Key Project Terms: Alterations: 1- and 2-Family Mixed Use

The following is a list of useful terms to use when researching additional Residential & Community Facilities information on each of the topics discussed:


The design and construction of buildings for accessibility and use by persons with physical disabilities, complying  with the Federal ADA Standards; US Housing and Urban Development (HUD); BC Chapter 11, BC Appendices E, N and P; and/or ICC/ANSI A117.1.


An alteration is the addition, change of use, or occupancy of a building or structure in existence, and always results in a new or amended Certificate of Occupancy. Work may involve an enlargement, reduction in size of the building, or a major change to the building egress, zoning use group, and/or building code occupancy use.

Building Systems Work

The installation, modification, or upgrade of existing building systems including plumbing, boiler, sprinkler, standpipe, fire alarm, HVAC, and fire suppression systems. If such repairs are part of the project, they must be included in the scope of work.

Certificate of Occupancy

A new or amended Certificate of Occupancy is issued for a building on completion of a project involving a change in occupancy or use, or when there are other changes that impact the existing Certificate of Occupancy. For example, where an existing building is vertically enlarged by a complete story, or if the use of a building is changed from commercial to residential, a new or amended CO would be required. Reference AC 28-118.3 for more information.

The following may also be issued:

  • Partial Certificate of Occupancy, for a portion of a building erected prior to January 1, 1938, depending on construction progress and safety;

  • Temporary Certificate of Occupancy (TCO), for a limited duration of time, because the project is not closed due to outstanding items, such as final surveys not submitted, etc., per AC 28-118.16.

Code and Zoning Determinations

Determination requests are issued to the Borough Commissioner's office to resolve an objection raised by a plan examiner or a possible future objection for an application not yet filed (pre-determination). To request a determination, file a Zoning Resolution Determination Form (ZRD1 Form) (ZRD1 Instructions) or a Construction Code Determination Form (CCD1 Form) (CCD1 Instructions). Forms must be signed and sealed by a professional. Determination requests are limited to one per form and must cite all related Code or Zoning sections.


Per the Zoning Resolution, Commercial, as applied to building use, is any retail, service or office use. Commercial can also describe the type of zoning district.

Commercial Facility

As per the Zoning Resolution, 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.


Per the Zoning Resolution, a conversion is a change of use. A use is any purpose for which a building, structure, or open tract of land is designed, arranged maintained or occupied.

Elevation in Flood Zones

Elevating a building to ensure that lowest occupied floor is above the flood levels, per FIRMS, and as described in BC Appendix G and ZR Article VI.


Per the Zoning Resolution, an enlargement is an addition to the floor area of an existing building or zoning lot, or an expansion of a use to an area not previously used for such purpose.
Per the Building Code, an enlargement is any addition of gross floor area to a building.

Layout Changes

Include changes to floor layouts that add, relocate, remodel, enlarge or reduce the size of interior rooms while maintaining the same building envelope.

Lot Line Windows

Windows of a building exterior wall located on the side or rear property zoning or tax lot lines. Such lot line windows require special Code-compliance review, dependent on the building type and building construction class, to determine the allowable window sizes, quantity, and fire protection needed.

Mixed Building

Per the Zoning Resolution, a mixed building is a building used partly for residential use and partly for community facility, and/or commercial use.

Mixed Use

Per the Building Code, a building with mixed occupancy would contain two or more occupancy classifications. Such occupancy classifications may or may not match the zoning use groups.

Natural Light and Air

The amount of natural light and natural air ventilation derived from passive openings such as operable and openable windows and skylights; this may be important in some rooms located within residential buildings to ensure compliance with Code and Zoning requirements.

New Building

New building is enclosed construction over a plot of land, having a foundation and footings, a roof and usually windows, used for any of a wide variety of activities, such as living, entertaining, or manufacturing.

Non-Complying Use

Any lawfully existing building or other structure which does not comply with applicable bulk regulations either on December 15, 1961 or as a result of a subsequent zoning amendment.

A non-compliance is a failure of a building or other structure to comply with any bulk regulation(s).

Non-Conforming Use

Per ZR 12-10, non-conforming use is any lawful use of a building that does not conform to any one or more of the applicable zoning use regulations of the district in which it is located. A non-conforming use shall result from failure to conform to the applicable district regulations on either permitted Use Groups or performance standards. Existing non-conforming use to remain per ZR 52-00.


The purpose or activity for which a building or space is used or is designed, arranged or intended to be used.

Occupancy Classification

The use as defined in the Building Code, and is the purpose or activity for which a building or space is used or is designed, arranged or intended to be used

One-Family Home

Any building or structure designed and occupied for residence purposes on a long-term basis for more than a month at a time by not more than one family as required by the Housing Maintenance Code (HMC).
Two-Family Home: Any building or structure designed and occupied for residence purposes on a long-term basis for more than a month at a time by not more than two families as required by the HMC.

Partial Demolition

Any construction that involves the removal, replacement or repair of load bearing and/or non-load bearing interior partitions, changes to structural elements (interior or exterior), facade changes, upgrades or portions thereof while maintaining the existing structure.

Registered Land Surveyor

A person licensed and registered to practice the profession of land surveying under the education law of the state of New York.


Changes to an existing building, including the remodeling or replacing of outdated or damaged structure and materials, and the partial demolition of interior partitions.  Building renovations can also include the installation or replacement of building systems, devices or equipment, materials or parts, as part of regular maintenance of the building. Renovation projects do not impact the existing means of egress, do not change the use of the building or space, and do not increase the occupant load.


Per the Building Code, Residential Group R includes the use of a building or structure, or a portion thereof, for dwelling or sleeping purposes. If there are three or more dwelling units in the building, it shall be classified as a multiple dwelling and is subject to the MDL. Residences can be either transient, in which the occupancy of a dwelling unit or sleeping unit is not more than 30 days, or non-transient, and therefore, could include community facilities with sleeping accommodations.
Per the Zoning Resolution, Residential, as applied to building use, is a building with one or more dwelling units or rooming units, but with exceptions; for example, hotels and community facilities with sleeping accommodations are not residences per the ZR. Residential can also describe the type of zoning district; for example, hotels are not allowed in residential districts, while community facilities can be located in residential districts.


A story is a floor level in a building that is significant in both the Code and Zoning Resolution. For example, if a fourth story is added to a one or two family home, it could trigger additional fire protection requirements in the Code. Basements are stories, while cellars are not. An attic may be considered as a story.

Tax Lot

A tax lot is a tract of property on the New York City tax map, for which property taxes are assessed. Multiple buildings can be present on a single zoning lot or on a single tax lot.


The purpose for which a building, structure, or space is occupied or utilized, unless otherwise indicated by the text; Use (used) shall be construed as if followed by the words ‘or is intended, arranged, or designed to be used.’

Use Group

The use as defined in the Zoning Resolution, Section ZR 12-10, and is any purpose for which a building or other structure, or an open tract of land, may be designed, arranged, intended, maintained or occupied; furthermore the use is any activity, occupation, business or operation carried on, or intended to be carried on.

Zoning/Zoning Resolution (ZR)

The aim of Zoning is to promote an orderly pattern of development and to separate incompatible land uses, such as industrial uses and homes, to ensure a pleasant environment. The Zoning Resolution is a legal instrument to regulate and establish limits on the use of land and building size, shape, height, and setback.

Zoning Lot

A zoning lot is a tract of land for which specific zoning regulations apply. A zoning lot does not have to coincide with a tax lot, and can consist of one tax lot or multiple tax lots

Key Points & Project Terms Categories

  1. Alterations

  2. Building Systems Installation & Modifications

  3. Construction Equipment

  4. Demolition COMING SOON!

  5. New Buildings COMING SOON!

  6. Renovations

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