The ADA requires that Braille tactile signs be included in all new buildings, but every Exit does not
require Braille signs. In some states, religious institutions and private clubs are not regulated by accessibility standards. Federal guidelines do not impose any restrictions on these private organizations.
However, more and more signs are now ordered with Braille, and varies slightly state-by-state. Certain states have laws that require religious buildings and private clubs to comply with accessibility standards. Most religious institutions want to be as welcoming as they can, and they are usually ahead of the crowd in providing ADA compliant restrooms, signs, and entrances.
Since you work in a public institution, you will need Braille accompanying your Exit sign. Raised Braille characters must be at least 5/8" (16mm) high, but no higher than 2" (50mm).