ADU Constructionin Buena Park, CA
You can build an ADU in Buena Park: the City approves a complete application without a hearing within 60 days, and a garage conversion needs no replacement parking. A new unit may reach 850 square feet, or 1,000 with more than one bedroom. The City Council amended its ADU ordinance on September 8, 2026, so confirm each number with Planning.
Most Buena Park ADU lots are ordinary single-family lots. The land was part of Rancho Los Coyotes, the town was laid out in 1887 beside the railroads and the city incorporated on January 27, 1953. The Census Bureau's 2024 estimates count 15,504 detached homes among 25,789 housing units, 60.1 percent, with another 2,398 attached, and 43.1 percent of all units date from the 1950s. On those lots the City allows one converted ADU, or one new ADU plus one junior unit.
Below you will find which version of the rules applies after this autumn's ordinance, the size and height limits, garage conversions, soft ground, fees and the Public Works permit, the fire edge beside West Coyote Hills, and the paperwork for junior units and old unpermitted ones. The City's code host returned a 403 error to our tools, so the numbers come from the City's ADU and JADU guide and Ordinance No. 1770. Confirm them with the Planning Division. Costs and the phase list are on our ADU construction page.
Buena Park Planning and Building rules that apply to ADU construction
Where adu construction permits come from in Buena Park: City of Buena Park Community Development Department, Building Division.
- Buena Park's ADU ordinance (Section 19.348.010, adopted June 2025) says a complete ADU or JADU application with site plan, floor plan, demolition plan and elevations is approved ministerially, with no discretionary review or hearing, within 60 days of receipt, and a denial must come back within 60 days with a written list of defects. Replacing a detached garage with an ADU needs a demolition permit reviewed with the ADU application.
- ADU height is 16 feet from grade, except 2 stories up to 30 feet (or the height of an existing two-story house) for an attached ADU on a single-family lot, and 20 feet for a detached ADU within one half mile of a major transit stop or high-quality transit corridor or on a multifamily lot with a multistory dwelling. New ADUs need 4 foot side and rear setbacks, a converted or same-footprint structure keeps its existing setbacks, and second-story balconies need 5 feet.
- New ADUs may not exceed 850 square feet for up to one bedroom or 1,000 square feet for more than one bedroom, the minimum is 150 square feet, and a JADU may not exceed 500 square feet. A conversion inside an existing accessory structure may expand up to 150 square feet only for ingress and egress.
- Buena Park requires one parking space per ADU (tandem on a driveway allowed) but waives it when the unit is within one half mile walking distance of public transit, in a historic district, inside the footprint of the house or an accessory building, where on-street permits are required but not offered, or within one block of a car share vehicle. Replacement parking for a demolished garage is not required.
- On a single-family lot the City allows one ADU conversion or one new ADU plus one JADU, and on multifamily lots up to two new detached ADUs on a lot being developed, up to eight on an existing multifamily lot (not exceeding the number of existing units), or conversions within existing multifamily buildings up to 25 percent of the units. JADUs are not allowed in multifamily zones.
- The ordinance bars separate sale of an ADU, sets a 30 day minimum rental term, charges proportionate park land dedication or in-lieu fees for ADUs of 750 square feet or more, and says fire sprinklers are not required in an ADU or JADU when the main house does not need them and that building an ADU alone does not trigger sprinklers in the existing house.
- JADU rules in the ordinance require owner occupancy of the house or the JADU, a recorded declaration of restrictions with the County Recorder as a building permit condition, a separate entrance and an efficiency kitchen. A garage conversion must replace a visible garage door with a wall, windows or other design consistent with the house.
- ADUs may not sit on a lot fronting a street narrower than OCFA's minimum road width standards unless one on-site space per bedroom and replacement parking are provided, or a conditional use permit is approved under Section 19.128.020.
Sources for these rules
Which ADU rules apply in Buena Park: the June 2025 guide or Ordinance 1770?
Both exist, and the newer one controls. The City's ADU guide dates from June 2025 and rests on Section 19.348.010 of its zoning code. On September 8, 2026 the City Council passed Ordinance No. 1770 by a 5 to 0 vote, and the Planning page says its zoning chapters take effect October 8, 2026. The ordinance carries the ADU updates that follow SB 9, SB 543 and AB 1154, which the Governor signed on October 10, 2025.
We read the guide in full and the ordinance only in part, since its PDF text is partly garbled, so we cannot say which numbers moved. Treat every figure below as the June 2025 guide's figure and confirm it through the Ask a Planner portal or at 714-562-3620 before a design is locked.
State clocks sit under either version. Under Government Code 66317, a city must say within 15 business days whether an application is complete, then approve or deny a complete one within 60 days or the permit is deemed approved. Buena Park's ordinance repeats the 60 days and requires a denial to list the defects in writing.
How big can an ADU be in Buena Park, and how close to the lot line?
A new ADU may not exceed 850 square feet with up to one bedroom or 1,000 square feet with more than one, the minimum is 150 square feet and a junior unit tops out at 500. New construction needs 4 foot side and rear setbacks, a converted or same-footprint structure keeps the setbacks it already has, and a second-story balcony must sit 5 feet back. A conversion inside an existing accessory building may grow by up to 150 square feet, and only for entry and exit.
Height starts at 16 feet from grade. An attached ADU on a single-family lot may rise two stories to 30 feet, or match an existing two-story house. A detached unit within half a mile of a major transit stop or high-quality transit corridor, or on a multifamily lot with a multistory home, may reach 20 feet. The Metrolink station is one stop to measure from, and the City's review decides whether a lot qualifies.
Multifamily lots count differently: up to two new detached units on a lot being developed, up to eight on an existing multifamily lot but never more than the existing units, or conversions of up to 25 percent of the units. About 4,999 Buena Park units, 19.4 percent, sit in buildings of five or more.
Garage conversion ADU in Buena Park: parking, the garage door and the demolition permit
Turning a garage into an ADU does not trigger replacement parking, and neither does tearing down a detached garage for a new unit, though the demolition permit is reviewed together with the ADU application. The City asks for one space per ADU with tandem on a driveway allowed, and waives even that within a half mile walk of public transit, inside the footprint of the house or an accessory building, in a historic district, where on-street permits are required but not offered, or within one block of a car-share vehicle.
A converted garage must lose its visible garage door. The opening becomes a wall, windows or another treatment consistent with the house. Buena Park also requires driveways and required parking areas to be concrete or decorative cement pavers, so a new tandem space cannot be gravel or asphalt.
Ask the builder how the old slab will be checked for cracks, moisture and level before any floor goes over it, and who answers for that check.
Build an ADU on Buena Park's soft soil: foundations and the soils question
The City's hazard plan says about 80 percent of Buena Park, mainly the part south of Malvern Avenue, lies on soil prone to liquefaction. The ADU guide does not say when a soils report is needed, and we found no Buena Park rule on foundation type for ADUs, so we do not claim one. A detached unit is new construction, and its engineer decides the footing and slab design.
At the first meeting, ask the designer whether the lot sits in the mapped zone, which foundation system is proposed and whether a geotechnical report is in the budget as its own line. The hazard plan also says the Norwalk Fault crosses the northeast part of the city and the Los Coyotes Fault lies near the northern boundary, which is part of why a detached unit should be engineered and not copied from a catalog.
A conversion that reuses an existing slab and walls changes far less, and the same-footprint rule lets it keep its old setbacks.
ADU fees, utilities and the Public Works permit in Buena Park
We print no City fee figures because the development fee and planning fee schedules are scanned images that would not read as text. The ordinance does say that larger units pay a proportionate park land dedication or in-lieu fee. State law adds that no impact fee may be charged on a unit of 750 square feet or less, that fees above that size must be proportional to the main house, and that utility connection charges are a separate matter.
Work in the public right of way, such as a driveway approach, parkway landscaping or a utility connection, needs a Public Works permit that can take up to three weeks, and Public Works requires a licensed contractor for it, with concrete work done by a C-8. Engineering Services answers at 714-562-3670. The City's addition handout also warns that Orange County Sanitation fees may apply to additions, so ask whether an attached unit triggers them.
Call DigAlert at 811 before any trench. A new detached ADU must carry solar panels under the Energy Code, according to the state's ADU handbook, while conversions and attached units do not.
ADU near the West Coyote Hills: fire zones and narrow streets
CAL FIRE's 2025 recommended maps put small Moderate, High and Very High zones along the northern edge of Buena Park, beside the 650-acre West Coyote Hills wildland. As we read the table, they total 36, 31 and 32 acres, and the City's hazard plan counts 173 parcels in them. We found no City ordinance adopting the map, so ask the Building Division whether a given parcel is inside a zone.
For new buildings in High and Very High zones, the hazard plan says Chapter 7A of the California Building Code requires ignition-resistant construction, and Government Code 51182 sets defensible space duties in a Very High zone. A detached ADU is a new building, so ask early whether Chapter 7A reaches it. The plan adds that a fire would not stop at a zone line, since it could run south along the Los Coyotes Country Club fairways to Malvern Avenue.
Streets count too. The ordinance bars an ADU on a lot fronting a street narrower than the Orange County Fire Authority's minimum road width unless the lot provides one on-site space per bedroom plus replacement parking, or a conditional use permit is approved under Section 19.128.020.
Matching a 1950s house, junior ADUs and old unpermitted units in Buena Park
An ADU must repeat the main house's architectural features, materials and color, from the roofing and roof design to the fascia, exterior finish, doors, windows and garage door. On a 1950s house that means a matching roof pitch, trim and window style, so ask for a written material and color list with the plans.
A junior ADU, capped at 500 square feet inside the house, needs a recorded declaration of restrictions as a permit condition, a separate entrance and an efficiency kitchen. A single-family lot gets one conversion, or one new ADU plus one junior unit. ADUs cannot be sold separately and rentals must run at least 30 days. The June 2025 guide still ties a junior unit to owner occupancy, while AB 1154 narrowed the state rule from January 1, 2026, so ask Planning which version it applies.
For a unit built before 2020 without a permit, the City lists a Substandard Housing ADU Checklist for the AB 2533 process and asks owners to call Planning first. State law, Government Code 66311.7, limits a denial for such a unit to corrections needed for a health and safety standard.
ADU photos from Buena Park and nearby homes
ADU scenes tied to Buena Park and the Orange County and Los Angeles County communities around it, from garage conversions and slabs to finished cottages. Tap a photo to enlarge it.
What adu construction costs around Buena Park
The sourced ranges on the ADU construction page are about $100,000 to $200,000 for a garage conversion into a studio or one bedroom, and about $200,000 to $400,000 for a new detached unit of 400 to 800 square feet. Three independent reads support them: a UC Berkeley survey of Los Angeles County projects from 2018 and 2019 that found a $100,000 median, $90,000 for garage units and $180,000 for detached ones; the Terner Center's 2020 estimate of $148,000 for Los Angeles; and a $178,536 job cost in Remodeling magazine's 2025 Cost vs. Value report, which recouped 39.9 percent at resale. None is a Buena Park quote and we found no Orange County ADU survey, so permit, plan check and connection charges appear as separate lines in a written proposal. The ADU cost guide covers what moves the price, and the ADU versus JADU guide compares the two unit types. Cypress and Stanton have no page on our site yet, so compare ADU construction in Fullerton, Anaheim, La Mirada and Los Angeles. A bath inside the unit is on our Buena Park bathroom page, an attached addition on the Buena Park room addition page, new glass on the Buena Park window page, and the Buena Park 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 |
Buena Park ADU questions, answered
Can I build an ADU in Buena Park?
Yes. The City approves a complete ADU or JADU application without a hearing, within 60 days of receipt, and a single-family lot may have one conversion or one new ADU plus one junior unit. The ordinance was amended on September 8, 2026, so confirm lot-specific numbers with the Planning Division before design starts.
How do I build an ADU in Buena Park, step by step?
Check zoning and the fire map, then draw a site plan, floor plan, demolition plan and elevations, which are what the City lists for a complete application. Planning approves it ministerially, the Building Division issues the permit, and inspections follow. The City's free Plan PreCheck can flag corrections first. Plans are accepted in person, Monday through Thursday.
How big can an ADU be in California?
State law lets a detached ADU reach 1,200 square feet and bars a city from capping new units below 850 square feet, or 1,000 with more than one bedroom. Buena Park's guide sets 850 and 1,000, with a 150 square foot minimum and a 500 square foot junior unit. Confirm after the ordinance changes.
How much does it cost to build an ADU in California?
Plan on about $100,000 to $200,000 to convert a garage and $200,000 to $400,000 for a new detached unit of 400 to 800 square feet. The ranges come from Los Angeles-area data because no Buena Park or Orange County survey turned up, and City fees show as separate lines in a written proposal.
Do I need to provide parking for my ADU?
Often not. Buena Park asks for one space per ADU, tandem on a driveway allowed, but waives it within a half mile walk of transit, inside the house or an accessory building, in a historic district, where on-street permits are not offered to the unit, or near a car-share vehicle. Garage replacement parking is never required.
What is the difference between an ADU and a JADU?
A JADU is a unit of up to 500 square feet built inside the existing house, with a separate entrance and an efficiency kitchen, while an ADU is a full separate unit that can be attached, detached or converted. A junior unit needs a recorded restriction with the County Recorder as a permit condition.
Can I convert my garage to an ADU?
Yes, and the City does not require replacement parking. The garage door must be replaced by a wall or windows that match the house, the structure keeps its existing setbacks, and a demolition permit is reviewed alongside the application if the garage comes down. Ask about slab condition before a floor goes in.
Can I sell my ADU separately from the main house?
No. The ordinance bars separate sale of an ADU, and state law allows exceptions only for a qualifying nonprofit sale to a low-income buyer or a city-adopted condominium ordinance. We did not find a Buena Park condominium ordinance for ADUs in the City's pages. Rentals must run at least 30 days.
How long does it take to get an ADU permit in Buena Park?
The City must approve or deny a complete application within 60 days, and state law adds a 15 business day completeness check, so a clean submittal should be decided in under three months if the clocks run as written. We found no published average, and plans can only be filed in person Monday through Thursday.
Tell us about your Buena Park ADU
Tell us whether you have a garage to convert or a yard for a new unit, which part of Buena Park the lot is in and roughly when the house was built, and the first visit starts there.