Accessory Dwelling Unit (ADU) Technical Assistance Guidance, Memos & State Law Resources

This template ordinance helps jurisdictions adopt or update a local ordinance that complies with current California ADU and JADU law. It incorporates laws from the 2025 legislative session and HCD's March 2026 ADU Handbook. Annotations explain key provisions, and optional language supports jurisdictions that want to go beyond minimum requirements.

Since January 1, 2020, the state has enacted several Accessory Dwelling Unit (ADU) and Junior Accessory Dwelling Unit (JADU) laws to ease requirements and encourage the development of new housing units. These laws define what is considered an ADU and a JADU, set objective standards and set requirements for ministerial review for ADU and JADU projects. This summary includes information about the state law requirements, how to comply, and ways jurisdictions may go above and beyond state law to support ADU and JADU development.

This is a template application checklist for applicants seeking to legalize unpermitted ADUs. It may also be used by staff as an inspection checklist for unpermitted ADUs seeking permits

Accessory Dwelling Units (ADUs) can be a valuable strategy for meeting local housing goals. While ADUs are often less expensive to build and rent than other forms of housing, costs remain high. ADU affordability programs help by providing financial and other incentives for qualified homeowners, which can increase production and housing options, particularly for low- and moderate-income households.

This memo provides guidance on incentives, supporting low-income homeowners and designing an ADU Affordability Program. It includes Checklists for Developing an ADU Affordability Program, program Examples and Case Studies.
 

Accessory Dwelling Units (ADUs) can be a valuable strategy for meeting local housing goals. Per California state law, jurisdictions may allow ADUs to be subdivided into condominium units with distinct ownership. This guide outlines the key legal provisions, potential benefits and pitfalls, as well as implementation steps for jurisdictions. Drawing from experiences in Seattle and Portland, as well as California programs in San José, Martinez, Berkeley and San Diego, this guide provides actionable insights for launching local ADU condominium programs. 

This memo provides guidance on developing and implementing an Accessory Dwelling Unit (ADU) and Junior Accessory Dwelling Unit (JADU) legalization or amnesty program. Under California state law, jurisdictions must allow homeowners to legalize most ADUs and JADUs originally built before January 1, 2020, without the required permits. However, jurisdictions have considerable flexibility in program implementation.

The Regional Housing Technical Assistance (RHTA) Program convened an Accessory Dwelling Unit (ADU) Work Group in 2024-25, offering five webinars for jurisdictions looking to encourage ADU development and comply with state ADU laws. This memo builds on the information shared through the Work Group sessions and provides an overview of opportunities to improve ADU policies, processes and public information while meeting the requirements of state laws. ADUs can be a key piece of local housing strategies, filling unmet needs in the housing market and empowering homeowners to help house their neighbors.