Coronado's Community Development Department decides ADUs and issues their building and coastal permits; the whole city lies in the Coastal Zone, and the City holds its own coastal permit authority. Its ADU section was rewritten by Ordinance 2026-08, adopted 5 to 0 on October 6, 2026 and in force November 5, which answers most of the 31 points the state's housing department raised in December 2025. The City kept a few: floor area limits on an ADU built with a new house, a parking space per ADU under the Coastal Act, surveyor certification, its carriage house rules and a covenant on every ADU. Three pre-approved plans were authorized in July 2026 for release this fall, and no part of Coronado sits in a fire hazard zone.
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BHI Builders takes on ADUs, remodels, additions and custom homes in Coronado, where the whole city lies in the Coastal Zone and an updated ADU section takes effect November 5, 2026. This page is built from Coronado's code, the state's findings and the Council's records.
Who issues permits here, and how does plan check run?
An ADU application goes to Community Development on the City's ADU form, and the director decides it. Building permits are applied for in person at City Hall on weekdays; the City has no online portal, and only small over-the-counter jobs go by email. Plan review sends the plans to Building, Planning, Engineering, Public Services and outside reviewers, and the City's handout puts the average first round of comments at ten to twelve business days; a plan check left open expires after 180 days, with one extension.
The code makes an ADU ministerial and decides it within 60 days of a complete application, and an ADU filed with a new house waits for the house, then gets its own 60 days. The City's ADU form still says the City has 60 days just to find the application complete; state law gives 15 business days, after which it is deemed complete, and governs. A coastal permit comes before the building permit under the City's code, while state law since AB 462 wants an ADU's coastal permit decided within the same 60 days, without a hearing, and beyond appeal to the Coastal Commission.
For the projects homeowners bring most often:
- An ADU or junior ADU: the City's ADU application, a coastal permit or exemption, surveyor certification for new walls near the lines, a sewer capacity fee at a fraction of a home's, and the building permit at City Hall.
- A kitchen or bath remodel that moves plumbing, wiring or walls: a building permit at City Hall reviewed against the 2025 codes, with a historic significance check where street-visible original features of a house 75 years or older come out.
- An addition or a second story: the zone's floor area and height, the coastal permit or its exemption for a single-family house, the historic check, and Coronado Unified's school fee above 500 square feet.
- A new house: floor area, the coastal program, the flood chapter's elevation rules near the bay and ocean, and the City's sewer capacity fee for a full dwelling.
Where do Coronado's ADU rules differ from state law?
Coronado's ADU rules are Municipal Code 86.56.105. Ordinance 2024-02 was the version the state's housing department reviewed, finding 31 points out of line on December 10, 2025; the City replied on February 6, 2026, conceding most of them. Ordinance 2026-08, recommended by the Planning and Design Commission on August 11, introduced 5 to 0 on September 1 and adopted 5 to 0 on October 6, 2026, takes effect November 5. Until then the 2024 text stands, though its own last subsection says state law controls where they conflict, and the City says it already applies state law.
The table states the section as it reads from November 5, 2026, with state law where the two still differ.
| Rule | In the City of Coronado |
|---|---|
| The units | A converted unit and a junior ADU; one new detached unit up to 800 square feet; converted space in an apartment building, one unit up to a quarter of the homes; and as many as eight detached units where apartments already stand, capped at the number of homes there, or two with a proposed building. Before November 5 the code read one ADU or junior ADU per single-family lot and two detached units on an apartment lot. |
| Size | 850 square feet at most for a studio or one-bedroom, 1,000 with two bedrooms or more, except a conversion or a unit detached from an apartment building; a junior ADU 500 inside a house on a single-family lot. |
| Floor area | ADUs follow the zone's floor area ratio, and an ADU built together with a new house must fit inside it. The state's housing department says a mandatory unit with a new house is free of floor area limits; the City cites a 2024 court ruling it won and kept the rule. Unsettled; raise it at intake for any new house with an ADU. An ADU added after the house is occupied is outside the calculation. |
| The 800 square foot unit | Allowed with 4-foot side and rear setbacks, checked with the building permit, but only where three findings are made, the last that there is no feasible alternative on the lot. The state's housing department calls that subjective, and state law allows only objective standards, which governs. |
| Height | 16 feet detached; 18 within half a mile's walk of major transit, which HCD says Coronado's ferry terminal is, plus 2 where the roof pitch matches the house; 18 beside a multistory apartment building; up to 25 feet or the house's limit, whichever is lower, for an attached unit. A City director said in July that two-story ADUs are not permitted outside carriage houses; for an attached unit the code and state law allow the height, so confirm at intake. |
| Setbacks and surveys | None for a conversion or a same-footprint rebuild, 4 feet at the sides and rear otherwise, with a licensed surveyor's certification before and after construction, which the City defends because many lots lack records and HCD says exceeds state law. |
| Design | Similar architectural features to the house, such as roofing, roof pitch and siding. |
| Parking | One space per ADU, tandem, uncovered or in a setback allowed, front-yard parking only in an existing driveway, and replacement when an ADU takes a garage; none for a junior ADU or a deed-restricted affordable unit. The City rests these on the Coastal Act, which state law preserves, and HCD asks it to cite the provisions; no document read settles it, and the City applies its rule. |
| Carriage houses | A two-story building on an alley with a garage below and up to 400 square feet of living space above may be converted, but stays under the carriage house rules; HCD says a converted one is an ADU like any other, and the City disagrees. Unsettled. |
| Sprinklers | Only if the house has them. |
| Junior ADU | Up to 500 square feet within the walls of a house on a single-family lot, with a cooking facility, its own entrance, and an interior door when it shares the bathroom; the owner lives on site unless it has its own bathroom. |
| Covenant | Recorded on every ADU and junior ADU; state law provides one only for a junior ADU, so for an ADU the statute governs. |
| Rentals | Terms of 30 days or more from November 5, replacing six months; state law wants more than 30 days for the mandatory units and junior ADUs, so 31. No home in a residential zone may be rented for 25 days or less, and the City's form bars short-term rentals of ADUs. |
| Selling a unit on its own | Only a unit built by a qualified nonprofit; the City has no condominium ordinance. |
| Fees | Impact fees begin only above 750 square feet for an ADU and 500 for a junior ADU, then as a share of the house's; no regional transportation fee on an ADU; planning fees waived for a deed-restricted affordable ADU. |
Where the City's documents still read differently from state law, and what governs:
- Completeness in 60 days on the City's form, and the coastal permit before the building permit with a Planning Commission hearing in the coastal chapter: state law's 15 business days and its 60-day, no-hearing coastal decision govern; the update did not touch either.
- No ADU occupancy before the house's, with no exception for a house lost in a declared emergency: state law adds that exception, and governs.
- The code's definition of an ADU still cites the repealed state section; a drafting lag only.
Can you build from a pre-approved ADU plan here?
Soon. The City hired RRM Design Group in June 2025 for three single-story detached plans, a 408 square foot unit, a 462 square foot one-bedroom and a 679 square foot two-bedroom, each in a coastal cottage, a Spanish and a contemporary style; the Planning and Design Commission reviewed them on July 14, 2026 and the Council authorized them 5 to 0 on July 21. The City's page says they will be available by fall 2026; using one, only a site plan for setbacks and parking is reviewed, and any change sends the plan through standard plan check.
At the July meeting the director said the City's lot study found few lots able to fit an 800 square foot ADU. Not yet stated: whether the sets are drawn to the 2025 codes, whether a 30-day review is offered, and whether outside designers can submit plans for pre-approval as state law asks.
The coast, historic review and floods
All of Coronado is in the Coastal Zone. The Coastal Commission's record shows the Land Use Plan effectively certified in 1981 and the City taking permit authority in January 1984 after its implementing rules were certified; the code itself names December 1983. A City coastal permit covers any development that is not exempt, and improvements to an existing house and a new single-family house that meets the program are among the exemptions; no City document says which path a detached ADU takes, and the fee schedule prices both a permit and an exemption. Under AB 462 the City's decision on an ADU's coastal permit cannot be appealed to the Commission.
Since December 4, 2025 a historic significance report goes to the Historic Resource Commission for any project that removes street-visible original features of a building 75 years or older, unless the City's inventory classes it Tier 3; altering a designated resource takes its own permit. Whether a ministerial ADU, such as a garage conversion, can trigger that review is not stated. On the flood maps, homes in the coastal high hazard areas are built on anchored piles or columns to the base flood level, landward of mean high tide. The State Fire Marshal's 2025 acreage table lists no hazard zone in Coronado.
Civil Code 4751 voids any homeowners association rule that bars an ADU or junior ADU or holds it back unreasonably.
What does an ADU pay in Coronado?
Resolution 2026-13, adopted 5 to 0 on April 7, 2026 and in force July 1, sets the fiscal 2026-27 fees: a coastal permit, cheaper when filed with other permits, and a coastal exemption; the historic significance determination; building plan check and inspection by size; and no planning fee for a deed-restricted affordable ADU. The City's April 2026 report exempts ADUs and carriage houses from the regional transportation fee, and the housing in-lieu fee applies to subdivisions, not to single homes or ADUs.
- Sewer. The City's wastewater capacity fee charges an ADU at a little over half a home's equivalent dwelling unit, adjusted yearly; state law limits when an ADU not built with a new house may be charged, and the code exempts junior ADUs and conversions.
- Water. California American Water serves Coronado under its San Diego County tariff; no Cal Am rule on ADU meters was found, and state law binds a water corporation's charges as it does a district's.
- School fees. Coronado Unified's current rate was not found; its last published figures date from 2012 and 2016, so ask the district. A unit no bigger than 500 square feet owes nothing.
How many ADUs Coronado permits
Coronado permits few ADUs: 20 at the peak in 2021, 9 in 2025.
- 102018
- 132019
- 192020
- 202021
- 182022
- 82023
- 52024
- 92025
Coronado's yearly ADU permit counts filed with HCD (the ADU line of Table A2), taken at permit rather than completion, junior ADUs included. The City's 2025 report agrees on 9 permitted, with 11 entitled and 9 finished; its Housing Element plans on 195 ADUs over the 2021 to 2029 period.
Recent changes in Coronado
What has changed in the City's permit rules since 2024, newest first.
Coronado's Ordinance 2026-08, in force November 5, 2026, lists one new 800 square foot detached unit; AB 956 doubles that floor eight weeks later, and in a city wholly inside the Coastal Zone, ask whether the second needs the City's coastal permit. Our guide explains the law.
Ordinance 2026-08 takes effect, updating the ADU section for state law; adopted October 6, 2026, 5 to 0.
The Council authorized three pre-approved ADU plans, 5 to 0, for release in the fall.
The fiscal 2026-27 fees took effect, with ADUs exempt from the regional transportation fee.
The City replied to the state, agreeing to most of the 31 findings and keeping floor area, parking, surveys and carriage houses.
The Council adopted the 2025 California codes with no local changes to the building code.
The state's housing department found Coronado's 2024 ADU rules out of line on 31 points.
Historic review changes took effect, removing Tier 3 properties from the 75-year review.
The Coastal Commission heard the City's housing amendment to its coastal program, including the parking changes for affordable ADUs and carriage houses.
The state found Coronado's Housing Element in substantial compliance.
How BHI approaches a Coronado project
What we look at first on a Coronado lot.
A Coronado project starts with the coastal permit or exemption, the floor area the City applies and the parking it still asks for, then the historic check on a house 75 years or older. On a tight lot the City's surveyor certification comes early too. Book a call to talk through yours.
What an ADU might rent for in Coronado
No agency puts out rents for ADUs by themselves, so the table gives HUD's FY2027 Small Area Fair Market Rent for Coronado's ZIP code, the ROI calculator's opening figure: for each size of unit, the level that 40 percent of recent movers paid under, with utilities.
| ZIP | Studio | 1 bed | 2 bed | 3 bed |
|---|---|---|---|---|
| 92118 | $3,280 | $3,500 | $4,230 | $5,610 |
HUD's FY2027 rents for ZIP 92118 by bedroom count, as held in the ROI calculator. Run your own lot through it over 30 years.
Next steps
Check your lot against the November 2026 section, the coastal path and the parking rule, price the unit, then read what fits.