San Jose Garage Conversion Cost and Permit Guide 2026

By Yoni Asulin, ASL Remodeling | CSLB #1060310 | Updated 2026

Garage conversion cost in San Jose runs from $100 to $350 per square foot. ASL offers a free consultation. This guide covers the City of San José's ADU Service steps, fees and timing.

Garage Conversion Options in San Jose

A garage conversion in San Jose usually follows one of three paths. You can build an ADU, you can build a JADU, or you can turn the garage into living space for the main house. The path you pick decides which City process you follow, so choose it first.

The City lists "garage or basement conversion to ADU or JADU" as a qualifying project for its ADU Service. The application starts at SJPermits.org, where you choose the sub type for an ADU, including a garage conversion.

A JADU is a smaller unit. The City describes it as under 500 square feet and inside the home's footprint. It can include an attached garage. That makes a JADU a natural fit for a garage that is attached to the house.

Size is the first thing to settle with either path. It is also the biggest driver of cost, which the next sections explain.

The third path is living space for the main house, such as a den, an office or a family room. That work follows the City's Additions and Remodels path. When the work includes structural changes, the City requires plans, and they are reviewed for zoning, building and fire codes.

If you want a team to walk you through these options, see our garage conversion and ADU services. Before you decide, write down what the new space is for. Each use points to a different path and a different size.

What a Garage Conversion Costs in San Jose

Garage conversions in San Jose run from $100 to $350 per square foot. The final price depends on the size of the garage and the scope of the work. ASL offers a free consultation.

Size is the biggest cost factor. The bigger the unit, the more the project costs. A smaller unit costs less.

Ask every contractor to price the same plan, so the totals can be compared.

Set aside a contingency of 10 to 15 percent of your budget. A reserve gives you room to deal with conditions nobody can see yet without stopping the job.

ASL does not provide direct financing, but we can point you to reputable home-improvement lenders. Talk to a lender before you commit to a scope, not after you have signed.

The City sets its own permit fees, and the fees section below lists them.

If you are weighing other projects at the same time, see our page for remodeling contractors in San Jose.

What Changes the Price

Several choices move the price of a garage conversion. Each one depends on your garage and your plan.

Size. The bigger the unit, the more the project costs. This is also true of the City's building permit fees, which are driven by ADU size.

A kitchen or a bathroom. Adding either one to the garage adds work. A new bathroom or kitchen is a real addition to the scope. Decide early whether you want one, because it changes the plans.

Energy documents. The City's ADU package needs Title 24 energy documents. Someone has to prepare them, and that work is part of planning the project.

Fire requirements. Plans are reviewed for fire codes as well as building and zoning codes.

The water flow letter. The City's checklist asks for a letter from your water company. The City warns that many projects get delayed because of failure to get this letter. Ask for it early.

A geotechnical report. The City's package includes a geotechnical report when it applies to your property. Ask the City whether yours does.

The City of San José Permit Path

A garage conversion to an ADU or JADU follows the City of San José's ADU process. The City's ADU process page lists these in order: the ADU Universal Checklist, planner feedback, plans to Bulletin 211, an SJPermits.org application, an SJePlans upload, and then three review phases. The phases are prescreen, plan review and issuance review.

Plans are submitted at SJPermits.org, where you choose the ADU sub type that includes a garage conversion. The planner meeting is optional. The City invoices it at $398 per hour, with a 30 minute minimum, as listed in October 2026.

The checklist asks for more than drawings. It includes the City's forms, among them the Form 302 address request, and the water company flow letter mentioned above. The package also needs Title 24 energy documents and, when it applies, a geotechnical report.

ASL handles the whole permitting process for you.

Living space for the main house is a different path. The City recommends a licensed contractor as the applicant for a remodel with structural changes.

Bathrooms have their own City path, which we cover in a separate post. If a new bathroom is part of your plan, read our San Jose bathroom permit guide as a side note to this section.

City Fees to Budget For

Permit fees are the City of San José's charge, not ASL's. The City schedule and estimator details below come from the City of San Jose's own pages.

The City's building permit fee schedule shows fees in effect as of August 11, 2026. Check the current schedule before you finalize a budget.

The City also offers a fee estimator, which is in beta for ADU projects. Treat its result as an estimate and not as a bill.

Fees do not arrive all at once. The City sends invoices at prescreen and again at issuance. The fees at issuance include residual plan review and inspection, and for larger units they may include school and parkland fees.

One piece of good news: school and parkland impact fees do not apply to ADUs under 750 square feet. If your unit is smaller than that, those two fees drop out of your budget.

Separate from the City's own schedule, cities commonly charge from $3,000 to $12,000 and up for ADU work, and the amount depends heavily on the city. Your own number comes from the City's schedule and your project. Ask the City for its current figures before you fix a budget.

How Long a Garage Conversion Takes

There are two clocks to plan around. One is the City's review, and the other is construction.

On the City side, its ADU FAQs say it typically takes 20 business days to go through the first round of building review. That is the first round only, so do not read 20 business days as the full approval time.

ASL plans for permit approval to take 2 to 4 months or longer. A basic garage conversion takes about 8 to 12 weeks to build, and a full ADU conversion takes longer.

I cannot promise dates. The City sets its own review schedule. What I can tell you is that the review comes before construction.

Some documents depend on other people, such as the water company letter, which the City says delays many projects when it is missing.

Plan your household around both clocks. During construction the garage is a job site, so think early about where your cars and stored items will go.

Read about our design build process.

Design Choices to Settle Before Plans

Settle these choices before the drawings start, so the plans match what you want.

A kitchen or a bathroom. Decide whether the space needs either one. This is the choice that changes the scope the most.

How it connects to the house. Decide whether the new space is entered from the main house, from the outside, or both.

We do not give code or engineering advice in a blog post. Those answers come from your plans and from the City's review.

ASL also offers design services.

If your goal is more space than the garage can offer, an addition may fit better than a conversion. Read about our San Jose room addition services to compare.

When you are ready to talk through your own garage, talk with ASL Remodeling about your garage.

San Jose Garage Conversion Checklist