Project Categories: Alterations - 1- and 2-Family Mixed Use

An alteration work application always results in the issuance of a new or amended Certificate of Occupancy. Types of alteration work may include any combination of the following:

  • Vertical and Horizontal Enlargement. An addition to the floor area in an existing building

  • Conversion. A change of an existing use or a new use, in an area not previously used for such purpose. A conversion is a change of ‘use’ as defined by the Zoning Resolution, and/or a change in the ‘occupancy classification’ as defined in the Building Code. A use or occupancy classification of a building is any purpose for which it is designed, arranged, maintained or occupied.

  • Egress Modifications. Any substantive change in the exiting width, length of travel distance, location, or occupancy load of exits, or any change in number of required exits in a building.

  • Floor Area Reductions. A reduction to an existing building’s floor area that impacts the Certificate of Occupancy; for example, the complete elimination of one or more stories from a building or the demolition of a public assembly space on the top floor.

A mixed-use building contains any combination of two or more uses; for example, residential and mercantile or residential and business. In the NYC Zoning Resolution (ZR 12-10), a ‘mixed building’ is a more narrowly defined term and includes only residential and commercial uses.

Per BC 310.1.3 occupancy classification R-3, these buildings provide shelter and sleeping accommodations on a long-term basis including, 1- and 2-family dwellings, group homes, convents and monasteries with fewer than 20 occupants, and similar residences.

A commercial space, or Business ‘B’ occupancy classification per BC 304 includes, but is not limited to: public, civic, and professional offices; banks; service-oriented establishments such as dry cleaning/laundry or barber/beauty shops; ambulatory health care facilities; animal hospitals and kennels; educational occupancies for students above the 12th grade; nonproduction laboratories; public libraries; motor vehicle showrooms, or similar. Commercial buildings may also include a building space used for any ‘Assembly’ occupancy classification with an occupant load of fewer than 75 persons, which is classified as Group B occupancy per BC 303.1.

A mercantile space, occupancy classification ‘M’ per BC 309 includes the display and sale of goods to the public such as drug stores, markets, retail or wholesale stores.

Per the Zoning Resolution ZR 22-13, a community facility may be located in residential areas to serve, on a not-for-profit basis, the educational, emotional, mental health needs, or other similar essential services of its residents.

Project Notes

  • Extensive alterations that involve increasing the floor surface area in excess of 110% are required to comply with requirements as if it were new construction. However, such a project shall be filed as an alteration.

  • Alteration work could also include other remodeling/renovation projects in the scope of work, which are better described under the various Renovation Project Guidelines.

  • Building Systems, such as new or modified plumbing, HVAC, or gas systems could be involved in an alteration project, which are better described under the various Building System Guidelines.

  • An alteration project shall not be filed as a renovation project. Renovations and/or existing Building System projects could be part of a larger alteration project’s scope of work.

  • Refer to Commercial Alteration guidelines for additional requirements pertaining to those uses.

  • Refer to Community Facility Alteration Guidelines for additional requirements pertaining to those uses.

Project Categories:

  1. Building Systems Installation & Modifications

  2. Renovations

  3. Construction Equipment

  4. Alterations

  5. Demolition COMING SOON!

  6. New Buildings COMING SOON!

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