This is the 2nd floor of a 3 story townhouse. The main part of the room is about 30' x 13'. There is a point that is about 5' from the middle of the room, lengthwise, where the floor slopes up about 3/8" over 4' and then very gradually slopes down the other side of the high point. This high point runs just about the entire 13' width of the room. Is it possible that this is due to one joist that is slightly higher than the rest? Would it be possible for someone to gently pull up the tile around the high point, get underneath, trim the joist, and then re-apply the tile? Could that potentially be a difficult and expensive fix? Would that all be worth it for 3/8"?