Los Angeles County
Santa Monica ADU rules
Research summary of local ADU rules on file for Santa Monica in Los Angeles County. Not a determination for a specific lot.
City or county ADU page
Check any California address for freeSanta Monica rules on file
Local rules recorded in this project for this jurisdiction. Where a city figure on file is stricter than the state baseline on file, both are shown.
Local regulations (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): In the Coastal Zone, a Coastal Development Permit or Waiver may also be required through the California Coastal Commission, and parking questions go to the Coastal Commission. This lookup cannot tell whether a parcel is in the Coastal Zone; check with the City Planning Division.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), Process; Parking, accessed 2026-10-23.
Permit route (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): ADUs and junior ADUs are ministerial: no design review or public hearing, building permit only. Full standards are in SMMC 9.31.025. Questions go through the City's 311 system.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), Process; Additional Questions, accessed 2026-10-23.
How many units (single-unit lot) (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): One converted ADU, one junior ADU and one detached ADU, plus, in the R1 district, one more attached or detached ADU.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), How many ADUs and JADUs can you build, accessed 2026-10-23.
ADU size (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): Minimum 150 sq ft. Maximum 850 sq ft (studio or one bedroom) or 1,200 sq ft (two or more bedrooms). A conversion of the main home is limited to 50% of it or those limits, whichever is less, but at least 800 sq ft. ADU floor area is exempt from floor area calculations.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), Converted ADUs: Size; Floor Area, accessed 2026-10-23.
Side and rear setbacks (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): 4 feet; none for existing space or a same-size rebuild that is converted. Detached means at least 4 feet from the main home.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), Setbacks; Detached ADUs, accessed 2026-10-23.
Height (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): Detached ADU: two stories or 24 feet. ADU within the main home: the zone height for the main home. Height is measured under SMMC 9.04.050; a survey is needed for multistory ADUs or sloped lots.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), Height, accessed 2026-10-23.
Design (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): Independent exterior access; no interior access to the main home (other than a garage serving the ADU). The zone's upper-story stepback and outdoor space standards apply; no projection closer than 4 feet to a lot line.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), Design Standards, accessed 2026-10-23.
Parking (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): No on-site parking required, and parking removed for an ADU does not have to be replaced (check with the Rent Control Department if it served a rent-controlled unit).
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), Parking, accessed 2026-10-23.
Owner occupancy, rentals and sale (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): No owner occupancy for ADUs. No short-term rentals (30 days or less). ADUs may be sold separately as condominiums under SMMC 9.31.026.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), Owner Occupancy, Lease Terms, and Separate Sale, accessed 2026-10-23.
Junior ADU (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): One per lot, 150 to 500 sq ft, within the main home (including an attached accessory structure) or a new addition, with an efficiency kitchen and its own or a shared bathroom (no bathroom needed with internal access). No parking. A deed restriction (no separate sale; size and attributes) must be recorded.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), JADUs, accessed 2026-10-23.
State-standard option (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): Instead of the Santa Monica standards, ADUs may be built under the state-mandated standards in SMMC 9.31.025.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Single-Unit Dwelling (November 2025), Alternative to the above Santa Monica standards, accessed 2026-10-23.
Multifamily lots (non-coastal areas only)
Outside the Coastal Zone only (does not apply to Coastal Zone parcels): Separate standards apply to parcels with multi-unit dwellings, including converted ADUs in non-livable space and detached ADUs.
Source: City of Santa Monica, ADU and JADU Guide: Parcels with a Multi-Unit Dwelling (November 2025), ADU and JADU Guide: Parcels with a Multi-Unit Dwelling, accessed 2026-10-23.
California state rules on file
The statewide baseline recorded from state law and the HCD ADU Handbook.
Detached size cap described in state law
1,200 sq ft. Recorded in this rules file from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Side and rear setback cap for a new ADU
4 ft. Recorded in this rules file from Government Code section 66314, which describes a cap on side and rear setbacks for a new ADU.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Setback for a conversion of an existing structure
No additional setback, as recorded in this rules file from Government Code section 66314 for a conversion of an existing structure.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Minimum lot size
A city may not impose a minimum lot size for an ADU, as recorded in this rules file from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Minimum unit the handbook says cities must allow
At least an 800 sq ft ADU with 4 ft side and rear setbacks. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(3).
Source: HCD ADU Handbook, 66321(b)(3); handbook updated March 2026, accessed 2026-10-16.
Detached height described in the handbook
16 ft, or 18 ft or 20 ft in some cases. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(4).
Source: HCD ADU Handbook, 66321(b)(4); handbook updated March 2026, accessed 2026-10-16.
Permit decision deadline
60 days. Recorded in this rules file from Government Code section 66317(a)(3): the permitting agency must decide on (approve or deny) a completed ADU application within 60 days when an existing single-family or multifamily dwelling is on the lot. Section 66317(a)(1) says the application is considered ministerially, without discretionary review or a hearing.
Source: California Government Code section 66317, 66317(a)(1), (a)(3), accessed 2026-10-17.
Owner-occupancy requirement
None. Recorded in this rules file from Government Code section 66315: a local agency may not impose an owner-occupancy requirement on an ADU. It may require that the property be used for rentals of terms 30 days or longer. The HCD ADU Handbook (updated March 2026) describes the same rule.
Source: California Government Code section 66315, 66315; HCD ADU Handbook updated March 2026, accessed 2026-10-17.
Parking near public transit
No parking standards within one-half mile walking distance of public transit. Recorded in this rules file from Government Code section 66322(a)(1). Section 66322(a) lists several other cases where parking standards may not be imposed.
Source: California Government Code section 66322, 66322(a), accessed 2026-10-17.
Ministerial categories
The HCD ADU Handbook (updated March 2026) states that Government Code section 66323 sets four ministerial categories. This rules file does not restate those four categories.
Source: HCD ADU Handbook, 66323; handbook updated March 2026, accessed 2026-10-16.
Fire Hazard Severity Zones
If your lot is in a Fire Hazard Severity Zone, the CAL FIRE Office of the State Fire Marshal says in Information Bulletin 25-004 (issued March 3, 2025): “Fire Hazard Severity Zones (FHSZs) should not restrict the development of Accessory Dwelling Units (ADUs). However, additional building standards may be necessary, including but not limited to California Fire Code Chapter 49 and California Building Code Chapter 7A.” State ADU law does not itself bar an ADU there. A city or county may still apply its building code, including wildfire-resistant construction (Gov. Code 66314(d)(8)); require side and rear setbacks “sufficient for fire and safety” for a unit converted under 66323(a)(1); and decline parking in setbacks on specific fire and life safety findings (66314(d)(10)(B)). It may also consider public safety when it designates where ADUs may be permitted (66314(a)). Sprinklers can't be required in an ADU or JADU if the primary residence doesn't need them (66314(d)(12), 66323(d)). Some cities and counties still apply their own fire-zone limits. Where this summary has one, it is listed with the local rules. This summary does not look up your lot. Check the CAL FIRE Fire Hazard Severity Zone map viewer linked from the State Fire Marshal's Fire Hazard Severity Zones page: https://experience.arcgis.com/experience/5065c998b4b0462f9ec3c6c226c610a9
Source: CAL FIRE Office of the State Fire Marshal Information Bulletin 25-004, page 4, issued March 3, 2025; Gov. Code 66314, 66323, accessed 2026-10-20.
State baseline on the directory → · State ADU rules on the homepage →
Can I build an ADU in Santa Monica?
State law sets a baseline for ADUs in Santa Monica, and the local standards on file are listed on this page. Whether a specific lot can add an ADU depends on zoning, utilities, and other site facts this page does not measure. Confirm with the City of Santa Monica Community Development Department (City Planning Division), or run a free address summary.
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