Is it time to end single-family zoning?
14 urban planners debate — and we outline the urban innovations that could advance the conversation.
At the heart of the movie “Parasite” — among the favorites for best picture heading into this weekend’s Academy Awards— is a tale of two cities.
On one hand, we have a poor family living in a dirty basement apartment in a dense downtown area, the stench of subway attached to them, scraping free Wi-Fi signals in search of a chance to move up. On the other hand, we have a wealthy family living in a modern suburban home, with a sleek black car to chauffeur them around, a big green lawn to soak up the sun, and a high-tech security system to keep out dirty basement types (quite unsuccessfully, we later find, to horrific ends).
To anyone interested in cities, such a premise can’t help but call to mind the complicated relationship between urban development and social justice — especially since, in the U.S. at least, the word “parasite” itself is deeply entrenched in this subject’s history. The term features prominently in the Supreme Court’s landmark 1926 ruling that established the basis for single-family zoning in America, in a disturbing passage that might as well have been the movie’s original treatment:
… 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. Moreover, the coming of one apartment house is followed by others, interfering by their height and bulk with the free circulation of air and monopolizing the rays of the sun which otherwise would fall upon the smaller homes, and bringing, as their necessary accompaniments, the disturbing noises incident to increased traffic and business, and the occupation, by means of moving and parked automobiles, of larger portions of the streets, thus detracting from their safety and depriving children of the privilege of quiet and open spaces for play, enjoyed by those in more favored localities — until, finally, the residential character of the neighborhood and its desirability as a place of detached residences are utterly destroyed.
Nearly a century into the story of single-family zoning, the plot is finally starting to twist. The City of Minneapolis and the State of Oregon both recently passed laws that loosen single-family regulations. California has proposed similar measures: some have failed (such as one encouraging denser development near transit), others have succeeded (such as ones encouraging backyard cottages). New bills in Maryland and Virginia also take aim.
Given these trends, the moment is right for everyone concerned with the future of cities to revisit single-family zoning, and indeed, there’s an entire issue of the Journal of the American Planning Association dedicated to that very debate. Published in January, the issue features nine essays, representing 14 total planning voices, taking up the question of whether or not single-family zoning’s time has come — and, if so, what to do about it.
The case against single-family zoning
A quick primer: single-family zoning (commonly known as R1 in planning parlance) prevents a community from building any type of housing in a given area except a detached single-family home. It’s nearly ubiquitous in the suburbs, but it’s also a central city problem. In San Francisco, 38 percent of residential land is zoned as R1; in Seattle, it’s 80 percent. Together this pattern creates an imbalance across an entire metro area’s housing market.
The pervasiveness of the rule is one of the reasons for its destructive social impacts, which have been documented in great detail. In brief, there’s compelling evidence that single-family zoning has damaged the environment by encouraging suburban sprawl and car reliance, worsened affordability by restricting housing supply, and undermined inclusion by keeping lower-income households out of high-opportunity neighborhoods.
With this context in mind, two JAPA papers say it’s time for single-family zoning to go.
One comes from UCLA planning and policy scholars Michael Manville, Paavo Monkkonen, and Michael Lens, who write: “In the 21st century, no city should have any land where nothing can be built except a detached single-family home.”
The other comes from planning scholar Jake Wegmann of the University of Texas-Austin, who hopes to see single-family zoning replaced by “missing middle” housing. He writes: “For members of the planning profession to make headway against the climate and inequality crises, they must cease defending the indefensible concept of single-family zoning.”
The papers each make a powerful case for ending single-family zoning, and are recommended in full. But in the interest of summary, here are six of their strongest points:
People can still build single-family homes. One of the most common arguments for keeping single-family zoning is that most people prefer single-family homes. That’s increasingly not the case, as seen by the premiums found in walkable urban neighborhoods, and studies show a desire for denser living even in car-friendly areas. But even if that were true, it wouldn’t be a good argument for single-family zoning, because removing the rule doesn’t prevent such housing from being built. If people still wanted these homes, developers would continue to build them. They’d just be allowed to build other types as well — in response to household preference.
Communities can still prevent Manhattanization. A primary goal of ending single-family zoning is to help new households move into neighborhoods they can’t currently access. That push for more housing is not to be mistaken with an invitation for skyscrapers. A community can still impose height restrictions without precluding the creation of alternative housing types, such as accessory dwellings or multiplexes. Cities like Washington, D.C., employ such restrictions and still generate loads of dense development, as well as single-family homes. And, as the UCLA scholars point out, Paris has a height restriction without much of either extreme: single-family or skyscraper.
The missing middle can unlock affordability. At its core, this push for more middle-density development is really a push for more housing affordability. Wegmann points to a recent case in Austin, where a developer used a zoning loophole to build six homes on a lot that would normally house just two single-family homes. Each sold in the mid-$400,000 range — or $200,000 less than the area average. While that’s still beyond the reach of many low-income households, creating more middle-income options ultimately frees up public resources to focus on creating affordable housing for those most in need.
There’s a sustainability case for the missing middle, too, with evidence showing that significant carbon savings come from converting low-density development to medium-density.
Upzoning won’t necessarily spoil housing investments. While single-family zoning successfully protects housing investments, Wegmann argues that’s not the role of planning, which should instead focus on creating more sustainable and equitable cities. And the UCLA scholars point out that upzoning an area can increase property values as well, by raising land prices for developers. “The question, then, is not whether homeowners will receive windfalls,” they write. “It is whether those windfalls will come from maintaining housing scarcity or enabling housing abundance.”
Existing tenants can be protected. Both papers acknowledge that ending single-family zoning could lead developers to build more housing in lower-income areas, where land is less expensive, ultimately displacing long-time or low-income residents. That’s a very real possibility, and one that should — and can — be safeguarded through rental protections. The UCLA scholars also note that single-family neighborhoods aren’t typically the ones facing these risks: only 4% of detached single-family homes in the U.S. hold renters with incomes less than $25,000 a year, according to 2017 Census figures.
Infrastructure strains can be managed. More people means more competition for shared space and shared infrastructure. The papers argue that these concerns can be managed in ways that balance the risks with the benefits. Parking shortages can be handled by allowing non-covered spaces or limiting on-street permits. More utility users also means more revenue for upgrades or maintenance. Family-friendly designs can keep higher-density communities safe and welcoming for kids. And the alternative to ending single-family zoning — pushing development further away from dense cores — creates new infrastructure strains of its own.
Commentary, counter-points, and qualifications
The rest of the special issue featured contributions that augmented, or in some cases attacked, the points made above. Again, in the interest of brevity, these will be summarized by their key points, but many of the full papers are worth reading.
Minneapolis shows the path forward. Paul Mogush and Heather Worthington, planners from City of Minneapolis, explained how they dented the R1 armor. First, they studied its history and confirmed the impact that restrictive zoning had on minority households. Then they settled on what they call an “obvious” first step toward improving housing equity: “Start by reversing the regulations that planners began using a century ago to stifle opportunity for people of color.” Minneapolis now encourages the missing middle by allowing at least three residential units on each parcel throughout the city and multifamily buildings “by right” near transit hubs. And to address displacement concerns, they committed to affordable housing investments and tenant protections.
Maryland isn’t so sure. Gerritt Knaap and Nicholas Finio, planners at the University of Maryland-College Park, aren’t sure their state will ultimately approve a Minneapolis- or Oregon-style law encouraging denser development, based on informal discussions with local government, developers, and even environmental groups — none of whom supported such measures. The reasons varied from legitimate concerns, such as serving low-density areas with transit and overcrowding schools, to more surprising responses, such as a vague distaste for “activist” planning. “Needless to say, without support from these groups, it seems unlikely single-family zoning will be banned in Maryland any time soon,” they conclude.
(It’s unclear whether the responses preceded Maryland’s latest proposal, which does try to address many common concerns.)
Incremental change is wiser. Glen Searle and Peter Phibbs, planning scholars at the University of Sydney, noted how unusual America’s zoning rules are. By contrast, in Sydney, planners actively pursue the missing middle. Still, they expressed caution against going from such a high share of single-family zoning to eliminating it. Their most persuasive point is that removing the rule might unintentionally promote more car use, since communities will now have more people living in places where transit is tough to provide. For this and other reasons, they suggest instead a “modified set of rules” in areas that are already suitable for greater density.
Political capital is better spent elsewhere. Arnab Chakraborty, urban planning professor at the University of Illinois at Urbana-Champaign, questioned whether ending single-family zoning alone would really improve affordability or help low-income households move to high-opportunity neighborhoods. (To that point, raised elsewhere, others agreed that ending R1 is necessary but not sufficient.) Calling for a “more measured approach,” Chakraborty cautioned that tackling single-family zoning will require enormous amounts of political capital that could better be deployed elsewhere, such as targeted affordability programs.
Focus on undeveloped areas. In the most contentious essay, Lane Kendig of the Kendig Keast Collaborative planning firm calls ending single-family zoning a “mistake” and a “facile remedy” for affordability. Kendig essentially argues that because ending single-family zoning will not end income-driven segregation, there’s no point. (To such points, the UCLA scholars reply that just because people commit crimes with a knife doesn’t mean governments shouldn’t pursue gun control.) Instead of battling for greater density in existing single-family areas, Kendig suggests focusing on undeveloped land and replacing conditional zoning rules that invite local opposition with performance-based zoning (a good idea, discussed more below), inclusionary zoning, and affordable housing mandates.
Ethics demand a change. Taking a strictly professional angle, urban studies professor Anaid Yerena of the University of Washington says planners have an “ethical responsibility” to eliminate single-family zoning. Yerena quotes from the American Institute of Certified Planners Code of Ethics and Professional Conduct, which states: “We shall seek social justice by working to expand choice and opportunity for all persons, recognizing a special responsibility to plan for the needs of the disadvantaged and to promote racial and economic integration.” To Yerena, eliminating single-family zoning is an obligation — “not merely a matter of choice.”
What’s needed most are new housing models. In perhaps the issue’s most persuasive piece, urban planning scholar Harley F. Etienne of the University of Michigan says abolishing single-family zoning isn’t enough to change a century of entrenched land use patterns and cultural attachments. Instead, planners need to go even further and offer a new model of development that “enables the public to aspire to a different mode of housing tenure.” This new model must encourage middle- and low-income housing, give these households access to good schools and jobs, and provide pathways for them to catch-up on the generations of wealth-creation they’ve missed out on. Until such a housing model comes along, writes Etienne, “we do not stand much of a chance.”
The role of urban innovation in advancing the conversation
Single-family zoning is a policy challenge that needs a policy solution. It’s not something technology can address on its own. But there are still a set of urban planning innovations (including some being development by Sidewalk Labs) that can advance the conversation in constructive ways — especially for single-family zoning in urban areas suitable for transit or greater density. These tools can make the spurious arguments for single-family zoning harder to defend, help evaluate or even relieve the legitimate concerns, and expand the menu of housing options.
Here’s a few we’re working on:
Flexible apartments. To the critical point raised by Etienne, right now the collective American housing ideal tends to follow a reliable trajectory that ends in suburban home ownership. Of course, that’s not true for everyone, and it’s increasingly less true across the country, but it remains the model of record. Breaking that pattern requires new urban housing options that can follow a household across a lifetime. That could mean flexible furniture that makes 500 square feet feel like 650; flexible units that can expand as a family grows (or contract as nests empty); and shared building spaces or neighborhood amenities that make square footage just one of many factors guiding a housing choice. Or it might mean financing models that help households generate home-value, such as shared equity programs that let tenants own a small share of a place — with a smaller down-payment — while renting the rest.
Factory-driven affordability. Some of the more cautious papers noted that zoning alone won’t unlock affordability, and it’s true that improving affordability requires pulling all sorts of policy levers. One of the strongest cards local government can play comes through its sale of publicly owned land, especially around transit hubs, to generate more affordable housing. As factory-driven construction methods improve, accelerating the pace of development projects, the value of such land stands to rise. The public sector can capture this value and ensure the creation of affordable housing in a few ways. One promising approach is to establish a housing trust fund that “lock-boxes” land premiums for affordable units, ensuring a steady source of funding over the long term.
Outcome-based zoning. Even opponents of ending single-family zoning (like Kendig) recognize the problems that arise when communities can reject new housing development for arbitrary reasons. At the same time, even strong proponents of abolishing this rule recognize that households deserve some basic assurances of neighborhood character — preventing, as Wegmann says, a smelting factory from moving in next door. Moving toward an outcome-based zoning system makes it possible to offer basic protections around common priorities like air quality, noise, or public health without the broad strokes of single-family zoning. Officials can set thresholds according to community preferences, then measure them via manual checks or environmental sensors. It’s the neighborhood character outcomes that should matter most, not how a particular development achieves them.
Generative neighborhood design. Going all the way back to 1926, proponents of single-family zoning have voiced concerns around things like blocking sunlight or reducing open space. These community needs can often stand in conflict with developer needs around density and total housing units: increase a building height in one place, create shadows in another. The common way of weighing these tradeoffs is for developers or planners to commission a small handful of neighborhood designs, at a very high cost. But advances in computational design make it possible to simulate millions of planning scenarios and identify many options that satisfy all project priorities, from developers and communities alike. And such tools also make it possible to discuss these options openly and transparently.
On-demand mobility instead of parking. Parking can be one of the most contentious issues that block new developments in single-family areas, with existing residents worried about having a space for their car. Setting aside the validity of such concerns — which effectively place the rights of cars above the opportunities of people — it’s true that single-family areas tend to require a car, given that transit service just can’t offer the same mobility freedom. But in new developments near transit stations, in particular, it’s possible to replace parking requirements with a package of on-demand mobility options (such as ride-hail or bike-share) that offer the same convenience as owning a car, at a comparable or even lower price, without requiring a parking space.
At one point in the movie “Parasite,” a character says something to the effect of: the best plan is no plan. The urban planning profession probably wouldn’t agree, but then again, if this special issue is any indication, it also wouldn’t have a consensus that the best plan is single-family zoning. The debate is clearly just heating up.