New York Consolidated Laws, Multiple Dwelling Law - MDW § 241. Partitions;  fire-stopping

1. In tenements erected after April eighteenth, nineteen hundred twelve, wood stud apartment partitions which are directly over each other shall run through the wood floor beams and rest upon the plate of the partition below.  In fireproof tenements erected after such date all partitions shall rest directly upon the fireproof floor construction and extend to the fireproof beam filling above.  Apartment partitions within the meaning of this section are partitions crossing the floor beams at any angle and separating one apartment from another or any part of an apartment from any public part of the dwelling.

2. In tenements erected after April eighteenth, nineteen hundred twelve, apartment studding shall be filled in solidly between the uprights to the depth of the floor beams with incombustible materials.

3. In non-fireproof tenements erected after April twelfth, nineteen hundred one, in every wall where wood furring is used, every course of masonry from the under side to the top of any floor beams shall project a distance of two inches or more beyond each face of the wall that is not on the outside of the dwelling, so as to provide an effective fire stop;  and whenever floor beams run parallel to a wall and wood furring is used, every such beam shall always be kept two inches away from the wall, and the space between the beams and the wall shall be built up solidly with brickwork from the underside to the top of the floor beams so as to form an effective fire stop.