There are two areas of NYC laws that touch upon this. You are over 9 units, so the first definitely applies to you: The first is the Housing Maintenance Code, Article 13, and it states that "a building of 9 apartments or more" is subject to the requirements.

The second is the Multiple Dwelling Law Article 3/title 83, which states "a dwelling with thirteen or more tenants."

Both articles state either/or... a 24 hour janitor or housekeeper or a janitor can reside in the building or a janitor can reside within 200 feet of the building (or the agent or owner lives in the building).

If you have a responsible party for the Coop that lives in the building (the Board President, or the like) who can be responsible in an emergency, you can most likely satisfy the requirements of the Fair Housing Maintenance Code, which is quoted at the top. I would put that person on the Multiple Dwelling Registration of the building as well.