Abstract
In urbanizing regions and metropolises world-wide, housing access is consistently a primary factor driving livability of cities and sustainable urban growth. Along with housing access and affordability, cities face shifting household composition, increasing vulnerabilities to severe weather events brought on by global warming, and accessibility and concerns about aging in place. Missing middle housing has been identified as a challenge to develop, but an important step towards improving affordable housing choices and creating vibrant and sustainable cities. Portland, Oregon, in an effort to increase the viability of missing middle housing production amidst an ongoing housing crisis, is in the process of implementing new local zoning regulations to increase housing production. The Residential Infill Project will increase development densities in residential areas across the city, allowing for development of one or two additional housing units in areas historically zoned single-family, making the construction of different – missing middle – housing types possible. The importance of this approach is that existing development can be incrementally retrofitted and adapted to meet changing and growing demands in housing. At the same time, the State of Oregon appears poised to be the first state to eliminate single-family zoning altogether. This paper will compare large-scale and incremental development approaches for spurring housing delivery and missing middle housing development with an aggregate approach favoring small-scale interventions. While the scale of housing delivery is important, current market rate and affordable housing development in Portland is dominated by large-scale housing development that, in the end, is either heavily subsidized or is characterized by monthly rents unaffordable to lower income and working families. While increasing housing supply is critical to long-term solutions to affordability and access, large-scale development favors large developers. Private incremental infill development on historically single-family neighborhoods may be a more effective and economically viable strategy – in an incremental fashion. The aggregated nature of this stands in stark contrast to large-scale multi-family housing construction. Research will look at recent and proposed Portland zoning amendments, including the Residential Infill Project, to promote higher density residential development through urban infill and urban small-scale redevelopment through the lens of housing delivery, affordability, and typology. Through geospatial analysis we will compare the comprehensive potential for aggregated versus large-scale development strategies to meet housing demand through missing middle housing production in the Portland Metro area.
