Lewis & Parker: Making the case for more housing diversity, density

For decades, land use regulation across the U.S. has emphasized single-family houses on large lots.

This approach has priced many people out of the quintessential American dream — homeownership. It also has contributed to suburban sprawl — a pattern of low-density, car-dependent development dominating growth at the edges of urban areas since the end of World War II.

Now, however, Americans may be starting to question the desirability of owning a home of their own. In response, some government entities, including the city of Minneapolis and state of Oregon, have begun allowing duplexes and other types of multi-unit housing in neighborhoods previously reserved for single-family housing. The state of Virginia has also been entertaining the idea, and several Democratic presidential candidates included such zoning changes in their housing policies.

Headlines have been predicting a housing revolution in response. But based on our research, it appears that while attitudes about suburban life may be evolving, the transition from single-family housing may prove slow and difficult in practice.

Guest Writer

Rebecca Lewis is an associate professor of planning, public policy and management. She holds a master’s in environmental policy and doctorate in urban and regional planning from the University of Maryland.

Elected officials are reconsidering single-family zoning in response to constituents’ concerns about cost, sprawl and social isolation.

Other academic research focuses on promotion of discrimination and exclusion. Ours concentrates on environmental impacts.

Guest Writer

Robert Parker serves as executive director of the University of Oregon’s Institute for Policy Research and Engagement. Over the last 30 years, he has managed more than 400 policy and planning analysis projects around the state. He is also a principal in the university’s Economic Development Center.

Dozens of studies have shown sprawl is energy-intensive, largely due to the demands it places on transportation. They also show it consumes too much land, degrades air and water quality, reduces species diversity and contributes to climate change.

We have examined how Oregon’s land use policy affects residential density along with its housing affordability crisis.

Oregonians despise density, because they value privacy and space. But they also abhor sprawl, because it uses valuable agricultural land. So Oregon would seem to be the ideal starting point for policies curbing single-family zoning.

One of Oregon’s 19 statewide land use planning goals, adopted in the early 1970s, addresses housing. It requires cities to include an array of housing types.
However, exclusive single-family neighborhoods still dominate Oregon’s landscape today.

In the early 1970s, in what came to be named “the quiet revolution in land use control,” some states started taking back authority over zoning previously ceded to cities and towns.

In 1973, Oregon created urban growth boundaries — lines of demarcation between urban and rural land uses — around each of its cities. It also enacted other measures to contain growth and prevent sprawl.

Our research reveals this approach taken at the state level has helped contain urban growth and promote more efficient land use.

Single-family density in urban growth boundaries, as measured by single-family housing units per acre, has consistently increased since the zones were created. Statewide, single-family density rose 22% between 1993 and 2012.

Still, sprawl exists within urban growth boundaries.

We have found that land exclusively zoned for single-family homes can support no more than eight to 10 units per acre. And as demand for houses exceeds supply, lower-income families are pushed into cheaper areas farther from their work.

Up for Growth, a national coalition that advocates for denser development, estimates only 89 housing units were built in Oregon for every 100 households formed from 2000 through 2015. And the emphasis remains on single-family, which currently accounts for 63% of Oregon’s total housing inventory.

Multi-family options also remain in short supply, driving prices higher. A 2019 Harvard University study concluded the supply of low-cost rental units — under $800 per month — had fallen 44% in Oregon between 1990 and 2017.

These issues aren’t limited to Oregon, of course.

According to the Harvard Joint Center on Housing, 47% of renter households nationwide are paying more than 30% of their income for housing costs. And overall, new residential construction remains below the rates prevailing prior to the recession of 2008-09.

Between 2000 and 2015, the U.S. underproduced 7.3 million units of housing, meaning families across the country are struggling to find accommodations both affordable and available. This shortage spanned 22 states and the District of Columbia.

Public officials are recognizing how giving primacy to single-family housing creates equity problems.

Single-family zoning segregated neighborhoods after World War II by pricing African American families out of middle-class areas. Most new single-family houses still feature at least a two-car garage, and the median floor space measures almost 2,400 square feet, so the problem continues.

Today, demand is increasing for smaller, connected houses within walking distance of services, including duplexes, triplexes and fourplexes. Many people like living this way.

However, as architect and urban designer Daniel Parolek has shown, regulatory barriers deter builders from producing more of these types of housing, which he terms the “missing middle.” As Parolek points out, many diverse housing types common in older neighborhoods, including duplexes and triplexes, are illegal under most current zoning codes.

All these factors helped spur Minneapolis and Oregon away from single-family zoning and allow more housing types. But for all the attention their actions have received, we predict the impact will be modest.

Housing markets are complex. They are affected by much more than zoning. So there is no guarantee costs will actually decline if policymakers succeed in encouraging more construction of diverse “missing middle” dwelling types.

But this does not mean changing zoning policies is misguided. Promoting construction of broader ranges of housing creates more vibrant neighborhoods, reduces conversion of farm and forest land for suburban development, reduces infrastructure costs and provides more equitable housing opportunities for all.
From The Conversation, an online repository of lay versions of academic research findings found at https://theconversation.com/us. Used with permission.