An Accessory Dwelling Unit (ADU) is accessory to a primary residence and has complete independent living facilities for one or more persons and has a few variations:

  • Detached: The unit is separate from the primary dwelling unit.
  • Attached: The unit is attached to the primary dwelling unit.
  • Converted Existing Space: Converted Existing Space: Converts an existing structure or space into an independent living unit.
  • Junior Accessory Dwelling Unit (JADU): A specific type of conversion of existing space that is contained entirely within the walls of an existing or proposed single-family residence with direct access to the primary dwelling.

Yes, subject to demonstraiting compliance with applicable requirements. In Government Code Section 65852.150, the California Legislature found and declared that, among other things, allowing ADUs in zones that allow residential single-family and multifamily uses provides additional rental housing and is an essential component in addressing California’s housing needs. Over the years, State ADU Law has been revised to improve its effectiveness at creating more housing units. Changes to State ADU Law effective January 1, 2021, further reduce barriers, streamline approval processes, and expand capacity to accommodate the development of ADUs and JADUs.

Yes. Cities and counties are mandated to permit ADUs on all single-family and multi-family residential zoned lots. JADUs are only permitted on single-family residential zoned lots.

State law requires an ADU to be a minimum of 800 square feet for a studio or one-bedroom unit or up to 1,200 square feet for two or more bedrooms. Local jurisdictions may set maximum size for a two or more bedroom unit. Also, “Attached ADUs cannot be larger than 50% of the main dwelling unit on the property, and JADUs cannot exceed 500 square feet.

New units must be at least four feet from the side and rear lot lines. In certain instances front-yard setbacks can be required. Converted ADUs do not have a minimum setback requirement.

The height of a detached ADU can be up to 16 feet, or 18 feet if the parcel is within one-half mile walking distance of a major transit stop or on a lot with a multi-family or multi-story dwelling. An attached ADU can be up to 25 feet high or the allowed height for a single-family or multi-family dwelling, whichever is lower. An ADU can be two stories.

Yes. This is called an ADU conversion.

The construction cost for ADU in California can range from $60,000 to $360,000. The range is based on the unit’s square footage, site conditions, building materials and finishes. Additional costs include plans, permit fees and development impact fees.

ADUs are subject to State ADU Law subject must be considered, approved, and permitted ministerially, without discretionary action. The 60-day review period is subject to objective development standards and does not require a hearing. Any ordinance regulating the issuance of variances or special use permits and must be considered ministerially. (Gov. Code § 65852.2, subds. (a)(3) and (a)(4).)

Many jurisdictions require that an ADU be “architecturally compatible” with the primary home and sometimes the surrounding neighborhood. These are commonly referred to as “design requirements.” It is important to become familiar with your jurisdiction’s design requirements before beginning the design process.

The updates to State ADU Law removed the owner-occupancy requirement for newly created ADUs effective January 1, 2020. The new owner-occupancy exclusion is set to expire on December 31, 2024; however, local agencies may not retroactively require owner-occupancy for ADUs permitted between January 1, 2020, and December 31, 2024. However, should a property have both an ADU and JADU, JADU law requires owner occupancy of either the newly created JADU or the single-family residence. Under this specific circumstance, a lot with an ADU would be subject to owner-occupancy requirements. (Gov. Code, § 65852.22, subd. (a)(2).)

Yes. However, cities can prohibit rentals of less than 30 days. And cities may have other rental restrictions.