This story was reported by WAMU.
On just over 70% of the developable land in Northern Virginia, there’s only one thing you can build: a single-family detached house. That’s the lead finding of research into the region’s zoning restrictions from a group of scholars at George Mason University’s Mercatus Center.
“Single-family zoning is the bread and butter of local zoning restrictions in the US,” said Emily Hamilton, a senior research fellow on the project. “This is the most expensive type of housing, when only one house is allowed on a lot, versus more economical types of housing, like townhouses or apartment buildings that can economize on expensive land.”
Hamilton said the 70% figure is roughly in-line with other areas of the country, including further south in Hampton Roads. The research documents key zoning restrictions — like height limits, parking requirements and building footprints — across Arlington, Fairfax, Loudoun and Prince William counties, plus the city of Alexandria and the rest of the region’s independent cities and towns.
Hamilton and her colleagues’ work means Northern Virginia is now included in the National Zoning Atlas, a nationwide look at local zoning restrictions that dictate what can be built where. She said that’s significant at a moment when Northern Virginia — and the U.S. as a whole — is experiencing a pronounced housing shortage, which is driving up housing and rent prices and making it harder for middle- and low-income families to live in major metropolitan areas like the Washington, D.C., region.
The region is behind on the housing production goals set by the Metropolitan Washington Council of Governments for 2030 — goals set in 2019, after research from the Urban Institute suggested low housing supply and increasingly stratified housing costs could take a toll on the region’s overall economic prosperity.
For local policymakers interested in using zoning changes to add to the region’s housing supply, the zoning atlas research could provide a starting point, Hamilton said. And it gives researchers a jumping-off point for evaluating how different zoning restrictions impact housing supply and housing cost — and what changes might be most impactful.
By far the most high-profile such zoning changes have come in Arlington and Alexandria, where lawmakers voted recently to end single-family-only zoning and allow developers to choose to build small multi-unit buildings.
Those shifts came with significant community controversy. Some residents cheered them as an end to a legacy of exclusionary zoning, while others expressed concerns about the possible impacts of new residents on local infrastructure.
That debate is currently playing out in a court challenge in Arlington, which wrapped up a week-long trial last month; a similar lawsuit is pending in Alexandria.
Hamilton said the lawsuits — plus Arlington’s cap on the number of permits that can be issued for so-called "expanded housing options" or "missing middle" projects — mean the impact of those changes is uncertain, but likely modest.
“The amount of new housing [in Arlington] that comes in the form of duplexes or townhouses or small multiplexes in what were previously single-family zones can only add up to about the size of one big apartment building that gets built in Arlington all the time along our transit corridors,” she said. “So the public debate about this change to single-family zoning is really outsized relative to the amount of housing that it can produce.”
Hamilton and her colleagues looked at other zoning policies as well — like accessory dwelling units, which most Northern Virginia localities permitted years ago as a way of adding standalone residential units to existing single-family dwellings.
ADUs are currently permitted on 65% of developable land in Northern Virginia, including 77% of the land zoned for single-family detached homes.
But the jurisdictions that permit ADUs often attach further restrictions, including age and employment rules for residents; requirements that the homeowner must reside in the primary dwelling while someone else rents the ADU; and parking requirements.
Applying such rules to ADUs “severely [limit] their feasibility,” the researchers wrote.
For anyone who’s spent time in the highly competitive housing market around Washington, one finding from the research may feel a bit surprising: The region’s housing supply is better than that of many similar coastal cities, largely because of the area’s embrace of development oriented around suburban Metro stations.
“As a result, relative to some of its peers, the Northern Virginia region — and the D.C. area more broadly — have seen more housing construction, especially of multifamily housing, and have experienced less of an increase in prices and rents compared to some of those peer jurisdictions,” Hamilton said.
“That’s not to say, as our atlas shows, that Northern Virginia doesn’t have lots of opportunities to reduce barriers to lower costs for housing construction. But just to say that things could be worse.”
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