Converting a garage into an ADU in San Jose: what to know

ADU or junior ADU?

• ADU (accessory dwelling unit): a complete, independent home with its own kitchen and bathroom. A converted attached or detached garage can become an ADU.
• Junior ADU (JADU): up to 500 square feet inside the existing house, which can include an attached garage. It needs its own outside entrance and at least an efficiency kitchen; it can share a bathroom with the main house. The owner must live in the main house or the JADU.
• Owner occupancy can't be required for a regular ADU under state law.

What California law allows

• No replacement parking: when a garage becomes an ADU, the city can't require you to replace the lost parking.
• No new setbacks: converting an existing garage within its footprint doesn't need to meet side or rear setbacks. Additions are limited to 4-foot side and rear setbacks.
• Fees: no impact fees for an ADU under 750 square feet; larger ADUs pay fees in proportion to the main home.
• Timing: the city must approve or deny a complete ADU application within 60 days.
• Fire sprinklers aren't required if the main house doesn't have them.

In San José

San José runs ADU permit services, including preapproved ADU plans from approved vendors that can shorten design and review. If your garage was already converted without a permit, the city also has a legalization program for older unpermitted ADUs and JADUs (California AB 2533). Check the city's ADU pages below for current steps and appointments.

What a garage conversion usually involves

• Making the space habitable: insulation, windows for light and emergency exit, ceiling height, and heating and cooling.
• Replacing the garage door with a wall, window or door, and raising or leveling the floor.
• Plumbing for a kitchen and bathroom, often the biggest part of the job; sewer line location matters.
• Electrical: a load calculation may show you need a panel upgrade or subpanel.
• Permits and inspections for building, electrical, plumbing and mechanical work.

Hiring a contractor

• Work of $1,000 or more needs a licensed contractor, usually a B General Building license from the CSLB. Look the license up before you sign.
• Ask who prepares the plans, who pulls the permits, and who meets the inspector.
• Get a written contract with a payment schedule tied to finished work; the down payment can't exceed 10% or $1,000, whichever is less.
• Ask for photos of garage conversions or ADUs they've finished nearby.