Accessory Dwelling Units as a Policy Execution Challenge: Feasibility, Regulatory Risk, and Early-Stage Decision Modeling

Abstract

The United States faces a structural housing shortage estimated at 3.8 million units, and accessory dwelling units (ADUs) have emerged as a key policy instrument to expand housing supply within existing residential neighborhoods. Despite broad legislative support-including California's SB 9 and SB 10, and federal incentives under HUD's ADU pilot programs-actual ADU construction rates remain far below policy targets. This paper argues that the primary barrier is not construction capacity or design expertise, but rather uncertainty in early-stage feasibility determination. This study proposes a methodological framework for pre-design feasibility analysis that integrates parcel-level conditions, zoning parameters, regulatory constraints, and procedural requirements to identify viable development pathways and quantify regulatory risk prior to architectural engagement. By shifting feasibility assessment upstream in the development lifecycle, the approach reduces reliance on trial-and-error permitting, improves decision clarity for property owners, and lowers administrative burdens for local planning and building departments. A simplified case application using a prototypical Los Angeles parcel demonstrates the framework's practical utility. The proposed methodology positions early feasibility analysis as a foundational decision infrastructure supporting more consistent, scalable, and equitable housing policy execution across U.S. jurisdictions.