Is there an official height that toilet seats are supposed to be at according to the ADA?
From the source:
4.16.3* Height. The height of water closets shall be 17 in to 19 in (430 mm to 485 mm), measured to the top of the toilet seat (see Fig. 29(b)). Seats shall not be sprung to return to a lifted position. Appendix Note
and from the Appendix Note in question:
Toilet seats 18 in (455 mm) high seem to be a reasonable compromise. Thick seats and filler rings are available to adapt standard fixtures to these requirements.
If you are putting in more than one toilet in an office, you can meet more people’s needs by putting them in at different heights. Likewise if you are leaving space for a wheelchair next to the toilet, try to have one with the space on the left and another with the space on the right. Details like how easy it is to use the lock and light switch are very important, and just having a handrails on the wall next to the toilet can help lots of people.
A toilet that is too low is better than one that is too high, as it is easy to fit a Toilet Seat Riser if needed. (This does not work for public toilets.)
At all times, think about the why. I have too often seen items like handrails on a wall that can’t be reached as it is behind the water heater, etc. Will it really work for real people?