Press Releases

Three Years Post-Sandy, Multifamily Housing in NYC and Other Urban Areas Remains Vulnerable to Flood

October 28th 2015

NYU Furman Center report illustrates challenges of floodproofing multifamily housing in New York City and other urban areas.

New York, NY: Three years after Superstorm Sandy devastated parts of New York City and the surrounding region, the housing stock in many urban coastal areas remains vulnerable to flooding, according to a report by the NYU Furman Center. The report illustrates the significant design and financial hurdles of retrofitting multifamily housing.

The report, Planning for Resilience: The Challenge of Floodproofing Multifamily Housing, released today, describes and maps the prevalence of multifamily housing in select flood-prone coastal areas.

"A significant share of the multifamily housing in urban coastal areas is older— constructed prior to the adoption of floodplain maps and regulations—and thus may not meet federal flood-resistant design and construction standards," said Jessica Yager, Deputy Director of the NYU Furman Center and author of the study.

Of the metro areas in the report, New York City's floodplain has the highest share of housing units in multifamily buildings, with 70% housing units in the floodplain in multifamily buildings (90% of which were constructed prior to 1983). Still, other coastal cities also have a significant share of housing units potentially at risk. Of the other metro areas studied, Miami has largest share of units in the floodplain in multifamily buildings (37%), followed by Baltimore/Washington D.C. (33%), Boston (23%), Tampa (23%), Philadelphia (16%), Houston (16%), Providence (14%), and Virginia Beach (13%).

"Retrofitting a multifamily building to meet FEMA standards can be expensive and difficult to design and finance, particularly for buildings serving low- and moderate-income households," said Yager. "As a result, buildings that provide affordable housing may remain at risk."

The report notes that FEMA regulations and flood insurance rates will be a driving factor shaping what retrofits building owners undertake, but it also outlines concrete actions state and local policymakers can take to help promote longer- term resilience planning by multifamily building owners.

Summary of Findings:

  1. Many major U.S. urban areas have a significant share of housing units in multifamily buildings in their floodplains.
    • New York City: The vast majority of housing units in New York City's floodplains (over 70%) is in multifamily buildings. The vast majority of these (over 90%) were built prior to the adoption of floodplain maps in 1983.
    • Share of multifamily housing stock in 100- and 500-year floodplains: The share of multifamily units as a share of total units in the 100/500-year floodplains varies significantly across the other metro areas included in this study: Miami (37%), Baltimore/Washington D.C. (33%), Boston (23%), Tampa (23%), Houston (16%), Philadelphia (16%), Providence (14%), and Virginia Beach (13%).
    • After New York City, Miami is most at-risk: Of the jurisdictions we analyzed, Miami has both the second largest number of multifamily units in the floodplains (over 400,000), and the second largest share of units in the floodplain that are in multifamily buildings (37%).
  2. FEMA's all-or-nothing compliance rules present significant design and financial challenges, leaving multifamily building owners vulnerable to expensive flood insurance premium hikes.
    • Elevate everything: In order for a residential building to comply with FEMA regulations, all building systems and living space must be moved above the Base Flood Elevation (BFE). Multifamily buildings often have residential units, common areas, or mechanical systems located on floors below the BFE. Reconfiguring these buildings can be expensive and complex.
    • Financial challenges of retrofitting: Flood retrofits can be expensive and hard to finance, particularly in multifamily buildings serving low- and moderate-income households. Government-subsidized buildings may face additional hurdles because of the regulatory requirements that govern them.
  3. While FEMA regulations and flood insurance rates will be a driving factor shaping what retrofits building owners undertake, state and local governments can take steps to help multifamily buildings adapt for resilience.
    • Align local regulations with resilience goals: Local governments can make sure that local zoning and building codes provide owners with flexibility to implement smart resilience strategies. This might include forward-looking regulations that incentivize buildings to elevate higher than what is currently required by FEMA to take into account the risk of future sea level rise.
    • Help owners understand and plan to mitigate flood risk: Local governments can provide the technical resources and information needed to plan.
    • Help property owners fund retrofits: Local governments should encourage owners to include resilience upgrades in their long-term capital plans for their buildings, while also looking for ways to help fund resilient retrofits directly through community investment groups or philanthropic organizations.

For more information, contact: Shannon Moriarty, [email protected], w 212-998-6492, c 617-824-0069

About the NYU Furman Center

The NYU Furman Center advances research and debate on housing, neighborhoods, and urban policy. Established in 1995, it is a joint center of the New York University School of Law and the Wagner Graduate School of Public Service. More information can be found at and @FurmanCenterNYU.