Key Project Terms: Basement/Cellar Apartments and Local Law 49 of 2019 (Alterations)

The following is a list of useful terms to use when researching additional Local Law 49 of 2019 Basement/Cellar Apartment Alteration information on each of the topics discussed:

Basement/Cellar Apartment Alteration


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:

  • Temporary Certificate of Occupancy, 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 for 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, 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.

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.


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

One and Two Family Home

One-Family: 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: 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

Maintaining the same building envelope, 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), and facade changes or other upgrades.

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. Per the Zoning Resolution, ‘Residential,’ as applied to a building’s use, is a building with one or more dwelling units or rooming units, but with exceptions. ‘Residential’ can also describe the type of zoning district


A story is a floor level in a building that is significant in both the Code and Zoning. For example, if a third 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 used to describe 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.

Local Law 49 of 2019

Program Area

Under the context of this local law, program area means Brooklyn community district 5, excluding Special Enhanced Commercial District and other areas generally south of line drawn under LL 49/2019.

Qualified Environmental Professional

LL 49/2019 §1.6 refers to DEP Rule 15 RCNY 24-03 for definition of a ‘qualified environmental professional’ (QEP). 15 RCNY 24-03 defines a QEP as “a person who possesses sufficient specific education, training, and experience necessary to exercise professional judgment to develop opinions and conclusions regarding the presence of releases or threatened releases to the surface or subsurface of a property or off-site areas, sufficient to meet the objectives and performance factors for the areas of practice identified by 15 RCNY Chapter 24.”

A QEP must:

  • Hold a current professional engineer's or a professional geologist's license or registration issued by any state, or hold a baccalaureate degree or higher in engineering or geology and have the equivalent of three years of full-time relevant experience in site investigation and remediation of the type detailed in 15 RCNY Chapter 24; or
  • Be a site remediation professional licensed or certified by the federal government, any state or a recognized accrediting agency, to perform investigation or remediation tasks consistent with office guidance, and have the equivalent of three years of full-time relevant experience.


Under the context of this local law, the term ‘apartment’ means a dwelling unit providing permanent provisions for both sanitation and kitchen facilities, occupied or arranged to be occupied by not more than 1 family maintaining a common household.


Under the context of this local law, the term ‘basement’ means a story partly below the grade plane and having less than ½ its clear height below the grade plane. The height is measured from finished floor to finished ceiling.


Under the context of this local law, the term ‘cellar’ means the portion of the building that is partly or wholly underground, and having ½ or more of its height below the grade plane. The height is measured from finished floor to finished ceiling. A cellar shall be counted as a story in measuring height of a building.

Grade Plane

Grade Plane, as defined in BC 502.1, is a reference plane representing the level of the curb as established by the city engineer in the Borough President's office, measured at the center of the front of a building. Where a building faces on more than one street, the grade plane shall be the average of the levels of the curbs at the center of each front.

Under the context of this local law, the definition of Grade Plane is generally similar to the zoning terminology of Curb Level, which, as defined in ZR 12-10, is the mean level of the curb adjoining a zoning lot. On corner lots, curb level is the average of the mean levels of the adjoining curbs on intersecting streets.

Partial or Amended Certificate of Occupancy

The following may be issued for alterations per LL 49 of 2019:

  • A Partial Certificate of Occupancy, if the existing building was erected prior to 1/1/1938 and no existing C.O. Note: LL 49 of 2019 §7.a.i allows partial certificates of occupancy for just the newly created apartments.
  • An amended Certificate of Occupancy, if the existing buildings has an existing C.O. Note: LL 49 of 2019 §7.a.ii allows amended certificates of occupancy for just the newly created apartments.

Pre-existing Violation

Under the context of this local law, a “pre-existing violation” means a violation issued by the department of buildings for which a notice of violation, administrative summons, criminal court summons or other process was issued prior to the date of issuance of the initial permit for work pursuant to this local law.

Window Well

Under the context of this local law, a partially below grade window surrounded by a ‘window well’ is permitted to contribute to the area required for natural light for a below grade habitable room, if such window well complies with LL 49/2019 §4.7.b.

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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