spiral staircase for loft

hey guys, heres a question for the builders among you
my daughter had a bedroom with vaulted ceilings and a build in closet that protrudes into the room
the top of this closet is 8 foot, 2 inches high, 2 foot deep and 8 and a half foot wide
ive been toying with the idea of building a loft up there by extending it out a few foot, giving it a foot print of 4 by 8 1/2 foot

i figured this would be a great hide out for her, or a place to sit back and read a book

my biggest issue is getting stairs to go up there, and i think a spiral staircase would look the best

anyone have any experience with this?

(here is a picture i snatched of the web, just to give you an idea of what the room looks like)

loft.jpg