Cal. Civ. Code § 170-A
Notwithstanding any other provision of this chapter, a dwelling, other than a frame dwelling, three stories or less in height erected aft...
Operative Text
§ 170-a. Notwithstanding any other provision of this chapter, a dwelling, other than a frame dwelling, three stories or less in height erected after April eighteenth, nineteen hundred twenty-nine as a one or two-family dwelling may be converted to a multiple dwelling to be occupied by not more than three families in all, with a maximum occupancy of two families on each floor in a two story building and one family on each floor in a three story building, provided however that all the provisions of this article are complied with and provided further that 1. No part of such dwelling shall be used for business purposes. 2. No part of such dwelling shall be arranged, designed for or occupied by roomers, boarders or lodgers. 3. The public hall or stair partitions and soffit of stairs shall be fire-retarded and said partitions fire-stopped. The apartment entrance doors and door assemblies in such hall shall be fire-proof and self-closing. 4. The required stairs shall comply with the provisions of subdivision three of section fifty-two of this chapter. 5. No door opening shall be permitted from a garage within the building to the stair hall or public hall. However, any other opening to the residential portion shall be provided with a fire-proof self-closing door, and the door assemblies shall be fire-proof. 6. The cellar shall not be used for any purpose other than household storage and mechanical equipment or appliances, and the cellar ceiling shall be fire-retarded.
N.Y. Mult. Dwell. Law § 170-A creates a specific conversion pathway for non-frame dwellings of three stories or less that were built after April 18, 1929, as one- or two-family homes. Such a building may be converted into a multiple dwelling housing no more than three families total, subject to strict occupancy caps per floor. The provision also imposes a set of structural and fire-safety conditions—covering hall and stair fire-retarding, door assemblies, garage openings, cellar use, and stair compliance—and prohibits any business use, as well as occupancy by roomers, boarders, or lodgers.
Plain English — not legal advice.
Property owners considering a conversion under N.Y. Mult. Dwell. Law § 170-A generally verify that the building meets the threshold criteria—non-frame construction, three stories or fewer, built after April 18, 1929, and originally a one- or two-family dwelling—before proceeding. Compliant operators typically ensure that public hall and stair partitions are fire-retarded and fire-stopped, that apartment entrance doors in those halls are fire-proof and self-closing, that no garage door opens directly into a stair or public hall, and that the cellar is restricted to household storage and mechanical equipment with a fire-retarded ceiling. Operators also confirm that the building will not be used for any business purpose and that no portion will be arranged for roomers, boarders, or lodgers, as § 170-A expressly prohibits both.
General guidance for property managers — not legal advice for your specific situation. Consult an attorney for advice on your case.
Tenants living in a building that was converted under N.Y. Mult. Dwell. Law § 170-A have an interest in knowing that the conversion was required to meet specific fire-safety and occupancy standards, including limits on total families, restrictions on business use, and prohibitions on roomer or boarder arrangements. If conditions in the building appear inconsistent with these requirements—such as missing fire-retarded partitions, non-compliant stair hall doors, or improper cellar use—tenants may have grounds to raise a violation with local housing or building code enforcement authorities. Tenant-rights organizations and legal aid services can help residents understand how § 170-A's requirements relate to their specific building's history and what complaint or defense options 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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