Garage to ADU, JADU or living space
Garage Conversions in San Jose
QA Builders handles garage conversions in San Jose from plans to final inspection, turning attached or detached garages into ADUs or added living space for the main house, and attached garages into junior ADUs (JADUs), as one licensed general contractor (CSLB License #1073096). We take care of the permit, insulation, utilities and finishes, so you deal with one team from the first site visit to move-in.
Call (669) 213-8077 or book a consultation to find out what your garage can become.
Garage to ADU, JADU or living space: which fits your plan?
The same garage can become three different things, and the choice decides the rules, the cost and if you can rent it out.
| Garage to ADU | Garage to JADU | Garage to living space | |
|---|---|---|---|
| What it is | A separate home with a full kitchen and bathroom | A small unit of up to 500 square feet with an efficiency kitchen | More rooms for the main house: a family room, office, gym or bedroom |
| Which garage | Attached or detached | Attached only (it must sit within the walls of the house) | Attached or detached |
| Bathroom | Its own | Its own, or shared with the house (then the owner must live on the property and there must be an interior door to the main home) | Optional |
| Can it be rented? | Yes, for terms longer than 30 days (Government Code 66323(e)) | Yes, for terms longer than 30 days (Government Code 66333(g)) | Not as a separate unit |
| Separate address and meter | Address assigned; PG&E requires its own meter | Address assigned; no separate meter | No |
| Parking | Garage spaces lost to the ADU do not have to be replaced | No additional parking may be required | Zoning parking rules for the house still apply |
A JADU also needs its own entrance and a deed restriction recorded with the county, and only one is allowed per lot. Turning the garage into living space for the house is not an ADU, so the state’s parking waiver does not cover it; San Jose’s parking rules are in Chapter 20.90 of the zoning code, and a city planner can confirm what your lot needs before you design.
San Jose rules for garage conversions
San Jose permits garage conversions to an ADU or JADU through its ADU service, as “ADU Accessory Dwelling Unit (including garage conversion)”. The rules that matter most for a garage, from state law and the city’s ADU Universal Checklist (Bulletin 210):
- The garage can stay where it is. No setback is required for an existing structure converted to an ADU, even if it sits close to the property line, as long as building and fire requirements are met.
- A small expansion is allowed. Up to 150 square feet may be added beyond the existing walls to make room for an entrance.
- A detached garage can be rebuilt. When a detached garage is torn down and replaced with an ADU, the demolition permit is reviewed with the ADU application and issued at the same time.
- The main home must be permitted, and any open code enforcement case has to be resolved before the city accepts ADU plans.
- Fire sprinklers are required in the converted unit only if the main house has them.
- Impact fees for schools and parks apply only to larger ADUs; a conversion under 750 square feet stays clear of them (the city’s pages word the limit differently at exactly 750, so confirm it with the City).
- Approval clock. State law gives the city 15 business days to decide whether an application is complete and 60 days to approve or deny a complete one; the city says its first round of building review typically takes 20 business days.
Rules change: the city updated Bulletin 210 in September 2026, so check the current version on the City of San Jose ADU pages before you design.
What a garage conversion involves
- Feasibility. A feasibility check confirms that the house and garage are permitted, looks up the lot’s flood, geohazard and fire designations, and measures the garage, its slab and its roof.
- Design. The layout places the kitchen and bathroom close to existing drain lines where possible, fills the garage door opening with a wall, window or door that matches the house, and gives every bedroom an emergency escape window as the building code requires.
- Permit package. Plans to the city’s Bulletin 211, Title 24 energy calculations and the CALGreen checklist, an address request (Form 302), the ADU owner declaration (Form 312) or, for a JADU, the deed restriction (Form 313, which needs a wet signature), and the water company’s hydrant flow letter.
- Construction. The slab is checked for level and moisture, the floor is built up or insulated, walls and ceiling are insulated, new plumbing is trenched through the slab to the sewer line, the electrical service and panel are sized for a kitchen and heating, and the finishes go in.
- Inspections and final. Inspections follow the city’s ADU inspection checklist (Bulletin 213), and the construction and demolition diversion sign-off comes before the final building inspection.
We handle all permit applications, plan checks, and utility coordination with the city of San Jose.
Garage conversion cost: what moves the price
QA Builders publishes no price range for garage conversions. The only figure we publish is for ADUs of every type, on our ADU builders page: “ADU costs typically range from $150,000 to $350,000+ depending on size, type, and finishes. Garage conversions are generally the most affordable option.” That range covers detached and attached units too, so it is not a garage conversion price; your quote is built from the items below, after a site visit.
Because the slab, walls and roof already exist, the budget goes into the inside of the unit. What decides where your project lands:
- Plumbing distance. The farther the kitchen and bathroom sit from the sewer line, the more slab has to be cut and trenched.
- Kitchen and bathroom level. An efficiency kitchen and a shared bath (JADU) cost less than a full kitchen and a private bathroom (ADU).
- Floor and slab. A sloped or cracked garage slab may need leveling, a moisture barrier or a raised floor before finishes.
- Electrical capacity. A separate PG&E meter for an ADU, or a panel upgrade, adds cost; a JADU stays on the house meter.
- Energy compliance. Insulation, windows and heating and cooling must meet the Title 24 energy calculations in the permit set.
- Exterior work. Closing the garage door opening with stucco or siding that matches the house, and any new windows or entry door.
- Size. Staying under 750 square feet keeps school and parkland impact fees off the bill.
Our ADU cost guide compares a garage conversion with attached and detached units, including utilities and city fees.
Already converted without a permit?
Under the state’s AB 2533 program, San Jose offers a penalty-free path to legalize an ADU or JADU that was built or converted without a permit before January 1, 2020. You provide proof of the construction date and as-built plans, the city inspects the unit against its substandard housing checklist, and only the corrections the inspector lists are required. The city says the process typically takes 4 to 6 months from a complete application, and it asks owners to hire a licensed contractor for the corrections.
Garage conversion questions
Do I need a permit to convert a garage in San Jose?
Yes. Converting a garage into living space or a dwelling unit changes walls, plumbing, electrical work and the use of the space, all of which require a building permit in San Jose. ADU and JADU conversions go through the city’s ADU service.
Can I convert my garage and still build a detached ADU?
Often yes, under the State standards. On a single-family lot they allow a conversion ADU, one new detached ADU and one JADU in combination, subject to the city’s checklist. Under the City standards the lot gets one ADU, attached or detached, plus a JADU.
Does a converted garage add to my home's floor area ratio?
Not as an ADU. San Jose leaves garages and ADUs out of the floor area ratio it uses for the Single-Family House Permit. A garage turned into rooms for the main house is no longer a garage, so ask the city planner whether it then counts toward the ratio.
Your licensed garage conversion contractor
We’ve completed dozens of ADU projects across San Jose and the Bay Area, from garage conversions to ground-up custom builds. Every project receives a dedicated project manager so you know who to turn to every step of the way. QA Builders is a Class B general building contractor, bonded, with workers’ compensation insurance on file with the state board.
We convert garages in San Jose, including Willow Glen, and across the Santa Clara, San Mateo and Alameda County cities we serve, from Santa Clara, Sunnyvale and Cupertino to Palo Alto, San Mateo and Fremont. Browse finished work in our project portfolio, see every ADU type we build on the ADU builders page, or, if you want the garage as part of the main house, read about our home additions.
Contact us for a free consultation and estimate. Call (669) 213-8077, email Contact@qabuilders.com or send your project details, and tell us if you are leaning toward an ADU, a JADU or extra living space.