The short answer
A pre-approved (or standard) ADU plan is a design your city has already checked against the building code. You still need a permit, and the city still reviews how the unit fits your lot, but plan check is shorter. Since January 1, 2025, state law has required every city and county in California to have a program for pre-approving ADU plans (Government Code § 65852.27).
For a detached ADU that uses a plan pre-approved in the current building-code cycle, the city must approve or deny a complete application within 30 days, instead of the usual 60 (§ 65852.27(b)).
Los Angeles: the ADU Standard Plan Program
Private, California-licensed architects and engineers submit designs, and the Department of Building and Safety (LADBS) pre-approves them against the building, residential and green codes. The plans belong to their designers: you buy or license one from its owner, who sets the price. The LADBS catalog listed 26 ADU plans when we checked on Sep 30, 2026, from a 280-square-foot one-story studio to a 1,180-square-foot two-story 3-bedroom unit. Most are one-story, one-bedroom designs, and at least one is a factory-built modular unit.
How to apply with one
- Pick a plan from the catalog and contact its owner for pricing and terms of use.
- Have the plan adapted to your lot: a title sheet (parcel number, zone, lot area, fire sprinklers, parking) and a plot plan showing setbacks, distance to other buildings, drainage and driveways.
- Submit a wet-stamped, signed copy of the plan with your site plans through ePlanLA, citing the plan's number (such as ADU96) in the work description.
- LADBS reviews what the plan can't: zoning, the foundation and other site conditions. Local soil may require a site-specific foundation design or engineering.
- Plan check and permit fees are based on the project's total valuation, as for any ADU.
Details are on LADBS's Standard Plan Program page.
The catalog
Each plan links to its LADBS page, which lists the owner's contact details.
| Plan | Plan owner | Size and layout |
|---|---|---|
| ADU96 | Castleblock, Inc. | 430 sq ft · 1 story, 2 bedrooms |
| ADU95 | Butterfly Dwellings, Inc. | 696 sq ft · 1 story, 1 bedroom |
| ADU94 | Butterfly Dwellings, Inc. | 1,044 sq ft · 1 story, 3 bedrooms |
| ADU93 | Butterfly Dwellings, Inc. | 702 sq ft · 1 story, 1 bedroom |
| ADU92 | Butterfly Dwellings, Inc. | 702 sq ft · 1 story, 2 bedrooms |
| ADU91 | ADU Garage Designs | 400 sq ft · 1 story, 1 bedroom |
| ADU90 | ADU Garage Designs | 400 sq ft · 1 story, studio |
| ADU89 | ADU Garage Designs | 280 sq ft · 1 story, studio |
| ADU88 | ARA-la Studio | 628 sq ft · 1 story, with a deck |
| ADU87 | Moore Land Co. LLC | 401 sq ft · 2 stories, studio |
| ADU86 | Swift Lee Office | 467 sq ft · 1 story, 1 bedroom (with a loft) |
| ADU85 | Buildoly | 497 sq ft · 1 story, 1 bedroom |
| ADU84 | Buildoly | 497 sq ft · 1 story, 1 bedroom |
| ADU83 | YD Group | 743 sq ft · 1 story, 1 bedroom |
| ADU82 | ERW Design | 695 sq ft · 1 story, 1 bedroom |
| ADU81 | HOMEIO | 600 sq ft · 1 story, 1 bedroom |
| ADU80 | YD Group | 900 sq ft · 1 story, 2 bedrooms |
| ADU79 | Cover | 512 sq ft · 1 story, 1 bedroom |
| ADU78 | Cover | 571 sq ft · 1 story, 1 bedroom |
| ADU77 | Cover | 870 sq ft · 1 story, 2 bedrooms |
| ADU76 | Mei Li Homes LLC | 400 sq ft · 1 story, 1 bedroom |
| ADU75 | YD Group | 1,180 sq ft · 2 stories, 3 bedrooms |
| ADU74 | Bright Space LLC | 750 sq ft · 1 story, 1 or 2 bedrooms |
| ADU72 | Infinity Concept Inc. | 1,080 sq ft · 1 story, 3 bedrooms |
| ADU71 | Plús Hús | 438 sq ft · 1 story, 1 bedroom |
| YOU-ADU | YOU-ADU | 455 sq ft · 1 story, 1 bedroom |
Plan owners set prices and terms; LADBS approval isn't an endorsement.
Of these, permit records name ADU76 (2 permits), ADU77 (2 permits), ADU75 (1 permit) and ADU78 (1 permit); no permit we found names the others. Many permits built from a standard plan don't name it, so these counts are a floor.
What the permit records show
At least 70 detached ADU permits Los Angeles issued from 2021 through Oct 31, 2026 cite a standard or pre-approved ADU plan, 41 of them for factory-built units. Their median time from application to permit was 120 days, against 209 days for other detached ADUs permitted in the same years. With most of them factory-built, the comparison mostly reflects factory-built plans. Treat this as a rough guide, not a controlled comparison: many permits built from a standard plan don't name it, and the ones that do are a small group.
Most permits that name a plan cite ones no longer in the catalog, from earlier rounds of the program: ADU30 (20 permits, factory-built), ADU29 (19 permits, factory-built) and 11 others with 1 to 3 permits each.
Ventura County, city by city
| City or area | Pre-approved plans |
|---|---|
| Unincorporated Ventura County | Three free detached plans: 1 bedroom (700 sq ft), 2 bedrooms (900) and 3 bedrooms (1,188), with reduced review fees and time. Finishes can change; size and layout can't. |
| Ventura | The same three sizes, free, with reduced fees and review time. |
| Moorpark | Standard plans of 700, 900 and 1,188 sq ft. Fire, water and sewer, school district and site approvals are still needed, and they can't go in a floodplain or on a slope. |
| Oxnard | Accepts plans pre-approved by Ventura County's and San Diego County's programs; review is shortened to 30 days, but plan check fees aren't reduced. |
| Thousand Oaks | An ADU plans gallery that includes pre-approved plans, bought or licensed from the designer; every plan still needs site planning. |
| Ojai | One free pre-approved one-bedroom plan in three styles (ranch, Spanish, traditional). |
| Santa Paula | Six plans are posted, marked as drafts only for now. |
| Camarillo | No pre-approved plans listed on the city's ADU page; ask the city. |
| Fillmore | No pre-approved plans listed on the city's ADU page; ask the city. |
| Port Hueneme | No pre-approved plans listed on the city's ADU page; ask the city. |
| Simi Valley | No pre-approved plans listed on the city's ADU page; ask the city. |
As each official page described its program on September 29, 2026. Programs change, so check the city's page before you choose a plan.
What a pre-approved plan doesn't cover
- Your lot. The plan still has to fit your setbacks, distance to other buildings, driveway and fire access. A design that works on one lot may not work on yours.
- The foundation and site work. Soil, grading and drainage can need their own engineering.
- Utilities. Water, sewer and electrical connections, and the utilities' own approvals.
- Fees. The plan's price goes to its designer; city permit fees, school fees and any other fees are separate.
- Changes. Altering the design can bring back full review. And a city's approval of a plan isn't an endorsement of its designer.
See also: California ADU rules, how long ADU permits take in Los Angeles, building a detached ADU in Los Angeles, choosing a licensed builder.
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