Understanding the Motivations and Barriers to ADU Construction

As cities across the country grapple with a crisis of affordable housing, accessory dwelling units (ADUs) have garnered increased attention as opportunities to increase the rental housing stock while helping homeowners offset their housing costs. There has been significant interest and research into developing permissive regulations to enable ADU construction. However, there has been less emphasis placed on exploring why individual homeowners may or may not choose to build an ADU.

Sacramento Homeowners' Openness to ADUs

In "Exploring Homeowners' Openness to Building Accessory Dwelling Units in the Sacramento Metropolitan Area" (Journal of the American Planning Association, Vol. 89, No. 1), authors Jamey M. B. Volker and Susan Handy share findings from their survey of over 500 single-family homeowners. Their study was designed to uncover the factors motivating or deterring homeowners from building an ADU.

While only 8 percent of respondents reported currently owning an ADU on their lot, the authors estimated based on survey results that between 33.8 percent and 47.2 percent of single-family detached homeowners in the area might be open to building one.

Barriers to ADU Adoption in Sacramento

Given its rising home prices, tight housing market, and permissive regulatory environment, Sacramento homeowners face clear incentives to build ADUs for extra income. What then might account for the low rate of adoption?

Of the 460 survey-takers without an ADU, 246 of them affirmed that they do not want one, for reasons ranging from space constraints to privacy concerns to simple disinterest. However, for respondents who were potentially open to building an ADU, the survey revealed that cost barriers were most salient.

Most respondents rated construction costs and development fees as the "major obstacles." While difficulties securing financing were not ranked highly overall as an obstacle, Black and Hispanic respondents noted this as a larger concern than their white counterparts.

For planners interested in seeing ADUs proliferate in their communities, these findings show that changing the regulatory environment is an important piece of a larger puzzle. Ensuring that ADU regulations are permissive, clear, and widely understood could go a long way toward reducing barriers. However cost remains a clear issue, and the authors' disaggregation of the data showed that constraints like obtaining financing may impact homeowners differently along the lines of race and income. Addressing these concerns may require more creative, targeted policy and programmatic interventions.

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