I had a big sag in my bathroom floor that was caused by the former one ton mud showerstall that had been there.

It was dramatic.

I leveled the floor in the bathroom as close as I could to the edge (still not 100%) with self leveling cement.

It worked out perfectly. Or as perfectly as I could have hoped for. It is not visually noticeable, the pencil that runs just above the vanity is miraculously level, and level with the vanity top, which means that somehow the floor ended up level!!

I am not doing the work, and the tub and a row or two of floor tile is in place.(On the opposite wall of the tub, not next to the tub). I am wondering if they will have to remove the tub, compensate for it somehow and then reinstall it.

I have one bathroom so they laid some tile in order to leave us without a toilet for the fewest days possible.

It does look like that only not so exaggerated, and it is still in the cement backer board phase.

The floor is an inch out of level across 5 feet and that's before it goes really down hill outside the bathroom, so leveling it in the bathroom would create a significant "step" up into the bathroom. (The wall is also about 4" out of square across 11 feet).

I am mostly concerned that the bathtub have adequate support under it too.

My situation will be closer together than you've shown Bill, but we are headed toward a gap, and vinyl base isn't going to cut it. I was thinking of using Daltile's quarter round ceramic tile between the floor and tub as one solution.

My contractor has actually been good so far, and has done other bathrooms in this (problematic)complex, and has done a good job. One difference has been that most people have used rather thick large format tile which may cover some discrepancies better (although I know the floor has to be "flatter" for these to avoid cracks), another is the location of the bathrooms within those houses and their relative "level"ness.

any thought to correcting the sag for the house?
almost an inch over 5 feet is a lot.

That's what we're doing in my house-- jacking up the center.

This house is a 10,000+ sq ft 170 year old house that is a multi unit apartment building. The first two floors are chock full of ornamental plaster and such that would be compromised trying to level things out. Some of the sags were corrected slightly 40 years ago, but there were lots of things that were done that go around the sags (drywall cut to fit bowed ceilings etc.) that clearly havent moved since. The floor in that particular part of the house, part of which is a 25 foot span is visibly and sensorily (if thats a real word) unlevel. Its several inches of sag and it really can't be corrected.

The GC came this morning and agrees that the tub cannot stay the way it is, but we had already discussed that we can't completely level the room either.

If you can't raise the one side because it would create a step, you could lower the other side by pulling the subfloor and planing down the tops of the joists.
I had the exact same problem you did, only it was only 3/8"; I fixed it be carefully shimming the subfloor up like a ramp within a 1' area adjacent to the tub. I was aware that the floor sagged, and I test fit everything before screwing down the plywood.
In your case, I would make a level plinth under the tub, and run the isolation membrane under the tub as well, so that any corner cracks would still be waterproof. By adding in trim tiles along the base of the tub, it's like asking for a leak.

Casey

As far as the step up into the room, we had a Hollywood stone threshold that "ramped" the height difference when all was said and done. (the bevel is broad)

Haven't stubbed toe once, and that is something I am prone to do; it is about 1 1/4" height change, no problem.