Article 49 — Accessory Dwelling Units and Junior Accessory Dwelling Units

Purpose.

The provisions of this section are intended to set standards, in compliance with California Government Code Sections 65852.2 and 65852.22, for the development of accessory dwelling units so as to increase the supply of smaller and affordable housing while ensuring that such housing remains compatible with the existing neighborhood.

(Ord. No. 568, 5-20-2025)

An accessory dwelling unit:

(a)

May be located on any lot that allows a single-family or multifamily residential use and includes a proposed or existing dwelling.

(b)

Is not subject to the density requirements of the general plan, but shall otherwise be consistent with the general plan text and diagrams.

(c)

Shall not be used for rentals with terms of less than thirty days.

(Ord. No. 568, 5-20-2025)

An application for an accessory dwelling unit or junior accessory dwelling unit that complies with all applicable requirements of this section shall be approved ministerially.

(a)

If the department, together with utility providers and county environmental health when a septic system is utilized, has not approved or denied the completed application within sixty days, the application shall be deemed approved. If the department denies an application for an accessory dwelling unit or junior accessory dwelling unit, it shall provide in writing 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 by the applicant.

(b)

A permit shall not be denied due to the correction of nonconforming zoning conditions, building code violations, or unpermitted structures that do not present a threat to public health and safety and are not affected by the construction of the accessory dwelling unit.

(c)

A permit shall not be denied for an unpermitted accessory dwelling unit that was constructed before January 1, 2018, because, among other conditions, the unit is in violation of building standards or state or local standards applicable to accessory dwelling units, unless the department finds that correcting the violation is necessary to protect the health and safety of the public or occupants of the structure.

(d)

A demolition permit for a detached garage that is to be replaced with an accessory dwelling unit shall be reviewed with the application for the accessory dwelling unit and issued at the same time. The applicant is

not required to provide written notice or post a placard for the demolition of a detached garage that is to be replaced with an accessory dwelling unit.

(Ord. No. 568, 5-20-2025)

(a)

Step One—Submittal. The application for an accessory dwelling unit permit shall be submitted to the department concurrent with an application for a building permit. In addition to the standard submittal requirements for a building permit, an application for an accessory dwelling unit permit shall include all of the following (except as noted below):

a.

Plot plan. A plot plan, drawn to scale, showing the dimensions of the perimeter of the parcel proposed for the accessory dwelling unit; the location and dimensioned setbacks of all existing and proposed structures on the site and structures located within fifty feet of the site; all easements, building envelopes, and special requirements of the subdivision as shown on the final map and improvement plans, if any; and average slope calculations for the site.

b.

Floor plan. A floor plan, drawn to scale, showing the dimensions of each room, and the resulting floor area. The use of each room shall be identified, and the size and location of all windows and doors shall be clearly shown.

c.

Elevations. Architectural elevations of each side of the proposed structure showing all wall height dimensions, openings, exterior finishes (including siding and window materials), original and finish grades, paint color, and roof pitch. The color of the existing or proposed primary residence shall be included if necessary to demonstrate compliance with section 49.09.a, below. Applications for accessory dwelling units which do not modify a building's exterior are not required to submit elevations per this subsection c.

(b)

Step Two—Decision. The department shall approve or deny an application for an accessory dwelling unit permit within sixty days of submittal of a complete application. The accessory dwelling unit permit shall be issued only if the proposed accessory dwelling unit complies with all applicable standards in this section.

(Ord. No. 568, 5-20-2025)

(a)

Except as provided in subsection 49.04.b, a separate new utility connection and payment of a connection fee or capacity charge pursuant to state law and city fee schedule will be required for any new accessory

dwelling unit.

(b)

No new or separate utility connection or related connection fee or capacity charge will be required for accessory dwelling units that are internal conversions of existing space within a single-family residence or an accessory structure, or for accessory dwelling units that are seven hundred fifty square feet or smaller. Any fee charged for an accessory dwelling unit of seven hundred fifty square feet or more shall be charged proportionately in relation to square footage of the primary dwelling unit.

(Ord. No. 568, 5-20-2025)

An accessory dwelling unit permit shall be issued only if the unit complies with the following development standards:

(a)

General.

a.

No development standards shall be applied that would prohibit up to an eight hundred square foot accessory dwelling unit that is no more than sixteen feet in height with four-foot side and four-foot rear setbacks to be constructed in compliance with all other local development standards.

(b)

Setbacks.

a.

Single-family residential districts including single-family planning department zone districts. An accessory dwelling unit shall comply with the following setback requirements:

i.

A new attached or detached eight hundred square foot accessory dwelling unit shall provide a minimum four-foot side and four-foot rear setback, and a front setback consistent with that of the primary dwelling unit in a standard zoning district. An eight hundred square foot accessory dwelling unit that complies with all other development standards may be built within the front yard setback of a lot if it is otherwise physically infeasible to build an accessory dwelling unit on other areas of the lot while maintaining the minimum rear and side yard setbacks outlined in this subsection. Side-corner setbacks shall be a minimum of four feet.

b.

Multifamily districts including multifamily districts. An accessory dwelling unit shall comply with the following setback requirements:

i.

A new attached or detached accessory dwelling unit shall provide a minimum four-foot side and four-foot rear setback. The front setback shall be consistent with a primary dwelling unit in the applicable standard zoning district, or the most similar standard zoning district. Side-corner setbacks shall be a minimum of eight feet.

c.

If the existing multifamily dwelling exceeds height requirements or has a rear or side setback of less than four feet, the department shall not require modification of the existing multifamily dwelling as a condition of approving the application to construct an accessory dwelling unit.

(c)

No setback shall be required for an existing legally constructed living area, garage, or other accessory structure that is converted to an accessory dwelling unit with independent exterior access from an existing or proposed residence. A setback of five feet from the side and rear property lines is required for an accessory dwelling unit constructed above an existing legally constructed or proposed garage.

(d)

Any new attached accessory dwelling unit, detached accessory dwelling unit or expansion of the single- family dwelling to support the internal conversion for an accessory dwelling shall be designed to maintain appropriate setbacks, as described in subsection B (a) and (b) above, from the future width of any abutting public streets. Future street configurations shall be based on the widths, standards and right-of-way lines in the circulation element of the City of Colusa General Plan or specifically addressed in a resolution adopted by the city council.

(Ord. No. 568, 5-20-2025)

(a)

New Detached ADUs: A newly constructed detached accessory dwelling unit (ADU) shall not exceed one thousand two hundred square feet of habitable space.

(b)

New Attached ADUs: A newly constructed attached ADU shall not exceed fifty percent of the existing residential square footage, except:

• A minimum of eight hundred fifty square feet must be allowed for a studio or one-bedroom ADU.

• A minimum of one thousand square feet must be allowed for ADUs with more than one bedroom.

(c)

Internal Conversion ADUs: An ADU created entirely within an existing single-family dwelling shall not exceed forty-five percent of the existing habitable space, excluding the garage, or one thousand two hundred square feet, whichever is less. However:

○ A minimum of eight hundred fifty square feet must be allowed for a studio or one-bedroom ADU.

○ A minimum of one thousand square feet must be allowed for ADUs with more than one bedroom.

(a)

An ADU created entirely within a detached accessory structure shall not exceed one thousand two hundred square feet.

(b)

Fire Sprinkler Requirement: An automatic fire sprinkler system must be installed in any building that undergoes a substantial remodel, addition, or both, if the total floor area is increased by more than fifty percent.

(Ord. No. 568, 5-20-2025)

(a)

A one-story accessory dwelling unit shall not exceed a maximum height of 16 feet, except as follows:

a.

The department shall allow an additional two feet in height (up to eighteen feet) to accommodate a roof pitch on an accessory dwelling unit that is aligned with the roof pitch on the primary dwelling unit.

b.

A detached accessory dwelling unit on a lot with an existing or proposed single-family or multi-family dwelling unit that is within one-half mile walking distance of a major transit stop or a high-quality transit corridor shall not exceed a height of eighteen feet.

c.

A height of eighteen feet is also permitted for a detached accessory dwelling unit on a lot with an existing or proposed multifamily, multistory dwelling. A height of twenty-five feet applies to an accessory dwelling unit that is attached to a primary dwelling. This provision does not require the department to allow an accessory dwelling unit to exceed two stories.

(b)

A two-story accessory dwelling unit shall not exceed a maximum height of twenty-seven feet. No accessory dwelling unit shall exceed twenty-seven feet in height.

(c)

When an accessory dwelling unit is located above an existing or proposed garage, carport or other accessory structure, the entire combined structure shall not exceed twenty-seven feet in height. No accessory dwelling unit shall exceed twenty-seven feet in height.

(Ord. No. 568, 5-20-2025)

An accessory dwelling unit (ADU) must comply with the lot coverage requirements of the applicable zoning district. If the property is in a zoning district without specific ADU standards, the most similar zoning district shall apply, as determined by the planning department.

(Ord. No. 568, 5-20-2025)

(a)

Architectural compatibility between the accessory dwelling unit and primary dwelling unit shall be demonstrated by matching two or more of the following qualities of the accessory dwelling unit to the proposed or existing primary dwelling unit:

a.

Color;

b.

Siding material and style; or

c.

Architectural design elements and features, (e.g., roof pitch, window style, trim details).

(b)

Exterior Entrance. An accessory dwelling unit must include a separate exterior entrance.

(c)

Privacy. A balcony, window or door of a second story accessory dwelling unit shall be designed to lessen privacy impacts to adjacent properties. Appropriate design techniques include obscured glazing, window placement above eye level, screening treatments, or locating balconies, windows and doors toward the existing on-site residence.

(d)

Residential Development. A residential dwelling must already exist on the lot or shall be constructed on the lot in conjunction with the construction of the accessory dwelling unit.

Number of Units. No more than the number of ADUs allowed by state law may be constructed on any lot.

(Ord. No. 568, 5-20-2025)

(a)

One off-street parking space is required for an ADU, except as outlined below. Parking may be uncovered, compact, tandem, or located within setback areas, unless deemed infeasible by the review authority due to site constraints, topography, or fire and life safety concerns.

a.

The ADU is seven hundred fifty square feet or less or a studio unit.

b.

The ADU is within an existing primary residence or an existing accessory structure.

c.

The ADU is permitted concurrently with a new single-family or multi-family dwelling on the same lot.

d.

The ADU is created by converting or demolishing a garage, carport, or covered parking structure (no replacement parking required).

(Ord. No. 568, 5-20-2025)

dwelling unit.

(a)

A proposed accessory structure with a floor area less than fifty percent of the accessory dwelling unit floor area:

a.

Shall be processed ministerially in conjunction with the accessory dwelling unit.

b.

Shall comply with the lot coverage and setback requirements of this section.

(b)

A proposed accessory structure with a floor area that exceeds fifty percent of the total floor area of the accessory dwelling unit:

a.

Is subject to any discretionary review required by this zoning code.

b.

Shall comply with lot coverage, height, and setback requirements for an accessory structure in the applicable standard zoning district or the most similar standard zoning district.

Junior accessory dwelling unit.

The following provisions are intended to set standards, in compliance with California Government Code Section 65852.22, for the development of junior accessory dwelling units so as to increase the supply of smaller and affordable housing while ensuring that such housing remains compatible with the existing neighborhood. This section does not intend to override lawful use restrictions as set forth in conditions, covenants and restrictions.

(Ord. No. 568, 5-20-2025)

A junior accessory dwelling unit:

(a)

May be located on any lot that allows single-family or multifamily dwellings and that contains only one existing or proposed single-family detached dwelling. Only one junior accessory dwelling unit shall be permitted per parcel.

(b)

Is not subject to the density requirements of the general plan but shall otherwise be consistent with the general plan text and diagrams.

(c)

Shall not be used for rentals with terms of less than thirty days.

(Ord. No. 568, 5-20-2025)

An application for a junior accessory dwelling unit that complies with all applicable requirements of this section shall be approved ministerially.

(Ord. No. 568, 5-20-2025)

(a)

Step One—Submittal. The application for a junior accessory dwelling unit permit shall be submitted to the department concurrent with an application for a building permit. In addition to the standard submittal requirements for a building permit, an application for a junior accessory dwelling unit permit shall include all the following:

a.

Plot plan. If any expansion of the foundation is required for a junior accessory dwelling unit, a plot plan, drawn to scale, showing the dimensions of the perimeter of the parcel proposed for the junior accessory dwelling unit; the location and dimensioned setbacks of all existing and proposed structures on the site and structures located within fifty feet of the site; all easements, building envelopes, and special requirements of the subdivision as shown on the final map and improvement plans, if any; and average slope calculations for the site.

b.

Floor plan. A floor plan, drawn to scale, showing the dimensions of each room, the area devoted to the junior accessory dwelling unit, and the resulting floor areas of the junior accessory dwelling unit and of the primary residence. The use of each room shall be identified, and the size and location of all windows and doors shall be clearly shown. The plan shall identify whether separate or shared sanitation facilities are proposed.

c.

Deed restrictions. Deed restrictions completed, signed and ready for recordation in compliance with subsection G.

(b)

Step Two—Decision. The department shall approve or deny an application for a junior accessory dwelling unit permit within sixty days of submittal of a complete application. A junior accessory dwelling unit permit shall be issued only if the proposed junior accessory dwelling unit complies with all applicable standards in this section. A permit for a junior accessory dwelling unit shall not be denied due to the correction of nonconforming zoning conditions, building code violations, or unpermitted structures that do not present a threat to public health and safety and are not affected by the construction of the junior accessory dwelling unit.

(Ord. No. 568, 5-20-2025)

No new or separate utility connection and no connection fee for water, sewer, or power is required for a junior accessory dwelling unit.

(Ord. No. 568, 5-20-2025)

A junior accessory dwelling unit permit shall be issued only if the unit complies with the following development standards:

(a)

Maximum floor area. The junior accessory dwelling unit shall not exceed five hundred square feet in total floor area.

(b)

Existing development. The junior accessory dwelling unit shall be contained entirely within the existing walls of an existing or proposed single-family dwelling, which includes the walls of an attached garage. However, an additional one hundred fifty square feet is permitted to allow for a separate entrance into the unit.

(c)

Kitchen. The junior accessory dwelling unit must contain an efficiency kitchen as defined by the Government Code Section 66333(f)(1) and (f)(2)

(d)

Sanitation. Bathroom facilities may be separate from or shared with the single-family dwelling. A separate bathroom facility shall be provided if the junior accessory dwelling unit does not include an interior entry into the primary residence.

(e)

Entrance. The junior accessory dwelling unit shall include an exterior entrance separate from the main entrance to the single-family dwelling. The junior accessory dwelling unit may include a second interior doorway for sound attenuation.

(f)

Parking. Off-street parking shall not be required for junior accessory dwelling units. No replacement off- street parking spaces are required when a junior accessory dwelling unit is created through the conversion or demolition of an attached garage, carport or covered parking structure.

(Ord. No. 568, 5-20-2025)

Prior to occupancy of a junior accessory dwelling unit, the property owner shall file with the county recorder a deed restriction containing a reference to the deed under which the property was acquired by the owner and stating that:

(a)

The junior accessory dwelling unit shall not be sold separately from the single-family residence;

(b)

The junior accessory dwelling unit shall be considered legal only if either the primary residence or junior accessory dwelling unit is occupied by the owner of the property's record. Such owner-occupancy, however, shall not be required if the property owner is a governmental agency, land trust or non-profit housing organization;

(c)

The restrictions shall run with the land and be binding upon any successor in ownership of the property. Lack of compliance shall void the approval junior accessory dwelling unit and may result in legal action against the property owner;

(d)

The developer of a subdivision that includes junior accessory dwelling units shall record the deed restrictions required by this subsection before the final map or parcel map. Each lot with a junior accessory dwelling unit shall remain unoccupied until the property transfers ownership, allowing for compliance with the recorded owner-occupancy restriction;

(e)

A junior accessory dwelling unit shall not exceed five hundred square feet of total floor area and shall comply with the development standards in subsection 49.19.

(Ord. No. 568, 5-20-2025)

CODE COMPARATIVE TABLE AND DISPOSITION LIST

This is a chronological listing of the ordinances of Colusa, California, beginning with Supplement No. 17, included in this Code.