ADU Constructionin El Segundo, CA
ADU construction in El Segundo is allowed by right in every zone that permits housing (Municipal Code 15-4E-2), alongside an existing or proposed home. A detached unit can reach 1,200 square feet, but the R-1 zone's 0.60 floor area ratio counts the ADU. Our code text comes from a mirror that may lag, so confirm with Planning.
El Segundo has 7,889 homes, and only 3,029 of them, 38.4 percent, are detached houses, the lot type that state ADU law is written around. Another 14.4 percent sit in buildings of two to four units and 41.3 percent in buildings of five or more. The city grew from 8,011 people in 1950 to 14,219 in 1960, and the 1950s and 1960s account for 39.7 percent of today's homes, so a large share of the houses an ADU would join are more than 55 years old.
This page covers which rules decide, how big a unit can be, the floor area cap, garage conversions, apartment lots and junior ADUs, the airport noise rules, and fees and street work. The City's websites refused our tools, so the ordinance text comes from the GoCodebook mirror, which can lag later ordinances, and the City's ADU resource page and any pre-approved plan library were never opened. Confirm sizes and fees with Planning before you design. Price ranges and phases are on our ADU construction page.
El Segundo Planning and Building rules that apply to ADU construction
Where adu construction permits come from in El Segundo: City of El Segundo Community Development Department, Building and Safety Division.
- El Segundo allows accessory dwelling units by right in every zone where residential use is allowed (Municipal Code 15-4E-2). An ADU may be inside or attached to a home, inside an existing accessory structure, or detached, but only together with an existing or proposed single-family or multifamily dwelling. The certificate of occupancy for an ADU cannot issue before the primary dwelling's, ADUs cannot be sold separately except by a qualified nonprofit builder, and rentals must run 30 consecutive days or longer.
- Under Municipal Code 15-4E-3, a detached ADU in El Segundo may be up to 1,200 square feet and must sit at least four feet from interior side and rear lot lines, with the same height limit as the R-1 zone. An ADU attached to or inside the home may be up to 49 percent of the combined floor area, and the code does not prohibit an ADU of up to 850 square feet, or 1,000 square feet with two bedrooms.
- El Segundo's state-mandated ADU track (15-4E-4) permits, on a lot with a single-family home, one attached or converted ADU plus one junior ADU, with an expansion of no more than 150 square feet beyond an existing accessory structure's dimensions for access, and one new detached ADU of up to 800 square feet with four-foot side and rear setbacks that may be combined with a junior ADU.
- El Segundo must approve or deny a complete ADU building permit application within 60 days or it is deemed approved, except when the ADU is filed with a new single-family home. An ADU of 750 square feet or more pays development impact fees in an amount set by Council resolution, and a previously unpermitted ADU built before January 1, 2020 pays no impact fee (15-4E-5).
- El Segundo requires no parking for an ADU and no replacement parking when a garage or carport is converted or demolished for one. An ADU with its own exterior access from the home must have its entrance on the side or rear, not facing the front yard, and fire sprinklers are required in an ADU only when the primary dwelling requires them (15-4E-3).
- If a covenant was earlier recorded on a permitted accessory structure saying it is non-habitable, El Segundo requires the owner to record a release of that covenant with the County Recorder, in a form approved by the Community Development Director and City Attorney, before the building permit for an ADU is issued (15-4E-2(F)).
- A junior ADU in El Segundo (15-4F) must be built within the walls of an existing or proposed single-family home, with a separate entrance and an efficiency kitchen, one per lot, with the owner living in either unit and a recorded deed restriction against separate sale. No added parking is required.
- On a lot with an existing multifamily building El Segundo allows ADUs converted from non-livable space (storage rooms, garages, attics, basements) up to 25 percent of the existing units, and up to eight detached ADUs but no more than the number of existing units. A lot with a proposed multifamily building may have two detached ADUs (15-4E-3 and 15-4E-4).
Sources for these rules
Can you build an ADU in El Segundo, and which rules decide?
Yes. Municipal Code 15-4E-2 allows accessory dwelling units by right in every zone where residential use is allowed, whether the unit sits inside a home, attaches to it, converts an existing accessory structure or stands alone, as long as a single-family or multifamily dwelling exists or is proposed. Three conditions follow the unit: its certificate of occupancy cannot issue before the main dwelling's, it cannot be sold separately except by a qualified nonprofit builder, and rentals must run 30 consecutive days or longer.
Two rulebooks run side by side. The City's ordinance sets local standards, the state's ADU statute (Government Code sections 66310 to 66342) sets the floor, and a local rule that conflicts with it gives way. El Segundo's state-mandated track in 15-4E-4 covers the cases a city cannot refuse. The clocks tightened on January 1, 2026 under SB 543: the City must tell you within 15 business days whether a filing is complete, and a complete application on a lot with a home is deemed approved if it gets no answer within 60 days. The City's own code repeats the 60 days, except when the ADU is filed together with a new single-family house.
How big can an ADU be in El Segundo? Detached, attached and state-protected sizes
Under 15-4E-3 a detached ADU may be up to 1,200 square feet and must sit at least four feet from interior side and rear lot lines, with the same height limit as the R-1 zone, which is 32 feet and two stories under a pitched roof or 26 feet under a flat one. An ADU attached to or built inside the home may be up to 49 percent of the combined floor area. The code does not prohibit a unit of 850 square feet, or 1,000 with two bedrooms.
The state-mandated track in 15-4E-4 is narrower and safer to count on. On a lot with a single-family home it allows one attached or converted ADU plus one junior ADU, with at most 150 square feet added beyond an existing accessory structure for access, and one new detached ADU of up to 800 square feet with four-foot side and rear setbacks, which may be combined with a junior ADU. An ADU with its own exterior entrance from the home must put that door on the side or rear, not facing the front yard.
Does an ADU count toward El Segundo's 0.60 floor area ratio?
In the R-1 zone, yes. Section 15-4B-3(F) counts attached and detached ADUs together with the main house toward a total building area of 0.60 times the lot area, and 15-4E-3 says the home and ADU together may not exceed the lot's maximum floor area unless the ADU converts an existing structure. That puts a conversion on a different footing from a new cottage, which has to fit inside the same total as the house.
What the 0.60 counts matters as much as the number. It includes habitable attic space, accessory buildings, balconies, decks, verandas and porches, and it leaves out basements, up to 500 square feet of garage and detached accessory structures of 120 square feet or less. The second floor of the main building is capped separately at 0.25. On a 5,000 square foot lot, the minimum for lots wider than 25 feet, the ratio gives 3,000 square feet of counted area, so a 2,000 square foot house and a 1,000 square foot cottage would reach the cap before any counted deck or porch is added.
Garage conversion ADU in El Segundo: parking, entrances and the old covenant
A conversion is the least disruptive route on a lot that is already built out. El Segundo requires no parking for an ADU and no replacement parking when a garage or carport is converted or demolished for one. Fire sprinklers are required in the ADU only when the main dwelling requires them. Because a conversion of an existing structure is the case the floor area rule excuses, it also sidesteps the 0.60 arithmetic.
Two local steps catch owners. If a covenant was recorded earlier on the garage saying it is non-habitable, the owner must record a release with the County Recorder, in a form approved by the Community Development Director and City Attorney, before the ADU building permit issues (15-4E-2(F)). And when a lot abuts an alley, vehicle access must come from the alley (15-4B-7). We found no El Segundo checklist for the walls, electrical panel and bathroom a converted garage needs. Los Angeles publishes one in its bulletin P/BC 2026-150, for that city only, so ask the building division for El Segundo's list.
ADUs on duplex and apartment lots, and the junior ADU alternative
With 41.3 percent of units in buildings of five or more, El Segundo's multifamily lots matter. On a lot with an existing multifamily building, the code allows ADUs converted from non-livable space such as storage rooms, garages, attics and basements, up to 25 percent of the existing units, plus up to eight detached ADUs but no more than the number of existing units. A lot with a proposed multifamily building may have two detached ADUs (15-4E-3 and 15-4E-4).
A junior ADU (15-4F) is the small option. It must be built within the walls of an existing or proposed single-family home, with its own entrance and an efficiency kitchen, one per lot, with the owner living in either unit and a recorded deed restriction against separate sale. No added parking is required. State law ties owner occupancy to junior ADUs only where sanitation is shared, so ask which owner rule the City applies. Our ADU versus JADU guide compares the two types, and room addition versus ADU helps when the real need is a bigger house.
Building an ADU under the flight path: LAX noise rules and sound-rated glass
Inside the Los Angeles International Airport noise impact boundary, new residences and added habitable rooms must keep indoor aircraft noise at or below 45 dB CNEL under Residential Code R341, proven either by an acoustical analysis with a measurement after construction or by prescribed methods. Those methods include windows rated STC 35 to 40, a 4:12 roof on 1/2 inch sheathing, R-30 attic insulation and recirculating kitchen hoods. A new detached ADU is new construction with habitable rooms, so ask the building division whether R341 applies to your unit before you price windows and the roof.
We could not find which streets sit inside the boundary or in its 65 and 70 dB bands. The latest Los Angeles World Airports map is kept at the Building Safety counter, so bring the address. The text we read names new buildings and habitable additions, and whether a garage conversion counts as either is another question for the counter. The north end has a second issue: the City's Housing Element says the residential areas near the northern boundary are the most affected by LAX traffic, air quality and odor.
ADU fees, sewer and utility trenches, and job hours in El Segundo
State law bars impact fees on an ADU of 750 square feet or less and on a junior ADU of 500 or less (Government Code 66311.5). El Segundo's code sets impact fees by Council resolution for an ADU of 750 square feet or more, and a previously unpermitted ADU built before January 1, 2020 pays none (15-4E-5). The text we read prints no amounts, so each fee should appear as its own line in a written proposal. Utility connection and capacity charges are separate from impact fees.
Trenching for a sewer or water line under a street or sidewalk is work in the public right of way. It needs a permit under 9-2-1, a cash deposit for inspection and a bond approved by the City (9-2-2). The noise chapter's construction exemption covers only 7:00 a.m. to 6:00 p.m. Monday through Saturday, with nothing on Sundays or federal holidays, and washout water may not go into a solid waste container.
MDG Builders, CSLB #1040337, is a general contractor: we draw the unit, file the application and schedule the trades, while licensed excavation, framing, plumbing and electrical firms build it. Each of them can be asked for a license number and a certificate of insurance.
ADU photos from El Segundo and nearby homes
ADU scenes tied to El Segundo and the South Bay communities around it, from garage conversions and slabs to finished cottages. Tap a photo to enlarge it.
What adu construction costs around El Segundo
On the ADU construction page, a garage conversion to a studio or one bedroom runs about $100,000 to $200,000, and a new detached unit of 400 to 800 square feet about $200,000 to $400,000. Three independent reads sit behind those ranges. A UC Berkeley survey of Los Angeles County households that finished or applied for an ADU in 2018 and 2019 found a median of $100,000, $90,000 for garage units and $180,000 for detached ones. The Terner Center's 2020 estimate for Los Angeles was $148,000. Remodeling magazine's 2025 Cost vs. Value report lists $178,536 for an ADU in Los Angeles, with 39.9 percent recovered at resale. None is an El Segundo quote, and a lot where the 0.60 floor area cap is already close can push the design toward a conversion. The ADU cost guide and the garage conversion guide go deeper. Other cities apply state law their own way, so compare ADU construction in Manhattan Beach, Redondo Beach, Hawthorne, Inglewood and Los Angeles. A bathroom inside the unit is on our El Segundo bathroom page, a bigger attached addition on the El Segundo room addition page, and the El Segundo area page lists every trade we cover in the city.
| What it covers | Typical range |
|---|---|
| Garage conversion to a studio or one bedroom | $100,000 to $200,000 |
| New detached ADU, 400 to 800 sq ft | $200,000 to $400,000 |
| UC Berkeley survey, Los Angeles County median, 2018 and 2019 projects | $100,000 overall. $90,000 garage. $180,000 detached. |
| Terner Center and Berkeley CCI, 2020 | $148,000 Los Angeles estimate. $167,000 statewide average. |
| Remodeling Cost vs. Value 2025, Los Angeles | $178,536 job cost |
| Electrical and plumbing, Angi Los Angeles, January 2026 | Electrical $2,600 to $7,800. plumbing $3,900 to $10,400. |
| City permit and plan check fees | Not priced here |
El Segundo ADU questions, answered
Can I build an ADU in El Segundo?
Yes. Municipal Code 15-4E-2 allows ADUs by right in every zone where residential use is allowed, together with an existing or proposed single-family or multifamily home. The building permit is still required. The code text we read comes from a third-party mirror, so ask Planning for the current standards and the application checklist.
How big can an ADU be in El Segundo?
A detached ADU may reach 1,200 square feet, with four-foot side and rear setbacks, and an attached or interior unit may reach 49 percent of the combined floor area. The state-protected detached unit is 800 square feet. In an R-1 zone the 0.60 floor area ratio counts the ADU, so the lot may cap the size before the code does.
Does an ADU count toward the floor area limit?
In the R-1 zone, yes, unless the ADU converts an existing structure. Attached and detached ADUs are counted with the main house toward the 0.60 ratio, along with decks, porches and habitable attics. Garage space up to 500 square feet and accessory buildings of 120 square feet or less are excluded.
How much does it cost to build an ADU in Los Angeles County?
Our working ranges are about $100,000 to $200,000 for a garage conversion and about $200,000 to $400,000 for a new detached unit of 400 to 800 square feet. The inputs are surveys from 2018 to 2020 and one 2025 job cost, and none covers El Segundo, so only a written proposal after a site visit gives a real figure.
Do I need to provide parking for my ADU?
No. El Segundo requires no parking for an ADU and no replacement parking when a garage or carport is converted or demolished for one. Junior ADUs need no added parking either. The City does require an exterior entrance from the home to face the side or rear, not the front yard.
What is the difference between an ADU and a JADU?
An ADU is a complete, independent unit, attached or detached, while a junior ADU is built within the walls of a single-family home, with its own entrance and an efficiency kitchen, and is capped at 500 square feet under state law. El Segundo allows one junior ADU per lot and records a deed restriction against separate sale.
Can I rent out my ADU or sell it separately?
You can rent it, but El Segundo requires terms of 30 consecutive days or longer, and the ADU cannot be sold apart from the main home except by a qualified nonprofit builder. Stays shorter than that fall under separate short-term rental rules, which this page does not cover.
How long does it take to get an ADU permit?
State law gives the City 15 business days to call an application complete and 60 days to decide once it is, and El Segundo's code states the 60 days, with deemed approval if there is no answer. We found no published plan check time in practice, and a filing together with a new single-family house is outside that clock.
Do I need a permit to convert my garage into an ADU?
Yes. A garage with a kitchen and bath becomes a dwelling, which needs the ADU approval and a building permit with plumbing, electrical and mechanical work inspected. If a non-habitable covenant was recorded on the garage, a release must be recorded before the permit issues. Starting early costs an extra fee equal to the permit fee.
Can you have two ADUs in California?
Yes, in some combinations. State law lets a lot with a single-family home hold one attached or converted ADU, a junior ADU and one new detached ADU of up to 800 square feet, and El Segundo's state track repeats that. On a multifamily lot the code allows up to eight detached ADUs, but never more than the existing units.
Tell us about your El Segundo ADU plans
Tell us whether you are weighing the garage or the back of the lot, how large the house and lot are, how old the house is and whether the lot is a house lot or an apartment lot, and we will plan the first visit around the floor area count.