N.Y.C. Admin. Code § 27-121: § 27-121 Alterations to residence buildings.

Alterations to one-or two-family residence buildings erected under the provisions of the building code in effect prior to December sixth, nineteen hundred sixty-eight, and damaged by fire or other catastrophe to the extent of less than fifty percent of the value of the building (except as otherwise provided in section 27-297 of article four of subchapter four of this chapter) may be reconstructed in accordance with the provisions of the building code in effect prior to December sixth, nineteen hundred sixty-eight.