ADU Laws · 2026
Santa Clara County ADU Permit Timeline: How Long It Takes
Your Santa Clara County ADU permit timeline is set by state law, which gives your city, or the county itself if you live outside city limits, 60 days to approve or deny a complete ADU application, with no public hearing. A detached ADU that uses a plan the same agency has already pre-approved gets a shorter deadline of 30 days. Both clocks start only once the application is complete, and that one word explains most permit delays. Your move-in date is a separate question, and with a factory-built home it overlaps with permitting instead of waiting behind it.
The short version: 60 days from a complete application is the legal ceiling, and 30 days applies to a detached ADU on a pre-approved or previously approved plan. San Jose can issue preapproved plan permits the same day on qualifying lots, and Gilroy within 15 working days. Those fast lanes are for plans on each agency’s pre-approved list. Outside the City of Santa Clara, where our Six Sixty Duo is on the city’s list, our homes go through standard ministerial review on the 60-day clock, with a complete, site-specific plan set our team prepares and submits. Because our team builds about 97% of your home in our Salinas factory while the permit moves, our published timelines run from about 4 months best case to 7 to 9 months, always subject to permitting.
On this page
The 60-day clock
The rules come from Government Code section 66317, and they apply the same way in San Jose, Sunnyvale, Gilroy and unincorporated county land. For the statewide picture, see our California ADU permit timeline. Here is what the law requires:
| Step | What state law requires |
|---|---|
| You submit the application | The agency has 15 business days to tell you in writing whether it is complete, with a list of anything missing |
| No answer within 15 business days | The application is deemed complete |
| You fix the listed items | The agency rechecks within another 15 business days and cannot add items that were not on its list |
| Decision deadline | Approve or deny within 60 days of a complete application, on a lot with an existing home |
| If denied | A full set of written comments within that same window, listing what is deficient and how to fix it |
| If the deadline passes | The application is deemed approved |
| If you ask for a delay | The 60 days pause for the length of the delay |
The written-comments rule matters locally: when the California Department of Housing and Community Development reviewed Santa Clara County’s ADU ordinance in June 2025, its findings told the county to amend it to provide for the timely return of written comments on a denial. One exception: if the ADU application is submitted together with a permit for a new primary home on the same lot, the agency may hold the ADU decision until it decides on the new home, though the ADU is still reviewed without a hearing.
30 days with a pre-approved or previously approved plan
AB 1332 added Government Code section 65852.27, which required every city and county to set up an ADU plan preapproval program by January 1, 2025. The same section sets a faster deadline: the agency must approve or deny an application for a detached ADU within 30 days of receiving a completed application when it uses either:
- A plan the agency pre-approved within the current triennial California building code cycle, or
- A plan identical to one used in a detached ADU application the agency approved within that same cycle.
Two details are easy to miss. The 30-day lane covers detached units only, and the earlier approval has to fall within the current code cycle (Santa Clara County now enforces the 2025 California codes). Pre-approved or not, San Jose, Morgan Hill and the county all still require site-specific documents showing where the ADU sits on your lot and how it connects to utilities. Framework First models are not on the county’s pre-approved list, so on unincorporated land our homes follow the standard 60-day path. Our guide to pre-approved ADU plans in California explains the difference.
City by city: San Jose, Gilroy, Morgan Hill and the rest
San Jose. The city says its first round of building plan review typically takes 20 business days, and it urges accurate, complete plans to stay within one or two review cycles. Its preapproved ADU program goes further: when the site-specific plan and documents are accurate and complete, permits may be issued the same day as the plan review meeting. To qualify, the lot must be zoned residential with an existing single-family home or duplex and must not sit in a geohazard, landslide, flood or Wildland-Urban Interface (WUI) area. Our San Jose ADU timeline walks through it week by week, and our San Jose ADU permit guide covers the submittal itself.
Gilroy. With one of the city’s pre-approved plans and an accurate, complete site-specific package, Gilroy says permits may be issued within 15 working days. See our Gilroy ADU timeline.
Morgan Hill. The city’s ADU Plans Gallery includes pre-approved plans, but they cannot be customized much beyond materials if you want the expedited review, and property-specific pieces like the foundation still get Planning and Building review. More in our Morgan Hill ADU timeline.
Los Gatos and the hillside towns. Same 60-day clock; topography and the engineering it calls for can set the pace. See our Los Gatos ADU timeline.
Sunnyvale, Mountain View, Cupertino, Palo Alto, Campbell and the rest run their own intake under the same state deadlines.
Unincorporated Santa Clara County
Outside city limits, in San Martin or the rural hills, the county’s Department of Planning and Development is your permitting agency. Applications go in through the county’s Public Permit Portal, get a completeness review, and are routed for plan review once complete and paid. The county strongly recommends a general consultation before you apply. Our guide to unincorporated Santa Clara County ADU rules covers size, setbacks and septic on county land.
The county’s Pre-Approved ADU Program offers free plans to unincorporated residents, though modified plans lose the expedited review and expedited permitting is not available in Wildland Urban Interface, special flood hazard or geologic hazard zones.
The county is also amending its ADU ordinance to reflect state law. Its published schedule had the Airport Land Use Commission hearing it on October 21, 2026, the San Martin Planning Area Commission on November 18, 2026 and the Planning Commission on December 17, 2026, with the Board of Supervisors set for the first quarter of 2027. The state deadlines above apply throughout.
What actually slows a Santa Clara County permit
The legal clocks are rarely the bottleneck. These are:
- An incomplete first submittal. Every missing sheet becomes an incomplete-items list, and each round of fixes costs weeks.
- Septic parcels. Rural lots on septic add septic review, and the county collects septic system fees at permit issuance. Whether a system needs an upgrade varies by parcel and is confirmed in the feasibility study.
- Fire access and WUI. San Jose checks that every side of the ADU is within 150 feet of the curb along a 4-foot clear path and that all exterior walls are within 600 feet of a hydrant; missing either can mean a Fire Variance. The city also asks for a water flow letter, and notes that projects are often delayed by not getting it early. WUI mapping rules out the fastest pre-approved lanes in both San Jose and the unincorporated county.
- Geologic hazard review. Hillside and landslide-mapped lots can need geologic review and clearance, which both San Jose and the county charge for separately.
- Title 24 and truss documents. Missing energy calculations or the manufacturer’s truss design keeps an application from counting as complete.
- Variances, clearances and deferred submittals. San Jose notes these can push even a preapproved plan past same-day issuance.
Why total delivery time is not permit time plus build time
Most answers to “how long does it take to build an ADU” stack the steps: design, permits, then months of construction in your yard. Our team builds about 97% of your home in our Salinas factory while your plans are in review, and the build continues while your foundation goes in after the permit is issued. A crane sets the finished home, then hookups and final inspection follow.
| Model | Published timeline |
|---|---|
| Four Fifty (450 sq ft studio) | About 4 months, best case |
| The 405, Five Five Five, Six Sixty, Six Sixty Duo | About 5 months |
| Seven Forty-Nine | 5 to 6 months |
| Eight Eighty-Five and Nine Forty-Five models | About 6 months |
| Twelve Hundred and Twelve Hundred U | 7 to 9 months |
Every one of those timelines depends on permitting, the one step no builder controls. Our team handles the paperwork: the plan set, the submittal, reviewer comments and inspections.
Our 14 models run $199,000 to $599,000 all-inclusive, with a permitting budget built in alongside plans, the factory build, delivery, hookups and appliances. Permit fees are set by your city or the county and vary by parcel, so we confirm yours in the feasibility study. Property-specific site work such as a septic upgrade is not part of the listed model price; we offer it in-house as part of your contract if your lot needs it.
Frequently asked questions
Does the 60-day clock include time spent on corrections?
The 60 days run from a complete application. Before that, the agency has 15 business days to list what is missing and another 15 to recheck your fixes, without adding new items. If you ask for a delay, the 60 days pause for that period. The fastest path is a first submittal that never needs a correction round.
What happens if the city or county misses the deadline?
Under state law, a complete ADU application that is not approved or denied within 60 days is deemed approved. A denial inside the window has to come with written comments explaining what is deficient and how to fix it.
Are pre-approved plans really faster in San Jose?
They can be. San Jose may issue preapproved plan permits the same day as the plan review meeting when site documents are accurate and complete, on lots with an existing single-family home or duplex outside geohazard, landslide, flood and WUI areas. State law separately sets a 30-day deadline for detached ADUs on pre-approved plans. Our homes in San Jose go through standard review with a complete plan set.
Is unincorporated county review slower than a city?
Not by law. The county is held to the same 60-day and 30-day deadlines as any city. The difference is the parcels: rural lots more often involve septic, fire access, WUI mapping or geologic review, each adding documents and review steps worth identifying before plans are drawn.
How long does a factory-built ADU take from start to move-in?
The factory build runs while the permit is in review, so what follows issuance is mostly the foundation, the crane set, hookups and final inspection. Our published timelines run from about 4 months best case for the Four Fifty to 7 to 9 months for the Twelve Hundred, all subject to permitting.
Want a timeline for your actual parcel? A feasibility study ($497 standard, $997 for an empty lot) confirms your city or county path, the documents your lot needs and your permit costs before you commit. It is refundable if your property cannot host an ADU, as a full refund minus payment processing fees, and it is credited toward your build if you sign with us within 90 days.
