ADU Constructionin Manhattan Beach, CA
ADU construction in Manhattan Beach follows state ADU law plus Municipal Code Chapter 10.74, which allows up to two ADUs on a single-family lot and reviews them ministerially, with no public hearing. The ordinance text we could read is older than a reported 2025 update, so confirm sizes, height and parking with Planning before you design.
Manhattan Beach has 15,281 homes, and 10,068 of them, 65.9 percent, are single-family detached houses, the lot type that state ADU law is written around. Another 2,407 units sit in buildings of 2 to 4 units. Most of the houses come from the postwar boom that lifted the population from 6,398 in 1940 to 33,934 in 1960, and 37.3 percent were built before 1960.
This page covers which rulebook governs, how many units and how much floor area a lot can carry, garage conversions, the Coastal Zone and beach soil, the junior ADU and SB 9 alternatives, fees, and the way a job runs. The ordinance text we quote is Municipal Code Chapter 10.74 as mirrored on GoCodebook, and it reflects amendments from 2019 and 2021. A search summary of the City's own coastal permit page says the Council adopted a new ADU ordinance on April 1, 2025. The City's site refused our tools, so we could not read it, and the numbers below may have changed. Confirm them with the Planning Division. Price ranges and phases are on our ADU construction page.
Manhattan Beach Planning and Building rules that apply to ADU construction
Where adu construction permits come from in Manhattan Beach: City of Manhattan Beach Community Development Department, Building and Safety Division.
- Manhattan Beach allows a maximum of two ADUs total on a lot with a single-family home (one if the lot also has a JADU, and only one detached ADU). Studio and one bedroom ADUs may not exceed 850 square feet and larger ones 1,200 square feet, the minimum is 220 square feet, a new attached ADU may not exceed 50 percent of the existing home, a detached ADU is limited to 16 feet (26 feet above or below a detached garage), side and rear setbacks are 4 feet, and a detached ADU needs 5 feet of building separation (Municipal Code 10.74.040).
- An ADU permit is reviewed ministerially by the Director with no public hearing on the timelines in Government Code 65852.2, and a building permit is still required. ADUs also need a recorded covenant (rented 30 days or more, not sold separately), a kitchen with a permanent cooking appliance, a permanent foundation, a separate exterior entrance and alley access for a new driveway when the lot abuts an alley (Municipal Code 10.74.030 and 10.74.040).
- An ADU needs one extra off-street parking space except when it is within half a mile walking distance of transit, in a historic district, part of the existing home or an existing accessory structure, in an area where parking permits are required but not offered to its occupant, or within one block of a car share space; replacement parking is not required when a garage is converted (Municipal Code 10.74.040(F)). The ordinance text I read dates from 2019 and 2021 amendments, so state ADU law changes since then may override it.
- JADUs are limited to 500 square feet, must sit entirely within the existing or proposed single-family dwelling and need a separate exterior entry (Municipal Code 10.74.050). A new ADU needs fire sprinklers if the main house has them, but a detached ADU up to 1,200 square feet on a lot whose main house has no sprinklers is exempt from the sprinkler rule (Municipal Code 10.74.040(D) and 9.03.060).
- SB 9 projects in Manhattan Beach (Chapter 10.78): at most two primary units on an RS lot, four units total with ADUs and JADUs on a lot that has not been split, two units on a lot created by an urban lot split, new units at least 4 feet from side and rear lines, no more than 25 percent of existing exterior walls demolished unless the site has had no tenant for 3 years, and one enclosed or partly enclosed parking space per new unit except near transit or a car share vehicle.
Which ADU rules apply in Manhattan Beach: Chapter 10.74, state law or the 2025 update?
All three matter, in a clear order. State law, Government Code sections 66310 to 66342, sets the floor. The City's ordinance fills in local standards, and where it conflicts with the statute, section 66326 says the local rule gives way and the state housing department can find the ordinance out of compliance. Chapter 10.74 says an ADU is reviewed ministerially by the Director, with no public hearing, and a building permit is still required.
The clocks changed on January 1, 2026 under SB 543. The City must tell you in writing within 15 business days whether the application is complete, then approve or deny within 60 days of a complete application when a house already stands on the lot. Silence past 60 days counts as approval, and a denial must list every defect. The GoCodebook text we read predates those clocks and cites the older code sections, so quote the statute when you talk to staff.
Because the City's own pages were closed to automated reading, the one fact we cannot give you is the current local ordinance number and text. Ask Planning for the adopted version and for the ADU application checklist on the same call.
How many ADUs and how big: the two-unit cap, 850 or 1,200 square feet, and the 16 foot limit
Chapter 10.74.040 allows at most two ADUs in total on a lot with a single-family home. If the lot also has a junior ADU the total is one, and only one of the units can be detached. Studio and one bedroom units may reach 850 square feet, larger ones 1,200, and the floor is 220 square feet. A new attached ADU cannot exceed 50 percent of the existing home. Side and rear setbacks are 4 feet, a detached unit needs 5 feet from other buildings, and detached height is 16 feet, or 26 feet above or below a detached garage.
State law sets minimums that a city cannot undercut: at least 850 square feet, or 1,000 with more than one bedroom, and a protected 800 square foot detached unit with 4 foot setbacks. The state also requires a city to allow 16 feet of height. Those figures line up with the local chapter, which is why we expect them to hold, but verify against the current text.
One question stays open. Manhattan Beach's height, floor area, setback and lot standards in section 10.12.030 cannot be loosened without a city-wide vote. We left the floor area factors out because the table was unreadable in both mirrors, so ask Planning whether an ADU counts toward buildable floor area and how height is measured for a unit behind the house.
Garage conversion ADU in Manhattan Beach: parking, alley access and sprinklers
A garage conversion is the least disruptive route on a built-out lot. Under Chapter 10.74.040(F) no replacement parking is required when a garage is converted, and state law agrees, sections 66314(d)(11) and 66322. The converted unit still needs a kitchen with a permanent cooking appliance, a permanent foundation and a separate exterior entrance. Where a lot abuts an alley, the text asks for alley access for any new driveway.
Parking for the ADU itself is one extra off-street space, with exceptions: within half a mile walking distance of transit, in a historic district, inside the existing home or an existing accessory structure, where street parking permits exist but are not offered to the occupant, or within one block of a car share space. Many Manhattan Beach lots will qualify under one of those, but the transit test depends on the address.
Fire sprinklers follow the main house. A new ADU needs them if the house has them, and a detached ADU up to 1,200 square feet on a lot whose house has none is exempt under 10.74.040(D). Separately, the Residential Code amendment at 9.03.060 can require sprinklers in an existing attached garage when a remodel adds habitable area beside or above it, so ask how the City reads that for a conversion.
Building an ADU near the beach: Coastal Zone review, groundwater and sandy ground
The western edge of the city lies inside a certified Coastal Zone, about 15 percent of the points in our sample, between roughly 33.879 and 33.903 north. A Coastal Development Permit is required there unless an exemption applies, and we could not read the exemption section, so we do not claim that an ADU is exempt. State law helps on time: section 66329 says the City or the Coastal Commission must act on the coastal permit within 60 days, concurrently with the ADU. Sites between the sea and the first public road are in the appealable area.
Soil and water matter too. The state seismic layer flagged 5 of 114 sample points for liquefaction, and the County tsunami layer flagged the same 5, all along the beach edge. None of the sample points landed in a landslide zone, an active fault zone or a mapped flood plain. A 2020 Coastal Commission staff report on a basement on The Strand warned that sea level rise can raise groundwater and force dewatering. A slab, a trench for the sewer line and a garage conversion near the sand all need a soils answer first.
Check each address on the City's zoning map and the state's hazard viewer rather than relying on our sample.
ADU, junior ADU or SB 9 duplex: choosing on a Manhattan Beach lot
A junior ADU is capped at 500 square feet, must sit inside the existing or proposed single-family house and needs its own exterior entry (10.74.050). State law ties owner occupancy to junior ADUs only where sanitation is shared. An ADU has no owner-occupancy rule, though the City may require rentals of 30 days or longer and a recorded covenant that bars separate sale.
Chapter 10.78 carries SB 9. On an RS lot it allows two primary units, up to four units in total with ADUs and junior ADUs on a lot that has not been split, and two units on each lot created by an urban lot split. New units stay at least 4 feet from side and rear lines, no more than 25 percent of existing exterior walls may be demolished unless the site has been tenant-free for 3 years, and each new unit needs one enclosed or partly enclosed parking space except near transit or a car share vehicle.
Which route fits depends on how much floor area the lot can still carry. Our ADU versus JADU guide compares the two small types, and room addition versus ADU helps when the real need is a bigger house.
ADU fees, utility connections and permit deadlines in Manhattan Beach
State law, section 66311.5, bars impact fees on an ADU of 750 square feet or less and a junior ADU of 500 or less. Above 750, fees must be proportional to the main house. A unit under 500 square feet is treated as adding no assessable space for school fees. Utility connection and capacity charges are separate, but a conversion of existing space cannot be forced into a new connection. The code text we read prints no City fee amounts, so every fee should appear as its own line in a written proposal.
Permit clocks run on both sides. A plan check that produces no permit within 12 months expires, with extensions in steps of up to 180 days and never beyond two years from submittal. An issued permit lapses after 12 months without work or 180 days of suspension, and no permit lasts more than 4 years. If the work needs grading or scraping, section 10.80.010 requires a topographic survey of the site and 5 feet beyond it.
For tax, the Board of Equalization says new construction is reassessed only on the new portion, at the market value it adds, not its cost.
From application to final: hours, plans and neighbors on a Manhattan Beach ADU job
Construction is allowed 7:30 a.m. to 6:00 p.m. on weekdays and 9:00 a.m. to 6:00 p.m. on Saturdays, never on Sundays or City holidays (Municipal Code 9.44.030). In Area Districts III and IV, any work needing demolition, grading or a building permit also needs an approved Construction Management and Parking Plan and 10 days' notice to every property within 100 feet. The code text does not say which neighborhoods sit in which district, so read the zoning map for your lot.
Deliveries and hauling over the public right-of-way need a temporary encroachment permit, with 72 hours' notice for a street, lane or sidewalk closure. A green mesh fence must line any public right-of-way before demolition starts. If a neighbor's damage claim goes unrepaired, 9.44.020 triggers mandatory mediation.
MDG Builders, CSLB #1040337, is a general contractor: we draw the unit, file the application, schedule the work and walk the final, while licensed excavation, framing, plumbing and electrical firms build it. Each of those firms can be asked for a license number and a certificate of insurance. State law also bars a certificate of occupancy for the ADU from coming before the main house's, so plan the order of final inspections.
ADU photos from Manhattan Beach and nearby homes
ADU scenes tied to Manhattan Beach and the beach communities around it, from garage conversions and slabs to finished cottages. Tap a photo to enlarge it.
What adu construction costs around Manhattan Beach
The ADU construction page prices a garage conversion to a studio or one bedroom at roughly $100,000 to $200,000 and a new detached unit of 400 to 800 square feet at roughly $200,000 to $400,000. Those ranges rest on three independent reads: a UC Berkeley survey of Los Angeles County households that finished or applied for an ADU in 2018 and 2019, with a $100,000 median, $90,000 for garages and $180,000 for detached units; the Terner Center's 2020 estimate of $148,000 for Los Angeles; and Remodeling magazine's 2025 Cost vs. Value job cost of $178,536, which recouped 39.9 percent at resale. None is a Manhattan Beach quote, and coastal review, soil work and construction logistics can push a beach lot higher. The ADU cost guide and the garage conversion guide go deeper. Other cities apply the state law their own way, so compare ADU construction in Redondo Beach, Torrance, Hawthorne and Los Angeles. A bathroom inside the unit is on our Manhattan Beach bathroom page, a bigger attached addition on the Manhattan Beach room addition page, and the Manhattan Beach 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 |
Other work we manage in Manhattan Beach
Manhattan Beach ADU questions, answered
Can I build an ADU in Manhattan Beach?
Yes. Chapter 10.74 of the Municipal Code allows ADUs on lots with a single-family home and reviews them ministerially, with no public hearing, though a building permit is still required. The text we could read dates from 2019 and 2021, and a 2025 update is reported, so ask Planning for the current standards and the application checklist.
How big can an ADU be in Manhattan Beach?
In the text we read, studio and one bedroom ADUs may reach 850 square feet and larger ones 1,200, the minimum is 220 square feet, and an attached ADU cannot exceed 50 percent of the existing home. Detached height is 16 feet, or 26 feet over a detached garage. Confirm against the current ordinance.
How much does it cost to build an ADU in California?
We use 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 Manhattan Beach, so only a written proposal after a site visit gives a real figure.
Do I need to provide parking for my ADU?
Usually one extra off-street space, but not in several cases. The text we read exempts units within half a mile walking distance of transit, in a historic district, inside the existing home or an accessory structure, or within one block of a car share space, and no replacement parking is required when a garage is converted. The transit test depends on your address.
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 a unit of up to 500 square feet carved out of the single-family house with its own entry and an efficiency kitchen. Manhattan Beach applies the 500 square foot cap in Chapter 10.74.050. Our ADU versus JADU guide compares the rules side by side.
Can I rent out my ADU or sell it separately?
You can rent an ADU, and state law lets a city require terms of 30 days or longer, but it generally cannot be sold apart from the house. Manhattan Beach asks for a recorded covenant to that effect. There is no owner-occupancy rule for ADUs. Short-term rental rules are separate and we did not research them here.
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 silence past that is deemed approval. We found no published Manhattan Beach review time in practice. Building permit plan check and, on a beach lot, the coastal permit run alongside that clock.
Do I need a permit to convert my garage into an ADU?
Yes. A garage with a kitchen and bathroom becomes a dwelling unit, which needs the ADU review and a building permit with plumbing, electrical and mechanical work inspected. Starting before the permit adds a fee set by the Building Official plus a special investigation fee of up to the permit fee, per the Residential Code amendment at 9.03.050.
Can you have two ADUs in California?
Yes, in some combinations. State law lets a lot with a single-family home hold an ADU and a junior ADU converted inside the house or a garage, plus one new detached ADU up to 800 square feet. Manhattan Beach's chapter caps the total at two ADUs and allows only one detached, so ask Planning which pairing fits your lot.
Tell us about your Manhattan Beach ADU plans
Tell us the neighborhood, whether you are weighing the garage or the backyard, how old the house is and whether the lot is near the sand, and we will plan the first visit around the Coastal Zone question.