The stairs up from the ball room on the north room are wooden and rotting. They are stable in some places but going up the stairs is tricky business. A DC check against acrobatics or climbing of 20 for each step will keep any steps from breaking under a person or having the person note that the stair is too rotten to step on. Fall damage is normal, no additional damage for any falls. The highest spot, (the top of the stairs), is only 20 feet high.
Up above, the floor circling the ball room is in fairly good condition. If you feel obnoxious have the players roll a perception check ever thirty feet or so to see if the spot any weak spots, but don't over do it, since the second floor is in pretty good condition and supported by stone supports.
There are eight rooms up on the second floor, two on each side.
Tomorrow: Room 1