Looking at the door, the downward side of the slope is towards the middle of the house. The joists in the ceiling (at least in the basement) run perpendicular. So the direction of sag is left/right of center, and the room beyond the door is the back of the house and behind me taking the picture is the front of the house. The floor in the room beyond the door also slopes towards the middle because when I get up from my office chair the heavy side swivels towards the slope.
The weird thing is that the door itself seems to be level, but the frame is "raised" on the right side.
Would basement floor jacks help this issue? House is 100+ years old.
