Kansas City’s design ground snow load is 20 pounds per square foot, and that single figure shapes the truss drawings, wind bracing, and ice barrier decisions on a permit anywhere near that city. What actually reaches a rafter is a smaller number: the code trims the ground figure down for slope, exposure, and heat loss before a builder ever cuts a truss. Start any roofing project by asking the local building department which value they use for your address, since it shifts with elevation and location across the state.
What is the ground snow load in Missouri?
Near Kansas City, the design ground snow load is 20 pounds per square foot (psf) under ASCE 7-16, the edition that IRC/IBC 2021 makes applicable in most states. That figure comes from the American Society of Civil Engineers’ snow load maps, and it is the one a permit application, a plan review, and a set of truss drawings all rely on. It is not, however, the load an actual roof carries.
Ground load versus roof load
Ground snow load measures what piles up on flat, open ground near a site’s elevation. A roof never sees that full number. The code applies exposure, thermal, and slope factors before converting it into a roof snow load, and for an ordinary heated house roof with a normal pitch near Kansas City, that works out to roughly 14 psf of roof snow load, the figure a truss designer actually uses on the drawings.
A newer edition, ASCE 7-22, maps the same point at 30 psf. That is not three years of heavier winters landing on Kansas City. The two numbers sit on different bases: 7-16’s 20 psf is a nominal value used with a 1.6 load factor, while 7-22’s 30 psf is a strength-level value used with a 1.0 load factor. A handful of jurisdictions are beginning to adopt 7-22, but the 7-16 figure is what’s in force on the permit most homeowners in the area are filing today.
Elevation changes this figure by the thousand feet across Missouri’s 114 counties, so the map value for Kansas City says nothing about a bluff-top lot two counties over, or a river-bottom lot two counties the other way. If you don’t already know your county’s design value, ask the local building department. They will have the figure their jurisdiction actually applies at plan review, and it may not match the Kansas City number at all.
How much snow can a roof hold in Missouri?
There’s no single inches-of-snow answer to this, because the same depth of snow can weigh two or three times as much depending on what it has turned into.
Start from the 20 psf ground snow load ASCE maps for Kansas City. For an ordinary heated, moderately pitched roof, the code converts that down to roughly 14 psf of roof snow load, the value that governs a typical gable or hip roof over living space. A steeper roof carries less, because snow slides off before it builds to full depth.
Drift is where the number runs the other way. Snow blown against a parapet, piled below a dormer, or dropped into a valley where two roof planes meet can load a small area at several times the open-field figure. Behind a taller adjoining wall or a rooftop unit, drift depth can pile up well past what the flat-field ground value suggests. That’s why roof failures so often start at a valley or a low roof tucked against a taller wall, not out in the open field of a simple gable.
Why depth alone doesn’t tell you the load
Fresh, light snow runs roughly 5 to 7 pounds per square foot for every foot of depth. Once it settles, or once rain or a freeze-thaw cycle wets it, that same foot of snow can weigh two to three times as much. An ice layer on top adds more weight still, in a much thinner layer. A foot of wet March snow sitting on an already-damp roof can outweigh two feet of dry January powder.
Watch for these signs that a roof is carrying more than it should:
- Interior doors that suddenly stick or won’t latch
- New cracks in ceiling drywall or at wall-ceiling joints
- A ridge line that looks like it’s sagging when viewed from the street
- Popping or cracking sounds from the attic under load
Any of these calls for getting snow off the roof, not waiting to see if it gets worse. A snow rake used from the ground, pulling snow off the lower few feet of the roof, is the safe way to relieve that load. Climbing onto a loaded roof to shovel it is how people get hurt, and it adds a concentrated live load exactly where the built-up snow has already stressed the structure. This is a structural question a magazine page can’t settle for a roof it has never seen. A building department or a licensed structural engineer can look at the actual framing and span and say whether it’s carrying what it should.
What wind speed must a roof withstand in Missouri?
Kansas City’s basic design wind speed is 110 mph under ASCE 7-16, for Risk Category II, the category covering ordinary houses. That’s a 3-second gust measured at 33 feet in open, Exposure C terrain, not a sustained wind and not what a weather forecast reports as wind speed. A steady 110 mph wind would be extraordinary. A 3-second gust that briefly reaches that speed during a storm is what the code is actually built around.
Kansas City isn’t flagged as a wind-borne debris region the way Gulf and Atlantic coast counties are, so the code’s impact-rated glazing and shutter requirements that apply along those coastlines don’t apply here. Coastal states set a much higher design speed and add that debris requirement on top of it, a difference our guide to Maryland’s roof snow load and wind rules lays out for the Chesapeake shoreline.
What the wind speed number actually governs
The 110 mph figure feeds shingle wind ratings, nailing patterns, sheathing fastening schedules, and the uplift connections tying 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. A roof that performs everywhere else can still lose shingles or decking right along those lines if the fastening there falls short of what the design speed calls for.
ASCE 7-22 maps the same Kansas City point at 110 mph too, so there’s no discrepancy between editions here to flag. Whichever edition a local jurisdiction has adopted, the number governing a Kansas City-area permit lands in the same place.
Does Missouri require an ice barrier under the shingles?
An ice barrier is a self-adhering, waterproof membrane installed along the eaves, run up the roof deck past the interior line of the exterior wall below. It isn’t there to stop snow from accumulating. It’s there to stop water from an ice dam backing up under the shingles and reaching the deck, insulation, and ceiling below.
What actually causes an ice dam
Kansas City’s mean daily minimum for the coldest month runs 19.5°F, per NOAA’s 1991-2020 climate normals. That’s cold enough, combined with heat escaping from a warm attic below and snow sitting on the roof above, to set up the classic freeze-thaw cycle: heat melts snow on the upper roof, the meltwater runs down to the cold eave overhang, and it refreezes there, building a dam that backs water up under the shingles.
The membrane only protects the deck once water is already backing up behind that dam. It doesn’t stop the dam from forming in the first place. Air sealing the attic floor and adding insulation so the underside of the roof deck stays uniformly cold is what actually prevents the melt-refreeze cycle. A roof with a flawless ice barrier and a leaky, under-insulated attic below will still grow an ice dam most winters. It just won’t leak into the ceiling while it does.
Missouri has no statewide residential building code. No state agency administers one, and many unincorporated areas across the state’s 114 counties have adopted none at all. Whether a given city or county’s adopted code requires an ice barrier, and under what conditions, is decided locally, not by any state office. Bills to create a statewide building code were introduced in 2024 and 2025 and did not pass. Virginia takes the opposite approach with one uniform code statewide, a difference our guide to Virginia’s roof snow load and wind rules covers in full. Before you plan a roofing job in Missouri, check with your city or county building department for the code they’ve adopted and whether it carries an ice barrier requirement for your address.
What roofing material suits Missouri best?
Near Kansas City, the combination that matters is a 20 psf ground snow load, a 110 mph design wind speed, and an IECC climate zone that splits across the state: zone 4A across 87 counties, zone 5A across 26, and zone 3A across 2, under the 2021 IECC. None of that picks one best material outright, but it does rule some choices in and some out for different reasons.
Weighing material against the loads
| Material | Wind performance | Snow behavior | Added dead weight |
|---|---|---|---|
| Architectural asphalt shingles | Wind-rated by class, performance depends on the nailing pattern matching the rating | Holds snow in place rather than shedding it | Lightest of the three |
| Standing-seam metal | Depends on panel gauge, clip spacing, and fastening into the deck | Sheds snow quickly once it warms, often in one slide | Light, similar to or less than shingles |
| Slate or concrete tile | Heavy individual units resist uplift once properly fastened | Holds snow much like shingles do | Substantially heavier, adds directly to the load the framing carries |
Fastening and underlayment matter more than the material itself where wind is doing the governing. A shingle rated for a high wind speed performs only to whatever standard it’s actually nailed to. A nailing pattern one step below the rating turns a good product into a roof that fails at its edges, rakes, and ridge, the three places uplift concentrates first, regardless of what the shingle wrapper promised.
A metal roof’s tendency to shed snow in a single slide is worth planning for, not just admiring. Where that snow lands matters. Over a walkway, a deck, a gas meter, or a driveway is a decision made at the eave and rake detailing during design, not something to discover the first heavy snow after moving in.
Slate and concrete tile add their own dead weight on top of whatever the roof already carries from snow. That weight has to be accounted for in the same structural calculation that sets the roof snow load in the first place, so it’s worth involving a licensed engineer or the building department before committing to a heavy roofing material on an older structure that wasn’t originally framed for it.