Add an ADU to your San Jose home

LotUpside is a one-stop ADU company for homes in the City of San Jose: we check your lot free against the city's rules, then match you with licensed designers and builders and coordinate the project with them.

Check your lot · free

What the San Jose rules allow on your lot: setbacks, the biggest unit that fits, fees.

Design your ADU · free

Shape it in live 3D: size, rooms, roof and finishes, with an estimate priced for San Jose.

Start designing

ADU rules at a glance

Largest detached ADU (City standards)Local rule: 1,000 sq ft; 1,200 sq ft on a lot over 9,000 sq ftSan Jose Municipal Code 20.80.175 D.1 (Table 20-55)
Detached ADU on State standardsState law: 800 sq ft, with 4 ft side and rear setbacksGov. Code 66323(a)(2); San Jose Municipal Code 20.80.176
Height, detached ADU (City standards)Local rule: 18 ft for one story; 25 ft for twoSan Jose Municipal Code 20.80.175 D.2
Side and rear setbacksLocal rule: 4 ft (City standards allow 0 ft for a first story if fire and building codes are met)ADU Universal Checklist (Bulletin 210), p.3 and footnote 2
Front setbackLocal rule: The zone's own: 20 ft in R-1-8 and R-1-5; less if it would block an 800 sq ft ADUSan Jose Municipal Code 20.30.200 (Table 20-60) and 20.80.175 D.3.a
ADUs per single-family lotState law: Up to 2 ADUs + 1 junior ADU (State standards); 1 ADU + 1 junior ADU (City standards)Gov. Code 66323(a)(1)-(2); San Jose Municipal Code 20.80.175 B.1
Impact-fee exemptionLocal rule: ADUs of 750 sq ft or lessADU Universal Checklist (Bulletin 210), question 17
City building permit feeLocal rule: $3,291 up to 750 sq ft; $5,103 for 751-1,200 sq ft (base fee, before taxes)FY 2026-27 Building Division Fee Schedule (effective Aug. 10, 2026), p.3
Park fee, ADUs over 750 sq ftLocal rule: The City's published parkland rate runs $1,700-$8,900 per ADU over 750 sq ft, by neighborhood; state law makes fees on larger ADUs proportionate to the main home, so yours may be lowerCity of San Jose, Parkland Impact Fees for Accessory Dwelling Units map
School feesState law: Up to $5.38 per sq ft, set by your school districts; some charge from 500 sq ftState Allocation Board, maximum Level I school fee (Jan. 28, 2026); Bulletin 210, question 17
ParkingLocal rule: None, and no replacement for a garage or carport you convert or removeSan Jose Municipal Code 20.80.175 I
Owner must live on siteState law: Not for an ADU; for a junior ADU only if it shares a bathroom with the houseGov. Code 66315 and 66333(b)
Permit decision deadlineState law: 60 days from a complete application, or it is deemed approvedGov. Code 66317(a)(3)
Pre-approved ADU plansLocal rule: Vendor plans the City has already reviewed; same-day permit possible for a complete applicationCity of San Jose, Preapproved ADUs page
City ADU help lineLocal rule: ADU Ally team: 408-793-5302, adu.ally@sanjoseca.govADU Universal Checklist (Bulletin 210), p.1

Last verified 2026-10-15. Rules change; the City of San Jose ADU Ally team has the final word (408-793-5302).

What's different in San Jose

Two sets of standards: City or State, never mixed

San Jose lets you design an ADU to the City's standards or to the State's, but not a mix of the two. City standards allow a detached ADU of 1,000 sq ft, or 1,200 sq ft on a lot over 9,000 sq ft, 18 ft tall for one story or 25 ft for two, placed behind the house or at least 45 ft from the front lot line and 6 ft from the house. State standards allow a new detached ADU of 800 sq ft and 16 ft (more near major transit) with 4 ft side and rear setbacks and no siting rule, plus a conversion ADU and a junior ADU on the same lot.

ADU Universal Checklist (Bulletin 210), Part 3; San Jose Municipal Code 20.80.175 and 20.80.176

Stay at 750 sq ft or less to skip impact fees

The City's checklist waives school and park impact fees for an ADU of 750 sq ft or less; from 751 sq ft both apply and must be paid before the permit is issued (state law makes impact fees on an ADU over 750 sq ft proportionate to the main home's size, so the City's published rates are a ceiling to confirm). The checklist measures floor area to the exterior finish while the state's 750 sq ft rule counts interior livable space, so confirm a design close to 750 sq ft with the City. Permits also cost more than the base fee: the City's Building Fee Estimator averaged $8,437 for a junior ADU, $12,866 for a detached ADU up to 750 sq ft and $22,108 for 751-1,200 sq ft (permits issued in the 12 months before October 4, 2026, construction taxes included, school and park fees not).

ADU Universal Checklist (Bulletin 210), question 17; City of San Jose Building Fee Estimator (averages queried Oct. 4, 2026)

Hazard zones and fire access can add steps

On a lot in a landslide zone, an earthquake fault zone (state fault maps are part of the City's geologic hazard zone, SJMC 17.10.225) or the City's geologic hazard zone, San Jose issues no building permit until it grants a Geologic Hazard Clearance, based on a geologic evaluation; a liquefaction zone needs a Geologic Clearance only for 2 or more units. Fire access is measured too: if the farthest side of the ADU is more than 150 ft from the street curb along a 4 ft clear path, you may need a Fire Variance with extra safety measures, and the permit application needs a fire-flow letter from your water company.

ADU Universal Checklist (Bulletin 210), questions 5, 11 and 13; San Jose Municipal Code 17.10.300

City pre-approved ADU plans and the ADU Ally team

The City lists ADU plans from outside vendors that City staff have already reviewed for code compliance; you still submit a site plan for your own lot. If the application is complete, the permit can be issued the same day as the plan review meeting, for a residential lot with a single-family home or duplex outside geohazard, landslide, flood and wildland-urban interface (WUI) areas. Questions go to the City's ADU Ally team at 408-793-5302 or adu.ally@sanjoseca.gov.

City of San Jose, Preapproved ADUs page

Estimated costs and rents in San Jose

Type	Est. all-in cost	Est. rent
Garage conversion	$268-$436 per sq ft of garage (about $107,000-$174,000 for a 400 sq ft garage)	$1,850-$2,650/mo
Junior ADU (inside the house)	$60,000-$110,000	$1,575-$1,925/mo
Detached studio	$229,000-$312,000	$1,975-$2,425/mo
Detached 1 bedroom	$277,000-$378,000	$2,375-$2,925/mo
Detached 2 bedroom	$277,000-$462,000	$2,825-$3,625/mo
Detached 3 bedroom	$330,000-$480,000	$3,500-$4,300/mo

Estimates for a first conversation, not bids or appraisals. Source: LotUpside price book sj-2026-10.

How we work in San Jose

1
Free lot check
A 12-check property screening from public records: what fits on your lot and what it adds.
2
Get matched with a licensed designer
Ask for a free consult and we look for a licensed designer for your plans and permit.
3
Get matched with a licensed builder
The builder holds the construction contract; we coordinate the project with them.

Licensed partners design and build, and the builder holds the construction contract. Partners are signed in some areas so far. All figures are estimates, not bids.

What our check reads in San Jose

Rules from City of San Jose ADU Universal Checklist (Bulletin 210); zoning from the City of San Jose zoning map, CA Gov. Code 66314. Plus county parcel and assessor maps, CAL FIRE fire zones, FEMA flood maps, the California Geological Survey, the USDA soil survey, USGS elevation and Microsoft building outlines.

San Jose ADU questions answered

Floor plans to start from

Measured ADU layouts you can edit and download as CAD files, then check against the San Jose rules above.

Ready to build in San Jose?

We'll match you with a licensed designer and builder in your area and coordinate the project. Free consult, no obligation.

Want to build it?

We'll match you with a licensed designer and builder in your area and coordinate the project. Free consult, no obligation.

Licensed partner designers and builders do the design and construction, and the builder holds the construction contract. Partners are signed in some areas so far; elsewhere we'll tell you plainly what we can do.

San Jose ADU questions

How big can an ADU be in San Jose?

Under the City's standards a detached ADU can be 1,000 sq ft, or 1,200 sq ft on a lot over 9,000 sq ft, if it sits behind the house or at least 45 ft from the front lot line (Municipal Code 20.80.175). Under the State standards it can be 800 sq ft with 4 ft side and rear setbacks, and the City's Bulletin 210 says you use one set for the whole design. LotUpside's free lot check tries each plan under both sets and keeps the better fit.

Do I have to replace parking if I turn my garage into an ADU in San Jose?

No. San Jose requires no parking for an ADU and doesn't make you replace garage or carport spaces removed to build it (Municipal Code 20.80.175 I); Bulletin 210 lists parking as none under both sets of standards.

How long does an ADU permit take in San Jose?

The City's ADU FAQ says the first round of building review typically takes 20 business days, and state law requires a decision within 60 days of a complete application (Gov. Code 66317). With a complete application on a City pre-approved ADU plan, the permit can be issued the same day as the plan review meeting (City Preapproved ADUs page).

Do I have to live on the property to build an ADU in San Jose?

No. State law bars owner-occupancy rules for ADUs (Gov. Code 66315). A junior ADU is different: the owner has to live in the house only if the junior ADU shares a bathroom with it (Gov. Code 66333, and the City's Bulletin 210 says the same).

Can I rent my San Jose ADU on Airbnb?

Not for short stays: the City's ADU FAQ says the minimum rental term for an ADU is 30 days, including Airbnb rentals.

What's free, and what's in the $49 full report?

The free check gives the verdict from a 12-check property screening, your best move with the value it adds, the monthly rent and the cash you put in. The full report adds every option ranked, cost vs value ranges, concept floor layouts and site plan drafts, and every check with its sources. It is a one-time payment per property.

Is this a permit, or a plan I can build from?

Neither. It is a screening from public records, not professional advice, and not a survey, soils report, appraisal, loan offer or permit; every number is an estimate. A licensed designer confirms the final plan, and your city or county gives final approval.