Building permits, zoning and land rules in Custer County, South Dakota

Yes, for most structures in unincorporated Custer County. A county building permit is required for every structure over 160 square feet, including a new or used mobile or modular home¹. A non-living structure with no water and no sewer that is 160 square feet or smaller uses the county's no-permit form instead¹. Inside residential subdivisions regulated by Custer County Ordinance #2, building and grading permits are required for new residential and accessory structures⁵. Custer County publishes a separate fee schedule, so verify the current charge before submitting payment². Custer County does not inspect footings, foundations, framing or the finished structure, but it does require final inspections of access approaches and individual wastewater systems; South Dakota handles plumbing and electrical inspections¹.

The Custer County Planning and Economic Department is the permit office for building, approach, wastewater, subdivision and floodplain matters. Its office is at 420 Mount Rushmore Road, Custer, SD 57730-1934, and its phone number is (605) 673-8174². The department publishes downloadable applications and an online application portal². Before issuing permits, the county requires proof of ownership for newly purchased property and verification of recorded access; permits go only to the owner or a designated agent^2,5. Submit a complete application, then pay the required fees when the permit is issued; starting regulated work first triggers a late application fee². Because there is no county building code, the county permit is principally a land-development process, not a full structural plan-review and inspection program^1,2.

Custer County has no county zoning districts and has not adopted a county building code². On unincorporated land, that means there is no county zoning minimum dwelling size, general minimum lot size, zoning setback, lot-coverage limit or building-height limit². Subdivision rules are the important exception: lots in residential subdivisions must contain at least 1 acre, and structures must sit at least 30 feet from a public-road right-of-way and 15 feet from other property lines⁵. Outside municipal boundaries, all subdivision of land is reviewed by Access Map Review or Plat Review⁵. Wastewater, driveway and floodplain requirements still apply, and incorporated municipalities may have their own building permits and zoning, which this county rule does not cover².

Custer County requires a wastewater permit when a septic system is installed, constructed, modified, extended, replaced or relocated². The Custer County Planning Office approves the permit, installation may begin only after approval, and the installer must be certified by South Dakota². Where applicable, a percolation test by a state-certified wastewater installer is required before issuance². The Planning Department must inspect every wastewater installation before any part of the system is covered¹. Site conditions deserve early attention because only 14.8% of county soils lack severe limits for a conventional drain field⁶. Alternative off-grid sanitation is governed separately: South Dakota permits specified unconventional systems where water or electrical service is unavailable, but systems other than vault privies require state approval before installation⁷.

Unincorporated Custer County has no zoning-based minimum dwelling size, but the county materials do not establish a general rule allowing full-time RV occupancy or tiny-home occupancy². In mapped flood-hazard zones, an RV must be present for fewer than 180 consecutive days, remain fully licensed and ready for highway use, or meet the applicable development-permit, elevation and anchoring requirements³. Ask the Custer County Planning and Economic Department about occupancy on the specific parcel². A tiny home or similar structure over 160 square feet needs a county building permit; the small-structure form applies only to a non-living structure with no water and no sewer at or below that size¹. Any septic work still requires county approval and a state-certified installer².

1. Confirm ownership and recorded access, because Custer County will not issue permits until access is verified^2,5.

1. Apply for the approach permit before driveway construction; the approach must be finalized before the county issues a 911 address^2,5.

1. Check whether the site is in a special flood-hazard area and obtain the floodplain development permit before construction or fill work there³.

1. Arrange the percolation work with a South Dakota-certified wastewater installer, submit the wastewater application, and wait for approval before installation².

1. Submit the complete building application and pay the applicable charges when the permit is issued².

1. Obtain applicable state plumbing and electrical permits and inspections, then keep the wastewater system uncovered for county inspection and arrange the final approach inspection^1,8.

Start with legal and physical access: Custer County requires an approved approach before building permits, wastewater permits or an emergency-services address are issued⁵. If the driveway connects to a state highway, obtain the state access permit before construction⁹. Test septic feasibility early because only 14.8% of county soils lack severe limits for a conventional drain field⁶. A water-right permit is required only for certain proposed water uses and, when required, must be approved before drilling; a person drilling for someone else must be state licensed¹⁰. Check the flood map because construction, structures, fill and other development in a special flood-hazard area require a county development permit before work begins³. High-density subdivisions within 0.5 mile of public water and sewer generally must connect unless municipal restrictions or topography prevent it⁵.