The avg stair is 7" tall and 11" deep.
Climbing 13 avg stairs, you climb 91" or 7'-7".
Given that everyone has 13 stairs, how tall are your ceilings on your lower floor? Avg floor joists are 10" deep. So, 7'-7" minus 10" is 6'-9". I would get my head cut off by your ceiling fans.
My house has 8' ceilings, but still only 13 stairs.
