Coronado · 92118 · Across the bay from Chula Vista
ADU Builder in Coronado, CA
Coronado has its own detailed ADU code, and in December 2025 the state told the City that 31 parts of them break California law. Coronado ADU, JADU and carriage house inquiries from this site are handled by a licensed San Diego general contractor. Below: the City code as written, the state's objections, and the points still in dispute.
Modern house with a green yardShort answer
You can add an ADU in Coronado, including the City's own carriage house type: a two-story accessory building with a garage below and up to 400 sq ft of living space above. The rules are in Coronado Municipal Code 86.56.105 and 86.56.110, largely set by Ordinance 2024-02 in April 2024. On December 10, 2025, the state housing department (HCD) found that ordinance out of compliance on 31 points, including its 16 ft height cap, six-month rental minimum, FAR limits and ban on separate sale. The City answered on February 6, 2026, agreeing to amend most items but holding firm on FAR, land surveys, parking and carriage house conversions. We found no adopted amendment as of November 7, 2026, so expect state ADU law to control wherever the City code is stricter, and expect some friction at the counter.
Coronado next to Chula Vista
Chula Vista sits straight across the bay, but the two cities treat ADUs very differently.
| Item | Coronado | Chula Vista (for comparison) |
|---|---|---|
| Code status | Ord. 2024-02 under HCD findings; amendments pending | CVMC 19.58.022 and 19.58.023, with state law filling the gaps |
| FAR on a new house plus ADU | City counts the ADU; HCD says it cannot | State limits on applying FAR to ADUs |
| Shortest rental | 26 days in residential zones; the ADU code says six months | 30 days |
| Pre-approved plans | Three RRM Design Group plans approved July 21, 2026 | Chula Vista offers 12 Standard ADU Plans |
| Water | California American Water | Sweetwater Authority or Otay Water District |
Coronado items from the City's ADU page, HCD's December 10, 2025 letter and Coronado Times reporting from August 2026. Chula Vista's own rules are in the Chula Vista ADU requirements guide.
The carriage house
Coronado treats this as its own type. Under CMC 86.56.110, a carriage house is a detached two-story accessory building: an enclosed garage on the ground floor and no more than 400 sq ft of habitable space upstairs, which can have its own kitchen and bathroom and work as a complete unit.
It suits lots with rear garage access, since the garage keeps its parking and the unit gets light and privacy above. Two cautions. The City's new pre-approved plans do not cover carriage houses or JADUs. And when an owner wants to convert an existing carriage house, the City still applies the 86.56.110 standards, which HCD told it to drop; the City's February letter says that request "exceeds existing state law." If you own one, expect that question to come up in plan check.
What HCD found, and where things stand
HCD's December 10, 2025 letter listed 31 findings and gave the City until January 9, 2026 to amend the ordinance or adopt findings defending it. HCD extended the deadline to February 8, and the City replied on February 6. The points that matter most to a homeowner:
| Issue | Coronado code | What HCD says | City's reply (Feb 2026) |
|---|---|---|---|
| Detached height | 16 ft | Allow 18 ft, plus 2 ft for roof pitch, within a half mile of a major transit stop | Not among the points contested |
| Units per lot | One ADU or JADU | Allow the full state combinations plus a JADU | Not among the points contested |
| Rental minimum | Six months, by deed restriction | No minimum longer than 30 days; no ADU deed restriction | Not among the points contested |
| Separate sale | Banned | Allowed in the cases state law permits | Not among the points contested |
| Design rules | Must match the house's style and materials | Only objective standards allowed | Not among the points contested |
| FAR | Applied when a new house and ADU are built together | Cannot be applied to the ADU | Declined, citing Scurlock v. City of Coronado (2024) |
| Land surveys | Licensed survey before and after construction | Remove; use permit records and inspections | Declined |
| Parking | One space per unit; replacement for converted garages | Add state exemptions or cite the Coastal Act | Relies on the Coastal Act |
Findings from HCD's letter; City positions as reported by the Coronado Times on August 11, 2026. The Times noted that Scurlock is unpublished and was decided under the former ADU statute.
As of August 2026, the City had asked to meet HCD staff before public hearings and had set no hearing date. We found no later hearing or adoption by November 7, 2026. If a city neither amends nor justifies its ordinance, HCD can refer the matter to the Attorney General.
In practice, state ADU law already overrides stricter local rules, and you can cite it. The City may still read its code its own way, as one resident planning an 800 sq ft ADU told the council on July 21. Leave room in the schedule for that.
Historic review
Coronado's housing stock is old, and the City protects it. If your project removes or demolishes original features visible from the street on a building 75 years old or more, the City requires a Determination of Historic Significance Review under Chapter 84.10, unless the property is listed as Tier 3 in the citywide inventory. For a designated Historic Resource, any exterior change needs a Historic Resource Alteration Permit under Chapter 84.20, and the Historic Resource Commission decides it at a public hearing using the Secretary of the Interior's Standards.
A detached ADU at the back of the lot often avoids touching the street face, which keeps it out of this review. A garage conversion or an attached unit on a corner lot may not. If your home already carries a Mills Act contract, ask Planning early whether an ADU affects it.
Coastal permits and parking
The City told HCD that the whole city lies in the Coastal Zone, and it relies on the Coastal Act to keep its ADU parking rules. Coronado reviews coastal permits under CMC 86.70, and HCD's Finding 31 asked the City to run that review at the same time as the ADU permit unless the owner asks otherwise. Until the code changes, plan for a coastal step and for a parking space per unit, and ask whether a half-mile walk to the ferry terminal or a bus stop exempts your lot.
The pre-approved plans
On July 21, 2026 the City Council unanimously authorized three pre-approved ADU designs by RRM Design Group, each in a different style: coastal cottage, Mediterranean, and contemporary. The local paper reported one-bedroom versions sized around 408 and 462 sq ft and a two-bedroom around 679 sq ft; check the agenda packet for exact figures. The Community Development Director said most Coronado ADUs are custom and he expects that to continue. A new house paired with one of these plans still has to meet FAR, as the City reads its code today.
What a Coronado ADU costs
Our ADU cost calculator is calibrated to Chula Vista. Coronado construction falls in similar coastal ranges, but extra drawings, surveys and review time push the soft costs up. Mid-finish planning figures before Coronado's own fees:
- Carriage house unit over a new garage: no calculator setting covers a two-story garage building; price it as a custom detached project.
- 500 sq ft detached unit: about $260,000, roughly $224,000 to $296,000.
- 740 sq ft detached unit: about $327,000, roughly $281,000 to $373,000.
- 400 sq ft garage conversion: $145,000 to $153,000.
- 300 sq ft JADU: about $100,000.
Fee differences to plan for:
- Surveys: the City currently asks for a licensed land survey before and after construction. A 2021 San Diego Housing Commission study put survey costs at $725 to $7,682 per site.
- City fees: Chula Vista's flat ADU fees do not apply. Get a Coronado planning and building fee estimate once plans exist; coastal and historic reviews can each add a line.
- School fees: Coronado Unified School District collects them on units over 500 sq ft, capped by the state Level 1 maximum of $5.38 per sq ft since January 2026. Confirm the district's current rate.
- Impact fees: none under 750 sq ft or for JADUs under state law, which HCD's Finding 22 told the City to state plainly.
- Water: California American Water serves Coronado. Ask Cal Am about a separate service before you design one.
Rents in Coronado
Zumper's Coronado averages, updated November 7, 2026, were studio $1,982, one-bedroom $3,617 and two-bedroom $6,000, drawn from a thin 30-day listing sample, so they swing a lot. HUD's FY2027 metro Fair Market Rent, $2,335 for one bedroom, is far lower. A cautious plan for a new one-bedroom ADU is somewhere between those two sources, roughly $2,500 to $3,500, on a lease of six months or more until the City's minimum changes.
Say a 450 sq ft one-bedroom rents for $3,000: $36,000 gross, about $31,300 after vacancy, upkeep and roughly $750 in new property tax. On a build of about $246,000 that is near 12% a year, though Coronado's longer approvals can delay the first rent check.
In pictures
Small units that suit Coronado lots
These are licensed stock photos (Pexels) chosen to show the kind of space or place described. They are not photographs of our contractor's completed projects.
Coronado ADU questions
Is Coronado's ADU ordinance legal?
HCD says parts of it are not. Its December 10, 2025 letter found 31 points out of line with state ADU law. The City agreed to amend most of them in February 2026 but disputes FAR, surveys, parking and carriage house conversions. Where the City code is stricter than state law, state law controls.
Does an ADU count against my FAR in Coronado?
The City says yes when a new house and ADU are proposed together, citing a 2024 court decision. HCD says the City may apply FAR to the house but not to a detached ADU built with it. This is the most contested point, so settle it with Planning before you size the house.
Can I rent my Coronado ADU to tourists?
No. Coronado prohibits short-term vacation rentals in residential zones and requires at least 26 consecutive days. The ADU code goes further, with a six-month minimum that HCD has told the City to reduce to 30 days.
What is a carriage house ADU?
A two-story detached accessory building with an enclosed garage below and up to 400 sq ft of living space above, under CMC 86.56.110. The upstairs can have a kitchen and bathroom and be rented as a unit.
Will my 1920s house trigger historic review?
Only if the project removes or demolishes original features you can see from the street, or the home is a designated Historic Resource. A rear detached ADU often avoids it; a change to the front of the house may not.
Sources
- HUD, Fair Market Rents (FY2027 San Diego metro)
- City of Coronado, Accessory Dwelling Units (ADUs) and Junior ADUs
- California HCD, Review of Coronado's ADU Ordinance (Dec 10, 2025)
- Coronado Times, State found Coronado's ADU laws out of compliance on 31 points (Aug 11, 2026)
- Coronado Eagle & Journal, Council approves pre-approved ADU program (Jul 30, 2026)
- Zumper, Coronado rent research (Nov 7, 2026)
- City of Coronado, Historic Preservation
- City of Coronado, Code Enforcement (short-term rentals)
- California American Water, San Diego County district customers (2023 release)
- San Diego Housing Commission, ADU Pilot Program Report (Oct 2021)
- State school fee cap raised to $5.38 per sq ft (Lozano Smith, 2026)
Last checked November 7, 2026. Coronado's ordinance is under state review and may change; confirm current standards, fees and coastal and historic requirements with the City's Community Development Department before you design.
Next step
Get your free Chula Vista ADU Fit Check
Three short steps, about a minute. A licensed San Diego County general contractor reviews what you send, checks your lot against the City's ADU rules, your HOA and your water district, and replies with a realistic range and the questions that would change it.
- Which ADU types your lot allows, and the size and height limits that apply
- Whether your HOA, a CFD or your water district changes the plan
- A line-by-line range, including fees and utility runs, before you pay for drawings
- No obligation and no pressure follow-up