O'Brien County, IA Roof Snow Load - 24.5 psf
O'Brien County, IA: your roof's ASCE 7 snow number, in plain English
O'Brien County's roofs are built to hold 24.5 psf of snow, the ASCE 7-22 figure a permit reviewer checks first.
In depth, not weight: that's roughly 53.9 inches of fresh, light snow, 19.6 inches of old, settled snow, or as little as 4.9 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. 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.
O'Brien County at a glance
- Design roof snow load24.5 psf
- Ground snow load, ASCE 7 map35 psf
- National rank#350 of 2,758
- Iowa rank#17 of 99
- Population14,260
- Annual snowfall, NOAA normal41.4 in.
- FIPS19141
O'Brien County by the numbers
Nationally that's #350 out of 2,758 rated counties, the top 13%; within Iowa alone, O'Brien County ranks #17 of 99. Iowa counties average 21.7 psf; O'Brien County runs 2.8 psf higher than that.
O'Brien County, FIPS 19141, is home to 14,260 people near 43.0837°N 95.6256°W. Its 35 psf ground snow load figure is the map value; 24.5 psf is what a roof is actually designed for.
O'Brien County's snowfall, most winters
41.4 in. a year: that's O'Brien County's NOAA 1991-2020 snowfall normal, measured at SANBORN, IA US (6.8 mi away). See the density guide.
Before you rely on O'Brien County's number
Treat the O'Brien 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.