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Right-Sizing the Bonus ADU Program

Click HERE for NFABSD's objections to the Planning Department bypassing public review and input of their proposed Bonus ADU changes.

Click HERE for NFABSD's specific responses to the Planning Department's proposed changes.

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Revising the Bonus ADU Program​

It should be noted first that almost 5,000 ADUs have been built in San Diego since 2021 without the Bonus ADU program, and revisions to the Bonus ADU regulations will allow those small-scale projects to continue. Many of Neighbors For A Better San Diego's supporters have ADUs on their own properties.

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Further, half of Bonus ADUs are produced in multi-family zones, which will not be substantially affected by proposed changes from the Planning Department or the public.

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The main issue is the allowance of unlimited Bonus ADUs on single-family lots in Sustainable Development Areas. The disproportionate impact these out-of-scale developments have on neighborhoods doesn't justify their limited returns on housing.

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A summary of the drawbacks of San Diego's regulations can be found HERE.​​

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Revision of the Bonus ADU program should be based on several core principles:

  • Eliminate the distinction between ADU regulations inside and outside the Sustainable Development Area. (Harmonize to regulations for outside SDA.) As noted above, the SDA is neither transit-oriented nor equitable and therefore shouldn't be used as a basis for development.

    • Applying the regulations outside the SDA citywide would still allow 3 ADUs (plus the existing house) on any single-family zoned lot in San Diego, which would exceed state requirements and continue to provide deed-restricted units. It would also encourage larger, family-sized units, which are the greatest need in San Diego.

  • Align heights, number of stories, and setbacks with neighboring buildings.

  • Restrict ADU units on properties with open space or steep hillsides located in Very High Fire Hazard Zones.

  • Collect Development Impact Fees, as allowed by state law, to pay for supporting infrastructure.

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The Community Planners Committee (CPC), which represents San Diego's 52 communities, has approved a comprehensive set of recommended changes to the Bonus ADU program, which are consistent with the above principles. NFABSD supports the CPC's recommendations and will provide an update when CPC presents them to the City.

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Why 4?

Limiting the total number of units on a single-family zoned parcel to 4 is consistent with other distinctions between single-family and multi-family developments:

  • The Department of Housing and Urban Development (HUD) defines single-family developments as 1-4 units (24 CFR Section 81.2), with 5 or more units being considered multi-family. (Effectively, "single-family" is a type of low-density multi-family housing, and contrary to an oft-repeated canard, it is not "illegal" to put more housing in single-family neighborhoods).

  • Residential trash pickup for single-family properties is limited to developments of 4 or fewer units. 

  • Limiting to 4 units keeps developments below the Inclusionary Housing threshold (5 units) in the Coastal areas and avoids gamification of those rules.

  • Limiting to 4 units would allow sale of properties under residential loan terms. (5 or more units triggers commercial loan requirements, which would preclude most homeowners from purchasing.)

  • As noted above, limiting to 4 units would still allow at least one affordable or accessible accessory dwelling unit on any parcel, continuing and improving the benefit of the Bonus ADU program in family-oriented neighborhoods.

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Aligning with State Law​

San Diego's ADU regulations cannot be more restrictive than State law. Click HERE to view comparisons between State and San Diego regulations for single-family and multi-family zones.​

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Because state ADU laws are changing every year, there are benefits to sticking to the state's regulations instead of veering away from the intention and design of state regulations with the Bonus ADU program. Those benefits are detailed HERE.

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Solving the wrong problems?

The Terner Center, a pro-developer policy group at UC Berkeley, published a recent study on San Diego's Bonus ADU program. (Source: M. Alameldin and Q. Underriner, “Missing Middle Housing: The Accessory Dwelling Unit Bonus Program,” Terner Center for Housing Innovation, February 15,2023.)

 

A key finding is that developers prioritize Bonus ADUs over traditional multi-family housing development because of advantages in permitting timelines, lowered impact fees, and building code flexibilities. This suggests that either the Bonus ADU program is a way of cutting corners on multi-family developments or multi-family building codes are unduly restrictive and should be relaxed to match the residential building codes applied to the Bonus ADU program. A bill (AB 6) has been introduced by Chris Ward (ASM 78) to study this question and make recommendations for future legislation.

 

State legislation now allows ADUs to be sold as condominiums. While there isn't much statewide experience to understand the benefits and pitfalls of this program, it is worth considering as a possible mechanism for increasing homeownership, which is an important value for NFABSD. As this is considered, however, it should be asked whether this is just a workaround for the state failing to address construction defect litigation, and will these lawsuits now be coming for attached ADU complexes.

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​The Decertification Bogeyman

Even though San Diego is the only city in California that has a Bonus ADU program (other cities prudently align their regulations to State law), the Planning Department has raised the specter of decertification of San Diego's Housing Element if the Bonus ADU program is revised. This is based on the agreement between the City of San Diego and Housing and Community Development (HCD) that San Diego would produce 40 deed-restricted units per year on non-vacant sites. This goal is being met by Bonus ADU projects in multi-family zones alone (49 deed-restricted units/year per the Staff Report), giving San Diego the discretion to revise the Bonus ADU program in RS zones. 

 

Further, the agreement with HCD didn’t include targets for Complete Communities Housing Solutions (CCHS). CCHS provides very low, low and moderate-income units not committed to in the 2021-2029 Housing Element (avg. 123 deed-restricted units/year).


With the Housing Element decertification threat no longer an issue, proponents of not making any changes to the Bonus ADU program will try to invoke the Housing Crisis Act of 2019 (SB 330), which prohibits cities from lowering zoning densities unless compensating density is added somewhere else. However, SB 330 does not apply because opt-in density bonus programs such as Bonus ADUs are not zoning changes. Even if they were, every community plan update supplies more than enough additional zoned housing capacity to offset the Bonus ADU program many times over.

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Data-Driven Policymaking​

In order to inform debate about the impact of different changes to the Bonus ADU program, Neighbors For A Better San Diego has analyzed 282 projects that have used the Bonus ADU program. The data was provided by the San Diego Housing Commission and includes projects from when the program went into effect in 2020 through February 14, 2025.

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Click HERE to view the analysis.

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