SnowLoadCheck

Union County, IL Roof Snow Load - 15 psf

What ASCE 7 says about snow load in Union County

Moderate
15 psf

That's Union County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from. ASCE 7's low-slope-roof minimum (§7.3.4) raises the governing figure to 15 psf - higher than the 10.5 psf the ground-load formula alone would give, and the code says use the larger one.

Converted to something you can actually eyeball on a roof: about 33 in. of fresh powder, 12 in. once it settles and packs down, or just 3 in. if it's turned to 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.

Snow on Union County's roofs right now?

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Union County, IL: quick facts

Where Union County's figure sits nationally

Out of 2,758 rated US counties, Union County sits at #1,492, the top 54% nationally - #93 of 102 within Illinois. That's 4.3 psf below Illinois's own county-average design load of 19.3 psf.

Near 37.4857°N 89.2446°W, FIPS 17181: Union County counts 16,886 residents and a 15 psf map value, which the code's own factors turn into 15 psf.

How much it actually snows in Union County

Most winters bring Union County roughly 10.4 in. of snow - NOAA's normal at ANNA 2 NNE, IL US, 0.6 mi off. (fresh vs. packed vs. ice explains why.)

Read this before you rely on it

Union County's number above is ASCE 7-22's default case, not a custom calculation: ordinary residential occupancy, heated, sited on ground that's neither fully sheltered nor fully exposed. Any one of those changing - pitch, exposure, heating, occupancy - moves the real figure.

Nothing here substitutes for an address-level number. Get one free, in about a minute, from the ASCE 7 Hazard Tool using your own coordinates rather than Union County's county-wide figure. (How this figure is calculated.)