SnowLoadCheck

Lee County, IL Roof Snow Load - 20 psf

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

Moderate
20 psf

Lee County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. The physics-based figure alone would be 17.5 psf, but ASCE 7's own low-slope minimum (§7.3.4) sets a floor of 20 psf for flat and low-pitch roofs here, which is the number that actually governs.

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.

Snow on Lee County's roofs right now?

in. of

Lee County at a glance

Lee County by the numbers

Nationally that's #833 out of 2,758 rated counties, the top 30%; within Illinois alone, Lee County ranks #39 of 102. 19.3 psf is Illinois's typical county figure - Lee County beats it by 0.7 psf.

Lee County, FIPS 17103, is home to 33,544 people near 41.7474°N 89.2994°W. Its 25 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.

Lee County's snowfall, most winters

28.9 in. a year: that's Lee County's NOAA 1991-2020 snowfall normal, measured at AMBOY, IL US (2.6 mi away). See the density guide.

Before you rely on Lee County's number

Treat the Lee 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.)