§ 260. One and two-story frame dwellings; area limitation. A frame
dwelling not exceeding two stories in height erected pursuant to plans
filed after April first, nineteen hundred fifty-nine, and containing an
area greater than three thousand square feet must, in addition to any
other applicable provisions of this article, comply with the following
provisions:

1. Fire-stopped partitions shall be constructed between apartments in
such dwelling so as to prevent the passage of fire, smoke or gases from
one apartment to another.

2. No section of such dwelling shall contain more than three thousand
square feet. Each such section shall be separated from all other
sections of the dwelling by fire walls of masonry or other materials
having a fire resistive rating of at least two hours. Such wall (1)
shall be unpierced except for openings for heat, utility and other
service lines and ducts with such openings sealed with incombustible
materials (2) shall extend continuously from the floor of the lowest
level of the dwelling, to at least two feet above the level of the
finished roof and (3) be fire-stopped at floors and roof in such manner
as to prevent the passage of fire, smoke or gases between sections.
Where there is a peaked or sloped roof, such wall may terminate at the
top of the roof boards.