How the bonus works now
The program trades deed-restricted affordable ADUs for extra market-rate "bonus" ADUs. The Planning Department's ADU page describes the affordable units as restricted to very low-, low- or moderate-income households for 15 years. The current limits are from IB 400:
| Rule | What IB 400 says (January 2026) |
|---|---|
| Zones barred | RS-1-1, RS-1-2, RS-1-3, RS-1-4, RS-1-8, RS-1-9, RS-1-10, RS-1-11, except the part of a lot in a High or Highest Resource CTCAC Opportunity Area that the land use plan shows as residential |
| Bonus count, inside a Sustainable Development Area | One bonus ADU for each deed-restricted ADU on site |
| Bonus count, outside | At most one bonus ADU and one deed-restricted ADU |
| Cap in single dwelling unit zones | 4 ADUs and JADUs on lots of 8,000 sq ft or less; 5 on 8,001 to 10,000 sq ft; 6 on larger lots |
| Floor area | Only lot area outside environmentally sensitive lands counts, and no more than 8,000 sq ft of it in single dwelling unit zones |
| Parking | One off-street space per affordable and bonus ADU outside a Transit Priority Area |
| Fire zones | In a Very High Fire Hazard Severity Zone the lot must front an improved public street with two evacuation routes; no bonus ADUs on a cul-de-sac or a lot with one way in |
| Sprinklers | Automatic fire sprinklers in all affordable and bonus ADUs |
| Fee | A Community Enhancement Fee on the floor area of the affordable and bonus ADUs |
| Affordability paperwork | Agreement and deed of trust with the San Diego Housing Commission before the first affordable or bonus ADU building permit |
The Planning Commission advanced these changes on 1 May 2025 (City release); the package also proposed fines of at least $10,000 per affordable ADU per month for deed-restriction violations. In the Coastal Overlay Zone, IB 400 says the newer ordinances (O-21618, O-21758, O-21836 and O-21989) take effect only after Coastal Commission certification, and it does not say they have been certified, so near the coast ask staff which version applies.
The rules without the bonus
A lot with a single-family home can have one attached or detached ADU, one ADU converted from existing space or an accessory structure, and one JADU. New ADUs run 150 to 1,200 sq ft. In a Very High Fire Hazard Severity Zone an ADU needs at least 4-foot side and rear setbacks. Since the August 2025 update most ADUs can be split off as condominiums and sold separately, after final inspection and a 30-day listing to owner-occupant buyers; JADUs cannot (IB 400 notice, 27 August 2025).
What it means when you hire
- Ask the zone first. A designer quoting a bonus project on an RS-1-7 or RS-1-8 lot should be able to tell you which side of the line it is on, before you pay for plans. Zone lookups are on the City's zoning pages.
- Sprinklers and fire access change the price. Every bonus or affordable unit needs sprinklers, which a plain ADU often does not.
- License. The builder needs a California CSLB license; check it on the San Diego contractor license lookup. In our file 52.0% of ADU firms matched an active license; 44.5% matched no license under the name on the permit.
- Ask for finished units. 72.5% of ADU firms in our data filed one permit in three years.
What 1,278 San Diego ADU permits show
| Measure | City of San Diego ADUs |
|---|---|
| Permits, October 2023 to September 2026 | 1,278 |
| Firms / active in the last 12 months | 640 / 258 |
| Usual filed value | $127,372 |
| Middle half of builders' usual job (93 firms with 3+ permits) | $105,805 to $174,174 |
| Usual days from issue to final | 442 |
| Finished (permits a year or more old) | 75.1% |
| Busiest / quietest month to file | April / September |
| Busiest firm, last 12 months | 1PLUS Studio (28) |
From issue to final, the usual ADU took 442 days, more than a year, so a bonus project with several units and sprinklers should be scheduled as a long build. The filed value is what the applicant declared for the permit and usually leaves out design, fees and site work.
Compare San Diego ADU builders by permit record →
Related
Filed values by size and home value: San Diego ADU cost. Unincorporated areas follow County rules instead: ADU cost in San Diego County. Looking up a permit: San Diego building permit search. Year-by-year counts: San Diego permit statistics.
What this does not tell you
Our permit file does not mark which ADUs used the bonus program or which were deed-restricted, so the figures cover every City of San Diego ADU permit. The rules above are from IB 400 as of January 2026; the City has amended the program several times, so confirm with Development Services before you design.
How we know this
Program rules are from the City of San Diego's Information Bulletin 400 (January 2026), its 27 August 2025 public notice, the Planning Department's ADU page and the City's 1 May 2025 release, all read 23 October 2026. Permit counts and filed values are City of San Diego permits on homes classified as ADUs, October 2023 to September 2026; the finished share uses permits a year or more old.
Numbers come from City of San Diego Development Services approvals, data through October 15, 2026. Nobody paid to be on this page and nobody can.
Questions
- Does San Diego still have the ADU bonus program?
Yes, in revised form. The City's Information Bulletin 400 (January 2026) keeps the ADU Home Density Bonus Program but bars bonus ADUs in the RS-1-1 to RS-1-4 and RS-1-8 to RS-1-11 zones, except in High or Highest Resource CTCAC Opportunity Areas, and caps total ADUs and JADUs in single dwelling unit zones by lot size.
- How many ADUs can I build in San Diego?
Without the bonus, a lot with a single-family home can have one new attached or detached ADU, one ADU converted from existing space and one JADU. With the bonus program in a single dwelling unit zone, IB 400 caps ADUs and JADUs at 4 on lots of 8,000 sq ft or less, 5 on 8,001 to 10,000 sq ft and 6 on larger lots.
- What is the maximum ADU size in San Diego?
1,200 sq ft of gross floor area for an attached or detached ADU, with a 150 sq ft minimum. A conversion of an existing accessory structure or part of the house is not held to the 1,200 sq ft cap (IB 400, January 2026).
- Do bonus ADUs in San Diego need fire sprinklers?
Yes. IB 400 says all affordable and bonus ADUs in a development must have automatic fire sprinklers under the California Building Code, and in a Very High Fire Hazard Severity Zone the lot must front an improved public street with at least two evacuation routes.
- How much does an ADU cost in San Diego?
ADU permits in the City of San Diego were filed at a usual $127,372 in our data, with the middle half of builders' usual jobs between $105,805 and $174,174. Filed value is the declared construction value, not the full price.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
Related guides
- Austin HOME initiative: three units on one lot, 1,800 sq ft small lots, and what it means when you hire a builder
- ADU construction cost in 2026: what ADU permits were filed at in 12 cities
- ADU vs home addition: what the permit file shows
- Can an unpermitted ADU be legalized? California's AB 2533 rule, and what it costs and takes
For one city
- Information Bulletin 400: Accessory Dwelling Units / Junior ADUs — City of San Diego Development Services (January 2026) (accessed 2026-10-23)
- Public notice: Information Bulletin 400 updates — City of San Diego (27 August 2025) (accessed 2026-10-23)
- Accessory Dwelling Units — City of San Diego Planning Department (accessed 2026-10-23)
- ADU program reforms advance to Land Use & Housing Committee — City of San Diego (1 May 2025) (accessed 2026-10-23)