Accessory Structures in Modesto, CA (2026)
3 verified accessory structures rules for Modesto, California, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Modesto Municipal Code Article 5 (sections 10-4.501 to 10-4.512) permits ADUs ministerially on lots with a single-family or duplex dwelling, capping detached units at 1,200 sq ft and 16 ft in height (18 ft near major transit), with 4 ft side and rear setbacks. Standards mirror Govt Code section 65852.2.
ADU rules: 1,200 sq ft cap, 16 ft height, 4 ft setbacks
Some RestrictionsModesto MC sections 10-4.501 to 10-4.512 (Ord. No. 3762-C.S., eff. May 11, 2023)
Ord. No. 3762-C.S., section 2, effective May 11, 2023, repealed section 10-4.115, which pertained to accessory dwelling units. (Current standards are codified at sections 10-4.501 through 10-4.512: minimum four (4) foot side and four (4) foot rear yard setbacks; detached ADU height limit of sixteen (16) feet, or eighteen (18) feet within one-half mile walking distance of a major transit stop.)
Shed & Carport Rules
Modesto MC section 10-4.114 governs detached accessory buildings (sheds, workshops, gazebos, detached garages) on single-family residential lots, limiting them to one story / 16 ft and 4 ft side/rear setbacks. Sheds 120 sq ft or smaller may sit on the property line. Lot-coverage caps scale with lot size from 400 to 1,000 sq ft.
Sheds & accessory buildings: 16 ft height, 4 ft setbacks
Some RestrictionsModesto MC section 10-4.114 (Accessory Buildings)
Section 10-4.114 Accessory Buildings: Front setback 25 feet; Street side 15 feet; Side and Rear: 0 feet for structures 120 sq ft or less, 4 feet minimum for structures over 120 sq ft, 5 feet minimum distance from main house; Height: 1 story / 16 feet maximum. Maximum floor area by lot size: under 5,000 sq ft - 400 sq ft; 5,000 to 10,000 sq ft - 600 sq ft; 10,000 to 20,000 sq ft - 800 sq ft; 20,...
Garage Conversions
Modesto allows an existing attached garage, or an existing detached garage or other accessory structure, to be converted into an accessory dwelling unit under MC 10-4.504(c). A detached conversion can be enlarged by up to 150 square feet, solely for ingress and egress, and the parking the garage held does not have to be replaced.
Modesto Garage Conversion to ADU Rules
Some RestrictionsModesto Municipal Code §§ 10-4.504(c), 10-4.506(c)(1)-(2), 10-4.508(b)
Converted . An ADU may be located within a proposed or existing single-family dwelling (e.g., an existing attached garage), or other living space to be converted to an ADU (e.g., master bedroom suite); or an existing detached accessory structure to be converted to an ADU. ... When an existing detached accessory structure is converted to an ADU, a maximum one-hundred-fifty (150) square-foot expa...
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County ordinances apply to unincorporated areas and may supplement Modesto city rules.
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