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 No. 3762-C.S., section 2, effective May 11, 2023, repealed section 10-4.115, which pertained to accessory dwelling units.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 MC section 10-4.504(c)(3) allows a detached garage (or interior living space) to be converted to an ADU ministerially. Section 10-4.506(c)(1) permits up to a 150 sq ft expansion of the existing footprint solely for ingress/egress. Replacement parking is not required when the converted garage was meeting an existing parking standard.
Garage conversions: ADU pathway with 150 sq ft expansion
Few RestrictionsModesto MC sections 10-4.504(c)(3) and 10-4.506(c)(1)
10-4.504(c)(3): 'A converted ADU may be located within an existing single-family dwelling (i.e., in living space to be converted to an ADU, e.g., a master bedroom suite), or within an existing detached accessory structure (e.g., a detached garage).' 10-4.506(c)(1): 'When an existing detached accessory structure is converted to an ADU, a maximum one-hundred-fifty (150) square-foot expansion beyo...
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