Illegal Conversions

An illegal conversion is an alteration or modification of an existing building to create an additional housing unit without first obtaining approval from the New York City Department of Buildings.

Examples of illegal conversions include:

  • Using a property zoned for manufacturing or industrial use for residential occupancy;

  • Creating a housing unit in a building designated for manufacturing or industrial use;

  • Adding an apartment in the basement, attic or garage without obtaining approval or permits from the Department of Buildings; or

  • Creating a rooming house (single room occupancy) or dividing an apartment into single room occupancies.


Why are Illegal Conversions harmful?

Illegal conversions pose serious safety risks to residents and to the City’s first responders by creating potentially unsafe living conditions and not complying with Building and Fire Codes. They reduce a neighborhood’s quality of life by straining essential services, causing overcrowding and reducing the already-limited amount of industrial and manufacturing space necessary to support local businesses.

Your apartment/room could be illegal if you answer yes to any of these questions:

  • Is your bedroom in the cellar? (A cellar has at least half its height underground.)

  • Do you live in the attic?

  • Do you get electricity with an extension cord?

  • Do you lock your room with a padlock?


What to do if You Suspect an Illegal Conversion

If you suspect an illegal conversion call 311 to have a Buildings Inspector routed to the site to inspect the property. You can also check the legal use of a building by visiting the Department’s website and viewing the building’s Certificate of Occupancy through the Department’s Buildings Information System.


Report illegal conversion or alteration of a:


Report illegal use of a building:


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