We did not locate any requirement regarding identification and marking of rated walls in NFPA 101 (Life Safety Code) or NFPA 99 (Health Care Facilities Code).  Michigan has adopted the 2015 International Building Code, which states the following:

703.7 Marking and identification.

Where there is an accessible concealed floor, floor-ceiling or attic space, fire walls, fire barriers, fire partitions, smoke barriers and smoke partitions or any other wall required to have protected openings or penetrations shall be effectively and permanently identified with signs or stenciling in the concealed space.  Such identification shall:

  1. Be located within 15 feet (4572 mm) of the end of each wall and at intervals no exceeding 30 feet (9144 mm) measured horizontally along the wall or partition.
  2. Include lettering not less than 3 inches (76 mm) in height with a minimum 3/8-inch (9.5 mm) stroke in a contrasting color incorporating the suggested wording, “FIRE AND/OR SMOKE BARRIER-PROTECT ALL OPENINGS,” or other wording.

How these code requirements are applied may vary depending on who surveys the facility.  Ultimately, it is up to interpretation by the AHJ and their decision to enforce or not.