SnowLoadCheck

Gallatin County, IL Roof Snow Load - 15 psf

Gallatin County, IL roof snow load, translated

Moderate
15 psf

A typical heated home in Gallatin County is designed to carry 15 pounds per square foot of snow on its roof, per ASCE 7-22. Flat and low-pitch roofs in Gallatin County are actually governed by ASCE 7's §7.3.4 minimum of 15 psf, not the 10.5 psf the ground-load formula alone would produce.

On a roof that means 33 in. of fresh snow, 12 in. once it packs down, or 3 in. of solid ice - three very different piles for the same load. 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.

Gallatin County in numbers

Where Gallatin County ranks

#99 of 102 Illinois counties by design load, top 58% of 2,758 nationally - that's Gallatin County's spot. That's 4.3 psf below Illinois's own county-average design load of 19.3 psf.

FIPS 17059, population 4,690, centered near 37.7687°N 88.228°W. ASCE 7's underlying ground snow load here is 15 psf before the code's exposure and importance factors bring it to the 15 psf design figure above.

Gallatin County: average annual snowfall

Gallatin County sees about 13.3 in. of snow most winters, per the MCLEANSBORO, IL US station's 1991-2020 NOAA normal. That station is far enough away (27.7 mi) that local snowfall - especially at a different elevation or near a lake - can run noticeably higher or lower than this figure. See the density guide.

Read this before you use Gallatin County's figure

The figure above assumes the case ASCE 7-22 treats as typical: a heated, ordinary-occupancy home on a partially exposed site. Change any of those - exposure, heating, roof pitch, occupancy category - and the real design number moves.

A building permit needs the number at your exact address, not the county average - the free ASCE 7 Hazard Tool returns that from your coordinates in about a minute and produces a PDF a plan reviewer will accept. See the methodology guide.