This article has been reprinted from the Transit Friendly Planning Newsletter with permission from NJTOD (New Jersey Transit Oriented Development). The original article was printed March 7, 2025. 

In New Jersey, as in much of the U.S., prospective homeowners and tenants often face a choice between single-family homes or large multifamily buildings, leaving a gap in available housing types. Missing middle housing—ranging from duplexes to structures with up to 12 units—was largely sidelined by post-war zoning and suburbanization, which prioritized low-density, single-family suburban neighborhoods and high-density urban areas. Planners and housing advocates, however, now emphasize its role in increasing affordability while maintaining neighborhood character. Policies encouraging middle housing in single-family or transitional neighborhoods fall under the concept of gentle density. 

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NJ TRANSIT’s Transit Friendly Planning (TFP) program released Gentle Density and Missing Middle Housing in New Jersey: A Guide for New Jersey Communities in September 2024, providing municipalities with guidance on how to implement gentle density and expand missing middle housing as a response to the state’s affordability crisis. This guide supplements Transit Friendly Planning: A Guide for New Jersey Municipalities (2022), deepening the discussion of missing middle housing types and their role in fostering context-sensitive density growth.  

The Guide traces New Jersey’s housing history and uses demographic data and surveys to highlight the potential for gentle density and missing middle housing in addressing the state’s housing challenges. Post-war development favored detached, single-family homes, while larger multi–family buildings were concentrated in urban areas like Newark or Jersey City. After the 2008 recession, housing construction shifted towards large multi–family buildings, while single-family home development declined—a shift influenced by increased demand for rental units and exclusionary zoning policies that limited density to specific areas. Throughout both housing development patterns, middle housing remained a small portion of new construction.

Demographic shifts, including the rise in one- and two-person households and ongoing affordability concerns, have made the need for middle housing more urgent. As homes have grown larger and household sizes have shrunk, many first-time buyers and renters struggle to find affordable options. Middle housing provides an opportunity to add density without dramatically altering neighborhood character, addressing the affordability gap and meeting the needs of diverse populations—especially in locations near transit hubs, where new development is often dominated by high-density housing.  

The Guide includes case studies of local and national efforts to implement gentle density. Some states, such as California, and cities like Minneapolis, have eliminated single-family zoning by allowing middle housing, such as duplexes and triplexes, in all formerly single-family zones. Other cities have adopted form-based codes, prioritizing building scale and context over rigid density requirements. In New Jersey, an increasingly common approach to gentle density is the permitting of accessory dwelling units (ADUs), allowing homeowners to build new units or renovate existing structures to add housing on their property in single-family zones.

To help municipalities integrate gentle density, the guide outlines planning strategies, including public engagement methods, spatial and statistical analyses, and GIS-based zoning assessments to identify suitable locations. It also builds upon a 2023 APA Zoning Practice report, which presents best practices for gentle density zoning, such as establishing standards for bulk, setbacks, building types, permitted land use, and design considerations. Expanding on these practices, the guide introduces a four-task planning framework with practical steps for municipalities to support gentle density. 

To learn more about gentle density, also see our article on this topic, Gentle Density: Tactics for Small-Scale TOD.