How Many ADUs Can I Build on One Lot in San Diego?
Last updated: May 2026
San Diego ADU count rules depend on whether the property is a single-dwelling lot, a multiple-dwelling lot, an existing multifamily building, or a project using the bonus ADU program.
Direct Answer
On many single-dwelling lots, San Diego guidance provides pathways for one attached or detached ADU, one conversion ADU from existing or proposed space, and one JADU. The exact combination depends on the site and project design.
Multifamily properties can be more powerful. Existing non-livable spaces may be converted into ADUs, and detached ADUs may be allowed based on the number of existing or proposed units.
Quick ADU Count Overview
| Property Type | Possible ADU Paths |
|---|---|
| Single-dwelling lot | 1 ADU + 1 conversion ADU + 1 JADU |
| Existing multifamily property | Conversion ADUs from non-livable spaces |
| Multifamily property with detached ADUs | Additional detached ADUs may be allowed |
| Density bonus projects | Additional bonus ADUs possible |
Transit Priority Areas (TPA)
Properties located inside San Diego Transit Priority Areas (TPA) may qualify for additional ADU flexibility, including parking-related exemptions and pathways commonly used with ADU density bonus projects.
TPA-related development is frequently discussed alongside Complete Communities Housing Solutions and the ADU Home Density Bonus Program.
Single-Dwelling Lots
- One single primary dwelling unit.
- One ADU attached to or detached from the dwelling.
- One ADU converted from existing or proposed space or an existing accessory structure.
- One JADU.
Multiple-Dwelling Properties
For existing multiple-dwelling structures, San Diego allows ADUs in existing non-livable spaces based on a percentage of existing units, with at least one ADU when the calculation yields less than one. Detached ADUs may also be allowed, subject to limits tied to the number of existing or proposed units.
Bonus ADUs
San Diego's ADU Home Density Bonus Program can allow additional ADUs when qualifying affordable ADUs are provided. This path is more complex and can add affordability agreements, fees, parking, tree, accessibility, and sprinkler requirements.
Related San Diego research: JADU vs ADU, separate sales, and parking near transit.
Building in LA instead? Check out our Los Angeles ADU Guide.
Source Notes
- City of San Diego Information Bulletin 400
- City of San Diego ADU/JADU program page
- San Diego Municipal Code ADU regulations
Informational only. Not legal, architectural, engineering, investment, or permit approval advice.
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