Rapid City, SD Accessory Structures: ADU Rules (2026)

219, most recently amended by Ordinance 6714 in 2026, sets Rapid City's accessory dwelling unit standards. Subsection C requires owner occupancy: no ADU may be created, established or occupied in a single-family dwelling unless the property owner lives full time in either the main dwelling or the detached accessory unit, as shown on the Pennington County tax assessment rolls. Subsection D limits where an ADU can go: within or as part of a single-family dwelling, or in a qualifying detached accessory structure, only in the Low Density Residential-1, Medium Density Residential, High Density Residential, Low Density Residential-2 or General Agricultural districts, while the Park Forest district allows an ADU only as part of the single-family dwelling itself, not as a detached unit.

Subsection E caps every owner-occupied lot at one accessory dwelling unit. Subsection G adds area limits on top of the underlying zoning district's standards: a detached ADU cannot sit in the front yard, cannot cover more than 10% of the lot, must be smaller than the primary dwelling's footprint (excluding any attached garage), and on a lot under 6,500 square feet an ADU is allowed only inside the main structure, not as a detached unit. Subsection I requires 3 total off-street parking spaces, two for the primary dwelling and one for the ADU, and subsection N requires every ADU, including ones built before December 2, 2019, to register with the Department of Community Development, submitting a site plan, floor plans and the applicable building permit fees.