Fresno County, CA Accessory Structures: ADU Rules (2026)
ADU rules in Fresno County, CA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Size, 0-1 bedroom
- 850 sq ft maximum
- Size, 2 bedrooms
- 1,000 sq ft maximum
- Absolute cap
- 1,200 sq ft / 50% of primary home
- Single-story height
- 16 feet above grade
- Side/rear setback
- 4 feet minimum, detached ADU
- Prohibited areas
- Low Water Area; sub-2-acre well/septic lots
Summary
Fresno County caps detached and attached accessory dwelling units at 850 to 1,200 square feet depending on bedroom count and limits single-story units to 16 feet in height, under the ministerial ADU standards in the county's Zoning Ordinance.
(1) Detached. May not exceed 850 square feet if it has fewer than two bedrooms or 1,000 square feet if it has two bedrooms. No more than two bedrooms are allowed. A detached ADU shall not exceed 50% of the floor area of the primary dwelling and have a maximum of 1,200 square feet.
(2) Attached. May not exceed 850 square feet if it has fewer than two bedrooms or 1,000 square feet if it has two bedrooms. No more than two bedrooms are allowed. An attached Accessory Dwelling Unit shall not exceed 50 percent of the floor area of the primary dwelling. An attached Accessory Dwelling Unit shall not exceed 50 percent of the floor area of the primary dwelling to a maximum of 1,200 square feet.
b. Height.
(1) Single-Story Attached or Detached. A single-story attached or detached Accessory Dwelling Unit shall not exceed 16 feet in height above grade, measured to the peak of the structure.
(2) Two-Story. A detached Accessory Dwelling Unit that is constructed with a second story shall be permitted in the AE, AL, A-2, R-R, R-C and R-S zone districts not exceeding the maximum allowable structure height for the area in which it is located.
Full Breakdown
22) through a ministerial permitting process. " The same size cap and the 50%-of-primary-dwelling rule apply to attached ADUs. 030(B)(7)(b): "A single-story attached or detached Accessory Dwelling Unit shall not exceed 16 feet in height above grade, measured to the peak of the structure," while two-story detached ADUs are permitted only in the AE, AL, A-2, R-R, R-C and R-S zone districts up to the zone's maximum structure height. 030(B)(3)). No minimum parcel size or width applies to build an ADU, and a detached, new-construction ADU must have side and rear setbacks of at least four feet.
Violations & Fines
An ADU built beyond the 850/1,000/1,200 square-foot caps, over the 16-foot single-story height limit outside the listed two-story-eligible zones, or in a prohibited Low Water Area or undersized well-and-septic parcel is a zoning violation and can be denied a Building Permit or subjected to county code enforcement.
Frequently Asked Questions
How big can an ADU be in unincorporated Fresno County?
How tall can an ADU be?
Are ADUs allowed everywhere in the unincorporated county?
Sources & Official References
Other rules in Fresno County
How Fresno County compares: Easiest Cities to Build an ADU·California rules heatmap·Compare Fresno County to another location·View the California accessory structures overview
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