Accessory Dwelling Units (ADUs)
- What are ADUs?
- New laws effective January 1, 2018
- Recent updates to state laws for ADUs - Includes webinar
- Technical Assistance Booklet - Includes FAQs and sample ordinances
- City and county ADU ordinances
- Sample materials from cities and counties
- Additional guidance
- External websites (contributors to Technical Assistance Booklet)
What are ADUs?
Accessory Dwelling Units (ADUs) are known by many names: granny flats, in-law units, backyard cottages, secondary units and more. No matter what you call them, ADUs are an innovative, affordable, effective option for adding much-needed housing in California.
What are the benefits of ADUs?
- ADUs are an affordable type of home to construct in California because they do not require paying for land, major new infrastructure, structured parking, or elevators.
- ADUs can provide a source of income for homeowners.
- ADUs are built with cost-effective wood frame construction, which is significantly less costly than homes in new multifamily infill buildings.
- ADUs allow extended families to be near one another while maintaining privacy.
- ADUs can provide as much living space as many newly-built apartments and condominiums, and they’re suited well for couples, small families, friends, young people, and seniors.
- ADUs give homeowners the flexibility to share independent living areas with family members and others, allowing seniors to age in place as they require more care.
New laws effective January 1, 2018
These bills, effective January 1, 2018, clarify and improve various provisions of the law to promote the development of ADUs, including allowing ADUs to be built concurrently with a single-family home, opening areas where ADUs can be built to include all zoning districts that allow single-family uses, modifying fees from utilities, such as special districts and water corporations, and reducing parking requirements.
Recent updates to state laws for ADUs
State legislation that took effect January 1, 2017 gave California cities more flexibility and latitude for allowing homeowners to build ADUs. Three separate bills were introduced and signed by Governor Brown; SB 1069 (Wieckowski), AB 2299 (Bloom), and AB 2406 (Thurmond). Each of these land use bills make it easier than ever for homeowners to take advantage of this attractive opportunity.
Webinar : Recent Legislation "Nuts and Bolts"
Technical Assistance Booklet
Download entire booklet (PDF)
Information for cities, counties, other local government bodies, and homeowners interested in adding an accessory dwelling unit to their property.
Download the entire booklet (PDF) or select one of the following excerpts:
New! Updated ADU booklet coming soon!
City and county ADU ordinances
Cities and counties are not required to create ordinances for ADUs; however, any city/county that does adopt an ADU ordinance, must submit the ordinance to HCD within 60 days.
Sample materials from cities and counties
- ADU flyer (PDF) - Sonoma County (to edit for your jurisdiction, download the Publisher version)
- Junior ADU flyer (PDF) - Sonoma County (to edit for your jurisdiction, download the Publisher version)
- ADU guidebook - City of Los Angeles
- ADU General Info Trifold (PDF) - Healdsburg
- ADU General Info Trifold (PDF) - City of Dublin (to edit for your jurisdiction, download the Publisher version)
- ADU General Info Trifold (PDF) - City of Fremont
- California State Fire Marshal (PDF) - Information bulletin regarding sprinkler system requirements.
- CalHFA (PDF) - Bulletin for ADU income which includes anticipated income from planned ADU to qualify for loan to create the ADU.
- 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) - April 18, 2017
- ADU guidance memo update (PDF) - November 20, 2017
- ADU Update: Early Lessons and Impacts of California's State and Local Policy Changes (PDF) – Provides an overview of ADUs as a housing solution for California. Covers recent policy changes at the state and local level, California's progress to date, and remaining barriers. Written by David Garcia at the Terner Center (U.C. Berkeley), December 2017
You'll find additional resources at the following websites, which are hosted by partners who contributed to HCD's Technical Assistance Booklet.
- Lilypad Homes - Resources to facilitate the development of accessory dwelling units that offer a more affordable housing option for both homeowners and renters. (Novato, CA)
- Accessory Dwellings - One-stop resource about accessory dwelling units. (Portland, OR)
- Second Unit Resources Center - Although focused on San Mateo County, this website can serve as a great model for other sites. It includes: