ADU Constructionin Cerritos, CA
ADU construction in Cerritos follows State law, because the City's own standards are unverified: the Housing Element says ADUs are allowed by right, yet the City's second-unit guide still shows a 750 square foot, one-bedroom limit. Ask Planning which rule applies to your lot, and treat State law as controlling where they conflict.
Cerritos was dairy land until voters approved rezoning from agricultural to residential in 1965, 440 to 324, and the first tract, Stardust Homes, priced houses at $24,000 to $30,000. By April 1968, 31 tracts holding more than 2,000 homes were finished or started, which is why 77.9 percent of the city's homes now date from 1960 to 1979 and 80.4 percent are single-family detached.
ADU rules are the unusual part of this city. This page separates what the City has published from what State law requires, says plainly where we could not verify a local standard, and covers garage conversions, soils, utilities and fees. Sizes, costs and permit clocks for Southern California are on our ADU construction page, and the Cerritos overview lists our other trades here.
What the City of Cerritos says about accessory dwelling units
Where adu construction permits come from in Cerritos: City of Cerritos Department of Community Development.
- The Housing Element says that, in compliance with State law, Cerritos allows ADUs and JADUs by right on all residential sites, including multifamily and mixed-use zones. The City permitted no ADUs in 2018, three in 2019 and none in 2020, and projected three a year (24 over the 2021 to 2029 period).
- Housing Element Program 16 commits the City to amend the Cerritos Municipal Code to reflect current State ADU law, with completion anticipated by October 2024. This research found no City page showing that amendment was adopted, so which local standards apply today should be confirmed with Community Development.
- The City's Residential Permit page says the City accepts ADU plans for pre-approval (AB 1332) and sends ADU questions to Community Development at (562) 916-1201.
- The City still lists an older 'Accessory Building, Second Unit' application guide. It requires an aerial photo, plans, structural calculations, a preliminary title report, a room addition application, a legal description, a subordination agreement when there are lien holders, a recorded deed restriction, owner consent, a waste management plan and the declaration form, plus an HOA form where applicable.
- The deed restriction in that guide (citing Municipal Code 22.40.210(3)(f)) limits a second unit to 750 square feet of floor area, one bedroom and one bathroom, with its own cooking facilities. The unit may be rented but not sold or transferred apart from the main house, may not be rented for 31 consecutive days or less, and the City can revoke the permit if a breach is not cured within 30 days of written notice. These older limits come from the City's own form, so ask Community Development whether they or State ADU standards govern a given project.
- Mirror, not the official text: gocodebook.com's copy of Cerritos Municipal Code Chapter 22.40 (the City's own publisher, eCode360, blocked every fetch). Section 22.40.210(3), 'Pets and accessory residential uses', as that site summarizes it, requires a second unit permit approved by the Director of Community Development, a parcel of at least 10,000 square feet in a single-family zone, one story for a detached unit, a detached unit 10 feet from the main house, lot coverage no higher than 40 percent, one on-site parking space in addition to the house's, no garage demolition or conversion, and a deed restriction filed before a permit issues. Its adoption notes end with Ord. 911 (2006).
- Mirror, not an official source: the same site's Cerritos ADU page is an AI-assisted summary (updated September 24, 2026) that says Cerritos has not adopted a modern, state-compliant ADU ordinance, that its older second-unit section (Ord. 911, 2006) appears preempted by State ADU law, and that State standards therefore apply. The page itself says to verify with Cerritos Planning.
- The Residential Design Manual says new plans should not give ground-floor bedrooms a separate entry door, to avoid conversion to a second unit; if a separate entry is needed, a recorded covenant prohibiting a second unit is required.
Build an ADU in Cerritos: which rule set controls?
State law controls wherever it conflicts with a local rule, and for Cerritos that is most of the picture. The City's 2021 to 2029 Housing Element says that, in compliance with State law, Cerritos allows ADUs and junior ADUs by right on all residential sites. The City's residential permit page says it accepts ADU plans for pre-approval and sends questions to Community Development at (562) 916-1201.
What we did not find is a current City ADU ordinance, handout or checklist. Housing Element Program 16 promised an amendment to the Municipal Code by October 2024 to reflect State ADU law, and no City page we read shows it was adopted. Every local standard below is therefore something to confirm with Planning before design starts, and we say where each number comes from.
At the State level, Government Code sections 66310 to 66342 require ministerial approval with no hearing under section 66317, a 15 business day completeness check and a 60 day decision on a lot with an existing house, and only objective standards with no minimum lot size under section 66314.
Does the old 750 square foot second-unit rule still apply in Cerritos?
The City still posts an older Accessory Building, Second Unit application guide. Its deed restriction, citing Municipal Code 22.40.210(3)(f), limits a second unit to 750 square feet, one bedroom and one bathroom, bars rentals of 31 consecutive days or less, and lets the City revoke the permit if a breach is not cured within 30 days of written notice.
State law differs on each point. A detached ADU can reach 1,200 square feet, a city may not cap size below 850 square feet (1,000 if there is more than one bedroom), and the State-protected 800 square foot unit with 4 foot side and rear setbacks must always be allowed. Rentals may be limited only to terms of 30 days or longer. These limits sit in sections 66314 and 66321 of the Government Code.
A third-party code mirror, gocodebook.com, which is not the City's official text, summarizes section 22.40.210(3) as asking for a 10,000 square foot lot, one story, a 10 foot gap from the house, 40 percent lot coverage, an extra parking space and no garage conversion. The same mirror's ADU page says the City has not adopted a state-compliant ordinance, so State standards apply, and tells readers to verify with Planning. We could not open the City's own code publisher, so confirm any of this with Planning and treat State law as the working rule.
Does Cerritos have pre-approved ADU plans, and what else reviews them?
The City says it accepts ADU plans for pre-approval under AB 1332, but we found no published list of approved plans. Ask Community Development which plan sets exist and whether pre-approval shortens review on your lot. Every application, pre-approved or not, is filed through the Permit Hub, where an account is required.
Planning approval comes before the building permit, and the Residential Design Manual still governs how a new unit looks from the street. Building plan check follows County codes because Cerritos contracts that work to Los Angeles County. The City's agency referral page also lists outside reviews that can sit between approval and permit, including County Fire Prevention, the Sanitation Districts for new sewers or increased use, and City Public Works for off-site work.
HOAs are a separate gate. The City wants a written HOA approval form with any exterior application, and State law limits what an association can do: Civil Code sections 4751 and 714.3 void rules that effectively prohibit or unreasonably restrict an ADU on a single-family lot, as the HCD ADU Handbook explains.
Can a Cerritos garage become an ADU, and what happens to the driveway?
State law protects garage conversions. Under Government Code section 66323 a city must approve an ADU, with a junior ADU beside it, built inside an existing house or accessory structure such as a garage, with up to 150 square feet added only for entry and exit. No setbacks apply to a converted structure, and section 66314 bars replacement parking when a garage is converted. The mirror's note about no garage conversion conflicts with this, which is one more reason to ask Planning.
The driveway is where Cerritos rules still bite. The City's front yard manual allows driveways up to 25 feet wide for a two-car garage and 35 feet for a three-car garage, with a 3 foot planter at the side line, and the Residential Design Manual says a driveway may not extend beyond the garage width on the front door side. Filling the old garage opening changes the front elevation, so ask Planning early how the new wall and the front yard will be reviewed.
Sprinklers follow the same logic. Section 66314 says an ADU needs no fire sprinklers if the main house has none, and an ADU cannot trigger them in the house. A garage was built as a vehicle room, so insulation, a bathroom, electrical service and the slab are the real scope questions, and we price them after the walls are opened.
What do liquefaction and shallow water mean for an ADU slab and sewer line?
The City's Safety Element says the entire city sits in a State-mapped liquefaction zone and that perched water lies within several feet of the surface in many areas. Whether a particular lot has trouble is a question only a geotechnical report answers. That makes soils a design input for any new slab or footing, and it is why a conversion that reuses the garage slab is simpler to scope than a detached unit with new footings.
Utilities add a second review. The Sanitation Districts review new sewers or increased use, and City Public Works handles off-site work. Anything placed in the public right-of-way needs an encroachment permit, and the City's page does not say how it treats an ADU sewer lateral, so call Engineering at (562) 916-1219. Streets paved in the last five years cannot be cut, and slurry-sealed streets are protected for two (Municipal Code 12.16.330), so ask Engineering before choosing a route.
Call 811 at least two days before digging, and keep the water, sewer and electrical routes on the drawings so the trench is priced once.
What fees apply to a Cerritos ADU, and does one pay back?
State law removes impact fees on an ADU of 750 square feet or less and on a junior ADU of 500 square feet or less, and above 750 square feet the fee must be proportional to the main house (section 66311.5). Utility connection charges are separate. The City's Master Fee Schedule lists a $1,545 planning fee for a new building and $865 for a residential addition, but we could not match an ADU to a line, so we print no planning fee for one. Permit issuance is $45 for one permit or $102 for linked permits, and County plan check fees come on top.
Value is about rent and resale. The Census median gross rent is $2,930 and the median owner-occupied home is $935,300, but those are citywide figures, not ADU rents. The Housing Element shows how little ADU activity there was early on: none permitted in 2018, three in 2019, none in 2020, and a projection of three a year through 2029.
Property tax rises only on the new construction, which the State Board of Equalization assesses at the market value it adds, not at what it cost.
Who builds an ADU in Cerritos, and how long does it take?
MDG Builders, CSLB #1040337, acts as the general contractor: it designs, handles the permits and manages the build, while licensed specialty subcontractors pour the slab, frame, run the plumbing and electrical, and finish the interior. Our planning ranges are 4 to 10 weeks of design, then the State's 15 business days for completeness and 60 days for a decision, then 3 to 5 months of construction for a garage and 5 to 9 months for a detached unit.
State law also caps what a contractor can ask up front. Business and Professions Code section 7159 limits a down payment to $1,000 or 10 percent of the contract, whichever is less, and requires written change orders and a payment schedule tied to the work. Our ADU versus JADU guide explains the unit types, and the garage conversion permit steps show what Los Angeles plan check asks for, a comparison point and not a Cerritos rule.
On site, Cerritos allows construction Monday to Friday from 7 a.m. to 6 p.m. and Saturday from 10 a.m. to 5 p.m., never on Sundays or City holidays. A self-hauled project of 900 square feet or more must post a $0.50 per square foot deposit and show 50 percent diversion, and hauling with Athens Services satisfies the rule.
ADU photos from Cerritos and nearby communities
ADU and garage conversion details tied to Cerritos and nearby places such as Artesia, La Palma and Cypress, from slabs to finished studios. Tap a photo to enlarge it.
What adu construction costs around Cerritos
Regional ranges on our ADU construction page run about $100,000 to $200,000 for a garage conversion and $200,000 to $400,000 for a new detached unit of 400 to 800 square feet. Remodeling magazine's Cost vs. Value 2025 report shows a Los Angeles ADU at $178,536 with 39.9 percent recouped at resale, and the University of California, Berkeley's survey of 2018 and 2019 projects put the Los Angeles County median at $100,000. Those sources disagree, and our ADU cost guide explains why. We found no Cerritos cost study. When the lot could take either project, the room addition or ADU comparison helps, and our room addition page for Cerritos covers the other path. Nearby cities set their own local rules: see Norwalk, Lakewood and Bellflower, and Long Beach for a larger city's approach.
| 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 |
Cerritos ADU questions, answered
How big can an ADU be in Cerritos?
State law sets the floor. A detached ADU may reach 1,200 square feet, and a city may not cap size below 850 square feet, or 1,000 with more than one bedroom. The City's older second-unit guide says 750 square feet and one bedroom, but we could not confirm it still governs, so ask Planning at (562) 916-1201 and plan to State limits.
How do I build an ADU in Cerritos with no current City ordinance?
Under State law, which fills the gap. Confirm the lot's zoning and HOA with Planning, choose a conversion or a detached unit, file through the Permit Hub, and expect ministerial review with no hearing. The City says it accepts pre-approved ADU plans, so ask which exist. Where the City's old guide conflicts with State law, ask Planning in writing.
Do I need a permit to convert my garage into an ADU in Cerritos?
Yes. A garage conversion needs Planning approval first and then a building permit from Building & Safety, which the County reviews under contract. Any new plumbing, electrical or mechanical work carries its own trade permits. State law says a city must approve a qualifying conversion ministerially, without a hearing, so the review is about plans, not discretion.
How long does it take to get an ADU permit in Cerritos?
State law gives the City 15 business days to say whether an application is complete and 60 days to decide on a lot with an existing house, or it is deemed approved. A correction round adds time. The City publishes no ADU review time of its own, so ask Community Development for a current estimate.
Do I need to provide parking for an ADU in Cerritos?
Not when a garage is converted. State law bars replacement parking in that case and caps any other requirement at one space per ADU or per bedroom, whichever is less. Several exemptions also apply, such as a historic district or an ADU inside the existing house. Ask Planning which applies to your address, since the old City guide predates these rules.
Can I sell my ADU separately in Cerritos?
Generally no. State law bars selling an ADU apart from the main house, except to a qualified low-income buyer through a qualifying nonprofit or under a city-adopted condominium ordinance. The City's older second-unit guide says the same thing in its deed restriction, so a sale of the unit alone is not an option on a typical lot.
Do I have to live on the property to rent out an ADU in Cerritos?
No for an ADU. State law does not allow a city to require owner occupancy of an ADU, and a junior ADU needs it only when the bathroom is shared. A city may require rental terms of 30 days or longer. The City's older guide uses a 31 day line, so ask Planning which wording applies.
How much does it cost to build an ADU in Cerritos?
Plan on about $100,000 to $200,000 for a garage conversion and $200,000 to $400,000 for a detached unit of 400 to 800 square feet. No Cerritos study turned up, so these anchor on Los Angeles sources, and slab condition, utilities and finishes move the total. Your written proposal lists the City and County fees for your address.
Can my HOA stop me from building an ADU in Cerritos?
Not by prohibiting it. California Civil Code sections 4751 and 714.3 void association rules that effectively prohibit or unreasonably restrict an ADU or junior ADU on a single-family lot, though reasonable design rules can stand. The City also wants a written HOA approval form with any exterior application, so read your covenants early.
Is Cerritos in a flood or liquefaction zone for an ADU?
The City's Safety Element says the entire city is in a State-mapped liquefaction zone, with perched water within several feet of the surface in many areas. It found no earthquake fault zone inside the city. Plan on a geotechnical report for a new slab, and ask Building & Safety what it requires for yours.
Tell us about your Cerritos ADU idea
Send the tract or neighborhood, whether you want a garage conversion or a detached unit and whether an HOA is involved, and we will check which rules apply before we visit the lot.