SnowLoadCheck

Big Horn County, MT Roof Snow Load - 20 psf

Big Horn County, MT: your roof's ASCE 7 snow number, in plain English

Moderate
20 psf

Big Horn County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. §7.3.4's low-slope minimum of 20 psf is what actually governs on a flat or low-pitch roof here - higher than the 17.5 psf the base ground-load formula gives.

In depth, not weight: that's roughly 44 inches of fresh, light snow, 16 inches of old, settled snow, or as little as 4 inches of solid ice - snow that heavy is rare here but ice from a freeze-thaw cycle adds up far faster than the depth suggests. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.

Big Horn County at a glance

Big Horn County by the numbers

Nationally that's #1,061 out of 2,758 rated counties, the top 38%; within Montana alone, Big Horn County ranks #10 of 29. That's 1 psf above Montana's own county-average design load of 19 psf.

Big Horn County, FIPS 30003, is home to 12,796 people near 45.4079°N 107.5182°W. Its 25 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.

Big Horn County's snowfall, most winters

43.9 in. a year: that's Big Horn County's NOAA 1991-2020 snowfall normal, measured at YELLOWTAIL DAM, MT US (21.4 mi away). See the density guide.

Before you rely on Big Horn County's number

Treat the Big Horn County figure as a starting point, not a final answer: it assumes standard occupancy, a heated structure and a moderately sheltered site, per ASCE 7-22's own defaults. Exposed terrain, an unheated building or a steeper roof all shift the real number.

For a real application, skip the county number and go straight to the ASCE 7 Hazard Tool - enter your coordinates and it returns a site-specific figure a plan reviewer will recognize. (How this figure is calculated.)