Do I need a stairway for egress from a balcony that's off a second floor bedroom?
Spiral staircases are allowed if they meet the specs (780 CMR 5311.5.8.1), but as with any bedroom, you have to have a second means of egress in an emergency (Sec. 5310). This can be a window in the bedroom, provided it meets the requirements. I don't see any requirement that a window be under a certain height from the ground. I recommend calling the local building inspector to be sure--your county or city may have more stringent requirements than the state building code.