Napa County · ADU permit data · Updated 2026-10-20
6.7months median, application to building permit, 2023–2025
That is 11% longer than the Bay Area median of 6.0 months. One in four applicants waited more than 12.8 months.
Based on 18 matched permits, under our ranking threshold of 20. Treat it as a rough read.
ADUs permitted in 2023–2025, 18 matched on parcel number. Includes time owners spent revising plans.
Source: California HCD Annual Progress Reports, filed by the City of Napa
Fast quarter, median and slow quarter, in months
Napa 4.5–12.8 mo
Napa County
Bay Area 3.8–10.5 mo
Median Fast quarter to slow quarter
Median wait
Where Napa sits among 52 ranked cities
Napa Other ranked cities Bay Area 6.0
Napa
6.7months
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
Napa
94%
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
Napa
12.8months
One applicant in four had a building permit within this time from first submission.
Source: HCD Annual Progress Reports, 2023–2025, 25th percentile
Napa
4.5months
Source: units by calendar year, as reported by the City of Napa to California HCD
Napa, units per year
ADU permits a year, 2023–2025 average
ADU permits a year per 1,000 houses, 109 places
Napa Other Bay Area places
Napa
63a year
ADU permits, 2023–2025 average
Of every home Napa permitted in 2023–2025, this share was an ADU.
Source: HCD Annual Progress Reports, 2023–2025
Napa
55%
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
Napa
3.2
rank 38 of 92
Yearly ADU permits in 2023–2025, up 37% from 2019–2021.
Source: HCD Annual Progress Reports
Napa
+37%
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
Napa
8.6months
median of 73
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
Napa
14.0months
Every page in Napa County: median wait where we can measure it, otherwise ADU permits a year
Timeline tool
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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 Napa, 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 Napa was 6.7 months (204 days), based on 18 permits we could match. A quarter took longer than 12.8 months.
Napa issued 189 ADU building permits in 2023–2025, about 63 a year. ADUs were 55% of all new homes permitted there.
The median time from building permit to certificate of occupancy was 8.6 months for ADUs completed in 2023–2025.