N.Y. Multiple Dwelling Law § 239: Tower fire-escapes and supplemental stairs

§ 239. Tower fire-escapes and supplemental stairs. In fireproof

tenements tower fire-escapes or stairs which are supplemental to the

stairs required by law may be installed providing such tower

fire-escapes or stairs shall be shut off from all other parts of the

dwelling by brick walls or partitions of terra cotta blocks at least

four inches thick, or hollow cement blocks at least four inches thick

which have successfully withstood a three-hour standard fire test and

been approved by the department, and have fireproof doors and assemblies

with the doors self-closing at all openings. Whenever such supplementary

stairs are provided they shall be constructed in accordance with such

supplementary regulations as may be adopted by the department. Such

tower fire-escapes or stairs shall not be used as service stairs and

shall be kept adequately lighted at all times and free from encumbrance.