ADU permit cost and fee breakdown in Sonoma, California
GetYourPermit’s researched permit-fee range for a detached accessory dwelling unit in Sonoma, with category estimates and direct reference links used in our investigation.
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ADU size
California prohibits development impact fees for ADUs of 750 sq ft or less, so the 749 / 750 / 751 steps are worth comparing.
Estimated total
GetYourPermit researched range at 750 sq ft
$6,736 – $14,041
This estimate combines our fee-schedule research and project-planning experience. Actual charges vary by parcel, plans, valuation, utilities, and outside agencies.
Typical planning amount
$10,006
Modeled at the 600 sq ft reference.
Where the money goes
These are fee components within the permit process, not separate approvals.
- Separate planning / zoning fee$350 – $800
Shown only where the City bills Planning or zoning review as a separate fee.
- Building plan check$944 – $1,888
The Building Division’s review of the drawings; part of the Building Permit process.
- Building permit issuance$1,320 – $1,673
The permit issuance charge; where plan check is bundled, the combined amount is carried here.
- Separate trade permits$600 – $1,350
Shown separately only where electrical, plumbing, or mechanical permits are billed outside a combination permit.
- School district fees$2,100 – $3,600
Possible school-district developer fees based on current thresholds and scope.
- Utility fees$800 – $3,000
Possible water, sewer, electrical, meter, or capacity-related charges.
- Processing, inspection & records$120 – $286
Fixed processing, inspection, records, and administrative charges.
- Surcharges, taxes & state fees$502 – $1,444
Percentage surcharges, construction taxes, and State-mandated charges.
The darker segment is the low end of the range; the full bar is the high end.
Published fee references
Building permit issuance
The permit issuance charge; where plan check is bundled, the combined amount is carried here.
| Fee | Amount | Basis | Source |
|---|---|---|---|
| Building Permit inspection fee by valuation | From $118 | Formula | 2023 Building Division Fee ScheduleLocation: Building Fee Schedule BL-21-AConfirms: The current schedule supplies the valuation formula but the City has announced replacement fees effective September 1, 2026. |
Plan check
Review of your drawings for code compliance.
| Fee | Amount | Basis | Source |
|---|---|---|---|
| Permit processing and plan-check fees | Set by City formula | Formula | 2023 Building Division Fee ScheduleLocation: 2023 Building Division Fee Summary Sheet, BL-02, BL-03, BL-04Confirms: The City schedule identifies application and hourly plan-review components, subject to the September 1 fee change. |
These are estimates, not official fees
Use these figures for early budgeting only. They are not a quote, not a government fee determination, and not legal advice. Actual fees depend on your parcel, your plans, your construction valuation, your utility provider, and the fee schedule in force on the day your permit is issued. Confirm every number with Sonoma before you commit money.
City reference pages for verification
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