Yes2009 IRC
R101.2 Scope.
The provisions of the International Residential Code for One- and Two-family Dwellings shall apply to the construction, alteration , movement, enlargement, replacement, repair, equipment, use and occupancy, location, removal and demolition of detached one- and two-family dwellings and townhouses not more than three stories above grade plane in height with a separate means of egress and their accessory structures .
STRUCTURE. That which is built or constructed.
STAIRWAY. One or more flights of stairs, either interior or exterior, with the necessary landings and platforms connecting them to form a continuous and uninterrupted passage from one level to another within or attached to a building, porch or deck.
Well You can't use the IRC so I guess you have to use the IBC
2009 IBC
101.2 Scope.
The provisions of this code shall apply to the construction, alteration , movement, enlargement, replacement, repair, equipment, use and occupancy, location, maintenance, removal and demolition of every building or structure or any appurtenances connected or attached to such buildings or structures.
STRUCTURE. That which is built or constructed.
STAIRWAY. One or more flights of stairs , either exterior or interior, with the necessary landings and platforms connecting them, to form a continuous and uninterrupted passage from one level to another.
Just because something is constructed on residential property does not require you to use the IRC exclusivly. Exterior stairs are covered under the IBC