Building an ADU in Santa Clarita. Rules, costs, timeline.

What you can build in Santa Clarita

Santa Clarita’s ADU rules generally follow the California state floor, with three local elements that matter on the ground: the High Fire Hazard Severity Zone access rule, oak tree protection, and a 6-foot detached-to-primary separation standard. The dimensional caps themselves match what state law requires cities to allow.

Number of units allowed

Single-family lots — the state-law § 66323 stack. The City Planning Division’s ADU FAQ describes one ADU plus one JADU as the per-lot allowance. California state law and the HCD ADU Handbook are more generous. Under the § 66323 stack, an eligible single-family lot can typically combine all three of the following on the same parcel, regardless of any narrower local language:

• One conversion ADU — built inside an existing accessory structure or existing primary-dwelling space (Gov. Code § 66323(a)(1)).
• One Junior ADU (JADU) — up to 500 sqft inside the primary dwelling’s existing walls (Gov. Code § 66333).
• One new detached Statewide Exemption ADU — up to 800 sqft, 16 ft in height, with 4-ft side and rear setbacks (Gov. Code § 66323(a)(4) & (b)).

That is up to three units per lot under state law. The HCD ADU Handbook confirms this stack and treats it as the governing rule for any single-family lot, even when the local ordinance or handout still describes the older 1-ADU-plus-1-JADU framing. Santa Clarita’s ADU FAQ predates the current handbook position — state law preempts the narrower local language under Gov. Code § 66316. Before you formally submit your application, ask the Santa Clarita Planning Division to confirm in writing that the full three-unit § 66323 stack applies to your lot. Getting that confirmation up front protects the entitlement if questions come up later during plan check.

Multifamily lots. The local rule references SCMC § 17.57.040 subsection L for multifamily counts. California SB 1211 (effective January 1, 2025) raised the state-law floor to up to eight detached ADUs on a multifamily lot, not to exceed the number of existing primary units, plus a 25% conversion-ADU allowance inside the multifamily structure (Gov. Code § 66323(c)). The state floor preempts any narrower local cap.

Size limits

Per SCMC § 17.57.040 and the City Planning ADU FAQ:

• Detached ADU: up to 850 sqft for studios and 1-bedroom units, or 1,000 sqft for 2-bedroom units.
• Attached ADU: same 850/1,000 sqft caps, with an additional limit that the ADU shall not exceed 50% of the primary residence’s floor area.
• Junior ADU: up to 500 sqft, built entirely inside the primary residence’s existing or proposed walls (including an attached garage). Mirrors Gov. Code § 66313(d).
• Garage conversion: must be constructed within the existing permitted garage footprint.
• Statewide Exemption ADU floor: per Gov. Code § 66323, every eligible lot is entitled to at least one ADU of up to 800 sqft, 16 ft in height, with 4-ft side and rear setbacks, regardless of local development standards.

Setbacks

Per SCMC § 17.57.040 and the City Planning ADU FAQ:

• Side and rear setbacks: 4 feet — matches the state-law floor in Gov. Code § 66314(d)(7).
• Detached-to-primary separation: 6 feet between the detached ADU and the primary residence. This is a Santa Clarita-specific spacing rule that affects site planning on tighter lots; it is in addition to, not in place of, the 4-foot side and rear setbacks.
• Front setback: governed by the underlying base zone — Santa Clarita applies the prevailing front-yard setback of the residential zone to ADUs.
• Conversion: no additional setback required when the ADU is built inside the existing permitted garage footprint.

Maximum height

Per SCMC § 17.57.040 and the City Planning ADU FAQ:

• Detached ADU — default: 16 feet. Matches the state-law floor in Gov. Code § 66321(b)(4)(A).
• Detached ADU — transit-proximate exception: on lots within one-half mile walking distance of a public transit stop, the height may reach 18 ft to the top plate plus an additional 2 ft to accommodate a minimum 2:12 roof pitch (effective 20 ft). Matches Gov. Code § 66321(b)(4)(B).
• Attached ADU: up to 25 feet and 2 stories. Matches the state-law floor in Gov. Code § 66321(b)(4)(D) for attached ADUs.
• Garage conversion: within the existing garage footprint, no separate height increase.

What this means for design. Santa Clarita is effectively a 1-story detached-ADU market by default, with a clean 2-story path available for attached ADUs under the 25-foot envelope. Lots within one-half mile of a public transit stop can stretch a detached ADU to 20 ft — useful for a vaulted ceiling but still a 1-story envelope. The product story on most SCV lots is a well-designed 1-story detached unit.

Parking

Per SCMC § 17.57.040 and the City Planning Division’s ADU FAQ:

• Default rule: one off-street parking space per ADU.
• Five state-law exemptions (Gov. Code § 66322): no on-site parking required when the ADU meets any of the following:
  • Within one-half mile walking distance of public transit.
  • Contained entirely within the existing primary residence or an existing accessory structure.
  • Studio with no bedrooms (per the City Planning ADU FAQ).
  • On a lot subject to a residential permit parking program where the ADU occupant is not eligible for a permit.
  • Within one block of a car-share vehicle.
• Garage conversion: no replacement parking required for the primary dwelling when a garage is demolished or converted in conjunction with ADU construction (Gov. Code § 66314(d)(11)). This rule preempts any local replacement-parking requirement.
• JADU parking: no parking is required for a JADU itself. If a JADU is built in a garage that the city counts toward the primary residence’s required parking, replacement parking for the primary may apply — verify with Planning during pre-submission review.

Lot coverage and FAR

Per Gov. Code § 66321(b)(3), a city cannot apply local FAR, lot coverage, or open-space standards in a way that prevents construction of at least an 800 sqft ADU with 4-foot side and rear setbacks and 16 feet of height. Santa Clarita’s base residential zones generally accommodate the 850/1,000 sqft caps on standard SCV single-family lots, which are typically 5,000–9,000 sqft and larger in master-planned subdivisions. The Statewide Exemption ADU under § 66323 is the floor any eligible lot can rely on.

Owner-occupancy

For ADUs: owner-occupancy is not required in Santa Clarita. Gov. Code § 66315 prohibits cities from requiring owner-occupancy for an ADU, full stop. Santa Clarita complies.

For JADUs: the City Planning Division’s ADU FAQ states that JADUs require a recorded deed restriction obligating owner-occupancy of either the JADU or the primary residence. However, effective January 1, 2026, California AB 1154 amended Gov. Code § 66333(b) to narrow that requirement: owner-occupancy now applies only when the JADU shares sanitation facilities with the primary residence. A JADU with its own dedicated bathroom is no longer subject to owner-occupancy under state law. Santa Clarita’s handout has not yet been updated to reflect AB 1154 — raise the shared-sanitation distinction explicitly during pre-submission review.

Impact fees

• Under 750 sqft: exempt from development impact fees per Gov. Code § 66318.
• 750 sqft and above: impact fees are charged proportionally to the primary dwelling, calculated using the ADU’s square footage per § 66318.
• Design implication: a 750-sqft ADU can shave thousands off the fee schedule compared to an 850–1,000 sqft unit. The Sunset Signature Home (480 sqft) and Wilshire Signature Home (400 sqft) both sit well inside the exemption.

Permitting timeline

Per Gov. Code § 66317, an ADU or JADU application that is deemed complete must be approved or denied ministerially within 60 days. No design review hearing, no neighbor notice, no discretionary conditions. Real-world elapsed time from initial submission to permit issuance in Santa Clarita typically runs 3 to 5 months because the 60-day clock starts only after the application is deemed complete, and most projects go through a correction cycle or two before that point. Lots with oak trees or in the High Fire Hazard Severity Zone run longer because of the additional review layers covered below.

Permitting your ADU

Ministerial review, 60-day clock

Per Gov. Code § 66317, Santa Clarita must approve or deny a complete ADU or JADU application ministerially within 60 days of the application being deemed complete. No design review hearing. No Planning Commission action. No neighbor notice. If your plans meet the objective standards in SCMC § 17.57.040, the City must approve.

The 60-day clock is statutory. The real-world elapsed time is longer because most projects go through one or two correction cycles, and because Building Safety plan check (Title 18 of the Municipal Code) runs alongside Planning review. Expect approximately 3 to 5 months from initial submission to permit issuance in Santa Clarita on a straightforward project — longer on lots with oak protection, hillside grading, or High Fire Hazard Severity Zone access review.

Where to submit

Applications go to the City of Santa Clarita Planning Division at 23920 Valencia Blvd., Suite 140 (phone (661) 255-4330). The City also operates an online Permit Portal accessible through santaclarita.gov for application submittal and plan-check tracking.

Pre-submission review we recommend

A pre-submission meeting with the assigned planner confirms code compliance before you enter the fee-paid review queue, catches High Fire Hazard Severity Zone access requirements and oak protection nuances specific to your parcel, and identifies the state-law preemption positions (SB 1211, AB 1154, § 66323 Statewide Exemption) you may need to assert. We do this on every Santa Clarita project and it materially reduces correction cycles.

Renting your new ADU

Per the City Planning Division’s ADU FAQ, a Santa Clarita ADU cannot be rented for less than 30 days — the 30-day floor matches state law under Gov. Code § 66314(e). Practically, that means a Santa Clarita ADU is a long-term tenancy asset: monthly leases or longer, not nightly Airbnb or weekly vacation rentals.

A few drivers anchor SCV rental demand. Six Flags Magic Mountain and Henry Mayo Newhall Hospital both employ locally in Valencia. CalArts pulls in a steady student and faculty rental base. Princess Cruises runs its corporate office population from Santa Clarita. SCV rents track the broader north-county market. A well-finished 1- or 2-bedroom ADU in Valencia, Saugus, Newhall, or Canyon Country usually leases within 60 to 90 days of completion. A rough payback on the all-in build is 10 to 14 years at 2026 SCV rents. The exact number turns on which Signature Home you build and the lot you build it on.