ADU rules in Huron

Huron's zoning title has no accessory dwelling use, and a detached backyard unit is not possible on an ordinary residential lot. Accessory structures are defined as nonresidential (23.08.010), and 23.10.022(2) allows not more than one principal building on a platted lot except in planned developments. The only multi-building residential route is a community unit plan, a conditional use permit for a tract of at least two acres in R-2 through R-5 (23.38.006), which is a development tool rather than a backyard cottage.

There is no ADU, accessory apartment or guest-house use, but a second unit can be created as a two-family dwelling (duplex) where that use is permitted: by right in R-3 (23.20.002(2)) and in R-4 and R-5, which incorporate the R-3 uses. R-1, R-2, R-7, R-O and A allow only one-family dwellings, so a second unit there needs a rezoning. In R-3 a two-family lot needs 10,000 sq ft and 100 ft of width if platted after March 1, 2002; older lots are grandfathered at a 6,000 sq ft minimum with a 60 ft width for two-family use (23.20.008).

Because the route is a two-family dwelling, Huron sets floor-area minimums rather than a maximum: 23.20.010(2) requires each double-dwelling unit to have at least 600 sq ft on the first floor, and an upper unit at least 500 sq ft. All structures on an R lot (except R-O) may cover at most 45 percent of the lot (23.10.024(3)), and the primary dwelling is capped at three stories or 35 ft (23.20.008(1)). Detached accessory buildings in R-1, R-2, R-3, R-6 and R-7 are capped at 25 ft and at the principal building's height, but they cannot hold a dwelling.

Nothing in Title 23 requires an owner to live in either unit of a two-family dwelling, and there is no ADU provision that could carry such a rule. South Dakota has no statewide owner-occupancy rule for second units. The only owner-occupancy references in the residential chapters concern vacation rental homes, which by the state definition the code adopts (23.08.183a) are not occupied by an owner or manager during the rental.

23.36.008(2) requires two-family dwellings to have at least one parking space per dwelling unit, and not more than one two-car garage per unit; the B-2 downtown core is exempt from the table. Converting a garage to living space needs replacement parking, since 23.36.008(1) bars a building permit for a garage conversion unless other acceptable provisions are made for the required space.

A two-family dwelling is a permitted use in R-3, R-4 and R-5, so it needs only a building permit showing compliance with Title 23 and the building codes, with a site plan and parking plan (23.04.004), issued by the building inspector. No hearing is required. Anything outside that route (a second dwelling in R-1 or R-2, or a multi-building community unit plan) needs a rezoning or a conditional use permit heard by the Board of Adjustment, which Ord. 2283-23-420 (effective 7-28-2026) now routes through the hearing examiner.

Chapter 5.90 (effective April 1, 2013) requires every residential rental unit to be registered and permitted before it is rented, renewable for one, two or three years (5.90.090). A vacation rental home (rented for less than a month at a time for more than fourteen days a year with no owner or manager present, 23.08.183a) requires a conditional use permit in R-2, R-3 and R-4, plus a copy of the South Dakota Department of Health vacation home license given to the planning department before operation (23.18.004(3), 23.20.004(6), 23.22.004(18)). Ord. 2282-23-419 (effective 4-28-2026, not yet codified) added vacation rental homes and bed and breakfasts as permitted uses in B-2 and B-3. R-1 does not list the use. No separate-sale rule applies to a duplex unit beyond ordinary platting.