Sagging floor issues often relates to framing issues or the loads that the floors are carrying.
How to fix sloping floors on second floor.
Common reasons for sloping or sagging second story floors.
Depending upon the conditions it is possible to strengthen or repair existing framing members such as floor joists or roof rafters by adding reinforcing material sandwiching the member on either side with plywood is sometimes worthwhile but the plywood must be installed correctly for greatest strength.
Load bearing wall removed or altered on first floor.
Except for that slope the floor itself might be flat.
If a load bearing wall is removed on the first floor then the second story floor joist or trusses may drop down in the area where the load bearing wall was removed.
Before embarking on the floor leveling project here take a simpler approach first.
For rooms that have a general slope the issue may be foundation problems that require the assistance of a foundation repair company or a general contractor.
Foundation issues deteriorating wood supports especially sills which rest on the foundation footer improperly installed joists or sub floors and other issues can all cause a floor to slope or sag.
Sloping floors verses sagging floors these terms are related and a sagging floor actually has a slope from each side of the sag.
Thus by repairing your out of level floor you may find the windows and doors in your home are a whole lot easier to use and last longer.
The cause of these may be the same or may be different.
There are several problems that can cause a sagging or sloping floor which is one of the reasons why fixing a sloping floor is difficult.