N.Y. Lab. Law § 269

§ 269. Application of provisions. 1. The provisions of sections two\nhundred and sixty-one, two hundred and sixty-two, two hundred and\nsixty-three, two hundred and sixty-five, two hundred and sixty-six, and\ntwo hundred and sixty-seven shall apply to all buildings erected after\nOctober first, nineteen hundred and thirteen, and to all construction\nmade after that date in buildings erected prior to that date. The board\nshall adopt rules affecting construction made before October first,\nnineteen hundred and thirteen, in buildings theretofore erected,\nrequiring compliance with such of the requirements of said sections, or\nwith such other or different requirements as it finds reasonable and\nadequate to protect persons employed in such buildings against fire.\n 2. Altered buildings. When changes are made to a building erected\nprior to October first, nineteen hundred thirteen, which are so material\nand extensive as to constitute a new building, such building shall\ncomply with the provisions of section two hundred seventy. However, the\nwords material or extensive shall not apply if the structure is altered\nby adding an extension horizontally in such manner as to increase any or\nall of its floor areas by not more than twenty-five per centum.\n