The City's rules
From Information Bulletin 400 (January 2026, read 26 October 2026). Some of the newer rules are not yet in effect in the Coastal Overlay Zone; IB 400 lists which.
| Rule | What IB 400 says |
|---|---|
| Permit | Building Permit or Combination Building Permit, "no exemptions"; Information Bulletin 125 decides which |
| Coastal | A Coastal Development Permit for ADUs in the Coastal Overlay Zone not fully inside the existing house; in the non-appealable area it can be issued as a building permit if administrative findings are met |
| How many, single-dwelling zone | One attached or detached ADU, one ADU converted from existing space or an accessory structure, and one JADU |
| Size | New ADU 150 to 1,200 sq ft; one ADU up to 800 sq ft allowed even over the zone's floor area ratio |
| Height | On single-unit lots, detached ADUs no more than two stories, within the zone's height limit |
| Fire zones | In a Very High Fire Hazard Severity Zone, at least 4-foot side and rear setbacks |
| Parking | "No parking spaces are required for ADUs outside of the Coastal Overlay Zone" |
| Sprinklers | Only if the main house has them; a detached ADU does not trigger sprinklers in the house |
| Solar | A newly built, non-manufactured detached ADU must have solar panels under the Energy Code, on the ADU or the house |
More units through the ADU Home Density Bonus Program have their own limits and fees; see San Diego ADU bonus program. Look up your zone first in the City's ZAPP portal.
What to submit
IB 400's minimum for each ADU or JADU: site plan and vicinity map, floor and roof plans, elevations and sections, structural plans and details, structural or truss calculations, Title 24 energy calculations, the General Application (DS-3032), the Water Meter Data Card (DS-16) and the Storm Water Applicability Checklist (DS-560). Projects with a single house follow Project Submittal Manual Section 2A.
The preapproved-plan route. Under AB 1332 you can apply with a plan the City has preapproved; "Applications that utilize preapproved plans will be subject to a 30-day review." You license the plan from its designer, who sets the price, and it still has to meet the zone's development rules.
Who can pull it
A licensed builder. A new ADU is general building work, CSLB class B (CSLB classifications); check the license with the San Diego contractor license lookup. In our file 52.0% of ADU firms matched an active CSLB license, and 44.5% matched no license under the name on the permit; for those, ask who will hold the contract and check that name.
You, as owner-builder. The City's owner-builder verification form is DS-3042 (IB 301 refers to it). As owner-builder you are the responsible party for the build.
What it costs
IB 400 does not price the permit; it points to Information Bulletin 501 and the City's Fees page, and lists the charges that apply to ADUs:
| Charge | When it applies (IB 400) |
|---|---|
| Building permit and plan check | Every ADU (IB 501) |
| School fees | ADUs and JADUs, per Information Bulletin 146 |
| General Plan Maintenance Fee | All ADUs and JADUs since 9 August 2022 |
| Development Impact Fees | Per SDMC §142.0640(b)(1) |
| Regional Transportation Congestion Improvement Program fee | Projects with more than one ADU |
| Inclusionary housing | If ADUs bring the lot to 10 or more units (5 in the Coastal Overlay Zone) |
| Community Enhancement Fee | Bonus-program ADUs only |
Ask the City for a fee estimate on your square footage before you pay for full plans. Fees are paid online by e-check or card.
How to apply
- Find the zone and overlays in ZAPP: coastal, fire hazard, historic.
- Apply digitally in the City's Development Services Application Portal: under Building Applications choose "Building Construction". Changes after issue go in as "Construction Change to a Building Permit".
- Plan review, 30 days on a preapproved plan.
- Build and inspect. The permit lists the inspections; the final closes it. Since the August 2025 update most ADUs can then be split off and sold as condominiums after a 30-day offer to owner-occupant buyers; JADUs cannot.
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 |
| Reached final (permits a year or more old) | 75.1% |
| Usual days from issue to final | 442 |
| Firms with a single permit | 464 (72.5%) |
| Busiest / quietest month to file | April (134) / September (58) |
An ADU here is a long job: 442 days from issue to final is usual, and 75.1% of permits a year or more old had reached final. The field is fragmented: 72.5% of firms filed one ADU in three years and the busiest holds 2.8%, so ask any builder for addresses of finished San Diego ADUs and look them up. Values by size and home value: San Diego ADU cost; national: ADU construction cost.
Compare San Diego ADU builders by permits finished →
Related
Rules elsewhere: do I need a permit for an ADU. Unincorporated areas follow County rules: ADU cost in San Diego County. An existing unpermitted unit: can an unpermitted ADU be legalized. Past permits: San Diego building permit search. Counts by year: San Diego permit statistics.
What this does not tell you
Filed value is what the applicant declared and usually leaves out design, fees and site work. Our file does not say which ADUs used preapproved plans or the bonus program. IB 400 does not list fee amounts, so we give none.
How we know this
Permit, coastal, size, height, parking, sprinkler, solar, submittal, fee-category and application rules are quoted from the City of San Diego's Information Bulletin 400 (January 2026), read 26 October 2026; the owner-builder form from IB 301 and license classes from CSLB. Our figures are City of San Diego permits 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
- Do I need a permit to build an ADU in San Diego?
Yes, always. Information Bulletin 400 says 'A Building Permit is required to create an ADU or JADU. There are no exemptions.' Depending on the number of units it is a Combination Building Permit or a Building Permit, and in the Coastal Overlay Zone most ADUs also need a Coastal Development Permit.
- How big can an ADU be in San Diego?
A new attached or detached ADU is 150 to 1,200 square feet of gross floor area. One ADU up to 800 square feet is allowed even if it pushes the lot over the zone's floor area ratio, and a conversion of existing space is not held to the 1,200 limit.
- How long does an ADU permit take in San Diego?
Plan review on the City's preapproved ADU plans is 30 days under AB 1332. Building takes longer: in our file the usual ADU permit reached final 442 days after it was issued.
- What fees do you pay for an ADU in San Diego?
IB 400 lists school fees, the General Plan Maintenance Fee on all ADUs and JADUs since 9 August 2022, Development Impact Fees under SDMC 142.0640(b)(1), and Regional Transportation Congestion Improvement Program fees when a project adds more than one ADU, plus building permit and plan check fees from Information Bulletin 501.
- Do I need parking for an ADU in San Diego?
Not outside the Coastal Overlay Zone. Inside it, a space is needed only in the Beach Impact Area outside a transit priority area, and even there not for an ADU of 500 square feet or less, an attached ADU, or a few other cases.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
Related guides
- Can an unpermitted ADU be legalized? California's AB 2533 rule, and what it costs and takes
- Do I need a permit for an ADU? Yes; here is what 9 cities require, and how long it takes
- San Diego building permit search: how to look up permits on an address
- Bellingham ADU rules under the 2025 interim ordinance: two per lot, 1,000 sq ft, no owner occupancy, and what ADU permits show
For one city
- Information Bulletin 400: Accessory Dwelling Units / Junior ADUs (January 2026) — City of San Diego Development Services (accessed 2026-10-26)
- Accela Citizen Access (Development Services Application Portal) — City of San Diego (2026-10-26)
- Zoning and Parcel Information Portal (ZAPP) — City of San Diego (2026-10-26)
- Information Bulletin 301 (owner-builder form DS-3042 reference) — City of San Diego (accessed 2026-10-23)
- CSLB Licensing Classifications (2026-10-22)