Door issues leveling 1 degree slope in room
I live in New Orleans and my house, like most here, as quite a slant. It is about a one degree consistent slope from side to side, with a little favor towards the front of house.
The house took its dip many years ago from settlement in a tight clay that is subject to significant fluctuations in shallow groundwater levels. It floats up and down about an inch either way depending on the season (e.g. precipitation). The house was built in 30s and is structurally very sound. It's a frame house with full brick veneer.
The house was renovated after Katrina and much of the tilt factor has been carpentered out. However, the third floor attack room and bathroom are in dire need of leveling. The room in need is approximately 18 ft x 12 feet in dimension. The connecting bathroom is 4 ft x 6 ft. The slope runs across the diagonal of the room towards the bathroom. The room has a total of four doors: entrance, side bedroom (already leveled), closet, and bathroom.
I plan to rip up the sub flooring and sister joists to make level. The one degree slope results in an elevation change of approximately 4 inches along the 20 foot diagonal, so its a major reconstruction.
So my questions are as follows:
1. With doors on three walls I anticipate major challenges with functionality after leveling. Will I need to rip out door jams and shim to make work? I am pretty sure I know the answer to this is yes, unless I was okay with massive gaps at the base of the doors. I would be interested in an easier solution.
2. If there is an easier way to level other than ripping up sub floor that would be good to hear. I have a problem with building up too high because the wall that needs to increase 4 inches is connected to the bathroom.
3. The bathroom also needs leveling but it's a tile floor and I thought I would use leveling compound. I've thought of using a large threshold between bedroom and bathroom, and then only increasing the elevation of the bathroom low side by less than an inch to avoid visual issues with shower threshold, which I really don't want to rip out and rebuild. In this case there would be a 4 inch elevation change between the bedroom and bathroom, which I am assuming is too much to fix with threshold...?