What the City of San José allows in 2026: sizes, heights, setbacks, parking, fees, rentals, JADUs, and how a factory-built ADU gets permitted.
Yes. Pick City or State standards for the whole project. Either way, no parking is required and the city has 60 days to act on a complete application.
San Jose ADU rules: City or State?
The city's checklist says you "must choose either all City standards or all State standards." Pick well and you get a bigger unit or an extra one.
Bigger cottage? City standards allow up to 1,000 sq ft (1,200 on lots over 9,000 sq ft), 18 ft for one story or 25 ft for two. More units? State standards fit an 800 sq ft ADU, 16 ft tall, plus a garage conversion and a junior ADU.
Check fire access first. Every side of the ADU should be within 150 ft of the street curb, and you'll need a water-flow letter for the nearest hydrant. "Many projects get delayed because of failure to get this letter," the city warns.
How much does an ADU cost in San Jose?
City building fees start at $3,291 for an ADU up to 750 sq ft, with no school or park fees at that size. Our price is one all-in number.
Launch price through Dec 31, 2026. Everything from permits to keys. Not included: solar, furniture, upgrades. What's included
Call PG&E early. The city says PG&E now requires ADUs to have their own meter, which can change your electrical plan and budget.
How long does it take?
The city has 15 business days to confirm your application is complete and 60 days to decide. Our projects take 4 to 6 months in total, from first call to keys.
Our homes are factory-built to HCD-approved plans (HCD #1585366) in our Lathrop factory. The city reviews the site plan and inspects the foundation and hookups, and crane day takes one day. What factory-built means
San Jose ADU FAQ
San Jose ADU rules in full, including fire access›
City standards (bigger unit): 1 ADU (attached or detached) + 1 JADU. Up to 1,000 sq ft (1,200 on lots over 9,000 sq ft); 18 ft for one story, 25 ft for two; behind the house or 45 ft from the front line; up to 40% of the rear yard; an attached ADU up to 50% of the main home's living area. 4 ft setbacks (zero for one story if building and fire codes are met), 6 ft from other buildings. San Jose measures square footage to the exterior finish of the walls.
State standards (more units): 1 new ADU + 1 conversion ADU + 1 JADU (no attached ADU if the lot also has a conversion ADU). 800 sq ft and 16 ft for a detached unit (state law allows more near major transit), 4 ft setbacks, no siting or coverage rules.
Fire access (both rulebooks): Every side of the ADU must be within 150 ft of the street curb, along a clear path at least 4 ft wide (if not, you may need a fire variance). The farthest exterior wall must be within 600 ft of a fire hydrant, and the hydrant must deliver 1,000 gpm at 20 psi, proven by a letter from your water company. "Many projects get delayed because of failure to get this letter. It's easy to get, so request it today!" says the city's ADU Service page. Fire sprinklers are required in the ADU only if your main house has them.
Source: City of San José Bulletin #210, ADU Universal Checklist (September 16, 2026); SJMC §§ 20.80.175-176.
San Jose fees to plan for›
Building fees, 0-750 sq ft: $3,291+ ($422 issuance, $1,137 plan review, $1,732 inspection). Same tier with the modular discount (10% off plan review, 20% off inspections; ask the city if your project qualifies): about $2,831. 751-1,200 sq ft: $5,103+. School and parkland impact fees up to 750 sq ft: $0 (school districts may charge over 500 sq ft).
Construction taxes based on valuation are extra, and so are a geologic clearance or a fire variance if your lot needs one. Call PG&E early: the city's ADU FAQ says PG&E now requires ADUs to have their own meter, which can change your electrical plan and budget (Building and Renovation Service Center, (877) 743-7782).
Sources: City of San José Building Fee Schedule FY 2026-27; Bulletin #210; Gov. Code § 66311.5. Try the city's Building Fee Estimator or our 2026 California ADU cost guide.
The 5 permit steps, and prefab in San Jose›
1. Check your lot (ADU Universal Checklist: zones, fire access). 2. Build the package (plans, Title 24 forms, water-flow letter). 3. Review and permit (SJePlans comments, then issuance; about 20 business days per round). 4. Crane day: the home is set on the foundation in 1 day. 5. Inspections and final; every ADU gets its own address.
The city's Preapproved ADU program lists seven vendors (checked October 24, 2026); with a complete site plan, those projects can be permitted the same day as the review meeting, if the lot has a single-family home or duplex and sits outside geohazard, flood, and wildfire-interface zones. Bay Modular isn't on that list today. Our homes are factory-built housing to HCD-approved plans (HCD #1585366): the state oversees the build in our Lathrop factory, and the city reviews the site plan and inspects the foundation and hookups. What factory-built means · Tour the factory
Junior ADUs (JADUs) in San Jose›
A JADU is up to 500 sq ft inside the footprint of a single-family home, including an attached garage, or inside a new home you're building. One is allowed per single-family lot, alongside an ADU. If the JADU shares a bathroom with the house, the owner must live on the property (Gov. Code § 66333); with its own bathroom, no owner-occupancy is required. JADU rentals must be longer than 30 days. The city also requires Form 313, a deed restriction signed in ink and mailed to the city for recording.
How to choose a San Jose ADU builder: 5 checks›
1. License. Look up the contractor on the CSLB license check. 2. Plans path. Preapproved list or regular ADU review, and who answers plan review comments. 3. Factory approval. A factory-built ADU should carry California HCD approval; ours is HCD #1585366. 4. Price in writing. One number for design, city fees, foundation, delivery, hookups, and installation, plus what isn't included. 5. Payment schedule. Payments follow finished milestones.
Do I need to live on the property to build an ADU in San Jose?›
No. California law bars owner-occupancy requirements for ADUs, and you can rent the house and the ADU to different people. The exception is a JADU that shares a bathroom with the main house.
Can I Airbnb my ADU in San Jose?›
Not for short stays. San Jose's ADU FAQ says the minimum rental term for an ADU is 30 days, including Airbnb rentals.
Will an ADU raise my property tax in San Jose?›
Only on the added value. The Santa Clara County Assessor says assessors treat ADUs like a home addition, and the existing home will not be reassessed.
We check your lot, tell you which model fits, and give you a fixed all-in price. You decide after that.
About Julia B. Julia B is a marketing specialist at Bay Modular, a licensed California ADU builder (CSLB #1112074) with its own factory in Lathrop. She writes about what ADUs really cost and how to avoid surprises.
Sources, city contacts, more guides
More: Models · Building in San Jose · Sunnyvale · Palo Alto · San Francisco guides
Sources
- City of San José, Bulletin #210, ADU Universal Checklist, updated September 16, 2026.
- San José Municipal Code Chapter 20.80, Part 2.75 (Accessory Dwelling Units).
- City of San José ADU pages: overview, permit process, FAQs, ADU Service, Preapproved ADUs, condominium conversions, AB 2533 program.
- City of San José, Building and Structure Permits Fee Schedule, FY 2026-27, effective August 2026.
- HCD, Accessory Dwelling Unit Handbook, March 2026; Government Code § 66317, §§ 66311.5, 66315, 66333.
- Santa Clara County Office of the Assessor, Granny Units / ADUs.
- Bay Modular Pricing & Financing, October 2026.
Sources checked October 8-24, 2026.
ADU Ally: adu.ally@sanjoseca.gov, (408) 793-5302 · Planning: ZoningQuestions@sanjoseca.gov, (408) 535-3555 · Fire permits: SJFDPermitSpecialist@sanjoseca.gov, (408) 535-7750
General information, not legal, tax, or financial advice. Confirm details for your address with the City of San José ADU Ally.
