Emily Hamilton is a senior research fellow and director of the Urbanity Project at the Mercatus Center at George Mason University in Arlington.
Similar debates are happening in prosperous cities and towns across the United States, where a lack of options has workers and families living beyond their means, in cramped quarters or on the wrong side of packed freeways and far-flung suburbs. Opponents of permitting more moderate housing density — the type that falls between single-family houses and high-rises — argue that it would harm the environment, increase prices and require higher taxes. But research shows the naysayers are wrong on all three counts.
Many of Arlington’s single-family neighborhoods have a lovely tree canopy, and some local environmentalists oppose permitting more units where trees might be eliminated. A state law gives localities the authority to mandate more tree-canopy coverage on lots zoned for fewer units per acre, but the proposed new structures in Arlington would not exceed the size of single-family structures. This limits the extent to which adding missing middle housing would reduce the tree canopy.
The focus on individual plants, however, misses the forest for the trees. National environmental groups and climate scientists agree that places like Arlington — with Metro service, walkable neighborhoods and proximity to the region’s job centers — are the most environmentally friendly places to build new housing. Building in Arlington is better for the environment on every margin relative to walling off its neighborhoods, creating further pressure to clear cut forests at the edge of the region and expecting drivers to burn fossil fuels getting there. Further, missing middle homes usually share walls and roofs and are less energy-intensive to heat and cool than single-family houses.
Others argue that permitting more missing middle construction will increase housing costs because new construction might replace the county’s oldest, least-expensive single-family houses. But both basic economics and real-world evidence show that banning housing construction does not, in fact, improve housing affordability. Houston is the U.S. city that’s seen by far the most missing middle construction in recent decades, in the form of small-lot houses. Partly as a result, Houston’s median house price is below the nation’s, despite decades of rapid local economic and population growth.
And, as anyone who lives in Arlington can see, current zoning makes it profitable for home builders to tear down small houses and replace them with new single-family houses that are some of the most expensive in the region. New construction costs would be lower with duplexes, triplexes and other, more affordable options allowed.
Finally, some critics have raised concerns that missing middle construction and accompanying population growth will lead to higher property tax rates for Arlington’s current residents. But permitting more housing to be built along existing streets, bike lanes, sewers and parks mean that more people will be sharing and paying for existing infrastructure. For example, the borough of Palisades Park, N.J., permits widespread duplex construction while surrounding towns don’t, and it has the lowest property tax rates among its neighbors. In the 1990s, Palisades Park policymakers imposed a brief moratorium on new duplexes. Property values fell and property tax rates rose, and the moratorium was quickly overturned.
Townhouses, duplexes and other types of missing middle make up the core of the housing stock in many of the country’s oldest and most-beloved neighborhoods. Widespread single-family-home zoning, however, largely prevents their construction today. Missing middle housing is one key component of solving the housing affordability problem in the D.C. region.