Des Moines County, IA Roof Snow Load - 20 psf
How much snow is too much for a roof in Des Moines County, IA?
20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Des Moines County to carry. 14 psf is what the ground-load formula alone gives; Des Moines 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.
Des Moines County in numbers
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#791 of 2,758
- Iowa rank#54 of 99
- Population38,411
- Annual snowfall, NOAA normal21.8 in.
- FIPS19057
How Des Moines County compares
20 psf ranks #791 of 2,758 US counties with a mapped snow load (top 29%) - and #54 of 99 in Iowa. 21.7 psf is Iowa's typical county figure - Des Moines County comes in 1.7 psf under it.
Population 38,411 (FIPS 19057), roughly 40.9153°N 91.1869°W. The 20 psf ground snow load ASCE 7-22 maps here becomes 20 psf once the code's own design factors are applied.
Typical snowfall in Des Moines County, IA
NOAA's 30-year normal for Des Moines County: 21.8 in. of snow a year, from the BURLINGTON 2S, IA US station. (fresh vs. packed vs. ice explains why.)
What this Des Moines 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.
Des Moines 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. (How this figure is calculated.)