The purposes of this chapter are to authorize second units; to establish a procedure for reviewing and approving their development to ensure and maintain healthy and safe residential living environments; to establish location and development standards for second units; and to comply with Government Code Section 65852.2, which requires local agencies to consider applications for second unit permits ministerially without discretionary review or a public hearing. (Ords. 2003-17 § 3, 87-67 § 3).

For purposes of this chapter, “second unit” has the meaning set forth in California Government Code Section 65852.2. (Ords. 2003-17 § 3, 87-67 § 3).

An application for a second unit permit that meets the location and development standards contained in this chapter and all applicable building standards in Title 7 shall be approved ministerially without discretionary review or public hearing. (Ord. 2003-17 § 3).

(a) One second unit may be located on any lot in a single-family residential district (R-6, R-7, R-10, R-12, R-15, R-20, R-40, R-65, and R-100), planned unit district (P-1) for residential uses, or a multiple-family residential district (M-6, M-9, M-12, M-17, and M-29).
(b) One second unit may be located on any lot in an agricultural district (A-2, A-3, A-4, A-20, A-40, and A-80). If a second unit is proposed for a lot under a Williamson Act contract, a second unit will be allowed only if the contract authorizes the second unit on the property.
(c) No subdivision rights are authorized that would result in the second unit being located on a separate lot. (Ords. 2006-19 § 2, 2003-17 § 3, 87-67 § 3).

(a) An application for a second unit permit must be submitted to the community development department prior to the submittal to the county of a building permit application.
(b) An application for a second unit permit must be made in writing and contain the following information:
(1) Name(s) and address(es) of applicant(s) and property owner(s).
(2) Address and assessor’s parcel number for the lot.
(3) Size, indicating dimensions and square footage of the primary residence and the proposed second unit.
(4) A legible scale drawing, showing:
(A) A north arrow to indicate parcel orientation.
(B) Lot dimensions and labels for all property lines.
(C) Siting and location of the primary residence and the proposed second unit.
(D) Floor plan configuration of the primary residence and the proposed second unit.
(E) All other existing improvements, including driveways and parking areas.
(F) Exterior design of the primary residence and the proposed second unit. “Exterior design” includes architectural style and exterior features, such as trim, windows, and roof.
(5) A description of the building and roof materials of the primary residence and second unit, and a sample board of the colors of the primary residence and second unit.
(6) Color photographs of the primary residence and surrounding properties taken from each of the property lines of the project site.
(7) Location and description of water and sanitary services for both the primary residence and the proposed second unit.
(8) Property owner’s consent to physical inspection of the premises.
(9) A written legal description of the property.
(Ords. 2003-17 § 3, 87-67 § 3).

A second unit permit will be issued only if it complies with the following development standards:
(a) Yards and Building Height.
(1) In single-family and multifamily residential districts, second units must comply with requirements relating to yards (front setbacks, side, and rear) and building height that are generally applicable to residential construction in the zone in which the property is located.
(2) In P-1 planned unit districts where an approved final development plan specifies requirements relating to yards (front setbacks, side, and rear) and building height, second units must comply with the requirements specified in the plan. In P-1 planned unit districts where an approved final development plan does not specify requirements relating to yards and building height, second units must comply with requirements relating to yards and building height that are generally applicable to residential construction in the R-6 zone.
(b) Lot Size. The minimum size of a lot with a primary residence and a second unit is six thousand square feet. Applications for a second unit permit are exempt from the requirements of Ordinance Code Section 82-10.002(c).
(c) Second Unit Configuration.
(1) Second Unit Attached to an Existing Primary Residence. A second unit may be attached to an existing primary residence only if the second unit is one of the following:
(A) An internal conversion of a garage or other area within the existing primary residence.
(B) An addition to the existing primary residence.
(2) Second Unit Attached to an Accessory Structure. A second unit may be attached to an existing or newly constructed accessory structure only if the accessory structure meets all of the following requirements:
(A) The remainder of the accessory structure is limited to garage space.
(B) The accessory structure complies with all requirements relating to yards (front setbacks, side, and rear) and building height that are applicable to the primary residence in the zone in which the property is located.
(C) The total floor area of the accessory structure does not exceed the following size:
(i) Four hundred square feet, not including the second unit, in any zoning district where a second unit is allowed, except for an accessory structure located on a parcel of five acres or more in an agricultural district.
(ii) Eight hundred square feet, not including the second unit, in an agricultural district where the accessory structure is located on a parcel of five acres or more.
(3) Detached Second Unit. A second unit may be detached from an existing primary residence only if the second unit is located on the same lot as the existing primary residence.
(d) Second Unit Size. A second unit must not exceed the following size:
(1) One thousand square feet, if the second unit is located in any zoning district where a second unit is allowed, except for a second unit located on a parcel of five acres or more in an agricultural district.
(2) One thousand two hundred square feet, if the second unit is located on a parcel of five acres or more in an agricultural district.
(e) Lot Coverage.
(1) In single-family residential districts, the second unit must not cause the maximum total structural lot coverage to exceed forty percent. In multiple-family residential districts, the second unit must not cause the maximum total structural lot coverage to exceed twenty-five percent in the M-6 through M-17 districts or thirty-five percent in the M-29 district.
(2) In P-1 planned unit districts where an approved final development plan specifies maximum total structural lot coverage, the second unit must not cause the maximum total structural lot coverage to exceed the specified percentage. In P-1 planned unit districts where an approved final development plan does not specify maximum total structural lot coverage, the second unit must not cause the maximum total structural lot coverage to exceed forty percent.
(f) Living Provisions. A second unit must provide complete independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking, and sanitation. The second unit may include one kitchen, living room, and dining room, and no more than two bathrooms and two bedrooms.
(g) Entry. The second unit must have a separate entrance located on either building side or rear and not visible from the street front area.
(h) Off-Street Parking. A lot containing a second unit must provide an additional off-street parking space to serve the second unit. The additional space may be in tandem, or the additional space may be in the existing driveway if the additional space is outside the existing setback or side yard. The exception under Ordinance Code Section 84-4.1202 shall not apply to lots for which a second unit permit is issued.
(i) Architectural Compatibility. The second unit must incorporate the same exterior design, building and roof materials, and colors as the primary dwelling unit. “Exterior design” includes architectural style and exterior features, such as trim, windows, and roof.
(j) Permanent Foundation. A permanent foundation is required for all second units.
(k) Sewage and Water. If a private sewage disposal system, water system or both are proposed to be used, it must meet all applicable county regulations and be approved by the health officer before a second unit may be established. Verification that the standard has been met is required prior to final inspection. (Ords. 2008-09 § 2, 2006-19 § 3, 2003-17 § 3, 87-67 § 3).

The owner of a parcel with a second unit shall occupy either the primary dwelling unit or the second unit. (Ords. 2003-17 § 3, 87-67 § 3).

Before obtaining a second unit permit, the applicant shall do the following:
(a) Enter into an agreement of restrictions with the county that refers to the deed under which the property was acquired by the applicant and provides the following:
(1) The second unit shall not be sold separately.
(2) The second unit is restricted to the maximum size allowed under Ordinance Code Section 82-24.012.
(3) The restrictions are binding upon any successor in ownership of the property and lack of compliance may result in legal action by the county against the property owner.
(b) Record the agreement with the county recorder.
(c) Prepare a disclosure statement that shall be included in any future offer or sale documents. The statement shall read as follows:

“You are purchasing a property with a permit for a second residential unit. This permit carries with it certain restrictions that must be met by the owner of the property. You are prohibited from selling the second unit separately. The second unit is restricted to the maximum size allowed under County Ordinance Code Section 82-24.012. The permit is available from the current owner or from the Contra Costa County Community Development Department.”

(Ords. 2003-17 § 3, 87-67 § 3).

Notwithstanding the provisions of Ordinance Code Section 82-8.006, if the existing primary residence is a legal nonconforming unit, a second unit may be constructed only if the nonconformity is not expanded and the second unit meets all current applicable zoning and building standards. (Ords. 2003-17 § 3, 87-67 § 3).

Fees for second unit permits will be in amounts established by the board of supervisors in the community development department’s fee schedule. Second units are subject to all new development fees, including but not limited to development impact fees, park fees, and assessment district assessment allocations. (Ords. 2003-17 § 3, 87-67 § 3).