The DOJ’s revised regulations, called, "2010 ADA Standards for Accessible Design", for the Americans with Disabilities Act of 1990 (ADA) were published on September 15, 2010, with the revisions applicable to signage. (Section 703)
In general, you are required to have an ADA sign with tactile copy and Grade 2 Braille if you are to identify a permanent room or space. Sounds simple enough? Well, just for a permanent room identification sign alone must be compliant of the following criteria:
Raised characters: 1/32 inch (0.8mm) minimum above background; uppercase; sans serif; the width of the uppercase letter “O” is 55 percent minimum and 110 percent maximum of the height of the uppercase letter “I”; 5/8 inch (16 mm) minimum and 2 inches (51 mm) maximum based on the height of the uppercase letter “I”; stroke thickness of the uppercase letter “I” shall be 15 percent maximum of the height of the character; spacing between individual raised characters shall be 1/8 inch (3.2 mm) minimum and 4 times the raised character stroke width maximum, and shall be separated from raised borders and decorative elements 3/8 inch (9.5 mm) minimum; spacing between the baselines of separate lines of raised characters within a message shall be 135 percent minimum and 170 percent maximum of the raised character height.
And these specifics are followed by the Standards for the Braille, Installation Height and Location, Finish and Contrast, Pictogram, Symbols of Accessibility.
ADA Signage: With Stringent Guidelines