Zoning and land use
Cellar and basement apartments
A basement apartment can be lawful in New York City. A cellar apartment usually cannot, outside one legalization program. The line is measured from the curb.
Can a cellar or basement apartment be legal in New York City?
Quick Answer
What the building may be used for
Who does this land on?
Owners of one and two family houses and small multiple dwellings, buyers pricing a garden-level rental, and anyone marketing a below-grade unit.
What governs it?
- The Multiple Dwelling Law and the Housing Maintenance Code, which define basement and cellar by the position of the floor relative to curb level
- The construction codes, which set the minimum ceiling height, window area, egress and fire separation for a habitable room
- The Zoning Resolution, which decides whether the additional unit is permitted in the district
- The Administrative Code enforcement provisions, which treat an unauthorized below-grade unit as an illegal conversion
- Local Law 126 of 2024, enacted under Chapter 56 of the Laws of 2024, Part S, which added Multiple Dwelling Law Article 7-D and let the City create a basement and cellar legalization program in fifteen community districts rather than citywide
How does the process run?
- Measure honestly: establish the curb level and the position of the floor and ceiling, because the classification follows the measurement
- Check the certificate of occupancy for what is authorized below grade
- Test the space against habitable-room requirements: ceiling height, window area to the outdoors, light and ventilation, and a second means of egress
- Check the zoning district for whether the additional dwelling unit is permitted at all
- Where the space qualifies as a basement and can meet the requirements, file an alteration to legalize it and obtain an amended certificate
- Where it is a cellar, check the Local Law 126 program area first, and otherwise plan for a lawful non-residential use of the space rather than a legalization
- Address flood zone requirements, which restrict below-grade habitable space in the mapped areas
Where does it bite in a transaction?
- A two-family is bought as a three-family because the garden level is rented
- A listing describes a garden apartment that the certificate of occupancy shows as storage
- A complaint-driven inspection produces a vacate order for the below-grade tenant
- An appraisal capitalizes rent from a unit that cannot be legalized at any budget
What is the actual difference between a basement and a cellar?
It is a measurement, not a description. A basement has less than one half of its floor-to-ceiling height below curb level. A cellar has more than one half below curb level. The same room can be a basement on a sloping street and a cellar on a flat one, which is why the survey and the grade matter.
Has New York City legalized basement apartments?
Not citywide and not as of right. Local Law 126 of 2024, enabled by Chapter 56 of the Laws of 2024, Part S, which added Multiple Dwelling Law Article 7-D, created a basement and cellar legalization program covering fifteen community districts, open to units that existed before April 20, 2024, with the owner’s application due by April 20, 2029. What the program issues is an authorization for temporary residence, and it expires ten years after the date it is issued, so the legalization work has to be finished inside that window. The Department of Buildings begins accepting those applications once its rule is final. Outside the program a below-grade unit is still legalized unit by unit against the code requirements, so anyone told otherwise should ask which program and which lot.
Does a flood zone change the answer?
Substantially. Where the property is in a mapped flood hazard area, the construction codes restrict habitable space below the design flood elevation, and that restriction can foreclose a legalization that would otherwise be feasible on light, air and egress alone. It is checked early because it is dispositive.
What else should you read before you file or sign?
In the glossary
- Certificate of Occupancy (C of O)The Department of Buildings document that fixes a building's legal use and occupancy. Lenders and title companies read it to confirm the property c...
- Violation (cited against the premises)An agency record that a condition at a property does not comply with a code or rule. It attaches to the premises and follows the property through a...
- OATH Hearings DivisionThe City tribunal, OATH (formerly ECB), that adjudicates summonses from most New York City enforcement agencies. Unpaid or defaulted summonses beco...
- SurveyA surveyor's drawing of the parcel, its improvements and any encroachments. Lenders on houses and townhouses generally require a current one or a s...
- Letter of No ObjectionA DOB letter confirming the lawful use of a building constructed before Certificates of Occupancy were required. It stands in for a C of O on many ...
Zoning and land use
- Legalizing an illegal conversionExtra units the certificate of occupancy does not show are an illegal conversion. There are two honest exits: legalize the unit, or remove it and p...
- Accessory dwelling unitsRecent zoning text amendments opened a path for accessory dwelling units in parts of New York City. Whether your lot qualifies is a parcel-level qu...
- Changing the use on a certificate of occupancyA change in occupancy classification or use group needs an amended certificate of occupancy, even when no construction happens. Here is what that f...
- Buildings with no certificate of occupancyOlder New York City buildings can lawfully have no certificate of occupancy. A letter of no objection is how the City confirms the lawful use instead.
- Zoning due diligence before you signSix records answer almost every zoning question on a New York City property, and all six can be pulled before the contract rather than after the de...
The violation code
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Legal Disclaimer: This page is general information about New York practice. It is not legal advice, it does not account for the terms of any particular contract, building or transaction, and reading it does not create an attorney-client relationship. This is attorney advertising. Prior results do not guarantee similar outcomes.