Fresno County

Unincorporated Fresno County ADU rules

Research summary of what we found for Unincorporated Fresno County in Fresno County. Not a determination for a specific lot.

Last checked October 24, 2026.

City or county ADU page

Unincorporated Fresno County Planning department. No ADU-specific page was found.

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How big can an ADU be in Fresno County?

Maximum size
An ADU may be up to 850 sq ft with fewer than two bedrooms, or 1,000 sq ft with two bedrooms. No more than two bedrooms are allowed. An attached ADU is also limited to 50% of the main home's floor area, up to 1,200 sq ft. A detached ADU up to 800 sq ft with 4 ft side and rear setbacks may be built alongside a JADU.
Source: Fresno County Zoning Ordinance Article 4 (March 2026), Section 834.4.030 Additional On-Site Dwellings, § 834.4.030(B)(5)(b)(2), (B)(7)(a), accessed 2026-11-01.

ADU setbacks in Fresno County

Setbacks
A detached ADU needs 4 ft side and rear setbacks. An attached ADU needs the side and rear setbacks the building and fire codes call for. No setback is needed when a legally existing structure is converted to an ADU. No passageway between buildings is required.
Source: Fresno County Zoning Ordinance Article 4 (March 2026), Section 834.4.030 Additional On-Site Dwellings, § 834.4.030(B)(5)(b)(2), (B)(5)(d)(2), (B)(7), accessed 2026-11-01.

What we found for Fresno County

What we have for this place. Where a local figure is stricter than the California state baseline, both are shown.

Local ADU rules
The County's ADU and JADU rules are in Zoning Ordinance Section 834.4.030 (Additional On-Site Dwellings), in Article 4 of the zoning ordinance as published in March 2026. The ordinance number and adoption date of this text were not found. ADU and JADU permits are ministerial, and the County issues the permit within 60 days of a complete application. Its standards are subject to changes the State makes to ADU law.
Source: Fresno County Zoning Ordinance Article 4 (March 2026), Section 834.4.030 Additional On-Site Dwellings, § 834.4.030(B), (B)(7)(f)(1), accessed 2026-11-01.

ADU types and how many
On a lot with a single-family home, a detached ADU up to 800 sq ft, 16 ft tall, with 4 ft side and rear setbacks is allowed alongside a JADU. On a lot with a multifamily building: ADUs inside non-livable space up to 25% of the existing units, and at least one. No minimum lot size or width applies.
Source: Fresno County Zoning Ordinance Article 4 (March 2026), Section 834.4.030 Additional On-Site Dwellings, § 834.4.030(B)(5)(b)-(d), accessed 2026-11-01.

Low Water Area and small well-and-septic lots
The code does not allow ADUs or JADUs in the County's Low Water Area (shown on the County of Fresno Low Water Area Map, generally east of the Friant-Kern Canal or west of Interstate 5), or on lots under 2 acres served by a private well and septic system. Check with County Zoning whether your parcel is in one of these areas before you apply. State law may still allow some ADUs here (Gov. Code § 66323).
Source: Fresno County Zoning Ordinance Article 4 (March 2026), Section 834.4.030 Additional On-Site Dwellings, § 834.4.030(B)(3)(a)-(b), accessed 2026-11-01.

Height
A single-story detached ADU may be 16 ft above grade, measured to the peak. A two-story detached ADU is allowed in the AE, AL, A-2, R-R, R-C and R-S zones, up to the zone's height limit.
Source: Fresno County Zoning Ordinance Article 4 (March 2026), Section 834.4.030 Additional On-Site Dwellings, § 834.4.030(B)(7)(b), accessed 2026-11-01.

Parking
One off-street space per attached or detached ADU, in addition to the main home's parking. It may be tandem, including on an existing driveway; front-yard parking only on the paved driveway. No space is needed within a half mile walk of public transit, in a historic district, for an ADU inside the home or an accessory structure, where on-street permits are required but not offered, or within one block of a car share space. Parking lost when a garage or carport is removed or converted does not have to be replaced. Converted ADUs and JADUs need no parking.
Source: Fresno County Zoning Ordinance Article 4 (March 2026), Section 834.4.030 Additional On-Site Dwellings, § 834.4.030(B)(7)(e), accessed 2026-11-01.

Junior ADUs
A JADU may be up to 500 sq ft inside the home, with up to 150 sq ft added only for entry and exit. A deed restriction is recorded before the building permit is issued, and the JADU may not be sold separately from the home. No parking is needed.
Source: Fresno County Zoning Ordinance Article 4 (March 2026), Section 834.4.030 Additional On-Site Dwellings, § 834.4.030(B)(4), accessed 2026-11-01.

Fees, utilities and rental
No impact fees (including school fees) for an ADU under 750 sq ft; larger ADUs pay in proportion to the main home's size. Water and sewer connection fees are separate. Attached and detached ADUs need new, separate utility connections to the provider. Fire sprinklers are needed only if the main home needs them. An ADU may not be rented for less than 30 days and may not be sold separately unless state law allows it.
Source: Fresno County Zoning Ordinance Article 4 (March 2026), Section 834.4.030 Additional On-Site Dwellings, § 834.4.030(B)(6)(i), (B)(7)(d), accessed 2026-11-01.

County ready-made ADU plans
The County offers ready-made ADU plans at no cost to homeowners, in several sizes with three options each. You still need a site plan and a grading and drainage plan, and a septic permit where needed. Check with County Zoning ((559) 600-4540) that ADUs are allowed on your parcel first.
Source: Fresno County Building and Safety, Accessory Dwelling Unit (ADU) page, accessed 2026-11-01.

California state rules

The statewide baseline recorded from state law and the HCD ADU Handbook.

Detached size cap described in state law
1,200 sq ft. From Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Side and rear setback cap for a new ADU
4 ft. From Government Code section 66314, which describes a cap on side and rear setbacks for a new ADU.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Setback for a conversion of an existing structure
No additional setback, from Government Code section 66314 for a conversion of an existing structure.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Minimum lot size
A city may not impose a minimum lot size for an ADU, from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Minimum unit the handbook says cities must allow
At least an 800 sq ft ADU with 4 ft side and rear setbacks. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(3).
Source: HCD ADU Handbook, 66321(b)(3); handbook updated March 2026, accessed 2026-10-16.

Detached height described in the handbook
16 ft, or 18 ft or 20 ft in some cases. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(4).
Source: HCD ADU Handbook, 66321(b)(4); handbook updated March 2026, accessed 2026-10-16.

Permit decision deadline
60 days. From Government Code section 66317(a)(3): the permitting agency must decide on (approve or deny) a completed ADU application within 60 days when an existing single-family or multifamily dwelling is on the lot. Section 66317(a)(1) says the application is considered ministerially, without discretionary review or a hearing.
Source: California Government Code section 66317, 66317(a)(1), (a)(3), accessed 2026-10-17.

Owner-occupancy requirement
None. From Government Code section 66315: a local agency may not impose an owner-occupancy requirement on an ADU. It may require that the property be used for rentals of terms 30 days or longer. The HCD ADU Handbook (updated March 2026) describes the same rule.
Source: California Government Code section 66315, 66315; HCD ADU Handbook updated March 2026, accessed 2026-10-17.

Parking near public transit
No parking standards within one-half mile walking distance of public transit. From Government Code section 66322(a)(1). Section 66322(a) lists several other cases where parking standards may not be imposed.
Source: California Government Code section 66322, 66322(a), accessed 2026-10-17.

Ministerial categories
The HCD ADU Handbook (updated March 2026) states that Government Code section 66323 sets four ministerial categories. What we have does not restate those four categories.
Source: HCD ADU Handbook, 66323; handbook updated March 2026, accessed 2026-10-16.

Fire Hazard Severity Zones
If your lot is in a Fire Hazard Severity Zone, the CAL FIRE Office of the State Fire Marshal says in Information Bulletin 25-004 (issued March 3, 2025): “Fire Hazard Severity Zones (FHSZs) should not restrict the development of Accessory Dwelling Units (ADUs). However, additional building standards may be necessary, including but not limited to California Fire Code Chapter 49 and California Building Code Chapter 7A.” State ADU law does not itself bar an ADU there. A city or county may still apply its building code, including wildfire-resistant construction (Gov. Code 66314(d)(8)); require side and rear setbacks “sufficient for fire and safety” for a unit converted under 66323(a)(1); and decline parking in setbacks on specific fire and life safety findings (66314(d)(10)(B)). It may also consider public safety when it designates where ADUs may be permitted (66314(a)). Sprinklers can't be required in an ADU or JADU if the primary residence doesn't need them (66314(d)(12), 66323(d)). Some cities and counties still apply their own fire-zone limits. Where this summary has one, it is listed with the local rules. This summary does not look up your lot. Check the CAL FIRE Fire Hazard Severity Zone map viewer linked from the State Fire Marshal's Fire Hazard Severity Zones page: https://experience.arcgis.com/experience/5065c998b4b0462f9ec3c6c226c610a9
Source: CAL FIRE Office of the State Fire Marshal Information Bulletin 25-004, page 4, issued March 3, 2025; Gov. Code 66314, 66323, accessed 2026-10-20.

State baseline on the directory → · State ADU rules on the homepage →

Can I build an ADU in Unincorporated Fresno County?

State law sets a baseline for ADUs in Unincorporated Fresno County, and what we found locally is listed on this page. Whether a specific lot can add an ADU depends on zoning, utilities, and other site facts this page does not measure. Confirm with the County of Fresno planning department, or run a free address summary.

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