Renovating for co-op use. Variance? ADA?

My building has a space at the top of our building (30th floor) that used to house water towers. I’d like to turn this space into a gym facility for personal/coop use only. A few things of note:

-There is no elevator access. The nearest elevator is 3 flights down (27th floor)
-The entire floor isn’t listed on the current or any past CO.

I’m wondering what the implications of such a renovation would be. Do I need a variance? Does this trigger a change-in-use if not listed in the CO? Do I need to provide elevator access to make this space accessible?

Any advice is helpful.

[Screen Shot 2017-01-05 at 09](//muut.com/u/brownstoner/s1/:brownstoner:ixFl:screenshot20170105at09.24.06.png.jpg)