Frequently Asked Questions

HCD uses the term “66323 Units” to refer to ADUs and JADUs that are created pursuant to Government Code section 66323. They have also been referred to as “State mandated” or “State exempt” ADUs. Government Code section 66323 creates four categories of ADUs (and JADUs) that must be approved ministerially and are not subject to standards set forth in Government Code sections 66314-66322. For example, 66323 Units do not have to comply with lot coverage, front setbacks, and design standards. However, these ADUs must comply with building code and health and safety requirements for dwellings. The four categories are:

1. Single-Family Converted ADUs and JADUs

One ADU per lot is permitted within the converted space of a proposed or existing single-family dwelling or accessory structure. This type of ADU must have exterior access and setbacks for fire and safety but is not subject to a four-foot side and rear yard setback. (Gov. Code, § 66323, subd. (a)(1).)

ADUs converted from accessory structures are eligible for a 150 square-foot expansion to accommodate ingress and egress. For example, if a second story from a single-family dwelling is converted into an ADU, a stairwell of not more than 150 square feet could be added, among other types of ingress and egress configurations that comply with the local building code. (Gov. Code, § 66323, subd. (a)(1)(A).)

In addition, one JADU per lot is permitted within the proposed or existing space of a single-family dwelling or accessory structure and must have exterior access, side and rear setbacks for fire and safety. (Gov. Code, § 66323, subd. (a)(1).) JADUs must also comply with the provisions of JADU Law found in Government Code sections 66333-66339. For the purposes of constructing a JADU, attached garages are part of a single-family dwelling. (Gov. Code, § 66333, subd. (d).) For more information, please see the Handbook section on JADUs.

2. Single-Family Detached ADUs

One detached new construction ADU that does not exceed four-foot side and rear yard setbacks is permitted on lots with an existing or proposed single-family dwelling (Gov. Code, § 66323, subd. (a)(2)). The maximum unit size is 800 square feet with a height limitation of 16, 18, or 20 feet depending on conditions specified in Government Code section 66321, subdivision (b)(4). (Gov. Code, § 66323, subd. (a)(2)(B).)

3. Multifamily Converted ADUs

ADUs may be created within the portions of existing multifamily structures that are not used as livable space (Gov. Code, § 66323, subd. (a)(3)(A)). Local agencies shall allow at least one ADU within an existing multifamily dwelling and up to 25 percent of the existing multifamily dwelling units (Gov. Code, § 66323, subd. (a)(3)(B)). Examples of structures that are not used as livable space include, but are not limited to: storage rooms, boiler rooms, passageways, attics, basements, or garages (Gov. Code, § 66323, subd. (a)(3)(A)).

4. Multifamily Detached ADUs

Up to two detached ADUs are allowed on a lot that has a proposed multifamily dwelling, or up to eight detached ADUs are allowed on a lot with an existing multifamily dwelling, not to exceed the number of existing units on the lot. These ADUs are subject to four-foot rear and side yard setbacks and height limits of 16, 18, or 20 feet depending on conditions specified in Government Code section 66321, subdivision (b)(4). (Gov. Code, § 66323, subd. (a)(4)(A).) A local agency may not require that a setback be modified for an existing multifamily dwelling with setbacks less than four feet as a condition of ADU application approval (Gov. Code, § 66323, subd. (a)(4)(B)).

The local agency must allow the four categories of ADUs listed above to be combined as allowed by the site and lot conditions. For example, pursuant to Government Code 66323, subdivision (a), local governments must allow units created pursuant to subparagraphs (1) and (2) together or (3) and (4) together.

This means that on single-family lots, local agencies must allow at least one ADU constructed from existing space, one JADU, and one newly constructed detached ADU. For multifamily lots, local agencies must permit at least one ADU constructed from existing non-livable space (or up to 25 percent of the number of multifamily units), and two detached ADUs.

A local agency may not impose development or design standards, including both local standards and standards found in State ADU Law, on 66323 Units that are not specifically listed in Government Code section 66323. (Gov. Code, § 66323, subds. (a), (b).) This includes, but is not limited to, parking, height, setbacks, or other zoning provisions (e.g., lot size, open space, floor area ratio, etc.).

Additionally, rentals of 66323 ADUs must be for terms longer than 30 days. (Gov. Code, § 66323, subd. (e).) Fire sprinklers are not required for the ADU if not required for the primary residence, and the construction of an ADU may not trigger the requirement for fire sprinklers in an existing multifamily dwelling. (Gov. Code, § 66323, subd. (d).)

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.

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 (Gov. Code, § 65008). Building code standards for minimum bedroom size still apply.

A limit on the number of bedrooms could be construed as a discriminatory practice towards protected classes, such as familial status, (Gov. Code, § 65008) and could also unreasonably restrict the ability of homeowners to create ADUs (Gov. Code, § 66311). Building code standards for minimum bedroom size still apply.

An ADU application pursuant to Government Code section 66314 may be denied due to building code violations on the primary unit only if the violations present a threat to public health and safety and are affected by the construction of the ADU (Gov. Code, § 66322, subd. (b)). However, all ADUs must comply with building code and health and safety requirements for dwellings.

Yes. ADU laws apply to jurisdictions in the California Coastal Zone, but do not alter or lessen the effect or application of Coastal Act resource protection policies (Gov. Code, § 66329). Coastal localities should seek to harmonize the goals of protecting coastal resources and addressing housing needs of Californians. For example, where appropriate, localities should amend Local Coastal Programs for California Coastal Commission review to comply with the California Coastal Act and new State ADU Laws.

For more information, see the California Coastal Commission 2020 Memo and reach out to the local Coastal Commission district office.

No. A local agency cannot impose a deed restriction on an ADU. Government Code section 66315 states, “Section 66314 establishes the maximum standards that a local agency shall use to evaluate a proposed accessory dwelling unit on a lot that includes a proposed or existing single-family dwelling. No additional standards, other than those provided in Section 66314, shall be used or imposed, including an owner-occupant requirement, except that a local agency may require that the property may be used for rentals of terms 30 days or longer.” Section 66314, subdivision (b)(1) allows for local objective standards, but the examples provided all relate to design and development standards (e.g., parking, height, setback, landscape, maximum size of a unit). A deed restriction is not such a standard and thus cannot be imposed.

Yes. A local agency may adopt an ordinance for the creation of JADUs (Gov. Code, § 66333). That ordinance must “[r]equire the recordation of a deed restriction” that includes only a prohibition on the sale of the JADU separate from the sale of the single-family residence and a restriction on the size and attributes of the JADU that conforms with state law (Gov. Code, § 66333, subds. (c)(1), (c)(2)).

Impact fees charged for the construction of ADUs must be determined in accordance with the Mitigation Fee Act and include any monetary exaction other than a tax or special assessment that is charged by a local agency in connection with the approval of an ADU for the purpose of defraying all or a portion of the cost of public facilities relating to the ADU. (Gov. Code, §§ 66324, subd. (a); 66000.) A local agency, special district, or water corporation shall not consider ADUs as a new residential use for the purposes of calculating connection fees or capacity charges for utilities, including water and sewer services. However, these provisions do not apply to ADUs that are constructed concurrently with a new single-family home. (Gov. Code, § 66324, subds. (b), (d).)

No. An ADU is exempt from incurring impact fees from local agencies, special districts, and water corporations if it is 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. (Gov. Code, § 66324 subd. (c)(1).) In this specific instance, impact fees also include Quimby fees specified in Government Code section 66477 (Gov. Code, § 66324 subd. (c)(2)).

For ADUs that include a 150 square-foot exterior expansion, the 150 square feet count towards the 750 square-foot limit. For example, a 700 square-foot interior conversion ADU with 23 a 150 square-foot exterior expansion for ingress and egress would count as an 850 squarefoot ADU for the purposes of calculating fees, thus triggering the proportionate fee requirement of Government Code section 66324, subdivision (c).

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)).

Only when sprinklers are required for the existing primary residence. Installation of fire sprinklers shall not be required in attached, detached, or converted ADUs if sprinklers are not required by building codes for the existing primary residence. For example, a detached singlefamily home designed and constructed decades ago would not have been required to have fire sprinklers installed under the applicable building code at the time. However, if the same primary dwelling recently underwent significant alteration and is now required to have fire sprinklers, any ADU created after that alteration must be provided with fire sprinklers. Additionally, the construction of an ADU under this code section shall not trigger a requirement for fire sprinklers for the primary residence. Finally, if a primary dwelling currently does not have fire sprinklers, and an attached ADU is proposed which would trigger fire sprinkler requirements due to the increase in livable space, that requirement shall not be imposed upon the primary dwelling unit. (Gov. Code, §§ 66314, subd. (d)(12); 66323, subd. (d).)

Possibly. While at the time of this writing the funds have been exhausted, the California Housing Finance Agency’s (CalHFA) ADU Grant Program provided up to $40,000 in assistance to reimburse qualifying homeowners for predevelopment costs necessary to build an ADU or JADU on a lot with an owner-occupied single-family dwelling unit. The ADU Grant Program was intended to create more housing units in California by providing a grant to reimburse qualifying homeowners for predevelopment costs. Predevelopment costs include, but are not limited to, architectural designs, permits, soil tests, impact fees, property surveys, and energy reports.

Some local agencies are creating funding opportunities for ADU/JADU predevelopment and construction costs, or they are waiving fees.

For local agencies wanting to apply for funding for ADUs and JADUs, some of HCD’s funding programs, such as the CalHome Program, the Permanent Local Housing Allocation program, the Prohousing Incentive Program, and the Local Housing Trust Fund Program, do include funding for these housing types as eligible activities.

For more information on local and state funding opportunities for ADU/JADU predevelopment or construction, or funding options for local agencies, please see the Grants and Funding section of our ADU webpage: https://www.hcd.ca.gov/policy-and-research/accessory-dwelling-units.

The Federal Housing Administration (FHA), Freddie Mac, and Fannie Mae also provide loans to support ADUs. The links below include information on these finance programs, including relevant definitions and criteria.

FHA

The FHA recently expanded access to mortgage financing for homes that have or will include ADUs. Specifically, the updated loan policies allow for the inclusion of rental income from the ADU in the borrower’s qualifying income and would allow more borrowers to qualify for FHA financing for properties with ADUs. This includes the 203(k) Rehabilitation loan. Note that the 203(k) Rehabilitation loan may only be used to construct an attached ADU.

For more information on the updated policies, please reference the FHA Single Family Housing Policy Handbook at https://www.hud.gov/sites/dfiles/OCHCO/documents/40001-hsghupdate15-052024.pdf, or the 2023 Mortgagee Letter that includes specific ADU finance changes in the handbook https://www.hud.gov/sites/dfiles/OCHCO/documents/2023- 17hsgml.pdf. Interested parties should look to HUD’s website for any updates.

Freddie Mac

Freddie Mac now offers several options for adding an ADU to an existing home and financing a purchase with the intention to rent or build an ADU. This includes allowing rental income from ADUs to be included in qualified income for a loan.

For more information, please visit https://sf.freddiemac.com/docs/pdf/fact-sheet/adu-factsheet.pdf.

Fannie Mae Fannie Mae now offers financing options for adding an ADU to an existing property, building a home with an ADU using Construction-to-Permanent Financing, and buying a home with an existing ADU.

For more information, please visit https://singlefamily.fanniemae.com/originatingunderwriting/mortgage-products/accessory-dwelling-units.

There is no height limit contained in State ADU Law, but local agencies may impose height limits pursuant to Government Code section 66321, subdivision (b)(4). A local agency may impose a height limit by adopting a compliant ADU ordinance.

A local agency may not impose a height limit that is less than the following:

Detached ADUs

16 feet on a lot with a proposed or existing single-family or multifamily dwelling unit (Gov. Code, § 66321, subd. (b)(4)(A)).

18 feet on a lot with an existing or proposed single-family or multifamily dwelling, including an additional 2 feet to accommodate roof pitch that aligns with the primary dwelling, when the lot is a half-mile from a major transit stop or high-quality transit corridor (Gov. Code, § 66321, subd. (b)(4)(B)). Please see the ADU Glossary for definitions of these terms.

18 feet height on a lot with an existing or proposed multifamily, multistory dwelling (Gov. Code, § 66321, subd. (b)(4)(C)).

If a detached two-story ADU can be built according to the height allowances required under State ADU Law while remaining compliant with the building code, a local agency cannot deny an ADU application to create a two-story ADU, irrespective of the underlying zoning that might restrict a primary dwelling to one story. (Gov. Code, §§ 66321, subd. (b)(4)(D); 66314, subd. (d)(8).)

Attached ADUs

25 feet or the height limitation that applies to the primary dwelling in the local zoning ordinance, whichever is lower (Gov. Code, § 66321, subd. (b)(4)(D)).

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. Sections 714.3 and 4751 of the Civil Code nullify covenants, conditions, and restrictions (CC&Rs) that either effectively prohibit or unreasonably restrict the construction or use of an ADU or JADU on lots zoned to permit single-family residential uses. Such CC&Rs, including operating rules, are void and unenforceable. Applicants who encounter prohibitions of ADUs and JADUs within CC&Rs, whether implicit or explicit, are encouraged to reach out to their local agency

HOAs may impose some limited objective standards on an ADU or JADU, such as requiring, within reason, specific materials, architectural styles, or other design and aesthetic restrictions. However, these standards may not be more stringent than State ADU Law and thereby unreasonably increase the cost to construct or effectively prohibit or extinguish the ability to create or serve an ADU or JADU. (Civ. Code, § 714.3, subd. (b).)

Examples of effective prohibitions, unreasonable costs, and extinguishments of the ability to construct an ADU or JADU may include, but would not be limited to:

• Any delay in reviewing an ADU or JADU for compliance with reasonable restrictions beyond the timeframes required of local agencies (60 days) or that significantly delay the construction or use of an ADU or JADU.

• Requiring alteration to an ADU or JADU application that would cause the property owner to incur substantial costs or forgo the development.

• Imposing a condition that would necessitate re-applying or amending a building permit application that substantially complies with State ADU and JADU Laws.

• Mandating neighboring property owners’ approval or agreement for an ADU or JADU application or considering any disapproval or disagreement to the construction or use of an ADU or JADU by the neighbors as part of the local agency’s ministerial process to approve or deny the application.

• Restricting the placement or location of an ADU or JADU such that it would be rendered infeasible or unusable by the property owner.

• Requiring major structural elements or design changes beyond the requirements set forth in State ADU and JADU Law that would extinguish the ability to construct or use the ADU or JADU.

• Imposing restrictions that are not objective or not knowable or available to the property owners in advance of submitting the application.

• Levying excessive application fees, conditions, or other financial requirements that would cause the property owner to incur substantial costs or forgo the development, such as requiring owner-occupancy of an ADU or charging excessive maintenance fees that would be unreasonable considering the size of the ADU proportionally to the primary dwelling.

Property owners whose construction or use of an ADU or JADU is impeded by an HOA (or their representatives or agents) are encouraged to reach out to their local agency and to seek legal counsel.

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. Pursuant to Government Code sections 66330, and 65583.1, ADUs and JADUs may be utilized towards the RHNA and the Housing Element Annual Progress Report (APR) required by Government Code section 65400. To credit a unit toward the RHNA, HCD and the Department of Finance (DOF) utilize the U.S. Census definition of a housing unit. Generally, an ADU, and a JADU with shared sanitation facilities, and any other unit that meets the U.S. Census definition and is reported to DOF as part of the DOF annual City and County Housing Unit Change Survey can be credited toward the RHNA based on the appropriate income level. The housing element or APR must include a reasonable methodology to demonstrate the level of affordability. Local governments can track actual or anticipated affordability to assure ADUs and JADUs are counted towards the appropriate income category. For example, some local governments request and track information such as anticipated affordability as part of the building permit or other local applications.

For more information, please refer to the Housing Element Building Blocks or contact HousingElements@hcd.ca.gov.

To count ADUs towards the RHNA in the housing element, local agencies must generally use a three-part approach: (1) development trends, (2) anticipated affordability, and (3) resources and incentives. Development trends must consider ADUs permitted in the prior planning period and may also consider more recent trends. Anticipated affordability can use a variety of methods to estimate the affordability by income group. Common approaches include rent surveys of ADUs, using rent surveys and square footage assumptions and data available through the APR required by Government Code section 65400. Resources and incentives include policies and programs to encourage ADUs, such as prototype plans, fee waivers, expedited procedures, and affordability monitoring programs.

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).

A “junior accessory dwelling unit” or JADU is a unit that is no more than 500 square feet in size and contained entirely within a single-family residence. A JADU may include separate sanitation facilities or may share sanitation facilities with the existing structure. (Gov. Code, § 66333.)

No. Only one JADU may be created per lot zoned for single-family residences with an existing or proposed single-family residence (Gov. Code, § 66333, subd. (a)). The JADU may be created within the walls of the proposed or existing single-family residence, including attached 29 garages (Gov. Code, § 66333, subd. (d)). If there are multiple detached single-family residential units on one lot, there can only be one JADU.

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 66310, the California Legislature found and declared that, among other things, California is facing a severe housing crisis and ADUs are a valuable form of housing that meets the needs of family members, students, the elderly, inhome health care providers, people with disabilities, and others. Therefore, ADUs are an essential component of California’s housing supply.

Recent changes to State ADU Law intend to address barriers, streamline approval, and expand potential capacity for ADUs, recognizing their unique importance in addressing California’s housing needs. The preparation, adoption, amendment, and implementation of local ADU ordinances must be carried out consistently with Government Code section 66310 and must not unduly restrict the creation of ADUs. Local governments adopting ADU ordinances should carefully weigh the adoption of zoning, development standards, and other provisions for impacts on the development of ADUs.

State ADU Law provides the statutory minimum requirements for ADUs and JADUs. Local governments may elect to go beyond this statutory minimum to further the creation of ADUs. (Gov. Code, § 66325, subd. (b).) Many local governments have embraced the importance of ADUs as an important part of their overall housing policies and have pursued innovative strategies.

Yes. One common strategy used by local agencies to promote ADU development is to adopt ADU bonus programs. HCD supports this approach to go above and beyond State ADU Law’s requirements to address California’s ongoing housing crisis. A successful ADU bonus program should meet the following criteria:

1. The ADU bonus program is completely optional – There is no requirement, and no consequence for not taking part in a local bonus program.

2. The ADU bonus program only offers benefits in addition to the provisions of State ADU Law, not in lieu of them – All state-mandated requirements are granted unconditionally.

3. The ADU bonus program removes one or more physical constraints, such as a limitation on the number of allowable units on a lot, ADU size, height, setback requirements, or a waiver of design and development criteria.

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/

No. A lot, as defined in Health and Safety Code sections 18210 and 18862.23, allows for only one manufactured home, mobilehome, or recreational vehicle. Health and Safety Code section 18862.23 also allows one tent, camp car, camping cabin, or camping party on a lot within a special occupancy park.

For more information, please contact the Division of Codes and Standards at: NAOStaff@hcd.ca.gov for Northern CA or SAOStaff@hcd.ca.gov for Southern CA.

For the purposes of creating an ADU, a structure with two or more attached dwellings on a single lot is considered a multifamily dwelling structure. Multiple detached single-unit dwellings on the same lot are not considered multifamily dwellings for the purposes of State ADU Law.

Yes. A local agency must permit an attached, detached, or converted ADU on a lot that is zoned to allow single-family or multifamily residential use and includes an existing or proposed dwelling (Gov. Code, § 66314, subds. (d)(2), (d)(3)). An applicant may build a detached or a converted ADU on a site in a residential or mixed-use zone with a proposed or existing multifamily dwelling. (Gov. Code, § 66323, subds. (a)(3), (a)(4).) (See next question for more information.)

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).)

No. State ADU Law limits a local agency’s ability to deny a permit application due to the correction of existing, nonconforming zoning conditions. Nonconforming zoning conditions are physical improvements on a property that do not conform to current zoning standards.

For 66323 Units, a local agency cannot condition approval on the correction of nonconforming zoning conditions. For all other ADUs, a local agency may only deny a permit to create an ADU due to zoning non-conformance when the non-conformance creates a threat to public health and safety and is affected by the construction of the ADU.

No. A local agency cannot impose an owner-occupancy requirement on any ADU.

No. Parking requirements for ADUs shall not exceed one parking space per unit or bedroom, whichever is less. These spaces may be provided as tandem parking on a driveway.

Guest parking spaces shall not be required for ADUs under any circumstances. In addition, a local agency may not require off-street parking spaces to be replaced when a garage, carport, covered parking structure, or uncovered parking space is demolished in conjunction with the construction of an ADU or converted to an ADU.

Local agencies may choose to eliminate or reduce parking requirements for ADUs, such as requiring zero or a fraction of a parking space per each ADU (such as a ½ space per unit), to further reduce barriers to ADU construction and to facilitate more development of mixed-modal transportation such as walking and public transit.

Yes. A local agency shall not impose parking standards on any of the following ADUs, pursuant to Government Code section 66322, subdivision (a):

1) ADUs located within one-half mile walking distance of public transit.

2) ADUs located within an architecturally and historically significant historic district.

3) ADUs that are part of the proposed or existing primary residence or an accessory structure.

4) When on-street parking permits are required but not offered to the occupant of the ADU.

5) When there is a car share vehicle located within one block of the ADU.

6) When a permit application for an ADU is submitted with a permit application to create a new single-family dwelling or a new multifamily dwelling on the same lot, provided that the ADU or the parcel satisfies any other criteria listed in Government Code section 66322, subdivision (a)(1)-(5).

Parking requirements for ADUs may not exceed one parking space per ADU or per bedroom, whichever is less. ADUs which have no bedrooms because they are an “efficiency unit” or studio do not increase the bedroom count.

In addition, local agencies may not impose parking requirements on 66323 Units.

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.

A permitting agency is “any entity that is involved in the review of a permit for an accessory dwelling unit or JADU and for which there is no substitute, including, but not limited to, applicable planning departments, building departments, utilities, and special districts.”

Yes. ADUs subject to State ADU Law must be considered, approved or denied, and permitted ministerially, without discretionary review or a hearing. Development standards must be objective to allow for ministerial review. Objective standards require a uniform benchmark or reference that is knowable by both the permit applicant and the permitting agency prior to the submission of an application to create or serve an ADU.

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. Local agencies may require that ADUs be used for rentals of terms longer than 30 days. ADUs created pursuant to Government Code section 66323 must be rented for terms longer than 30 days.

A local agency may adopt a local ordinance to allow separate conveyance of the primary unit and the ADU as condominiums if the ordinance meets specific requirements laid out in Government Code section 66342. In addition, Government Code section 66341 creates a narrow exception to allow separate conveyance of an ADU to a qualified buyer if the property was built or developed by a qualified nonprofit corporation and meets other requirements specified in section 66341.

SB 9 and State ADU Law are complementary. Both laws can be implemented in ways that result in developments with both “SB 9 Units” and ADUs. However, in no case does SB 9 require a local agency to allow more than four units on a single lot, in any combination of primary units and ADUs or JADUs. For example, when a lot split has not occurred, the lot is eligible to receive a second primary unit on the lot under SB 9 and to receive up to two ADUs under State ADU Law.

When a lot split occurs under SB 9, each lot is eligible for up to two units, including, for example, a primary unit and an ADU or JADU. In the case that a lot owner both splits a lot and builds two primary units on each resulting lot under SB 9, State ADU Law is superseded (i.e., neither lot is entitled to an ADU or JADU); in all other cases, State ADU Law applies, up to SB 9’s four-unit cap.

Members of the public with SB 9 complaints are encouraged to share them to the Housing Accountability Unit Portal.

Yes. A local agency may impose objective development standards, such as setbacks, for the creation of ADUs. A setback of no more than four feet from the side and rear lot lines shall be required for an attached or detached ADU. Additional setback requirements may be required in the Coastal Zone if required by a local Coastal Program.

No setback shall be required for an ADU or JADU created within an existing living area or accessory structure or an ADU created in a new structure in the same location and to the same dimensions as an existing structure.

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.

The CBC provides the minimum standards to which all buildings in California must be built (California Building Code, Vol. 2, 1.1.3). The CBC also allows local agencies to adopt amendments, additions, or deletions to the provisions of the CBC which are reasonably necessary and are more restrictive than the CBC’s standards (California Building Code, Vol. 2, 1.1.8).

The CBC defines “Floor Area, Gross” as “[t]he floor area within the inside perimeter of the exterior walls of the building under consideration, exclusive of vent shafts and courts, without deduction for corridors, stairways, ramps, closets, the thickness of interior walls, columns or other features. The floor area of a building, or portion thereof, not provided with surrounding exterior walls shall be the usable area under the horizontal projection of the roof or floor above. The gross floor area shall not include shafts with no openings or interior courts.”

Government Code section 66314, subdivision (d)(8) states that a local ADU ordinance must require ADUs to comply with local building codes. Thus, when a local agency has not adopted specific changes to the CBC in its local building standards, then the CBC standards, and in this case the definition of floor area, shall apply. If the local agency has made specific amendments, additions, or deletions relating to the definition of “Floor Area” within its local building standards, then those altered definitions shall apply.

No. Local governments may not include minimum lot size requirements for ADUs.

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.

Yes, newly constructed ADUs are subject to the California Energy Code requirement (excluding manufactured homes) to provide solar systems if the unit(s) is a newly constructed, detached ADU (though some exceptions apply). Per the California Energy Commission (CEC), the solar systems can be installed on the ADU or on the primary dwelling unit. ADUs that are constructed within existing space, or as an addition to existing homes, including detached additions where an existing detached building is converted from non-residential to residential space, are not subject to the California Energy Code requirement to provide solar systems.

Please refer to the CEC on this matter. For more information, see the CEC’s website at www.energy.ca.gov. You may email your questions to title24@energy.ca.gov, or contact the Energy Standards Hotline at 800-772-3300. CEC memos can also be found on HCD’s website at https://www.hcd.ca.gov/policy-and-research/accessory-dwelling-units.

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Possibly. While State ADU Law does not specifically reference “tiny homes,” “tiny home” is an industry term that can mean different structures or vehicles. If the unit meets the definition of an ADU in Government Code section 66313, subdivision (a), it is subject to ADU Law.

For more information on “tiny homes,” see Information Bulletin 2016-01 at https://www.hcd.ca.gov/policy-research/docs/hcd-bulletin-tiny-home-ib-2016-01.pdf. ContactMH-FBH@hcd.ca.gov. You may also contact HCD’s Division of Codes and Standards at ContactMH-FBH@hcd.ca.gov.

An attached ADU is a newly created (constructed) dwelling structure that structurally abuts (and connects to) an existing or proposed primary dwelling or accessory structure. This can be constructed on top of or below the primary dwelling. The attached ADU extends beyond the building plane of the existing or proposed primary dwelling unit. An attached ADU shall not exceed 50 percent of the existing primary dwelling’s floor area size.

Examples of attached ADUs include, but are not limited to:

• An ADU addition to a duplex.

• An ADU built on top of an attached garage.

• An ADU built as a new second story of a single-family dwelling.

• An ADU built in a newly constructed basement.

Converted ADUs are dwelling units that are created from existing space within proposed or existing primary dwelling units or existing accessory structures. For single family residences, the converted ADU is created from the proposed or existing space of the single-family residence or the existing space of an accessory structure. For multifamily dwelling structures, the converted ADUs are created from portions of the multifamily dwelling structures that are not used as livable space (i.e., storage rooms, passageways, etc.).

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.

Local agencies may not deny a permit for an unpermitted ADU or JADU created prior to January 1, 2020. An inspector from the local agency may inspect the unit for compliance with health and safety standards and provide recommendations to comply with health and safety standards necessary to obtain a permit. If the inspector finds noncompliance with health and safety standards, the local agency shall not penalize an applicant for having the unpermitted ADU or JADU and shall approve necessary permits to correct noncompliance with health and safety standards. However, the local agency may deny a permit if it finds that the building is substandard. This does not preclude the local agency from pursuing enforcement action on these violations, and an applicant may be required to make alterations or repairs accordingly.

A local agency shall inform the public about the provisions of this section through public information resources, including permit checklists and the local agency’s internet website, which shall include both of the following: (1) a checklist of the conditions specified in Section 17920.3 of the Health and Safety Code that would deem a building substandard, and (2) information that, before applying for a permit, the homeowner may obtain a confidential third-party code inspection from a licensed contractor to determine the unit’s existing condition or potential scope of building improvements.

See the Department of Consumer Affairs’ Contractors State License Board’s contractor license check resource, available at https://www2.cslb.ca.gov/onlineservices/checklicenseII/checklicense.aspx.

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.

ADUs and JADUs created from the existing space of a primary dwelling or accessory structure pursuant to Government Code section 66323, subdivision (a)(1), cannot be required to install a new or separate connection unless the ADU is constructed concurrently with a new single-family dwelling. For all other ADUs not created pursuant to Government Code section 66323, subdivision (a)(1), a new or separate connection directly from the utility to the ADU may be required.

HCD does not have authority over issues related to gas and electrical services. If an applicant believes that a local utility provider is not complying with connection requirements, fee schedules, or other issues that impact the creation of or service of an ADU, the applicant can file a complaint with the appropriate agency.

For privately owned public utilities such as PG&E, contact the California Public Utilities Commission (CPUC) by using CPUC’s online complaint form, by calling 1-800-649-7570, or by sending a letter to:

California Public Utilities Commission

505 Van Ness Avenue

San Francisco, CA 94102–3298

For publicly owned utilities such as SMUD, the applicant will need to contact the utility directly and follow their complaint process.

No. Local agencies may, by ordinance, designate where ADUs are permitted within zones that allow residential use. However, any limits on where ADUs are allowed may only be based on the adequacy of water and sewer service and on the impacts on traffic flow and public safety.

Local governments may not preclude the creation of ADUs altogether, and any limitation should be accompanied by detailed findings of fact explaining why ADU limitations are required and consistent with these factors. If a lot with a residence has been rezoned to a use that does not allow for residential uses, that lot is no longer eligible for an ADU. Impacts on traffic flow should consider factors like lower car ownership rates for ADUs. Finally, local governments may develop alternative procedures, standards, or special conditions with mitigations for allowing ADUs in areas with potential health and safety concerns.

HCD understands that extreme weather conditions occur, and the threat of destructive wildfires cannot be ignored. Some agencies have used the High (HFHSZ) and Very High Fire Hazard Severity Zone (VHFHSZ) maps provided by CAL FIRE to mark areas where ADUs may be restricted or prohibited altogether. However, according to CAL FIRE, the HFHSZ and VHFHSZ maps are intended to govern building materials used in construction and defining zones of defensibility around structures. These are not intended to restrict housing development. The presence of a High Fire Hazard Severity Zone is not a conclusive rationale to warrant restricting ADUs. A restriction based on the threat to public safety should be supported with findings detailing the impact of ADUs on public safety.

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.

Detached ADUs are newly constructed dwelling units that are created on a lot with an existing or proposed single-family or multifamily dwelling structure but are detached from the primary dwelling.

Yes. Multifamily lots qualify for two detached, new construction ADUs on lots with a proposed multifamily dwelling, or up to eight detached ADUs on a lot with an existing multifamily dwelling, not to exceed the total number of existing units on the lot. These ADUs are detached from the primary multifamily structure but do not have to be detached from each other or other accessory structures on the lot.

An ADU is accessory to a primary residence and has complete independent living facilities for one or more persons. ADUs are either “detached from,” “attached to,” or located within the proposed or existing primary dwelling. This includes attached garages, storage areas or similar spaces, and accessory structures. The ADU can also be detached from the proposed or existing primary dwelling, including detached garages, provided it is located on the same lot. (Gov. Code. §§ 66313, subd. (a); 66314, subd. (d)(3).)

Note that certain federal financing programs mentioned in the section on “Funding,” below, may have different definitions of an ADU.