ADU permit cost and fee breakdown in Fairfield, California
GetYourPermit’s researched permit-fee range for a detached accessory dwelling unit in Fairfield, 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
$5,690 – $8,780
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
$7,110
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$250 – $450
Shown only where the City bills Planning or zoning review as a separate fee.
- Building plan check$1,050 – $1,780
The Building Division’s review of the drawings; part of the Building Permit process.
- Building permit issuance$1,260 – $2,140
The permit issuance charge; where plan check is bundled, the combined amount is carried here.
- Separate trade permits$190 – $320
Shown separately only where electrical, plumbing, or mechanical permits are billed outside a combination permit.
- School district fees$2,550 – $3,330
Possible school-district developer fees based on current thresholds and scope.
- Processing, inspection & records$190 – $280
Fixed processing, inspection, records, and administrative charges.
- Surcharges, taxes & state fees$200 – $480
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 |
|---|---|---|---|
| ADU Building Permit and review fees | From $186 | Formula | Residential Fees for Accessory Dwelling Unit(s)Location: FY2026-27 ADU fee schedule, rows 1–10Confirms: The dedicated current City ADU schedule supplies the valuation basis and each named plan-review, MEP, and technology calculation. |
Impact fees
Development impact fees. Prohibited for ADUs of 750 sq ft or less.
| Fee | Amount | Basis | Source |
|---|---|---|---|
| ADU development and connection fee rule | From $0 | Formula | Residential Fees for Accessory Dwelling Unit(s)Location: FY2026-27 ADU fee schedule, rows 13–33 and notes (1)–(2)Confirms: The current City schedule directly establishes the 750-square-foot exemption, the proportional formula above that boundary, and the City-collected base fee layers. |
School district fees
Developer fees charged by the local school district.
| Fee | Amount | Basis | Source |
|---|---|---|---|
| ADU school development-fee lookup | Verify on the City’s official website | Verify on the City’s official website | Residential Fees for Accessory Dwelling Unit(s)Location: FY2026-27 ADU fee schedule, rows 23–24Confirms: The City identifies the school layer but directs applicants to Fairfield-Suisun Unified or Travis Unified for current developer fees. |
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 Fairfield before you commit money.
City reference pages for verification
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