N.Y.C. Admin. Code § EBC D504: D504 Fireproof stair enclosures (MDL 148(3)).

Every stair, fire-stair, and fire-tower shall be completely separated from every other stair, fire-stair, and fire-tower and from every public hall and shaft by fireproof walls, with fireproof doors and assemblies, with the doors self-closing and without transoms, at all openings. The doors giving access to such stairs shall not be held open by any device whatsoever.

Exceptions:

1. In dwellings 2 stories or less in height such walls shall be permitted to be constructed as 1-hour fire barriers in lieu of being fireproof.

2. In lieu of fireproof walls, such noncombustible walls shall be permitted to have a 2-hour fire-resistive rating where a full system of automatic sprinklers is installed throughout the building with a water-flow alarm connected to a central supervising station, and hard-wired smoke and carbon monoxide alarms or detectors are installed throughout the building as required for new construction in accordance with

Chapter 9

of the

New York City Building Code

.