California ADU rules · Los Angeles County
Can I Build an ADU in Santa Monica?
Yes — you can build an ADU in Santa Monica. California's statewide ADU law requires every city, including Santa Monica, to approve a qualifying accessory dwelling unit by right, plus a junior ADU (JADU) on a single-family lot. What varies city to city are the local specifics below.
Can you build one?
ADUs allowed
CA state lawYes — by right
ADUs and JADUs are allowed by right in all residential and mixed-use zones; ministerial approval, no hearing.
Units on a single-family lot
Local rule1 ADU (attached or detached) + 1 JADU
One ADU (attached or detached) and one JADU per parcel with a single-unit dwelling.
Units on a multifamily lot
CA state lawConversion ADUs (≥1, up to 25% of units) + up to 8 detached
Conversions of non-livable space (at least 1, or up to 25% of existing units) plus up to 8 detached ADUs on a lot with existing multifamily — never exceeding the number of existing units. JADUs are single-family only.
Junior ADU (JADU)
CA state lawAllowed
Up to 500 sq ft, within the walls of an existing single-family home (single-family lots only).
Size & height
Max detached ADU size
Local rule1,200 sq ft
850 sq ft for a studio/1-bedroom detached ADU; 1,200 sq ft for 2+ bedrooms.
Max attached ADU size
Local ruleUp to 50% of the primary dwelling's floor area, capped at 850 sq ft (studio/1-bedroom) or 1,200 sq ft (2+ bedrooms), but never less than the state minimum
Guaranteed minimum size
CA state law800 sq ft
An 800 sq ft ADU must be allowed regardless of FAR/lot-coverage caps; a city also cannot cap an attached ADU below 850 sq ft (1,000 for 2+ bedrooms).
Max JADU size
CA state law500 sq ft
Max height
Local rule24 ft
Detached ADUs may be up to 24 ft / 2 stories — above the 16-ft state baseline. Attached ADUs and JADUs follow the underlying zoning district's height limit; the state transit/2-story minimums apply if more permissive.
Setbacks
Side setback
CA state law4 ft
A city cannot require more than 4 ft side or rear setback; conversions of existing structures are exempt.
Rear setback
CA state law4 ft
Front setback
CA state lawNo front setback may block the mandatory 800 sq ft / 16-ft / 4-ft-setback ADU; otherwise per base zone
Separation from main house
CA state lawNone required
No statewide separation requirement between the ADU and the primary dwelling.
Parking
Parking required
Local ruleNone
Santa Monica requires no parking for any ADU or JADU regardless of location, and no replacement parking for garage conversions.
Transit parking exemption
CA state lawYes — no parking required near transit & for conversions
No parking may be required within ½ mi walking distance of transit, in a historic district, for an ADU within an existing structure, within one block of car-share, or in certain permit-parking areas.
Garage-conversion replacement parking
CA state lawNot required
When a garage/carport is demolished or converted to build an ADU, replacement parking cannot be required.
Approval, timeline & cost
Approval path
CA state lawMinisterial (by right)
No public hearing or discretionary design review for a qualifying ADU.
Approval timeline
CA state law60 days
The agency must act within 60 days of a complete application — and the ADU is deemed approved if it does not.
Owner-occupancy
Local ruleOnly for a JADU
No owner-occupancy for ADUs; a JADU requires the owner to occupy either the JADU or the primary dwelling (unless owned by a government agency, land trust, or housing organization).
Impact-fee waiver
CA state lawWaived under 750 sq ft
An ADU of 750 sq ft or less pays no impact fees (the 750 sq ft threshold itself is exempt under § 66311.5); larger ADUs pay fees proportional to the primary dwelling. JADUs (≤ 500 sq ft) are exempt.
Permits required
CA state lawBuilding permit
Only a ministerial building permit — no conditional use permit or discretionary design review for a qualifying ADU.
Santa Monica-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Full local impact-fee exemption (all sizes)
Santa Monica exempts every ADU and JADU — regardless of size — from its four local development impact fees (Affordable Housing Production, Childcare Linkage, Transportation Impact, and Parks & Recreation Development), going beyond the state's ≤750 sq ft impact-fee waiver.
Coastal Zone / Coastal Act
Properties in the Coastal Zone may require additional review or a coastal development permit for Local Coastal Program consistency; the code adds no local ADU overlay, but Coastal Act compliance still applies.
Historic & architecturally significant districts
ADUs on designated historic properties or in historic districts may be subject to additional review or standards, and demolishing a garage in such an area can trigger the state notice/placard requirement.
Santa Monica allows one ADU plus one JADU on a single-family lot, permits detached ADUs up to 24 ft and two stories with a 1,200 sq ft cap for 2+ bedrooms (among the most generous in Los Angeles County), and requires no parking anywhere in the city. Distinctively, it exempts all ADUs and JADUs from its four local development impact fees regardless of size. Feasibility is usually driven by Coastal Zone review and tight lot dimensions rather than the entitlement itself.
Frequently asked questions
Can I build an ADU in Santa Monica?
Yes. California's statewide ADU law requires Santa Monica to approve a qualifying accessory dwelling unit ministerial (by right), plus a junior ADU (JADU) on a single-family lot.
How big can an ADU be in Santa Monica?
A detached ADU of at least 1,200 sq ft must be allowed, and an ADU of 800 sq ft can never be zoned out by floor-area or lot-coverage limits. A JADU can be up to 500 sq ft.
What are the setback requirements for an ADU in Santa Monica?
Side and rear setbacks are limited to 4 ft. No front setback may block the mandatory 800 sq ft / 16-ft / 4-ft-setback ADU; otherwise per base zone.
Is parking required for an ADU in Santa Monica?
None. No parking can be required within ½ mile of transit, for conversions, or for units inside the primary home. When a garage is converted, replacement parking is not required.
How long does ADU approval take in Santa Monica?
A complete application must be acted on within 60 days, with ministerial (by right) — no public hearing or discretionary design review for a qualifying ADU.
Do I have to live on the property to build an ADU in Santa Monica?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- SMMC § 9.31.025 (Ord. No. 2814CCS)
- SMMC § 9.31.025(H)(1)
- SMMC § 9.31.025(I)(1)(a)(v)
- SMMC § 9.31.025(I)(1)(a)(v)(c)
- SMMC § 9.31.025(I)(1)(a)(vi)
- SMMC § 9.31.025(L)(1)
- SMMC § 9.31.025(K)(2)
- SMMC § 9.31.025(O)
- SMMC § 9.31.025(F)
- SMMC § 9.31.025(F); Gov. Code § 66314(f)
- Cal. Gov. Code §§ 66310–66342 (ADU Law)
- HCD 2025 Accessory Dwelling Unit Handbook
- Cal. Gov. Code § 66317 (ministerial approval, 60-day deadline)
- Cal. Gov. Code § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66321 (size minimums & height)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
- Cal. Gov. Code § 66314 (local ordinance standards)
- Cal. Gov. Code § 66311.5 (impact fees: none for an ADU ≤ 750 sq ft or JADU ≤ 500 sq ft)
Last updated 2026-06-25. This is an AI-assisted summary of Santa Monica's ADU rules, drawn from its published ordinance and California ADU law — general information, not legal advice, and it may be incomplete or out of date. Verify the controlling rule for your specific parcel with Santa Monica Planning before relying on it.
Will an ADU work on your Santa Monica lot?
Ask GoCodebook about your address and get the size, setback, parking and permit rules that actually apply to your parcel — with the exact citation.
Check my parcel free