California
Modular homes for California projects
Wolf builds and delivers modular homes for select California projects, and they take more work than a Washington or Oregon job. Title 24 adds its own energy review, and the Title 24 filing must list an outside contractor. We don’t have a standing HCD-approved model, so the drawings for each California home go through HCD approval on their own. You also need a qualified local contractor for the site work, and lining one up is part of planning the project. We price and schedule each California home on its own. We have delivered homes to Santa Rosa and Petaluma in Sonoma County and to St. Helena in Napa County.
Additional requirements for a California project
Title 24 energy
California’s Building Energy Efficiency Standards (Title 24, Part 6) require a separate energy review and set of forms. For Wolf projects, the filing must list an outside contractor. Bringing that contractor in adds coordination and time before the plans can be approved.
California Energy Commission standards ↗HCD factory approval
A Wolf home is modular IRC/IBC (International Residential Code / International Building Code), not HUD (the federal standard for manufactured homes) manufactured. California approves factory-built plans through HCD, and the review covers the Title 24 energy calculations. We don't have a standing HCD-approved model, so the drawings for each California home go through approval on their own. That approval has to be in hand before the local building department can permit the home for installation.
California HCD inspections and approvals ↗Local site work
Our crews don't do site work in California, so the foundation, utilities, and finish work go to a local contractor. Finding a qualified one who has worked with modular homes takes time, so it’s worth starting that search early. We still handle the home, permitting, and delivery. Final pricing follows a review of the property and local requirements.
Where we’ve delivered in California
We built homes in Santa Rosa and Petaluma in Sonoma County after the 2017 fires. In St. Helena, up in Napa County, a narrow winding driveway meant splitting a 616 sq ft home into four pieces for delivery. See the St. Helena project.
Sonoma, San Jose, and Los Angeles
A California address can sit in a city or in the unincorporated county, and those are different permit counters. The notes below are the published ADU (accessory dwelling unit) rules for Sonoma, San Jose, and Los Angeles. Title 24 and HCD approval still apply on top of them.
Sonoma
A Sonoma mailing address can be the City of Sonoma or unincorporated Sonoma County. The city and the county use different ADU codes, so the parcel map decides which packet you file.
Inside the city, SMC 19.45.040 sets the standards for an ADU that needs an ADU permit. A studio or one-bedroom unit is limited to 850 square feet. A two-bedroom unit is limited to 1,000 square feet, and the code allows no more than two bedrooms. New attached and detached ADUs need a 4-foot side setback and a 4-foot rear setback. A conversion of existing living space, or of an accessory structure rebuilt in the same place and to the same dimensions, does not take a new setback. Front and street-side setbacks follow the zone, unless those setbacks would block an ADU of at least 800 square feet, in which case they drop to 4 feet. Lot coverage, floor-area ratio, open space, and minimum lot size also cannot be used to force the unit under that 800-square-foot, 4-foot side-and-rear floor.
In unincorporated Sonoma County, inland and outside the coastal zone, Permit Sonoma’s ADU standards (county code 26-88-060) are looser on size. The published maximum is generally 1,200 square feet, and the county says at least an 800-square-foot ADU has to be allowed when height and setbacks are met. Side and rear setbacks are 4 feet. The front setback is the base zone’s, unless it would block that 800-square-foot unit. A detached ADU is limited to 18 feet or the base zone’s accessory-structure height. There is no minimum lot size inland, but the parcel still has to meet the zoning and building code, including septic and riparian setbacks where those apply. Coastal-zone lots use a different section, 26C-325.1.
We have delivered homes to Santa Rosa and Petaluma in Sonoma County, and to St. Helena in Napa County. The St. Helena house was 616 square feet, split into four pieces for a narrow driveway. See that project.
San Jose
Inside the City of San José, the permit counter is the city’s Planning, Building and Code Enforcement department. A San Jose mailing address in unincorporated Santa Clara County is a county file. The city says an ADU is a small living unit with its own kitchen and bathroom, on a residentially zoned lot, including single-family, duplex, and multifamily properties.
The city’s ordinance archive still prints older size tables that step from about 600 to 900 square feet by lot size. The city labels those tables as not current. The document it tells you to use is the ADU Universal Checklist, which it says tracks state law and the local code. Read that checklist for the size, setback, and height that apply to the lot.
Los Angeles
A Los Angeles address can be the City of Los Angeles, another city in the county, or unincorporated Los Angeles County. City of Los Angeles building permits go to the Department of Building and Safety (LADBS). Zoning questions go to City Planning.
City Planning has posted an ADU amendment dated September 3, 2026. The file is marked draft and the ordinance number is blank, so the rules to use are the ones LADBS is applying when you file. The local contractor pulls the site permit.
On every California lot, including these three, we still don’t hold a standing HCD-approved model, the Title 24 filing has to name an outside contractor, and a local contractor does the foundation, utilities, and finish work. Send the address and we’ll say which counter it is before anyone prices a floor plan.
Tell us the California address
Send the property address. We’ll review the Title 24 and HCD requirements, along with the expected schedule and cost, before recommending a floor plan.
Prefer a Washington or Oregon lot instead?
Wolf provides turn-key service in Washington and Oregon, where our own crews handle the site work.
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