Pratt Center is a founding member of the Basement Apartments Safe for Everyone (BASE) campaign, which advocates for a legal pathway for converting New York City basements and cellars into safe, healthy, and affordable apartments. The campaign won the East New York Basement Pilot in 2016, and is currently focused on city and state policy reforms to permit and fund basement and cellar apartment conversions citywide. We provide technical assistance to the campaign with a focus on land use and zoning analysis, communications strategy, and policy advocacy. 

Advocates from BASE coalition stand together holding signs reading "Legalize Basement and Cellar Apartments" and "Make basement and cellar apartments safe" in bold lettering.
BASE Rally in Jackson Heights in March 2023

The intersecting crises of housing affordability, climate, and the COVID-19 pandemic add urgency to the need for safe and affordable housing for all, especially immigrants, people of color, and low-income workers. A crucial strategy is to legalize basement and cellar apartments in NYC’s existing stock of small homes.  A citywide basement and cellar conversion program, based on the East New York Basement Pilot, could potentially produce up to 200,000 new apartments benefitting almost every neighborhood in New York City. Current city and state policy, however, makes this almost impossible. 

After success in launching the Pilot and a commitment from Mayor de Blasio to expand it citywide, the program was defunded as part of budget cuts during the COVID-19 pandemic. The devastating floods of Hurricane Ida in 2021, in which 11 New Yorkers living in basement apartments lost their lives, highlighted the urgent need to make these apartments safe and legal. Our current work focuses on building the political will and community backing to fight for what we know is a vital tool for the City to overcome the myriad crises low-income homeowners and tenants face around housing stability.

Group of advocates holding signs at a press conference on the steps of City Hall
Advocates gathered with elected officials at City Hall in anticipation of new legislation creating an East New York Basement Apartment Conversion Pilot program.
Group poses on the steps of City Hall holding signs that read: "Basements Keep East New York Safe-Stable-Affordable", and "Basement Apartments=Affordable, Safe, Stabilizes Homeownership, Prevents Homelessness, Protects Tenants, a place to call home"
Members of the BASE coalition created signs reiterating the importance of basement apartments at a February 13 press conference in 2019.

Our ongoing work includes:

  • Serving as a member of the BASE Campaign steering committee alongside Chhaya CDC, Cypress Hills Local Development Corporation, Queens Legal Services, and the Center for NYC Neighborhoods. 
  • Ongoing technical analysis of zoning and building codes that impact the ability of homeowners to create legally recognized apartments. 
  • Representing the BASE Campaign on a statewide coalition creating legislation to allow for the construction of Accessory Dwelling Units across New York State
  • Providing communications and design support for the campaign, including the creation of flyers, presentations, and social media campaign content and strategy.

Contributions & Milestones

  • In March 2022, BASE launched its Platform for Basement Apartments, outlining five key pillars to create safe, legal, and affordable basement and cellar apartments citywide including: establishing a citywide basements apartment program, fully funding the East New York Basements Pilot, passing State legislation to remove barriers to creating accessory dwelling units in small homes, making it affordable and accessible, and making efforts today around climate resiliency and flood infrastructure. Pratt Center contributed research, policy analysis and strategy, and design to the development of the platform.
  • In early 2022, Pratt Center released the Basements Data Dashboard, a free interactive resource that helps legislators and advocates identify the potential opportunity for new basement and cellar apartments in neighborhoods across New York City.
  • Our 2021 report, New York’s Housing Underground: 13 Years Later analyzed unaccounted for basement and cellar apartments and found that they are predominantly in BIPOC communities with higher levels of rent burden and poverty than the citywide average. This report was an update to our 2008 report, New York’s Housing Underground.
  • From 2016–2018, we helped the Coalition for Community Advancement in East New York win a Basement Conversion Pilot through the neighborhood rezoning, then participated in a Task Force of City agencies and community-based advocates which crafted legislation creating the East New York Pilot 
  • Our 2008 report New York’s Housing Underground: A Refuge and Resource documents the neighborhoods with the greatest need and articulates some of the basic components of a successful policy in New York City.
BASE logo shows the word BASE within the outline of a house. Text on the outside reads, "Basement Apartments Safe for Everyone"

Project Status



  • Policy
  • Research & Analysis



  • Citywide