You price out a backyard unit, your designer sketches something around 1,000 square feet, and then someone at the permit counter asks whether the lot sits within a thousand yards of the beach. Now there is a second permit in the conversation and a second set of standards. In Santa Barbara that question comes up constantly, and it is not the only fork in the road.
Santa Barbara caps a detached accessory dwelling unit at 850 square feet for a studio or one-bedroom and 1,000 square feet with two or more bedrooms on lots under 15,000 square feet, rising to 1,200 square feet on larger lots, with a four-foot interior setback for new construction (§ 28.86.055). If your lot is in the coastal overlay, a coastal development permit comes with it (§ 28.44.110).
Key numbers
| What | Santa Barbara's number | Where it comes from |
|---|---|---|
| Detached unit, lot under 15,000 sq ft | 850 sq ft studio or 1-bedroom; 1,000 sq ft with 2+ bedrooms | § 28.86.055 |
| Detached unit, lot 15,000 sq ft or larger | 1,200 sq ft | § 28.86.055 |
| Attached unit | No more than 50% of the main house's living area | § 28.86.055 |
| Unit carved out of existing space | No size limit | § 28.86.055 |
| Junior unit (inside the house) | 500 sq ft maximum | § 28.86.020 |
| Interior setback, new construction | 4 feet | § 28.86.055 |
| Gap between the house and a detached unit | 5 feet minimum | § 28.86.055 |
| Small "special" detached unit | 800 sq ft, 18 feet and one story | § 28.86.090 |
| Smallest unit you can build new | 150 sq ft efficiency, 220 sq ft studio, 400 sq ft otherwise | § 28.86.050 |
Santa Barbara runs two rulebooks, and you have to pick one
Most cities have one set of accessory dwelling unit standards. Santa Barbara has two, and choosing between them is the first real decision of the project.
Standard units are the bigger ones. You get the floor areas in the table above — up to 1,200 square feet on a large lot — but only one unit on the lot, on top of the main house (§ 28.86.035).
Special units are the smaller ones, and they buy you things the standard track will not. A new detached special unit is capped at 800 square feet and 18 feet in height at one story, plus two more feet if that is what it takes to match the main house's roof pitch. In return, the special track is what lets you put a unit on a lot in a Fire Hazard Area, and what lets you have more than one unit (§ 28.86.090).
On a single-house lot, the special track allows one junior unit inside the house plus one newly built or converted special unit — two rentals where the standard track allows one. On a lot that already has two or more homes on it, it allows up to two converted units, or 25% of the existing number of units, whichever is greater.
One catch worth reading twice: you cannot cherry-pick. The special standards section says applications using it "may not utilize the less restrictive configuration, size, and height standards allowed under another section to achieve a larger unit or more than one unit." Pick a track and stay on it.
There is one more height wrinkle on the special track. On a lot in the Foothill or Extreme Foothill High Fire Hazard Areas that is not within half a mile's walk of a major transit stop, the detached special unit drops to 16 feet and one story.
Setbacks, spacing, and the yard you still have to keep
For a newly built standard unit, the interior setback — the gap to your side and rear property lines — is four feet. The front setback is whatever your zone requires for houses.
Converting existing space is treated very differently. If you are turning legally permitted floor area in the house or in an accessory building into a unit, no setback is required at all. The same holds if an old building is demolished and rebuilt in the same footprint with the same dimensions and floor area, and you are allowed one small 150-square-foot first-floor addition on a rebuilt nonconforming accessory building.
A detached unit has to sit at least five feet from the main house.
Open yard is the rule most people trip over. The unit itself needs no open yard of its own. But a new standard unit that eats into the yard the main house is required to keep has to leave a minimum behind: 500 square feet on lots under 6,000 square feet, 800 on lots of 6,000 to 7,999, 1,000 on lots of 8,000 to 9,999, and 1,250 on lots of 10,000 square feet or more — at least 15 feet long and 15 feet wide (§ 28.86.055).
There is also a safe harbor buried in the same section. An 800-square-foot attached or detached standard unit with four-foot interior setbacks can be built regardless of limits on lot coverage, floor area ratio, open space, front setback, minimum lot size, or any cap based on a percentage of the main house. That mirrors the state's floor: California forbids a city from writing a rule that blocks an 800-square-foot unit with four-foot side and rear setbacks (§ 66321).
Keep that direction straight. When the state says a city may not cap units below 850 square feet, that is a limit on the city, not a ceiling on you. Santa Barbara's 1,000 and 1,200 square foot allowances sit above the state floor, and the state has nothing to say about them.
The coastal permit most guides skip
Santa Barbara's coastal overlay zone covers "generally all of the land 1,000 yards from the mean high tide line" inside the city, including the airport and Goleta (§ 28.44.020). That is a wide band, and a lot of ordinary residential streets are inside it.
The good news is that the city wrote accessory dwelling units their own lane. When the project is a detached unit added to an existing single-family home — or any unit on a lot that already has two or more homes or a mixed-use building — the coastal development permit goes to a Staff Hearing Officer:
the application shall be reviewed by the Staff Hearing Officer without a public hearing in accordance with Government Code Section 65852.2
No public hearing, no neighbors at a podium. The officer cannot decide for at least 10 calendar days after notice goes out, can read written comments, and their decision is the city's final word. In the appealable area — the strip closest to the water — that decision can still be appealed to the California Coastal Commission (§ 28.44.110).
So the coastal permit is a real step with a real calendar, not a veto. Budget the time.
Historic properties get their own gate
Santa Barbara will not permit a unit if it "would cause a substantial adverse change in the significance of a historical resource" — a property on the National Register or the California Register, a City Landmark or Structure of Merit, or anything inside a designated historic district. The Community Development Director makes that call against the Secretary of the Interior's Standards (§ 28.86.070).
This is not the city freelancing. State law tells cities their objective standards must include ones "that prevent adverse impacts on any real property that is listed in the California Register of Historical Resources" (§ 66314).
What every unit has to contain
Whichever track you take, the unit needs its own kitchen with a sink, cooking appliances and refrigeration; its own bathroom with a toilet, sink and tub or shower; a separate living room; and a separate sleeping room unless it is a studio. It needs independent exterior access — one lockable door through to the main house is allowed — and a permanent foundation (§ 28.86.050).
A junior unit is the lighter version: up to 500 square feet, entirely inside the existing floor area of the house or an attached garage, allowed to share the house's bathroom, and allowed an efficiency kitchen — cooking and refrigeration appliances, a food prep counter, and a sink larger than 12 by 12 inches (§ 28.86.020).
And the one that saves projects: fire sprinklers are required only if they are required for the main house, and building the unit does not trigger sprinklers in an existing house that does not have them.
What the permit counter will ask for
Two Santa Barbara-specific steps catch people out. Within five calendar days of filing your application you have to post a public notice sign on the property, and it stays up until the building permit issues or the application dies. And before the building permit is issued you have to record an agreement against the deed covering the sale, rental and owner-occupancy rules (§ 28.86.100).
If you are building the main house at the same time, the unit's permit waits: approval is held until the primary home's permit is approved and issued, and the unit cannot get its final inspection before the house does.
One thing this post does not give you is a single height number for a standard unit, or the parking rule. Santa Barbara sets those through the standards that apply to accessory buildings in your base zone rather than as one citywide figure, so ask Community Development for the number attached to your zone before anyone draws a roof. For the rest of the local picture, the Santa Barbara city page and the Santa Barbara ADU guide are the places to start.
A last practical note from state law: you may rent the unit out separately, but you cannot sell it separately from the main house (§ 66314).
Sources
- Santa Barbara Municipal Code § 28.86.055 — Development Standards for Standard Accessory Dwelling Units
- Santa Barbara Municipal Code § 28.86.090 — Development Standards for Special Accessory Dwelling Units
- Santa Barbara Municipal Code § 28.86.035 — Unit Configuration
- Santa Barbara Municipal Code § 28.86.050 — Required Features
- Santa Barbara Municipal Code § 28.86.020 — Definitions
- Santa Barbara Municipal Code § 28.86.070 — Protection for Historic Resources
- Santa Barbara Municipal Code § 28.86.100 — Permits and Processing
- Santa Barbara Municipal Code § 28.44.020 — Coastal Overlay Zone Location
- Santa Barbara Municipal Code § 28.44.110 — Authority to Review Coastal Development Permits
- California Government Code § 66314 — Local Accessory Dwelling Unit Ordinances
- California Government Code § 66321 — State Size and Height Floors
- California Government Code § 66323 — Ministerial Approval
