Santa Clara County
San José ADU rules
Research summary of local ADU rules on file for City of San José in Santa Clara County. Not a determination for a specific lot.
City or county ADU page
Unincorporated Santa Clara County ADU page
Check any California address for freeCity of San José rules on file
Local rules recorded in this project for this jurisdiction. Where a city figure on file is stricter than the state baseline on file, both are shown.
Before you start
The main home must be legally built with permits, and any open Code Enforcement case must be resolved before the City accepts ADU plans.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 1, accessed 2026-10-23.
City or State standards
Design the ADU under either City standards (Municipal Code 20.80.175) or State standards (20.80.176). The two sets can’t be mixed.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 3, accessed 2026-10-23.
State standards on single-family lots
One new attached or detached ADU up to 800 sq ft (4 ft side and rear setbacks; attached up to 25 ft, detached 16 ft, plus up to 2 ft for roof pitch within a half mile of major transit), one conversion ADU (no size cap; up to 150 sq ft may be added for entry), and one junior ADU up to 500 sq ft. An attached ADU isn’t allowed with a conversion ADU. The front setback may be encroached if that’s the only way to fit an 800 sq ft ADU. No parking.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 3 (single-family), accessed 2026-10-23.
City standards on single-family lots
One detached or attached ADU plus a junior ADU. Detached: up to 1,000 sq ft (lots under 9,000 sq ft) or 1,200 sq ft (larger lots), 18 ft for the first story and 25 ft with a second, 4 ft side and rear setbacks, behind the main home or 45 ft back, at most 40% rear-yard coverage, 6 ft from other buildings. Attached: up to 50% of the main home (1,000 or 1,200 sq ft max), 25 ft, with the front door on a different side of the building. No parking.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 3 (single-family), accessed 2026-10-23.
Duplex and multifamily lots
State standards: up to 8 detached ADUs with existing buildings (not more than the existing units) or 2 with a new building, up to 800 sq ft and 18 ft (plus 2 ft for roof pitch); conversions of unused space such as attics, basements or garages for at least one and up to 25% of existing units. City standards allow one detached or attached ADU. No parking.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 3 (duplex & multifamily), accessed 2026-10-23.
Junior ADUs
Inside the footprint of a single-family home (an attached garage can be converted). Owner occupancy of the main home is required only when the junior ADU shares a bathroom.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), accessed 2026-10-23.
Historic properties
Under City standards, ADUs on listed historic properties follow simplified design standards in 20.80.175(E). Under State standards, no extra design standards apply.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 2, item 6, accessed 2026-10-23.
Site hazards
Flood zones A, AE, AH and AO need flood design per Bulletin #211. Geohazard and landslide zones need a Geologic Hazard Clearance. Wildland-Urban Interface lots follow the WUI fire policy.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 2, accessed 2026-10-23.
Fire access and water
The farthest point of the ADU should be within 150 ft of the street along a 4 ft clear path and within 600 ft of a hydrant; otherwise a Fire Variance with extra safety measures may be needed. Get a fire-flow letter from your water company and submit it with the permit. ADUs need sprinklers if the main home has them.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 4, accessed 2026-10-23.
Address
ADUs get a unit number, posted visibly from the street and by the ADU entry; submit Form #302 with the application.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 4, item 10, accessed 2026-10-23.
Trees
Removing an ordinance-size tree for an ADU needs no tree permit but the tree must be replaced; heritage trees follow the heritage tree process.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 5, item 16, accessed 2026-10-23.
Impact fees
ADUs of 750 sq ft or less pay no school or parkland impact fees; 751 sq ft or more pay them before the permit is issued.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), Part 5, item 17, accessed 2026-10-23.
Contact
ADU questions: ADU.ALLY@sanjoseca.gov or 408-793-5302.
Source: City of San José Bulletin #210 ADU Universal Checklist (updated 09/16/2026), accessed 2026-10-23.
California state rules on file
The statewide baseline recorded from state law and the HCD ADU Handbook.
Detached size cap described in state law
1,200 sq ft. Recorded in this rules file from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Side and rear setback cap for a new ADU
4 ft. Recorded in this rules file from Government Code section 66314, which describes a cap on side and rear setbacks for a new ADU.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Setback for a conversion of an existing structure
No additional setback, as recorded in this rules file from Government Code section 66314 for a conversion of an existing structure.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Minimum lot size
A city may not impose a minimum lot size for an ADU, as recorded in this rules file from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Minimum unit the handbook says cities must allow
At least an 800 sq ft ADU with 4 ft side and rear setbacks. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(3).
Source: HCD ADU Handbook, 66321(b)(3); handbook updated March 2026, accessed 2026-10-16.
Detached height described in the handbook
16 ft, or 18 ft or 20 ft in some cases. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(4).
Source: HCD ADU Handbook, 66321(b)(4); handbook updated March 2026, accessed 2026-10-16.
Permit decision deadline
60 days. Recorded in this rules file from Government Code section 66317(a)(3): the permitting agency must decide on (approve or deny) a completed ADU application within 60 days when an existing single-family or multifamily dwelling is on the lot. Section 66317(a)(1) says the application is considered ministerially, without discretionary review or a hearing.
Source: California Government Code section 66317, 66317(a)(1), (a)(3), accessed 2026-10-17.
Owner-occupancy requirement
None. Recorded in this rules file from Government Code section 66315: a local agency may not impose an owner-occupancy requirement on an ADU. It may require that the property be used for rentals of terms 30 days or longer. The HCD ADU Handbook (updated March 2026) describes the same rule.
Source: California Government Code section 66315, 66315; HCD ADU Handbook updated March 2026, accessed 2026-10-17.
Parking near public transit
No parking standards within one-half mile walking distance of public transit. Recorded in this rules file from Government Code section 66322(a)(1). Section 66322(a) lists several other cases where parking standards may not be imposed.
Source: California Government Code section 66322, 66322(a), accessed 2026-10-17.
Ministerial categories
The HCD ADU Handbook (updated March 2026) states that Government Code section 66323 sets four ministerial categories. This rules file does not restate those four categories.
Source: HCD ADU Handbook, 66323; handbook updated March 2026, accessed 2026-10-16.
Fire Hazard Severity Zones
If your lot is in a Fire Hazard Severity Zone, the CAL FIRE Office of the State Fire Marshal says in Information Bulletin 25-004 (issued March 3, 2025): “Fire Hazard Severity Zones (FHSZs) should not restrict the development of Accessory Dwelling Units (ADUs). However, additional building standards may be necessary, including but not limited to California Fire Code Chapter 49 and California Building Code Chapter 7A.” State ADU law does not itself bar an ADU there. A city or county may still apply its building code, including wildfire-resistant construction (Gov. Code 66314(d)(8)); require side and rear setbacks “sufficient for fire and safety” for a unit converted under 66323(a)(1); and decline parking in setbacks on specific fire and life safety findings (66314(d)(10)(B)). It may also consider public safety when it designates where ADUs may be permitted (66314(a)). Sprinklers can't be required in an ADU or JADU if the primary residence doesn't need them (66314(d)(12), 66323(d)). Some cities and counties still apply their own fire-zone limits. Where this summary has one, it is listed with the local rules. This summary does not look up your lot. Check the CAL FIRE Fire Hazard Severity Zone map viewer linked from the State Fire Marshal's Fire Hazard Severity Zones page: https://experience.arcgis.com/experience/5065c998b4b0462f9ec3c6c226c610a9
Source: CAL FIRE Office of the State Fire Marshal Information Bulletin 25-004, page 4, issued March 3, 2025; Gov. Code 66314, 66323, accessed 2026-10-20.
State baseline on the directory → · State ADU rules on the homepage →
Can I build an ADU in San José?
State law sets a baseline for ADUs in San José, and the local standards on file are listed on this page. Whether a specific lot can add an ADU depends on zoning, utilities, and other site facts this page does not measure. Confirm with City of San José Planning, Building and Code Enforcement, or run a free address summary.
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