Alteration or Renovation?
In NYC DOB language, most renovations are technically filed as building alterations. The DOB uses the term “alteration” on permits and applications, while “renovation” is an everyday word owners and brokers use for the same types of projects.
Alteration (in NYC DOB sense) means a construction project which, upon successful completion and final inspection, always results in the issuance of a new Certificate of Occupancy.
Examples: converting a one-family house into a two-family, adding a floor or major extension, changing a store into an apartment, or reworking egress paths.
Work that does not result in a new CO* is classified as a renovation project.
In simple words: if the change (already done without paperwork) makes your legal home nicer, newer, or better laid out, without changing its official classification → it’s renovation.
When in doubt, safely consult an architect or expeditor – some “big renovations” cross into alteration territory even if they feel like “just remodeling” to a homeowner.
An alteration changes the “legal facts” about your building: use, occupancy, exits (egress), or building size.
Types of alterations (how DOB classifies them)
Alteration Type – I – This is described as a major change to the Certificate of Occupancy (CO). It could be a commercial to residential conversion or vice versa. Or an additional building or space…
Alteration Type – II – These are alterations that do not change the use or occupancy of the building but require several types of work – which could be plumbing or construction. When this application is filed under directive 14 the applicant may sign off after Final Inspection has been completed.
Alteration Type – III – This is a minor alteration that involves minimal work such as the cutting of a curb or a construction fence. In some instances detailed plans are not required and these can be filed by a non-professional.
Related terms
Some glossary entries use an asterisk * at the end of the term (for example, violation*). This mark is only a technical tool to stop the system from creating too many automatic links on the website. It does not change the meaning of the term.
- Renovation*
- occupancy
- building
- Certificate of occupancy
- Final inspection
- inspector*
- PW1
- code
- approval
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