ADUs Are Not Enough for California

ADUs Are Not Enough for California

This article was originally published on Common Edge.

ADUs or accessory dwelling unit, a word mostly used by architects, is "a smaller, independent residential unit located on the same lot as a stand-alone single-family home" according to the American Planning Association. They can be converted spaces of existing houses, additions, or new stand-alone structures. In this piece, author Walter explores the recent policies in California that seek to reduce the shortage of housing.

The recently approved California legislation SB-9/10 effectively eliminates single-family zoning in the state as a step toward higher housing production and reducing the persistent shortage. The well-intentioned laws are full of potential. However, much will depend on how they get implemented locally. If used with deliberate form in an urban context, they could drastically improve cities and demonstrate a constructive way forward. But if haphazardly inserted into the existing suburbia, retaining outdated rules like setbacks and parking mandates, they could further decrease the livability of cities and lead to a massive backlash that might make the NIMBY movements of today seem quaint by comparison.


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It’s logical to look for solutions to the state’s housing shortfall in the low-density sprawl that once defined the American Dream. Nearly two-thirds of all the residences in California are single-family homes. As much as three-quarters of the developable land in the state is now zoned only for single-family housing, so-called R-1 areas, according to UC Berkeley research. Those areas require only a relatively minor increase in density to achieve the housing numbers needed for many decades to come. But without holistic changes to the city and its transportation infrastructure, adding density will overload the capacity of the vast car-centric suburbia and likely fail.

Recent multifamily housing construction by larger developers has focused on the little available land outside the R-1 zones, in select corridors and transit-oriented development areas. In theory this offers new residents a chance to live a less car-dependent life. But the resulting buildings are not popular. Block-sized projects balancing on top of even larger parking garages are grotesque, bloated, and rightly considered “out of character” and “out of scale.”

This is not what most people dream of when they contemplate living in the city, in massive housing projects, where they will get a small box to call their home, on a long corridor, with dozens of other doors that look the same. Perversely, this is called “urban” in real estate marketing speak, but it really is an intensified, taller gated suburban community, with even more cars. This product type is economically profitable. And in a massive housing shortage, it does not take too much arm twisting to get people to occupy them, since there is little else. 

Surveys indicate many people would like to live in housing typically found in small towns or college towns. Their walkable form makes them ideal for inexpensive, green living. They feature compact street grids that support small, incremental buildings and vacant lots ready for infill. Small towns usually have good existing character and allow for personally tailored space. The classic Main Street buildings feature ground floor retail with one or two stories of office or residential above. These are buildings built to last. Their good scale, proportions, open floor plans, and operable windows make them highly flexible. This formula results in beautiful buildings with authentic materials; excellent, handcrafted elements; and real estate that far exceeds the value of new construction.

The missing middle housing movement advocates for building types that once created these kinds of towns. Such communities have long functioned as the 15-minute city model that is so fashionable in today’s urban design literature. And the vision is attractive: Who wouldn’t like to live within proximity of almost everything one needs? But the hope that merely allowing some accessory dwelling units (ADUs) and duplexes will convert suburbia into these small-town environments is misplaced. Quality small-scale urban fabric will not automatically evolve without sustained and active transformational design support.

To start, typical suburbs cannot tolerate even slightly higher automobile densities. It’s no surprise that many street signs in opposition to SB-9/10 referred to a future “congestion” crisis. There’s a density paradox illustrating that the car-based model works well for lower densities, and that the transit model works well for higher densities, but the in-between densities do not really work for either. More density without alternative mobility choices overloads the parking capacity on the block, and the driving capacity on the streets. As a reminder, Measure U, the downzoning of greater Los Angeles, was supported by a widespread feeling that L.A.’s streets were already too crowded. More ADUs with cars could trigger a backlash and provide new motivations for an unwise Measure U redo.

While a complete reintroduction of missing middle building types would indeed be a major step toward more livable cities, ADUs and duplexes represent only a subset of the building types needed: small, multistory apartment buildings; row houses; courtyard apartments, both in their attached and detached versions; etc. But the biggest problem with SB-9/10 is the impact it will have on urban form. Specifically, it will wipe out what was so great about SoCal living in the first place: namely, its immediate connection to the great outdoors, in one of the best climates on Earth.

Southern California’s climate is Mediterranean, and in similar climate zones around the world there are numerous examples of positive, climate appropriate open space and outdoor living. Traditional towns have whole ecosystems to maximize this benefit. The leisurely evening stroll in Italy is called a passeggiata, and most Mediterranean cultures encourage something similar in so many different forms, from Barcelona’s La Rambla to tree-covered boulevards to landscaped promenades along the water.

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A walled garden in Prague. The sculpted wall is a fire wall to the next building. . Image via theworldisabook

Additionally, there are parks and walled gardens, all protected from cars and providing quiet respites from the busy city. People enjoy courtyards and backyards, and have for centuries. Appealing open space is a major contributor to the quality of life. 

Many cities these days create pedestrian districts and weave protected and safe bicycle paths through the neighborhoods. Walkable and bikeable cities often rank among the most desirable places to live. There are some rare examples in Southern California for this type of environment, with the most visible example being Santa Monica’s 3rd Street Promenade.

Suburbs generally don’t have such spaces. There are no plazas, leafy promenades, or pedestrian zones, other than the ones found at a shopping mall, and they are often surrounded by parking lots. Suburbs are the direct inverse of properly designed urban fabric. In a suburb, a building is placed in the middle of a lot, and the open space is the leftover space around that building. Historically, a 1,500 square-foot home on a 5,000 square-foot lot leaves a pleasantly sized backyard. But once an ADU is built in that backyard, soon the only open space left will be the zoning mandated buffer space (aka the setbacks). “Leftover” spaces create terrible outdoor environments for people. The strip of land on the sides of the buildings may be large in area, but it will never be a space to hold a backyard gathering or enjoy perfect weather in a hammock. And the front yard is even worse because it is exposed to traffic.

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Santa Monica, 3rd Street Promenade.. Image via Wikipedia Creative Commons

There are model developments in Southern California that foreshadow what kind of city these rules will generate. In such developments, the first floor belongs to cars. The buildings are a pleasant three stories tall, but the ambience bears no similarity to traditional cities around the Mediterranean. If aliens were to discover the ruins of such a city in the future, the joke goes, they would have to conclude that the cars were the masters, and humans lived on top to serve them.

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Site Plan from L.A.’s ADU design competition.. Image Courtesy of ADU design competition

Southern California needs different cities. They need not be tall, but they need to offer better qualities of life in walkable, denser environments. This can be done with middle-height, three- and four-story tall cities that exist all over the world and are highly desirable to live in.

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A subdivision development in Silverlake.. Image via Google Street View

Urban design and planning need to facilitate a design transition from post WWII automobile suburb toward this timeless urban form. The switch from suburban to urban has little, if anything, to do with building height. Also, the reference to timeless form need not mean that the buildings look historically referential (although they could). There are many examples around the world where a traditional urban context is used to host strikingly modern buildings of modest scale. Usually, these small new towns thrive and are appreciated by their new residents.

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Vallastaden, Sweden.. Image Courtesy of White Arkitekter

In an urban framework, the individual buildings are merely building blocks for the larger urban form. Such cities are filled with leafy boulevards and quiet mews, plazas, crescents, shared courtyards, and walled gardens, as if the urban form itself was a recognition of how precious open space is in denser cities, and that it’s the buildings’ job to protect that.

Urban form cannot be created one lot at a time, but it could be generated over several adjacent lots. This is where SB-9/10 does not go far enough. If setbacks must be maintained between buildings, then the paved-over car city is all that can emerge. But if adjacent property owners could agree to build, let’s say, a series of row houses, they could easily double the housing density and create a better quality of life with increased density. The single-family house for the city is a row house; there are lots of examples for them in almost every climate zone.

In areas near transit, one could also add small, urban, stacked apartment buildings. They look like row houses but are slightly larger, and typically have one apartment on each floor. These buildings often surround a shared inner courtyard, and the apartments then would have the advantage of offering natural cross-ventilation via front and back windows. People could sleep looking into the quiet inner courtyards with open windows. Again, this is a building type that constitutes much of the housing stock in cities around the world.

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Several apartments looking into a green, semiprivate courtyard in Amsterdam.. Image via Wikipedia Creative Commons

With these additional considerations, SB-9/10 not only would facilitate a transition to a denser Southern California, but also convert R-1 neighborhoods into more desirable places to live. Near transit, some streets could be slowed down for pedestrians or bikes. Slowly, a different way of moving around in the city would emerge, too.

The discussion about urban vs. suburban form is curiously absent in design discussions in California. In many places around the world, urban planners and architects are acutely aware of closed (urban, attached) and open (suburban, detached) building methodology, and they know when to switch from one to the other. Southern California is built mostly on the open building methodology, around automobiles. This needs to be intentionally transformed first. Once that decision has been made, there will need to be additional conversations about different zoning rules and additional building typologies. Eventually, this will benefit everybody and evolve the city to a higher capacity model. But these conversations will never happen if planners attempt to cling to the suburban framework and force that into higher densities.

There are few good local examples to illustrate how great a quality city, designed on the traditional model, could be. This makes urban change even harder, because in addition to solving the technical and legal problems of how to do this incrementally, one also must convince a highly skeptical public first of the eventual benefits of doing so.

If for no other reason, it must be done to lower our carbon footprint. There is a study that finds people in suburbs have a carbon footprint four times as large as people in cities. With climate change becoming a more and more urgent threat, we simply cannot afford to wait. With proper design guidance, SB-9/10 can be the beginning of an upward trajectory in the quality of urban life while simultaneously also solving many intractable, related problems. It’s time that Southern California embraced this kind of positive change, with the urgency it requires.

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Cite: Walter Jaegerhaus. "ADUs Are Not Enough for California" 05 Nov 2021. ArchDaily. Accessed . <https://www.archdaily.com/971385/adus-are-not-enough-for-california> ISSN 0719-8884

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