Can I build an ADU in Madera County?

Yes. California state law requires Madera County and its cities to allow ADUs on residentially-zoned single-family and multifamily properties. The county handles unincorporated areas; the City of Madera, Chowchilla, and any other incorporated cities have their own building departments.

Are there special considerations for mountain areas of Madera County?

Yes. Eastern Madera County includes areas adjacent to Sierra National Forest and the gateway to Yosemite, with mountain communities like Oakhurst, Bass Lake, and North Fork. These areas may have fire hazard severity zone (FHSZ) designations that require ignition-resistant construction (Chapter 7A CBC), additional setbacks from vegetation, and defensible space clearance. Confirm your parcel's fire hazard designation with the county before designing your ADU.

Does Madera County have septic requirements for ADUs?

Many unincorporated Madera County parcels — especially in rural and mountain areas — rely on septic systems and private wells. A septic capacity evaluation or percolation test is typically required to show the existing system can handle the additional dwelling. If the system cannot handle the added load, expansion or replacement may be required as a condition of the ADU permit.

How long does permit review take in Madera County?

California law requires the jurisdiction to act on complete ADU applications within 60 days. Madera County's Planning Department handles a much lower volume than urban Bay Area counties, but incomplete applications still cause delays. Submit complete plans from the start.

What fire building code applies to ADUs in fire hazard severity zones?

ADUs in State Responsibility Areas (SRA) or areas with Very High Fire Hazard Severity Zone (VHFHSZ) designations must comply with CBC Chapter 7A — Ignition-Resistant Construction. This includes requirements for exterior wall cladding, eaves, vents, decking, and glazing. Defensible space clearance (30/100 feet) is also enforced by CAL FIRE.

Madera County ADU Requirements (2026)

Who this guide is for

If you're planning to build an ADU in Madera County — in unincorporated county land, the City of Madera, Chowchilla, or a mountain community like Oakhurst — this guide covers the key requirements before submitting plans.

Madera County spans from the San Joaquin Valley floor to the Sierra Nevada foothills and mountains, creating diverse terrain with significantly different building requirements. This guide focuses on unincorporated Madera County; city rules may vary.

Jurisdiction overview

Jurisdiction	Planning authority	Notes
Unincorporated Madera County	Madera County Planning Department	Valley and mountain areas; fire hazard zones in east
City of Madera	Madera Planning Division	Urban core, valley floor
City of Chowchilla	Chowchilla Community Development	Northern county; contact for standards
Mountain communities (Oakhurst, Bass Lake, North Fork)	Unincorporated county	CAL FIRE SRA, fire hazard zones apply

Size limits

ADU type	Maximum size
Detached ADU	Up to 1,200 sq ft
Attached ADU	Up to 50% of existing living area, or 1,200 sq ft — whichever is less
JADU (Junior ADU)	Up to 500 sq ft, within existing structure
Garage conversion	Full existing garage area

Setback requirements

Setback	Requirement
Side and rear (new construction)	4 ft minimum (state law)
Front	Per underlying zoning district
Conversion of existing structure	No additional setback required
Height limit (detached)	16 ft
Fire hazard zone setbacks	Additional setbacks from vegetation may apply

Required documents

A complete ADU application for unincorporated Madera County typically requires:

Permit application form — Madera County Planning Department
Site plan — parcel boundaries, setbacks, existing structures, proposed ADU, access, utilities, drainage
Floor plan — dimensioned rooms, fixtures, egress, door swings
Elevations — all four sides, heights, exterior materials
Structural plans — foundation, framing, seismic resistance
Title 24 energy compliance — CF1R forms
CalGreen checklist — mandatory green building measures
Proof of ownership — deed or title
Septic evaluation — for parcels not on public sewer
Chapter 7A compliance documentation — for parcels in fire hazard severity zones

Fire hazard construction requirements

Eastern Madera County — including most mountain communities near Sierra National Forest — falls within State Responsibility Areas (SRA) and Very High Fire Hazard Severity Zones. If your parcel is in these areas:

CBC Chapter 7A applies: ignition-resistant construction required
Exterior wall cladding: must meet ignition-resistance standards (no wood siding without treatment)
Eaves and soffits: enclosed or protected
Vents: ember-resistant venting required
Decking: Class A or ignition-resistant materials
Glazing: multi-pane or tempered required for wildfire exposure
Defensible space: 30-foot Zone 1 and 100-foot Zone 2 clearance required (enforced by CAL FIRE)

This is one of the most common sources of plan check corrections for mountain ADU projects. Have a Chapter 7A compliance narrative prepared before submitting.

Fees

California limits ADU fees:

No impact fees for ADUs under 750 sq ft
Proportional impact fees for ADUs 750 sq ft and above
No school fees for ADUs

Madera County fees are lower than coastal counties. As of 2026:

Building permit fee: $1,500–$4,000 depending on project valuation
Plan check fee: Typically 65% of building permit fee
Septic evaluation/connection: Varies by parcel

Common reasons ADU plans are sent back

Chapter 7A compliance not addressed for fire hazard zone parcels
Septic evaluation missing for rural and mountain parcels
No Title 24 energy forms included
Structural plans incomplete — no seismic lateral resistance details
Site plan missing north arrow, scale, setback dimensions
Elevations missing one or more sides
No ignition-resistant construction details for exterior materials in SRA areas

A pre-check before submission catches these issues before the building department does.