Clay County, IL Roof Snow Load - 20 psf
What ASCE 7 says about snow load in Clay County
That's Clay County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from. The physics-based figure alone would be 14 psf, but ASCE 7's own low-slope minimum (§7.3.4) sets a floor of 20 psf for flat and low-pitch roofs here, which is the number that actually governs.
Converted to something you can actually eyeball on a roof: about 44 in. of fresh powder, 16 in. once it settles and packs down, or just 4 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.
Clay County in numbers
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#1,060 of 2,758
- Illinois rank#72 of 102
- Population12,821
- Annual snowfall, NOAA normal8.3 in.
- FIPS17025
Where Clay County's figure sits nationally
Out of 2,758 rated US counties, Clay County sits at #1,060, the top 38% nationally - #72 of 102 within Illinois. Illinois counties average 19.3 psf; Clay County runs 0.7 psf higher than that.
Near 38.7468°N 88.4823°W, FIPS 17025: Clay County counts 12,821 residents and a 20 psf map value, which the code's own factors turn into 20 psf.
How much it actually snows in Clay County
Most winters bring Clay County roughly 8.3 in. of snow - NOAA's normal at FLORA 5 NW, IL US, 5.6 mi off. (fresh vs. packed vs. ice explains why.)
Read this before you rely on it
Clay 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 Clay County's county-wide figure. See the methodology guide.