Building Conversion or Occupancy Complaint

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You can report building occupancy that goes against its authorized use or past conversion to a room, space, apartment, or building that was done without DOB approval.

Conversion or Alteration

Illegal conversion is when an existing residential or commercial building has been changed to create an additional room, space, or unit without first getting approval from the New York City Department of Buildings.

Use or Occupancy

Illegal use is when a residential or commercial property is being used for anything other than its approved Certificate of Occupancy or zoning.

This can include illegally renting housing to guests who stay less than 30 days. To report a residential rental less than 30 days, go to the Housing Used for Short-Term Rental (Vacation Rentals or Illegal Home-Sharing) page.

Learn if an apartment or room is illegal or unsafe.

Reports of illegal activities must be reported to the New York Police Department (NYPD). Call 911 to report illegal or dangerous activity, including drug use or sale, gambling, prostitution, or immediate danger in progress.

You can report a past illegal residential building conversion or alteration to the Department of Buildings (DOB).

Illegal conversions include: 

  • Illegal apartments from an altered basement, cellar, or attic.
  • Other illegally subdivided areas of an apartment, house, or a building.

Include in your report:

  • Details about the original use of the building
  • Details about the new use of the building

To report active/current construction without a permit or against approved plans, go to the Building Construction Complaint page.

Reports of illegal activities must be reported to the New York Police Department (NYPD). Call 911 to report illegal or dangerous activity, including drug use or sale, gambling, prostitution, or immediate danger in progress.

You can report past illegal conversion or alteration of a commercial space to the Department of Buildings (DOB).

This includes commercial space altered for residential or manufacturing purposes.

Include in your report:

  • Details about the original use of the building
  • Details about the new use of the building

To report active/current construction without a permit or against approved plans, go to the Building Construction Complaint page.

Reports of illegal activities must be reported to the New York Police Department (NYPD). Call 911 to report illegal or dangerous activity, including drug use or sale, gambling, prostitution, or immediate danger in progress.

You can report past conversion or alteration of a manufacturing building that is now being used as residential or commercial space to the Department of Buildings (DOB).

Include in your report:

  • Details about the original use of the building
  • Details about the new use of the building

To report active/current construction without a permit or against approved plans, go to the Building Construction Complaint page.

You can report a residential space used as a business. This type of activity violates zoning regulations.

Include in your report:

  • The type of business

You can report people living in commercial space. This type of activity violates zoning regulations.

You can report a rooming house, boarding house, or other Single Room Occupancy (SRO) dwelling that is used as a business, illegally converted, or overcrowded.

SRO dwellings are specific types of dwellings that rent out single rooms. Boarding houses and rooming houses are SROs. Hotels are not SROs.

An SRO unit is one or two rooms and either lacks a complete kitchen and/or bathroom or shares them with other units. They are often furnished and rent is usually paid weekly or monthly.

Any alterations to an SRO must follow Single Room Occupancy regulations.

Include in your report:

  • If work was done

To report a Single Room Occupancy (SRO) being rented as a hotel room, use the Housing Used for Short-Term Rental (Vacation Rentals or Illegal Home-Sharing) page.

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