ADU Rules in Santa Clarita (2026): What You Can Build

An accessory dwelling unit (ADU) is a second, self-contained home with its own kitchen, bathroom and entrance on a lot that already has a house. The City of Santa Clarita permits ADUs and junior ADUs under state ADU law (Government Code 66310–66342) and its own ordinance, Unified Development Code Section 17.57.040, revised on April 28, 2026 after the state found the earlier version out of compliance. Green Design and Build is a licensed general contractor (CSLB #1110975) serving homeowners across Los Angeles County, Orange County, Ventura County, western Riverside County and western San Bernardino County. The headline fact: state law requires Santa Clarita to approve a detached ADU of up to 800 sq ft with 4-foot side and rear setbacks on any single-family lot, and the city’s own standard allows 850 sq ft for a studio or one bedroom and 1,000 sq ft for two bedrooms.

This page covers Valencia, Saugus, Canyon Country and Newhall, inside the city; Stevenson Ranch, Castaic and Val Verde are unincorporated Los Angeles County and follow the county’s ordinance. See our ADU rules by city for other jurisdictions.

Who we are

Green Design and Build is led by Dekel Sofer. We hold a 4.7-star rating across 146 Yelp reviews and have completed hundreds of projects. We are a full-service residential general contractor, not an ADU specialist: ADUs and garage conversions are one part of what we build in Santa Clarita, alongside kitchens, bathrooms, additions and whole-home renovations.

ADU rules in Santa Clarita at a glance

Rule	City of Santa Clarita (2026)
Detached ADU, max size	850 sq ft (studio or one bedroom) or 1,000 sq ft (two or more bedrooms) under the city standard; an 800 sq ft unit cannot be denied under state law
Attached ADU, max size	Same by bedroom count, and no more than 50% of the main house; the 50% rule cannot block an 800 sq ft unit
Junior ADU (JADU)	Up to 500 sq ft inside the existing house, own entrance and cooking area; one per lot
Height	Detached: 16 ft, or 18 ft plus up to 2 ft of roof pitch within half a mile of major transit. Attached: 25 ft or the main house’s zoning height, whichever is lower, two stories max
Setbacks	4 ft side and rear for new units; none for a conversion, which may add up to 150 sq ft to a converted accessory structure for entry and exit
Parking	None for a conversion, a JADU or an 800 sq ft state-standard ADU. One space may be required for a larger city-standard unit unless a state exemption applies (within half a mile of transit, and others). Garage parking lost to a conversion is not replaced
Owner-occupancy	Not required for an ADU. Required for a JADU that shares a bathroom with the main house, by deed restriction
Units on a single-family lot	One conversion ADU, one detached ADU of up to 800 sq ft and one JADU, in any combination
Short-term rental	Not allowed; rentals must be 30 days or longer
Impact fees	None under 750 sq ft; proportional above. The city’s Bridge and Thoroughfare fee starts at 750 sq ft
Review timeline	Ministerial; complete or incomplete within 15 business days; approved or denied within 60 days of a complete application
Where to apply	Planning Division review, then Building & Safety plan check, at the Permit Center, 23920 Valencia Blvd, Suite 140, Santa Clarita, CA 91355, (661) 259-2489, via the city’s Accela online portal

Stevenson Ranch, Castaic and Val Verde apply to Los Angeles County Public Works, Santa Clarita Valley Building and Safety office, 23757 Valencia Blvd, Valencia, CA 91355, (661) 222-2940, through the county’s EPIC-LA portal. The state floor is the same; the county’s local standards differ (see our Los Angeles County page).

Size, height and setbacks

Santa Clarita has two layers of ADU rules. The state layer, Government Code 66323, guarantees a detached ADU of up to 800 sq ft with 4-foot side and rear setbacks and at least 16 feet of height, free of the city’s design, lot-coverage, open-space and parking standards. The city layer allows 850 or 1,000 sq ft by bedroom count, with the city’s standards attached. The city’s handout also calls for a 6-foot separation between a detached ADU and the house; state law says a separation rule cannot prevent an 800 sq ft unit with 4-foot setbacks, and the state flagged the city’s rule in 2023, so ask Planning how it is applied before fixing the footprint.

Three local conditions come up. Hillside lots in Saugus, Canyon Country and Placerita Canyon usually need a geotechnical report and an engineered foundation. Protected oaks are routed through the city’s Urban Forestry division on every ADU plan; the city has acknowledged that state law does not let it deny a compliant ADU because of an oak, so design around the protected zone where you can. The city’s 2023 handout required an ADU in a High Fire Hazard Severity Zone to front a highway or have two separate ways out; the state rejected that restriction and the April 2026 ordinance was adopted to comply, so confirm the current standard with Planning. County Fire stamps every ADU plan, and fire-zone construction uses Chapter 7A materials.

Garage conversions and JADUs in Santa Clarita

A garage conversion is the least expensive ADU on most Santa Clarita tract lots because the slab, roof and walls exist. The city must approve a conversion of an attached garage, or of existing space in the house, with no new setback, no parking and no replacement of the parking lost; a detached garage can be converted the same way and enlarged by up to 150 sq ft for entry and exit. Fire sprinklers follow the main house: if the house does not need them, the ADU does not, and the ADU cannot trigger sprinklers in the house. An attached unit needs a one-hour fire-rated separation. Our garage conversion page covers the construction side.

A junior ADU is up to 500 sq ft carved out of the existing house, typically a bedroom and bath, with its own exterior entrance and cooking area. If it shares a bathroom with the main house, the owner must live in either unit and record a deed restriction. A JADU needs no parking, and state law allows one conversion ADU, one detached ADU and one JADU on the same lot.

Pre-approved plans, fees and utilities

State law required every city to set up an ADU plan pre-approval program by January 1, 2025, but as of September 2026 we could not find a published pre-approved plan gallery on the city’s website, so ask the Planning Division. Unincorporated Santa Clarita Valley can use Los Angeles County’s Standard ADU Plans Program; see our page on ADU standard plans in Los Angeles.

Neither the city nor we publish an all-in ADU fee. Per the city’s January 2026 residential agency referral list, a Santa Clarita ADU runs through: plan check and permit fees; the Bridge and Thoroughfare fee for ADUs of 750 sq ft and larger; William S. Hart Union High School District fees for any detached ADU (state law exempts units of 500 sq ft or less); a Sanitation Districts of Los Angeles County sewer connection fee; a Santa Clarita Valley Water certificate for a new service; and a County Fire stamp. Development impact fees are waived under 750 sq ft. A new detached ADU also needs solar under Title 24; a conversion does not.

Government Code 66324 bars the city and the water agency from requiring a new or separate utility connection, or a connection fee, for a conversion ADU or JADU; a new detached unit may need a separate connection with a fee proportional to its size. A separate electric meter is optional; a subpanel is standard, and a 100-amp panel usually becomes a 200-amp Southern California Edison service upgrade, performed by licensed electricians and scheduled and supervised by us as your general contractor.

The permit process in Santa Clarita, step by step

1. Confirm the jurisdiction and the lot. We check the parcel for city versus county, zoning, fire zone, slope and oaks, and submit any HOA architectural package first so the permit set matches what the association approved.
2. Design to the right standard. An 800 sq ft state-standard unit, a larger city-standard unit or a conversion; the choice sets which rules the city may apply.
3. Planning Division review. Every ADU and JADU is reviewed by Planning before Building & Safety opens plan check, including any oak-tree clearance.
4. Building & Safety plan check. Plans, structural calculations and Title 24 forms go through the Accela portal; the city has 15 business days to declare the application complete and 60 days from a complete application to decide.
5. Agency clearances. Hart School District, Sanitation Districts, SCV Water, County Fire and an SCE will-serve letter for a new meter, before the permit issues.
6. Construction and inspections. Foundation, framing, rough trades, insulation, drywall and final.
7. Certificate of Occupancy. Issued after final inspection; only then can the unit be rented.

End to end, a Santa Clarita ADU takes six months to a year; a garage conversion sits at the short end, a hillside detached unit at the long end.

What an ADU costs in Santa Clarita

Our published figures apply across our service area: a garage conversion ADU typically runs $100,000–$200,000; a detached 500 sq ft ADU $180,000–$260,000; a 700–800 sq ft unit $225,000–$350,000; and a 1,000 sq ft unit $300,000–$450,000 or more, or $300–$450 per sq ft all-in and $500 or more per sq ft on difficult lots. In Santa Clarita the drivers that push a project toward the top of a range are a sloped lot needing an engineered foundation, oak protection that forces a longer utility run, Chapter 7A fire-zone construction, a 200-amp service upgrade and HOA conditions. Our guide to how much it costs to build an ADU walks through a real project, and our ADU rules calculator shows the state-law floor for your lot.

Frequently asked questions

How big can an ADU be in Santa Clarita?

In the City of Santa Clarita an ADU can be up to 850 sq ft for a studio or one bedroom and 1,000 sq ft for two or more bedrooms. State law separately requires the city to approve a detached ADU of up to 800 sq ft with 4-foot side and rear setbacks on any single-family lot. A junior ADU is capped at 500 sq ft.

Do I need a parking space for an ADU in Santa Clarita?

Not for most Santa Clarita ADUs. State law prohibits any parking requirement for a conversion, a JADU or an 800 sq ft state-standard detached ADU, and garage spaces lost in a conversion are not replaced. For a larger city-standard unit the city may require one space unless a state exemption applies, such as being within half a mile of transit.

Does Santa Clarita require the owner to live on the property?

No for an ADU: state law bars Santa Clarita from imposing an owner-occupancy requirement, and the state directed the city in December 2025 to remove that language from its ordinance. A junior ADU that shares a bathroom with the main house is the exception; the owner must live in one of the units. Either unit may be rented for 30 days or longer, but not as a short-term rental.

How long does a Santa Clarita ADU permit take?

Santa Clarita must review an ADU application ministerially, confirm within 15 business days whether it is complete, and approve or deny a complete application within 60 days. Plan-check corrections and agency clearances add time on top of that clock, inside an overall project of six months to a year.

Are the ADU rules different in Stevenson Ranch or Castaic?

Yes. Stevenson Ranch, Castaic and Val Verde are unincorporated Los Angeles County, so an ADU there is permitted by Los Angeles County Public Works from its Santa Clarita Valley office at 23757 Valencia Blvd, through the EPIC-LA portal, under the county’s ADU ordinance. The state floor is the same, but the county’s larger-unit standards, fire-zone parking rule and pre-approved plans are its own.

Can I build an ADU on a Santa Clarita lot with protected oak trees or in a fire zone?

Generally yes. Santa Clarita’s Urban Forestry division reviews every ADU plan for oak impacts, but the city has stated that state law does not let it deny a compliant ADU on oak-tree grounds, so site the unit outside the protected zones. In a High Fire Hazard Severity Zone, County Fire reviews the plans and Chapter 7A materials apply; the road-access rule in the city’s 2023 handout was rejected by the state and the ordinance was revised in April 2026, so confirm the current standard with Planning.

Find out what your Santa Clarita lot allows before you draw anything

Send us your address and we will confirm city or county jurisdiction, the fire-zone, oak and slope conditions on the parcel, and which ADU standard fits your lot, then give you a written, itemized estimate. No cost, no obligation.