This room is part of our current project.  Technically, we're working on the dining room but due to some previous water issues that have caused the ceiling to dip significantly for amost the entire length of the room, the room above needs to be investigated as well.  That's why we're working up here.  Don't be misled, we're really working on the dining room!
When the 1893 house was added, this room was divided into 3 sections.  One for the bathroom, one which provided some kind of service to the adjoining bedroom, and one long narrow room.
From our demolition up here we have discovered that part of this room was made into a bathroom when the 1893 addition was built as we have been able to confirm by the plaster and lath used in various areas.  This room was once 17' 3" x 17' 3" and was probably a bedroom for the original 1846 house. 
Bedroom 5
When the previous owner purchased the house, he removed the wall between the bathroom and the window to enlarge the room and make room for a shower unit.  The clawfoot tub that is now in the downstairs master bath was originally in this room. 
North wall
South wall
North wall
East wall
The long narrow room was converted into a laundry room and a door was added between the new laundry room and the newly expanded bath.  The hot water heater, washer, dryer, sink toilet and shower all lined up along the wall that had been added in 1893.  The weight of all that along with the water damage, seemed to be what was causing the bowing in the upstairs floor and the dining room ceiling. 
One time we asked the previous owner if he knew what caused the bow in the dining room ceiling and the dip in the bathroom floor.  His response was "What dip?"

Ok, so it was 20 years ago when this little issue was patched instead of fixed, so maybe he forgot, but it's pretty clear to see that at some point he was involved. 
We'll take a moment for some mindless comical observances.  It's always good to keep a sense of humor with these things. 

So, here we have what was behind the wall of the shower unit.  Have a look at that back corner on the right.  Major sinkage. 
The sinkage is caused by moisture coming into contact with the 1/4" chipboard that was the only thing keeping that corner from falling into a hole in the floor underneath.  Now add the weight of a full grown person to into the mix.  Question A. Is 1/4" chipboard substantial enough to possibly handle 200 lbs? 
Question B.  Is 1/4" chipboard an appropriate product to use in a potentially wet situation. 

I think the only reason someone hadn't already fallen through was because it was nailed, screwed, and stapled (all within inches of each other) to the surrounding walls. 
The next bizarre finding was under the carpet on the stairs leading into the room from the main hall. 

So, how many 2x4s does it take to emulate a step? 

Notice that the major reinforcement is up against the wall and nowhere near where the flow of traffic.  The tread itself is made from a 1x. so my question would obviously be "Is this really necessary???
So, we have heavy duty support on stairs where no one will ever step and something like cardboard holding up the shower.  Is anyone else having a problem with this?
What's holding up the drain?
Wallpapers found in the room all post 1893