In Washington state, a single cottage court can achieve densities of up to 21 units per acre, even with one-story homes. This efficiency allows for more housing units on smaller footprints, providing diverse options for residents in growing communities. Such innovative housing types, often referred to as missing middle housing, offer a human-scaled approach to accommodating population growth.
Missing middle housing offers a path to increased urban density and affordability, but existing regulations often make these efficient housing types economically unfeasible to build. For instance, a fourplex with four, 600 square foot units might require four times the parking and open space as a single 2,400 square foot detached home, according to missingmiddlehousing. These regulatory burdens often hinder the very housing types that could address affordability challenges.
As state and local governments increasingly mandate zoning reforms, the availability of diverse, moderately dense housing options will likely expand, gradually easing housing affordability pressures in many urban areas. This shift towards enabling smaller, more adaptable housing types through targeted regulatory reform fosters a decentralized, bottom-up approach to densification.
A cottage court, featuring one-story homes, can achieve net densities from 14 to 21 units per acre, despite each cottage being only 25 feet by 30 feet, according to missingmiddlehousing. This challenges the perception that high density requires multi-story construction. Increased urban density correlates with housing costs, with elasticities ranging from 0.041 to 0.05, according to Sciencedirect, indicating that more housing units per acre can contribute to affordability. Despite this potential, existing regulations present significant hurdles, impeding the construction of efficient housing types, even though such designs aim to make low-density mixed-use buildings more feasible, according to nyc.
Missing middle housing refers to a range of house-scale buildings that fit between single-family homes and large apartment complexes, offering a variety of housing options that are compatible with existing neighborhood character. These include duplexes, triplexes, fourplexes, cottage courts, and townhouses. The term 'missing' highlights their historical prevalence in many communities before being largely eliminated by single-family zoning and other restrictive land-use regulations. These housing types inherently provide greater density at a smaller scale, making them a crucial component for addressing urban housing shortages and improving walkability in neighborhoods.
States and Cities Pave the Way for Diverse Housing
Washington state's 2023 legislative session enacted significant changes, requiring accessory dwelling units (ADUs) in every Growth Management Act (GMA) community, according to commerce. These new parameters for ADU regulation specifically removed barriers to development, such as previous size limitations. This policy shift supports individual property owners in contributing to urban density without requiring large-scale rezonings.
House Bill 1096 further defined lot splitting and outlined its process in RCW 58.17.145, mandating that cities adopt new requirements by July 27, 2027, according to commerce. Furthermore, Washington state law now requires unit lot subdivisions to be included in short plat regulations for all cities, towns, and counties. These legislative actions actively dismantle traditional zoning barriers, creating a clearer path for the development of diverse, moderately dense housing options like ADUs and lot splits.
The stark contrast between the high density achieved by one-story cottage courts and the excessive parking requirements imposed on fourplexes reveals a significant regulatory challenge. While cottage courts achieve 14 to 21 units per acre with modest, one-story homes, according to missingmiddlehousing, a fourplex often requires four times the parking and open space of a 2,400 square foot detached single-family home, per the same source. Design innovation alone is insufficient; cities must aggressively tackle outdated parking and open space mandates to truly unlock affordable missing middle housing.
Companies and developers focused solely on large-scale projects are missing the significant, cumulative impact of missing middle housing, especially as states like Washington, according to commerce, and cities like New York, according to nyc, shift towards enabling smaller, more adaptable housing types through targeted regulatory reform. The incremental addition of duplexes, triplexes, and cottage courts across numerous lots can collectively add substantial housing supply. This decentralized approach, enabled by legislative changes, offers a more politically viable path to densification compared to contentious broad zoning overhauls.
What are the benefits of missing middle housing?
Missing middle housing offers several benefits, including increased housing affordability by providing smaller, more diverse unit types. It promotes walkable communities by integrating housing within existing neighborhoods and can help reduce urban sprawl. These housing forms also support local businesses and strengthen community character by offering housing options that blend with the existing architectural fabric.
How does urban density affect housing prices?
Urban density directly correlates with housing prices, with elasticities ranging from 0.041 to 0.05, according to Sciencedirect. Increasing density in desirable areas can lead to more housing supply, which moderates price increases. This effect is most pronounced when regulatory barriers to new construction are reduced.
What are the challenges of implementing missing middle housing?
Implementing missing middle housing faces challenges, including community resistance rooted in concerns about neighborhood character and increased traffic. Outdated zoning codes, particularly those mandating excessive parking and open space requirements, also create economic hurdles for developers. Overcoming these challenges requires both legislative reform and community engagement to foster acceptance of moderate density increases.
The Broader Impact: More Affordable, Livable Cities
New York City's 'City of Yes for Housing Opportunity' proposal aims to change bulk rules, which govern building size and placement on a lot, according to nyc. This initiative aligns with Washington's focus on ADUs and lot splitting, reflecting a broader national trend towards micro-level regulatory adjustments rather than sweeping rezonings to address housing shortages. These reforms contribute to creating more integrated urban environments.
Area auto commutes correlate negatively with residents' housing costs, according to Sciencedirect. Policies promoting denser, more walkable communities can reduce transportation expenses, thereby improving overall housing affordability. When people rely less on cars, their total cost of living decreases, making cities more accessible.
By Q3 2026, as legislative shifts in states like Washington and cities like New York continue to enable diverse development models, many communities will likely see increased housing options and more affordable, integrated urban environments.
