Using Accessory Dwelling Units (ADUs) to Satisfy RHNA

This technical memo describes how to use accessory dwelling units (ADUs) as part of your Housing Element Sites Inventory section.

In partnership with Bay Area jurisdictions, the Association of Bay Area Governments (ABAG) has been administering an affordability survey to learn more about the rents of newly built ADUs. In 2024 and 2025, participating jurisdictions distributed the survey as part of the permitting process. This data is complimented by similar studies in Oakland and San José. 

This memo provides guidance on reporting Accessory Dwelling Unit (ADU) affordability in the 2024 Annual Progress Reports (APRs) due April 1, 2025.

This memo uses and extends the 2022 UC Berkeley report “Implementing the Backyard Revolution: Perspectives of California’s ADU Homeowners” to  provide a foundation that Bay Area jurisdictions may build upon as they consider ADU affordability levels while developing their Housing Element sites inventory analyses.