Grand Rapids, MI Accessory Structures: ADU Permits (2026)

The Grand Rapids ADU framework lives in Chapter 61 of the Code of Ordinances (Zoning Ordinance) with detailed use standards in Article 5. Following 2023 City Commission action, accessory dwelling units are now broadly permitted in low-density residential (LDR), traditional neighborhood (TN-LDR, TN-TCN, TN-TBA), Monroe North (MON, MOR), and Neighborhood Office Service (NOS) districts. Key standards: (1) one ADU per single-family lot, in attached, detached, or interior-conversion configuration; (2) maximum ADU floor area generally capped at the lesser of 850 square feet or 50 percent of the principal dwelling floor area for detached ADUs, with attached/interior conversions having more flexibility; (3) detached ADUs subject to rear-yard setback (typically 3 feet from side and rear lot lines, with greater setbacks where the ADU exceeds 1 story or specific height); (4) height limited to roughly the principal-dwelling height or 25 feet, whichever is less, for detached units; (5) parking — Grand Rapids eliminated minimum off-street parking requirements citywide in 2023, so no additional parking is required for an ADU. Building permits are issued by the Grand Rapids Development Center under the 2015 Michigan Residential Code (Michigan Construction Code Act, PA 230 of 1972, MCL 125.1501 et seq.). The Michigan Fire Prevention Code (PA 207 of 1941, MCL 29.1 et seq.) and IFC 2015 (Michigan amendments) govern smoke and CO alarm placement, egress, and fire separation. Verify current parcel zoning through Grand Rapids GIS and confirm specific design standards with Planning before designing.