NYC code review is not a one-code exercise. The right code path depends on what you are doing, when the building was built, what was previously approved, and whether the proposed work changes use, occupancy, egress, structure, fire protection, accessibility, zoning, or building systems.
 
A new building is usually straightforward: start with the current NYC Construction Codes. Existing buildings are where the real code work starts. For those projects, the review generally begins with the current Administrative Code and current Construction Codes, then works backward only where prior-code compliance is still permitted.
 
At 3C Codes, the practical approach is simple: first identify the scope, then confirm the building history, then determine which current and prior-code provisions actually apply. Prior code is not a shortcut. It is a compliance tool that has to be supported by the building's approved history.
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Quick Answer: WHICH NYC CODE APPLIES?

For new buildings and new structures, start with the current NYC Construction Codes.

For existing buildings, start with the current Administrative Code and Construction Codes, then review whether the 1968 Building Code, 1938 Building Code, zoning, RCNY, Multiple Dwelling Law, DOB bulletins, prior approvals, or other laws need to be applied.

For filings submitted before the NYC Existing Building Code becomes effective, existing building work should still be reviewed under the current DOB framework. The NYC Existing Building Code has been enacted, but DOB lists the effective date as July 17, 2027. Until that effective date, alterations and maintenance of existing buildings continue to be regulated by the Administrative Code and the 2022 NYC Construction Codes, with the permitted prior-code framework for qualifying prior-code buildings.

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Applying the Codes Overview

The latest NYC Construction Codes are based on model code concepts, but New York City modifies and enforces them through its own local laws, Administrative Code, DOB rules, bulletins, and agency interpretations.

That means a project may involve more than one layer of review. A simple-looking alteration can still touch zoning, energy, accessibility, fire protection, structural requirements, prior-code conditions, and DOB filing procedures.

The question is usually not, "Which single code applies?" The better question is: Which code applies to this part of the work, in this building, under this approved history?

That distinction matters. A pre-1968 building, a 1970s building, and a post-2008 building may all be altered today, but they may not be reviewed the same way.