Please consult the Americans Disabilities Act (ADA) Signage guidelines
Americans Disabilities Act (ADA) gives a set of guidelines that are intended to make facilities more accessible to the blind and visually impaired. These guidelines cover places of "public accommodations" and "commercial facilities". These are rooms or offices that are accessible to the public. A number of the key aspects of these rules are as follows:
Permanent space signs in areas of Public Access require both tactile lettering and Grade 2 Braille. In practical terms, Room Numbers and Room Name signs are covered under this guideline.
Permanent room signs must be mounted 60" from the floor to the center of the sign on the wall next to the latch side of the door.
Directory signs, signs that tell you how to get around the building, or signs that give you information about permanent features of the building do not require Braille. These signs, however, must still comply with height, finish and contrast rules for lettering and background. These informational signs are not required to have raised letters or Braille.
Not every sign is covered. As we all know, a typical school, hospital, factory, etc, has a maze of signs. Marketing or trade name signs are not covered. In practical terms, safety, industrial marking and notices are not made using tactile letters. General and informational signs are not required to have raised letters or Braille. The primary use, in practice, for tactile signs are found in offices and for permanent room installations.