On single-family residential lots in San Jose, you can build one ADU (attached or detached) and one Junior ADU (JADU). The JADU must be created from existing space within the primary residence and cannot exceed 500 square feet. Your lot must be zoned R-1, R-2, R-M, or PD, or be designated in the General Plan for residential or mixed-use development.

Duplex and multifamily properties in San Jose can build up to two detached ADUs. A duplex may also add an attached ADU. For larger multifamily buildings, you can convert existing non-livable space (such as storage areas or garages) into ADUs—up to 25% of the existing unit count. For example, a 12-unit building could qualify for up to 3 attached conversion ADUs.

Yes, San Jose allows Junior ADUs up to 500 square feet. A JADU must be located entirely within the existing footprint of the primary residence or an attached accessory structure like a garage. JADUs may share a bathroom with the main home and only need to meet "efficiency kitchen" requirements. Note that JADUs have an owner-occupancy requirement—you must live on the property if you build a JADU.

San Jose does not have a separate guest quarters classification like some other California cities. Any secondary living space with a kitchen would be classified as an ADU and count toward your allowable units.

Detached ADU size limits in San Jose depend on your lot size. On lots smaller than 9,000 square feet, you can build a detached ADU up to 1,000 square feet. On lots 9,000 square feet or larger, the maximum increases to 1,200 square feet. ADUs are also subject to the rear yard coverage rule—total coverage of structures in the rear yard cannot exceed 40% of the rear yard area or 800 square feet, whichever is greater.

Attached ADUs in San Jose are limited to 800 square feet, or up to 50% of the primary residence's floor area—whichever is greater—without exceeding 1,000 square feet on lots under 9,000 square feet. Attached ADUs must share a wall or roof structure with the main residence and be separated by no more than 10 feet.

Yes. Under California state law, ADUs up to 800 square feet are exempt from lot coverage and floor area ratio (FAR) requirements. This means you can build an 800 square foot ADU even if your lot is otherwise maxed out on coverage. San Jose also waives school and parkland impact fees for ADUs under 750 square feet, which can save you $15,000 or more.

Single-story detached ADUs can be up to 18 feet tall. Two-story detached ADUs can reach 24 feet, depending on zoning. If you already have a JADU on the property, state law limits any additional ADU to 16 feet maximum. Attached ADUs follow the same height limits as the primary residence.

The minimum setback for detached ADUs is 4 feet from the rear and interior side property lines. Front yard and street-side setbacks follow the underlying zoning for your property. If your ADU is two stories or covers more than 40% of the rear yard, you must maintain the 4-foot setback. Attached ADUs follow the same setback requirements as the main dwelling.

The minimum setback for detached ADUs is 4 feet from the rear and interior side property lines. Front yard and street-side setbacks follow the underlying zoning for your property. If your ADU is two stories or covers more than 40% of the rear yard, you must maintain the 4-foot setback. Attached ADUs follow the same setback requirements as the main dwelling.

San Jose requires a minimum 6-foot separation between detached structures on the same property. Keep in mind that if structures are closer than 10 feet (eave to eave), fire codes may require special fire-rated materials on both structures, which increases construction costs.

San Jose has streamlined its ADU permitting process. The first round of building review typically takes about 20 business days for complete applications. Overall, you can expect 2-3 months from submission to permit issuance if your plans are accurate and complete. The city offers a pre-approved ADU plans program that can cut your approval time significantly by using designs that already meet city requirements.

Permit fees in San Jose vary based on your ADU's size and complexity. For a new construction ADU between 751 and 1,200 square feet, expect to pay approximately $17,000 or more for building application fees, permit issuance, and miscellaneous department fees. Smaller ADUs under 750 square feet qualify for reduced fees and are exempt from school and parkland impact fees.

San Jose does not mandate soils reports for standard ADU projects. Building surveys are also not typically required unless there are questions about property line locations. However, if your property is in a geohazard zone or has unusual site conditions, additional reports may be requested during plan review.

San Jose waives parking requirements for ADUs if the property is within half a mile walking distance of public transit—which covers most of the city. If parking is required, it cannot exceed one space per ADU. The parking space can be located within setbacks or in an existing driveway as tandem parking.

No. California state law prohibits cities from requiring replacement parking when a garage, carport, or covered parking structure is demolished or converted to an ADU. This makes garage conversions a cost-effective option since you don't need to build new parking elsewhere on your property.

If a parking space is required, San Jose allows flexibility in placement. Parking can be located in setback areas, within the front yard, or in an existing driveway as tandem parking behind another vehicle. This gives homeowners options even on smaller lots.