Averting Crisis

The scale of the deficit provides insights into the necessary scope of zoning reform and additional policies needed to address housing and climate adaptation needs in the study area. By contextualizing this gap at the local level, the report also documents relevant policies and planning tools to be leveraged and prioritized based on the built environment, infrastructure, and flood hazard conditions of neighborhoods and localities across the region.

Policymakers and planners usually focus on population growth and affordability when deciding how many homes a community or region needs. But what if the land we plan to build on is prone to flooding? These climate-related factors must be integrated into our housing needs assessments to ensure we’re building safe, resilient, and sustainable communities for the future.

By 2040, around 77,300 acres of residential-zoned land in New York City and the study area suburbs – or 10.5% of such land – may face flooding. Suffolk County has the largest acreage of residential districts exposed to future flooding, with approximately 37,800 acres or 10% exposed. New York City follows, with approximately 20,900 acres of residential districts exposed to flooding, representing 15% of the city’s total. By 2040, up to 10% of the people in the study area might reside in areas prone to future flooding. With more than 1 million people at risk in the urban core and regional downtowns, 63% of the potentially affected population could be living in higher-density urban areas. An additional 1 million jobs could be situated in zones vulnerable to future flooding, with approximately 726,000 in the urban core and regional downtown regions areas. Hazards include storm surge, riverine flooding, and sea level rise projections based on New York Panel Climate Change (NPCC) 16″ of sea level rise by 2040 (75th percentile).

Flood Loss

Flood exposure represents the potential for damage based on a property’s location and vulnerability to flooding. In contrast, flood loss refers to the actual damage or financial loss incurred due to a flood event. For residential loss to occur, exposure must be frequent and/or severe enough to result in significant damage. Aside from the degree of exposure, socioeconomic conditions, building regulations, and insurance policies can influence whether a housing unit is lost.

According to the RPA estimates, communities in New York City, Long Island, and Westchester (the study area) could lose up to 82,000 housing units due to permanent, chronic, and coastal flooding, doubling to 160,000 by 2070. These estimates are focused only on flooding, but a more complete assessment should have a multihazard perspective (e.g., extreme rainfall or wildfires).

Housing losses by the year 2040 could occur in 78% of municipalities in the suburbs (124 out of 159) ) and 60% of community districts in New York City (30 out of 55). The most flood-prone areas where the largest losses may occur are the towns of Hempstead, Babylon, Islip, Brookhaven on Long Island and cities in Westchester County along the Long Island Sound. Each could lose over 6,000 units by 2040. Neighborhoods in New York City like Rockaways, South Ozone Park, and Canarsie could also be significantly impacted, with each area losing over 2,000 units.

For this analysis, RPA considered lost housing resulting from two types of hazards: sea-level rise and storm-related flooding.

Sea-level rise refers to gradual, permanent, or chronic inundation. Using the projections developed by the New York Panel on Climate Change (NPCC) and a bathtub model, RPA calculated the number of housing units exposed to monthly high tides and considered them lost. We developed a range of estimates based on the NPCC’s 25th and 75th percentiles and projections for 2040 and 2070.

In addition to sea-level rise, RPA also factored storm-related flooding, which refers to acute, random, and temporary flooding. We used FEMA’s basic Hazus-generated depth grids for damage analysis over multiple return periods (10, 50, 100, and 500-year storm events). When a portion of a building was likely to receive substantial damage (>50%) in the time interval, RPA considered them destroyed. We assumed 50% of substantially damaged homes would be replaced under the low scenario and 0% replacement of substantially damaged homes under the high scenario. As with the sea-level rise estimates, we produced projections for 2040 and 2070.

Current Housing Needs

RPA estimates that about 362,000 additional housing units are necessary to meet immediate needs in New York City, Long Island, and Westchester. To define current housing needs, RPA considered vacancy rates (for rent and sale), overcrowded households, and temporarily sheltered populations.

• Low vacancy rates are strongly associated with higher costs for both renters and prospective home-owners. To address the region’s low vacancy rates, an estimated 132,000 units are required. In New York City, apartments available for rent dropped to a minuscule 1.4% in 2023. Vacancy rates in the Metro area range between 1% for sale and 2.9% for rental units. Respectively, these figures are well below the 3.5% and 5% rates that represent a well-functioning buyer and rental housing market.

• Overcrowded units represent roughly half the current needs in the study area. According to census estimates, 370,800 households in the study area are overcrowded, 314,000 in NYC (85% of the share). Overcrowding also disproportionately affects workers and low—and moderate-income families, which provides insights into the scale of the current need for affordable housing.

• Homelessness is also strongly connected to market conditions and, as such, serves as another critical indicator to consider when assessing housing needs. There are approximately 150,000 homeless people within the study area; 130,000 are in the NYC shelter system, and over 20,000 live on Long Island and in Westchester County. In recent years, homeless families have grown as a share of the overall sheltered population, now accounting for more than ⅔ of the temporary sheltered. Permanently housing this population would require between 40,000 and 50,000.

The following maps show the distribution of housing needs by NYC neighborhoods and for suburbs in the study area. By contrasting needs by category, the maps also show how each locality has a unique housing profile, with the mix between current, prospective, and flood loss-related needs varying depending on location. Generally, suburban localities have a profile where prospective housing needs represent a more significant proportion of their total. Municipalities in Long Island show a higher share of flood loss-related needs when compared to New York City and Westchester counties. In contrast, areas in the urban core show a profile where the proportion between current and prospective housing needs is more even.

As communities in America confront the pressing issues of high housing costs, underutilized land, and deteriorating neighborhood conditions, an increasing number of local officials are acknowledging that zoning regulations contribute to these problems – and that zoning reforms can help solve them. Even though villages, towns, and locally elected officials across the region may seem to have little control over global emission trends and their related hazards, they greatly influence zoning regulations. These local stakeholders hold a key policy lever in maintaining zoning rules that control where we can build or retreat from, with significant implications for climate mitigation and adaptation efforts. In aggregate, the existing land use rules remain overly prescriptive, disjointed, and insufficient to address the challenges of a regional housing market facing a severe deficit and increasing flooding exacerbated by climate change.

Housing Deficit

Using a first-of-its-kind database of zoning laws produced by the National Zoning Atlas, RPA estimated the zoning development capacity within Long Island and Westchester. We also estimated the development capacity of New York City, including the recent reforms implemented under the City of Yes Housing Opportunity initiative and using the city’s Primary Land Use Tax Lot Output (MapPluto) dataset. We then produced a gap analysis by comparing this build-out against housing needs, including prospective and flood loss-related.

The analysis reveals that the current residential zoning development capacity allows less than half (45%) of the total housing needed by 2040, leaving a net deficit of approximately 680,000 units. To meet both current and future needs, including losses related to flooding, zoning development capacity would need to increase by a factor of 2.2 (the ​“deficit ratio”).

The following table and maps illustrate the distribution of the housing deficit across community districts in New York City and suburban localities within the study area. Although neighborhoods in the urban core typically have greater zoned capacity, the housing needs in these areas are also significantly larger. Consequently, the net deficit is concentrated in the urban core. However, the spatial distribution of the deficit ratio (number of times zoned capacity has to increase to meet housing needs) highlights a critical need to significantly increase capacity in the inner suburbs, particularly in Nassau County, and in some instances by a factor much higher than current zoning regulations.

This gap is based on the potential build-out under current zoning, which could allow as many as 580,000 housing units on an as-of-right basis. This includes 390,000 units in New York City and 190,000 across Long Island and Westchester. The estimates also assume that all underdeveloped properties are built to the maximum allowed density. The buildout capacity was based on parcel-level analysis and applicable zoning regulations, including recent reforms implemented in New York City under the City of Yes Housing Opportunity initiative.

Zoning and Residential Land

As a whole, zoning in the region is permissive for sprawl but very restrictive for multifamily development. Suburbs (particularly those in Long Island) prohibit multifamily development within most zoning districts. Single-family residences are permitted on an as-of-right basis on nearly all residentially zoned land: 100% in NYC, 98%, and 96% in Long Island and Westchester, respectively. While multifamily buildings with four units or more are allowed on 61% of New York City’s residentially zoned land, they are allowed on less than 5% of the land in the suburbs. Despite their proximity to New York City, Suffolk and Nassau Counties ban multifamily residential development on 96% and 93% of their residential land, respectively. Restrictive zoning that does not allow for multifamily housing—even moderately sized—makes it much more challenging to address the housing crisis experienced in the region and beyond.

New York Suburbs: Zoning Capacity Analysis

RPA estimates that as-of-right residential zoning in Long Island and Westchester allows a potential build-out of approximately 190,000 units. This assumes that all viable underdeveloped properties (i.e., soft sites) are built to their maximum allowed density.

To arrive at this estimate, RPA first linked the NZA zoning attributes to parcel-level data, starting with 470,000 parcels in the suburbs. These parcels were based on non-residential and residential underdeveloped lots, then subjected to a multi-step screening process to identify likely development sites (i.e., soft sites). The screening involved several tests based on zoning regulations and parcel attributes (e.g., does the parcel meet the minimum lot size requirement? Is the allowable density much larger when compared to the existing?). Of the initial 470,000 parcels evaluated, approximately 49,500 passed the tests and were considered part of the build-out calculation.

For the parcels that remained after the screening process (49,500 lots), we calculated the maximum number of dwelling units (DUs) allowed on an as-of-right basis, as determined by the corresponding building treatments. For multifamily districts (allowing four or more units), we used lot size information, allowed DUs per Acre, and maximum Floor Area Ratio (FAR) to estimate the maximum number of units allowed per site. In addition, we conducted a series of building envelope studies based on the bulk control regulations applicable to multifamily districts (four or more units). Wherever necessary, we adjusted residential density to reflect instances where the maximum of DUs per Acre was not achievable due to other constraints and dimensional criteria (i.e., lot coverage or height limitations). The residential build-out estimates were produced on a parcel level and then aggregated to their corresponding locality.

Achieving meaningful housing and resilience goals will require regional thinking. However, the policies and tools needed to advance these objectives will be implemented in specific neighborhoods and localities. Therefore, understanding localized characteristics related to potential growth and flood risk while maintaining a regional perspective will be crucial for both minimizing exposure to flood risk and reducing the housing deficit. This chapter identifies four types of communities – Smart Growth Haven, Resilient Refuge, Adaptive Retreat, and Stable Support – and offers recommendations for goals and strategies for each.

Some places already have infrastructure and built-form conditions that encourage growth in compact, walkable, and transit-oriented development, while others do not display these characteristics. Certain locations have relatively low exposure to future flooding, whereas others are highly vulnerable. By comparing local attributes associated with flood risk and smart growth potential. RPA defined four ​“area types,” each with a distinct combination of the two variables. These four area types can be used to categorize the various neighborhoods and localities throughout New York City and its suburbs, identifying respective policy priorities to address regional needs.

The following area types do not represent forecasts or prescribe policy. Whether a neighborhood or locality falls into any of these categories will depend on the choices made in the coming years and decades, the extent of collaboration between public and private entities, evaluation of needs and acceptable degree of risk, and the level of coordination at the local, state, and federal levels. These types are based on the challenges and opportunities presented by a location’s built and natural environment and provide an overview of potential planning interventions and policies aimed at minimizing risk and addressing the housing deficit. Depending on conditions, these policies and programs could be deployed across the full range of growth and risk profiles depicted in the diagrams. However, the following policies should not be considered exclusive to a given type. Depending on conditions, these policies and programs could be deployed across the full range of growth and risk profiles depicted in the diagrams.

Goals and Policy Priorities:

• Housing need assessments: Evaluate and determine current and future housing requirements at the local and regional levels. Consider immediate needs such as overcrowding, temporary sheltered population, and vacancy rates. In addition, evaluate future demand resulting from household formation, dilapidation rates, and flood loss.

• Housing action plan: Establish goals and prioritize actions based on comprehensive need assessments. Identify land use actions, policy changes, and site-specific interventions to facilitate growth in proportion to regional housing needs.

• Zoning capacity: Expand residential zoned capacity proportionately to regional housing needs and future demand.

• Housing types and uses: Broaden the geographic scope of zoning districts that allow for multifamily development and residential middle-density typologies.

• Transit-Oriented Development: Promote TOD and other forms of infill by utilizing special districts, overlays, and building treatment regulations in relation to transit proximity.

• Approval processes: Expedite public and environmental review procedures for multifamily and infill development.

• Bulk and use regulations: Implement flexible zoning and land use regulations that govern building treatments, density, parking requirements, and other dimensional criteria (lot coverage, setbacks, height, etc.).

• Financing and funding: Prioritize and leverage financing and discretionary funding programs (e.g., the New York Pro-Housing Community, Downtown Revitalization, and NY Forward programs) to promote sustained growth,

• Affordable housing: Encourage affordable housing by implementing inclusionary zoning and other strategies.

• Infrastructure: Make sustained investments to enhance and expand the capacity of infrastructure, services, and utilities.

Resilient Refuge (High Risk - High Growth)

This category identifies areas with compounding adaptation needs: significant risks from future flooding and a high potential for smart growth development. These locations will require comprehensive planning to promote growth while protecting existing infrastructure and communities through flood-resilient design and other adaptive measures.

Goals and Policy Priorities:

• Housing need and climate risk assessments: Assess and quantify potential housing needs and climate risks. Establish goals and actions based on forward-looking needs assessments within a regional context.

• Zoning capacity: Expand residential zoned capacity proportionately to regional housing needs and demands.

• Capital budgeting: Align budget scope and priorities with growth and adaptation needs. Prioritize and secure community investments and funding where growth can be encouraged and accommodated. Improve and expand infrastructure and services, such as transit, sewers, and resiliency projects, to address current and future needs.

• Special districts: Develop districts with incentive-based zoning (e.g., Waterfront Access Zoning), assessment fees, or tax increment financing mechanisms to help pay for adaptation projects and infrastructure maintenance.

• Building standards for resilience: Update codes to ensure that buildings can withstand and recover from adverse events and extreme weather while reducing exposure in surrounding areas.

• Shore-based measures: Protect the coast from erosion, flooding, sea level rise, and damage to coastal communities and infrastructure. Depending on the location and specific needs, these measures can include hard engineering solutions like sea walls, revetments, land elevation, and levees, or soft engineering techniques and natural processes, such as beach nourishment and the restoration or creation of dunes and wetlands.

• Sewer systems: Expand or retrofit the capacity of the sewer network, pumping stations, and other structures that collect, move, and treat wastewater and stormwater.

• Green infrastructure: Expand natural systems and engineered solutions into the built environment to manage stormwater, mitigate coastal flooding, and enhance climate resilience.

Resilient Refuge locations face the dual challenge of managing significant climate risks while accommodating substantial housing growth. To effectively tackle this complexity, these areas must prioritize policies that integrate climate resilience with housing development. Comprehensive risk and needs assessments should be conducted to inform strategic investments in resilient infrastructure and development. Capital budgets and reliable sources of resilience funding should align with both growth and adaptation needs, providing targeted support for vulnerable communities. These areas can lead efforts at the intersection of climate change and the housing crisis, serving as examples of sustainability.

Key policy levers to encourage housing growth include upzoning, creating special districts or overlays, and offering development incentives. Integrating affordable housing into new developments will benefit current residents and vulnerable populations. Environmental design standards should be developed to incorporate sustainable systems into buildings.

Investing in public transit and existing infrastructure is vital for maintaining essential network services. Shore-based measures, along with storm surge barriers in some cases, will be critical for reducing flood risks. Strategically designing green infrastructure and open spaces can effectively manage flooding while enhancing urban landscapes. These improvements should be implemented alongside or in anticipation of residential development.

Adaptive Retreat (High Risk - Low Growth)

This typology represents neighborhoods and localities that are highly exposed to future flooding and have relatively low potential for smart growth.

Goals and Policy Priorities:

• Managed retreat: Implement strategies that support the purposeful, coordinated, and voluntary movement of people and residential buildings away from risks over time. This may involve the movement of individuals, infrastructure (e.g., building or road), or community. Include incentives that keep residents within the same town or county. Areas highly exposed to flooding can be reprogrammed to facilitate low-risk uses, such as community centers and open spaces with active and passive recreation options.

• Buyout programs: Implement programs for voluntary acquisitions that require permanently removing properties from high-risk areas. After a structure is removed, strict land use management measures are typically imposed. Develop programs to support low-income homeowners and renters, including bonuses to keep residents within the town or county. Create buyout programs for both single- and multi-family properties that are effective, equitable and address the needs of both owners and renters.

• Special districts/flood risk zones and overlays: Create districts where flood risk zoning/building codes and development standards apply. Facilitate transfer of development rights (TDRs) using special districts or credits.

• Shore-based measures: Safeguard the coastline against erosion, flooding, rising sea levels, and damage to coastal communities and infrastructure. Leverage opportunities to restore the coastal edge, delivering natural protective benefits and economic advantages of ecotourism. Facilitate wetland migration where suitable.

• Green infrastructure: Expand natural systems and engineered solutions into the built environment to manage stormwater, mitigate coastal flooding, and enhance climate resilience. Pair widespread green infrastructure with hard infrastructure to aid in long-term resiliency as well as add a sense of ​“place” and nature.

Adaptive Retreat communities in this category must prioritize addressing risk and safety concerns related to flood hazards. Instead of focusing solely on disaster recovery, they should reframe timelines and design for long-term adaptation. Localities should utilize land use authority to discourage residential development and assist homeowners and renters in relocating away from flood hazards. Areas highly exposed to flooding can be reprogrammed to facilitate low-risk uses, such as community centers and open spaces with active and passive recreation options. Transparent and consistent communication between authorities and residents is essential for equitable planning within adaptive retreat areas.

Proactive movement away from hazards can be achieved through acquisition programs, managed retreat plans, special districts and overlay zones, and, in cases of very serious risk, using eminent domain. Managed retreat plans should comprehensively understand which specific areas of a locality are at risk and which areas could be targeted for growth, ideally including incentives to retain residents within the locality. Special districts/flood zones and overlays can facilitate the transfer of development rights and establish zones where strict building codes, development standards, and zoning restrictions apply. Applicable ranges of risk should be accurately conveyed to homeowners and developers through the stringency of building codes and the cost of property insurance to deter development in higher-risk areas.

In addition to relocating from hazards, these areas must also focus on mitigating future risks. Shore-based strategies and green infrastructure can create opportunities to restore a coastal or riverine edge that offers both ecological benefits and flood protection. Residents who choose to remain should not experience a decline in their quality of life. The transformation of these areas into regional open spaces or park networks centered around ecotourism should be considered.

Stable Support (Low Risk - Low Growth)

The Stable Support category encompasses areas with low levels of future flood loss and low potential for smart growth development. These areas can benefit from targeted interventions to enhance livability and sustainability while avoiding sprawl through adaptive reuse and middle-density buildings.

Goals and Policy Priorities:

• Adaptive reuse: Facilitate mixed-use development and adaptive reuse of underutilized/vacant properties, whether commercial, vacant, or parking lots. Facilitating this can also help compatible uses to be near each other and for housing to be added, especially along existing commercial or transit hubs.

• Middle density: Gradually increase housing density in existing neighborhoods, adding more homes (e.g., Accessory Dwelling Units (ADUs), duplexes, and triplexes) without disrupting the neighborhood’s character.

• Housing fund contributions: Create funds to incentivize affordable housing that can be credited elsewhere. Create funding obligations to subsidize non-profit and for-profit developers to build or substantially rehabilitate multi-family apartments within a certain jurisdiction.

• First- and last-mile connections: Improve the final segment of a person’s journey between the main transit system (e.g., the bus or train network) and the rider’s final destination.

• Fair share: Adopt legal requirements for municipalities to provide a fair share of affordable housing for their region. Calculations are usually based on population size, jobs, income, and underdeveloped land. Allocate and build affordable housing units for vulnerable populations and various income levels.

Stable Support communities should prioritize land-use changes along existing transit and commercial corridors to encourage mixed-use development, increase density, and enhance connectivity within their built environment. The most appropriate approach for these areas is incremental development at a moderate density paired with gradual transit improvements.

Specific policy tools, such as adaptive reuse , middle density , parking reductions, fair share housing allocations, and contributions to housing funds, are recommended to support this incremental housing development approach. Additionally, localities should concentrate on expanding and enhancing the connectivity of public transit and active transportation networks to improve accessibility and mobility.