Modesto, CA Accessory Structures: ADU Permits (2026)

MMC 10-4.115 implements Cal. Gov. Code 65852.2 in Modesto. Detached new-construction ADUs may be up to 800 square feet with a maximum height of 16 feet for one-story (or up to 25 feet, or two stories, when attached to the primary dwelling, subject to underlying zone limits). Side and rear setbacks are a minimum of 4 feet, consistent with state law. JADUs are capped at 500 square feet and must be contained within the walls of an existing or proposed single-family dwelling. Cal. Gov. Code 65852.2(b)(1) requires Modesto to act on a complete ADU application within 60 days; if not acted upon, the application is deemed approved. Applications use the Modesto ePlans portal and must include a site plan, floor plans, elevations, California Building Standards Code compliance, and confirmation of water/sewer service. Parking can be required at up to one space per bedroom but is waived where the property is within one-half mile of a transit stop or otherwise exempt under state law. Modesto's ADU Express Program offers same-day plan review for ministerial projects using pre-approved plans, and Stanislaus County partners with Modesto on a free pre-approved ADU plan library.