Merced, CA Accessory Structures: ADU Rules (2026)

The City of Merced adopted detailed ADU standards in Chapter 20.42 of its Zoning Ordinance (Ord. No. 2555, adopted September 18, 2023), expressly written to conform to and not conflict with California Government Code Sections 65852.2 and 65852.22. Section 20.42.030 allows, on a lot with a proposed or existing single-family dwelling, one attached ADU, one detached ADU, and one junior ADU (JADU). A detached ADU may not exceed 1,200 square feet; an attached or converted ADU is limited to 50 percent of the primary dwelling's living area or 1,200 square feet, whichever is less. Garages and carports are excluded from these floor-area calculations, and up to 150 square feet may be added for ingress/egress. A detached ADU's height is capped at 16 feet, increasing to 18 feet (or 20 feet to match the primary roof pitch) within one-half mile of a major transit stop. Side and rear setbacks are four feet for detached ADUs. Under the statewide exemption, the City cannot use lot coverage, floor-area ratio, open space, or minimum lot size to preclude an ADU up to 800 square feet with four-foot setbacks. Per Section 20.42.040, no owner-occupancy may be imposed on ADUs permitted between January 1, 2020 and January 1, 2025; afterward, owner occupancy applies only in the R-1 zone. ADUs and JADUs require connection to public water and sewer.