Windows Code Requirements in Wyoming

State with significant severe hail frequency per NOAA SPC storm reports. Insurance restoration contractors should document pre-existing hail damage and recommend impact-resistant materials.

Ground snow loads range from 20 psf in the eastern plains and basins to 30+ psf in central Wyoming. Statewide base zone — see Mountain Snow Load overlay for western mountain counties with loads of 40-80+ psf. Extreme wind-driven snow drifting is a major concern statewide due to Wyoming's high wind exposure.

Western and mountain Wyoming experiences extreme cold and heavy snow loads. Design temperatures range from -20F (Cheyenne, Casper) to -40F (Pinedale, Jackson). Ground snow loads range from 30 psf (lower elevation plains) to 100+ psf (mountain valleys like Jackson Hole and Star Valley). Much of western Wyoming is designated as "Case Study" in ASCE 7, requiring site-specific snow load analysis. Frost depths can exceed 48 inches in Zone 7 areas. Wind-blown snow drifting is a major concern statewide.

Ice barrier underlayment is REQUIRED statewide on all roof eaves per IRC R905.1.2. Mean January temperature is well below 25°F across the entire state. Wyoming's combination of heavy snow, extreme cold (design temps -10°F to -30°F), and high winds creates severe ice dam and wind-driven rain/snow intrusion conditions.

Western Wyoming has significant seismic activity. Teton County (Jackson area) is Seismic Design Category D due to the Teton Fault, one of the most active faults in the Intermountain West. Park County (Yellowstone area) experiences frequent earthquakes associated with the Yellowstone Caldera volcanic system. Lincoln and Sublette counties also have elevated seismic risk. The 1959 Hebgen Lake earthquake (M7.3) near Yellowstone caused significant damage. SDC ranges from B (eastern Wyoming) to D (Teton County).

Areas designated as Zone A, AE, or AH on FEMA Flood Insurance Rate Maps. Wyoming has significant riverine flood risk along the North Platte River (Casper, Douglas), Green River (Green River, Rock Springs), Snake River (Jackson), Wind River (Riverton, Lander), Bighorn River (Thermopolis, Worland), and other major waterways. Spring snowmelt flooding is the primary flood hazard. Flash flooding occurs in mountain canyons and dry creek beds.

Wyoming has extensive WUI areas where residential development meets wildland vegetation. High-risk areas include: Teton County (Jackson Hole valley and surrounding mountains), Park County (Cody area and Yellowstone gateway), Sheridan County (Bighorn Mountain foothills), Albany County (Laramie Range), Sublette County (Wind River Range foothills), and Lincoln County (Star Valley). Grassland fires on the eastern plains also pose risk. Wyoming's dry climate, high winds, and extensive rangeland create significant wildfire hazard.