{"data":{"id":"us-nyc/n.y.c.-admin.-code-bc-u101","jurisdiction":"us-nyc","citation":"N.Y.C. Admin. Code § BC U101","heading":"Section BC U101: General","body":"U101.1 Scope.\n\nExcept as modified by the express provisions of this appendix, an ancillary dwelling unit shall be constructed on the same tax lot as a one- or two-family dwelling in accordance with the requirements of this code.\n\nU101.1.1 Multiple dwelling law.\n\nWhere the ADU is located within the same building as the primary dwelling, and the total number of dwelling units of such building exceeds 2, the entire building shall be classified as Group R-2 occupancy and comply with all applicable requirements of Group R-2 occupancy in this code and the New York State Multiple Dwelling Law as applicable, except for basement and cellar units in the program area pursuant to Section U202.12. Buildings constructed as Type V construction may not be converted or altered to a three-family dwelling, except for eligible conversions made habitable pursuant to U202.12.\n\nU101.2 General conditions.\n\nAny ADU permitted pursuant to this appendix must comply with the following conditions:\n\n1. An ADU shall only be permitted to be associated with a primary dwelling that is classified in occupancy Group R-3.\n\n2. An ADU shall not be used as a care facility providing custodial care to any persons pursuant to Section 310.5.\n\n3. An ADU shall not be constructed in the rear yard, as such term is defined by the New York City Zoning Resolution, of an attached one- or two-family dwelling.\n\n4. An ADU in a cellar must have a clear ceiling height that is at least 2 feet above the grade plane.\n\nU101.3 Types of ADUs.\n\nWhere permitted by the New York City Zoning Resolution, no more than 1 ADU may be constructed on each tax lot, in 1 of the following locations:\n\n1. Above the grade plane, adjoining, or within the same building as the one-family dwelling, including attic or enlargement, constructed in accordance with Section U201.\n\n2. In the basement or cellar of the building containing the primary dwelling, constructed in accordance with Section U202.\n\n3. Separated by a fire wall from the two-family dwelling, constructed in accordance with Section U203.\n\n4. Detached from the primary dwelling, constructed in accordance with Section U204.\n\n5. Manufactured home, installed in accordance with Section U205.\n\nU101.4 Certificate of occupancy.\n\nNo ADU shall be occupied for dwelling purposes without a certificate of occupancy issued by the commissioner to permit such ADU in accordance with Section 28-118.3 of the Administrative Code. An ADU constructed in accordance with Section U203, U204, or U205 shall require a separate certificate of occupancy from the primary dwelling unit. An ADU constructed in accordance with Section U201 and U202 shall require a new or amended certificate of occupancy for all the primary dwelling units and the ADU. In addition to Section 28-118.6 of the Administrative Code, such certificate of occupancy shall indicate the following as applicable:\n\n1. An ADU located in the basement or cellar shall be identified as “ADU Apartment U per BC U202”.\n\n2. An ADU located in the basement or cellar in the program area, as defined in Section U202.2, shall be identified as “ADU Apartment U per BC U202 and MDL Art 7-D”.\n\n3. An ADU with the main entrance opening to the rear yard shall be identified as “ADU Apartment R”.\n\n4. All ADUs shall have “Ancillary Dwelling Unit per ZR 12-10 and BC Appendix U” in the comment.\n\n5. An ADU located in the basement or cellar shall be indicated in the applicable flood area designation where the premises are located, in accordance with Section U202.3.1.\n\nException: Notwithstanding Section 28-118.3 of the Administrative Code, where an authorization for temporary residence is issued by the department in accordance with Article 507 of Chapter 5 of Title 28 of the Administrative Code and Section U202.12, a basement or cellar ADU shall be permitted to be occupied for dwelling purposes without the certificate of occupancy.\n\nU101. 5 Department rules.\n\nThe department shall consult with the fire department and the office of emergency management in promulgating any standard protective of health and safety pursuant to this Appendix.\n\n(L.L. 2024/127, 12/18/2024, eff. 6/16/2025)","path":["New York City Administrative Code","Title 28","Chapter 7: New York City Building Code"],"source_url":"https://files.amlegal.com/pdffiles/NewYorkCity/Admin/XML.zip","current_through":"Local Law 2026/135 (enacted August 31, 2026)","vintage":"","retrieved_at":"2026-09-06T02:48:57Z","sha256":"2b7fe399791b863f6ce5df09fbfab8bda1408d62e50dfe8ffe3cdaea2c4eb131","source_id":"us-nyc","stale":false,"prev":"us-nyc/n.y.c.-admin.-code-bc-s101","next":"us-nyc/n.y.c.-admin.-code-bc-u102"},"notice":"GroundRules: Original legal text. Not legal advice."}