The Multiple Dwelling Law in New York is a state statute that sets minimum safety, maintenance, occupancy, and registration standards for residential buildings where three or more families live independently of one another. It applies automatically to any New York city with a population of 325,000 or more, and smaller municipalities can adopt it by local ordinance.1NYC.gov. New York State Multiple Dwelling Law In practice, that means the law shapes almost every aspect of apartment life in New York City, from window size and winter heat to who the city can call when something goes wrong.
Which Buildings and Cities It Covers
Section 3 makes the statute automatic in any New York city of 325,000 or more residents. Other cities, towns, and villages can opt in through a local law.1NYC.gov. New York State Multiple Dwelling Law Certain pieces of the law have their own, higher population thresholds: the serious-violation rent abatement in Section 302-a reaches only cities of 400,000 or more, and some enforcement provisions reference cities of one million or more.2New York State Senate. New York Multiple Dwelling Law 302-a – Abatement of Rent in the Case of Serious Violations
Section 4 defines a “multiple dwelling” as any building rented or occupied as the home of three or more families living independently of each other.3New York State Senate. New York Multiple Dwelling Law 4 A modest three-unit walkup counts. So does a single-family house that has been chopped into three apartments. Covered buildings fall into two classes:
- Class A dwellings are permanent residences, meaning apartment buildings, tenements, and maisonettes where occupants stay 30 consecutive days or more.
- Class B dwellings are transient housing such as hotels, rooming houses, and lodging facilities, where stays are typically shorter than 30 days.
The class matters. Class A buildings carry the strictest occupancy rules, including a flat ban on short-term use.3New York State Senate. New York Multiple Dwelling Law 4 Local law can go further than the MDL but not weaker, so New York City tenants and landlords operate under both the state statute and the city’s Housing Maintenance Code.
What Owners Must Maintain
The longest sections of the MDL govern physical conditions inside covered buildings. These standards apply regardless of a building’s age.
Light and Ventilation
Section 30 requires that every room, aside from bathrooms, water-closet compartments, and cooking spaces under 80 square feet, have windows totaling at least one-tenth of the floor area, with each window at least 12 square feet.4New York State Senate. New York Multiple Dwelling Law 30 – Lighting and Ventilation of Rooms A landlord who blocks a window, puts up partitions that cut off airflow, or turns a windowless space into a bedroom is violating the statute.
Heat and Hot Water
Section 79 fixes specific heating requirements. From October 1 through May 31, owners must keep indoor temperatures at a minimum of 68°F between 6:00 a.m. and 10:00 p.m. whenever the outside temperature falls below 55°F. At night, from 10:00 p.m. to 6:00 a.m., the minimum drops to 55°F when outdoor temperatures are below 40°F. Hot water must be supplied year-round. These rules are among the most commonly cited in older buildings, and losing heat in winter is immediate grounds for complaint.
Repairs
Section 78 places a broad duty on owners: every multiple dwelling, including its roof and the lot it sits on, must be kept in good repair. Tenants can be held responsible only for conditions they or their guests cause through willful acts or negligence.5New York State Senate. New York Multiple Dwelling Law 78 – Repairs A leaking roof, crumbling plaster, broken stairs, or inoperable locks all fall squarely within this provision, which is the backbone of most housing court repair cases.
Fire Safety
Section 53 covers fire escape access. Every living room rented to a boarder or lodger must have direct access to a fire escape without passing through a public hallway, and the access cannot be blocked by sinks, kitchen fixtures, or anything else. Iron bars or security gates on windows leading to fire escapes are unlawful unless they are an approved type that opens easily from inside. In cities of one million or more, the local fire commissioner approves such devices.6New York State Senate. New York Multiple Dwelling Law MDW 53 Common hallways and stairways must stay clear, and required fire-retardant materials must be maintained.
Owner Registration and Why It Matters
Section 325 requires every owner of a multiple dwelling to file a notice with the local housing department identifying the owner, the property, the building’s class, the number of apartments and rooms on each floor, and the number of families living there. If the owner is a corporation, the names and home addresses of its officers must be listed. Updated information must be filed within 30 days of any ownership change or officer replacement, and the obligation reaches anyone who takes control through legal proceedings, foreclosure, or inheritance.7New York State Senate. New York Multiple Dwelling Law 325 – Registry of Owner, Agent and Lessee
In New York City, registration runs through the Department of Housing Preservation and Development’s Property Registration Online System (PROS).8NYC HPD. NYC HPD Property Registration Online System A valid registration has two parts: a properly completed form filed with HPD and payment of a $13 annual fee, billed through the Department of Finance on the property’s Statement of Account each July 1.9NYC HPD. Register Your Property – HPD
Here is the consequence that catches landlords off guard. In cities of over one million (which means New York City), an owner who has not complied with the registration rules cannot recover rent until the registration is current. A tenant who stops paying can sit through an eviction case while the court checks the registry; if nothing valid is on file, the rent claim fails.7New York State Senate. New York Multiple Dwelling Law 325 – Registry of Owner, Agent and Lessee A $13 oversight routinely derails nonpayment proceedings worth thousands.
Short-Term Rentals in Class A Buildings
The MDL states that a Class A multiple dwelling “shall only be used for permanent residence purposes,” defined as occupancy by the same person or family for 30 consecutive days or more. Renting a unit in a Class A building for fewer than 30 days violates this rule unless a narrow exception applies, such as unpaid house guests of a permanent occupant or temporary occupancy while the resident is away for personal reasons like vacation, with no payment changing hands.3New York State Senate. New York Multiple Dwelling Law 4
New York City layered more restrictions on top through Local Law 18 of 2022. Anyone offering a short-term rental must register with the Mayor’s Office of Special Enforcement, and even registered hosts may rent lawfully only if they are physically present during the stay, host no more than two guests, and give guests access to the full dwelling unit. Booking platforms cannot process transactions for unregistered listings.10NYC Rules. Registration and Requirements for Short-Term Rentals Between the state statute and the local rule, most unhosted stays under 30 days in New York City are illegal.
What Tenants Can Do When a Landlord Won’t Comply
The law gives tenants real tools, not just complaint hotlines.
HP Proceedings
An HP proceeding is a Housing Court action that forces a landlord to make repairs and correct code violations. Before filing, tenants should write to the landlord and keep a copy. If nothing happens, the case can be started in the Housing Court for the borough where the building sits.11NYCOURTS.GOV. Starting a HP Proceeding to Obtain Repairs Calling 311 first to request an inspection creates a documented record. HP proceedings cover no heat, no hot water, vermin, structural damage, broken locks, and any other condition that violates the housing code.
Rent Abatement for Serious Violations
Section 302-a goes further. A “rent-impairing violation” is a condition that constitutes, or will soon constitute, a fire hazard or serious threat to the life, health, or safety of occupants, and the local housing department publishes the list of qualifying violations. If a rent-impairing violation stays uncorrected for more than six months, the owner is barred from collecting rent for any unit where the violation exists, for as long as the condition persists.2New York State Senate. New York Multiple Dwelling Law 302-a – Abatement of Rent in the Case of Serious Violations This is not a discretionary reduction. It is a statutory bar.
Court-Appointed Administrator
When conditions deteriorate to the point that an owner is clearly unwilling or unable to run the building, tenants or the city can petition for a court-appointed administrator under Article 7-A of the Real Property Actions and Proceedings Law. The court can appoint someone other than the owner to collect rents and use the money for necessary repairs under court supervision.12New York State Senate. New York Real Property Actions and Proceedings Law 778 – Appointment of Administrator Courts don’t grant this lightly, but in genuinely dangerous buildings it is the most effective remedy available.
Illegal Conversions
One of the hazards the MDL is designed to prevent is a building that has been carved into more units than it was approved for. A single-family home turned into three apartments without a new certificate of occupancy is an illegal multiple dwelling. So is a basement apartment that was never approved for habitation.
In New York City, the Department of Buildings investigates illegal conversion complaints through its Quality of Life Unit. Inspectors examine the property, can issue a vacate order if they find imminent danger, and can get a warrant with police assistance if denied access.13NYC.gov. Illegal Conversion – Buildings These units are especially dangerous because they usually lack the fire escapes, ventilation, and egress routes that the actual population requires. Tenants in illegally converted units still have legal protections, but the unit itself may be ordered vacated.
Penalties
Section 304 sets a tiered penalty structure. Most MDL violations are misdemeanors: a first offense carries up to $500 in fines, up to 30 days in jail, or both, and a second or subsequent offense for failing to correct the same violation can bring up to $1,000, up to six months in jail, or both. A separate, lighter track applies to violations of certain sections, including the registration requirement in Section 325. Those are classified as offenses rather than crimes, with a maximum fine of $50 for a first violation, $250 for a second, and $500 for a third or subsequent one, and no criminal record.14New York State Senate. New York Multiple Dwelling Law 304 – Penalties for Violations For registration lapses, the real cost is almost never the fine. It is losing the right to collect rent.