Cal. Civ. Code § 150
Cellar and basement stairs
Operative Text
§ 150. Cellar and basement stairs. 1. Except as otherwise provided in this section, there shall be no inside stair communicating between the lowest cellar or the lowest story, if there be no cellar, and the floor next above, but any stair communicating between such floors shall be located outside the dwelling and if enclosed shall be fireproof in a fireproof enclosure with fireproof doors and door assemblies, with the doors self-closing, at all openings. 2. This provision, however, shall not apply to any stair not extending through more than one story and leading from an entrance hall to the upper stories where the walls enclosing such hall are fireproof and unpierced except for openings to stairs, elevators, apartments, public reception rooms, professional offices and the outer air. In no event shall there be any other opening from such an entrance hall, and all apartments and such professional offices opening therefrom shall be entirely separated from any space within such dwelling used for any other purposes by fireproof walls which shall be unpierced except for means of egress into the entrance hall. The provisions of this subdivision shall not apply to openings which are protected with fireproof vestibules. Any such vestibule shall have a minimum superficial floor area of fifty square feet and its maximum area shall not exceed seventy-five square feet. It shall be enclosed with incombustible partitions having a fire-resistive rating of three hours. The floor and ceiling of such vestibule shall also be of incombustible material having a fire-resistive rating of at least three hours. There shall be two doors to provide access from the entrance hall and any other space not used for openings to stairs, elevators, apartments, public reception rooms and the outer air. Each such door shall have a fire-resistive rating of one and one-half hours and shall be provided with a device to prevent the opening of one door until the other door is entirely closed. One of these doors shall swing into the vestibule from the entrance hall and the other shall swing from the vestibule into space which it serves. Such vestibule shall also be equipped with sprinklers and with an independent exhaust duct having a minimum cross-sectional area of one hundred forty-four square inches for each one thousand cubic feet, or fraction thereof, of air content, and such exhaust duct shall not be connected with any other ventilating system. 3. In dwellings three stories or less in height which are occupied by two families or less on every story, any stair leading to the cellar may be located inside the dwelling provided it is entirely enclosed with fireproof walls and with fireproof doors and door assemblies at both the cellar level and the story above, with the doors self-closing. 4. The provisions of subdivision one shall not prohibit or apply to an inside stair extending from a space used for commercial purposes in the cellar or lowest story to a store on the story next above, provided such stair is of incombustible materials, has closed risers, is enclosed between the two lowest floors with walls having a three-hour fire resistive rating and has fireproof doors and door assemblies at top and bottom, with the doors self-closing, and provided such commercial space in the cellar or lowest story is completely enclosed with partitions having a fire-resistive rating of at least two hours and there is no opening between the store on the story next above and any entrance hall or other public hall or public portion of the dwelling.
N.Y. Mult. Dwell. Law § 150 establishes fire-safety rules governing how stairs connecting a building's lowest cellar or ground-level story to the floor above may be constructed and positioned. As a general rule, such stairs must be located outside the dwelling and, if enclosed, must be built with fireproof materials, fireproof enclosures, and self-closing fireproof doors. The law carves out several exceptions—including for small residential buildings, certain entrance-hall configurations with compliant fireproof vestibules, and commercial-to-store connections—each of which comes with its own detailed construction and fire-resistance requirements.
Plain English — not legal advice.
Operators of multiple dwellings subject to N.Y. Mult. Dwell. Law § 150 generally ensure that any stair connecting the lowest cellar or ground story to the floor above is either positioned outside the building or, where an exception applies, fully enclosed with materials meeting the statute's fire-resistive ratings and fitted with self-closing fireproof doors and door assemblies. Compliant operators document which exception, if any, applies to their property—such as the small two-family dwelling allowance under subdivision 3 or the commercial-space provision under subdivision 4—and maintain all required enclosures, vestibule dimensions, sprinkler systems, and exhaust ducts in working order. Routine inspections and records of any construction or alteration work help demonstrate ongoing compliance with the provision's specific technical standards.
General guidance for property managers — not legal advice for your specific situation. Consult an attorney for advice on your case.
N.Y. Mult. Dwell. Law § 150 gives tenants an interest in knowing that cellar and basement stair configurations in their building meet the fire-safety standards the law prescribes, including proper enclosures, self-closing fireproof doors, and—where vestibules are used—compliant construction and sprinkler systems. Tenants who believe their building's stair arrangement does not conform to § 150 may consider reporting the condition to the New York City Department of Buildings or the relevant local building or housing authority, which has enforcement authority over multiple dwelling code requirements. Tenant-rights organizations and legal aid offices can help residents understand what documentation to gather and what complaint or inspection processes may be available.
General guidance for tenants — not legal advice for your specific situation. Consult a tenant-rights organization or attorney for advice on your case.
Generated September 13, 2026 — auto-generated, not yet human-reviewed. See /transparency for methodology.
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