Share of new homes that are ADUs
Of every home Unincorporated Alameda County permitted in 2023–2025, this share was an ADU.
Source: HCD Annual Progress Reports, 2023–2025
Unincorporated Alameda County
52%
Alameda County · ADU permit data · Updated 2026-10-20
How long does an ADU permit take in Unincorporated Alameda County?
102permits a year ADU building permits, 2023–2025 average
- Bay Area
- 6.0 mo
- Status
- Too few
- Rank
- unranked
We cannot publish a reliable wait time for unincorporated Alameda County. Fewer than 10 ADUs here could be matched from application to permit in 2023–2025.
State limit Bay Area months
60 days
6.0 mo
Permit wait
All 52 ranked citiesMonths from ADU application to building permit
Bay Area figures for reference. Fewer than 10 ADUs here could be matched from application to permit in 2023–2025.
Source: California HCD Annual Progress Reports, filed by Alameda County
Fast quarter, median and slow quarter, in months
Alameda County
Bay Area 3.8–10.5 mo
Median Fast quarter to slow quarter
Median wait
- Alameda County 6.3 mo
- Bay Area 6.0 mo
- Livermore fastest nearby 3.0 mo
- Piedmont slowest nearby 8.0 mo
Median wait in the 52 ranked cities
Other ranked cities Bay Area 6.0
Bay Area
6.0months
median of 5,578 matched Bay Area permits, 2023–2025
Permits issued
305 ADU permits, 2023–2025ADU building permits issued and ADUs finished, by year
Source: units by calendar year, as reported by Alameda County to California HCD
Unincorporated Alameda County, units per year
ADU permits a year, 2023–2025 average
ADU permits a year per 1,000 houses, 109 places
Uninc. Alameda Co. 2.9
Uninc. Alameda Co. Other Bay Area places
Unincorporated Alameda County
102a year
ADU permits, 2023–2025 average
ADU permits per 1,000 houses
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
Unincorporated Alameda County
2.9
rank 42 of 92
Change since 2019–2021
Yearly ADU permits in 2023–2025, up 168% from 2019–2021.
Source: HCD Annual Progress Reports
Unincorporated Alameda County
+168%
Build time
118 finished ADUsBuilding permit to finished ADU
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
Unincorporated Alameda County
11.1months
median of 118
Slow quarter of builds took longer than
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
Unincorporated Alameda County
17.7months
Alameda County
15 cities and areas · all citiesMedian Fast quarter to slow quarter Bay Area median, 6.0 months Number is the rank out of 52 cities
06121824
median - 4Livermore 3.0
- 5Albany 3.2
- 10Alameda 4.3
- 26Hayward 5.7
- 29San Leandro 6.2
- 36Fremont 7.0
- 39Oakland 7.3
- 42Piedmont 8.0
Every page in Alameda County: median wait where we can measure it, otherwise ADU permits a year
Planning an ADU in Unincorporated Alameda County
- 1 After the permit, ADUs here took a median of 11.1 months to reach a certificate of occupancy (Bay Area: 13.0).
- 2 Unincorporated Alameda County permits about 102 ADUs a year, up 168% from 2019–2021. Local designers and builders have recent examples to show you; ask for permitted ADUs in Unincorporated Alameda County, not elsewhere.
- 3 The part of the wait you control is the first submission. Complete drawings, a site plan that matches the survey, and answers to the city's ADU checklist cut down on correction rounds.
- Read next: why home plans get sent back · permit drawings vs. full plans · architect fee calculator
Timeline tool
When would your permit come through?
Pick a start date and see the fast, likely and slow dates for Unincorporated Alameda County, from the numbers on this page.
Estimate my permit datesNext step
Not sure who to call first?
Answer a few questions about your lot and your plans. We point you to the right kind of help for an ADU in Unincorporated Alameda County: an architect, a permit-drawing team, or a design-build firm. About two minutes, no call list.
Find the right first callStart with the city's own rules: ADU rules and process.
- Sheet
- C-195
- Drawing
- ADU permit record, unincorporated Alameda County
- Date
- 2026-10-20
- Scale
- Not to scale
- Drawn by
- Bay Area Architect
Source: Bay Area ADU Permit Clock 2026, our analysis of the California HCD Housing Element Annual Progress Reports (data.ca.gov) filed by Alameda County, 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
Common questions
How long does it take to get an ADU permit in Unincorporated Alameda County?
There are not enough comparable records to give a reliable number for unincorporated Alameda County. Across the Bay Area the median was 6.0 months.
How many ADUs does Unincorporated Alameda County approve?
Unincorporated Alameda County issued 305 ADU building permits in 2023–2025, about 102 a year. ADUs were 52% of all new homes permitted there.
How long does it take to build an ADU in Unincorporated Alameda County?
The median time from building permit to certificate of occupancy was 11.1 months for ADUs completed in 2023–2025.