Santa Monica allows ADUs and JADUs by right on any parcel zoned for single-unit or multi-unit residential use under SMMC 9.31.025 (last amended by Ord. 2814CCS, adopted May 27, 2025). Local standards allow a detached ADU of 850 sq ft (studio/1-bedroom) or 1,200 sq ft (2+ bedrooms), 2 stories or 24 ft tall, with 4 ft side and rear setbacks and no parking; the 800 sq ft state-mandated unit is available as an alternative. The permit is a ministerial building permit decided within 60 days, ADUs are exempt from the city's transportation, parks, affordable-housing and childcare impact fees (9.31.025(O)), and a detached ADU may be sold separately as a condominium under SMMC 9.31.026. Parcels in the Coastal Zone also need a Coastal Development Permit or waiver from the California Coastal Commission, which Gov. Code 66329 now puts on the same 60-day clock.
Zoning & Size Requirements [1][2][3][4][5]
Yes — Santa Monica allows ADUs. A detached ADU can typically be up to 850 sq ft under current California and Santa Monica zoning rules.
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| Allowed Zones | Any legal parcel zoned for single-unit or multiple-unit residential use (residential and mixed-use districts) with an existing or proposed primary dwelling (SMMC 9.31.025(E)); not allowed on a parcel with a Gov. Code 66499.41 multi-unit ownership project or where the unit would exceed the SB 9 duplex/lot-split cap |
| Max Size (Detached) | 850 sq ft (studio/1-bedroom) or 1,200 sq ft (2+ bedrooms) under the local standards, 150 sq ft minimum; a garage with an internal connection to the ADU does not count toward the cap (SMMC 9.31.025(I)(1)(c)). The state-mandated alternative under 9.31.025(J) is 800 sq ft |
| Max Size (Attached) | 850 sq ft (studio/1-BR) or 1,200 sq ft (2+ BR), but an ADU converted from or added onto the existing house may not exceed 50% of the existing primary dwelling, whichever is less (SMMC 9.31.025(I)(1)(a)(v), (I)(1)(d)); the city's Guide guarantees at least 800 sq ft for conversions of the existing house |
| Max Size (JADU) | 500 sq ft of floor area (150 sq ft minimum), within the walls of the existing or proposed single-unit dwelling including an attached garage, or in a new addition to the house; a recorded deed restriction is required (SMMC 9.31.025(I)(1)(b), (K)) |
| Max Height | Detached ADU: 2 stories or 24 ft (SMMC 9.31.025(I)(1)(c)), measured per SMMC 9.04.050 (usually from average natural grade; a land survey is required for 2-story or sloped-lot units). Attached ADUs and JADUs: the underlying district's height limit for the primary dwelling. Detached ADUs on multi-unit parcels: 24 ft |
| Max Units | Single-unit parcel: 1 converted ADU + 1 JADU + 1 detached ADU, plus 1 more attached or detached ADU in the R1 zone that must be deed-restricted as a rental or sold as a condo (SMMC 9.31.025(H)(1), (I)(1)(d)). Multi-unit parcel: converted ADUs equal to 25% of existing units (at least 1) in non-livable space, plus up to 8 detached ADUs with an existing building (not more than the existing unit count) or 2 with a new one (9.31.025(H)(2)) |
Setback Requirements [1][2][3][4][5]
Santa Monica requires a rear setback of about 4 ft for a detached ADU, and no additional parking is required. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 4 ft (SMMC 9.31.025(I)); no setback for existing space or a structure rebuilt in the same location and to the same dimensions, including unpermitted structures built before Jan 1, 2020 that are converted to an ADU (Guide p.3) |
| Side Setback | 4 ft; a detached ADU must sit at least 4 ft from the primary dwelling, measured between exterior walls (SMMC 9.31.025(B), 'Detached'), and may share a wall with another detached ADU or accessory structure |
| Front Setback | Not permitted within the required front setback of the underlying zoning district; a conversion of an existing structure already in the front setback may expand up to 150 sq ft for ingress and egress (SMMC 9.31.025(I)(1)(a)(ii)) |
| Parking Required | None required for ADUs or JADUs, and parking removed to build one (garage, carport or driveway) need not be replaced (SMMC 9.31.025(L)); displaced parking may be relocated to the front half of the lot per SMMC 9.28.070(A)(1)(a)(ii). Coastal Zone parcels should confirm parking with the Coastal Commission |
| Owner Occupancy | ADUs: not required (SMMC 9.31.025; Guide pp.4, 9). JADUs: SMMC 9.31.025(K)(2) and the Nov 2025 Guide require the owner to live in the main house or the JADU; since Jan 1, 2026 state law (Gov. Code 66333(b), AB 1154) allows that only for JADUs that share a bathroom with the main house, so ask Planning how the city applies it |
| Min Lot Size | None — SMMC 9.31.025 sets no minimum lot size, and Gov. Code 66321 bars any lot-size minimum that would block an 800 sq ft ADU with 4 ft setbacks |
Permit Process & Fees [6][7][8][9][10]
An ADU permit in Santa Monica goes through a ministerial, by-right review. Typical timeline: 60 days from a complete application, or the ADU is deemed approved (SMMC 9.31.025(G)); since Jan 1, 2026 the city must also issue a completeness notice within 15 business days (Gov. Code 66317, SB 543). A Coastal Zone CDP runs on its own 60-day clock (Gov. Code 66329). Permit fees: Plan check and building permit fees are valuation-based under the City's adopted fee schedule (finance.smgov.net); Planning charges $985.11 for a deed-restriction application and $833.46 for a Coastal Zone Approval in Concept (fees effective July 1, 2026).
| Approval Process | Ministerial building permit only — no design review or hearing (SMMC 9.31.025(D), (G)) — filed through the city's Electronic Plan Review system; JADUs and R1 bonus ADUs also file a Planning deed-restriction application. Coastal Zone parcels need a Coastal Development Permit or waiver from the California Coastal Commission, processed concurrently under Gov. Code 66329 |
| Review Timeline | 60 days from a complete application, or the ADU is deemed approved (SMMC 9.31.025(G)); since Jan 1, 2026 the city must also issue a completeness notice within 15 business days (Gov. Code 66317, SB 543). A Coastal Zone CDP runs on its own 60-day clock (Gov. Code 66329) |
| Permit Fees | Plan check and building permit fees are valuation-based under the City's adopted fee schedule (finance.smgov.net); Planning charges $985.11 for a deed-restriction application and $833.46 for a Coastal Zone Approval in Concept (fees effective July 1, 2026) |
| Impact Fees | ADUs and JADUs are exempt from the city's Transportation (Ch. 9.66), Parks (Ch. 9.67), Affordable Housing (Ch. 9.64) and Childcare (Ch. 9.65) impact fees (SMMC 9.31.025(O)). Statewide, ADUs 750 sq ft or less and JADUs 500 sq ft or less owe no impact fees (Gov. Code 66311.5); the city warns that ADUs larger than 750 sq ft may owe Public Works (water/wastewater) capital facility fees, and school fees apply above 500 sq ft |
| Plan Check | Electronic Plan Review: a prescreen for completeness, then routed plan check with corrections issued by email; initial plan review fees are paid at submittal and final fees before issuance. Every ADU needs its own address via an Address Application |
| Pre-Approved Plans | Preapproved ADU Program under Gov. Code 65852.27 (AB 1332) accepts vendor-submitted Standard ADU Plans for detached ADUs only, with no modifications allowed; as of Sept 2026 the city lists no approved plans ('NONE AT THIS TIME') |
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Construction Costs [11]
Building an ADU in Santa Monica typically costs $250,000-$500,000 ($325-$550 per sq ft); a garage conversion runs $140,000-$245,000.
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| Average Build Cost | $250,000-$500,000 |
| Cost per Sq Ft | $325-$550 |
| Garage Conversion | $140,000-$245,000 |
| Prefab ADU (Installed) | $200,000-$350,000 |
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Rental Income Potential [12]
A 2-bedroom ADU in Santa Monica rents for around $4,000-$4,700/mo, an estimated 5-8% annual return.
| Avg Rent (1 Bedroom) | $3,000-$3,700/mo |
| Avg Rent (2 Bedroom) | $4,000-$4,700/mo |
| Short-Term Rental | No — ADUs and JADUs may not be rented for 30 days or less (SMMC 9.31.025(M)); the only carve-out is licensed home-sharing under SMMC Ch. |
| Est. Annual ROI | 5-8% annual return |
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Recent Law Changes
What's Changed Recently
- Sept 20, 2026 re-verification: SMMC 9.31.025 read in full (as amended by Ord. 2792CCS, Oct 8, 2024 and Ord. 2814CCS, May 27, 2025); owner-occupancy, unit counts, the impact-fee exemptions and the 4 ft detached-separation rule now match the code text; planning fees updated to the July 1, 2026 schedule
- Ord. 2814CCS (adopted May 27, 2025): latest amendment of SMMC 9.31.025 and 9.31.026, aligning the ordinance with the renumbered Gov. Code 66310-66342 — 60-day deemed approval, up to 8 detached ADUs on multi-unit parcels, separate sale under Gov. Code 66340
- Gov. Code 66329 (current text): the Coastal Commission must approve or deny a coastal development permit for an ADU within 60 days of a complete application, and the city must notify the Commission as soon as the ADU application is complete
- SB 543 (Ch. 520 of 2025, eff. Jan 1, 2026): 15-business-day completeness notice, a written appeal path, and JADUs of 500 sq ft or less exempt from impact fees; the 60-day deemed-approval rule was already in SMMC 9.31.025(G)
- AB 1154 (Ch. 507 of 2025, eff. Jan 1, 2026): JADU owner-occupancy may only be required when the JADU shares sanitation facilities with the main house (Gov. Code 66333(b)); SMMC 9.31.025(K) and the city's Nov 2025 Guide still state the older blanket requirement
- SMMC 9.31.026 (Ord. 2792CCS, Oct 8, 2024): Santa Monica opted into AB 1033 — ADUs on single-unit and multi-unit parcels may be sold separately as condominiums (JADUs excluded)
- City ADU/JADU Guides for single-unit and multi-unit parcels dated November 2025 remain the current handouts as of Sept 2026; the Preapproved ADU Program still lists no approved plans
Tips for Building an ADU in Santa Monica
- Check whether your parcel is in the Coastal Zone first (the western part of the city, roughly between the beach and 4th St/Lincoln Blvd — confirm on the City GIS map): those parcels need a Coastal Development Permit or waiver from the California Coastal Commission, which now runs on the same 60-day clock as the building permit under Gov. Code 66329
- R1 parcels can stack four accessory units — a converted ADU, a JADU, a detached ADU and one more attached or detached ADU — but the fourth unit must be deed-restricted as a rental or sold as a condo under SMMC 9.31.026 (SMMC 9.31.025(I)(1)(d))
- Santa Monica offers two rulebooks: the local standards (850/1,200 sq ft, 24 ft, 4 ft setbacks, 50% cap for attached units) or the state-mandated unit (800 sq ft, height per Gov. Code 66321, no other local design standards) — pick the one that fits your lot (SMMC 9.31.025(I) vs (J))
- Unpermitted structures built before Jan 1, 2020 can be converted to an ADU with no setback compliance required (Guide p.3) — get written permit-history verification from Building & Safety first
- Under SMMC 9.31.025(O) an ADU pays none of the city's transportation ($10,797-$11,081), parks ($10,413), affordable-housing or childcare impact fees that a new single-family unit would owe (FY2025-26 Development Impact Fees sheet); budget instead for valuation-based plan check and permit fees, a $985.11 deed-restriction fee if you build a JADU or R1 bonus ADU, and possible Public Works capital fees above 750 sq ft
- Since Jan 1, 2026 the city must tell you within 15 business days whether your ADU application is complete; the 60-day decision clock runs from the complete application, and a complete application not acted on in 60 days is deemed approved (SMMC 9.31.025(G); Gov. Code 66317)
- If a garage conversion removes parking that was an amenity for a rent-controlled unit, contact the Rent Control Department first — rent adjustments may apply (Guide p.6)
- Cost basis: build-cost ranges are Westside industry estimates as of June 2026 (about $280,000-$365,000 for 840-1,080 sq ft two-story detached plans, roughly $310-$370 per sq ft hard cost; custom, hillside and Coastal Zone projects run higher); rents are RentCafe/Yardi Matrix Santa Monica averages as of Aug 31, 2026 ($3,452 for a 1-bedroom, $4,483 for a 2-bedroom)
- Cost basis (2026-09-20 re-verification): short term allowed: No — ADUs and JADUs may not be rented for 30 days or less (SMMC 9.31.025(M)); the only carve-out is licensed home-sharing under SMMC Ch. 6.20, which needs a City home-share permit and business license — vacation rentals are prohibited
ADU Builders in Santa Monica
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Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- SMMC 9.31.025 Accessory Dwelling Units and Junior Accessory Dwelling Units (as amended by Ord. 2814CCS, May 27, 2025) Municipal Code — Accessed 2026-09-20
- ADU and JADU Guide — Parcels with a Single-Unit Dwelling (City of Santa Monica, Nov 2025) Planning Department — Accessed 2026-09-20
- ADU Guide — Parcels with a Multiple-Unit Dwelling (City of Santa Monica, Nov 2025) Planning Department — Accessed 2026-09-20
- AB 1154 (Ch. 507, Stats. 2025) — Junior accessory dwelling units: owner-occupancy (Gov. Code 66333) state_statute — Accessed 2026-09-20
- Gov. Code 66329 — ADUs in the Coastal Zone (60-day coastal development permit decisions) state_statute — Accessed 2026-09-20
- Preapproved ADU Program — City of Santa Monica Planning Department — Accessed 2026-09-20
- City Planning Division Application Fees Effective July 1, 2026 (FY26-27, revised) fee_schedule — Accessed 2026-09-20
- Development Impact Fees FY 2025-2026 (City of Santa Monica Planning Division) fee_schedule — Accessed 2026-09-20
- SB 543 (Ch. 520, Stats. 2025) — ADU/JADU permitting timelines and fee limits (Gov. Code 66311.5, 66317) state_statute — Accessed 2026-09-20
- Planning Resources — City of Santa Monica (links to current ADU guides and fee worksheets) Planning Department — Accessed 2026-09-20
- Santa Monica ADU Rules, Costs & Timeline 2026 — CALI ADU (reviewed June 2026) industry — Accessed 2026-09-20
- Average Rent in Santa Monica, CA — RentCafe / Yardi Matrix (updated Aug 31, 2026) Market Data — Accessed 2026-09-20
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