reach before closing everything up to prevent mildew?

As long as you give the wall a week or so to dry out afterwards.