Everything homeowners need to know about building an accessory dwelling unit in Santa Clara - size limits, setbacks, permits, and how Silicon Valley's rules compare to the rest of the Bay Area.
Last verified: August 2026
8/10 · Very ADU-friendly
1,200 sq ft*
Max ADU size
18-25 ft
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes Santa Clara City Code Section 18.60.020 (Accessory Dwelling Units) and California's statewide ADU law for general reference - it is not legal advice. Regulations change; always confirm current requirements with the City of Santa Clara Planning Division before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached, lots under 5,500 sq ft
1,000 sq ft
18 ft for a single story; up to 25 ft for a 1.5-story unit
4 ft rear, side, and corner setback; 6 ft from the main residence
Detached, lots 5,500 sq ft and up
1,200 sq ft
18 ft for a single story; up to 25 ft for a 1.5-story unit
Half-story portions need a 15 ft rear setback
Attached (addition to the primary home)
1,000 sq ft or 50% of the primary home's size, whichever is smaller
Up to 25 ft, maximum 2 stories
Upper-story emergency egress windows must face the primary residence, not neighboring yards
Junior ADU (JADU)
500 sq ft
Same as primary structure
Must be built within the walls of the existing house
Allowed zoning districts
Permitted in R1 single-family districts, R3 medium-density multifamily districts, Planned Development (PD) areas, and the city's mixed-use districts (MUCC, MURC, MUNC), essentially anywhere residential use is allowed, including HOA neighborhoods. Confirm your parcel's zoning with Planning.
Additional standards
Setbacks, parking & other rules
Setbacks
4 ft from rear, side, and corner lot lines, and at least 6 ft from the main residence, for detached units
Parking
Not required for an ADU or JADU anywhere in the city; a parking space removed to make room for the ADU doesn't need to be replaced
Units per lot
1 ADU plus 1 JADU on a single-family lot; qualifying multifamily properties may add up to 8 detached ADUs under state law, or convert up to 25% of existing non-livable space
Owner-occupancy
Not required for a standard ADU under California's AB 976. A JADU only requires owner-occupancy if it shares a bathroom with the main house, per 2026's AB 1154
Rental terms
JADUs may not be rented for fewer than 30 days under state law; confirm current city practice for standard ADUs
Building code
Must meet current California Building, Residential, Energy, Plumbing, Mechanical, and Electrical Code standards; homes in liquefaction-risk areas typically need a soils report as part of design
Ordinance history
How Santa Clara's ADU rules got here
2017Statewide ADU law takes effect. California Government Code section 65852.2 required Santa Clara, like every city in the state, to approve qualifying ADUs ministerially.
2020Local code updated for the state's ADU overhaul. Following a wave of 2019 state legislation (AB 68, AB 881, AB 587, AB 2299, AB 671), the city revised its ADU and JADU standards under City Code Section 18.60.020 to match reduced setbacks, smaller minimum lot sizes, and looser parking rules.
2024Owner-occupancy eliminated and multifamily ADUs expanded statewide. AB 976 permanently barred owner-occupancy requirements for standard ADUs, and SB 1211 opened the door to as many as 8 detached ADUs on qualifying multifamily properties - both incorporated into the city's practice.
2026ADU/JADU guidance refreshed. The city issued an updated ADU and JADU handout in January 2026 reflecting current state law, including AB 1154's narrower JADU owner-occupancy rule and SB 543's faster review deadlines.
Worth knowing: Santa Clara is one of the more permissive Silicon Valley cities on paper, dropping parking requirements entirely and offering an expedited pre-approved plan track - but the region's high land and construction costs remain the bigger practical barrier to building, not the zoning rules themselves.
Permit process
How Santa Clara ADU permitting works
1
Pre-application check
Confirm zoning eligibility and lot-size tier with the Planning Division, (408) 615-2450 or planning@santaclaraca.gov, before designing.
2
Choose pre-approved or custom plans
The city's Pre-Approved ADU Plans program can cut plan review to roughly 4 weeks and reduce fees to about 25% of the standard rate compared with a custom design.
3
Submit through the Permitting Online Portal
Most ADUs and JADUs are processed as a standard building permit; a new attached second-story ADU on a single-family lot also needs Architectural Review. Staff checks submittals for completeness within about 5 business days.
4
Plan review
State law requires a decision within 60 days of a complete application; Santa Clara's typical full process runs about 3-4 months for a custom design.
5
Building permit & inspections
Once approved, schedule the standard framing, plumbing, electrical, and final inspections through the Building Division, (408) 615-2420, at least 24-48 hours ahead.
Fees and timelines are approximate and subject to change - confirm current figures with the Planning Division.
Budgeting
What it costs to build an ADU in Santa Clara
Garage conversion
Roughly $70,000-$185,000, the least expensive path since the shell already exists
Basement/addition conversion
Roughly $100,000-$225,000, depending on existing structure and utility access
New detached ADU
Roughly $155,000-$350,000+, with Silicon Valley labor and land costs pushing many projects toward the higher end
Architectural Review & ADU fee
A flat $306, plus valuation-based permit fees typically ranging from $750-$7,500
Soils report (if applicable)
Roughly $3,000-$5,000, often needed for properties in the city's liquefaction-risk zones
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, finishes, and site engineering needs. The pre-approved plan program is the most reliable way to control both fees and design cost.
Before you apply
Tips for a smooth approval
Check your lot size before assuming the 1,200 sq ft cap applies. Lots under 5,500 sq ft are capped at 1,000 sq ft instead - confirm your parcel's square footage early.
Use the pre-approved plan program if your design allows it. It's the fastest and cheapest path through review, cutting both timeline and fees substantially versus a custom plan.
Budget for a soils report if you're in a liquefaction zone. Much of Santa Clara sits on ground that requires this extra engineering step - ask your designer to check early, before you're deep into permitting.
Don't over-budget for parking. Santa Clara doesn't require a parking space for an ADU or JADU, so don't let a contractor quote include one you don't need.
Mind the second-story window rule. If you're building a 1.5-story detached ADU or an attached second-story unit, emergency egress windows must face your own property, not a neighbor's yard - it can affect your floor plan.
FAQ
Common questions
Do I need to live on the property to build an ADU in Santa Clara?
No, not for a standard ADU. California's AB 976 permanently eliminated owner-occupancy requirements for ADUs statewide as of 2024. A JADU only requires owner-occupancy if it shares a bathroom with the primary home, under 2026's AB 1154.
What's the maximum size for a detached ADU in Santa Clara?
1,000 sq ft on lots under 5,500 sq ft, or 1,200 sq ft on larger lots, with height capped at 18 ft for a single story or up to 25 ft for a 1.5-story unit.
Do I need parking for an ADU?
No. Santa Clara doesn't require off-street parking for an ADU or JADU anywhere in the city, and you don't have to replace a garage or driveway space you remove to build one.
How many ADUs can I build on one lot?
A single-family lot can add 1 ADU plus 1 JADU. Qualifying multifamily properties can go further, adding up to 8 detached ADUs under state law (SB 1211) or converting a share of existing non-livable space.
How long does the permit process take?
State law requires a decision within 60 days of a complete application, and Santa Clara's typical full process for a custom design runs about 3-4 months. Using the city's pre-approved plan program can shorten that to roughly 4 weeks for plan review.
How much does an ADU cost to build in Santa Clara?
Garage conversions tend to run roughly $70,000-$185,000, basement or addition conversions $100,000-$225,000, and new detached units $155,000-$350,000 or more, based on local contractor estimates and regional reporting - Silicon Valley labor and land costs often push projects toward the higher end.
Can I rent my ADU out on Airbnb or a short-term rental platform?
State law bars renting a JADU for fewer than 30 days. Standard ADU short-term rental practice can vary by city policy, so confirm current rules with the Planning Division before assuming short-term rental is allowed.
Has HCD found any problems with Santa Clara's ADU ordinance?
Not for the City of Santa Clara specifically, as of this page's last verification. HCD has issued ADU non-compliance findings against neighboring Santa Clara County's unincorporated-area ordinance (a separate jurisdiction), but no published HCD finding against the City of Santa Clara's own ordinance turned up in available records. Confirm current status directly with the city, since ordinances are periodically amended to track new state law.
What is the difference between a JADU and a standard ADU here?
A JADU is capped at 500 sq ft and must be built within the walls of the existing house, sharing some systems with the main home; a standard ADU can be attached or fully detached and sized up to 1,000-1,200 sq ft depending on lot size.
