While it is a convention that buildings over 12 storeys high do not have an elevator button 13, I am always curious as to whether there is a hidden floor, not accessible from the elevator.

For six months, I was working for a bank, which had a 20 storey building (though I was working in an 8 storey annexe), and I still do not know to this day whether there is a hidden floor 13.

One way to find out is to use the stairs. This option was not available to me, as all the emergency exit doors were alarmed, and there was no fire drill to provide the opportunity.

Another way is to count the floors of the building from the outside. If the skyscraper is very tall, this can be very difficult. Also, the following complicate the issue:

  • British lifts start at floor 0 (or G), the ground floor, whereas American elevators have floor 1 as the ground floor. I have used this comparison when teaching about arrays to CS students.
  • Sometimes, your entrance to the building is not on the ground floor, e.g. if the building is on a hillside.
  • Sometimes, there are mezzanine floors between floors.
  • Sometimes a parapet obscures the top floor(s).
  • Often the elevator does not go all the way to the top of the building. This is so that the winch machinery can be housed inside the building without any ugly projections.

Have any noders encountered real hidden 13th floors? I would be interested to hear stories.