What you can build in the City of San Diego
San Diego ADU Regulations & Zoning
KEY RULES AT A GLANCE
Size and Separation
Maximum size 1200 square feet
Side/rear setbacks 0 feet (4 feet preferred and for two-story)
Two story Yes
Building separation 6 feet
Soils Report No
Building Verification Survey No
Coastal permit (in some areas) Yes
Stormwater Mitigation No
Number of ADUs Allowed in the City of San Diego
How many ADUs can you build in San Diego?
On San Diego single-family residential lots, you may build one ADU (either attached or detached) and one Junior ADU (JADUs have an owner occupancy requirement). You can also build one more income-restricted affordable ADU, and another bonus ADU (at market rates), so long as everything conforms to the underlying zoning requirements on lot coverage.
So you could have a total of 4 ADUs (one ADU, one JADU, one affordable ADU, one bonus market rate ADU). In transit priority areas, you may be able to build even more – learn more about the City of San Diego’s affordable ADU bonus program.
How many ADUs does San Diego allow for multifamily properties?
You can build two detached ADUs on multifamily lots in San Diego, plus a potential bonus of additional units if restricted to low or moderate income housing, just as described above for single family.
On a premises located in a Single Dwelling Unit Zone with an existing multiple dwelling unit, or a premises located in a Multiple Dwelling Unit Zone with an existing or proposed dwelling unit, two ADUs that are attached to and/or detached from an existing or proposed structure are permitted.
In other words, you can build two detached ADUs in a multifamily zone (even if there is just one single family residence) OR in a single family zone where an existing multifamily structure (like a duplex) exists.
Additionally, existing non-livable space may be converted to ADUs (e.g. storage areas and garages). In the City of San Diego, there is no limit on the number of ADUs that can be created in this manner. These conversions are in addition to the allowed number of detached ADUs.
ADU San Diego – Size & Building Constraints
What size detached ADU can you build in San Diego?
San Diego allows for a detached ADU up to 1200 sqft. ADUs up to 800 square feet are exempt from lot coverage requirements. (Meaning: You can build an ADU of this size even if you’re maxed out on lot coverages).
How big can an attached ADU be in San Diego?
In the City of San Diego, the square footage of any attached ADU may be up to 1,200 sqft. Note that the City of San Diego does not tie a size limit to the size of the primary home like many other local jurisdictions do.
What is the height requirement for an ADU in San Diego?
The height of a detached ADU can be at least 16′ and still have reduced setbacks of zero on the side and back yard. You can actually build higher than 16′ in San Diego, subject to the height maximums for the underlying zone and subject to 4′ side and rear setbacks (specifically “if the side or rear property line abuts another premise that is residentially zoned or developed with exclusively residential uses.”)
Max building height in San Diego for most residential properties is 24′ to 30′, with a few going up to 35′. (§131.0444 Angled Building Envelope Plane / Maximum Structure Height in Residential Zones).
Can you build a 2-story ADU in San Diego?
Two-story ADUs are allowed in San Diego, per the above info on height requirements. However, for ADUs located above a garage or other accessory building, the maximum height for flat-roofed structures is 21′ and the maximum structure height for sloped-roofed structures is 30′ (§141.0307 (f) Guest Quarters or Habitable Accessory Buildings).
Also note that the City of San Diego requires all stairs to be a minimum of 5′ from the property line (or more, typically stairs follow the underlying setbacks) and also requires that two-story units that are on a property abutting another residential property must adhere to 4′ setbacks.
Read more about two story ADUs and height limits.
Can you stack detached ADUs on top of each other?
Yes, you can stack ADUs on top of each other in San Diego. (Per City of San Diego Planning department consult Oct 2021)
Can you attach two ADUs to each other in San Diego?
Can you build an ADU with an attached JADU?
The City of San Diego does allow you to have a junior accessory dwelling unit (JADU) attached to the ADU. The structure can be up to 1,850 SF, allowing for 1,200 SF ADU, 500 SF JADU, and 150 SF ingress and egress. The 150 SF cannot count as livable space. Also, the two structures could not have a breezeway between them, as the JADU must be entirely within the ADU.” Note that this type of project could be completed under one project number and plan, e.g. at the same time during permitting.
This information was confirmed on July 31, 2023 with an associate planner at the City of San Diego through a virtual DSD appointment.
Does San Diego allow roof decks on ADUs?
Generally roof decks would be permitted, but must meet the height restrictions for the zone. Roof decks cannot encroach into the required setbacks. Generally railings & access staircases above 42″ are included in height calculations.
What are the requirements of the exterior of the ADU?
San Diego makes no mention of specific requirements for the exterior of the ADU. However, general guidance is that the exterior roofing, trim, walls, windows and the color palette of the ADU shall incorporate the same features as the primary dwelling unit.
ADU Setbacks in the City of San Diego
What is the setback requirement for an ADU in San Diego?
ADUs must comply with the front yard setbacks, with a 0′ side yard and rear setback for ADUs of up to 16′ in height. In other words, you can technically build all the way up to the property line. If you build two story, you must keep 4′ side & rear setbacks.
Also, note that street side setbacks in City of San Diego are enforced for ADUs, meaning you will need to adhere to the underlying street side setback and not 4′ – this was verified by an associate planner in September 2023.
Note any open staircases must follow underlying setbacks, which means staircases must typically be at least five feet from the property line, if not more.
Lastly, an important note is that if you are closer than 5′ to the property line, building code requires that the structure must be fire-rated, which will increase your build cost by several thousand dollars. Also, we require a clearance of at least 4′ from existing structures on property lines to facilitate construction work (it is possible to build closer than that, but it’s more expensive since it requires more manual labor). So for these reasons, we recommend allowing more than a 5′ setback when possible. Leaving this buffer will also reduce your risk of being required to provide a survey to prove the location of your ADU is allowed.
What is the minimum distance the ADU must be from existing structures?
Per San Diego Municipal Code 131.0450, detached dwellings shall maintain 6 ft min. distance between dwellings on the same premises.
Also note that fire codes will require special materials – and possibly fire rating on the existing primary dwelling – when closer than 10′ eave to eave between structures.
Additional Requirements in the City of San Diego
Does San Diego require in-person submission of plans for an ADU?
No, San Diego allows digital submission of applications for an ADU.
Does San Diego require a soils report for an ADU?
No, San Diego does not mandate soils reports for ADUs.
Does San Diego require coastal development permits?
Yes, accessory dwelling units developed within the coastal zone are subject to a coastal development permit (CDP). This process recently changed. On September 7, 2022, the California Coastal Commission certified (W15) the City of San Diego’s changes to their Local Coastal Program (LCP). Plans are now approved by city staff and cannot be appealed to the Planning Commission or City Council so long as they comply with existing zoning and building regulations.
There will still be noticing requirements, and this will all take more time and money. We do not know exactly what the process will look like yet in San Diego because it is so new, but it will essentially be a longer and more expensive standard ADU submission with more paperwork requirements to make sure compliance with all coastal zone rules that are not covered or preempted by the State ADU laws.
Read more about ADUs in the coastal zone.
What landscaping requirements apply to ADUs in City of San Diego?
If construction of an ADU or JADU that would bring the number of ADUs or JADUs on the premises to a total of two or more is proposed, two trees shall be provided on the premises for every 5,000 square feet of lot area, with a minimum of one tree per premises. If planting of a new tree is required to comply with this section, the tree shall be selected in accordance with the Landscape Standards of the Land Development Manual and the City’s Street Tree Selection Guide.
What is the plan check process with the City of San Diego? How long does it take?
Once plans are submitted for pre-plan check review, typically within 3-5 days the City of San Diego will issue the invoice for a “Plan Check Fee, which covers the entire cost to review plans by the city. The city will not formally start reviewing the plans until this fee is paid.
Plan check fees will be around $1,500-$2,500. Thereafter, the city technically has 60-days to do their first review of the plans, which they are fully taking at this time. They will then provide corrections to the plans that will be addressed by the designer and resubmitted. Plan check reviews after this initial phase take about 30-days. Overall, the plan review time can take around 90-100 days.
Once your plans are deemed “approved,” the project is placed in an “issuance” queue that takes another 15-20 days for the city to process. During this time you will be provided with additional fees, such as Building Permit Fee (similar in cost to plan check fees), school impact fees (depending on your school district may vary), and various small sewer/water meter review fees. Read more about ADU permit fees.
Parking for San Diego ADU
What is the parking requirement for an ADU in San Diego?
A parking space is not required for an ADU in any of the following instances:
- Within a one-half mile walking distance from public transit, which includes bus stops.
- Within an established historic district.
- Converted from the existing space of a primary residence or accessory structure, or are attached to an existing or proposed primary residence.
Where can a parking space be located?
If a parking space is required, it may be located within the setbacks and in an existing driveway as tandem parking. Parking spaces don’t need to be replaced when a garage, carport, or covered parking structure is demolished in conjunction with the construction of an ADU or converted to an ADU.
Additional City of San Diego ADU Regulation Resources
Watch our ADU 101 Webinar
Thinking about building an ADU in San Diego and want to learn more about the whole process? We’d love to help make sure you know exactly how it all works in our on-demand webinar led by SnapADU co-founder, Whitney Hill.