ADU Builder in Santa Clarita, CA: Permits, Costs and Local Rules

What does the Santa Clarita ADU handout say?

The city's March 2026 ADU handout explains the city's planning guide for ADUs and JADUs. State law caps a detached ADU at 1,200 square feet and does not let a city set a maximum below 850 square feet (1,000 for two or more bedrooms); the city's handout lists 4 foot side and rear setbacks and a 16 foot height limit for a detached new build. Within a half mile of a transit stop, the height rises to 18 feet to the top plate with an additional two feet for a minimum roof pitch. A Junior ADU is allowed up to 500 square feet inside the home. Setbacks for a converted ADU follow the same setbacks for the main home. There are no parking requirements for ADUs or JADUs under the city's handout.

How does the Santa Clarita ADU permit process work?

The Planning Division reviews ADUs and JADUs under a Class I ministerial application before Building and Safety begins plan check. State law requires the city to determine completeness within 15 business days and to approve or deny a complete application within 60 days, with the application deemed approved if the deadline is missed, per Gov. Code 66317. The city's ADU Plan Requirements handout lists the agencies that must clear an ADU before the building permit issues, including Planning, Engineering Services and Environmental Services for new structures, Address Assignment, Traffic and Transportation Planning for detached ADUs, the County of Los Angeles Fire Prevention Bureau, the William S. Hart High School and Elementary School Districts, and the Sanitation Districts of Los Angeles County. A geotechnical report is required for new buildings or additions over 1,000 square feet or where geotechnical hazards are known.

What fees does a Santa Clarita ADU pay?

The Planning Division processes ADU applications before Building and Safety opens plan check, and the city's Planning and Building fee brochures published on santaclarita.gov set the line item amounts. School district developer fees are billed by the William S. Hart High School District and the William S. Hart Elementary School District. Under Gov. Code 66311.5, an ADU of 750 square feet or less is exempt from city impact fees, and any impact fee on an ADU over 750 square feet is charged proportionally to the square footage of the primary dwelling. L Square collects the live fee amounts for your address from the city's current brochures before submittal.

How much does an ADU cost in Santa Clarita?

L Square publishes configured model prices on the cost guide page: $180,000 for Model 600, $240,000 for Models 800A and 800B, $295,000 for Models 1000A and 1000B, and $354,000 for Model 1200. These are model prices, not a final total for your lot. Santa Clarita lots often sit on slopes, and a longer sewer or water run, a new electrical service, fire sprinkler work to match an existing sprinklered main home, and the city's planning, building permit and school district fees are priced after a site review. A garage conversion or a Junior ADU inside the house is priced from a property specific scope.

What should you confirm before building in Santa Clarita?

Check three things before drawings are final. First, ask the Planning Division whether your lot falls inside the city's high fire hazard severity zone or a flood zone, because geotechnical and fire requirements change the scope and the geotechnical report is required for new buildings over 1,000 square feet. Second, confirm which school district serves the lot, since the developer fee line item is billed to the school district listed for your address. Third, confirm whether the ADU will share sanitation with the main home, because a Junior ADU that shares bathrooms triggers the owner occupancy rule and a deed restriction recorded with the city.

Official Santa Clarita ADU sources

• The Santa Clarita March 2026 ADU handout lists 800 square feet as the detached new build size the city must allow with 4 foot side and rear setbacks and a 16 foot height limit; within half a mile of a transit stop the height rises to 18 feet to the top plate plus an additional two feet for a minimum roof pitch; a Junior ADU is allowed up to 500 square feet inside the home; and there are no parking requirements for ADUs or JADUs. Official source
• The Santa Clarita ADU Plan Requirements handout lists Planning, Engineering Services and Environmental Services for new structures, Address Assignment, Traffic and Transportation Planning for detached ADUs, the County of Los Angeles Fire Prevention Bureau, the William S. Hart High School and Elementary School Districts, and the Sanitation Districts of Los Angeles County as the agencies that must clear an ADU before the building permit issues, and requires a geotechnical report for new buildings or additions over 1,000 square feet or where geotechnical hazards are known. Official source
• A permitting agency must approve or deny a complete ADU application within 60 days, and the application is deemed approved if the deadline is missed, under California Government Code Section 66317. Official source
• A local agency shall not impose any impact fee upon an ADU of 750 square feet of interior livable space or less, and any impact fee on a larger ADU is charged proportionally to the primary dwelling square footage, under California Government Code Section 66311.5. Official source
• The detached ADU ceiling under California Government Code Section 66314(d)(5) is 1,200 square feet, and an ADU converted from an existing structure is exempt from replacement parking under subdivision (d)(11). Official source
• A Junior ADU that shares sanitation with the main residence requires the owner to occupy either the main home or the Junior ADU, and a deed restriction is recorded with the city, under California Government Code Section 66333. Official source