DeKalb County, IL Roof Snow Load - 20 psf
What ASCE 7 says about snow load in DeKalb County
That's DeKalb County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from. §7.3.4's low-slope minimum of 20 psf is what actually governs on a flat or low-pitch roof here - higher than the 17.5 psf the base ground-load formula gives.
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. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.
DeKalb County at a glance
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#651 of 2,758
- Illinois rank#19 of 102
- Population101,335
- Annual snowfall, NOAA normal33.1 in.
- FIPS17037
Where DeKalb County's figure sits nationally
Out of 2,758 rated US counties, DeKalb County sits at #651, the top 24% nationally - #19 of 102 within Illinois. Illinois counties average 19.3 psf; DeKalb County runs 0.7 psf higher than that.
Near 41.8946°N 88.7689°W, FIPS 17037: DeKalb County counts 101,335 residents and a 25 psf map value, which the code's own factors turn into 20 psf.
How much it actually snows in DeKalb County
Most winters bring DeKalb County roughly 33.1 in. of snow - NOAA's normal at DE KALB, IL US, 2.8 mi off. (fresh vs. packed vs. ice explains why.)
Read this before you rely on it
DeKalb 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 DeKalb County's county-wide figure. See the methodology guide.