ADU Builder in Danville, CA
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Larger ADUs on Larger Danville Lots
Danville allows more ADU space than most Bay Area cities. Under the Town’s ADU rules (FAQ updated November 2025):
- Up to one attached ADU, one junior ADU and one detached ADU on a single-family lot.
- ADUs up to 1,200 sq ft, or up to 2,000 sq ft in zoning districts with lots over 40,000 sq ft.
- An attached ADU is limited to 50% of the main home, but an 800 sq ft ADU is always allowed.
- Junior ADUs up to 500 sq ft, with the owner living on the property.
- Detached ADUs 16 feet tall, or up to 24 feet if they meet the main home’s setbacks. Attached ADUs up to 25 feet.
- 4-foot side and rear setbacks; front setbacks follow the zoning district.
- One parking space, with state exemptions. The Town publishes an ADU parking map.
- New detached ADUs require solar. Fire sprinklers are required only if the main home requires them.
- Rentals must be 30 days or longer.
ADU Construction
The Garden Cottage Program
Danville has offered free, permit-ready detached ADU plans through its Garden Cottage Program, in studio, one-bedroom and two-bedroom versions and Craftsman, Mediterranean or Contemporary styles, with expedited review. We can build from a Garden Cottage plan or design a custom ADU that matches your home in colors, siding and roofing as the Town requires.
The Danville ADU Permit Sequence
- Confirm zoning and setbacks with the Planning Division.
- Look up your project type in the Town’s Permit Directory for submittal requirements.
- Get Central San review and stamp before you apply for additions beyond the existing footprint, decks, ADUs, carports, generators and ground-mounted solar.
- Complete the building permit application and the Outside Agency Checklist.
- Submit in person or online.
- Obtain a San Ramon Valley Fire Protection District approval letter before permit issuance, and its final letter before the Town final.
500 La Gonda Way, Danville, CA 94526
Town offices (925) 314-3388 · Permit Center (925) 314-3330 · Planning (925) 314-3310
Applications can be submitted in person or through the Town’s Online Permit Center / Citizen Access Portal. Inspections: danville.ca.gov/CAP or (925) 314-3333, before 3 p.m. for the next business day.
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Danville ADU FAQ
How big can an ADU be in Danville?
Up to 1,200 sq ft, or up to 2,000 sq ft in districts with lots over 40,000 sq ft. A junior ADU is up to 500 sq ft.
Does Danville have pre-approved ADU plans?
Danville has offered free permit-ready detached plans through its Garden Cottage Program.
Do I need Central San approval for an ADU?
Yes. Central San reviews and stamps ADU plans before you apply for the building permit.
Is solar required on a Danville ADU?
New detached ADUs require solar.