ADU Rules in Santa Monica.
Local ADU regulations, permit fees, setback requirements, and typical timelines for Santa Monica. Last updated 2026-05-27.
Santa Monica ADU Requirements
Attached ADU: up to 25 ft
Santa Monica is entirely within ½ mile of Big Blue Bus and Metro transit lines.
Plan check and permit fees; school fees apply for units over 500 sq ft.
Design 4 weeks · Permit 6 weeks · Build 36 weeks
Plain-language summary
In Santa Monica, a detached ADU requires a minimum 4-foot side setback and 4-foot rear setback. The maximum height for a detached ADU is 16 feet, while an attached ADU may be up to 25 feet. The maximum size for a detached ADU is 1,200 sq ft; a Junior ADU (JADU) is limited to 500 sq ft. Replacement parking is not required for most projects. Typical permit fees range from $7,000 to $16,000. A typical project takes approximately ~11 months from design start to move-in, including 4 weeks of design, 6 weeks for permit review, and 36 weeks of construction.
⚠️ ADU rules change frequently. Always verify current requirements with the Santa Monica Building & Safety Department before submitting plans. Official source →
What to Watch Out For
- Properties west of Lincoln Blvd and south of Olympic Blvd may be in the Coastal Zone — a Coastal Development Permit is required.
- Rent control (SMMC Chapter 4.36) applies to existing structures; new ADUs are generally exempt if permitted after 1995.
- LADU HQ is located in Santa Monica — local permit expertise is particularly strong here.
How Long Does It Take to Get an ADU Permit in Santa Monica?
Site study, floor plans, elevations, structural drawings.
Plan check, corrections, and permit issuance by Santa Monica Building & Safety.
Foundation, framing, MEP rough-in, finishes, final inspection.
A licensed engineer on your lot, free.
30 minutes. We walk the property, figure out what's feasible, and answer any questions you have.
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