Accessory Dwelling Unit Requirements and Regulations in Concord
Accessory Dwelling Units (ADUs) in Concord are permitted on lots with existing or proposed single-family or multifamily principal dwellings, provided they meet specific size, height, and setback standards. Junior Accessory Dwelling Units (JADUs) are also allowed within existing single-family principal dwellings under specific occupancy and covenant requirements.
Applicability and Permitted Districts
Accessory Dwelling Units are allowed in the following zoning districts that permit single-family or multifamily principal dwelling residential uses [Section 18.200.180(C)(7)]:
| Zoning District |
|---|
| R (Residential) |
| NTS (North Todos Santos) |
| CO (Community Office) |
| CMX (Commercial Mixed-Use) |
| NC (Neighborhood Commercial) |
| DP (Downtown Pedestrian) |
| DMX (Downtown Mixed-Use) |
Development Standards for Accessory Dwelling Units
Size Requirements
The living area of an Accessory Dwelling Unit must be at least 150 square feet and cannot exceed 50 percent of the principal dwelling’s floor area, subject to the following maximums [Section 18.200.180(C)(8)]:
- Lots less than 12,000 square feet: Maximum 1,000 square feet (excluding up to 230 square feet for attached garages or carports).
- Lots 12,000 square feet or greater: Maximum 1,200 square feet (excluding up to 460 square feet for attached garages or carports).
Note: The size limitation is waived if it restricts the Accessory Dwelling Unit to less than 800 square feet.
Height Limits for Detached Accessory Dwelling Units
Detached Accessory Dwelling Units must comply with the following height limitations [Section 18.200.180(C)(17)(b)]:
| Location/Condition | Maximum Height |
|---|---|
| Standard lot with single-family or multifamily principal dwelling | 16 feet |
| Lot within 0.5 mile of a major transit stop or high-quality transit corridor | 18 feet |
| Lot with multifamily, multistory principal dwelling | 18 feet |
| Conversion of existing detached accessory structure | No limit |
Setbacks
Accessory Dwelling Units must provide interior side and rear setbacks of at least four feet. Front and corner-side setbacks for Accessory Dwelling Units must comply with the requirements for the principal dwelling [Section 18.200.180(C)(16)].
Parking Requirements
Parking required for an Accessory Dwelling Unit is in addition to the requirements for the principal dwelling [Section 18.200.180(C)(11)]. One off-street parking space is required per Accessory Dwelling Unit or per bedroom, whichever is less. However, parking is not required in the following instances [Section 18.200.180(C)(11)(b)]:
- The unit is within one-half mile walking distance of public transit.
- The unit is located within a designated architecturally and historically significant historic district.
- The unit is part of the proposed or existing principal dwelling or a conversion of an accessory structure.
- On-street parking permits are required but not offered to the occupant.
- A car share vehicle site is located within one block of the unit.
Junior Accessory Dwelling Units (JADUs)
Junior Accessory Dwelling Units are allowed on lots zoned for single-family principal dwellings and must be contained entirely within the walls of an existing or proposed single-family principal dwelling or attached garage [Section 18.200.180(E)(1), (D)(2)(a)].
- Maximum Size: 500 square feet [Section 18.200.180(B)].
- Parking: No additional parking is required [Section 18.200.180(E)(3)].
- Covenant: Owners must record a covenant prohibiting the sale of the JADU separate from the principal dwelling, prohibiting rentals of less than 30 days, and requiring owner-occupancy of either the principal dwelling or the JADU (unless the owner is a government agency, land trust, or housing organization) [Section 18.200.180(E)(4)].
Sections Cited
- Section 18.200.180 (Accessory dwelling units)
- Section 18.200.100 (Home-based businesses)
- Section 18.200.110 (Live/work or work/live units)
- Section 18.160.040 (Parking requirements)
- Section 18.160.100 (Additional standards for driveway access easements, curb cuts, parking lots, and structures)
- Section 18.415 (Design and Site Review)