Shower Floor Leaking

have free standing shower next to an upstairs bedroom. It is located above a dining room that we seldom use anymore, and I had to go in there for something and man what a mess. The water has dripped from under the shower floor onto the ceiling below it, eaten its way thru that, and dripped on the the dining room floor enough to raise the hardwood strips and buckle them to the point where they have raised up enough to trip me. I have never repaired a grouted shower base before, but I am thinking that this is much more than that. Does someone have a set of design parameters for what has to go in there, assuming that the tiles have to be sawed along the edges and removed and then put back. I have seen the rubber pad that is supposed to go under the floor (installed on UTube videos) but something has to go under that , and then something must have to go over the rubber pad to re attach the tiles I suppose. I have the tools to do almost anything in a house except HVAC stuff but no experience with shower or tub installation. I need a shopping list for the home center to get this fixed fast! I can handle the replacement ceiling stuff, and will deal with the flooring when the leak is stopped.

Shower Floor Leaking