Garage Conversion in San Jose, CA: Cost, Permits & Rules (2026)

A garage conversion is usually the lowest-cost path to an ADU in San Jose — $100,000-$220,000, versus $180,000-$400,000 for a new detached build — because the shell already exists.

Garage Conversion Cost in San Jose

Converting an existing garage in San Jose runs $100,000-$220,000. That's well under the $180,000-$400,000 typical cost of a ground-up detached ADU, because you're reusing the foundation, walls, and roof. The biggest variables are whether the slab and framing are sound, what utility/electrical upgrades are needed, and your finish level. Permit fees add City building permit fees, FY 2026-27 Building and Structure Permits Fee Schedule, effective August 10, 2026. ADU 0-750 sq ft: permit issuance $422, plan review $1,137, inspection $1,732 (total $3,291). ADU 751-1,200 sq ft: permit issuance $633, plan review $1,950, inspection $2,520 (total $5,103). Permit issuance includes addressing assignment for the unit; inspection includes the meter release inspection. Modular fees are 10% lower for plan review and 20% lower for inspections. Separately, an optional preliminary virtual meeting with a planner is billed at the Planning Division's hourly rate of $398/hour with a 30-minute minimum (i.e. $199). These are city permit fees only and exclude school/parkland impact fees, construction taxes, and construction cost.. A converted unit rents for about $2,000-$2,800/mo (1BR) in San Jose.

The San Jose Garage Conversion Permit Process

A garage-to-ADU conversion in San Jose needs building permits even if the exterior is unchanged. Approval process: Ministerial, run through a defined six-step city process. Step 1: complete the ADU Universal Checklist (Bulletin #210) and optionally book a preliminary virtual meeting with a planner ($398/hour, 30-minute minimum). Step 2: prepare plans per Bulletin #211. Step 3: apply online via SJPermits.org and name an 'ePlan Applicant'. Step 4: upload the submittal package to SJePlans - must include Bulletin #211 plans, Bulletin #213 inspection checklist, Title 24 energy and CalGreen documents, Form 302 address assignment, Form 312 owner declaration (or Form 313 for a JADU), and a water-flow letter from the water company. Step 5: three-phase review - Prescreen (invoice for initial plan review fees), Plan Review (comment/resubmittal cycles), Issuance Review (residual plan review, inspection, school and parkland fees paid, then permit issues). Step 6: construction and inspections. Preapproved-plan projects use a separate expedited path with a dedicated City review team. Multifamily and AB 2533 legalization projects are routed through the ADU Ally team. The review timeline is The city's own published figure is that the first round of building review typically takes 20 business days, with complete and accurate plans staying within one or two review cycles. Preapproved-plan projects may receive same-day permit issuance at the scheduled plan review meeting. The 60-day figure in our record is the state ministerial deadline (Gov. Code Chapter 13 / SB 543), not a San José-published processing time, and should not be presented as a city fact. The city flags the missing water-company flow letter as a main cause of delay., with plan check: Standard review process. Pre-approved plans: Yes - a well-developed Preapproved ADU program, described by the city as the fastest and lowest-cost permit path, supported by a dedicated City review team. 6 preapproved plans from 4 vendors are currently available: Acsiom Designs (749 sq ft, 2bd/2ba); Ca2Homes (499 sq ft 2bd/1ba, 747 sq ft 2bd/2ba); J. Kretschmer Architect (748 sq ft 2bd/1ba, 476 sq ft 1bd/1ba); LiveLarge (795 sq ft 2bd/2ba). Permits may be issued the same day as the scheduled plan review meeting when site-specific documents are accurate and complete (exception: deferred structural submittals, clearances or variances take longer). Eligibility: lot must be zoned residential with an existing single-family home or duplex, and must NOT be in a geohazard, landslide, flood or Wildland-Urban Interface zone. Applicants still submit site-specific plans showing siting, utility connections and setbacks. A further 7 vendors have plans under review (including 800 and 1,000 sq ft options) that are NOT yet eligible for expedited review..

1. Confirm eligibility — ADUs are allowed in Any zoning district where the site has a legally-built, permitted main residence - single-family, duplex or multifamily. Not restricted to the named residential districts, so listing R-1/R-2/R-M/R-MH understates where ADUs are allowed. Practical gating is by property condition rather than zone: an active Code Enforcement case must be resolved before plans are accepted, and flood, geohazard/liquefaction/landslide, historic and Wildland-Urban Interface designations add design requirements or clearances rather than prohibiting the ADU..
2. Prepare conversion plans — layout, egress windows, insulation, ventilation, smoke/CO detectors, plus a kitchen and bathroom.
3. Submit for plan check — Standard review process.
4. Pull permits and build — fees run City building permit fees, FY 2026-27 Building and Structure Permits Fee Schedule, effective August 10, 2026. ADU 0-750 sq ft: permit issuance $422, plan review $1,137, inspection $1,732 (total $3,291). ADU 751-1,200 sq ft: permit issuance $633, plan review $1,950, inspection $2,520 (total $5,103). Permit issuance includes addressing assignment for the unit; inspection includes the meter release inspection. Modular fees are 10% lower for plan review and 20% lower for inspections. Separately, an optional preliminary virtual meeting with a planner is billed at the Planning Division's hourly rate of $398/hour with a 30-minute minimum (i.e. $199). These are city permit fees only and exclude school/parkland impact fees, construction taxes, and construction cost.; then framing, electrical, plumbing, and final inspection.

No Replacement Parking Required

No. California law (AB 68 / Gov Code §66314) prohibits cities from requiring replacement parking when you convert or demolish a garage to build an ADU — so you do not need to add a parking space anywhere on the lot. Owner-occupancy is not required, so you can rent the converted unit out.

The JADU Option for an Attached Garage

If your garage is attached to the house, you can convert it into a junior ADU (JADU) — capped at 500 sq ft maximum, 150 sq ft minimum. Must be built within the existing footprint of a single-family home (including converting an attached garage) or within a proposed new single-family residence, and must comply with SJMC 20.80.178. Same 500 sq ft cap under both the City and State tracks. and built within the existing walls. JADUs are cheaper and faster to permit than a full ADU, though they may share sanitation with the main home. A full ADU gives you more size and a separate unit; a JADU is the budget route.

San Jose Garage Conversion FAQ