Fast, Reliable New Detached ADU Across Santa Monica
A new detached ADU in Santa Monica typically runs $285,000-$485,000 all-in, from permit set through final inspection, with most projects taking 8-14 months depending on Coastal Development Permit timelines. We dispatch from our Los Angeles office and coordinate crews locally across Santa Monica, from Ocean Park to the streets north of Wilshire. Call (213) 698-7591 to schedule your free estimate.
We’ve designed, permitted, and built ADUs in Santa Monica since 2015, and we’ve learned that this city plays by its own rules. The Coastal Zone covers nearly every residential lot here. That means a separate permit queue, separate design standards, and separate fees that don’t exist in Culver City or Venice. Our New Detached ADU team handles both the Coastal Development Permit and the standard Building & Safety review under one contract, one written price, so you’re not hiring a designer and hoping your builder can read their drawings.
Why Ellery ADU Studio Westchester Is Santa Monica’s Preferred New Detached ADU Company
We’ve completed ADU projects across Santa Monica’s distinct neighborhoods, including Sunset Park, Ocean Park, and the Pico District. Our clients here receive the same documentation we provide everywhere: a written price before any work starts (Haven Standard, Clause 1), a documented photo record on every site visit, and a 365-Day Done Right Promise backed in writing.
Response time matters when you’re holding a permit set that’s about to expire. We coordinate scheduling from our Los Angeles office and typically meet Santa Monica clients within 48 hours of initial contact. Our crews know the local streets, the parking restrictions near the beach, and which Santa Monica plan checkers ask for structural calc packages versus which ones flag landscape plans first.
Our license number appears on every page. Our crews are background-checked and uniformed. And our Free Second Opinion applies to any written estimate you’ve already received - we’ll review it against Santa Monica’s specific Coastal Zone requirements and tell you what’s missing.
Nadia Ellery built this studio in 2015, the year California’s ADU laws shifted statewide. Since then, we’ve designed, permitted, and built 900+ ADUs, every one with a written price before work started and a documented photo record when work was complete.
Our New Detached ADU Services in Santa Monica
Custom Built ADU
A custom built ADU in Santa Monica gives you full control over layout, materials, and façade design - critical here, where the Coastal Zone’s “visual compatibility” review can reject standard plans that would pass in West Hollywood or Beverly Hills. We design the permit set in-house, price every line item in writing, and build what we drew. Typical range in Santa Monica: $320,000-$485,000 all-in, depending on square footage, foundation type, and the extent of Coastal Development Permit revisions required.
Prefab ADU Installation
Prefab ADU systems from Plant Prefab and Boxabl can shorten the construction timeline, but in Santa Monica they still face the same Coastal Development Permit queue as site-built units. We specify and coordinate these brands within our single-contract model - the drawings, the CDP application, and the crane-day logistics are all our responsibility. Prefab units in Santa Monica typically run $285,000-$395,000 installed, though foundation and utility tie-in costs on older lots can push the upper end higher.
Modular ADU
Modular ADUs built off-site to California Building Code standards work well in Santa Monica’s mild climate, but the marine-layer humidity means we specify moisture-resistant sheathing and real vapor-barrier details that some modular manufacturers treat as optional. We coordinate modular delivery and set with the same permit-set rigor we apply to custom builds. Most modular ADU projects in Santa Monica fall between $295,000-$420,000.
Studio ADU
Studio ADUs - typically 300-450 square feet - are the most common detached unit we permit in Santa Monica’s tight lots, particularly in Sunset Park and north of Wilshire where setback requirements squeeze buildable footprints. A studio ADU here typically runs $285,000-$365,000. The smaller footprint doesn’t exempt you from CDP review, but it can reduce the scope of “visual compatibility” revisions if the massing stays below the primary roofline.
1-Bed & 2-Bed ADU
One-bedroom and two-bedroom detached ADUs in Santa Monica require more square footage, which means tighter setback calculations and often a full structural package for plan check. These units suit homeowners planning long-term rental income or family housing. Typical range: $340,000-$485,000. We size HVAC modestly - the coastal climate reduces heating loads - but we specify dehumidification-capable systems because the chronic humidity here is harder on finishes than cold ever is.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Santa Monica
We specify and coordinate prefab and modular systems from Plant Prefab, Boxabl, and Tuff Shed within our single-contract design-build model. For site-built shells in Santa Monica’s salt-air environment, we default to James Hardie fiber-cement siding with stainless or hot-dipped galvanized fasteners - standard galvanized hardware corrodes visibly within two years near the coast. Our Santa Monica clients receive the same brand fluency we’d apply in any coastal city, but with hardware specifications tightened for the marine layer.
Common New Detached ADU Problems We See in Santa Monica Homes
- Ungrounded wiring in 1920s-1940s garages. Most detached garages in Ocean Park, Sunset Park, and north of Wilshire still contain active knob-and-tube or early Romex with no ground. Opening walls for a new detached ADU triggers electrical upgrades that weren’t visible in the original scope. We inspect before we quote, document what we find, and price the panel and circuit upgrades in writing.
- Substandard foundations with no footings. The small detached garages common in Santa Monica’s older neighborhoods were built on 3-inch slabs with no rebar and no footing below frost line - acceptable in 1935, not today. We core-test during our initial site visit and specify a proper foundation replacement if the existing slab won’t carry the new load.
- Dry-rotted framing from marine-layer moisture. Years of fog and salt air penetrate unsealed garage framing, particularly at top plates and sill plates. We find this routinely in Santa Monica’s pre-war housing stock. Our field crew documents it with photos, stops work, and prices the repair before proceeding - no surprise invoices after walls are open.
- Coastal Development Permit triggers on “simple” projects. Homeowners assume a backyard ADU avoids CDP review. In Santa Monica, if your project alters the exterior envelope or adds visible massing in the Coastal Zone, you may face full CDP review with façade revisions. We identify this risk during preliminary design, not after you’ve paid for a permit set that won’t pass.
Pricing for New Detached ADU in Santa Monica, CA
| ADU Type | Typical Range (All-In) | Key Cost Drivers |
|---|---|---|
| Studio ADU (300-450 sq ft) | $285,000-$365,000 | Foundation condition, utility distance, CDP revisions |
| 1-Bed ADU (450-650 sq ft) | $340,000-$420,000 | Structural package, setback variances, HVAC sizing |
| 2-Bed ADU (650-850 sq ft) | $395,000-$485,000 | Full structural, potential parking replacement, coastal hardware specs |
| Custom Built ADU | $320,000-$485,000 | Material selections, façade complexity, CDP negotiation rounds |
| Prefab/Modular Installed | $285,000-$420,000 | Unit base price, foundation, crane access, utility tie-ins |
These ranges reflect Santa Monica’s specific conditions: the Coastal Development Permit layer, the independent Building & Safety queue fees, and the upgraded hardware and moisture-management specifications the marine layer demands. Every project is quoted with a written price before any work begins - Haven Standard, Clause 1 - and the scope is locked at signing. If we open walls and find conditions we couldn’t reasonably predict, we document them, price the additional work in writing, and require your signed approval before we proceed. No door-side upsells. No scope creep.
Call (213) 698-7591 for your exact quote. Estimates are free.
We Also Serve Cities Near Santa Monica
Our crews work across the Westside, including Santa Monica‘s neighboring cities: Venice to the south, Culver City to the east, Beverly Hills to the northeast, and West Hollywood to the north. Each city has its own permit office, its own fee schedule, and its own surprise conditions. We know the difference because we’ve built in all of them.
Serving Santa Monica, CA - Our Local Coverage Area
We’re based in the Santa Monica area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - New Detached ADU in Santa Monica
Yes, almost certainly. Santa Monica sits almost entirely within the California Coastal Zone, so the vast majority of new detached ADUs require a Coastal Development Permit through the city’s Planning Division before Building & Safety will issue a construction permit. This is a separate application, separate fee, and separate design-compatibility review that doesn’t exist in Culver City or unincorporated LA. We handle both the CDP and standard permit tracks under one contract. Call (213) 698-7591 to review your specific lot.
Because the original quote assumed conditions that aren’t there. In Santa Monica’s 1920s-1940s housing stock, we routinely find ungrounded wiring, cracked slabs with no footings, and moisture-damaged framing hidden behind intact drywall. At Ellery, we inspect first, write allowances into the contract, and if we find something unexpected, we stop work, photograph it, and price the repair in writing before touching it - Haven Standard, Clause 5 (No Surprises). Call (213) 698-7591 and we’ll show you exactly how our contracts handle unknown conditions.
No. Santa Monica operates its own Building & Safety Department, completely separate from the Los Angeles Department of Building and Safety. That means its own plan-check queue, its own corrections format, and its own inspectors - not LADBS’s. We’ve worked with both offices extensively and know which structural details Santa Monica’s plan checkers flag first. Call (213) 698-7591 to discuss your project’s permit path.
We specify hot-dipped galvanized or stainless fasteners, stainless flashing, and moisture-resistant sheathing on all Santa Monica builds. Standard galvanized hardware corrodes too quickly in the marine layer. We also design real vapor-management details and cross-ventilation into new shells - the chronic coastal humidity here damages finishes more than temperature extremes ever do. These specifications are written into every Santa Monica contract. Call (213) 698-7591 to review the material schedule for your project.
Often yes, but rarely “as-is.” The detached garages in Ocean Park and Sunset Park are typically 1920s-1940s structures with ungrounded wiring, substandard foundations, and inadequate head height. Opening the walls triggers code upgrades that convert the scope from a simple remodel to a near-rebuild. We assess the existing structure during our initial site visit and tell you whether conversion or tear-down-and-rebuild makes more financial sense. Call (213) 698-7591 to schedule that assessment - estimates are free.
Ready to move forward? Call (213) 698-7591 to schedule your free estimate. We’ll review your lot, explain the Coastal Development Permit path, and deliver a written price before any work starts - guaranteed under Haven Standard, Clause 1.
Written by Nadia Ellery, Owner at Ellery ADU Studio Westchester, serving Santa Monica since 2015.