Frequently Asked Questions

Yes. An ADU created within the existing space of an accessory structure can be expanded beyond the physical dimensions of the structure up to 150 square feet solely for the purpose of accommodating ingress and egress. (Gov. Code, § 66323, subd. (a)(1)(A).) An example is the construction of a staircase to reach a second story ADU. The ADUs shall conform to setbacks sufficient for fire and safety. (Gov. Code, § 66323, subd. (a)(1)(C).)

NOTE: A JADU may be created within the walls of a single-family residence and not within an accessory structure. JADUs may not be expanded beyond the existing dimensions of the single-family dwelling.

For more information regarding 66323 multifamily accessory units, please see Multifamily ADUs.

Yes. School districts are authorized to, but do not have to, levy impact fees for ADUs larger than 500 square feet pursuant to Section 17620 of the Education Code and the Mitigation Fee Act (Gov. Code, § 66000). ADUs less than 500 square feet are not subject to school impact fees. Local agencies are encouraged to coordinate with school districts to carefully weigh the importance of promoting ADUs and to ensure appropriate nexus studies are conducted on fees to facilitate construction or reconstruction of adequate school facilities, as required by the Mitigation Fee Act. Local agencies should not withhold the issuance of a permit to create an ADU or JADU due to the imposition of school fees.

ADUs constructed 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 concurrently with a new single-family dwelling (Gov. Code, § 66324, subd. (b)). 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 (Gov. Code, § 66324, subd. (e)).

There is no limit on the number of stories contained in State ADU Law. A local agency must allow at least two stories, and an attached ADU may be built to the height of the zoning for the primary dwelling or up to 25 feet, whichever is lower. (Gov. Code, § 66321, subd. (b)(4)(D).)

The California State Geoportal features an interactive map and searchable database to assess whether any California address is within a High-Quality Transit Corridor (HQTC) (as described in Public Resources Code sections 21155, 21064.3, and 21060.2). This can assist with determining if your projects are eligible for an extra two feet in height. However, the State ADU Law does not designate a definitive resource for making HQTC proximity determinations. Applicants should go to their Metropolitan Planning Organizations first to find out if they are in a HQTC. If there is not one in their area, then they should go to their local agency.

No. An HOA may not influence a local agency’s ministerial approval of an ADU or JADU. Local agencies must provide an approval process that only includes ministerial provisions for the approval of ADU permit applications. This approval process shall not include discretionary processes, provisions, or requirements except as provided in Government Code section 66315. Thus, third party reviews by an HOA or their representatives or agents would violate State ADU Law. (Gov. Code, § 66315.) No other local ordinances, policies, or regulations may be applied in the approval or denial of an ADU or JADU permit application (Gov. Code, § 66317, subd. (c)). If a local agency allows an HOA to be involved in any part of an ADU or JADU application process, the local agency is in violation of State ADU Law.

Yes. The housing element must include a description of zoning available to permit ADUs, including development standards and analysis of potential constraints on the development of ADUs. The element must include programs to address identified constraints. In addition, housing elements must include a plan that incentivizes and promotes the creation of ADUs that can offer affordable rents for very low-, low-, or moderate-income households and requires HCD to develop a list of state grants and financial incentives in connection with the planning, construction, and operation of affordable ADUs. (Gov. Code, § 65583; HSC, § 50504.5.)

Yes. To qualify for a Prohousing Designation, a local agency must be in compliance with all applicable state housing laws, such as those mentioned in Government Codes section 65585, subdivision (j), which includes State ADU Law. An approved housing element and any associated programs which promote ADU development will also need to be enacted and in compliance to meet the minimum threshold requirements for a Prohousing Designation. Additionally, ADUs and JADUs are specifically identified within the Prohousing Designation Program as designation criteria under California Code of Regulations, Title 25, section 6606, meaning that an ADU ordinance or program which promotes ADU development beyond the minimum requirements of State ADU Law may score additional points towards their Prohousing Designation. In other words, local agencies that are in violation of State ADU Law will be ineligible for a Prohousing Designation, while local agencies that promote additional ADU development can score additional points towards their Prohousing Designation, and all the benefits that designation provides. (CCR Title 25, §§ 6600-6608).

Yes, a JADU is permitted in a half-plex. A half-plex consists of two primary dwelling units on separate lots that share a dividing wall. One JADU is permitted in each half-plex in areas zoned for single-family use. (Gov. Code, § 66333, subd. (a).) If two units are attached on a single lot (i.e., a duplex), the primary dwelling is considered multifamily and would not qualify for a JADU.

JADUs are required to be within the walls of the primary dwelling but are not required to have an interior connection to the primary dwelling. However, if the JADU does not include a separate bathroom, the JADU must include an interior entrance to the main living area. (Gov. Code, § 66333, subd. (e)(2).)

No, JADUs are not allowed in accessory structures. The creation of a JADU must be within the single-family residence. As noted above, “enclosed uses” within the residence, such as attached garages, are eligible for JADU creation. (Gov. Code, § 66333, subd. (d).)

No. Only ADUs that are created from existing accessory structures are allowed to add up to 150 square feet “beyond the physical dimensions of the existing accessory structure” to provide for ingress or egress (Gov. Code, § 66323, subd. (a)(1)(A)).

Yes. The owner must reside in either the remaining portion of the primary residence or in the newly created JADU. Owner-occupancy is not required when the owner is another governmental agency, land trust, or housing organization. (Gov. Code, § 66333, subd. (b).)

An efficiency kitchen is a cooking facility with appliances, a food preparation counter, and storage cabinets that are of reasonable size in relation to the size of the JADU (Gov. Code, § 66333, subds. (f)(1), (f)(2)). A local agency cannot be more restrictive than this definition. Thus, requirements such as counter or cabinet sizes, specified electrical or gas connections, or appliance types are not authorized by State JADU Law.

No. Local agencies may not require parking as a condition to permitting a JADU, even when the JADU is converted from an attached garage (Gov. Code, § 66334, subd. (a)).

Yes. Pursuant to Government Code section 66326, subdivision (a), local agencies are required to submit a copy of newly adopted ADU ordinances to HCD within 60 days of adoption. HCD may thereafter provide written findings to the local agency as to whether the ordinance complies with State ADU Law. If HCD finds that the ADU ordinance does not comply with State ADU Law, the local agency must respond to HCD’s written findings within 30 days. The local agency shall either amend its ordinance in accordance with HCD’s findings, or adopt the ordinance without changes, but include findings in its resolution explaining why the ordinance complies with State ADU Law despite HCD’s findings. (Gov. Code, § 66326, subd. (b).)

Although not required by State ADU Law, HCD may continue to offer further technical assistance to the local agency. However, if the local agency does not amend its ordinance in accordance with HCD’s findings or adopt a resolution explaining why the ordinance is compliant, HCD shall notify the local agency and may notify the Attorney General that the local agency is in violation of State ADU Law. (Gov. Code, § 66326, subd. (c)(1).) While an ordinance is non-compliant, the local agency shall apply state standards for the approval of ADUs, until the local agency adopts a compliant ordinance. (Gov. Code, § 66316.)

In addition, HCD may review, adopt, amend, or repeal guidelines to implement uniform standards or criteria that supplement or clarify State ADU Law (Gov. Code, § 66327).

No. Local agencies may choose not to adopt an ADU ordinance. Should a local government choose not to adopt an ADU ordinance, any proposed ADU development would be subject only to the standards set forth in State ADU Law. (Gov. Code, §§ 66315, 66316.) A local agency that adopts an ADU ordinance may impose objective development and design standards in compliance with Government Code section 66314.

Yes. A local government, upon adoption of an ADU ordinance, must submit a copy of the adopted ordinance to HCD within 60 days after adoption. After the adoption of an ordinance, HCD may review and submit written findings to the local agency as to whether the ordinance complies with the State ADU Law. (Gov. Code, § 66326, subd. (a).)

Yes. State ADU Law applies to a local agency, which is defined as a city, county, or city and county, whether general law or chartered (Gov. Code, §§ 66312; 66313, subd. (g)).

Possibly. The TRPA was formed through a bistate compact between California and Nevada, which elevates its authority above state laws. Under this authority, TRPA has adopted certain restrictions that effectively limit lot coverage on developed land. State ADU Law may conflict to a degree with the TRPA standards, and to the extent that it does, the TRPA law preempts or overrides State ADU Law.

For more information, please see: https://www.trpa.gov/adus/

Under Government Code section 66323, an applicant may apply to build up to eight detached ADUs (Gov. Code, § 66323, subd. (a)(4)(A)) and at least one conversion ADU within an existing multifamily dwelling and up to 25 percent of the number of units in the existing multifamily dwelling (Gov. Code, § 66323, subd. (a)(3)(B)).

No. JADUs may only be constructed on a site with a proposed or existing single-family dwelling in an area zoned for single-family residences; a JADU cannot be constructed on a multifamily site (Gov. Code, § 66333, subd. (a)).

Maybe. For more information on ADA standards as they apply to your specific dwelling, please contact the Division of Codes and Standards at HCDBuildingStandards@hcd.ca.gov.

Yes. A leasing office within an existing multifamily dwelling structure can be converted to at least one ADU – and up to 25 percent of the existing multifamily dwelling units – provided the ADUs comply with state building standards for dwellings. (Gov. Code, § 66323, subd. (a)(3)(A).)

In addition, a leasing office on a lot with an existing multifamily dwelling may be converted into up to eight detached ADUs, not to exceed the number of existing units on the lot and subject to height limitations in section 66321, subdivision (b), and to rear yard and side setbacks of no more than four feet. (Gov. Code, § 66323, subd. (a)(4)(A).

Finally, an ADU can be created from an accessory space, including a leasing office, that is either attached to or located within the multifamily structure or an accessory structure, or is detached from the primary dwelling and located on the same lot as the primary dwelling, and complies with other applicable standards. (Gov. Code, § 66314, subd. (d)(3).)

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 otherwise 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 of an ADU, or converted to an ADU, the local agency shall not require that those off-street parking spaces for the primary unit be replaced.

Examples include numeric and fixed standards such as heights or setbacks, or design standards such as specified colors or materials.

Subjective standards require independent judgement and are open to multiple interpretations. Language such as “privacy,” “compatibility with neighboring properties,” “promoting design harmony and balance,” “must maintain similar architecture style,” or requiring “high quality materials” are subjective and may not be imposed on ADU development.

Under the Permit Streamlining Act, and whether or not a local agency has adopted an ordinance, a local agency has 30 calendar days to determine whether or not an ADU application is complete. If an application is deemed incomplete, the local agency must provide an exhaustive list of items that were not complete. That list shall be limited to those items actually required on the lead agency’s submittal requirement checklist.

If the application is complete, it must be approved or denied ministerially within 60 days from the date the permitting agency received the complete application. Applicants are responsible for paying all applicable processing and permitting fees that may be due at the time of application.

ADUs and JADUs approved ministerially are statutorily exempt from CEQA pursuant to Section 15268 (Ministerial Projects) of the CEQA guidelines and Section 21080, subdivision (b)(1) of the Public Resources Code. In addition, ADUs can be categorically exempt from CEQA pursuant to Sections 15301 and 15303 of the CEQA guidelines, authority cited under Public Resources Code Sections 21083 and 21084. ADU and JADU ordinances are statutorily exempt from CEQA pursuant to Section 21080.17.

A ministerial review ensures that the permit application meets all the applicable objective standards effective at the time of the review and uses no discretionary judgment, opinion, or subjective standards.

Agency staff inspect the submitted application, site plan, and building plans for compliance with applicable standards. This often means that the permitting agency (i.e., planning, building, fire departments and utilities) reviews the application using only checklists.

Yes. If an applicant would like to request a delay on their application for any reason, they may do so. The 60-day period to approve or deny the permit shall be tolled for the period of the delay.

An ADU permit application is “deemed approved” when the permitting agency fails to approve or deny a completed application within 60 days of receiving a completed application.

Yes, property owners must obtain a Certificate of Occupancy from the local agency prior to any residential occupancy of an ADU or JADU.

A local agency shall not deny a permit for an unpermitted ADU that was constructed before January 1, 2020, due to the ADU being in violation of building standards, non-compliance with State ADU Law, or any local ordinance regulating ADUs. However, the local agency may deny the permit if the local agency makes a finding that correcting the violation is necessary to protect the health and safety of the public or occupants of the structure, or if the building is deemed substandard pursuant to section 17920.3 of the Health and Safety Code.

The permitting agency denying the application must provide the applicant a full set of comments listing items that are defective or deficient and include a description of how the application may be remedied. A full set of comments includes all comments from all reviewers, from every permitting agency. The 60-day countdown continues until the complete list is provided. A local agency which has provided a complete set of correction comments has fulfilled this requirement. Following a denial, a subsequent application resets the 60-day period.

The applicant may address the proposed remedy and resubmit the application to the permitting agency. A local agency may charge a fee to process a resubmitted application.

Questions and requests for technical assistance should be submitted through HCD’s ADU Portal, which is available on HCD’s ADU webpage: https://www.hcd.ca.gov/policy-and-research/accessory-dwelling-units. To reach the portal, navigate to “Contact the ADU Team.” Applicants should first work to address the denial with the permitting agency via the agency’s process. HCD may provide technical assistance after an application has been submitted. However, HCD may not respond or follow up with a permitting agency if there is no pending application.

Yes. A local agency may apply front yard setbacks for ADUs, but front yard setbacks cannot preclude an ADU of at least 800 square feet from being built on the property, even if that ADU would exist partially or wholly within the front setback.

Maybe. Local agencies may set objective standards, including front setbacks. However, a permitting agency may not require that an ADU of up to 800 square feet be built in an alternative location based on discretionary, or non-objective, standards. Requiring an alternative site, using objective standards, to comply with front setback requirements must not be overly burdensome such that it unreasonably restricts the ability of homeowners to create ADUs in zones in which they are authorized by local ordinance.

State ADU Law does not address the distance between an ADU and other structures on a lot. A local agency may impose objective development standards for the creation of some ADUs, and all ADUs must comply with local building codes. However, development standards should not unreasonably restrict the creation of ADUs. Minimum distance or other requirements may not be applied if they would unreasonably restrict the creation of ADUs, unless they are a requirement of a Building or Fire Code.

Limits on lot coverage or any floor area ratio requirements cannot preclude the creation of an ADU of at least 800 square feet that maintains four-foot rear and side setbacks. While floor area ratio and lot coverage requirements can be applied to other ADUs, such requirements must not unreasonably restrict the creation of ADUs.

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 a compliant 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. An efficiency unit may be as small as 150 square feet in floor area.

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.

No. A local agency's open space zoning requirements may not deny an ADU of at least 800 square feet with four-foot rear and side setbacks. In addition, 66323 Units are not subject to local open space and landscaping requirements in an ADU ordinance.

Yes. Local agencies may utilize a percentage (e.g., not greater than 50 percent) of the existing primary dwelling as a maximum unit size for attached ADUs, but only if it does not restrict an ADU’s size to less than 850 square feet, or 1,000 square feet for ADUs with more than one bedroom.

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

Objective standards related to height, lot coverage, landscape, design, development, and architectural standards in the local ADU ordinance do not apply to ADU conversions. However, since ADU conversions are created within an existing structure, the height of ADU conversions are limited to the dimension of the original structure. ADU conversions are not subject to setback requirements because they are created within an existing living area or are constructed in the same location and to the same dimensions as an existing structure. ADU conversions are subject to all applicable building, health and safety, and fire standards for dwellings.

Yes. The conversion of detached garages, sheds, and other existing detached accessory structures into ADUs is permitted by State ADU Law.

No. A homeowner applying for a permit for a previously unpermitted ADU or JADU constructed before January 1, 2020, shall not be required to pay impact fees or connection or capacity charges to obtain a permit if they provide written evidence that their household income does not exceed the definition of a low- or moderate-income household, as defined in Section 50093 of the Health and Safety Code.

No. An ADU ordinance shall provide that ADUs do not exceed the allowable density on the lot. Additionally, ADUs which conform to Government Code section 66314 shall not be considered to exceed the allowable density for the lot.

Yes. A project initially qualifies under the SDBL when the project’s “total units,” as defined in the SDBL (i.e., the number of units in the project before a density bonus is received) meet or exceed five units. Although the SDBL makes no mention of ADUs in its text, it likewise does not expressly narrow the definition of unit to exclude ADUs. Provided they are counted within the total units of the project, ADUs are a type of housing unit that may be counted for the purposes of achieving the five total unit minimum.

No. The calculation of a density bonus is based solely on a site’s maximum allowable residential density, which does not include ADUs. A density bonus is defined as “a density increases over the otherwise maximum allowable gross residential density…”. Maximum allowable residential density is defined as “the greatest number of units allowed under the zoning ordinance, specific plan, or land use element of the general plan.”

As an example, if the zoning ordinance allows up to two units and the general plan allows up to three, the applicable maximum allowable residential density (i.e., base density) on the site is three units, even though the addition of two ADUs brings the total units to five (see question above). The density bonus would then be calculated on top of a base density of three units, not five.

Yes. With an adopted ADU ordinance in compliance with State ADU Law, a local government may apply objective development and design standards that include, but are not limited to, parking, height, setback, landscape, architectural review, maximum size of a unit, and standards that prevent adverse impacts on any real property that is listed in the California Register of Historical Resources. These standards must be objective to allow ministerial review of an ADU. ADUs created under Government Code section 66323 shall not be subject to design and development standards except for those that are specified in section 66323.

Yes. ADUs are allowed within a historic district and on lots where the primary residence is subject to historic preservation. State ADU Law allows for a local agency to impose standards that prevent adverse impacts on any real property that is listed in the California Register of Historical Resources.

As with non-historic resources, an agency may impose objective standards that do not unreasonably restrict the creation of ADUs. Local agencies are encouraged to incorporate these standards into their ordinances and to submit these standards along with their ordinances to HCD.

The local or permitting agency must review and issue the demolition permit and ADU application at the same time. The applicant shall not be required to provide written notice or post a placard for the demolition of the garage unless the property is located in an architecturally and historically significant historic district.