We must continue to expand housing opportunities for people of all incomes throughout the entire region, with a heavy focus on policies that will combat historical and existing discrimination. However, simply building our way out of this housing shortage will be challenging. Major new affordable multi-family buildings are part of the solution, but ultimately we cannot meet our housing growth needs solely through large new developments.

Fortunately, we don’t have to. Done thoughtfully, every municipality can create more housing simply by allowing more flexibility within the context of existing land use patterns.

Not all of these new homes would necessarily mean new people. Some would allow extended families to live in more comfortable situations, by having separate units for grandparents, older children or others currently living together in a single-family house. Others would allow for upgrades to legal dwelling units for people currently living in units which don’t meet code compliance - which would also help ensure that these units are safe. All would be valuable additions to housing choice in neighborhoods and the housing supply of the region as a whole.

We can achieve the creation of these additional homes through policies that can be implemented by the states and by local communities through both legislation and local zoning changes, by addressing technical issues to unlock this ​“hidden housing,” and by addressing the misconceptions that can undermine productive dialogue around this issue in local communities.

The Effects of our Housing Shortage

For residents throughout the region, but especially for people of color, buying a home is increasingly out of reach, commutes continue to get longer, and opportunities to move up the economic ladder are declining. For the most vulnerable in our region, those opportunities have been decimated by the pandemic and ongoing economic crisis. Younger people and families with scarce opportunities to rent or buy are being pushed out, and empty nesters and seniors looking to downsize or move have nowhere to go in their hometowns. Between 2000 and 2015, the number of households in the region considered to be rent burdened increased by 16 percent. Households making less than $25,000 were pushed out to places poorly served by transit and with scarce amenities.

Without new affordable homes, high-priced neighborhoods and towns have become wealthy and overwhelmingly White enclaves, inaccessible to the teachers, firefighters, home healthcare workers, landscapers, caretakers, and many others who commute to these areas for work.

ADUs and Conversions

New buildings are one needed part of this solution. In RPA’s 2017 report, Untapped Potential, we detailed possibilities for building 250,000 new homes in complete neighborhoods near commuter rail stations. But we cannot meet our housing growth needs solely through new construction. We also need to work with the buildings we have.

Regionwide

1. Promote ADUs and Conversions through New York, New Jersey, and Connecticut State Legislation
   Each state in the region should establish policies that encourage municipalities to implement local regulations that enable ADUs and conversions. These policies should specify the minimum rights of owners to create accessory apartments and include recommended guidelines and assistance to municipalities. In some cases, and with the proper oversight, these new units could contribute to local fair share obligations required by state law.
2. Make it Easier to Legalize and Construct ADUs and Make Conversions through Zoning Code Changes and Local Ordinances
   With or without state policy, municipalities in our region should update their zoning and other relevant local ordinances to make it easier to create ADUs and conversions. Incentives for good design and accessibility should be included, and strict standards on things like occupancy or dimensional criteria of ADUs should be relaxed. Regulations that require large lots should also be minimized.
3. Create More Flexible Parking Requirements
   Parking standards can make or break ADU and conversion policies. In neighborhoods close to transit, off-street parking requirements should be minimized, and in most cases, on-street parking on public rights-of-way should be considered as a viable option to accommodate ADUs and conversions.
   
4. Provide Technical Assistance, Financing, and Information
   Municipalities should work to create programs that provide assistance for constructing ADUs and making conversions by simplifying technical language and streamlining approvals. Statewide financing programs, especially targeting senior citizens, should be should be prioritized.

New York City

1. Allow Housing Conversions and ADUs in NYC by Eliminating Zoning Requirements that Exclusively Require Large Detached Single-Family Dwellings
   Zoning districts R1, R1-1, R1-2, R2, R2A, and R2X only allow large detached single-family dwellings (or community facilities). All other types of uses are prohibited. Permitted land uses in these zones should be expanded to include two-family dwellings.
   
2. Reduce Multi-Family Consolidations
   The flip side of encouraging more flexible use of single-family homes is discouraging the conversion of multi-family housing into one single, large house. While it is difficult to legally prohibit these types of consolidations, they should continue to be treated as the previous multi-family buildings for property tax purposes and other disincentives through building or zoning codes could also be explored.
3. Support NYC’s Basement Apartment Program Expansion on a City-Wide Level, and Look for Opportunities for Other Ways to Add ADUs
   In early 2019, NYC signed into law a pilot program that modifies code standards and offers low or no-interest loans that facilitate safe basement apartment units. While NYC had initially announced it would expand this program, it has instead recently been eliminated due to upcoming budget cuts. This program needs to not only be retained, but expanded citywide. In addition, other reforms to laws and building codes should be explored in order to ease not just conversions of basements, but attic, garage and other space conversions that could still meet safety standards.
4. Rethink Off-Street Parking Requirements for Two- and Three-Family Homes
   Even when allowed by zoning, additional off-street parking requirements often make ADUs and conversions impossible. Especially near transit, off-street parking requirements for added units should be modified.

Within our region and beyond, land use and both racial and economic segregation are deeply intertwined. The tri-state region allocates a disproportionate amount of land towards large single-family detached houses. The share of the total housing stock based on this housing typology is also a metric that is heavily correlated with race and ethnicity.

This is true even in areas well suited for denser transit-oriented development (TOD) where historical investments and ongoing capital commitments have been made towards transit infrastructure. Such imbalance in residential land use is not a coincidence, but the physical manifestation of accumulated policy and planning decisions that have perpetuated housing discrimination and segregation.

This is not only a failure to properly utilize our investments in infrastructure, but also a clear manifestation of a spatially segregated region that increases commuting times and stifles economic growth.

Both near and far from transit, predominantly White municipalities have self-segregated through various ways, but a key strategy has been creating exclusionary zoning rules where the only permitted residential uses are large single-family detached houses. When examining the housing stock for each of the 782 municipalities in our region that have control over their land use, one can observe that the share of single-family detached units increases in areas where spatial segregation by race, ethnicity, and income is starker. For example, municipalities where more than 90 percent of the housing stock is provided in the form of single-family detached units, the percent of the White population is 86 percent, with Black and Latinx representing less than 2 and 6 percent of the population, respectively.

Allowing the housing typologies presented in this report, accessory dwelling units (ADUs) and conversions from single-family to multi-family homes, are by no means a silver bullet solution to either racial segregation or to our housing affordability crisis. A true change of course will require comprehensive policies and significant changes in leadership. However, allowing ADUs and multi-family conversions are a necessary and incremental step in the right direction, as part of a bigger puzzle where multiple strategies need to be advanced. By implementing policies and programs that promote ADUs and conversions as soon as possible, we will be in a better position to address many of the physical and institutional barriers we have created and ensure everyone has the opportunity to live a full and healthy life.

This report outlines strategies to help meet the demand for more homes in our region and more housing choice in areas that are largely comprised of single-family homes. It focuses on two main options for tapping into this new housing: accessory dwelling units (ADUs) and conversions.

Accessory Dwelling Units (ADUs)

Typologies

ADUs and conversions can come in various shapes and sizes. Often, ADUs make use of existing structures in the yard of single-family homes such as detached garages and sheds. Attics, basements, or attached garages can also be retrofitted to create an ADU or an additional dwelling unit in the form of a duplex or triplex.

Attached ADU example

Impacts of ADUs and Conversions

Like all new housing, ADUs allow for more people, and need the proper urban infrastructure to support them. Concerns over traffic, waste management, water and sewer systems, and schools are often raised when debating new housing of all sorts, and these concerns need to be addressed on a local level through proper upgrades to these infrastructure systems to accommodate additional people. Adding to the property tax base, which ADUs and conversions do, helps pay for these as can increased assistance from counties or states for municipalities which allow for these additional housing opportunities.

One of the best ways to reduce the impacts that new housing can bring is to take advantage of already existing infrastructure capacity. And consistent findings demonstrate that the cost of infrastructure and administering services increases in direct proportion to how far apart homes are spaced. Because of this, ADUs and conversions are one of the ways to add housing that is less impactful to the existing municipal infrastructure. While the amount of dwelling units increases, the amount of buildings does not. Waste pickup does not need to expand its routes to new addresses. New water and sewer extensions do not need to be built. As a result, ADUs and conversions are one of the smartest and most sustainable paths for meeting our housing needs.

Unauthorized ADUs and Conversions

A new ordinance in Westchester

In November 2019, the Westchester County Department of Planning approved a model ordinance for ADUs. The main goal was to create new housing units while maintaining the look and scale of single-family neighborhoods. Other benefits include the efficient use of existing housing stock and infrastructure, environmentally-friendly housing choices and smaller associated carbon footprints, responding to changing family needs, and providing housing for seniors and persons with disabilities.

With the exemption of the owner-occupied requirement, the model ordinance set a range of reasonable criteria in a flexible enough framework. This will likely promote a substantial amount of ADU creation without greatly affecting the built environment of single-family neighborhoods. The ordinance makes a distinction between accessory apartments and accessory cottages. Both are smaller secondary homes located on the same lot as the primary dwelling. The ordinance imposes a limit of one ADU per lot, as well as an owner occupancy requirement (living either in the ADU or primary dwelling). While ADUs are exempt from residential density and parking standards, they still have to comply with height restrictions, maximum lot coverage thresholds, and yard setbacks. The ordinance also provides some general design considerations for location of entrances and exterior stairs. Ultimately, each municipality will have to adapt this model code to their local circumstances and existing local zoning.

In the New York metropolitan region, public transit infrastructure is the lifeblood of the economy, connecting people with jobs and homes. Nearly 12 million people live within a 60-minute commute of Manhattan’s central business district or within 30 minutes of the other most populous municipalities in our region.

While housing supply has increased in NYC and around some of the region’s job centers outside the urban core over the past decade, many transit-served communities have been slow to embrace creating more housing. ADUs and conversions are an exciting opportunity to unlock the untapped potential that exists in many transit-served communities to create more homes for more people without major new construction on single-family lots and within existing buildings.

The economic, environmental, and social benefits of transit-oriented development (TOD) are extensive and well documented. Our region’s strongest markets are in transit-served locations, consistent with regional and national trends demonstrating demand for homes and experiences in walkable, mixed-use places with access to public transportation. Restrictive zoning that prohibits new homes in transit-served communities is exacerbating our region’s housing affordability crisis, stifling economic growth, and perpetuating segregation. Instead of restricting housing development, municipalities should be actively seeking solutions that enable more housing to be created. In particular, municipalities in our region that have rail stations that provide access to employment into Manhattan’s central business district within 60 minutes or access to our region’s other job centers within 30 minutes are prime candidates for enabling more housing.

Recommendations

1. Promote ADUs and Conversions through NY, NJ, and CT State Legislation

Each state in the region should establish policies that provide guidelines for municipalities in the use of their local authority to regulate ADUs and conversions. State legislation should create a framework that establishes minimum standards and encourages municipalities to implement regulations that enable ADUs and conversions.

These state acts should be aimed at providing incentives that encourage local municipalities to enable this housing. Such policies would specify the rights of property owners and the powers that municipalities may exercise in regulating this type of housing. This may include but should not be limited to recommended guidelines for parking, owner occupation, design review, and other considerations. While maintaining local land use control, state policy should prohibit localities from regulating ADUs or conversions in ways that violate the intent of the act. If local regulations are found to be excessively restrictive in ways that make ADUs and conversions unachievable, the local provisions should be reevaluated and amended. This could include default provisions for obtaining a permit to create an ADU if a local community does not adopt an ADU ordinance. States can also provide grant programs and technical assistance to enable and encourage communities to adopt and implement ADU provisions. In some cases, and with the proper oversight, these new units could contribute to local fair share obligations required by the Mount Laurel Doctrine in New Jersey or the 8-30g statute in Connecticut.

2. Make it Easier to Legalize and Construct ADUs and Conversions through Zoning Code Changes and Local Ordinances

With or without state policy, municipalities in our region should update their zoning and other relevant local ordinances to make it easier to create ADUs and do conversions. Many codes prohibit ADUs in single-family zones or put constraints on their construction with restrictive special permit requirements such as owner-occupancy, excessive parking, dimensional requirements, and others. Lifting these restrictions to promote ADUs should be explored in communities throughout the region. Any impact fees leveled for ADUs should account for their much lower impact on a neighborhood than traditional construction.

Zoning to enable and encourage ADUs and conversions would be a significant step towards addressing our region’s limited housing supply and high housing costs without significantly changing the built environment in single-family neighborhoods. There is a significant amount of low-density housing in places with good access to transit and jobs, including more than 750,000 single-family homes (almost of which are McMansions) in areas with high access to employment. ADUs and conversions offer a creative approach to creating much needed and relatively affordable housing.

Remove Owner-Occupancy and Relational Requirements for ADUs
In zoning codes where ADUs are allowed, there are often special permit requirements that mandate that the primary or secondary unit must be owner-occupied or that the secondary unit may only be occupied by a relative of the occupant of the primary unit. These requirements restricting occupancy are a disincentive for property owners who might otherwise consider constructing an ADU on their lot, as well as being an improper intrusion of a municipality into the relationships of a specific household. Where they exist, these types of restrictions on ADUs represent an unfair burden on property owners and tenants alike and should be eliminated. Other building or zoning codes which dictate specific household structures, such as New York City’s rule that three unrelated people cannot live in the same household, are also inappropriate and should be eliminated.

Relax Dimensional Criteria
While not a main driver, relaxing dimensional criteria can make it easier to create ADUs. In municipalities with deep setbacks and conservative maximum lot coverage requirements relaxed, standards should be considered, particularly in close proximity to transit.

Create Incentives for Visitable Housing Units
Visitable housing units are designed to be easily lived in or visited by people who have mobility impairments. Creating more visitable units increases the accessibility and resilience of neighborhoods, adding housing options for people to stay in their homes as they age, and removing barriers. A house is considered visitable when it meets three requirements: one no-step entrance; doors with 32” of clear passage space; and one bathroom on the main floor that is accessible by wheelchair.

Accessory dwelling units can easily meet visitability requirements with a one-level floor plan and inclined walkway entrance. As it is more costly to retrofit existing structures, encouraging visitability from the start will foster more inclusive housing. Incentivizing visitability is beneficial for the entire community.

3. Create Flexible Parking Requirements

Flexible Parking Requirements in Areas with Access to Transit
In neighborhoods close to transit, on-site parking requirements should be minimized and in most cases, on-street parking on public rights-of-way should be considered as a viable option to accommodate ADUs. This will also avert the burden of creating parking where it’s not needed. In general, removing minimum parking requirements for residential lots has the potential to reduce lot area used for pavement, preserve greenspace and landscaping, and offer greater flexibility to building forms. Additionally, it preserves on-street parking that could be lost to driveways and curb cuts.

Los Angeles has a similar policy. If the ADU is within a half-mile of a transit station, in a historic district, within one block of a car share, or part of an existing residence, the homeowner is not required to create more parking.

Encourage and Manage On-Street Parking
Municipalities should encourage on-street parking, including policies to discourage unnecessary curb cuts which eliminate on-street parking. Residents often worry that more housing will dramatically increase the number of cars, overcrowding the streets; however, there is no evidence that suggests ADU construction or home conversions cause parking problems. Instead of requiring off-street parking to prevent crowding the on-street spaces, municipalities can better manage the on-street parking. In addition, ADUs contribute fewer cars per household than single-family residences.

4. Provide Technical Assistance, Financing, and Information to Make it Easier to Build ADUs and Make Conversions

Create Programs that Promote ADU Construction and Conversions
Concerns about ADUs are often based on a lack of good information. Potential impacts of constrained parking and crowded schools are generally overstated while the many benefits are overlooked. Many residents can be unaware that ADUs even exist. By creating a local program that promotes ADUs, municipalities can disseminate knowledge of their capabilities and the positive impact it could have on their neighborhood. Changing the conversation around ADUs is key to their success as an effective housing development tool.

At the same time, local governments should launch programs to provide technical assistance for interested homeowners. These programs could include supporting elements, such as a government-run website to calculate what it might cost to build a secondary unit at any given locality. Other programmatic elements might include robust how-to guides and FAQ documents that demystify confusing zoning codes and permits.

Develop Toolkits to Simplify Technicalities
Many municipalities in our region allow for ADU construction, but enforce confusing, time-consuming, and expensive processes that discourage homeowners from engaging the process. Cities should create comprehensive toolkits to assist homeowners looking to responsibly build an ADU. During Portland’s push for the development of ADUs, 36 percent of homeowners reported that they had issues with the permit process and 22 percent had experienced poor professional help. Helping residents during the regulatory process will create more and safer new units.

Provide Local Financial Assistance
Often people underestimate the cost of building an ADU and can be disappointed when they discover just how high it can be. However, with proper financial guidance and products, ADU construction is possible and can transform into a lucrative investment. Municipalities should assess their current market conditions and create a local finance guide to ADU construction, and consider working with local firms on developing up-to-date finance and lending guides. It is difficult to standardize costs, especially as economic conditions frequently change, but a guide will be an essential starting point.

In addition, each state should consider creating a program that assists eligible homeowners to finance an ADU. Larger municipalities in the region could create or expand their own financing programs as well. In 2017, Boston launched their Additional Dwelling Unit Loan Pilot Project, offering homeowners in three pilot areas interest-free loans of up to $30,000 for an ADU remodeling project. Following its success, the Boston Zoning Commission approved a city-wide zoning text amendment that scaled the program and made it permanent. Governments should also consider a program that specifically targets assistance to senior citizens.

Case Studies in the Suburban Region

The following case studies have neighborhoods located within 60 minutes via transit to Manhattan’s Central Business District or 30 minutes to a city with a population of more than 100,000. In all four examples, commuter rail is supplemented by bus services that further increase access to employment. Each of these case studies also represents a set of specific policy recommendations on how to overcome barriers for expanding the use of ADUs and conversions.

Throughout our region and over the last two decades the ratio of housing to job production has ranged widely. NYC alone has had the largest housing production to job growth undersupply, adding 363,000 more jobs than housing units produced. Even if the economic crisis resulting from COVID-19 temporarily reverses this trend, the pandemic is heading us toward a new wave of homelessness and foreclosures that is creating an even greater urgency to expand a diverse range of affordable housing choices. Allowing and encouraging more housing options will result in a stronger and more resilient recovery.

A recent report from NYC Department of City Planning revealed that even though the city produced consistent numbers over the past decade, job growth significantly outpaced housing production – by a rate of 3.6 net new jobs for every unit permitted. During pre-Great Recession years, the tendency was different. NYC permitted 3 housing units for every job gained.

But in spite of this general trend, the use of single-family zoning has actually increased in NYC. Today almost 10,000 more parcels require single-family detached homes than in 2002. And while single and two-family dwellings represent less than a quarter of the city’s housing stock, they occupy over 65 percent of all residential land. As the five boroughs hold 37 percent of our region’s population, it is critical that NYC reverses this trend and leads by example with solutions to address our housing and affordability crises.

Even though only 15 percent of residential land in NYC is zoned for single-family homes, over 314,000 parcels – almost 40 percent of all residential land – are classified as single-family dwellings. About 142,000 of these parcels meet proper dimensional criteria for doing extensions or conversions that would allow ADUs or two-family dwellings. There are an additional 250,000 two-family dwellings (26 percent of residential land). About 180,000 of these two-family dwellings are either underbuilt parcels, or have large enough built floor areas to facilitate conversions. If just a third of single-family and two-family parcels that meet appropriate dimensional criteria were retrofitted with ADUs or conversions, then over 100,000 new legal dwelling units could be created. All of this housing would benefit from proximity to NYC’s subway, rail, ferry and bus network.

NYC already has over 60,000 parcels classified as being legally converted from single-family into two-family dwellings. This suggests that with the right policies, proper coordination across programs, and long term planning efforts, the ability to add 100,000 additional legal units created through conversions, extensions, and ADUs is highly feasible. Other organizations and campaigns looking at conversions, such as the BASE (Basement Apartments Safe for Everyone) campaign have also found similar possibilities, with the BASE campaign finding that potentially more than 110,000 units could be legalized.

NYC has about 80,000 parcels that are zoned for single-family housing only, and which are not classified as Historic Districts (R1, R1-1, R1-2, R2, R2A, and R2X). The highest concentration of these parcels exist in Queens (76 percent - 59,800 lots), with less on Staten Island (18 percent - 14,200 lots), Brooklyn (5 percent - 4,000 lots), and The Bronx (1 percent - 870 lots). There are none in Manhattan. Of these single-family zoned parcels, about half are underbuilt and could accommodate at least one ADU or a duplex, while maintaining maximum Floor Area Ratio (FAR) restrictions. Almost 7,000 of these parcels are significantly underbuilt and could add two more units while remaining within the maximum allowed FAR required by zoning. If a third of single-family zoned and underbuilt properties were to be retrofitted, then over 20,000 new homes could be created.

Beyond these zoning districts, there are over 37,000 parcels with single-family dwellings that are underbuilt by more than 50 percent available FAR. An additional 65,000 parcels with single-family dwellings are large enough to accommodate another unit through a conversion. If a third of these units were to be retrofitted, then almost 34,000 homes would be created. An additional 60,000 homes could be created by facilitating extensions and conversions of two-family dwellings into three-family dwellings.

There are almost 250,000 two-family dwellings constituting 26 percent of all residential land, most of them in Brooklyn and Queens. From this stock, about 60,000 parcels are underbuilt by more than 50 percent available FAR. An additional 120,000 houses are large enough to be converted into triplexes.

If a third of these units were to be retrofitted, then almost 20,000 dwellings would be created through ADUs or extensions and another 40,000 from creating three-family dwellings. Again, not all of these conversions would necessarily add more people. In many cases it would simply allow for an extended family or non-family household to live more comfortably. In many neighborhoods in NYC, a large number of illegal conversion of single-family homes already exist. The ability to legalize these existing units, as well as create new units, would likely result from the implementation of these policies and estimates include both scenarios.

Recommendations

1. Allow Housing Conversions and ADUs in NYC by Eliminating Zoning Requirements that Exclusively Require Large Detached Single-Family Dwellings

Zoning districts R1, R1-1, R1-2, R2, R2A, and R2X only allow detached single-family dwellings (or community facilities); any other type of land uses are prohibited. Almost 80,000 parcels in NYC have a zoning requirement that prevents a homeowner from converting their single-family home into a two-family home, even if it would require no new construction and not affect the exterior of the building at all. Furthermore, even when the building envelope is within the allowable Floor Area Ratio (FAR), excessive yard requirements and Dwelling Unit Factors, would often impede the ability to build an ADU or reconfigure residential area. These types of dimensional criteria should be waived or relaxed. Finally, the number of permitted land uses should be expanded to include and allow for two-family or more dwellings. Dimensional criteria should be relaxed and expanding the number of permitted land uses to include and allow for two-family dwellings in these zones should be instituted.

2. Disincentivize Consolidations Through Zoning, Tax, and Building Code Reform

There are an increasing number of units in multi-family buildings being lost to consolidation into single-family luxury homes. Manhattan has seen a 44 percent increase in single-family residences, with 723 additional single-family homes over the past two decades. These almost always do not come from new construction, but rather from multi-family buildings being turned into large single-family residences, costing the city much-needed housing near jobs and transit.

With the increasing popularity of the region’s core areas, as well as increasing local and global income inequality, wealthy individuals have both the means and desire to outbid multi-family uses in Manhattan and nearby neighborhoods. However, the core of the region, with its significant access to jobs and transit, is the place where we can least afford to lose housing units.

While it is difficult to legally prohibit these types of consolidations, they should continue to be treated as the previous multi-family buildings for property tax purposes. Overly large new residences above a certain square footage should also be treated as more than one residence for property tax purposes. For example, a newly built 12,000 square foot penthouse could instead be treated as four 3,000 square foot units for property tax purposes. Other disincentives through building or zoning codes could also be explored, including classifying overly large residences as an inappropriate use in multi-family districts.

3. Support NYC’s Basement Apartment Program Expansion on a City-Wide Level, and Look for Opportunities for Other Ways to Add ADUs

Greater housing choice can create more variety in unit prices and living arrangements, meeting a wider range of needs for prospective renters and homeowners. There is interest in accessory dwelling units, spurred by studies indicating a significant number of illegal basement and converted units. A 2008 study found that 114,000 new illegal units were added city-wide in just 10 years, and news coverage shows an increase of illegal micro-units being created. Most of these conversions happen in the outer boroughs.

In early 2019, NYC signed into law a pilot program in East New York that modifies code standards and offers low or no-interest loans that facilitate safe basement apartment units. In early 2020, NYC announced that it would expand this program citywide. However, due to upcoming budget cuts, this program is now slated for elimination completely. This is a short-sighted decision - the program represents one of the most cost-effective ways to create more affordable housing.

This program should be retained and expanded citywide as originally slated, and other reforms to laws and building codes should be explored in order to ease not just basements, but attic, garage and other space conversions that could still meet safety standards.

4. Rethink Off-Street Parking Requirements for Two- and Three-Family Homes

Adding additional units in any zone up to R4 means adding another off-street parking space as well, unless it is an IRHU (income restricted housing unit) which are very rare in two- and three-family homes. These parking restrictions prevent thousands of buildings from adding another unit, even if the house is otherwise able to convert or add an ADU. Especially near transit, these parking restrictions need to be modified or eliminated. This includes rethinking the excessive parking requirements in Lower-Density Growth Management Districts.

There can be many benefits to increased density if done smartly: improved infrastructure, better mobility and transportation, a more active local economy, and a more vibrant community. But there are also many misconceptions about the impact of increased density, and it is important to address these concerns head-on. In fact, in many cases, density can solve the very problems that many fear it creates.

Property Values Will Be Impacted Due to Higher Density

There is no concrete research that property values will increase or decrease as a result of adding more housing through ADU construction or conversion. While initial costs can be high, especially for ADUs, new units can be sensible long term investments as homeowners have the ability to collect rent while paying minimal maintenance costs.

Still, as with any unplanned new construction, there will likely be a negative effect if construction of new units is done haphazardly. When ADU construction or conversion is part of a coordinated development and planning strategy that considers compatibility and growth, the fear of declining property values has little basis. In fact, it is more likely that property values will rise.

Existing Infrastructure Will Be Unable to Compensate for the Added Density

Increased density can both encourage and facilitate infrastructure investment, while also enhancing the viability of community services such as health, education, and recreation. More compact forms of growth can also reduce infrastructure duplication and make efficient use of present capacity.

Studies have found that the cost of building infrastructure and providing services is proportionate to how far apart homes are located. It has also been estimated that urban sprawl costs the U.S. economy more than $1 trillion each year. Efficiencies compound in a favorable way when cities grow in more compact patterns. As more housing units are built along a road or sewer line, the capital cost of infrastructure and services per house decreases. This has been demonstrated by calculating the costs of infrastructure per capita, and looking at the correlation between travel distances and the cost of providing services such as transportation, education, water, and solid waste, among others. Consistent findings demonstrate that the cost of infrastructure and administering services increases in direct proportion to how far apart homes were spaced.

It is a valid concern that waste, water, and school systems might be stressed when handling an influx of residents or workers; however, the long term efficiencies deriving from more compact growth will reduce the costs of providing and maintaining public infrastructure. ADUs and conversions, as defined in this report, lay out mechanisms that are both non-invasive, and a smarter path for long-term growth and management.

When we talk about adding more housing, one of the first concerns raised in local communities is typically what the impact will be on the school district. Recent research on this subject looking at actual numbers in New Jersey shows that, on average, large single-family homes or other low-rise developments add by far the most school children per unit. Smaller units – which are the vast majority of ADUs – as well as mid- and high-rise developments add significantly fewer.

But ultimately, if the proposals in this report do end up adding new children to a particular community, educating young people is a regional civic responsibility. More and more places are seeing the benefits of welcoming new neighbors of all ages, rather than fighting proposals that intend on passing the burden over to the next neighborhood or municipality. As recommended in the Fourth Regional Plan, if states should take up far more responsibility for funding schools, then a growing population is seen as less of a burden.

Increased Density Will Cause Traffic and Transit Congestion

Higher-density helps expand transportation choices by providing riders options like bike, bus, and rail. It also encourages walkability. Investments in transportation systems need density to justify resource allocation and achieve returns. With destinations close by, car trips become shorter and more infrequent. People can choose to walk, bike, or take transit at least some of the time.

Current problems with traffic and congestion are not because of higher density, but due to systemic inefficiencies resulting from urban sprawl and under investment in transit systems. With better service and more options, our municipalities can shift mobility dependency from cars to mass rapid transit. In our region, businesses, elected officials, and the public at large have a growing understanding about the implications of properly funding transit infrastructure. Recent commitments and significant investment have been allocated towards improving our transit. This year alone, NYC, New York State, Connecticut, and New Jersey have announced major transit upgrade plans, which need to be fully funded and continued. While important obstacles still need to be overcome before these commitments are fully implemented, there is growing consensus that density is not the problem, rather the solution for more efficient mobility and creating healthier, more equitable, and prosperous communities.