ADU Rules in Santa Monica, CA (2026)

Santa Monica, CA permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. California state law actively preempts local restrictions, making ADU approval a streamlined ministerial process. In Santa Monica, the Santa Monica Community Development Department — Building and Safety Division handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Santa Monica.

ADU Size Limits

ADU Size Limits in Santa Monica: Detached ADU: up to 1200 sq ft (max height: 16 feet). Attached ADU: 50% of primary dwelling up to 1200 sqft. Junior ADU (JADU): up to 500 sq ft — must be within the existing primary dwelling or accessory structure. Detached ADU maximum 1,200 sqft per California Gov Code 65852.2(c)(2)(B). JADU maximum 500 sqft within existing dwelling per Gov Code 65852.22. Santa Monica's extremely high land values make ADUs for rental income highly lucrative — even a 500 sqft JADU can rent for $2,500+ per month. SMMC Section 9.31.290.

Permit Fees

ADU Permit Fees in Santa Monica: Plan check fee: $800–$4,000 depending on project value. Building permit fee: $1,500–$6,000 depending on valuation. Impact fees: None. School fees: Exempt for ADUs under 750 sqft. ADUs 750+ sqft subject to Santa Monica-Malibu Unified School District developer fees.. Total estimated permit cost: $3,000–$12,000 total permit fees — higher than most CA cities due to Santa Monica's premium fee schedule. Impact fees waived for ADUs under 750 sqft per Gov Code 65852.2(f)(3). Santa Monica Water department connection fees for new services. Santa Monica is in the Coastal Zone — Coastal Development Permits required for properties west of Lincoln Blvd and near the beach. CDP review is an additional step and cost. Fee schedule: https://www.santamonica.gov/departments/community-development/building

Permit Timeline

Santa Monica ADU Permit Timeline: Santa Monica Community Development processes ADU permits through SMGovNet online portal. Ministerial approval within 60 days per state law. Plan review typically 4-8 weeks due to high permit volume in this dense city. Construction 4-12 months. Santa Monica's Coastal Zone status for beachside properties adds Coastal Development Permit requirements. Apply through the Santa Monica Community Development Department — Building and Safety Division online permit portal. Phone: (310) 458-8355.

Setback Requirements

ADU Setback Requirements in Santa Monica: Front setback: Same as zone standard. Side setback: 4 feet. Rear setback: 4 feet. 4-foot side and rear setbacks for new detached ADUs per California Gov Code 65852.2(c)(2)(E). Santa Monica's R1 zones typically require 5 ft interior side and 15-20 ft front setbacks for primary dwellings. ADU setbacks at 4 ft are less than primary dwelling standards — state law cannot be restricted locally.

Parking Requirements

Parking Requirements: No additional parking required for ADUs within one-half mile of Metro E Line (Expo Line) stations. Downtown Santa Monica (4th/Colorado), 17th St/SMC, and 26th St/Bergamot stations create broad transit proximity zones. No replacement parking when garage converted to ADU. Per California Gov Code 65852.2(d).

Restrictions & Requirements

• •ADU must comply with Santa Monica Municipal Code objective standards — SMMC Chapter 9.31.290
• •ADU subject to Santa Monica Rent Control Charter Amendment (RCCA) if it meets RCCA coverage criteria (generally applies to buildings with 2+ units built before 1979)
• •Short-term rental of ADU (fewer than 30 days) prohibited under Santa Monica's strict STR ordinance
• •ADU in the Coastal Zone west of Lincoln Blvd may require Coastal Development Permit
• •ADU cannot be sold separately from primary dwelling
• •Historic districts (Wilshire Montana Boulevard Overlay District) may require Design Review

How Many ADUs Are Allowed?

Number of ADUs Allowed in Santa Monica: Single-family lots: 1 ADU + 1 JADU per single-family lot. Multifamily properties: Up to 25% of existing units (minimum 2) as detached ADUs; internal conversions permitted per state law. CRITICAL NOTE: Santa Monica Rent Control (RCCA) may apply to newly created ADUs in certain circumstances. Consult a Santa Monica rent control attorney before creating an ADU if you have existing tenants or multifamily buildings. New ADUs in newly built structures (post-1995) are generally exempt from rent control under Costa-Hawkins.

State Law & Preemption

Historic District Considerations

Frequently Asked Questions