Tazewell County, IL Roof Snow Load - 20 psf
Tazewell County, IL roof snow load, translated
A typical heated home in Tazewell County is designed to carry 20 pounds per square foot of snow on its roof, per ASCE 7-22. §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 14 psf the base ground-load formula gives.
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.
Tazewell County, IL: quick facts
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#628 of 2,758
- Illinois rank#16 of 102
- Population129,821
- Annual snowfall, NOAA normal24.4 in.
- FIPS17179
Where Tazewell County ranks
#16 of 102 Illinois counties by design load, top 23% of 2,758 nationally - that's Tazewell County's spot. That's 0.7 psf above Illinois's own county-average design load of 19.3 psf.
FIPS 17179, population 129,821, centered near 40.5081°N 89.5163°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.
Tazewell County: average annual snowfall
Tazewell County sees about 24.4 in. of snow most winters, per the MACKINAW 3WSW, IL US station's 1991-2020 NOAA normal. See the density guide.
Read this before you use Tazewell 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. Details: the calculation guide.