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(925) 239-4165 ext: 271
Schedule ADU Consultation (925) 239-4165 ext: 271

Concord ADUs

Everything about building Accessory Dwelling Units in Concord, CA

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The city government of Concord has updated its local zoning codes to comply with the State ADU mandate.
The California Building Code (CBC) 2019 is adopted.

Last Updated 10/13/20


City Hint: The city permitted a total of 33 ADU projects in the past year of 2019, which makes it above average for ADU production compared to other cities statewide.

Number of ADUs allowed:

1. Lots with an existing or proposed principal residence:
i. One ADU within the space of a proposed or existing principal residence;
ii. One ADU located within the footprint of an existing accessory structure legally constructed with a building permit; OR
iii. One detached, new construction ADU.

Lots with an existing multi-family dwelling:
i. At least one ADU on a lot containing an existing multi-family dwelling, constructed within areas that are not used as livable space, including, but not limited to, storage rooms, boiler rooms, passageways, attics, basements, carports or garages, not to exceed 25 percent of the number of existing multi-family dwelling units; and
ii. Two detached ADUs per lot.

Types of ADUs allowed:

Detached ADU, Attached ADU, Junior ADU are permitted. ADUs may be new construction or converted from existing space. JADUs must be converted from existing space.

Lot size:

Residential properties will not be subject to any minimum lot size for Accessory Dwelling Unit (ADU)s by ordinance or of the underlying zoning district. ~ AB-68

ADU size:

Studio or one bedroom: 850 square feet maximum
Two or more bedrooms: 1,000 square feet maximum
Additionally, attached ADUs (including conversion of existing habitable space within the principal residence) shall not exceed fifty percent (50%) of the gross floor area of the existing principal residence. The 50% limitation does not apply if the ADU is 800 square feet or less.


Front yard: Per the applicable zoning district
Side and rear yards: Four feet
Corner side yard: Four feet but in no case shall the ADU be closer to the property line than the proposed/existing principal dwelling
Between structures: Per the Fire and Building Code Regulations (typ. 5 feet)
The minimum setbacks shall be waived for an ADU constructed entirely within the footprint of a legally constructed principal residence or accessory building, and for up to 150 square feet outside of the footprint of said principal residence or accessory building if the additional area is limited to accommodating ingress and egress; however, the ADU must still comply with all applicable Building Code Regulations.


One off-street parking space per ADU is required. These spaces may be provided by a garage or carport, as tandem parking on a driveway. Only uncovered spaces may be located in setback areas. The required parking can be waived if findings are made that parking is not feasible. No new parking spaces are required if a garage, carport or covered parking structure, legally constructed with a building permit, is demolished to accommodate new construction of an ADU or if said structures are converted to an ADU.
In addition, no new parking is required for ADUs when:
1. Located within ½ mile walking distance of public transit (e.g., a bus stop or BART station); or
2. The ADU is within the proposed principal residence or within an existing principal residence or within an existing accessory structure legally constructed with building permits; or
3. When on-street parking permits are required but not offered to the occupant of the ADU; or
4. When there is a car share vehicle (e.g., Zipcar) located within one block of the ADU.

Fire Safety:

Fire Sprinklers are not required unless they are required in the primary home.

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.


The maximum height for an ADU is sixteen feet. The maximum height (16 feet) can be exceeded to accommodate an ADU constructed entirely within the exterior physical dimensions of (i) an existing principal residence, multifamily dwelling, or accessory building legally constructed with a building permit or
(ii) a proposed principal residence. In no case shall the ADU have a building height greater than the existing building or sixteen feet, whichever is greater.

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:

No Maximum on number of bedrooms by the state.


The property is not required to occupy the ADU or principal residence.

Utility connections:

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


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:

*** Beginning in 2020, according to state law, all residential zoning districts, including single-family and multi-family, are allowed to build Accessory Dwelling Units. ***

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:

Residential Building Code:

The California Building Code (CBC) 2019 is adopted.

Concord City Planning Offices

Planning & Zoning

1950 Parkside Drive Concord, CA 94519 Concord, CA 94519

Read Concord Housing Market Update

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ADU Design Library

Browse hundreds of models to find the right fit for your property.

ADU Model 560 sqft

W 40 ft L 14 ft

ADU Model 400 sqft

W 20 ft L 20 ft

ADU Model 450 sqft

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Customer Reviews

"Housable has been a great resource regarding my ADU project. I purchased both the Property and Design Reports. In both cases, they delivered as promised and on time."

Ed in Corona, CA

"My experience with Housable was exceptional. The team was extremely helpful and responsive. I am very satisfied and happy to have used these services. As a home owner I do not know the construction lingo or process but the Housable team very kind and helpful and patient with me. My expectations were exceeded. Thank you for everything."

Monica H. in Oakland, CA

"The property report was great! Made me feel like my project is feasible."

Alexandria in Santa Ana, CA

Complete 5-Step Process

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What our customers say:

Customer Reviews

"My permits were APPROVED, thank you for all your hard work. I am in the process of meeting with contractors. "

Mary S. in San Jose, CA

"I just wanted to let you know that the permit process has been completed and we are currently in the construction phase. The work you guys did was great and I will definitely be using this service again in the future. I will keep you guys updated on anything important. Thanks!"

Patrick L. in Orange County, CA

Detached ADU - Completed in 2020
1,003 sq. ft., 3 bed, 2 bath

Estimate Your ADU Potential
Costs / ROI



* upon completion of ADU


* based on local average price per sqft


* estimated by location


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


Size: 500 sqft


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)

Check your property's zoning, browse designs & get contractor estimates for your ADU project:

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