San Jose / ADU construction
ADU Construction in San Jose
San Jose permitted 488 ADUs in 2024. Yours starts with picking the right rulebook.
San Jose lets owners build under city standards or state standards, and the two cannot be mixed. We design and build ADUs here from the site check to the PG&E meter, with the permit path chosen before a floor plan is drawn.
SAN JOSE AT A GLANCE
How San Jose handles ADUs.
San Jose has its own ADU help desk, a preapproved plan program that can issue a permit the same day, and a separate-meter rule from PG&E that catches many owners late. Here is who does what.
- 488
- ADU permits issued in 2024, up from 10 in 2015
- 59%
- of San Jose homes built before 1980
- 20
- business days for a typical first building review
Permits
Development Services Permit Center
Applications go through SJPermits.org, plans and reviewer comments through SJePlans. Inspections are booked on SJPermits.org. A preliminary meeting with a planner costs $398 an hour.
(408) 535-3555ADU permit process ↗Help desk
ADU Ally
San Jose's dedicated ADU contact answers questions on rules, stalled reviews and legalizing an existing unpermitted unit. Email adu.ally@sanjoseca.gov.
(408) 793-5302ADU FAQs ↗Utilities
PG&E plus San Jose Clean Energy
PG&E now requires a separate meter for an ADU; junior ADUs are exempt. San Jose Clean Energy pays $500 per prewired circuit for induction, a dryer or EV, and $1,000 toward a 200 amp panel when paired with a heat pump.
(877) 743-7782SJCE EcoHome rebates ↗CITY OR STATE STANDARDS
Two rulebooks, one choice.
Under San Jose's own standards a detached ADU can reach 1,000 square feet, or 1,200 on lots over 9,000 square feet, and 18 feet high for one story or 25 for two. Under state standards the guaranteed size is 800 square feet at 16 feet. The city path allows larger units; the state path allows more of them. Bulletin 210 requires choosing one.
Detached ADU
Up to 1,000 or 1,200 square feet under city rules, 4 foot side and rear setbacks, behind the main home or at the 45 foot front setback.
Attached ADU
Up to 50 percent of the main home, capped at the same 1,000 or 1,200 square feet. Not allowed alongside a conversion ADU.
Garage conversion
Converting existing space keeps the footprint. Under state standards it can be combined with one new ADU and one junior ADU.
Junior ADU
Under 500 square feet inside the home. The owner must live on site if a bathroom is shared, recorded with a deed restriction.
Preapproved plans
Seven vendors offer city-approved plans from 476 to 991 square feet. With complete site documents the permit can be issued the same day, outside hazard zones.
Duplex and multifamily lots
Up to 8 detached ADUs on a lot with an existing multifamily building, and conversions of up to 25 percent of the existing units.
BULLETIN 210
City standards or state standards.
San Jose's ADU Universal Checklist lets owners build under either set of rules, but not a mix of both. The city path allows a bigger unit; the state path allows more units on one lot.
| City standards | State standards | |
|---|---|---|
| Detached ADU size | 1,000 sq ft, or 1,200 sq ft on lots over 9,000 sq ft | 800 sq ft guaranteed |
| Attached ADU size | Up to 50% of the main home, same caps | 800 sq ft guaranteed |
| Height | 18 ft one story, 25 ft two stories | 16 ft detached, 25 ft attached |
| Side and rear setbacks | 4 ft | 4 ft |
| Units on a single-family lot | One ADU plus one junior ADU | One new ADU, one conversion, one junior ADU |
| Parking | Not required | Not required |
SAN JOSE CLEAN ENERGY
Rebates for an all-electric ADU.
San Jose Clean Energy pays EcoHome rebates when gas equipment is replaced with electric. Approval is needed before work starts, so we apply during design.
SJCE
Heat pump water heater
$2,500, or $3,500 income-qualified
Replacing a gas water heater.
SJCE
Heat pump heating and cooling
$1,500, or $2,500 income-qualified
Replacing a gas furnace.
SJCE
Panel upgrade to 200 A
$1,000, or $2,000 income-qualified
Add-on to a heat pump rebate.
SJCE
Prewired circuits
$500 each, or $750 income-qualified
For induction cooking, an electric dryer or an EV charger.
Amounts from sanjosecleanenergy.org/ecohome-rebate, October 2026. Program terms can change.
Planning the work
How a San Jose ADU gets built.
Site check
Free visit. Lot size, setbacks, utilities, hazard zones and whether a preapproved plan fits.
Rulebook and design
City or state standards chosen, then plans drawn or a preapproved plan adapted to the site.
Permit and PG&E
SJPermits submittal, a first review of about 20 business days, and the PG&E meter application filed at the same time.
Build and final
Foundation, framing, rough-in inspections, finishes, final inspection and the new meter set by PG&E.
WHAT SLOWS ADUS IN SAN JOSE
Problems San Jose owners run into, and how we plan around them.
Collected from San Jose homeowners' own posts and the city's ADU pages. Most delays come from outside the building itself.
A permit sits in review for months, and calls reach only a recording.
We check SJPermits status every week and escalate stalled reviews through the city's ADU Ally desk at (408) 793-5302.
PG&E service work, especially underground, takes far longer than construction.
The PG&E application goes in with the city permit, and the meter location is fixed during design, not after framing.
A preapproved plan barely fits, or does not fit, the setbacks on a narrow lot.
Lot dimensions, 4 foot setbacks and 6 foot building separation are measured before a plan is chosen.
Trenching for water, sewer and power costs more than expected.
Utility routes are walked and priced at the site visit, before the design is final.
The hydrant water-flow letter from the water company holds up the permit.
The letter is requested at the start of design, since the city lists it as a frequent cause of delay.
Legalizing an existing unit drags on for years.
We pre-inspect the unit, fix obvious safety items first, and only then schedule the city inspection.
Sources: r/SanJose, r/BayAreaRealEstate and r/AccessoryDwellings threads, 2023 to 2026; sanjoseca.gov ADU pages.
BEFORE YOU APPLY
What San Jose asks for.
Documents to gather
- Site plan or survey showing lot lines and existing buildings
- Completed ADU Universal Checklist, Bulletin 210
- Hydrant water-flow letter from your water company
- PG&E Your Projects application for the new meter
- Title showing current ownership
A preapproved plan fits when
- The lot is residential with an existing single-family home or duplex
- It is outside geohazard, landslide, flood and wildland-urban interface zones
- The plan meets 4 foot setbacks and 6 foot separation
- The site documents are complete for same-day issuance
Expect a longer path when
- The property is in a hazard or historic designation
- A second story or an ADU over 750 sq ft is planned
- The existing unit is unpermitted and needs legalization
- PG&E must extend or upgrade service underground
How big can an ADU be in San Jose?
Up to 1,000 square feet for a detached ADU on a lot under 9,000 square feet and 1,200 square feet on a larger lot, under San Jose's city standards. Under state standards the guaranteed size is 800 square feet. A junior ADU must be under 500 square feet, and owners must pick city or state standards without mixing them.
Are there impact fees for an ADU in San Jose?
No, not for an ADU of 750 square feet or less. School and park impact fees apply once an ADU reaches 751 square feet, which is why many preapproved San Jose plans are designed at 746 to 799 square feet.
Does an ADU in San Jose need its own PG&E meter?
Yes. PG&E now requires a separate electric meter for an ADU, while junior ADUs are exempt. The meter application should go in with the city permit, because PG&E service work, especially underground, is one of the most common causes of delay.
How long does an ADU permit take in San Jose?
The first building review typically takes 20 business days, and a preapproved ADU plan can be permitted the same day if the site documents are complete. The hydrant water-flow letter from the water company is a frequent cause of delay, so it is requested early.
Can I sell an ADU separately in San Jose?
Yes, in some cases. San Jose adopted Ordinance 31095 in June 2024 under state law AB 1033, allowing an ADU to be split off as a condominium through a parcel map, with HOA rules, CC&Rs and lender consent.
Can I legalize an existing unpermitted ADU in San Jose?
Yes. San Jose runs a legalization path for existing unpermitted units under state law AB 2533, coordinated through the ADU Ally at (408) 793-5302. Expect an inspection and corrections to bring the unit up to safety standards.
