A. 
Purpose. The purpose of this section is to allow, encourage, and regulate the development of accessory dwelling units (ADUs) and junior accessory dwelling units (JADUs) in compliance with California Government Code Sections 66310 et seq.; to increase the opportunities to provide affordable housing meeting the city's very low, low, and moderate income housing objectives; and to protect property values and the integrity of neighborhoods by adopting design and development standards for units to ensure that they are compatible.
B. 
ADUs that satisfy the requirements of this Chapter 17.715 are allowed on a legal lot that is zoned RE, R-1-E, R-1, R-2. R-3, COR, CR, PEC, or a PD zone that allows single-family or multifamily dwelling residential use.
C. 
One JADU that satisfies the requirements of this Chapter 17.715 is allowed on a legal lot that is zoned RE, R-1-E, R-1, or a PD zone that is a single-family residential zone.
(Ord. 1083, 2/25/2025)
An ADU or JADU that conforms to the standards in this chapter will not be:
A. 
Deemed to be inconsistent with the city's general plan and zoning designation for the lot on which the ADU or JADU is located;
B. 
Deemed to exceed the allowable density for the lot on which the ADU or JADU is located;
C. 
Considered in the application of any local ordinance, policy, or program to limit residential growth;
D. 
Required to correct a nonconforming zoning condition, as defined in Section 17.715.030 below.
(Ord. 1083, 2/25/2025)
As used in this section, terms are defined as follows:
"Accessory dwelling unit" or "ADU"
means an attached residential dwelling unit, a detached residential dwelling unit, or a conversion of space to a residential dwelling unit that provides complete independent living facilities for one or more persons and is located on a parcel with a proposed or existing primary dwelling. It shall include permanent provisions for living, sleeping, eating, cooking, and sanitation on the same parcel as the single-family or multifamily dwelling is or will be situated. An accessory dwelling unit also includes the following:
1. 
An efficiency unit, as defined by Section 17958.1 of the California Health and Safety Code; and
2. 
A manufactured home, as defined by Section 18007 of the California Health and Safety Code.
"Attached"
means a building shares a common wall, in whole or in part, with a single-family dwelling or multifamily dwelling.
"Complete independent living facilities"
means permanent provisions for living, sleeping, eating, cooking, and sanitation on the same parcel as the single-family or multifamily dwelling is or will be situated.
"Conversion"
means converting space within a proposed or existing single-family dwelling, an existing multifamily dwelling, an existing accessory building that was legally constructed, or in the same location and to the same dimensions as an existing accessory building that was legally constructed in accordance with any applicable building permits for use as an accessory dwelling unit. Where an accessory building is converted to an accessory dwelling unit on a parcel containing a single-family dwelling, conversion includes an increase of up to an additional one hundred fifty square feet to accommodate ingress and egress.
"Detached"
means a building not structurally part of and not sharing a common wall or any other attachment other than utilities with a single-family dwelling or multifamily dwelling.
"Efficiency kitchen"
means a kitchen that includes all of the following:
1. 
A cooking facility with appliances.
2. 
A food preparation counter and storage cabinets that are of a reasonable size in relation to the size of the JADU.
"Efficiency unit"
has the same meaning as defined in Section 17958.1 of the California Health and Safety Code.
"Junior accessory dwelling unit" or "JADU"
means a residential unit that satisfies all of the following:
1. 
It is no more than five hundred square feet in size.
2. 
It is contained entirely within an existing or proposed single-family dwelling. An enclosed use within the residence, such as an attached garage, is considered to be a part of and contained within the single-family dwelling.
3. 
It includes an exterior entrance separate from the exterior entrance for the single-family dwelling.
4. 
It includes its own separate sanitation facilities or shares sanitation facilities with the existing or proposed single-family dwelling.
5. 
If the unit does not include its own separate bathroom, then it contains an interior entrance to the main living area of the existing or proposed single-family dwelling in addition to an exterior entrance that is separate from the main entrance to the single-family dwelling.
6. 
It includes an efficiency kitchen, as defined above.
"Livable space"
means a space in a dwelling intended for human habitation, including living, sleeping, eating, cooking, or sanitation.
"Living area"
means the interior habitable area of a dwelling unit, including basements and attics, but does not include a garage or any accessory building.
"Nonconforming zoning condition"
means a "nonconforming facility" as defined in Section 17.610.003 and refers to a physical improvement on a property that conformed with zoning when constructed but does not conform with current zoning standards.
"Primary dwelling"
means the proposed or existing single-family dwelling or multifamily dwelling on the lot.
"Proposed dwelling"
means a dwelling that is the subject of a building permit application and that meets the requirements for permitting.
"Public transit"
means a location, including, but not limited to, a bus stop or train station, where the public may access buses, trains, subways, and other forms of transportation that charge set fares, run on fixed routes, and are available to the public.
"Setback"
as used in this section means the distance between the exterior wall of the ADU, which includes any and all appurtenant features, to the property line.
"State exempt ADU"
means an ADU that meets the requirements provided in Section 17.715.050(B) below.
"Tandem parking"
means that two or more automobiles are parked on a driveway or in any other location on a lot, lined up behind one another.
(Ord. 1083, 2/25/2025)
An ADU or JADU application must be considered ministerially, without discretionary review or a hearing. The following approvals apply to ADUs and JADUs under this section:
A. 
Ministerial Approval. An ADU or JADU application must be considered through the building permit process without discretionary review or a hearing.
B. 
Process and timing.
1. 
The city must approve or deny an ADU application using preapproved ADU plans consistent with Government Code Section 65852.27(b) within thirty days from the date that the city receives the completed application.
2. 
The city must approve or deny an application to create an ADU or JADU within sixty days from the date that the city receives a completed application. If the city has not approved or denied the completed application within sixty days, the application is deemed approved unless either:
a. 
The applicant requests a delay, in which case the sixty-day time period is tolled for the period of the requested delay; or
b. 
The application to create an ADU or JADU is submitted with a permit application to create a new single-family or multifamily dwelling on the lot. The city may delay acting on the permit application for the ADU or JADU until the city acts on the permit application to create the new single-family or multifamily dwelling, but the application to create the ADU or JADU will still be considered ministerially without discretionary review or a hearing.
3. 
If the city denies an application to create an ADU or JADU, the city must provide the applicant with comments that include, among other things, a list of all the defective or deficient items and a description of how the application may be remedied by the applicant. Notice of the denial and corresponding comments must be provided to the applicant within the sixty-day time period.
(Ord. 1083, 2/25/2025)
A. 
Number of ADUs and JADUs Per Lot.
1. 
Only one ADU shall be permitted on a lot with proposed or existing single-family or multifamily dwellings unless all existing and proposed ADUs on the lot are state exempt ADUs. The maximum number of state exempt ADUs permitted on a lot is as set forth in subsection B below.
2. 
Only one JADU may be permitted on a lot and shall only be permitted on a lot with no more than one existing or proposed single-family dwelling.
B. 
Any ADU that meets satisfies the requirements of one of the following subsections (B)(1) through (4) is a "state exempt ADU." State exempt ADUs shall be ministerially permitted on a lot and are not required to meet the additional development and design standards in the underlying zoning district or in subsection (C), (F), or (M) below, unless otherwise specified:
1. 
One conversion ADU that:
a. 
Is either within the space of a proposed single-family dwelling, within the existing space of an existing single-family dwelling, or within the existing space of an accessory structure, plus up to one hundred fifty additional square feet of the accessory structure if the expansion is limited to accommodating ingress and egress;
b. 
Has exterior access that is independent of that for the single-family dwelling; and
c. 
Has side and rear setbacks sufficient for fire and safety, as dictated by applicable building and fire codes.
2. 
One detached, new-construction ADU on a lot with a proposed or existing single-family dwelling if the detached ADU satisfies each of the following limitations:
a. 
The side- and rear-yard setbacks are at least four feet, and the ADU is set back from the primary dwelling at least four feet.
b. 
Maximum size: The total floor area is eight hundred square feet or smaller.
c. 
Maximum height: The peak height above grade does not exceed the applicable height limit in subsection E, below.
3. 
One or more ADUs within portions of existing multifamily dwellings that are not used as livable space, including, but not limited to, storage rooms, boiler rooms, passageways, attics, basements, or garages, if each converted ADU complies with state building standards for dwellings. At least one converted ADU is allowed within an existing multifamily dwelling, up to a quantity equal to twenty-five percent of the existing multifamily dwelling units.
4. 
Detached ADUs up to the number in subsection (B)(4)(a) or (B)(4)(b) below if the peak height of each ADU above grade does not exceed the applicable height limit in subsection E and the side- and rear-yard setbacks are each at least four feet. If the existing multifamily dwelling has a rear or side yard setback of less than four feet, the city will not require any modification to the multifamily dwelling as a condition of approving the ADU.
a. 
On a lot that has a proposed multifamily dwelling, two detached ADUs.
b. 
On a lot that has an existing multifamily dwelling, the lesser of eight ADUs or the number of existing units in the multifamily dwelling.
C. 
Development Standards. An ADU shall comply with the requirements of this section, the underlying zoning district, and other provisions of the Brentwood Municipal Code except:
1. 
If the requirements of the underlying zoning district or other provisions of the Brentwood Municipal Code are inconsistent with the provisions of this Chapter 17.715, the standards of this chapter shall apply.
2. 
If limits on lot coverage, front yard setback, floor area ratio, open space, and size preclude the development of an eight hundred square foot detached or attached accessory dwelling unit with four-foot side and rear yard setbacks, and if the proposed accessory dwelling unit complies with all other applicable development standards, the applicable standard must be waived by the city.
3. 
If the ADU or JADU is existing, constructed without permits, and is seeking a permit pursuant to subsection (G)(2) below.
4. 
The city may not require as a condition of approval the correction of nonconforming zoning conditions.
D. 
Access. An ADU shall have a separate exterior entrance and exit from the primary dwelling unit.
E. 
Height.
1. 
Except as otherwise provided by subsections (E)(2) and (E)(3) below, a detached ADU created on a lot with an existing or proposed single-family or multifamily dwelling unit may not exceed sixteen feet in height.
2. 
A detached ADU may be up to eighteen feet in height if it is created on a lot with an existing or proposed single-family or multifamily dwelling unit that is located within one-half mile walking distance of a major transit stop or a high quality transit corridor, as those terms are defined in Section 21155 of the Public Resources Code, and in such locations, the ADU may be up to two additional feet in height (for a maximum of twenty feet) if necessary to accommodate a roof pitch on the ADU that is aligned with the roof pitch of the primary dwelling unit.
3. 
A detached ADU created on a lot with an existing or proposed multifamily dwelling that has more than one story above grade may not exceed eighteen feet in height.
4. 
An ADU that is attached to the primary dwelling may not exceed twenty-five feet in height or the height limitation imposed by the underlying zone that applies to the primary dwelling, whichever is lower. Notwithstanding the foregoing, ADUs subject to this subsection may not exceed two stories.
5. 
For purposes of this subsection E, height is measured above existing legal grade to the peak of the structure.
F. 
Design and Size.
1. 
Except for state exempt ADUs, the exterior of the ADU shall be designed so that its roof slope, siding materials, and colors are the same as the primary dwelling. Outdoor lights shall be shielded and directed downward.
2. 
For detached or attached ADUs, maximum square footage is eight hundred fifty square feet for a studio/one bedroom unit and one thousand square feet for an ADU with two or more bedrooms. The detached or attached ADU must have a minimum of four foot side and rear setbacks. Notwithstanding the foregoing, an attached ADU that is created on a lot with an existing primary dwelling is further limited to fifty percent of the floor area of the existing primary dwelling.
G. 
Building and Fire Code.
1. 
The ADU and JADU must comply with all applicable building and fire code requirements (BMC Title 15).
2. 
An existing ADU or JADU, constructed without permits prior to January 1, 2020, may be legalized unless the Chief Building Official or designee makes findings that correcting a building standard violation is necessary to comply with the standards provided in Health and Safety Code Section 17920.3.
3. 
No Change of Occupancy. Construction of an ADU does not constitute a Group R occupancy change under the local building code, as described in Section 310 of the California Building Code, unless the building official or a city code enforcement officer makes a written finding based on substantial evidence in the record that the construction of the ADU could have a specific, adverse impact on public health and safety. Nothing in this subsection prevents the city from changing the occupancy code of a space that was uninhabitable space or that was only permitted for nonresidential use and was subsequently converted for residential use in accordance with this section.
4. 
Prior to January 1, 2030, when the chief building official provides a notice to correct a violation of any building standard, the chief building official shall include in that notice a statement that the owner of the ADU has a right to request a delay must provide a notice if the ADU that was built prior to January 1, 2020, or built when the city had a noncompliant ADU ordinance. If the ADU was built when the city had a noncompliant ADU ordinance, this chapter must be compliant with state law at the time the request for delay in enforcement is made.
a. 
The owner of the ADU may submit a written request to the chief building official requesting that correction of any violation of building standards be delayed for five years.
b. 
The chief building official will grant the application if the chief building official determines that enforcement of the building standard is not necessary to protect health and safety.
c. 
For purposes of this subsection (G)(4), "building standards" refers to those standards enforced by local agencies under the authority of Section 17960 of the California Health and Safety Code.
H. 
Building Separation. Except for state exempt ADUs, a new detached ADU shall be no closer than four feet from any other building on the lot.
I. 
Deed Restriction.
1. 
Prior to issuance of a building permit for a JADU, the property owner shall record with the county recorder a deed restriction setting forth the following:
a. 
The single-family and the accompanying ADU(s) or JADU(s) are on a single parcel, and the units cannot be sold separately except as provided in Government Code Section 66340 et seq.
b. 
The JADU is restricted to the approved size and other attributes allowed by this chapter.
2. 
For JADUs only, prior to issuance of a building permit, the deed restriction shall require that either the single-family dwelling or the JADU is the bona fide principal dwelling of the legal owner or owners of the parcel, unless the owner is a governmental agency, land trust, or housing organization.
J. 
Fees.
1. 
Impact Fees. Development impact fees for an ADU are as outlined in the city's adopted development fee program, as amended from time to time by city council resolution. Impact fees do not include any connection fee or capacity fee charge for water or sewer service.
a. 
Impact fees are not required for an ADU that is less than seven hundred fifty square feet in total area or a JADU.
b. 
Impact fees required for ADUs seven hundred fifty square feet and greater shall be charged proportionately in relation to the square footage of the primary dwelling unit.
2. 
Utility Fees.
a. 
Conversion ADUs on parcels zoned for single-family use are not required to have a new or separate utility connection directly between the ADU and the utility. ADUs are not considered new residential uses for the purposes of calculating any connection fees or capacity charges for utilities, including water and sewer service, unless the accessory dwelling unit is constructed with a new single-family dwelling.
b. 
Other ADUs may not have water and wastewater utility connections as an extension from the primary dwelling unit, except for: (a) ADUs existing water and wastewater connections; and (b) Contra Costa Health Services approved septic systems. Utility services may be extended from the private utility lateral, between the public utility main and the primary dwelling unit or may be a separate connection to the public utility main. Applicants must follow the application procedures and pay all applicable charges, including any applicable security deposit, application fee, service connection charge, meter charge, service line charge, existing facilities charge, and any other charges as set forth in the city's cost allocation plan, except that any connection fee and capacity charge must be proportional to the size in square feet of the accessory dwelling unit or its drainage fixture unit (DFU) value.
c. 
A JADU is not considered a separate or new dwelling unit for the purposes of providing service for water or sewer. No water or sewer requirements may be applied to single-family dwellings containing a JADU unless they apply uniformly to all single-family dwellings in the zone regardless of whether or not they contain a junior accessory dwelling unit.
K. 
Fire Sprinklers.
1. 
Fire sprinklers shall be required in ADUs only where they are also required for the primary dwelling unit.
2. 
The construction of an ADU does not trigger a requirement for fire sprinklers to be installed in the existing primary dwelling.
L. 
Owner Occupancy. JADUs are subject to an owner occupancy requirement. The legal owner or owners shall reside in either the remaining portion of the single-family dwelling or the JADU. The owner occupancy restriction shall not be required if the owner is another governmental agency, land trust, or housing organization.
M. 
Parking.
1. 
ADUs. Required parking shall not exceed one parking space per ADU. The parking space may be covered, uncovered, off-site, or as tandem parking on a driveway. The parking space must be in compliance with the city's parking ordinance (Section 17.620.007(A)). The parking space is in addition to the parking requirements for the single-family or multifamily dwelling unit, except as provided in subsection (M)(2)(b) below.
2. 
Exceptions. Parking standards shall not be imposed for an ADU that meets one or more of the following criteria:
a. 
The ADU is located within one-half mile walking distance of public transit.
b. 
The ADU is located within an architecturally and historically significant historic district.
c. 
The ADU is part of the proposed or existing primary dwelling, or an existing accessory building conversion.
d. 
When on-street parking permits are required but not offered to the occupant of the ADU.
e. 
When there is an established car share vehicle located within one block of the ADU.
f. 
When the permit application to create an ADU is submitted with an application to create a new single-family or new multifamily dwelling on the same lot, provided that the ADU or the lot satisfies any other criteria listed in subsections (M)(2)(a) through (e) above.
3. 
JADUs. Parking shall not be required for a JADU.
4. 
Converted or Destroyed Parking Structure.
a. 
When a parking structure, uncovered parking, or covered parking is converted or destroyed in the construction of an ADU, the lost parking is not required to be replaced. However, replacement parking is required if parking in an attached garage is converted into a JADU.
b. 
If the applicant applies for a demolition permit to demolish a detached garage and a building permit to construct a detached ADU, the demolition permit and building permit for the ADU shall be issued at the same time.
N. 
Rental Term. No ADU or JADU may be rented for a term of less than thirty days. This prohibition applies regardless of when the ADU or JADU was created.
O. 
No Separate Conveyance. An ADU or JADU may be rented in accordance with subsection N above, but except as otherwise provided in Government Code Sections 66340 through 66341, no ADU or JADU may be sold or otherwise conveyed separately from the lot and the primary dwelling (in the case of a single-family lot) or from the lot and all of the dwellings (in the case of a multifamily lot).
P. 
Utilities. All new utilities for detached ADUs shall be installed underground.
Q. 
Solar Panels. Solar panels are required when mandated under the California Energy Code.
(Ord. 1083, 2/25/2025)