ADU rules in Sioux Falls

A detached accessory dwelling unit is a 'permitted special' accessory use in the five single-family detached dwelling forms: DD1 (RR district), DD2 (RS, RD-1, RD-2, RA-1 and MH districts), DD3 (RT-1 and RT-2), DD4 (RHP historic preservation district) and DD7 (RCD residential cluster PUD). Only one additional unit is allowed per lot, it must sit in the rear yard at least ten feet from the main dwelling, and it must keep the principal building's required yards (DD1 adds a 60-foot front setback or six-foot recess behind the house front). The manufactured-home forms (DD5, DD6), the attached and multiple dwelling forms do not list the use.

No attached or internal ADU use exists; a second unit attached to or inside a house is lawful only as a duplex (AD1 form) in RD-1, RD-2, RA-1, RA-2, LW and S-2 PUD, not in RS or RR (nor RT-1 or RHP). The § 160.005 definition covers attached units, but every DD form authorizes only 'Accessory dwelling units, detached' and permits a single-family dwelling as its only principal use. The AD1 duplex is a plain permitted principal use (zoning and building permits, no hearing) that must meet the AD1 bulk rules: 50 feet of lot frontage for two dwellings on one lot, 25-foot front and rear yards, 5-foot side yards and 35 feet of height, plus one parking space per unit (two for a unit with three or more bedrooms unless the home predates 1983). The ADU owner-occupancy and 40 percent size rules do not apply to a duplex.

Each DD form caps the detached ADU at 40 percent of the square feet of the main structure; the DD2 form (the most common suburban single-family form) measures against the principal building 'not including the garage'. There is no fixed square-foot cap or ADU-specific height limit; the form's bulk regulations apply (35 feet maximum height in DD2), and detached accessory buildings may not occupy more than 30 percent of the rear yard. A unit that cannot meet the standards may seek a conditional use permit under § 160.616.

Every DD form's ADU provision states that only one additional single-family dwelling unit is allowed 'and one of the units must be owner-occupied', so the owner must live in either the house or the ADU. The text sets no recorded deed restriction and no expiry, so the requirement reads as ongoing. South Dakota has no state ADU statute preempting owner occupancy.

Ord. 34-26 (passed 5-5-2026) replaced the former rule that the ADU needed additional off-street parking under §§ 160.550 et seq. as an additional single-family dwelling with: 'A minimum of two off-street parking spaces are required. Existing off-street parking may count towards this requirement.' In practice a lot that already has two hard-surfaced off-street spaces (the standard single-family requirement) needs no new space. Parking is barred in the required front and side yards except on the driveway, per § 160.553.

A detached ADU that meets the listed standards is a 'permitted special' accessory use approved administratively through a zoning permit (§ 160.705) and building permit, with no hearing. When a standard cannot be met (for example a unit outside the rear yard), the owner may instead seek a conditional use permit heard by the planning commission under §§ 160.605 et seq., judged on whether the substitute 'should perform at the same or higher level' and stay compatible with single-family character (the 2024 case CU-019650-2024 at 4301 W. Kogel Dr. is an example). The attached route differs only in form, not in review: an AD1 duplex in RD-1, RD-2, RA-1, RA-2, LW or S-2 PUD is a permitted principal use needing zoning and building permits, with no hearing.

Because one of the two units must be owner-occupied, the other unit (house or ADU) may be rented long-term. Since 1-1-2024 every residential rental unit, long- or short-term, needs a city residential rental permit ($50 per address, a two-hour course unless a licensed manager is used, a local contact if the owner lives over 50 miles away). Chapter 160 does not separately regulate short-term rentals inside city limits; a short-term rental unit (rented in its entirety on a daily or weekly basis for more than 14 days a year while not occupied by an owner or manager) must also show a state sales tax license and a Department of Health lodging license under SDCL 34-18. Nothing in Chapter 160 provides for selling the ADU separately.