Jersey County, IL Roof Snow Load - 20 psf
Jersey County, IL: your roof's ASCE 7 snow number, in plain English
Jersey County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. ASCE 7's low-slope-roof minimum (§7.3.4) raises the governing figure to 20 psf - higher than the 14 psf the ground-load formula alone would give, and the code says use the larger one.
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. Modern-code homes carry a load like this without issue; an older addition, a carport, or any flat-roofed section is where it is worth checking first.
Jersey County in numbers
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#945 of 2,758
- Illinois rank#51 of 102
- Population21,150
- Annual snowfall, NOAA normal12.5 in.
- FIPS17083
Jersey County by the numbers
Nationally that's #945 out of 2,758 rated counties, the top 34%; within Illinois alone, Jersey County ranks #51 of 102. That's 0.7 psf above Illinois's own county-average design load of 19.3 psf.
Jersey County, FIPS 17083, is home to 21,150 people near 39.0802°N 90.3614°W. Its 20 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.
Jersey County's snowfall, most winters
12.5 in. a year: that's Jersey County's NOAA 1991-2020 snowfall normal, measured at JERSEYVILLE 2 SW, IL US (1.8 mi away). See the density guide.
Before you rely on Jersey County's number
Treat the Jersey 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. Details: the calculation guide.