Building an ADU in Santa Cruz

What you can build in Santa Cruz

ADUs are allowed on lots of any size in any zone that allows homes, as long as there is a home on the lot or one is being built with the ADU. The rules are in Santa Cruz Municipal Code Chapter 24.16, Part 2, last amended in 2026, and the Planning Department summarizes them on its ADU page. The code says that if state law changes and conflicts with it, state law wins.

Santa Cruz sorts ADUs into two groups:

• Statewide exemption ADUs follow only basic state standards for size, setbacks and height. They include a new detached ADU of up to 800 sq ft with 4-foot side and rear setbacks, and a conversion of space inside the house or an existing accessory building.
• Non-exempt ADUs are anything else, such as a larger detached unit or an addition to the house. They must meet the city's own site and design standards.

Single-family lots (including townhomes and detached units on a shared lot) can have one statewide exemption detached ADU, one statewide exemption conversion ADU, one non-exempt ADU and one junior ADU.

Multifamily lots. With an existing building of two or more attached units, you can add as many statewide exemption detached ADUs as there are existing units, up to eight. You can also convert non-living space such as storage rooms or garages into ADUs: at least one, and up to 25% of the existing units. A lot with a proposed multifamily building can have up to two detached ADUs. Non-exempt ADUs aren't allowed on multifamily lots.

In February 2024, state housing agency HCD found that the city's 2022 ADU ordinance did not comply with state law. HCD objected to slope permit and discretionary review steps, exceptions to the 60-day timeline, and historic and creek rules. HCD's findings letter is public. The city has amended the chapter since (ordinances in 2024, 2025 and 2026). HCD's letter said state law allows extra historic standards only for properties listed in the California Register of Historical Resources. The current city code still requires a historic consultant's report for a non-exempt ADU on a property listed by the city, the state or the National Register. If your property is historic, ask Planning how this applies. Statewide rules are on our California page. [1][2][3]

Size, height and setbacks

These limits apply to non-exempt ADUs. A statewide exemption detached ADU instead can be up to 800 sq ft and 16 feet tall (18 feet within a half mile walk of a major transit stop or high-quality transit corridor, plus 2 feet to match the main roof pitch), with 4-foot side and rear setbacks.

Detached ADUs

• Size: the greatest of 850 sq ft (studio or one bedroom), 1,000 sq ft (two or more bedrooms), or 10% of the net lot area up to 1,200 sq ft, measured as interior livable space.
• Height: 16 feet to the roof peak if it is less than 4 feet from a side or rear line; 22 feet if it is 4 feet or more away.
• Setbacks: 3 feet from interior side and rear lines up to 16 feet tall, 4 feet for any part above 16 feet. The front setback is the lesser of the main house's front wall line or the zone's setback. Buildings must be at least 6 feet apart.

Attached ADUs can be the greatest of 850 sq ft, 1,000 sq ft (two or more bedrooms) or 50% of the home's habitable area. They follow the zone's height and front setback for the house, with 4-foot interior side and rear setbacks.

Conversions can be any size that fits the existing building, plus up to 150 sq ft of footprint and 2 feet of height.

If normal zoning rules would leave no room for an 800 sq ft ADU with 4-foot side and rear setbacks, you can waive the lot coverage, floor area ratio, open space, front setback and percent-of-house limits as far as needed. Other limits apply near natural features: no ADU within 20 feet of a 30% or steeper slope, minimum distances from heritage and street trees, and biologist reports near wetlands or sensitive habitat.

Where an ADU doesn't meet the zone's normal setbacks, entrances, stairs and upper decks must face into the lot (or toward an alley or street), and windows facing a neighbor must be obscured or screened. [1][2]

Parking and the coastal zone

Outside the Coastal Zone, no parking is required for any ADU, and you don't have to replace a garage or parking space you remove to build one.

Inside the Coastal Zone, one off-street space is required for an ADU close to the coast, in the area shown on the city's "ADU Parking Required" map layer in its GIS planning layers. Coastal parking and replacement rules vary by location, so the city asks you to consult a planner.

Some ADUs in the Coastal Appeal Zone need a Coastal Permit. It doesn't require a public hearing, but the city sends a notice of the application to nearby properties. Planning staff can tell you if your ADU can be exempt or excluded. [1][2]

Fees, utilities and fire sprinklers

Impact fees. State law bars impact fees on an ADU with 750 sq ft or less of interior livable space, and requires proportional fees above that. School fees are separate. The city's ADU page says ADUs under 750 sq ft fall below the threshold for school impact fees (around $3.15 per square foot). HCD's handbook says school districts may charge school fees on ADUs larger than 500 sq ft, so confirm with the city before you count on skipping them.

Permit fees. The city says conversions cost the least in permit fees and construction, and new free-standing ADUs cost the most. A conversion that is fully demolished and rebuilt is charged plan review and permit fees as new construction. Every ADU and junior ADU needs its own address, and the addressing fee is added to the building permit.

Water and sewer. Conversion ADUs and attached ADUs don't have to install separate water and sewer connections, but an ADU can outgrow the existing meter and trigger an upsize. New detached ADUs "will almost always trigger" new water and sewer connections and fees. The city suggests talking to the Water Department early.

Fire sprinklers. An ADU can't be required to have sprinklers when the main home doesn't. But if an attached ADU is larger than 50% of the home's existing habitable space, the addition may require sprinklers in the whole building. If you're near that size, the city suggests checking with the Fire Department first.

For typical costs, see our ADU cost guide. [1][2][4]

How the permit process works

All ADUs need a building permit, with architectural drawings, energy calculations, green building calculations and inspections. No public hearing or planning permit is required (except a Coastal Permit for some coastal ADUs). Building permits don't require public notice and can't be appealed.

The code sets the deadlines: the city must tell you within 15 business days whether your application is complete, and approve or deny a complete application within 60 days. The clock pauses if you ask for a delay, and the city can wait to act on an ADU filed together with a new house. If your application is found incomplete or denied, you can appeal in writing to the Planning Commission, and the city must give a final written decision within 60 business days.

Building permits are handled online through the Access Santa Cruz portal; see the city's Building & Safety page. New applications must follow the 2025 California Building Standards Code, in effect since January 1, 2026.

Pre-approved plans. Under state law (AB 1332), Santa Cruz offers a pre-approved ADU program for detached ADUs, with a 30-day review and lower permit costs. As of October 2026 the city says no plans are pre-approved yet. Plans approved by Santa Cruz or other California agencies under the current building code cycle are eligible. More on the process in our ADU permit guide. [1][2][5]

Garage conversions and junior ADUs

Garage conversions. Any legal garage, workshop or guest house can become a conversion ADU of any size. Legal means built with permits, or old enough to be legally nonconforming. You can expand it by up to 150 sq ft of footprint and 2 feet of height, and the expansion must meet new-construction setbacks. The building must meet current building code for a dwelling. A garage can even be fully rebuilt and still count as a conversion for zoning, but it is then reviewed and charged as new construction under the building code. See our garage conversion guide.

Junior ADUs. One junior ADU is allowed per lot with a single-unit home. It can be up to 500 sq ft of interior livable space inside the house, including an attached garage, or part of an addition or a new home. It needs its own outside entrance and a cooking area with appliances, a counter and cabinets. It can share a bathroom with the house through an inside door. Before the permit, you record a deed restriction: no separate sale, size limits, and rentals longer than 30 days only.

Owner occupancy for junior ADUs. The city code, as amended in 2026, requires the owner to live in the house or the junior ADU only when they share a bathroom. That matches state law since January 1, 2026. The city's ADU web page still says owners of any junior ADU must live on site, so confirm with Planning. See our junior ADU guide. [1][2][4]

Renting it out or selling it

You don't have to live on the property to build or keep an ADU. If you have an old owner-occupancy deed restriction, you can ask the Planning Department to remove it.

Short-term rentals. Neither an ADU nor the main home on its lot can be rented for 30 days or fewer. The code makes an exception for legal ADUs that were already short-term rentals before November 10, 2015 and keep paying transient occupancy tax. Single-family properties with ADUs can't join the city's short-term rental program. Some multifamily properties with ADUs may be eligible if the owner lives on site and the rental isn't in the ADU or its primary unit.

Selling an ADU. Since 2025, ADUs can be mapped as condominiums and sold separately. On a single-family lot, the house and each ADU can become separate condos. A junior ADU can't. Four or fewer condo units need a parcel map from Public Works; five or more need a tentative map from Planning and a final map from Public Works. Every lender with a lien on the property must consent before the map and condo plan are recorded. Condo ADUs must meet the city's inclusionary housing rules, and tenants get certain protections when existing units are converted. [1][2]

Legalizing an unpermitted ADU

If you have an ADU or junior ADU built without permits before January 1, 2020, the city can't deny a permit to legalize it for not meeting building code or ADU standards. It can deny the permit only if the unit is deemed substandard under the state Health and Safety Code.

To start, download the AB 2533 checklist from the city's Building & Safety page and submit it with a building permit application. The city's ADU legalization page explains that you can first get a confidential inspection from a licensed contractor. Impact fees and connection charges generally don't apply unless utility work is needed for safety. Questions about legalization go to (831) 420-5112. [1][2][6]

Permit steps in Santa Cruz

1. Check your lot

   Confirm your zoning, whether you're in the Coastal Zone, and the "ADU Parking Required" layer in the city's GIS planning layers, and read the ADU page. [1]

2. Talk to Planning

   Call the planning counter at (831) 420-5416 to confirm which ADU type you qualify for and whether you need a Coastal Permit. [1][5]

3. Prepare plans

   You need architectural drawings, energy calculations and green building calculations, plus an Addressing Request Form. For a pre-approved plan, add a site plan showing setbacks, existing structures and utility lines. [1][5]

4. Apply for a building permit

   Submit through the Access Santa Cruz online portal, linked from the Building & Safety page. Some coastal ADUs need a Coastal Permit as well. [1][5]

5. Completeness and review

   The city must tell you within 15 business days whether the application is complete, and approve or deny it within 60 days of a complete application. [2]

6. Record agreements

   For a junior ADU, record the deed restriction with the county before the building permit is issued. [2]

7. Build and pass inspections

   Building inspections follow the permit; the ADU gets its own address. [1]

Pre-approved and sample plans

• Pre-Approved ADU Program (AB 1332)

  A 30-day review and lower permit costs for detached ADUs using a pre-approved plan; the city says no plans are on its list yet. [5]

Who to call

• City of Santa Cruz Planning (ADU questions)

  General ADU questions and zoning; planningcounter@santacruzca.gov

  (831) 420-5416

  [1]

• City of Santa Cruz Building & Safety

  Building permits, plan review and inspections; permits@santacruzca.gov

  (831) 420-5110

  809 Center Street, Room 101, Santa Cruz, CA 95060

  [5]

• ADU legalization help

  Questions about legalizing an existing ADU or whether your ADU is legal

  (831) 420-5112

  [1][6]

Questions people ask