Abstract:Problem, research strategy, and findings: Accessory dwelling units (ADUs) are once again a hot topic, as communities across the United States face housing shortages and rising housing costs. For planners and policymakers attempting to facilitate ADU development, it is important to understand the homeowners who donot yet have one. Yet there is remarkably limited research on whether those homeowners are open to building an ADU, what motivations and obstacles they perceive regarding adding one, and why some homeowners do notwant to build one at all. We surveyed 502 single-family homeowners in the Sacramento (CA) metropolitan area to investigate those three questions. Our findings suggest that up to 47% of singlefamily detached homeowners in the city of Sacramento could be open to building an ADU. Homeowners’ top-ranked motivation for adding one was housing themselves, family, or friends in the future. Cost-related concerns ranked as the biggest perceived obstacles. Homeowners who did not want an ADU cited a mixture of logistical challenges and potentially more immutable personal preferences.
Takeaway for practice: Our findings suggest five lessons for planners. First, permissive regulation is an essential, but not sufficient, step toward addressing homeowners’ perceptions of regulatory obstacles. Second, local government regulations are not the only source of ADU restrictions. Third, even where ADUs are technically allowed, it can still be an arduous process to get one permitted. Fourth, cost remains a big obstacle to building ADUs. Fifth, homeowners—especially low-income households—need better financing options.

Key words: accessory dwelling units, housing, single-family zoning