What is the ADU Bonus Program?

The ADU Bonus Program is a City of San Diego ministerial pathway that allows developers to add ADUs to qualifying parcels beyond what base zoning would normally permit. In multifamily zones, there is no unit cap—density is limited only by the base zoning envelope (FAR, height, setbacks) and fire/access requirements. Note: ADUs in the Coastal Zone may still require a Coastal Development Permit (CDP), which involves a separate review process.

Is the ADU Bonus Program available outside the City of San Diego?

No. The ADU Bonus Program is a City of San Diego–specific program established under the municipal code. Other jurisdictions in San Diego County have their own ADU regulations, which differ significantly in scope and allowable density.

Is there a unit limit under the ADU Bonus Program?

In RM (multifamily) zones within SDA/TPA areas, there is effectively no unit cap. In RS (single-family) zones within SDAs, Ordinance O-2025-136 now caps units at 4–6 depending on lot size (4 for lots ≤8,000 SF, 5 for 8,001–10,000 SF, 6 for ≥10,001 SF). Affected zones are RS-1-1 through RS-1-4 and RS-1-8 through RS-1-11. These caps do not apply in High/Highest CTCAC Opportunity Zones. Outside of SDA, the state SB 1211 pathway allows up to 8 detached ADUs on lots with an existing multifamily dwelling (capped at the number of existing units on the lot). For proposed new multifamily buildings, the state cap is 2 detached ADUs.

Is the ADU Bonus Program intended for multifamily development?

Yes. While the program technically applies to both single-family and multifamily parcels, Ordinance O-2025-136 significantly reduced its usefulness on single-family lots through unit caps, FAR limitations, and enhanced fire safety requirements. The program's density advantages are most meaningful—and most economically viable—on multifamily-zoned parcels.

What are the affordability requirements?

ADU Bonus units must be deed-restricted at 110% of Area Median Income (AMI) for a period of 15 years. Affordable/bonus ADUs must match the size and bedroom count of bonus units. Deed restrictions must be recorded before building permit issuance. Violations carry penalties of up to $10,000 per month. Despite these requirements, this remains the least restrictive affordability framework of any density bonus program in San Diego.

Are development fees waived for ADU Bonus projects?

Partially. Development Impact Fees are fully waived for the first 2 ADUs on any qualifying parcel and for all ADUs under 750 square feet. Remaining ADUs are assessed on a sliding scale based on unit size. A Community Enhancement Fee for sub-750 SF units was adopted as part of Ordinance O-2025-136 and is now in effect—contact the City for current rates.

What are the fire safety requirements?

In High Fire Severity Zones, bonus ADU projects must have two exit routes, sprinkler systems, and comply with stricter setback and defensible space requirements. Cul-de-sac lots and lots with limited emergency vehicle access in HFSZ areas are excluded from the program. Outside HFSZ, standard ADU fire and building code requirements apply.

What is CCHS and how does it increase development yield?

CCHS (Complete Communities Housing Solutions) is San Diego's local density bonus program that can significantly increase your buildable units. ArchiDev Studio has achieved results like 4 base units to 14 yield units using CCHS Coastal Tier 2.5 FAR allowances.

What types of multifamily projects does ArchiDev specialize in?

ArchiDev specializes in 20-100 unit infill housing, mixed-use corridors, and transit-oriented development. We work with market-rate, workforce, and affordable/LIHTC developers to maximize site potential through density bonus programs.

How does ArchiDev's code-first design approach work?

Code-first design means regulations inform the design from day one. We analyze zoning, density bonus eligibility, and entitlement pathways before drawing a single line—ensuring maximum yield and streamlined approvals.

The ADU Bonus Program as a Developer Density Tool

San Diego’s ADU Bonus Program is a high-leverage infill strategy that can significantly increase unit yield—especially on multifamily-zoned sites—while staying within a predictable regulatory framework.

The program’s core premise is simple: increase residential unit count by pairing market-rate ADUs with deed-restricted affordable ADUs, while still designing within the site’s base-zone development envelope.

What developers should know up front:

Unit yield can be very high and, in some multifamily scenarios, effectively uncapped—but it is always constrained by base-zone FAR, height limits, setbacks, fire/access requirements, and site design efficiency.
The program is best suited to multifamily and higher-density residential parcels, where it can unlock substantial additional units without relying on rezones.
Recent rule changes have reduced the program’s usefulness for many single-family-zoned lots, so the most scalable opportunities are generally in multifamily zones.
A strong alternative density pathway for sites outside Complete Communities Housing Solutions (CCHS) areas—especially multifamily-zoned parcels where maximizing yield is the priority.

Key Advantage: Unlimited Density in Multifamily Zones

Multifamily-Zoned Sites (RM Zones)

Multifamily zones remain largely unaffected by recent program changes. In these zones, the ADU Bonus Program continues to allow unlimited ADUs, subject to base zoning controls.

Key rules for RM-zoned properties:

No unit cap on ADUs
Base FAR and height limits apply
Affordability requirements apply
Fire access rules may limit yield in HFSZ areas

Two primary paths exist:

RM within SDA / TPA → Unlimited ADUs (base envelope controls apply)
RM outside SDA → SB 1211 pathway (up to number of existing units, capped at 8)

This makes the ADU Bonus Program a viable alternative to density bonus law on constrained or irregular sites.

Important Distinction: Not a Single-Family Strategy

Recent updates to the ADU Bonus Program significantly limit density on single-family zoned lots, making them far less attractive for development-scale projects.

Single-Family Zones (RS)

Many RS zones are now ineligible for the Bonus Program
Remaining RS zones are subject to strict unit caps
FAR is artificially capped using an 8,000 SF calculation method
Bonus density is no longer scalable

As a result, this program is no longer intended for speculative single-family upzoning and is best deployed on multifamily-designated parcels.

Envelope Controls: Density Without FAR Relief

Unlike Complete Communities, the ADU Bonus Program does not provide FAR increases. Developers must work within:

Base zone FAR
Base zone height limits
Fire setbacks (if applicable)
Access and egress constraints

This creates a tight but predictable envelope, favoring:

Smaller unit sizes
Efficient circulation
Repetitive unit stacking
Type V wood-frame construction

In practice, this often results in higher unit counts than zoning alone would permit, even without FAR relief.

Affordability Requirements (Developer-Friendly)

The ADU Bonus Program requires affordability, but at levels that remain very close to market rents.

Current affordability standards:

Units must be rented at ≤110% Area Median Income (AMI)
15-year deed restriction for low or moderate income units
No long-term (55-year) covenant as required under other programs

At 110% AMI, rents often track closely with prevailing market conditions, making this one of the least restrictive affordability frameworks available.

Fees, Waivers & the New Community Enhancement Fee

Development Impact Fees (DIFs)

First two ADUs → DIFs waived regardless of size
ADUs ≤750 SF → No DIFs under state law
Additional ADUs >750 SF → Fees assessed on a sliding scale
No double-charging for affordable units

New: Community Enhancement Fee

Recent program updates introduce a Community Enhancement Fee for certain ADUs under 750 SF. The fee schedule has not yet been finalized, but it represents a new cost consideration for high-unit-count projects.

Despite this change, the ADU Bonus Program still offers significant fee advantages compared to traditional multifamily development.

Parking & Transit Rules

Within SDA / TPA → No parking required
Inside SDA / Outside TPA → 1 space per ADU
Site-specific reductions may apply depending on access, street width, and emergency services

This strongly incentivizes transit-adjacent multifamily sites, where parking can be fully eliminated.

Fire & Site Constraints (Critical for Feasibility)

Fire regulations can significantly affect yield and must be evaluated early:

High Fire Severity Zones (HFSZ) impose stricter access and setback requirements
Lots without two points of ingress/egress may be ineligible
Outside HFSZ, zero-lot-line ADUs up to 16’ remain allowed

Multifamily sites outside HFSZ offer the cleanest path to unlimited ADUs.

Strategic Positioning for Developers

The ADU Bonus Program works best when:

Zoning already supports multifamily use
Sites are constrained but transit-adjacent
Developers seek maximum yield without discretionary approvals
Long-term affordability covenants are undesirable

It is not a replacement for Complete Communities, but rather a parallel density tool that excels on:

Smaller RM parcels
Irregular lots
Infill sites where rezoning is impractical

How ArchiDev Studio Uses This Program

ArchiDev Studio evaluates ADU Bonus Program feasibility through:

Envelope optimization studies
Yield vs. fee tradeoff modeling
Fire and access constraint analysis
Affordability strategy alignment

Our approach is developer-first, ensuring the program is used only where it meaningfully improves project economics.

Next Steps

Not every site qualifies—but when it does, the ADU Bonus Program can unlock density that zoning alone cannot. Contact us for a site-specific feasibility analysis.

Book a Consultation

This page is provided for general informational purposes only and is intended as a high-level overview of the City of San Diego’s ADU Bonus Program as it applies to multifamily and higher-density residential development. Program requirements, fee structures, eligibility criteria, and interpretations are subject to change and may vary based on zoning, site conditions, overlay zones, fire regulations, and agency discretion. This content does not constitute legal, financial, or entitlement advice. Project feasibility, unit yield, and affordability obligations must be evaluated on a site-specific basis in coordination with the appropriate public agencies and professional consultants.

THE ADU BONUSPROGRAM AS A DEVELOPERDENSITY TOOL

The ADU Bonus Program as a Developer Density Tool

Key Advantage: Unlimited Density in Multifamily Zones

Multifamily-Zoned Sites (RM Zones)

Important Distinction: Not a Single-Family Strategy

Single-Family Zones (RS)

Envelope Controls: Density Without FAR Relief

Affordability Requirements (Developer-Friendly)

Fees, Waivers & the New Community Enhancement Fee

Development Impact Fees (DIFs)

New: Community Enhancement Fee

Parking & Transit Rules

Fire & Site Constraints (Critical for Feasibility)

Strategic Positioning for Developers

How ArchiDev Studio Uses This Program

Next Steps

THE ADU BONUS
PROGRAM AS A
DEVELOPER
DENSITY TOOL