Junior Accessory Dwelling Units (JADUs) are allowed to be created within the walls of a proposed or existing single-family residence and shall contain no more than 500 square feet. JADUs offer additional housing options. They may share central systems, contain a basic kitchen utilizing small plug-in appliances, may share a bathroom with the primary dwelling, all to reduce development costs. JADUs present no additional stress on utility services or infrastructure because they simply repurpose existing space within the residence and do not expand the dwellings planned occupancy.

Funding for Homeowners

CalHFA’s ADU Grant Program — The CalHFA ADU Grant Program provides up to $40,000 in assistance to reimburse homeowners for predevelopment costs necessary to build and occupy an ADU.

ADU Funding Laws

• The California Health and Safety Code (HSC), Section 65583(c)(7), requires that cities and counties develop a plan that incentivizes and promotes the creation of ADUs that can be offered at affordable rent for very-low to moderate-income households.
• As recapped below, HCD has developed a list of existing state grants and financial incentives in connection with the expenses for the planning, construction and operation of an ADU with affordable rent for very low to moderate- income households.
  • Potential State Grants and Financial Incentives for ADUs
    • CalHome Program — State funds to local public agencies and nonprofit corporations for first-time homebuyer mortgage assistance including a home purchase with an ADU or JADU; owner-occupied rehabilitation assistance including rehabilitation of ADUs or JADUs; ADU/JADU assistance including construction, repair, and reconstruction; and homeownership development project loans including predevelopment and carrying costs during construction related to ADUs and JADUs (HCD CalHome program)
    • Local Early Action Planning (LEAP) Grants — State grants to local jurisdictions including eligible partnerships for housing planning, and developing or improving an ADU ordinance in compliance with Section 65852.2 of the Government Code (HCD LEAP program)
    • Local Housing Trust Fund (LHTF) Program — Matching funds to local and regional housing trust funds. Funds may also be used for the construction, conversion, repair, reconstruction or rehabilitation of ADUs or JADUs (HCD LHTF program)
    • Regional Early Action Planning (REAP) Grants — Grants to council of governments (COGs) and other regional entities for activities relating to housing planning and activities including establishing Prohousing Policies such as adopting ADU ordinances or other mechanisms that reduce barriers for property owners to create ADUs (HCD REAP program)
    • SB 2 Planning Grants — Grants to local governments including eligible partnerships for housing planning and to encourage ADUs and other innovative building types through ordinances, outreach, fee waivers, pre-approved plans, website zoning clearance assistance, and other homeowner tools or finance tools (HCD SB2 program)
    • Community Development Block Grant Program (CDBG) — Federal funds allocated to non-entitlement jurisdictions, and non-entitlement jurisdictions that partner with non-federally recognized Native American communities for community development activities including single- and multi-family rehabilitation and potential local ADU rehabilitation and planning programs. Applicants must be income qualified in low- to moderate-income households for rehabilitation and areas for planning. Contact your local jurisdictions for more information.
  • Other Potential Grants and Financial Incentives for ADUs
    • San Diego Housing Commission ADU Finance Program — The program provides financial assistance in the form of construction loans (up to $200,000) and technical assistance (at no cost to the homeowner) that helps homeowners understand and complete the process of building an ADU.
    • City of Clovis: ADU Finance Program — Provides financing to eligible property owners seeking funding to build or repair ADUs on their existing single-family lot in the City of Clovis.
    • Santa Cruz County: ADU Forgivable Loan Program — Offers forgivable loans up to $40,000 to homeowners who rent ADUs to low-income households at affordable rents for up to 20 years.
    • San Mateo County: One Stop Shop Program — Provides no-cost support from Hello Housing with the design, permitting, and project management involved with building an ADU.
    • Monterey Bay: My House My Home Program — Creates affordable ADUs for low-income senior homeowners in the Monterey Bay area.
    • City of San Jose: Accessory Dwelling Unit Program — Provides pre-approved ADU plans and support for ADU construction.
    • City of Chico ADU Program — Provides pre-approved ADU plans and support for ADU construction.
    • Housing Trust Silicon Valley — Provides funding to support homeownership, rental housing, development financing, and offers programs for homeowners.

NEW: See the updated ADU Handbook for changes to State ADU Law. We also updated and expanded the FAQ section.

View the Accessory Dwelling Unit Handbook (PDF).

Vea la versión en español del Manual de Unidades de Vivienda Accesoria (PDF).

View the 2025 Accessory Dwelling Unit Handbook Webinar.

For additional assistance, please contact HCD’s ADU team.

Although cities and counties are mandated to permit ADUs and JADUs, they are not required to adopt ADU and JADU ordinances. However, any city/county that does adopt an ADU ordinance, must submit the ordinance to HCD within 60 days.

Requests for adopted ADU ordinances may be submitted here:

Request an Ordinance

• ADU Technical Assistance and Ordinance Review Letters (XLS)
  • HCD ADU Ordinance Review Letters — HCD’s review of draft ADU ordinances as well as proposals to explore and allow a variety of housing choices, including "movable" tiny homes (Placer County and the City of Los Angeles).
  • Responses from Jurisdictions — Jurisdictions are required to provide a response letter to HCD within 30 days of HCD’s ADU Ordinance Review Letter. The spreadsheet indicates whether a response letter was received.

• California State Fire Marshal (PDF) — Information bulletin regarding sprinkler system requirements.
• California Energy Commission updates for ADU:
  • Blueprint Newsletter Issue 129 January 2020 – March (PDF) — ADUs and adoption of 2019 Energy Code: PV (solar panel) Requirements for ADUs
• California Department of Housing and Community Development (PDF) — Information Bulletin providing clarification and outlining provisions of various residential types, ranging from recreation vehicles and manufactured homes to site-constructed California
• Building Standards Code dwellings.
• For ADUs in Coastal Commission areas:
  • ADU guidance memo for planning directors in coastal cities and counties (PDF) — January 21, 2022

Guidance from ADU Handbook contributors

You'll find additional resources at the following websites, which are hosted by partners who contributed to HCD's Technical Assistance Booklet.

• Casita Coalition — ADU Best Practices Guidebook
• Casita Coalition — The statewide cross-sector nonprofit offers free downloads of ADU guidance memos for practitioners and homeowners on their Guidebooks and Resources page [casitacoalition.org], including guidebooks on Legalizing an Unpermitted ADU, SB 9 Two-Unit Developments and Lot Splits, Multifamily ADUs, ADU Best Practices, ADU Financing, and Garage Conversions.

Materials from Cities and Counties

• Learn about creating an ADU in Napa or Sonoma County, including informative webinars Napa Sonoma ADU
• Learn about creating an ADU in San Mateo County, San Mateo ADU
• ADU plans available from cities and counties:
  • Clovis Old Town Cottage Home Program (PDF)
  • Del Mar Sample ADU Floor Plans
  • City of Fresno ADU Program and Pre-approved Plans
  • Stockton ADU Studio
  • Stockton ADU 1 Bedrooms
  • Stockton ADU 2 Bedrooms
• Pre-approved ADU plans, and a “Guide to Building Accessory dwelling Units” from the City of Stockton
• “ADU Educational Workshop” — Virtual ADU educational workshops, including planning, permitting, building, financing and property management
• ADU amnesty program, with an ADU idea book and cost estimator, in San Mateo County for existing ADUs constructed without necessary permits and approvals. — ADU amnesty program
• Discover the potential for an ADU on your property. Lot and zoning information by simply providing your address — ADU possibilities on your lot
• ADU Resource Center the American Institute of Architects (AIA)
• The ABCs of ADUs (PDF) — A guide to Accessory Dwelling Units and how they expand housing options for people of all ages (from AARP)
• Clovis Cottage Home Program (PDF) — Promotion of infill residential development on qualified properties in the Old Town area with city provided floor plans, building permit package and fee-waived checked plans
• Accessory Dwellings — One-stop resource about accessory dwelling units. (Portland, OR)
• Everything About Building ADU in Los Angeles — Although the City is still in the process of adopting an ADU ordinance, this fact sheet provides guidance for types of ADU, parking, current building codes, cost estimates, potential rental rates and more.
• Second Unit Resources Center — Although focused on San Mateo County, this website can serve as a great model for other sites. It includes:
  • Ideas, Stories, and Photos
  • How to Build an ADU — A step-by-step guide from design to move-in
  • Second Unit Calculator — Calculate typical costs, rents, and more
  • Idea Book (PDF)
  • Workbook (PDF)
• low- and moderate-income homeowners, additional financial tools are needed to facilitate the creation of ADUs.