We are currently renting our house and considering purchasing it from the owner, but it is sagging, and in some rooms it is rather significant and noticeable, with the worst parts being approximately a 1" rise in a 24" run. It has apparently been this way for a while, as all the owner's trim work has strange angles cut to fit the shape of the house.
There is a thick beam in the basement, probably 6" by 6" or greater, that crosses the entire house and supports all the joists. A four foot section was removed to put in the new furnace. I'm not sure if this cut is the reason the house is sagging, but I'm wondering if this amount of sagging is something to worry about, if we should look into fixing it and how hard of a fix it is likely to be, or if it's strongly suggested that we find another place.