STATEWIDE UPDATE: New California ADU Bills SB13, AB68, AB881, AB670 have passed. These laws will create more options for building an ADU in Concord in 2020. To prepare for the upcoming changes use our ADU Services to learn how these laws will effect your property!
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Last Updated 08/11/19


The city government of Concord has updated its local zoning codes to comply with the State ADU mandate.
The California Building Code (CBC) 2016 is adopted with the following amendment(s): 16-7 and 17-3 CALGreen
Relevant state bill updates for SB13, AB68, AB881, AB670 are shown in green below.


City Hint: The city permitted a total of 50 ADU project(s) in the past year of 2018, which makes it above average for ADU production compared to other cities statewide.


Number of ADUs allowed:

One ADU permitted per primary dwelling.

AB68 & AB881 Update: Properties which convert existing space to create ADUs may be eligible for one ADU -AND- one JADU.

Types of ADUs allowed:

Detached, Attached and Junior accessory dwelling units are allowed.

Lot size:

Are allowed without minimum lot size, provided it complies with the maximum density of the underlying zone.

AB68 & AB881 Update: Properties will not be subject to minimum lot standards by ordinance or of the applicable zoning district.

ADU size:

Between 150 square feet and 640 square feet for lots less than 12,000 square feet in net area and up. To 1,200 square feet for lots greater than 12,000 square feet in net area. An accessory dwelling unit constructed through an addition to an existing residence shall not exceed 50 percent of the existing floor area of the principal residence. The floor area RATIO for an attached accessory dwelling unit shall not exceed 50% of the principal dwelling unit.

AB68 & AB881 Update: Properties will be allowed up to 850 square feet for a one bedroom or up to 1,000 square feet for a two bedroom ADU.


Accessory dwelling units established through a new addition to an existing dwelling or newly constructed detached building must typically be setback a minimum of 15-20 feet from the rear property line (depending on zoning district) and at least five feet from the side property line in most cases. Required setbacks can be found in the Residential Districts section of the Development Code. For accessory dwelling units proposed as a conversion of existing living space within a principal dwelling or through the conversion of an existing accessory structure, no additional setback is required so long as the distance is sufficient for fire safety. For second-story accessory dwelling units proposed above a garage or above a principal dwelling a minimum of feet from the side and rear property line is required.

AB68 & AB881 Update: The maximum required setback for a detached new construction ADU shall be no more than 4 feet from the rear or side property lines.


A one bedroom unit shall provide one (1) covered or uncovered space and a two bedroom unit shall provide two (2) spaces in addition to the required off-street parking for the principal residential dwelling. The parking space may be an uncovered space or tandem space and may be located in the front yard setback if contained within the space of an existing paved driveway. When a garage, carport, or covered parking structure for the principal dwelling unit is demolished in conjunction with the construction of an accessory dwelling unit, the replacement spaces may be located in any configuration on the same lot as the accessory dwelling unit, including, but not limited to, as covered spaces, uncovered spaces or tandem spaces contained within the space of an existing paved driveway. Additional parking may not be required in certain situations.

AB68 & AB881 Update: Properties which convert an existing garage will not be subject to replacement parking requirements.

Fire Safety:

Per State Requirements.

Shape, materials and style:

Accessory dwelling units must be subordinate to the primary structure by size, location, and appearance, and must comply with the following criteria:
1. Roofing and siding materials shall be the same style, color, and materials as the roofing and siding materials predominant on the primary structure.
2. Accessory dwelling units shall be painted the same color, or be complementary to, the color scheme of the primary structure.
3. Architectural detailing, including but not limited to fascia, window trim, and door trim, shall replicate and be complementary to the trim detailing of the primary structure.


ADU height shall be in accordance with the underlying zoning code.

Design review:

A new accessory dwelling units require Planning Ministerial Approval and a Building Division Permit. A checklist for submittal requirements for the Planning Minister Approval is attached for reference.

Number of Bedrooms:

A maximum of one bedroom for units measuring between 150 square feet and 640 square feet and a maximum of two bedrooms for units between 640 and 1,200 square feet


Unit is not intended for sale separate from the primary residence and may be rented. (State requirements)

SB13 Update: Owner-occupancy requirements for ADUs will be voided statewide for 5 years.

Utility connections:

Local health officer approval where a private sewage disposal system is being used, if required. (State requirements)

Permit Fees

SB13 Update: Local impact fees for ADUs will be reduced substantially statewide.


An accessory dwelling unit is an independent dwelling located on the same lot as an existing single-family residence. The unit may be created by converting existing floor space, converting an existing accessory structure, attaching the unit to the main residence, or building a separate structure. The purpose of allowing Accessory Dwelling Units is to provide the opportunity for the development of small rental housing units designed to meet the special needs of families and individuals.

Allowed Zones:

Accessory dwelling units are allowed in all single-family residential (RR, RS) districts, low-density residential districts (RL), and in other districts where a legal single family residences exists. An accessory dwelling unit shall meet all provisions of the district in which they are located (Zoning information can be found at:

AB68 & AB881 Update: ADUs will be allowed statewide in all single-family or multi-family zoning districts.

Residential Building Code:

The California Building Code (CBC) 2016 is adopted with the following amendment(s): 16-7 and 17-3 CALGreen

Concord City Planning Offices

Planning & Zoning

1950 Parkside Drive Concord, CA 94519 Concord, CA 94519

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* based on local average price per sqft


* estimated by location


* 30 years / 5% interest rate / 20% down payment


Appreciation Estimate = (Base Value: $) / (Home's Living Space: sqft) * (ADU's Living Space: sqft)

Rental Estimate = (Rent Per Sqft: $3.08) * (ADU's Living Space: sqft)

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