ADU Rules In Santa Monica: What Owners Should Know

Thinking about adding an accessory dwelling unit to your Santa Monica property? With state reforms streamlining approvals and strong local housing demand, an ADU can be a smart way to create flexible space or long-term rental income. Still, the rules can feel complex, especially with coastal and historic overlays. In this guide, you will learn the essentials on where ADUs are allowed, how approvals work, what to expect for parking and utilities, and the rental basics to keep in mind. Let’s dive in.

ADUs in Santa Monica: The basics

California law requires cities to allow ADUs and junior ADUs under a ministerial review process in most single-family and many multifamily situations. That means the City uses objective standards and cannot apply discretionary design review in most cases. Santa Monica must follow this state framework, but the City can set objective rules for size, height, setbacks, and design details.

State law generally prohibits local owner-occupancy requirements for ADUs in most situations. In practice, you can often build and rent an ADU without living in the primary home, subject to other local rules. To avoid delays, plan to submit a complete application so you stay within the state’s short review clock that typically applies to compliant, complete files.

Where ADUs are allowed

Most single-family lots in Santa Monica can add one ADU or a junior ADU inside the primary home, and some configurations allow both. Multifamily properties may also qualify for interior conversions or detached ADUs, but the exact number and placement depend on your site and the City’s standards.

If your parcel has an overlay, such as the Coastal Zone or a historic district, you may have extra steps. Start by confirming your zoning, lot dimensions, and any overlays with Santa Monica Planning before you invest in design.

Size, height, setbacks, and design

State law sets some ceilings and baseline protections, and Santa Monica adds objective standards you must meet. Expect rules that address:

• Maximum square footage for attached and detached ADUs
• Height limits for detached ADUs and conversions
• Side and rear setbacks, often smaller for ADUs, with state rules in many cases allowing reduced setbacks such as 4 feet
• Lot coverage or floor-area-ratio calculations, including how ADU area is counted
• Objective design criteria, such as materials, window placement, or massing

Because numbers vary by zoning district and lot, ask for the City’s ADU handout and verify the standards that apply to your specific parcel.

Parking and access

State law significantly limits how much parking cities can require for ADUs, especially near public transit or for certain unit types. Given Santa Monica’s transit access, many parcels may not need new off-street parking for an ADU, but you should confirm your site’s specific requirement with City Planning.

You still must satisfy basic access and safety needs. Driveway standards, turning radii, and fire access can affect siting. Work these details into your early site plan so they do not trigger redesign later.

Utilities, connections, and fees

Plan early for water, sewer, and electrical service to the ADU. The City and utilities will review capacity and outline allowed connection methods, metering options, and related fees. Local plan-check and building-permit fees apply, and some impact-fee rules are limited by state law for smaller ADUs. Fee schedules and any incentives change, so request current estimates from Santa Monica Planning and Building & Safety.

For rentals, understand how utilities will be billed and whether a separate meter or submeter is needed. This decision affects tenant agreements and operating costs.

Coastal Zone and historic districts

Parts of Santa Monica are in the Coastal Zone. Your ADU must be consistent with the City’s Local Coastal Program. Many ADUs still follow a ministerial path, but coastal-specific requirements can add complexity. If your property is in a historic district or has a designated historic resource, expect additional objective standards and review focused on preservation. Verify this status early so your design aligns with the required standards.

Rental use, STR rules, and tenant protections

Santa Monica has strict short-term rental rules. If you are considering listing an ADU as a vacation rental, confirm whether that use is legal and what registrations or primary residence rules apply. Many owners choose long-term rentals instead. New ADU construction is generally not covered by traditional rent control that applies to older registered units, but local tenant-protection rules can still apply. Always confirm current obligations with the City and consult legal counsel as needed.

The permitting path

A smooth ADU project starts with clear steps and a complete file:

1. Pre-application. Contact Santa Monica Planning for an intake conversation. Request the latest ADU packet, application checklist, and fee schedule.
2. Site and zoning check. Confirm zoning district, lot coverage, height limits, setbacks, and overlays such as Coastal Zone or historic districts.
3. Prepare plans. Assemble a site plan, floor plans, elevations, and utility plans. Include title information and proof of lot dimensions. JADUs require plans that show conversion within existing walls.
4. Submit for building permits. Building & Safety will review structural, electrical, plumbing, energy code, and other life-safety items. Fire review may apply.
5. Pay fees and coordinate utilities. Plan-check, permit, and utility connection fees are typical. Confirm metering and capacity with the utility providers.
6. Inspections and final. Complete required inspections and obtain final approval for occupancy.

State law sets a short ministerial review timeframe for complete ADU applications. Incomplete submittals and special overlays can extend timelines, so aim to meet every item on the City’s checklist at first submittal.

Common pitfalls to avoid

• Submitting incomplete plans. Missing drawings, utility notes, or title information can reset the clock. Use the City’s checklist.
• Overlooking overlays. Coastal and historic rules can change your design and extend review.
• Misreading parking rules. Transit proximity often limits parking requirements. Confirm your parcel’s status early.
• Assuming short-term rental income. Santa Monica’s STR rules are strict. Verify legality before you design around a particular business plan.
• Ignoring HOA/CC&R limits. Some private rules still apply, even with state ADU protections. Review your documents and consult counsel if needed.

Financial planning considerations

An ADU is both a lifestyle upgrade and a long-term asset. As you plan, outline your total project budget, expected holding costs, and your rental strategy. Consider how utility metering, maintenance, and potential vacancies affect net income. If your property is in the Coastal Zone or a historic district, build schedule contingency into your financial plan.

If you are weighing multiple design options, compare scenarios that balance cost, timeline, and rental flexibility. A clear pro forma helps you decide whether to prioritize a larger detached ADU, an interior conversion, or a JADU inside the primary home. Coordinate with your legal and tax advisors so your plan aligns with current local rules and your broader financial goals.

Quick owner checklist

• Verify zoning and overlays with Santa Monica Planning, including Coastal Zone and historic status.
• Request the current ADU handout, application checklist, and fee schedule from the City.
• Schedule a pre-submittal check with Planning and Building & Safety.
• Assemble complete plans: site plan, floor plans, elevations, utilities, and title documents.
• Confirm parking rules for your parcel, especially transit proximity.
• Coordinate with water, sewer, and electric providers on capacity and metering.
• Review short-term rental rules and your HOA or CC&Rs before finalizing a design.
• Submit a complete application and budget for inspections and compliance.

Ready to move from idea to action with a clear, numbers-forward plan? As a boutique advisory led by a licensed REALTOR and CPA, we help you evaluate costs, timelines, and rental strategies so your ADU decision supports your lifestyle and long-term equity.

Connect with Lisa B Realty to discuss your Santa Monica ADU plans in a confidential, focused consultation.

FAQs

Can I build an ADU on a single-family lot in Santa Monica?

• In most cases yes, since state law requires cities to allow ADUs under ministerial review, but you must meet Santa Monica’s objective standards and verify any overlays on your parcel.

How big can a Santa Monica ADU be?

• Size and height limits are set by objective local standards within state law, so request the City’s ADU handout to confirm square footage, height, and how ADU area counts toward coverage.

Do Santa Monica ADUs need off-street parking?

• State rules limit parking requirements, especially near transit and for certain ADUs, but you should confirm your parcel’s exact requirement with City Planning.

What is the typical ADU approval timeline in Santa Monica?

• State law requires a timely ministerial decision on complete applications, commonly cited around 60 days, but coastal or historic reviews and incomplete submittals can extend timelines.

Can I use an ADU for short-term rentals in Santa Monica?

• Santa Monica has strict short-term rental rules, so verify whether your planned use is legal and whether registration or primary residence rules apply before you proceed.

Are new ADUs subject to Santa Monica rent control?

• New construction ADUs are generally not covered by older rent-control protections, but local tenant-protection rules may still apply, so confirm current obligations with the City and legal counsel.