Polk County, IA Roof Snow Load - 20 psf
How much snow is too much for a roof in Polk County, IA?
20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Polk County to carry. 17.5 psf is what the ground-load formula alone gives; Polk County's 20 psf low-slope minimum (§7.3.4) beats it, so that figure is the one that governs on flat and low-pitch roofs.
Picture it, not just weigh it: 44 in. if it's fresh powder, 16 in. once it settles, or a mere 4 in. if it's ice. 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.
Got real snow on a Polk County roof right now?
Polk County, IA: quick facts
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#542 of 2,758
- Iowa rank#43 of 99
- Population516,185
- Annual snowfall, NOAA normal24.7 in.
- FIPS19153
How Polk County compares
20 psf ranks #542 of 2,758 US counties with a mapped snow load (top 20%) - and #43 of 99 in Iowa. Iowa counties average 21.7 psf; Polk County runs 1.7 psf lower than that.
Population 516,185 (FIPS 19153), roughly 41.6848°N 93.569°W. The 25 psf ground snow load ASCE 7-22 maps here becomes 20 psf once the code's own design factors are applied.
Typical snowfall in Polk County, IA
NOAA's 30-year normal for Polk County: 24.7 in. of snow a year, from the ANKENY, IA US station. (fresh vs. packed vs. ice explains why.)
What this Polk County figure assumes
This is a county-level reference figure for a typical heated home built to Risk Category II (ordinary residential), on a partially exposed lot - the assumptions ASCE 7-22 itself treats as the default case. A steeper roof, a fully exposed hilltop lot, an unheated structure, or a higher risk category all change the actual number.
Polk County's permit office wants an address-specific figure, not this county average - the ASCE 7 Hazard Tool is free, takes under a minute, and outputs a PDF most reviewers accept. Details: the calculation guide.