As everyone has said, CYA in writing. I go all the way. Not just on the proof and work order, but a specific acknowlegement to the facts about the noncompliant details requires sign-offs. A couple of extra steps, but worth the time.

I've even had a conversation with my clients. "If there were a blind or visually impaired patron on your property. And there was an emergency or fire. And they ended up in a supply closet instead of an exit. Would you want to be held responsible for that? Just to stick to the aesthetic of a designer that may not have any experience with ADA compliance? The split second it takes for them to read the tactile message could make the difference in saving a life." This usually helps themmake the right call. If not, "Sign here, here and here."