Detached ADU Construction
A standalone cottage at the back of the lot, up to two stories under Santa Monica's local rules, with its own entry, kitchen, bath and utility connections.
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Santa Monica ADU contractor
ADU Builder in Santa Monica, California
From the wide parcels north of Montana to the wartime cottages of Sunset Park, we design, permit and construct accessory dwelling units, and we cover the Los Angeles neighborhoods along the city line too.
4 ftMost a city can require for ADU side and rear setbacks
60Days a city has to act on a complete ADU application
500Square feet: the size cap for a junior ADU
750Square feet: ADUs under this size skip impact fees
California ADU law (Government Code 66310-66342). Coastal, hillside and fire-zone lots can carry extra local rules.
ADU services
ADU Services in Santa Monica
Every service below can be handled on its own or as part of one design-build contract. Most clients here start with a property and one aim (a home for a parent, rental income, room for grown kids), and we match the unit type to the lot, the budget and the city's standards.
Attached ADU Construction
A unit built onto the side or rear of your house with a separate entrance, sharing one wall and often the existing sewer line and electrical service.
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Garage Conversion ADU
Turning a detached or attached garage into a legal studio or one-bedroom, with new foundation work, insulation, windows and utilities where the old structure needs them.
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Junior ADU (JADU)
A unit of up to 500 square feet carved from space inside your single-family home, with an efficiency kitchen and its own exterior door.
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Above-Garage and Two-Story ADU
Living space stacked over a new or rebuilt garage, a good fit for narrow lots where the yard is too small to give up for a cottage.
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Prefab ADU Installation
Factory-built ADU modules set on a site-built foundation, with crane logistics, utility hookups and city inspections handled by our crew.
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Multifamily ADU Construction
On duplex and apartment lots: new freestanding units plus converted storage or garage space, sized to what state law and city rules allow.
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ADU Design and Plans
Site surveys, floor plans, elevations and engineering drawn for Santa Monica's objective standards, or adapted from a preapproved city plan.
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ADU Permits and Approvals
Preparing the submittal, answering plan check comments and tracking coastal or deed restriction steps with the city or with LADBS.
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ADU Foundations and Utilities
Foundations, trenching, sewer and water laterals, electrical service upgrades and fire sprinklers where the code calls for them.
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ADU Kitchens and Bathrooms
Kitchens and baths sized for small floor plans, with ventilation, plumbing and appliance choices that pass inspection.
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Not sure which ADU fits your lot?
Tell us about the property and what you want the space for. We will reach out and talk through the options that fit your lot and local rules.
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ADU builders in Santa Monica
Accessory Dwelling Units Built for Santa Monica Lots
Santa Monica ADU Builder Pros is a design-build team for second units on the Westside. We carry an ADU from the first look at your lot through drawings, plan check, construction and final sign-off, so one group answers for the whole project. Most of our work sits inside city limits, where the Community Development Department handles ADUs. The rest is in Venice, Mar Vista, Sawtelle and Santa Monica Canyon, where the permit comes from LADBS instead.
Housing here is old and mixed. There are 1910s and 1920s Craftsman bungalows near Ocean Park, Spanish and Traditional houses on the long lots north of Montana, small one-story homes in Sunset Park that went up for aircraft workers, and duplexes and courtyard buildings across the grid. Each of those points to a different kind of unit: a new two-story cottage at the back, a garage turned into a studio, or a junior unit inside a spare bedroom.
See How We Build ADUsADU project types
ADU Project Types on Santa Monica Lots
These are the unit types that tend to fit the lots in four of the areas we serve. They describe how the property usually shapes the project, not jobs we are claiming. Every parcel gets its own review before we recommend a direction.
Two-Bedroom Detached ADU on a 50 by 150 Foot Lot
Long, flat parcels here have room for a two-story cottage near the rear line while keeping a real garden between the buildings. Santa Monica's local size cap for units with two or more bedrooms makes this the area where a family-sized ADU is most often realistic.
What is involved:
- Survey and design
- Two-story framing
- Utility trenching
- Landscape restoration
Garage Conversion Behind a 1940s Cottage
Many small postwar houses here have a detached garage at the back of the lot. Converting it keeps the yard open and reuses the footprint. Old slabs and thin walls often need upgrading, which is why we bring in structural review before the design is final.
What is involved:
- Foundation check
- Insulation
- New windows
- Panel upgrade
Above-Garage ADU on a Narrow Coastal Lot
Ocean Park lots are often tight, and some sit inside the Coastal Zone. Building the unit over a rebuilt garage saves ground space. The coastal status of the parcel is confirmed first, since it can add a Coastal Commission permit or waiver.
What is involved:
- Coastal Zone check
- Structural design
- Stair layout
- Plan check
Detached ADUs on an Existing Apartment Lot
Sawtelle mixes small houses with older apartment buildings. On a multifamily lot, state law allows several detached units plus conversions of storage or garage space, with permits issued by the City of Los Angeles rather than Santa Monica.
What is involved:
- Unit count review
- LADBS permits
- Sewer capacity
- Tenant coordination
Santa Monica Lets an ADU Be Sold as a Condominium
State law allows ADUs to be sold apart from the main house only where a city has adopted its own ordinance. Santa Monica did, in Municipal Code Section 9.31.026. That changes how some owners think about the project: the unit can be a long-term rental, a home for family, or later a separate property with its own title. The condo path has its own requirements, so we flag it during design.
How ADU permits work in Santa MonicaSanta Monica ADU Process, Step by Step
The order rarely changes, though the time each stage takes depends on the lot, the design and how complete the submittal is. Here is how a typical Santa Monica ADU moves from first conversation to keys.
01
Lot Review and ADU Design
We look at zoning, the Coastal Zone map, setbacks, the alley and utility locations, then draw a layout that fits your goal. You pick between a custom plan and a city preapproved plan before engineering begins.
02
Santa Monica ADU Permit and Plan Check
We submit to City Planning and Building and Safety, or to LADBS for Los Angeles parcels. State law gives the city 15 business days for its completeness call, then 60 days to rule on a complete file.
03
Construction and Final Inspection
Demolition, foundations, framing, rough utilities and finish work are done by our crew, with city inspections at each required stage. Final inspection closes the permit, and then the unit can be occupied or rented.
Why build an ADU in Santa Monica
Why an ADU Makes Sense in Santa Monica
Santa Monica handles ADUs ministerially. Municipal Code Section 9.31.025 sets the rules, and a project that meets them needs a building permit and nothing more: no design review board, no public hearing, no neighbor appeal. In a city where other residential work can stall in review, that clear path is a big part of the appeal.
Some local standards also go past what state law requires. A detached unit may rise two stories and 24 feet, and a design with two or more bedrooms can reach 1,200 square feet. The city does not ask owners to live on the property, and it has a separate ordinance that lets an ADU be sold on its own as a condominium.
- No on-site parking required for the new unit
- Detached ADUs up to two stories and 24 feet
- Owner occupancy not required to build or rent
- A local path to sell the ADU as a condominium
- Rentals must run longer than 30 days
Santa Monica Lot Types, Alleys and ADU Rules
Most of the city is flat and laid out on a regular grid, and many blocks are served by a rear alley. That alley is often the most useful thing on the property. It can give a backyard unit its own front door, a route for utility trenches and a way to bring in lumber without crossing the front lawn. Where there is no alley, we plan the side-yard path early, since a four-foot setback leaves little room for a crew.
Lot size shapes the answer. A roughly 7,500 square foot parcel north of Montana can hold a full two-bedroom detached unit and still keep a usable yard. Narrower lots in Ocean Park and the Pico neighborhood often do better with a converted garage or a second floor built over one. A single-unit lot may combine a converted ADU, a JADU and a detached ADU, and R1 lots can add one more unit if a deed restriction is recorded.
Two overlays can add steps. Parcels in the Coastal Zone, mostly toward the beach, may need a Coastal Development Permit or a waiver through the California Coastal Commission on top of the city permit. Homes listed on the California Register of Historical Resources can face extra standards. A house that is merely old, or locally admired, is not caught by that rule unless it carries that listing.
Santa Monica ADU Cost: What Moves the Number
Prices are not posted here, because two units of the same size in this city can end up far apart. The largest swing is between reusing a structure and starting fresh. A garage conversion keeps the slab, walls and roof, though a 1940s garage often needs a new foundation and reframing once the engineer looks closely. A new detached cottage starts from dirt and carries every system with it.
Utilities come next. Inside city limits, water and sewer service come from the City of Santa Monica and power from Southern California Edison. A new unit may need a bigger electrical panel, a new service drop, or a long sewer lateral out to the main in the street or alley. How far the unit sits from those connection points, and whether trenching runs under old trees or paving, moves the figure.
The rest is choice. Bedroom count, a second story, window area, kitchen and bath finishes, and whether you start from a plan in the city's Preapproved ADU Program or a custom design all change the budget. Fees are part of it too. Under state law, units at or below 750 square feet carry no impact fees, so it can pay to talk about square footage before anyone draws a line.
Santa Monica service areas
ADU Builders Across Santa Monica and the Westside
Our work covers all six residential neighborhoods inside the city: North of Montana and Wilshire Montana, Mid-City and Pico, Ocean Park and Sunset Park. Across the line, we take projects in Santa Monica Canyon, Venice, Mar Vista and Sawtelle, where LA's ADU ordinance and LADBS apply. Pick your area below for notes on its lots and permit path.
Santa Monica area
ADU Builder in Pico
See Pico
Santa Monica area
ADU Builder in Ocean Park
See Ocean Park
Santa Monica area
ADU Builder in Sunset Park
See Sunset ParkFAQs
Santa Monica ADU Questions
Is owner occupancy required for a Santa Monica ADU?
No. The city does not require owner occupancy for an ADU, and state law bars cities from adding that condition. The one exception involves junior ADUs: if a JADU shares a bathroom with the main house, the owner must live in one of the two.
Can I rent my Santa Monica ADU as a short-term vacation rental?
No. Santa Monica does not allow ADUs to be rented for 30 days or less. Longer rentals are fine, and many owners rent to a single tenant on a lease or house a family member instead.
How quickly can a Santa Monica ADU permit be issued?
It depends mostly on how complete the drawings are. Since 2026, the city has 15 business days to tell you whether an application is complete, and once it is, state law gives 60 days to approve or deny it. Coastal Zone parcels can add a separate Coastal Commission step.
Do I need to add parking for an ADU in Santa Monica?
No on-site parking is required for an ADU in the city, and garage spaces lost to a conversion do not have to be replaced. If the garage served a rent-controlled apartment, the city points owners to the Rent Control Department about possible rent adjustments.
Does an ADU trigger a property tax reassessment?
Only on the part you add. The house keeps its existing assessed base, and the assessor values the new unit and adds that amount on top. A tax professional can estimate the figure for your parcel.
Can I sell my ADU separately from my house in Santa Monica?
Yes, under the city's ADU condominium ordinance in Municipal Code Section 9.31.026. That route involves a condominium map and its own requirements, so it should be planned from the start rather than added later.
How do I know if my Santa Monica lot is in the Coastal Zone?
The city's zoning maps show the Coastal Zone boundary, and we check it during the first lot review. Parcels inside it may need a Coastal Development Permit or a waiver from the California Coastal Commission in addition to the building permit.
ADU consultation
Get Santa Monica ADU Options for Your Property
Describe the parcel, what stands on it now and who the new unit is for. Within 24 hours of the form landing, we phone or email to go over what fits.
- Design
- Permits
- Construction