New York Consolidated Laws, Multiple Dwelling Law - MDW § 211. Height and bulk

1. No tenement shall be increased in height so that its height shall exceed by more than one-half the width of the widest street upon which it stands.  Except as otherwise provided in subdivision four of this section, no non-fireproof tenement shall be increased in height so that it shall exceed five stories, except that any tenement may be increased to any height permitted for multiple dwellings erected after April eighteenth, nineteen hundred twenty-nine, if such tenement conforms to the provisions of this chapter governing like multiple dwellings erected after such date.

2. If there are bulkheads, superstructures or penthouses exceeding ten feet in height or exceeding in aggregate area ten per centum of the area of the roof, the measurement of height shall be taken to the top of such bulkhead, superstructure or penthouse, except that this shall not apply to elevator enclosures not exceeding twenty-three feet in height used solely for elevator purposes, nor to open pergolas or similar open ornamental treatment of roof-gardens or playgrounds.

3. In a fireproof tenement house in which one or more passenger elevators are operated, penthouses may be erected on the main roof.  Such penthouses shall be set back at least five feet from the front walls and ten feet from the rear walls of the dwelling and at least three feet from any court wall.  Such penthouses shall have a clear inside height of not less than nine feet from finished floor to finished ceiling, and shall not exceed twelve feet in height from the high point of the main roof to the highest point of the penthouse roof.  Such penthouses shall not be deemed to affect the measurement of height of the dwelling.  All such penthouses shall be entirely fireproof except that windows shall not be required to be glazed with wire glass.

4. Any non-fireproof old-law tenement five stories in height may be increased in number of stories to six provided that such increase in number of stories does not result in an increase in the height of the roof beams above the curb level.  In any tenement so altered, the first floor above the lowest cellar, or, if there be no cellar, above the basement or other lowest story, shall be fireproof.  Any yard or court of such altered tenement shall not be less in any dimension than the minimum dimensions prescribed in section twenty-six.