ADU rules in Box Elder

Box Elder allows one detached ADU per lot as a permitted accessory use (P-A) in the Agricultural (AG), Rural Residential (RR), Low Density (R-1), Moderate Density (R-2) and High Density (R-4) residential districts. Detached ADUs are barred in the R-3 Multi-family district, the Planned Development district and all commercial and industrial districts. On lots smaller than 6,500 square feet the ADU must be inside the main structure, so a detached unit needs at least that much lot area.

An internal ADU (created within the footprint of the primary dwelling) is a permitted accessory use in AG, RR, R-1, R-2 and R-4, and also in the Planned Development (PD) district; it is barred in R-3 and the nonresidential districts. Only one ADU, internal or detached, is allowed per lot, and an internal ADU is not allowed inside a mobile or manufactured home. The code defines an internal ADU as one created 'for the purpose of offering a long-term rental of thirty (30) consecutive days or longer'.

Section 44-156 requires the ADU to be smaller than the footprint of the primary dwelling unit and caps it at 1,200 square feet in all cases. Lots under 6,500 square feet may have an ADU only within the main structure. The primary dwelling's setbacks and lot coverage limits apply to both internal and detached ADUs, and design standards require a pitched roof (unless the house has a flat roof), at least 20 percent shared exterior materials and 50 percent matching color on every facade, a separate entrance, and no separate utility meters.

The property owner or an immediate family member must live in either the primary dwelling or the ADU, and the code defines 'property owner' as full-time residency by the bona fide owner shown on the Pennington or Meade County tax assessment rolls. The requirement is ongoing: on sale of the primary dwelling the ADU may remain only while it fully complies with city ordinances. South Dakota has no statute preempting local owner-occupancy rules.

Parking for any ADU must be provided on-site and is in addition to the parking required for the primary dwelling unit, with a minimum of one space per ADU. Landscaping must provide a visual buffer for that on-site parking from adjacent properties and rights-of-way. No state law limits ADU parking in South Dakota.

ADUs are listed as 'P-A' (Permitted Accessory) in the land use matrix and §44-156 says an ADU 'shall be allowed as a permitted use' in the listed districts, so no conditional use hearing (the 'C' and use-on-review track in §44-669) applies. Review is by the Zoning Administrator, who may require inspections by city departments, together with a building permit through the planning department's Civic Access portal; accessory uses may only be built with or after the building permit for the primary use.

Section 44-156 states 'An ADU shall not be used as a short term rental', and the code defines a short-term rental as rental of any house or part of a house for less than 28 days; the internal-ADU definition frames the unit as a long-term rental of 30 consecutive days or longer. Because the owner or an immediate family member must reside in one of the two units, one unit can be rented long-term. The ADU may not be sold separately or subdivided from the primary dwelling. Whole-house vacation home rentals elsewhere need a city business license (§44-174) and, under state law, a Department of Health lodging license, but that route is closed to the ADU itself.