What are the Statewide ADU Regulations in California?

Understanding SB 13 and AB 68, California's landmark housing legislation to support housing development statewide through Accessory Dwelling Units. Go to your city page and check your property to learn more about what you kind of ADU could work best for you.



CA State ADU Codes Summary (Updated for 2020 Laws: SB 13 and AB 68)

These are the default minimum set of standards required by The State of California for all cities in the state. Search for your city to find your local municipality has adopted a local set of zoning standards for ADUs.


Statewide ADU Standards
Single-Family Properties
ADU Category
Detached ADUs
Attached ADUs
Conversion ADUs
Junior ADUs
Adu Qty
One unit per property.
One unit per property.
One unit per property.
One unit per property.
Adu Size
Limited to 850 sq. ft. for studio and one bedroom units, and 1,000 sq. ft. for two bedroom units.
Up to 800 sq. ft. or 50 percent of the floor area primary home, whichever is greater.
Up to 800 sq. ft. or 50 percent of the floor area primary home, whichever is greater. (Must be existing legal space.)
Limited to 500 sq. ft.
Lot Size
No minimum size requirement.
No minimum size requirement.
No minimum size requirement.
No minimum size requirement.
Setbacks
Sides and rear setbacks are 4 feet, front setbacks apply.
Sides and rear setbacks are 4 feet, front setbacks apply.
Not applicable.
Not applicable.
Max Height
One story, 16 feet maximum.
One story, 16 feet maximum.
Not applicable.
Not applicable.
Limit Rooms
Two bedrooms and one bathroom per unit.
Two bedrooms and one bathroom per unit.
Two bedrooms and one bathroom per unit.
One bedroom and one bathroom per unit.
Owner Occupancy
Not required.
Not required.
Not required.
May be required.
Fire Safety
Only required when required in the existing primary unit.
Only required when required in the existing primary unit.
Only required when required in the existing primary unit.
Only required when required in the existing primary unit.
Existing Structures
Not applicable.
Not applicable.
Must be created from existing legal space.
Must be created from existing legal space that is connected to the primary home.
Permit Fees
No impact fees for units under 750 sq ft.
No impact fees for units under 750 sq ft.
No impact fees for units under 750 sq ft.
Not applicable.

Statewide ADU Standards
Multi-Family Properties
ADU Category
New Construction ADUs
Conversion ADUs
Adu Qty
At least one and up to two if eight or more units existing legally on the property.
At least one and up to 25 percent of the units existing legally on the property.
Adu Size
Limited to 850 sq. ft. for studio and one bedroom units, and 1,000 sq. ft. for two bedroom units.
Up to 800 sq. ft. or 50 percent of the floor area primary home, whichever is greater. (Must be existing legal space.)
Lot Size
No minimum size requirement.
No minimum size requirement.
Setbacks
Not applicable.
Not applicable.
Max Height
Not applicable.
Not applicable.
Limit Rooms
Two bedrooms and one bathroom per unit.
Two bedrooms and one bathroom per unit.
Owner Occupancy
Not required.
Not required.
Fire Safety
Only required when required in the existing units.
Only required when required in the existing units.
Existing Structures
Not applicable.
Must be created from existing legal space.
Permit Fees
No impact fees for units under 750 sq ft.
No impact fees for units under 750 sq ft.

Conversion of exisitng legal structures or existing units into an ADU is not subject to size limits.

The unit is exempt from parking requirements if any of the following are true:

1.) The property is located within 1/2 mile from a public transit station.

2.) The property is located with a historically designated area.

3.) The unit is an existing structure or part of an existing structure.

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

5.) When there is a car-share drop off point located within one block of the unit.

Units above 500 sq ft may be subject to school permit fees. Units above 750 sq ft may be subject to impact fees.


Check your local ADU requirements




Frequently Asked Questions About the Statewide ADU Requirements

Please feel free to email us questions that are not answered on this page to feedback@housable.com and we'd be happy to add them to this page. All FAQ was sourced from the offical ADU memorandum issued by The State of California, which can be found at the link below.


Can a Local Government Preclude ADUs?

No local government cannot preclude ADUs.


Can a local government adopt less restrictive requirements?

Yes, ADU law is a minimum requirement and its purpose is to encourage the development of ADUs. Local governments can take a variety of actions beyond the statute that promote ADUs such as reductions in fees, less restrictive parking or unit sizes or amending general plan policies.


Are existing ordinances null and void?

Yes, any local ordinance adopted prior to January 1, 2017 that is not in compliance with the changes to ADU law will be null and void. Until an ordinance is adopted, local governments must apply “state standards” (See Attachment 4 for State Standards checklist). In the absence of a local ordinance complying with ADU law, local review must be limited to “state standards” and cannot include additional requirements such as those in an existing ordinance.


Are local governments required to adopt an ordinance?

No, a local government is not required to adopt an ordinance. ADUs built within a jurisdiction that lacks a local ordinance must comply with state standards (See Attachment 4). Adopting an ordinance can occur through different forms such as a new ordinance, amendment to an existing ordinance, separate section or special regulations within the zoning code or integrated into the zoning code by district. However, the ordinance should be established legislatively through a public process and meeting and not through internal administrative actions such as memos or zoning interpretations.


Can a local government apply development standards and designate areas?

Yes, local governments may apply development standards and may designate where ADUs are permitted (GC Sections 65852.2(a)(1)(A) and (B)). However, ADUs within existing structures must be allowed in all single family residential zones. For ADUs that require an addition or a new accessory structure, development standards such as parking, height, lot coverage, lot size and maximum unit size can be established with certain limitations. ADUs can be avoided or allowed through an ancillary and separate discretionary process in areas with health and safety risks such as high fire hazard areas. However, standards and allowable areas must not be designed or applied in a manner that burdens the development of ADUs and should maximize the potential for ADU development. Designating areas where ADUs are allowed should be approached primarily on health and safety issues including water, sewer, traffic flow and public safety. Utilizing approaches such as restrictive overlays, limiting ADUs to larger lot sizes, burdensome lot coverage and setbacks and particularly concentration or distance requirements (e.g., no less than 500 feet between ADUs) may unreasonably restrict the ability of the homeowners to create ADUs, contrary to the intent of the Legislature.


Can local governments establish minimum and maximum unit sizes?

Yes, a local government may establish minimum and maximum unit sizes (GC Section 65852.2(c). However, like all development standards (e.g., height, lot coverage, lot size), unit sizes should not burden the development of ADUs. For example, setting a minimum unit size that substantially increases costs or a maximum unit size that unreasonably restricts opportunities would be inconsistent with the intent of the statute. Typical maximum unit sizes range from 800 square feet to 1,200 square feet. Minimum unit size must at least allow for an efficiency unit as defined in Health and Safety Code Section 17958.1.


Can ADUs exceed general plan and zoning densities?

An ADU is an accessory use for the purposes of calculating allowable density under the general plan and zoning. For example, if a zoning district allows one unit per 7,500 square feet, then an ADU would not be counted as an additional unit. Minimum lot sizes must not be doubled (e.g., 15,000 square feet) to account for an ADU. Further, local governments could elect to allow more than one ADU on a lot.


How are fees charged to ADUs?

All impact fees, including water, sewer, park and traffic fees must be charged in accordance with the Fee Mitigation Act, which requires fees to be proportional to the actual impact (e.g., significantly less than a single family home). Fees on ADUs, must proportionately account for impact on services based on the size of the ADU or number of plumbing fixtures. For example, a 700 square foot new ADU with one bathroom that results in less landscaping should be charged much less than a 2,000 square foot home with three bathrooms and an entirely new landscaped parcel which must be irrigated. Fees for ADUs should be significantly less and should account for a lesser impact such as lower sewer or traffic impacts.


What utility fee requirements apply to ADUs?

Cities and counties cannot consider ADUs as new residential uses when calculating connection fees and capacity charges. Where ADUs are being created within an existing structure (primary or accessory), the city or county cannot require a new or separate utility connections for the ADU and cannot charge any connection fee or capacity charge. For other ADUs, a local agency may require separate utility connections between the primary dwelling and the ADU, but any connection fee or capacity charge must be proportionate to the impact of the ADU based on either its size or the number of plumbing fixtures.


What utility fee requirements apply to non-city and county service districts?

All local agencies must charge impact fees in accordance with the Mitigation Fee Act (commencing with Government Code Section 66000), including in particular Section 66013, which requires the connection fees and capacity charges to be proportionate to the burden posed by the ADU. Special districts and non-city and county service districts must account for the lesser impact related to an ADU and should base fees on unit size or number of plumbing fixtures. Providers should consider a proportionate or sliding scale fee structures that address the smaller size and lesser impact of ADUs (e.g., fees per square foot or fees per fixture). Fee waivers or deferrals could be considered to better promote the development of ADUs.


Do utility fee requirements apply to ADUs within existing space?

No, where ADUs are being created within an existing structure (primary or accessory), new or separate utility connections and fees (connection and capacity) must not be required.


Does “public transit” include within one-half mile of a bus stop and train station?

Yes, “public transit” may include a bus stop, train station and paratransit if appropriate for the applicant. “Public transit” includes areas where transit is available and can be considered regardless of tighter headways (e.g., 15 minute intervals). Local governments could consider a broader definition of “public transit” such as distance to a bus route.


Can parking be required where a car share is available?

No, ADU law does not allow parking to be required when there is a car share located within a block of the ADU. A car share location includes a designated pick up and drop off location. Local governments can measure a block from a pick up and drop off location and can decide to adopt broader distance requirements such as two to three blocks.


Is off street parking permitted in setback areas or through tandem parking?

Yes, ADU law deliberately reduces parking requirements. Local governments may make specific findings that tandem parking and parking in setbacks are infeasible based on specific site, regional topographical or fire and life safety conditions or that tandem parking or parking in setbacks is not permitted anywhere else in the jurisdiction. However, these determinations should be applied in a manner that does not unnecessarily restrict the creation of ADUs.


Is covered parking required?

No, off street parking must be permitted through tandem parking on an existing driveway, unless specific findings are made.


Is replacement parking required when the parking area for the primary structure is used for an ADU?

Yes, but only if the local government requires off-street parking to be replaced in which case flexible arrangements such as tandem, including existing driveways and uncovered parking are allowed. Local governments have an opportunity to be flexible and promote ADUs that are being created on existing parking space and can consider not requiring replacement parking.


Are setbacks required when an existing garage is converted to an ADU?

No, setbacks must not be required when a garage is converted or when existing space (e.g., game room or office) above a garage is converted. Rear and side yard setbacks of no more than five feet are required when new spaceis added above a garage for an ADU. In this case, the setbacks only apply to the added space above the garage, not the existing garage and the ADU can be constructed wholly or partly above the garage, including extending beyond the garage walls. Also, when a garage, carport or covered parking structure is demolished or where the parking area ceases to exist so an ADU can be created, the replacement parking must be allowed in any “configuration” on the lot, “…including, local governments must provide reasonable accommodation to persons with disabilities to promote equal access housing and comply with fair housing laws and housing element law. The reasonable accommodation procedure must provide exception to zoning and land use regulations which includes an ADU ordinance. Potential exceptions are not limited and may include development standards such as setbacks and parking requirements and permitted uses that further the housing opportunities of individuals with disabilities, but not limited to, covered spaces, uncovered spaces, or tandem spaces, or….” Configuration can be applied in a flexible manner to not burden the creation of ADUs. For example, spatial configurations like tandem on existing driveways in setback areas or not requiring excessive distances from the street would be appropriate.


Are ADUs Permitted in Existing Residence or Accessory Space?

Yes, ADUs located in single family residential zones and existing space of a single family residence or accessory structure must be approved regardless of zoning standards (Section 65852.2(a)(1)(B)) for ADUs, including locational requirements (Section 65852.2(a)(1)(A)), subject to usual non-appealable ministerial building permit requirements. For example, ADUs in existing space does not necessitate a zoning clearance and must not be limited to certain zones or areas or subject to height, lot size, lot coverage, unit size, architectural review, landscape or parking requirements. Simply, where a single family residence or accessory structure exists in any single family residential zone, so can an ADU. The purpose is to streamline and expand potential for ADUs where impact is minimal and the existing footprint is not being increased. Zoning requirements are not a basis for denying a ministerial building permit for an ADU, including non-conforming lots or structures. The phrase, “..within the existing space” includes areas within a primary home or within an attached or detached accessory structure such as a garage, a carriage house, a pool house, a rear yard studio and similar enclosed structures.


Are owner occupants required?

No, however, a local government can require an applicant to be an owner occupant. The owner may reside in the primary or accessory structure. Local governments can also require the ADU to not be used for short term rentals (terms lesser than 30 days). Both owner occupant use and prohibition on short term rentals can be required on the same property. Local agencies which impose this requirement should require recordation of a deed restriction regarding owner occupancy to comply with GC Section 27281.5


Are fire sprinklers required for ADUs?

Yes. ADU law explicitly applies to “local agencies” which are defined as a city, county, or city and county whether general law or chartered (Section 65852.2(i)(2)).


Do ADUs count toward the regional housing need allocation?

Yes, local governments may report ADUs as progress toward Regional Housing Need Allocation pursuant to Government Code Section 65400 based on the actual or anticipated affordability. See below frequently asked questions for JADUs for additional discussion.


Must ADU ordinances be submitted to The Department of Housing & Community Development?

Yes, ADU ordinances must be submitted to the State Department of Housing and Community Development within 60 days after adoption, including amendments to existing ordinances. However, upon submittal, the ordinance is not subject to a Department review and findings process similar to housing element law (GC Section 65585)


View & Download the Full Statewide Memorandum here:

http://www.hcd.ca.gov/policy-research/docs/2016-12-12-ADU-TA-Memo.docx.pdf


Questions about getting started? Schedule a free ADU consultation today. (415) 300-2387


Questions about getting started? Schedule a free ADU consultation today. (415) 300-2387

Check your local ADU requirements




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Housable is providing information about specific properties that is furnished to users as a good-faith estimate of the development potential of a property. You should not in any way base your development, investments, or other financial decisions on this information. We strongly advise you to consult with an industry professional, such as a lender, realtor, contractor, or architect, who is sufficiently licensed and insured in their field, and who can work with you individually to confirm all requirements before moving forward with any real estate development or investment.