This article ran in the Summer 2021 issue of Hourglass Quarterly. View the full publication here.
Lancaster County is not building at the density outlined in Places2040, which is 7.5 units/acre. One challenge for building at a higher density is zoning. Another is misconceptions from neighbors that dense housing will change the character of their neighborhood, increase traffic, or other issues. What can Washington, D.C. teach us about tackling this challenge? A Brookings Institute Report.
On roughly 75% of land in most cities today, it is illegal to build anything except single-family detached houses. The origins of single-family zoning in America are not benign: Many housing codes used density as a proxy for separating people by income and race. But as communities across the U.S. grapple with worsening housing affordability, there is growing interest in how zoning rules could be relaxed to allow smaller, less expensive homes.
Often, the choice is posed as a trade-off between detached homes with big yards or skyscraping apartment towers. In reality, the housing stock in most communities is much more diverse than these two extremes. While high-rise apartments in strategic locations should be part of the solution, many single-family neighborhoods could easily yield more housing—and more affordable housing—if land use rules allowed “gentle” increases in density, such as townhomes, two- to four-family homes, and small-scale apartment or condominium buildings.
A D.C. example
Washington, D.C. has several predominantly single-family neighborhoods close to downtown that would offer perfect opportunities for gentle density. According to tax assessor data, the median lot size for single-family detached homes in the District is 5,460 square feet, compared to 1,600 square feet for rowhouses and 4,100 square feet for four- to six-unit multifamily buildings. This suggests that most single-family lots could accommodate more housing. The figure below shows some different scenarios for a 4,500 square foot lot, currently occupied by a two-and-a-half-story, 3,000 square foot single-family home including: the lot as is, redeveloped with three side-by-side townhomes, or redeveloped with a three-story, six-unit condo building.