San Diego County ADU Regulations & Building Guide

As per California State Law, residential properties can have an Accessory Dwelling Unit (ADU) and/or a Junior Accessory Dwelling Unit (JADU). These living spaces provide separate facilities for one or more individuals and can be added to existing or proposed single-family dwellings (SFDs). A JADU is a self-contained living area within the SFD, with a maximum size of 500 square feet, complete with its own exterior and interior access, and a full bathroom. It is advisable to promptly contact the relevant Fire Department to ensure ADU compliance with fire setbacks and determine if fire sprinklers are required.

For lots with existing or proposed SFDs (single family dwelling) in residential or mixed-use zones, one ADU and one JADU may be allowed if the following conditions are met:

• The ADU must be attached to the existing SFD or detached but on the same legal lot.
• The ADU can be rented out but not sold separately from the primary residence.
• The lot must not already have a guest living quarters, accessory living quarters, or accessory apartment. However, it may be possible to convert an existing guest living quarters, accessory living quarters, or accessory apartment into an ADU with a building permit.
• The attached ADU must not exceed 50% of the SFD's floor area, up to a maximum of 1,200 square feet. The detached ADU must not exceed 1,200 square feet, regardless of the size of the existing SFD.
• Applicants must provide mathematical calculations of the "floor area" for both units on the plot plans, based on the exterior dimensions of the outside walls.
• The proposed garage attached to a detached ADU must not exceed the allowable combined square footages specified in Section 6156.g unless authorized by an approved Administrative Permit.
• No other rooms, additions, or uses can be attached to the ADU, except for a garage, unless authorized by an approved Administrative Permit.
• An ADU may potentially be attached to an existing and permitted barn, shed, workshop, or similar structure, as long as it is placed within the existing and permitted accessory structure and does not have internal communication with the remaining portions of the structure.
• Setbacks are not required if an existing and permitted accessory structure, or a portion thereof, is converted into an ADU, except for fire safety.
• When converting an existing detached or attached accessory structure into an ADU, it is important to ensure that any new addition for the ADU complies with the specified setbacks.
• A detached ADU typically has a maximum height of 24 feet, with exceptions for multifamily complexes.

• For an ADU constructed above a permitted detached accessory structure, it is necessary to maintain a setback of at least 4' from the side and rear lot lines. These setbacks specifically apply to the additional space above the accessory structure, allowing the ADU to extend beyond its walls.
• All newly constructed ADUs must adhere to the required front and exterior side yard setbacks, as well as a minimum side and rear setback of 4' (excluding any required fire setbacks).
• Any attached garage, carport, patio, or other accessory structure to an ADU must comply with the regular setback and height regulations outlined in the Zoning Ordinance.
• If an ADU is attached to the primary residence, it should conform to the required main building setbacks.
• It is important to note that an ADU must provide at least one parking space, which can be located within the setbacks or in an existing tandem parking driveway. There is no need to replace parking spaces when a garage, carport, or covered parking structure is demolished or converted into an ADU.
• However, there are specific instances where a parking space is not required for an ADU. Firstly, if the ADU is situated within half a mile of public transit. Secondly, if the ADU is located within an architecturally and historically significant historic district.
• It is prohibited to separately sell or own an ADU, unless the lot is subdivided to create separate lots for each dwelling.
• Additionally, it is important to remember that an ADU cannot be used or rented for less than 30 days.
• In cases where a property has an existing non-conforming single-family residence and is in a zone that does not allow residential use, there may be potential allowance for an ADU and/or JADU.
• However, properties with multiple existing non-conforming single-family residences in a residential zone that only permits single-family residences are not permitted to have an ADU or JADU.

Requirements for Junior Accessory Dwelling Units (JADU):

• One Junior Accessory Dwelling Unit (JADU) and one detached Accessory Dwelling Unit (ADU) may be permitted on lots within a residential or mixed-use zone that already have or propose a Single Family Dwelling (SFD).
• The JADU should not exceed a total area of 500 square feet.
• The JADU must maintain an interior connection to the main living area, while also having a separate exterior entry.
• The JADU should include an efficiency kitchen, consisting of a cooking facility with appliances, and a food preparation counter with storage cabinets proportionate to the size of the unit.
• No additional parking is required for the JADU.
• The JADU cannot be rented for less than a 30-day period.
• While the JADU may be rented out, it cannot be sold separately from the primary residence. The owner must live in one of the two units.
• New proposed ADUs on lots with an existing and permitted SFD may be eligible for the County Fee Waiver Program until January 2024. For more information, please visit the County Fee Waiver Program. Note that JADUs are not eligible for the Fee Waiver Program.

ADU Regulations for Multifamily Complexes

• Multiple ADU's may be permitted within portions of an existing multifamily complex within a residential or mixed-use zone if certain requirements are met:
• Only structures/rooms within the existing multifamily complex that are not used as livable space can potentially be converted into multiple ADU's, up to 25% of the existing multifamily dwelling units.
• Up to two detached ADU's may be permitted per lot that has an existing multifamily complex if certain requirements are met:
• The detached ADU's are limited to a height of 16 feet and 4' rear yard and side setbacks.
• The addition of two detached ADU's is not subject to any nonconforming regulations.
• Multiple ADU's for multifamily complexes do not qualify for the County Fee Waiver Program.
• Regarding the ADU regulations, any structure designed for human habitation that is divided into two or more independent living quarters on a single lot is considered a multifamily complex.

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California law (AB 68, AB 881, SB 9, and subsequent legislation) guarantees your right to build ADUs. Cities cannot:

• Require owner-occupancy for ADUs permitted after 2020
• Require additional parking for ADUs near transit
• Charge impact fees for ADUs under 750 sq ft
• Deny ADUs that meet state minimum standards
• Impose lot coverage limits that prevent a 800 sq ft ADU

If you believe your ADU application is being unfairly denied, California HCD can intervene on your behalf.

This information is for informational purposes only and does not constitute legal advice. Consult a qualified attorney for legal guidance.

California ADU Legislation Overview

California leads the nation in ADU-friendly legislation. The state has passed numerous laws to encourage ADU construction as a solution to the housing crisis.

Key California ADU Laws:

• AB 68 (2020): Reduced local government review time and expanded ADU construction options.
• SB 13 (2020): Limited impact fees and reduced owner-occupancy requirements.
• AB 881 (2020): Prohibited minimum lot size requirements and allowed JADUs in all zones.
• AB 2221 (2022): Further streamlined the ADU approval process.
• SB 897 (2022): Increased height limits for ADUs in certain zones.

California ADU Benefits:

• Property value increase of 20-30% on average
• Rental income potential of $1,500-$3,500+ monthly
• Housing flexibility for family members
• No owner-occupancy requirements (until 2025)