Compare ADU rules across South Dakota

There is no attached or internal ADU either, but a second unit inside or attached to a house is lawful as a two-family dwelling where the district allows one. A single-family dwelling is 'a building having one dwelling unit' (Sec. 60-1), so a basement or addition with complete living facilities turns the house into a two-family dwelling. Two-family dwellings are a permitted use in R-2 (Sec. 60-54(b)(3)) and, by reference, R-3 (Sec. 60-55(b)), and in the M-AG mini-agricultural district (Sec. 60-64(b)(2)); in R-1 they need a Board of Zoning Adjustment special exception after a public hearing (Sec. 60-53(c)(3)). The lot must meet the two-family minimums in Sec. 60-91: 17,000 sq ft in R-1, 10,000 sq ft in R-2 and 4,000 sq ft in R-3.

Ordinance read October 2026

It depends on the district. In R-2, R-3 and M-AG a two-family dwelling is a permitted use, so a conversion needs the zoning permit the zoning inspector must issue when the plans conform (Secs. 60-218, 60-219, within ten days) plus a building permit. In R-1 a two-family dwelling is a special exception the Board of Zoning Adjustment decides 'in its discretion' after a public hearing on the Sec. 60-193 criteria. In A-1 and the other districts there is no route short of a rezoning, and Sec. 60-198(d)(2) bars a variance that 'will permit a use of land, building, or structure which is not permitted in the district'.

Ordinance read October 2026

There is no attached or internal ADU use, but a second unit inside or attached to a house is possible as a two-family dwelling (a building "designed or used exclusively for occupancy by two families"). Two-family dwellings are permitted by right in the R-2, R-3, R-3A and RMH districts and need a conditional use permit in the single-family R-1B, R-1C and R-1D districts, where Sec. 94-304 also requires one frontage on an arterial or collector street. They are not allowed at all in the R-1 rural estate or R-1A districts. The lot must meet the two-family minimums (for example 9,900 sq ft and 65 ft wide in R-2).

Ordinance read October 2026

Where a two-family dwelling is a permitted use (R-2, R-3, R-3A, RMH), the route is administrative: a zoning and use registration permit from the community development director under Sec. 94-50 plus a building permit. In R-1B, R-1C and R-1D it is a conditional use, which requires a published and posted public hearing before the planning commission and then a city council hearing and decision (Secs. 94-221 to 94-227). In R-1 and R-1A no second unit is possible without rezoning.

Ordinance read October 2026

Deadwood has no detached ADU use: its code defines an accessory dwelling unit as a unit 'within a single-family dwelling unit', and the 'Accessory housing' use listed in R1 and R2 follows that definition. A detached second home is possible only as a second principal building in the R2 multi-family district under 17.60.110, which requires street or alley access, a parking easement and separate utilities for each unit, underground utilities, 10 feet between buildings, and the lot area of both units combined (for example 10,000 sq ft for two single-family homes). In R1 no more than one principal building may stand on a lot unless approved as a planned unit development.

Ordinance read October 2026

An accessory dwelling unit inside a single-family home (listed as 'Accessory housing') is a use by right in the R2 multi-family residential district but needs a conditional use permit in the R1 residential district, Deadwood's main single-family zone. Duplexes follow the same split (by right in R2, conditional use in R1). Accessory housing is not listed in the A1, PF or commercial districts.

Ordinance read October 2026

In R2, accessory housing is a use by right handled through a building permit. In R1, it needs a conditional use permit: the Planning and Zoning Commission reviews and reports, and the Board of Adjustment holds a published, posted public hearing and decides. R1 and R2 conditional use permits are temporary, personal to a resident, reviewable annually, limited to one per lot, and expire if unused for six months or discontinued for twelve. Projects affecting a building also need Historic Preservation Commission project approval unless staff finds no effect on historic property, and a certificate of appropriateness for any exterior work in planning unit 4.

Ordinance read October 2026

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).

Ordinance read October 2026

In the unincorporated county, a detached ADU is allowed only as a conditional use in the A-1 Agricultural, RR Rural Residential, R-1 Residential and RC Recreation/Conservation districts, added by Ordinance MC16-183-25 (adopted by the County Commission 4-22-2025). It must sit on the same platted lot as the primary single-family dwelling, with only one ADU per parcel, on permanent frost-protective footings, with proof that the parcel can handle the added wastewater and no separate new access from a township, county or state road. ADUs are not listed in the Commercial or Industrial districts, and none may be placed in a regulated floodway.

Ordinance read October 2026

An attached or internal ADU ('within or attached to an existing single family dwelling') is allowed on the same conditional-use basis as a detached one, in the A-1, RR, R-1 and RC districts only, subject to the same general requirements (one per parcel, wastewater capacity proven before the conditional use permit is approved, no separate access). It must meet all required setbacks and the county building code.

Ordinance read October 2026

Every ADU needs a conditional use permit decided by the Minnehaha County Planning Commission after a public hearing with mailed notice to owners within 500 feet and a posted sign, judged against the Article 19.05(D) criteria; the decision is final unless appealed to the Board of County Commissioners within five working days. After approval, a building permit from the Office of Planning and Zoning is required. The Commission has been granting ADU permits regularly since 2025 (for example CUP 26-10, 26-40 and 26-49 in 2026).

Ordinance read October 2026

There is no attached or internal ADU category either, but a second unit inside or attached to a house is lawful as a two-family dwelling where the district allows one. A 'dwelling unit' is separate living quarters 'with cooking, sleeping, and sanitary facilities' for one family (Sec. 10-2-2), so a basement or addition apartment turns the house into a two-family dwelling. Two-family dwellings are a permitted use in R-3 Medium Density Residential (Sec. 10-5D-2, on a lot of at least 9,000 sq ft and 75 ft wide) and fall within R-4 High Density Residential's permitted 'multi-family dwellings of twenty four (24) units or less' (Sec. 10-5E-2, with a two-unit row of 8,000 sq ft and 75 ft); they are a conditional use in R-2 (Sec. 10-5C-3) and are not listed at all in R-L or R-1, whose only dwelling use is single-family. R-5 lists multi-family dwellings of twelve units or less only as a conditional use.

Ordinance read October 2026

It depends on the district. In R-3 (and R-4) a two-family dwelling is a permitted use, so a conversion or duplex needs only a building permit through Public Works (the city's Planning and Zoning page posts the Building Permit Application). In R-2 a two-family dwelling is a conditional use: the application goes to the Planning Commission for a noticed public hearing (mailed notice to owners within 140 ft and a newspaper notice), and the Board of Adjustment, which under Sec. 3-3-1 is the whole City Council with the mayor as chair, decides it on the Sec. 10-3-3(C) criteria with a two-thirds vote of its full membership. In R-L and R-1 no second unit is available without a rezoning, and a variance cannot add a use (Sec. 10-3-3(B)).

Ordinance read October 2026

In unincorporated Pennington County a detached accessory dwelling is allowed only by Conditional Use Permit in the agriculture and residential zoning districts (AG, RCH, RR, LDR, SR-1, SR-2), decided by the Planning Commission after a public hearing. One accessory dwelling per lot; the lot must be at least 6,500 square feet, and on lots under one acre the unit cannot sit in the front yard. The county defines an accessory dwelling as a detached structure smaller than the single-family primary house, on a permanent foundation, and not a recreational vehicle. Each district's own lot size and septic minimums (for example 20,000 square feet for an on-site wastewater system) still apply.

Ordinance read October 2026

No attached or internal ADU use exists (PCZO 324 is detached-only and the residential districts allow one dwelling per lot); a second unit attached to or inside a house is lawful only as a two-unit dwelling by right in SR-2. The ordinance calls that a multiple-family dwelling (two to four units), and in SR-2 it needs a lot of at least 7,500 square feet for up to two units and must meet §303 (a separate water heater and laundry hookups per unit, 300 square feet of private recreation and leisure area per unit on sites under 20,000 square feet, a screened refuse enclosure on a concrete pad) plus two parking spaces per unit under §310. Outside SR-2, §303(C)(1) allows a multiple-family dwelling only as a Conditional Use with a Planning Commission hearing under §510. Lots on septic still need the §204(M) minimums (20,000 square feet, or 43,560 with a private well).

Ordinance read October 2026

The property must be owner-occupied as determined by the county Department of Equalization (that is, carrying the owner-occupied property-tax classification), unless the main dwelling is occupied as a long-term rental of 28 consecutive days or more. So an owner who lives off-site can still have an ADU if the main house is let long-term, but neither unit can stand empty while the other is short-term rented. The requirement is ongoing and is checked through the Planning Commission's periodic CUP reviews. South Dakota has no state owner-occupancy preemption.

Ordinance read October 2026

Every accessory dwelling needs a Conditional Use Permit under PCZO §510: a published notice at least 10 days ahead, registered or certified mail to owners within 500 feet, a posted sign, and a public hearing at which a favorable majority of the Planning Commission must approve. Appeals of the Planning Commission's decision go under SDCL 11-2-61.1. Approved ADU permits are reviewed afterward for compliance (§324(C)), and the 2026 Planning Commission agendas carry a steady run of ADU CUP and CUP-review items. A building permit under the county Building Code and Construction Ordinance No. 735 is also required. A two-unit dwelling in SR-2 is a use by right, so it needs only the building permit and staff review against §303; elsewhere a two-unit dwelling is itself a §510 conditional use.

Ordinance read October 2026

There is no attached ADU use, but in the Two-Family Residential District a two-family dwelling (duplex) is a principal permitted use and an existing house 'may be converted into a Two-Family dwelling' by right, provided any exterior stairway to a second floor is at the rear. In the One-Family A, B, C and D districts only single-family dwellings (or manufactured homes in C and D) are allowed, so a second unit there needs a rezoning. The Multiple Family district allows multiple dwellings outright.

Ordinance read October 2026

Detached ADUs are allowed as an accessory use (RCMC 17.50.210.A.8) in the LDR-1, MDR, HDR, LDR-2 and General Agricultural districts, but not in the Park Forest district, where an ADU may only be part of the single-family house. A detached ADU also needs a lot of at least 6,500 square feet (smaller lots may have an internal or attached ADU only) and may not sit in the front yard. One ADU per single-family lot.

Ordinance read October 2026

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.

Ordinance read October 2026

Spearfish's zoning chapter (Chapter 156) has no accessory dwelling unit use or definition; a second home on a lot is handled district by district. In R-2 (one- and two-family) a lot may carry a 'maximum of two detached dwellings' by right, and R-3 takes every R-2 use. In R-1 (single-family) a 'second dwelling unit' needs a conditional use permit from the Planning Commission, and in the RLS-1 rural large-lot and AG districts a 'second residence/guest house' needs one too. So a backyard cottage is by right only in R-2 and R-3 and needs a public hearing in the single-family and rural districts.

Ordinance read October 2026

An attached second unit is lawful by right as a 'two-family dwelling on one common lot' in R-2, and in R-3 (which allows every R-2 use). In R-1 the only route is the 'second dwelling unit' conditional use, a term the code never defines and does not limit to detached buildings, so an internal or attached unit there goes through a Planning Commission hearing. The code's 'dwelling unit' definition requires the unit to be served by municipal water and sanitary sewer.

Ordinance read October 2026

In R-2 and R-3 a second detached dwelling or a two-family dwelling is a primary permitted use needing only a building permit. In R-1 (second dwelling unit), RLS-1 and AG (second residence/guest house) it is a conditional use: the Planning Commission decides after a public hearing with mailed notice to owners within 140 feet and a posted sign, by simple majority of members present and voting. Applications go through the city's OpenGov portal.

Ordinance read October 2026

There is no ADU use, and two-family (duplex, over-under) dwellings are not a listed use in any ordinary residential district; they appear only inside a planned unit development of one acre or more, a use on review. The by-right route to a second unit is the 'attached single-family dwelling': in the Low Density and Medium Density Residential districts (and R-3, which allows every R-1 and R-2 use) the code permits attached single-family dwellings for two to seven families, at most two stories, divided by a one-hour separation wall running from the foundation to the underside of the roof. So a side-by-side attached unit built to that standard is permitted, but a basement or upstairs apartment inside an existing house is not a recognized use. The Single-Family Residential/Office Commercial district (GC-3) bars attached single-family dwellings outright.

Ordinance read October 2026

There is no attached or internal ADU use, but a second unit inside or attached to a house is lawful as a duplex. A 'multiple-family dwelling' (which the code says includes a DUPLEX) is 'a building, or portion thereof, containing 2 or more dwelling units' (Sec. 155.008), so a basement or addition apartment with its own kitchen turns the house into a multiple-family dwelling. That use is permitted by right in R-2 (Sec. 155.033(A)) and R-3 (Sec. 155.034(A)) on a lot of at least 7,500 sq ft and 50 ft frontage (75 ft at the building line in R-2). It is not allowed at all in R-1, which permits only single-family detached dwellings plus conditional single-family attached townhomes (Sec. 155.031), or in the R-T townhome district, so most R-1 owners would need a rezoning.

Ordinance read October 2026

There is no ADU, accessory apartment or in-law suite use, and a single-family dwelling is defined as a home occupied by not more than one family. A second unit inside or attached to a house is possible only as a duplex, which is a permitted use in the R-2 and R-2A Single Family Attached districts and the R-3 Multi-Family district (21.1602, 21.1803, 21.2002), on a lot meeting the duplex minimums (R-2: 9,000 sq ft and 80 ft wide; R-3: 6,000 sq ft and 80 ft; R-2A: 6,000 sq ft and 50 ft). The A-1, R-1 and R-1C districts, which cover most single-family neighborhoods, allow single-family dwellings only, so a homeowner there would need a rezoning first.

Ordinance read October 2026

There is no accessory dwelling unit as such, but a second unit in the same building is allowed by right as a two-family dwelling in the R-3 two-family and R-4 multiple-family districts (and in B-1 and B-3, which carry R-4 or R-2 standards). R-3 requires 8,000 sq ft of lot area for a two-family dwelling (6,000 for single-family) and R-4 requires 6,000 sq ft. The R-1 and R-2 single-family districts, which cover most single-family neighborhoods, allow only one-family detached dwellings, so converting a basement or adding an attached unit there takes a rezoning. In B-2 a one- or two-family dwelling is a conditional use.

Ordinance read October 2026