Santa Clara County
Santa Clara ADU rules
Research summary of local ADU rules on file for City of Santa Clara in Santa Clara County. Not a determination for a specific lot.
City or county ADU page
Check any California address for freeCity of Santa Clara 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.
How many ADUs
Single-family lots: one detached ADU, one attached ADU, or one junior ADU, or a combination of one detached ADU, one junior ADU and one converted ADU. Multifamily and mixed-use lots: up to two detached ADUs, plus conversions of non-living space for at least one and up to 25% of existing units.
Source: City of Santa Clara ADU and JADU Handout (Rev. 01/26; City Code 18.60.020), Ministerial ADU “Approval”, accessed 2026-10-23.
Historic properties
On properties in the California Register of Historical Resources, the City can regulate parking, height, setbacks, landscaping, design and size, and adding an ADU needs a Significant Property Alteration permit.
Source: City of Santa Clara ADU and JADU Handout (Rev. 01/26; City Code 18.60.020), ADUs on Historically Designated Properties, accessed 2026-10-23.
Standards for all ADUs
No minimum lot size. Minimum 150 sq ft. No parking, and garages removed or converted don’t need replacing. ADUs can’t be in the sight-distance triangle at intersections or driveways, or in easements.
Source: City of Santa Clara ADU and JADU Handout (Rev. 01/26; City Code 18.60.020), Development Standards for All ADUs, accessed 2026-10-23.
Detached ADUs
Up to 1,000 sq ft on lots of 5,500 sq ft or less, 1,200 sq ft on larger lots. 4 ft side, corner-side and rear setbacks; 6 ft from the main home. 18 ft for one story, 25 ft for 1.5 stories (max 1.5 stories). Detached ADUs over one story or 18 ft: dormers up to 40% of the wall and egress windows facing the main home.
Source: City of Santa Clara ADU and JADU Handout (Rev. 01/26; City Code 18.60.020), Development Standards for Detached ADUs, accessed 2026-10-23.
Attached ADUs
Up to 1,000 sq ft or 50% of the main home, whichever is less, with at least 800 sq ft allowed. 4 ft side and corner-side setbacks; 4 ft rear for one-story parts. Up to 25 ft and 2 stories, matching the main building’s height. Exterior access required; attached ADUs within the building envelope may add up to 150 sq ft for entry.
Source: City of Santa Clara ADU and JADU Handout (Rev. 01/26; City Code 18.60.020), Development Standards for Attached ADUs, accessed 2026-10-23.
Converted ADUs
No size limit. No setbacks for conversions in the same place and size; no parking; up to 150 sq ft added for entry; exterior access required.
Source: City of Santa Clara ADU and JADU Handout (Rev. 01/26; City Code 18.60.020), Development Standards for Converted ADUs, accessed 2026-10-23.
Junior ADUs
Up to 500 sq ft inside the walls of a single-family home (not accessory structures, no 150 sq ft expansion). Efficiency kitchen. Owner occupancy only when it shares a bathroom. No rentals under 30 days. A deed restriction against separate sale is recorded.
Source: City of Santa Clara ADU and JADU Handout (Rev. 01/26; City Code 18.60.020), Development Standards for JADUs, accessed 2026-10-23.
Contact
Planning Division: 408-615-2450, planning@santaclaraca.gov.
Source: City of Santa Clara ADU and JADU Handout (Rev. 01/26; City Code 18.60.020), Contact Information, 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 Santa Clara?
State law sets a baseline for ADUs in Santa Clara, 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 Santa Clara Planning Division, or run a free address summary.
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