ADU rules in Santa Monica

Detached ADUs are allowed on any legal parcel zoned for single-unit or multiple-unit residential use that has or will have a primary dwelling (SMMC 9.31.025(E)(1)), and the use tables list ADUs and JADUs as permitted (P) in R1, R2, R3, R4, every Ocean Park district (OP1, OPD, OP2, OP3, OP4) and the Oceanfront (OF) district. A single-unit parcel may add one new detached ADU, either a local-track unit (850 or 1,200 sq ft, two stories or 24 ft) under 9.31.025(I)(1)(c) or the state-exempt unit of up to 800 sq ft with 4-ft side and rear setbacks under 9.31.025(J)(1)(b) and Gov. Code 66323(a)(2), and in the R1 district a second, bonus ADU that may also be detached if it is deed-restricted as a rental or sold as a condominium (9.31.025(I)(1)(d)). Multifamily parcels may add up to eight detached ADUs beside an existing building, never more than its unit count, or two with a proposed building (9.31.025(H)(2)(b); 66323(a)(4)). Approval is a ministerial building permit, and inside the coastal zone a Coastal Commission coastal development permit or waiver is also required (see permitType). No ADU or JADU may be added to a parcel with an approved Gov. Code 66499.41 (SB 684) ownership project, and on SB 9 duplex and lot-split parcels ADUs count toward the 9.31.125(E)(2) unit caps (9.31.025(E)(2)).

Attached and internal ADUs are allowed on every single-unit parcel as one converted ADU within the existing or proposed home or an existing attached or detached accessory structure such as an attached garage (9.31.025(I)(1)(a), (J)(1)(a)). Under the local track a conversion may also grow by a conforming addition (only 150 sq ft for ingress and egress where the converted space sits in the front setback), while the state-exempt conversion stays within existing space plus a 150 sq ft access expansion for accessory structures but carries no size cap (Gov. Code 66323(a)(1)). One JADU of up to 500 sq ft is allowed within the walls of a single-unit home, including an attached garage (9.31.025(K)(1)); the local track also accepts a JADU in a newly built addition to an existing home (9.31.025(I)(1)(b)(iii)). In the R1 district the bonus ADU may be a newly constructed attached addition to the home (9.31.025(I)(1)(d)(ii)). On multifamily parcels at least one ADU, or up to 25 percent of the existing units, may be created in non-livable space such as storage rooms, boiler rooms, attics, basements or garages (9.31.025(I)(2)(a), (J)(1)(c); 66323(a)(3)).

Local-track ADUs must be 150 sq ft to 850 sq ft with a studio or one bedroom, or up to 1,200 sq ft with more than one bedroom, measured as floor area (9.31.025(I)(1)(a)(iv)-(v), (I)(1)(c)(ii)-(iii), (I)(2)(b)(ii)-(iii)); a conversion of an existing home and the R1 bonus attached addition are further limited to 50 percent of the existing home or those caps, whichever is less, and a converted detached accessory structure keeps its existing floor area plus any permitted expansion. State law sets the floor: no percentage or other limit may block an ADU of at least 800 sq ft of interior livable space with 4-ft side and rear setbacks, and no cap may fall below 850 sq ft, or 1,000 sq ft with more than one bedroom, of interior livable space (Gov. Code 66321(b)(2)-(3)); the City's November 2025 guide guarantees 800 sq ft for home conversions but does not say so for R1 additions. The state-exempt detached unit is capped at 800 sq ft (9.31.025(J)(1)(b); 66323(a)(2)) and a JADU at 500 sq ft (9.31.025(I)(1)(b)). Heights: local-track detached ADUs two stories or 24 ft (24 ft beside multifamily buildings), attached ADUs the zone height for the main home, and state-exempt detached units 16 ft, 18 ft within one-half mile of major transit (plus 2 ft to match the roof pitch) or 18 ft beside a multistory multifamily building (66321(b)(4)). Santa Monica measures floor area from the interior face of exterior walls and counts closets, storage and covered parking (9.04.080), while ADUs and JADUs are excluded from the parcel's floor-area ratio (9.04.080(B)(12)); the amendment on the 10-13-2026 council agenda would restate every cap in interior livable space.

Santa Monica imposes no owner-occupancy requirement on ADUs (Gov. Code 66315), and the City's November 2025 guide states 'Owner occupancy not required' for each ADU type. For JADUs the codified text still requires the owner to live in the home or the JADU in every case except where the owner is a government agency, land trust or housing organization (9.31.025(K)(2)), but since 1-1-2026 Gov. Code 66333(b) (AB 1154) permits owner occupancy only where the JADU shares sanitation facilities with the home, so a JADU with its own bathroom needs no owner on site. The JADU deed restriction barring separate sale and fixing the unit's size and attributes is still recorded (9.31.025(K)(3); 66333(c)). The amendment on the 10-13-2026 council agenda would write the separate-sanitation exemption into 9.31.025(K)(2)(c). The R1 bonus ADU carries a rental-or-condominium deed restriction, not an owner-occupancy requirement (9.31.025(I)(1)(d)(iii)).

SMMC 9.31.025(L)(1) requires no parking for an ADU or JADU anywhere in the city; parking an owner chooses to provide must meet Chapter 9.28 and the district standards. Garages, carports and covered or uncovered spaces demolished or converted to create an ADU or JADU need not be replaced (9.31.025(L)(2); Gov. Code 66314(d)(11)), and the City's guide adds that displaced parking may move to the front half of the parcel, keeping an existing curb cut, if it meets the 9.28.070 dimensional and visibility rules. Inside the coastal zone the City's guide tells applicants to contact the California Coastal Commission about parking, because the Commission's coastal permit is a separate approval that Gov. Code 66329 leaves under the Coastal Act. On rent-controlled properties, removing parking that was a tenant amenity may lead to a rent adjustment, and the guide directs owners to the Rent Control Department.

ADUs and JADUs that meet 9.31.025 are permitted by right and approved ministerially by building permit with no discretionary review or hearing (9.31.025(D), (G)); the City must approve or deny within 60 days of a complete application or the application is deemed approved, and a denial must list the deficiencies in writing (9.31.025(G)(1)-(2)). Gov. Code 66317(a)(2) also requires a written completeness determination within 15 business days, which the amendment on the 10-13-2026 council agenda would codify. Inside the coastal zone the City has no certified Local Coastal Program, so after the City approves the ADU the applicant also needs a coastal development permit or waiver from the California Coastal Commission (City guide; 5-12-2026 council presentation), and Gov. Code 66329(b) requires the Commission to approve or deny an ADU coastal permit within 60 days of a complete application, concurrently with the City's review, or it is deemed approved. The R1 bonus ADU additionally needs a recorded rental deed restriction or a 9.31.026 condominium approval, and the City's guide says properties on the California Register of Historical Resources may face additional standards or processes.

SMMC 9.31.025(M) bars ADU and JADU rentals of 30 days or less except home-sharing permitted under Chapter 6.20, which bans vacation rentals and allows only hosted home-sharing in the host's primary residence while the host lives on site; an ADU permitted on or after 3-31-2017 counts as a separate dwelling unit, so it can be home-shared only if it is the host's own residence (6.20.010(a), (f), 6.20.030; Home-Sharing Rules § V.A). State law removes that exception for state-exempt units and JADUs, which may be rented only for terms longer than 30 days (9.31.025(J)(2)(c); Gov. Code 66323(e), 66333(g)), and the amendment on the 10-13-2026 council agenda would bar 30-day JADU rentals outright. Every other ADU or JADU lease falls under the Residential Leasing Requirements Ordinance: a written lease with an initial term of at least one year, an unfurnished unit and a tenant who is a natural person using it as a primary residence (6.22.020(d), 6.22.040 to 6.22.070), unless the ADU's plans were submitted for plan check by 12-31-2020 and it sits on an owner-occupied single-unit lot with the owner on site, in which case terms over 30 days and under one year are allowed (6.22.100(a)(6)). The R1 bonus ADU must be used as a rental under a deed restriction or sold as a condominium (9.31.025(I)(1)(d)(iii)); otherwise an ADU may be sold separately only as a condominium under 9.31.026 (the City's Gov. Code 66342 opt-in, Ord. No. 2792CCS) or to a qualified buyer under the nonprofit rule of 66341, and a JADU never (9.31.025(N); 66333(c)). Rented ADUs and JADUs outside the Rent Control Charter must be registered with the City every year under Chapter 4.25 (effective 1-1-2026), and from 1-1-2027 no rent may be collected without a current registration certificate (4.25.060(b)).