SnowLoadCheck

Rock Island County, IL Roof Snow Load - 20 psf

How much snow is too much for a roof in Rock Island County, IL?

Moderate
20 psf

20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Rock Island County to carry. §7.3.4's low-slope minimum of 20 psf is what actually governs on a flat or low-pitch roof here - higher than the 14 psf the base ground-load formula gives.

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. 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.

Already snow on the roof in Rock Island County?

in. of

Rock Island County in numbers

How Rock Island County compares

20 psf ranks #622 of 2,758 US counties with a mapped snow load (top 23%) - and #15 of 102 in Illinois. 19.3 psf is Illinois's typical county figure - Rock Island County beats it by 0.7 psf.

Population 142,731 (FIPS 17161), roughly 41.4684°N 90.5721°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 Rock Island County, IL

NOAA's 30-year normal for Rock Island County: 36.1 in. of snow a year, from the MOLINE QUAD CITY INTL AP, IL US station. (fresh vs. packed vs. ice explains why.)

What this Rock Island 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.

Rock Island 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.