South Dakota

Statewide summary — confirm with your building department before designing

No value on this row was changed by this audit. Seismic design category A is confirmed and is the cleanest reading in this group: the USGS ASCE 7-16 design maps service, at Site Class D and Risk Category II under the IRC single parameter method, returns short period design accelerations of 0.097 g at Sioux Falls, 0.148 g at Rapid City and 0.117 g at Pierre, all comfortably inside category A. Termite risk of slight corresponds to the IRC slight to moderate band, which covers the southern and eastern parts of the state where most South Dakotans live; the northern counties fall in the none to slight band. The remaining values could not be checked against any adopted South Dakota table and should be treated as unverified. Wind speed of 105 mph sits between the ASCE 7-16 contours on the northern plains and is reported rather than adjusted, because the project has not settled whether to round up to the next contour. Frost depth of 48 inches is deeper than the 42 inches commonly used around Sioux Falls and so over builds rather than under builds. Ground snow load of 35 psf is a reasonable eastern South Dakota figure but says nothing useful about the Black Hills, where ground snow loads several times that are ordinary at elevation. Winter design temperature derives from ASHRAE data that no South Dakota jurisdiction was found to have adopted into its own table, so it remains unestablished. None of these are state level quantities. IRC Table R301.2 is filled in by the local jurisdiction, and the number that governs your lot is the one your building official has adopted, not the one on this row. Source: https://earthquake.usgs.gov/ws/building-codes/ Snow load audit, August 2026. South Dakota has no statewide residential building code, so there is no state ground snow load range and both range columns stay null. SDCL 11-10-12, as amended by SL 2026 ch 59, is permissive in terms: the governing body of a municipality "may enact requirements ... by adopting the 2024 edition of the International Residential Code," may amend any provision of it, and may not impose requirements more stringent than that code. SDCL 11-10-5 works the same way for non-residential ordinances, requiring any such ordinance to comply with the 2024 IBC, and SDCL 11-10-6 makes the 2024 IBC the default design standard for buildings begun after July 1, 2026 in a jurisdiction with no ordinance, while expressly excluding residential structures, mobile and manufactured homes, and farmsteads. Nothing in chapter 11-10 contains a snow load, a wind speed, a seismic category or a frost depth. One official South Dakota document does name ground snow loads, and it is worth recording precisely because it is the only one. The Model Building Code Workgroup convened by the Board of Technical Professions under SDCL 11-10-13 published its 2025 Building Codes Review summary report in October 2025. In its review of IRC Figure R301.2(3), allowable stress design ground snow loads, the workgroup writes that the figure was revised to follow ASCE 7-22, that the approach is now address specific rather than a broad map, and gives as its worked example that Sioux Falls increases from 40 to 55 pounds while Pierre stays at 40. These are ground snow loads, not roof snow loads, and they are allowable-stress-design values, which is the quantity IRC Table R301.2 asks for. They are two point values for two cities, not a statewide minimum and maximum, and the Black Hills are not addressed anywhere in the report, so they cannot be used to populate the range columns. Corrected ground_snow_load_psf from 35 to 40 because no South Dakota source places any location at 35 psf, while the state workgroup report puts Pierre at 40 psf under both the old and the new mapping and puts Sioux Falls at 40 psf under the mapping in force before the 2024 IRC. Read the corrected value as an eastern and central South Dakota figure only. Under the 2024 IRC that SDCL 11-10-12 now references, the same state report puts Sioux Falls at 55 psf, so 40 understates the state largest city under the current edition; and ground snow loads in the Black Hills are far higher and are quantified by no South Dakota authority. The other three values were not changed. Seismic design category A was re-confirmed against the USGS ASCE 7-16 design maps service at Site Class D and Risk Category II, returning short-period design accelerations of about 0.097 g at Sioux Falls and 0.148 g at Rapid City, both category A on the short-period parameter and on the one-second parameter.