SnowLoadCheck

Will County, IL Roof Snow Load - 20 psf

Will County, IL: your roof's ASCE 7 snow number, in plain English

Moderate
20 psf

Will 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 17.5 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. This is a meaningful design load - most modern-code homes handle it fine, though an addition, a carport or a flat-roofed section can be a weak spot.

Will County at a glance

Will County by the numbers

Nationally that's #524 out of 2,758 rated counties, the top 19%; within Illinois alone, Will County ranks #4 of 102. Illinois counties average 19.3 psf; Will County runs 0.7 psf higher than that.

Will County, FIPS 17197, is home to 708,583 people near 41.4485°N 87.9785°W. Its 25 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.

Will County's snowfall, most winters

16.9 in. a year: that's Will County's NOAA 1991-2020 snowfall normal, measured at JOLIET BRANDON RD DAM, IL US (7.5 mi away). See the density guide.

Before you rely on Will County's number

Treat the Will 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.)