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Can I build an ADU in Sierra Madre, California?

Sierra Madre, Los Angeles County · Ordinances checked 2026-10-05 · Reviewed · 15 cited sections

Allowed with a permit

Yes. Under Ordinance No. 1494 (adopted May 26, 2026), Sierra Madre must approve an ADU on a single-family lot ministerially (no hearing), and an application not acted on within 60 days is deemed approved. A new detached ADU of up to 800 sq ft of interior living space, 16 feet tall and 4 feet from side and rear lot lines is guaranteed; a new detached unit can be up to 1,200 sq ft if the lot's floor-area and lot-coverage limits allow. In the R-1 zone no extra parking space is required.

Guaranteed detached ADUUp to 800 sq ft interior livable space, 4-ft side/rear setbacks [1]
Max detached ADU size1,200 sq ft interior livable space for a new detached unit (subject to zone floor area/lot coverage) [2]
Max attached ADU sizeGreater of 850 sq ft (1,000 sq ft if 2+ bedrooms) or 50% of the house [3]
Junior ADU max size500 sq ft [4]
Detached ADU height (single-family lot)16 feet [5]
Attached ADU heightLesser of 25 feet or the zone limit [6]
Side and rear setback, new ADU4 feet [7]
Parking in the R-1 zoneNo additional space required [8]
Owner-occupancyOnly for a JADU that shares bathroom facilities with the house [10]
Minimum rental term30 days (no short-term rentals) [11]
City decision deadline60 days or deemed approved [12]

These rules come from Ordinance No. 1494, adopted May 26, 2026 and effective 30 days later [14]. It now governs; the online code (Ch. 17.22) still shows the older 2022 text, including owner-occupancy for every junior ADU. We read the ordinance's redline as adopted (additions in, deletions out).

What you can build

ADUs are a by-right residential use in zones that allow homes. On a single-family lot the City must ministerially issue a permit for one converted ADU and/or one junior ADU (JADU) inside the house or an existing accessory structure, plus one new detached ADU of up to 800 sq ft of interior livable space with 4-foot side and rear setbacks [1]. Larger units are allowed: up to 1,200 sq ft for a newly built detached unit [2], and for an attached unit the greater of 850 sq ft, 1,000 sq ft with more than one bedroom, or half the house [3]. A JADU is capped at 500 sq ft [4]. Beyond the 800 sq ft guarantee, the lot's floor-area and lot-coverage limits still apply.

Height and setbacks

A new detached ADU on a single-family lot can be 16 feet tall [5] (18 feet near major transit). An attached ADU can reach the lesser of 25 feet or the zone limit [6]. New construction needs 4-foot side and rear setbacks; a conversion built to the same dimensions as the existing structure needs none [7]. No new roof decks are allowed.

Parking

One space per ADU is the general rule [15], but no additional space is required in the R-1 zone [8][9]. Ord. 1494 removed the R-H (Hillside) zone from that exemption, so in R-H one space applies unless another exemption fits, such as a JADU, a conversion of existing space, the 800 sq ft state-mandated unit, or a site within half a mile of transit. A converted or demolished garage doesn't have to be replaced.

Occupancy and renting

Owner-occupancy applies only to a JADU that shares sanitation facilities with the house [10]. ADUs and JADUs can be rented for 30 days or more but not as short-term rentals, and you need an annual business license while renting [11]. Before the building permit is issued you must record a covenant [13].

Process

Applications are reviewed ministerially; if a complete application isn't approved or denied within 60 days it is deemed approved [12]. Older homes (75+ years) need a historic resource evaluation, and work near protected trees needs an arborist report. Starting January 1, 2027, state law (AB 956) will require cities to allow two new detached ADUs on a single-family lot; Sierra Madre's ordinance doesn't reflect that yet (see state rules).

See how Sierra Madre compares with 8+ other California towns on accessory dwelling units (adus) →

Next steps

  1. Check your zone (R-1, R-H, etc.) and lot floor-area and coverage limits with Planning & Community Preservation, 232 W. Sierra Madre Blvd., (626) 355-7138.
  2. If you want the state-guaranteed 800 sq ft unit, say so in your application and cite SMMC 17.22.060 (the City won't assume it).
  3. Submit the building permit application through the Building and Safety page/Accela portal with site plan, floor plans, elevations, project data table and photos listed in SMMC 17.22.100.
  4. Order a historic resource evaluation if the house is more than 75 years old, and an arborist report if work is near protected trees.
  5. Record the required covenant before permit issuance, and get a business license before renting the unit.

Common questions

Can I build an ADU in Sierra Madre, California?
Yes. Under Ordinance No. 1494, Sierra Madre must approve an ADU on a single-family lot ministerially, with no hearing, and a complete application not acted on within 60 days is deemed approved.
How big can an ADU be in Sierra Madre, California?
A new detached ADU of up to 800 sq ft of interior livable space is guaranteed, and it can be up to 1,200 sq ft if the lot's floor-area and lot-coverage limits allow. An attached ADU can be the greater of 850 sq ft (1,000 sq ft with more than one bedroom) or half the house, and a junior ADU is capped at 500 sq ft.
How tall can a detached ADU be in Sierra Madre, California?
A new detached ADU on a single-family lot can be 16 feet tall, or 18 feet near major transit. An attached ADU can reach the lesser of 25 feet or the zone limit, and new construction needs 4-foot side and rear setbacks.
Do I need parking for an ADU in Sierra Madre, California?
Not in the R-1 zone, where no additional space is required. In the R-H (Hillside) zone one space applies unless another exemption fits, such as a JADU, a conversion or a site within half a mile of transit. A converted garage doesn't have to be replaced.
Can I rent my ADU on Airbnb in Sierra Madre, California?
No. ADUs and JADUs can be rented for 30 days or more but not as short-term rentals, and you need an annual business license while renting. Owner-occupancy applies only to a JADU that shares sanitation facilities with the house.

California's statewide ADU law

California's ADU law (Gov. Code §§66310–66342, recodified from §65852.2; latest amendments effective January 1, 2026) overrides conflicting city rules, including in charter cities. Cities must approve ADUs ministerially (no hearing) within 60 days of a complete application, or the permit is deemed approved.

What cities cannot require or do:

  • Owner-occupancy for an ADU.
  • A minimum lot size.
  • Side or rear setbacks over 4 feet for a new ADU, or any setback for a converted existing structure.
  • Size, lot coverage or floor-area rules that block an ADU of at least 800 sq ft. Size caps can't be under 850 sq ft (1,000 for 2+ bedrooms).
  • Parking within half a mile walking distance of public transit, or replacement parking for a garage converted to an ADU.
  • Impact fees on ADUs of 750 sq ft or less.

By right on a single-family lot: one converted ADU plus one junior ADU (JADU, up to 500 sq ft inside the house), plus one new detached ADU (up to 800 sq ft, 16 ft tall). Owner-occupancy may be required only for a JADU that shares a bathroom.

Short-term rentals: cities may bar ADU rentals under 30 days, and must for by-right ADUs, JADUs and SB 9 units.

Coming January 1, 2027: AB 956 raises the by-right count to two new detached ADUs per single-family lot.

SB 9 (§§65852.21, 66411.7) allows two homes on a single-family lot, or a split into two lots of at least 1,200 sq ft (with a 3-year owner-occupancy affidavit).

State sources: Gov. Code §66314 (ADU ordinance standards) · Gov. Code §66315 (no owner-occupancy requirement) · Gov. Code §66317 (ministerial review, 60-day deadline) · Gov. Code §66321 (size, setback and height limits on local rules) · Gov. Code §66322 (parking exemptions) · Gov. Code §66323 (by-right ADUs and JADUs) · Gov. Code §66333 (junior ADUs) · Gov. Code §66311.5 (impact fees) · AB 956 (2026), Stats. 2026, ch. 791 · Gov. Code §65852.21 (SB 9 two-unit projects) · Gov. Code §66411.7 (SB 9 urban lot splits) · HCD, Accessory Dwelling Units (ADU Handbook, updated March 2026)

What the ordinance says

Exact text from Sierra Madre's published ordinances. Section numbers are as printed in the source.

  1. Sec. 17.22.060(A)(2) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 7
    One detached, new construction, accessory dwelling unit that does not exceed four-foot side and rear yard setbacks, an interior livable space of eight hundred square feet, and a height as defined in Section 17.22.030(D) of this Chapter for a lot with a proposed or existing single-family dwelling.
  2. Sec. 17.22.030(C)(2)(a) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 3
    The total interior livable space for newly constructed detached accessory dwelling units shall not exceed 1,200 square feet.
  3. Sec. 17.22.030(C)(1) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 3
    a. 850 square feet of interior livable space; b. 1,000 square feet of interior livable space if the accessory dwelling unit provides more than one bedroom; or
  4. Sec. 17.22.030(C)(1)(d) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 3
    The interior livable space for a junior accessory dwelling unit shall not exceed 500 square feet.
  5. Sec. 17.22.030(D)(2)(a) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 4
    On a lot with an existing or proposed single-family or single-story multifamily dwelling, the height of a newly constructed accessory dwelling unit or addition onto an existing accessory structure shall not exceed sixteen feet.
  6. Sec. 17.22.030(D)(1)(a) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 4
    For an newly constructed accessory dwelling unit that is attached to a primary dwelling, the height shall not exceed the lesser of twenty-five feet or as governed by the applicable zoning requirements.
  7. Sec. 17.22.030(G)(2) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 5
    A setback of no less than four feet from the side and rear lot lines shall be required for new construction or replacement structures not built to the same dimensions as the existing structure.
  8. Sec. 17.22.030(F)(3)(h) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 5
    Located in the R-1 (One-family Residential) zone.
  9. Sec. 17.22.030(F)(3) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 5
    Exemptions. No additional parking space is required for accessory dwelling units meeting any one of the following:
  10. Sec. 17.22.050(A) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 6
    The owner must reside in either the single-family dwelling or within the junior accessory dwelling unit if the junior accessory dwelling unit shares sanitation facilities with the primary structure.
  11. Sec. 17.22.130 (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 14
    A. An accessory dwelling unit or junior accessory dwelling unit may be rented for terms no less than thirty days. The person or party responsible for ownership of property that has an accessory dwelling unit or junior accessory dwelling unit shall obtain and maintain an annual business license, in accordance with Title 5, for dwelling accommodations when actively renting or advertising the rental of the dwelling unit.
  12. Sec. 17.22.100(B)(5) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 12
    If a building permit application is not approved or denied within sixty (60) days, the application shall be deemed approved.
  13. Sec. 17.22.090(A) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 8
    As a prerequisite to obtaining a building permit, the applicant for an accessory dwelling unit permit shall record a covenant or deed restriction specifying that the accessory dwelling unit will at all times comply with the provisions of this chapter and applicable state law.
  14. Ord. 1494, Section 8, Ordinance No. 1494 - ADU Municipal Code Text Amendment (MCTA 26-01), adopted May 26, 2026, p. 1
    Pursuant to Government Code Section 36937, this Ordinance shall take effect thirty days after its adoption.
  15. Sec. 17.22.030(F)(1) (Ord. 1494, Exh. 1), Ordinance No. 1494 Exhibit 1 - changes to Ch. 17.08 and Ch. 17.22 (ADUs), p. 5
    One on-site parking space shall be required for each accessory dwelling unit in addition to parking required for the primary dwelling(s).
This page summarizes Sierra Madre's posted ordinances as of 2026-10-05. Ordinances are amended, and individual lots can have overlays, subdivision covenants, or HOA rules that are stricter. Confirm with City of Sierra Madre Planning & Community Preservation Department / Building and Safety, 232 W. Sierra Madre Blvd. ((626) 355-7138) before you build. Spot an error?