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From large cities and metropolitan areas to smaller cities and towns, communities across the country are grappling with rising housing costs. In most local jurisdictions, zoning ordinances have resulted in only two types of allowable housing: single-detached homes or mid- to high-rise multifamily residential buildings. Often, most land zoned for residential use only permits single-detached housing, resulting in limited housing options and ever-rising costs to buy or rent as demand for housing outpaces supply.

Increasing housing affordability requires a suite of policy solutions. Middle housing, commonly called missing middle housing, provides one such opportunity.

Middle housing generally refers to housing types somewhere in the middle of the spectrum of housing, between single-detached houses and mid- to high-rise multifamily apartments and condos. It can take various forms, including duplexes (stacked or side-by-side), triplexes, fourplexes, townhouses (also known as row houses), bungalow or cottage courts, and mansion apartments.

Middle Housing Understood

Middle housing was once popular. New homes in the early twentieth century included duplexes, triplexes, and townhouses. But by the 1940s and 1950s, communities began adopting zoning ordinances that severely limited or banned middle housing types altogether. Over time, the lack of production led to our current lack of middle housing.

Today’s housing reflects these historical zoning decisions. According to the 2021 American Housing Survey, around 64% of residential structures in the U.S. are detached one-unit dwellings, compared to only 7% containing two to four dwelling units.

Current zoning restrictions continue to impact new housing. In many communities, most middle housing is either prohibited or strictly regulated by zoning ordinances that limit where they can be built and how they can look. Further, land use policies like comprehensive plans that establish the future vision for communities often only envision areas for either single-detached housing or mid- to high-rise multifamily development.

What Middle Housing Offers

 Middle housing can make communities more livable by offering affordable and accessible residential options, often with improved access to transportation, services, public spaces, and social engagement opportunities for people of all ages. Allowing more middle housing construction in a local jurisdiction promotes greater housing diversity that meets the needs of all community members while lowering overall housing costs by expanding supply. Single adults looking to live in a residential neighborhood, individuals and families with a lower or fixed income, or older adults looking to downsize all have the potential to benefit.

Because middle housing generally has a smaller per-home land cost, it is often more affordable than a single-detached house in the same neighborhood. And as home values in these neighborhoods rise over time, people with a broader range of income levels can build generational wealth. Further, middle housing can help address inequities left by practices like redlining, offering opportunities for people from diverse backgrounds to purchase homes in neighborhoods previously out of reach.

Several middle housing types can incorporate universal design and features that support people living with disabilities and older adults who want to age in place and stay in their community. One-story housing, such as a one-story cottage or the first floor of a stacked duplex, offers stair-free living and step-free entrances. New middle housing can also incorporate wider doorways and hallways, wheelchair-accessible bathrooms, and many other features to support accessibility.

Recent Middle Housing Legislation

While zoning happens at the local level, the rising popularity of middle housing has spurred legislation in states nationwide. Successful bills can guide stakeholders interested in middle housing in their communities. Below are a few examples.

Oregon. HB 2001, passed in 2019, directed cities with populations greater than 25,000 or within a metropolitan service district to allow duplexes, triplexes, fourplexes, townhouses, and cottage clusters in areas zoned for single-detached dwellings. The legislation has paved the way for similar middle housing legislative solutions in other states.

Nebraska. Passed in 2020, LB 866 linked middle housing to a broader effort to address housing affordability. The bill directed cities with populations greater than 20,000 to adopt an affordable housing action plan.

California. SB 9, passed in 2021, allows homeowners in California to split their lots into two and allows two homes to be built on each of those lots that previously only allowed one home.

Washington State. In April 2023, HB 1110 passed, allowing specific multi-family housing based on a city’s population. HB 1110 also includes affordable housing requirements.

Montana passed SB 382 in April 2023, a middle housing bill that allows local governments to implement 5 out of 14 regulation options, which include building more middle housing (duplexes and multi-family), eliminating accessory dwelling unit (ADU) impact fees, and reducing parking mandates.

A Middle Housing Policy Resource

 In April 2023, AARP released Re-Legalizing Middle Housing: A Model Act and Guide to Statewide Legislation (Model Act and Guide), which aims to empower volunteer leaders, interested residents, planners, and government officials to advocate for and establish effective legislation that can increase middle housing options, affordability, and accessibility. In collaboration with ECONorthwest, the Model Act and Guide expands on AARP’s publication, Discovering and Developing Missing Middle Housing, a resource with information about what missing middle housing is, where it still exists, and why it’s time for communities nationwide to return this versatile residence type to America’s housing portfolio.

The Model Act and Guide includes best practices that states can consider when developing middle housing legislation, including provisions that are more prescriptive and targeted to specific areas, as well as flexible provisions that allow for greater local authority. It provides multiple definition options for technical terms such as middle housing, subject jurisdiction, or transit-rich areas, allowing lawmakers to choose what works for their state and communities. The guide emphasizes equitable distribution while prioritizing high-opportunity and high-amenity areas, and it advocates for affordable housing requirements to accompany legislative solutions. At the same time, the Model Act and Guide seeks to balance statewide regulations with local control so that localities can address their own concerns, such as disadvantaged areas where displacement might be a possibility or take other substantive actions to support housing availability, affordability, stability, and equity.

A Key Piece of the Housing Puzzle

From AARP’s perspective, a community is more livable if it accounts for multiple dimensions of community life: housing, transportation, neighborhood characteristics, environment, health, opportunity, and civic and social engagement. Middle housing provides residents choices that offer walkability, a sense of community, and proximity to services, amenities, and necessities, from medical offices, grocery stores and transit to restaurants, parks, and shopping.

The country is facing a record housing supply shortage, and enabling the expansion of middle housing is not a panacea. Still, it is one of many solutions that can effectively address the issue and help create more livable communities.