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

What you can build in Santa Clarita

Since Ordinance 26-2 (April 28, 2026), Santa Clarita’s ADU rules are the California state floor: SCMC § 17.57.040(L) sets no local size, height, setback, parking or unit-count standard and defers to Gov. Code §§ 66310 et seq. outright. Two local layers still matter on the ground: oak tree protection, and the Fire Code access requirements that apply on state-designated fire-hazard lots. No detached-to-primary separation is set in § 17.57.040(L) after Ordinance 26-2 — confirm with Planning whether a general accessory-structure spacing rule elsewhere in Chapter 17.57 applies to your lot.

Number of units allowed

Single-family lots — the state-law § 66323 stack. Ordinance 26-2 removed the former one-ADU-plus-one-JADU cap from SCMC § 17.57.040; the subsection now defers to Gov. Code § 66323 directly. Under the § 66323 stack, an eligible single-family lot can typically combine all three of the following on the same parcel:

• 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, and in Santa Clarita it is now the local rule as well as the state one. If an older City handout still describes a one-ADU-plus-one-JADU allowance, it no longer reflects § 17.57.040(L). The HCD ADU Handbook confirms the stack as the governing rule for any single-family lot. 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. Santa Clarita sets no local multifamily count since Ordinance 26-2. 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(a)(4)(A)(ii)). With no local cap in § 17.57.040(L), the state figure applies directly.

Size limits

SCMC § 17.57.040(L) sets no local size cap since Ordinance 26-2, so Gov. Code § 66321 governs directly:

• Detached ADU: the City may not cap a detached ADU below 850 sqft for studios and 1-bedroom units, or 1,000 sqft for units with two or more bedrooms (Gov. Code § 66321(b)(2)). These are the floors the City must allow, not local ceilings.
• Attached ADU: the same 850/1,000 sqft floors apply. The former local limit of 50% of the primary residence’s floor area went with the rest of the Ord. 25-1 standards.
• 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

SCMC § 17.57.040(L) sets no local ADU setback since Ordinance 26-2, so the state guarantees govern directly:

• Side and rear setbacks: 4 feet — the state-law guarantee in Gov. Code § 66321(b)(3), applied directly.
• Detached-to-primary separation: none is set in § 17.57.040(L) after Ordinance 26-2. Confirm at pre-submission whether a general accessory-structure spacing rule elsewhere in Chapter 17.57 applies to your lot.
• Front setback: governed by the underlying base zone’s front-yard setback — which, under Gov. Code § 66321(b)(3), may not be applied so as to prevent an 800 sqft ADU with 4-foot side and rear setbacks.
• Conversion: no additional setback required when the ADU is built inside the existing permitted garage footprint.

Maximum height

SCMC § 17.57.040(L) sets no local height cap since Ordinance 26-2, so Gov. Code § 66321(b)(4) governs directly:

• Detached ADU — base: 16 feet — the state base height in Gov. Code § 66321(b)(4)(A), applied directly.
• Detached ADU — transit exception: within one-half mile walking distance of a major transit stop or high-quality transit corridor, 18 feet plus 2 ft to match the primary dwelling’s roof pitch (effective 20 ft) (Gov. Code § 66321(b)(4)(B)).
• Detached ADU — multistory-multifamily exception: on a lot with an existing or proposed multistory multifamily dwelling, 18 feet, with no roof-pitch bonus (Gov. Code § 66321(b)(4)(C)).
• Attached ADU: up to 25 feet or the height limit the zone applies to the primary dwelling, whichever is lower, and 2 stories (Gov. Code § 66321(b)(4)(D)). This floor defers to the zone — confirm the parcel’s zone limit before designing to 25 ft.
• Garage conversion: within the existing garage footprint, no separate height increase.

What this means for design. Because the City sets no cap of its own, the state 16-ft base is the operative detached envelope on most lots — Santa Clarita is effectively a 1-story detached-ADU market by default, with a 2-story path available for attached ADUs under the 25-foot envelope (or the zone’s primary-dwelling limit, if lower). Our two-story Signature plans stand roughly 25 feet, so they cannot be permitted as detached units in Santa Clarita as drawn; we modify them to fit the envelope, or design a custom ADU. Lots within one-half mile of transit 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

SCMC § 17.57.040(L) imposes no local parking requirement since Ordinance 26-2 (the former local waiver list is gone), so Gov. Code § 66322 governs directly:

• Default rule: at most one off-street parking space per ADU (Gov. Code § 66322).
• 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.
  • Located within an architecturally and historically significant historic district.
  • 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: parking may never be required for a JADU (Gov. Code § 66334(a)). The former local JADU garage-replacement language was deleted by Ordinance 26-2.

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 state floors 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: not required. Ordinance 26-2 deleted the former SCMC § 17.57.040(L)(2)(n)(i) provision that put an owner-occupancy condition on any ADU applied for on or after January 1, 2025, and Gov. Code § 66315 bars a city from imposing owner-occupancy on an ADU in any event. There is nothing left in the code to be quoted at the counter.

For JADUs: SCMC § 17.57.040(L)(3)(b) requires the property owner to occupy either the single-family residence or the JADU, unless exempt under applicable law, including Gov. Code § 66333(b). That is the AB 1154 exemption (effective January 1, 2026): owner-occupancy applies only when the JADU shares sanitation facilities with the primary residence. A JADU with its own dedicated bathroom is not subject to owner-occupancy, and Santa Clarita’s code now cites the exemption expressly.

Impact fees

• Under 750 sqft: exempt from development impact fees per Gov. Code § 66311.5(c)(1).
• 750 sqft and above: impact fees are charged proportionally to the primary dwelling, calculated using the ADU’s square footage per § 66311.5(c)(1).
• What the local code says: SCMC § 17.57.040(L)(5)(a) states that all ADUs and JADUs are subject to development impact fees, charged proportionally to the primary dwelling’s square footage, “except as provided in applicable law.” The local text omits both state exemption thresholds. Gov. Code § 66311.5(c)(1) governs: no impact fee on an ADU of 750 sqft or less, none on a JADU of 500 sqft or less, and proportional charging only above 750 sqft — and § 17.57.040(L) itself provides that California law controls on any conflict.
• Utility connections: SCMC § 17.57.040(L)(5)(b) requires a separate utility connection for each ADU and JADU, subject to a connection fee or capacity charge, “except as provided by applicable law.” State ADU law bars requiring a new or separate connection for an ADU created by conversion within an existing single-family dwelling or accessory structure, and requires any connection fee to be proportionate to the unit’s burden on the system; the subsection’s own supremacy clause means the state rule controls.
• 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 SCMC § 17.57.040(L)(3)(a), any rental of a Santa Clarita ADU must be for a term of 30 days or longer (the JADU rule at (L)(3)(b) is the same) — 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 est. cost to 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.