Accessory Dwelling Units in RS-8 Single-Family Residential Districts
In the RS-8 Single-Family Residential district, Concord property owners are permitted to build accessory dwelling units (ADUs) as an accessory use to a single-family principal dwelling, subject to specific size, design, and objective standard requirements. ADUs are treated as a permitted use in the RS-8 district and are not subject to the district's density limit for principal dwellings [Section 18.30.020, Section 18.200.180(C)(3)].
General Requirements for Accessory Dwelling Units in RS-8
Accessory dwelling units in the RS-8 district are intended to provide additional, smaller, and more affordable housing while maintaining the character of the existing neighborhood. Development must comply with the California Building Code [Section 18.200.180(C)(1)].
An accessory dwelling unit may be an attached or detached dwelling unit providing complete independent living facilities. A junior accessory dwelling unit (JADU) may also be permitted if it is contained entirely within the walls of the existing or proposed single-family principal dwelling [Section 18.200.180(B)].
Size and Height Limitations
The following standards apply to the size and height of accessory dwelling units in the RS-8 district:
| Standard | Requirement |
|---|---|
| Minimum Size | 150 square feet |
| Maximum Size (General) | Lesser of 50% of the principal dwelling floor area or 1,000 square feet (for lots < 12,000 sq. ft.) |
| Maximum Size (Detached/Attached) | Must be permitted up to 800 square feet regardless of lot coverage or floor area ratio if other standards cannot be met [Section 18.200.180(C)(8)] |
| Maximum Height (Attached) | 25 feet or the height of the principal dwelling, whichever is lower |
| Maximum Height (Detached) | 16 feet (standard); 18 feet if within 0.5 miles of a major transit stop [Section 18.200.180(C)(17)] |
Parking Requirements
Parking for an accessory dwelling unit is required in addition to the parking required for the principal single-family dwelling. The requirement is one off-street parking space per accessory dwelling unit or per bedroom, whichever is less. However, the requirement is waived in several instances, including if the accessory dwelling unit is within a half-mile walking distance of public transit or if the unit is part of the conversion of an existing accessory structure [Section 18.200.180(C)(11)].
Development and Design Standards
- Setbacks: Attached and detached accessory dwelling units must provide a minimum interior side and rear setback of at least four feet [Section 18.200.180(C)(16)].
- Foundation: A permanent foundation is required for all accessory dwelling units [Section 18.200.180(C)(2)].
- Subdivision: Accessory dwelling units cannot be sold independently of the principal dwelling [Section 18.200.180(C)(4)].
- Rentals: Accessory dwelling units may not be rented for terms of less than 30 days [Section 18.200.180(C)(5)].
- Design: For units that are not pre-approved, exterior colors and materials must be consistent with the principal dwelling, and building detailing (fascia, trim, etc.) must be complementary [Section 18.200.180(C)(10)].
Sections Cited
- Section 18.20.030 (Definitions)
- Section 18.30.020 (Residential Districts – Allowed uses and permit requirements)
- Section 18.200.180 (Accessory dwelling units)