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Unlock your property’s full potential with ARC Engineers — your trusted partner in designing and building ADUs and Jr. ADUs in San Diego.
1) An Accessory Dwelling Unit is an attached or detached residential dwelling unit that is: 1,200 square feet in size or less.
2) Provides complete independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking, and sanitation.
3) Is located on a lot with a proposed or existing single dwelling unit or multiple dwelling units.
ADUs are very common to create additional income opportunities or simply provide additional space for relatives in need of a home in this home shortage crisis.
Our team of ADU experts are able to conduct a feasibility study on the existing property parameters such as property lines,
setbacks, floor area ratios, and design a custom ADU to fit your property and adapt your vision for a custom design.
Whether it is a garage conversion, to detached building configuration, or addition to existing property, we can design an ADU that will meet your goals and provide the most habitable space and functionality to help meet your goals.
ADUs are permitted in Zones that permit Residential Uses. The location must be verified by the design consultant to ensure it will be allowed by zoning.
Number of Allowed ADUs:
1. Single Dwelling Unit Zones
A Single Dwelling Unit Zone is a zone that allows a maximum of one dwelling unit on a single lot.
a) Permitted within Single Dwelling Unit zones:
- 1 Single Primary Dwelling Unit
- 1 Accessory Dwelling Unit
- 1 Junior Accessory Dwelling Unit
1. The minimum gross floor area for an attached or detached ADU is 150 square feet.
2. The maximum gross floor area for an attached or detached ADU is 1,200 square feet.
3. The gross floor area of an ADU is included in the total gross floor area of a premises.
4. An ADU may exceed the total gross floor area of a premises, however the ADU shall be limited to a maximum of 800 square feet of gross floor area.
5. Minimum room dimension requirements contained within the California Building Standards Code are applicable.
Conversions or Interior Alterations of Existing Structures.
Where an existing structure is converted to an ADU, the ADU may continue to observe the setbacks of the existing structure.
Demolition and Reconstruction of Existing Structures
Where an existing structure is demolished and reconstructed as an ADU, the ADU may continue to observe the setbacks of the original structure. The reconstruction must be at the same location, and to the same dimensions as the original structure.
Addition of Floor Area to Existing Structures
Where an addition to an existing structure is proposed for an ADU, the ADU must observe the Front Yard and Street-Side Yard Setbacks of the Zone. The ADU may encroach into the Side Yard and Rear Yard Setbacks of the Zone, including up to the Property Line, if the structure height is 16 feet or less.
If the side or rear property line abuts another premises that is residentially zoned or developed with exclusively residential uses, an ADU with a structure height that exceeds 16 feet, or is multistory, shall observe a 4-foot Interior-Side Yard and Rear Yard setbacks.
Construction of New Detached Structures
Where a new structure is proposed as an ADU, the ADU must observe the Front and Street-Side Setbacks of the Zone. The ADU may encroach into the Side and Rear Setbacks of the Zone, including up to the Property Line.
ADUs must comply with all requirements in the California Building Standards Code, including requirements for fire separation distance, opening protection, allowable height, and allowable area.
No parking spaces are required for ADUs.
The conversion or demolition of a garage, carport, or covered parking structure does not require the replacement of parking spaces. If the construction of an ADU or JADU involves the conversion or demolition of a covered parking structure and the existing driveway curb is no longer compliant with City standards, the associated driveway shall be closed to the satisfaction of the City Engineer.
Where off-street parking spaces are provided, parking spaces may be within setback areas, and in any configuration including tandem configurations and mechanical lifts.
The property owner is not required to live on-site.
An ADU may not be leased for a term of less than 31 consecutive days. An ADU may not be usedfor Transient Lodging.
Detached ADUs only require sprinkler protection when the primary dwelling unit is sprinkler protected.
For duplexes and multiple dwelling unit (MDU) building sites adding an ADU, the primary dwelling unit is considered the entire duplex or the MDU building.
Attached ADUs always require sprinkler protection when the primary dwelling unit is sprinkler protected.
The following attached ADU designs do not require sprinkler protection when the primary dwelling unit is not sprinkler protected:
ADU attached to a single family home.
ADU attached to a duplex (two-family dwelling) created by converting existing, permitted space. Although this project is a change of occupancy from a Group R-3 to a Group R-2, California Existing Building Code (CEBC), Section 506.1 allows for a change of occupancy without compliance with all of the requirements of the code for the new occupancy when the new use is less hazardous.
ADU attached to an MDU created by converting the existing permitted space. As there is no change in occupancy and no increase in fire area, sprinklers are not required.
Newly constructed ADUs are subject to the California Energy Code requirement to provide solar panels if the unit(s) is a newly constructed, non-manufactured, detached
ADU. Per the California Energy Commission (CEC), the panels can be installed on the ADU or on the primary dwelling unit.
ADUs that are constructed within existing space, or as an addition to existing homes, including detached additions where an existing detached building is converted from non-residential to residential space, are not subject to the California Energy Code requirement to provide solar panels.
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