§ 9. Buildings converted or altered. 1. On or after July first,
nineteen hundred fifty-two, no multiple dwelling shall be enlarged or
its lot diminished so that the yard or other unoccupied areas shall be
diminished in size or area below the minimum requirements of this
chapter.

2. A building not a dwelling, if converted on or after July first,
nineteen hundred fifty-two, to a multiple dwelling, shall thereupon
become subject to all the provisions of this chapter applicable to new
multiple dwellings of like class and kind. "Class" shall mean the use of
a multiple dwelling for either permanent or transient occupancy or both.
"Kind" shall mean the type of construction of a building, either
fireproof or non-fireproof.

3. No dwelling shall be altered or converted so as to be in violation
of any provision of this chapter relating to dwellings of like class and
kind, and, except as provided in subdivision four, a dwelling, altered
or converted to be occupied primarily for permanent-residence use, shall
comply with article three; and a dwelling converted or altered to be
occupied primarily for transient use shall comply with article four.

4. If any multiple dwelling three or more stories in height is altered
after July first, nineteen hundred fifty-three so as to increase its
height or bulk for living purposes or so as to increase the number of
living rooms by more than twenty per centum, such dwelling shall be made
to conform to the requirements of this chapter with respect to new
dwellings of like class and kind erected after such date.

5. It shall be unlawful to convert a frame dwelling to a multiple
residence, except that a frame dwelling not more than two stories and
attic in height and erected before July first, nineteen hundred
fifty-two, as a one-family or two-family residence may be converted to a
multiple dwelling for permanent occupancy by complying with article
three; and if such residence is converted to be occupied, as a rule, for
transient use, it shall comply with article four.