ADU FAQs

An Accessory Dwelling Unit (ADU) is a self-contained living unit that is secondary to the main house on a residential property. It is typically designed for independent living and has its own kitchen, bathroom, and entrance. ADUs are commonly used for rental purposes or to provide additional living space for family members or guests. The second unit is smaller than the main dwelling.

People build ADU for many reasons. Clients build ADU for the use as a long term rental property short term rental like AirBnB. Other clients have built them for family members retirement for multi generational living. Some clients build this for office space and extra guests.

An attached ADU is a living unit that is either contained within the walls of the primary dwelling i.e. conversion of garage or bedroom, or is newly constructed and shares a common wall with the primary dwelling.

A Junior ADU (or JADU) is a new category of dwelling units created by the State of California. There are several distinctions between a standard ADU and a JADU. The main difference is that a JADU is not required to have a dedicated bathroom.

Properties developed with a single-family residence may have one standard ADU (either attached or detached) and one Junior ADU.

The minimum unit size must comply with the requirements of the California Residential Code.

Yes. A local government may, by ordinance, establish minimum and maximum unit size requirements for both attached and detached ADUs; however, maximum unit size requirements must allow an ADU of at least 850 square feet, or 1,000 square feet for ADUs with more than one bedroom. For local agencies without an ADU ordinance, maximum unit sizes are 1,200 square feet for a new detached ADU and up to 50 percent of the floor area of the existing primary dwelling for an attached ADU (at least 800 square feet). Finally, the local agency must not establish by ordinance a minimum square footage requirement that prohibits the development of an efficiency unit as defined in Health and Safety Code section 17958.1.

The conversion of an existing accessory structure or a portion of the existing primary residence to an ADU is not subject to unit size requirements. For example, an existing 3,000 square-foot barn converted to an ADU would not be subject to the local unit size requirements, regardless of whether a local government has an adopted ADU ordinance. Should an applicant want to expand an accessory structure to create an ADU beyond 150 square feet, this ADU would be subject to the size maximums outlined in State ADU Law or in the local agency's adopted ordinance

Yes. Local agencies may utilize a percentage (e.g., 50 percent) of the primary dwelling as a maximum unitsize for attached ADUs, but only if it does not restrict an ADU's size to less than the standard of at least 850 square feet (or at least 1,000 square feet for ADUs with more than one bedroom). Local agencies shall not, by ordinance, establish any other minimum or maximum unit sizes, including limits based on a percentage of the area of the primary dwelling, that precludes an 800 square-foot ADU. Local agencies utilizing percentages of the primary dwelling as maximum unit sizes can consider multi-pronged standards to help navigate these requirements.

Yes. Maximum unit sizes can exceed 1,200 square feet for ADUs through the adoption of a local ADU ordinance. State ADU Law does not limit the authority of local agencies to adopt less restrictive requirements for the creation of ADUs.

Yes. Local agencies should be flexible when siting parking for ADUs. Off-street parking spaces for the ADU shall be permitted in setback areas in locations determined by the local agency or through tandem parking unless specific findings are made. Specific findings must be based on specific site or regional topographical or fire and life safety conditions.

When a garage, carport, or covered parking structure is demolished in conjunction with the construction ofan ADU, or converted to an ADU, the local agency shall not require that those off-street parking spaces for the primary unit be replaced.

No. Parking requirements for ADUs shall not exceed one parking space per unit or bedroom, whichever isless. These spaces may be provided as tandem parking on a driveway. Guest parking spaces shall not berequired for ADUs under any circumstances. a local agency may not impose any ADU parking standards.

There is no height limit contained in State ADU Law, but local agencies may impose height limits provided that the limit is no less than 16 feet. For a local agency to impose a height limit, it must do so through the adoption of a compliant ADU ordinance.

Yes, converting a garage into an ADU is a popular and affordable option. The new laws have made this process easier.

Yes. Local agencies may require that the property be used for rentals of terms longer than 30 days. ADUs permitted ministerially, shall be rented for terms longer than 30 days.

A limit on the number of bedrooms could be construed as a discriminatory practice towards protected classes, such as familial status, and would be considered a constraint on the development of ADUs. Building code standards for minimum bedroom size still apply.

No. An ADU is exempt from incurring impact fees from local agencies, special districts, and water corporations if less than 750 square feet. If an ADU is 750 square feet or larger, impact fees shall be charged proportionately in relation to the square footage of the ADU to the square footage of the primary dwelling unit.

For purposes of calculating the fees for an ADU on a lot with a multifamily dwelling, the proportionality shall be based on the average square footage of the units within that multifamily dwelling structure. For ADUs converting existing space with a 150 squarefoot expansion, a total ADU square footage over 750square feet could trigger the proportionate fee requirement.

Yes. Agencies can waive impact and any other fees for ADUs. Also, local agencies may use fee deferrals for applicants.

ADUs converted from existing space and JADUs shall not be considered by a local agency, special district, or water corporation to be a new residential use for purposes of calculating connection fees or capacity charges for utilities, unless constructed with a new single-family dwelling. The connection fee or capacity charge shall be proportionate to the burden of the proposed ADU, based on its square footage or plumbing fixtures as compared to the primary dwelling. ADU Law does not cover monthly charge fees.