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Ending Single-Family Zoning Is Not a Stand-Alone Solution

The practice has become a focus of housing reform but eliminating it might not make much difference if other regulations aren’t considered.

An apartment building being built.
In 2020, the Portland City Council changed zoning rules to allow more multifamily units to be built amid single-family homes.
(Doug Beghtel/LC- The Oregonian/TNS)
Nearly 4 in 10 American households rent their homes. Almost half are “rent-burdened,” spending more than 30 percent of their income on housing, and more than 10 million renters spend half or more of their income on rent.

Despite a softening of the rental market early in the pandemic, a July market report from Zillow found that typical rents were 9.2 percent higher than they had been the year before. According to the rental listing site Zumper, median one-bedroom rents went up more than 12 percent in 2021, compared to 0.3 percent in 2019.

These trends aren’t expected to continue, but that won’t resolve the mismatch between the supply of affordable housing and the demand for it. The shortfall of rental housing affordable to very low-income households is nearly 7 million units, the National Low Income Housing Coalition estimates. This gap will never be filled if new housing continues to be available at the current pace.

Most renters live in multifamily structures, but zoning codes can restrict or prohibit the construction of these buildings on much of the available land in cities. A growing number of policymakers believe that the elimination of single-family zoning can open the door to housing development, but a first-of-its-kind research effort in Connecticut reveals that this step alone will not be enough.

More than 6 in 10 renters live in multifamily housing, almost half in structures with five or more units.

Not Welcome in Every Backyard

An infamous 1926 ruling by the Supreme Court established a basis for single-family zoning and set a tone that would hold for decades: “Very often the apartment house is a mere parasite constructed in order to take advantage of the open spaces and attractive surroundings created by the residential character of the district.” Single-family zoning gained momentum after World War II to preserve a suburban ideal fueled by federal loans and, too often, to foster segregation.

Policies that restrict multi-unit housing development to a fraction of available land don’t square with population growth, the unsustainability of sprawl, a fast-growing preference for multigenerational living, the sheer unaffordability of detached homes in many parts of the country or the lifestyle choices of millennials. Cities and states are beginning to rethink these laws.

Minneapolis was the first major city to eliminate single-family zoning, in 2019. In 2020, the Portland City Council voted to change residential zoning rules to allow more duplexes, triplexes, fourplexes and accessory dwelling units to be built amid single-family homes. In October 2021, the Seattle City Council voted to replace its “single-family” zoning designation with the term “neighborhood residential zones,” stopping short of changing zoning but opening the door to alternative policies.

California Gov. Gavin Newsom signed a bill that will allow as many as four dwellings — two duplexes or two homes with attached units — to be built on lots zoned for single-family residences, with some exceptions. The legislation was applauded by affordable housing advocates, but the director of the League of California Cities complained that it “undermines the ability of local governments to responsibly plan for the types of housing that communities need, circumvents the local government review process, and silences community voices.”

Similar efforts are being considered elsewhere in the country, but they are likely to fall short of their goals if they don’t take the full spectrum of zoning regulations into account, says architect and attorney Sara Bronin, a professor at Cornell University and founder of the nonprofit Desegregate Connecticut.
The Zoning Atlas on the Desegregate Connecticut website is an interactive map showing regulations in every district of the state. (Desegregate Connecticut)

The First Code Atlas

Desegregate Connecticut came into existence in June 2020, a response to calls for racial justice in the aftermath of the murder of George Floyd. Early on, Bronin realized that it would be difficult to advocate effectively for policies to improve housing equity and diversity without understanding existing policy well enough to identify potential points of change.

To accomplish this, she volunteered her own time and enlisted a team that included Yale undergraduates, professional planners, law students and a local community foundation. The team collected zoning codes from every jurisdiction in the state — a total of 2,622 zoning jurisdictions in 169 municipalities and 11 submunicipal districts.

The code data was organized, analyzed and formed into a data set that was combined with GIS maps for every district in the state. The resulting Connecticut Zoning Atlas, an interactive graphic representation of the zoning rules gathered by the research team, is the first resource of its kind.

“There has not been a study like this that collected zoning information at the scale of the district and then mapped districts across multiple jurisdictions in a way that enables users to see what the codes actually mean on a lot-by-lot basis,” says Bronin.

Studies regarding zoning requirements and their potential to constrain housing options are often built on survey responses from officials. But according to Bronin, “what people say zoning laws say in a survey is not necessarily what zoning laws say.”

The compilation of all the actual codes for her state into a single, searchable resource brought unprecedented clarity to the ways that regulations interacted. Bronin shared what she discovered about single-family zoning in a paper for the Cornell Journal of Law and Public Policy, which she titled “Zoning by a Thousand Cuts.”

Not a One-Step Solution

Analyzing the zoning data, Bronin found that over two-thirds of the primarily residential land in Connecticut allows only single-family homes to be built without a public hearing. Developments of four or more units can proceed without a hearing on less than 2 percent of primarily residential land.

Zoning reform that only addresses single-family restrictions isn’t enough in itself to change things. Bronin discovered that a surprising number of other zoning requirements have the potential to interfere with efforts to open more land to multifamily dwellings, a phenomenon that is not limited to her state.

Sara Bronin
Sara Bronin: “It’s important to ground your efforts in data and research.”
(Jane Shauck/IRIS Photography)
Projects which require a public hearing are more likely to be rejected, and the first major lesson from the Connecticut data, she writes, is that “public hearing requirements are an important target for regulatory reform, because they are far more widespread in constraining multifamily housing than I suspect even well-versed researchers might have guessed.”

Other factors include minimum parking and maximum building height requirements and prescriptions regarding lot size, lot coverage or floor-to-area ratio. Some codes impose unit sizes on accessory dwelling units or limit the occupants of them to a relative or employee of the owner, or the elderly.

In short, Bronin concludes, “even if we increase the number of units allowed on individual lots in a district, a multitude of other, hidden factors may prevent more units from actually being built.”

Advancing Equity

Using the data from its research, and partnering with other housing advocates, Desegregate Connecticut played a role in achieving legislative reform that could open the door to more affordable housing development in the state.

Among other things, Public Act 21-29 eliminates or reduces parking requirements for various housing types, allows accessory apartments to be built without a special permit or public hearing and prohibits towns from enacting regulations that cap the number of multifamily housing units or require minimum square footage. It also calls for an expert group to develop model design guidelines for buildings and streets.

If people understand what zoning is and what it does, they are more likely to see good reasons to modernize it for the 21st century. It’s important for those who want to make a difference to ground their efforts in data and research, and a guide to help others create the kind of data resource that has helped Desegregate Connecticut is available on its website, says Cronin. “For jurisdictions out there who want to assemble a zoning atlas like the one we have here, we are open to collaboration and would extend the invitation to talk more about lessons learned.”
Carl Smith is a senior staff writer for Governing and covers a broad range of issues affecting states and localities. He can be reached at or on Twitter at @governingwriter.
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