ADUs and garage conversions San Jose

Planning an ADU in San Jose, from the checklist to a condo sale

A San Jose ADU is a detached backyard unit, a converted garage or basement, or a junior unit inside the house, and the first decision is the rulebook. The city's ADU Universal Checklist makes you design under either its own standards, which allow a two-story detached unit up to 25 feet, or the state standards, never a mix of the two.

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Hotel Valencia at Santana Row in San Jose
Hotel Valencia at Santana Row in San Jose. Photo: Payton Chung, CC BY 2.0, via Wikimedia Commons.
Rulebook
City or State ADU standards, chosen once and never mixed
Detached height, City
18 ft for one story, 25 ft for two
School and park fees
Apply only to ADUs of 751 sq ft or more
City help
ADU Ally team in the Building Division

Permits and local rules

Where San Jose ADU permits slow down or stop

  1. Flood, geohazard, WUI and a filled-in pool

    Bulletin #210 sends you to SJPermits.org to read a property's designations. A lot in flood zone A, AE, AH or AO follows the flood design rules in Bulletin #211; a geohazard or landslide designation needs a Geologic Hazard Clearance; a Wildland-Urban Interface lot follows the Fire Department's WUI Fire Conformance Policy. Where a swimming pool was demolished, the ground is treated as nonbuildable until the submittal includes pool demolition documents under Bulletin #289 or a geotechnical report with a foundation design.

    City of San José, Bulletin #210 ADU Universal Checklist (opens in a new tab)

  2. The hydrant letter and fire access

    Fire review wants every side of the ADU within 150 feet of the street curb along a clear path at least four feet wide, and the farthest wall within 600 feet of a hydrant. The application must include a letter from your water company, whether San Jose Water, Great Oaks Water or the San José Municipal Water System, giving the flow at the nearest hydrant against a 1,000 gpm at 20 psi benchmark. The city says projects are often delayed because applicants do not get this letter.

    City of San José, ADU FAQs (opens in a new tab)

  3. Sprinklers, trees and the 750-square-foot line

    If the main house has fire sprinklers, the ADU needs them too, and an attached ADU over 500 square feet that brings the combined floor area past 3,600 square feet means sprinklering both. Removing an ordinance-size tree for an ADU needs no removal permit, but the tree must be replaced; a heritage tree follows its own process. School and parkland impact fees apply from 751 square feet, and the permit is not issued until they are paid.

    City of San José, Bulletin #210 ADU Universal Checklist (opens in a new tab)

  4. Selling the ADU as a condominium

    To sell or convey an ADU separately from the main residence, the owner first applies for a condominium conversion of both. The San José City Council adopted Ordinance No. 31095 in June 2024 under AB 1033, and only projects that meet every condition in the ADU Condominium Checklist may apply for the Parcel Map. After the map, condominium plan, HOA documents and CC&Rs are recorded, Form #302 gets the unit a new address, since it can no longer be called Unit X.

    City of San José, ADU Condominium Conversions (opens in a new tab)

State license for this work: B General Building. Look up a contractor's license on the CSLB website (opens in a new tab).

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Free to request, and you agree the scope and price with the person you hire before work starts. In California, a job over $1,000 in labor and materials, or one that needs a building permit, must be done by a contractor licensed by the CSLB in the right class. Ask for the license number and check it at cslb.ca.gov.

A two-story laneway house with a garage, a small detached home at the back of a lot in Vancouver
A two-story laneway house with a garage, a small detached home at the back of a lot in Vancouver. Photo: Mike, CC BY-SA 2.0, via Wikimedia Commons.

The houses here

Tract lots, attached garages and the permits behind them

Much of the single-family housing here went up as post-war tracts on the valley floor, and the garage is often where an ADU starts. An attached garage can become a junior unit of under 500 square feet inside the home's footprint; a detached one at the back can be converted or replaced. Two early questions on the city's checklist decide whether there is a project at all. Is the lot really inside San José, which SJPermits.org answers in its Incorporated field? And was the main home built with approved permits? A room enclosed decades ago without one can stop the application before design begins.

The work

Four shapes an ADU takes on a San Jose lot

  1. A two-story detached unit under City standards

    San Jose's own standards allow a detached ADU of up to 1,000 square feet on a lot under 9,000 square feet and 1,200 square feet on a larger one, at 18 feet for one story or 25 feet for two. It has to keep four feet from side and rear lines, stay six feet from other buildings, and leave structures covering no more than 40 percent of the rear yard. The State path caps a new detached unit at 800 square feet and 16 feet.

  2. A junior unit in the attached garage

    A JADU has to fit within the existing footprint of a single-family house, and San Jose's checklist names converting an attached garage as one way to do it. The owner must live in the main home if the two share a bathroom. The JADU Deed Restriction Agreement, Form 313, needs a wet signature because the Santa Clara County Recorder's Office requires one, so it is printed, signed and mailed rather than sent through DocuSign. A JADU does not need its own PG&E meter.

  3. Bringing an unpermitted unit into the record

    If a garage or backyard room was converted and rented out without a permit years ago, it can still be brought into the record. San Jose runs an AB 2533 ADU and JADU Legalization Program and asks owners to email its ADU Ally team to see whether a unit qualifies. Separately, state law lets the owner of an ADU built before January 1, 2020 ask the city to delay enforcing a building standard against it, subject to the Health and Safety Code. A contractor then prices the corrections the inspection turns up.

  4. Building a unit that can be sold on its own

    San José says it was the first California city to allow ADU sales, and that the first ADU condominium sale in the state closed in June 2026 on a 749-square-foot home on Josefina Street near downtown. Selling one takes a condominium conversion of the house and ADU: the ADU Condominium Checklist, then an AB 1033 Parcel Map from Public Works, then a new address. If a sale is the plan, design separate utilities, parking and an outside entry from the start.

Before you hire

Questions to put to a San Jose ADU contractor

  • Which San Jose rulebook does your design use, City or State standards, and what does that choice give up on my lot?
  • Who asks my water company for the hydrant flow letter, and how early in the project?
  • Is the unit drawn under 751 square feet on purpose, and what changes if it grows past that line?
  • Who acts as the ePlan Applicant answering plan review comments in SJePlans, and does the license at cslb.ca.gov show B General Building?
  • If I might sell the ADU later, how do the utilities, parking and entry fit the city's ADU Condominium Checklist?

Questions

San Jose ADU questions owners ask early

Does the size of a San Jose ADU change the fees?

Yes, at 750 square feet. San Jose does not charge school or parkland impact fees on an ADU of 750 square feet or less, and its own FAQ suggests building under that size as one way to save. Several vendor plans on the city's preapproved list are drawn at 746 to 749 square feet, and larger preapproved designs are listed too.

Does an ADU in San Jose need its own PG&E meter?

The city says PG&E now requires ADUs to have their own PG&E meter, and points owners to PG&E's Building and Renovation Service Center to confirm the requirement, since the city does not set PG&E's metering policy. A junior ADU is not treated as a separate unit and does not need a separate meter. Ask the contractor to start the PG&E application early.

Can a new detached ADU in San Jose have gas appliances?

Yes, for now. The city's ADU FAQ says San José has paused enforcement of its natural gas prohibition ordinance, so a detached ADU may be designed with natural gas or all-electric. The city still encourages all-electric construction and points owners to San José Clean Energy for electrification tips.

We filled in an old pool where the ADU would go. Is that a problem?

It can be. San Jose's checklist treats the area of a demolished swimming pool as nonbuildable until the submittal shows how it was filled. You can check SJPermits.org for old pool permits on the property, and the plans then need either a plot plan meeting Bulletin #289's pool demolition requirements or a geotechnical report and foundation design, which may mean hiring an engineer.

How long does San Jose take to review ADU plans?

The city's FAQ says the first round of building review typically takes 20 business days unless the plan needs additional review, and that complete, accurate plans keep a project to one or two review cycles. With a preapproved plan and complete site documents, the city may issue the permit at the scheduled plan review meeting itself. Missing items, such as the water company's hydrant letter, are a common reason for delay.

Where these facts come from

Checked against these public sources in October 2026. Rules and programs change: confirm permit requirements with the city before work starts, and a contractor's license on the CSLB website.

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