We've seen plenty of pictures of the front
of the stairway, here is one of the back. You can see that I end nailed
the landing joist and there is a structural beam (4 x 8) that's holding
up the lower landing.
It wouldn't have been a bad idea to lay out the 2 x4 wall studs, in the
wall correctly. Obviously, he needed to notch one of the 2 x 4 studs
around the 4 x 8, but it should have been moved.
Split Level Stair Framing