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San Diego ADUs

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El Cajon

749 sf
1 Bed

San Diego ADU Guidelines Last Updated 09/16/21

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


City Hint: The City of San Diego permitted a total of 492 ADU projects in the past year of 2020.

Number of ADUs allowed:

According to state law, all single-family homes are allowed at least one Accessory Dwelling Unit (ADU). Additionally, single-family properties which are owner-occupied may create one Accessory Dwelling Unit (ADU) and one Junior Accessory Dwelling Unit (JADU). Also, multi-family properties may now add one ADU per every four existing residential units, so long as they were legally established. Multi-family properties are also allowed up to two detached ADUs.

ADU Bonus for Affordable ADUs. One additional ADU shall be permitted for every ADU on the premises that is set aside as affordable to very low income, low income, and moderate income households for a period of not less than 15 years guaranteed through a written agreement, and a deed of trust securing the agreement, entered into by the applicant and the President and Chief Executive Officer of the San Diego Housing Commission.
(i) There is no limit on the number of bonus ADUs within a transit priority area.
(ii) One bonus ADU is permitted outside a transit priority area.

(iii) For ADUs to be counted as affordable and meet the requirements of this Section 141.0302(b)(2)(G), the qualifying criteria in Table 141-03A shall be met

Types of ADUs allowed:

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

Lot size:

Accessory Dwelling Unit (ADU) projects on single family or multi-family residential lots will not be subject to the minimum lot size of the underlying local zoning code or by special ordinance. ~ AB-68

ADU size:

The minimum gross floor area of an ADU shall not be less than 150 square feet. The maximum gross floor area of an ADU shall not exceed 1,200 square feet. An ADU constructed within an existing dwelling unit or accessory structure may construct an additional 150 square feet for ingress and egress only.


The following setback allowances are applicable:

(i) Conversion of existing structure to an ADU or JADU. No setback is required for an existing dwelling unit or accessory structure that is converted to an ADU or JADU, or to a portion of an ADU or JADU. An ADU or JADU that is constructed in the same location and to the same dimensions as an existing structure may continue to observe the same setbacks as the structure it replaced.

(ii) New ADU and JADU structures. New ADU and JADU structures must comply with the front yard and street side yard setbacks of the zone. New ADU and JADU structures may encroach into the required interior side yard and rear yard setbacks up to the property line to accommodate construction of the ADU or JADU.


(A) No on-street parking spaces or off-street parking spaces are required for ADUs and JADUs. If the applicant chooses to provide off-street parking spaces for ADUs and/or JADUs located on the premises, those spaces shall comply with the following:

(i) Off-street parking spaces may be located in any configuration, may be within the setback areas, and may include tandem spaces or mechanical lifts.
(ii) Off-street parking spaces shall be located within hardscape areas and shall comply with the minimum standards and guidelines to provide safe and efficient means of vehicular access to the lot.

(B) When a garage, carport, or covered parking structure is demolished in conjunction with the construction of an ADU or JADU, or converted to an ADU or JADU, replacement of those off-street parking spaces is not required.

Fire Safety:

The ADU shall only be required to have fire sprinklers if they are required in the primary dwelling.

Shape, materials and style:

The ADU shall resemble the architectural design characteristics of the primary dwelling, including but not limited to, paint color, windows, roof pitch and massing.


For ADUs located above a garage or other accessory building: The maximum structure height for flat-roofed structures is 21 feet; and The maximum structure height for sloped-roofed structures with a roof pitch of at least 3:12 (3 vertical feet to 12 horizontal feet). For detached ADUs, not above a garage or other accessory building: Max is 15 feet without a chimney or flue, or 17 feet with a chimney or flue.

Design review:

You must apply for a building permit. Please refer to the Project Submittal Manual, Section 2A, for all general requirements related to the submittal process.

A. Typical Submittal Documents Minimum submittal requirements for each companion or junior unit proposal includes the following
(per Project Submittal Manual, Section 2A):

1. Plans / Calculations:
(a.) Site Plan and Vicinity Map (See Information Bulletin 122).
(b.) Floor Plans and Roof Plans.
(c.) Elevations and Sections (as applicable).
(d.) Structural plans and details.
(e.) Structural calculations and/or truss calculations (as applicable).
(f.) Title 24 Energy calculations.

2. Forms.
(a.) General Application, DS-3032.
(b.) Water Meter Data card, DS-16.
(c.) Storm Water Applicability Checklist, DS-560 (not required for a Junior Unit).

*** According to state law, ADUs must be provided a ministerial review process. This requires that a proposed ADU which complies with all state and local standards should be approved within no greater than 120 days from the date of submission, or else that ADU should be approved automatically.

Number of Bedrooms:

Not specified by State Standards.


Owner-occupancy will not be required for new Accessory Dwelling Unit (ADU)s (conversion and new construction) built between 2020 and 2025. ~ SB13

Utility connections:

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

Historic Requirements:

If the property is located in a potentially historic district the project will be required to be reviewed historic compliance.

Coastal Areas

Within the Coastal Overlay Zone, companion units are subject to the provisions of Chapter 12, Article 6, Division 7. If inside the costal overlay, the project will be required to be reviewed for compliance prior to issuance of a building permit.


Companion unit entrances shall not be located on the building street wall or within the front 50 percent of the structure. The companion unit must have a separate entryway from the main dwelling.

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. ***

1. Permitted as a limited use in residential zones.
2. Permitted as a limited use in multiple dwelling unit residential zones where the maximum allowable density is two units based on the existing lot area.
3. Within the Coastal Overlay Zone, a Coastal Development Permit is required for a companion unit.

Floor Area Ratio

The gross floor area of the companion unit shall be included in the floor area ratio calculation for the premises.


One 24-inch box tree shall be planted in the required front yard of the premises or in the abutting parkway. Existing trees that are at least 15 feet high and 15 feet in width may be used to satisfy this requirement.

Residential Building Code:

The California Building Code (CBC) 2019 is adopted.

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