N.Y.C. Admin. Code § EBC D603: D603 Conversion to 3 families; no more than 3 stories.

A building originally erected before December 6, 1968, as a one- or two-family dwelling, 3 stories or less in height, shall be permitted to be converted to a Class A multiple dwelling with no more than 3 families and shall be classified EBC-CDA, provided such building meets this code and the following requirements. However, for such building, any requirement of this code that covers the same subject matter as the following shall not apply, and such following requirements in Sections D603.1 through D603.15 shall apply in lieu thereof:

D603.1 Frame buildings.

The building shall not be a frame building. However, the conversion of nonresidential spaces in existing frame buildings to apartments shall be permitted in accordance with the Exception to Section D306.5.

D603.2 Treads and risers.

The treads and risers of every stair shall be of uniform height and width in any 1 flight. Each tread, exclusive of nosing, shall be not less than 9 and one-half inches wide (241.5 mm); each riser shall not exceed 7 3/4 inches (197 mm) in height; and the product of the number of inches in the width of the tread and the number of inches in the height of the riser shall be at least 70 inches (1778 mm) and at most 75 inches (1905 mm).

D603.3 Public hall.

Every public stair hall shall provide access to the street as well as extending to and through the roof by a bulkhead or scuttle, except that no bulkhead or scuttle, or stair or ladder leading thereto, shall be required where the roof is a peak roof with a pitch of more than 15 degrees (0.26 rad).

D603.4 Stairs.

Existing wood stairs shall be permitted to remain. Existing stairs shall be at least 30 inches (762 mm) in clear width.

D603.5 Entrance hall.

The entrance hall to the street shall be at least 32 inches (813 mm) in clear width.

D603.6 Scuttle.

Any scuttle required by Section D603.3 shall be at least 21 inches (533 mm) in width and 28 inches (711 mm) in length, covered on the outside with metal and provided with a stair or a stationary iron ladder leading thereto and easily accessible to all occupants of the dwelling. Every scuttle shall be located in the ceiling of the stair hall on the top story and access to the roof through the scuttle shall be direct and uninterrupted. It shall be unlawful to enclose in any manner the ladder or stair leading to a scuttle.

D603.7 Roof access.

Every bulkhead door or scuttle shall not be self-locking and shall be fastened on the inside with movable bolts, hooks, or a lock which does not require a key to open from the inside of the dwelling.

D603.8 Business purposes.

No part of such dwelling shall be used for business purposes, except a home occupation as provided for in the New York City Zoning Resolution.

D603.9 Boarders, roomers, lodgers.

No part of such dwelling shall be arranged, designed for, or occupied by roomers, boarders, or lodgers.

D603.10 Dwelling unit doors.

The dwelling unit entrance doors and door assemblies in public stair halls and public halls shall be provided with self-closing door assemblies with a minimum of a three-fourth-hour fire resistance rating.

D603.11 Fire rating of public hall and fire retarding of stairs.

The public hall and stair partitions shall be constructed as 1-hour fire barriers and the soffit of the stairs, if combustible, shall be fire retarded in accordance with Section E402 of Appendix E.

D603.12 Fire rating of ceilings.

The ceiling of the cellar and the ceiling of any dwelling unit located below a different dwelling unit, or below a public hall or stair, shall be constructed as horizontal assemblies with a fire-resistance rating of not less than 1 hour.

D603.13 Separation of dwelling units.

Dwelling units shall be separated by assemblies meeting a fire-resistance rating of not less than 1 hour.

D603.14 Cellar entrance.

If there is a cellar, there shall be an independent entrance thereto from outside the dwelling by means of a metal fire ladder or fireproof stair leading to an opening in the outside cellar wall at least 30 inches (762 mm) in width and 6 feet (1829 mm) in height. Such entrance to the cellar shall be permitted to be through an areaway or through a fireproof passageway leading directly to the street. The entrance to the cellar may be closed off with a grating or doors which shall not be locked or bolted unless they can be readily unbolted or unlocked from the inside without a key and shall be arranged and constructed so as to be readily opened at all times. Such cellar entrance shall not be used to satisfy a required means of egress unless it also meets the standards required for such egress.

D603.15 Sprinklers.

Sprinklers shall be provided throughout the building in accordance with Section 903 of the New York City Building Code.