Thousand Oaks Municipal Code Art. 45 Accessory Dwelling Units

The intent and purpose of this article is to expand opportunities in the City to create additional housing, allow more efficient use of existing housing stock, and provide a range of housing opportunities through the creation of new accessory dwelling units (ADUs) and junior accessory dwelling units (JADUs) on lots in designated zones that already contain one (1) established unit, or in conjunction with the construction of a new residential unit. It is the intent of this article to permit ADUs and JADUs, in conformance with state law, in designated zones in a manner consistent with the City’s General Plan.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) California Government Code Sections 66310-66342 allow local agencies to provide for the creation of ADUs and JADUs in areas zoned for single-family and multifamily residential use.

(b) If a conflict is found between this article and California Government Code Sections 66310-66342, California Government Code Sections 66310-66342, as it may be amended, shall prevail.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) No ADU or JADU may be created without a building permit. Whenever an ADU or JADU is proposed as a project, an application shall be submitted to the Community Development Department on a form provided by said department along with any necessary supporting information. An application for development of an ADU or JADU created pursuant to this article will be reviewed ministerially, without discretionary review or a hearing, and approved if it meets all applicable requirements.

(b) Within fifteen (15) business days of receipt of an ADU or JADU application, the Community Development Department shall determine whether the application is complete and provide written notice to the applicant of that determination. If incomplete, the notice shall include a list of incomplete items and a description of how the application may be made complete. Upon resubmittal of materials to address an incomplete application, the City shall determine completeness within fifteen (15) business days.

(c) ADU and/or JADU applications shall be ministerially approved or denied within sixty (60) days from the date a complete application is submitted if there is an existing single- or multifamily dwelling on the lot, unless the applicant requests a delay, in which case the sixty (60)-day time period is tolled for the period of the delay. A denied application for an ADU and/or JADU shall include a full set of comments to the applicant with a list of items that are defective or deficient, and a description of how the application can be remedied.

(d) If the permit application to create or serve an ADU and/or a JADU is submitted with a permit application to create a new single-family dwelling on the lot, the Community Development Department may delay approving or denying the permit application for the ADU and/or JADU until the Community Development Department approves or denies the permit application to create the new single-family dwelling, but the application to create or serve the ADU and/or JADU shall be considered without discretionary review or hearing.

(e) The City shall not deny an application due to existing nonconforming zoning conditions, building code violations, or unpermitted structures that do not pose a threat to public health and safety and are not affected by the proposed ADU or JADU.

(f) Except as expressly permitted by California Government Code Section 66328, a certificate of occupancy for an ADU or JADU shall not be issued before issuance of a certificate of occupancy for the primary dwelling.

(g) The permitting of an ADU and/or a JADU is subject to the California Building Code (CBC) and California Residential Code (CRC), except that the construction of an accessory dwelling unit shall not constitute a Group R occupancy change under the local building code, as described in Section 310 of the California Building Code (Title 24 of the California Code of Regulations), unless the Building Official makes a written finding based on substantial evidence in the record that the construction of the accessory dwelling unit could have a specific, adverse impact on public health and safety.

(h) Modifications to an approved ADU or JADU require a new permit, processed pursuant to this section.

(i) Appeals.

(1) An applicant may appeal a determination of incompleteness or denial on a form provided by the City, together with the applicable appeal fee, within ten (10) calendar days of issuance of the written determination.

(2) Appeals shall be considered and decided ministerially and shall not include a public hearing.

(3) An appeal filed pursuant to this subsection shall be scheduled for consideration by the Planning Commission, and a final written decision shall be issued, within sixty (60) business days of receipt of the appeal.

(4) The decision of the Planning Commission shall be final and not subject to further appeal.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) Single-Family Zones.

(1) ADUs may be constructed on any lot in the R-A, R-E, R-O, R-1, RPD, or HPD zone, or within any adopted Specific Plan that is improved with one (1) existing or proposed primary dwelling unit. Each lot may have the State-mandated ADUs permitted by Section 9-4.4511. Each lot may have one (1) ADU that complies with the standards in Sections 9-4.4509 and 9-4.4510, which shall be counted as an ADU pursuant to Section 9-9-4.4511.

(b) Multi-Family Zones.

(1) Lots in the R-2, R-3, RPD, MU zone, or any adopted Specific Plan are allowed to have ADUs as permitted pursuant to Section 9-4.4511.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by Part 3, Ord. 1735-NS, eff. April 25, 2025, and Part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) One (1) off-street parking space shall be provided for an ADU, in addition to the parking required for the primary residence. ADU parking spaces may be covered or uncovered, may be located in any setback area, and may be tandem in a driveway.

(b) ADU parking spaces are required in addition to those required for the primary dwelling on the lot. However, that when a garage, carport, covered parking structure, or uncovered parking space is demolished or converted in conjunction with the construction of an ADU, those parking spaces are not required to be replaced.

(c) Parking in subsection (a) above is not required for an ADU in any of the following instances:

(1) The ADU is located within one-half (1/2) mile walking distance of public transit.

(2) The ADU is located within an architecturally and historically significant historic district.

(3) The ADU is part of the proposed or existing primary dwelling or an accessory structure and/or is created from the conversion or reconstruction of an existing structure.

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

(5) There is a car share vehicle located within one (1) block of the ADU.

(6) When a permit application for an accessory dwelling unit 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 accessory dwelling unit or the parcel satisfies any other criteria listed in this section.

(7) The accessory dwelling unit is five hundred (500') square feet of interior livable space or smaller.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by Part 6, Ord. 1735-NS, eff. April 25, 2025, and Part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) An ADU and/or JADU may be rented separately from the primary dwelling but may not be sold or otherwise conveyed separately from the primary dwelling except as provided in Government Code Section 66341.

(b) An ADU and/or JADU shall not be rented for a term of thirty (30) days or less.

(c) On a lot with a JADU, the property owner shall occupy either the primary dwelling or the JADU only when the JADU shares sanitation facilities with the primary dwelling, or when the owner is a governmental agency, land trust, or housing organization. When a JADU contains separate sanitation facilities, no owner-occupancy requirement shall apply, consistent with California Government Code Section 66333, as amended.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by Part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) Fire sprinklers are not required for the proposed ADU/JADU(s) if they are not required for the primary dwelling. The construction of an accessory dwelling unit shall not trigger a requirement for fire sprinklers to be installed in the existing primary dwelling.

(b) New or separate utility connections from the primary dwelling is required for ADUs, except for ADUs created from the conversion or reconstruction of an existing structure.

(c) ADUs utilizing an existing or proposed new onsite wastewater treatment system must demonstrate adequate septic feasibility to the satisfaction of, and be permitted by, the California State Water Resources Control Board prior to building permit issuance. Properties to be connected to an onsite wastewater treatment system shall submit an application for a new onsite wastewater treatment system concurrently with the application for Accessory Dwelling Unit Development. Construction of all wastewater treatment systems shall be permitted by the City and comply with the current plumbing and building code standards.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by Part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) An ADU/JADU may not be considered a new residential use by a local agency, special district, or water corporation to calculate utility connection fees or capacity charges unless the ADU/JADU is constructed with a new single-family dwelling.

(b) Impact fees may not be assessed by local agencies, special districts, or water corporations on an ADU smaller than seven hundred fifty (750') square feet of interior livable space. Impact fees may be assessed on an ADU of seven hundred fifty (750') square feet of interior livable space or greater in an amount proportionate to the square footage of the primary dwelling unit.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by Part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) Limits on unit location.

(1) No ADU shall be located within or encroach upon a natural slope steeper than twenty-five (25%) percent.

(2) ADUs proposed on properties that are located within the Protected Ridgeline Overlay zone are subject to the following objective standards:

(i) No new structure or addition to an existing structure shall be placed or constructed, no grading shall occur and, except as to meet fire clearance requirements, no native vegetation shall be removed within three hundred (300') feet horizontally or one hundred (100') feet vertically of the crest of a protected ridgeline unless the construction of the minimum allowed two (2) units of eight hundred (800') square feet or less is precluded, in which case the development must be sited at the lowest possible elevation.

(3) No ADU created pursuant to this article shall be constructed, or require grading at the time of construction, within the protected zone (as defined by Sections 9-4.4202 and 9-4.4302) of a protected tree unless the construction of the minimum of eight hundred (800') square feet or less is precluded, in which case the protected tree may be encroached upon or removed if replaced onsite per the recommendations of a City Arborist, on a 1:1 basis, with a thirty-six (36") inch box Quercus agrifolia Live Oak or Quercus lobata Valley Oak. If the replacement tree(s) is unable to be successfully sited onsite, an in-lieu fee will be required per Resolution 2010-014, as may be amended.

(b) Conversion within or attached to primary dwelling accessory dwelling units.

(1) The maximum size is eight hundred fifty (850') square feet of interior livable space or fifty (50%) percent of the existing primary dwelling’s total floor area, whichever is greater. The minimum size is the same as an efficiency dwelling.

(2) The side and rear setbacks are four (4) feet from the property line for new enclosed square footage for the attached ADU. The front setback is the same as required for the primary dwelling.

(3) The maximum height is twenty-five (25') feet, or the height limitation as detailed in Section 9-4.2501 that applies to the primary dwelling, whichever is lower.

(4) A full kitchen and sanitation facilities are required and must be separate from the primary dwelling.

(5) Attached and converted ADUs must share a minimum of ten (10') feet of the wall of the main single-family home. No internal connection is permitted.

(c) Detached accessory dwelling units.

(1) The maximum size of a detached ADU is one thousand (1,000') square feet of interior livable space.

(2) The side and rear setbacks are four (4') feet from the property line. The front setback is the same as required for the primary dwelling.

(3) The maximum height is sixteen (16') feet.

(4) The maximum height can be increased to eighteen (18') feet for a detached accessory dwelling unit on a lot with an existing or proposed single-family dwelling unit that is within one-half (1/2) mile walking distance from a major transit stop or a high-quality transit corridor, as those terms are defined in Section 21155 of the Public Resources Code.

(5) The maximum height can be increased by two (2) feet to accommodate a roof pitch that is aligned with the roof pitch of the primary dwelling unit.

(6) Detached ADUs may not be attached to the existing single-family dwelling by breezeways or any similar structure and must be separated from any proposed or existing structure by a minimum of six (6') feet as measured from the face of wall to the nearest face of wall.

(d) Accessory structures.

(1) No accessory structure shall be attached to a detached ADU unless the combined total floor area of the accessory structure and ADU does not exceed the allowable size of the ADU.

(2) Where a detached ADU is proposed with an attached garage, the garage portion shall be no larger than four hundred (400') square feet.

(3) The size of any proposed patio cover(s) and/or covered porch(s) will be cumulatively limited to ten (10%) percent of the square footage of the proposed ADU. The patio cover and/or covered porch square footage is not to be included in the total livable space calculation in Section 9-4.4509(c)(1).

(4) An ADU attached to an accessory structure shall not have internal access to the accessory structure.

(e) Conversion of existing structures.

(1) A portion of an existing legally established single-family dwelling, or all or a portion of an accessory structure, may be converted to an ADU, even if such structure does not comply with the otherwise applicable height and setback requirements.

(2) An accessory structure may be demolished and reconstructed in the same location and to the same dimensions and may be fully or partially converted to a detached ADU, even if such structure does not comply with the otherwise applicable height and setback requirements.

(3) An accessory structure, including a demolished and reconstructed structure, that is being fully or partially converted to a detached ADU, may be expanded by up to one hundred fifty (150') square feet to accommodate ingress and egress. Any new construction proposed for ingress/egress must be setback from the side and rear yards at least four (4') feet and have a maximum height that matches the accessory structure or sixteen (16') feet, whichever is less.

(4) Attached ADUs converted from the existing primary dwelling can add one hundred fifty (150') square feet for the purpose of ingress and egress, not to exceed the square footage allowance. Any new construction proposed for the purposes of ingress/egress must be setback from the side and rear yards at least four (4') feet and have a maximum height that matches the existing structure or sixteen (16') feet, whichever is less.

(5) Where an attached garage that provides the required parking for a primary dwelling is partially converted to an ADU, the remaining space shall continue to be utilized for parking if physically feasible. If it is not feasible for the remaining space to be used for parking, the remaining space shall be utilized for storage or similar non-habitable use for the primary dwelling.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by Part 4, Ord. 1735-NS, eff. April 25, 2025, and Part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) Design and features.

(1) The materials and colors of exterior walls, roof, eaves, windows, and doors of an attached or converted ADU must match those of the primary dwelling.

(2) The roof slope of an ADU must match the dominant roof slope of the primary dwelling. The dominant roof slope is the slope shared by the largest portion of the roof as measured by the footprint of the roofed area and not the face of the roof. If a structure has multiple equal dominant roof slopes as measured by the footprint of the roofed area, the dominant slope closest to the public-right-of-way shall be followed.

(3) A newly constructed detached ADU must incorporate a minimum of one material and one color from the existing or proposed primary dwelling unit.

(4) All ADU windows that are constructed within ten (10') feet of an adjoining residential property shall only contain privacy glass (minimum of fifty (50%) percent opacity) to screen views directly into adjoining residential properties.

(5) Skylights are permitted on roofs above ten (10') vertical feet of the first-floor wall plane. Skylights must be flat and not domed.

(6) Roof-top decks above ADUs are prohibited.

(7) No roof-mounted mechanical equipment shall be allowed on ADUs. All ground-mounted mechanical equipment shall be located outside the four (4')-foot side and rear yard setbacks.

(b) Exterior Ingress/Egress.

(1) All ADUs must have an independent exterior entrance separate from the primary dwelling.

(2) Separate exterior access for attached ADUs shall be provided on a different wall face than the primary residence's entry door.

(c) Second-story ADU(s).

(1) Exterior stairs are not permitted. Stairs or elevator must be interior and meet four (4') foot side and rear setbacks, with an overhang of one (1') foot or less.

(2) The colors and material of all building walls must be the same as the primary dwelling unit.

(3) The color, slope, style, and material of the roof must be the same as the primary dwelling unit.

(4) ADUs that are newly constructed (not converted from existing square footage) shall be set back a minimum of two (2') feet from the existing first floor wall plane.

(5) To avoid blank facades for second-story conversions and additions for the purpose of creating an ADU, ADUs shall incorporate at least two (2) of the following standards:

(i) A minimum one (1') foot offset for any wall plane that exceeds twenty (20') feet in length.

(ii) Windows or door openings that cover at least ten (10%) percent of the facade and match the color and style of the primary dwelling.

(iii) Landscaping or privacy glass must be installed to prevent a direct line of sight from the ADU windows to a contiguous developed residential property.

(iv) Architectural details which provide visual interest such as awnings, ornamental light fixtures, window shutters, columns, cornices, moldings, trellises, etc.

(d) Driveway access.

(1) An ADU must be served by the same driveway access to the street as the existing primary dwelling unit unless the ADU has access from a public alley contiguous to the lot or is located on a corner lot for which secondary vehicular access is already permitted.

(2) The driveway may only be removed if it is replaced with landscaping or open space, and the curb cut and driveway apron are removed and replaced with a curb and gutter which meet city standards.

(e) Required walkway separation.

(1) Pedestrian walkways are required to provide access from the right-of-way to the entrance of the ADU, if not already provided.

(f) Conversion of a garage to ADU.

(1) The garage door shall be removed, and window(s) shall be installed in its place incorporating the window style and architectural elements found on the primary dwelling.

(2) The installation of a new wall shall include at least ten (10%) percent of the facade with doors and/or windows.

(3) Street facing garage conversions shall provide a minimum of three (3') feet landscaping directly in front of the converted garage wall, except for where an entrance is proposed.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by Part 5, Ord. 1735-NS, eff. April 25, 2025, and Part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) The City shall ministerially approve an application for a building permit pursuant to Section 9-4.4504 to create any of the following units, or any combination of the units:

(1) Conversions on single-family lots: One (1) ADU and one (1) JADU on a lot with a proposed or existing single-family dwelling on it, where the ADU or JADU:

(i) Is either: within the space of a proposed single-family dwelling; within the existing space of an existing single-family dwelling; or in the case of an ADU only, within the existing space of an existing accessory structure, plus up to one hundred fifty (150') additional square feet if the expansion is limited to accommodating ingress and egress;

(ii) Has exterior access that is independent of that for the single-family dwelling; and

(iii) Has side and rear setbacks sufficient for fire and safety, as dictated by applicable building and fire codes.

(iv) The JADU complies with the requirements as described in this article.

(2) A newly constructed detached ADU on single-family lots: One (1) detached, new-construction ADU on a lot with a proposed or existing single-family dwelling, if the detached ADU satisfies the following limitations:

(i) The side- and rear-yard setbacks are at least four (4') feet;

(ii) The interior livable space area is eight hundred (800') square feet or smaller; and

(iii) Any height limitation shall allow at least the following, as applicable:

a. A height of sixteen (16') feet or less.

b. A height of eighteen (18') feet for the unit located within one-half (1/2) mile walking distance of a major transit stop or a high-quality transit corridor, as defined in Section 21155 of the Public Resources Code. An additional two (2') feet to accommodate a roof pitch that is aligned with the roof pitch of the primary dwelling.

(3) Conversions on lots with existing multifamily dwellings: At least one ADU, and up to twenty-five (25%) percent of the existing multifamily dwelling units, within portions of existing multifamily dwelling structures 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.

(4) Detached ADUs on multifamily lots with existing multifamily dwelling: Not more than eight (8) detached ADUs, or as many ADUs as there are existing units on the lot, whichever is less, provided that each detached ADU satisfies the following limitations:

(i) The side- and rear-yard setbacks are at least four (4') feet. If the existing multifamily dwelling has a rear or side setback of less than four (4') feet, no modification of the existing multifamily dwelling is required.

(ii) Any height limitation shall allow at least the following, as applicable:

a. A height of sixteen (16') feet or less for single-story dwellings.

b. Eighteen (18') feet for a detached accessory dwelling unit on a lot with a multistory dwelling.

c. A height of eighteen (18') feet for a detached accessory dwelling unit located within one-half (1/2) 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. An additional two (2') feet in height shall be permitted to accommodate a roof pitch on the accessory dwelling unit that is aligned with the roof pitch of the primary dwelling unit.

(5) Detached ADUs on lot with proposed multifamily dwelling: Not more than two (2) detached ADUs, provided that each detached ADU satisfies the following limitations:

(i) The side- and rear-yard setbacks are at least four (4') feet.

(ii) Any height limitation shall allow at least the following, as applicable:

a. A height of sixteen (16') feet or less for single-story dwellings. Eighteen (18') feet for multifamily, multistory dwellings; or

b. A height of eighteen (18') feet for a detached accessory dwelling unit located within one-half (1/2) 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. An additional two (2') feet in height shall be permitted to accommodate a roof pitch on the accessory dwelling unit that is aligned with the roof pitch of the primary dwelling unit.

(§ 2, Ord. 1732-NS, eff. November 22, 2024, as amended by Part 7, Ord. 1735-NS, eff. April 25, 2025, and Part 1, Ord. 1747-NS, eff. April 10, 2026)

(a) Location and configuration. A JADU shall be created only through the conversion of existing space within an existing or proposed single-family dwelling, including an attached garage. A JADU shall not be created through new construction or expansion of the primary dwelling.

(b) Development standards.

(1) JADUs are to be constructed within the walls of the proposed or existing single-family residence, including an attached garage.

(2) The JADU shall include a separate entrance from the main entrance to the single-family residence.

(3) The maximum size is five hundred (500') square feet of interior livable space, and the minimum size is the same as an efficiency dwelling unit.

(4) Sanitation facilities may be separate from or shared with the primary dwelling. If the JADU does not include a separate bathroom, the JADU shall include an interior entry to the main living area.

(c) Deed restriction. Upon approval of a JADU, a deed restriction running with the land in a form provided by the City must be recorded with the Ventura County Recorders Office at the Property owner's expense. The deed restriction must include the following:

(1) The property owner shall be required to occupy either the primary dwelling or the JADU only if the JADU shares sanitation facilities with the primary dwelling. No owner-occupancy requirement shall apply if the JADU has separate sanitation facilities, or when the owner is a governmental agency, land trust, or housing organization;

(2) A prohibition on the sale of the JADU separate from the sale of the single-family dwelling, including a statement that the deed restriction may be enforced against future purchasers;

(3) A restriction on the size and attributes of the JADU that conforms with this article and Government Code Section 66333 et seq;

(4) Notice and disclosure to future owners of the owner occupancy requirement; and

(5) The deed restriction is enforceable by the Community Development Department or their designee for the benefit of the City. Failure of the property owner to comply with the deed restriction may result in legal action against the property owner, and the City is authorized to obtain any remedy available to it at law or equity, including, but not limited to, obtaining an injunction enjoining the use of the JADU in violation of the recorded restrictions or abatement of the illegal unit.

(Part 1, Ord. 1747-NS, eff. April 10, 2026