SnowLoadCheck

Carroll County, IA Roof Snow Load - 20 psf

Carroll County, IA: your roof's ASCE 7 snow number, in plain English

Moderate
20 psf

Carroll County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. 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.

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. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.

Carroll County, IA: quick facts

Carroll County by the numbers

Nationally that's #956 out of 2,758 rated counties, the top 35%; within Iowa alone, Carroll County ranks #64 of 99. Iowa counties average 21.7 psf; Carroll County runs 1.7 psf lower than that.

Carroll County, FIPS 19027, is home to 20,407 people near 42.0395°N 94.8676°W. Its 25 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.

Carroll County's snowfall, most winters

34.5 in. a year: that's Carroll County's NOAA 1991-2020 snowfall normal, measured at DENISON, IA US (23.7 mi away). See the density guide.

Before you rely on Carroll County's number

Treat the Carroll 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. (How this figure is calculated.)