Missing Middle Housing Types Case Studies

Issues Addressed:
Affordable Housing Housing Costs Housing Options Multigenerational Sustainable Housing

Dover, NH

Dover's zoning ordinance has long been a model for aligning zoning rules with housing production needs and traditional neighborhood design. All of its residential districts allow—whether by-right or by Special Exception—homes with up to four housing units per structure. (In lower-density areas, these housing types are only allowed in cluster housing developments.) Lot size and setback requirements provide reasonable opportunities to produce housing, with minimum lot sizes for missing middle housing types tending to be less than an acre. Dover Zoning Code, ​​https://www.dover.nh.gov/Assets/government/city-operations/2document/planning/Regulations/Zoning%202018.pdf
An excerpt from the Dover zoning code.

Hanover, NH

In 2022, Hanvoer town meeting approved a new base zoning district along one street in Downtown Hanover near Dartmouth College. The stated goal of the zoning amendment is "to increase the number of residential units," according to the zoning text itself. The existing neighborhood fabric has a mix of housing types, including missing middle housing types. Under the new rules, single-family, twofamily, and multifamily hosuing is allowed by-right. Importantly, the district's dimensional rules and dimensional rules were also relaxed to enable more infill small multifamily. Main Wheelock's new zoning was accompanied by design guidelines that specify architectural treatment of new housing. The zoning change was at least ten years in the making, with one failed proposal in 2015. In the 2022 effort, Dartmouth students were significantly involved in advancing the proposal and in the Town Meeting vote itself. At least area landowner had plans to add new housing to the area upon the amendment's passage.

Grand Rapids, MI

In 2008, Michigan’s second largest city updated their zoning to allow duplexes in previously single-family-only zones. (The amendments also allowed mixed-use development in commercial districts, and included “form-based light” provisions.) Duplexes were allowed by Special Permit on corner lots under the 2008 law. In 2018, An excerpt from the Dover zoning code. 72 Missing Middle Housing Types the City amended the new code to remove the Special Permit requirement and allow duplexes by-right.
A prewar duplex in Grand Rapids—the type of housing the city hoped to allow again.

Bend, OR

In 2019, Oregon passed a law to allow some missing middle housing types in all single-family zones across the State, giving discretion in implementation to a state land use board. In additional to allowing duplexes, fourplexes, and other small multifamily options, the board reduced local parking minimums for small multifamily homes in large Portland-area cities. Bend, Oregon became the first community to comply with the law locally, adjusting its zoning to allow duplexes and fourplexes. Those changes, combined with a strong real estate market, with 650 units under construction in early 2022.

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Three axonometric diagrams connected by one-way arrows. First, a small home on a small plot of land labeled "Historic, compact development pattern." Second, a larger home on a larger plot of land with arrows specifying setbacks, etc. labeled "Development mandated under zoning." Third and finally, a home and land parcel the same size as the first drawing, with arrows indicating setbacks, etc. and labeled "Reduced requirements."
Reduced Zoning and Subdivision Requirements
A subdivision of eight single-family homes surrounding a central green. The plot of land is labeled "Site plan that allows for community septic, prioritizing shared open space." Underground pipes lead from each home into a large underground box labeled "Joint septic tank." A pipe leads from that box into a smaller underground box labeled "Pre-treatment system." A pipe extends from that box and branches into many pipes with holes in them under a green area labeled "Community open space that doubles as a leach field."
Wastewater System Alternatives
A diagram of a single-family subdivision with twelve homes. Eight homes in red are labeled "Base Market-Rate Units." Two homes in yellow are labeled "Affordable Units." Two homes in blue are labeled "Bonus Market-Rate Units."
Inclusionary Zoning
A diagram with two versions of the same plot of land, one over the other. On the top version, the land contains only one single-family home with many wings and a large garage and a long driveway. This version is labeled with a large 'X' and "Regulations cannot mandate unaffordable housing everywhere." The version below contains two modestly sized single-family homes at the front of the site, and a driveway leading back to a cottage court, containing six small single-family homes around a central green. This version is labeled with a large checkmark and "Workforce housing must be allowed in a majority of residential areas."
Workforce Housing Ordinance
A diagram of a parcel of land. On the top is a mix of one- to three-story buildings, many with an apparent mix of uses, sitting along the intersection of two roads. This is labeled "Mix of uses using traditional village design." Lines at the edges of this area point draw down, showing this area is at the center of a larger area shown in dark green and apparently undeveloped. It is labeled "80% of rural and conserved in VPA."
Village Plan Alternative (VPA)
A grayscale diagram of a three-story, mixed-use, traditionally styled building with three columns of windows and a cornice. On the left is a diagram of the front facade, on the right is an axonometric diagram of the building on its land parcel. There are unlabeled arrows implying measurements for total height, total living area height, ground floor height, upper floor heights, cornice heights, ground and upper floor fenestration, setbacks, land widths, parcel depths, etc.
Form-Based Codes
A diagram of an idealized age-friendly neighborhood. The neighborhood includes a mix of housing types, including detached single-family homes of various sizes, mixed-use buildings, and a cottage court. The diagram includes the following labels pointing to aspects of the drawing: "Nearby retail, community center, and open space;" "Diverse housing options, including apartments and starter homes;" "Single-story housing layouts with shared amenities;" "Sidewalks and other accessible infrastructure;" and "Accessory dwelling units for multi-generational households."
Age Friendly Neighborhoods