Santa Clara County · ADU permit data · Updated 2026-10-20
4.6months median, application to building permit, 2023–2025
That is 23% shorter than the Bay Area median of 6.0 months. One in four applicants waited more than 7.4 months.
ADUs permitted in 2023–2025, 120 matched on parcel number. Includes time owners spent revising plans.
Source: California HCD Annual Progress Reports, filed by the City of Sunnyvale
Fast quarter, median and slow quarter, in months
Sunnyvale 3.1–7.4 mo
Santa Clara County
Bay Area 3.8–10.5 mo
Median Fast quarter to slow quarter
Median wait
Where Sunnyvale sits among 52 ranked cities
Sunnyvale Other ranked cities Bay Area 6.0
Sunnyvale
4.6months
median wait, 2023–2025
State law gives the city 60 days to act once an application is complete. Counted from first submission, this share of ADUs took longer. Ask for the completeness letter, which is due within 15 business days, and keep its date.
Source: HCD Annual Progress Reports, 2023–2025; Gov. Code 66317
Sunnyvale
90%
of matched ADUs
One applicant in four took longer than this. Plan on it if the city sends your plans back for another round of corrections.
Source: HCD Annual Progress Reports, 2023–2025, 75th percentile
Sunnyvale
7.4months
One applicant in four had a building permit within this time from first submission.
Source: HCD Annual Progress Reports, 2023–2025, 25th percentile
Sunnyvale
3.1months
Source: units by calendar year, as reported by the City of Sunnyvale to California HCD
Of every home Sunnyvale permitted in 2023–2025, this share was an ADU.
Source: HCD Annual Progress Reports, 2023–2025
Sunnyvale
25%
Permits a year for every 1,000 detached houses, so small and large cities can be compared.
Source: HCD Annual Progress Reports; DOF housing estimates
Sunnyvale
3.3
rank 37 of 92
Yearly ADU permits in 2023–2025, up 20% from 2019–2021.
Source: HCD Annual Progress Reports
Sunnyvale
+20%
Median time from building permit to certificate of occupancy for ADUs finished in 2023–2025. Add it to the permit wait for a full timeline.
Source: HCD Annual Progress Reports, 2023–2025
Sunnyvale
12.5months
median of 155
One ADU in four took longer than this to reach a certificate of occupancy after the permit.
Source: HCD Annual Progress Reports, 2023–2025, 75th percentile
Sunnyvale
20.3months
Median Fast quarter to slow quarter Bay Area median, 6.0 months Number is the rank out of 52 cities
Every page in Santa Clara County: median wait where we can measure it, otherwise ADU permits a year
Timeline tool
Pick a start date and see the fast, likely and slow dates for Sunnyvale, from the numbers on this page.
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Source: Bay Area ADU Permit Clock 2026, our analysis of the California HCD Housing Element Annual Progress Reports (data.ca.gov) filed by the City of Sunnyvale, and DOF housing estimates. Wait times are matched on parcel number and include applicant revision time. The 60-day rule is in Government Code section 66317. How we measured it · See all 109 jurisdictions
For ADUs permitted in 2023–2025, the median time from application to building permit in Sunnyvale was 4.6 months (142 days), based on 120 permits we could match. A quarter took longer than 7.4 months.
Sunnyvale issued 222 ADU building permits in 2023–2025, about 74 a year. ADUs were 25% of all new homes permitted there.
The median time from building permit to certificate of occupancy was 12.5 months for ADUs completed in 2023–2025.