What types of signage have no rules or requirements?

Signs that give the names for companies or office occupants and their titles have no requirements. Company logos are always exempt. There is another list of exempt signs, such as directories and signs in parking lots and structures, but it is wise to use as many of the ADA standards as possible since, although directories and signs for drivers certainly don’t require Braille or raised characters, other rules like those for contrast and highly readable fonts make sense for everybody.

—The ADA Sign Lady