Accessory Dwelling Units in RS-6 Single-Family Residential Zoning Districts

Accessory Dwelling Units (ADUs) are permitted in the RS-6 Single-Family Residential zoning district, provided they comply with the development standards outlined in the Concord Development Code. Homeowners must obtain a building permit, which is processed ministerially within 60 days of the receipt of a complete application, to establish an ADU or Junior Accessory Dwelling Unit (JADU).

Permissibility and General Requirements

In the RS-6 Single-Family Residential zoning district, Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs) are permitted as accessory uses to a single-family principal dwelling [Section 18.200.180(D)(1)].

All ADUs and JADUs must adhere to the following core requirements:

Building Permit: A building permit is required for all ADU and JADU construction, which must comply with the California Building Code [Section 18.200.180(C)(1)].
Permanent Foundation: All ADUs must be constructed on a permanent foundation system in accordance with the Uniform Building Code [Section 18.200.180(C)(2)].
Short-Term Rentals: Renting an ADU or JADU for a term of less than 30 days is prohibited [Section 18.200.180(C)(5)].
Subdivision: Subdivision of land or air rights to sell an ADU or JADU independently of the principal dwelling is prohibited; however, they may be leased separately [Section 18.200.180(C)(4)].

Size and Design Standards for Accessory Dwelling Units

ADUs are subject to specific size limitations based on the floor area of the principal dwelling on the property.

Standard	Requirement
Minimum Living Area	150 square feet
Maximum Size (General)	The lesser of 50% of the principal dwelling's floor area or 1,000 square feet
Maximum Size Waiver	Size limitations are waived if they restrict the ADU to less than 800 square feet

Design and Exterior

Except for pre-approved units, ADUs must maintain visual consistency with the principal dwelling [Section 18.200.180(C)(10)]. This includes:

Materials/Colors: At least two matching exterior materials from the principal dwelling’s palette or one matching exterior color from the principal dwelling's palette.
Roof: A matching roof slope or pitch consistent with the principal dwelling.
Exceptions: If the planning division determines these design requirements cannot be met, a discretionary design and site review process is required [Section 18.200.180(C)(10)(a)].

Parking Requirements

Parking standards for ADUs in the RS-6 district are as follows:

Parking Type	Requirement
Required Spaces	One off-street space per ADU or per bedroom, whichever is less
Location	May be uncovered, tandem, or in the front yard setback (if within existing/proposed driveway)
Exceptions	Parking is not required if the ADU is within 0.5 miles of public transit or is an "exempt accessory dwelling unit" [Section 18.200.180(C)(11)(b)]

Parking spaces for an ADU are in addition to those required for the single-family principal dwelling [Section 18.200.180(C)(11)]. Widening an existing driveway to accommodate this parking is permitted, provided the expansion does not cover more than 50 percent of the required front setback or yard area [Section 18.200.180(C)(11)(a)].

Junior Accessory Dwelling Units (JADUs)

JADUs are permitted within the walls of an existing or proposed single-family principal dwelling or attached garage [Section 18.200.180(E)].

Size: Maximum of 500 square feet [Section 18.200.180(B)].
Facilities: Must include an efficiency kitchen; sanitation facilities may be private or shared with the principal dwelling [Section 18.200.180(E)(2)].
Covenant: Owners must record a covenant prohibiting the sale of the JADU separate from the principal dwelling and restricting the unit to owner-occupied properties [Section 18.200.180(E)(4)].

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