South Dakota is one of the few states with no statewide residential building code, so whether a rule applies to your roof depends on your city or county, not any state agency. The design ground snow load at Sioux Falls, the reference point used for permits across the region, comes in at 40 psf, and that’s the figure your truss drawings get built around. Check with your local building department before you order materials, because they decide which code edition applies and whether it’s been amended locally.
What is the ground snow load in South Dakota?
The design ground snow load at Sioux Falls is 40 psf, under ASCE 7-16, the edition of the ASCE 7 standard that IRC/IBC 2021 makes applicable in most states. That’s the number a permit application, a plan review and a set of truss drawings all reference. It is not, on its own, a measurement of what actually sits on a rafter.
Ground load vs. roof load
Ground snow load is the weight the snow puts on open ground, not on a pitched roof above a heated house. The code applies exposure, thermal and slope factors before that number reaches a truss. For an ordinary heated sloped roof, the result at Sioux Falls lands near 28 psf, roughly 0.7 of the ground figure, and a steeper roof brings that lower still. This is the single most common mix-up on the subject: quoting the ground number as if it were the load on the shingles overstates the uniform design load and understates what matters more, which is drift.
The coming edition: ASCE 7-22
ASCE 7-22, which some jurisdictions are beginning to adopt, maps the same Sioux Falls point at 79 psf. That is not more snow and not a sign that existing roofs are undersized. The two editions use different bases: ASCE 7-16 is a nominal value paired with a 1.6 load factor, while ASCE 7-22 is a strength-level value paired with a 1.0 load factor. The 79 psf figure is what shows up once code adoption catches up, not a new hazard that appeared overnight. Sioux Falls sits in the state’s southeast corner, and elevation rises considerably toward the Black Hills in the west, where this figure does not apply. A licensed engineer or your local building department is the right source for a site that differs enough to matter.
How much snow can a roof hold in South Dakota?
There’s no single number, and that’s the honest starting point. How much a given roof can hold depends on its slope, its exposure to wind, and what the snow itself has become by the time it’s sitting there.
Ground load to roof load, and where drift adds to it
Working from the Sioux Falls ground figure of 40 psf, the code’s roughly 0.7 conversion puts an ordinary heated sloped roof near 28 psf under uniform snow. That uniform number is rarely where a roof actually fails. Drift is. Snow piles unevenly against a parapet wall, below a dormer, or on a lower roof section next to a taller one, and in those spots the local load can run well above the open-field figure the ground map gives. The same drift mechanics play out across very different terrain, and it’s worth seeing how they show up in a place with sharper elevation changes, like Idaho, where mountain drift patterns make the local variation even more pronounced than on the plains.
Depth to weight, and the warning signs
A foot of snow is not a fixed weight. Fresh, light, dry snow runs roughly 5 to 7 pounds per square foot per foot of depth. Once that snow settles, or falls wet, the same depth can weigh two to three times as much. An ice layer, formed when meltwater refreezes within the snowpack, adds more still. That’s why a foot of snow sitting on a roof in January is not equivalent to a foot that falls in a wet March storm, even though both measure the same on a yardstick.
Watch for the practical signs that a roof is being asked to hold more than it should:
- Interior doors that suddenly stick or won’t latch
- New cracks in ceiling drywall, especially running along a ridge or beam line
- A visibly sagging ridge line or a roof surface that looks wavy from the ground
- Popping or cracking sounds from the attic or roof framing
- A garage door or overhead door that bows or resists opening
If you see any of these, raking snow from the ground with a long-handled roof rake is the safe response. Climbing onto a snow-loaded roof to shovel it is not, both because the roof may already be near its limit and because the surface is far more slippery than it looks.
What wind speed must a roof withstand in South Dakota?
The basic design wind speed at Sioux Falls is 112 mph under ASCE 7-16, for Risk Category II, the classification that covers an ordinary house. That is a 3-second gust measured at 33 feet in open, Exposure C terrain, not a sustained wind and not what a weather forecast means when it announces a wind speed. Comparing it directly to a hurricane’s headline number invites the wrong conclusion, since the two are measured on different bases.
What the number means
This figure drives the wind rating a shingle product must carry, the nailing pattern used to fasten it, the fastening schedule for the roof sheathing beneath it, and the uplift connectors, straps or clips, that tie the roof framing down to the walls. Edges, rakes and ridges fail first in a wind event, because that’s where uplift pressure concentrates hardest. ASCE 7-22 maps this same Sioux Falls point at 112 mph as well, so the two editions agree here, unlike the snow load figure where the bases diverge.
Wind-borne debris: not a factor here
The code’s wind-borne debris provisions, which require impact-rated glazing or approved shutters on windows and doors, apply in hurricane-prone regions along the Atlantic and Gulf coasts. South Dakota’s inland location does not carry that designation, so this obligation does not apply here. That’s a real difference from a coastal state. In a place like Massachusetts, the wind-borne debris line along the shoreline adds a real cost that an inland South Dakota project simply doesn’t face. As with the snow figure, treat 112 mph as the Sioux Falls reference point rather than a single number for the whole state, since a building official elsewhere may work from a different point on the map.
Does South Dakota require an ice barrier under the shingles?
An ice barrier is a self-adhering membrane run along the eaves and up past the interior face of the exterior wall line. Its job is not to stop snow. It’s to stop meltwater that backs up behind an ice dam from soaking into the roof deck and finding its way into the house below.
Sioux Falls’ mean daily minimum in the coldest month is 8.5°F, under NOAA’s 1991-2020 climate normals, and the region also carries a real roof snow load, the roughly 28 psf figure discussed above. That combination, cold enough for repeated freeze-thaw cycling and enough sustained snowpack to supply the meltwater, makes ice damming a genuine risk here rather than a hypothetical one.
What actually causes an ice dam
Heat escaping from the living space into the attic melts the underside of the snowpack even while the air outside stays well below freezing. That meltwater runs down the roof deck until it reaches the cold overhang beyond the heated wall line, where it refreezes into a dam. Water backs up behind that dam and finds its way under the shingles. The membrane protects the deck from that intrusion. It does nothing to stop the dam from forming in the first place. Only air sealing the attic floor and bringing insulation up to full depth stops the underlying cause. A homeowner who installs the membrane and calls the problem solved has bought protection against the symptom, not the mechanism.
The code that applies, and who enforces it
South Dakota has no state agency that administers a residential code. State law provides only that a municipality choosing to regulate homes must use the 2024 International Residential Code and may not impose requirements stricter than it. The state’s commercial code expressly excludes residential structures, and adoption is decided city by city or county by county, with no statewide mandate either way. The 2024 IRC’s model text includes a self-adhering ice barrier requirement in areas with a history of ice forming along the eaves, but whether that clause governs your roof depends entirely on whether your city or county has adopted that edition. Your local building department is the source for that answer, not a state office.
What roofing material suits South Dakota best?
The combination that matters here is Sioux Falls’ 40 psf ground snow load, its 112 mph design wind speed, and a climate zone spread that splits the state’s 66 counties between IECC zone 6A, covering 48 counties, and zone 5A, covering 18. None of those figures alone tells you which material to choose. Together they set the trade-offs.
Matching material to the load
| Material | Snow behavior | Wind consideration | Added structural weight |
|---|---|---|---|
| Architectural asphalt shingles | Holds snow on the surface rather than shedding it | Wind rating must match the design gust speed for the roof’s location | Low, minimal addition to the snow load itself |
| Standing-seam metal | Sheds snow readily off a smooth surface, often in a sudden slide | Panel clips and seam fastening govern uplift resistance | Low, similar to shingles |
| Slate or concrete tile | Holds snow similarly to shingles, adds its own dead load underneath | Heavier assembly generally resists uplift well when properly fastened | Substantial, adds to the snow load the structure carries |
Metal’s smooth surface sheds snow well, but that’s exactly why where it lands matters. A slide that releases over a doorway, a walkway, or a parked vehicle is a design decision the roof layout has to account for, not an accident to discover the hard way. Slate and concrete tile add their own weight directly on top of whatever the structure already carries from snow, which matters more in a place with a nontrivial ground snow figure than in a milder climate. Fastening and underlayment matter more than the material label wherever wind governs the design: a shingle rated for high wind but nailed to a lower standard performs to that lower standard, full stop. If you haven’t settled on a roofing material yet, matching the fastening schedule to the design wind speed is the step that actually protects the house, more than the brand on the bundle.
Climate zone also shapes the attic insulation and venting that keep the underside of the roof deck cold enough to avoid melt-refreeze cycling in the first place. The 2021 IECC’s county table splits South Dakota between zones 6A and 5A rather than treating the state as a single climate, which means the insulation depth that stops an ice dam from forming in one county isn’t automatically the right number two counties over.