N.Y.C. Admin. Code § 27-282: § 27-282 Construction class II-B.

Includes buildings and spaces in which the exterior walls, fire walls, exitways, and shaft enclosures are of noncombustible materials having the required fire-resistance ratings; and in which the floors, roofs, and interior framing are wholly or partly of wood of smaller dimensions than required for class II-A construction, or are of other combustible or noncombustible materials, having the required fire-resistance ratings.