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Modesto ADU Regulations

Modesto offers a same-day "ADU Express" coordinated review for qualifying ministerial ADU/JADU projects. The regional Stanislaus County free ADU plan catalog (7 models, shared across six cities) is available for use here.

Official Modesto ADU Page →Design Your ADU
Population
220,000
Permit Shot Clock
60 business days
Plus 15-day completeness review
Pre-Approved Plans
Verify with city
ADU Programs
3 city programs listed
See program list below

What Makes Modesto Different

  • ADU Express: same-day coordinated review for qualifying ministerial projects
  • Stanislaus County regional free ADU plan catalog (7 models, 6 cities)
  • Valley First Credit Union "Expand. Enhance. Empower." ADU loan partnership
  • Stormwater: >500 sq ft net new impervious area needs onsite detention

Size & Building Constraints

Planning code references Municipal Code §10-4.115 Table 4.1-3. Free regional plan sets shown from 260 sq ft up.

State guarantee: California requires every city to allow at least an 800 sq ft ADU exempt from local lot coverage, FAR, and front-setback rules.

Height baseline: 16 ft for detached, rising to 18 ft within ½ mile of major transit. Attached ADUs follow the primary home, capped at 25 ft.

Sketching an ADU for Modesto? Draft a floorplan and walk through it in 3D — no sign-up required.
Open Design Tool →

Parking

Garage ADU conversions may trigger administrative review if abutting single-story homes. Otherwise state ADU parking limits govern typical ministerial cases.

Permitting Process

Primary intake via eTRAKiT online permits (select ADU). Same-day "ADU Express" coordinated review by appointment ((209) 577-5232 ext. 0 / Permits@modestogov.com).

State backstop: A complete ADU permit must receive a decision in 60 business days. If the city stalls past 30 business days, AB 253 lets you hire a certified private plan checker to force a 10-business-day decision.

Fees & Cost Programs

Example ADU Development Fees PDF (FY22/23) linked. Capital Facilities Fee policies exist separately — check bulletin for waivers/deferrals.

SB 543: No impact fees on ADUs ≤750 sq ft. Above 750 sq ft, fees scale to the ratio of ADU size vs the main home.

Modesto ADU Programs

ADU Express (same-day review)
Stanislaus County Regional ADU Plans
Valley First CU ADU Financing Partnership

Visit the official Modesto ADU page (link in hero) for current eligibility and downloads.

Owner Occupancy & JADUs

Standard ADUs in Modesto: no owner-occupancy required (made permanent in 2023).

JADUs: limited to 500 sq ft of interior livable space within an existing single-family home. Owner occupancy is required only when sanitation facilities are shared with the main house. JADUs cannot be used as short-term rentals (AB 1154 / SB 543).

Design an ADU that fits Modesto’s rules

Sketch a floorplan, walk through it in 3D, and have our planners review it for size, height, and setback compliance before you submit to Modesto.

Start Designing — FreeRequest Plan ReviewExplore FinancingCheck Local Rents

Other cities in Central Valley

Fresno
Fresno County
Bakersfield
Kern County
Stockton
San Joaquin County

Heads up: Local rules change frequently. This page summarizes publicly available state law (California Government Code §§ 66310–66342) and current local guidance for general planning purposes. Always confirm specifics with the Modesto planning desk before submitting plans. ADUMetrics does not provide legal advice.