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What are Santa Clarita's ADU rules?

As of October 2026, the City of Santa Clarita permits ADUs on the state baseline: on a single-family lot, one detached unit of up to 800 sq ft with 4-foot side and rear setbacks and a 16-foot height limit, with no parking required and a $425 Planning Division fee 127. The first question, though, is whether your house is in the city at all. Stevenson Ranch and Castaic are unincorporated Los Angeles County, so the county, not the city, writes their ADU rules 202124.

Edited by Ryan Rambo, construction managerFacts checked 2026-10-13

Is my house actually inside the City of Santa Clarita?

Do not trust the city name on your mail. A "Santa Clarita" or "Valencia" mailing address proves nothing. Stevenson Ranch, west of Interstate 5, is an unincorporated community in Los Angeles County that the city has tried and failed to annex 20. Castaic, to the northwest, is also unincorporated 21. The line moves, too: parts of Sand Canyon were not annexed into the city until 2012 and 2013 22.

Two free lookups settle it:

  1. The city's own interactive map. Search by address and look for the field labeled "Jurisdiction"; it reads CITY or COUNTY 23.
  2. LA County's Z-NET. The county's zoning map says to use it to verify the jurisdiction, and it has no zoning data for incorporated cities, which are masked out in white 24. Enter an address or the 10-digit Assessor's parcel number without dashes, and the zoning for the property comes back below the search box 25.

If both tools say CITY, the rest of this guide applies and your permit goes to the city's Planning Division and Building & Safety at 23920 Valencia Boulevard 18. If they say COUNTY, skip to the last section.

How big and how tall can an ADU be in Santa Clarita?

The city's March 2026 ADU handout sets out three types for single-family lots, all under Government Code Section 66323 6:

You may have each type on one property, and every unit needs its own exterior door 5.

These are the state's protected minimums, and the city's handout does not describe a larger local ADU. In March 2023 HCD, the state housing department, found that the city's 2021 ordinance did not comply with state ADU law on parking exemptions, a tree-planting requirement and the zones where ADUs were allowed 12. The City Council adopted amendments to the ADU ordinance on April 28, 2026 1011. If you want a unit larger than 800 sq ft, ask the Planning Division in writing what the amended code allows before anyone draws plans.

The city also cannot set a minimum lot size for an ADU 18, and once your application is complete it has 60 days to approve or deny it or it is deemed approved 16. See our JADU vs ADU guide and setbacks guide.

Do I need to add parking, and can I rent the unit out?

No parking, and yes to renting. The city's handout says flatly that there are no parking requirements for ADUs or JADUs 2. State law backs that up: a city may not require you to replace off-street parking when a garage, carport or even an uncovered space is demolished or converted for an ADU 14.

On renting and selling, the handout says an ADU may be rented separately from the main house but may not be sold or conveyed separately, and it cannot be rented for less than 30 days 3. The state bars cities from requiring owner occupancy for an ADU, except one sold separately to a qualified buyer under a special program 15. A junior ADU is different. If it shares a bathroom with the main house, either the house or the JADU must be owner-occupied 3. Our owner-occupancy guide covers the state rule in detail.

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What does Santa Clarita charge for an ADU?

The city's own planning fee is small. The Planning Division fee schedule effective August 24, 2026 lists "Accessory Dwelling Unit (ADU) $425", and the schedule notes that all fees are updated annually 7. Building & Safety permit and plan-check fees come on top.

The larger list is the other agencies. The Building & Safety ADU handout lists the clearances a permit can need: city Planning, Engineering and Environmental Services, Address Assignment, Traffic & Transportation (detached units), the County Fire Prevention Bureau, the William S. Hart and elementary school districts, and the County Sanitation Districts, or County Health Services on septic. Some of them charge fees, and the handout says to ask before preparing plans 8.

State law caps the biggest of those charges. An ADU of 750 sq ft of interior livable space or less is exempt from impact fees from local agencies, special districts and water corporations; above 750 sq ft, impact fees must be charged in proportion to the ADU's size against the main house 13. Utilities also may not treat an ADU as a new residential use when they calculate connection fees or capacity charges for water and sewer, unless you are building it together with a new house 19. An 800 sq ft detached unit can therefore owe proportional impact fees that a 750 sq ft one does not.

What will Santa Clarita's plan check ask for?

The Building & Safety handout is the checklist. Clearance from the Planning Division is required before Building & Safety will review any plans, so the $425 planning step comes first 8. Every ADU gets its own new address from Building & Safety 9. New detached ADUs must include solar, and it has to appear on the energy forms 9. A geotechnical report is required for any new building or addition over 1,000 sq ft of total proposed floor area, or where geotechnical hazards are known 9.

On fire sprinklers, the handout says that if the main residence has a sprinkler system the ADU must have one too, or as LA County Fire Prevention requires 9. State law sets the floor the other way: sprinklers cannot be required in an ADU or JADU if the existing main house was not required to have them 17. Projects in a fire zone or flood zone may be asked for more information and face extra construction requirements 9. Our fire sprinklers guide and fire zone guide explain what that means for the building itself, even though they are written for the City of Los Angeles.

My house is in Stevenson Ranch or Castaic. Whose rules apply?

Los Angeles County's. Unincorporated parcels are permitted by the county Department of Regional Planning, whose ADU page says the county is updating its ADU ordinance as state housing law evolves 26. Treat the draft with care: the county's 2026 ADU Ordinance Amendment page says the materials are a proposed draft with no hearing dates scheduled and no force of law, so existing county and state regulations still govern 27.

The county's 2024 FAQ describes the floor. On a single-family property the statewide exempt units are one ADU converted from existing or proposed space, one JADU and one detached ADU of up to 800 sq ft, and these must be approved without local development standards 28. In a Very High Fire Hazard Severity Zone, local ADU rules apply if the property meets fire access requirements; if it does not, only the statewide exempt ADUs are allowed 28. When a garage or carport is demolished or made unusable by ADU construction, no replacement parking is required, and ADUs and JADUs must be rented for at least 30 days at a time 28.

The 750 sq ft impact-fee exemption, the 60-day clock and the ban on owner-occupancy requirements are state law and apply on both sides of the line 131615.

Quick answers

How big can a detached ADU be in Santa Clarita?

The city's 2026 handout lists a detached ADU at 800 sq ft with 4-foot side and rear setbacks and a 16-foot height limit, rising to 18 feet to the top plate within half a mile of a transit stop 1.

Does Santa Clarita require parking for an ADU?

No. The city's handout says there are no parking requirements for ADUs or JADUs 2.

What is the city's ADU planning fee?

The Planning Division fee schedule effective August 24, 2026 lists the ADU fee at $425, and fees are updated annually 7.

Is Stevenson Ranch part of the City of Santa Clarita?

No. Stevenson Ranch is an unincorporated community in Los Angeles County, and the city's attempts to annex it have not succeeded 20. Castaic is unincorporated as well 21.

How do I check whether my address is city or county?

Search the city's interactive map by address and read the Jurisdiction field, which says CITY or COUNTY 23, or search LA County's Z-NET, where incorporated cities are masked out in white 24.

Sources

  1. Accessory Dwelling Unit (ADU) for Single-Family Homes FAQs (March 2026), development standards table: Detached, City of Santa Clarita Planning Division. Facts checked 2026-10-13
  2. Accessory Dwelling Unit (ADU) for Single-Family Homes FAQs (March 2026), parking, City of Santa Clarita Planning Division. Facts checked 2026-10-13
  3. Accessory Dwelling Unit (ADU) for Single-Family Homes FAQs (March 2026), renting and selling, City of Santa Clarita Planning Division. Facts checked 2026-10-13
  4. Accessory Dwelling Unit (ADU) for Single-Family Homes FAQs (March 2026), JADU definition, City of Santa Clarita Planning Division. Facts checked 2026-10-13
  5. Accessory Dwelling Unit (ADU) for Single-Family Homes FAQs (March 2026), expansion, number of units, exterior access, City of Santa Clarita Planning Division. Facts checked 2026-10-13
  6. Accessory Dwelling Unit (ADU) for Single-Family Homes FAQs (March 2026), development standards table: Conversion, City of Santa Clarita Planning Division. Facts checked 2026-10-13
  7. Planning Division Fee Schedule, effective August 24, 2026, City of Santa Clarita Community Development, Planning Division. Facts checked 2026-10-13
  8. ADU/JADU Building Plan Requirements, Planning clearance and Agency Clearance Requirements, City of Santa Clarita Building & Safety Division. Facts checked 2026-10-13
  9. ADU/JADU Building Plan Requirements, addresses, solar, geotechnical, fire sprinklers, fire and flood zones, City of Santa Clarita Building & Safety Division. Facts checked 2026-10-13
  10. Council Recap: April 28, 2026, City of Santa Clarita. Facts checked 2026-10-13
  11. 2026 Accessory Dwelling Unit Ordinance and Housing Law Updates, Notice of Exemption (SCH 2026041415, posted April 30, 2026), City of Santa Clarita via CEQAnet (Governor's Office of Land Use and Climate Innovation). Facts checked 2026-10-13
  12. Review of Santa Clarita's Accessory Dwelling Unit (ADU) Ordinance under State ADU Law, letter of March 24, 2023, California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  13. Accessory Dwelling Unit Handbook (March 2026), Fees: impact fees for ADUs of 750 square feet or less, California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  14. Accessory Dwelling Unit Handbook (March 2026), Parking: exemptions and replacement parking, California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  15. Accessory Dwelling Unit Handbook (March 2026), Owner-Occupancy, California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  16. Accessory Dwelling Unit Handbook (March 2026), Summary of Recent Changes: 60-day deemed approval, California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  17. Accessory Dwelling Unit Handbook (March 2026), Fire Protection and Fire Sprinkler Requirements, California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  18. Accessory Dwelling Unit Handbook (March 2026), Lot size, California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  19. Accessory Dwelling Unit Handbook (March 2026), Fees: utility connection fees and capacity charges, California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  20. Stevenson Ranch, California, Wikipedia (secondary; community status). Facts checked 2026-10-13
  21. Castaic, California, Wikipedia (secondary; community status). Facts checked 2026-10-13
  22. Sand Canyon, Santa Clarita, California, Wikipedia (secondary; annexation history). Facts checked 2026-10-13
  23. Maps & Jurisdictions: Interactive Santa Clarita Map, Film Santa Clarita (City of Santa Clarita). Facts checked 2026-10-13
  24. Z-NET: Find Your Zoning and Verify Jurisdiction, Los Angeles County Department of Regional Planning. Facts checked 2026-10-13
  25. Z-NET User Guide (April 2025), Search, Los Angeles County Department of Regional Planning. Facts checked 2026-10-13
  26. Accessory Dwelling Units (ADU), Los Angeles County Department of Regional Planning. Facts checked 2026-10-13
  27. 2026 ADU Ordinance Amendment, Draft Evaluation Phase (updated July 2026), Los Angeles County Department of Regional Planning. Facts checked 2026-10-13
  28. ADU Ordinance Amendment: Frequently Asked Questions (February 2024), Los Angeles County Department of Regional Planning. Facts checked 2026-10-13

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Greenlight is not a contractor, architect or engineer, and this is not legal advice. Rules change; every fact here shows the date we last checked it.