Accessory Dwelling Units

NEW! Browse Pre-Approved County Standard ADU Building Plans!




You may want to consider taking advantage of the change in State law which made it easier to add a second house, called an Accessory Dwelling Unit (ADU), to your residential zoned property.



What is an ADU?

An ADU is an additional dwelling unit that could provide affordable housing options for family members, friends, students, the elderly, in-home health care providers, the disabled, and others.



Where is an ADU allowed?
An ADU can be located on residentially zoned property that has an existing single-family residence. For a complete list of ADU requirements, please click here.



Is a building permit required for an ADU?
Yes, you will be required to obtain a Building Permit to ensure that the new house meets all the zoning, building, health & safety codes.



What size ADU is allowed? How big?
An ADU is intended to be secondary in size to the single-family residence. An ADU attached to a primary dwelling may be up to 50% of the size of the single-family residence, up to a maximum of 1,200 square feet. An ADU detached from the single-family residence may be up to 1,200 square feet, regardless of the size of the residence.



Examples for allowable ADU sizes are provided below:

Square Footage of Existing single-family residence (SFD) Maximum Allowed Square Footage for Detached ADU Maximum Allowed Square Footage for Attached ADU (up to 50% of SFD)
1,450 sq. ft. 1,200 sq. ft. 725 sq. ft.
1,800 sq. ft. 1,200 sq. ft. 900 sq. ft.
2,000 sq. ft. 1,200 sq. ft. 1000 sq. ft.
3,000 sq. ft. 1,200 sq. ft. 1,200 sq. ft.
4,500 sq. ft. 1,200 sq. ft. 1,200 sq. ft.

 

After reviewing the information provided on ADU’s, if you still have any questions please contact us:
Phone Number: (858) 495-5382
E-mail: PDS.ADUquestions@sdcounty.ca.gov

Parcel-specific Development Information

General ADU Guidelines and Frequently Asked Questions

Comprehensive List of ADU Requirements

Instructions for Obtaining a Building Permit