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Building an ADU in Santa Monica, CA — Westside coastal neighborhoods near the Santa Monica Pier and the bay, where CALI ADU permits backyard Signature Home ADUs under SMMC § 9.31.025
Santa Monica · ADU Rules, Costs & Timeline 2026

Building an ADU in Santa Monica. Rules, costs, timeline.

What SMMC § 9.31.025 actually allows, how the California Coastal Zone affects your permit timeline, and what an all-in build costs on a Santa Monica lot in 2026.

Reviewed by CALI ADU’s ADU specialists · June 2026

What you can build — at a glance

Reviewed by CALI ADU’s ADU specialists · June 2026

Max ADU size
850 sqft (studio / 1BR) · 1,200 sqft (2BR+) per SMMC § 9.31.025
Detached height
2 stories / 24 ft by right (SMMC § 9.31.025) · above 16/18 ft state floor
Attached height
Matches underlying zoning district’s primary-dwelling limit
Side & rear setbacks
4 ft · 4 ft separation from primary dwelling
Units per SFR lot
Up to 3: conversion ADU + JADU + new detached ≤800 sqft (Gov. Code § 66323; HCD Handbook). SMMC also allows additional detached/attached ADU paths on R1 lots.
Parking required
None on-site (SMMC § 9.31.025 imposes no requirement)
Permit timeline
60 days · ministerial review, no hearing (Gov. Code § 66317)
AB 1033 separate sale
Yes — Santa Monica has opted in. ADU may be sold separately via condo map (SMMC § 9.31.026)
  • Detached Up to 1,200 sqft (2BR+) · 24 ft / 2 stories by right
  • Attached Matches primary dwelling zoning height
  • Junior ADU Up to 500 sqft inside primary dwelling
  • Conversion Existing accessory structure to ADU
  • Exemption ADU 800 sqft / 16 ft state-law floor (Gov. Code § 66323)

Per SMMC § 9.31.025 and Gov. Code §§ 66310–66342. Units-per-lot figure reflects the state-law stack confirmed by the HCD ADU Handbook (March 2026). Full citations in the sections below.

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On this page

Where Santa Monica’s ADU rules come from

Every rule on this page is sourced from one of four primary documents: California Government Code §§ 66310–66342 (the state ADU statute, renumbered from former § 65852.2 et seq. by SB 477 effective March 25, 2024), Santa Monica Municipal Code (SMMC) § 9.31.025 (Santa Monica's ADU ordinance), SMMC § 9.31.026 (Santa Monica's ADU Condominium ordinance), and the City's official ADU and JADU Guide — Parcels with a Single-Unit Dwelling published by the Santa Monica Community Development Department, City Planning Division, November 2025. When the Guide and state law differ, the more permissive of the two controls — because state law sets a floor that cities cannot drop below, and the Santa Monica ordinance sets ceilings that in several places go higher than the state floor (most notably on height).

Last verified against primary sources on April 23, 2026. State ADU law changes every January 1. If you are reading this six months from now, confirm the current version before you commit to a design — or call us and we will confirm it for you.

Santa Monica is not the City of Los Angeles

The biggest mistake we see is homeowners applying City of LA rules — or worse, a generic online ADU calculator's assumptions — to a Santa Monica parcel. Four things are meaningfully different:

  • Different permitting authority. Your permit goes to Santa Monica Community Development Department (CDD) — Building & Safety Division and Planning Division — not to LADBS.
  • Different ordinance. Santa Monica's ADU rules live in SMMC § 9.31.025. Los Angeles's live in LAMC § 12.22.A.33. They overlap where state law forces them to overlap, and diverge everywhere else.
  • Coastal Zone overlay. Large chunks of Santa Monica — generally west of Lincoln plus portions of Ocean Park — are inside the California Coastal Zone. City of LA has a Coastal Zone too (Venice, Pacific Palisades, San Pedro), but Santa Monica's overlay is larger relative to the city's footprint. The Santa Monica ADU Guide states that when a parcel is in the Coastal Zone, a Coastal Development Permit or Waiver may be required through the California Coastal Commission — a separate track from the ministerial ADU building permit.
  • Strictest short-term rental rules in LA County. SMMC Chapter 6.20 prohibits vacation rentals outright. Home-sharing is allowed only when the host is present. The Airbnb-income calculus that works in the rest of LA does not work here.

What you can build in Santa Monica

The numbers below come directly from the City's official ADU and JADU Guide — Parcels with a Single-Unit Dwelling (Santa Monica CDD, November 2025) and SMMC § 9.31.025. On several standards — most notably height and the number of ADUs permitted per parcel — Santa Monica is more permissive than the state-law floor. On the rest, the City meets the state minimum. Homeowners may also elect to build under the State Mandated standards instead of Santa Monica's standards where that produces a better result.

Number of ADUs per parcel — Santa Monica allows up to four units on an R1 lot

The Guide allows all of the following on a parcel with a Single-Unit Dwelling, in combination:

  • One converted ADU — carved out of the existing or proposed SUD, an attached accessory structure (like an attached garage), or a detached accessory structure.
  • One JADU — within the SUD footprint, ≤ 500 sqft, deed restricted.
  • One detached ADU — a new free-standing structure.
  • One attached ADU — an additional attached ADU on parcels in the R1 Zoning District (requires a deed restriction).

On an R1 lot that can mean up to four dwelling units total (the primary home plus the combinations above), which is materially more generous than the state-law floor of one ADU plus one JADU. On multifamily parcels, Gov. Code § 66323(c) (as amended by SB 1211, 2024) independently allows up to eight detached ADUs.

Maximum size

  • Studio or 1-bedroom: up to 850 sqft.
  • 2-bedroom or more: up to 1,200 sqft.
  • Minimum: 150 sqft of floor area.
  • JADU: up to 500 sqft, per Gov. Code § 66333 and SMMC § 9.31.025.
  • Conversion of an existing SUD: total ADU floor area may not exceed 50% of the existing primary dwelling or the maximum size limits above, whichever is less — but the Guide expressly guarantees a minimum of 800 sqft regardless. The 800-sqft floor is what makes a conversion on a small primary dwelling still viable.
  • Conversion of an existing detached accessory structure: limited to the existing floor area, with expansion permitted up to the maximum size caps if all other standards are met.
The Melrose Signature Home — 2 BR / 2 BA, 800 sqft, Spanish flat-roof exterior — coastal aesthetic for Santa Monica lots
The Melrose — 2 BR / 2 BA, 800 sqft, Spanish flat-roof exterior. Sits well under Santa Monica’s 1,200 sqft cap for 2+ bedroom ADUs (SMMC § 9.31.025) and matches the coastal Mediterranean aesthetic.

Maximum height in Santa Monica: 2 stories, 24 feet by right

  • Detached ADU — 2 stories or 24 feet by right. This is the Santa Monica standard (SMMC § 9.31.025, ADU Guide p. 9). It is taller than the 16-foot and 18-foot floors state law (Gov. Code § 66321) requires every California city to allow. If you want two stories on a detached ADU in Santa Monica, you can have them without variance or discretionary approval.
  • ADU within an existing or proposed SUD: the underlying zoning district's height limit for the primary dwelling applies.
  • Attached ADU (R1 zone): the underlying zoning district's height limit for the primary dwelling applies.
  • Height is measured per SMMC § 9.04.050 (Measuring Height). Most flat parcels use Average Natural Grade (ANG). Two-story or sloped-parcel ADUs require a land survey with the building-permit application.

Setbacks and separation

  • Side and rear setbacks: 4 feet.
  • Front setback: ADUs are not permitted within the required front setback of the underlying zoning district.
  • Separation from the primary dwelling: 4 feet minimum between a detached ADU and the primary dwelling, measured between exterior walls. Unenclosed access features like exterior stairs may intrude into that 4-foot separation.
  • No setback required for an ADU that reuses an existing living area or accessory structure, or for a structure rebuilt in the same location and to the same dimensions — including existing unpermitted structures built before January 1, 2020 being converted into an ADU (AB 2533, 2024).

Parking

  • On-site parking is not required. Per the ADU Guide and SMMC § 9.31.025, there is no on-site parking requirement for an ADU or JADU. That is independent of the transit-proximity and car-share exemptions in Gov. Code § 66314(d) and AB 2097 (2022) — Santa Monica simply does not impose the requirement in the first place.
  • No replacement parking required. When a garage or parking area is used to establish the ADU, the eliminated parking need not be replaced. SB 1211 (2024) separately eliminated replacement parking for uncovered off-street spaces at the state level.
  • Coastal Zone caveat. Parcels within the Coastal Zone should confirm parking rules directly with the California Coastal Commission — the ADU Guide flags this on every parking row.
The Sunset Signature Home — 1 BR, 480 sqft, modern flat-roof exterior — coastal modern aesthetic for Santa Monica lots
The Sunset — 1 BR, 480 sqft, modern flat-roof exterior. Compact enough for any Santa Monica walk-street or alley-fronted lot, with no on-site parking required (SMMC § 9.31.025).

Development fees

State law (Gov. Code § 66318) prohibits impact fees on any ADU under 750 sqft and caps fees on larger ADUs at a share proportional to the primary dwelling. You will still pay standard building-permit and plan-check fees — which are based on project valuation, not on the fact that you are building an ADU — and utility connection fees where required.

Owner-occupancy

You do not have to live on the property to build or rent an ADU. Gov. Code § 66315 bars Santa Monica from imposing an owner-occupancy requirement on an accessory dwelling unit. A junior ADU is the one exception — and a narrow one after AB 1154 (effective January 1, 2026), which amended Gov. Code § 66333 so the requirement reaches only a JADU that shares sanitation facilities with the primary home. Give the JADU its own bathroom and owner-occupancy no longer applies. The JADU still records the deed restriction prohibiting separate sale (SMMC § 9.31.025).

The dual-track option: state standards as an alternative

The Guide repeats a sentence on every section — converted ADU, JADU, detached ADU, and R1 attached ADU — that is worth reading carefully: "Alternative to the above Santa Monica standards, ADUs may be established ... with the State Mandated standards as set for in SMMC Section 9.31.025." Translation: if the Santa Monica standard is more restrictive than state law in a given situation, you can elect to build under the state-mandated standard instead. We run the numbers both ways on every project before choosing.

Coastal Zone permits for Santa Monica ADUs

The California Coastal Act (Pub. Resources Code § 30000 et seq.) designates a Coastal Zone along the state's coastline. If your parcel sits inside that zone, the City's ADU Guide states plainly: "if the parcel is within the Coastal Zone, a Coastal Development Permit or Waiver may also be required through the California Coastal Commission." That is the big distinction — coastal review is processed through the California Coastal Commission, not through the City's ministerial ADU approval. The ADU building permit itself remains ministerial. The coastal overlay is separate.

Is my lot in the Coastal Zone?

The zone generally extends inland from the mean high tide line to Lincoln Boulevard, plus portions of Ocean Park and the beachfront blocks. If you are west of Lincoln, assume yes and verify. If you are east of Lincoln, assume no and verify. We confirm the coastal designation for every Santa Monica parcel before we commit to a schedule.

Two pathways: CDP or Waiver

  • Coastal Development Permit (CDP). Required for a new detached ADU in most Coastal Zone contexts — a new structure with its own footprint, roofline, and use is "development" under the Coastal Act.
  • CDP Waiver. Projects the Coastal Commission determines are consistent with the Local Coastal Program but do not rise to full CDP review may qualify for a waiver. Interior conversions and same- footprint/same-dimension rebuilds often fit here.

The ADU Guide also calls out parking: "If subject parcel is located within the Coastal Zone, please contact the California Coastal Commission regarding parking requirements." That is the one place Santa Monica's blanket no-parking rule may be subject to Coastal Commission conditions.

Timeline impact

Expect the coastal review to add weeks, not months, to an otherwise ministerial ADU permit. The state 60-day clock under Gov. Code § 66317 applies to the building permit itself. The coastal review runs in parallel. For higher-risk lots — beachfront, bluff-top, or in an appealable zone — we build extra float into the schedule.

Permitting your ADU in Santa Monica

  • Ministerial review, not discretionary. SMMC § 9.31.025 and Gov. Code § 66317 require Santa Monica to approve or deny a complete ADU application without discretionary review or public hearing. No design review. No neighbor notice. No Planning Commission. If your plans meet the objective standards in the ordinance, the City has to approve them.
  • 60 days from a complete submittal. Gov. Code § 66317 requires action within 60 days of a complete application. For ADUs permitted with a new primary dwelling, that clock runs with the primary dwelling's review.
  • Electronic plan review. Santa Monica uses an Electronic Plan Review System. Plans, site information, and the Hold Harmless Agreement are submitted digitally.
  • Standard plan-check fees apply. These are based on project valuation and are not the development fees state and city law exempt.

The preapproved ADU program (AB 1332)

California AB 1332 (2024) required every city to establish a preapproved ADU plan program by January 1, 2025. Santa Monica has. The program lets third-party vendors submit Standard ADU Plans for preapproval without site-specific detail; once a plan is on the approved list, homeowners select it, the vendor adds site-specific detail, and the combined submittal goes through expedited review.

CALI ADU does not participate in Santa Monica's Preapproved ADU Program. We build our Signature Homes as a full design-build package, not as inventory on a City-managed catalog. The practical difference: a preapproved plan is faster through the counter but cannot be modified; our Signature Homes are individually permitted on your lot, engineered from day one to pass SMMC § 9.31.025 on paper, and adaptable to your site's specific conditions (setback geometry, grade, utilities, existing structures). If you want the fastest possible permit on a standard lot and are willing to build a plan exactly as the City has it on file, the preapproved program is a real option. If you want a fixed-price design-build partner, that is us.

Can you Airbnb a Santa Monica ADU?

If your investment thesis depends on short-term rental income, Santa Monica is the wrong city. SMMC Chapter 6.20 (Home-Sharing and Vacation Rentals), first adopted May 12, 2015 and amended through 2019, is the strictest STR ordinance in LA County.

The City's ADU and JADU Guide states the rule in one sentence, repeated on every ADU type (converted, JADU, detached, and R1 attached): "Short-term rentals (30 days or less) are not permitted." There is no carve-out for ADUs. There is no exception for primary residence. An ADU or JADU in Santa Monica is a 30+ day tenancy, full stop.

Citywide, SMMC Chapter 6.20 (Home-Sharing and Vacation Rentals) prohibits vacation rentals outright and permits home-sharing only in a host's primary residence while the host is present. Chapter 6.20 governs the primary home; the ADU Guide governs the ADU. Both point to the same conclusion.

The practical effect: a Santa Monica ADU is a long-term rental asset (30+ day tenancies), a multigenerational space, or a home office / studio. Which is fine, because Santa Monica long-term rents are among the highest in LA County.

Why two-story ADUs work on Santa Monica lots

Santa Monica's typical single-family lot is 5,000 to 7,500 sqft. Subtract the existing house footprint, the 4-foot separation between the detached ADU and the primary dwelling, the 4-foot side and rear setbacks, and the front setback, and the footprint math for a 1,000 sqft single-story ADU gets tight fast — and eats most of your usable yard.

A two-story ADU solves the problem by stacking the program. The same 1,000–1,200 sqft fits on a footprint half the size. You keep your yard, you keep sight lines from the main house, and you comply with SMMC § 9.31.025's 24-foot / 2-story by-right detached-ADU standard — which is taller than the 16-foot and 18-foot minimums state law requires. Santa Monica is one of the few LA-area cities where the two-story detached ADU is not a variance conversation; it is the ordinance.

Three of our Signature Homes are two-story and designed specifically for this condition:

  • The Fairfax ADU — 2BR/1.5BA, 840 sqft, 448 sqft footprint. The smallest two-story option we build.
  • The Venice ADU — 2BR/2BA, 1,080 sqft, 540 sqft footprint. Our most popular two-story for Westside lots.
  • The Culver ADU — 3BR/2.5BA, 1,200 sqft, 600 sqft footprint. Sized at the ceiling Santa Monica permits for a 2BR+ detached ADU, on the minimum feasible footprint.

All three clear SMMC § 9.31.025's objective standards (24-ft / 2-story height, 4-ft setbacks, 4-ft separation) and Gov. Code §§ 66314–66323 floors. Coastal Zone parcels also run a CDP or Waiver in parallel.

The two-story Signature Home trio

Designed for Santa Monica's by-right 2-story / 24-foot envelope under SMMC § 9.31.025. Compact footprints. Fixed prices. The only productized two-story ADU lineup in LA.

The Fairfax — 2 BR / 1.5 BA, 840 sqft Signature Home ADU by CALI ADU

The Fairfax

2 BR / 1.5 BA · 840 sqft · 2-story

$339,000 all-inclusive iFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.

See model →
The Venice — 2 BR / 2 BA, 1080 sqft Signature Home ADU by CALI ADU

The Venice

2 BR / 2 BA · 1080 sqft · 2-story

$399,000 all-inclusive iFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.

See model →
The Culver — 3 BR / 2.5 BA, 1200 sqft Signature Home ADU by CALI ADU

The Culver

3 BR / 2.5 BA · 1200 sqft · 2-story

$459,000 all-inclusive iFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.

See model →

See the full two-story collection.

Recent state-law changes that apply in Santa Monica

California ADU law has been amended almost every year since 2017. Santa Monica's ordinance is required to comply with the current state statute even where the City has not formally updated its own text. The five changes that matter right now:

  • SB 1211 (2024). On multifamily parcels, up to eight detached ADUs are now allowed (up from two), not to exceed the number of existing or proposed primary units. Also eliminated the requirement to replace uncovered off-street parking lost to ADU construction.
  • AB 1332 (2024). Every city, including Santa Monica, must offer a preapproved ADU plan program by January 1, 2025. Santa Monica has.
  • AB 2533 (2024). Amnesty for unpermitted ADUs and JADUs built before January 1, 2020. Santa Monica cannot deny a permit to legalize such a unit on the basis of building code violations, provided the structure is not substandard.
  • AB 2097 (2022). No parking requirement for any residential or mixed-use project within one-half mile of a major transit stop. Most of Santa Monica qualifies.
  • AB 1033 (2023) — and Santa Monica has opted in. AB 1033, now codified at Gov. Code § 66342 (post-SB 477 renumbering from former § 65852.26), allows cities to permit ADUs to be sold separately from the primary dwelling as condominiums. Most cities have not adopted an ordinance. Santa Monica has: SMMC § 9.31.026 (Accessory Dwelling Unit Condominiums) sets the local standards. The City's ADU Guide confirms it — on both converted ADUs and detached ADUs on SUD parcels, the Guide states the unit is "permitted to be sold separately from the SUD following the standards of SMMC Section 9.31.026." That makes Santa Monica one of the few LA-area cities where an ADU-as-condo exit is actually on the table.

What an ADU costs in Santa Monica (2026)

Our Signature Homes are fixed price. Same model, same number, whether the lot is in Santa Monica, Culver City, or the Valley. Here is the lineup:

Model Configuration Size Collection Fixed price
The Wilshire Studio / 1BR 400 sqft Single-story $219KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.
The Sunset 1BR/1BA 480 sqft Single-story $239KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.
The Westwood 1BR/1BA 550 sqft Single-story $259KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.
The Laurel Canyon 2BR/1BA 660 sqft Single-story $289KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.
The Melrose 2BR/2BA 800 sqft Single-story $329KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.
The Fairfax 2BR/1.5BA 840 sqft Two-story $339KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.
The Lincoln 3BR/2BA 1,000 sqft Single-story $389KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.
The Venice 2BR/2BA 1,080 sqft Two-story $399KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.
The Culver 3BR/2.5BA 1,200 sqft Two-story $459KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign.
The Venice Signature Home — 2 BR / 2 BA, 1,080 sqft two-story traditional-gable ADU on a small Westside lot footprint, $399,000 all-inclusive
The Venice — 2 BR / 2 BA, 1,080 sqft, $399,000 all-inclusive. Two stories on a compact footprint — the Westside’s answer to small-lot density without giving up the backyard.

Fixed price. Not an estimate, not a range, not a "starting at." The number in the table is the number on the contract. We can quote it because our Signature Homes were engineered to pass Santa Monica's objective standards in SMMC § 9.31.025 — and because we control the whole stack from design to permit to construction partner.

What is not in that number: your standard Santa Monica building-permit and plan-check fees (based on valuation, payable directly to the City), utility connection fees (SoCal Edison, Southern California Gas, Santa Monica Water), and — if your parcel is in the Coastal Zone — your CDP processing fee. Your Backyard Review includes a line-item estimate of those pass-through costs for your specific lot.

For sizing and payback math: try our ADU calculator and the ROI calculator.

Renting your Santa Monica ADU

Santa Monica blocks short-term rentals (SMMC Chapter 6.20). That sounds restrictive. It actually helps owners.

Long-term rents in Santa Monica are among the highest in LA County. Supply of legal, fully-permitted detached rentals is tight. Tight supply protects pricing.

Here’s what each Signature Home rents for in Santa Monica today:

Model Config Size Fixed price Directional SM monthly rent
The Wilshire Studio / 1BR 400 sqft $219KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign. $2,800 – $3,400
The Sunset 1BR/1BA 480 sqft $239KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign. $3,200 – $3,800
The Westwood 1BR/1BA 550 sqft $259KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign. $3,400 – $4,000
The Laurel Canyon 2BR/1BA 660 sqft $289KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign. $3,800 – $4,500
The Melrose 2BR/2BA 800 sqft $329KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign. $4,200 – $4,900
The Fairfax 2BR/1.5BA (2-story) 840 sqft $339KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign. $4,300 – $5,000
The Lincoln 3BR/2BA 1,000 sqft $389KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign. $5,200 – $6,200
The Venice 2BR/2BA (2-story) 1,080 sqft $399KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign. $4,800 – $5,600
The Culver 3BR/2.5BA (2-story) 1,200 sqft $459KiFixed contract price for the Signature Home on a standard lot. Site-specific work — soil reports, utility routing, driveway, retaining walls — is identified and priced upfront, before you sign. $5,800 – $7,000

For payback math keyed to your specific lot and financing assumptions, use the ADU ROI calculator.

The Rent Control point worth knowing: Santa Monica's Rent Control Charter Amendment applies to most rental units. Newly constructed ADUs first occupied after February 1995 are generally exempt from rent-ceiling controls under the Costa-Hawkins Rental Housing Act (Civ. Code § 1954.50 et seq.). They are not, however, exempt from Santa Monica's just-cause eviction protections or from registration requirements. Confirm your specific situation with the Santa Monica Rent Control Board before you lease.

The rental rent ranges above are directional market estimates based on publicly available Santa Monica listings for comparable 30+ day rentals. They are not a guarantee. Your specific ADU's performance depends on finish level, lot, access, parking, and the rental market at the time you lease it. Ranges reflect typical market variability between a "good" and "very good" Santa Monica micro-location; truly premium blocks (e.g. north of Montana, direct beach-adjacent) can exceed the high end.

Why Santa Monica is one of the best ADU markets in LA

Between the Coastal Zone overlay, the Chapter 6.20 short- term rental rules, and the rent-control regime, Santa Monica has more regulatory complexity than most LA County jurisdictions. Why build here anyway?

  • Two-story, 24-foot detached ADUs by right. SMMC § 9.31.025 is more permissive than state law on detached-ADU height. Most LA-area cities build to the 16/18-ft state floor. Santa Monica gives you the extra story without a variance conversation.
  • Up to four dwelling units on an R1 lot. The Guide's combination rule (1 converted + 1 JADU + 1 detached + 1 attached on R1) is materially more generous than the state-law floor. That is real density — and real rental yield — on a single-family parcel.
  • ADU-as-condo is on the table. SMMC § 9.31.026 gives you a separate-sale exit under AB 1033 that most LA-area cities simply do not offer.
  • On-site parking is not required. The ordinance does not impose it. For a Westside lot where every square foot matters, that is worth five figures in design optionality alone.
  • Long-term rents are among the highest in the county. The absence of STR supply tightens the long-term rental market, which benefits legal, fully-permitted ADU owners.
  • Ministerial approval is real. If the plan meets SMMC § 9.31.025 on paper, the City has no discretion to reject it. No design review, no neighbor appeal path.
  • Property values among the most resilient in California. A fully permitted ADU adds square footage that comps directly into resale. In a market where comps are rare because turnover is low, that is real money.
  • State law backstops the city. Even when the City is slow on something, Gov. Code §§ 66310–66342 preempts. The 60-day clock under § 66317 runs. The state-mandated minimums apply.

Santa Monica ADU questions, answered

The questions Santa Monica homeowners actually ask before they start — with citations to SMMC § 9.31.025 and the City’s ADU and JADU Guide.

Does Santa Monica allow two-story ADUs?

Yes — and Santa Monica is more generous than the state floor. Per the City’s official ADU and JADU Guide (November 2025) and SMMC § 9.31.025, a detached ADU in Santa Monica may be built up to 2 stories or 24 feet tall by right. That is taller than the 16 ft / 18 ft minimums state law (Gov. Code § 66321) requires every city to allow.

For ADUs built within or attached to the primary dwelling, the underlying zoning district’s height limit for the primary dwelling applies.

Do I need a Coastal Development Permit for a Santa Monica ADU?

If your property is inside Santa Monica’s Coastal Zone (generally the area west of Lincoln Boulevard plus portions of Ocean Park and the beachfront), a new detached ADU typically requires a Coastal Development Permit (CDP) issued by the City of Santa Monica.

Conversions that do not change the building footprint or roofline — like converting an attached garage to a JADU — may qualify for a CDP waiver or exemption. The CDP is processed alongside the building permit.

How large an ADU can I build in Santa Monica?

Per the City’s ADU and JADU Guide (November 2025) and SMMC § 9.31.025: a detached ADU is capped at 850 sqft for a studio or 1-bedroom, and at 1,200 sqft for a 2-bedroom or larger. Minimum size is 150 sqft. JADUs are capped at 500 sqft.

ADUs created by converting an existing single-unit dwelling may not exceed 50% of the primary dwelling’s floor area or the size caps above, whichever is less — but a minimum of 800 sqft is guaranteed regardless.

Can I rent a Santa Monica ADU on Airbnb?

No — not as a traditional short-term rental. Santa Monica’s official ADU and JADU Guide states plainly: “Short-term rentals (30 days or less) are not permitted.”

Citywide, SMMC Chapter 6.20 (Home-Sharing and Vacation Rentals) prohibits vacation rentals outright and permits home-sharing only where the host is present throughout the stay in the host’s primary residence. The practical effect: a Santa Monica ADU is a 30+ day tenancy asset, not a nightly rental.

What are Santa Monica’s ADU setback requirements?

Per SMMC § 9.31.025 and the City’s ADU and JADU Guide: side and rear setbacks are 4 feet. ADUs are not permitted within the required front setback of the underlying zoning district.

A detached ADU must be separated at least 4 feet from the primary dwelling, measured between exterior walls — unenclosed access features like exterior stairs may intrude into that 4-ft separation. No setback is required for a converted ADU that reuses an existing living area or accessory structure, or for a structure rebuilt in the same location and dimensions — including existing unpermitted structures built before January 1, 2020.

Can a Santa Monica ADU be sold separately from the main house?

Yes. Santa Monica has opted into AB 1033 through SMMC § 9.31.026 (Accessory Dwelling Unit Condominiums). The City’s ADU and JADU Guide states — for both converted ADUs and detached ADUs on Single-Unit Dwelling parcels — that the ADU is “permitted to be sold separately from the SUD following the standards of SMMC Section 9.31.026.”

That makes Santa Monica one of the relatively few LA-area cities where an ADU-as-condo sale is actually available. JADUs may not be sold separately.

Do I have to live on the property to build a Santa Monica ADU?

No — not for an ADU. Gov. Code § 66315 bars Santa Monica from requiring owner-occupancy on an accessory dwelling unit, so you can build one and rent it whether or not you live on the lot.

A junior ADU is different, but only narrowly. After AB 1154 (effective January 1, 2026, amending Gov. Code § 66333), owner-occupancy applies to a JADU only when it shares sanitation facilities with the primary home. Give the JADU its own bathroom and the requirement does not apply.

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