Not all stairs are part of an accessible means of egress and therefore not all stairs are required to have solid risers. The OP did not indicate if the exterior stairs are meeting the means of egress stair requirements and if they are the second or third exit from this second floor 1009.7.5.3 Solid risers. Risers shall be solid. Exceptions: 1., What is a guard and where are guards required? While handrails are there to help slow or prevent a fall on a stair or ramp, guards are to help prevent a fall over an open side of a walking surface. Guards are required along the open sides of means of egress paths where there is a vertical drop of at least 30 in. (760 mm)., The exterior egress stair requirements are in place to ensure the public health and safety for exterior stairs used as a means of egress from commercial, residential, and industrial buildings., MEANS OF EGRESS – DOORS/STAIRS/RAMPS Accessible Means of Egress Means of egress are required to be accessible per requirements of Section 1007 as well as Chapters 11A or 11B, as applicable. If more than one exit is required, both of them are required to be accessible., 1001.1 General. Buildings or portions thereof shall be provided with a means of egress system as required by this chapter. The provisions of this chapter shall control the design, construction and arrangement of means of egress components required to provide an approved means of egress from structures and portions thereof., Guards shall be provided for those portions of open-sided walking surfaces, including floors, stairs, ramps and landings that are located more than 30 inches (762 mm) measured vertically to the floor or grade below at any point within 36 inches (914 mm) horizontally to the edge of the open side. Insect screening shall not be considered as a guard..