San Francisco Fire Code § 1032.2 Maintenance of the Means of Egress

Fire escapes and related balconies, ladders, landings, and operating devices shall not be obstructed in any manner. No object shall be stored on or attached to a fire escape without the approval of the fire code official. Fire escapes shall not be located beyond a locked door or room that restricts immediate access to the fire escape from the corridor. Exception: These restrictions shall not apply to a building in which every dwelling or commercial space within the building has immediate access to a fire escape without exiting the dwelling or space and entering the corridor.