As I continue to gut this house, I've formed an opinion on a hotly debated topic: When do you install cabinets and tubs?
In my house, both were installed directly on the subfloor; the finished floor went only to the edges of these 'built-ins.' I believe this is the wrong way to do things.
In both cases, this complicated the demolition, as things had to be lifted over the underlayment and finished floor to be removed. That's a lot harder than simply sliding things out. When the item is a 500# cast iron tub with nothing to grab ahold of, that's a real problem.
The break in the finished floor also, in both cases, directed water to the subfloor. This allowed leaks to be undetected, and the floor to rot through. The same had happened at the toilet - where the leak proved to be at the bowl/tank juncture, rather than at the base of the bowl.
A similar issue arose around the tub flange. The opening had been framed to accept the tub; both the wall sheathing and tile were placed over the flange. This resulted in a tub you could not remove - or a replacement you could not install- without first demolishing a large section of wall.
I'm going out on a limb here and say that the design of the typical tub is seriously flawed for this reason. They're simply not intended to ever be replaced.
Related to the water damage issue is: how do you make the walls? I found quite a bit of evidence the drywall had been soaked several times behind the cabinets and toilet. Drywall concealed by the upper cabinets also had quite a bit of surface mold. Oddly enough, the walls around the tub / shower were in good shape, except for the area around the faucet.
The wall behind the toilet was water damaged, yet was protected by tile. So far, it looks like the tile guy knew his trade; it's not clear to me where the water came from.
The wall behind the lavatory was water damaged, despite the tile job. The worst of the damage was at baseboard level.
So ... what will I do?
Well, I'm persuaded to finish the floors before I instal any cabinets or appliances. I might even notch the bottom edges of the cabinets, or make other provisions to let any water that might get in there drain. Maybe even slightly raise the cabinets by setting them atop a sheet of Formica placed over the finished floor.
(As a side note, the sheet of Formica used as a backsplash in the kitchen worked exceptionally well fo 56 years- though some fool painted it!)
It might be a good detail to face the wall behind the cabinets with FRP, and to replace drywall with Durock in the areas where plumbing penetrates.
Say what you will about expanding foam insulation .... but it won't hold water the way rockwool does.
I'm forming a bias in favor of a wall-mounted toilet - or, at least, a tankless one (to eliminate one source of leaks).
Likewise, there's something to be said for the old claw-foot tub, with a small 'free' space all around it. I've already decided to separate the tub from the shower.
Still, bathrooms and kitchens both get water on the floor. Maybe - just maybe - we ought to install floor drains as a matter of course; give the water a place to go! I'm also in favor of continuing the flooring up the walls, at least 4". Make it 'self molding,' so to speak., with nice radiuses to keep dirt and water from being drawn to the corners.