Jo Daviess County, IL Roof Snow Load - 20 psf
What ASCE 7 says about snow load in Jo Daviess County
That's Jo Daviess 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 20 psf - higher than the 17.5 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 44 in. of fresh powder, 16 in. once it settles and packs down, or just 4 in. if it's turned to ice. This is a meaningful design load - most modern-code homes handle it fine, though an addition, a carport or a flat-roofed section can be a weak spot.
Jo Daviess County at a glance
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#939 of 2,758
- Illinois rank#49 of 102
- Population21,528
- Annual snowfall, NOAA normal30.2 in.
- FIPS17085
Where Jo Daviess County's figure sits nationally
Out of 2,758 rated US counties, Jo Daviess County sits at #939, the top 34% nationally - #49 of 102 within Illinois. That's 0.7 psf above Illinois's own county-average design load of 19.3 psf.
Near 42.3624°N 90.2115°W, FIPS 17085: Jo Daviess County counts 21,528 residents and a 25 psf map value, which the code's own factors turn into 20 psf.
How much it actually snows in Jo Daviess County
Most winters bring Jo Daviess County roughly 30.2 in. of snow - NOAA's normal at ELIZABETH, IL US, 3.3 mi off. (fresh vs. packed vs. ice explains why.)
Read this before you rely on it
Jo Daviess 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 Jo Daviess County's county-wide figure. (How this figure is calculated.)