To slow the current rise in rents and home prices in many urban areas, there is a need to balance efforts to create and preserve dedicated affordable housing with an increase in the overall supply of housing in the market. Given constraints on the availability of undeveloped land in many of these areas, increases in the supply of housing will often require an increase in the density with which housing is built. However, proposed increases in density are often opposed by existing residents who raise concerns about traffic, education costs, changes in neighborhood character and, in some cases, displacement from changing neighborhoods.
The paradigm that many have in mind when they debate the wisdom of density in an urban or suburban setting is generally the new construction of a relatively large number of housing units on a vacant parcel, either as a single multifamily development or as closely-situated single-family homes or townhomes. But a new approach for increasing density being considered in a number of cities would facilitate smaller increases in density on a more scattered-site basis. This strategy offers a particular focus on allowing the construction of duplexes, triplexes and other so-called “missing middle housing” in areas currently comprised largely of single-family homes.
Local Actions to Facilitate Missing Middle Housing
On December 7, 2018, for example, the Minneapolis City Council approved a new Comprehensive Plan that, among other things, calls for zoning changes to allow duplexes and triplexes in all residential neighborhoods zoned for single-family housing. The plan, titled Minneapolis 2040, also authorizes more traditional density increases, such as changes to allow multifamily housing along select public transit routes, with higher densities near high-frequent transit lines and METRO stations. To further facilitate new development, the plan proposes eliminating the requirement for off-street parking minimums throughout the city.
Olympia, Washington similarly took action recently to expand the range of housing options within certain residential districts. On November 5, 2018, the city passed an ordinance to facilitate the development of accessory dwelling units, cottage housing, courtyard apartments, duplexes, triplexes and fourplexes, SROs and tiny houses.
The explanatory materials for Olympia’s zoning changes refer explicitly to “missing middle housing,” a term coined by Daniel Parolek of Opticos Design to describe “a range of multi-unit or clustered housing types compatible in scale with single-family homes that help meet the growing demand for walkable urban living.” An illustration on Parolek’s MissingMiddleHousing.com website positions the “missing middle” as falling in between single-family housing on the one hand and mid-rise construction on the other. Missing middle housing includes duplexes, triplexes and fourplexes, courtyard apartments, bungalow courts, townhouses, multiplexes and live/work spaces.
Will Efforts to Facilitate Missing Middle Housing Significantly Increase Supply?
The jury is still out on whether a missing middle housing approach will appreciably increase the overall supply of housing. After all, the construction of a duplex in place of a single-family home adds only one additional unit to the stock, in contrast to the dozens of units that may be added by a multifamily development. Accordingly, there will need to be many more “actions” to take advantage of the new zoning in order to have an equivalent effect on unit volume. In addition, the construction of individual duplexes or triplexes can’t take advantage of the economies of scale available to larger developments.
But it’s worth trying for two main sets of reasons. First, from a practical perspective, a focus on missing middle housing dramatically expands the potential locations where density may be increased. Large sections of most urban and suburban areas are already built out along a single-family paradigm. Assembling a parcel large enough for a multifamily development in these neighborhoods may be extremely difficult, but investors or other buyers could choose to replace aging single-family homes with duplexes or triplexes, instead of the more customary single-family McMansions. The duplex, triplex or even quadraplex may even look exactly like a single-family McMansion, helping to reduce local opposition.
Second, irrespective of whether zoning changes to accommodate missing middle housing will produce enough volume to moderate rent and home price increases, these changes could help to make resource-rich neighborhoods somewhat more inclusive of people of different incomes, races and ethnicities. A growing body of work has demonstrated that the neighborhoods in which children grow up have a profound impact on their earnings and educational achievement as young adults. While there are certainly exceptions, many of the neighborhoods with the greatest potential for beneficial impact on children’s achievement are likely single-family neighborhoods with high home prices. While homes newly constructed as (or modified to be) duplexes, triplexes or quadraplexes in these neighborhoods would not likely be affordable without subsidies to low-income families, they would almost surely rent or sell at levels below those of single-family homes, helping to improve access to these neighborhoods for moderate income households, including households of color.
On their own, interventions to boost supply will never be enough to create the desired level of affordability. But they’re an important part of the larger affordability puzzle. So keep an eye out for efforts to facilitate missing middle housing, and let’s hope they make a meaningful difference.