Clark County, IL Roof Snow Load - 20 psf
How much snow is too much for a roof in Clark County, IL?
20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Clark County to carry. Flat and low-pitch roofs in Clark County are actually governed by ASCE 7's §7.3.4 minimum of 20 psf, not the 14 psf the ground-load formula alone would produce.
Picture it, not just weigh it: 44 in. if it's fresh powder, 16 in. once it settles, or a mere 4 in. if it's ice. 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.
Clark County in numbers
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#1,025 of 2,758
- Illinois rank#66 of 102
- Population15,076
- Annual snowfall, NOAA normal11.9 in.
- FIPS17023
How Clark County compares
20 psf ranks #1,025 of 2,758 US counties with a mapped snow load (top 37%) - and #66 of 102 in Illinois. 19.3 psf is Illinois's typical county figure - Clark County beats it by 0.7 psf.
Population 15,076 (FIPS 17023), roughly 39.3323°N 87.7917°W. The 20 psf ground snow load ASCE 7-22 maps here becomes 20 psf once the code's own design factors are applied.
Typical snowfall in Clark County, IL
NOAA's 30-year normal for Clark County: 11.9 in. of snow a year, from the CASEY, IL US station. (fresh vs. packed vs. ice explains why.)
What this Clark County figure assumes
This is a county-level reference figure for a typical heated home built to Risk Category II (ordinary residential), on a partially exposed lot - the assumptions ASCE 7-22 itself treats as the default case. A steeper roof, a fully exposed hilltop lot, an unheated structure, or a higher risk category all change the actual number.
Clark County's permit office wants an address-specific figure, not this county average - the ASCE 7 Hazard Tool is free, takes under a minute, and outputs a PDF most reviewers accept. See the methodology guide.