The Complete San Jose ADU Requirements Guide
Building an accessory dwelling unit (ADU) in San Jose, starts with a choice: follow the city’s local development standards, or use the default rules guaranteed by the state. ADUs are self-contained living units—often a backyard cottage, garage conversion, or in-law suite—built on the same lot as a primary home. They create rental income, long-term value, and flexible space for family.
In 2024, San Jose became the first city in the country to let property owners sell backyard ADUs separately from the main residence as condominiums. Combined with streamlined permitting and a pre-approved plans program, it’s one of the most ADU-friendly cities in the state.
What follows is a breakdown of the requirements—size, setbacks, zoning, parking—and how Samara can help you get it done from start to finish.
San Jose ADU regulations at a glance
San Jose offers two permitting pathways for ADUs: you can use the city’s local development standards, or follow California’s state ADU standards—but not both. The local option allows more design flexibility in exchange for complying with stricter height and setback rules. The state option is more prescriptive but guarantees that certain units will be approved regardless of lot size or zoning limits. You’ll need to choose which track you’re using when you submit your application.
Most ADU permits are approved in three to four months.
Size and lot requirements
San Jose allows ADUs on any lot with a single-family or multifamily home. You must choose either the city’s local development standards or California’s state ADU standards when you apply. Requirements vary by type:
- Detached ADUs following local standards may be up to 1,000 square feet on lots 9,000 square feet or smaller, or up to 1,200 square feet on larger lots. One-story units are allowed up to 18 feet in height; two-story units may go up to 25 feet. There are no required side or rear setbacks, but units must be set back at least 45 feet from the front property line and may not exceed 40% of the rear yard.
- Detached ADUs following state standards can be up to 800 square feet, regardless of lot size. They’re allowed up to 16 feet in height by default, 18 feet near transit or on multifamily lots, and 20 feet if the roof pitch matches the main home. A minimum 4-foot side and rear setback is required.
- Attached ADUs following local standards may be up to 1,000 square feet on lots 9,000 square feet or smaller, or up to 1,200 square feet on larger lots. If there’s an existing home, the ADU can’t exceed 50% of the primary residence’s floor area. Height is limited to 25 feet or two stories. Attached ADUs must follow the same front, side, and rear setbacks as the main home.
- Attached ADUs following state standards must be allowed at least 850 square feet for a one-bedroom unit, or 1,000 square feet for a two-bedroom unit—even if that exceeds the 50% limit. These may be built up to 25 feet in height or to the height of the primary home, whichever is lower. State standards require 4-foot side and rear setbacks.
- Junior ADUs (JADUs) follow the same rules under both tracks. They must be 500 square feet or smaller and located entirely within the existing or proposed single-family home. JADUs must have their own entrance and an efficiency kitchen, and may share a bathroom with the main house.
Conversions of existing structures are not subject to new setback requirements. Additional safety-related standards may apply in flood, fire, seismic, or historic zones.
Meet the KurodasZoning eligibility
ADUs are allowed on any lot in San Jose that includes an existing or proposed single-family or multifamily home. JADUs are allowed only on lots with an existing or proposed single-family home, and must be built within the main residence. Additional standards may apply in overlay zones, but ADUs cannot be denied outright based on zoning or lot size. You can find case-by-case instructions in San Jose’s ADU checklist.
Number of ADUs allowed
On single-family lots, you can build one ADU and one JADU. The ADU can be detached, attached, or a conversion, and the JADU must be created within the existing home.
Multifamily lots with an existing residential building are allowed up to eight detached ADUs—or fewer if that would exceed the number of existing units—and any number of interior conversion ADUs created from non-livable space such as storage rooms or garages. Up to 25% of the existing unit count may also be converted from habitable space. If the primary building is still in development, up to two detached ADUs are allowed during construction.
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Streamline your San Jose ADU
In California, building an ADU typically costs upwards of $250,000, but it’s still far more cost-effective than purchasing another property. Even with custom upgrades and high-end finishes, total project costs often come in at less than half the price of a median California home, which reached $781,246 in 2024. Samara’s ADUs start at $147,000 before installation.
If you’re looking to build an ADU, Samara makes it easy. We handle everything from permits to installation and even offer our own financing. Call us at 650-420-2607 to schedule a 15-minute consultation and discover how simple adding a Backyard ADU can be.
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With five prefab models, Samara has an ADU for every yard.
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