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What are Santa Monica's ADU rules?

Santa Monica has its own ADU code, SMMC Section 9.31.025, and its own November 2025 guides 12. On a lot with one house you may build a converted ADU, a JADU and a detached ADU; the detached unit can be 850 sq ft as a studio or one-bedroom or 1,200 sq ft with two or more bedrooms, two stories or 24 feet tall, 4 feet from the side and rear lines, with no parking and no owner-occupancy requirement 34567. The city exempts ADUs from its four development impact fees 14. The catch is the Coastal Zone: Santa Monica has no certified Local Coastal Program, so a parcel west of 4th Street north of Pico, or west of Lincoln south of Pico, also needs a permit or waiver from the California Coastal Commission 22225.

Edited by Ryan Rambo, construction managerFacts checked 2026-10-13

Does Santa Monica follow the same ADU rules as Los Angeles?

No. Santa Monica is a separate city, and its ADU rules live in Santa Monica Municipal Code Section 9.31.025, not the LA code 1. The city published two plain-language guides in November 2025, one for parcels with a single-unit dwelling and one for parcels with a multiple-unit dwelling 2.

The process is ministerial: no design review, no public hearing, only a building permit, unless the parcel is in the Coastal Zone or listed on the California Register of Historical Resources 2. The city has 60 days from a complete application to approve or deny, and an application not acted on in 60 days is deemed approved 13.

The code is also fresh. In February 2024 the state housing department (HCD) found the 2023 ordinance out of step with state law on 18 points, including a rule allowing only one ADU and one JADU per parcel 21. The section was amended on October 8, 2024 and May 27, 2025 15, and the guide now allows a converted ADU, a JADU and a detached ADU on one lot 3. For a house inside the City of Los Angeles, use our setbacks, height and parking guides instead.

How many ADUs can I build on a Santa Monica house lot, and how big?

On a parcel with a single-unit dwelling, the guide lists four types, and you may build all that apply: one converted ADU, one JADU, one detached ADU, and one more ADU on parcels in the R1 zone 3.

The size rules for a converted or detached ADU are the same 4:

A detached ADU may be two stories or 24 feet tall, may not sit in the required front setback, and must be 4 feet from the side and rear lines and 4 feet from the main house, wall to wall 5. A JADU is capped at 500 sq ft inside the footprint of the house 8. The fourth unit, for R1 lots, must be deed-restricted as a rental or sold separately as a condominium 9.

If the city standards get in the way, a new detached ADU may instead use the state-mandated standards in the same section 10: up to 800 sq ft, 4-foot side and rear setbacks, and the height limits in Government Code Section 66321 11. See our JADU guide for the ADU-versus-JADU difference. On a parcel with two or more units, the code allows at least one ADU or up to 25 percent of the unit count by converting non-livable space, plus up to eight detached ADUs, not to exceed the number of existing units 12.

Do I need parking, and can I convert my garage?

No parking is required for an ADU anywhere in Santa Monica, and when a garage becomes an ADU the lost spaces do not have to be replaced 6. If you want to keep a space, parking displaced by an ADU may be relocated to the front half of the parcel with the existing curb cut kept, provided it meets the dimensional and visibility standards and is not on a no-backout street 6.

The guide tells owners in the Coastal Zone to contact the California Coastal Commission about parking, because the Commission applies its own rules there 6. And if the garage was a parking amenity for a rent-controlled unit on the property, the guide says to contact the Rent Control Department about possible rent adjustments 6.

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Can I rent it out, live somewhere else, or sell the ADU separately?

For an ADU, yes to all three, with one limit. Owner occupancy is not required, short-term rentals of 30 days or less are not permitted, and the ADU may be sold separately from the house under SMMC Section 9.31.026, Accessory Dwelling Unit Condominiums 7. That section allows separate sale of a primary unit and its ADUs as condominiums under Government Code Section 66342, the state law added by AB 1033 16.

A JADU is different: the owner must live in either the house or the JADU, a deed restriction is recorded, and the JADU cannot be sold separately 8. Our owner-occupancy guide explains the state rule, our condo guide covers separate sale in practice, and our property tax guide covers how the new unit is assessed.

What fees does Santa Monica charge for an ADU?

Fewer than most cities. The code exempts ADUs and JADUs from the city's four development impact fees: the Affordable Housing Production Program, the Child Care Linkage Program, the Transportation Impact Fee Program, and the Parks and Recreation Development Impact Fee Program 14. The exemption has no size limit.

Two charges can still apply:

  1. Public Works fees on larger units. The city's preapproved-plan page says ADUs larger than 750 sq ft may be subject to Public Works impact fees 17. State law draws the same line: 750 sq ft or less of interior livable space is exempt from impact fees, and a larger unit pays in proportion to the size of the main house 19.
  2. Water and wastewater capital facility fees. These one-time fees apply when a project changes water demand or wastewater discharge; the water fee is charged by meter size and only when you request a new or larger meter, and the 3/4-inch meter fee was $8,429 when the schedule took effect March 1, 2021 18. State law adds that an ADU is not a new residential use for connection fees or capacity charges unless it is built together with a new house 19.

Plan check and permit fees vary by project, so ask Building and Safety for an estimate. Santa Monica set up a preapproved ADU plan program under AB 1332, but as of October 2026 its list of approved plans reads "NONE AT THIS TIME" 17. Los Angeles has a working version; see our standard plans guide.

Is my lot in the Coastal Zone, and what does that add?

The Coastal Zone in Santa Monica runs from the ocean to 4th Street north of Pico Boulevard and to Lincoln Boulevard south of Pico, about 1.5 square miles 25. Inside it, the city guide says a Coastal Development Permit or waiver may also be required through the California Coastal Commission 2.

The Commission, not the city, issues that permit because Santa Monica's 1992 Land Use Plan was only partly certified and its Implementation Plan was never approved 2625; the Commission counts Santa Monica among twelve jurisdictions where it issues coastal permits directly 22.

In practice, a typical backyard ADU gets a de minimis waiver rather than a full permit. In 2022 the Commission waived the permit for a two-story, 850 sq ft ADU over a new garage at 208 Alta Avenue, a quarter mile from the ocean, after the city's Planning Division approved it in concept; staff noted the certified plan allows one unit per parcel but the Commission has regularly found that ADUs are not equivalent to a full unit 23. The Commission's 2025-26 fees are $785 for a de minimis waiver and $3,923 for an administrative permit 24.

Where there is no certified Local Coastal Program, the Commission must approve or deny a complete coastal permit application for an ADU within 60 days, and if it does not act and there is an existing primary dwelling, the application is deemed approved 20. AB 1740, signed in October 2026, requires Santa Monica to submit a complete Local Coastal Program by January 1, 2029, after which the city will process most coastal permits locally 27.

Quick answers

How big can a detached ADU be in Santa Monica?

Up to 850 sq ft for a studio or one-bedroom and up to 1,200 sq ft with two or more bedrooms, at two stories or 24 feet 45.

Does Santa Monica require parking for an ADU?

No. On-site parking is not required, and parking removed to create the ADU does not have to be replaced; in the Coastal Zone, ask the Coastal Commission about its parking rules 6.

Does Santa Monica charge impact fees on ADUs?

The city exempts ADUs and JADUs from its affordable housing, child care, transportation and parks impact fees, but units over 750 sq ft may owe Public Works fees 1417.

Who issues the coastal permit for an ADU in Santa Monica?

The California Coastal Commission, because Santa Monica has no certified Local Coastal Program; it must act within 60 days of a complete application 2220.

Sources

  1. Accessory Dwelling Units (topic explainer), City of Santa Monica. Facts checked 2026-10-13
  2. ADU and JADU Guide, Parcels with a Single-Unit Dwelling (November 2025), Process, City of Santa Monica, City Planning Division. Facts checked 2026-10-13
  3. ADU and JADU Guide, Parcels with a Single-Unit Dwelling (November 2025), How many ADUs and JADUs can you build, City of Santa Monica, City Planning Division. Facts checked 2026-10-13
  4. ADU and JADU Guide, Parcels with a Single-Unit Dwelling (November 2025), Converted ADUs: Size, City of Santa Monica, City Planning Division. Facts checked 2026-10-13
  5. ADU and JADU Guide, Parcels with a Single-Unit Dwelling (November 2025), Detached ADUs: Permitted Locations, Setbacks, Height, City of Santa Monica, City Planning Division. Facts checked 2026-10-13
  6. ADU and JADU Guide, Parcels with a Single-Unit Dwelling (November 2025), Parking, City of Santa Monica, City Planning Division. Facts checked 2026-10-13
  7. ADU and JADU Guide, Parcels with a Single-Unit Dwelling (November 2025), Detached ADUs: Owner Occupancy, Lease Terms, and Separate Sale, City of Santa Monica, City Planning Division. Facts checked 2026-10-13
  8. ADU and JADU Guide, Parcels with a Single-Unit Dwelling (November 2025), JADUs, City of Santa Monica, City Planning Division. Facts checked 2026-10-13
  9. ADU and JADU Guide, Parcels with a Single-Unit Dwelling (November 2025), ADUs Located on Parcels in the R1 Zoning District: Use of the ADU, City of Santa Monica, City Planning Division. Facts checked 2026-10-13
  10. ADU and JADU Guide, Parcels with a Single-Unit Dwelling (November 2025), Detached ADUs: state alternative, City of Santa Monica, City Planning Division. Facts checked 2026-10-13
  11. Santa Monica Municipal Code § 9.31.025 J, State Mandated ADUs and JADUs: detached ADU size and height, City of Santa Monica (code text mirrored at gocodebook.com; official host ecode360 refuses automated fetches). Facts checked 2026-10-13
  12. Santa Monica Municipal Code § 9.31.025, multiple-unit dwellings: converted and detached ADUs, City of Santa Monica (code text mirrored at gocodebook.com). Facts checked 2026-10-13
  13. Santa Monica Municipal Code § 9.31.025 G, Procedures, City of Santa Monica (code text mirrored at gocodebook.com). Facts checked 2026-10-13
  14. Santa Monica Municipal Code § 9.31.025 O, Development Impact Fees, City of Santa Monica (code text mirrored at gocodebook.com). Facts checked 2026-10-13
  15. Santa Monica Municipal Code § 9.31.025, ordinance history, City of Santa Monica (code text mirrored at gocodebook.com). Facts checked 2026-10-13
  16. Santa Monica Municipal Code § 9.31.026, Accessory Dwelling Unit Condominiums: Purpose, City of Santa Monica (code text mirrored at gocodebook.com). Facts checked 2026-10-13
  17. Preapproved ADU Program, City of Santa Monica. Facts checked 2026-10-13
  18. Council Sets New Water and Wastewater Capital Facility Fees (Nov. 24, 2020), City of Santa Monica, Public Works. Facts checked 2026-10-13
  19. Accessory Dwelling Unit Handbook (March 2026), Fees: impact fees, connection fees, California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  20. Accessory Dwelling Unit Handbook (March 2026), Coastal Commission, California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  21. Review of Santa Monica’s Accessory Dwelling Unit (ADU) Ordinance under State ADU Law (letter, Feb. 26, 2024), California Department of Housing and Community Development (HCD). Facts checked 2026-10-13
  22. SB 1077 ADU LCP Processing Guidance (July 1, 2026), Background and Coastal Act Authority, California Coastal Commission. Facts checked 2026-10-13
  23. South Coast District Deputy Director's Report for Los Angeles County, February 2022: De Minimis Waiver 5-21-0546-W, 208 Alta Ave., Santa Monica, California Coastal Commission. Facts checked 2026-10-13
  24. Filing Fee Schedule 2025-26 (Exhibit 1 to staff report W6d, June 2025), Residential Development, California Coastal Commission. Facts checked 2026-10-13
  25. What new coastal zoning rules could mean for Santa Monica, Santa Monica Daily Press. Facts checked 2026-10-13
  26. Santa Monica City Council resolution (Exhibit to Coastal Commission staff report Th13a, March 2022), recitals on the 1992 LUP, California Coastal Commission / City of Santa Monica. Facts checked 2026-10-13
  27. Newsom signs Zbur bill setting path to Santa Monica coastal plan (Oct. 7, 2026), Santa Monica Daily Press. Facts checked 2026-10-13

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Greenlight is not a contractor, architect or engineer, and this is not legal advice. Rules change; every fact here shows the date we last checked it.