Accessory Structures in Modesto, CA (2026)
9 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 No. 3762-C.S., section 2, effective May 11, 2023, repealed section 10-4.115, which pertained to accessory dwelling units.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.)
ADU Permits
Modesto processes accessory dwelling units ministerially under Modesto Municipal Code section 10-4.115, consistent with California Government Code section 65852.2. Applications go through the Community and Economic Development Department's Building Safety Division at 1010 10th Street. Decisions are required within 60 days of a complete application under state law, with no public hearing or design review.
Modesto ADU Permit Process
Few RestrictionsADU Impact Fees
Modesto is bound by Cal. Gov. Code 65852.2(f)(3)(A), which prohibits any local agency - including Modesto - from charging impact fees on ADUs under 750 square feet. ADUs at or above 750 sq ft may be charged impact fees only in proportion to the square footage burden imposed by the primary dwelling. Modesto Irrigation District water charges and Stanislaus County school developer fees may still apply where authorized.
Modesto ADU Impact Fees
Few RestrictionsADU Owner Occupancy
Modesto does not require owner-occupancy for ADUs, consistent with Cal. Gov. Code 65852.2(a)(8) as amended by AB 587 (2019) and AB 976 (2023), which permanently prohibit owner-occupancy as a condition of ADU permitting. JADUs, however, continue to require owner-occupancy under Cal. Gov. Code 65852.22(a)(2) - the owner must reside in either the primary dwelling or the JADU, and a deed restriction is recorded with Stanislaus County.
Modesto ADU Owner Occupancy
Few RestrictionsADU Rental Restrictions
Modesto ADUs cannot be rented for fewer than 30 consecutive days under Cal. Gov. Code 65852.2(a)(6) and MMC 10-4.115. Long-term rentals (31+ days) are permitted with no city-issued occupancy permit. ADUs may not be sold separately from the primary residence unless Modesto adopts an opt-in ordinance under AB 1033 (Cal. Gov. Code 65852.26), which the city has not done. Short-term rentals citywide require a Transient Occupancy Registration Permit under MMC 8-2-606.
Modesto ADU Rental Restrictions
Some RestrictionsShed 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...
Carport Rules
Modesto's zoning code regulates carports as accessory structures under MMC §§ 10-4.107, 10-4.108, and 10-4.114, imposing minimum setbacks, a one-story height cap, and maximum floor area tied to lot size.
Carports Subject to Setback, Height, and Size Limits
Some RestrictionsTiny Homes
Modesto regulates tiny homes through its Accessory Dwelling Unit ordinance at Modesto Municipal Code 10-4.115, consistent with California Government Code 65852.2. Detached tiny-home ADUs are limited to 800 square feet, 16 feet in height (with state-permitted exceptions), and 4-foot side and rear setbacks. Tiny homes on wheels (THOWs) are not recognized as permanent ADUs.