SnowLoadCheck

Piatt County, IL Roof Snow Load - 20 psf

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

Moderate
20 psf

Piatt County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. 14 psf is what the ground-load formula alone gives; Piatt County's 20 psf low-slope minimum (§7.3.4) beats it, so that figure is the one that governs on flat and low-pitch roofs.

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.

Piatt County in numbers

Piatt County by the numbers

Nationally that's #997 out of 2,758 rated counties, the top 36%; within Illinois alone, Piatt County ranks #57 of 102. Illinois counties average 19.3 psf; Piatt County runs 0.7 psf higher than that.

Piatt County, FIPS 17147, is home to 16,628 people near 40.009°N 88.5924°W. Its 20 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.

Piatt County's snowfall, most winters

18.1 in. a year: that's Piatt County's NOAA 1991-2020 snowfall normal, measured at MONTICELLO (RIVER), IL US (2.1 mi away). See the density guide.

Before you rely on Piatt County's number

Treat the Piatt 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.