To fix the master bathroom I removed the tub, then removed the floor. That left a large hole going down into the 5th dimension somewhere...
Next was to put in some solid insulation to keep the neighborhood cats and other varmits out Then the studs needed to be 'sistered' so the new floor could be fastened down all the way around. The seam between the 4 by 8 sheet of plywood and the additional one foot needed would have been in mid air, so I covered that stud with a strip of plywood that would be used to bind the two sheets of plywood together in the next layer.
The next problem was that the new floor was not level enough so I used a bag of floor leveler to make the area under the tub completely level. Then the tub could not be put into place without knocking a hole in the wall because the room is exactly 5 feet wide. Then there was the next puzzle to solve. The drain from the old tub was above the floor but the new one is below the floor. The drain also doubled as a sewage vent so the plumbing got very trick at this point. I kept putting all of the pieces together untill I had it right then glued it all in.
The final problem is still not fixed...the hot and cold are backwards! I went by the length of the pipes and never checked it until it was all done.
Here is what the bathroom looked like before the tub and the floor were replaced;
Here is what it looks like after being renovated;