Warren County, IA Roof Snow Load - 20 psf
Warren County, IA: your roof's ASCE 7 snow number, in plain English
Warren County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. §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.
In depth, not weight: that's roughly 44 inches of fresh, light snow, 16 inches of old, settled snow, or as little as 4 inches of solid ice - snow that heavy is rare here but ice from a freeze-thaw cycle adds up far faster than the depth suggests. 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.
Warren County in numbers
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#714 of 2,758
- Iowa rank#50 of 99
- Population56,343
- Annual snowfall, NOAA normal30.8 in.
- FIPS19181
Warren County by the numbers
Nationally that's #714 out of 2,758 rated counties, the top 26%; within Iowa alone, Warren County ranks #50 of 99. 21.7 psf is Iowa's typical county figure - Warren County comes in 1.7 psf under it.
Warren County, FIPS 19181, is home to 56,343 people near 41.3324°N 93.5688°W. Its 20 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.
Warren County's snowfall, most winters
30.8 in. a year: that's Warren County's NOAA 1991-2020 snowfall normal, measured at INDIANOLA 2W, IA US (4.7 mi away). See the density guide.
Before you rely on Warren County's number
Treat the Warren County figure as a starting point, not a final answer: it assumes standard occupancy, a heated structure and a moderately sheltered site, per ASCE 7-22's own defaults. Exposed terrain, an unheated building or a steeper roof all shift the real number.
For a real application, skip the county number and go straight to the ASCE 7 Hazard Tool - enter your coordinates and it returns a site-specific figure a plan reviewer will recognize. See the methodology guide.