SnowLoadCheck

Brown County, IL Roof Snow Load - 20 psf

Brown County, IL roof snow load, translated

Moderate
20 psf

A typical heated home in Brown County is designed to carry 20 pounds per square foot of snow on its roof, per ASCE 7-22. ASCE 7's low-slope-roof minimum (§7.3.4) raises the governing figure to 20 psf - higher than the 14 psf the ground-load formula alone would give, and the code says use the larger one.

On a roof that means 44 in. of fresh snow, 16 in. once it packs down, or 4 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.

Already snow on the roof in Brown County?

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Brown County at a glance

Where Brown County ranks

#82 of 102 Illinois counties by design load, top 43% of 2,758 nationally - that's Brown County's spot. Illinois counties average 19.3 psf; Brown County runs 0.7 psf higher than that.

FIPS 17009, population 6,307, centered near 39.9621°N 90.7503°W. ASCE 7's underlying ground snow load here is 20 psf before the code's exposure and importance factors bring it to the 20 psf design figure above.

Brown County: average annual snowfall

Brown County sees about 13.5 in. of snow most winters, per the MT STERLING, IL US station's 1991-2020 NOAA normal. See the density guide.

Read this before you use Brown 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. (How this figure is calculated.)