The house buit 1900 has severe dips in the floor on the second level, downstairs in remodeled(unsure how) Straight downstairs and up to 2" dips in the floor upstairs, even in places where there are no load bearing walls below. What is the best strategy to fix the floor, can't even shut the doors they hang-up on the floors. **the upstairs floors are hard wood and the hardwood is even dipped. The downstairs is drywalled and seems to be pretty even.

It could be several things, the year it was built is probably the most obvious, the upstairs floor joists are probably undersized for the span. Do you notice any dips in the downstairs ceiling, and do you know if it has been dropped in an earlier remodel. There is really no easy fix as you would have to open up the floor on the second floor or the ceiling on the first floor to look at the structure. I would call a local contractor and have them come out and take a visual look. I'm guessing with the age of the house, it might not have been originally built for second floor living space? Good luck