S.C. Code Ann. § 5-25-900: Firestopping construction on floor levels.

At each floor level, in all buildings erected after February 20 1917 all stud walls, partitions, furrings and spaces between joists, where they rest on division walls or partitions, shall be firestopped with incombustible material in a manner to cut off completely communication by fire through concealed spaces. Such firestopping shall extend the full depth of the joists and at least four inches above each floor level. Stair carriages shall be firestopped at least once in the middle portion of each run.